Professional Paper No. 16 Series 0, Systematic Geology and Paleontology, 63 

DEPARTMENT OF THE INTERIOR 


UNITED STATES GEOLOGICAL SURVEY 


CHARLES 1). WALCOTT, DIRECTOR 

C MIONIFEROUS FORMATIONS AND FAUNAS 


OF 

COLORADO 

BY 

GEORGE H. G-IIITT-Y. 

WASHINGTON 


GOVERNMENT PRINTING OFFICE 


1903 
Library Copy 

PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY. 

[Professional Paper No. 16.] 

The serial publications of tb e United States Geological Survey consist of (1) Annual Reports, 

(2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Mineral Resources, (6) Water-Supply 

and Irrigation Papers, (7) Topographic Atlas of the United States-folios and separate sheets 

thereof, (8) Geologic Atlas of the United States-folios thereof. The classes numbered 2, 7, and 8 

are sold at cost of publication; the others are distributed free. A circular giving complete lists may 

be had on application. 

The Bulletins, Professional Papers, and Water-Supply Papers treat of a variety of subjects, and 

the total number issued is large. They have therefore been classified into the following series: A, 

Economic geology; B, Descriptive geology; C, Systematic geology and paleontology; D, Petrography 

and mineralogy; E, Chemistry and physics; F, Geography; G, Miscellaneous; Ti, Forestry; I, Irrigation; J, Water storage; K, Pumping water; L, Quality of water; M, General hydrographic investigations; N, Water power; 0, Underground waters; P, Hydrographic progress reports. This bulletin 

is the sixty-third in Series C, the complete list of which follows. (B=Bulletin, PP=Professional 

Paper.) 

SERIES C, SYSTEMATIC GEOLOGY AND PALEONTOLOGY. 

B 3. Fossil faunas of Upper Devonian, along the meridian 76° 30', from Tompkins County, New York, to Bradford 

County, Pennsylvania, by H. S. Williams. 1884. 36 pp. 

B 4. Mesozoic fossils, by C. A. White. 1884. 36 pp., 9 pls. 

B 10. Cambrian faunas of North America. Preliminary studies, by C. D. Walcott. 1884. 74 pp., 10 pls. (Out of stock.) 

B 11. Quaternary and recent mollusea of the Great Basin, with descriptions of new forms, by R. Ellsworth Call. Intro. 

duce by a sketch of the Quaternary lakes of the Great Basin, by G. K. Gilbert. 1884. 66 pp., 6 pls. 

B 15. Mesozoic and Cenozoic paleontology of California, by C. A. White. 1885. 33 pp. 

B 16. Higher Devonian faunas of Ontario County, New York, by J. M. Clarke. 1885. 86 pp., 3 pls. 

B 18. Marine Eocene, fresh-water Miocene, and other fossil Mollusca of western North America, by C. A. White. 1885 

26 pp., 3 pls. 

B 19. Notes on the stratigraphy of California, by G. F. Becker. 1885. 28 pp. (Out of stock.) • 

B 22. New Cretaceous fossils from California, by C. A. White. 1885. 25 pp., 5 pls. 

B 24. List of marine Mollusca, comprising the Quaternary fossils and Recent forms from American localities between 

Cape Hatteras and Cape Roque, including the Bermudas, by. W. H. Dall. 1885. 336 pp. 

B 29. Fresh-water invertebrates of the North American Jurassic, by C. A. White. 41 pp., 4 pis. 

B 30. Second contribution to the studies on the Cambrian faunas of North America, by C. D. Walcott. 1886. 369 pp., 

33 pls. (Out of stock.) 

B 31. Systematic review of our present knowledge of fossil insects, including myriapods and arachnids by S. H. Scudder.. 

1886. 128 pp. 

B 34. Relation of the Laramie molluscan fauna to that of the succeeding fresh-water Eocene and other groups, by C. A. 

White. 1886. 54 pp., 5 pls. 

B 37 Types of the Laramie flora, by L. F. Ward. 1887. 354 pp., 57 pls. 

B 41. Fossil faunas of the Upper Devonian-the Genesee section, New York, by H. S. Williams. 1887. 121 pp., 4 pls. 

B Tertiary and Cretaceous strata of the Tuscaloosa, Tombigbee, and Alabama rivers, by E. A. Smith and L. C. Johnson. 

1887. 189 pp., 21 pls. 

B 51. Invertebrate fossils from the Pacific coast, by C. A. White. 1889. 102 pp., 14 pls. (Out of stock.) 

B 56. Fossil wood and lignite of the Potomac formation, by F. H. Knowlton. 1889. 72 pp., '7 pls. 

B 63. Bibliography of Paleozoic Crustacea from 1698 to 1889, including a list of North American species, and a systematic 

arrangement of genera, by A. W. Vogdes. 1890. 177 pp. 

B 69. Classed and annotated bibliography of fossil insects, by S. H. Scudder. 1890. 101 pp. 

B 71. Index •to known fossil insects of the world, including myriapods and arachnids, by S. H. Scudder. 1891. 744 pp. 
II 
ADVERTISEMENT. 

B 77. The Texan Permian and its Mesozoic types of fossils, by C. A. White. 1891. 51 pp., 4 pls. 

B 80. Correlation papers-Devonian and Carboniferous, by H. S. Williams. 1891. 279 pp. 

B 81. Correlation papers-Cambrian, by C. D. Walcott. 1891. 447 pp., 3 pls. (Out of stock.) 

B 82. Correlation papers-Cretaceous, by C. A. White. 1891. 273 pp., 3 pls. 

B 83. Correlation papers-Eocene, by W. B. Clark. 1891. 173 pp., 2 pls. 

B 84. Correlation papers-Neocene, by W. H. Da11 and G. D. Harris. 1892. 349 pp., 3 pls. 

B 85. Correlation papers-The Newark system, by I. C. Russell. 1892. 344 pp., 13 pls. (Out of stock.) 

B 86. Correlation papers-Archean and Algonkian, by C. R. Van Hise. 1892. 549 pp., 12 pls. (Out of stock.) 

B 87. Synopsis of American fossil Brachiopoda, including bibliography and synonymy, by Charles Schuchert. 1897. 

464 pp. 

B 88. Cretaceous foraminifera of New Jersey, by R. M. Bagg, jr. 1898. 89 pp., 6 pls. 

B 93. Some insects of special interest from Florissant, Colo., and other points in the Tertiaries of Colorado and Utah, by 

S. H. Scudder. 1892. 35 pp., 3 pls. 

B 97. Mesozoic Echinodermata of the United States, by W. B. Clark. 1893. 207 pp., 50 pls. 

B 98. Flora of the outlying Carboniferous basins of southwestern Missouri, by David White. 1893. 139 pp., 5 pls. 

B 101. Insect fauna of the Rhode Island coal field, by S. H. Scudder. 1893. 27 pp., 2 pls. • 

B 102. Catalogue and bibliography of North American Mesozoic invertebrata, by C. B. Boyle. 1893. 315 pp. 

B 105. The Laramie and the overlying Livingston formation in Montana, by W. H. Weed, with report on Flora, by F. H. 

Knowlton. 1893. 68 pp., 6 pls. 

B 106. Colorado formation and its invertebrate fauna, by T. W. Stanton.. 1893. 288 pp., 45 pls. (Out of stock.) 

B 110. Paleozoic section in the vicinity of Three Forks, Mont., by A. C. Peale. 1893. 56 pp., 6 pls. 

B 120. Devonian system of eastern Pennsylvania and New York, by C. S. Prosser. 1895. 81 pp., 2 pls. 

B 121. Bibliography of North American paleontology, by C. R. Keyes. 1894. 251 pp. 

B 124. Revision of North American fossil cockroaches, by S. H. Scudder. 1895. 176 pp., 12 pls. 

B 128. Bear River formation and its characteristic fauna, by C. A. White. 1895. 108 pp., 11 pls. 

B 133. Contributions to the Cretaceous paleontology of the Pacific coast: The fauna of the Knoxville beds, by T. W. 

Stanton. 1895. 132 pp., 20 pls. 

B 134. Cambrian rocks of Pennsylvania, by C. D. Walcott. 1896. 43 pp., 15 pls. 

B 141. Eocene deposits o the Middle Atlantic slope in Delaware, Maryland, and Virginia, by W. B. Clark. 1896. 167 pp., 

40 pls. 

B 142. Brief contribution to the geology and paleontology of northwestern Louisiana, by T. W. Vaughan. 1896. 65 pp., 

4 pls. 

B 145. Potomac formation in Virginia, by W. M. Fontaine. 1896. 149 pp., 2 pls. 

B 151. Lower Cretaceous gryphEeas of the Texas region, by R. T. Hill and T. W. Vaughan. 1898. 139 pp., 35 pls. 

B 152. Catalogue of Cretaceous and Tertiary plants of North America, by F. II. Knowlton. 1898. 247 pp. 

B 153. Bibliographic index of North American Carboniferous invertebrates, by Stuart Weller. 1898. 653 pp. 

B 163. Flora of the Montana formation, by. F. H. Knowlton. 1900. 118 pp., 19 pls. 

B 173. Synopsis of American fossil Bryozoa, including bibliography and synonymy, by J. M. Nickles and R. S. Ba,ssler. 

1900. 663 pp. 

B 179. Bibliography and catalogue of fossil vertebrata of North America, by 0. P. Hay. 1902. 868 pp. 

B 191. North American geologic formation names: Bibliography, synonymy, and distribution, by F. B. Weeks. 1902. 

448 pp. 

B 195. Structural details in the Green Mountain region and in eastern New York (second paper) by T. NelsOn Dale. 1902. 

22 pp., 4 pls. 

B 204. Fossil flora of the John Day Basin, Oregon, by F. H. Knowlton. 1902. 153 pp., 17 pls. 

B 205. The Mollusca of the Buda limestone, by G. B. Shattuck, with an appendix on the Corals of the Buda limestone, by 

T. W. Vaughan. 1903. 94 pp., 27 pls. 

B 206. A study of the fauna of the Hamilton formation of the Cayuga Lake section in central New York, by H. F. Cleland. 

1903. 112 pp., 5 pls. 

B 210. The correlation of geological faunas; a contribution to Devonian paleontology, by H. S. Williams. 1903. 147 pp.,,1 p1. 

B 211. Stratigraphy and paleontology of the Upper Carboniferous rocks of the Kansas section, by G. I. Adams, G. H. Girty, 

and David White. 1903. 123 pp., 4 pls. 

PP16. Carboniferous formations and faunas of Colorado, by G. H. Girty. 1903. 546 pp., 10 pls. 
LIBRARY CATALOGUE SLIPS. 

[Mount each slip upon a separate card, placing the subject at the top 

Of the second slip. The name of the series should not be repeated 

on the series card, but add the subsequent numbers, as received, to 

the first entry.] 

Girty, George H. 

. . The Carboniferous formations and faunas 

of Colorado, by George H. Ginty. Washington, 

Gov't print. off., 1903. 

546, III p. 10 pl. 24 x 23ein. (U. S. Geological survey. Professional paper no. 16. ) 

" Bibliography " : p. 10-26. 

Subject series C, Systematic geology and paleontology, 63. 

Girty, George H. 

. . . The Carboniferous formations and faunas 

of Colorado, by George H. Girty. Washington, 

Gov't print. off., 1903. 

• 

• 

546, III p. 10 pl. 29i x 23cm. (U. S. Geological survey. Professional paper no. 16. ) 

"Bibliography " : p. 10-26. 

Subject series C, Systematic geology and paleontology, 63. 

U. S. Geological survey. 

Professional papers. 

no. 16. Girty, G. H. The Carboniferous forma- t tions and faunas of Colorado. 1903. 

U. S. Dept. of the Interior. 

$5<2 see also 

4 U. S. Geological survey. 

III 

CONTENTS. 

Page. 

Introduction 7 


Bibliography 10 


Resum6 of literature and classification of areas 27 


Uinta Mountain region 28 


Grand River region 51 


Elk Mountain region 69 


South Park region 78 


Sangre de Cristo region 


Front Range region 97 


San Juan region 122 


Dolores River region 132 


Recapitulation of Paleozoic formations 139 


Cambrian 140 


Ordovician 147 


Silurian 156 


Devonian? r 156 


Devonian 161 


Carboniferous 162 


Mississippian 162 


Pennsylvanian 170 


Faunal evidence and correlation 217 


Mississippian 217 


San Juan region 218 


Crested Butte quadrangle 219 


Aspen district 220 


Leadville region 221 


Salida 224 


Canyon 224 


Pikes Peak quadrangle 225 


Perry Park 226 


Larimer County 226 


Summary 228 


Pennsylvanian 231 


Uinta Mountain region 231 


• 	 Grand River region 232 


Elk Mountain region 235 


South Park region 239 

4 CONTENTS. 

Faunal evidence and correlation—Continued. 


Pennsylvanian—Continued. Page. 


San Juan region 245 


Ouray 256 


Dolores River region 257 


Summary 258 


Descriptions of species 268 


Mississippian 269 


Pennsylvanian 317 


Plates. 
 481 


Register of localities 519 


Index 
 533 
ILLUSTRATIONS. 

Page. 

PLATE I. Figs. 1 and 2, Menophyllum ulrichanum; figs. 3 and 4, Spiriferina solidirostris; fig. 5, 

Seminula subquadrata'; figs. 6 and 7, Cran,wna subelliptica; figs. 8-10, Cranwna subel 

liptica var hardingensis; figs. 11 and 11a, Eumetria woosteri; fig. 12, Myalina keokuk; 

fig. 13, Streblopteria media; fig. 14, Archwocidaris ourayensis; fig. 15, Prismopora trian 

gulata; figs. 16 and 16a, Orthotichia schuchertensis; figs. 17-18, Chonetes flemingi; figs. 

19 and 19a, Chonetes geinitzianus; figs. 20-23, Chonetes mesolobus � 484 

II. Productus semireticulatus var hermosanus� 488

III. 	 Figs. 1-3, Productta inflatus; figs. 4-8a, Productus gallatinensis; figs. 9-11, Productus 

sp. b 490 

IV. Productus cora 	 494 

V. Figs. 1-2a, Productus nebraskensis; fig. 3, Productus sp. a; figs. 4 and 4a, Marginifera 

lasallensis; figs. 5-7, Marginifera muricata; figs. 8 and 8a, Marginifera wabashensis 

var.; figs. 9-11a, Marginifera haydenensis; figs. 12-13b, Marginifera ingrates 496 

VI. Figs. 1-3, Spirifer boonensis ?; figs. 4-7c, Spirifer rockymontanus; figs. 8-10a, Squamularia perplexa; figs. 11-11c, Spiriferina kentuckyensis � 500 

VII. Figs. 1-10, Seminula subtilita; figs. 11 and 11a, Dielasma bovidens; figs. 12 and 13, Hustedia 

mormoni; figs. 14-14b, Pugnax utah� 504 

VIII. Fig. 1, Aviculopecten occidentalis; fig. 2, Aviculopecten sp. a; fig. 3, Aviculopecten? 

interlineatus; fig. 4, Pseudomonotis kansasensis; fig. 5, Pseudomonotis equistriata; figs. 

6 and 7, Myalina subquadrata; figs. 8-13, Myalina wyomingensis; figs. 14-17, Myalina 

cuneiformis � 508 

IX. Figs. 1 and 2, Aviculopecten nebraskensis; fig. 3, Monopteria alata; figs. 4-6, Allerisma 

terminate; figs. 7-9, Edmondia gibbosa; fig. 10, Schizodus cuneatus; figs. 11 and 12, 

Pleurophorus subcostatus� 512 

X. 	 Figs. 1-2a, 

phostylus remex; 

Platyceras parvum; 

figs. 6-7a, Bulimorpha chrysalis; fig. 

figs. 3 and 3a, Strophostylus subovatus?; 

8, Loxenemar peoriense; 

figs. 4-5b, Strofigs. 9 

and 9a, Euconispira taggarti; figs. 10-10b, Patellostium ourayense; figs. 11 and 12, 

Phillipsia trinucleata � 516 

THE CARBONIFEROUS FORMATIONS AND FAUNAS OF 

COLORADO. 

By GEORGE H. GIRTY. 

INTRODUCTION. 

In the following pages the geology and paleontology of the Carboniferous rocks 

of Colorado are discussed from the viewpoint of the stratigraphic paleontologist. 

This viewpoint is also that of one not personally acquainted with the field in question, 

except in very small measure. I made or assisted in making a few collections of 

fossils, and enjoyed the privilege of being connected for a month with a field party 

under the charge of Mr. Whitman Cross during the season of 1900. Most of the 

extensive collections which I have studied are the work of others, and the strata, in 

their characters and mutual attitudes, have been viewed only through the pages of 

geologic reports. The tendencies of my work are almost exclusively toward the 

historical geology, for from the nature of the case, even had I wished, it would have 

been difficult to dealwith the structural or economic phases of the. subject. 

The paleontologic data for this work reside in a rather extensive collection from 

200 localities, representing the available .resources of the Geological Survey and the 

National Museum in the matter of Colorado Carboniferous fossils. In the paleontologic discussion the purpose has been not so much to see what or how many species 

occurred within, the limits of Colorado as to ascertain their grouping into local and 

formational faunas, and to determine, if possible, by means of the invertebrate fossils, 

the relation to one another of the strata forming the different more or less disconnected and isolated areas of Carboniferous outcrop. Aside from such correlative 

indications as the study of these collections has furnished, a fact of some interest, 

though by no means for the first time brought to notice, is the close relation which 

evidently existed in Carboniferous time between the Colorado seas and those of the 

Mississippi Valley. Almost the entirety of the numerous fauna recognized in 

Colorado occurs also in the coal fields of the Ohio and Mississippi valleys, and it has 

been found necessary to describe but very few species as new. 

7 
CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In a work which has suffered from so frequent and so prolonged interruptions 

as this, giving opportunity for many changes of opinion—one, too, in which facts are 

involved so many and so variously related—I can hardly expect to have escaped 

errors and inconsistencies. The hope is entertained that they will not detract too 

much from what value this work would otherwise have had. The task proposed has 

been found a difficult one, appreciation of its magnitude growing as investigations 

into literature and faunas progressed. It has proired, indeed, that the points in 

relation to which a demonstration was possible are few, and not, perhaps, very 

important. The facts are not at hand to determine many of the questions which 

have arisen at different points of my investigations. I have permitted myself, however, to frame a number of hypotheses, and to suggest a number of possibilities. It 

would indeed be gratifying to think that in this way the solution of problems 

whose answers have eluded me has in any measure been facilitated. 

It seems desirable to offer a few words of explanation, or it may be of excuse, for 

several omissions and commissions in the following pages that may be considered 

serious enough to excite criticism. One license which I have permitted myself is 

the equalization, for purposes of convenience and simplicity, of zoological groups 

whose unequal importance is generally recognized. That the difference is of so 

general recognition is perhaps the greater excuse for this lax usage, this concession 

to convenience. I refer at present especially to the placing of the Bryozoa and 

Brachiopoda and the several divisions of the true Mollusca upon a temporary parity 

with the Protozoa, the sponges, and the other groups having the rank of classes. This 

arrangement has been observed in the tables and in the discussion of species, and is 

one which the paleontologist is almost certain to make, mentally at least, in studying 

a varied fauna. It amounts, in short, to breaking up the larger and more unwieldy 

groups into recognized subdivisions, from which the master titles are omitted. A 

slightly different practice is that of the constant use of subgeneric names in a titularly generic sense. For convenience and brevity, each subgenus has been written 

free, as if it were an independent genus; an indulgence from which I would certainly 

have abstained had this work been planned upon systematic or biologic lines. 

Many are the names which would be mentioned if all were to be set down to whom 

recognition is due for assistance, great and small, in the preparation of this paper. 

First, perhaps, should be mentioned the geologists, Messrs. Cross, Spencer, Eldridge, 

Emmons, Lee, and others, through whose accumulation of material my work was, 

not only made possible but even suggested. Acknowledgments are due also to the 

Museum of Cliicago University, from which, through Mr. Stuart Weller, I have 

enjoyed the privilege of examining and illustrating some specimens importantly 

connected with my subject. I have consulted freely with my colleagues, Mr. 

Schuchert, Mr. Ulrich, and Mr. Bassler, upon paleontologia whenever occasion has 
INTRODUCTION. 9 

required, and profited frequently by their advice. Mr. Stanton and Mr. Cross have 

also been consulted upon points connected with the general plan and its execution, 

and to them and others some of the more far-reaching considerations touched upon 

have been referred. My acknowledgments should not, however, be brought to a 

close without an expression of thanks to Miss Frances Wieser and Miss Mary 

Mitchell, who have executed the drawings by which the paleontologic portion of this 

work is illustrated. 
BIBLIOGRAPHY. 

In the bibliography to follow I have endeavored to include all papers which 

contain information about the Paleozoic, and especially the Carboniferous, rocks of 

Colorado. It would be hard to overestimate the service which the general bibliographic works on .Amer'_ean geology compiled by N. H. Darton and by F. B. Weeks 

have rendered in this effort. Without them it would have been practically impossible 

to attain the completeness now reached with comparative ease. 

The bibliography as it now stands includes nearly 140 entries, all of which have 

been examined with greater or less care, as occasion seemed to demand. Only a 

comparatively few of these, however, were found to contain matter which it is 

necessary to bring into discussion. On the other hand, the works included in the 

bibliography form but a small portion of those more hastily examined in the search 

for matter relating to the subject in hand. Selection was frequently not easy and 

may not always have been made with discernment and uniformity. Many works, of 

which the very early accounts of travel form one class and the briefer papers of an 

economic nature another, touch so lightly upon the stratigraphic and historical sides 

of the geologic question that it really seems to matter little whether they are 

included or not. They 6,-,Ldom contribute much, still less often anything different or 

new, to the subject. I endeavored to select from this material in a uniform manner. 

If failure has arisen it has been not through any wish, but through an inability, 

to select impartially. 

The earliest publications seen by me in which rocks of Carboniferous age are 

reported in Colorado are two geologic maps of the United States, one by 

Hitchcock, the other by Marcou. Both appeared in 1853. Marcou colors in a small 

area of Mountain limestone in the northern part of the State. Hitchcock represents 

three areas of Coal Measure rocks, one having somewhat the position of that drawn 

by Marcou, another apparently occupying somewhat the position of the San Juan 

Mountains, while a third appears to be situated about where lies the Sangre de Cristo 

Range. As has long beon known, Marcou's Mountain limestone in the West is for 

the most part really Upper Carboniferous, so that for the State of Colorado 

Hitchcock's map is rather more accurate than Marcou's, but geologic knowledge of 

the West at that early day was so imperfect and fragmentary that neither map has 

10 
BIBLIOGRAPHY. 11 

more than a historical interest. Hitchcock's map went through several editions 

without change; Marcou's was republished a number of times and frequently altered. 

Perhaps its best form is that which accompanied his Geology of North America in 

1858. These maps were the precursors of a number of similar attempts which have 

appeared from time to• time and which for the present culminate in the McGee map, 

the latest and so far the best general geologic map of the United States. Maps of 

this sort form a rather distinct but small and relatively unimportant branch of the 

literature relating to the geology of Colorado, and I have made no determined effort 

to include all of them in my bibliography. The scale to which they are drawn and 

the unequal character of the information upon which they are based, brought 

together from a variety of sources, do not permit the eras to be so subdivided or the 

divisions so represented upon the map as to be serviceable for detailed comparisons. 

They can not present the facts in the detail of the original reports which furnished 

them and which form the natural material for a bibliography. J. Marcou and J. B. 

Marcou a and C. H. Hitchcock b have published descriptions of the general geologic 

maps of the United States. 

The earliest account of actual geologic exploration in Colorado is that published 

by Schiel in 1854. Schiel traversed a large tract of country very hastily, one 

would judge, and his brief account, which in the light of later explorations contains 

nothing of geologic importance, is of only historic interest. He entered the mountains by the way of the Huerfano River, crossed the Sangre de Cristo Range, 

traversed the south-central part of the State, and passed on to Salt Lake through 

the San Juan and Wasatch mountains. He describes the lithologic character of both 

sedimentary and igneous rocks traversed on this route, which was not one best 

suited to display the Paleozoics of Colorado, but obtained no fossils from the older 

rocks of the State, and only in one instance attempted to assign any of them to a 

definite geologic period. In the Sangre de Cristo Valley he mentions as Cambrian 

(p. 123) a bluish brittle limestone associated with hard shale and sandstone. 

This is clearly not Cambrian, and if not one of the Carboniferous limestones is 

more probably of Cretaceous or Tertiary age. It, would be possible, though certainly unprofitable, by careful comparisons of lithologic character and geologic 

position, and with the aid of the maps and descriptions of later geologic work, to 

determine the formations to which many of the beds mentioned by Schiel probably 

belong, but it has not been attempted. This report was republished in its original 

form the year following (1855). 

The account of the geology of the Upper Missouri, published by Hayden in 

1863, though no longer of practical value, on account of more accurate work in the 

aU. S. Geol. Survey, Bull. No. 7, 1884. b Am. Inst. Min. Eng., Trans., vol. 15, 1887, pp. 465-488. 
12 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

same field by the same geologist and others coming after, was at the time a real and 

important contribution to the geologic literature of Colorado. This report, so far 

as it relates to this subject, deals with the formations exposed along the eastern 

margin of the Front Range. In 1868 appeared two other papers by the same author 

dealing with the same subject, which will be referred to in the resume of historical 

geology. 

Hayden's third annual report, published in 1869 and afterwards reprinted, gives 

an account of a hasty but extended trip through eastern Colorado and New Mexico, 

which is reviewed in the resume, to follow. 

In 1874 appeared the first of a series of four reports in which the geology of the 

entire State was outlined by means of reconnaissance explorations systematically 

planned. The discussion of the material contained in these reports forms one of the 

most important parts of my resume. The one which appeared in 1874 is the seventh 

of the annual reports of the Hayden survey. It contains reports by Hayden, Endlich, Peale, and Marvine. The same year saw the publication of Ruffner's report on 

the geology of the Ute country. A topographic map of a large portion of Colorado 

accompanies this report, the text of which is largely descriptive of geographic and 

other features. Brief geologic reports by F. Hawn and L. Hawn accompany it, 

dealing chiefly with the Sangre de Cristo, Elk, and San Juan mountains. This will 

be discussed in more detail below. 

In 1875 was published the third volume of the final reports of the Wheeler survey, containing a description by Stevenson of a very extensive area in central Colorado examined during the year 1873. This will be considered in detail later on: 

The same is true of a report by Cope on northwestern New Mexico, in which, however, the geology of a portion of Colorado is incidentally considered. Endlich 

discusses the mines and geology of the San Juan country, in which, though the 

sedimentary beds are not described in the text, Carboniferous limestone and Carboniferous sandstone are represented, on a map accompanying the report, in the general region of Silverton. 

In 1876 was published the eighth annual report of the Hayden survey --the 

second one dealing particularly with the geology of Colorado. It contains reports 

by Holmes, Hayden, Endlich, and Peale, all of which are considered in detail in 

the geological discussion. S. G. Williams described the geology near Canyon; 

Powell's book upon the geology of the Uinta Mountains, with a paleontologic portion by White, also appeared; and a series of maps by Gilbert, Marvine, and Howell 

were published the same year. 

In 1877 appeared the ninth annual report of the Hayden survey, containing 

papers by Holmes, Endlich, Peale, and Hayden. These, so far as they concern the 

subject in hand, are discussed in detail in the resume. The same year saw the publi-
BIBLIOGRAPHY. 13 

cation of the second volume of the Fortieth Parallel Survey by Hague and Emmons, 

setting forth the descriptive geology of the territory examined by that organization. 

Such portions of this work as relate to the Carboniferous of Colorado are discussed 

below; but the volume by Clarence King on the 'systematic geology (Vol. I), which 

was published the year following,• is more advantageous in its arrangement 

and comparisons. The brief discussion by Peale and Stevenson as to the age of the 

Rocky Mountains is included in my bibliography, because, while not directly bearing 

upon the historical geology of the Paleozoic, it deals with factors which determine 

the distribution and characteristics of sediments and faunas. 

In 1878 appeared the tenth annual report of the Hayden survey—the fourth and 

last volume dealing particularly with the geology of Colorado,. It contains reports 

by Peale, Endlich,White, and Holmes, which, so far as they pertain to my subject, 

are discussed in the resume. The same year was published the volume on systematic geology of the Fortieth Parallel Survey. In this volume King has assembled 

with industry and discussed with judgment the facts available from many sources at 

the time of his writing. The arrangement is such as to make it more convenient for 

my purpose than the individual accounts upon which it is based, and these, therefore, 

I have as a rule laid aside in favor of King's more correlated work. 

In 1879 was published a preliminary report by Stevenson on operations in Colorado and New Mexico. In Colorado the only Carboniferous area touched on is that 

on the east side of the Sangre de Cristo Range, from Spanish Peaks to Costillo Peak. 

The facts upon which this report is based are given in greater detail in a publication 

which appeared in 1881, and I have not, therefore, given it special eonsideration. The 

paper by Henrich on the ore deposits of Leadville, which appeared this year, is the 

first of the numerous series of short articles relating especially to the economic geology of this great mining camp which were published for some time preceding and 

immediately following the publication of Emmons's Leadville monograph. I will 

include these in the bibliography, but not refer to them individually. 

In 1880 Dutton issued a publication on the Permian of North America, in which 

he refers part of the Red Beds of Colorado, etc., to the Permian, the upper portion 

being Triassic. Hayden expressed somewhat the same view the same year, in 

describing the Twin Lakes and Teocalli Mountain. 

' The most important work relating to this subject which appeared in 1881 was 

Stevenson's report upon examinations in southern Colorado and northern New Mexico, a preliminary account of which was published in 1879. The only Carboniferous 

area in Colorado discussed in this paper is that along the east side of the Sangre de 

Cristo Range from Spanish Peaks to Costillo Peak. 

A paper which appeared in 1883, "Notes on the geology and mineralogy of San 

Juan County, Colo.," by T. B. Comstock, so far as it concerns my subject, is largely 
14 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

an abstract of the work of the Hayden survey, in which many of the errors committed by Endlich are repeated. Thus the early Paleozoics are described as having 

furnished the material out of which the " metamorphic series" was formed, while all 

the Upper Carboniferous beds, which were later called the Hermosa formation, are 

referred to the Lower Carboniferous. Probably, however, this term is here 

employed in the objectionable sense in which it was used by the Hayden survey--to 

indicate the lower portion of the Carboniferous section of any particular region. 

Broadhead's paper on the Juratrias, published this year, concerns us in that some of 

the strata called Juratrias in Colorado are probably Carboniferous. On the other 

hand, his paper is a summary or digest of the literature, practically without discussion, conclusion, or new matter of any sort. Of a similar bibliographic nature is T. S. 

Hunt's description of the progress of geology for 1882. It is of subsidiary interest 

to this resume as containing an abstract of the results of Emmons's Leadville work. 

A paper by Hallowell, entitled " Supposed Juratrias of the Front Range," seems to 

be an effort to prove that no Juratrias exists along the Front Range of Colorado 

and that the rocks called such actually overlie the Cretaceous. 

In 1884 little or nothing bearing upon the matter in hand was published, and in 

1885 only papers of a less important kind. In the latter year Emmons, in his report 

upon the Rocky Mountain division, calls attention to two unconformities, one preJurassic, the other intra-Carboniferous, which had not previously been detected. 

These were observed in the Elk Mountains, and were later discussed and represented 

in the Anthracite-Crested Butte folio. 

The important event of the year 1886, so far as it concerns this subject, was the 

publication of Emmons's Leadville monograph. This work will of course receive 

attention in the resume. The other publications of the year are of minor importance. 

Stevens briefly describes the geology of the San Juan region in a report which adds 

little or nothing to the Hayden survey. Emmons somewhat casually describes the 

section at Red Cliff in which the Sawatch, Yule, and Leadville formations are said to 

occur. 

In 1887 appeared a number of papers of the less important sort. Comstock 

described the geology and vein structure of a large area in southwestern Colorado in 

a paper which will be discussed later on in the resume. Olcutt described the Battle 

Mountain mining district of Eagle County, giving .the geologic section observed 

there. To one familiar with the sequence in central Colorado the Paleozoic character of these beds is clear, but the author makes no attempt to correlate them with 

other sections or to fix their geologic age. Lakes described the geology of the Aspen 

district in a paper which will be referred to later. A map of the United States by 

Hitchcock appeared this year, and to this I have already made general reference. 

Areas of Carboniferous (called Permo-Carboniferous) are shown in Colorado some-
BIBLIOGRAPHY. 15 

what as in the Hayden atlas. Tilden also describes the ore deposits at Red Cliff, and 

gives the geologic sequence occurring there. This will be mentioned separately 

below. 

In 1888 Emmons published a preliminary note on Aspen, in which the section in 

that vicinity is described and compared with the Leaklville section. As the statement 

of fact is little different from that in the Aspen monograph, by Spurr, I shall not give 

this paper special reference in the resuna4. Kedzie briefly describes the ore deposits 

and geology of the Red Mountain mining district of Ouray, and Siver and Brunton 

those of Aspen. Brunton's is an able paper, with figures of models showing topography, and a carefully considered section in which the same formations as those at Leadville appear. The Weber formation is referred to the Middle Carboniferous, and the 

upper beds of the Carboniferous are not considered. Lakes discusses the geology 

of Colorado ore deposits in a paper which was published 'in the same form in two 

places. So far as concerns my subject this paper was too general and elementary, as 

to both geology and paleontology, to require especial consideration. 

Again, in 1889 the geology and mineral 'deposits of Aspen were treated by Henrich in a carefully prepared paper, published in the Transactions of the American 

Institute of Mining Engineers. Henrich compared his section with that of Emmons 

at Leadville, and that of Lakes, published in 1887, and called attention to several 

errors made, by the latter. His section closed with the Weber shales, so called. 

White described the geology and physiography of the epstern portion of the Uinta 

Mountains in a paper whose geologic bearing is rather structural than historical. 

Eldridge described the geologic sequence in the vicinity of Denver from the Archean 

up. The lowest sedimentaries are, of course, the Red Beds, whose characters are 

given and whose age is discussed. 

In 1890 Newberry published some notes upon the geology of the Aspen mining 

district. The divisions recognized by him are the Cambrian quartzite, the Silurian 

quartzite and limestone, the Lower Carboniferous dolomite, the Lower Carboniferous 

blue limestone, the Middle Carboniferous shale and shaly limestone, the Middle Carboniferous limestone, and the Jura-Triassic sandstones. The equivalence of this 

section with that adopted by Spurr in his Aspen monograph is too obvious to need 

special discussion. Apparently Newberry's two Middle Carboniferous formations 

are the same as the Weber formation, while the Juratrias, of which there are said to 

be many hundred feet, comprises the Maroon formation and the bright-red sandstone, 

noted by Spurr in the Lenado Canyon. Emmons's paper on orographic movements 

in the Rocky Mountains is important to the subject in hand because of its bearing 

upon the disposition of land and water in Colorado during Carboniferous time and 

the relation of the Carboniferous faunas and sediments at different points in this 

State. This subject will be considered at a later place. The same author describes, 

in McFarlane's Railroad Guide, the Carboniferous of Colorado, but from the nature 
16 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

of the case the discussion is a general one. Eldridge's paper on structural features 

near Denver contains an incidental description of the TriaSsic and later beds, and an 

account of some of the peculiarities of distribution. 

A paper by Cannon in 1892 describes the geology in the vicinity of Palmer 

Lake, along the Front Range. He recognizes the absence of Paleozoics in this 

vicinity, but calls attention to the prevalence of chert bowlders, both free and in 

conglomerates, containing Paleozoic types of fossils. He concludes that they represent exposures of certain beds that have long since been eroded. It is from an occurrence similar to those recalled by Cannon that the fossils described by, White from a 

conglomerate in Larimer County were obtained. Duiing the same year appeared 

papers by Eldridge, Farish, and McMechen, which have little bearing upon my 

discussion, but are included in the bibliography. This is less true of a paper by 

C. D. Walcott, who describes the Paleozoic section at Canyon, and gives lists of 

fossils. So far as Mr. Eldridge's paper concerns us at all it embraces the same strata 

described by Walcott, whose section is mentioned particularly in my discussion. 

In 1893 G. L. Cannon described the geology of Denver and vicinity. The oldest 

sedimentary strata considered are of course the Red Beds, which he refers to the Triassic 

and Jurassic, but because they are possibly, in part, of Carboniferous age, this paper 

comes properly within my purview. The same area has been made the subject of a 

monographic study by Emmons, Cross, and Eldridge, and I will not, therefore, give 

Cannon's account further consideration. The itinerary in Colorado of the Fifth 

International Geological Congress, which took place in 1891, was arranged and 

described chiefly by S. F. Emmons and Whitman Cross, and their reports were 

published in 1893, in the Comptes Rendus of this body. They add, however, little 

or nothing to the present discussion, and it probably will not be necessary to refer 

to them again. 

In 1894 appeared the Pikes Peak and the Anthracite-Crested Butte folios (Nos. 

7 and 9 of the Geologic Atlas of the United States). The Pikes Peak folio was the 

work of Whitman Cross, who contributed to the Anthracite-Crested Butte folio 

the description of igneous rocks, while G. H. Eldridge desCribed the sedimentary 

formations, and S. F. Emmons discussed the geologic history of the Elk Mountains. 

These two volumes form important accessions to the literature which I am considering, and will receive particular discussion at a more appropriate point. 

The Geology of the Denver Basin, by Emmons, Cross, and Eldridge, in 1896, 

deals with the area about Denv.er, as the title indicates, in which strata belonging to 

the Red Beds rest directly upon the granites and metamorphics of the Front Range. 

Though this series is referred by these authors to the Triassic, the probability that 

part of it belongs to the Carboniferous has made it necessary to include this series 

and all papers relating to it in my discussion. To this monograph I will therefore 

refer in the resume of geologic literature below. 
BIBLIOGRAPHY. 17 

In 1897 appeared a number of minor articles by Lakes, Draper, Rickard, and 

others. Some of these are included in the bibliography, but require no special discussion. The Pueblo folio, by G. K. Gilbert, which was published the same year, 

receives consideration in connection with the Pikes Peak and Walsenburg folios in 

the resume. 

The Aspen monograph, by Spurr, with an introduction by S. F. Emmons, and the 

Tenmile folio, by Emmons, which were published in 1898, are two works of detailed 

and monographic character, such as have established sections at a number of points 

through the State, serving as.convenient standards of comparison with each other 

and with works which have more of the character of reconnaissance. To these it 

will he necessary frequently to refer. 

The same is true of the Walsenburg folio, by Hills, and the Geology of the Rico 

Mountains, by Cross and Spencer, which appeared in 1900. I have hesitated to 

include in the bibliography two papers by A. C. Spencer and myself, which were 

published this year. They deal with the Ouray limestone and its Devonian fauna, 

and their connection with the present subject consists in the fact that this formation 

and fauna were for a long time considered of Carboniferous age; that the Ouray limestone does, locally at least, contain a Mississippian fauna in its upper part, though this 

was not known at the time these papers were written; and that I erroneously referred 

two specimens of this Mississippian fuana to the Devonian. I shall have occasion 

several times to refer to these facts, but it will not be necessary to give special discussion to the papers themselves. 

In 1901 N. H. Darton read a paper before the Geological Society of America 

upon a comparison of the stratigraphy of the Black Hills with that of the Front 

Range of the Rocky Mountains. This paper was never published in full, but identical abstracts of it appeared in the bulletins of the society and in Science. No detail 

is naturally expected from this paper, but some interesting comparisons and correlations are made between the Front Range section and that of the Black Hills. I 

will briefly discuss this paper at a later point. Elmer S. Riggs the same year 

described the Dinosaur beds of the Grand River Valley in southwestern Colorado. 

To this paper also I shall somewhat briefly refer later on. 

In 1902 only two papers have come to hand dealing directly with the Paleozoics 

of Colorado. Both are by W. T. Lee. In one of them he describes the areal 

geology of the Castle Rock region. This paper is of interest because it describes 

one of the rare occurrences of well-defined Paleozoic strata along the eastern 

margin of the Front Range in Colorado, and I shall make special reference to it in 

my resume of geologic literature. In the other he speaks of the Carboniferous 

beds of the Sangre de Cristo Range, and to this, too, I will give further consideration. 

14364—No. 16 03 2 
18 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PUBLICATIONS DEALING WITH THE CARBONIFEROUS ROCKS OF COLORADO. 

1853. 

HITCHCOCK, EDWARD. Outline of the geology of the globe, and of the United States in particular, with 

two geological maps and sketches of characteristic American fossils, Boston, 1853; second edition, 

Boston, 1854. 

MARCOU, JULES. Geological map of the United States and British provinces of North America, with 

explanatory text and geological sections, 92 pages, 8 plates, Boston, 1853. 

Soc. geol. France, Bull., 2d series, vol. 12, pp. 813-936, map plate, under title, Resume explicatif d'une carte geologique des Etats Unis et des provinces anglaises de l'Amerique du Nord, 

avec un profil 043:lc:gigue allant de la vallee du Mississipi aux cotes du Pacifique, et une planche 

de fossiles. 

1854. 

SCHIEL, JAMES. Geological report of the country explored under the thirty-eighth and forty-first 

parallels of north latitude in 1853-54. Report of explorations for the Pacific Railroad on the 

line of the forty-first parallel of north latitude, by E. G. Beckwith, pp. 120, 8°, Washington, 

1854. 

1855. 

MARCOU, JULES. Geological map of the United States and British provinces of North America, with 

explanatory text and geological sections, 92 pages, 8 plates. Map in atlas to Voyage dans 

l'Amerique du Nord, par G. Lambert, Bruxelles, 1855. 

Geological map of the United States and British provinces of North America, with explanatory text and geological sections, 92 pages, 8 plates. Annales des Mines, vol. 7i p. 320, p1. 9. 

Ueber die Geologie der Vereinigten Staaten and der englischen Provinzen von Nord-Amerika. 

Petermann's Mitt., vol. 1, pp. 149-159, map, 4°, 1855. 

SCHIEL,.JAMES. Geological report of the country explored under the thirty-eighth and forty-first 

parallels of north latitude in 1853-54. Explorations and surveys for a railroad route from the 

Mississippi to the Pacific Ocean, vol. 2. Report, explorations for a route for the Pacific Railroad 

on the line of the forty-first parallel of north latitude, by. Lieut. E. G. Beckwith, pp. 96-112, 4°, 

Washington, 1855, Thirty-third Congress, second session, Senate Ex. Doc. No. 78. 

1858. 

MARCOU, JULES. Geological map of the United States and British provinces of North America, with 

explanatory text and geological sections, 92 pages, 8 plates. Geology of North America, 4°, 

Zurich, 1858. 

1862. 

HAYDEN, F. V. On the geology and natural history of the Upper Missouri, being the substance of a 

report made to G. K. Warren. 218 pages, map, 4°, Philadelphia, 1862. 

1863. • HAYDEN, F. V. On the geology and natural history of the Upper Missouri, being the substance of a 

report to G. K. Warren. American Phil. Soc., Trans., vol. 12, new series, pp. 1-219, map, 4°, 1863. 

1867. 

MARCOU, JULES. Geological map of the United States and British provinces of North America, with 

explanatory text and geological sections, 92 pages, 8 plates. "La vie souterraine, ou les mines 

et mineurs," par L. Simonin, plates 10, 11, 14, 4°, Paris, 1867. 
BIBLIOGRAPHY. 19 

1868. 


HAYDEN, F. V. Remarks on the geological formations along the eastern margins of the Rocky 

Mountains. Am. Jour. Sci., 2d ser., vol. 45, pp. 322-326, 1868. 

Notes on the geology of Wyoming and Colorado, No. 1. American Phil. Soc., Proc., vol. 10, 

pp. 463-478. 

1869. 

REPORT of the U. S. geological survey of Colorado and New Mexico, under F: V. Hayden, 3d Annual 

Report, pp. 1-99. Washington, 1869. 

Reprinted with first and second Annual Reports, Washington, 1870; pp. 103-199 of reprint. 

1870. 

HAYDEN, F. V. Sun pictures of Rocky Mountain scenery, with a description of the geographical and 

geological features and some accounts of the resources of the great West [etc.], 150 pages, 

30 plates, 4°, New York, 1870. 

1871. 

MEEK, F. B. Preliminary paleontological report, consisting of lists of fossils, with descriptions , of 

some new types, etc. U. S. geological survey of Wyoming and portions of contiguous Territories, F. V. Hayden in charge, preliminary, 2d report, pp. 287-318, Washington, 1871. 

A second e ition identically the same as that of 1871 bears date 1872. 

1872. 

HAYDEN, F. V. . S. geological survey of the Territories, F. V. Hayden in charge; profiles, sections, 

and other llustrations designed to accompany the final report of the chief geologist of the 

survey, an sketched under his direction by H. W. Elliot, 65 plates, 4°, New York, 1872. 

MARCOU, JULES. Geologishe Uebersichtskarten der Erde nach Marcou. Physikalische Karten, 

Vienna, 18 2. 

1873. 

HITCHCOCK, C. H and BLAKE, W. P. Geological map of the United States. Statistics of mines and 

mining in he States and Territories west of the Rocky Mountains. Fifth Report, by R. W. 

Raymond, ashington, 1873. • 

HAYDEN, F. V. U. S. geological survey of the Territories, embracing Colorado and New Mexico, 

conducted nder the authority of the Secretary of the. Interior, by F. V. Hayden, U. S. Geologist, 

1st, 2d, an 3d Ann. Rept. U. S. Geol. Survey Terr. for years 1867, 1868, and 1869, pp. 103-251, 

Washingto , 1873. 

JONES, W. A. R port of a survey and exploration in the Uinta Mountains, Utah. U. S. Army, 

Chief of E gineers, Report for 1872, pp. 1108-1118 (Appendix AA), Washington, 1873. 

1874. 

ENDLICH, F. M. [Report of the San Luis division.] U. S. geological and geographical survey of the 

Territories, embracing Colorado, F. V. Hayden in charge, [7th] Annual Report, for 1873, pp. 

275-301, 30.-361, Washington, 1874. 

HITCHCOCK, C. H , and BLAKE, W. P. Geological map of the United States. Statistical atlas of the 

United Sta • s, based on the results of the Ninth Census, 1870, by F. A. Walker, plates 13; 14, 

folio, Was ington, 1874. 
20 CARBONIFEROUS FORMATIONt4 AND FAUNAS OF COLOR kDO. 

HAYDEN, F. V. [General report.] U. S. geological and geographical survey of the Territories, 

embracing Colorado, F. V. Hayden in charge, [7th] Annual Report, for 1873, pp. 17-82, Washington, 1874. 

MARVINE, ARCHIBALD R. [Report of Middle Park division.] U. S. geological and geographical survey of the Territories, embracing Colorado, F. V. Hayden in charge, [7th] Annual Report, for 

1873, pp. 83-192, Washington, 1874. 

PEALE, A. C. [Report of South Park division]. U. S. geological and geographical survey of the Territories, embracing Colorado, F. V. Hayden in charge, [7th] Annual Report, for 1873, pp. 193­

273, Washington, 1874. 

PROUT, HENRY G. [General description of country]. Report of a reconnaissance in the Ute country, made in 1873, by Ruffner, pp. 6-51, Forty-second Congress, first session, House Ex. Doc. 

No. 193, Washington, 1874. 

1875. 

COPE, EDWARD D. Report on the geology of that part of northwestern New Mexico examined during 

the •field season of 1874. Geographical explorations and surveys west of the one hundredth 

meridian, in charge of G. M. Wheeler, annual report. Annual Report of the Chief of Engineers, 

U. S. Army, for 1875, Appendix LL, pp. 61-97, plates, Washington, 1875. 

ENDLICH, F. M. Report on the mines and geology of the San Juan country. U. S. geological and 

geographical survey of the Territories, F. V. Hayden in charge, Bull., vol. 1, 2d series, pp. 151­

164, map, Washington, 1875. 

HITCHCOCK, C. H., and BLAKE, W. P. Geological map of the United States. Petermann's Mittheilungen, -vol. 21, plate 16, 4°, 1875. 

LOEW, OSCAR, Geological and mineralogical report on portions of Colorado and New Mexico. Geographical explorations and surveys west of the one hundredth meridian, in charge of G. M. 

Wheeler, annual report. Annual Report of the Chief of Engineers for 1875, Appendix LL, 

pp. 97-416, Washington, 1875. 

Lieut. G. M. Wheeler's zweite Expedition nach Neu-Mexiko und. Colorado, 1874. Petermann's Mittheilungen, vol. 21, pp. 441-454, 4°, 1875. (Continued in 1876.) 

STEVENSON, JOHN J. Geology of a portion of Colorado explored and surveyed in 1873. Geological 

and geographical exploration and surveys west of the one hundredth meridian, in charge of 

G. M. Wheeler. Report, vol. 3, geology, pp. 303-501, 4°, Washington, 1875. 

1876. 

ENDLICH, F. M. [Report as geologist of San Juan division]. U. S. geological and geographical survey 

of the Territories, embracing Colorado and parts of adjacent Territories, F. V. Hayden in charge, 

[8th] Annual Report, for 1874, pp. 181-240, Washington, 1876. 

HAYDEN, F. V. [General report.] U. S. geological and geographical survey of the Territories, 

embracing Colorado and parts of adjacent Territories, F. V. Hayden in charge, [8th] Annual 

Report, for 1874, pp. 19-58, plates, Washington, 1876. 

HITCHCOCK, C. H., and BLAKE, W. P. Geological map of the United States. Special report of 

Smithsonian Institution for the Centennial, Washington, 1876. 

HoLmm, W. H. Report on the northwestern portion of the Elk Range. U. S. geological and geographical survey of the Territories, embracing Colorado and parts of adjacent Territories, F. V. 

Hayden in charge, [8th] Annual Report, for 1874, pp. 59-71, Washington, 1876. 

LOEW, OSCAR. Lieut. G. M. Wheeler's zweite Expedition nach Neu-Mexiko und Colorado, 1874. 

Petermann's Mitt., vol. 22, pp. 209-217, maps 12, 4°, 1876. (Continued from 1875. ) 
BIBLIOGRAPHY. 21 

EWBERRY, JOHN S. Geological report. Report of expedition from Santa Fe, N. Mex., to the junction of th Grand and Green rivers of the Great Colorado of the West, in 1855, under the 

command f Capt. J. N. Macomb, pp. 9-118, map, plates, 4°, Washington, 1876. 

PEALE, A. C. R port [as geologist of middle division]. U. S. geological and geographical survey of 

the Territo ies, embracing Colorado and parts of adjacent Territories, F. V. Hayden in charge, 

[8th] Ann al Report, for 1874, pp. 73-180, Washington, 1876. 

POWELL, JOHN . Report on the geology of the eastern portion of the Uinta Mountains and a 

region of ountry adjacent thereto. U. S. geological and geographical survey of the Territories, vii, 18 pp., 4°, atlas folio, Washington, 1876. 

WHITE, CHARLES A. In Powell's Report on the geology of the eastern portion of the Uinta Mountains and region of country adjacent thereto. U. S. geological and geographical survey of 

the Territ ies, Washington, 1876, pp. 74-135. 

WILLIAMS, SAMU L G. Notes on the geology of some localities near Canyon City, Fremont County, 

C01.0. U. . geological and geographical survey of the Territories, F. V. Hayden in charge. 

Bull., vol. 1, 2d series, pp. 249-251, Washington, 1876. 

1877. 

ENDLICH, F. M. [Report as geologist of the southeastern division.] U. S. geological and geographical surve of the Territories, embracing Colorado .and parts of adjacent Territories, F. V. 

Hayden i • charge, 9th Annual Report, for 1875, pp. 181-240, Washington, 1877. 

HAGUE, ARNOLD, and EMMONS, S. F. Descriptive geology. U. S. geological exploration of the fortieth 

parallel, C arence King, geologist in charge, Rept., vol. 2, 890 pages, 25 plates, 4°, Washington, 

1877. 

HAYDEN, F. V. Letter [on general results]. U. S. geological and geographical survey of the Territories, em .racing Colorado and parts of adjacent Territories, 9th Annual Report, for 1875, 

pp. 1-28, Washington, 1877. 

Geological and geographical atlas of Colorado and portions of adjacent territory. U. S. 

geological and geographical survey of the Territories, 1877. 

HITCHCOCK, C. H., and BLAKE, W. P. Geological map of the United States. Atlas of the United 

States and the world, by Gray, folio, Philadelphia, 1877. 

HOLMES, W. H. [Report as geologist of the San Juan division.] U. S. geological and geographica 

survey of the Territories, embracing Colorado and parts of adjacent Territories, F. V. Hayden 

in charge, 9th Annual Report, for 1875, pp. 237-276, Washington, 1877. 

PEALE, A. C. [Report as geologist of the Grand River division.] U. S. geological and geographical 

survey of the Territories, embracing Colorado and parts of adjacent Territories, F. V. Hayden 

in charge, 9th Annual Report, for 1875, pp. 31-101, Washington, 1877. 

Notes on the age of the Rocky Mountains in Colorado, Am. Jour. Sci., 3d series, vol. 13, pp. 

172-181, 1877. Also review by J. J. Stevenson, ibid., pp. 297-299. 

STEVENSON, J. J. Parts of southern Colorado and northern New Mexico. Atlas sheet 70 [A]. Atlas, 

U. S. geographical surveys west of the one hundredth meridian, in charge of G. M. Wheeler, 

folio, Washington, May 7, 1877. ' [2d ed., June 30, 1881.] 

1878. 

ENDLICH, F. M. Report on the geology of the White River district. U. S. geological and geographical survey of the Territories, embracing Colorado and parts of adjacent Territories, F. V. 

Hayden in charge, 10th Annual Report, for 1876, pp. 61-131, Washington, 1878. 
22 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

HITCHCOCK, C. H., and BLAKE, W. P. Geological map of the United States. "Die Vereinigten 

Staaten von Nord-Amerika," vol. 1, Munchen, 1878. 

KING, CLARENCE. Systematic geology. U. S. geological exploration of the fortieth parallel, Rept., 

vol. 1, 803 pages, 40 plates, atlas, 4°, Washington, 1878. 

PEALE, A. C. Geological report on the Grand River district. U. S. geological and geographical survey of the Territories, embracing Colorado and parts of adjacent Territories, F. V. Hayden in 

charge, 10th Annual Report, for 1876, pp. 161-185, Washington, 1878. 

WHITE, CHARLES A. Report on the geology of a portion of northwestern Colorado. U. S. geological 

and geographical survey of the Territories, embracing Colorado and parts of adjacent Territories, 

F. V. Hayden in charge, 10th Annual Report, for 1876, pp. 1-60, Washington, 1878. 

1879. 

HENRICH, CARL. The ore deposits of Leadville, Colo. Sci. Am., Suppl., vol. 7 (no. 167), p. 2658, 4°, 

1879. 

STEVENSON, JOHN J. Report on a special geological party operating in Coldrado and New Mexico from 

Spanish Peaks to the south, field season of 1878 [and 1879]. U. S. geographical surveys of the 

territory of the United States west of the one hundredth meridian, in charge of G. M. Wheeler, 

Annual Report, in Annual Report of the Chief of Engineers for 1879. Appendix 00, pp. 2249­

2259 (pp. 271-281 in separate edition), Washington, 1879. 

VIVIAN, A. P. Wanderings in the western land. London, 1879. Contains geologic map from Colorado to the Pacific; scale, 45 miles to the inch. [Not seen.] 

WHITE, CHARLES A. Remarks upon certain Carboniferous fossils from Colorado, Arizona, Idaho, Utah, 

and Wyoming, and certain Cretaceous corals from Colorado, together with descriptions of new 

forms. U. S. geological and geographical survey of the Territories, F. V. Hayden in charge, 

Bull., vol. 5, pp. 209-221, Washington, 1879. 

1880. 

DUTTON, C. E. On the Permian formation of North America. Washington Phil. Soc., Bull., vol. 3, 

pp. 67-68, 1880. 

EMMONS, S. F. [Report of Rocky Mountain division.] U. S. Geological Survey, C. King, Director, 

1st Annual Report, 1879-1880, pp. 16-23, Washington, 1880. 

HAYDEN, F. V. Twin Lakes and Teocalli Mountain, central Colorado, with remarks on the glacial 

phenomena of that region. American Naturalist, vol. 14, pp. 858-862, 1880. 

1881. 

STEVENSON, JOHN J. Report upon geological examinations in southern Colorado and northern New 

Mexico during the years 1878 and 1879. U. S. geographical surveys west of the one hundredth 

meridian, in charge of G. M. Wheeler, Reports, vol. 3, Supp., 420 pages, plates, 3 maps, 4°, 

Washington, 1881. 

Parts of Colorado and New Mexico; parts of atlas sheets Nos. 69 [B], 69 [D], 77 [B], and 

78 [A]. Atlas, United States geographical surveys west of the one hundredth meridian, in 

charge of G. M. Wheeler, folio, Washington, June 30, 1881. 

1882. 

EMMONS, S. F. Geology and mining industry of Leadville, Colo. U. S. Geological Survey, 2d Annual 

Report, pp. 201-290, 1882. 
BIBLIOGRAPHY. 23 

1883. 

BROADHEAD, G. C. Jura-Trias. Kansas City Review. vol. 6, pp. 534-540, 1883. 

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HALLOWELL, JOHN K. Supposed Jura-Trias of the Front Range of Colorado. Kansas City Review, 

vol. 6, pp. 492-496, 1883. 

HUNT, T. STERRY. Geology [progress of, for 1882]. Smithsonian Report for 1882, pp. 325-345, 1883. 

1884. 

EmmoNs, S. F. Introductory geological sketch of Buffalo Peaks, Mosquito Range, Colorado. U. S. 

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EMMONS, S. F. Geological sketch of the Rocky Mountain division. 10th Census United States, vol. 13, 

statistics and technology of the precious metals, pp. '60-104, 4°, Washington, 1885. 

Report of Rocky Mountain division. U. S. Geological Survey, J. W. Powell, Director, 6th 

Annual Report, for 1884-1885, pp. 62-67, Washington, 1885. 

1886. 

EmmoNs, S. F. Geology and mining industry of Leadville, Colo. U. S. Geological Survey, Monograph, 

vol. 12, 4°, Washington, 1886. 

Notes on some Colorado ore deposits. Colorado Sci. Soc., Proc., vol. 2, part 2, pp. 85-105, 1886. 

HILLs, R. C. Remarks on the occurrence of coal in the Carboniferous formation at Aspen and Glenwood Springs, Colo. Colorado Sci. Soc., Proc., vol. 2, pt. 1, pp. 25, 26, 1886. 

RATH, G. VON. Wahrnehmungen in der Umgebung von Silver Cliff, Salida, Leadville und Gunnison, 

Colo. Vortrage und Mittheilungen, 1886.. [Not seen.] 

ROLKER, CHARLES M. Note on the Leadville ore deposits. American Inst. Mining Eng., Trans., vol. 

14, pp. 273-292, 1886. 

Note on the Leadville ore deposits. Eng. and Mining Journal, vol. 41, pp. 36-40, 4°, 1886. 

STEVENS, R. P. On the San Juan Mountains, Colorado. New York Academy of Science, Trans., vol. 

5, pp. 121-130, 1886. 

1887. 

COMSTOCK, THEODORE B. The geology and vein structure of southwestern Colorado.. American Inst. 

Mining Eng., Trans., vol. 15, pp. .218-265, plates 1-4, map, 1887. 

HITCHCOCK, CHARLES H. Geological map of the United States and part of Canada. Compiled to 

illustrate the scheme of coloration and nomenclature recommended by the International 

Geological Congress. American Inst. Mining Eng., Trans., vol. 15, pp. 465-488, 1887. 

LAKES, A. Geology of the Aspen mining region, Pitkin County, Colo. Colorado State School of 

Mines, Biennial Report, 1886, pp. 43-84, plates, 1887. 

OLcurr, E. E. Battle Mountain mining district, Eagle County, Colo. Eng. and Mining Jour., vol. 

43, pp. 418, 419, 437-463, 40, 1887. 

TILDEN, GEORGE C. Mining notes from Eagle County. Colorado State School of Mines, Biennial Report for 1885 and 1886, pp. 129-133, 1887. 
24 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1888. 

BLOW, A. A. The ore chutes and recent developments of Iron Hill, Leadville, Colo. Colorado State 

School of Mines, Annual Report, 1887, pp. 61-85,. plates, 1888. 

Bnurrrori, D. W. Aspen Mountain, its ores and their mode of occurrence. Eng. and Mining'Journal, 

vol. 46, pp. 22, 23, 42, 45, 4°, 1888. 

Emmorrs, S. F. Preliminary notes on Aspen. Colorado Sci. Soc., Proc., vol. 2, pp. 251-277, 1888. 

IHLSENG, M. C. Note on Leadville. Colorado State School of Mines, Annual Report for 1887, pp. 29­

45, 1888. 

KEDZIE, G. E. The bedded ore deposits of Red Mountain mining district, Ouray County, Colo. 

American Inst. Mining Eng., Trans., vol. 16, pp. 570-581, 1888. 

LAKES, A. Geology of Colorado ore deposits, clix pages, plates, 8vo, Denver, Colo., 1888. Reprinted 

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SIVER, LEONARD D. The geology of the Aspen, Colo., ore deposits. Eng. and Mining Journal, vol. 

45, pp. 195-196, 40, 1888. 

WHITE, CHARLES A. Mountain upthrust. American Naturalist, vol. 22, pp. 399-408, 1888. 

1889. 

ELDRIDGE, GEORGE H. Some stratigraphical and structural features of the country about Denver, Colo. 

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Colo. American inst. Mining Eng., Trans., vol. 17, pp. 156-206, 1889. 

STEVENSON, JOHN J. The Mesozoic rocks of southern Colorado and northern New Mexico. Am. 

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1890. 

BLow, A. A. The ore chutes and recent developments of Iron Hill, Leadville, Colo. With additions. 

American Inst. Mining Eng., Trans., vol. 18, pp. 145-181, plates, 1890. 

BREWER, WILLIAM H. Warren's new Physical Geography, 144 pages, 4°, Philadelphia, 1890. [Not 

seen.] 

CANNON, G. L., Jr. Notes on the geology of Perry Park, Colorado. Colorado Sci. Soc., Proc., vol. 3, 

pt. 3, pp. 308-315, 1890. 

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Eng., Trans., vol. 18, pp. 273-278, 1890. 

.1892. 

CANNON, GEORGE L., Jr. Notes on the geology of Palmer Lake, Colorado, and the Paleozoic exposures 

along the Front Range. Colorado Sci. Soc., Proc., vol. 4, pp. 224-234, with map, 1892. 

ELDRIDGE, GEORGE H. The Florence oil field, Colorado. American Inst. Mining Eng., Trans., vol. 20, 

pp. 442-462. 
BIBLIOGRAPHY. 25 

FARISH, JOHN B. The ore deposits of Newman Hill [Rico, Colorado]. Colorado Sci. Soc., Proc., vol. 

4, pp. 151-164, 1892. -

MCMECHEN, THOMAS R. The ore deposits of Creede, Colo. Eng. and Mining Journal, vol. 53, pp. 

301-303, 1892. 

WALCOTT, CHARLES D. Preliminary notes on the discovery of a vertebrate fauna in Silurian (Ordovician) strata. Geol. Soc. America, Bull., vol. 3, pp. 153-167, 3 pls.; discussion, pp: 168-171; 

1892. 

1893. 

CANNON, GEORGE L., Jr. Geology of Denver and vicinity. Colorado Sci. Soc., Proc. 1891-1893, vol. 

4, pp. 235-270, 1893. 

CARLYLE, W. A. Notes on the great silver camp. Canadian Record Science, vol. 5, pp. 403-412, 1893. 

CROSS, WHITMAN. Itinerary, geological excursion to the Rocky Mountains. Int. Cong. Geol., 

Compte Rendu, 5th sess., pp. 423-424, 430-435, 438-442, 1893. 

EMMONS, S. F. Itinerary, geological. excursion to. the Rocky Mountains. Int. Cong. Geol., Compte 

Rendu, 5th sess., pp. 403-417, 425-426, 428-429, 1893. 

1894. 

CRoss, WHITMAN. Pikes Peak folio, Colorado. U. S. Geological Survey, Geologic Atlas of the 

United States, folio 7, 1894. 

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folio 36, 1897. 

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RICKARD, T. A. Enterprise mine, Rico, Colo. American Inst. Mining Eng., Trans., vol. 26, pp. 

906-980, 48 figs., 1897. 

1898. 

EmmoNs, S. F. Tenmile district special folio, Colorado. U. S. Geological Survey, Geologic Atlas of 

the United States, folio 48, 1898. 

[Geology of the Aspen mining district, Colorado. Introduction.] U. S. Geological Survey 

Mon., vol. 31, pp. xvii-xxxii, 1898. 

LAKES, A. The geology of Aspen and the conditions existing in the Smuggler mine at the time of the 

fire [Colorado]. Mines and Minerals, vol. 18, pp. 251-253, 3 figs., 1898. 

SPURR, J. E. Geology of the Aspen mining district, Colorado, with atlas. U. S. Geological Survey, 

Mon., vol. 31, 260 pp., pls. 1-43, figs. 1-11, atlas sheets 1-30, 1898. 
26 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

VAN DIEST, E. C. and P. H. Notes on the geology of the western slope of the Sangre de Cristo Range 

in Costilla County, Colo. Colorado Sci. Soc., Proc., vol. 5, 1894, 1895, 1896, pp. 76-80, map, 

section. 

1900. 

CROSS, WHITMAN, and SPENCER, A. C. Geology of the Rico Mountains, Colorado. U. S. Geological 

Survey, 21st Ann. Rept., pt. 2, pp. 15-165, pls. i-xxii, 1900. 

GIRTY, G. H. Devonian fossils from southwestern Colorado ; the fauna of the Ouray limestone. U. S. 

Geological Survey, 20th Ann. Rept., pt. 2, pp. 31-63, pls. iii-vii, 1900. 

HILLS, R. C. Walsenburg folio, Colorado. U. S. Geological Survey, Geologic Atlas of the United 

States, folio 68, 1900. 

SPENCER, A. C. Devonian strata in Colorado. Am. Jour. Sci., 4th ser., vol. 9, pp. 125-133, 1900. 

Abstract : Science, n. s., vol. 11, pp. 105-106, 1900. 

1901. 

DARTON, N. H. Comparison of stratigraphy of the Black Hills with that of the Front Range of 

the Rocky Mountains. Abstract: Geol. Soc. America, Bull., vol. 12, pp. 478-479, 1901. 

Comparison of stratigraphy of the _Black Hills with that of the Front Range of the Rocky 

Mountains. Abstract: Science, n. s., vol. 13, p. 188, 1901. 

RIGGS, ELMER S. The Dinosaur beds of the Grand River Valley of Colorado. Field Columbian Mus., 

Pub. 60, Geol. Ser., vol. 1, no. 9, pls. xxxiv-xxxix, pp. 266-274. Chicago, Sept., 1901. 

1902. 

LEE, W. T. The areal geology of the Castle Rock region, Colorado. Am. Geol., vol. 29, pp. 96-109, 

pl. 4, 1902. 

Note on the Carboniferous of the Sangre de Cristo Range, Colorado. Jour. Geol., vol, 10, No. 

4, pp. 393-396, 1902. 
RESUME OF LITERATURE AND CLASSIFICATION OF AREAS. 

Although I had set out to consider only the Carboniferous rocks and faunas of 

Colorado, it seemed that the relations to each other of the sections situated in 

different parts of the State could not be intelligently estimated without more or less 

careful reference to the strata upon which they rest or those by which they are 

succeeded. As the earlier Paleozoics play but an insignificant part in the sections 

seen in the State, it proved a comparatively easy task to carry along the entire 

pre-Carboniferous portions of the different sections; and the supposed Trias and 

Jura were also held in mind. 

Carboniferous rocks, are usually seen in Colorado only where brought to the 

surface by mountain uplifts. Otherwise they lie deeply buried beneath heavy 

sections of Mesozoic and Tertiary sediments and often beneath igneous flows. 

Their present outcrop, therefore, consists largely of more or less discontinuous 

areas exposed along the flanks of mountain ranges or sometimes in the channels of 

rivers. 

As exhibited on the general geologic map of the Hayden atlas,a the most 

conspicuous feature in the distribution of the Carboniferous is a discontinuous band 

stretching from the northwest corner of the State to the center of its southern 

border. This is too large a tract to be conveniently considered without subdivision, 

especially as the geologic section is not uniform throughout. 

The northwestern portion of this band of CarbOniferous outcrop is formed by 

the eastern end of the Uinta Mountains; and as it is separated by a considerable 

extent of Mesozoic and Tertiary beds from the remainder of the Carboniferous 

outcrop to the southeast, it can appropriately be considered as a distinct area, under 

the name of the Uinta Mountain region. 

Southeast of the Uinta Mountains is a large area of Carboniferous having a very 

irregular outline, which is chiefly exposed along the White and Grand rivers and 

their tributaries. No single topographic feature seems to be preeminently distinctive 

of this area, but I have distinguished it as the Grand River region, giving it the 

name of the river which divides it in the middle. 

Connected with this to the south, and really forming a part of it, is the area 

produced by the upturned beds of the Elk Mountains. I will, however, speak of 

a Tj. S. Geol. Geog. Surv. Terr., Atlas Colorado, etc., 1877. 27 
28 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

this as the Elk Mountain region, restricting the name Grand River region to the 

northern portion. 

To the east and southeast of the Grand River and Elk Mountain areas, and 

separated by the Archean Sawatch Mountains, is a narrow and smore linear 

tract, the northern portion of which lies on the western side of the mountain 

valley called South Park. This, southward to the canyon of the Arkansas, I shall 

designate the South Park region. 

Pra,ctically connected with this, but sending off a long spur to the northwest, 

the outcrop is taken up by the Sangre de Cristo Range, and from the Arkansas 

River southward to Costillo Peak, where the Carboniferous exposures cease, it may 

be appropriately called the Sangre de Cristo- region. 

Another well-defined area of Carboniferous rocks is found in southwestern 

Colorado. This may be. designated the San Juan area, and the Hayden survey has 

several times employed for this general country the name Sun Juan region, or San 

Juan district. Under this title will be included the Paleozoic series of the Rico and 

the La Plata mountains, as well as the exposures in the valley of the Animas River. 

Another interesting series of outcrops occurs in western Colorado along the 

lower portion of the Dolores River to its junction with the Grand, and along the 

Grand from this point to beyond the State line in Utah. This series of outcrops, 

because the name Grand River area has already been made use of, I will call the 

Dolores River region. 

The last and final area is the entire strip of sediments upturned along the 

eastern margin of the Front Range. The main portion of this outcrop, though 

here and there containing patches of early Paleozoic beds, consists of the Red Beds 

usually referred to the Trias; but their Triassic age is not well established, and 

as reason exists for supposing that part of the series at least is of Carboniferous 

age, I will speak of this as the Front Range region. This area will begin with the 

northern border of the State and extend southward to the Huerfano River, including, . 

in fact, the bordering outcrops of the Wet Mountains as well as those of the Front 

Range. 

All these areas have more or less extensive contiguous disconnected outliers, 

but to these it, did not seem necessary to apply independent names, especially as no 

evidence at hand demanded particular reference to them. Most of these areas are 

artificial in delimitation and established for the purpose of convenience in treatment. 

The Uinta area is independent because of its isolated position, and because, perhaps, 

of the peculiarities of its section. 

UINTA MOUNTAIN REGION. 

Perhaps the earliest geologic exploration in the Uinta Mountains, the earliest 

certainly of which I have found note, was made by W. A. Jones," who traversed the 

a Chief of Engineers U. S. Army, Rept. for 1872. 1873, pp. 1108-1118. 
RESUME OF LITERATURE. 29 

mountains in 1871. He describes the structure of the Uinta Range with some 

accuracy, though stating that the upheaval took place not long subsequent to the 

Carboniferous epoch (p. 1112). "The uplifted beds," he says, "as displayed by 

the lateral erosion, are almost entirely composed of a brownish-red sandstone, 

rarely, if at all, fossiliferous, of the Subcarboniferous epoch, the color rarely 

changing into gray. * * * They are -of very great thickness, from 2,000 to 

3,000 feet, being visible near the summit. Higher up in the series, and lying along 

the base of the mountains toward Green River, the Carboniferous beds of soft, 

bright yellow sandstone, coarse conglomerate, blue limestone (quite rare and thin), 

and gypsum (in thin seams) are exposed. * * * The series above the Carboniferous either do not occur or are overlaid by a highly fossiliferous deposit of 

Tertiary age. This deposit lies nearly horizontal, and is composed of soft yellow 

and red marls, greensand, and thin beds of soft limestone and chert" (p. 1113). 

Apparently the Carboniferous of this account forms part of the Mesozoic of Powell's 

Uinta Mountains report, and the geologic age, determined as Carboniferous, must 

have been assigned, I fear, because of its contained coal seams. Jones's Subcarboniferous is with little doubt the Uinta sandstone of Powell's report, and he 

determination of its age apparently depends upon the fact that it lies under the 

coal-bearing series thought to be Carboniferous. 

A report by Powell upon the geology of the Uinta Mountains, published in 1876, 

and the reports of the Fortieth Parallel Survey which appeared almost immediately 

after, discuss the geology of considerable Carboniferous areas in northwestern Colorado, and remain at the time of writing almost the only accounts, as they are certainly the most comprehensive ones, of the subject. These reports, together with 

one by White published subsequently and that by Jones already referred to, constitute the entire literatuie of the Uinta area, and it is all too meager and 6ontradictory. 

In the case of the Fortieth Parallel Survey the actual explorations were made 

by Hague and Emmons,a whose accounts constitute volume 2 of that series. The 

volume on systematic geology by King (vol. 1), however, which is a restatement 

of their facts and a general discussion based upon them, is a more convenient and 

suggestive form in which' to consult these data. 

Powell's observations, as already said, are embodied in the volume upon the 

geology of the Uinta Mountains,' which contains a relatively lengthy paleontologic 

discussion by C. A. White, who subsequently published in the Tenth Annual Report 

of the Hayden Survey an account, based upon independent observations, of the 

geology of a part of the Colorado Uinta area, and also several briefer papers 

recapitulating much of the same matter. 

The title of Powell's work is somewhat misleading, as his discussion is mainly of 

a U. S. Geol. Expl. 40th Par., Rept., vol. 2, 1877. 


b U. S. Geol. Geog. Surv. Terr., Powell's Rept. Geol. Uinta Mountains, 1876. 

30 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the geology of the Plateau province as a whole, and but 75 of the upward of 200 

pages comprised in it deal directly with the geology of the Uinta Mountains, and that 

only of the eastern portion. Through his presentation of the subject it thus happens 

that while the typical exposures of the Red Wall and of the upper and lower Aubrey 

groups are in northern Arizona, the same names are employed for formations in 

northwestern Colorado, and that the geology of the latter area, historically at least, 

is intimately connected with that of the Grapd Canyon country. In a similar manner, since Emmons and King describe the Uinta sediments in connection with those 

of the Wasatch Mountains, recognizing the same formations and employing the same 

names in both, the Uinta section can not well be considered apart from that, of the 

Wasatch Mountains. 

1 am especially concerned only with the strata of Carboniferous age in the Uinta 

Mountains. These are described on page 57 and again on page 146 of Powell's work, 

while the general section and description for the Plateau province occur on pages 

40 and 54. The faunal characters of the Carboniferous are outlined and discussed on 

pages 76, 79, and 88. 

Over 5,000 feet of strata in the Uinta Mountains are referred by Powella to the 

Carboniferous, and four subdivisions of Carboniferous beds are recognized. These 

are called in ascending order the Lodore group, the Red Wall group, the lower 

Aubrey group, and the upper Aubrey group. The Lodore group, 460 feet in thickness, consists of sandstones and shales with conglomerates at the base. The Red 

Wall group is 2,000 feet thick and consists chiefly of limestones separated by thin 

sandstones. The lower Aubrey comprises 1,000 feet of rather soft sandstones with 

intercalated limestones. The upper Aubrey is composed of two members—a massive, 

homogeneous, light-gray sandstone at the base, called the Yampa sandstone, which 

has a thickness of 1,000 feet or more, and above 150 to 200 feet of cherty limestone 

for which the name Bellerophon limestone is employed. 

These four Carboniferous formations are conformable with one another, but 

according to Powell they are separated by a profound unconformity from the underlying beds, which have been called the Uinta sandstone. The unconformity is one 

both of dip and erosion. The difference of dip between the Lodore group and the 

Uinta sandstone is about 4 degrees, the lower formation having the greater inclination to the south. Cliffs of the Uinta sandstone formed prior to the deposition of the 

Lodore project in some instances 400 feet into the mass of superimposed sediments 

(page 144). 

The upper Aubrey formation is succeeded by the Juratrias groups, which 

received the names of the Shinarump, Vermilion Cliff, White Cliff, and Flaming 

Gorge groups. No unconformity was observed between the upper Aubrey and the 

a Powell mentions the constituent members of his Carboniferous series in several places, and each time with .a 

different thickness. The above is the sum of the thicknesses in a detailed section, aggregating in all 5,305 feet. 
RESUME OF LITERATURE. 31 

Shinarump groups, but as the lowest beds of the Mesozoic are of very friable material, the exact junction was rarely seen (page 150). At the same time, that an interruption in sedimentation did occur at the top of the upper Aubrey group is indicated 

by the following passage, quoted from page 69: 

"The plane of demarcation between the Shinarump group and the summit of 

the Carboniferous is always well marked. Soft, gypsiferous shales are found at the 

base of the upper group, and either a pure limestone, a cherty limestone, or a homogeneous sandstone at the summit of the Carboniferous. In places, however, a conglomerate is found at the base of the. Shinarump group, its coarser fragments being 

composed of cherty limestone which contains Upper Carboniferous fossils. So in 

some places, at least, the epoch of change was a period of erosion." 

Accompanying the report upon the geology is a paleontologic report by. C. A. 

White, which forms an important part of the volume under discussion. He gives 

faunal lists from the different formations of the Plateau province from which collections were obtained, discusses the ages of the beds and describes many new forms. 

Carboniferous faunas are cited from the Red Wall and the upper and lower Aubrey 

groups. His conclusions in regard to the Carboniferous faunas are expressed in the 

following words (page 79): 

"A large proportion of all these fossils are specifically identical with well-known 

forms in the strata of the Carboniferous or Coal-Measure period in the States of the 

Upper Mississippi Valley; and all but two of them belong to such types as we might 

naturally expect to find in the equivalents of those strata. These two belong to the 

two genera, respectively, Archimedes and Amplexus, the former of which especially 

has been regarded as an exclusively Subcarboniferous genus; and yet they are found 

in the lower Aubrey group, nearly 3,000 feet above the base of the Carboniferous 

series, and also above and mingled with types that have not hitherto been found 

in strata so low as the Subcarboniferous. 

"Few or none of the fossils of the collections are of such a character as to suggest the Permian age of the strata from which they were obtained, not even those 

of the upper Aubrey group. I have elsewhere showna that the prevalence of certain types which have been relied upon to prove the Permian age of the strata, containing them may be due to peculiar physical conditions, and I therefore regard it 

as not improbable that the time of the Permian period may be represented in the 

Plateau Province by the upper Aubrey group, although the distinguishing types are 

wanting there. In view also of the mixture which we find, of Carboniferous and 

Subcarboniferous types in the same strata, it seems projable that the time of the 

whole Carboniferous age, including its three. periods, Subcarboniferous, Carboniferous, and Permian, is collectively represented by 'the four groups in the Plateau 

Province." 

No fossils are cited from either the Lodore or the Uinta formations. The latter, 

however, is provisionally referred to the Devonian by Powell (pages 70, 141), while 

the Lodore group, which overlies it unconformably, is included in the Carboniferous. 

aGeology of Iowa, 1870, vol. 1, p. 249. 
32 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Between the Flaming Gorge group, with a fauna identified as fresh-water Jurassic, and the upper Aubrey, which is Carboniferous, intervene three formations 

whose age was not ascertained—the Shinarump, Vermilion Cliff, and White Cliff 

groups. These belong to the Red Beds series and have been placed with the Juratrias. There is some reason to believe that the upper limit of the Carboniferous 

should have been placed at a somewhat higher horizon, and it is possible that the 

upper portion of the Uinta sandstone should have been included in the same period. 

These points will be discussed further on. 

Both lithologically and faunally the geologic sections in northeastern Utah and 

northern Arizona are sufficiently unlike, so far as the Paleozoic strata are concerned, 

to cast suspicion upon the correctness of Powell's correlations. The lower Aubrey 

and Red Wall groups, as described by Powell in the different sections, seem to present 

pretty much the same lithologic characters, but the upper Aubrey group is more 

variable. " To the southward, in the Grand Canyon country, these beds are a series 

of cherty limestones. At the junction of the Grand and Green they are a series of 

sandstones with intercalated cherty limestones, with a homogeneous sandstone at the 

summit 150 feet in thickness. In the Uinta Mountains we have a homogeneous gray 

sandstone which we call the Yampa sandstone, from 1,000 to 1,200 feet in thickness, 

capped by a bed which is believed to be the equivalent of the one mentioned as 

found at the summit of the series at the junction of the Grand and Green, and 

varies from 150 to 200 feet in thickness. On the south side of the Uinta Mountains 

it is an indurated, calciferous sandstone, but on the north side of the mountains it is 

a cherty limestone, and on both flanks it is characterized by a species of Bellerophon. 

Here we have called it the Bellerophon limestone." (Page 55.) The Lociore group, 

which is typically exposed in the eastern Uintas, does not extend far to the south, 

nor was the Tonto group, which, in the Grand Canyon region, underlies the Red 

Wall group, traced far to the north. Because of a certain similarity in stratigraphic 

position Powell wished to correlate these two formations and to employ for both the 

name Tonto group (page 56). Walcott, however, has shown that the Tonto group is 

of Cambrian age,a while the Lodore group can, with great probability, be referred 

to the Carboniferous.b 

In the Uinta Mountains the Lodore group is underlain unconformably by the 

great mass of the Uinta sandstone, 12,500 feet in thickness, of which the Uinta Range • is mainly composed. The age of this series was not ascertained, but it was referred 

tentatively to the Devonian (page 70). The Uinta sandstone rests uncomformably 

upon the Red Creek quartzite, of which 10,000 feet are reported without the bottom 

having been seen. 

In the Grand Canyon region, uncomformably below the Tonto sandstone, is found 

a Am. Jour. Sci., 3d ser., vol. 26, 1883, p. 439. 

b Powell states that Carboniferous fossils have been found in the Lodore group (pp. 56 and 147), but apparently none 

were collected (p. 79). 
RESUME OF LITERATURE. 33 

the Grand Canyon group, 10,000 feet of sandstones and conglomerates, and this in 

turn rests unconformably upon the Grand Canyon schists. The Grand Canyon 

schists and the Red Creek quartzite Powell regards as of Eozoic age, and the Grand 

Canyon group he refers to the Silurian (pages 56, 70). Upon this construction of 

the facts the Grand Canyon schists and the Red Creek quartzite would be in a 

manner correlated, and the Grand Canyon group of the Grand Canyon area would 

underlie the Uinta group of the Uinta area, neither great series being represented 

in both regions. It would appear from this that in Paleozoic time at least the two 

regions passed through very different geologic histories. In fact, however, it appears 

to me more probable that the Grand Canyon group is to be correlated with the Red 

Creek quartzite and that both are Algonkian. 

A critical study of the paleontologic evidence reveals discrepancies well nigh 

as marked as those shown by the comparison of the geologic sequence. 

But a single Carboniferous species is cited by White as having been obtained in 

Colorado itself, but more or less extensive collections were made in portions of the. 

Uinta Mountains which lie beyond its confines in the State of Utah. No fossils are 

cited from the Red Wall limestone in the Uinta Mountains, but three collections were 

made in the lower Aubrey formation and one in the upper Aubrey. The only 

faunas known from the Red. Wall group were collected at two stations situated close 

together southeast of the central part of Utah. From Gypsum Canyon were obtained 

Chwtetes milleporaceus and Syringo_pora multattenuata, and from Cataract Canyon 

an undetermined species of Campoph,yllum. These faunas, so far as they go, are quite 

dissimilar, but are yet so limited that they might readily have come from the same 

bed, somewhat the more because the zoologic relations of the three species are all 

with the same class, the corals. On looking up the collections upon which this 

report was based the specimens referred to Ch. milleporaceus could not be found. 

The original material of S. multattenuata, as well as it could be identified, consists 

of an external cast, and can not be definitely determined. The Campo_phyltum is 

probably that form from the Diamond Mountains figured by Meek in the reports of 

the King survey.a The evidence therefore, whether of the lists or of the fossils, is 

inconclusive, but so far as it goes is coincident in indicating Upper Carboniferous. 

In the detailed section at Cataract Canyon, given by Powell on p. 60, the Red 

Wall group is described as huffish lavender, friable, fine-grained sandstone; base not 

seen. This is not at all the character of the real Red Wall limestone, and these beds 

more probably belong above the Red Wall, in the lower .Aubrey series. Thus the 

stratigraphic and paleontologic evidence agree in discrediting Powell's identification 

of the Red Wall at this place. At the same time it should not be lost sight of that 

the upper half of the typical Red Wall belongs in the Pennsylvanian. 

a U. S. Geol. Expl. 40th Par., Rept., vol. 4, 1877, p. 57, p1. 5, figs. 2,2b. 

14364—No. 16-03 3 
34 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

'The lower Aubrey group furnished most of the fossils collected, and an extensive 

fauna is cited, obtained chiefly at three localities. One of these is not far from the 

stations at which the Red Wall fossils were found. The two others, Echo Park and 

Split Mountain Canyon, are close together in the Uinta Mountains in the extreme northeastern part of Utah. From Echo Park are cited Amplexus zaph,rentiformis, Fenestella 

sp., Archimedes sp., Chonetes platynotus, Prodiuctus longispinus (?), Productus 

costatus (?), P. costatus var., Productus muricatus, Hemipronites crenistria, Seminula 

subtilita, S_pirifer rockyntontanus, and Ph,i1U_psia sp. ; and from Split Mountain 

Can3Ton are cited Amplexus zaphrentVormis, Ch.tetes milleporaceus, Acervularia sp., 

and Spirifer rockymontamus. It thus appears that two of the four species collected 

at Split Mountain Canyon occur also at Echo Park, and there seems to be no reason 

for suspecting- that the two lists do not represent the same fauna. The specimens 

upon which some of the listed species were based appear to have been lost from the 

collection, and while I do not agree in every case with Professor White's identifications, I think the fauna shown, whether by the lists or by the specimens themselves, 

must be taken as indicating Upper Carboniferous. On the other hand, the 

assemblage is not quite that of one of the common Upper Carboniferous faunas of 

the Mississippi Valley, so that to a certain extent Powell's statement is borne out— 

that in the Great Basin region the grouping of fossils is peculiar (loc. cit., p. 4). It is 

with this fauna that there is said to occur the anomalous association of Lower 

Carboniferous types, such as Amplexus zaphrentiformis and the genera Lithostrotion, 

Acervularia, and Archimedes, with an Upper Carboniferous fauna, a fact to which 

attention was directed by White in a passage previously quoted. The survival into 

the Upper Carboniferous of the already long-established genus Amplexus, which is 

known in America as late as Upper Mississippian time, would not necessarily 

occasion surprise, nor even possibly that of the Devonian genus _Acervularia, which 

is also known in the Carboniferous, but the case is somewhat different with 

Archimedes. A striking and highly specialized scion of the fenestellid stock, this 

type makes its earliest appearance in the Keokuk epoch; it attains its maximum in 

the Chester, and has never before, I believe, been cited in association with an Upper 

Carboniferous fauna. For my own part, I should wish to see the occurrence verified 

'in the present case, and am even inclined to invoke an accidental, or some other 

than an actual faunal, association. Unfortunately, and the circumstance may not

. be without significance, the representatives of both Archimedes and Acervularia are 

missing from the collection as it now stands. 

On the other hand, as the Lower Carboniferous is supposed to be missing in the 

eastern Uintas, the whole Paleozoic section above the Uinta sandstone being referred 

to-the Upper Carboniferous, if these specimens of Archimedes really were obtained 

from this area and from beds now in place, it seems that the peculiar association 
RESUME OF LITERATURE. 35 

noted by White must be accepted. In a condition thus unsatisfactory, without 

having attained to more than the probabilities, it seems necessary to turn from this 

point until fresh evidence is obtained. 

From the upper Aubrey group in the Uinta Mountains only a meager fauna 

is known. White cites Bellerophon carbonarius var. subpapillosus from Junction 

Mountain and near Diamond Peak, in northwestern Colorado; and in Utah, from near 

Echo Park, Bellerophon earbonarius var. subpapillosus, and from Beehive Point, 

near Horseshoe Canyon, Discina sp., Hemi:prondtes creastria, S_pirigera subtilita, 

Spirifer rockymontanus, and Bellerophon carbonarius var. subpapillosus. This fauna, 

so far as it goes, indicates again the Upper Carboni Serous, without any suggestion 

of Permian, as White also has remarked. 

Gypsum and Cataract canyons, where the only collections from the Red Wall 

limestone were made, and the junction of the Grand and Green rivers, where the 

largest collections representing the lower Aubrey group were obtained, are close 

together, southeast of the center of Utah. In this region, as the Lodore group was 

not, I believe, identified outside of the Uinta Mountains, the Red Wall group is the 

lowest of the Carboniferous formations. Its fauna has already been spoken of, and 

the opinion expressed that it indicates in an inconclusive but at the same time an 

unambiguous manner the age of the Upper Carboniferous. 

From the lower Aubrey group at the junction of the Grand and Green rivers 

sp., 

a considerable and characteristic fauna is cited, as follows: 

pora 

Erisocrinus typos, Scaphiocrinus carbonarius, Eupachycrinus platybasis, Polypora 

Productus punctatus, P. longispimus (?), P. prattenianus,

sp., Lophophyllum _proliferum, Areh,wocidaris cratis, Archwocidaris trudifer, 

Fistulipora 

semireticulatus 

sp., Syringovar. 

ivesii, P. nebraskensis, P. multistriatus, Ch,onetes gradiulifer, Hemipronites crenistria, 

lffeekella striaticostata, Seminula subtilita, SpirVer cameratus, Spinferina kentuckyrophorus 

ensis, Myalina recurvirostis, Allerisma subeuneatum, Edmond& aspinwallensis, Pleusp., Schizodus wheeleri, Bellerophon sp., Euomphalus sp., Pleurotomaria 

excelsa, and Naticopsis remex. This fauna has no uncertain significance, and evidently belongs in the Upper Carboniferous. 

At the same locality, but in the upper Aubrey group, was obtained the following 

a determination is in line with its position in the section above a well-characterized 

fauna: 

to assign the horizon to the Permian. 

Upper Carboniferous fauna. In the four species cited there is nothing to lead one 

fortianus. 

Spiriferina kentuckyensis, Jiyalina 

Though scanty, this fauna is indicative of Upper Carboniferous, and such 

sp., Edmondia sp., and Bellerophon montThe comparison of these faunas with those in the Uinta Mountains supposed to 

come from the same beds is full of interest. Of the thirty species which are cited 

from the lower Aubrey group at the junction of the Grand and Green rivers, but 
36 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

three are common to the list from the beds called by the same name in the Uinta 

Mountains, and these three (brem•ipronites crenistria, Productus longispinus, and 

Seminula subtilita) are such as, having in common acceptation specific limits of the 

broadest, have also the longest range, which may he said to have been synchronous 

with all Upper Carboniferous time. Two Upper Carboniferous faunas of equal 

extent could scarcely have less in common than the two listed here. The same is 

true of the meager faunas known from the upper Aubrey group in the two areas. 

These faunas, as cited from the Uinta Mountains and from the confluence of the Grand 

and Green rivers, contain not a single species in common, but it is noteworthy that 

the fauna of the upper Aubrey in the Uinta Mountains is practically the same as 

that of the lower Aubrey in the same region, and a similar resemblance may be 

pointed out between the faunas of the upper and lower Aubrey groups at the 

confluence of the Grand and Green rivers. 

Of the geology of the Grand Canyon region, whence Powell derived the names by 

which the formations in the Uinta Mountains are denoted, but little need be said. 

Powell himself cites no Carboniferous fossils from this region. Gilbert first gave 

local names to the Carboniferous series in the Grand Canyon region,a dividing it into 

the Aubrey limestone, the Aubrey sandstone, and the Red Wall limestdne. He cites 

from the Aubrey limestone (the upper Aubrey of ;Powell) an Upper Carboniferous 

fauna not unlike that which the latter obtained in the homonymous beds at the junction of the Grand and Green rivers. In the topmost strata Schizodus, Pleuroph,orm, 

and Bakewettia were found, an assemblage not noted by Powell, and one "suggesting 

the Permo-Carboniferous of the Mississippi Valley." a The Aubrey sandstone contains few fossils, " but an intercalated limestone, below the middle of the series at 

Canyon Creek, bears the familiar Coal Measure shells."a 

In the Red Wall limestone fossils are said to be " abundant near the top, but 

difficult to find in the lower portions."b The lowest horizon from which fossils were 

obtained was a trifle below the middle of the series. They were doubtfully referred 

by Meek to the Lower Carboniferous. "The fauna of the upper portion is rich in 

species, and, while differing from that of the Aubrey limestone, is equally referable 

to the Coal Measures." 

In describing the Paleozoic section in Kanab Canyon, Walcott e identifies Silurian, 

Devonian, Carboniferous, and Permian strata. These are separated from one another 

by planes of erosional unconformity, and in addition the Permian is divided into 

two portions by an erosion period, and the Upper Permian is succeeded by another. 

To the Carboniferous Walcott refers the Red Wall limestone and the upper and 

lower Aubrey groups. His Lower Permian is the Permo-Carboniferous of Gilbert, 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, p. 177. 


b Ibid., p.178. 


0 Am. Jour. Sci., 3d ser., vol. 20, 1880, p. 222. 

RESUME OF LITERATURE. 37 

and his Upper Permian seems to be a portion of the series which Gilbert, lacking 

paleontologic evidence, referred to the Trias. 

Frech a has briefly described the geologic section in Congress Canyon on the 

occasion of an excursion of the International Geological Congress in 1891. He refers 

the Red Wall group to the Lower Carboniferous and the Aubrey group to the Upper 

Carboniferous. 

It thus appears that the three reports which have been cited agree in referring, 

on paleontologic evidence, the Red Wall group wholly or in part to Lower Carboniferous time. Walcott carries the Carboniferous (Permian) above the top of the 

upper Aubrey group. The following statement from Gilbert is also of interest: b 

"The classification adopted for the Carboniferous rocks in the Grand Canyon 

and along the southern margin of the Carboniferous plateau is of local value only. 

Seventy-five miles to the west, in the Spring Mountain Range, I was unable to 

correlate the series in detail, and eastward, from Canyon Creek to Camp Apache, the 

progress of a rapid transformation can be traced." 

It seems that we can accept Powell's section of the eastern Uintas with some 

modifications, but not his correlations with the Grand Canyon section in the case of 

the lower beds. Powell seems to fix the thickness of the upper Aubrey, lower 

Aubrey, Lodore, and Red Wall groups of the Uinta section at over 5,000. feet. 

King allows only 2,000 to 2,500 feet for the same interval. White, as will appear 

later, places the thickness at 3,100 feet, which, as it is intermediate between the figures given by Powell and King, is perhaps nearer the true thickness.c It might be 

inferred also that Powell had overestimated the extent of the unconformity between 

the Lodore and Uinta formations. King seems to discredit it altogether, and White 

states that in his area it was slight and easy to be overlooked. 

All available evidence points to the conclusion that Powell's. Red Wall limestone 

of the Uinta section is wrongly correlated, and with it several other beds. The 

lower part of the real Red Wall is without doubt of Mississippian age. This has 

been the opinion held more or less tentatively by Meek, Walcott, and Fred], and 

we have a Mississippian fauna from it. On the other hand, it is, almost certain that 

the "Red Wall" of the Uinta Mountains belongs entirely in the Upper Carboniferous. The few fossils collected from it by Powell at Gypsum and Cataract canyons 

indicate Upper Carboniferous. The Uinta sandstone, which underlies it, seems to 

be rightly correlated with the Weber quartzite, which carries Upper Carboniferous 

fossils. The Uinta sandstone itself has probably furnished a few fossils of the same 

age. Powell mentions Carboniferous fossils as occurring in the Lodore group, and 

a Cong. Geol. Internat., 5th sess., Compte Rendu, 1893, p. 476. 

b U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, p. 179. 

c This measurement is exclusive of the Lodore group, which White says was not presen tin his area. At the same time, 

as the Lower and Middle Carboniferous are said to be so like one another and so like the Uinta sandstone as to be sometimes difficult to distinguish, it may be that he merely failed to discriminate the Lodore. If really absent an overlap 

would be indicated above the Lodore, as well as an unconformity below it. Its thickness is but 465 feet. 
38 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

as it is highly probable, from its lithologic composition, that the Lodore does not 

belong to the Mississippian limestone series of the West, it must be of Upper 

Carboniferous age. King cites a few species of unmistakable Pennsylvanian age 

from 60 feet above the Weber quartzite, a horizon which must be in the Lodore 

group and below the Red Wall limestone of the Uinta section. 

I shall later offer some evidence tending to show that the lower portion of the 

Uinta sandstone is Cambrian and the upper portion Upper Carboniferous (Weber 

quartzite). If this is so, the Grand Canyon series of the Grand Canyon section would 

probably be equivalent to the Red Creek quartzite of the Uinta section, and the Tonto 

sandstone to the lower part of the Uinta sandstone, while the Devonian and the true 

Red Wall limestone would probably be wanting. It remains to find the equivalent in 

the Grand Canyon section of the Pennsylvanian portion of the Uinta sandstone and 

. of the beds which Powell called the Lodore group, the Red Wall limestone, and the 

upper and lower Aubrey groups. On the whole it seems to me most probable that 

the four formations last mentioned represent the Aubrey group of Gilbert. The 

lithologic character of the series is not unlike, and in a general way Powell traced 

their equivalence in the field. The paleontologic evidence is partly faVorable and 

partly adverse to this correlation. From the Aubrey group Gilbert cites Productus 

hmsid, Productus semireticulatus, SpiriXr lineatus, Seminula subtilita, Veekella sp., 

Derbya sp., Aviculopecten cf. occidentalis (p. 177). Most of these are well-known 

Pennsylvanian species of the Mississippi Valley section; but I am inclined to 

question the exact identity in some cases. Newberry, however, had previously 

pinis, Archaeocidaris ornatus, Archwocidaris grew/Xs, Meekella occidentalis, _Meekdescribed a number of species from this horizon, namely, 

ella pyramidatis, Ohonetes verneuilanus, Productus costatoides, Brauctus 

lineatus, Seminula subtilita, Aviculopecten coloradoensis, Allerisma capax, 

Productus occidentalis, Productus costatus, Productus semireticulatus, Splirifer 

Archwocidaris longisetc.a 

Many of these species are new and are not known to occur in the Mississippi 

Valley. To this list may be added Productus subhorridus Meek, which is 

found at this horizon. From the lower Aubrey group, at the junction of the 

Grand and Green rivers, White cites some of the same forms, among them 

ductus ivesn, 

As associated with it is mentioned also 

which I provisionally regard as correlated with the Aubrey group of the Grand Canhorizon in the Wasatch Mountains is in the Upper Coal Measure limestone, a series 

.. which appears to be especially characteristic of the Aubrey formation. 

Productus multistriatus, a species whose 

Proyon country, and with the four formations of the Uinta sandstone now under consideration. This evidence is of course very slender, and must be reenforced by a full 

consideration of all these faunas, a task to which I shall address myself at some future 

a Ives's Report Colorado River of West, Senate Ex. Doc. No. —, Thirty-sixth Congress, first session, 1861, pp. 116-129, 
RESUME. OF LITERATURE. 39 

time. As I have already shown, the faunas from the eastern -portion of the Uinta 

Mountains, supposed to come from the same horizon, are almost entirely different. 

The peculiar and striking forms, whether of the Aubrey group of the Grand Canyon, 

or of the Upper Coal Measure fauna of the Wasatch MOuntains, seem to be absent. 

Another circumstance adverse to the correlation consists in the thickness of the 

formations supposed to be equivalent. The typical Aubrey groiip has a thickness of 

but 1,800 feet, while the Lodore, Red Wall, upper Aubrey, and lower Aubrey groups 

of the Uinta Mountains, according to Powell, amount to 5,000 feet, though, as 

already noted, White assigns 3,100 feet and King but from 2,000 to 2,500 feet to the 

same formations. It is a fact not perhaps without suggestion, that if to the Aubrey 

group be added half the thickness of the Red Wall limestone, the upper portion of 

which is known to be of Pennsylvanian age, the total (3,070 feet) is almost precisely 

the same as White's measurement in the Uinta Mountains, which is -nearly a mean 

between King's and Powell's. Upon this point—whether the Pennsylvanian portion 

of the Red Wall limestone is missing from the Uinta section, or is represented by 

part of King's Upper Coal Measures, there is very little evidence. There exists, 

however, such an analogy between the sections of the Wasatch Mountains, the Grand 

Canyon region, and central Colorado, where each shows a limestone series which 

is in part Mississippian and in part Pennsylvanian (the Wasatch limestone in the 

Wasatch Mountains, the Red Wall limestone in the Grand Canyon, and the Leadville and Weber limestones in the Crested Butte section), that I am disposed to 

assume uniformity in other respects, and to believe that the whole of the Red Wall 

limestone is missing in the eastern Uintas, just as all the Wasatch limestone and the 

Leadville and Weber formations are supposed to be. According to this correlation, 

then, the Devonian, Mississippian (lower Red Wall), and lower Pennsylvanian (upper 

Red Wall) wedge out as the eastern Uintas are approached,a while the Weber quartzite, 

which is supposed to come above them, disappears southward. The 'inconformity 

which Powell noted between the Lodore group and the Uinta sandstone might be 

cited as a cause for the removal of this series in the Grand Canyon region. 

The occurrence of great Algonkian (?) masses in the Grand Canyon series of the 

Grand Canyon, in the quartzites of the Needle Mountains in Colorado, and in the 

Red Creek quartzite of the Uinta section, suggests that a band of this series, having 

an approximate north-south trend, may extend through this region. 

The year following the publication of Powell's report upon the Uinta mountains 

appeared the second volume of the reports of the Fortieth Parallel Survey.6 In 

discussing both in this place and later the import of the data collected by this 

organization, it will not be necessary to contrast and distinguish between the views 

a Probably owing to the same agency which destroyed the supposedly equivalent series still exisiting in northern 

Utah and central Colorado, erosion prior to the Weber quartzite. 

b U. S. Geol. Expl. 40th Par., Rept., vol. 2, Descriptive Geology, 1877. 
40 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and statements set forth in this volume and in the resume by King of the results 

in systematic geology of the work of • this survey a published the year later, so far 

as they are in agreement. 

The work of the Fortieth Parallel Survey embraced a strip of territory adjacent 

to the fortieth parallel of north latitude, including considerable areas in northern 

Colorado and Utah. Here are dealings, not only with the eastern portion of the 

Uinta Mountains, which Powell described, but also with their western extension, 

which he had not carefully studied (Powell, p. 61), and of the Wasatch Range, which 

adjoins them on the west. 

The section of the. Wasatch Mountains which King uses as a reference section 

consists of the following formations:b 

Section of Wasatch Mountains. Feet. 

Permo-Carboniferous 650 

Upper Coal Measures 1, 700-2, 100 

Weber quartzite 5, 000-6, 000 

Wasatch limestone 7, 000 

Ogden quartzite I, 000-1, 500 

Ute limestone I, 000-2, 000 

Cambrian shales 75-600 

Cambrian quartzite 12, 000 

Lower Cambrian slates 800 

The lite limestone is reported as containing Quebec fossils. The Ogden quartzite 

has as yet furnished no fossils, but is referred to the Devonian on the strength of 

correlation with sections farther west, where its supposed equivalent is defined by 

fossiliferous horizons above and below. The Wasatch limestone is reported as having 

Devonian fornme in the lower part, with Waverly fossil's above and Coal Measure 

faunas running clown to 1,600 feet above its base. The Devonian species cited in the 

Wasatch Mountains are, however, few,e and occur also in the Waverly fauna. I 

have never seen any Devonian fossils from the Wasatch Mountains, and in one case 

at least (Rock Canyon, back of Provo) the very basal beds of the Wasatch limestone 

carry a Waverly fauna. There seems to me, therefore, to be no evidence for 

referring any portion of the typical Wasatch limestone to the Devonian. Farther 

west, however, in Nevada, in the Tucubits, White Pine, and other ranges, abundant 

and well-marked Devonian faunas are found, but the limestones in which they occur 

are evidently not the Wasatch limestone, but another formation underlying it, which 

is not found in the Wasatch section. From the Ruby and Egan mountains d faunas 

are cited as from the Wasatch limestone which have a peculiar facies that is believed 

to be distinctive of the limestones which come above the Weber quartzite in the 

a U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878. o Streptorhynchus inxquale and Proetus peroccidens, ibid., p. 177. 

b Ibid., p. 155. d Ibid., p. 203. 
RESUME OF LITERATURE. 41 

Wasatch Mountains; and it seems to me, therefore, that King's correlations of the 

Wasatch Mountain and Nevada sections are not to be relied upon. 

The facts at hand seem to indicate that the Ute limestone is probably of Ordovician age; the Ogden quartzite Devonian or older; the Wasatch limestone Mississippian in its lower portion, with more than half above Pennsylvanian; the Weber 

quartzite and overlying limestones Pennsylvanian. More recent collections taken 

from the Permo-Carboniferous of King have introduced an uncertainty as to whether 

this series is really Permian or Mesozoic. The component formations of the 

Wasatch Mountain section have not all the same distribution, for in Rock Canyon, 

back of Provo, I found Waverly fossils at the base of the Wasatch limestone only 

a few hundred feet' above thin blue limestones carrying Middle Cambrian trilobites. 

King describes the Paleozoic formations of the Uinta Mountains in the following 

terms: a 

" 1. A. series of siliceous beds 12,000+ feet thick, impure sandstones at the east 

end of the uplift, but gradually compacted into quartzite in the western portion of 

the range; these beds are intercalated with groups of clay shales and occasional 

conglomerate sheets which contain round rolled Archean pebbles. 

" 2. Conformably, as we believe, over No. 1 is a series 2,000 to 2,500 feet thick 

of mixed limestone, calciferous sandstones, and cherty limestones, showing great 

variability in the thickness of bedding, but prevailingly of heavy limestone near the 

base, with varying thin-bedded intercalations of lime and sand near the top, always 

capped with a zone of highly cherty Bellerophon-hearing limestones. From bottom 

to top the series is rich in Upper Coal Measures fossils. 

" 3. From 200 to 500 feet of calcareous shales and argillaceous rocks and clays 

intervening between the Coal Measures and Trias, conformable to both, and carrying 

Permo-Carboniferous fossils." 

The first paragraph of the preceding quotation refers to the great thickness of 

beds to which Powell gave the name Uinta sandstone. This Emmons traced westward and identified with the Weber quartzite of the Wasatch Range, and the name 

Weber formation is therefore frequently employed to designate it. In the second 

paragraph are collectively described beds which are discriminated by Powell as the 

Lodore group, the Red Wall group, the upper Aubrey group, and the lower 

Aubrey group. King frequently refers to this division under the name of the Upper 

Coal Measure limestone. The upper series described by King in the third paragraph 

must be the lower portion of Powell's Shinarump group. These two divisions are 

evidently supposed by King to represent the Upper Coal Measures and PermoCarboniferous of his Wasatch Mountain section. 

Several points of disagreement appear when the account by Powell of the geology of the Uinta Mountains is compared with the review by King of the same subject. 

One of these is the reference by the latter of a part of Powell's Shinarump group to 

a U. S. Geol, Expl. 40th Par., Rept., vol. 1, 1878, p. 153. 
42 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

th Carboniferous. The faunal list on page 146 of King's report comprises lifyalina 

(r sembling subguadrata), n. sp., Bakewellia parva, Pleuroph,orus sp., and 

erodon, sp. King remarks: "These are the only fossils obtained in Uinta Range 

fr m the easily eroded beds that separate the lower sandstones of the Trias from the 

Bellerophon cherts which mark \the uppermost horizon of the Coal Measures, and are 

interesting, since the forms as well as the physical condition of the beds are closely 

allied to the Permo-Carboniferous of Weber Canyon." The fauna does, indeed, tend 

to confirm King's correlation with the Wasatch section, but, as previously remarked, 

some doubt exists as to whether it belongs in the Permian or Mesozoic. Another 

less important instance seems to be the fact that King ascribes to the Upper Coal 

Measure limestone a thickness of but from 2,000 to 2,500 feet, while this is stated by 

Powell as 5,305 feet, if I am justified in combining the measurements of the upper 

Aubrey, lower Aubrey, Red Wall, and Lodore groups given by him on page 57. 

Furthermore, Powell describes a great unconforrnity as occurring at the top of the 

Uinta sandstone which he believes to be pre-Carboniferous in age. The geologists 

of the Fortieth Parallel Survey did not ascertain the unconformity noted by Powell. 

They refer this important formation to the Carboniferous, correlating it with the 

Weber quartzite of the Wasatch section. From the Weber quartzite a fairly satisfactory fauna is known, which proves the age of the formation to be beyond doubt 

Upper Carboniferous. As to the age of the Uinta sandstone, but little paleontologic 

evidence exists. Powell found it to be completely unfossiliferous, and the only fossils 

obtained by the Fortieth Parallel Survey were not found in place. They consist of 

a crinoid column, half of a ribbed brachiopod, somewhat doubtfully referred by Hall 

and Whitfield to 

or more beneath the top of the Uinta sandstone. 

horizon is believed to be about 700 feet below the summit, and certainly as much 

atus. The Spirifer imbrex 

Spirifer imbrex, 

was found upon the slopes of Mount Agassiz, and the 

and a well-preserved specimen of 

Spirifers of the imbrex 

Spirifer earnertype are 

unknown in the Devonian, and are especially characteristic of the Lower Carboniferous. It would hardly be safe to infer from this specimen more, however, than that 

the age of this horizon is probably Carboniferous, without reference to any division 

of the Carboniferous series. The crinoid column could not be taken to indicate much 

more than an age probably subsequent to the Cambrian, but in view of local facts of 

lithologic and stratigraphic occurrence, it may well belong to Carboniferous time. 

The Spirifer caim,eratus was found in a pebble of red jaspery quartzite near Geode 

Canyon, and its origin was evidently the Weber quartzite beds of the interior of the 

range, while the character of the matrix would indicate that the stratum in which it 

was deposited belonged to the middle of the series.a Spirifer eameratus is a distinctly 

Pennsylvanian species, and forms even resembling it are very rare in the Mississipa U. S. Geol. Expl. 40th Par., Rept., vol. 2, 1877, p. 290. 
RESUME OF LITERATURE. 43 

pian. Both Mount Agassiz and the upper Bear River Valley, where the crinoid 

column was obtained, are situated in the western part of the Uinta Mountains, but 

Geode Canyon is in the eastern part. Thus the paleontologic evidence is, as far as it 

goes, confirmatory of the stratigraphic correlation of the Uinta sandstone (at least in 

part) with the Weber quartzite. Inasmuch, however, as the Weber quartzite has a 

thickness of only 5,000 feet, while the Uinta sandstone measures over 12,000 feet, it 

would seem probable that the latter includes more than the Weber beds, 

At two points in the western end of the Uintas, fossils are cited from beds just 

above the Weber quartzite. King says: a "From the foothills of the range, near 

Kamas Prairie, were obtained, at a point evidently not far removed from the contact 

with the Weber formation, Productus semireticulatus, ASpir'ferina pulchra, Martina 

lineata." Spiriferina _pulch,ra is a peculiar form whose position should not be far 

above the top of the Weber, so that the faunal evidence confirms that derived from 

stratigraphy. Again, at Rhodes Spur, from the base of the Upper Coal Measure 

series, not far above the Weber beds, were obtained b Ch,onete8 granulifer, Jfartinia 

lineata, Syringopora multattenuata, Zaph,rentis, Lithostrotion, and _Euomph,alus. 

This list apparently indicates an Upper Carboniferous horizon, but recent collections made from this locality and horizon contain species which determine its 

age as Lower Carboniferous, and identify the horizon as the lowex part of the 

Wasatch limestone. If the list cited by King be considered in the light of this fact, 

it becomes evident that Chonetes granulifer, which is without doubt a misidentification, is really the only characteristic Upper Carboniferous form, Syringopora, 

Zaphrentis, Lith,ostrotion, and Euomphatu,s being rather indicative of the lower 

Wasatch, where they are common. It would appear, therefore, that in the western 

Uintas there are two siliceous series so similar lithologically that they were mistaken 

for the same in the rapid reconnaissance work of the King survey. One of these is 

very probably the Weber formation, as, indeed, King identifies it. The other is 

without much doubt pre-Wasatch in age, and represents the Ogden quartzite or some 

of the Cambrian quartzites, or both, wholly or in part. It is evident that the 

Wasatch limestone (the supposed upper Coal Measures of one outcrop) must 

intervene between the two supposed exposures of Weber quartzite. 

The 12,000 feet of Uinta sandstone of the eastern Uintas is suggestive, by reason 

of its thickness, siliceous character, and stratigraphic position, of the Cambrian 

quartzites, sandstones, and shales of the Wasatch section, which have a combined 

thickness of about 13,000 feet; but as the Cambrian of central Colorado, which is 

presumably a continuation of that in Utah, has a thickness of less than 1,000 feet 

it would be natural to suppose that in the Uinta Mountains the Cambrian would be 

a U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878, p. 147. 

b Ibid., p. 146. 

a Probably 600 feet in Peale's Eagle River section is the maximum. The thickness averages from 400 to 200 feet, and 

ranges to complete absence. 
44 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

somewhat intermediate in thickness, corresponding to its intermediate geographic 

position. 

The Mississippian was so uniformly a limestone-making epoch in the area of 

these Western States, of which the Madison, Wasatch, Ouray, Leadville, Red Wall, 

and other limestones are evidence, that I would hesitate to accept an unsupported 

correlation which would assign to this epoch sands and conglomerates in the area 

referred to. I would therefore regard the absence of any limestone series in the 

Uinta sandstone as evidence that none of its beds can be correlated with the Mississippian portion of the Wasatch limestone. If the horizon of the Mississippian 

Wasatch were conceived as coming below the Uinta sandstone, it is probable that the 

latter must be taken as the representative of the Weber quartzite, as King supposes. 

Under this hypothesis it would be necessary to account for the absence of the 13,000 

feet of Cambrian beds and 7,000 feet of Wasatch limestone, not to include the Ute 

limestone and Ogden quartzite, and for the great thickness of the Uinta sandstone, 

when its supposed equivalents, the Weber quartzite in Utah and the Maroon-Weber 

interval in Colorado, amount to only 5,000 or 6,000 feet. In the absence of definite 

knowledge, however, explanation of both these objections can be made. The upper 

portion of the Wasatch limestone, in amount 5,400 feet, is of Upper Carboniferous 

age and is not persistently a limestone. The probable equivalents of these beds in 

the Oquirrh Mountains contain considerable thicknesses of quartzite, and King 

instances several beds which in their lateral extension vary in an important Manner 

in the relative proportions of the calcareous and siliceous constituents (pp. 142 

and 143). It is not unthinkable, therefore, that the Pennsylvanian portion of the 

Wasatch limestone in passing eastward may lose its calcareous composition and 

become indistinguishable from the Weber quartzite. The beds would have a 

combined thickness of from 10,400 to 11,400 feet—not far from that of the Uinta 

sandstone. 

There can be little doubt that the earliest Pennsylvanian sediments were preceded 

by erosion, at all events in Colorado, for in Colorado the Mississippian portion of 

the Wasatch limestone, which has in Utah a thickness of 1,600 feet, is reduced to 

400 or 500 feet (Leadville limestone),a with visible evidence of erosion along its upper 

plane. In places it has even been completely removed. If the pre-Carboniferous 

quartzites of the Wasatch section have their equivalent in the Red Creek quartzite 

of the Uinta section, and if the Mississippian portion of the Wasatch limestone were 

removed by erosion and the Pennsylvanian portion joined with the Weber in the 

manner outlined, the difficulties incident to this hypothesis would be in large measure 

removed. 

If, on the other hand, the horizon of the Mississippian portion of the Wasatch 

be regarded as coming above the Uinta sandstone, the Red Creek quartzite would 

a 500 feet appears to be about the maximum for this formation, and part of it is of Devonian age. 
RESUME OF LITERATURE. 45 

probably be Algonkian, and the Uinta sandstone would represent the pre-Carboniferous quartzites of the Wasatch section. The Mississippian portion of the Wasatch 

must needs be absent and not represented by Powell's Red Wall, as is involved in 

his correlation of the Uinta bed with that in the Grand Canyon region, because 

Pennsylvanian fossils were found immediately above the Uinta sandstone, as preseems in full force in the east end of the range, must undergo to find its equiva 

might be urged the very rapid diminution in bulk, which the Uinta series, which 

tata 

lence in the really insignificant thickness of pre-Carboniferous sedimentaries of 

viously noted 

found near Ute Peak in the eastern portion of the range). As opposed to this 

(Spiriferin,a kentuckyen,sis, Serninula subtilita, and Meekella striaticoscentral Colorado. There is also the faunal evidence, very slender but not to be 

overlooked, which would tend to assign the upper portion of the Uinta sandstone to 

the Carboniferous (and if so, doubtless to the Upper Carboniferous); and the difficulty, 

in view of the correlation of the other Uinta and Wasatch formations sanctioned by 

by both stratigraphy and paleontology, of accounting for the Weber quartzite, which 

really has no lithologically similar correlate in the section of the eastern Uintas 

except the Uinta sandstone. 

A third hypothesis is also possible, and on the whole it seems to me to possess 

more advantages than the two others. It has been shown that the Mississippian 

portion of the Wasatch liMestone exists, with its characteristic fauna, in the western 

end of the Uinta Range, and that it there separates two quartzite series of very 

different geologic ages, but lithologically so alike that they were in one instance at 

least mistaken for one another. If the Wasatch limestone were removed - it is 

evident that these two formations would come in contact, and would form a series 

whose members it would be difficult to distinguish, except by most careful scrutiny. 

To suppose, then, that the upper part of the Uinta sandstone represents the Weber 

formation, and the lower the pre-Carboniferous, chiefly Cambrian, quartzites of the 

Wasatch section, would account for the correlation by King of the Uinta sandstone 

and overlying Carboniferous series with the Weber quartzite and Upper Coal 

Measures of the Wasatch section, for the probable occurrence. of Carboniferous 

fossils in the upper portion of the Uinta formation, for, the probable thinning of the 

Cambrian in its eastern transit into Colorado, and for other observed facts which 

have a bearing upon this problem. 

The faunal evidence is indecisive for any hypothesis, and is not conclusively 

favorable to that last advanced. As previously pointed out, the very scanty fauna 

so far obtained from the Uinta sandstone indicates that its upper portion is of Pennsylvanian age, and tends to corroborate the correlation by stratigraphy of that portion 

at least with the Weber quartzite. From the Upper Coal Measures, using King's 

term, of the Uinta Mountains but little paleontologic evidence exists. In the 
46 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Wasatch Mountains this division contains some striking and peculiar species. I 

collected Productus n,evadensis, Productus multistriatus, iSpiriferina pulch,ra, and 

several other forms, few of which probably are known in the Mississippi Valley, 

from this horizon in Weber Canyon. A somewhat similar fauna is cited by Emmonsa 

from Mill Creek Canyon--Spirifer cameratus, Spirifer octoplieatus, S_piriferina 

pulchra, and Prockctus subhorriclus. Some of these forms are cited from the same 

horizon in the Uinta Mountains. From the foothills bordering Kamas Prairie were 

obtained Productus semireticulatus, Spirtferina pulchra, and JWartinia lineata.5 

This locality, however, is in the western end of the range, and so far as known these 

interesting forms do not appear east of this point. In the eastern Uintas the fauna 

of the Upper Coal Measures, except for the Bellerophon limestone, which I shall 

speak of later, comprises only the usual Pennsylvanian types. From Zenobia Peak e 

are cited 

sp., 

tuckyensis, Seminula subtilita, 

this same locality,e 

Emmons also states that Marsh found at this horizon, and apparently very near 

Spirifer cameratus, Seminula subtilita, 

Spirifer lineatus 

Zaph,rentis stansburyir, Fenestella 

and 

and 

Spirifer ()Anus; 

Jfeekella striaticostata. 

and Phillipsia? 

near Ute Peak 

sp., Derbya crassa, Productus 

sp. These are from the 

Spiri‘ferina keneastern end of the range, and present no seeming departures from the usual faunas 

of the Mississippi Valley Pennsylvanian. 

A somewhat peculiar assemblage of species, however, is found in the Bellerophon limestone, which forms the upper limit of the Upper Coal Measures division 

of these authors, or the topmost bed of the Carboniferous of Powell and White. 

From this horizon at Vermilion Creek Canyon are cited!Fusulina sp., 11Tucula parva, 

Sedgwickia concava, Pleurotom,aria sp., Bellerophon carbonarius; from Section 

Ridge g Yuculana bellistriata, Schizodus curtus, Bellerophon, earbonarius, Orthoceras 

cribrosum, 11Taiadites sp.; from Geode Canyon a similar fauna!' It should be added 

ceras cribrosum is Dentalium 

that of the species cited Bellerophon carbonarius is Euphemus subpapillosus; Orth,ocf. camna, and Nuculana bellistriata is Leda cf. obesa. 

These stations are all situated toward the east end of the Uinta Mountains. Though 

this fauna is not cited from the western portion of the range, nor from the Wasatch 

Mountains, it should not be lost sight of that the horizon is believed to occur in that 

area. King says: i "The prominent capping cherty limestone is quite constant wherever in the Uinta a good section of the whole Coal Measure series is obtained, and it 

is to be considered as the dividing line between this group and the Permo-Carboniferous." This remark refers to the Uinta Range, while the following is made of 

Cottonwood Canyon, in the Wasatch Range:i "A continuous belt of limestone, about 

a U. S. Geol. Expl. 40th Par., Rept., vol. 2, p. 368. f U. S. Geol. Expl. 40th Par., Rept., vol. 1, p. 142; vol. 2, p. 274. 


bldem, vol. 1, p. 321; vol. 2, p. 147. g Idem, vol. 1, p. 144; vol. 2, p. 285. 


cIdem. vol. 1, p. 144; vol. 2, p. 287. h Idem, vol. 1, p. 145; vol. 2, p. 291. 


d Idem, vol. 1, p..145; vol. 2, p. 289. Idem, vol. 1, p. 143. 


e Am. Jour. Sci., March, 1871, p. 197. .1 Ibid., p. 171. 

RESUME OF LITERATURE. 47 

1,200 feet thick, is here exposed, of which the upper portion is rather finely stratified 

and shaly, and bears Bellerophon carbonarius." 

Another probable occurrence of this horizon is in W eber Canyon, mentioned by 

King on page 163 of Volume I. Furthermore, in a collection recently made in the 

western end of the Uinta Range a small fauna like that of the Bellerophon limestone, with similar lithology and stratigraphic position, was obtained. 

It seems probable, therefore, that this horizon extends from the eastern end of 

the Uinta Mountains westward into the Wasatch Range, and that the correlation 

made by the King survey of the Wasatch and Uinta sections is probably in the main 

correct. Yet the faunal and stratigraphic evidence alike are so insufficient that it is 

necessary to proceed with caution and to postpone a final decision until more data 

have been secured. 

The Paleozoic series in the Grand Canyon, as exemplified in the Kanab Canyon 

section, shows as striking an agreement with that of the Wasatch Mountains as does 

the section made out in central Colorado. The Cambrian is represented by quartzites, sandstones, and limestones, as in Utah, though the thickness is much less. The 

Cambrian is followed by a limestone of Ordovician age comparable to the Ute limestone, though always considerably thinner. Then succeed some sandy and limy 

beds which have been much reduced by erosion and are not persistent. They contain 

the remains of placoganoid fishes, and Spurr desires to correlate them with the Parting quartzite, which occupies a position in the Colorado section similar to that of the 

Ogden quartzite of ITtah.a Except for this brief series, the Devonian is unrepresented in either area, the succeeding formation in Kanab Canyon being the Red Wall 

limestone, which, like the Wasatch limestone of Utah, has a Mississippian fauna in 

its lower portion and a Pennsylvanian fauna in its upper. The Mississippian fauna 

of the lower Red Wall admits its correlation with some certainty with the similar 

portion of the Wasatch limestone. The Wasatch limestone, however, is greatly 

thicker than the Red Wall, and probably contains beds of Mississippian age which 

are wanting in the Grand Canyon region. 

The sandstones of the lower Aubrey and the limestones of the upper Aubrey, 

which next succeed, are suggestive of the Weber quartzite and Upper Coal Measures 

series of the Wasatch Mountains. I feel that the upper Aubrey can with some 

probability of correctness be correlated with the Upper Coal Measures of the Wasatch 

section, and Walcott's Permian in a general way with the Permo-Carboniferous of 

that area, though doubtless they may not have precisely the same boundaries. 

Whether the lower Aubrey represents the Weber, or, that formation being absent 

in the Grand Canyon, goes with the upper Aubrey to make up the southward 

extension of the Upper Coal Measures, is a point upon which it is impossible to form 

a U. S. Geol. Survey, Mon., vol. 31, 1898, p. 21. 
48 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

credible judgment. As a rule the formations in the Grand Canyon are very much 

thinner than those of the Wasatch Mountains, and are comparable rather to those of 

central Colorado, where an almost precisely similar succession of beds has been 

made out. 

In 1878 was published a report by C. A. Whitea upon an area in northwestern 

Colorado whose limits he describes in these words: "The district upon which the 

following report is made is included within the following boundaries: The eastern 

boundary is approximately upon a straight line drawn from a point where the 

meridian of longitude 107° 50' west from Greenwich crosses White River to where 

the meridian of 107° 25' crosses Yampa River. The northern boundary is the parallel 

of north latitude 40° 30'; the southern is the channel of White River, and the western 

the meridian of 109° 30'." (Page 5.) Regarding this area he goes on to say: "The 

districts surrounding the one here reported upon have, within the last few years, been 

geologically surveyed by different persons. That which adjoins it upon the west 

has been reported upon by Professor Powell in his ' Geology of the -Uinta Mountains.' 

A geologic map of the district which adjoins this one upon the north has been 

prepared by Mr. Clarence King during the progress of the United States Geological 

Survey of the Fortieth Parallel. Reports to be published simultaneously with this 

are in preparation by the other geologists of the United States Geological Survey of 

the Territories on the other districts which adjoin this one." (Page 20.) This statement has the appearance at least of being somewhat erroneous, as the maps of both 

King and Powell cover perhaps the greater portion of the area surveyed by White, 

and both bound it upon the north and west, but principally upon the north. 

White recognizes the following Paleozoic divisions, named in descending order: 

" No. 11. Upper Carboniferous.—Irregularly bedded light-yellowish sandstones, 

with occasional calcareous layers, the sandstone layers often containing masses and 

nodules of chert. Thickness about 600 feet. 

"No. 12. _Middle Carboniferous.—Compact bluish fossiliferous limestone, heavily 

or thinly bedded, alternating in some places with strata that are sandy and ferruginous. Thickness about 1,000 feet. 

"No. 13. Lower Carboniferous.—Massive layers of limestone alternating with 

those of sandstone and sandy limestone, all more or less ferruginous, generally presenting a reddish-brown aspect, and all usually regularly bedded. Thickness about 

1,500 feet. 

"No. 14. Uinta sandstone.—Massive or thinly bedded brick-red or more usually 

brownish-red sandstones; usually hard and often quartzitic. Thickness, exposed in 

this district, only about 400 feet; but the group reaches a thickness of nearly or 

quite 15,000 feet in the Uinta Mountains only a few miles from this district." 

Though for No. 14 of this section White uses the name " Uinta sandstone" in 

the extract above quoted, he elsewhere adopts from King the name "Weber quartza U. S. Geol. Geog. Surv. Terr., Tenth Ann. Rept., for 1876, pp. 3-60. 
RESUME OF LITERATURE. 49 

ite" for this series, and employs the term " Uinta group" as King uses it, for one of 

the Tertiary formations. 

In his table of correlated sections on page 22 White represents the Weber 

quartzite of his section as being the same as the Uinta sandstone of Powell's, his 

Lower Carboniferous the same as Powell's Red Wall, his Middle Carboniferous the 

same as Powell's lower Aubrey, his Upper Carboniferous the same as Powell's 

Upper Aubrey, and his Triassic( ? ), which lies above, the same as Powell's Shinarump, Vermilion Cliff, and White Cliff groups. 

Regarding the Lodore group, which Powell described as immediately overlying 

the Uinta sandstone, White remarks: "Furthermore, at all places in this district, as 

well as within a large area outside of t, the strata of the Lower Carboniferous rest 

directly upon the Uinta sandstone, those of the Lodore group being absent." (Page 

23.) And again: "Although the typical locality of the Lodore group which Professor Powell represents as existing at the base of the Carboniferous series and above 

the Uinta quartzite is near the northern border of the district here reported on, it 

does not occur within its limits." (Page 20.) If this is indeed the case, an overlap 

above the Lodore group is indicated, as well as an unconformity below it. 

White was associated With Powell in his geologic investigation of this general 

region two years previously (1875), and without doubt the correlation indicated is as 

accurate as may be. White also correlates his section with that of King, whose 

report had not then been published, and with whose work he was less closely in touch. 

He parallels his Weber quartzite with King's formation of the same name, his Lower 

and Middle Carboniferous with King's Upper Coal Measures, and his Upper Carboniferous with King's Permo-Carboniferous. The correlation was made relying upon 

advance sheets of King's map, unaccompanied by text, and in the case of the PermoCarboniferous and Upper Aubrey is without doubt erroneous. The Permo-Carboniferous of King, as previously remarked, lies above the bed taken by Powell as the 

top of his upper Aubrey. It is really part of Powell's Shinarump and the basal 

portion of White's Triassic. Therefore, not only the Lower and Middle Carboniferous 

of White, but the Upper Carboniferous as well, go to make up the Upper Coal 

Measures of King, which also includes the Lodore group where present. White 

assigns the Red Wall a thickness of 2,000 feet, and the upper and lower Aubrey each 

1,000 feet, in .the section on page 76 of Powell's Geology of the Uinta Mountains, and 

it would appear that the Red Wall and upper Aubrey were of diminished thickness 

in the new area. This is still more striking if the thicknesses in Powell's measured 

section (2,460 feet and 1,575 feet, respectively) be considered. The rather marked 

disparity between the thickness (2,500 feet) which King assigns to his Upper Coal 

Measures, and the 5,000 feet which are contained in the detailed section in Powell's 

report, has already been referred to. This is somewhat less marked accordingly in 

14364—No. 16-03-----4 
50 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the case of White's section, where these beds aggregate 3,100 feet, though this 

measurement excludes the Lodore group, which contains 460 feet. 

The upper portions of the Weber quartzite are described as so closely resembling 

the beds of the Lower Carboniferous as to make their satisfactory discrimination 

in some cases impossible. He says: " The Lower Carboniferous strata are often so 

very like those of the Weber quartzite in general aspect that a casual observer would 

be in danger of confounding one with the other, especially if the unconformity should 

be, as it generally is, slight or obscure." (Page 23.) Referring again to the unconformity which was reported by Powell as occurring at the top of the Uinta sandstone, 

and which, it will be remembered, the geologists of the Fortieth Parallel Survey 

were unable to verify, he remarks that it " is usually so slight as to be easily 

overlooked." (Page 23.) 

A resemblance similar to that which is reported between the Weber quartzite 

and the Lower Carboniferous, appears to exist also between the Lower and Middle 

Carboniferous, and in some cases, as in Yampa Mountain, the Lower Carboniferous 

is not satisfactorily separated from the middle group.-(Page 25.) The Upper 

Carboniferous group, on the other hand, is said to be easily distinguishable from that 

below. 

If the resemblance between these different strata is so great, may not, one is 

inclined to ask, the absence of the Lodore group be the result of a similar resemblance, owing to which it was merged unrecognized with the Uinta sandstone or with 

the Lower Carboniferous ? 

White cites no fossils from any of the Paleozoic formations recognized by him. 

None, indeed, seem to have been found in the Weber quartzite, which he provisionally places in the Silurian, following Hayden and Marsh, whose reference seems to have 

been equally unbiased by paleontologic evidence. (Page 23.) Carboniferous fossils 

were found in the three overlying groups, but these seem to haVe been altogether of 

Coal Measure or Upper Carboniferous type, Eocarboniferous or Mississippian and 

Permian faunas being absent. This inference seems to be justified from the discussion 

on pages 24, 25, and 26. White says in especial: " I shall regard all the groups that 

have been named in the foregoing sections and elsewhere in this report as purely 

stratigraphical divisions, and probably inseparable from each other on paleontological 

grounds." (Page 24.) Regarding the upper group he says: " Fossils are rare in 

this group, but a few have been found in its upper strata, and those yet known are not 

such as to distinguish it clearly from the other two Carboniferous groups." The 

groups below it " contain fossils that are as closely allied with the 

Permian of Europe as any that have yet been discovered in the strata of this upper 

one." (Page 26.) As the divisions recognized by White are entirely stratigraphic, 

the employment by him of names which have a more or less precise significance in the-
RESUME OF LITERATURE. 51 

geologic time scale is extremely unfortunate. Yet he seems to think that these names 

may have some vicarious significance in a palentologic sense, for he says: "The first 

of the following groups mentioned, however, is not to be here regarded as distinctively Subcarboniferous, although it may be so in fact, so far as anything is known to 

the contrary." (Page 25.) To understand this last expression in connection with 

what has gone before, it is necessary to bear in mind the belief held by this author that 

the Carboniferous divisions of Mississippian, Pennsylvanian, and Permian are not 

characterized by faunal differences as in the Mississippi Valley. Later paleontologic 

research, however, seems to substantiate the theorem that throughout the United 

States these three periods are distinguishable, where present, by characteristic 

faunas, and that these faunas, where in the same basin, are characterized in the main 

by the same assemblages of the same species as occur in the Mississippi Valley, and 

where in different basins, by assemblages of similar species. 

GRAND RIVER REGION. 

The great Carboniferous outcrop of the Uinta Mountains, with its outliers in 

Junction Peak and Yampa Peak, is described in the reports of White, Powell, and 

King, which have just been discussed. To the southeast of this, and separated by 

beds of Mesozoic and Tertiary age, occurs another large Carboniferous area of very 

irregular outline, which is seen chiefly along the valleys of White and Grand rivers 

and their afflilents. The southern part of this area is formed by the "peninsula" 

of the Elk Mountains, which is connected with the larger mass by a more slender 

Carboniferous outcrop along the western flank of the Archean Sawatch Mountains. 

For convenience this can be denominated the Grand River region, from the stream 

which divides it almost in the middle. As defined in a previous paragraph, however, 

the Carboniferous outcrops of the Elk Mountains do not form part of the Grand 

River region. 

The mountain region of central Colorado has been visited by many geologists 

and its geology described in a general or detailed manner, as the case might be, many 

times. Reconnaissance surveys were made by Peale, Holmes, Hayden, Marvine, 

and others of the Hayden survey, and by Stevenson of the Wheeler survey, and as 

it has become the scene of vast and varied mining enterprises it has been the subject 

of more detailed investigation by the United States Geological Survey in such works 

as the Leadville and Aspen monographs and the Tenmile and Anthracite-Crested 

Butte folios, and of many minor reports. The sections established in the four 

works last mentioned, from their detailed and accurate character, and because 

the constituent strata are grouped upon lithologic or fossil evidence into named 

formations according to modern usage, can conveniently be taken as sections of 

reference in the different areas in which they occur. The Crested Butte section 
52 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

would thus become standard for the Elk Mountain area, the Aspen and Tenmile 

sections for the Grand River area, and the Leadville section for the South Park area. 

The areas of the Aspen monograph and the Tenmile folio are both properly 

included in the Grand River region, but they are so marginal as to be geographically 

nearer related, the one to the Crested Butte, the other to the Leadville district. 

Nevertheless, I will consider the sections described in these reports, and use them as 

a basis of comparison with other geologic reports covering the Grand River region. 

The Paleozoic geologic section is remarkably uniform over this central Colorado 

area, and essentially the same subdivisions are recognized and essentially the same 

nomenclature is employed both in the four'monographic publications just mentioned 

and in many smaller papers of later issue which it will not be necessary specifically to 

consider. In the case of the publications of the Hayden survey and others of an early 

date, the system at present in use of discriminating lithologic groups and giving to 

them local names was not employed, and the strata were divided, if at all, into groups 

supposed to have a definite time value. As, however, paleontologic evidence was often 

deficient, and as the discrimination of these groups was frequently made on evidence 

more or less fanciful, and in a different manner by different geologists, the result is 

far from satisfactory. It is usually possible in these reports to identify by their 

faunal and lithologic characters certain horizons, such as the Sawatch quartzite, the 

Leadville limestone, the Maroon formation, etc., when they are mentioned, but seldom 

to determine satisfactorily, even 'in the few detailed sections which the early literature contains, what should be the limits in them of the formations now recognized. 

This is so far true that I have attempted a close correlation of these sections only in 

a very few instances. Much of the older literature, therefore, adds to our knowledge 

of the distribution of the formations or of geologic structure, with which I am not 

so much concerned, but not to the details of their lithology, paleontology, or mass. 

The geology about Leadville, especially with regard to its mining industries, 

was described many times in papers of the briefer sort before the Leadville monograph was published, and an almost equal number followed its appearance. In a 

similar manner much careful observation had been recorded, and the geologic section 

was almost as well known as it is to-day, when the Aspen monograph appeared. 

Lakes in 1887, Emmons, Siver, and Brunton in 1888, Henrich in 1889, Newberry in 

1890, and Carlyle in 1893, had all written accounts of varying length and excellence 

before Spurr brought his work to publication. But since his is probably the most 

authoritative account, as it is certainly the longest and most elaborate one, I will 

confine my discussion to it alone and neglect the claims of temporal priority. 

The section at Aspen, condensed from Spurr's monograph,a is as follows, 

descending: 

aU. S. Geol. Surv., Mon., vol. 31, 1898. 
 

RESUME OF LITERATURE. 53 

Section at Aspen. 

Feet. 

Gunnison formation: A gray or yellow basal sandstone, often calcareous, overlain by reddish, grayish, or variegated shaly sandTrias stones • 300 

Red sandstones: Light-red sandstone, more or less grading into the 

darker beds below 2,600 

Maroon formation: Impure grits, and thin-bedded, shaly limestone; 

calcareous and thin bedded at first, but more massive and arenaceous above; in color, a peculiar dark red 4,000 

Weber formation: Thin-bedded, carbonaceous limestones and calcaCarboniferous reous shales; the typical rock a black limestone; separated from 

the Leadville limestone by a distinct plane 1,000 

Leadville limestone: Above, a massive blue limestone 100 to 150 feet 

in thickness; below, a heavy, hard, gray-blue dolomite, .with some 

chert: thickness from 200 to 250 feet 350 

(Parting quartzite: This formation consists of thin beds of quartzite, Devonian (?) sandstone, dolomitic shale, and dolomite 67 

'Pure dolomites of a light gray-blue color, with some chert; the thick- Silurian ness varies from 250 to.400 feet, thickening southward 250-400 

A fine white quartzite, conglomeratic at the base; the upper third is 

dolomitic, sometimes glauconitic, and it graduates above into the 

pure dolomites of the Silurian 200-400 Cambrian Like the latter, this formation thickens to the southward, where it 

measures from 350 to 400 feet. In the north its thickness is 200 

feet or less. 

Granite. 

Besides the unconformity which is hinted at between the Leadville and Weber 

formations, Spurr mentions an important one which occurred at the close of the 

deposition of the red Triassic sandstones. "This break," he says (page 43), "was 

probably accompanied by a considerable uplift, for the succeeding beds of the 

Gunnison formation, which are of late Juratrias age, are probably of fresh-water 

origin. In the interval between the deposition of the red sandstones and shales 

there was probably some folding and perhaps a great amount of erosion. The red 

sandstones appear to be missing in part or wholly in certain areas which closely 

adjoin the Aspen district." 

The determination of the age of the Paleozoic beds is not based directly upon 

paleontologic evidence, for apparently fossils were not collected except in a few 

instances, but upon correlation with formations in areas near by whose age is more 

or less well established. From the Leadville limestone a number of foraminiferal 

types are mentioned, none of which, however, have come into my hands. a They .are 

of little importance in determining the age of this formation, which should without 

doubt be placed in the Lower Carboniferous. The Devonian age of the Parting 

quartzite depends upon some scanty and imperfect fish remains, and though this 

a Lakes cites from this formation at Tourtelotte Park Syringopora, Zaphrentis, Pleurotomaria, and Straparollus, and from 

Fryingpan Creek, Straparollus and Euomphalus. These fossils are among those studied by me and are referred to in the 

paleontologic section of this report (Colorado State School of Mines, Bienn. Rept. for 1886, 1887, p. 60.) 
54 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

determination may be correct, the occurrence- at Canyon of fish remains representing types commonly regarded as belonging to the Devonian detracts from the 

force of this evidence. 

The geologic section described in the Tenmile folio,a which is not strictly that of 

the Tenmige district itself so much as of the region immediately surrounding, may 

be condensed as follows: 

Section in Tenmile district. 

Feet. 

Wyoming formation: Principally sandstone of an intensely brickred color; limestones are practically absent. " If the Permian 

Trias? is represented in Colorado, the evidence of which appears to 

the writer as yet very uncertain, it would be included in these 

beds, which have evidently been deposited in direct and 

unbroken succession over the Upper Carboniferous" 1, 500 

Maroon formation: Coarse gray and red sandstone, sometimes 

conglomeratic, with many irregularly developed beds of limestone which are generally nonmagnesian; the formation is 

limited by the Robinson limestone below and the Jacque Mountain limestone above; both these limestones contain an invertebrate fauna of Coal Measures type 1,500 

Weber grits: Mainly coarse sandstone or grits, with a subordinate 

development of shale and a few thin and nonpersistent dolomitic limestones 2,500 Carboniferous Weber shale: Transitional between the massive limestone below 

and the grits above, and consisting of argillaceous and calcareous 

shale alternating with quartzitic sandstone 300 

Leadville limestone: A typical dolomite of bluish-gray or black 

color near the top and lighter colored near the base, passing 

upward into alternations of shale. and sandstone; it contains 

characteristic concretions of chert and is fosSiliferous near the 

top; sometimes much less but never more than 200 leet in 

thickness 200 

Parting quartzite: Siliceous beds, generally quartzites; these may 

possibly belong to the Devonian, but because of an unconformity 

at the top are left with the Silurian 15-60 Silurian 

Yule limestone: Light drab-colored, rather thin-bedded limestones, which are often magnesian and always more or less 

siliceous 120-160 

Sawatch quartzite: Remarkably pure, white, evenly bedded 

Cambrian quartzite, which is conglomeratic at the base and impure above, 

passing into argillaceous and calcareous shales 160-200 

The correlation of the Aspen and Tenrnile sections is indicated in the nomenclature employed for the formations. 

In his work at Aspen, Spurr notes a considerable thinning of the Sawatch quartzite 

to the north, and' although the Tenmile region is more to the east of Aspen than to 

the north, the Cambrian there is only about half its thickness at the former locality. 

In the shales at the top of this formation Cambrian fossils belonging to the Dikela U. S. Geol. Surv., Geol. Atlas U. S., Tenmile District Special Folio, folio 48, 1898. 
RESUME OF LITERATURE. 55 

locephalus fauna are said to have been found. The same is true of the Yule limestone, which though from 250 to 400 feet thick at Aspen only reaches 120 to 160 feet 

in the Tenmile district. Similarly also with the Parting quartzite, which measures 

67 feet in a typical detailed section near Aspen, while here it is said to be from 15 to 

60 feet. Emmons maps these beds as Silurian in the Tenmile folio. His position is 

best defined in his own words, And I quote as follows: 

" Near Leadville evidence has been found of an unconformity by erosion between 

them and the overlying beds. While no fossils have been found which would connect them with either the Silurian or the Carboniferous system, they have hitherto 

been mapped under the Silurian color, mainly because of this unconformity, which 

might account for the apparent absence of Devonian strata. 

"Within the last few years, however, Devonian fossils, principally fish remains, 

have been found in other parts of the Rocky Mountains in beds that occupy a stratigraphic position so closely corresponding to that of these q-tiartzites that it has become 

probable that the latter are of Devonian age also. Nevertheless, in the absence of 

direct evidence,, it has not been judged wise to designate them by Devonian color on 

the sheet showing structural sections." 

Like the earlier beds, the Leadville limestone is thinner in the Tenmile district 

than at Aspen, varying from 300 feet at the latter to 200 feet at the former, where it 

is sometimes much reduced. Emmons refers the Leadville limestone to the Mississippian period, and in this he is with little doubt correct. 

The Weber shale and the Weber grits are grouped in the Tenmile folio under 

the name of the Weber formation, which with the series of beds called here the 

Maroon represents the combined Weber and Maroon formations of the Aspen monograph. It seems fair to infer that the Weber shale of the one is the equivalent of 

the Weber formation of the other (Aspen). In this case also the decreased thickness 

of the Weber in the Tenmile region is a peculiar feature. It has there a thickness 

of 300 feet, while at Aspen it measures but little less than 1,000 feet. In the 

Tenmile folio the limestones of this formation are said to contain fossils of Coal 

Measure age, and our collections from both the Leadville and Crested Butte districts 

confirm this statement. 

The upper portion of the Weber formation of the Tenmile folio, or the Weber 

grits, as it is there called, must, along with the Maroon formation of the same 

report, represent the Maroon formation of the Aspen monograph. In the case of 

this formation the thickness, in marked contrast to the formations which preceded 

it, is the same in both the Aspen and Tenmile districts, being measured at 4,000 feet 

in both. The Maroon formation in the Tenmile district is divided from the Weber 

grits below by the Robinson limestone, and its upper limit is taken at the Jacque 

Mountain limestone. Both of the strata last mentioned are said to contain 

invertebrate faunas of Upper Coal Measure type. 
56 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In the Aspen district the Maroon formation graduates into a bright-red 

sandstone which Spurr refers to the Triassic. In the Tenmile district the Maroon 

formation is succeeded by a series of sandstones of an intensely brick-red color. 

These are correlated upon the evidence of their lithologic position with the Wyoming 

sandstone of the Front Range, the name being derived from the Denver Basin area. 

All the evidence except that of a paleontologic nature, since fossils have been found 

in neither formation, indicates that the Wyoming formation of the Tenmile district 

corresponds to the Triassic of Spurr's section at Aspen. The latter has a thickness 

of '2,600 feet in Lenado Canyon, while the Wyoming formation is but 1,500 feet 

thick; but as the Wyoming is immediately succeeded in the Tenmile area by 

Quaternary deposits, it is possible that it may have suffered erosion, and that this 

measurement does not indicate its original thickness. At Aspen the " Triassic" is 

overlain by the Gunnison formation, with an unconformity between, so that its 

thickness there also is probably not the original thickness. 

Spurr, as we have just seen, places this formation in the Trias, but Emmons 

groups it with the Carboniferous formations, remarking that " If the Permian is 

represented in Colorado, the evidence of which appears to the writer as yet very 

uncertain, it would be included in these beds, which have evidently been deposited 

in direct and unbroken succession over the Upper Carboniferous." From facts 

which I will discuss later, it seems to me rather more probable that the Wyoming 

formation is in fact of Triassic age. 

Aside from the two monographic works briefly discussed, but little has been 

written upon the Grand River region that calls for remark, although considerable 

literature of an occasional character centers about the mining camps of Aspen, Red 

Cliff, etc. 

Possibly before being diverted to the consideration of some of the earlier literature, it would be well to speak here of the geologic section at Red Cliff, which has 

been briefly described by Emmons (in 1886)a and by Tilden the year following.b 

Emmons speaks of the series as being practically the same as at Leadville. The 

Blue or Leadville limestone and the Cambrian quartzite are the same in both .areas and 

have the same thickness. The total thickness to the top of the Leadville limestone 

averages less than 500 feet at Red Cliff, as against 600 feet at Leadville. This is 

owing chiefly to the White or Yule limestone, while the Parting quartzite was not 

definitely recognized, though thin siliceous beds occur at about the horizon for it. 

Tilden's section, which was made at Battle Mountain, near Red Cliff, in Eagle 

County, is more detailed and runs as follows: 

«Colorado Sci. Soc., Proc., vol. 2, pt. 2, pp. 85-105. 


b Colorado State School of Mines, Bienn. Rept. for 1886, 1887, pp. 129-133. 

RESUME OF LITERATURE. 57 

Section at Battle Mountain, Eagle County.� 

Feet. 

Cambrian white quartzite 125 

Fine-grained sandstone 100 

Silurian white quartzite 5 

Conglomerate quartzite 8 

Blue dolomitic limestone 250 

Black siliceous limestone 300 

Carboniferous limestone 1, 000 

Leadville quartz-porphyry 200 

Over the ridge 1,000 feet and more of -Weber grits, sandstones, shales, and 

quartzites were found. 

Probably the four lower members of the section, aggregating 238 feet, should 

be considered as representing the Sawatch quartOte. This formation is 160 to 200 

feet thick in the Tenmile district, and in the ASpen district from 400 feet in the 

southern part to 200 feet or less in the northern part, so that Tilden's measurement 

is not excessive. The next two divisions, amounting to 550 feet, have the position and 

character of the Leadville limestone. If they be taken to represent the Leadville, however, no equivalent of the Yule and the Parting quartzite can be found. It is clear 

from Emmons's remarks that these formations are not normal at this locality. If a 

portion of the blue dolomitic limestone belongs' to the Yule, the Parting quartzite 

would still be missing. Tilden seems to suggest Oat the third member of the section, 

which he designates the Silurian quartzite, is the Parting formation. If this is 

indeed the case, the Yule limestone as such is absent. The next bed, consisting of 

1,000 feet of limestone, would appear to represent the Weber formation of the Aspen 

district and the Weber shale of the Tenmile district. The Leadville limestone and 

the Weber here are comparable in thickness, and seemingly in character, with their 

equivalents in the Aspen a and Peale's Eagle River sections. In the Tenmile district 

these formations have a thickness of but 200 and 300 feet, respectively. In the 

Crested Butte quadrangle they measure 400 to 525 feet and 100 to 550 feet, respectively. At Aspen, however, they attain a thickness, the one of 350 feet and the 

other of 1,000 feet, while on Eagle River their combined thickness is somewhere 

near 1,500 feet. 

The area assigned to Marvine in 1873° is a rectangle included between parallels 

39° 30' and 40° 20' north latitude and meridians 1p4° 45' and 106° 30' west longitude. 

In the southwestern co ner of this area is the most eastern portion of the Grand 

River. Carboniferous ar a, but apparently Marvine was not able to push his work 

into this tract, for I do of find it described in his report. In the year following 

his survey was extended to the area west of that which he examined in 1873. This 

territory Hayden descri ed in the following words:c "The main portion is bordered 

Not in thick ess in the case of the Aspen section, however. 

bU. S. Geol. eog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 83-192. 

c U. S. Geol. eog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 2. 
58 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

by the Park Range on the east, south by the Eagle and Grand rivers, and north by 

the Bear River. Westward the work extends nearly to longitude 108°." The area 

thus bounded includes within its limits the larger portion of the Grand River Carboniferous outcrop, and it is much to be regretted that owing to Marvine's untimely 

death his geologic report never reached publication. There is very little literature 

aside from this upon the geology of the Grand River area north of the line made 

by the Grand and Eagle rivers, and our information concerning it is almost restricted 

to such facts as are deducible from the maps of the Hayden Atlas of Colorado," 

together with the section (B, Sheet XVII), which passes just north of parallel 39° 

45' north, and from such inferences as may be framed from consideration of the 

geology of adjacent territory. From the maps and sections the Paleozoic rocks are 

seen to consist of Silurian, Lower Carboniferous, Middle Carboniferous, and Upper 

Carboniferous, the latter being followed by those of Triassic age. The character 

and thickness of these formations can not be ascertained from this source. 

Peale in 1873 was assigned to the South Park district,b which is defined as being 

limited on the north by the parallel of latitude 39° 15', on the south by parallel 38° 

30', on the east by the eighth guide meridian of the land survey, and on the west by 

the one hundred and seventh meridian. In 1874 Peale surveyed the territory to the 

north and west of this,c with the following boundaries: "Commencing Commencing at the' intersection of meridian 109° 30' and the Grand River, the line runs northeastward up the 

Grand River to the junction of the Eagle River; thence up .Eagle River to the 

mouth of Roche Moutonnee Creek; thence westward along the northern boundary 

of last summer's (1873) work to its intersection with meridian 107°; thence southward along the western side of last summer's work, approximately on the one 

hundred and seventh meridian, to parallel 38° 30'; thence westward on this parallel 

to the intersection of meridian 109° 30'; and thence northward on this meridian to 

the intersection of 109° 30' with Grand River." This area not only adjoins his own 

work on tie north, as has already been set down, but it is conterminous also with 

Marvine's district of the same year. 

During the operations of these two years Peale made several sections on Eagle 

River, which it.is of interest to compare with the sections of the Aspen and the Tenmile districts already considered. The most important of these sections appeared in 

three different forms. It was originally published in the annual report for 1873, 

where it is incomplete. In the report for 1874 it is repeated, with some additions, 

and in the report for 1875 it is summarized for comparison with other sections, 

similarly prepared, of different areas surveyed by the same author. In each case 

the series is subdivided, upon evidence more or less indifferent, into the great time 

a U. S. Geol. Geog. Surv. Terr. Geol. and Geog. Atlas of Colorado, etc., 1877. 

b U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 194-273. 

B U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874,-1876, pp. 73-180. 
RESUME OF LITERATURE. 59 

divisions which are supposed to be represented. I have repeated the section of 1874 

and 1875, returning it in the former case to its original continuous form, but 

retaining Peale's grouping. The following is the Eagle River section as it appears 

in the report for 1874: 

Section of Permian or Permo-Carboniferous strata on Eagle River. (After Peale.) a 

Thickness. 

Ft. In. 

7. Space probably filled with sandstones and shales reaching to the summit of the hill back 

from the bluffs, containing a thickness of about 500 0 

6. Rather coarse gray sandstones, in thin beds, fossiliferous and weathering of a rusty color_ 342 4 

5. Massive sandstones, generally of a gray color with a greenish tinge. 	 They are mostly 

fine grained and generally micaceous. Some of the beds are pebbly, and near the bottom is a band of black shale with carbonaceous material. This band is from 6 to 8 

feet in thickness. These sandstones are exposed in a bluff, in the upper part of which 

they are conglomeritic and darker in color than below 205 10 

4. Coarse gray sandstone with interlaminated shales 	 145 0 

3. Very hard, irregular-structured blue limestone, of a brownish color on weathered surface 	 10 0 

2. Greenish-gray micaceous sandstone shales, with bands of very hard sandstone 45 11 

1. Coarse white conglomerate 	 27 3 

Total thickness about 	 1, 276 4 

Section of Carboniferous strata on Eagle River. (After Peale. b 

Thickness. Ft. In. 

1. Pink conglomeritic sandstones 	 37 5 

2. Conglomeritic sandstones and gray shales 	 92 9 

3. Light-gray shales with hard sandstone bands 	 3 9 

4. Blackish micaceous shales 	 3 9 

5. Sandstones and interlaminated micaceous shales, some of the sandstones conglomeritic_ 367 2 

6. Sandstone conglomerate with pebbles of quartz from 1 to 2 inches in diameter. 	 This 


bed is the base of a bluff-like wall, and is •10 feet in thickness. Above are beds of 


shale and coarse sandstone in alternation. On top is a greenish micaceous sandstone_ 252 0 

7. Coarse, grayish sandstone, with interlaminated shales; near the top is a layer of red 

sandstone, succeeded by a conglomeritic layer 	 25 1 

8. Fine-grained, reddish-brown sandstone 	 27 4 

9. Coarse-grained, hard sandstone, spotted with green, general color gray 	 4 0 

10. 	White and greenish-gray conglomerates and shales. First we have a conglomeritic 

sandstone, and then green micaceous shales with black carbonaceous layers; followed 

by more conglomeritic layers, above which is about 15 feet of hard sandstone, with 

interlaminated soft shales; then 5 feet of compact gray micaceous sandstone. Next 

are very soft greenish-gray micaceous shales, extending for about 10 to 12 feet of 

alternating shales and sandstone (some of the latter conglomeritic) in beds from 2 to 

4 feet in thickness. Above these are conglomeritic sandstones with shales in the 

center. The total thickness is about 511 0 

11. Coarse white sandstone, with a band of hard fine-grained sandstone near the top. The 

micaceous character is marked between the layers 40 

all. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rep't., for 1874, 1876, p. 118. b Ibid., p. 115. 
60 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

Thickness. 

Ft. In. 

12. White conglomeritic sandstone 	 5 0 

13. Red conglomeritic sandstone 	 38 8 

14. Dark-red micaceous shaly sandstones 	 6 8 

15. Brownish-red sandstones, conglomeritic 	 30 10 

16. Fine-grained sandstone, generally white, but becoming pink in places, with two or three 

layers of gray micaceous shale, each from 2 to 4 inches thick 4 0 

17. Coarse white sandstone, with grains of quartz and some decomposed feldspar 71 3 

18. Soft greenish sandstone in fine layers, with a few hard bands, each a few inches in 

thickness 	 99 3 

19. Red sandstone 	 11 4 

20. Brownish sandstones 	 99 8 

21. White granular brown-spotted sandstone 	 8 0 

22. Greenish-gray micaceous sandstones, partially conglomeritic 	 352 0 

23. A space in which the beds were so much concealed that it was impossible to make a 

detailed section; the upper portion is probably filled with a prolongation downward 

of the micaceous shales and sandstones, while the base is limestone. In the latter I 

found Aviculopecten, Pleurophorus, and an Avicula or Bakevellia. The total thickness 

of strata as indicated by the space is. 	 408 4 

Total thickness of supposed Carboniferous 	 2, 504 20 

The remainder of the section to the beds I included in the Devonian? is as follows: 

Feet. 

24. A laminated trachytic rock 	 15 

25. Space probably filled mainly by limestones a 1, 000-1, 500 

26. Black, flinty limestone, with pieces of pyrite and fragments of Spirifer or Spiriferina} 

Section of Silurian strata on Eagle River. (After Peale.) b 

Ft. In. 

7. Light-bluish limestones on weathered surfaces, white and yellow. It is in bands from 

3 to 8 inches thick, with a cross fracture and nonfossiliferous. A great portion of 

these limestones are probably magnesian. At the top they are crystalline 219 6 

Calciferous group: 

6. Space, in the upper portion of which there is an outcrop of metamorphosed conglomerate, 

seemingly composed of pieces of white quartzite and brown sandstone. The masses 

are irregularly shaped. The outcrop is only a few feet in thickness and the remainder 

of the space is probably filled with sandstones and quartzites, with perhaps a few shales. 

The space was so covered that the beds were all concealed. The entire thickness is 68 4 

5. Milk-white quartzite, similar to that of No. 1 	 4 9 

4. Space probably filled with sandstones 	 22 8 

3. Grayish-brown laminated sandstones with a greenish coating and mud marks on the 

surfaces of the laminm 98 6 

2. Fine-grained, rather compact, glauconitic sandstone, somewhat laminated, dark brown 

and greeilish gray 	 10 0 

Primordial group: 

1. Milk-white quartzite 	 400 0 

Gneiss: 

Total thickness of Silurian about 	 819 9 

a Estimated. 8 U. 8. Geol. Geog. Surv. Terr., Eighth Ann. Rept., for 1874, 1876, p. 113. 
RESUME OF LITERATURE. 	 • 61 

In the same volume is published another series of sections made on Eagle River 

at a point considerably below the foregoing, which represents the higher beds of the 

series, as that does the lower ones. 

Section of Jurassic, head of second canyon, Eagle River, -oath side. (After Pale. a 

Thickness 

in feet. 

1. Space probably filled with sandstones and marls, about 	 500 

2. Laminated sandstones and blue limestones 

190 

3. Light-yellowish brown sandstone 

4. Blue limestone 	 50 

5. Gray shaly sandstones with interlaminated marls and thin bands of blue limestor.e 200 

Total about 	 940 

Section of Triassic on Eagle River at second canyon. (After Peale.) b 

Feet. 

8. Massive light-colored quartzitic sandstone 	 10-20 

7. Red sandstones somewhat laminated 

300 

6. Pink quartzitic sandstone 

5. Red sandstones, more massive than the lower layers, although there is some lami nation ____ 375 

4. Coarse white sandstone 5 

3. Red and brown laminated sandstones, some of the layers being seemingly calcareous 193 

2. Purplish sandstones 15 

1. Red sandstones, somewhat laminated 70 

Total thickness 978 

Section of Permo-Carboniferous. (After Peale.) c 

Feet: 

1. Gypsiferous shales and sandstones. The gypsum occurs in great quantity an is rather 

impure. The sandstones are laminated and generally of a pink or red co or. I was 

unable to get the exact thickness, but the outcrop was from 500-800 

2. 	Shales, sandstones, and limestones, alternating colors, pink, brown, gray, yel ow, white, 

cream color, and blackish. These beds are best shown on the north side o the river. 

They incline generally about 60°. In some places they are inclined past t e vertical, 

especially in the upper portion. The thickness is about 500 

3. 	Pink, brown, and gray shaly sandstones with interlaminated thin beds of blu o limestone. 

These beds resemble those I noticed in 1873 in South Park, which are given i the report 

of 1873, in sections 9, 10, and 11. The thickness on Eagle River is about 200 

Total thickness 	 1, 500 

The first section contains beds referred to the Silurian, Car oniferous, and 

Permian; the other to the Permian, Triassic, Jurassic, etc. It is not clear from the 

context that the Permian portion of the latter is continuous with tie Triassic and 

the Jurassic series, but this appears to be the case. The following is the summarized 

a U. S. Geol. Geog. Bury. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 119. b Ibid., p. 122. c Ibid., p. 125. 
62 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

section, based apparently upon both of the foregoing ones, which he published in 

the annual report for 1875. It includes only strata believed to belong to the Eocarboniferous, Coal Measures, and Permian. There appear to be important departures 

from the original section from which the summary was derived. 

Generalized section on the Eagle River, district of 1874. (After Peale) .a 

PERMIAN. 

Feet. 

Micaceous sandstones and gypsiferous shales of varieghted colors, with thin beds of limestone at 

the base. Fossils: Calamites suckovii, C. gigas, Stigmaria ficoides, Spinfer, Procluctus, Orbicula _ _ 2, 000 

COAL MEASURES. 

White, greenish, and reddish, laminated, micaceous sandstones and black shales, with patches 

of carbonaceous material; near the base are limestones, b with Avicula, Aviculopecten, 

Pleurophorus 2, 500 

SUBCARBONIFEROUS. 

Limestone, somewhat shaly above, but massive as we descend, about 500 

Total 5, 000 

The first section quoted was made, as I have already stated, along the upper 

portion of the Eagle River, the Carboniferous beds being chiefly exposed near the 

mouth of Roche Moutonnee Creek. This section is northeast of the Aspen district 

and northwest of the Tenmile district, the three points forming a triangle with nearly 

equal sides. This section is subdivided into a Silurian,. a Carboniferous, and a 

Permian series, with the possibility that ,a thin Devonian series may be 'included 

with the Carboniferous. In the section quoted it is apparent that the lowest group, 

consisting of 400 feet of quartzite, which Peale refers to the Primordial, is the 

Sawatch quartzite of the Tenrnile and Aspen sections, and that the 200 feet of 

magnesian limestone at the top of his Silurian section, which is otherwise unclassified, 

belongs to the Yule limestone. The question then presents itself of the disposition 

of the 200 feet of siliceous beds which he refers to the Calciferous group. It is 

possible that the bed of glauconitic sandstone which Peale cites just over his 

Primordial quartzite can be correlated with a similar bed which Spurr described as 

occurring in the upper portion of his Cambrian quartzite. The two beds agree 

with singular closeness in thickness, lithologic character, and stratigraphic position.' 

The strata which overlie the glauconitic quartzite at Aspen and are transitional to 

the Silurian dolomite are also similar to the Calcifefous group of Peale's section.d • 

a See sections, Report of 1874, pp. 115-119. 

b This layer may possibly be Subcarboniferous [Peale]. 

a Spurr calls attention to the wide extent of this glauconitic horizon on page 7 of the Aspen monograph, Mon. U. S. 

Geol. Surv., vol. 31, 1898, 

The upper, transitional portion of the Sawatch quartzite of the Tenmile district is not unlike Peale's Calciferous 

group, although very much thinner. The latter also resembles the lower or quartzite member of the original Yule. 
RESUME OF LITERATURE. 63 

The most satisfactory course seems to be to consider the latter an xpansion of the 

upper or transitional portion of the Sawatch quartzite. Described s it is in Peale's 

section, this series would hardly be regarded as part of the Yule imestone of the 

Aspen section. At all events, the siliceous beds at the base of the section have a 

greater development on the Eagle River than either at Aspen o in the Tenmile 

district. The Yule limestone, though thicker than in the latter a ea, is somewhat 

thinner than at Aspen. Taken together, the Cambrian and Siluri n beds, 823 feet 

in thickness, are slightly in excess of the combined maximum mea urements of the 

two series at Aspen, and greatly more than their combined meas rements in the 

Tenmile district. It would appear that the lower portion of the s ction, especially 

the siliceous part, is thickening rapidly toward the northwest. This inference 

receives confirmation from a remark by Pealea to the effect that " t ere was a much 

greater development in Mr. 1Vlarvine's district." This statement refers to the 

Silurian beds, under which term it must be remembered are included both the 

quartzitic and the calcareous strata mentioned above. 

The limestones at the base of the Carboniferous portion of the ection occur just 

above those given in the section of the Silurian. The lowest of these evidently 

belongs to the Leadville limestone, and the beds above, which app • ar to be mainly 

calcareous, must represent the Weber formation or Weber shales of t e oth6r sections. 

In spite of the fact that Peale says, referring to beds 25 and 26, that "The remainder 

of the section to the beds I included in the Devonian ? is as follows," indicating that 

the Devonian occurred below bed 26, it is quite clear from remarks on the opposite 

page5 that beds 25 and 26 are the ones which are regarded as belongi g to this period. 

The reference of these beds to the Devonian seems to be largely hypothetical, and is 

in part certainly erroneous, while it may be in part also correct. 

I am satisfied, from the lithologic character, the position in the section, and to a 

certain extent from the fossils, that bed 26, whose thickness is not given, is the 

Leadville limestone of later reports. This formation is known a so many and so 

widely separated localities to contain a Devonian fauna in its lower portion that it is 

probable the same occurrence will be found at this point also. 

Bed 22, from its lithologic character and relative position, can •afely be referred 

to the Maroon formation, or Weber grits, as it is alternatively ca led. As the 408 

feet of beds immediately below, which are said to be concealed fo the most part, 

consist of micaceous shales and sandstones in the upper portion, ith limestone at 

the base, it seems probable that a portion of bed 23 also belong• in the Maroon. 

From the limestone is cited a fauna which is probably of Upper C rboniferous age. 

As the Leadville limestone contains a Mississippian fauna it is necessary to conclude 

that the base of 23 belongs in either the Weber or the Maroon formation, the age of 

a U. S. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 110. b Ibid., 114. 
64 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

both being Upper Carboniferous. It seems probable that beds 26, 25, and possibly 

also a portion of 23, represent the Leadville-Weber interval, using the term Weber 

as it is employed in the Aspen monograph. This leaves the formation without any 

determinable boundaries and with a thickness only approximately determinable. 

Beds 25 and 26 have a combined thickness of from 1,000 to 1,500 feet; and if to this 

be added 100 or 200 feet from the base of 23, we obtain 1,200 to 1,700 feet as the 

approximate thickness of the Leadville and Weber formations. In the Aspen district 

these formations have an aggregate thickness of 1,350 feet, while in the Tenmile district their thickness is only 500 feet. It thus,appears that Peale's Eagle River section 

in the matter of the two formations mentioned above is close to the Aspen section, 

but differs widely from that of the Tenmile district. 

The remainder of Peale's Carboniferous series, with an aggregate thickness of 

about 2,300 or 2,400 feet, corresponds in position and character to the lower part of 

the Maroon formation of the Aspen district. There seems to be, however, a much 

smaller proportion of dark-red or brownish members. This series also is similar to 

and probably represents the Weber grits of the Tenmile district, and as the thickness is nearly the same in each case, it may be that the horizon taken by Peale as the 

top of his Carboniferous series about corresponds to the line dividing the Weber 

grits from the Maroon formation of Emmons's section. 

The Carboniferous series continues upward into one which Peale calls Permian. 

The evidence for this reference, consists of three species of plants, one of which is 

exclusively Permian, the two others being especially Coal Measure, though ranging 

up to or into the base of the Permian. As the evidence of invertebrate fossils found 

elsewhere at the same horizon a indicates that the geologic age is not Permian but 

tipper Carboniferous, it would be desirable to have the paleobotanical evidence 

reviewed and a larger flora collected. Of the Permian, in the section under consideration, Peale gives 1,276 feet before the top is reached. This Permian series is 

lithologically similar to that called Carboniferous, and like it, I believe, represents 

the Maroon formation, belonging to the upper portion, which was not differentiated 

by Spurr, but to which Emmons restricts the name Maroon. 

Peale's other Eagle River section, made near the second canyon, comprises series 

referred to the Permian, Triassic, Jurassic, etc. The two Permian sections are by 

no means strikingly similar lithologically, and I doubt if any more than the basal 

portion of the second corresponds to the top of the first. Possibly they are even 

entirely superimposed. Indeed, Peale remarks b that " Farther down Eagle River, 

where the Red Beds are present, the strata immediately beneath are so changed that 

I could not positively recognize any of the beds of the section made further up the 

a Probably about the Rico formation of the San Juan and the upper Maroon of the central part of the State. 

bjU. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 118. 
RESUME OF LITERATURE. 65 

river." So far but about 3,600 feet have been correlated with the Maroon formation, 

which at Aspen has a thickness of 4,000 feet, as the equivalent series has in the 

Tenmile district. It is quite clear to me that strata are included in the Permian 

of the lower Eagle River section that are higher than the highest of the Permian of 

the upper section, but just how great a thickness, if any, is equivalent, and whether 

the superjacent portion belongs to the Maroon formation or to the Red Beds, are 

questions difficult to answer. I shall return to this point presently. 

Peale's Dakota group seems to correspond to that to which Spurr applied the 

same name at Aspen. His Jurassic is marked by characters similar to those of the 

Gunnison formation of that region, and I think that they will be found to be equivalent. If, as seems probable, the unconformity which preceded the Gunnison in the 

Crested Butte and Aspen regions was present where Peale obtained his section, it 

appears to have escaped his notice. Peale's Triassic is the well-known Red Beds 

series, and can probably be correlated in a general way with the Triassic of the Aspen 

and with the Wyoming sandstone of the Tenmile district, but the former has a thickness of 2,600 feet, and the latter of 1,500 feet, while Peale's Triassic, which is represented only in the lower Eagle River section, measures less than 1,000 feet. If, 

however, to this series be added the upper portion of that which underlies it, called 

Permian by Peale, the thickness becomes more normal, viz, 1,500 to 1,800 feet; and if 

we can grant that the lower part of the Permian of this same section, whose upper part 

has been joined with the Triassic, is not really the equivalent of the Permian of the 

upper Eagle River section, but largely overlies it, the equivalent of the Maroon will 

be increased from 3,600 to 4,300 feet. It is objectionable to depart from the author's 

grouping of these beds, but by doing so in this case greater uniformity in the lithology and thickness of the different formations is attained. Peale himself has made 

equally wide departures in his summarized section published in the annual report for 

1875, apparently with the object of bringing this section into a closer agreement with 

those of other areas. In this section he refers 500 feet at the base to the Eocarboniferous. This division is clearly that to which a thickness of 1,000 to 1,500 feet 

was earlier given, and which was doubtfully referred to the Devonian (beds 25 and 

26). The Coal Measures division of the summarized section comprises without doubt 

beds 1 to 23 of his early Carboniferous section (section No. 2, page 115). To the 

Permian of the summary section a thickness of 2,000 feet is ascribed, while of the 

earlier Permian sections one has 1,500 feet and the other 1,276 feet. The upper portion of the summarized section evidently corresponds to the top of the Permian of the 

lower Eagle River section. The increase of 500 feet in the later reference must have 

been arbitrarily made, or else have been justified by adding to the base of the section 

on the lower Eagle River some portion of the Permian of the upper Eagle River 

section. This is the course which I have allowed myself in the foregoing discussion. 

14364—No. 16-03 5 
66 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Proceeding in the manner already outlined, the combined Leadville and Weber 

formations, according to Peale's sections, would have an approximate thickness of 

from 1,200 to 1,700 feet. Assuming 300 feet for the Leadville limestone (this 

formation measures 350 feet at Aspen and 200 feet in the Tenmile district), and 

accepting about the mean of the measurements for the combined thickness of the two 

formations, in the neighborhood of 1,000 feet would then have to be assigned to the 

Weber formation. The Maroon, according to the above calculations, measures about 

4,300 feet, and the Wyoming 1,500 to 1,800 feet. 

Comparing the Carboniferous formations in the three sections discussed, it is found 

that their relative thickness is as follows: Leadville limestone, at Aspen 350 feet, on 

Eagle River 300 feet (assumed), in the Tenmile district 200 feet; Weber formation, 

at Aspen 1,000 feet, in Peale's section 1,000 to 1,200 feet, in the Tenmile district 300 

feet; Maroon conglomerate and its equivalents, at Aspen 4,000 feet, in Peale's section 

4,300 feet, in the Tenmile district 4,000 feet; Wyoming formation, at Aspen 2,600 

feet, in Peale's section 1,500 to 1,800 feet, in the Tenmile district 1,500 feet; the 

upper limit of the Wyoming formation being an unconformity in each case. The 

total thickness of the Upper Carboniferous would then be, at Aspen, 7,600 feet; in 

Peale's section, about 7,500 feet, and in the Tenmile district 5,800 feet. The greatest 

variation in individual formations appears to be in the case of the Weber and 

Wyoming formations. The Maroon remains remarkably constant in thickness, 

though apparently very variable in lithologic detail. The Leadville also varies 

proportionately in thickness, being at Aspen nearly twice as much as in the Tenmile 

district. Variations in the thickness of the constituent formations and of the mass 

as a whole may be due to erosional unconformities, one of which followed the Leadville, while others possibly intervened between the Triassic and the Maroon and 

between the Weber and Maroon formations. 

Stevenson's report for the One Hundredth Meridian Survey a upon his district in 

central Colorado covers much of the area which was worked by Marvine, Peale, and 

others. He describes several sections made in the Grand River, Elk Mountain, and 

South Park regions, one of which (that on the forks of Eagle River) must have been 

taken very near the outcrops which furnished Peale's section just discussed. Just what 

streams are intended to be indicated by the north and south forks of Eagle 

River I have not been able to ascertain, but the section must be located, as I have 

said, very near that which Peale worked out on Eagle River near the mouth of Roche 

Moutonnee Cfeek. 

The exposures of the Silurian are said to be exceedingly fine on the South Fork 

of the Eagle River, and to differ little from those of Bald Peak. They appear to 

consist of massive, dark quartzite, which rests upon granite (page 360). No detailed 

a U. S. Geog. Geol. Expl. Surv. W. 100th Mer., Rept., vol. 3, 1575, pp. 303-501. 
RESUME OF LITERATURE. 67 

section is given. Apparently here, as in the Elk Mountains, Stevenson did not see 

or did not record the light-colored Yule limestone which usually intervenes between 

the Sawatch quartzite and the Carboniferous. 

The Carboniferous section, according to Stevenson, possesses characters which 

were uniformly observed over all the area examined. Referring to the s etion on 

the forks of Eagle River, he remarks: "As exhibited there and elsewhere, t e succession seems to consist of, first, a group of sandstones resting on a thick imestone 

and holding beds of gypsum interstratified with thin limestones; second, r sting on 

No. 1, a group of limestones and coarse sandstones; third, above all a grea mass of 

coarse sandstone, in which no beds of limestone were seen." (Page 362.) pplying 

this to the detailed section of the rocks exposed on the forks of Eagle River ( age 368), 

it appears that the upper division, bed 1 of the section, is about 2,500 feet in thickness; the middle division, beds 2 to 20, inclusive, 500 feet in thickness; and t e lower, 

beds 21 and 22, about 2,000 feet in thichness. But it must not be supposed hat with 

bed 22 the bottom of the section is reached, for he says (page 370): ith this 

stratum, which is not more than 200 feet above the bottom limestone, the easured 

section closes." The "bottom limestone" of this quotation is probably that escribed 

on page 362 as the thick limestone upon which the major portion of t section 

rests. This heavy limestone series must, I think, include the Leadville li estone as 

one of its members, with possibly the limestones of the Weber formation in its 

upper portion and the Yule limestone at its base. The three groups of strata overlying it appear to belong to the Maroon formation. 

Stevenson apparently missed the Red Beds altogether in making this se Lion, for 

(1) he does not recognize any Triassic series in this area, by which name he lsewhere 

distinguishes the Red Beds; (2) he remarks no discrepancy between this section 

and the Carboniferous sections of the Crested Butte region, where the Red Beds 

are apparently wanting; and (3) he compares the upper portion of the section of the 

Sangre de Cristo Range, in which no strata belonging to the Red Beds are included, 

with the upper portion of his section on the forks of Eagle River.a I therefore 

conclude that Stevenson saw no equivalent of the Wyoming formation in making 

this section; that if he had he would have referred it to the Triassic; any that the 

recognizable portions of his section can be referred to the Leadville limeston • and the 

Maroon formation. He probably did not distinguish any beds equivale t to the 

Weber limestone. 

The whole series of Stevenson's section above the basal limestone a i pears to 

belong to the Maroon formation, and is equivalent to the Carbonifero s (bed 1 

to the middle of bed 23) and Permian of Peale's upper Eagle River section, with 

probably the lower 700 feet of the Permian of the lower Eagle Rive t section. 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Suppl., p. 74. 
68 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Apparently the upper portion of Peale's series, including the gypsum beds, is not 

represented in Stevenson's section. Peale states a that the gypsiferous series on 

Eagle River which Stevenson refers to the Carboniferous is the same which he himself reported as Permian or Permo-Carboniferous. This can, however, hardly be 

the case, as Stevenson's gypsiferous series is at the bottom of his section, while 

Peale's is naturally at the top. The thickness given by Stevenson, which *amounts 

to 5,000 feet, is greater than that of the corresponding beds in Peale's, Spurr's, or 

Emmons's sections,b and there is a more or less marked lack of agreement in detail 

between his section and the others mentioned, though this is to be expected in all 

save Peale's. Compared with the Aspen section, that given by Stevenson represents 

the Maroon formation, but at Aspen the Maroon is 4,000 feet thick and the calcare 

ous beds are chiefly confined to the lower portion, while Stevenson found them in 

the middle portion and assigned to the whole a thickness of 5,000 feet. The series 

which Stevenson divides into two great sandstones with an intermediate calcareous 

group must apparently be correlated with the Weber grits and Maroon formation 

of the Tenmile folio. In the latter their combined thickness is given as 4,000 feet, 

while in Stevenson's section it is said to be 5,000 feet. Limestones appear to be 

much more abundant in the Tenmile district than in the section at the forks of Eagle 

River, and are especially characteristic of the upper portion, in which, in the latter, 

none were seen. This only proves, besides possibly a slight exaggeration, in Stevenson's measurements, the great variability in lithologic details from point to point of 

this series of sediments. Stevenson has stated that the general description which I 

have quoted above, holds good for the great area surveyed by him. It is true that 

the generai features are very persistent and that the sequence almost everywhere 

consists of a heavy limestone below and a great series of sandstones, with shales and 

thin limestones, above. But the other points mentioned are not constant. Stevenson usually seems to find, it is true, gypsum beds in the lower part of the sandstone 

series, an occurrence not often mentioned by other geologists, but the abundance 

and position of the limestone beds, upon which the subdivisions made by the latter 

depend, appear to be features of great varrability. 

Stevenson remarks upon the conglomerate which forms the downward termination of his measured section on the forks of Eagle River that this bed is " somewhat altered, but in all other respects resembles, the conglomerate seen at the head 

of Taylor River." This expression evidently refers to the section in the Elk 

Mountains described on page 365 of his report, where a conglomerate is recorded as 

a U. S. Geol. Geog. Surv. Terr., Ninth Ann. Rept., for 1875, 1877, p. 73. 

b It is more in agreement with the Maroon of the Crested Butte quadrangle, which measures 4,500 feet, though here 

may be included probably inconsiderable portions of altered and unrecognizable Wyoming sandstone. Stevenson calls 

attention to the similarity of the upper division of his Eagle River section to the upper division of that in the Sangre de 

Cristo Range. The latter in its lithologic character strikingly resembles the upper Maroon of the Crested Butte district. 

All three have the same thickness, 2,500 feet (U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supplement, 1881.) 
RESUME OF LITERATURE. 69 

overlying 100 feet of shale and sandstone which rests upon 150 feet of limestone. 

The suggestion conveyed is that the "bottom limestone" which un erlies the 

arenaceous series in the section on the forks of Eagle River, and wh. h I have 

already inferred to be the basal calcareous member of the generalized Car i oniferous 

section as recognized by Stevenson, corresponds to the limestone forming tthe base of 

the section on the West Fork of. Taylor River. The character of these limestones is 

such as to support the belief that they belong to the Leadville limestone. 

In 1876 Endlich was given the White River district for geologic e anfination 

and report.° "To us," he says, " had been assigned the region lying est of the 

[White River Indian] agency, bordered on the north by. the White Ri er, on the 

west by longitude 109° 30' west, on the south by north latitude 40°, and joining on 

the east with the district of the late Mr. Marvine (1873) along a line of bout 107° 

45' west."6 This area includes only the western margin of the Grand Rive Paleozoic 

region. 

The oldest beds exposed in this district are the Red Beds, or Juratr as. These 

are said to rest conformably upon the Carboniferous, which outcrops ex i • nsively in 

Marvine's district to the east. Endlich's account is very brief and may b: condensed 

into few words. According to him the Trias consists of massive beds o red sandstone which have a thickness at one point of 2,000 feet and are overlain by a series 

of gray shales and marls interstratified with thin beds of sandstone. The latter 

apparently represent the Gunnison formation of the Crested Butte qua angle, but 

the massive white sandstone at the base of the Gunnison is not differentiat • d here, or, 

at all events, is not distinguished by Endlich. The Triassic itself I am isposed to 

believe the same as the Lenado Red Beds and the Wyoming formation i f the Tenmile district. The Lenado Triassic is reported as 2,600 feet in thicknes , while the 

latter measures 1,500. On the other hand, Endlich states of the Red Be s that " In 

no manner were they observed to differ particularly from those obse ed on the 

eastern slope of the Front Range. Most likely their vertical developme i t is somewhat larger here than there, but in all lithological and stratigraphical f :attires they 

agree closely." The occurrences on the Front Range I have supposed uo represent 

the Wyoming, and possibly, in local sections, part of the Maroon format ons. 

ELK MOUNTAIN REGION. 

The only piece of detailed geologic work in the Elk Mountains in whi h a section 

is established suitable for use as a basis of compf9ison with the less compl • to observations of the several reconnaissance surveys whi h have visited this reg on is Folio 

9 of the Geologic Atlas of the United States.' 

aU. S. Geol. Geog. Surv. Terr., Tenth Ann. Rept., for 1876, 878, pp. 61-159. 


b Ibid., p. 63. 


e U. S. Geol. Surv., Geol. Atlas of the U. S., Anthracite-Cr ted Butte Folio, Colorado, folio 9, 1894. 

70 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The Paleozoic geologic section in the Crested Butte quadrangle, as given in the 

Anthracite-Crested Butte Folio, is as follows: 

Paleozoic section in Crested Butte quadrangle. 

JURATRIAS. Feet. 

Gunnison formation: The upper two-thirds drab, green, yellow, and pink clays, with thin 

limestone. The base is a heavy white qUartzite 350-500 

CARBONIFEROUS. 

Maroon conglomerate (upper portion): Conglomerate and sandstone in heavy beds. The 

material chiefly derived from the Archean and partly from the earlier Carboniferous beds. 

Occasional thin beds of fossiliferous limestone 2,500 

Maroon conglomerate (lower portion): Quartzose conglomerate, grit, and sandstone with 

varying amount of pebbles derived from the Carboniferous, which sometimes form the bulk 

of the deposits. Color yellowish gray. There are thin, interbedded limestone layers. 

These and the limestone pebbles are fossiliferous 2,000 

Weber limestone: Dark gray to black shale, with thin limestones carrying black chert 100-550 

Leadville limestone: The upper third massive, blue, and cavernous. The lower two-thirds 

bedded, gray to brown. Dark cherts 400-525 

SILURIAN. 

Yule limestone: At the top, 80 feet of green, pink, and yellow shale and thin limestone. The 

middle portion massive gray limestone with white chert. Lower portion white quartzite 

75 to 100 feet thick 350-450 

CAMBRIAN. 

Sawatch quartzite: The upper two-thirds red quartzite containing glauconite. The lower 

two-thirds quartzite with conglomerate at the base; pebbles of white quartz 50-350 

ARCHEAN. 

Granite, gneiss and schist. 

An unconformity is indicated at the base of the Sawatch quartzite, another 

between the Weber and Leadville limestones, and a third at the top of the Maroon 

conglomerate. 

The geologic sequence in the Crested Butte quadrangle appears to be in the 

main very similar to that at Aspen which I have discussed on the pages devoted to 

the Grand River region; and as the most probable correlation between the two is 

indicated by the nomenclature employed for the formations of the two sections, as 

well as in the text of the monograph, no discussion on my part is called for except in 

one or two instances. Spurr found that in his ai•ea the Cambrian and the Silurian 

beds became thicker toward the south, but, contrary to what one would expect from 

this, the Cambrian of the Crested Butte quadrangle is thinner than that of the Aspen 

region. The Silurian, however, is a trifle thicker. The combined thickness of these 

formations appears to be about the same in both areas. 
RESUME OF LITERATURE. 71 

The Parting quartzite was not recognized as a distinct formation in the Crested 

Butte quadrangle, but seems to be represented there in the upper part of the Yule 

formation. Spurr states:4 "Mr. Eldridge has described what is also evidently the 

equivalent of these beds in the Crested Butte area thus: The upper division, 60 to 90 

feet thick, consists mainly of green, yellow, red, and white shales, with more or less 

arenaceous and calcareous layers, the latter passing into thin limestones. The persistence of its general lithologic character renders this horizon easily recogiilzable." 

The Leadville limestone is proportionally much thicker in the Crestd Butte 

quadrangle than at Aspen, while the Weber formation is, on the other timid, much 

thinner. The Maroon formation is about the same in each, being a little t icker in 

the Crested Butte quadrangle. It is possible that the discrimination bet een the 

Weber and Maroon formations was not made at precisely the same horiz n in the 

two areas, and at all events the combined thickness of these formations i in close 

agreement, being 5,000 feet near Aspen and from 4,600 to 5,050 feet in th Crested 

Butte quadrangle. 

Spurr seems to feel satisfied that the beds which he calls Gunnison for i i ation in 

the Aspen district are the equivalent of those bearing the same name in the Crested 

Butte quadrangle. The described character and occurrence of the two se ies tend 

to corroborate this view. A similar probability surrounds the correlati r n of the 

Maroon formation in the two areas. In the Crested Butte quadrangle th Maroon 

conglomerate is succeeded by the Gunnison formation with an unconformity • etween. 

In the Aspen region, however, beds having the character of the Maroon pas upward 

without apparent break into a series otherwise somewhat similar in char. cter, but 

colored a brighter red. It is this formation which at Aspen is followed by he Gunnison preceded by its unconformity, as in the Crested Butte quadrangle. It seems 

from this that we have at Aspen a series of considerable thickness which is not represented in the Crested Butte region, a fact to which Spurr calls attent on.b Its 

absence in the Crested Butte quadrangle can hardly be accounted for in ny other 

way as satisfactorily as by ascribing the conditions there prevailing to the unconformity owing to which the Gunnison formation in that area, we are told, rests sometimes upon the Maroon conglomerate and in some cases upon older forma ions. It 

is possible, however, that this series may actually occur in the Crested But e region, 

but so changed by metamorphism as to be unrecognizable. In the souther i part of 

the region, however, where the upper portion of the Maroon is thinner an has not 

been altered, its absence is nearly certain. 

Aside from the Anthracite-Crested Butte folio, but little has been wri en about 

the geology of the Elk Mountains which closely concerns the subject in ha t d. 

Perhaps the earliest account of geologic exploration in this region was that puba U. S. Geol. Surv., Mon., vol. 31, 1898, p. 20. b Ibid., p. 38. 
72 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

lished by Ruffner in 18714, the geology being described by F. Hawn. One of the 

routes traversed by Ruffner's reconnaisance in the Ute country crosses the southern 

end of the Elk Mountains. The descriptive treatment, as one might expect from 

the rapidity with which the party must have traveled, consists of little more than 

mere notes, and 1 am unable to recognize with certainty the different rock groups 

distinguished in the Anthracite-Crested Butte folio except in one instance, where 

Coal Measure fossils are cited from an exposure of shale and sandstone some 200 

feet thick, near the mouth of Spring Creek (p. 78). These probably belong to the 

Weber formation, and in that case the heavy limestone just below is the Leadville 

limestone. The Carboniferous age of all the beds both here and elsewhere in which 

Coal Measure fossils were obtained was recognized by Hawn, but in the Elk 

Mountains it seems from the context (p. 83) impossible to avoid the conclusion that 

he referred the anthracite coal seams, at the head of Anthracite Creek, to the same 

period. 

The field of work assigned to Endlich for the season of 1873 was styled the San 

Luis region. His report for the year b deals chiefly with the line of Paleozoic outcrops along the Mosquito and Sangre de Cristo ranges, but he also discusses portions 

of the Front Range and Elk Mountain areas. Of the Paleozoics in the latter area 

coming under Endlich's survey I shall here briefly speak. The series in the Sangre 

de Cristo and Front ranges are considered elsewhere. 

The Gunnison River, cutting through the Elk Mountains, dissevers their southern end, which, under the name of Fossil Ridge, forms an area of Paleozoic outcrop 

distinct from the larger body north of the river. The geologic sequence at Endlich's 

station 38, which is situated on Fossil Ridge, is described as follows: 

"The lowest members that can well be distinguished are about 320 feet of light 

gray to bluish to almost white limestones, with quartzitic segregations characteristic 

to the strata of that horizon, and sparse remains of crinoids. Although the identification is necessarily not a very thorough one, these beds have been referred to the 

Silurian. Above that follow 80 feet of yellow and gray shales, regarded as Devonian; then 175 feet of variegated shales, partly sandy, with isolated banks of limestone, 

weathering smoothly, with a steep face; 260 feet of light-gray and yellowish limestones follow, interstratified with narrow bands of shale, and partly altered so as to 

appear like marble; the whole is covered by 40 feet of light shales, separated from 

45 feet of the same material by a 20-foot stratum of dark-blue Carboniferous limestone full of fossils, etc. Upon this follow 150 feet of light-blue and yellow limestones, .dolomitic in part, etc. Single bands of quartzite appear also, and almost all 

the strata contain a few fossils. Overlying these are 50 feet of yellow, reddish, and 

whitish shales without any fossils, etc." 

a Rep. Reconnaisanee in the Ute Country in 1873, by Lieut. E. H. Ruffner. Washington, 1874. 43d Cong., 1st sass., 

House Ex. Doc., No. 193. 

b U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 305-357. 
RESUME OF LITERATURE. 73 

This series, which is reported as almost identically the same as that north of the 

canyon, both in thickness and in lithology, allows itself to be correlated with comparative ease with the formations recognized in the Crested Butte quadrangle. The 

Sawatch quartzite, it is clear, is wanting, or, more probably, occurs below the lowest 

strata described. These consist of 320 feet of light-colored limestone with chert 

concretions, and they, with little doubt, represent the Yule limestone. The yellow 

and gray shales next above, which have a thickness of 80 feet, are the equivalent of 

beds of a similar character which in the Crested Butte quadrangle occur at the top 

of the Yule limestone, and which, it will be remembered, Spurr correlates with the 

Parting quartzite. The variegated shales which follow also suggest the upper portion 

of the Yule limestone, but to so identify them would give this formation an almost 

excessive thickness. All the succeeding formations, except the last, probably belong 

to the Leadville limestone. The dark-blue limestone with Carboniferous (?) fossils 

at least almost certainly does. The age of the fauna is not clearly indicated by the 

faunal list given by Endlia. It is compared, perhaps upon the authority of Meek, 

with the fauna from Mystic Lake, which is of Mississippian age. On the other 

hand, the general make-up rather suggests the Devonian fauna of the Ouray limestone. The Rhynch,onella, "which has a decidedly Devonian aspect," I suspect to 

be Camarotoechict endlich,i. It is now known that both Devonian and Carboniferous 

faunas are found in the Ouray limestone, and it may be that the material collected 

in this case was a mixture from both horizons. At all events, in the limestone in 

the Elk Mountains identified with the Leadville limestone, Devonian and Carboniferous faunas occur similar to those from the Ouray limestone in the San Juan 

region, and the two formations can evidently be correlated. The occurrence in the 

limestone of Fossil Ridge of a fauna suggesting the same horizon, corroborating as 

it does the indications arising from geographic proximity and stratigraphic succession,, makes it highly probable that we have a recurrence of that very persistent 

formation. There is, however, much more shale associated with the limestone than 

is known elsewhere, and the lithologic character of the series seems to be more like 

that of the Weber limestone. 

The enormous area of Stevenson's survey in 1873 a included portions of the Elk 

Mountains in Colorado. The Silurian he found to be well represented. I have 

quoted his description of these rocks at length, but while his remarks incite speculation they lend little aid toward arriving at a conclusion. He says (page 360): 

" On Taylor River, at its head and along the west side of Taylor Park, as well 

as at its southeast corner, the Silurian rocks are well exposed, underlying the 

Carboniferous. So, also, at the head of Tumichi Creek. Throughout this region it 

seems to be almost entirely free from limestones, and the sandstones give no evidence 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, pp. 303-501. 
74 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

of calcareous matter. At the head of Taylor River the following section, descending, 

was obtained: 

Feet. 

1. Sandstone, very dark, somewhat vesicular in portions; contains much calcspar and some iron 

ore. It is not at all certain that this is Silurian. In many respects it is more nearly allied 

to the Carboniferous above 20 

2. Sandstone, completely converted into quartzite; fine grained, light gray 20 

3. Shale, arenaceous above, white on fresh fracture, bright buff , on weathered surface; below 

quite argillaceous, with layers of cone in cone, and in parts quite micaceous 1 18 

4. Sandstone, quartzite, coarse above, fine below; contains much chert, usually in lenticular 

nodules, but sometimes united so as to form continuous layers; this chert is mostly bluishblack, but occasionally light colored and dendritic; geodes of quartz are numerous, 1 to 3 

inches in diameter. The stratum is very thick bedded 75 

5. Sandstone, slightly altered, grayish yellow, fine grained, micaceous, shaly, with thin films of 

quartz along cleavage planes 45 

6. Sandstone, on top completely altered, and for 20 feet has fracture like flint, is perfectly smooth, 

without grain, but shows clearly the lines of deposition; color, bluish white. Lower down 

is less altered, and the rock is a coarse-grained, compact sandstone. At the base is a conglomerate quartzite, the pebbles being usually as large as a pea. This stratum rests < upon 

coarse granite • 70 

"At the head of Taylor Canyon No. 4 is quite light in color, and the chert is 

almost white, while at the head of Tumichi Creek it is as described in the section 

above. At the head of the canyon No. 5 is greatly increased in thickness, and is of 

Venetian-red or burnt-umber color, and has the same character where exposed along 

the headwaters of Tumichi Creek. Along the old, miners' trail from Taylor to East 

River this section is occasionally seen, and differs from that given above only in 

that No. 3 becomes quite calcareous, being at one locality an argillaceous limestone. 

Nos. 3 and 5 are very characteristic and persistent throughout this region. In the 

southern portion of this area the Silurian has always been thin. On the lower 

portion of Tumichi Creek and at two localities west from the Indian agency isolated 

exposures are seen where erosion has removed the overlying eruptive rocks. The 

rocks here belong wholly to No. 6 of the section above, and have a total thickness of 

not more than 70 or 80 feet." 

The thickness of this series, which aggregates only 248 feet, and its generally 

siliceous character, would lead one to believe at first that the whole section represents 

the Sawatch quartzite alone. On the other hand, it is peculiar that there appear to 

be no cakareous beds below the Carboniferous suitable to be referred to the Yule 

limestone. It is possible that Stevenson grouped the Yule limestone with the Carboniferous limestone, but this can not be ascertained from his descriptions. On the 

other hand, the lithologic sequence when closely compared with the section of the 

Crested Butte quadrangle is somewhat strikingly similar, though the measurements 

given by Stevenson are in every case considerably less. The lowest bed, No. 6, is 

lithologically quite like the basal member of the Sawatch quartzite. No. 5, which 

at the head of the canyon is reported as having a Venetian-red color, resembles the 

upper member of the Sawatch quartzite. No. 4 is similar to the basal portion of the 
RESUME OF LITERATURE. 75 

Yule limestone. No. 3, which is said to be calcareous at one point, may represent 

the middle division of the Yule, but the upper division, that which Eldridge mentions as being especially persistent, and which Spurr correlates with the Parting 

quartzite, appears to have no equivalent in Stevenson's section, unless No. 3 represents it, instead of the middle division. The surprising variability of these beds as 

described by Stevenson half leads one to doubt the accuracy with which they were 

identified at different points, in view of the rapidity with which the work must have 

been carried on. Stevenson's beds 1 and 2 seem to have no representatives in the 

Crested Butte section on the scale of the comparisons which have just been made. 

It seems more likely, therefore, that the varied series described by Stevenson is 

really only the Sawatch quartzite.a It is significant also that he in no instance 

describes beds which have the character and position of the Yule limestone. 

. The different beds mentioned by Stevenson suggest some of those described by 

Endlich in the San Luis district, but a detailed comparison would not be profitable. 

If the whole of Stevenson's section represents the Sawatch quartzite, a parallel to the 

calcareous and shaly portion (No. 3) seems to be cited by Endlich, who says (page 

308) that sometimes the quartzites at the base of his section are represented by 

calcareous beds. 

Stevenson gives two sections of the Carboniferous in the Elk Mountains, one 

near the head of Rock Creek (page 363), which I take to be the Rock Creek on the 

west side of the Elk Mountains, having its sources near Sopris Peak, and the other 

at the head of the West Fork of Taylor River. The relation of the Carboniferous 

beds at the latter locality to the Silurian section is not given, whether it follows 

directly or with an interval between. 

The three beds of limestone at the base, aggregating 140 feet in thickness, are 

with little doubt the Leadville limestone, while the shale above it has the position 

and many of the characters of the Weber formation as described in the AnthraciteCrested Butte folio. With the conglomerate, just above, the Maroon formation 

probably begins. Above the 100 feet of conglomerate and sandstone which are 

supposed to form the base of the Maroon conglomerate there follows an interval of 

unknown extent, which is succeeded by the section near the head of Rock Creek 

previously mentioned. This interval is occupied principally by coarse sandstones. . . ." The Rock Creek section consists of sandstones, thin limestones, and 

some shale. The thickness, aside from beds 16-25, which are Cretaceous (page 365), 

amounts to 1,475 feet, but as there is a repetition in the Cretaceous beds, there may 

be one, though it is not obvious, in the Carboniferous also. All these strata belong 

evidently to the Maroon formation. 

a In this area the Maroon formation sometimes rests upon the Archean and occupies the position of the Sawatch 

quartzite. It is possible that an occurrence of this sort may have introduced a complication into this discussion. 
76 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Stevenson recognized no Triassic in this area, which is in accord with the 

mapping of the Crested Butte quadrangle. 

The area of Peale's survey in 1873 embraced large areas of Paleozoic outcrop in 

central Colorado, and in chapter 4 of his report a a description of the geology of the 

Elk Mountains is given. Owing to the complicated geologic structure of this region 

and the absence of detailed geologic maps, of detailed sections of any length, or of a 

general section, it is difficult for the reader to gain an understanding of the extent, 

character, and thickness of the geologic sequence there shown. Bearing in mind, 

however, the sections given in the Anthracite-Crested Butte folio and the Aspen 

monograph, it is possible here and there to identify with the formations recognized 

in those works the strata described by Peale. Apparently the geologic sequence is 

maintained with reasonable constancy over all the area surveyed. 

In the quartzite which he refers to the Silurian the Sawatch quartzite can be 

recognized, while the Yule and Leadville limestones can frequently be identified in 

his descriptions. His Jurassic is the Gunnison formation. I can not but think 

that for the most part his Triassic, Permo-Carboniferous, and Carboniferous, except 

such portion of the latter as may belong to the Weber and Leadville formations, are 

the Maroon formation of the Anthracite-Crested Butte folio. As pointed out by 

Emmons and Spurr, the bright-red sandstones which in the Aspen region are found 

to follow the Maroon formation and are referred to the Trias in the Aspen 

monograph have not , been recognized in the Crested Butte quadrangle. Presumably they are wanting over the southern portion of the Elk Mountains. Wherever 

this formation is not present (and considerable of Peale's work lay in the southern 

portion of the range) his Permian and Triassic belong in the Maroon formation. 

It is possible that farther north his Triassic may be equivalent to the red sandstone 

previously mentioned, which I take to represent the Wyoming formation of the 

Tenmile folio. The fact is of interest, to which Spurr calls attention,b that the 

Triassic sandstones on Woody Creek were mapped by the Hayden survey as 

Carboniferous. 

In narrating his observations during the field season of 1875 c this author compares the section observed that year in the Dolores River region with other previous 

sections. In so doing he compiles a generalized section for the Elk Mountains, 

which is more readily intelligible than the fragmentary ones of the original report. 

This section I will quote as follows:d 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, l p. 193-273. 

bU. S. Geol. Surv., Mon., vol. 31, 1898, p. 38. 

c U. S. Geol. Geog. Surv. Terr., Ninth Ann. Rept., for 1875, 1877, pp. 29-101. 

dU, S. Geol. Surv., Mon., vol. 31, 1898, p. 77. 
RESUME OF LITERATURE. 77 

Generalized section in the Elk Mountains district of 1873.a (After Peale.) 

PERMIAN. 

Feet. 

Maroon-colored sandstones and shales, with conglomerate at base. No fossils. Thickness not estimated 

COAL MEASURES. 

Yellowish-gray and reddish sandstones and shales, with bands of limestone. Lower part 

of series is gray and greenish micaceous sandstones. Fossils. Third layer (top), 

Loxonema, b Productus muricatus, Spirifer; second layer, Productus muricatus, Athyris 

subtilita, Rhynchonella osagensis, Hemipranites crassus, Terebratula bovidens, Retzia punctulifera; first layer, Productus muricatus � 1, 300-2, 000 

SUBCARBONIFEROUS. 

Limestones and limestone shales. Beds so distorted that thickness not positively taken. 

Fossils of Subcarboniferous type not yet examined 

[Total] 4, 000-4, 500 

The most appropriate sections with which to compare the foregoing are those of 

the Crested Butte quadrangle and of the Aspen district. It is clear that the lowest 

member of Peale's section represents in a general way the Leadville limestone, but 

it may also include the Weber formation, for the lowest beds of the " Upper. Carboniferous," just above those from which the fossils are cited, probably belong to the 

Maroon conglomerate. This is the conclusion at which I have arrived from a study 

of the original detailed section given on page 251 of the Annual Report for 1873. 

Both the Carboniferous and Permian of Peale's generalized section of 1875 seem to 

belong in the Maroon formation, at least so it appears from the lithology of the upper 

beds and the thickness of the lower ones. The Permian, however, Peale correlates 

with the Permian of the Dolores River, the Eagle River, and the Park Range. Upon 

one hypothesis the Coal Measures and Permian combined of the Elk Mountains section are equivalent to the Coal Measures and the lower portion of the Permian of the 

Dolores River region, the boundary in one case passing above the Permian and in the 

other through it. Upon another hypothesis the Permian of the Elk Mountains, supposing it to have the same limits as the upper division of the Maroon, is missing in 

the Dolores River region, the Coal Measures and the lower part of the Permian of the 

latter being equivalent to the Coal Measures of the Elk Mountains. 

The real equivalent of most of the Permian (and of most of the Triassic) in the 

Dolores section seems to be the bright-red sandstone described by Spurr from Lenado 

Canyon in the vicinity of Aspen. This formation is apparently not found at all in 

the Crested Butte quadrangle, and probably not at all in the southern portion of the 

aSee pp. 21, 225, 230, 232, 247-264, report of 1873. 

bin modern terminology these forms are of course Loxonema, Marginifera muricata, Spirifer, Marginifera muricata, 

Seminula subtilita, Pugnax utah, Derbya crassa, Dielasma bovidens, and Hustedia mormoni. 
78 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

Elk Mountains. Wherever Peale cites the Permian or the Triassic from this region, 

therefore, the beds probably form part of the Maroon formation. Farther north 

the beds so denominated may be equivalent to the "Lenado" sandstone on the one 

hand and in a more or loss general way to this author's Permian and Triassic in other 

areas. Accordingly, thus qualified, the Permian of the Elk Mountains combined 

with the Carboniferous represents the Carboniferous and Permian of the Eagle 

River, with the exception of the upper 800 feet of the latter. This, together with 

the Triassic, would accordingly be equivalent to Spurr's Triassic about Aspen and to 

Peale's Permian and Triassic in the Elk Mountains wherever, if at all, these do not 

belong in the Maroon. Similarly, the Permian and Carboniferous combined of the 

Elk Mountains are equivalent to the Permian and Carboniferous of the Park Range, 

both representing the Maroon formation of the Crested Butte quadrangle. The 

Triassic of the Park Range, according to my view, is the same as Spurr's Triassic at 

Aspen, and probably has no equivalent in Peale's Elk Mountain section except, 

perhaps, sporadically. 

The reports by Hayden and by Holmesa (chapters 5 and 4) upon explorations in 

the Elk Mountains during the year 1874 are descriptive in character and devoted to 

a discussion of the structural rather than of the historical geology of the area. One 

can recognize in their descriptions the Sawatch quartzite, the Maroon conglomerate, 

and the Wyoming sandstone, but the observations recorded are of a general character, and while agreeing with the section described in the Anthracite-Crested Butte 

folio add little or nothing to it except perhaps in the matter of distribution of the 

formations. Both authors speak of the gradation through the Red Beds into the 

well-established Carboniferous, and as a result of this circumstance and of the complicated geologic structure the Red Beds are united with the Carboniferous under .a 

single color in the geological map accompanying their report. In the present 

instance the term Red Beds is employed for the bright-red "Triassic" series, the 

maroon-colored series being correctly referred to the Carboniferous ,(p. 62). 

SOUTH PARK REGION. 

Though situated at the extreme northern end of the Mosquito Range, the 

Leadville section would naturally be selected to compare with the less formal 

reports of earlier work dealing with the South Park region. Except for a few 

changes in the matter of formation names, the section described in the Leadville 

monograph b is practically the same as that of the Tenmile folio, which, though that 

area is almost contiguous with the Leadville district, has been considered in connection with the geology of the Grand River region. Both the Leadville monograph 

aU, S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, pp. 54-58 and 59-71. 

b U. S. Geol. Surv., Mon., vol. 12, 1886. 
RESUME OF LITERATURE. 79 

and the Tenmile folio, as is well known, are the work of the same geologist. The 

geologic section in the Leadville district may be condensed as follows (p. 58 et seq.): 

Section in Leadville district. 

CARBONIFEROUS. Feet. 

Upper Coal Measures: Base taken at the Robinson limestone. Consists of alternating calcareous and siliceous beds, which at the base are like those of the Weber grits and at the top like 

those of the Trias 

Weber grits: The typical rock a coarse white sandstone, passing into conglomerate, with 

which are mingled quartzose shale and mica-schists 2,500 

Weber shale: Extremely variable. A transition series of argillaceous and calcareous shale, 

alternating with quartzitic sandstone 150-300 

Blue limestone: Dolomitic, deep grayish-blue in color, often nearly black near the top, while 

some of the lower beds are lighter. Upper strata marked by' chert concretions containing 

fossils 200 

SILURIAN. 

Parting quartzite: White quartzite 40-70 

White limestone: Light-colored, more or less siliceous dolomitic limestone 120-160 

CAMBRIAN. 

Lower quartzite: Below, thin-bedded, white, saccharoidal quartzites, conglomeritic at the 

base. The upper 50 feet are shaly and calcareous, passing gradually into the siliceous 

limestone of the Silurian 150-200 

ARCHEAN. 

Granite, gneisses, and schists.. 

The section obtained from the Leadville monograph calls for but little comment, 

as it differs from that given in the. Tenmile folio, whose relation with the other 

sections in central Colorado has already been discussed, chiefly in its nomenclature. 

From the different formations, and especially from those belonging to the 

Carboniferous, more or less extensive faunas are cited. The faunal evidence, which 

will be discussed more at length in the section devoted to paleontology, shows that 

the Leadville limestone is of Lower Carboniferous age and that the rest of the beds 

belong to the Upper Carboniferous. There is nothing to suggest the presence of 

Permian. 

The Paleozoic section throughout the South Park area seems to be in the main 

uniform and similar to that of the Grand River area, and the section described in 

the Leadville monograph is in a general way representative of the entire region. 

Aside from the Leadville monograph but little of importance has been written 

regarding the geology of this narrow strip of Paleozoic outcrop, and that little also 

deals chiefly with its northern portion. Peale described the geology and gave some 

sections, for the most part of the Leadville region, and Endlich described the 

geology of the southern portion in a way which it is difficult to understand and 

which does not inspire confidence as to his accuracy. 
80 CARBONIFEROUS FORMATIONS ANI) FAUNAS OF COLORADO. 

Peale's report for the year 1873, to which reference has already been made, has 

to do in part with the Elk Mountains, in part with the Front Range, which I shall 

consider later on, and with the Park Range.a 

The sections given by Peale can be correlated more or less closely with the 

formations recognized in the Leadville monograph and the Tenmile folio. In fact, 

they are all located rather north than south of the central portion of the area. Those 

numbered 9 and 18 are the most complete and will best serve to compare with the 

Leadville section. Section 9, the description of which begins upon page 216 of 

the Hayden volume, was taken from the Platte River to Trout Creek, about 5 miles 

north of Fairplay. Beds 1 to 51, inclusive, Peale refers to the Carboniferous and 

Permian. They probably all belong to the two formations which are called Weber 

grits and Upper Coal Measures in the Leadville monograph and Weber grits and 

Maroon formation in the Tenmile folio. This series consists chiefly of sandstones, 

with some shaly beds and a considerable number of 2 and 3 foot limestones. Above 

these come the Red Beds, which attain here a thickness of 1,500 feet and have "all 

the characters of the same beds east of the foothills and on Trout Creek west of 

them." (Page 218.) This series Peale refers to the Triassic?, and it is followed without any observed unconformity by the Jurassic, and this by the Dakota Cretaceous. 

The Triassic, in its character and thickness, invites comparison with the formation 

which is described in the Tenmile folio as the Wyoming formation. It is also 

similar to the Permian (in part) and Triassic of Peale's section on the Eagle River. 

Indeed, Peale calls attention to the similarity of the lower portion of his Permian 

section on Eagle River b to the upper beds of the series called Permian and Carboniferous in the section under discussion. This naturally suggests that the Triassic 

of the latter corresponds to the Triassic and the upper portion of the Permian, 

combined, in the former. 

Following Peale's suggestion, all the beds included in his sections Nos. 10, 11, 

and 12 would belong to the Weber grits and Maroon formation. In the section 

made from the mouth of Fourmile Creek westward to Horseshoe Mountain (No. 18, 

p. 229) beds 98 to 78 can with great probability be referred to the Sawatch quartzite. 

They aggregate 150 feet in thickness and consist of quartzites in the lower part and 

sandstone above. The four beds which come next in the section are limestones and 

dolomites and probably represent the Yule limestone. It is difficult to distinguish 

the Parting quartzite. Bed 72, representing 50 feet of blue limestone, and bed 68, 

representing 60 feet of bluish-black limestone, probably belong to the Leadvil!' 

limestone. If this is so, the interval between beds 77 and 73, inclusive, though representing a thickness of only 100 feet, must stand for the Yule limestone and Parting 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 212-239. 

b U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 119. 
RESUME OF LITERATURE. 81 

quartzite combined. The thin, dark-colored limestones, interbedded with shales and 

sandstones, which overlie bed 68, apparently belong to the Weber shale, though possibly they should be referred to the Leadville limestone. At all events, bed 38, with 

its well-marked Upper Carboniferous fauna, must be higher than the Leadville, and 

perhaps represents the upper limit of the Weber shale, for immediately above occur 

some coarse sandstones, pretty well interstratified with limestones, it is true, which 

seem more characteristic of the Weber grits. Less than 2,000 feet of Weber grits 

then follow, after which there is a repetition of the basal portion of the section. 

Beds 11 to 19 are again the Potsdam, as pointed out by Peale, and belong to the 

Sawatch quartzite. This formation seems here to have a thickness of only 110 feet, 

while Peale points out that in Mosquito Gulch the thickness is 160 feet and in 

Buckskin Gulch over 200. The average thickness of the Potsdam group along this 

range he believes to be about 150 feet and the remainder of the Silurian about 200 

feet. The rest of the section, consisting of about 230 feet, probably belongs in the 

Yule limestone, unless bed No. 2, consisting of 30 feet of blue limestone, belongs to 

the Leadville. 

In describing his observations made during the field season of 1875 Peale dvotes 

considerable space to comparisons and a summary,a in the course of which he gives a 

generalized section of the Carboniferous series, of the Park Range for comparison 

with that made out for the region of the Dolores River. This generalized section, 

which seems to be in large measure made up from the early sections, No. 9 and No. 

18, I will quote as follows: 

Generalized section in the Park Range west of South Park on Fourmile Creek, district of 1873. b (After Peale.) 

PERMIAN. 

Feet. 

Red, pink, and maroon-colored sandstones, gypsiferous and calcareous, with limestones in thin 

beds. No fossils 2, 000-2, 500 

COAL MEASURES. 

Conglomeritic sandstones, green and gray micaceous sandstones and shales, bluish limestones, and 

interlaminated sandstones. Fossils, from below—Second layer: 

ductus prattenianus, Productus semireticulatus, Spirifer opimus, Pleurotomaria taggarti. 

Productus nebraskensis, ProFirst 

layer: Productus, Spirifer, Trilobites � 2. 000 

SUBCARBONIFEROUS. 

Blue limestones and sandstone shales, limestones predominating; fossils are indistinct 300-400 

Total 4, 300-4, 800 

aU. S. Geol. Geog. Surv. Terr., Ninth Ann. Rept., for 1875,1877, pp. 70-79. 

bSee section No. 18, p. 229, report 1873. 

14364—No. 16--03 6 
82 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The most suitable standard sections with which to compare this of Peale's are 

those described in the Leadville monograph and in the Tenmile folio. There can be 

little doubt that in the Lower Carboniferous of Peale's section the Leadville limestone is included, and probably something more. He seems to have assigned to the 

Lower Carboniferous beds 40 to 72 of his detailed section No. 18. His Upper Carboniferous is probably the Weber grits of the Tenmile folio. The Weber shale of 

that folio I suspect to be equivalent to the upper part of his Lower and the lower 

part of his Upper Carboniferous. His Permian appears to correspond in the main 

to the Maroon formation of the folio, but it is possible that with it is included a 

part of the Wyoming sandstone, which in the main answers to his Triassic. This 

formation—i. e., the Permian—is in part described as being pink and containing 

gypsum, characters rather suggestive of the beds which in other sections he calls 

Permian and Triassic, and also of the Wyoming sandstone; but it is singular that 

none of the formations in either the Leadville monograph or the Tenmile folio is 

described as being gypsiferous, nor is this character mentioned in the original detailed 

sections from which the generalized one is supposed to be derived. 

Just as the lower part of Peale's composite section for the Park Range is based 

mainly upon section No. 18 of 1873, the upper part is based upon section No. 9. In 

the latter all the higher beds up to 52 which he refers to the Triassic are " Permian." 

The Triassic, here 1,500 feet thick, probably represents the Wyoming formation, and 

the beds below, chiefly because of the abundance of limestone strata, would more 

naturally belong in the Maroon formation. If this is so, and if the upper part of 

the composite section is based upon this, or, consistently, upon several detailed 

sections, then the "Permian" of the general section would answer to the Maroon 

formation of the Tenmile folio without containing any of the Wyoming. Peale 

seeks to correlate the Permian beds of the Park Range with those in the Elk Mountains for which the same designation is employed. To this there would be no objection, as both probably represent the upper portion of the Maroon formation without 

extending up into the Wyoming sandstone. He also, however, assigns both these 

groups to the Permian of the Eagle River section. This does not seem to me 

altogether probable, as I suspect that the upper portion of the Eagle River Permian 

belongs to the Wyoming sandstone. 

The relation to that of the Dolores River region of this Park Range section is 

open to two interpretations. In the one case the Coal Measures and Permian of the 

latter represent the Coal Measures and lower portion of the Permian in the former. 

In the other case only the Coal Measures division of the Park Range beds represents 

the Coal Measures and lower Permian in the Dolores River region, the Permian of 

the former being wanting in the latter. The Park Range "Triassic" would in any 

case answer to the upper part of his "Permian" combined with the lower part of his 

"Triassic" of the Dolores River section. 
RESUME OF LITERATURE. 83 

The so-called San Luis district which Endlich surveyed in 1873a included the 

southern portion of the South Park region and the northern portion of the Sangre de 

Cristo region. As these outcrops are practically continuous, and as Endlich did not 

divide his discussion geographically, it will be less confusing in abstracting his 

report to pursue the same course. Therefore his account of the geology of that 

portion of the South Park region included in the San Luis district will be discussed 

in connection with the Sangre de Cristo region. The same is true of Stevenson's 

account of the geology of the South Park and Sangre de Cristo b regions, which, 

as it is brief and more general in character, less readily yields to consideration in 

different sections. 

SANGRE DE CRISTO REGION. 

Endlich's report upon the geology of the San Luis district is one of the most 

unsatisfactory with which I have had to deal. The omission in the majority of cases 

of the thickness of the beds whose succession he describes greatly enhances the 

uncertainties involved in a comparison of different sections, while his failure to indicate upon the map many of the numbered stations with reference to which his obser 

vations are located is deserving of criticism. The presentation of his matter is 

obscure, so that with the defects already mentioned and other omissions and inconsistencies, it is a laborious task to effect a comprehension of what he has written. 

While some of the horizons of the Leadville 'and Crested Butte sections can be recognized with reasonable certainty in those described by Endlich, there is evidence of 

considerable change in constitution from their occurrence to the north and west. 

There is also ground for suspicion that Endlich has in some cases misinterpreted the 

mutual attitude of the beds and has possibly reversed their real succession. 

There being in the Sangre de Cristo region no detailed section of the Paleozoic 

rocks similar to those of the several monographic works dealing with central Colorado, I have had to employ the latter as a basis of comparison in this region also. 

The area included in the San Luis district is " bordered on the north by a 

line running east to west 6 miles south of Pike's Peak, on the west by the one 

hundred and seventh meridian, on the south by a line running east to west 12 miles 

south of Saguache, and on the east by, the eastern slope of the Front. Range." 

(Page 305.) Of the Carboniferous this area includes a strip along the Front Range 

(more correctly along the Colorado Range and the Wet Mountains) consisting chiefly 

of the series mapped as Triassic; of a somewhat branching body of outcrop, the 

northern portion of the Sangre de Cristo Range, the farthest extremity of which 

in the Park Range all but connects with the Carboniferous area reaching south from 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 305-351. 

b U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, pp. 307-501. 
84 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Leadville; and of two small outlying patches to the west. In the western part are 

two local Carboniferous areas, one of them, Fossil Ridge, being an outlier to the 

south of the Elk Mountain area, and the other, called the Tomichi dome, a smaller 

and more isolated patch to the south of this. 

Referring, it would seem, in a general way to the stratigraphic series in his district, rather than to any particular occurrence, Endlich says (page 308): "Resting 

immediately upon the granite, we find the Silurian characterized by but few fossils 

and the well-known quartzitic formation. At times the rock partakes more of the 

character of a limestone, but in that case segregations of siliceous matter, mostly in 

the shape of chalcedony and hornstone, afford a welcome lithologic character of 

distinction. Wherever the Silurian formation occurs in section a, it conformably 

underlies the Devonian and Carboniferous as far as could be ascertained." It would 

be natural to interpret the quartzite to which he refers as representing the Sawatch 

quartzite of the sections already discussed, his calcareous Silurian being the Yule 

limestone, which is also frequently characterized by cherty segregations; but in some 

of his sections the calcareous beds are reported as underlying the siliceous ones, and 

the quartzite in these cases can not be the Sawatch but must represent the Parting 

formation. Endlich's expression would appear to indicate a belief on his part that 

the calcareous and siliceous beds are only different aspects of the same series of 

strata. There is some evidence, however, that the Yule limestone rests in some 

cases immediately upon the granite, thus occupying a position similar to that of the 

Sawatch without, of course, being in any sense its equivalent. 

While I believe that the Devonian is probably present in this area, the evidence 

so far except in one instance is quite inconclusive, and the beds to which I make 

reference seem not to be those which Endlich had in mind, if, indeed, he entertained 

precise views upon the subject. That his uncertainty in one case was considerable 

appears from the lines: " Whether any of the strata above the ones just spoken of 

should be referred to the Devonian, I am unable to say. The poorly preserved relics 

of paleontological testimony that could be obtained were so few and unsatisfactory 

that I am inclined to think the Devonian, if represented, is no formation of great 

extent, either vertically or horizontally." The same lack of evidence and apparently 

the same uncertainty seem to have existed in other instances where the Devonian is 

cited. 

The Carboniferous recognized by Endlich consists of three divisions; a lower and 

an upper limestone, and a heay series of red sandstone included between them. The 

lower limestone can probably be correlated with the Leadville limestone, or possibly 

the Leadville and Weber formations combined, and I expect that it will be found to 

contain in addition to its Lower Carboniferous fauna, a Devonian one, similar .to that 

of the Ouray limestone, just as is the case in the regions to the north and west of 
RESUME OF LITERATURE. 85 

this. Indeed, as the Devonian fauna of the Ouray limestone occurs very characteristically at Salida, its presence throughout the South Park and Sangre de Cristo, 

regions wherever the Leadville limestone is present may be inferred with probability. 

The red sandstone would seem to be the representative of the Maroon formation, 

while the equivalence of the upper limestone, unless it is a localization of limestone 

beds elsewhere distributed through the Maroon, is uncertain.a 

The Red Beds generally called Juratrias in the Hayden reports are recognized 

by Endlich, but their occurrence is apparently restricted to the eastern side of the 

Front Range, where they are accompanied by patchy outcrops of the Paleozoic series. 

The main body of the Paleozoic outcrop described by Endlich lies in the long 

and narrow strip brought up by the elevation of the South Park and Sangre de. 

Cristo ranges. The portion considered by Endlich is from where Trout Creek 

divides the Mosquito Range on the north, nearly to Sangre de Cristo Pass on the 

south. His work, therefore, comes partly in the artificial area which has been called 

the South Park region, and partly in that which has been designated the Sangre de 

Cristo region. For the sake of continuity, however, both areas will be considered in 

the same division of this resume, and in that portion of it devoted to the Sangre de. 

Cristo Range. 

Turning now to Endlich's report, it seems that his station 53, though I have 

been unable to identify it with certainty upon the map, is located at the extreme 

northern end of that portion of the South Park region included within the San Luis. 

district. A section running through station 53 is said to consist of the following 

elements. Resting upon the granite is a bluish quartzitic limestone in heavy beds, 

hard and compact, containing numerous crinoidal fragments resembling Heterocrinus, 

and a few indeterminable specimens of Orthoceras. Then follows a thin layer of 

dark-gray slaty shales. These are succeeded by hard gray limestone containing in 

its upper portion a number of corals and Spongidw, above which follow thick beds 

of white,, yellow, and pink quartzite, which turn higher up into a light-red sandstone. 

What is with little doubt the continuation of this section is described on page 

311 of Endlich's report, and from this I condense as follows: "Reclining upon the. 

reddish Silurian sandstone and conformable with it is a thick stratum of yellowish 

and brown sandy shale, covered by light-yellow and gray shale.. Upon these rests a. 

limestone, grayish blue in color but weathering white, in which, apparently near the 

top, were found Orthis, Productus, and Orthoceras. Overlying the limestone are 

shales of gray and brown color, succeeded by others of a more sandy character, and 

these are brought to a close by a series of heavy strata of dark-blue limestone capped 

by brown sandstone." 

a It perhaps represents the series of intermingled siliceous and calcareous beds called in the Leadville monograph 

Upper Coal Measures. 
86 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Comparison of the series thus briefly characterized with other known sections 

in areas adjacent is hampered by lack of measurements of thickness which Endlich 

fails to supply, and by the meagerness of paleontologic data. Nevertheless, if this 

series be closely compared with that of the Leadville monograph, though the result 

shows considerable changes in lithology between Leadville and the southern end of 

the Park Range, yet certain horizons seem to be recognizable as probably equivalent 

in the two sections. In view of its lithology and position, the siliceous limestone at 

the base of the section can be taken as representing the Yule limestone, and with it 

would probably go the overlying limestone containing corals and sponges. The 

Cambrian Sawatch quartzite appears from Endlich's statements to be entirely lacking. The light-colored limestone with Orthis and Productus is probably the Leadville limestone (or its more or less close equivalent, the Ouray limestone). The 

quartzite between these two calcareous formations should, from its character and 

position, be the Parting quartzite. The light-red sandstone and the heavy shale series 

above it, however, seem to have no lithologic equivalent in the Leadville section. 

Perhaps they should, in conjunction with the quartzites, be taken as representing the 

Parting formation. The shales above the supposed equivalent of the Leadville 

limestone present some claims of similarity to the Weber shales, but the succeeding 

beds certainly do not at all resemble the Weber grits series as it is described by 

Emmons. It seems rather more probable that the massive blue limestone above, as 

well as the lower fossiliferous one, belong in the horizon of the Leadville limestone, 

and, of course, with it would be carried the intermediate series of shales. The dark 

sandstones with which the section closes certainly are more similar to the Weber 

grits than any of the beds below. 

Results not altogether satisfactory attend the comparison of this section with 

that described by the same author as occurring at Fossil Ridge in the Elk Mountain 

region. The series of Ordovician beds in the two sections are probably to be correlated with each other and with the Yule limestone. In the South Park region these 

consist of a blue quartzitic limestone with crinoids and Orthoceras, overlain by a hard 

gray limestone containing corals and sponges, with a thin interstitial shale. At Fossil Ridge this series comprises 320 feet of light-gray limestone, with quartzitic segregations and sparse remains of crinoids. The two limestone series which I. correlate 

with the Leadville limestone are also probably equivalent. At Fossil Ridge these 

comprise 260 feet of light-gray and yellowish limestones, interstratified with narrow 

bands of shale; 40 feet of light shale; and 20 feet of dark-blue limestone carrying 

upper Devonian or lower Mississippian fossils. The bed last mentioned can be 

assigned with great probability to the Leadville or Ouray limestone. Above it 

come 45 feet of light shale, 150 feet of light-blue and yellow limestone, and 50 

feet of yellow, reddish, and whitish shales, which may belong with the Leadville 
RESUME OF LITERATURE. 87 

limestone or with the Weber limestone. In the other section till Leadville seems 

to consist of a lower series of gray limestone, an upper one of dark-blue limestone, 

and an intermediate one of shales. A certain resemblance to this series will be 

observed in the Fossil Ridge section, though the latter contains some overlying 

shale and limestone which appear to be without equivalent in the other. 

Intermediate between the Yule and Leadville limestones at Fossil Ridge occur 

80 feet of yellow and gray shale and 175 feet of variegated shale and limestone. The 

former especially seems to resemble in thickness and character the upper member of 

the original Yule limestone, which Spurr correlates with the Parting quartzite, but 

the other and heavier bed may possibly belong to the same series. In the South 

Park section Endlich describes a white, yellow, and pink quartzite and red sandstone as occurring just above the Yule, followed by yellow and brown shale and light-. 

yellow and gray shale. The quartzite is not represented in the Fossil Ridge section, 

but is suggestive of the original Parting quartzite in character and position. The 

overlying shales have more the character of the Parting formation of the Elk 

Mountain region. The circumstances thus detailed suggest the possibility that the 

Parting beds, as identified at different localities, are of a dual character, consisting 

of quartzites below and variegated shales above, the shales alone being found in the 

Elk Mountain region, the quartzite alone at Leadville, both shale and quartzite in 

Endlich's section, and neither shale nor quartzite at Red Cliff. At all events, this 

formation apparently varies considerably from point to point both in character and 

thickness. 

South of the point at which the preceding section occurs, according to Endlich, 

the Silurian retains its characters, the quartzitic limestone resting directly upon 

granite, and at a point designated by him as station 56 another section was taken 

across the same line of outcrop. 

This station I have been unable to locate exactly, but it appears to be situated 

southeast of station 53 and not far to the west of the more northerly transsection by 

Badger Creek of the Paleozoic outcrop. The stratigraphic succession at station 56 

consists of the following members: Resting upon porphyritic granite are found a 

series of yellow to light-brown, hard quartzites, followed by fine-grained white and 

pink quartzites, and covered by shales that can be referred to the Carboniferous. 

Endlich suggests that the blue limestone which formed the base of the other section 

underlies the quartzites, although it was not found at this point. The continuation 

of this section also appears to be found upon page 311 of Endlich's report. " Overlying," he says, "the yellowish shales, interstratified with quartzites, which have 

been referred to the Upper Silurian, are a series of blue limestones, irregularly alternating with gray shales containing Orth,is and crinoids." On page 309 of his report, 

however, the yellowish shales are not referred to the Upper Silurian but to the Car-
88 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

boniferous, and no reference is made to their being interstratified with quartzites. 

The blue limestone and shales Endlich prefers to regard as oldest Carboniferous 

rather than Devonian. "Bluish shales that have been eroded considerably follow, 

forming the bottom of a narrow valley, and are covered in turn by a saccharoidal 

limestone rising steeply from them." Apparently following the limestone comes 

"the red sandstone, which has not appeared for 4 or 5 miles along the line of 

Carboniferous outcrop," nor, it might be added, has it appeared specifically mentioned before in Endlich's description, though it is probably the sandstone casually 

referred to on page 310-311 and the same as his Arkansas sandstone. 

This section is so nearly a repetition of that made at station 53 that the correlation of the constituent members is obvious. A conspicuous feature is the absence of 

the basal limestone, which", however, appears to be only local, as Endlich states (page 

310) that it reappears south of station 58 and remains entirely or partially exposed 

southward to beyond the Arkansas. This circumstance conspires with several others 

to render it probable that the granite in this case is not the Archean granite, but an 

intrusive body. 

The Carboniferous formations are reported as following the Silurian to his 

station 58, at which point the sandstones, farther north of no great dimensions, are 

enormously developed, and the upper limestones make their appearance. Of the 

latter a spur branches off to the east and runs through a granitic country for a distance of about 7 miles, dipping northeast to east, and then comes to an end without 

connecting again (page 310). 

This sandstone is said to be uniform in appearance and to be greatly developed, 

reaching a thickness of more than 5,000 feet, and even exceeding this in section h 

south of the Arkansas. To this formation Endlich gives the name "Arkansas sandstone." Running parallel with the Arkansas sandstone was found an outcrop of gray 

and bluish limestone already referred to, which, " for stratigraphical reasons, must 

be considered as properly belonging above the Arkansas sandstone." In this limestone were found Favosites and a few other fossils. As the range of Favosites, so 

far as known, does not extend above the lower Mississippian, the presence of this 

genus in this limestone, if the generic identification can be relied on, seriously 

contradicts other statements bearing evidence as to the geologic age of this bed. 

In the Hayden atlas, moreover, this spur is represented as consisting of Lower 

Carboniferous and Middle Carboniferous sediments. As there can be but little 

doubt that the Lower Carboniferous of this map is Endlich's lower limestone, and 

that his Arkansas sandstone is the Upper Carboniferous, it seems clear that the best 

information at the time the map was constructed indicated that the limestones of the 

spur were not a new series of limestones overlying the Arkansas sandstone, but a 

repetition of the series lying beneath it. 
RESUME OF LITERATURE. 89 • 

The Paleozoics south of the Arkansas (sections b and c of Endlich's district) come 

in the area which I have defined for my purposes and named the Sangre de Cristo 

region. Here the Silurian is again found, though in small quantities, but the 

Carboniferous occupies larger areas. The latter consists chiefly of the Arkansas 

sandstone, which forms the main bulk of the Sangre de Cristo Range. The typical 

Arkansas sandstone is here found to be more or less interstratified with dark shales and 

isolated limestones, the combined thickness of which is said in one instance probably 

to exceed a mile. The lower limestone, determined by its petrographic character 

and position, also occurs south of the river, and accompanies the Arkansas sandstone 

for some miles. No fossils were found in it (pages 326,327). 

Farther west, along the southern end of the Arkansas Valley (in section c of 

Endlich's district), the Silurian is again reported. It consists of light-colored 

quartzites of yellowish, bluish, and reddish tints, which are conformably overlain 

by gray to bluish limestone with siliceous segregations. Lithologically they are 

said to be identical with those found north of the Arkansas River. 

One can hardly doubt that in this instance the quartzite is the Sawatch quartzite, 

and that the limestone is the equivalent'of a similar bed at Fossil Ridge, in the Elk 

Mountain region, of the basal limestone at station 53 in the South Park region, and 

of the Yule limestone of established sections. Endlich galls attention to the resemblance which these strata bear to those north of the river, but in the latter area 

the quartzite is represented as lying upon instead of under the limestone, so that its 

position is not that of the Sawatch but of the Parting quartzite. The Sawatch, 

indeed, appears to be wanting, but I can not altogether banish the suspicion that the 

sequence is wrong in Endlich's sections north of the Arkansas. 

In the Hayden report for 18754 is found Endlich's account of the geology of the 

so-called Southeastern district. He described the boundaries of this district in the 

following terms (page 105): "The district assigned to our party during the field season 

for 1875 extended from longitude 104° 30' west to longitude 108° west, was bordered 

on the south by north latitude 36° 45' and on the north by north latitude 37° 50'. On 

the west side it connected with the work of 1874, and on the north with that of 1873." 

The geologic discussion is distributed into five divisions based upon geographic 

occurrence. These are the Sangre de Cristo Range and the Huerfano region, the 

San Luis Valley, the southern extension of the Sawatch Range, the Rio San Juan and 

its drainage, and the Post-Cretaceous formations of the Trinidad region. Only one 

of these chapters, that upon the Sangre de Cristo Range, contains anything of 

importance in our discussion. 

Though present in the more northern portion of the Sangre de Cristo Range (see 

Endlich's report for 1873), the strata of Silurian and Mississippian age gradually 

a U. S. Geol. Geog. Surv. Terr., Ninth Ann. Rept., for 1875, 1877, pp. 103-215. 
90 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

disappear and are not found at all farther south, and the Arkansas sandstone generally rests directly upon the Archean. An exception to this statement seems to 

exist in the vicinity of Trinchera Peak, where a grayish-brown, compact shale, sandy 

in part, and interbedded with limestone, was seen conformably underlying the red 

Carboniferous sandstone. The position and character of these strata make it 

probable that they represent the Weber formation, or else, as suggested by Endlich, 

the horizon of the Ouray and Leadville limestones. 

It was in the southern part of this area mapped by Endlich as " Lower Carboniferous" that Lee made a section and collected fossils as hereinafter described. The 

fauna obtained by Lee not far above the contact with the Archean is unquestionably of Pennsylvanian a4e, and is related to that of the Hermosa formation and 

of the Weber limestone and lower Maroon formation. Unless still lower rocks 

occur in other parts of the area, it is evident that the "Lower Carboniferous" 

color, so far as the " Lower Carboniferous of the Hayden survey is understood 

to be equivalent to the Leadville limestone, is wrongly introduced in the vicinity 

of Trinchera Peak. 

The remainder of the Paleozoic consists of the Arkansas sandstone, whose outcrop covers large areas on both sides of the Sangre de Cristo Range, extending as 

far south as Costillo Peak. This formation is made up chiefly of red sandstone, with 

which are interstratified red shales and blue limestones. In the vicinity of Costillo 

Peak Endlich reports some whitish sandstones and a quartzitic bed in association 

with the red sandstone (page 122). Although in his previous work the Arkansas 

sandstone had been placed in the Carboniferous, the first paleontologic evidence was 

not obtained until 1875. Hayden a had, however, collected Carboniferous fossils in 

this range in 1869 and Ruffner in 1873.6 Endlich cites Productus semireticulatus, 

Seminula subtilita, and Spirifer at one station, Calamites and Sigillaria at another, 

while a third furnished Productus, Orthis, Spirifer, and crinoids. The latter fauna 

suggests those which he obtained in 1873 from rocks of supposed Mississippian age, 

but otherwise are diagnostic only of the Carboniferous as a whole. The thickness 

of the Arkansas sandstone is here given as 2,000 feet, while farther north it was 

reported by the same author as in one place not less than 5,000 feet. This great 

diminution in bulk, conjoined with the entire absence of• the series which Endlich 

a Apparently the first adequate evidence as to the age of these beds was obtained by Hayden in 1869 (11. S. Geol 

Surv. Terr., Ann. Rept. for 1867, 1868, and 1869,1873, p. 175), who observed near Sangre de Cristo Pass an extensive series of 

reddish sandstones, some of which contain impressions of Calamites, while from a bed of limestone, in a series of alternating limestones and sandstones, were obtained several species of Productus, "Spirifer subtilita, Rhynchonella rockymontana, 

Spirifer lineatus, and numerous corals and crinoidal stems." The names of species in this list are singularly mangled, but 

it is evidently an Upper Carboniferous fauna that is presented. These were found near the junction of the sedimentaries 

with the (Archean?) granite. 

In his paleontologic report the year following Meek lists (U. S. Geol. Survey Wyoming, etc., Preliminary Rept. 

[Fourth 'Ann. Rept.] , 1871, p. 295) Productus punctatus, Productus semireticulatus, and Seminula subtilita from Sangre de 

Cristo Pass. 

b Ruffner's Rept. Recon. Ute Country, 43d Cong., 1st sess., House Ex. Doc. No. 193, p. 61. 
RESUME OF LITERATURE. 91 

in 1873 disti guished by the name of Upper Carboniferous (if, indeed, the beds so 

designated r ally occupied the position ascribed to them), would indicate that the 

southern po ion of the Sangre de Cristo Range had been the scene of severe postCarbonifero s erosion, though doubtless to the unconformity which preceded the 

deposition o the Arkansas sandstone may be ascribed an important share in the 

influences th t produced this difference in bulk. 

Endlich reports no Triassic in the Southeastern district, except at the southern 

end of the et Mountains. To these exposures I shall refer in connection with the 

Front Rang region. 

In 1874 as published Ruffner's report upon a reconnaissance in the Ute country a 

made the y ar previous. The map accompanying the report covers an extensive 

territory, e tending from the thirty-seventh parallel on the south to north latitude 

39° 30', an from 105° 30' west longitude on the east to 108° on the west. The 

primary obj ct of the expedition was not geologic, but two geologists in the persons 

of F. and L Hawn accompanied it, and their accounts form Appendix B (pp. 59 to 

88) of the eneral report. The identification of the different outcrops described 

with the re ognized Paleozoic formations of Colorado is in many cases difficult or 

impossible ecause of the brief mention made of them, but in several instances 

the citation f Carboniferous faunas removes all doubt with reference to formations 

of that per'od. The geologic observations so far as they concern this resume fall 

into the Sa Juan, Elk, Sangre de Cristo, and Front ranges. These accounts add 

little to the subject, on account of the more detailed character of subsequent work 

in the sam areas, and the interest which attaches to them is largely historical. 

In the earli r portion of the work, which is devoted to a general description of the 

route, not i i frequent reference is made to the occurrence, character, and even thickness of the rocks observed, but with these I have not concerned myself, dealing 

only with t e descriptions in the geologic reports. 

In the Sangre de Cristo Range the chief line of observation was the road 

between Pueblo and Fort Garland by the way of Sangre de Cristo Pass. Mention 

is made of the Carboniferous limestones and brown, sandstones (p. 61) of Sangre de 

Cristo Pass, and from the former are cited Cyathophyllum sp., Productus equicostatus, 

tuckyensis, 

Productus emireticulatus, Productus cora, SpirVer cameratus, Spir9ferina kennd Seminula subtilita. This is one of the earliest accounts' that I 

have found f this occurrence of fossiliferous strata, though authors have several 

times made subsequent mention of it. 

Carboniferous rocks appear to have been found also at the extreme northern 

end of the ange, and it is possible to recognize as the Leadville limestone a bed 

a U. S. War n ept., Rept. Reconnaissance Ute Country in 1873, by Ruffner, Washington, 1874, pp. 1-101. 

b Hayden f i and these fossiliferous beds as early as 1869 (see IT. S. Geol. Survey Terr., Ann. Rept. for 1867, 1868, and 

1869, 1873, p. 175) The fossiliferous Carboniferous beds of the Sangre de Cristo Range are also mentioned by Cope (p. 64, 

Ann. Rept. Whe ler Survey for 1875), but in a very cursory manner. 
92 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

which is described a as a gray, cherty limestone containing small fragments of 

Cyathoph,ylium. This is succeeded by hard, ferruginous gray and blue sandstone, 

which in all probability belongs in Endlich's Arkansas sandstone. The point at 

which this observation was made is on the Arkansas River above its pass through 

the Sangre de Cristo Range and somewhat above the mouth of the Little Arkansas. 

This place can not be far from the locality, near Salida, at which were found the 

fossils in our collections representing the Devonian and Mississippian phases of the 

Leadville limestone. 

As a portion of the extensive area embraced in Stevenson's report in Volume 

III of the Wheeler survey, the geology of the highlands on the west side of South 

Park, more or less directly connecting southward with the Sangre de Cristo Range, 

is briefly described.b What he says about the former should properly be considered 

in the section of this discussion devoted to the South Park region, but I believe that 

its relations will be easier appreciated in connection with the beds belonging to the 

Sangre de Cristo division. 

To the Silurian Stevenson refers "all strata underlying the Carboniferous limestone;" (page 357) and, thus defined, it is exposed in numerous outcrops along the area 

mentioned. In his section of the Silurian made on Bald Peak in the canyon of 

Fourmile Creek (page 357), the five lowest beds (6 to 10) can safely be referred to the 

Sawatch quartzite. They consist of sandstones, and have a combined thickness of 162 

feet. The 40-foot limestone represented as bed 5 is probablythe Yule limestone, though 

it appears to be here of only half the usual thickness. The 170 feet of sandstone 

overlying can hardly be anything but the Parting quartzite, and possibly with it 

should be included the 20 feet of limestone of bed 1. The Sawatch quartzite is 

reported at numerous scattered localities. Its color varies from white to dark blue, 

and it ranges in thickness up to 200 feet. In the canyon of the Arkansas a very 

different section of these beds is given. I quote as follows (page 359): 

Section in canyon of Arkansas River. 

1. Sandstone, partially altered, with layers of quartzite; somewhat argillaceous; weathers to 

ochery color; contains many large fragments of jasper 

2. Clay, calcareous, indurated, reddish, weathers into mud 

3. Limestone, siliceous above, more argillaceous below, with thin layers of comparatively pure 

bluish limestone 

Feet. 

75 

20 

27 

4. Limestone, varying from dove color to black; several argillaceous layers; near the top vast 

numbers of crinoidal stems, with many sections of cyathophylloid corals and Brachiopoda. 

As these are not silicified they can not be separated. Near the base is a thin, argillaceous 

layer which contains many compressed individuals of Rhynchospira sp. and occasionally a 

bryozoan. From this layer was obtained also a fragment of a large trilobite 35 

a Ruffner., op. cit., p. 80. bU. S. Geog. Geol. Surv. W. 100th Viler., Rept., vol. 3, 1875, pp. 307-501. 
50 

RESUME OF LITERATURE. 93 

Feet. 

5. Limestone, m stly quite siliceous and compact; varies from dove color to black; layers of 

the latter c for very fetid when struck; weathers in lines and disintegrates readily; almost 

entirely no fossiliferous, but near the top saw a few crinoidal plates and some very indistinct bryoz ans 

6. Sandstone, g yish blue in color, fine grained, and entirely 'converted into quartzite. Below 

this we fin an exceedingly dark, hornblendic gneiss. 

The sand tone at the base (No. 6) presumably represents the Sawatch quartzite. 

Stevenson sta es that the limestones, Nos. 3, 4, and 5, are certainly the equivalent of 

No. 5 of the ald Peak section, but the dark color of the limestone, together with 

the character of the meager fauna cited, might suggest that these do not belong to 

the Yule but to the Leadville limestone, which is known to be present in this region 

(e. g., at Sali a). In the former case the sandstone and clay (1 and 2) would probably be the P rting quartzite; in the latter they would be the earliest beds of the 

Upper Carbo if erous. The Arkansas Canyon is the most southern point along the 

range at whi h Silurian beds are cited by Stevenson. 

Carbonif rous strata appear to be exposed almost continuously along the line of 

the South Pa k and Sangre de Cristo ranges, and are mentioned at numerous localities from Qu ndary Peak to the divide between Wet Mountain Valley and Huerfano 

Park. The s ries seems to be twofold, consisting of limestones below and sandstones 

above. The ower member is a dark limestone of undesignated thickness, and it is 

usually refer ed to by Stevenson simply as "the limestone." Near the Arkansas Canyon the uppe member is described as an enormous mass of reddish and gray sandstones and sh les, not less than 2,500 feet thick, which forms the canyon's walls to 

its mouth at leasant Valley (page 371). At the northern end of the range, in the 

Leadville re ion, it is spoken of as " an enormous mass of red and gray sandstones, 

more or les finely conglomerate, capping the mountains on the main divide, and 

including sev ral of these thin limestones, two of which are seen in Hamilton Pass." 

(Page 374.) Near its base the upper series is gypsiferous. "In Sangre de Cristo 

Pass the san tones are finely exposed, and at one locality the limestone is seen with 

many imper ect fossils, of which Product'us semireticulatus is most abundant." 

(Page 371.) 

The lim stone member of the Carboniferous is evidently the Leadville limestone, while he sandstone member represents wholly or in part the Weber shale, 

Weber grits and Upper Coal Measures, or the Weber and Maroon formations of 

Emmons's w rk, and the Arkansas sandstone of Endlich's. In the north, because of 

the presenc of interbedded limestones, and because both the divisions of the 

Upper Carb niferous which Emmons in the Tenmile folio distinguished as the 

Weber and aroon formations, are known to be present, Stevenson probably saw 

nearly the w ole series. Farther south, however, at Arkansas Canyon, he allows a 
94 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

thickness of but 2,500 feet and does not mention interbedded limestones. In both 

particulars this agrees especially with the Weber grits formation alone. Still 

farther south, on the other hand, fossiliferous limeststones are present, as we have 

just seen. Trustworthy and detailed information about the whole range south of 

the Leadville region is, unfortunately, sadly lacking, but I judge that the Upper 

Carboniferous sandstones and conglomerates, represented southward by the Arkansas sandstone, are thinner in the southern part, and suspect that this will prove to 

be due to erosion of the upper surface by one or several combined of the erosion 

periods that appear to have succeeded the deposition of the Maroon sediments. 

Stevenson found no Triassic in this region, and, in fact, the bright Red Beds appear 

to be in large measure wanting. They are, however, found in the Tenmile region, 

and their apparent absence farther south is possibly owing to the same cause by 

which the thickness of the Maroon sediments appears to have been seriously diminished.a Wherever any representation of the Wyoming formation occurs in the area 

examined by Stevenson it was evidently included by him in the Carboniferous. 

In the supplement to volume 3 of the reports of the Wheeler survey b Stevenson described the geology of an extensive territory in New Mexico and southern 

Colorado. It probably included in the latter State all the mountainous portion 

south of north latitude 37° 20'. Two Carboniferous areas are described, one of 

which is situated entirely in Colorado and the other entirely in New Mexico. The 

Colorado area, which is described in less detail than the other, occurs on the eastern slopes of the chain of mountains called in the Hayden atlas the Sangre de 

Cristo Range, and extends from Spanish Peaks to Costillo Peak. The Carboniferous beds rest upon the Archean. The base of the series is a conglomerate sandstone 

not far from 800 feet thick which contains some beds of fine-grained red sandstone and red shale. Above this comes in the lowest limestone, which is 7 feet 

thick, blue, slaty, hard, and somewhat fossiliferous. Next occurs an interval of 

700 feet filled with red shale and sandstone. This is succeeded by a blue, very 

compact limestone, of which 20 feet are exposed, showing some calcspar but no 

fossils. Above the limestone occur 300 feet of red sandstone and reddish shale. 

Next follows another limestone which is gray, not very hard, richly fossiliferous, 

and not far from 100 feet thick. Above the limestone are about 1,800 feet of 

reddish, thin-bedded, fine-grained sandstones, holding beds of red shales. The 

rocks thus far mentioned, which have a total thickness of 3,727 feet, seem to 

aI have suggested the probability of an extensive time break and period of erosion between the brick-red or 

" Triassic " Red Beds and the Maroon formation. To this the reduction in the thickness of the upper Maroon from 2,500 

feet in the Crested Butte quadrangle to 300 feet in the San Juan region (Rico formation) has been ascribed. Possibly the 

same influence was felt to the east and the Maroon reduced before the deposition of the "Triassic," which has been 

itself removed. The great thickness of the Maroon (Arkansas sandstone) farther south in the Sangre de Cristo would 

rather seem to indicate that the thinness of these beds in the region of the Arkansas was a local matter and probably the 

result of comparatively recent causes. 

bU. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Suppl., 1881. 
RESUME OF LITERATURE. 95 

constitute a lower series and are overlain by an upper one of reddish-brown 

co nglom er to sandstone not far from 2,500 feet thick. Large fragments of granite, 

gneiss, and quartzite prevail, but with them are some of sandstone and limestone. 

"This par of the section bears close resemblance to the upper division of the 

Carbonifer us series seen on the Eagle River of central Colorado." No Triassic 

was found in this area, the Carboniferous underlying the Dakota throughout. 

It ma be added that neither has the "Triassic" series or "Red Beds" been 

reported b any of the geologists who have written of the Sangre de Cristo region, 

nor is it re resented upon the Hayden maps. Its absence in this area is in agreement with ts absence over the southern part of the South Park region, the southern 

part of the Elk Mountain region, and the southern part of the Front Range region, 

where the `Red Beds" apparently belong in the Fountain and not in the Wyoming 

formation. At the same time Hills remarks that a small thickness of brick-red 

sandstone ccurs in the Sangre de Cristo Range above the Arkansas sandstone and 

in the Walsenburg quadrangle above the Badito formation. Yet, though the position and color of this bed rather suggests the "Triassic," it can probably be 

provisionally regarded as part of the Arkansas sandstone. 

No fo sils are cited from the Carboniferous, so that conclusive evidence is 

lacking as ;o the presence or absence of the Mississippian limestone in this section. 

The Hayd n atlas, it is true, represents an area of Lower Carboniferous at and about 

Trinchera eak, and this division frequently contains beds of Mississippian age, but I 

am disposed to think that the Mississippian is really wanting, if not at the Trinchera 

Peak locality, at least from Stevenson's section, first, because there is nothing in it 

comparable to the massive and persistent Leadville limestone, unless it be the highest 

limestone of the section, and, second, because the limestones of Sangre de Cristo Pass, 

which are probably the equivalents of those in Stevenson's section, appear from their 

fossils to be Upper Carboniferous. It would thus appear probable that the whole of 

the Carboniferous section is of Pennsylvanian agea and to be compared with the 

Maroon conglomerate of the Crested Butte section and with the Weber grit and 

Upper Coal Measures of the Leadville section. The two divisions of Stevenson's 

section are indeed comparable to the two divisions of the original Maroon. The 

resemblance in both lithology and thickness in the case of the upper divisions is 

rather striking. The lower one in Stevenson's section, however, though not unlike 

the other lithologically, is much thicker. But with indications of an unconformity at 

the base of the Maroon, and a possible time break between its two divisions, disparity 

in the thickness of the lower portion in different areas would not be surprising. 

a This appears to be certainly the case in Lee's section west of Trinidad, but it is possible that here, as along the 

Front Range, the Mississippian limestone and earlier Palezoic formations may underlie the Arkansas sandstone in 

disconnected patches. 
96 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Very recently W. T. Lee a published a detailed section taken at the crest of the 

Sangre de Cristo Range directly west of Trinidad, Colo., between the sources of 

the Middle Fork and the North Fork of the Purgatory River. This point is near 

Culebra Peak, not far from the southern border of the State. Lee's section comprises 

about 400 feet of strata immediately overlying the Archean granite. Lithologically 

the series consists of coarse grits, conglomerate, and sandstones, with some shales and 

a number of thin limestones. Upper Carboniferous fossils were found in abundance 

about 150 feet above the base, and an extensive fauna is cited. Lee calls attention to 

the fact that Endlich had mapped Lower Carboniferous rocks at this point. Every 

test shows the inaccuracy of Endlich's work; but Stevenson, as long ago as 1881, 

described the section in such a manner as to leave no reasonable doubt that the Lower 

Carboniferous was generally absent from the Sangre de Cristo Range, at least from 

Spanish Peaks southward to Costillo Peak. The whole series is referred by him to 

the Carboniferous, apparently on paleontologic evidence, though no identified species are cited. Upper Carboniferous fossils had long been known from this series, 

however, having been obtained chiefly from the vicinity of the Sangre de Cristo Pass. 

The horizon of the earlier collections with relation to the granite was never, I believe, 

ascertained. The fauna cited by Lee is much more abundant than had ever been 

previously known from these rocks, and the stratigraphic position is far lower than 

any fossiliferous horizon mentioned by Stevenson. The combined evidence, both 

stratigraphic and paleontologic, tends to confirm Stevenson's early reference of the 

entire series to the Upper Carboniferous. The Lower Carboniferous and earlier 

Paleozoics must be either entirely missing or represented by local fragments, for I 

little doubt that they once extended over this region. Geologically the beds described 

by Lee doubtless belong at the base of Stevenson's lower series, which I am disposed 

to correlate with the lower portion of the Maroon formation. 

The collections made at this point have recently come into my hands, though too 

late to be incorporated into the paleontologic discussion. The fauna, while not 

without individuality, is distinctly related to that of the Hermosa formation and of 

the Weber limestone and lower Maroon series, and quite distinct from that of the 

Rico formation. 

In 1898 E. C. and P. H. Van Diest published a note on the geology of the 

western slope of the Sangre de Cristo Range in Costillo County.° The area of 

observation was along. the Rito Seco, northeast of the town of San Luis. In this 

area Endlich had indicated (Hayden atlas) extensive areas of Upper Carboniferous. 

Apparently this series does not occur there, but instead Archean, Cambrian, and 

Silurian strata were found. The Sawatch here consists of white saccharoidal 

quartzites, with a thin basal conglomerate. These are succeeded by a thin bed of 

a Jour. Geol., vol. 10, 1902, pp. 393-396. bcolorado Sci. Soc., Proc., vol. 5, 1898, pp. 76-80. 
RESUME OF LITERATURE. 97 

argillaceous shale, " and the whole section is topped by layers of light-gray siliceous 

limestones or about 200 feet, where a quartzy parting separates them from others 

of somewha darker color."a Though no fossils were found in these beds, their 

occurrence nd lithology, as the authors point out, make it highly probable that the 

quartzite is he Cambrian and the limestone the Ordovician of the Paleozoic sections 

of central olorado. Except that the wording seems to indicate an insignificant 

thickness fo the siliceous bed above the light-colored limestone, one might see in it 

and in the d rker limestone above, representatives of the Parting quartzite and the 

Leadville estone. Neither Endlich nor Stevenson, nor, so far as I have ascertained, 

any other eologist, found the older Paleozoics in the Sangre de Cristo Range, 

except in its northern part, while Lee's section seems to afford positive evidence that 

they are in • laces actually absent. 

FRONT RANGE REGION. 

The ch, racter and correlation of the Paleozoics of the East as they reappear along 

the front of the Rocky Mountains after their long sequestration beneath the plains 

under deposits of later geologic ages is a subject of peculiar interest. In Colorado 

Paleozoic exposures (except for the Red Beds) are neither numerous nor extensive 

along the Front Range, and circumstances have combined to make their correlations, 

both with different outcrops of the same series and with the typical sections of the 

East, often matter of difficulty. 

The Pi es Peak quadrangle, which lies just west of Colorado Springs, contains 

part of one f the few areas of recognized Carboniferous in this region. Although 

much literat re upon the geology of the Front Range had appeared before the Pikes 

Peak folio') was published, inasmuch as I shall use the nomenclature and definitions 

adopted in it, for the different formations, it seems best to employ the logical rather 

than the historical order in this discussion. 

The Pikes Peak quadrangle, therefore, includes portions of two more or less 

distinct Paleozoic areas, and as they seem to have passed through somewhat different geologic histories, or at least to show differences of note in the histories preserved to us, it will be more intelligible to consider the sequence in each separately. 

In the southern part is an area which extends southward and eastward beyond the 

limits of the quadrangle and reaches the well-known locality of Canyon. In the north 

is a somewhat smaller area, the southern extremity of the isolated Manitou Park 

Paleozoic tract. The basal formation in both areas resting upon granite and gneiss 

is called the Manitou limestone. A small thickness of quartzite and cherty limestone 

at the base is probably Cambrian, but the main body of the formation is Ordovician. 

"In Garden Park it consists of fine-grained pink or reddish dolomite less than 100 

a Colorado Sci. Soc., Proc., vol. 5, p. 78. b1.1. S. Geol. Surv., Geologic Atlas U. S., folio 7, Pikes Peak, 1894. 

14361 No. 16-03-7 
98 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

feet thick, and contains Opitileta, Camarella, and a few other invertebrate fossils 

characteristic of the Lower Silurian formation in the section at Manitou Springs and 

at Manitou Park, whence the name is derived." In the northern part of the quadrangle this limestone is not dolomitic, and is connected directly with the typical 

locality at the north end of Manitou Park. In the southern part of the quadrangle 

the Manitou limestone is immediately overlain by the Harding sandstone, which is 

predominantly a fine-grained, saccharoidal sandstone in alternating banks of lightgray and pinkish or variegated colors, and sometimes calcareous at the base. The 

maximum thickness is about 100 feet. This horizon is characterized by numerous 

remains of fishes of types not elsewhere found below the Devonian, and it carries 

also a rich invertebrate fauna of Trenton age. " The Harding sandstone is not found 

in Manitou Park, nor at Manitou Springs, and has not been identified at any other 

locality." In Garden Park the Harding sandstone rests with apparent conformity 

upon the Manitou limestone, but evidence elsewhere indicates that before its deposition the Manitou limestone was subjected to a period of erosion. 

Succeeding the Harding sandstone with apparent conformity there occurs a 

bluish-gray or pinkish dolomite which has a thickness in Garden Park of about 100 

feet, but increases southward, and near Canyon reaches a maximum of 270 feet. 

This is partly through the development of an upper and highly fossiliferous member 

not seen in Garden Park. The Fremont limestone in Garden Park is especially 

characterized by Halysites catenulatus, and it also contains a large invertebrate fauna 

like that of the upper Trenton of New York. This limestone horizon has not been 

recognized in other sections of Paleozoic strata along the east base of the mountains, 

nor has its equivalent been found in any other part of the West. Its present limitation eastward from Garden Park, on the slopes of the range, is by erosion, which 

took place after the deposition of the Millsap limestone. 

The long period between the deposition of the Fremont and the Millsap seems to 

have been one of elevation and erosion, though there is seeming conformity between 

the two limestones in local exposures. Of the Millsap itself only: remnants are found 

resting upon the Fremont limestone in Garden Park and along the western line 

toward Canyon. The formation is now represented by about 30 feet of thinly 

bedded, variegated, dolomitic limestone, with a few thin sandstone layers. Chert 

nodules in the upper part carry a limited fauna, elsewhere described. 

The Fountain formation includes a series of red sandstones, grits, and conglomerates, a part of the so-called " Red Beds." The typical locality is in the northern part 

of the quadrangle, but it seems to have essentially the same lithologic characters in 

Garden Park. The thickness is estimated at. nearly 1,000 feet. The Fountain beds 

rest unconformably upon the edges of the entire Silurian section in Red Ridge, at 

the upper end of Garden Park, and along the southern end of the Colorado Range 
RESUME OF LITERATURE. 99 

they come in contact with the Harding sandstone. Beyond the eastern line of the 

quadrangle they are usually found to abut against granite or gneiss. 

The Fountain formation is succeeded by the Morrison formation, and the Morrison by the Dakota. " The Morrison strata rest with apparent conformity upon the 

Fountain grits in the main foothill section, but in Twelvemile Park and in the higher 

plateau region to the north they lie directly upon granite. There is thus a great 

stratigraphic break between the Morrison and the Fountain formations. An extensive vertebrate fauna found in the Morrison formation shows that its age is postPaleozoic." a 

The Paleozoic series, then; in the southern part of the Pikes Peak quadrangle 

has at its base a slight development of Cambrian sediments, too thin to be mapped, 

upon which rest in succession the Manitou limestone, Harding sandstone, Fremont 

limestone, Millsap limestone, and Fountain formation. The Manitou, Harding, 

and Fremont formations represent Ordovician time, the 1VIillsap and Fountain, Carboniferous. The age of the Fountain formation is determined only by analogy; that 

of the other formations rests upon paleontologic evidence. Unconformities occur 

between the Manitou limestone and the Harding sandstone, between the Fremont 

limestone and the Millsap limestone, and between the Millsap limestone and the 

Fountain formation, while still a fourth and very important one is found between 

the Fountain formation and the overlying Mesozoic. 

The section in the northern, or Manitou Park, Paleozoic area is similar to that 

in the southern one, except that the Harding sandstone, the Fremont limestone, and 

the Millsap limestone are lacking in it. 

In connection with the field work leading up to the Leadville monograph, Whitman Cross made a visit to the 'exposures in Manitou Park, on the eastern side of the 

Front Range.' 

"Although only 50 to 75 miles distant from the Mosquito Range exposures, the 

beds were found to vary so much in lithological composition that it was impossible 

to obtain an exact correspondence of horizons. The purely siliceous beds at the base 

are much thinner than in the Mosquito Range, the greatest thickness found being 

50 feet. They are succeeded by calcareous sandstones and shales of variegated colors, 

red prevailing, which pass up into white or drab limestones, sometimes containing 

chert secretions and alternating with shaly beds, with an aggregate thickness of 

about 200 feet. These beds may be considered as the equivalents of the Lower 

quartzite and White limestone of the Mosquito Range." 

From the east bank of Trout Creek (Bergens Creek on: the Hayden map), 2 miles 

below the hotel, Mr. Cross obtained fossils which have been identified by Mr. C. D. 

Walcott, as follows: 

From reddish-brown sandstone, 45 feet above the Archean. 

a Much of the preceding digest is stated in the words of the original. 

bU. S. Geol. Surv., Mon., vol. 12, 1886, p. 62. 
100 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Lingule_pis sp. ? An elongate form allied to L. pinnwformis of the Potsdam. 

sandstone of Wisconsin. 

From red calcareous sandstones, alternating with white limestone, 105 to 122 feet 

above the Archean. 

Glytocistites (?). Single plates. Cyrtolites. 

Lingula sp. undet.; probably new. Orthoceras sp. undet.; probably new. 

Orthis desmopleura Meek. Bathyurus simillimus Walcott (?)'. 

Metoptoma new sp. 

These formations probably represent the Cambrian beds and. Manitou limestone 

of the Pikes Peak folio. 

For the same reason that the discussion of the geology of the Front Range area 

was introduced with the Pikes Peak folio, I will prefer the consideration of the 

Denver Basin monograph to accounts which preceded it in point of time. 

In 1896 appeared Monograph XVII of the United States Geological Survey, by 

Emmons, Cross, and Eldridge, describing the geology of the Denver Basin. The 

map of areal geology shows what may be taken as the limits of this area. It is 

bounded on the south by parallel 39° 30', its northern boundary being 3 or 4 miles 

north of the fortieth parallel. Its eastern boundary is about an equal distance east 

of longitude 104° 40', and its western, the edge of the Archean mass of the Rocky 

Mountains, or approximately meridian 105° 20' west. The oldest sedimentaries 

recognized are the Rocky Mountain Red Beds, which are described as the Wyoming 

formation. This consists of brilliant red conglomerates, sandstones, and shales, 

with thin limestones and gypsum in the upper, part. The thickness exposed in the 

Denver Basin varies from 500 to 3,000 feet, but is generally somewhat under 1,500 

feet. The variation, which relates chiefly to the lower beds, is accounted for as 

being due to the unevenness of the ancient floor upon which the formations were 

laid down. 

"The formation is separable about midway into a lower division of soft, friable 

conglomerates and coarse sandstones with fine shale, and an upper one of shales, with 

some prominent sandstone bands, narrow beds of limestone, and small local deposits 

of gypsum." (Page 52.) 

The lower Wyoming has below a mass, chiefly red sandstone and conglomerate, 

with a normal thickness of 1,200 feet, while the upper portion consists of the 

" creamy sandstone" 200 to 400 feet thick. The upper Wyoming contains in its 

lower half bright brick-red arenaceous shales and sandstone, with important intercalations of limestone. The strata above the limestone become more and more 

arenaceous, though still retaining in large degree their shaly nature. 

"At 150 or 200 feet below the top of the Triad the strata become more clayey 

and take on a variety of irregularly distributed bright colors—gray, yellow, green, 
RESUME OF LITERATURE. 101 

pink, and lilac. In this zone gypsum and brown earthy limestone are common." 

(Page 36.) 

The Wyoming formation is succeeded by the Morrison, consisting essentially of 

fresh-water marls, and having an average thickness of about 300 feet. Its upper 

limit is sharply defined by the Dakota sandstone. Its Mesozoic age is positively 

determined by its contained saurian remains, and it is referred to the Jurassic. The 

age of the Wyoming formation is assigned, on somewhat indirect and conflicting 

evidence, to the Triassic. 

The Wyoming formation is thought to overlie the Fountain formation described 

in the publication previously discussed, which is referred to the Carboniferous, and 

on this account a new name was given to the Wyoming beds. It is not improbable 

that the greatly varying thickness of the Wyoming formation in the Denver Basin 

may be due to the presence of local undifferentiated fragments of the Fountain series. 

The same suggestion is made by Emmons on page 19 of the monograph. 

In 1901 Darton a read a paper before the Geological Society of America entitled 

"Comparisons of Stratigraphy of the Black Hills with that of the Front Range of 

the Rocky Mountains." This paper was never published• except in abstract, in which 

form it appeared in the bulletins of the society and in Science. Speaking of the fine 

sections at Morrison, west of Denver, he says: 

"There was found an extension of the Purple (Minnekahta) limestone of the 

Black Hills, having precisely similar stratigraphic relations in the Red Beds and 

containing some of the same Permian fossils, although these are scarce and not well 

preserved. The limestone was traced south for a considerable distance, and found 

to merge into a sandy bed, which was finally lost in the great mass of coarse, red 

deposits in the vicinity of the Garden of the Gods. Its very distinct occurrence, at 

Morrison affords the means for a precise correlation with the Black Hills region. 

The underlying mass of coarse sandstones against the crystalline rocks represents 

portions, or perhaps all, of the Carboniferous formations of the Black Hills. The 

Red Beds overlying this Minnekahta limestone at Morrison are gypsiferous shales, 

similar to those of the red valley encircling the Black Hills." 

The geologic position of the horizon containing Permian fossils mentioned by 

Darton is evidently in the Wyoming formation, and his characterization of the overlying beds as gypsiferous shales would indicate that it was in the upper division, from 

200 to 300 feet below the top. Darton's correlation once accepted, the Paleozoic 

age of nearly the whole of the Red Beds of this area would be demonstrated, the 

Triassic being absent altogether or represented by a few hundred feet below the 

Morrison beds. 

However, the character of the fossils upon which this correlation is based is 

not stated, so that it is impossible to pronounce upon the weight which should 

a Geol. Soc. America, Bull., vol. 12, 1901, pp. 478-479. 
102 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

be given to it, and the fossils themselves can not be found. A small collection 

supposed to belong to the same horizon was obtained somewhat farther north, at 

Lyons, but it proves to be of little value in determining the questions at issue. It 

would be impossible to form from it a well-founded opinion as to whether the age is 

'Mesozoic or Paleozoic. A minute gasteropod, resembling 11Tatica or Natieopsis, was 

obtained, and some small pelecypods, suggesting by their shape several Paleozoic and 

Mesozoic genera. While on one hand the gasteropod is probably distinct from Natica 

with which one would first compare it, it is at the same time at present unknown 

in the Minnekahta fauna. The pelecypod also appears not to occur there. Though 

it may be the same as some indeterminable forms from the Black Hills, I believe, so 

far as the poor preservation justifies an opinion, that it is distinct. Paleontologic 

evidence, therefore, if given any weight at all in this instance, seems to be somewhat 

adverse to this correlation, which, based upon little but lithology and stratigraphic 

occurrence, can not under existing conditions be given unreserved acceptance. 

Darton further says of the horizon from which he obtained fossils at Morrison 

that it was traced southward for some distance, until lost in the coarse sandstones of 

the Garden of the Gods. These sandstones, however, are supposed to represent the 

Fountain formation, and to occur stratigraphically entirely below the Wyoming, or' 

to be equivalent to some of the lower beds included in it in certain sections. 

One of the earliest reports which relate to the geology of Colorado, and perhaps 

the earliest whose scope and method give it real scientific value, was Hayden's 

account of the geology and natural history of the Upper Missouri.° This is the first 

of a number of papers from the pen of the same author in which the geology of this 

portion of Colorado is discussed, but the later ones mark but little advance, so far as 

the Paleozoics are concerned, over this earliest contribution. The map which accompanies this report, and the report itself, extend sufficiently far west to include the 

northern half of the Front Range in Colorado and its extension into Wyoming, 

though the chief field of observation was farther east. Hayden maps a continuous 

strip of Lower Silurian, Carboniferous, Permian, and Red Beds strata (which are 

here referred to the Jurassic) along the eastern flank of the Front Range from 

Laramie Peak southward to Pikes Peak. Of the existence of these series to the 

north and east Hayden had more or less satisfactory paleontologic evidence. Their 

identification along the Front Range was influenced by the idea that the sequence 

there was complete and unbroken, and was in most cases dependent upon similarity 

in lithologic characters or evidence still less appreciable. 

The Lower Silurian of the Front Range is apparently the red sandstone and 

limestone underlying the fossiliferous 'Carboniferous limestones which play out just 

south of Colorado's northern line. King,b it will be remembered, later compared 

a Am. Phil. Soc., Trans., vol. 12, n. s., 1863, pp. 1-219. 

b U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878, p. 129. 
RESUME OF LITERATURE. 103 

these strata with the "Primordial" of the Black Hills, and tried to correlate them. 

Hayden's Carboniferous, a series of calcareous, areno-calcareous, and arenaceous 

beds said to occur on both sides of the Rocky Mountain Divide, probably includes 

the fossiliferous strata already mentioned. His Permian color, I think, must have 

been introduced on general principles without, it may be, his having any definite 

beds in mind, and certainly without any definite evidence of. their Permian age. 

Regarding this same area, Hayden writes in 1868: a 

"At the head of Pole Creek on the eastern margin and in the Laramie Plains 

west, the Carboniferous rocks are mostly of a red arenaceous character, with a few 

layers 2 to 10 feet in thickness of whitish or yellowish limestone. From these 

limestones I collected Productus prattenianus, Athyris satilita, and other wellknown Carboniferous forms. Above these red beds which contain intercalated beds 

of limestone is a considerable thickness of purely red arenaceous beds, but in studying 

all these rocks with some care from Pole Creek nearly to Pikes Peak, I could not 

separate the red beds from the Carboniferous by any break in continuity, and I was 

rather inclined to the opinion that inasmuch as a large portion of the gypsiferous or 

variegated beds could be shown to he Carboniferous they might possibly all be 

included in that period." 

In 1869 Hayden b made an extended and apparently a hasty trip chiefly along 

the eastern edges of the Rocky Mountains from Cheyenne, Wyo., as far south as 

central New Mexico. His observations deal in large measure with the eastern 

margin of the Front Range, but as they appear to be inaccurate in many particulars, and 

have been duplicated by the more detailed work of later geologists, I have made no 

serious attempt to compare or to harmonize them with known facts or present systems 

of classification. Hayden recognized the general absence of Paleozoic outcrops along 

the Front Range, and refers the Red Beds to the Triassic, with the reservation that 

they may in part be Jurassic.c But he is by no means consistent in maintaining this 

opinion, even in the course of the single paper under consideration, for, after citing 

a limestone with an undeniable Carboniferous fauna from the line of the Union 

Pacific Railroad just north of Granite Canyon,4 he says that near Park station are 

some dull-purplish sandstones and pudding stones " which are probably of Carboniferous age," e while to the same period he assigns a considerable thickness of limestone observed on Boxelder Creek in association with red Triassic sandstones/ 

The last two localities are in Colorado, but the first is in Wyoming. On the other 

hand, on page 126, the statement occurs: 

"I do not know of any portion of the West where there is so much variety 

displayed in the geology as within space of 10 miles square around Colorado City. 

Nearly all the elements of geolog cal study revealed in the Rocky Mountains are 

aim. Jour. Sci. (2), vol. 45, 1868, p. 324. 


bSee U. S. Geol. Geog. Surv. Terr., First, Seem , and Third Ann. Repts., 1873, Third Ann. Rept., pp. 103-251, 


cIbid., p. 113. dlbid., p. 111 e Ibid., p. 118. f Ibid., p. 120. 

104 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

shown on a unique scale in this locality. The same may be said, though in a less 

degree, of the valley of the Arkansas as it emerges from the mountains near Canon 

City. I am inclined to believe that it is only in these localities that rocks older than 

the Triassic or Red Beds are shown along the eastern flanks of the mountains south 

of Cheyenne. I have looked in vain for a single exposure of well-defined Paleozoic 

strata from Big Thompson to Colorado City, a distance of over 100 miles. I am 

now convinced that in the North the Paleozoic rocks are often concealed .for long 

distances, although I have usually represented them by colors on a geological map 

by continuous bands along the mountains. That they exist continuously along the 

eastern margins in Colorado and New Mexico I can not doubt, but only at these 

specially favored localities do they appear from beneath the Triassic or Red Beds. 

They are, however, far more frequently exposed farther northward, and I think 

much more largely developed." a 

Yet a little beyond, on page 133, he mentions the Jurassic Red Beds and the 

Paleozoic sandstone as occurring in Boulder Valley. 

The actual presence of the older Paleozoics at several points along the Front 

Range was recognized by Hayden, as is seen in the passages above quoted. It is 

to one of these occurrences that be refers on page 144, without assigning any 

geologic age. On pages 145 and 148, however, he cites Carboniferous beds at 

Camp Creek Canyon and at Oil Creek. From the geographic position of these 

occurrences, and from the fact that practically all the Carboniferous along the Front 

Range, if Carboniferous at all, consists of Red Beds, which Hayden places in the 

Mesozoic, and from other associated circumstances, it is fairly certain that the rocks 

mentioned in all three instances are Ordovician. 

In 1868,6 referring to the Red Beds of Colorado and Wyoming, Hayden expresses 

the belief that their lower portion is of Carboniferous age, and that it is quite possible 

that a portion is Triassic, while the yellow, gray, and rusty sands and sandstone 

above are Jurassic. This was a preliminary statement prepared immediately after 

the field work which furnished the material for the report above quoted. 

In his annual report for 1874 Hayden° again takes occasion to describe the 

geology of the Front Range. "Up to this time," he says, "we have determined 

the existence, in this belt in Colorado, of the Silurian, Carboniferous, Triassic (?), 

Jurassic, Cretaceous, and Tertiary groups; yet, while the more modern formations 

are very persistent throughout the entire distance from the north to the south line, 

some of the older beds are wanting in many places." From Fort Laramie to 

Colorado Springs, a distance of over 200 miles, no Silurian beds were recognized, 

with the possible exception of the variegated sandstones which lie next to the granite 

at Pleasant Park.. 

a Essentially the same view is expressed in different language on page 189. 

b Am. Phil. Soc., Proc., vol. 10, 1868, p. 474. 

U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, pp. 19-58. 
RESUME OF LITERATURE. 105 

Hayden speaks in some detail of the sections at Colorado Springs and Canyon, 

referring to the Silurian, at the latter, the sandstones at the base of the section, and 

600 to 800 feet of limestones lying above. The thickness in the latter case is 

probably erroneous, for in Peale's section at Glen Erie there are only 300 feet of 

beds which are, with any probability, Silurian. Hayden compares the sandstone 

at the base.of the section at Canyon with "the Potsdam sandstone as seen in other 

localities farther 'to the north." But the sandstone at Canyon is Ordovician in age, 

and not Cambrian. This sandstone passes up into a hard and rather massive 

limestone, evidently the same as that noted at Colorado Springs." This correlation 

is a very natural one, but at the same time is probably incorrect, for the limestone 

at Canyon, what part of it is not Carboniferous in age, is the Fremont liniestone, of 

which Cross states that it has not been recognized in other sections along the east 

base of the mountains. 

Of the Carboniferous he speaks in a general way, touching chiefly upon its 

distribution. He says: 

"The Carboniferous group is a little more persistent, and yet this seems to be 

wanting over extended intervals unless a portion of what have been called the Red 

Beds is of this age. This group is extensively exposed along the flanks of the mountains 100 to 150 miles north of Cheyenne, as was shown in the annual report of 1870. 

It seems, however, to diminish somewhat in force and to contain comparatively few 

fossils in its southern extension until we reach Canon City. From thence southward into New Mexico it increases again in thickness and importance, and yields an 

abundant supply of its characteristic fossils." 

The Red Beds he refers to the Triassic, with some admitted uncertainty on 

account of the general lack of fossils. This group, he says, "is very persistent, 

and if absent at all, only at very short intervals." "Geographically, it is one of the 

most widely distributed formations in the West. From the northern boundary to 

the southern line and east of the Wasatch Range in Utah this red formation makes 

its appearance wherever a mountain range is elevated so as to expose the various 

sedimentary groups. The evidence indicates that it extends without any important 

interruption over the broad area as defined above." He states that this series varies 

in color from a pale, dull tint to a deep purple, in texture from a rather coarse conglomerate to a fine sandstone, and in thickness from 400 feet •to 2,000 feet. He 

remarks (page 43) that he formerly held the view that the elevation of the Front Range 

was a single event and comparatively modern, and that the changes in the position of 

all the groups were brought about by the same cause and at the same time. "There 

could not be a strict conformity in the sedimentary groups, inasmuch as entire groups 

are wanting, and in some cases only fragments of others are remaining." " We 

now have the evidence, from the texture of these Red Beds and their position on the 
106 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

underlying granitic rocks, that the Front Range, during the supposed Triassic period, 

formed a vast shore line, and that the sediments of the Red Beds were deposited upon 

the base against the sides of the granitic range." It seems probable, indeed, that 

this condition has been one of periodic occurrence, and that the Front Range represents a line of permanent weakness which has been repeatedly elevated, denuded, 

and submerged. 

Peale's district for 1873 a includes, besides other territory west of this, the 

Front Range from the South Platte to Colorado Springs. Important detailed 

sections were made on the South Platte, through Pleasant Park, and at Glen Erie, 

and four others of almost equal interest were described from Trout Creek. The 

strata in the Front Range sections are classed as Silurian, Carboniferous, Triassic, 

Jurassic, and Cretaceous. 

The southern part of the Trout Creek or Manitou Park Paleozoic area is included 

in the northern part of the Pikes Peak quadrangle, which in its southern portion 

embraces a larger area of the Paleozoics about Canyon. In the section given 

by Cross for that portion of the Manitou Park area included in the Pikes Peak 

quadrangle, the Ordovician, as we have just seen, is represented only by the 

Manitou limestone, and the Carboniferous by the Fountain formation. The four 

sections given by Peale deal only with the strata which underlie the Red Beds, or 

Fountain formation, which are mapped as Triassic, and therefore only with the 

Cambrian rocks and the Manitou limestone. The Millsap limestone apparently is 

entirely lacking, and the Hayden atlas shows no Carboniferous color in this area. 

The Cambrian is shown by Peale's sections to be considerably thicker here than 

in the Pikes Peak quadrangle. It consists of yellow, purplish, pink, and green 

sandstones, reaching a thickness in one case of 80 feet, from which Cambrian fossils 

(Obolus , and Lingulepis) were obtained. The Manitou limestone contains red, 

white, and pink limestones, attaining in one instance a. thickness of 130 feet. A 

well-characterized Ordovician fauna was obtained from them. 

In the section made at Glen Erie, whose outcrops are all but connected with 

those of the Manitou Park area, the best-characterized bed is that numbered 13, which 

by reason of its fossils, its character, and its position clearly belongs to the Manitou 

limestone. With it can probably be associated the 26 feet of variegated calcareous 

beds next below, as indicated by Peale, while the sandstones forming the base of the 

whole section are probably Cambrian. Above bed 13 follows 279 feet of gray, 

purplish, and yellowish limestone, unfossiliferous and not otherwise differentiated. 

From the fact that there is no fossil evidence indicating that any portion is of 

Carboniferous age, and that the Millsap limestone, so far as is known, is absent from 

the Manitou Park area, this entire thickness may be regarded as belonging to the 

a U. S. Geol. Geog Surv. Terr., [Seventh] Ann. Rept., for 1873. 1874, pp. 193-273. 
RESUME OF LITERATURE. 107 

Manitou limestone. On the other hand, the horizon of the Milisap limestone is 

certainly present at Pleasant Park, and its occurrence in this region is too fickle to 

admit of a strong presumption based upon its presence or absence in neighboring 

areas.a The Trias belongs to the Fountain formation or to the Fountain and 

Wyoming combined, and the Jurassic has the characters of the Morrison formation. 

Considering next the section through Pleasant Park and comparing it with that 

of the Pikes Peak quadrangle, a convenient point of departure is found in bed 8, 

which, with but little doubt, belongs in the Milisap limestone. It is impossible at 

this distance and without further information to reach a conclusion as to whether the 

beds below this horizon are all Carboniferous, as Peale has it, or in part earlier 

Paleozoic. The 80 feet of white sandstone at the base of the section, and the other 

sandstones above, in position and character are so like the Cambrian of the Glen 

Erie section as to suggest to my mind that perhaps they are equivalent beds. 

However, the fact that this correlation did not recommend itself to Peale, who was 

personally acquainted with the sections, is an impeachment of its correctness' At 

all events in the fossiliferous, calcareous stratum (bed 8), and probably in the thin 

limestone just below, we are assured, all things considered, of an equivalent of the 

Milisap limestone and the presence of Lower Carboniferous sediments. The Triassic 

of the Pleasant Park section probably represents the Fountain formation in part and 

in part the Wyoming. The Jurassic corresponds to the Morrison formation, and 

the massive sandstone which overlies it, `.` No. 1 Cretaceous," as it is called, to the 

Dakota sandstone. The thickness of the Red Beds is here about 1,500 feet. This is 

about the average thickness of the Wyoming formation, which was described from 

the area of the Denver Basin, near by. But the Fountain beds also are known not 

far off, in the northeast corner of the Pikes, Peak quadrangle. Lee refers part of 

this series to the Carboniferous and correlates it with the Fountain formation, while 

the portion which he calls " Trias," though not accepting this as its true geologic 

age, probably finds its equivalent in the Wyoming formation. 

Section No. 1 of Peale's report, which was taken on the south side of the South 

Platte River, comprises about 4,000 feet of strata referred to the Triassic, Jurassic, 

and Cretaceous. The Triassic, which here rests immediately upon the granite, 

consists of from 1,500 to 2,000 feet, chiefly of red and red and white sandstones, and 

600 feet of white sandstones overlying them. The locality where this section was 

made is probably just included in the southwestern corner of the Denver Basin. 

There can be little doubt that the Dakota sandstone of the Denver monograph is 

a Mr. A. W. Grabau has recently informed me that he has collected a Carboniferous fauna from the upper portion 

of this limestone. It is not probable that this is an Upper Carboniferous limestone, and the conclusion seems safe that it 

represents the Millsap formation. Whether the entire thickness belongs to the Milisap or the lower part represents the 

Manitou limestone can not be ascertained. 

b Hayden, however, suggests the same thing, for he writes, remarking upon the Calciferous group' "It is possible 

that in Pleasant Park, about 50 miles south of Denver, there are traces of this formation in the variegated sandstones 

that lie next to the granites, as shown in the section." (Ann. Rept. for 1874, p. 41.) 
108 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the basal member of Peale's Cretaceous (bed 7). Beneath this, in Peale's section, is 

a space estimated at 600 feet, a portion of which only is equivalent to the Morrison 

formation, as the latter has an average thickness of but 200 feet. The remainder 

and major portion of Peale's Jurassic, and his Triassic, having a maximum aggregate 

thickness of 3,100 feet, must be included in the Wyoming formation. The heavy 

bed of white sandstone (No. 14) forming the top of Peale's Triassic is probably the 

"creamy sandstone" which constitutes the upper member of the lower Wyoming. 

The Wyoming formation is referred to the Trias in the Denver Basin monograph, 

but, as already pointed out, in view of the great variation in thickness of the lower 

member, especially if the Fountain formation does occur as near as at Perry 

Park, it seems probable that the heavier sections of the Wyoming may include 

at their base portions of a distinct series, most likely the Fountain beds. This 

has been suggested also by Emmons, one of the joint authors of the Denver Basin 

monograph. 

The beds here at the base of the section resemble those in Pleasant Park 

similarly situated. The latter, I suspect, may prove to be Cambrian, and the 

resemblance noted suggests the possibility that the base of the section here also may . 

be of Cambrian age. The Millsap limestone, if the name may still be applied at 

Pleasant Park, had there thinned to complete insignificance, and if absent altogether 

the Red Beds of the Fountain formation would rest immediately upon the basal 

sandstones. It seems more probable, however, that the whole early Paleozoic 

section is here missing. 

In a recently published paper W. T. Lee a describes the areal geology of the 

Castle Rock region. Except for the Red Beds, the only Paleozoics described occur 

'in Perry Park. No detailed section is given and the characters of the geologic 

sequence described may be condensed as follows: The only Cambrian outcrop occurs 

6 miles south of the area mapped, near Deadmans Creek. It is a•deep-red quartzite 

25 feet thick and corresponds in character and stratigraphic position with a similar 

quartzite in Manitou Park referred to the Cambrian in the Pikes Peak folio. Above 

the red quartzite appears a series of cherty limestone layers interstratified with 

red clay. Some obscure brachiopods, identified as Dalmanella testudinaria, indicate 

that the age of this bed is Ordovician. 

The Carboniferous is thus described: 

"At the base of the formation occur 40 feet of coarse-grained, crumbling sandstone, conglomeratic in places and mottled in varying shades of red and gray. 

Above this sandstone is a series, 10 to 15 feet thick, of deep red to white cherty 

limestone in layers, alternating with red shale. Near the top of this series is the 

fossiliferous seam. Above is a series of several hundred feet of coarse-grained 

a Am. Geol., vol. 29, 1902, pp. 96-109. 
RESUME OF LITERATURE. 109 

sandstones and conglomerates, which appear to be perfectly conformable with the 

fossiliferous series. They are colored irregularly in various shades of red and gray 

to an extent which gives the series a conspicuous mottled appearance. The gray 

predominates near the base. From thence upward the red becomes prominent and 

the series passes gradually into the, so-called Trias'—the Red Beds. No line of 

demarkation was found between this formation and the Trias." 

The fossils mentioned, together with a series collected by Whitman Cross, are 

discussed in the paleontologic portion of the present paper. Of the Carboniferous 

age of this fauna there can be no doubt, and it can safely be referred to the Lower 

Carboniferous. The upper portion of Lee's Carboniferous section he correlates, 

by stratigraphy and lithology, with the Fountain beds of the Pikes Peak quadrangle, and the opinion seems to be entertained that by this series, together with the 

typical Red Beds into which it graduates, the Carboniferous and Permian, as well -as 

the Triassic periods are represented. A nearly vertical series east of the park 

undoubtedly belongs to the Red Beds proper (Lee). 

The relation of the beds in Lee's map is such as to indicate an unconformity 

by overlap of the Red Beds, which seem to be the Wyoming formation of the 

Denver Basin area, upon the supposed equivalent of Cross's Fountain formation. 

Peale's section in Perry Park, or Pleasant Park, as it appears to have been called 

at that time, must include the same strata described by Lee. Peale refers all the 

lower part' of the section down to the granite to the Carboniferous, as does Lee, but 

I inclined to identify as Cambrian the sandstones at the base of his section, founding 

the opinion upon the resemblance in lithology and position to strata in other near-by 

sections from which he reported Cambrian fossils. Hayden also suggests the possibility of the view held by me. All the lower part of Peale's section below the Red 

Beds seems to be equivalent to Lee's Carboniferous (except the part supposed to 

represent the Fountain formation). The fossiliferous limestone at the top in each 

case is the Millsap limestone. Of this, Peale cites 9 feet, and Lee 10 to 15 feet. 

As occurring beneath the limestone, Peale mentions 105 feet of red, white, and 

purplish sandstones, while Lee finds 40 feet of red and gray sandstones. The 

differences so far noted are not important, and doubtless result from the two sections 

not having been made at the same exposures. The sandstones in Peale's section, 

however, rest on granite, while in Lee's section one would infer that they were 

underlain by the Ordovician limestone already referred to. The Ordovician limestone, however, appears not to have been found in the Castle Rock quadrangle, but to 

have occurred with the red Cambrian ( ?) quartzite south of the area mapped by Lee. 

Several interesting possibilities present themselves. The most probable is that 

the sandstones under the Millsap limestone are really not Carboniferous, but Cambrian, and that the place of the Ordovician limestone is not below but above them, 

the limestone itself having been cut out by the erosion by whicn the Millsap lime-
110 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

stone is known to have been preceded. If Lee is correct in placing the Ordovician 

beneath the sandstone, the latter either belongs with the Millsap, as Lee and Peale 

have it, and is a new element introduced into the formation, or else it represents the 

Harding sandstone, the Ordovician limestone in all probability being the Manitou. 

This seems to me altogether improbable, as the Harding sandstone appears to be 

wanting north of Garden Park. • 

Peale's Trias, of course, is the more or less precise equivalent of Lee's Red Beds,: 

including also the sandstones and conglomerates lying above the Millsap limestone, 

which he places, in the Carboniferous. The raison d'etre for the introduction into 

literature of the name Wyoming appears to have been that it was supposed to be 

Triassic and of later geologic age than the Fountain formation which Cross provisionally referred to the Carboniferous. Although in the Pikes Peak quadrangle the 

Fountain beds are followed by the Morrison formation, east of the Pikes Peak area 

the Wyoming formation is supposed to. intervene. As Perry Park is intermediate 

between the Denver Basin and the Pikes Peak quadrangle, and as the Red Beds 

there seem to have the characters of the Fountain formation in the lower part and 

of the Wyoming formation in the upper part, it seems not improbable that the distinction made by Lee is correct. The Wyoming and Fountain formations and their 

supposed equivalents in other areas have the appearance of being continuously 

deposited, but the evidence of overlap here and in the Dolores River region seems 

to prove that this was not the case. 

The area immediately north of that surveyed by Peale in 1873 was examined by 

Marvinea the same year. Th s, the Middle Park division, contains no beds referred 

by him to the Carboniferous or even to the Paleozoic, but as I regard the Red Beds 

which he maps as Triassic as possibly Carboniferous in age, his remarks upon that 

division are germane to our study. The area embraced by the Middle Park division 

is included between parallels 39° 30' and 40° 20' north latitude and meridians 104° 45' 

and 106° 30' west longitude. It contains three topographic and geologic areas, the 

plains, the mountains, and the park, but it is only in the plains skirting the mountains that any of the so-called Triassic beds occur. They are there continuous with 

the series which Peale describes under the same name, and they extend without break 

to the northern limit of the Middle Park district. Their occurrence here differs 

both from the exposures to the north in Wyoming and those to the south in Peale's 

district in having no recognized Carboniferous beneath, resting directly upon the 

smoothed but uneven surface of the granite. The Red Beds vary in thickness in 

this area from over 1,600 to 2,000 feet down to 400 feet. The thinnest sections are 

found a few miles north of Golden, from which point the series thickens rapidly to 

the north and to the south. The color is for the most part a dark red, though in 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 83-192. 
RESUME OF LITERATURE. 111 

some places lighter colors predominate. In texture the rock is a sandstone with 

coarse grits and shaly layers. Though conglomerates may occur anywhere in the 

series, they are mostly confined to near the base, where they are often plainly 

derived from the subjacent rock. In this series, and in the Jurassic above, no fossils 

of any sort were found. 

The area of Marvine's district completely embraces that of the Denver Basin 

monograph, and Marvine's Triassic and Jurassic in a general way correspond to the 

Wyoming and Morrison formations of the latter. Marvine's district also adjoins 

Peale's on the south, and from the uniformity in the thicknesses assigned to the 

Triassic and Jurassic by the two authors in their respective areas,a it seems that the 

same limits were adopted by both for these formations. As, in the case of Peale's 

Jurassic, it was found that only the upper portion belonged in the Morrison formation, as defined in the Denver monograph, so it seems necessary to assign to the 

Wyoming formation the lower part of Marvine's Jurassic, to which he gives a 

thickness of 770, 660, 870, and 400 to 500 feet in different sections, while the 

Morrison averages but 200 feet. As I have had occasion to remark in connection 

with Peale's report and the Denver monograph, the great variations in the thickness 

of the Wyoming formation as measured at different points may be due to the presence 

and inclusion of local undifferentiated remnants of the Carboniferous Fountain beds. 

It is too well known to require repetition that the field of observation of the 

King survey was along and chiefly to the north of the fortieth parallel, and that it 

included a strip quite across the State of Colorado whose northern boundary is the 

forty-first parallel. Within this occur two areas of Paleozoic outcrop. One of these 

is found in the Uinta Mountains and their outliers; the other consists of two narrow 

strips--one on the east, the other on the west side of the Front Range. The report 

of this survey as it relates to the Uinta Mountains has been discussed elsewhere. I 

will here consider its discussion of the Paleozoics along the Front Range. It might 

be added, however, that, instead of the original descriptive account by Arnold Hague, 

I have considered especially the summary report by King,b in which much the same 

facts are presented in a more convenient arrangement. 

The beds referred to the Paleozoic by King on the east side of the range begin 

just south of the, forty-first parallel, but on the west side they do not come in until 

some distance north of it, and therefore are not strictly within the limits of my paper; 

but as their northern continuation bears somewhat upon the construction to be placed 

upon the succession farther south, I will summarize King's remarks upon them. 

King's discussion, unfortunately, begins with a misstatement of fact, which, 

though unimportant, nevertheless stands open to correction. He says: " In Colorado 

a In the South Platte section, as I have already had occasion to quote from Peale, the thickness of the Trias is from 

1,500 to 2,000 feet. 

b U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878, pp. 127-139, 249-259. 
112 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Range, between Colorado Springs and latitude 41°, the lowest sedimentary rocks 

found in contact with the metamorphic A rchean series are sandstones of the Triassic 

age." In fact, however, the Hayden maps show CarboniferouS rocks at the head of 

West Plum Creek, north of Colorado Springs, and there is reason to believe that 

some of the Paleozoics still exist in the canyon of the South Platte. 

On the east side of the range, according to King, except for Tertiary overlaps, 

there is a continuous chain of Paleozoic outcrops from the headwaters of Boxelder 

Creek for 70 miles northward. Here the total Paleozoic series is limited to 850 feet. 

Of this the lower 150 feet consist of red limestones and a reddish sandstone of varying fineness. The upper portion consists of gray and blue arenaceous limestone and 

calcareous sandstone. At the base of the upper division Upper Carboniferous fossils 

occur. The species cited are Productus cora, Productus semireticulatus, and Seminula 

subtilita. King compares the rocks of this area, both as to lithology and to sequence, 

with those of the Black Hills, and comes to the conclusion that the lower series here 

is the same as the Primordial of that area. He believes, indeed, that into the 150 to 

200 feet of beds below the horizon bearing Coal Measure fossils is condensed a complete and conformable series of all the sedimentation of Paleozoic time prior to the 

Upper Carboniferous. He says (p. 129): "Although we have actually found no 

fossils in this horizon [the lower division], we feel the greatest confidence in asserting 

that the whole Paleozoic series, from the Primordial to the Triassic, is here compressed within the 850 feet." And again (p. 132): "It may be predicted that sooner 

or later the missing horizons between the Trias and the Cambrian are likely to be in 

large part discovered, for in an ocean in which undisturbed deposition took place 

from the beginning of the Cambrian to the close of the Mesozoic age no great period 

of time would be likely to elapse without sedimentation, and it is to be predicted 

that one after another the now missing main horizons will be identified, even if 

reduced to extreme thinness." And also (page 138): "Although they are barren of 

fossils, from the downward sequence of beds, we have no doubt whatever that the 

red sandstones, conglomerates, and quartzites underlying the Carboniferous limestones belong, as we have correlated them, with the Primordial of the Black Hills 

and Colorado Range. On the east side of Laramie hills the Paleozoic series reaches 

its greatest compression, namely, 800 feet in thickness. There is absolutely no 

unconformity from the base to the summit. Therefore in this thin deposit is represented all the time from the Cambrian to the Trias, and yet organic life is only 

represented by types of the Coal Measure epoch and the Permian." 

This hypothesis hardly deserves consideration at this day, but it is possible that 

the lower beds of the section may be, as claimed by King, pre-Carboniferous. 

Possibly the apparent nonconformity by overlap, cited by King, from the south 

branch of Crow Creek, by which the lower part of the section is missing and the 
RESUME OF LITERATURE. 113 

upper is in contact with the Archean, should be regarded as evidence favorable to 

this view. But the strata at this point have a nearly vertical position, and this 

circumstance suggests that the thinning of the series here may be due to structural 

causes. The fact that King compares the compact conglomerate, which is the lowest 

bed exposed, with one " which is interstratified far up in the limestone, as seen 

at various points on the western slope," would seem to indicate that if an actual 

overlap the horizon of transgression does not coincide with the top of the lower of 

the divisions recognized by him, but took place at a higher level. On the whole, I am 

disposed to consider it more probable that the lower beds belong to the same series 

as the upper• and that all are of Pennsylvanian age. The paleontologic evidence 

necessary to settle this point one way or the other is as yet unfortunately wanting. 

"Along the west flank, as already mentioned, the series makes a continuous 

outcrop from the northern limit of the map to a point 2 miles north of the Pacific 

Railroad, where it is overlapped by the conformable red Trias." "Always next to 

the Archean series occur the red sandstones, which we correlate with the Black 

Hills Primordial, presenting toward the east a rather abrupt, but low, mural 

outcrop." Here, however, a greater thickness of the whole series is developed ,than 

on the eastern side of the range, for it contains beds amounting to 1,200 feet. " On 

the western side no fossils were obtained from the uppermost members, but distinct 

Coal Measure types were obtained within 200 feet of the base." The species, which 

are the same as found to the east, consist of Productus semireticulatus, Productus 

costatus, Productus cora, Seminula subtilita, Bellerophon sp., and Orthoceras sp. 

Much the same series, apparently, occurs at several points in the Medicine Bow 

Range, but at Rawlins Peak is one which rather suggests that in central Colorado. 

At the base is about 700 feet of gray and white quartzites and "sandstones, the 

uppermost bed being a ferruginous sandstone 15 feet thick. These are suggestive 

of the Sawatch quartzite. The drab lithographic and white siliceous limestone next 

above may possibly represent the Yule limestone, while the dark blue, earthy 

limestone with Pleurophorus oblongus and Productus, both as to color, position, and 

fossil content, shows points of resemblance with the Leadville limestone, in which 

Whitfield identified Pl. oblongus at Leadville.a The gap of 500 feet not far above, 

which is supposed to be largely made up of calcareous and. argillaceous beds, 

possibly represents the Weber formation. "Above this is another gap, without 

outcrop, of 400 feet, limited above by the distinct and characteristic Triassic beds."h 

Apparently in the Triassic near its base was found the species Natica ? Lelia, which 

King believes to indicate the top of the Permian, but which is now generally placed 

in the Mesozoic. Considered by itself, this species can hardly be allowed much 

diagnostic force, and from this locality, at all events, no associated fauna is known, 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 66. b U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878, p. 137. 

14364—No. 16-03 8 
114 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

King seems to take it for granted that the siliceous bed at the base of the Rawlings 

Peak section is the same as that occurring in a similar position .on the flanks of the 

Laramie Mountains, but as the latter consists of red sandstones and red limestones, 

and the former of whitish quartzite without any limestone at all, there seems to be 

room for skepticism. If my conjectures prove at all true, the geologic ages of the 

two are entirely different. 

As previously noted, south of the forty-first parallel, the strata bordering the 

Archean nucleus and resting upon it belong to the well-known Rocky Mountain Red 

Beds of supposed Triassic age. Locally, at several points south of this parallel, and 

more generally north of it, the Red Beds are underlain by strata of recognized Paleozoic age. King states that the relative position of the Red Beds and Paleozoics is 

one of conformity, but from the marked overlap of the Red Beds, it seems clear that 

the conformity can be only apparent. 

"The beds along the southern limit of the map, bordering the Big Thompson and 

the Cache la Poudre, attain a thickness of 800 to 850 feet, thinning thence northward 

and reaching a minimum in the region of Horse and Lodgepole creeks, where they 

scarcely attain 300, but thickening again in the region of Chugwater and Bush creeks 

to nearly 700 feet. 

" On the western borders of the range the conditions thus sketched are repeated. 

North of the Union Pacific Railroad the soft, easily eroded beds of the Trias, varying from 400 to 800 feet in thickness, rest directly upon the uppermost limestones of 

the Coal Measures. South of the railroad the Trias overlaps, and, as on the eastern 

side of the range, comes in contact with the Archean. 

"Taken as a whole, and with the exception of the gypsum and limestone beds, which 

nowhere within our field of observation exceed 40 feet in thickness, it is essentially 

a sandstone series, for both clays and shales are exceedingly arenaceous, and the 

dominant color is a brick red for the lower half of the series, and variable lighter 

reds, pinks, and yellowish reds for the upper half. While this division of color holds 

good in general, it is often varied by extremely brick-red, almost vermilion-colored, 

beds appearing near the top, and light ones intercalated in the region of the heavy 

red lower strata. 

"The Red Beds of Colorado Range have thus far yielded to our search no organic 

remains, saving obscure pieces of half-petrified, half-carbonized wood, which crumbles 

on exposure to the air, and displays no characteristic structure." 

The distribution of the Triassic, so far as concerns the region discussed by King, 

consists chiefly of two strips, one on the eastern and the other on the western side of 

the Colorado Range, of an area of outcrops at Elk Mountain at the northern extremity 

of the Medicine Bow Mountains, of another at Rawlins Peak, of a bordering of 

outcrop on both sides of North Park near its northern end, and of one on both sides•of 

the Uinta Mountains. In North Park the thickness is nearly 1,000 feet, and in the 

Uinta Mountains in the region of Vermilion Creek it is 2,000 feet. 
RESU3Ii OF LITERATURE. 115 

It seems probable that this upper brick-red series is the Wyoming formation of 

the Denver Basin area, while all the series between it and the Archean, part of which 

contains Carboniferous fossils, may be the equivalent of the Fountain formation. 

Because of their stratigraphic position and of the lack of fossil evidence as to 

the age of the Red Beds (by which term is here designated the upper or " Mesozoic" 

portion), King, as we have seen, refers them to the Trim.° 

Quite recently W. C. Knight b reported the discovery of a Carboniferous fauna 

in the Red Beds of Wyoming. The locality is near Red Mountain, on the Colorado 

line, in the Laramie quadrangle, where the King atlas represents the Triassic as 

overlapping the Carboniferous and resting upon the granite. The horizon is about 

725 feet above the base of the series, whose whole thickness is given as 1,578 feet. 

Knight states that the calcareous beds which King maps as Carboniferous a little 

farther north do not in reality underlie the Triassic series of Red Mountain, but, 

merging into it, are equivalent to its lower portion. He remarks on page 420: 

" Just what proportion of the Red Beds will be equivalent to the limestones has 

not been determined, but probably not less than 500 feet of the strata near the Colorado line will correspond to limestones and light-colored sandstones some 15 or 20 

miles to the northward, and possibly a greater thickness." 

Of the Carboniferous age of the fauna found at Red Mountain it is impossible 

to entertain a doubt, but one may not draw from this occurrence any strong 

inference as to the age of the beds above, of the "Triassic" series farther north, or 

of the Wyoming formation of the eastern flank. A question may well be raised, 

however, as to the existence _of the series consistently called "Triassic" by King 

and other authors; or, in other words, since the lithologic characters which locally 

distinguish the Carboniferous and "Triassic" beds break down within so short a 

distance as 20 miles, leaving the series uniform and indistinguishable, whether 

there is sufficient evidence to warrant separating 800 feet at the top and placing so 

important a division line as that between Paleozoic and Mesozoic in the midst of 

so thin and uniform a series. The consideration of this question is bewildered 

through the lack of paleontologic data or of refined stratigraphic evidence, of which 

we have some, but far too little. However, the Red Beds, including the so-called 

"Triassic," of this general area may prove to be Carboniferous, as suggested by 

Knight; but a closely similar case may be instanced in the Rico and Dolores formations of the San Juan region, where fossils seem to demand a division. 

Probably the first account of the Paleozoics about Canyon is to be found in 

Ruffner's report on a reconnaissance in the • Ute country, published in 1874.° 

Hawn's description contained therein amounts to little more than a mere mention of 

a U. S. Geol. Expl. 40th Par., Rept., vol. 1, 1878, p. 249 


bJour. Geol., vol. 10, 1902, pp. 413-422. 


c Ruffner's Rept. Recon. in the Ute Country, 43d Cong., 1st sees., House Ex. Doc., No. 193, 1874. 

116 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the beds, without any attempt to determine their age. He says: "On descending 

again later in the day we met heavy formations of limestone dipping at nearly 

every angle and crowning some of the high foothills. These strata are hard, 

cherty, massive, and compact. They soon disappear with a general dip toward the 

east. We then pass on to thick beds of conglomerate ferruginous oxides, cementing 

rounded pebbles and water-worn bowlders." (Page 81.) The heavy limestones can 

probably be safely identified with the Ordovician and Mississippian limestones, which 

have subsequently been named the Manitou, Fremont, and Millsap formations. The 

conglomerates are possibly the Fountain beds. On page 81 fish remains are cited 

from Canyon, and it seems probable that they were derived from the horizon their 

occurrence in which has caused especial interest to attach to the Ordovician of this 

locality. 

In 1876 S. G. Williams published a section along Oil Creek from the head of 

Oil Creek Park to the Arkansas River. a The essential portion of this section lies 

within the limits of the Pikes Peak quadrangle, and it is possible to identify 

Williams's formations with some accuracy. The whitish limestone at the base of 

his section (No. 1) is, with little doubt, the Fremont limestone. Fifty feet were 

measured and the bottom not seen. The mottled marble above (No. 2), 15 feet thick, 

is the Millsap limestone of Cross. The three red sandstones overlying (Nos. 3, 4, 

and 5), which have a combined thickness of 1,140 feet, can be no other than the 

Fountain formation. Williams says: 

"Nos. 1 and 2 are probably Carboniferous; rocks holding the same relative 

position in the Arkansas Canyon, and from which I have fossils, are certainly of that 

age." 

If my correlations with Cross's section are correct Williams is of course mistaken as to the age of his lowest bed. 

In 1892 C. D. Walcott described the geologic section at Harding's quarry, about 

1 mile northwest of Canyon. e He distinguishes, describes, and names the Harding 

sandstone series and the Fremont limestone series. The former included beds 1(a to 

f); the latter, beds 2, 3, 4 (a—c), and apparently 5 of his section. Fossils of Ordovician age were found in lc and a few in lb, just below. The latter are indecisive, 

but probably indicate the same age. Bed 4c contains a large and varied fauna of 

the Trenton type. Bed 5 consists of impure variegated limestone with interbedded 

sandstones and argillaceous shales, and has a thickness of from 15 to 30 feet. It 

contains a few species of fossil Brachiopoda which are correctly assigned to the Carboniferous. It thus appears that probably the whole of this section except its upper 

aU. S. Geol. Geog. Surv. Terr., Bull., vol. 1, 2 ser., 1876, pp. 249-251. 


b Ibid., p. 249. 


eGeol. Soc. America, Bull., vol. 3, 1892, pp. 153-172. 

RESUME OF LITERATURE. 117 

bed is of Ordovician age. There seem to be no traces of the Silurian and Devonian 

groups. 

Comparing this section with that in the Pikes Peak quadrangle near by, we find 

both the Harding sandstone and the Fremont limestone recognized as such, Cross 

having adopted the names from the Canyon exposures. Bed la of Walcott's section 

rests directly upon gneiss and schist, while in the Pikes Peak quadrangle, beneath 

the Harding sandstone, is found another limestone formation, named the Manitou 

limestone, and an inconsiderable thickness of Cambrian. The Cambrian and part of 

the Ordovician, therefore, seem to be missing in the Canyon section. 

The propriety is somewhat doubtful of including in a single formation beds of 

geologic age as diverse as Ordovician and Carboniferous, and Cross has therefore 

distinguished the Carboniferous portion of the original Fremont under the name of 

the Millsap limestone. 

In the third volume of the Wheeler Survey is a report by Stevenson, in which 

the geology of a large portion of Colorado is described.a Carboniferous is reported 

in a number of areas. Neither Silurian nor Carboniferous rocks are recognized 

along the Front Range, however, and the opinion is expressed that their western 

outcrop is far to the east of the base of the mountain, deeply buried under the more 

recent formations.b The series of red sandstones and conglomerates which was 

observed from Golden to the Greenhorn Mountains this• author refers to the Triassic. 

At Beaver Creek, a few miles northeast from Canyon, a thickness of 2,700 feet is 

ascribed to it. At Manitou a bed of shale and another of limestone were observed 

at the base of the Triassic, and the suggestion was put forward that they might be Carboniferous. The Triassic is said to be unconformable with the overlying Jurassic, 

which is in turn conformable with the Cretaceous. The Jurassic on Oil Creek near 

Canyon consists of light-colored sandstones and shales, amounting in all to about 

120 feet, overlying a limestone. 

Stevenson's Jurassic corresponds in geologic position, lithologic character, and 

thickness with the Morrison formation. His Triassic appears to include in different sections now the Wyoming formation, now. the Wyoming and Fountain, and 

again only the Fountain formation. Beaver Creek, the point at which he records an 

estimated thickness of 2,700 feet of Triassic strata, is in the extreme southeastern 

corner of the Pikes Peak quadrangle. His " Triassic " corresponds in this instance 

only to the Fountain beds, but as Cross gives this formation a thickness of but 

1,000 feet, it seems that that assigned to it by Stevenson was overestimated. 

While the "Triassic" of Stevenson embraced in the main only the Rocky Mountain Red Beds, in the limestones seen at Manitou it probably includes some Ordovician 

as well. However, the distribution along the Front Range of the older Paleozoics is 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, pp. 303-501. 

b Ibid, p. 376. 
11 8 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

so sporadic that with this exception it might easily be that none came under his 

observation. 

The Pueblo quadrangle corners with the Pikes Peak quadrangle, which lies 

immediately to the northwest, and it is bounded upon the south by the Walsenburg 

quadrangle. Many of the formations occurring in the Pikes Peak are found also in 

the Pueblo quadrangle. The Paleozoic section consists of the Harding sandstone, 

Millsap limestone, and Fountain formation, above which follows the Morrison 

formation. 

The Cambrian and the Manitou limestone of the Pikes Peak quadrangle appear to 

be wanting in the one under consideration, the earliest deposits preserved being a white 

sandstone which rests on the Archean, and which Gilbert correlates with the Harding 

sandstone. Above the Harding follows a series of gray and purple limestones 200 

feet in thickness, with some shales in the lower part and with 30 feet of coarse gray 

and red sandstone on top. This series Gilbert calls the Millsap limestone, from 

which it would appear that the Fremont limestone of the Pikes Peak quadrangle is 

regarded as absent. His position upon this point is stated as follows: 

"In a bed near the middle of the overlying limestone were found a few fossil 

shells of Spirifera rockymontana, -a Carboniferous species found also in the Millsap 

limestone of the Pikes Peak quadrangle, but nothing was found to mark the presence 

of the Fremont limestone (Silurian), which in the Pikes Peak district separates the 

Harding and Millsap formations. The application of the name Millsap to the whole 

series of the Pueblo district is a somewhat arbitrary procedure, and is subject to correction when more facts are available." 

As the Millsap limestone in the Pikes Peak quadrangle is only 30 feet in thickness, and as the Fremont is reported by Cross as 270 feet at Canyon, the natural 

expectation would be that the Millsap would be the one to die out in the Pueblo 

quadrangle. There can, however, be little doubt of the upper half at least of 

Gilbert's Millsap being correctly correlated. In any event, that formation shows a 

much increased thickness, and should it prove that the whole bed represents the 

it will afford but one more instance of the sporadic and fragmentary representation of the Paleozoic horizons alqng the eastern line of the Front Range. It is 

not clear whether Gilbert includes in the Millsap the 30 feet of sandstone above the 

calcareous portion, but this would seem to be the case. One would think that these 

beds belonged to the Fountain formation. In view of the conditions observed in 

the Pikes Peak quadrangle I do not see how there could be conformity between 

the Millsap and Harding formations in the Pueblo quadrangle, especially if the 

Fremont limestone is absent, so that the Millsap rests on the Harding. 

The Fountain formation in the Pueblo quadrangle has a thickness of 2,100+ feet, 

as against a maximum of 1,000 feet in the Pikes Peak quadrangle. The question 

might be raised whether a part of this does not represent the Wyoming forma-
RESUME OF LITERATURE. 119 

Lion. Gilbert refers the whole to the Juratrias. Only so far as any part of these 

strata belong to the series which farther north has been called the Wyoming formation do I believe this reference to be a correct one. The Fountain formation I have 

little doubt is Carboniferous. Of course, without fossils, opinions as to its age are 

largely matters of conjecture. 

The Fountain formation is, according to Gilbert, conformably overlain by the 

Morrison formation; but Cross has shown the existence above the Fountain of an 

important erosion interval. 

These Paleozoics, which Gilbert refers to the Harding and Millsap formations, 

form, by their outcrop, part of an area which is represented under the Lower 

Carboniferous color in the Hayden atlas. Endlich described these beds as grayish 

limestone and shale, from which it would appear that he missed the Harding beds. 

The Walsenburg quadrangle is a 30-minute quadrangle whose northwest corner 

is formed by the intersection of the thirty-eighth parallel north latitude and the one 

hundred and fifth meridian. It lies immediately south of the Pueblo-quadrangle and 

its northern border is not far south of the town of Pueblo, Colo. The geology of 

this quadrangle has been described and the formations mapped in the folio atlas of 

the same name. 

According to the Hayden atlas, this quadrangle should contain a small area of 

Carboniferous in its southwestern corner (Arkansas sandstone), but this, area proves 

to be occupied by Eocene (?) and Upper Ctetaceous rocks. 

The northwestern corner includes part of the southern end of the Wet Mountains, or of the Greenhorn Mountains, the area in which Endlich described Juratrias 

rocks as mentioned above. 

The oldest sedimentary formations recognized by Hills in this quadrangle are the 

Badito and the Morrison formations, of which the former is referred questioningly 

to the Carboniferous, and the latter to the Juratrias. Of the Badito, Hills says: 

"The upper half of this formation consists of brick-red sandstone, about 100 

feet in thickness, generally massive or thick bedded, but sometimes shaly on the 

weathered surface. It apparently corresponds to part of the Fountain formation, 

but to what portion of it is uncertain. The lower half consists of about the same 

thickness of very coarse conglomerate of a brownish-red color. * * * No organic 

remains by which the age of these beds could be satisfactorily determined have been 

found within the limits of the quadrangle. In the Sangre de Cristo Range, to the 

westward, the stratigraphic section corresponds very nearly with that at the southern 

extremity of the Greenhorn Mountains, except in respect to the thickness of the 

conglomerate. Below the Cretaceous beds and the Morrison formation there is in 

each case about the same thickness of capping red sandstone, but the coarse conglomerate and sandstone on which it rests attain in the Sangre de Cristo a thickness 

of several thousand feet. In that locality the beds have afforded remains of an 

Upper Carboniferous fauna and flora. The evidence of a similar character from the 
120 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Fountain formation on the eastern slope of the Rocky Mountains is meager and 

contradictory, and it is still a question whether it should be classed as Permian or 

Triassic." 

It would thus appear that the earlier Paleozoic is entirely unrepresented in this 

quadrangle, even the Harding and Millsap formations recognized in the Pueblo quadrangle having disappeared. A change of tint similar to that noted by Hills as 

occurring in the Badito formation has been described in many local sections of the 

red-colored beds of Colorado. The upper strata are often spoken of as brick red 

and the lower ones as being brownish red or maroon colored. Hills compares the 

lower part of his Badito formation with the Arkansas sandstone, thus suggesting a 

correlation with the Maroon formation and its equivalents in other parts of Colorado, 

while the upper, bright-red portion may represent the Lenado beds, the Wyoming 

formation in the Tenmile district, etc. Upon this hypothesis the Badito formation 

would contain the dividing line between the Wyoming and Fountain formations, and 

include about 100 feet of each series, the one above, the other below. This may be 

the case, and could be explained in its relation to the conditions existing in the Pueblo 

and Pikes Peak folios by considering the uncomformities which preceded the Fountain 

formation, the Wyoming formation( ?), and the Morrison formation. But in view 

of the great thickness of the Fountain beds in the Pueblo quadrangle immediately 

north and of the apparent absence there and in the Pikes Peak quadrangle of the 

Wyoming formation it seems as if the color change in this case were being misinterpreted and as if the Badito formation represented the Maroon and Fountain horizon. 

The Spanish Peaks quadrangle adjoins the Walsenburg quadrangle on the south. 

In its northwest corner this quadrangle should include, according to the Hayden 

atlas, an area of Carboniferous rock, probably part of Endlich's Arkansas sandstone; 

but the facts brought out in this folio show the Hayden mapping to have been 

incorrect. The oldest strata recognized in the Spanish Peaks folio is the Morrison 

formation, there being no Archean or Paleozoic in this area. 

In his report upon the San Luis district a Endlich described the geologic succession along the Front Range from a point somewhat south of Colorado Springs to 

the thirty-eighth parallel! South of Canyon an overlap of younger deposits conceals the beds of the Juratrias, which reappear, however, north of the limit above 

referred to. The northern area at least has been the subject of other reports, especially that of Cross upon the Pikes Peak quadrangle and Gilbert upon the Pueblo 

quadrangle; fortunately, since it seems impossible to make much out of Endlich's 

account. In this northern and more extensive area he gives three sections, to which, 

as usual with this author, measurements of thickness are lacking, and from these it 

would appear that he missed all of the admitted Paleozoics along this tract, though 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 275-361. 

b Pages 312 to 316 and 328 to 329 of his report. 
RESUME OF LITERATURE. 121 

some of them are delineated as Silurian upon the Hayden Atlas. He states that the 

sedimentaries maintain a rather uniform character. The oldest of these he seems to 

refer to the Triassic and Jurassic, though adopting for them the name Mesozoic, 

which he employs in exclusion of the overlying. Cretaceous formations. His Mesozoic beds, then, include the Fountain and Morrison formations recognized by Cross 

and by Gilbert, and his Cretaceous opens with what they call the Dakota formation. 

But little space is devoted to the more southern exposures of the Triassic and 

Jurassic formations, which here, at least, seem to be discriminated, though it is not 

clear at what point the division is made. " South and southeast of station 78 * * * 

the shales of a dark red to a brown color seem to increase considerably in thickness, 

* * while those beds referred to the Jurassic formation seem to decrease in 

thickness." Combined, their bulk probably exceeds 1,000 feet, though by how 

much is not told. 

Near the southern limit of the tract grayish limestones and shales of Carboniferous age identified by fossils are reported, and they are mapped in the Hayden 

Atlas as Lower Carboniferous. 'Shortly south of this occurrence the beds which we 

have been following are concealed by the Cretaceous overlap.

, This area which appears under the Lower Carboniferous color in the Hayden 

Atlas is partially included in the Pueblo quadrangle, and the beds which Endlich 

discriminated in the manner above described are identified by Gilbert as the Harding 

sandstone and Millsap limestone, though apparently Endlich saw only the latter. 

In his Southeastern district Endlich reports upon the tract along the Front 

Range, immediately south of that included in the San Luis district. He describes 

the Trias as occurring on the southern end of the Wet Mountains, and it is so 

represented on the Hayden Atlas. 

Endlich's remarks about these strata are somewhat obscure, but apparantly he 

recognizes two groups, the lower of which, consisting of bright red sandstones, 

shales, and marls, he calls the Red Beds or Triassic, and the upper consisting 

of light shales and marls, is called Jurassic. The lower strata have single beds 

of white or yellowish sandstone mingled with them, and are said to attain a considerable thickness. 

Endlich states that these beds are identical with those further north, and 

expresses surprise that in his area they have not a more general distribution. 

Part of the area which is colored Triassic in the Hayden Atlas falls within the 

Walsenburg quadrangle, and the beds grouped by Endlich under the title Juratrias 

are probably the exact equivalent of the Badito and Morrison formations of the 

Walsenburg Folio, though lithologically Endlich's beds resemble especially the 

'Morrison formation as described and delimited by Hills. 
122 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

SAN JUAN REGION. 

In 1900 appeared a careful description by Cross and Spencer of the 'geology of 

the Rico Mountains,a the same group which in the Hayden atlas is set down as the 

Bear River Mountains. The strata' described are classified as Devonian, Carboniferous, Juratrias, and Cretaceous. The Devonian is reported , as consisting. of three 

members. The lowest is a sandstone or quartzite, frequently conglomeratic in the 

lower part; the middle is a shale, and the upper a limestone, for which the name 

Ouray limestone is employed. It is said that, the -same series occurs in the Animas 

region, and apparently some points in the description are amplified from this wider 

knowledge. " In certain localities in the San Juan the quartzite was not deposited 

upon* the Algonkian, and elsewhere both the quartzite and the shale are missing, in 

which case the limestone rests directly upon the pre-Paleozoic; but whenever the 

lowest member is present it is always followed in order by the other two in conformable sequence. It is possible that the shale and quartzite are pre-Devonian." There 

are thus indications of a species of unconformity between the several portions of the 

Devonian beds. 

The quartzite is again described as massive, very dense, and highly indurated, 

in color dull yellow and white, with red and brown staining. Its thickness is given 

as about 200 feet. At the time this report was written no fossils were known from 

the quartzite, and its reference to the Devonian, as shown in the statement quoted 

above, was clearly made in a tentative manner. The character and geologic position 

of this bed are so similar to those of the Cambrian of other parts of Colorado as to 

suggest the Cambrian age of this series also. Furthermore, in some talus, with little 

doubt derived from this quartzitic formation, Mr. Cross has recently found a slab 

containing numerous specimens of a linguloid shell, probably belonging, to the genus 

()bolus (Lingulella). This evidence, though imperfect in several ways, combined with 

the other, makes the Cambrian age of the quartzite member highly probable. This 

formation Cross now proposes to call the Ignacio quartzite. 

The central shaly member of the Devonian series is not specifically described, 

but its thickness appears to be about 50 feet. If the quartzite does, as I suspect, 

represent the Sawatch quartzite, the Yule limestone, as such, has no equivalent in 

the Rico section. The relation of the shaly member to the series established for the 

Crested Butte quadrangle is of course altogether speculative, but the suggestion is 

made that it may correspond to the shale which in that section Spurr correlates with 

the Parting quartzite. This correlation is rendered somewhat the more probable 

because from this horizon Endlich 6 reports the occurrence of bones and scales of 

fishes of large size, a type of fossil that seems to characterize the Parting quartzite 

horizon. 

a U. S. Geol. Surv., Twenty-first Ann. Rept., pt. 2, 1900, pp. 7-165. 


bU. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 212. 

RESUME OF LITERATURE. 123 

The Ouray limestone is made up of massive beds of limestone, separated by thin 

intercalations of marl or shale. Fossils are to be found in most sections, and show 

the geologic age to be upper Devonian. Only the Devonian fauna was known at 

the time this report was written, but at certain localities, at least, the top strata of 

the Ouray limestone contain fossils of a distinctly Mississippian aspect. The same 

Devonian fauna occurs in the Leadville limestone at Glenwood Springs, in the vicinity 

of Salida, and in the Crested Butte quadrangle, while a similar Mississippian fauna 

is found in the upper portion of the Leadville at Salida, in the Crested Butte quadrangle, and at Aspen. It can be regarded as established, therefore, that the Ouray 

limestone is the equivalent of the Leadville limestone of the Elk Mountains. 

The Carboniferous of Cross and Spencer consists of the Hermosa and Rico 

formations, both of Upper Carboniferous age, for the Mississippian fauna of the 

Ouray limestone was not known at the time of their writing, and the Mississippian 

epoch accordingly was supposed to be unrepresented. On the evidence of the 

invertebrate faunas the Hermosa formation is referred to the Pennsylvanian period, 

and the Rico formation to the Permo-Carboniferous. 

" Occurring between the Devonian limestone and the typical Red Beds, and 

sharply defined from each, there is a heterogeneous series of rocks which is generally distributed in the San Juan region, where it reaches a maximum thickness of 

about 2,000 feet * * * Lithologically the Hermosa is composed of limestones, 

shale, and sandstone, hut all of these strata are more or less calcareous throughout. 

The limestones are of a blue-gray color, rather dense in texture, and usually very 

fossiliferous. They are frequently more or less bituminous, sometimes so much so 

as to afford a distinct odor of petroleum when struck with a hammer. The shales 

vary from black bituminous clay shales, rather fissile, to sandy shales and sandstones of an olive-green color. The sandstones are also of a greenish color * * * 

This formation has a considerable distribution in the western part of the San Juan 

region, but throughout the area of its occurrence it is not in general divisible, since 

individual beds and groups of strata change greatly in character from place to place, 

so that horizons can not be definitely recognized in localities separated from one 

another by more than short distances." 

At Rico, still more than in the Animas section, are the limestones persistently 

segregated in the middle portion of the formation. It is therefore possible to 

divide the Hermosa at Rico into three approximately equal parts. The Hermosa 

formation corresponds in a general manner with the Middle Carboniferous mapped 

by the Hayden survey. 

Between the Hermosa formation and the Ouray limestone in the Needle Mountains quadrangle occurs a bed of red shaly material whose character and occurrence 

are peculiar. It was not given particular description in the report by Cross and 

Spencer, but it is now proposed to discriminate it as the Molas formation. The 

following account of this horizon is abstracted from a description written by Mr. 

Cross: 
124 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The Molas formation is the lowest of the three Upper Carboniferous formations 

distinguished in the Animas Valley and adjacent region. It is distinguished on 

lithologic grounds, because it records a preceding interval of erosion, by which 

formations of Mississippian age were in large measure destroyed, and, in a subordinate degree, because of certain faunal peculiarities which further collections may 

or may not affect." The Molas beds were not included in the original definition of 

the Hermosa formation, although the Hermosa was said to rest on the Ouray limestone. In the localities examined before that definition was formulated there was, 

in fact, a hiatus in the observations, the thin Molas beds being nowhere well 

exposed. This formation is especially characterized by its deep-red, friable, sandy 

strata, which are variably calcareous and often shaly. They are seldom very 

distinctly bedded, and disintegrate so rapidly on weathering that good exposures 

are rare. In the lower part of the formation dark chert nodules abound, often 

making a large part, of flat lentils or discontinuous layers. The best section of 

the formation thus far observed is situated on the southwest slope of the Needle 

Mountains, on the south side of Tank Creek. At that locality there is a continuous 

section, about 75 feet in thickness, representing the whole formation as there 

developed between the Ouray limestone and the Hermosa complex. There is no 

distinct stratification in the section. At the base is a zone of gradation into the 

Ouray limestone, for the upper zone of the latter is much broken up with the red 

calcareous mud of the Molas filling the interstices. This filling of the formation is 

very common. For some feet above this transition zone there is a chaotic mixture 

of chert and limestone fragments, with not a few of bluish or white quartzite, but 

none of granite or schist. In all the lower part of the section much of the material 

is an impure limestone, reddish in color, but with the saccharoidal texture of the 

Ouray. It is probably a limestone sand rock. The matrix in which the fragments 

of chert, quartzite, and limestone are held is a red marl-like material. There are in 

places indications that a calcareous mud was broken up before consolidation, and 

was worked over with the fragments of foreign rocks. Gradually the section 

becomes more and more sandy, but chert fragments were found almost up to the 

fossiliferous limestone of the Hermosa. 

The shale contains nodules of chert carrying a Mississippian fauna related to 

that in the upper portion of the Ouray limestone, and it is believed that they were 

derived from the Ouray. Otherwise the shale is almost unfossiliferous; but from 

some thin limestones in the uppermost part of the formation, in a single locality in 

the Needle Mountains quadrangle, a few species were obtained by Mr. Cross which, 

while not of themselves altogether diagnostic, are unlike the Mississippian fauna of 

the Ouray and similar to that which comes in at the base of the Hermosa, which is 

clearly Upper Carboniferous. On this account the beds down to the top of the 

Ouray are regarded as belonging in the Upper Carboniferous. 
RESUME OF LITERATURE. 125 

The Rico formation includes the lower portion of the Red Beds in this region, 

the upper portion being described as the Dolores formation. Lithologically the 

two formations are quite similar, and their discrimination is based chiefly upon 

the evidence of fossils. The fauna of the Rico formation is of Carboniferous age, 

while that of the Dolores is Triassic. The boundary between the Rico and the 

Hermosa formations is well marked, but that between the Rico and Dolores " is at 

present entirely artificial, being based upon the highest known occurrence of the 

Rico fossils. The former is made to include only strata characterized by the Rico 

fauna, while the latter comprises the apparently unfossiliferous medial portion of the , 

Red Beds, together with the upper part, of known Triassic affinities. The actual age 

of the unfossiliferous Red Beds is thus left in doubt; they may eventually prove to 

be either Permo-Carboniferous, true Permian, or Trias. They correspond to what 

has been called Trias throughout the Rocky Mountain province." The thickness of 

the Rico formation thus determined is about 300 feet, and it is made up of " sandstone and conglomerates with intercalated shales and sandy fossiliferous limestones." 

The general characteristics of the Rico formation are again described as being, first, 

" its calcareous nature, in which it resembles the strata above and below; second, the 

very arkose character and the coarseness of the sandstones, in which respect it differs 

from the Hermosa and resembles the Dolores; and, third, its chocolate or darkmaroon color, which contrasts sharply with the gray or green of the Hermosa and 

which is more or less distinct from the bright vermilion of the Dolores." 

With the Rico formation the portion of the section falling within the scope of 

my work is exhausted, but I will briefly recapitulate the important characters of the 

Juratrias groups. "All the Juratrias formations of the San Juan region," it is 

reported, "are represented in the Rico Mountains. Beginning at the base, they are 

the Dolores Red Beds, 1,600 feet in thickness; the La Plata sandstone, 250 feet or 

more; and the McElmo shales and sandstones, exposed to a thickness of 300 feet 

within the area represented on the map, but having a total thickness of nearly 900 

feet in the region adjacent." 

The La Plata sandstones and McElmo formations are said by Cross and Spencer 

to represent, respectively, the lower and upper portions of the Gunnison formation 

of the Crested Butte region. The Ouray limestone, as already shown, can be correlated with the Leadville limestone of that area, so that the Molas, Hermosa, Rico, 

and Dolores formations in one area and the Weber and Maroon formations in the 

other occupy similar positions in the section. The Weber formatitm appears to 

have no especially discriminated lithologic equivalent in the San Juan region. 

The Hermosa formation, in thickness, lithologic character, and position, is similar to 

the lower of the two divisions recognized in the Maroon conglomerate. The Rico 

formation in its color and lithology is similar to the upper division of the Maroon, 
126 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and both are characterized by their arkose character, indicating that erosion having 

cut through the overlying sediments was playing upon the granitic basement rock. 

The Rico is, however, very much thinner, and its characteristic fauna has as yet not 

been found in the Maroon conglomerate, the fauna of the upper part of which is 

unknown. The bright-red Dolores beds appear to have no equivalent in the Crested 

Butte quadrangle, but they can be compared to the similar deposits described by 

Spurr at Lenado Canyon near Aspen. The time interval between the Rico fauna 

and that characterizing the top of the Dolores is so great that I believe that a 

period of erosion or of nondeposition must have intervened, even though it is not 

now recognizable in the mutual attitude of the sediments. With such a theory the 

great disparity in thickness between the Rico formation and the upper Maroon is 

in accord, and also the greatly reduced thickness of the upper Maroon in the 

southern part of the Crested Butte quadrangle reported by Eldridge. On the other 

hand, the Gunnison formation was preceded in the Crested Butte region by a 

recognized unconformity, and it is by pre-Gunnison erosion that the apparent absence 

of the Dolores formation in that region may be accounted for. 

The paper which furnished the foregoing brief summary was one of the last 

dealing with the geology of this area, but because it establishes for the first time 

a section and a nomenclature, its consideration has been, as a matter of convenience, 

taken up before those of earlier date. 

In the geologic reports which accompany Ruffner's report upon a reconnaissance in the Ute country a are accounts by F. Hawn and L. Hawn, of observations 

at Animas Park and Animas River in the San Juan Mountains. Most of the strata 

described along the Animas seem to belong to the Hermosa formation, and Carboniferous faunas are cited from them in a number of instances. At two localities 

in the vicinity of Engineer Mountain fossils are cited from a cherty limestone, which 

are said to be of Eocarboniferous age. The following species are reported (p. 68): 

Cyatho_phyllum, Gorgonio, Crin,oidea, Productus reticulates, and Euomphalus latus. 

As the character of the rock, the locality, and, to a certain extent, the fauna agree 

with our collections from the top of the Ouray limestone, it seems probable that 

Hawn was correct in the age determination of these beds. The red sandstone 

mentioned on page 68, and reported as 1,000 feet thick, possibly represents the Rico 

formation, unless the color is due to metamorphism as suggested by Hawn. 

Stevenson's report in the third volume of the Wheeler survey b touches briefly 

upon the geology of the San Juan region.c The only beds which come within the 

purview of this discussion are referred to the Carboniferous and the Triassic. They 

were seen chiefly in the Animas Valley. The Carboniferous, distinguished by its 

a Ruffner's Rept. Recon. in the Ute Country, Forty-third Cong., 1st sess., House Ex. Doc. No. 193, 1874. 


b U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875, pp. 307-501. 


c Ibid., p. 374 et seq. 

RESUME OF LITERATURE. 127 

characteristic fossils, comprises sandstones, limestones, and dark shales. Their 

thickness is reported as 1,200 feet, and the series is correlated with the lower sandstone measures in the Eagle River section. The Triassic beds, having a thickness of 

1,500 feet, are said to abut against the lower sandstones of the Carboniferous. 

There is nothing to indicate that the older Paleozoics recognized by Cross and 

Spencer in their Rico. Mountains section were seen by Stevenson, and his Carboniferous, therefore, is more or less completely the equivalent of the Hermosa formation. The character of the Triassic beds is not described, but it is fair to assume 

that they are of the type of the Red Beds elsewhere in Colorado. With this interpretation the Triassic would be in a general way the same as the Rico, Dolores, and 

La Plata formations of the Rico section. Stevenson's measurements are in both 

cases, it may be mentioned, somewhat less than those more recently made by Cross 

and Spencer. Stevenson's correlation of the Hermosa with the lower portion of his 

Eagle River section is of interest, and that correlation I, too, am disposed to favor. 

The area examined by Endlich in 1874, called the San Juan district,a lies between 

the one hundred and seventh and the one hundred and eighth degrees of west longitude, and between 37° 15' and 38° 15' north latitude. The Paleozoics in this area are 

largely confined to a more or less crescent-shaped outcrop on the southwest side of a 

subcircular Algonkian (?) nucleus, the northeastern half being concealed by eruptives. 

There are also a few small outlying bodies of outcrop, as that at Ouray. 

The arrangement of this report is greatly improved over that of the preceding 

year, but we find employed the same objectionable method of indicating points of 

observation by numbered stations which are not systematically described or represented upon a map. 

At only one point, the canyon of Lime Creek, did Endlich observe any beds 

which he refers to the Silurian, but in his Devonian are probably included the older 

horizons of the Paleozoic section. The Lime Creek exposures are said to consist of 

white, coarse-grained sandstones deposited in thick strata, and it was Endlich's now 

very quaint-seeming opinion that the pre-Devonian beds generally, and these sandstones in particular, furnished the material for, and by metamorphism were transformed into, the quartzites and other Algonkian(?) rocks of this area. Endlich 

implies that this sandstone underlies and is distinct from his Devonian, but it seems 

more probable that it is only a local phase of the siliceous lower portion of it (i. e., 

of the Ignacio quartzite). 

His Devonian along Lime Creek is a light-blue to grayish limestone with 

abundant fossils, the entire series having a thickness of 1,200 to 1,500 feet. "Above 

the limestones the Carboniferous beds begin, while they are underlaid probably for 

all. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, pp. 181-240. 
128 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

a considerable distance by the Silurian sandstone. This was observed, however, only 

at one point." (Page 211.) 

The section at station 48, which appears to be located on the southern boundary 

of the metamorphic area, has at its base a white to red and brown quartzite resting 

immediately upon granite. Next follows a thin stratum of yellow siliceous shale 

containing narrow interstrata of softer shale. This formation is characterized by 

the presence of well-marked pseudomorphs after salt, together with scales and 

fragments of bone of large fishes. Above this the limestones set in. " The entire 

thickness of the sedimentaries at station 48 amounts to about 200 feet, while farther 

south the limestone alone reaches that figure." The limestone, which is presumably 

the same in both sections, is evidently the bed to which Cross subsequently has given 

the name, Ouray limestone. Endlich cites a list of the species found by him in the 

Ouray limestone. I described and illustrated this fauna characterized by the fine 

species, Camarotwchia endlichi, in some detail in 1900," and although it was for a 

time set down as Carboniferous, later and more complete collections vindicate 

Meek's early determination of its age as Devonian. The Ouray limestone was 

succeeded by an interval of erosion, not of course observed by Endlich, and locally, 

at least, it contains in its upper portion another and quite distinct fauna of Mississippian age, whose presence was not known at the time I described the Devonian 

fauna. Whether the differences in thickness, to which attention is called by Endlich, 

are due to this post-Mississippian erosion, I am unable to say, but it seems probable 

that this was partially, at least, the case. If, as one would infer from Endlich's 

statements, the white limestone, called by him Silurian, underlies the so-called 

Devonian, the absence on Lime Creek between the Silurian sandstone and the Ouray 

limestone of the quartzite and siliceous shale observed at station 48, and of the Silurian sandstone at the latter between the granite and the Devonian, are equally 

inexplicable. It seems more reasonable to suppose that the white sandstone is a 

local phase of the siliceous beds at the base of the series exposed at station 48, or 

that it is a new group developed in the thicker section, probably at a higher horizon 

than the quartzite of the latter. The quartzite, both from its lithology and stratigraphic position whentcompared with other sections, and also from such scanty fossil 

evidence as it has yet furnished, is surmised to be of Cambrian age and equivalent to 

the Sawatch quartzite, while for similar reasons the siliceous shales can be compared 

with the Parting quartzite, or with that general horizon. The presence of fish 

remains in this formation rather enforces this hypothesis and brings to mind the fishbearing Parting beds at Aspen. 

Endlich divides the Carboniferous sediments into two divisions, which he calls 

the Lower Carboniferous and the Upper. As usual, these terms are to be divorced 

a U. S. Geol. Surv., Twentieth Ann. Rept., pt. 2, 1900, pp. 31-63. 
RESUME OF LITERATURE. 129 

from their ordinary paleontologic associations. While the Lower Carboniferous 

consists of sandstones, shales, and limestones, the Upper is confined almost 

exclusively to massive beds of red sandstone. "In its lower strata the former 

shows mainly yellowish sandstones, interstratified with yellowish and gray shales, 

while higher up the blue limestone sets in, containing characteristic fossils. Immediately above that the red sandstones begin, and continue in an unbroken series 

until the white sandstones of the Lower Cretaceous are reached. Trias and Jura 

are missing or reduced to a minimum, and only exposed locally." 

The "Lower Carboniferous" is reported by Endlich as entirely conformable with 

the Devonian. There is, indeed, an apparent conformity, but its earliest sediments 

were deposited upon the Ouray limestone' only after the latter had undergone a 

protracted period of erosion. Endlich gives no total or average thickness for this 

formation, but he states the thickness of exposures at several points. Near station 

49„ apparently, 1,000 feet were observed (p. 216); at station 40 but 400 feet (p. 216); 

and in the Animas Valley it, would appear to have a thickness of 1,400 to 1,800 feet, 

more or less (p. 219). Endlich found this series, which Cross has distinguished as 

the Hermosa formation, to be sparingly fossiliferous, but from it Cross and his 

associates have obtained extensive collections. Endlich cites Productus semistriatus, 

Seminula subtilita, and Spirifer sp. The species first mentioned was not found in 

the recent collections, and if its occurrence is authentic, as I doubt, it is of some 

interest, seeing that the species is a rare one. Apparently, however, the name is a 

blunder of Endlich's for the common Productus semireticulatus, for we seem to have 

his fossils among our present collections, and they belong to the type which I have 

discriminated as P. semireticulatus var. h,ermosanus. 

The red sandstone or Upper Carboniferous of Endlich succeeds the beds which 

he calls Lower Carboniferous. This, series consists principally of red sandstone, as 

already pointed out, but it seems to contain a certain amount of dark shale and to be 

sometimes strikingly interstratified with beds of white sandstone (p. 218).. At one 

point a thin limestone occurs above the sandstone (p. 217). The thicknesses seen at 

several points are 2,000 feet on the east side of the Animas, 1,400 feet at station 40, 

and 1,800 feet on sear Creek (p. 217). Fossils are reported as especially scanty, but 

Seminula subtilita is cited, and also Productus semistriatus, though the latter was 

not found in place, and some doubt seems to have been entertained as to the 

specimens really belonging to this horizon. Here also, if I judge correctly from 

the context, are reported crinoids and corals similar to those found in the red sandstone of the Sangre de Cristo Range. Indeed, that formation to which Endlich gave 

the name Arkansas sandstone he is disposed to regard as the stratigraphic equivalent 

of the Upper Carboniferous of the San Juan region (p. 240). 

From the color of Endlich's Upper Carboniferous series, and the fact that it is 

14364—No. 16-03-9 
130 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

followed by the Lower Cretaceous sandstone, and also because he in one place 

assigned to the Lower Carboniferous a thickness almost as great as that of Cross and 

Spencer's Hermosa formation, the inference might be made that his Upper Carboniferous represented their Rico, Dolores, and La Plata formations; but his faunal 

evidence seems to place this out of the question and make it necessary to consider 

that series part of the Hermosa formation, unless, what is not improbable, his 

Upper Carboniferous is represented by the Hermosa in one instance and by the 

Dolores in another. 

The red sandstone is followed by the white sandstone of the Lower Cretaceous, 

which rests unconformably upon it, and Endlich points out that it was preceded by a 

deformation of the Paleozoic formations (p. 215). He says: 

"Although the Cretaceous beds of the southern and western portion have the 

same general direction of dip as the older ones, several localities have furnished evidence that the disturbances affecting the Devonian and Carboniferous must have 

occurred before the deposition of the Cretaceous. It is possible that to this fact, to 

the higher relative position at the time, the absence of Triassic and Jurassic beds 

may be attributed" (p. 240). 

In 1875 W. H. Holmes was given charge of the geologic survey of the San Juan 

division,a and his report is found on pages 237 to 276 of the Hayden Annual Report 

for that year. The San Juan division is defined as the area which is "bounded on 

the west by 109° 30', on the south by 36° 45', on the north by 37° 50', and on the 

east by Mr. Wilson's work of 1874." Portions of this area lie in the States of Utah, 

Arizona, and New Mexico, but by far the greater part is in Colorado. 

This territory is chiefly occupied by rocks of post-Paleozoic age, and it is to 

these, consequently, that most of the discussion is devoted. Carboniferous beds 

occur, however, overlaid by the Juratrias. To the latter are assigned beds 12, 

13, 14, and 15 of the general section, with a combined thickness of 1,500 feet. 

"Group 12 consists of brownish and purplish laminated sandstones, generally less 

than 200 feet in thickness. This is the fossil-bone bed of Dr. Newberry, which is 

thought by him to be Triassic. Group 13 is the well-marked bed of massive white 

and pinkish sandstone. This is succeeded by a laminated series, and this by red 

sandstones." 

I find it difficult to correlate these subdivisions exactly with the formations 

recognized by Cross and Spencer in the Rico Mountains, though the general equivalence is obvious. It seems a safe hypothesis io suppose that the Upper Dakota of 

Holmes is the same as the Dakota sandstone of Cross and Spencer. His Lower 

Dakota;therefore, would probably be the same as their McElmo formation. With 

this, however, the resemblance seems to end. Though the two sets of formations 

agree singularly in thickness when arranged in parallel columns according to this 

all. S. Geol. Geog. Surv. Terr., Ninth Ann. Rept., for 1875, 1877, pp. 237-276. 
RESUME OF LITERATURE. 131 

scheme, their lithologic and other characters do not agree. Bed 12, which Holmes 

believes to be the same as Newberry's bone bed, invites comparison with the Dolores 

formation, which also is bone-bearing, butt the thickness is widely different. Similarly the white sandstone, which is Holmes's bed 13, resembles the La Plata sandstone, but they differ widely in thickness, and if correlated the bone bed would occur 

above the division in one case and below it in the other. Probably the Lower 

Dakota and the laminated bone bed combined are equivalent to the McElmo formation, the white and pink sandstone to the La Plata, and the red massive sandstone 

to the Dolores. 

The distribution of these beds is described by Holmes as follows: 

"The areas occupied by Juratrias and Carboniferous rocks call for nothing more 

than a mere mention, as they are quite limited in extent, incomplete in exposures, 

and totally without fossil remains. In the La Plata Mountains there are exposures 

both of Red Beds and of Carboniferous sandstones; but they are to a great extent 

metamorphosed beyond recognition. About the sources of Bear River there are also 

exposures of the rocks of these ages, but I was not able to examine them. In 

Dolores Canyon, in the McElmo at the north base of Ute Peak, in the Montezuma 

Canyon, and on the Lower San Juan, there are slight exposures of the purple 

laminated beds and of the pink and red sandstones. On three sides of the Carriso 

Mountains there are outcrops of the Red Beds, but these are mostly beyond our district. From the summits of the Carriso Mountains I obtained a comprehensive view 

of the tract of country about the valleys of Gothic Creek and the Rio de Chelly; 

nothing but red and white sandstones appear. A white or slightly pinkish sandstone 

is in this section peculiar to the upper part of the heavy sandstones of the Juratrias." 

Under the title of "The geology and vein structure of southwestern Colorado," 

Comstock treats of an extensive area which includes the San Juan region.a The 

sandstones cropping out near the Animas Canyon this author refers to the Upper 

Silurian, and the Ouray limestone he makes Devonian. The Carboniferous is divided 

by him into an Eo- and a later Carboniferous series. The former, consisting of argillace-ous, calcareous, and arenaceous beds with a thickness of 1,200 feet, is probably 

the exact equivalent of Cross's Hermosa formation. He remarks (page 227): " On 

Hayden's map they are marked Middle Carboniferous; but I can not find any good 

reason for this, and I suspect that we have here the representatives of both the 

Lower Carboniferous and Middle Carboniferous of other portions of the Rocky 

Mountains." In this, of course, he is undoubtedly in error, as the Ouray limestone 

represents the Lower Carboniferous, as the term is used and the beds generally 

identified, by the Hayden survey. Productus Semistriatus, Ath,yris 8ubtilita, and 

Spirifer sp. are cited from this bed, the fauna apparently being , borrowed from 

Endlich's account in the Hayden annual reports.b Under the term -Later Carboniferous, he includes some 2,000 feet of red sandstone which probably is about 

a Am. Inst. Min. Engrs., Trans., vol. 15, 1887, pp. 218-265. 


b U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 216. 

132 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 


equivalent to the Rico and Dolores.formations of Cross and Spencer. Possibly part 

of their Hermosa formation is also included. 

DOLORES RIVER REGION. 

The district assigned to Peale for the year 1875 a was designated as the Grand 

River district. It lies between the parallels of latitude 37° 52' and 39° 15'. On the 

west it is limited by the meridian 109° 30', and on the east by the western limit of 

the work of 1874,. which is approximately the Gunnison and Uncompahgre rivers. 

In addition to this, there is a narrow strip of country south of the Gunnison River, 

from 10 to 20 miles in width, extending from meridian 107° to 107° 30'. 

It was found that over a great part of this area the Red Beds (Triassic) rest 

immediately upon the Archean rocks. "In the extreme western limits of the district 

it is probable that older formations lie between," but "there are no exposures of 

rocks older than the upper part of the Lower Carboniferous. * * * Along the 

western edge of the Uncompahgre plateau we have Permo-Carboniferous, and west 

of the Dolores two places where beds of Upper Carboniferous age appear." In fact, 

the Hayden atlas shows that the Dolores and some of its tributaries are bordered 

with "Upper Carboniferous" rocks almost from the thirty-eighth parallel to the 

junction of the main stream with, the Colorado, and that they accompany the Colorado 

from that point westward beyond the one hundred and ninth meridian. In Sinbads 

Valley rocks of "Middle Carboniferous" age are shown. 

Peale's section made at the head of Salt Creek, which is about synonymous with 

saying in Sinbads Valley, is as follows (pp. 82 and 71): 

Section at head of Salt Creek. 

[TRIAssic.] 

Feet. 

1. Light-red sandstones, massive} 

2. Dark-red shales 600 

3. Massive blood-red sandstones 700 

4. Brown sandstones with interlaminated red shales 300 

1, 600 

[CARBONIFEROUS.] 

1. Pink and red shales with conglomeritic sandstones becoming light-colored near the base 

and containing gypsum 700 

2. Yellowish and black shales and sandstone with gypsum and salt. The creek, in passing the 

bluff where these beds are exposed, acquires a strong alkaline taste 300 

3. Space filled with shaly sandstones and, perhaps, bands of limestone. Beds for most part 

entirely concealed 3, 500 

4. Light yellowish and greenish shaly sandstones 300 5. Blue limestone with Productus, crinoids, and corals} 

Total 4, 800 

a U. S. Geol. Geog. Bury. Terr., Ninth Ann. Rept., for 1875, 1877, pp. 31-101. 
RESUME OF LITERATURE. 133 

The section as here given is compiled from two parts of what appears to be a 

single continuous series divided into its Carboniferous and Triassic portions, and 

separately described on pages 71 and 82 of Peale's report. For comparison with 

sections similarly arranged of other areas examined by him, Peale has condensed 

the Carboniferous portion of this section and grouped its beds in the following 

form, which appears on page 77 of the same report: 

General section in region of Dolores River—district of 1875. 

PERMIAN. 

Feet. 

Pink conglomeritic sandstones and red gypsiferous shales 1, 000 

COAL MEASURES. 

Shales mostly arenaceous with calcareous and gypsiferous beds at the top. The beds 

are generally concealed; debris is light-yellow color 3, 500 

No fossils. SUBCARBONIFEROUS. 

Limestone, only upper part showing fossils, indistinct and not determined. Productus, 

corals, and crinoidal stems 300 

Total 4, 800-5, 000 

The correspondence of this section with that previously quoted is obvious and 

requires little comment save in the case of the Permian. In the original section the 

shales at the base of this division are described as yellowish and black, while in the 

later form their color is said to be red. 

It is to be noted that the stratigraphic base of the section here is not given, 

and presumably was not observed. Peale is inclined to believe that the lowest bed 

is near the line separating the Mississippian from the Pennsylvanian. It may be 

provisionally regarded as representing the horizon of the Ouray and Leadville limestones. Beds 3 and 4 are referred by Peale to the Upper Carboniferous or Pennsylvanian, while 1 and 2 he calls Permian or Permo-Carboniferous. " Eastward the 

beds rapidly thin out and Nos. 2, 3, 4, and 5 disappear. No. 1 on West Creek rests 

on the granite and is made up of coarse conglomerates, especially at the base, showing the near proximity of land during their formation." "Along the Dolores River 

the pink conglomerates [upper Permian ?] and sandstones appear beneath the blood 

red shales and sandstones that lie immediately below the massive red sandstones that 

cap the bluffs." These remarks describe the section quoted above, but appear to be 

less applicable to the Triassic exposures elsewhere. 

"The general character of the Triassic beds is as follows: A massive yellow, 

white, or pink sandstone forms the top of the series. Toward the western part of 

our district this sandstone is calcareous. In many places the sandstones are markedly cross-stratified. The color is subject to much change locally, passing from 

white, through orange and pink, into deep red. Below the massive sandstone are 
134 CARBONIFEROUS FORMATIONS .AND FAUNAS OF COLORADO. 

blood-red shales, followed in most cases by massive brick-red sandstone. In Unaweep Canyon the sandstones are laminated, while northward and westward. they 

seem to be consolidated into one massive bed. They are followed, as we descend 

in the series, by shales and blood-red sandstones, which, on the Dolores, change 

gradually into gypsiferous shales and sandstones." (P. 80.) 

The beds last mentioned are probably those which form the upper division of 

the Permian of his Salt Creek section. This description can not be strictly fitted to 

the section of the Triassic series observed in Sinbads Valley, and other sections show 

similar deviations in detail. The Jurassic consists of variegated shales and marls, 

with thin bands of limestone near the base. 

This series can most appropriately be compared with those of the San Juan 

district and of the Crested Butte quadrangle. The lowest bed seen can probably be 

correlated with that widespread calcareous horizon, the Leadville or Ouray limestone. 

The shaly sandstone above, of which Peale cites a thickness of more than 3,600 

feet, seems to correspond to the Hermosa formation of the San Juan region. The 

Red Beds are the probable equivalents of the Dolores and La Plata formations, while 

the Jurassic is almost certainly the McElmo formation. 

The correlation of the Hermosa formation with Peale's Carboniferous beds has 

much to recommend it, yet the latter have a thickness of over 3,500 feet, while the 

Hermosa contains but 1,800 feet. However, the faunal break between the Hermosa 

formation and the Rico is sufficiently important to suggest an unrepresented time 

interval between those formations, to which the upper beds in Sinbads Valley may 

correspond. The only fossils we have from Sinbads Valley come from near the top 

of the supposed Hermosa. The fauna is quite distinct from the Rico fauna, and 

yet presents a different facies from the Hermosan fauna. So far the paleontologic 

evidence is favorable to this correlation and to the explanation suggested for the 

difficulties which arise from it. 

Lithologically the 300 feet of yellowish and black shale which Peale includes with 

the Permian is unlike the Red Beds above and more similar to the Hermosa formation, 

with which it seems to me more appropriate to unite it. This course is also justified 

by the overlap of the Red Beds portion of the "Permian" upon the granite, as 

reported by Peale. The Rico fauna has not yet been found in the Sinbads Valley 

section, but it may occur there, as so little is known of the paleontology of that area. 

If the Rico does occur, however, it must have undergone a lithologic change, as there 

are no chocolate or dark maroon measures at the base of the Red Beds. The possible correlation of the Rico formation with the upper member of the Maroon has 

already been suggested, and the total absence of the series in Sinbads Valley would 

be quite in line with its great reduction in the San Juan region. Assuming that the 

Rico is absent in this area, that the base of the Red Beds begins with the upper half 

of Peale's Permian, and that the top ends with the base of his Jurassic, the interme-
RESUME OF LITERATURE. 135 

diate beds would necessarily be the equivalent of the Dolores and La Plata formations combined. The massive, brick-red sandstone at the base of Peale's Triassic 

strongly suggests the Dolores formation, while the massive, light-colored upper 

portion is like the La Plata, but there is here an intermediate series, while below the 

beds similar to the Dolores 700 feet of Red Beds are found, which Peale places in the 

Permian. The total thickness of the Red Beds in the La Sal Mountain region, with 

the limits taken as above, is 2,300 feet. The Dolores and La Plata formations have 

a combined thickness of only 1,850 feet. The statement made by Cross and Spencer 

that the Dolores formation, which i's almost 2,000 feet thick in the Animas region, 

is reduced to scarcely half that amount in the vicinity of the La Sal Mountains,a is 

in a measure offset by this fact, that the La Plata sandstone, which varies from 100 

to 500 feet in the San Juan region, expands to the northwest, and in the Canyon and 

Plateau regions, to two or three times the maximum figure for the San Juan (loc. cit., 

p. 74). Furthermore, though the McElmo formation contains 300 feet in the Rico 

Mountains, and though Peale assigns to his Jurassic a thickness of 250 feet, yet 900 

feet are said to be found in the region adjacent to the Rico section (loc. cit., p. 66), 

so that some of the upper beds of Peale's Triassic may go with his Jurassic to form 

the McElmo formation. 

Peale relates that upon West Creek bed 1 (the upper division of his Permian 

series) rests upon the granite, and that over large areas his Triassic beds occupy a 

similar position. The interpretation of these fasts which is to me the most probable 

is that they record two distinct episodes of submergence, if, indeed, it be granted 

that Peale has successfully performed the difficult task of correlating or tracing the 

variable members of his Red Beds sections. It may prove, however, that the conglomeratic beds on West Creek which he considers represent the upper member of 

his Permian are really identical with those producing the Triassic overlap; that there 

was a single submergence; and that parts of the section have been duplicated. In 

any event there appears to be a sort of unconformity between Peale's Permian, or at 

least the upper and larger portion of it, and the beds supposed to represent the 

Hermosa formation. As previously mentioned, there is evidence of this also in the 

fact that the Hermosa 'in Peale's area is so much thicker than farther east, and that 

the upper portion carries a somewhat different fauna. These speculations, however, 

are subject to such varying possibilities that in the absence of accurate stratigraphic 

tracing or the means for paleontologic correlation they seem almost futile. 

Comparing next Peale's section with that exposed in the Crested Butte quadrangle, it appears that if the loWest limestone of the former is really of Mississippian 

age, it is the equivalent of the Leadville limestone. The shale sandstone above the 

limestone would then represent the Weber combined with the lower member of the 

a U. S. Geol. Surv., Twenty-first Ann. Rept., pt. 2, 1900, p. 67, 
136 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Maroon formation, while the upper heavy sandstone of the Triassic, together with 

the overlying Jurassic, would represent the Gunnison formation. Peale's Permian 

and the lower part of his Triassic apparently have no equivalents in the Crested 

Butte quadrangle, where there is an important unconformity between the Maroon 

and Gunnison formations; hut they probably do find expression in the Red Beds 

which overlie the Maroon at Aspen and other points farther north. The upper 

division of the Maroon has no lithologic equivalent in the Dolores River region. 

Peale's district for the season of 1876 a was again called the Grand River 

district, and the extent and character of the geologic section seems to be similar to 

that described in the report for 1875. 

On the south side of Grand River there are a few isolated exposures of granitic 

rock, but neither Silurian nor Devonian was recognized. Upper Carboniferous 

beds were found in Paradox Valley and in the canyon of the Dolores, but "both 

the localities noted on the map were seen from a distance, and therefore no details 

respecting them can be presented. They are probably similar to the rocks of the 

same age showing farther north and west, which were described in the report 

for 1875 (p. 71). * * * The line separating them from the Trias has been 

arbitrarily fixed, as the soft sandstones and gypsiferous shales are much like the 

beds forming the base of the Trias." Another but unimportant outcrop is said to 

occur on the Grand River below the mouth of the Dolores. 

Speaking of the Juratrias, he says: " The line separating the Triassic from the 

Jurassic is almost as obscure as that separating the Carboniferous from the Triassic. 

The line has been drawn lithologically, the massive red sandstone being considered 

the top of the Triassic." Of the latter, he remarks: "A massive red sandstone, 

becoming lighter colored toward the top, cross stratified at many places, is the prevailing characteristic rock. Its thickness is from 500 to 1,000 feet. The beds become 

laminated below, and gypsiferous, passing gradually into the Upper Carboniferous." 

The Jurassic is said to consist of "soft greenish and gray argillaceous and arenaceouF 

shales and marls near the top, passing into the Lower Dakota sandstone, and dull, 

reddish, laminated sandstones and shales at the base." 

Along Grand River the lithologic line separating the Trias and Jura is better 

defined. " The sandstones forming the upper part of the Red Beds are very massive, and the shaly beds just above contain thin beds of limestone. Below the 

massive sandstones come blood-red shales, followed by massive sandstones, generally of a deep-red color, although in many places the color fades to almost white. 

The thickness exposed is nearly 500 feet, which represents only a portion of the 

formation." 

The correlation of the beds thus briefly described would apparently be the same 

a U. S. Geol. Geog. Surv. Terr., Tenth Ann. Rept., for 1876, 1878, pp. 161-185. Ibid., p. 178. 
RESUME OF LITERATURE. / 137 

as that suggested for the similar section described in the report for 1875, and it is 

similarly uncertain. The Lower Dakota of Peale's report may be safely correlated 

with the Dakota of Cross's and Spencer's Rico Mountains section, and his Jurassic 

is, in a general way, equivalent to their McElmo formation. Peale gives a generalized section of his Jurassic beds, to which a thickness of 200 feet is assigned. 

At the base is a white sandstone, which may represent the whole or only a part of 

the La Plata sandstone. In either case Peale's Jurassic is considerably inferior in 

thickness to the McElmo formation. 

By analogy with his Carboniferous series of the year previous, part of that for 

1876 would represent the Hermosa formation and part would belong in the Red 

Beds. Indeed, in the passage quoted above, he calls attention to the similarity of 

the soft sandstones and gypsiferous shales forming the top of his Carboniferous to 

the beds forming the base of the Trias. Probably 700 feet of his Salt Creek section 

(which in 1875 he called Permian) should go with the Trias (?). The upper portion 

of his Carboniferous series, therefore, together with his Triassic, and possibly the 

white sandstone at the base of the Jurassic, probably represent the Dolores and 

La Plata formations. As the Triassic is said to measure 500 to 1,000 feet, possibly a 

maximum of about 1,700 feet would represent Peale's measurements, and this is not 

far from the combined thickness of the Dolores and La Plata given by Cross and 

Spencer, though all these formations appear to vary greatly from point to point. 

Peale's measurements made the year previous are considerably larger. He had 

then 250 feet of Jurassic and in the Salt Creek section 1,600 feet of Triassic. 

In 1901 Elmer S. Riggs described the Dinosaur beds of the Grand River Valley 

of Colorado.a The section treated by this author consists of so-called Mesozoic strata 

of this region, which is the vicinity of the Dolores, Grand, and Uncompahgre rivers. 

The lowest of these beds rest upon granitic rock and are referred to the Trias. The 

Trias is represented by a massive ledge of reddish sandstone, slightly cross bedded, 

and weathered in peculiar pinnacle and dome-like shapes. Below this is a softer 

stratum of vermilion-colored sandy shale, the entire thickness being about 400 feet. 

These are followed above by Jurassic strata, which range from 600 to 700 feet in 

thickness and admit of four subdivisions. The lower or marine Jura is from 100 to 

120 feet in thickness, and consists of bluish and grayish gypsum-bearing clays in 

which thin layers of fine-grained sandstone and nodular ledges of limestone are interspersed. The latter are never more than 6 or 8 inches in thickness, and are usually 

from 3 to 5 in number. In no instance were fossils found in these measures. Above 

this lower member lies a stratum of greenish shale about 100 feet in thickness, and 

then a darker zone 40 or 50 feet thick, containing frequent ledges of cross-bedded 

sandsto'ne, and at the top a series of variegated clays reaching a thickness of 300 or 

a Field Columbian Museum, Publication 60, Geologic series, vol. 1, No. 9, 1901, pp. 267-274. 
138 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

more feet. The Jurassic strata have no bearing upon the present discussion, though 

possibly the Triassic ones, which may be partially equivalent to the Wyoming sandstone, are germane to it. It is to be noted in this connection that Riggs conceives 

the granitic rock beneath the Triassic to be of intrusive origin (see pl. 39), but this 

formation has been regarded by the Hayden survey, and usually, I believe, as 

Archean. 

It seems that the Jurassic beds of this paper, which have a thickness of 500 feet, 

are the same as the McElmo formation of the Telluride quadrangle, and they here 

have about the thickness as well as, the character of that formation as it appears in 

the Rico region. It is also the Jurassic of Peale, though considerably thicker, and it 

does not contain the basal white sandstone which Peale in his report for 1876 includes 

in the Jurassic. 

The Triassic is comparable in character and thickness to the beds discriminated 

by Peale under the same name in 1876. His Triassic of 1875 was much thicker. The 

character of Riggs's Triassic is similar to that of the Dolores formation, but it is 

thinner. It is difficult to understand the absence of the La Plata in Riggs's section. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 

It is proposed in the following pages to give a brief summary of the historical 

geology of the Paleozoic strata of Colorado. My discussion will be limited geologically to data furnished by the literature, and paleontologically to the literature and 

to the Carboniferous faunas which have come into my hands. Perhaps a consideration of the Carboniferous strata is all that is strictly appropriate, but the distribution of the older Paleozoics is not without a bearing upon the mutual relations of 

land and water during Carboniferous time, and this in turn is prime in importance in 

the matter of the relations of the Carboniferous sediments and faunas. 

The presence of Paleozoic sediments is demonstrated over extensive areas in 

Colorado. They are concealed over large areas by later deposits, and in places their 

absence is an established fact; but I believe that originally they may have existed 

almost continuously over the State. Even if preserved from post-Paleozoic erosion, 

however, it seems improbable that the different groups would have had the same 

distribution, owing to erosion and disturbances within Paleozoic time itself. 

The only Paleozoic strata at present known in Colorado are those of the Cambrian, Ordovician, Devonian, Mississippian, and Pennsylvanian eras, which are represented in an imperfect and fragmentary manner. This condition is doubtless in 

part due to original deposition, but is, I believe, in larger measure than generally 

admitted, the effect of periods of Paleozoic erosion. The Cambrian, Ordovician, 

Devonian, and Mississippian beds are reduced to comparatively insignificant thickness, and though these strata underlie broad areas, their outcrop is chiefly linear, 

following that of the present Archean and Algonkian masses. In some cases Carboniferous or later deposits are brought by overlap into direct contact with the Archean. 

Some of the areas where early Paleozoic sediments might be expected, but are 

apparently lacking, are very extensive. Much of the work done in Colorado so far 

has been of a reconnaissance character, greatly deficient in detailed measured sections, careful tracing of beds, and the accumulation of paleontologic evidence. Thus 

it seems probable that thin measures of Cambrian or other Paleozoic sediments may 

have been overlooked, but in some cases they are obviously lacking. 

It is generally true that where one of these earlier Paleozoic groups is found the 

others also are present, but while this holds good in a general way, important exceptions occur. 

139 
140 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The Upper Carboniferous formations, however, are much more important in the 

matter of thickness; their outcrop covers extensive areas, and their distribution conforms only partially to that of the earlier Paleozoics. The largest body of Paleozoic 

outcrop in Colorado is that in the central portion of the State, and as the Paleozoic 

section is rather surprisingly uniform over this area the most advantageous manner 

of approaching the subject will be to consider the sediments and faunas of this region 

first, and to compare with them those of surrounding districts. 

CAMBRIAN. 

The Cambrian of central Colorado has been named the Sawatch quartzite. In 

the Crested Butte quadrangle this formation, which is extremely variable in thickness, 

permits of being divided into two portions. The lower division, which is from 50 to 

200 feet thick, is a white quartzite, and has a persistent conglomerate of pure white 

quartz at the base. The upper division, with a maximum thickness of 150 feet, is a 

red, ferruginous, and somewhat calcareous sandstone. In it a few fossils of the 

Potsdam type have been found. This division is in places entirely wanting, a; at the 

head of Taylor Creek. 

The Cambrian about Aspen bears the same name and is essentially identical in 

its physical characters with that of the Crested Butte quadrangle. It is thicker to 

the south, where it measures 350 or 400 feet, but gradually diminishes northward, 

where it is 200 feet or less. Spurr does not recognize two divisions, as does Eldridge, 

but describes it as consisting at the base of a thin bed of conglomerate, which soon 

passes upward into fine white quartzite. The upper third is not so compact and pure 

as the rest, and consists of dolomitic quartzite, glauconitic grit, and sandy dolomite. 

The glauconitic grit has a peculiar reddish color, and others of the upper beds are 

stained with iron. 

In his Eagle River section Peale described 604 feet of siliceous rocks which I 

think must represent the Sawatch quartzite. At the base is 400 feet of white quartzite which he identifies as Primordial, the remainder of the section being referred to 

the Calciferous. This consists of 10 feet of glauconitic sandstone at the base, with 

quartzite and sandstone above. Both Eldridge and Spurr have described the Sawatch 

as being glauconitic, and Spurr regards this as a characteristic feature. Peale does 

not mention the reddish sandstones to which Eldridge and Spurr make reference, 

but if the glauconitic sandstone of his section can approximately be correlated with 

the similar bed in the Sawatch quartzite at Aspen, the horizon appears to be represented, even if that lithologic ch'aracter is lost. 

At Red Cliff, according to Tilden, the entire sedimentary series below the 

Leadville limestone has a thickness of only 250 feet, and consists throughout of 

quartzite and sandstone. A few feet at the top of this series are referred to the 
RECAPITULATION OF PALEOZOIC FORMATIONS. 141 

Silurian, and are, I understand, supposed to represent the Parting quartzite. A 

simpler interpretation would be to refer the entire quartzitic series to the Cambrian, 

and to suppose the Yule and Parting formations to be absent, owing, possibly, to the 

unconformity noticed at Leadville between the Leadville limestone and the Parting 

quartzite. The Cambrian at Red Cliff would then be somewhat intermediate in 

thickness as well as in position between the Eagle River section, where it is at least 

400 feet, and that of the Tenmile district, where it is from 160 to 200 feet. 

In the Tenmile district and the area adjacent the Cambrian, which here also is 

called the Sawatch quartzite, has a thickness of from 160 to 200 feet. It consists of 

the typical white quartzite, with a conglomerate at its base, but seems to lack the red 

sandstone which distinguishes its upper portion at some points. However, it is said 

to pass upward into reddish and greenish argillaceous and calcareous shales, in which 

have been found •fossils belonging to the Dikellocephalus fauna of the Upper 

Cambrian. 

Of the Grand River area north of the Eagle and the Grand we have little or no 

precise knowledge. The indications are, however, that the Sawatch quartzite with 

all its distinguishing characters will be generally found there wherever the proper 

horizon is brought to view. Although, aside from the sections mentioned above, our 

information is of a reconnaissance character, in view of the frequent mention by 

geologists of beds of quartzite of the character of the Sawatch and at the right 

horizon, the wide distribution of this formation in central Colorado is certain. 

The Sawatch quartzite at Leadville, called in the Leadville monograph the Lower 

quartzite, has an average thickness of about 150 to 200 feet. The lower 100 feet are 

composed of finely and thinly bedded white saccharoidal quartzite, with a finegrained conglomerate at its base. The upper 50 feet are shaly in character and more 

or less argillaceous and calcareous, and transitional to the Silurian limestone, above. 

On the east side of the Mosquito Range, however, the thickness is in some cases 

diminished to 40 feet. The upper division, which weathers brown or rusty, is 

extremely variable. On the east flank of. Quandary Peak a species of Dikellocephalus 

near D. minnesotensis was found at an horizon apparently above the main body of 

quartzite and near the base of the transitional series. 

We may infer from Stevenson's account that the Sawatch, as part of his 

Silurian group, is more or less continuously exposed from the Leadville district, 

where it was first distinguished, to the southern limit of the South Park region. 

His section, made at Arkansas Canyon, represents it as a grayish-blue fine-grained 

quartzite resting on hornblendic gneiss and overlain by limestones whose faunas 

show them to be post-Cambrian in age. The thickness is not given, and the red, 

sandy member, which elsewhere appears in the upper portion, seems to be missing. 

Endlich's observations upon this area are confined to the southern portion, and 
142 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

are, I fear, not to be wholly relied on. In one case he describes at a certain "station 

56" yellow and brown quartzites resting upon porphyritic granite and followed by 

white and pink quartzite, then by shales and yellow quartzite, and finally by blue 

limestone and gray shales, which are probably Carboniferous. The other section, 

made at station 53, shows a different. series. Resting on granite is a heavy quartzitic 

limestone, which can hardly be older than the Ordovician, and this is followed by 

thin shales, gray limestone, white, yellow, and pink quartzite and red sandstone, 

yellow and brown sandy shale, gray limestone, gray shale, sandy shale, dark blue 

limestone, and brown sandstone. ' The gray limestone near the "top of the section 

appears to belong to the Lower Carboniferous. 

The section first mentioned can probably be best interpreted by taking the 

porphyritic granite as an intrusive, and considering the basal quartzite as the Parting 

formation and equivalent to the very similar quartzite of the other section made at 

station 53. Unless the granite of the latter is also an intrusive it would appear that 

through nondeposition or ancient erosion the Sawatch is wanting in places even in 

the South Park region, so that the Yule rests directly upon the Archean. 

Endlich found the "Silurian," under which title the Sawatch quartzite is elsewhere included, in small quantities south of the Arkansas, and the Hayden Atlas 

shows the Silurian color in the northern end of the Sangresle Cristo region bordering 

the river. In section c of the San Luis district Endlich describes the Silurian as 

consisting of light-colored quartzites of yellowish, bluish, and reddish tints, conformably stratified with the superincumbent gray to bluish limestone with siliceous 

segregations (p. 338). These beds certainly suggest the Sawatch quartzite and 

Yule limestone of standard sections, and Endlich states that lithologically they are 

identical with the Silurian north of the Arkansas. As described by Endlich, the 

lithologic resemblance is in some cases striking, but an unexplained contradiction 

seems to exist in stratigraphic position. In Endlich's Fossil Ridge section (Elk 

Mountain region) only the limestone is cited, the quartzite, if present, probably 

lying unexposed beneath it. In the series described as occurring at station 53, north 

of the Arkansas, both quartzite and limestone are found, but with their relative 

position the reverse of that recorded in section c, for the quartzite there rests upon, 

not under, the limestone. In the section at station 56, also north of the Arkansas, 

only the quartzite is found, resting upon a porphyritic rock which probably can 

be best interpreted as an intrusive concealing the limestone which, as at station 53, 

near by, lies beneath the quartzite. From its reported position in the two sections 

north of the Arkansas, the quartzite must be regarded as the Parting formation, 

while in that cited from section c it must be the Sawatch. It seems, therefore, 

either that Endlich's correlation of the beds is faulty, or, what is not improbable, 

that his observations as to the position of the quartzite is in error in one case or the 

other. 
RECAPITULATION OF P.A:BEOZOIC FORMATIONS. 143 

South of the Arkansas border—that is, over almost the whole of the Sangre de 

Cristo region—the Sawatch, together with the other early Paleozoics, is lacking, perhaps through nondeposition, but more probably, I believe, through erosion prior to 

the deposition of the Arkansas sandstone Which rests for the most part upon the 

granitic foundations of the range. However, on the west side of the ,Sangre de 

Cristo Range, in the vicinity of Culebra Peak, in an area mapped by Endlich as 

Arkansas sandstone, the Van Diests have recorded the occurrence of beds which 

probably represent both the Sawatch- quartzite and the Yule limestone. 

The identification in this case, though based only upon lithologic character and 

geologic position, is fairly conclusive, and this isolated occurrence makes it not 

improbable that similar disconnected areas of older Paleozoics may be discovered in 

this and other regions where they now seem to be wanting. 

In the Uinta Mountain region the section is so different from that of central 

Colorado that a comparison of the lithologic sequence without further means of 

paleontologic correlation is hazardous. The great forniation which Powell designates the Red Creek quartzite must belong to the series now called Algonkian. This 

is immediately overlain by the Uinta sandstone. If the recognition of this formation by geologists of the King survey as the equivalent of the Weber quartzite of 

the Wasatch Mountains be correct, since the latter is of Pennsylvanian age, the Cambrian would appear to be absent in the Uinta Mountains. Yet, as the Uinta sandstone is so much thicker than the Weber formation, it is possible that its base may 

comprise an undifferentiated series belonging to the Sawatch quartzite, and even that 

other pre-Carboniferous horizons may be represented there by siliceous equivalents. 

On the whole-, however, it seems to me probable that the Uinta sandstone comprises 

Carboniferous strata above, with probably a considerable thicknesss of Cambrian 

beds in its lower part. Unfortunately, about the exposures north of Eagle River, 

whose conduct might afford a clue to their relation with the Uinta section, very little 

is known. 

Along the Front Range the Paleozoic are largely concealed by the Red Beds, 

though I have no doubt that they are present somewhere to the east, under the 

plains. The Cambriari outcrops but scantily along the Front Range, and it is no 

longer the white quartzite which formed such a distinctive feature of the Sawatch, 

but is composed largely of reddish sandstones, resembling rather the upper beds of 

the Sawatch and the Cambrian of the Black Hills. In the Pikes Peak quadrangle 

Cross describes it as follows: 

"No Cambrian formation is represented upon the map, although it is probable 

that a small thickness of quartzite and of cherty limestone below the Manitou Silurian limestone belongs to that period. In Manitou Park and near Manitou Springs 

brachiopod shells, Lingulepis and Obolella, have been found in quartzites beneath 
144 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the Manitou limestone, and the cherty limestone at the base of the series in Garden 

Park has yielded a trilobite Ptychopctria." 

Peale, in his report for 1873,a gives a number of sections near Trout Creek and 

in Manitou Park, or, as he calls it, Bergen Park. In the section across Trout 

Creek, just below the canyon (sections No. 4 and 5 on page 208), the series consists 

of (1) granite, (2) yellow sandstone, (3) pinkish sandstone, (4) dark, purplish-brown 

sandstone, (5) green sandstone, and (6) blood-red calcareous sandstone. Of these there 

are about 100 feet. From the upper bed Lhigule_pis and Obolus are cited. Above 

the fossiliferous horizon occur pink limestones (7) with an extensive Ordovician 

fauna. Peale refers 6 and 7 to the Quebec group, and the sandstones below to the 

Potsdam. The two genera cited from 6, however, are, if correctly identified, clearly 

indicative of Cambrian, while the fauna of 7, though not without contradictions, 

probably indicates Ordovician. On a small stream flowing into Trout Creek (section 

p. 207) he gives 40 feet of yellow, brown-purplish, and green sandstone resting 

on a granite, which, with little doubt, represents the Cambrian of the preceding 

section, and these are succeeded by 130 feet of Manitou ? limestone. Another small 

tributary of Trout Creek gives the following section: (1) Granite, (2) white and 

yellowish sandstone, (3) pink sandstone, (4) dark, purplish-brown sandstone, (5) 

green sandstone, (6) brick-red shaly limestone, (7) pale-pink and gray limestone, 

(8) pink limestone (sec. 7, p. 209). The sequence here is the same as in sections 4 

and 5 preceding, and as the limestones are said to contain the same fossils it will be 

necessary to draw the Cambro-Silurian line at the top of bed 6, giving the Cambrian 

a thickness of 86 feet. 

Passing now to the very margin of the Front Range, the early Paleozoics are 

represented by the Hay den atlas as absent over all the northern portion from the 

Wyoming line southward to Manitou Park. King, however, held the view that into 

an unfossiliferous series of red limestones and reddish sandstones only 150 feet 

thick, occurring below a thickness of Red Beds measures in which Upper Carboniferous fossils are found, the whole of earlier Paleozoic time is condensed. This 

series, which he correlates with the "Potsdam" of the Black Hills, he includes 

under the Carboniferous color in two bands which extend along both flanks of the 

Colorado Range, and on its eastern side reach a short distance into the State. of 

Colorado, where a similar area is represented (as Carboniferous) on the Hayden 

maps. While it is possible that the series thus differentiated by King is of Cambrian 

age, the evidence so far adduced is very slight. It nevertheless resembles lithologically those beds farther south along the range whose fossils seem to demonstrate 

their Cambrian age, as well as the Cambrian of the Black Hills. 

Although not represented upon the Hayden maps, Cambrian beds probably occur 

a U. S. Geol. Geog. Snrv. Terr., [Seventh] Ann. Rept., for 1873, 1874, pp. 193-273. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 145 

in Pleasant or Perry Park, the series to which I refer being apparently included by 

Hayden in the Carboniferous. 

We have two sections of the Perry Park beds, one by Peale and the other by 

Lee. These have been discussed and a certain lack of agreement pointed out. 

Peale's series is as follows: 

Section at Perry Park. Feet. 

8. Fossiliferous limestone with chert pebbles 6 

7. Irregular limestone, with pebbles of chert and limestone 3 

6. Red calcareous sandstone 3 

5. Compact red sandstone 15 

4. Dark-purplish cherty limestone 3 

3. Red calcareous sandstone 4 

2. Very coarse white sandstone 80 

1. Granite. 

This first is of Carboniferous age, the equivalent of Cross's Millsap limestone. 

It seems to me probable that the lower beds of this section, possibly even from 2 to 

6, inclusive, may be Cambrian. 

Lee found some quartzites overlaid by cherty limestones, not m Perry Park 

itself, but some distance to the south. The quartzite he believes to be of Cambrian 

age, and the same as the Cambrian quartzite of the Pikes Peak quadrangle. The 40 

feet of coarse-grained crumbling sandstone at the base of his Carboniferous section 

in the park is evidently the same as the basal sandstones of Peale's section, which 

seem by analogy with other sections to be Cambrian. 

In the vicinity of Colorado Springs, Peale gives a section, which is No. 3 on page 

201 of the same report. The series here is as follows: 

Section near Colorado Springs. Feet. 

5. Brick-red sandstone, with green layers 20 

4. Coarse gray sandstone 6 

3. Coarse dark-green sandstone 4 

2. Coarse grayish-white sandstone 20 

I. Granite. 

Peale says (p. 202): " Beds Nos. 2 to 5 I have referred to the Potsdam group, 

while those just above are undoubtedly of the Quebec group, as in beds lithologically 

the same on the western side of the range I found characteristic fossils." This is 

not altogether conclusive, but certainly the correlation suggested appears the most 

satisfactory one. Yet it is possible (though not probable, since that formation is not 

found in Manitou Park) that these lower beds are the Harding sandstone, which 

Cross says on the southeast side of the range rests locally on the basal cherty 

limestone (Cambrian), or even on granite. The beds immediately above 5 are red 

limestones, from which no fossils are known, but which Peale refers to the 

14364—No. 16 03 10 
146 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Quebec group. Cross also visited Manitou Park in connection with the work of the 

Leadville monograph. He found about 50 feet of reddish-brown sandstone resting 

upon the Archean and succeeded by about 200 feet of calcareous sandstones and 

shales of variegated colors, red prevailing, which pass up into white or drab 

limestones, sometimes containing chert secretions and alternating with shalt' beds. 

The lower beds furnished a Lingulepis related to L. pinn,iformis, while from 60 to 

77 feet above, an Ordovician fauna was obtained. The limestone is without doubt 

the Manitou limestone, and the Cambrian is correlated, by Emmons, with the Lower 

quartzite (Sawatch quartzite) of the Leadville area. In the Pikes Peak quadrangle 

the Cambrian is reported as present, but in measures too thin to be given separate 

representation upon the map. It consists of quartzite and cherty limestone. 

In Walcott's Canyon section no paleontologic evidence has been found to indicate 

the presence of Cambrian, and there hardly seems room for it below the earliest 

Ordovician strata. It appears, therefore; best to regard the Cambrian as absent at 

this point. Walcott's section rests immediately upon the Algonkian, and Cross's 

remark regarding the Harding sandstone, which I have quoted above, was apparently 

made with reference to a case similar to this. 

No Silurian, under which term the Hayden geologists included also Cambrian, is 

represented in the Hayden atlas along the mountain front south of the Canyon 

outcrop, and at some points it is almost certainly wanting, as in Lee's section in 

the. Sangre de Cristo Range west of Trinidad, near the southern border of the 

State. Indeed it is probably wanting over much of the range except its northern 

portion, but E. C. and P. H. Van Diest have shown it and the Yule. limestone to 

exist on the west side of the Sangre de Cristo Range near Culebra Peak, as I have 

already mentioned. The evidence is purely lithologic and stratigraphic, but the 

occurrence seems to be authentic. The formation here is a white quartzite with a 

basal conglomerate closely similar to the typical Sawatch quartzite. 

In the San Juan region the Cambrian is probably represented by the 200 feet 

of yellow, white, red, and brown quartzites occurring below the Ouray limestone. 

These were tentatively placed as the lower member of the Devonian by Cross and 

Spencer, but their Cambrian age is suggested by their lithology and stratigraphic 

position when compared with other Colorado sections, and by the fact that Mr. Cross 

has found among - some talus very probably belonging to this formation, a block of 

quartzite covered with linguloid shells which can apparently be referred to the genus 

Lingulella. 

In the valleys of Grand and Dolores rivers and many of their tributaries the 

Cambrian appears to be unrepresented, the Carboniferous in some cases and in others 

sediments of later age resting immediately upon the Archean. 

Two of the most marked peculiarities of this formation are its diminution in 
RECAPITULATION OF PALEOZOIC FORMATIONS. 147 

thickness eastward, and its change of character along the Front Range. Its 

thickness in the Crested Butte quadrangle is from 50 to 350 feet; near Aspen 350 

to 400 feet in the south and 200 feet or less in the north. On Eagle River it is 604 

feet (Peale); at Red Cliff 235 feet (Tilden); in the Tenmile district 160 to 200 feet; 

in the Leadville district 150 to 200 feet. On the east side of the Mosquito Range 

it is only 40 feet; in Manitou Park, at different points, 40, 86, and 100 feet (Peale); 

in Perry Park 105 feet (Peale); at Colorado Springs 50 feet (Peale); in the Pikes 

Peak quadrangle, too thin to be mapped; at Canyon (and all but a few places along 

the Colorado and Sangre de Cristo ranges) absent; near San Luis 160+ feet (Van 

Diesf); in the San Juan region 0 to 200 feet. It seems to be generally present over 

the Grand River, Elk Mountain, and South Park, and in the northern end of the 

angre de Cristo areas. 

The Cambrian of the Front Range for the most part seems to consist of reddish 

sandstones more or less comparable to the Black Hills Cambrian and to the upper 

part of the Sawatch quartzite which rests upon white quartzite in the Crested Butte 

district and elsewhere. If the red sandstones of the Front Range do prove to be 

the same as the reddish part of the Sawatch considerable evidence of an unconf ormity between its two members seems to be furnished by the fact that the red 

member is lacking in some areas (e. g„ on Eagle River, at Red Cliff, and locally 

at Crested Butte), and the white quartzite is lacking in others (along the Front 

Range). 

ORDOVICIAN. 

There is no evidence of the presence of Upper Silurian strata in Colorado. 

The only Silurian known is that of the Ordovician, though many of the older surveys 

employed this term to include the Cambrian also. In central Colorado this is a limestone formation, and has received the name of the Yule limestone. The Silurian is 

not a formation of great thickness anywhere in the State. Its outcrop is linear and 

generally follows that of the Cambrian Sawatch quartzite. 

In the Crested Butte quadrangle, its typical area, the Yule limestone is assigned 

an aggregate thickness of 350 to 450 feet. Three subdivisions are recognized, the 

lower of which consists of quartzite, the middle of limestone, and the upper of manly 

variegated beds. The quartzite, 75 to .100 feet thick, is generally white, often calcareous, and contains indistinct fossil remains. The limestones of the middle division 

are 250 to 280 feet thick, light colored, thin bedded, frequently siliceous, especially at the base, and carry grayish-white cherts. They contain characteristic 

fossils, among which may be mentioned the fish scales abundantly found at this 

horizon near Canyon. The upper division is 60 to 90 feet thick, and its horizon is 

said to be wonderfully persistent in retaining the same lithologic characters. 

In the Aspen district, to the Silurian are referred some pure dolomites of light 

gray-blue color, hard and compact, with a fine frosty luster. They are also some-
148 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

what siliceous. Like the Cambrian, these beds are said to thicken toward the south 

and to range from 250 to 400 feet. It seems to me probable that Spurr's Silurian 

corresponds to only the middle division of the three which Eldridge makes in the 

Yule limestone, for the upper division of Eldridge's section Spurr correlates with 

the Parting quartzite. The lower division may not exist at Aspen or elsewhere, 

and is in fact very variable at Crested Butte, being even wanting in places. It is 

more like Spurr's Cambrian than his Silurian, and there seems a possibility that the 

line between Cambrian and Ordovician may have been variously taken in different 

areas. The occurrence of a glauconitic horizon, to which Spurr calls attention, in 

the upper part of the Sawatch in the Crested Butte and Aspen districts, and in 

Peale's Calciferous group on Eagle River, seems to warrant a provisional correlation. 

Above the glauconite at Aspen occur sandy dolomites of unrecorded thickness, while 

above the glauconitic sandstone in Peale's section are found about 175 feet of sandstone and quartzite that may represent the quartzite series at Crested Butte which 

Eldridge, apparently upon fossil evidence, separated from the Cambrian and placed 

in the Ordovician. The lower member of the original Yule limestone, therefore, 

probably represents the transitional beds elsewhere grouped with the Sawatch 

quartzite. 

In Peale's Eagle River section the quartzite and sandstone of his Calciferous 

group are succeeded by 219 feet of light colored magnesian limestone. This is the 

Yule limestone. Spurr found this formation to be thinning toward the north. Its 

thickness in the northern portion of his area was 250 feet, and its reduction to 219 

feet in Peale's section is quite in line with this observation. 

Tilden describes the entire section below the Leadville limestone at Red Cliff 

as consisting wholly of quartzite and sandstone, with a total thickness of but 250 

feet. He denominates a few feet at the top of this series as " Silurian quartzite," by 

which may be meant the Parting formation, and while it seems more probable that 

this, like the beds below, is Cambrian, there is evidently nothing in the sub-Leadville 

series which invites comparison with the Yule limestone. 

In the Tenmile district the Yule limestone is represented by a series of light 

drab-colored limestones, which are often magnesian and always more or less siliceous, 

sometimes passing into calcareous sandstone. Their thickness averages 120 to 160 

feet, and the scanty paleontologic evidence determines their age to be probably 

Ordovician. 

In the Leadville district this formation was originally called the White limestone, 

and was said to consist in the main of light drab dolomite, with from 10 per cent 

upward of silica. It is characterized by concretions of white, semitransparent 

chalcedony or chert. The average thickness is 120 to 160 feet. 

Farther south in the Mosquito Range our information is less satisfactory. 

Stevenson found the Silurian, under which title are included all the sedimentary for-
RECAPITULATION OF PALEOZOIC FORMATIONS. 149 

mations below the Carboniferous limestone, to be practically continuous from Mount 

Lincoln to the Arkansas, and it is thus represented on the Hayden atlas. The Silurian appears upon the west but not upon the east side of South Park, apparently 

indicating an overlap of the Carboniferous at this point along a line having a northsouth trend. In the canyon of Fourmile Creek the beds referred by Stevenson 

to the Silurian consist of two limestones separated by 1,10 feet of sandstone, with some 

Cambrian quartzites at the base. The lower limestone is 40 feet thick, siliceous, and 

contains fossils which probably indicate the Ordovician. The upper limestone is 20 

feet thick, red, argillaceous, fissile, and without distinct fossils. The intermediate 

sandstones are converted into quartzites, and it seems to me probable that they 

represent the Parting quartzite. In this event of course the upper limestone would 

not belong to the Yule. On the other hand the succession at this point suggests the 

Manitou, Harding, and Fremont formations of the Front Range. In the Arkansas 

Canyon the Yule compromises 112 feet of limestone, varying from dove color to 

black, overlain by partially altered sandstone with layers of quartzite. The latter 

probably is the Parting member, and Stevenson is, without much doubt, correct in 

correlating the limestone with the Lower limestone of the former section. 

Endlich also describes two sections in the South Park region, but without giving 

the thickness of the constituent beds. They are located in the southern portion of 

the region, but their exact situation can not now be ascertained. The beds observed 

at station 56 have at the base a porphyritic granite above which occur yellow and 

brown quartzite, white and pink quartzite, yellowish shales interstratified with 

quartzites, blue limestone alternating with gray shales, etc. It seems probable 

that the porphyritic granite is an intrusive rather than an Archean body, in which 

case the quartzite, because of its relation with the rest of the section, would better 

be taken as the Parting quartzite instead of the Sawatch, which would be the 

natural interpretation if the igneous basement rock were the Archean. The blue 

limestone with Orthis, crinoids, etc., would then be the Leadville limestone, while 

the red sandstone above is clearly the Arkansas sandstone. In the section made at 

station 53 the beds which appear to belong to the Yule are described as a blue 

quartzitic limestone with crinoids and Orth,oceras, separated from a hard gray 

limestone with corals and sponges by a thin shale bed. The gray limestone is 

overlain by white, yellow, and pink quartzites, which I take to represent the 

Parting quartzite, and to be the same series that formed the base of the previous 

section. The blue siliceous limestone rests immediately upon coarse-grained red 

granite. It does not seem altogether probable that in this instance the granite is 

intrusive, and in the event of its belonging in the Archean this seems to be an 

instance of the overlap of the Yule over the Sawatch member. 

The Silurian is accordingly mapped in the Hayden atlas almost continuously 

along the west side of South Park to the Arkansas River, and south of the river in 
150 CARBC►NIFEROUS FORMATIONS AND FAUNAS OF COLORADO 

the northern end of the Sangre de Cristo Range. Endlich describes it in section e 

of the San Luis district as a gray to bluish limestone with siliceous segregations, 

characters which apply equally to the typical Yule of the Crested Butte district or 

to the White limestone at Leadville. It rests upon a quartzite having the characters 

of the Sawatch quartzite. Except in the vicinity of the Arkansas River neither 

Endlich nor Stevenson found any Silurian in the Sangre de Cristo region, and in the 

Hayden atlas it is represented as missing, the Arkansas sandstone resting immediately 

upon the granitic axis of the range. 

In a recent detailed section by Lee, made near Culebra Peak, the older Paleozoics 

certainly seem to be unrepresented. E. C. and P. H. Van Diest, however, on the west 

side of the range, at a point nearly opposite Lee's section, in an area in which the Carboniferous color appears on the Hayden map, found not the Arkansas sandstone, but 

beds which appear to belong to the Sawatch and Yule formations. The supposed 

Silurian rests upon the white Cambrian ( ? ) quartzite separated only by a thin bed 

of argillaceous shale, and consists of light gray siliceous limestone about 200 feet 

thick, with others of darker color above.a Possibly other isolated occurrences similar to the foregoing will be discovered in the Sangre de Cristo region. 

Of the Paleozoics of the central Colorado area which lies north of the Eagle 

and Grand rivers, we know next to nothing except that there seems to be a much 

greater development of the Cambrian and Ordovician.b 

The section of the Uinta Mountains is lithologically unlike that of the rest of 

Colorado, and our paleontologic evidence is so incomplete and to a certain extent so 

contradictory that it will be useless to look there for the Yule limestone or a representative of it until better information is at hand. It appears, at least, to be absent 

in its character of a limestone, and should it prove to be represented there, it must be 

by some as yet undifferentiated portion of the Uinta sandstone. I am not unprepared, however, to find that the whole Uinta series is of Carboniferous age. 

Turning now to the Front Range we find the Ordovician section, like the Cambrian, different from that of the interior of the State. The most complete section is 

that of the Pikes Peak quadrangle, and I will briefly recapitulate the formations 

there found and their characters, before touching upon the other sections. In the 

Pikes Peak folio,' Cross recognizes three Ordovician formations—the Manitou limestone, the Harding sandstone, and the Fremont limestone. The oldest of these, the 

Manitou limestone, is a fine-grained pink or reddish dolomite less than 100 feet thick, 

containing 0_ph,ileta, Camarella, and a few other Ordovician fossils. The Harding 

sandstone has a maximum thickness of 100 feet and is made up of fine-grained sac­

.charoidal sandstone in alternating banks of light gray and pinkish or variegated colors 

a Colorado Sci. Soc., Proc., vol. 5, 1898, pp. 76-80. 


b Peale, U. S. Geol. Geog. Surv. Terr., [Eighth] Ann. Rept., for 1874, 1876, p. 110. 


a U. S. Geol. Surv.. Geol. Atlas United States, folio 7. 1894. 

RECAPITULATION OF PALEOZOIC FORMATIONS.. 151 

with• a few bands of dark-red or purplish sandy shale. It contains fish plates and 

scales, and a rich invertebrate fauna like that of the lower Trenton of New York. 

The Fremont limestone is a bluish-gray or pinkish dolomite of uneven grain. It is 

100 feet thick in Garden Park, but increases southward, reaching a maximum of 270 

feet near Canyon. It is characterized by lialysites catenulatus, and contains also a 

large invertebrate fauna like the upper Trenton of New York. The Harding is 

separated from the Manitou limestone by an unconformity, and the Fremont is similarly separated from the overlying Millsap limestone. As the distribution of these 

formations is far from uniform, and as the Pikes Peak quadrangle contains portions 

of two distinct and different areas of outcrop, I will depart from the artificial collocation of the folio and discuss the areas in their natural relations. 

Ordovician strata are known along the Front Range in Colorado at Perry Park, 

at Manitou Park, near Colorado Springs, and about Canyon. 

Between the outcrops in the vicinity of Colorado Springs and those to the north 

of Canyon a small area of Silurian is represented in the Hayden atlas. Of these beds 

no description has been found, but presumably they comprise some of the formations discriminated by Cross in the Pikes Peak quadrangle just to the west. In 

addition to the foregoing, King distinguishes in Wyoming a series at the base of the 

Red Beds which he correlates with the Black Hills Primordial, and regards as. the 

representative of almost the whole of Paleozoic time. The beds immediately overlying contain Pennsylvanian fossils, and both series are included under the Carboniferous color in bands extending along both flanks of the Front Range, the more 

eastern of these reaching from Wyoming a short distance into Colorado. This 

correlation with the Black Hills beds is based upon lithology and position, and 

lies especially between the Cambrian of the Black Hills and of the Front Range. 

The presence of Ordovician beds in the series discriminated by King remains an 

open question. 

The Pikes Peak quadrangle includes part of the Manitou Park tract. In this 

area only the Manitou limestone appears and it derives its name from this occurrence. 

Peale has given a number of sections in Manitou Park, and these show the following characters of this formation, its equivalents being ascertained as well as I am 

able. The section on page 207, made on a small stream flowing into Trout Creek, 

is as follows: 

Section near Trout Creek. Feet. 

3. White massive limestone }100 4. Shaly-white limestone 

5. Pink limestone 30 

6. Green sandstone 4 

7. Brown-purplish sandstone 6 

8. Yellow sandstone 

9. Granite 
152 . CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The lower part of the section should probably be referred to the Cambrian, the 

Manitou limestone embracing beds 3, 4, and 5, which are succeeded by the sandstones 

and conglomerates of the Red Beds. In sections 4 and 5, on page 208, probably only 

the pink limestone forming the highest bed of the section should be referred to the 

Manitou. In it were found an Orthis like 0. desmopleura, Euomphalus, Asaphus 

(Vegalaspis), Conocoryphe, Lingula, Bathyurus, and Paradoxides, or Olenus. Peale 

unites this with the bed 6, assigning them, with a combined thickness of about 60 feet, 

to the Quebec group, but as the blood-red calcareous sandstone (bed 6) is said to 

contain Lingulepis and Obolus, it seems that it should be united with the strata below 

which Peale calls the Potsdam. Another section (sec. 6, p. 208) was made on Trout 

Creek. The lower portion was concealed, the exposures consisting altogether of beds 

which probably belong to the Manitou. These are from below upward: 

Section on Trout Creek. 

Feet. 

6. Yellowish white limestone 20 

5. Mottled limestone 3 

4. Purplish sandstone 

3. Red limestone 34 

2. Light shady limestone 20 

I. Red limestone 26 

These give a combined thickness of 100 feet. The lowest limestone is fossiliferous, the fauna cited indicating Ordovician. Section 7 (p. 209) was made on a small 

tributary of Trout Creek. Though no fossils were found in this section, by analogy 

with the sections 4 and 5, with which a close agreement exists, all the lower portion 

belongs in the Cambrikn, and only the 16 feet of pale pink and gray limestone (bed 7) 

and the pink limestone above it belong in the Manitou limestone. 

The beds in Manitou Park were examined in connection with the geologic work 

of the Leadville monograph. On page 62 of this work it is stated that Whitman 

Cross obtained from a reddish brown sandstone, 45 feet above the Archean, a species 

of "Lingulepis related to L. pinnceform,is of the St. Croix sandstone of Wisconsin." 

From red calcareous' sandstone alternating with white limestone 105 to 122 feet above 

the Archean, he obtained Glyptocystites (?) sp., Lingula sp., Orthis desmopleura, 

Ifetoptoma n. sp., Cyrtolites sp., Orthoceras sp., and Bathyurus simillimus (?). The 

Ordovician age of this fauna is not to be questioned. It is said to be essentially the 

same as that of the upper third of the Pogonip limestone of Nevada. Lithologically the beds in which these fossils occur do not exactly agree with any one of the 

varying sections described .by Peale, but they are most similar to section 6. 

The geologic section in Perry Park has been described by Peale and later by 

W. T. Lee. In Peale's section a there appears to be no equivalent of the Manitou 

cr U. S. Geol. Geog. Surv. Terr., [Second] Ann. Rept., for 1875, p. 197. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 153 

limestone,, though the lower part resembles the Cambrian beds of Manitou Park. 

Lee found a series of cherty limestones interstratified with red clay, in which were 

found Dalmanella testudinamia and other fossils obscurely preserved, indicating 

Ordovician time. This occurrence is south of Perry Park and the Ordovician there 

rests upon a deep red quartzite supposed to be Cambrian. A. similar bed exists in 

the southern part of Perry Park, where it is represented on the map as resting upon 

the pre-Cambrian and as being overlaid by Red Beds. No fossils were found at this 

point. These beds appear to be missing in the exposures on Plum Creek, according 

to both Peale and Lee. The horizon of this formation in the Plum Creek section 

should be below the Mississippian limestone and above the sandstones which underlie 

it, if the latter are, as I have suggested, Cambrian. To explain what now appear 

to be the facts of distribution of these formations requires an overlap of the Ordovician upon the Archean, and an erosion period followed by an overlap of the Mississippian upon the Cambrian. 

Peale also made a section through Glen Erie, near Colorado Springs.a The 

sandstones at the base probably belong to the Cambrian. Peale refers them to the 

Potsdam, and the beds just above to the Quebec group. The latter, ascending, is as 

follows: 

Section through Glen Erie. Feet. 

13. Red shaly limestone with fragments of fossils (Silurian) 4 

12. Limestone with interlaminated shale 7 

11. Red limestone with flint nodules 7 

10. Red limestone 2 

9. Red shaly limestone 1 

8. Red limestone 1 

7. Irregularly laminated limestone 5 

6. Red and greenish limestone 5 

These, I believe, can all be safely referred to the Manitou limestone, together 

with part of the bed following, No. 14, consisting of 279 feet of gray„purplish, and 

yellow limestone. The upper portion at least represents the Millsap formation. 

The Ordovician beds here also appear to belong to the Manitou limestone. 

The Paleozoic outcrops of Garden Park. in the southern part of the Pikes Peak 

quadrangle connect with those about Canyon. The section in Garden Park contains 

both the Manitou limestone, the Harding sandstone, and the Fremont limestone, 

whose description, abbreviated from the Pikes Peak folio, has already been given. 

The geologic section at Harding's quarry near Canyon was described by C. D. 

Walcott, and it is from this series that the names Harding sandstone and Fremont 

. limestone were adopted by Cross. The Cambrian is apparently lacking in this 

section, the Harding resting directly on the Algonkian. The Harding sandstone, 

with a thickness of 86 feet, consists of gray, reddish, and purplish-brown sandstones 

U. S. Geol.. Geog. Surv. Terr., [Seventh] Ann. Rept„ for 1873, p. 201. 
154 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and shales, and from it an extensive fauna is listed, from which the conclusion is 

drawn that the formation is of lower Trenton or Black River and Birdseye age. 

The Fremont limestone series consists of red and purple fine-grained arenaceous 

shales, gray siliceous limestone, compact light-colored limestone, dark reddish brown 

sandstone, and compact light gray limestone, a total of 274 feet. Walcott 

apparently included here 15 to 30 feet of impure variegated banded limestone with 

interbedded sandstones and argillaceous beds containing Carboniferous fossils. 

This, Cross later differentiated and called the Millsap limestone. The fauna of the 

Fremont is large and varied and is compared with the middle and upper Trenton of 

America, or the Bala of Europe. The fauna of the Harding sandstone is remarkable 

for its fish remains, associated with a well-marked Ordovician fauna. With the 

outcrops near Canyon, at one of which the section quoted from Walcott was made, 

the Paleozoic area included in the southern portion of the Pikes Peak quadrangle is 

essentially continuous. The section in Garden Park, however, includes Cambrian 

beds, the Manitou limestone, the Harding sandstone, and the Fremont limestone, 

while only the Harding and Fremont are found at Harding's quarry. Furthermore, 

the thickness of the Fremont limestone in Garden Park is about 100 feet, but it 

increases southward, and near Canyon reaches a maximum of 270 feet. This is 

partly through the development of an upper and highly fossiliferous member not 

seen in Garden Park (Cross). 

In the Pueblo quadrangle the Cambrian and the Manitou limestone appear to be 

wanting, and possibly also the Fremont limestone. The beds referred by Gilbert to 

the Harding consist of white sandstone and rest upon the Archean. They are 

followed in the section by a series of gray and purplish limestones, some 200 feet in 

thickness, with some shale in the lower part, which Gilbert calls the Millsap limestone. Near the middle of the formation was obtained Spirifer rockymontamus, 

which is cited also from the Millsap limestone of Garden Park, so that the upper 

part of the formation at least is Carboniferous. As the Millsap is only 30 feet thick 

in the Pikes Peak quadrangle, and as the Fremont is 270 feet at Canyon, it is unexpected to find the former increased to 200 feet at this point and the latter totally 

absent. Perhaps, therefore, the lower part of Gilbert's 1V1illsap belongs in the 

Fremont, which otherwise, like the Manitou, has no representative in this area. 

The outcrop of these beds is in the western part of the quadrangle, and includes 

part of the small area which in the Hayden atlas is represented as Lower Carboniferous. Endlich describes these beds as grayish limestone and shale with Carboniferous fossils. 

This is, so far as known, the last outcrop of the pre-Carboniferous sedimentaries 

south of Canyon along the mountain front. None have yet been found on the eastern flank of tne Sangre de Cristo Range, and one detailed section—that made by Lee 
RECAPITULATION OF PALEOZOIC FORMATIONS. 155 

west of Trinidad—leaves little room for doubt that th y are absent at that locality. 

West of Canyon, in the northern end of the Sangre de Cristo Range, Silurian strata 

occur, and are so colored upon the Hayden maps, as h s already been remarked. 

On the western flank of the range, though no Sil rian beds are mapped by the 

Hayden survey, they have been recognized at one loca ity, at least, though the identification rests upon stratigraphic and lithologic, and no upon paleontologic evidence. 

The locality is northeast of the town of San Luis, nea y opposite the point at which 

Lee's section shows its absence on the east side. Li hologically, the Silurian here 

appears to belong to the Yule limestone. 

Attention has already been directed to the differen e between the Silurian section 

of the Front Range and that of the interior of the tate. The evidence is not at 

hand to determine the relationship existing between he two sets of beds. If any 

exact lithologic correlation is possible, it rests betwe n the Yule limestone on the 

one hand and the Manitou or Fremont limestone on t e other. I rather expect that 

the correlation will be made, if at all, between the -ule and Fremont. Emmons 

correlated the Cambrian sandstone and Manitou limest ne of Manitou Park with the 

Sawatch quartzite and Yule limestone of the Leadville section (Leadville monograph, 

p. 64). There deserves to be considered in this connec ion the occurrence of the fishbearing horizons in the Paleozoic rocks of Colorado, hese vertebrate remains being 

in every case of the Devonian type. They constitute aii important factor in the fauna 

of the Harding sandstone and are found also in the Parting quartzite at Aspen, in 

the middle or calcareous division of the Yule limesto e at Crested Butte, and in the 

middle or shaly member of Cross and Spencer's De • nian in the San Juan region. 

The latter I believe can with great probability be p aced in the Parting quartzite 

horizon, and the other occurrences carry the suggesti n that possibly this formation 

is the equivalent of the Harding sandstone. The sequ • nce of the Sawatch, Yule, and 

Parting formations is, therefore, suggestive of the Ca brian, Manitou, and Harding 

beds of the Front Range. In this case the Yule would e e correlated with the Manitou, 

as Emmons has suggested, nor does the occurrence o these fish remains at Crested 

Butte in the formation underlying seem to me a serio s objection to this correlation. 

On the other hand, Eldridge has suggested in the A thracite-Crested Butte folio a 

correlation of the middle or calcareous member of t i e Yule formation in which fish 

scales occur, with the fish-bed in the Ordovician at l anyon. Cross relates that the 

Fremont limestone is especially characterized by the 

in mind that the lowest division of the typical Yule s a quartzite formation apparently assigned to the Ordovician on paleontologic vidence, and that in the Front 

latus, 

Range an unconformity intervenes between the Har ing and Manitou beds. There 

a fossil which is not rare in the Yule limesto i e. It should further be borne 

ii ccurrence of Hak8ites catenuis thus considerable evidence favorable to correlating the lower and middle divisions 
156 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

of the original Yule with the Harding sandstone and Fremont limestone. If future 

information proves the correlation thus suggested, it is evident that the Manitou 

formation must be missing from the section of central Colorado, while the Parting 

quartzite must be missing on the eastern side of the Front Range. 

No lithologic equivalent of the Yule limestone and no strata of Ordovician age 

are known in the San Juan region. Cross and Spencer make a three-fold division of 

the beds which they refer to the Devonian, qualifying the reference by the opinion 

that the two lower members, a quartzite and a shale, may be pre-Devonian. The 

quartzite I have already suggested as a possible equivalent of the. Sawatch quartzite. 

The shalt' member may belong in the Ordovician, but shows a different phase of 

deposition from that which produced the calcareous division of the Yule limestone. 

It more probably represents the upper portion of the typical Yule, which Spurr 

correlates with the Parting quartzite and refers to the Devonian. 

SILURIAN. 

There is but little evidence of the existence of Upper Silurian strata in Colorado. 

Emmons states (Leadville monograph, p. 61): " Casts of a Rhynclionella, between 

B. neglecta and B. inclian,ensis of the Niagara epoch, were found in the prospect 

shaft in California Gulch, not far below the White Limestone quarry, in such a 

position that they must have been derived from the beds of this horizon at least 50 

feet above the base of the formation." The evidence of this one species is unimportant, nor is the deduction drawn from it by Mr. Emmons that any portion of the 

Yule limestone is of Upper Silurian age; and in view of the extreme rarity of Upper 

Silurian strata in the west, considering besides that none are known elsewhere in 

Colorado, and that the. Yule limestone has in many places furnished an Ordovician 

fauna, it is only fair to reason that Upper Silurian time is not, so far as known, 

represented in the rocks of the State, and that the evidence for its existence near 

Leadville is due to the imperfect condition of the fossils or to ill-considered 

identifications. 

DEVONIAN (?). 

Above the Yule limestone over much of central Colorado occurs a second 

quartzite horizon, similar to the. Cambrian at the base of the section. This formation was first discriminated by Emmons, at Leadville, where he called it the Parting 

quartzite, and it has since been recognized at a number of localities. At Leadville 

this formation is a white quartzite, of rather variable thickness but remarkable persistence, and it was regarded as constituting the upper limit of the Silurian. In 

thickness it varies from 40 to 70 feet. On the east fork of the Arkansas evidence of 

nonconformity by erosion was observed at its upper boundary, " which renders it 

possible that the Upper Silurian and Devonian formations may be entirely wanting 
RECAPITULATION OF PALEOZOIC FOI" MATIONS. 157 

in this region." (Leadville monograph, p. 61.) It w 11 also be remembered that 

an unconformity occurs at this horizon in the Front Range region, between the 

Millsap limestone and the underlying beds. 

Spurr identifies the Parting quartzite at Aspen. He gives a section- (Aspen 

monograph, p. 13) in which it is seen to comprise 6 feet of dolomite, dolomitic 

shale, sandstone, and quartzite in thin alternations. t Castle Butte the series is 

said to consist of a basal impure quartzite, a shaly bed stained a deep maroon color, 

a heavy light-green lithographic dolomite, and at.the i p a heavy quartzite. Spurr 

correlates the beds at Aspen having the above character, and a stratigraphic position 

between the Yule limestone and the Leadville limestones with the Parting quartzite 

of Leadville and with the upper member of the Yule li estone as it was differentiated 

and described by Eldridge in the Crested Butte qua' rangle. This portion of the 

Yule is from 60 to 90 feet in thickness and consists o green, yellow, and red and 

white shale, with more or less calcareous layers, the atter passing into thin limestone. The lithologic characters of the bed differ some particulars from the 

Parting quartzite at Aspen, and both differ from he formation at - its typical 

localities. 

Emmons identifies the Parting quartzite in the T•nmile district. It there has 

a thickness of from 15 to 60 feet and consists of silicei us beds, generally quartzites. 

The possibility of its being of Devonian age is referr d to, but it is still retained 

with the Silurian, chiefly because of the unconformity t its top. 

I have not recognized the Parting quartzite in P ale's Eagle River section, but 

the strata are there largely concealed at the horizon at which it ought to occur. 

At Red Cliff, also, the Parting quartzite is possib y missing. Emmons was not 

able definitely to recognize it, nor is its recognition cle r in Tilden's section at Battle 

Mountain. He found beneath the Leadville limesto e the following sedimentaries 

in ascending series: Cambrian white quartzite, 125 fee ; fine-grained sandstone, 100 

feet; Silurian white quartzite, 5 feet; and conglom, rate quartzite, 8 feet. One 

might infer Tilden's opinion to be that the lowest bed of this series represented the 

Sawatch quartzite, the succeeding one the Yule limestone, and the third and fourth, 

probably the Parting quartzite. By this interpretation, however, the Yule is represented by a sandstone, while the Parting formation is reduced to but 13 feet in 

thickness. As the Sawatch measures 400 feet on Eagle River, not to mention a considerable transitional series above it, and 160 to 200 feet in the Tenmile district, all of 

the siliceous beds at Red Cliff, amounting to less than 240 feet, might, as to thickness, without impropriety be referred to the Sawatch quartzite. This, however, 

involves the local absence of both the Yule limestone and Parting quartzite, which is 

open to objection but might be explained through the unconformity by which the 

Leadville limestone was preceded in the Leadville district. While it seems to me 
158 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

more probable that at Red Cliff all the beds below the Leadville limestone belong to 

the Sawatch quartzite, it is quite possible that the Parting formation also is 

included, as indicated by Tilden. • 

Spurr, as we have already seen, correlates with the Parting quartzite the variegated shales which form the upper division of the typical Yule limestone in the 

Crested Butte district. What may be the same series is described by Endlich as 

occurring in the southern part of the Elk Mountain region, south of the Gunnison 

River, in an isolated area called upon the map Fossil Ridge. The series here seems 

to resemble that in the Crested Butte in position, but shows a remarkable increase in. 

thickness. It apparently comprises .80 feet of yellow and gray shales overlaid by .175 

feet of variegated shale, partly sandy, with isolated banks of limestone. These•beds 

occur above a thickness of limestone that can with a high degree of probability- be 

identified as the Yule limestone and below another series of limestones from which 

a Mississippian fauna is cited. The character, thickness, and position of the lower 

shale especially are such as to correlate it with the upper division of the Yule, 

which, according to Spurr, represents the Parting quartzite. Though to regard the 

upper shales as forming part of the same series gives the formation a thickness not 

known at any other point, this course seems more natural than to join them with the 

Leadville series. 

In .the Grand River region the Parting quartzite occurs at Aspen as identified 

by Spurr, and in the Tenmile district as identified by Emmons, but it seems to be 

absent at Red Cliff and may not be present on Grand River. At Fossil Ridge, at 

Crested Butte, and at Aspen this formation seems to lack some of the qualities that 

characterize it at Leadville, being composed, apparently, largely of shales, some of 

which are sandy and some calcareous. In the Tenmile district, however, the composition of the formation is more typical, and it consists for the most part of quartzite. 

In the South Park district the Parting quartzite occurs at Leadville, which is 

indeed its typical area, and it is probably to be found more or less continuously southward to the Arkansas. As part of the Silurian of Stevenson it is described as having 

this distribution, and the Hayden atlas shows the Silurian color continuously along 

the west side of South Park. Stevenson gives two sections in which this formation 

can be recognized. In that made at Fourmile Creek .there appear to belong to it 

170 feet of quartzite the upper portion of which is a conglomerate. These beds 

occur above a limestone which, can probably be correlated with the Yule, and below 

another upon which the Leadville limestone presumably rests. Though Stevenson 

includes the overlying limestone in the Silurian, it would seem more appropriate to 

close the Parting quartzite with the siliceous beds and refer the limestone provisionally to the Leadville. 

A second section was made by Stevenson in the canyon of the Arkansas on the 
RECAPITULATION OF PALEOZOIC FORMATIONS. 159 

southern border of the South Park region. At that locality 75 feet of sandstone 

described as "partially altered, with layers of quartzite; somewhat argillaceous; 

weathers to ochery color; contains many large fragments of jasper," can be referred 

to the Parting formation. It here rests upon 112 feet of limestone which represent 

the Yule, about 20 feet of red calcareous clay intervening between the two formations. 

The overlying beds are not known, and Stevenson remarks (p. 359) that it is more 

than probable that the Arkansas exposures do not exhibit the complete section, 

being defective on top. 

Endlich also gives two sections in this region which include beds belonging, it 

would appear, to the. Parting quartzite. They are situated in the southern part of 

the South Park region, but their exact location can not be known. One of these, 

which was made at station 56, contains a series of yellow to light brown hard quartzites, followed by white and pink quartzites of very fine texture, covered by yellowish shales which are later said to be interstratified with quartzites. Above these 

occur shales and limestones which appear to belong to the Leadville series. The 

underlying rock is a porphyritic granite which is more probably an intrusive than a 

portion of the Archean complex. In the other section, that made at station 53, the 

series is of a similar character. It consists of thick beds of white, yellow, and pink 

quartzites passing into light red sandstone. To this must probably be added a thick 

stratum of yellow and brown sandy shale covered by light yellow and gray shales. 

Beneath the quartzite are limestones whose partially identified fossils are suggestive 

of the Ordovician faunas, and above the shale a blue limestone with a fauna which 

appears to be Carboniferous. It will be observed that in the two sections cited from 

Endlich the strata which occupy the position of the Parting quartzite consist of a 

series of quartzitic beds below and another of variegated shales which rest upon them. 

The quartzitic portion possess considerable resemblance to the typical Parting quartzite, while the shales resemble the beds which at Fossil Ridge, Crested Butte, and 

Aspen, have been referred to the same series. It is possible that these occurrences 

at the same time indicate a dual nature for the strata referred to the Parting formation and demonstrate the stratigraphic relations of the constituent members. 

The Parting quartzite probably forms part of the Silurian of the Hayden reports, 

as it does in the case of Stevenson's. Endlich found Silurian 'strata .along the 

northern edge of the Sangre de Cristo region in that portion of his San Luis district 

which he designates as sections b and c. Here it comprises the Sawatch and Yule 

beds, and he describes nothing which has the lithology and stratigraphic position of 

the Parting series. It may be recalled that at stations 53 and .56 north of the 

Arkansas this author describes two sections in which beds of light-colored quartzite 

are reported as overlying a limestone of probable Ordovician age. These quartzites, 

which hold the position of the Parting quartzite, resemble the Sawatch a uartzite 
160 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

which lies beneath the Ordovician limestone in section e south of the Arkansas. 

Endlich apparently regards them as the same. This fact and the apparent absence 

of the Sawatch in Endlich's sections north of the river lead me to consider it possible 

that he may have mistaken the position of the beds, and that the quartzite really 

occurs beneath instead of upon the Yule. In that case the Parting formation as a 

quartzite would be wanting at stations 5,3 and 56, and the sections at Fossil Ridge 

and on the south side of the Arkansas would be in closer agreement with those made 

there. Along with the Sawatch and Yule, the Parting formation, probably as the 

result of Paleozoic erosion, seems to be wanting over the Sangre de Cristo region 

in all but its northernmost portion, though possibly it may be found in fragments 

associated with them in occurrences such as the Van Diests have made known in the 

vicinity of Trinchera Peak on the west side of the range. 

In the San Juan region it seems to me probable that the Parting quartzite will 

prove to be represented by th.e middle or shaly member of the threefold Devonian 

series of Cross and Spencer, the two lower divisions of which are recognized by 

them as possibly pre-Devonian. This shale in the San Juan region, which has a 

thickness of about 50 feet, occupies a position with regard to the Ouray limestone 

similar to that which the upper or shaly member of the Ytile limestone holds to the 

Leadville limestone in the Crested Butte district. This portion of the Yule, which 

measures 60 to 90 feet in thickness, Spurr believes to be the same as the Parting 

quartzite of the Aspen and Leadville sections. Spurr found fish remains of 

Devonian type in the Parting quartzite at Aspen. Somewhat similar ones occur in 

the middle or calcareous member of the Yule limestone at Crested Butte, while 

Endlich cites them from the middle or shaly division of Cross and Spepcer's 

Devonian. While positive proof is lacking, it seems to me that a number of circumstances favor the correlation of these shales in the Crested Butte district and San Juan 

region. The absence of the calcareous and typical Yule limestone in the latter area 

shows an independence of distribution which would seem to justify the separation of 

the upper from the middle divisions of that series made by Spurr. Its correlation 

with the Aspen section and position in the time scale, however, are questions apart, 

and I am indisposed to accept the evidence for the Devonian age of this horizon as 

conclusive. 

The Paiting quartzite was included by Stevenson in the Silurian, to which he 

referred all the sedimentaries below the Carboniferous limestone, and the practice 

of the Hayden survey appears to have been the same. Emmons, as we have already 

seen, refers it to the Silurian in his Leadville work. Eldridge, in the Crested Butte 

district, includes what, according to Spurr, is an equivalent body, as the upper division 

of his Yule limestone. Spurr recognized the Parting quartzite at Aspen, but, on the 

strength of some fish remains of Devonian type, assigns the formation to that period. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 161 

In the Tenmile folio, however, Emmons; while recognizing the data upon which 

Spurr proceeded, in the lack of direct evidence as to the age of these beds, still 

retains them in the Silurian, influenced to a considerable extent by the unconforinity 

which intervenes between it and the overlying Leadville limestone. Although Spurr 

found Devonian fishes in the Parting quartzite at Aspen, it should be borne in mind 

that similar fish remains of Devonian types occur in the Harding sandstone, whose 

Ordovician age seems to be secure, and in the calcareous division of the Yule 

limestone in the Crested Butte quadrangle, of whose Ordovician age there is also 

little doubt. In view of these facts the force of this evidence is largely destroyed. 

Considering that the only known Paleozoic horizon in Colorado distinguished. for its 

fish remains is in the Ordovician, that the Parting quartzite is separated from the 

Leadville limestone, at Leadville at least, by an erosional unconformity, and that 

the lower portion of the Leadville limestone contains over large areas a Devonian 

fauna, it seems to me that the evidence preponderates in favor of the Ordovician 

rather than the Devonian age of the Parting quartzite. This, however, is only 

another of the departments in which further and thorough research is necessary 

before a satisfactory conclusion can be reached. If the Parting quartzite should 

prove to be Ordovician, it would bring out a certain correspondence between 

the early Paleozoics of the Front Range and those of 'central Colorado, for the 

Manitou limestone and Harding sandstone of the one show a certain resemblance to 

the Yule limestone and Parting quartzite of the other, which, while not extremely 

close, certainly gives the two sections more uniformity than if the Parting quartzite 

were Devonian. Both the Parting quartzite and the Harding sandstone are siliceous, 

they are variegated in color, have about the same thickness, and are characterized 

by containing fish remains. It is true, however, that the abundant Trenton fauna of 

the Harding is not yet known in the Parting quartzites, and that the Yule limestone 

in the Crested Butte quadrangle also contains fish remains, while none have been 

noted from its possible equivalent, the Manitou limestone. 

DEVONIAN. 

There is an undoubted Devonian horizon in Colorado. The fauna was originally 

discovered in the San Juan region and it has since been recognized at widely separated points through the State. These fossils were first listed and described by 

Meek", who identified the horizon as Devonian. Later, C. A. White found some 

reason, which was never stated, for regarding it as Carboniferous. More recently 

extensive collections were made in the San Juan region by Whitman Cross and A. C. 

Spencer, who procured a large fauna, which I described in 1900.° The latter fauna is 

a U. S. Geol. Geog. Surv. Terr., Bull,, vol. 1, 2d ser., No. 1, p. 46, 1875, see also U. S. Geol. Geog. Surv. Terr [Eighth] 

Ann. Rept. for 1874, 1876, pp. 212-214. b cont. Invert. Pal., No. 6, p. 133, 1880 (extracted from the Twelfth Ann. Rept. of the Hayden survey for 1878). 

CU. S. Geol. Surv., Twentieth Ann. Rept., pt. 2, pp. 25-81. 

14364—No. 16-03 11 
162 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

extensive enough and critical enough to clearly demonstrate the Devonian age of this 

horizon and vindicate Meek's earlier judgment. This fauna occupies the major portion of the Ouray limestone of the San Juan region and the lower part of the. Leadville limestone of central Colorado. It has been found in the Durango and Engineer 

mountain quadrangles of the San Juan region, at Ouray, in the Crested Butte quadrangle, at Salida, at Glenwood Springs, and on White River in northwestern Colorado. 

It seems probable that it will also be found, if sought for, in the lower part of the 

Leadville limestone at Leadville, and, in fact, wherever this formation is exposed in 

Colorado. Perhaps the only strict exception which need be made is along the Front 

Range, where the Millsap limestone, the probable equivalent of the Carboniferous 

portion of the Leadville limestone, appears to lack this Devonian horizon. There 

are areas also in which the Leadville limestone is probably missing, and there, doubtless, it may not be expected. Of the distribution of this formation, I will speak 

a little more specifically in connection with its Mississippian fauna. 

The Ouray fauna, as I may continue to call it, is not closely similar to the faunas 

'of eastern and central United States. It seems indeed to have a closer parallel in 

the Devonian of the Ural Mountains,a with which it shows some striking similarities. 

It also has points in common with and seems to be related to the interior Devonian 

of the Rocky Mountain. region. The absence of this fauna in certain areas where 

the Mississippian fauna, which it often accompanies, is present, as on the eastern 

margin of the Front Range, and apparently over part of the Wasatch Range (e. g., 

Rock Canyon), leads me to think that probably deposition was not quite continuous 

even where both faunas occur, and both are found in limestones, and that a slight 

unconformity may exist between the strata characterized by the Devonian and 

Mississippian faunas in the midst of the Ouray and Leadville formations. 

CARBONIFEROUS. 

MISSISSIPPIAN. 

The Lower Carboniferous strata of Colorado are geologically comparatively 

unimportant by reason of their thinness, but they are widely distributed and form 

one of the richest metalliferous horizons in the entire rock series. This horizon is 

everywhere a limestone or a dolomite, sometimes more or less interstratified with 

shale, but owing to minor differences of lithologic character and circumstances of 

distribution several local names have been received by it. In central Colorado this 

limestone is called the Leadville limestone. In the San Juan region it is called the 

Ouray limestone, and, along the Front Range it has received the name of tha Millsap 

limestone. The lower portion almost everywhere contains a distinctive and unmistakable Devonian fauna. At least this fauna has been found at so many and such 

a Murchison, etc., Geologie de la Russie, Paleontologic, London. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 163 

widely separated points that it may safely be regarded as generally present over the 

central part of the State wherever the formation is brought to view. In the few 

fragments of it which are still visible along the Front Range, however, the Devonian 

fauna seems to be wanting. This individuality in the matter of distribution has led 

me to suspect that the Devonian and Carboniferous portions of the Leadville limestone may not have been deposited strictly consecutively. 

Beginning with its typical locality at Leadville, this formation is described as a 

heavily bedded series of dolomitic limestone, in the upper part often coarsely crystalline, having an average thickness of 200 feet. The color is a deep grayish blue, 

frequently nearly black in the upper portion, while some of the lower beds are lighter 

in color, approaching a drab. The upper bed is marked by characteristic concretions 

of black chert, often containing casts of fossils. A list of species of fossils derived 

from this horizon is appended to the description in the Leadville monograph, and 

the conclusion drawn that "this horizon represents the Lower Carboniferous of this 

district." (Page 66.) This conclusion I believe to be correct, though it hardly seems 

to follow from the faunal list, which, with one exception, contains nothing but Upper 

Carboniferous species. In the Leadville monograph, from which I have quoted above, 

this limestone is called the Blue or Ore-bearing limestone, and it was not until later 

that it received the name by which it is now known. 

Under the title of the Blue or Leadville limestone this formation is redescribed 

by the same author in the Tenmile folio. No new facts are brought out, and it will 

not be necessary to repeat the description. 

It is easy to recognize this horizon in Peale's Eagle River section, in which 

bed 26, described as a black, flinty limestone, with pieces of pyrite and fragments 

of Spinfer or Spiriferina, clearly represents it. Possibly a part of No. 25, which 

'indicates a space probably filled mainly by limestone, also belongs to the Leadville, 

but it is evident that little besides distribution is added in this instance. 

At Red Cliff; according to Tilden, the Leadville limestone comprises 250 feet of 

blue, dolomitic limestone below, overlaid by black, siliceous limestone 300 feet thick. 

In the Aspen district the Leadville limestone has an average thickness of about 

350 feet. It consists of two members, the lower of which is a heavy dolomite from 

200 to 250 feet in thickness, and the upper a massive blue limestone from 100 to 150 

feet. Spurr states that there is abundant evidence of two periods of dolomitization, 

one of which occurred before the deposition of the Blue limestone, while the other 

was much later, and was closely connected with the ore deposition (page 22). This 

fact and the circumstance that these two divisions have a well-marked plane of separation (page 23) afford evidence in support of the hypothesis that an interruption in 

sedimentation occurred between the Devonian and the Carboniferous portions of the 
164 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Leadville and Ouray limestones. Some further evidence may possibly be found in 

the sandstone dikes occurring in the lower dolomitic member, to which Spurr has 

called attention. In this connection, however, it remains to be shown that the 

Devonian phase of Leadville deposition is represented in the Aspen beds, and that 

the stratigraphic plane noted by Spurr corresponds to the time boundaries between 

the Devonian and the Carboniferous. Regarding the former point, the wide distribution of the Devonian fauna and its recognition at points as near as Salida, Glenwood 

Springs, and the Crested Butte quadrangle, make its presence at Aspen a matter of 

great probability. Regarding the second particular, on the other hand, Spurr very 

naturally seeks to correlate the lower or dolomitic member at Aspen with the entire 

Leadville limestone at Leadville, which is only 200 feet thick and dolomitic through 

out, and with the lower, dolomitic portion of the Leadville in the Crested •Butte 

quadrangle. This inference would tend to indicate that the line between Devonian 

and Carboniferous is not coincident with that between the dolomitic and calcareous 

portions of the Leadville, since I refer fossils from this formation at Leadville to the 

Carboniferous. It is possible that the difference in facies between the Leadville • 

faunas as we know them, from Leadville on the one hand and Aspen and the Crested 

Butte region on the other, may be due to a difference of horizon in agreement with 

the correlation suggested by Spurr. It is noteworthy that the Millsap limestone, 

whose fauna is similar to that at Leadville and different from those at Aspen and. 

Crested Butte, is also. dolomitic. From the dolomite in the Aspen region no fossils 

are known, but Spurr mentions a number of foraminiferal genera as having been 

identified by R. M. Bagg in thin sections of the Blue limestone. 

In the Anthracite-Crested Butte folio, where I believe the name Leadville 

limestone is first mentioned, it is described somewhat as follows: Its thickness varies 

from 400 to 525 feet and it consists principally of beds of limestone from 5 to 30 feet 

thick, sometimes separated by bands of quartzite or calcareous shale. At the top of 

the formation is a massive bluish-black bed 75 to 150 feet thick, known to miners as 

the "Blue limestone." Below this the limestones are grayer, apparently somewhat 

dolomitic, and carry a few dark-gray or black cherts. The Leadville here seems to be 

much thicker than at 'Leadville itself, a condition which can be adequately explained 

by the erosional unconformity•by which the formation is followed. 

The character of the Leadville at some of the points where it is best known has 

been briefly outlined. In the Grand River region it has been studied in 'more or 

less detail at Aspen, at Red Cliff, on Grand River, and in the Tenmile district, and 

the statement seems justified that it is generally present in that area. In. the Elk 

Mountain region also it may be said to be in all probability continuously present. 

Its occurrence in the Crested Butte district has already been described. Endlich 

gives a section made at Fossil Ridge south of the Gunnison, in which the Leadville 

probably includes 260 feet of light gray and yellowish limestone and shale, 40 feet 
RECAPITULATION OF PALEOZOIC FORMATIONS. 165 

of light shale, and 20 feet of dark-blue Carboniferous limestone. This 20-foot bed 

contains a fauna which is compared with that found near Mystic Lake in Montana, 

and is without much doubt a member of the Leadville limestone. It is followed by 

45 feet of light shale, 150 feet of light limestone and quartzite, and 50 feet of yellow, 

red, and white shale. These may belong either to the Leadville or the Weber 

limestones so far as any information is at hand. The light-colored limestone which 

I have included with the Leadville is underlain by 80 feet of yelloW and gray shale 

and 175 feet of variegated shale with isolated banks of limestone. Both of these 

beds probably belong to the Parting formation, though here again satisfactory 

evidence entirely fails. 

In the South Park region the Leadville limestone, as it occurs at Leadville and 

its vicinity, has already been described. Information with regard to the region 

south depends chiefly upon the accounts of Stevenson and of Endlich, though Peale 

also has briefly touched upon it. Stevenson usually refers to this formation as the 

Carboniferous limestone, and he apparently found it at intervals on the west side of 

South Park all the way from Mount Lincoln to Hunts Peak. He gives no sections 

and no detailed description. Endlich publishes two sections which include the 

Leadville beds, but their exact location can not be determined. They occur in the 

northern portion of his San Luis district and the southern portion of my South Park 

region. In the section made at "station 53" the strata which probably belong to 

the Leadville consist of a grayish-blue limestone, from which were obtained &this, 

Productus, and Orthoceras, followed by shales of a gray and brown color, more 

sandy above, which are in turn overlain by a series of heavy strata of dark-blue 

limestones. The lower limestone rests upon quartzites and variegated shales, which 

I refer to the Parting quartzite. The fauna mentioned suggest8 the Devonian fauna 

of the Ouray limestone or the Mississippian fauna of the Leadville horizon. The 

upper limestone is followed by a brown sandstone, which is apparently the Maroon 

.or Arkansas sandstone. In this case the Weber limestone or shale is wanting, unless 

the upper limestone represents it instead of the Leadville. In the section made at 

"station 56" the Leadville probably comprises a series of blue limestones irregularly 

alternating with gray shales containing Orthis and crinoids. Bluish shales follow, 

and are covered in turn by a gray saccharoidal limestone. Beneath the lower limestone are found the quartzites and shales of the Parting formation, while above 

the upper one comes in a series of red sandstones, which I take to be the Arkansas 

sandstone and equivalent to the brown sandstone of the previous section. In the 

two sections just discussed, as well as in that from Fossil Ridge quoted previously, 

the beds referredlo the Leadville formation consist of two limestones separated by 

shales, but the corresponding members of each series do not agree especially well 

with each other in lithologic detail. At Fossil Ridge the upper limestone is over-
166 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

lain by shales and other limestones and contains a fauna which I have little doubt 

correlates it with the Leadville and Ouray limestones. In the two South Park sections no transitional or intermediate series is mentioned above the upper limestone, 

and the diagnostic fossils, so far as they are diagnostic at all, are reported only from 

the lower member, so that if the Weber formation is present it would probably 

embrace some of the beds tentatively placed with the Leadviile formation. In the 

other case the change of the Leadville, which farther north appears to be a homogeneous limestone series, to two limestones with an interbedded shale is worthy of 

note. 

Though the older Paleozoics whose distribution the Leadville limestone closely 

follows, are said by Endlich to occur for a short distance south of the Arkansas, and 

the " Lower Carboniferous " color appears in the Hayden atlas in the north end of 

the Sangre de Cristo Range, the Mississippian limestone is wanting over most of the 

region. We have, however, no description of its occurrence at its northern localities. 

The Hayden atlas also represents a small area of Lower Carboniferous at Trinchera 

Peak, and this Endlich describes as a grayish-brown, compact shale, sandy in part, 

and interbedddd with limestone, and conformably underlying the red Carboniferous 

sandstone. He suggests that this may represent the Lower Carboniferous. There 

really seems to be no evidence sufficient to determine whether it is the Leadville 

series (though from the lithology this hardly seems likely), the Weber formation, or 

part of the Arkansas sandstone.a Lee has recently examined part of the area where 

Lower Carboniferous is represented on the map and found only the Arkansas sandstone, from which the inference may be drawn either that the limits of the area are 

incorrectly represented on the map, or that Endlich erred in separating these beds 

from the younger formation. Stevenson describes no formation older than the 

Arkansas sandstone south of the river, and if he met with any occurrences he presumably included them in the Pennsylvanian. While these formations pinch out and 

disappear south of the Arkansas it is possible that they may occur in local patches 

beneath the sandstone. The somewhat doubtful occurrence of the Leadville limestone 

at Trinchera Peak, and the appearance of the Sawatch quartzite and the Yule limestone northeast of San Luis, reported by the Van Diests, indicate that other similar 

instances may exist. 

The equivalent of this formation in the Uinta Mountains is well-nigh as uncertain as that of the earlier Paleozoic beds. It can be correlated with the lower portion 

of the Wasatch limestone of Utah and with the Red Wall limestone of the Grand 

Canyon country, the lower portion of which belongs in the Mississippian, as Meek, 

Walcott, and Frech report. Though Meek's reference was made with hesitation, and 

a The strata above the Archean in Lee's section have more the character of the Maroon than of the Weber limestone, 

which is absent or has lost its calcareous character. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 167 

several circumstances unite to cast suspicion upon the Mississippian determination 

for the Red Wall, collections of fossils more recently made demonstrate that the 

lower portion at least belongs to that epoch. The Pennsylvanian age of the upper 

portion, however, is unmistakably shown by the faunal list supplied by Meek, and 

since the upper Mississippian is usually missing in the western sections, owing to 

Pennsylvanian erosion (or possibly to nondeposition), it seems probable that the 

formation is divided by an unconformity otherwise undetected. Furthermore, Powell 

claims to have traced the Red Wall into the Uinta Mountains, where, both by its 

somewhat ambiguous fauna a and by its stratigraphic position above the Uinta sand-. 

stone, which Emmons correlates by tracing with the Weber quartzite, whose Pennsylvanian age throughout is satisfactorily known, it belongs, with little doubt, in the 

Upper Carboniferous. If the Leadville limestone occurs in the Uinta Mountains it 

must be as one of the siliceous beds of the Uinta sandstone and not as the Red Wall 

limestone as identified by. Powell; but since this horizon is so persistently characterized by its calcareous nature it seems somewhat more probable that Mississippian 

time is unrepresented in the Uinta series of rocks. 

Along the eastern margin of the Front Range the Mississippian limestones. appear in several places. It is in this tract called the Millsap limestone. The Millsap limestone was first described in the Pikes Peak folio, from which I abstract the 

following: It consists only of local remnants resting upon the Fremont limestone in 

Garden Park and along the western line toward Canyon. It is represented by about 

30 feet of thinly bedded, variegated, dolomitic limestone, with a few thin sandstone 

montanus 

it. These sections have already been referred to, as the sandstones in the loWer 

is found also at Perry Park, where both Peale and Lee have made sections including 

preceded and that which followed it by an erosional unconformity. This formation 

layers. Chert nodules in the upper limestone layers carry casts of 

and Seminula subtilita. It is divided from both the formation which 

Spirifer rockyportion, though assigned by both authors to the Carboniferous,' may yet prove 

to be Cambrian. Peale's section includes the following beds: 1. Granite; 2. Very 

coarse white sandstone, 80 feet; 3. Red calcareous sandstone, 4 feet; 4. Dark 

purplish cherty limestone, 3 feet; 5. Compact red sandstone in layers of 1 foot 

thickness, with cross seams of calcite, 15 feet; 6. Red calcareous sandstone, very 

hard and with cross cleavage layers of 1 inch, 3 feet; 7. Irregular limestone, with 

pebbles of greenish chert and limestone, 3 feet; 8. Indistinct outcrop of limestone, 

with chert pebbles and fossiliferous—in the upper part of the space a purplish 

sandstone, above which is, a gray sandstone passing into the next bed-6 feet. Peale 

says (p. 198): "The fossils found in No. 8 (Terebratula and Spiriferina) prove it to 

be Carboniferous beyond a doubt." This stratum, which probably belongs to the 

a Found not in the Uinta Mountains proper, but south of them, in eastern Utah. 

U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, p. 197. 
168 - CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Millsap limestone, is overlain by the Red Beds. With No. 8 will probably go No. 7, 

and possibly also 6, 5, and 4, though it seems to me rather probable, by analogy with 

neighboring sections, that 2 and 3 at least are pre-Carboniferous and represent the 

Cambrian. No. 1 also suggests the Harding sandstone of the Pueblo quadrangle. 

The beds which Lee refers to the Carboniferous have at the base 40 feet of 

coarse, green, crumbling sandstone, conglomeratic in places, and mottled in varying 

shades of red and gray. Above this sandstone appear 10 to 15 feet of deep-red to 

white cherty limestones alternating with red shales. Near the top of this series 

Carboniferous fossils were obtained. Above these occur several hundred feet of 

coarse-grained sandstones and conglomerates, which appear to be perfectly conformable with the fossiliferous series. It is clear that the siliceous series last referred to 

is not a part of the Millsap limestone, but probably represents a portion of the Fountain beds above. The sandstones at the base probably correspond to those mentioned 

by Peale, which I have referred, upon somewhat doubtful evidence, to the Cambrian. 

The Millsap limestone, then, would embrace merely the small thickness of cherty 

limestone in the middle of Lee's Carboniferous. It seems probable from these sections that the Millsap, small as is its thickness in Garden Park, in the Pikes Peak 

quadrangle, is still further reduced in Perry Park. 

The Millsap is apparently absent in Manitou Park, the Fountain beds coming 

down upon the Ordovician; but at Glen Erie,a near Colorado Springs, the whole or 

part of a series of gray, purplish, and yellow limestoneS, 279 feet in thickness, may 

belong to it. Mr. A. W. Grabau informs me that he has collected a Carboniferous 

fauna from the upper portion. Beneath this bed occur red shalt' limestones with 

Ordovician fossils (the Manitou limestone), and above it the Red Beds. 

Some beds belonging to the Millsap limestone are apparently included by 

Walcott in a section which he •describes from Harding's quarry, near Canyon. 

Here it is reported as 15 to 30 feet in thickness, and as consisting of impure, variegated, banded limestone, with interbedded argillaceous beds. 

tanus 

consists of gray and purple limestone, with some shale, especially in the lower part. 

Gilbert recognized the Millsap limestone in the Pueblo quadrangle, where it 

and Seminula subtilita are cited. 

$_pirifer rockymonThese strata are 200 feet thick, and are said to rest conformably upon the Harding 

sandstone. Near the middle was found S.

pirifer rockymontanus, a species which

is cited from the typical exposures in Garden Park. It seems probable, therefore, that the upper part of Gilbert's Millsap is correctly correlated. As at the 

nearest outcrops of these formations, viz, those at Canyon, the Harding sandstone 

is followed by 270 feet of Fremont limestone and but. 15 to 30 feet of Millsap, it is a 

little unexpected to find that the thick Fremont has vanished, and that the Millsap 

a U. S. Geol. Geog. Surv. Terr., [Seventhi Ann. Rept., for 1873, 1874, p. 201. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 169 

has increased to ten times its bulk. It thus seems possible that the lower portion of 

this series in the Pueblo quadrangle may, represent the Fremont, though satisfactory 

evidence upon this point is lacking, while Cross's remarks upon the restricted distribution of the Fremont should be borne in mind. In any event the Millsap is 

greatly increased in thickness from its Garden Park and Canyon outcrops. 

Endlich also recognized the Paleozoic nature of these beds, and they are represented on the Hayden maps as an area of Lower Carboniferous, part of which .is 

included in the Pueblo quadrangle. Endlich described them as consisting of. grayish limestones and shales, and apparently his observation relates to the Millsap limestone alone, without including the Harding sandstone which lies beneath. 

In the San Juan region Mississippian time is represented by the Ouray limestone, 

the major portion of the formation, however, containing a Devonian fauna. 

The Ouray limestone is. defined by Cross and Spencer somewhat as follows: It 

consists of massive beds of limestone separated by thin intercalations of marl or 

shale. Certain thin bands are frequently quite coarsely crystalline, but the large 

mass of the formation is a dense or semicrystalline limestone. The thickness is 

about 150 feet. The greater part of this formation appears to be of Devonian age, 

and it was only comparatively recently that a Mississippian fauna was obtained from 

its upper portion. The latter is intimately related to the Mississippian faunas at 

Leadville and Aspen, and also to the Waverly fauna of the Wasatch limestone of 

Utah, the Madison limestone of Wyoming and Montana, the typical Waverly of 

Ohio, and the Chouteau limestone of Missouri. The fauna of the Millsap limestone, 

as we know it from Perry Park and also from Garden Park and Canyon, and that 

of the Leadville limestone at Leadville, present a rather peculiar facies, but even 

this fauna seems to be related to those of the early Mississippian, and it is somewhat singular that the Leadville fauna is more nearly allied to that of Perry and 

Garden parks, while lithologically and stratigraphically -the Leadville as a formation 

is especially to be compared with the Leadville of Aspen and of the Crested Butte 

region. I think we can safely regard these faunas as varying facies of a single widespread and contemporaneous fauna, the differences being due in part to varying 

environmental conditions and in part to quite a different cause. Our collections 

from these beds are extremely meager, and to this circumstance can be referred 

some of the differences at present existing. 

The Lower Carboniferous of the Hayden survey geologists consists in the main 

of this bed, though it is doubtful if they were consistent throughout in recognizing 

its limits. With them also the term was used rather as meaning the lower portion 

of the local Carboniferous section than in its strict paleontological sense as the 

equivalent of Mississippian. In this sense apparently the term is used in the 

Leadville monograph, where the Leadville limestone is referred to the Lower 
170 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Carboniferous. Walcott in his Canyon section, Cross in the Pikes Peak folio, and 

Gilbert in the Pueblo folio refer the Millsap limestone to the Carboniferous merely, 

without being sure to what portion of the system it belonged. Lee, in discussing 

the Pikes Peak section, uses my determination of the age of the Millsap. Emmons 

in the Tenmile folio, Eldridge in the Anthracite-Crested Butte folio, and apparently 

Spurr in the Aspen monograph, refer the Leadville limestone to the Lower 

Carboniferous in its true sense as a division of the geologic time scale. Peale in his 

Eagle River section seems to be uncertain whether the, corresponding beds were 

Carboniferous or Devonian. Cross and Spencer refer the Ouray limestone to the 

Devonian, because a Devonian and no Carboniferous fauna was known from it at 

the time of their writing. It is now fairly certain that the Carboniferous portion 

of the Leadville, Ouray, and Millsap limestones are of early Mississippian age. 

This formation, or, as it has received several names, this horizon, is widely 

distributed in Colorado. It is known in the Grand River region (the Devonian 

portion has been recognized on the White River and at Glenwood Springs and the 

Carboniferous probably on Eagle River), in the Elk Mountain region, in the South 

Park region, in the northern part of the Sangre de Cristo Range, in the San Juan 

region, and along the Front Range. It is probably lacking over much of the Front 

Range and Sangre de Cristo areas, in the Uinta Mountains, and in the valleys of 

the Dolores and the Grand, and it is concealed over extensive areas by deposits 

of later geologic age; but it is perhaps the most widespread of all the Paleozoic 

formations except those belonging to the Pennsylvanian. The remarkable persistency 

of this horizon as a limestone formation, not only in Colorado but throughout the 

West, and the widespread distribution of essentially the same fauna, would argue 

extended and uniform marine conditions during Mississippian time. Whatever may 

have been the conditions prior to the formation of the Leadville limestone, I believe 

that there were no land areas in Colorado during the Leadville epoch. Aside from 

the persistency of the fauna and the lack of anything like shore deposits at this 

horizon, the fact that the Leadville nowhere, so far as I have read, lies upon the 

Archean is evidence in point. As the Leadville period was one of subsidence, had 

there been permanent Archean land areas deposits could hardly have failed to be 

laid down upon some of the submerged land. The possibility that the waters 

advanced only so as to fall short of at all points, or not to transgress, some former 

level does not need serious consideration. On the other hand, I do not see that the 

sedimentation of Leadville beds upon the Archean, even if it does occur, would 

necessarily be evidence in favor of permanent Archean land masses in Colorado. 

PENNSYLVANIAN. 

The Lower Carboniferous period was followed by an epoch of elevation and 

erosion. At all events none but the early portion of Mississippian time is 
RECAPITULATION OF PALEOZOIC FORMATIONS. 171 

apparently represented in the Colorado sediments. The chronological point at 

which this elevation took place is, except in a general way, unknown. It may 

have occurred soon after the formation of the Leadville limestone, the absence of the 

upper Mississippian horizons being due not so much to erosion as to nondeposition; 

but it seems to me rather more probable that this episode was nearly contemporaneous 

with the elevation in eastern North America at the close of Mississippian time. That 

the elevation is of wide extent is indicated by the absence over such large areas in 

our Western States of upper Mississippian faunas. To the erosion which resulted 

from this elevation the variation in thickness of the Leadville limestone in different 

sections can often be ascribed. When subsidence again permitted the formation of . 

sediments, the earliest deposits were frequently of a less purely marine character, 

and shortly a great thickness of sands and conglomerates intermingled with nonpersistent limestone bands began to form over great areas in the State. 

The Paleozoic section of central Colorado, by which term I would include the 

Grand Rive'', Elk Mountain, and South Park areas, is singularly uniform, and this 

is scarcely less true of the strata of Carboniferous age than of the earlier Paleozoics. 

Though these are fairly constant in lithologic characters, the nomenclature employed 

for them has varied somewhat. Thus in the Anthracite-Crested Butte folio the 

Carboniferous formations are called the Leadville limestone, Weber limestone, and 

Maroon conglomerate; in the Aspen monograph, the Leadville limestone, Weber 

formation, Maroon formation, and the Triassic;a in the Tenmile folio, the Leadville 

limestone, Weber shale, Weber grits, Maroon formation, and Wyoming formation;a 

and in the Leadville monograph, the Blue limestone, Weber shale, Weber grits, and 

Upper Coal Measures. 

The distribution of the Leadville limestone has already been described. While 

the general equivalence of the Upper Carboniferous formations of this area is 

comparatively easy to ascertain, their relations to the different formations of the 

regions adjacent, of the Uinta Mountains, of the Front Range, of the Sangre de 

Cristo Range, and of the San Juan region are questions of more intricacy, and it 

will not be possible to consider each formation by itself, but in relation to the other 

Pennsylvanian formations of the same section. 

In the Crested Butte quadrangle the beds immediately overlying the Leadville 

limestone are called the Weber formation, and they are succeeded by the Maroon 

formation. The Weber formation apparently derives its name from the Weber 

quartzite of the Wasatch Mountains of Utah. I shall refer to this point again, but 

it seems that the correctness of the correlation suggested by the nomenclature is very 

doubtful and that the employment of the term Weber for formations in Colorado 

can not with propriety be continued. The Weber formation consists principally of 

a I do not of course mean to imply that the Triassic of the Aspen district and the Wyoming formation are Carboniferous 

formations, but I desire to consider them in connection with the Carboniferous and to compare their nomenclature. 
 

172 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

dark carbonaceous and calcareous shales and thin limestones. The thickness varies 

from 100 to 550 feet, a range of measurement which is accounted for by Eldridge by 

the fact that it follows a marked unconformity. Its fossils are abundant, and of the 

Coal Measures type. The Maroon conglomerate is taken to begin with thin beds of 

calcareous grits different from the constituents of the Weber formation, and to end 

with " the unconformity overlying the Gunnison sandstone," though in this last 

statement " overlying" is clearly a misprint for underlying. The maximum thickness is thus 4,500 feet. A lower and an upper division of the formation are recognized.. "The lower division is an alternating series of yellowish-gray grits, thin 

limestones, and shale beds, reaching 2,000 feet in thickness in their greatest development along lower Cement Creek. The grits consist of grains and pebbles of quartz 

and limestone, with a calcareous and somewhat ferruginous'cement." The limestone 

pebbles vary in size up to 3 or 4 inches, and frequently contain Coal Measures fossils. 

This occurrence of Upper Carboniferous fossils in pebbles in the Maroon conglomerate is an important and well-established fact. Station 2306, near Cement Creek, 

in our collections, seems to be an instance of this association, and the fauna, it will 

be seen, is clearly a Pennsylvanian one. It is somewhat unexpected that the fauna 

of these pebbles is the native Maroon fauna and not that of the eroded Leadville 

limestone or Of the Weber formation. The limestones of the lower division occur 

in beds from 1. to 15 feet thick, are of bluish-gray color, and are frequently fossiliferous. The upper division, which has a maximum thickness of about 2,500 feet, is 

composed of alternating beds of conglomerate and sandstone, with some shales and 

occasional limestone beds. The pebbles of the conglomerate consist largely of red 

gra-nite and schist from the Archean areas, with representatives of quartzites and 

limestones of the older sediments. The upper division is of a peculiar red or 

chocolate color. It is found in greatest thickness in the northern part of the 

Crested Butte quadrangle, and is very greatly decreased in the southern portion. 

In the Aspen district the Weber formation consists of a series of thin-bedded 

carbonaceous limestones and calcareous shales. The typical rock is a black limestone, 

thin bedded, and aphanitic. The maximum thickness is reported at not much less 

than 1,000 feet. "Above the Weber formation comes a 'great thickness of mixed 

arenaceous and calcareous sediments forming impure grits and thin-bedded shaly 

limestones. This formation is calcareous and thin bedded at first, but becomes more 

massive and arenaceous farther up. The general color is a peculiar dark red 

* * *." a "The purplish-red beds pass upward into more massive and fine-grained 

sandstones which are more purely siliceous in composition and of a bright brick-red 

color." "The change to these Red Beds, however, is not abrupt, and does not indicate any break in the sedimentation." There is a basal gray bed of the. Maroon 

a U. S. Geol. Surv., Mon.; vol. 31, p. 33. b Ibid, p. 34. . 
RECAPITULATION OF PALEOZOIC FORMATIONS. 173 

formation (which in this district is not very conglomeratic) of about 200 feet in 

thickness, the remainder being a dark reddish-brown, impure, micaceous sandstone. 

The gray grits of this formation are made up almost wholly of granitic material, quartz, 

feldspar, and mica. The red sandstones are ferruginous and contain more calcareous 

and less granitic material. Spurr assigns to the Maroon formation a thickness of 

4,000 feet, and to the brick-red sandstone overlying a thickness of 2,600 feet. 

The relation between the sections described by Spurr from about Aspen and that 

of the Crested Butte quadrangle is not absolutely clear, although geographically the 

two areas are not widely separated. The Weber formation of the Aspen district 

appears to answer to the Weber formation of the Crested Butte quadrangle, though 

at Aspen its thickness is double what it seems to be in the Crested Butte quadrangle. 

The Maroon formation appears in the Aspen district with characters considerably 

changed. These seem to persist more uniformly throughout the series, in such a 

manner that it no longer can be divided into two members, as in the Crested Butte 

quadrangle. There it is Conglomeratic, especially -in the upper portion; but this 

character seems to be largely lost in the Aspen district. On the other hand, the 

dark-reddish color, which is one of the distinguishing characters of the upper member of the original Maroon, seems to pertain practically to the entire series about 

Aspen. The Maroon at Aspen graduates into a bright-red series, the Triassic of 

many authors, which appears to be unrepresented in the Crested Butte region. In 

the one case the Maroon formation, in the other the Trias, is overlain by the Gunnison formation, which. was preceded by an erosional unconformity. 

An argument might be constructed to show that the Maroon of Spurr represents 

only the upper member of the typical formation, but on the whole this seems -too 

improbable to require serious discussion. Unfortunately, the paleontologic evidence 

is not at hand to put these matters beyond dispute. 

While it is comparatively easy to see the general equivalence between Peale's 

Eagle River section and the groups of rocks distinguished in the later monographic 

and folio work, it is a little difficult to satisfactorily determine their corresponding 

boundaries. 

In the Crested Butte quadrangle the Maroon formation is terminated above by 

an unconformity, and immediately followed by the Gunnison formation, of Mesozoic 

age. In the Aspen section Spurr distinguished above the beds correlated with the. 

Maroon a series of bright-red sandstones referred to the Triassic. These are followed by an unconformity, and then by the supposed equivalent of the Gunnison 

-formation. The beds which Peale counts as Jurassic appear to be same as the Gunnison formation of Spurr, and the latter's Leadville, Weber, and Triassic formations 

would be comprised in the series lying between Peale's Silurian and Jurassic. 

These Peale discriminates as possible Devonian, Carboniferous, Permo-Carboniferous 
174 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

or Permian, and Triassic. Theye are one Devonian, one Carboniferous, two Permian, 

and one Triassic section, which it will be desirable to consider. The Devonian, Carboniferous, and one of the Permian sections form, with the Silurian, a single continuous series. The other Permian section is probably continuous with the Triassic 

and with one of the Jurassic sections, and was made at a different locality from the 

first. Instead of being equivalent, I think Peale's two Permian sections are much 

more likely to be nearly consecutive, the second being above the first, but overlapping, it may be, to some extent. I have quoted Peale's sections in full in another 

place, and discussed their relations. 

Above the beds which Peale refers to the Silurian occur black, flinty limestones 

with pieces of pyrite and fragments of Spinier or AS:pinferina. This is succeeded 

by a space probably filled mainly by limestones, the entire thickness being estimated at from 1,000 to 1,500 feet. The black, flinty limestone is without much 

doubt the Leadville limestone, but probably not the entire thickness can be assigned 

to that formation, which is only 350 feet thick at Aspen and. 200 feet thick in the 

Tenmile district. After an interruption of 15 feet of trachytic rock, the section 

proceeds in an upward direction, with a space of 408 feet filled mainly with shale 

and sandstone, and having a limestone at the base, from which some fossils were 

obtained that seemed to indicate Pennsylvanian time. Avieulopecten, Pleurophorus, 

and an Avieula or Bakewellia are cited. The middle or upper portion of this series 

of poorly exposed beds probably belongs with the Maroon formation. The limestone 

at the base, together with those below, would then represent the Leadville and 

Weber formations, so that the dividing line between the Leadville and the Weber 

and between the Weber and the Maroon formations can not be ascertained. At all 

events, the calcareous beds of the Leadville and the Weber at this locality must 

aggregate about 1,500 feet, more or less. This is more like the Aspen section, where 

these two formations amount to 1,350 feet, than the Tenmile district, where they 

only measure 500 feet. In Tilden's section at Red Cliff also they have a combined 

thickness of 1,550 feet. The remainder of the Carboniferous section above the portion supposed to represent the Leadville and Weber limestones amounts to about 

2,400 feet. The Permian section, which is continuous with it, is 1,276 feet 

thick. Together the two series comprise 3,676 feet, of about the same character 

of rock, and can safely be taken as part of the Maroon formation. The " Carboniferous" beds consist of greenish, brownish, white, gray, red, reddish-brown, 

and pink sandstones, which are sometimes conglomeratic and more or less 

intermingled with shaly beds. The Permian consists of gray sandstones and 

white conglomerate, with about 10 feet of blue limestone. The other Permian 

section consists of a lower portion 700 feet thick, which probably belongs in 

the Maroon conglomerate, and an upper portion 500 to 800 feet thick, which I think 
RECAPITULATION OF PALEOZOIC FORMATIONS. 175 

should be placed in the Red Beds. The lower division, which probably somewhat 

overlaps with the other Permian section but may follow it, with or without an interval, consists of pink, brown, and gray shaly standstone, with thin interlaminated 

beds of limestone below, followed by shales, sandstones, and limestones in alternating 

colors of pink, brown, gray, yellow, white, cream color, and blackish. With the 

addition of these strata the equivalent of the Maroon would have a thickness of 4,376 

feet, approximately, and with the characters above designated. This thickness is 

greater than that of the Maroon in the Aspen district, which Spurr places at 4,000 

feet, and less than the maximum thickness of the original Maroon, which measures 

4,500 feet. It is• possible, however, that in the latter measurement are included 

bodies of metamorphosed and no longer recognizable Triassic. The lithologic characters of Peale's series differ in detail from either the Aspen or the Crested Butte 

Maroon, and seem to be more like the Weber grits and Maroon series of the Tenmile and Leadville districts. The Maroon at Aspen seems to be nearly uniform 

throughout, to contain very little conglomerate, and to be of a dark brownish-red 

color. On Eagle River the conglomeratic bands appear to be more numerous, and 

while brownish and red beds occur, to consist mainly of grays. The original Maroon 

was divided into two approximately equal series, the upper of which was characterized by being a conglomerate and possessing a dark maroon color. On Eagle River 

beds of conglomerate and others of deep-red color occur, but instead of being segregated in the upper portion of the section, are distributed through it. The upper 

part of Peale's second Permian section, which I would unite with the "Triassic" as 

part of the Red Beds, is, as I have already said, from 500 to 800 feet in thickness, and 

consists of gypsiferous shale and sandstone having generally a pinkish or red color. 

The Triassic contains 978 feet, and consists of sandstone of red, pink, purplish, 

brown, white, and light colors, the red largely predominating. United these two 

series make up 1,478 to 1,778 feet of sediments, generally similar to Spurr's Triassic 

and to the Wyoming formation of the Tenmile district, the former of which measures 2,600 feet and the latter 1,500 feet. In Tilden's section at Battle Mountain, 

near Red Cliff, he found above the Leadville limestone 1,000 feet of Carboniferous 

limestone which would seem to be the equivalent of the Weber limestone and the 

Weber shales. In Peale's Eagle River section the Weber shale can hardly measure 

less than 1,000 feet, and at Aspen it measures 1,000. In the Crested Butte quadrangle, however, its thickness is from 100 to 550 feet, and in the Tenmile district it 

is only about 300 feet. 

Peale found no distinctive invertebrate fossils, save a few species already 

mentioned. In the case of his Permian series, the age assigned rests upon a few 

plants which Lesquereux identified as Calamites suckovii Brogn., Stigmaria ficoides, 

and Calamites gigas Brogn. Before accepting the Permian age of these beds, in 
176 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

view of somewhat conflicting evidence upon this point, I should desire to see these 

identifications corroborated, and also the additional evidence of a larger flora or 

fauna. 

Stevenson also describes a section, made on the forks of Eagle River, at nearly 

the same point at which that made by Peale was taken. At the base lies the 

Leadville limestone, some 200 feet above which is found a conglomerate 40 feet in 

thickness, followed immediately by 2,000 feet of sandstone, shale, and conglomerate, 

including gypsum beds. Reddish gray and yellow seem to be the prevailing colors. 

Then come in about 500 feet of sandstones interbedded with limestones, some of 

which contain Carboniferous fossils. The limestones are blue, and the sandstones 

reddish, gray, brown, etc. The upper member contains 2,500 feet of coarse sandstone, mostly of reddish-gray color and entirely without limestones and shales. It 

is this member of the section to which Stevenson later compares the upper portion 

of the Arkansas sandstone in the Sangre de Cristo Range. Stevenson apparently 

did not observe the series which is called by Peale Triassic, and for which the local 

name, Wyoming formation, is employed in the Tenmile district. No beds similar in 

position and lithology to the Weber shales or limestone can be discerned in this 

section unless the space of 200 feet at the base contains them. All these strata, 

therefore, would appear to belong to the Maroon formation of the Crested Butte 

district or the Weber grits and Maroon of the Tenmile district. The peculiarities 

of this section, among Which may be mentioned the segregation of the limestones 

near the middle, the gypsiferous nature of the lower portion and the character and 

coarseness of its conglomerate beds, and the dark color of the upper portion which 

is compared with beds in the Sangre de Cristo having a reddish-brown tint, are 

probably not to be found together in any one of the described. sections, and illustrate 

the great variability in detail of this series from point to point. 

In the Tenmile district the Upper Carboniferous formations discriminated by 

Emmons are the Weber and Maroon; the Wyoming formation, above, is placed in the 

Trias. Of the Weber formation he recognizes two divisions, the'Weber shales and 

the Weber grits. The Weber shales, which appear to be the equivalent of the Weber 

formation of the Anthracite-Crested Butte folio and the Aspen monograph, are 

described as consisting of argillaceous and calcareous shale alternating with quartzitic 

sandstones. Beds of impure limestone contain Coal Measure fossils. The thickness, 

which is very variable, is assumed to be about 300 feet. The Weber grits are part of 

the series elsewhere described under the name of Maroon conglomerate. The formation here distinguished by that name has an average thickness of about 2,500 feet. 

It consists mainly of coarse sandstones, or grits, often very micaceous, with a subordinate development of shales and a few thin and nonpersistent dolomitic limestones. 

The sandstones are generally light gray in color, and their prominent constituents 
RECAPITULATION OF PALEOZOIC FORMATIONS. 177 

are quartz and feldspar, evidently derived from the Archean. The Maroon formation 

consists predominantly of coarse gray and red sandstone, in some places passing into 

conglomerates, with many irregularly developed beds of limestone. The red color 

is more common than in the Weber grits, and results from iron. oxide in the ceme.nt, 

and not from the presence of pink feldspar. The limestones of the Maroon differ 

from those of the Weber in physical characters, and are generally nonmagnesian. 

The Maroon as here defined is limited by the Robinson limestone below and the 

Jacque Mountain limestone above. The Wyoming formation has a maximum 

thickness of 1,500 feet, consisting principally of sandstones of an intensely brick-red 

color, with a moderate development of thin shales, and with limestones generally 

absent. The sandstones are often coarse, sometimes conglomeratic, and composed 

mainly of Archean debris. Archean bowlders 2 feet in diameter are cited. 

The name "Wyoming formation" was first used in this connection in the Denver. 

Basin monograph,a and by its employment in the Tenmile district a correlation is 

suggested with the bright colored Red Beds which occur on the eastern flank of the 

Colorado range. Emmons says that this name was used for these beds "not because 

of any fossil evidence of their age that could be found, but because by their position 

and petrological character they most nearly correspond to the beds of this formation 

which elsewhere in the Rocky Mountain region have, on fossil evidence, been 

determined to be Triassic. If the Permian is represented in Colorado, the evidence 

of which appears to the writer as yet very uncertain, it would be included in these 

beds, which have evidently been deposited in direct and unbroken succession over 

the Upper Carboniferous." 

It can be admitted that the Weber shale of this section is the equivalent, in a 

general way at least, of the formation called by the same name at Aspen and in the 

Crested Butte region, and that the Weber grits and Maroon bear the same relation 

to the Maroon formation of the Crested Butte quadrangle and Aspen. The 

Wyoming formation appears to be the equivalent of the Triassic of the Aspen 

section. 

While in a general way this seems to be the appropriate correlation of the 

different sections, there appear to be certain discrepancies in the lithologic character 

of the beds correlated. For instance, the origin of the material of the Weber grits of 

the Tenmile district seems to be the Archean, while the lower part of the Maroon 

at Crested Butte is derived from the older sedimentary series. Also it appears that 

the Maroon series at Aspen and the upper portion of the Maroon in the Crested 

Butte quadrangle are characterized by a dark-reddish color, more than is the case in 

the Tenmile district. The Wyoming formation of the Tenmfie district appears to 

be more conglomeratic than the Trias of the Aspen section. Emmons states that 

a U. S. Geol. Surv., Mon., vol. 27, 1896, p. 81. 

14364—No.. 16-03 12 
178 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the Weber formation corresponds in a general way to the Weber quartzite of the 

Wasatch Mountain section and to the Lower Aubrey of the Colorado Canyon 

section" (Tenmile folio.) I have elsewhere stated more fully my own tentative 

correlation of these beds. The Weber grits, together with the Maroon formation, 

as defined by Emmons, which he seems to exclude from the correlations expressed 

above, I would assign to the .Uinta sandstone, which Emmons at an earlier date 

correlated with the Weber quartzite. According to my view the Aubrey sandstone 

is stratigraphically above the horizon of the Weber quartzite and its equivalents. 

The corresponding beds in the Leadville district bear the names of Weber shale, 

Weber grits, and Upper Coal Measures. The Weber grits are extremely variable 

in lithologic character and thickness, consisting of argillaceous and calcareous shales 

alternating with quartzitic sandstones. Impure limestones are sometimes developed, 

and they are abundantly fossiliferous. A large fauna of Upper Carboniferous 

species is cited in the Leadville monograph. The Weber grits, whose upper and 

lower limits are not sharply defined, have a thickness of 2,500 feet, and consist 

mainly of coarse sandstones, passing into conglomerates. The typical rock is a coarse 

white sandstone. A small Upper Carboniferous fauna is cited from a tolerably pure 

limestone occurring near the middle of the formation. The Upper Coal Measures 

are like the Weber grits, but in the Mosquito Range contain more calcareous and 

argillaceous beds (Tenmile folio). They consist of alternating calcareous and siliceous 

beds, the latter not being distinguishable from those of the Weber grits at the base, 

but passing upward into reddish sandstones, which in their turn are sometimes 

difficult to distinguish from the overlying red sandstones of the Trias. The lower 

limit is taken at the Robinson :imestone. The calcareous beds below the Robinson 

are all more or less dolomitic, while the Robinson limestone itself is a pure limestone. 

The upper sandstones of this group are distinguished from the overlying Triassic 

beds by a deeper color, approaching a venetian red, whereas in the latter the color 

is rather of a light brick red. A large fauna of Coal Measure type is known from 

this horizon. The corresponding formations in the Tenmile folio, which have already 

been briefly described, are too obvious to require special citation. In lithology and 

thickness there is a close correspondence. 

In the South Park region south of the Leadville district the Maroon formation 

seems to be continuously present, and still further to the south it forms the mass of 

the Sangre de Cristo Range in Colorado. its occurrences in this area have been 

described in a cursory manner by Stevenson and also by Endlich and Peale, but no 

detailed sections are given. It was in this connection that Endlich used the name 

Arkansas sandstone. 

While the persistence of the Leadville limestone has caused it to be often mentioned by those who have written of the geology of Colorado, the Maroon formation 
RECAPITULATION OF• PALEOZOIC FORMATIONS. 179 

is that to which most frequent reference has been made. It has seldom been described 

in detail save in the sections mentioned above, and to cite and comment upon all the 

references would be fatiguing and unprofitable. It is, however, seldom possible to 

recognize in these reconnaissance reports either the Weber formation as a distinct 

unit or the two divisions of the original Maroon, for one of which the name Weber 

grits was subsequently used. From facts brought out by the literature, some of 

which have been repeated here, it seems safe to infer that the Maroon formation, 

though differing somewhat in character from point to point, is persistent over the 

Elk Mountain, Grand River, and South .Park regions, being present wherever the 

horizon for it is brought to view. The Weber formation, however, much thinner 

than the Maroon and less prominent than the Leadville formation, can hardly be 

recognized outside of a few detailed sections. In Fossil Ridge 45 feet of .light shale, 

followed by 150 feet of light blue and yellow limestone and quartzite and 50 feet of 

•yellow, reddish, and whitish shales, may belong to this formation. They rest upon 

the Leadville. The occurrence of the Weber at Crested Butte, at Aspen, on Eagle 

River, at Red Cliff, and in the Tenmile and Leadvilie districts has already been 

described. South of Leadville I have not been able to identify it in the South Park 

region, though this is perhaps due to a lack of detailed information. If present, this 

series would probably contain the gypsum beds mentioned by Stevenson. In two 

sections described by Endlich it may be represented by part of the series which 

have been taken to belong to the Leadville limestone. This consists in the one case 

of gray and brown shale and dark-blue limestone, and in the other of bluish shale 

and gray saccharoidal limestone. 

The great mass of the Upper Carboniferous sandstones and conglomerates 

appears to have been at one time continuous over most of central Colorado, and its 

distribution is still very wide. These strata seem to be generally present over the 

Grand River region, the Elk Mountains, and the South Park region, and they form 

the mass of the Sangre de Cristo Range southward to Costillo Peak, near the 

southern border of the State. Several geologists have described their occurrence in 

this range, but records of detailed study are rare. Endlich gave to them the name 

of the Arkansas sandstone, though but little satisfaction can be obtained from his 

reports. At one point in the San Luis district he describes the Arkansas sandstone 

as over a mile in thickness, consisting of heavy beds of red sandstone more or less 

interstratified with dark-brown shale and containing isolated beds of limestone. In his 

Southeastern district it appears to be made up chiefly of red sandstone interstratified 

with red shale and blue limestone. Stevenson says but little of these strata as they 

appear in the northern part of the range, but describes in more detail their occurrence in the southern part, where he recognizes two series, both of which are 

included in the Carboniferous. The lower one has a total thickness of 3,727 
180 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

feet, and contains the following elements, beginning at the base: Conglomerate, 

with red sandstone and red shale, 800 feet; blue fossiliferous limestone, 7 feet; red 

shale and sandstone, 700 feet; blue unfossiliferous limestone, 20 feet exposed; red 

sandstone and reddish shale, 300 feet; gray limestone, richly fossiliferous, 100 feet; 

and reddish sandstone holding beds of red shale, 1,800 feet. The upper series is a 

reddish-brown conglomeratic sandstone not far from 2,500 feet thick. Large fragments of granite, gneiss, and quartzite prevail, but with, these are some of sandstone 

and limestone. "This part of the section bears close resemblance to the upper division of the Carboniferous series seen on the Eagle River of central Colorado."a 

The entire thickness of this series is 6,200 feet, distinctly greater than at any point 

at which measurements have elsewhere been made. 

Stevenson's comparison of the upper beds in the Sangre de Cristo with the upper 

division of the Carboniferous on Eagle River (=the upper Maroon?) is suggestive, 

and the two divisions distinguished in the Sangre de Cristo can be compared with* 

the two divisions of the Maroon formation in the Crested Butte district. This is 

especially true of the upper division, which measures the same in both areas, 2,500 

feet. The lower division in the Sangre de Cristo is much thicker. In the San Juan 

the upper division is reduced to 300 feet (Rico formation) and the lower to 1,800 

feet (Hermosa formation). In the Dolores River region, however, the upper 

division appears to be entirely absent, while the beds supposed to be equivalent to 

the lower division have about the same thickness as in the Sangre de Cristo, aggregating, according to Peale, 3,500 feet, to which possibly 300 more feet should be 

added from his Permian series. The fauna found by Lee near the base of Stevenson's lower division distinctly favors its correlation with the Hermosa and lower 

Maroon series. 

W. T. Lee has recently published a very detailed section embracing about 400 

feet at the bottom of the Arkansas sandstone. It was made on the east side of the 

range at a point directly west of Trinidad, near the southern end of a tract having 

its center at Trinchera Peak, which Endlich mapped as Lower Carboniferous. A 

horizon about 100 feet above the crystallines contains a well-marked Pennsylvanian 

fauna, and as no evidence of the Mississippian was found, nor any significant lithologic changes, there can be little doubt that the lowest beds at this point belong in 

the Upper Carboniferous. Lithologically the series described by Lee consists of 

numerous alternations of coarse red grits and sandstones, red and black shales, and 

limestones. The fauna collected by Lee presents points of individuality, but is 

distinctly that of the Hermosa formation in distinction from the Rico fauna. 

The Arkansas sandstone for the most part rests directly upon the Archean, the 

earlier Paleozoics probably having been lost by erosion prior to its deposition. 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Suppl. p. 74. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 181 

There can be no reasonable doubt of the absence of these strata in Lee's section, but 

as we have just seen, reputed Lower Carboniferous is 'mapped by Endlich about 

Trinchera Peak, while on the west side of the range, almost opposite where Lee's 

section was made, E. C. and P. H. Van Diest found the Sawatch quartzite and the 

Yule limestone in an area where the Arkansas sandstone is represented in the Hayden 

atlas. Lee cites Coal Measure fossils from several horizons near the base of the 

Arkansas sandstone, and fossils more or less diagnostic of the same age were reported 

by Hayden, Ruffner, Endlich, and Stevenson, the earliest as far back as 1869. The 

general resemblance to the Maroon formation, as it appears at other points in Colorado, of the series to which Endlich applied the name Arkansas sandstone in the 

Sangre de Cristo Mountains is apparent. It is to be remarked that in spite of the 

uniformity in general characteristics and the variability in details which this formation shows it seems generally divisible into two more or less equal portions. This 

has been done by Stevenson, as we have just seen, in the Crested Butte quadrangle 

and in the Tenmile and Leadville districts. Frequently the upper division seems to 

be characterized by a deeper red color than the lower, though when the lower has 

but little of a reddish tinge the upper does not show the same brownish red that 

appears where the lower is darker. The occurrence of coarse conglomerates derived 

from the Archean is. somewhat variable. Stevenson cites conglomerates of this 

character and origin from the upper division in the Sangre de Cristo Range and 

from the top of the lower division on the forks of Eagle River. In the Crested Butte 

district sediments of this type appear in the upper half of the Maroon, while in the 

Tenmile section they occur in the Wyoming sandstone. This circumstance suggests 

a consideration of the possibility of the Wyoming sandstone and its correlates 

being only local variations of the same large series. The great variability in detail, 

especially in color, of this series at different points would lend probability to such 

a supposition, and the fact that where the thickest sections of the Maroon occur 

(Crested Butte quadrangle and Sangre de Cristo Range) sediments of the Wyoming 

type are not found. On the other hand, the very general change of tint to beds distinguished by distinctly brick-red color, the overlap of these beds upon the Archean 

(as along the Front Range and in the Dolores Valley), and the marked faunal break 

which sometimes. occurs (as in the San Juan region) between the brick-red series and 

the underlying Carboniferous strata, seem to indicate that this is a distinct group. 

Stevenson's comparison of the upper series of the Sangre de Cristo Range with the 

upper portion of the Eagle River series is interesting, because the Eagle River beds 

appear to belong to the Maroon conglomerate and to occur below the horizon of the 

Wyoming sandstone. 

Except for rare patches of older Paleozoic beds and the occasional overlapping 

of sediments of later deposition, the strata lying next to the granite and almost con-
182 CARBONIFEROUS FORMATIONS. AND FAUNAS OF COLORADO. 

tinuously exposed from the Wyoming line southward to the Greenhorn Mountains 

belong to the well-known Rocky Mountain Red Beds. These have usually been 

referred to the Triassic, but occasionally the lower portion has been called Carboniferous. The evidence in either case is for the most part indirect, remote, and unsatisfactory. It would hardly be worth while to quote every opinion which has been 

expressed as to the age of the Red Beds of the Front Range in Colorado or to 

recapitulate all the terms in which these strata have been described, but some of the 

more important evidence and some of the more significant sections will be repeated 

in the pages following. 

Except for the Sangre de Cristo Range, which is composed largely of Carboniferous sandstones and conglomerates, the only areas of Carboniferous beds represented upon the Hayden atlas along the mountain front from the north to the south 

line of the State consist of five small disconnected areas. One of these is on the 

Wyoming line, another is in Pleasant or Perry Park, a third in Manitou Park, a 

fourth in the Garden of the Gods, and the last in the Wet Mountains southwest of 

Pueblo. That near the north line and that in Perry Park is Upper Carboniferous; 

in Manitou Park and southwest of Pueblo, Lower Carboniferous, while in the Garden 

of the Gods both Lower and Upper Carboniferous seem to occur. 

King recognizes three series in the Red Beds as 'they appear upturned on the 

flanks of the Front Range in Wyoming and in northern Colorado. On the east side 

of the range the lower division is composed of red limestone and reddish sandstone, 

and has a thickness of about 150 feet. It contains no fossils, but is regarded by 

King as representing all of Paleozoic time prior to the Carboniferous, and he correlates it with the Primordial of. the Black Hills, which it resembles lithologically and 

which has a similar stratigraphic position. 

Above this series follows one composed chiefly of limestone and having a thickness of about 700 feet. The limestones are blue, gray, and red in color, siliceous 

and sandy, and more or less interstratified with sandstones and conglomerates. They 

contain fossil shells which show the geologic age to be Pennsylvanian. These strata 

in several ways suggest the Rico formation of the San Juan region. 

Upon these rests the Triassic. Of this series King says: "Taken as a whole, 

and with the exception of the gypsum and limestone beds, which nowhere within 

our field of observation exceed 40 feet in thickness, it is essentially a sandstone 

series, for both clays and shales are exceedingly arenaceous, and the dominant 

color is a brick red for the lower half of the series and variable lighter reds, pinks, 

and yellowish reds for the upper half. While this division of color holds good in 

general, it is often varied by extremely brick-red, almost vermilion-colored beds 

appearing near the top, and light ones intercalated in the region of the heavy red 

lower strata." The thickness of this series is from 300 to 850 feet. It rests with 
RECAPITULATION OF PALEOZOIC FORMATIONS. 183 

apparent conformity upon the Carboniferous, but makes a striking overlap upon the 

Archean. No fossils occur in it except obscure and ill-preserved fragments of wood. 

On the west side of the range these beds appear with somewhat increased 

thickness. The Paleozoic series measures 1,200 feet instead of 850, Carboniferous 

fossils occurring 200 feet above the base. 

Too much importance need not attach, in the ease of the lower division, to King's 

correlation with the Black Hills Primordial, and as there appears to be really no 

satisfactory evidence for distinguishing the lower series from that above, it seems 

best for the time being to assign both to! the Upper Carboniferous. The striking 

overlap of the Triassic sediments, however, would seem to sanction their recognition 

as distinct from the Carboniferous. In the Laramie quadrangle an overlap of this 

sort occurs, which according to Knight is only apparent, the lower beds of the 

Triassic which lie next the granite being continuous with the Carboniferous farther 

north. It is possible that other supposed cases of overlap may find a similar 

explanation, but without doubt some are real. 

The Paleozoic series does not, upon the west side of the range, extend into 

Colorado territory, but its outcrop upon the east side reaches a short distance into 

the State. It, is with little doubt these beds that are represented in the Hayden atlas 

near the Wyoming line, and as they appear under the Carboniferous color without 

any Silurian intervening between them arid the granite, it would seem that Hayden 

also did not recognize King's lower series as older than the Coal Measures. 

Marvine examined the Red Beds in the northern part of the Front Range 

region, and describes them as varying in thickness from 1,600 or 2,000 to 400 feet, 

and consisting of red sandstones. The texture varies from coarse grits and moderately coarse sandstones, with fine examples of cross bedding, to quite fine-grained 

and shaly layers, which occasionally make up a considerable thickness. The conglomerates are mostly confined to near the base, where they are plainly derived from 

the subjacent rock. Dark red is the preailing color, though light red, yellow, and 

cream-colored beds are frequent, and may in places predominate. 

These rocks, which rest upon the granite, Marvine refers, as was customary, to 

the Triassic, and probably they are, for the most part at least, the equivalent of 

King's Triassic, the Paleozoic series being concealed by overlap. In some of the 

thicker sections, however, I suspect that carboniferous beds are present. 

Part of the area examined by Marvine forms the subject of the detailed work 

by Emmons, Cross, and Eldridge, the results of which appeared as the Denver Basin 

monograph. 

To the Red Beds series as it occurs in the Denver Basin, Emmons, Cross, and 

Eldridge give the name Wyoming formation. They describe it as consisting of 

brilliant red conglomerates, sandstones, and shales, with thin limestones and gypsum 
184 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

in the upper part. The thickness varies from 500 to 3,000 feet, but is generally 

somewhat under 1,500 feet. The formation is separable about midway into a lower 

division of soft, friable conglomerates and coarse, sandstones, with few shales, and 

an upper one of shales, with some prominent sandstone bands, narrow beds of 

limestone, and small local deposits of gypsum. The lower 5 to 20 feet of the Red 

Beds is nearly everywhere composed of coarse, subangular fragments of the adjacent 

granites, gneisses, and schists, with a small admixture of their derived sand, which 

shades in places to a red, arenaceous mud. Succeeding this formation is a series of 

heavily bedded sandstones and grits, with small local beds of arenaceous shale. The 

normal thickness is about 1,200 feet. The color varies from prevailing red to gray, 

according as the chief constituent of the rock is red feldspar or quartz. The lower 

200 feet of sediments are generally coarser and less compact than those overlying. 

These pass, by a broad transitional zone of lighter red sandstones, to the upper member of the lower division, a bed of creamy white sandstone from 200 to 400 feet 

thick. It contains impure limestones and some conglomeratic layers. The lower 

half of the upper division consists of bright brick-red arenaceous shales and sandstones, with important intercalations of limestone. The strata above the limestone 

series become more and more arenaceous, though still retaining in large degree 

their shaly nature. At 150 or 200 feet below the top of the Trias the strata become 

more clayey, and take on a variety of irregularly distributed bright colors—gray, 

yellow, red, green, pink, and lilac. In this zone gypsum and brown earthy limestones are common. The Trias usually closes with a sandstone from 15 to 25 feet 

thick. The Wyoming formation is overlaid by the Morrison formation, the former 

being assigned to the Triassic and the latter to the Jurassic period. The Wyoming 

is supposed to overlie the Fountain formation, by which name Cross designates the 

lower portion of the Red Beds in the Pikes Peak quadrangle, but it has suggested 

itself to me that probably a part of the Wyoming formation may locally be equivalent to the Maroon. The great variability of the lower member, the lower half of 

which ranges from 270 feet to 2,000 feet, might be taken as evidence that at the 

points of greatest thickness the lowest beds belong to a different and older formation. 

The lithology of the lower division is not unlike that of the Maroon, while it is only 

the upper division which is described as being brick red. Emmons offers a similar 

suggestion, on page 19 of the monograph. No fossils were found in the Wyoming 

formation and the evidence for assigning it to the Trias is more or less unsatisfactory. In the Morrison, however, remains of Jurassic dinosaurs occur. 

In a paper read before the Geological Society of America, but never published, 

save by abstract, N. H. Darton recognizes in the fine section at Morrison a limestone 

which he identifies with the Minnekahta limestone of the Black Hills, "having," he 

says, "precisely similar stratigraphic relations in the Red Beds and containing some 
RECAPITULATION OF PALEOZOIC FORMATIONS. 185 

of the same Permian fossils, although these are scarce and not well preserved." 

Darton does not state more specifically the species found at Morrison, nor have the 

fossils themselves come to hand. He obtained from the same horizon at Lyons, 

farther north, however, a hand specimen containing more or less indistinct impressions of a gasteropod and a pelecypod. The former is very small and has the general 

appearance of a Natica or Naticopsis, but may be something quite different. The 

pelecypod is also small, oblong, and transverse, having somewhat the shape of a 

small Plearophoras, but in this case also the generic position is indeterminable. 

Taken by itself this fauna is altogether negative as to the question under consideration, while a comparison with the fauna of the Minnekahta limestone of the Black 

Hills is almost equally inconclusive. It would be unsafe to say that neither of the 

species from Colorado occurs in the Black Hills, but the gasteropod has not yet been 

found there, and though I should be unwilling to state definitely that the pelecypod 

is different from some ill-preserved forms among the Black Hills fossils, I believe 

that it is not the same. For the present, therefore, it will probably be best to regard 

the paleontological evidence as nil. Reduced to a proposition of identification of 

horizon by means of tracing lithologic character and stratigraphic position, the 

correlation may be accepted with caution. 

The area south of that examined by Marvine was the subject of Peale's report 

for 1873. Peale gives no general description of the Red Beds and attempts no 

classification, save by calling the lower portion Triassic, with a Jurassic series overlying. The Triassic beds, which are in a general way the equivalent of the typical 

Wyoming formation, especially with the upper portion of the thicker and all of the 

thinner sections, consist mainly of red, pink, and white sandstones, and are represented upon the Hayden atlas as continuous from the South Platte, where Peale's 

district begins, to Perry Park. Between Perry Park and Colorado Springs they are 

concealed by overlap of later sediments, while in the vicinity of Colorado Springs 

and in Manitou Park areas of greater or less extent are represented. The Triassic 

beds appear to be for the most part in direct contact with the Archean, but at Perry 

Park, Manitou Park, and Colorado Springs areas of Carboniferous and in some 

cases Silurian strata are represented as underlying them. While the Triassic apparently consists mainly of sandstones, the Jurassic comprises for the most part limestones and shales, and probably is the equivalent more or less precisely of the 

Morrison formation. 

The Hayden atlas represents Upper Carboniferous sediments as intervening 

between the granite and Triassic in Perry Park. As I have already shown, the limestone described by both Peale and Lee as lying near the base of the sedimentary 

series in Perry Park carries Mississippian fossils and is to be correlated with the 

Millsap limestone. The sandstone beneath it I think may possibly be Cambrian. It 
186 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

is these beds which are represented under the Upper Carboniferous color in the atlas, 

and possibly some of the Red Beds above are included with them. Peale, in his 

Pleasant Park section, refers the overlying sandstone to the Triassic. Lee, however, 

is disposed to assign to the Carboniferous a series of unclesignated thickness at the 

base of the Red Beds in Perry Park, which he correlates with the Fountain formation of the Pikes Peak quadrangle. He represents this series upon his map as occurring beneath the Triassic or Red Beds in Perry Park, but not farther north, on Platte 

Canyon. If this correlation with the Fountain formation is authentic, the appearance, at the base of some of the thicker sections of the typical Wyoming formation, 

of beds representing the Fountain series, is much more probable. 

A considerable area of Triassic is represented by the Hayden atlas as occurring 

in Manitou Park, and beneath it beds of Lower Carboniferous and Silurian age are 

colored in. I can not see upon what evidence the Lower Carboniferous color is 

introduced into this area, however, as the Millsap limestone is apparently missing, 

while that portion of the "Triassic" coming in the southern part of the tract depicted 

on the map, which is included in the Pikes Peak quadrangle, is regarded by Cross as 

belonging to the Fountain formation, supposed by him to be of Carboniferous age. 

From the best evidence at hand, therefore, it would appear that the " Lower Carboniferous" is probably lacking in Manitou Park, that the "Triassic" of that area 

represents the Fountain and not the Wyoming formation, and that it is probably 

Carboniferous and not Triassic in age. 

Near Colorado Springs the Triassic is represented as underlain by Upper Carboniferous, Lower Carboniferous, and Silurian beds. I have elsewhere suggested 

that in Peale's Glen Erie section part of a considerable thickness of limestone 

lying beneath the Red Beds is to be correlated with the Millsap limestone, and it 

is probably this bed which is represented as Lower Carboniferous on the Hayden 

atlas. In this section Peale gives as occurring above the Millsap limestone ( ?) and 

below the Jurassic about 1,200 feet of sandstone of red and white colors, which he 

calls Triassic. It seems probable, in fact, that all these beds belong to the Fountain 

formation, and that the Triassic, though represented on the map, is really absent, 

the Morrison coming down upon the Fountain formation exactly as in Garden Park, 

in the Pikes Peak quadrangle; and it is apparent from the following quotation that 

Hayden must have referred nearly if not quite all of Peale's Triassic beds to the 

Carboniferous. Hayden says, "On the small map of `Colorado Springs and vicinity,' 

a light band will be seen between the Silurian on the west and the Red Beds or 

Triassic on the east, which represents a peculiar group of strata not observed elsewhere on the eastern slope, but resembling very closely a series of variegated beds, 

described by Dr. Peale in the annual report for 1873, in the valley of Eagle River, 

which yielded well-marked Carboniferous types. This group of strata is composed 
RECAPITULATION OF PALEOZOIC FORMATIONS. 187 

of variegated beds of sandstones of van us textures alternately with layers of arenaceous clay. The entire thickness was stimated at about 1,000 feet. It is most 

probable that these beds are Carbonifer us."a The beds on Eagle River with which 

Hayden compares this series (section 3, p. 244) form part of the Maroon formation. 

South of Colorado Springs the P zoics and Red Beds are concealed for a short 

distance by Cretaceous overlap, but t ayden atlas represents a considerable tract 

of Triassic and Silurian across the s ern end of the Colorado Range, north and 

northeast of Canyon. Much of this re is included in the Pikes Peak quadrangle, 

where Cross recognizes two Carbon fe ous formations, the Millsap limestone and 

the Fountain formation, intervening be ween the Ordovician Fremont limestone and 

the Morrison formation of Jurassic age. The Millsap limestone is probably included 

under the Silurian" color, the Fount in beds being the Triassic and the Morrison 

the Jurassic of the atlas. The condit ons 'here would then be the same as I have 

supposed them near Colorado Springs, ith the "Triassic" or Wyoming beds absent 

beneath the Morrison. Nevertheless. ast of the Pikes Peak quadrangle this series 

is supposed to reappear above the Faun ain formation. 

The Millsap limestone is, of course, of Mississippian age and has been considered 

in the appropriate section. Cross's defi ition of the Fountain formation applies alike 

to the outcrop in Garden Park in the s uthern part of the quadrangle and to those 

in the northeastern part which connect *th the exposures in Manitou Park north of 

the area. This consists of a series hiefly of coarse-grained, crumbling, arkose 

sandstones in heavy banks, locally cong omeratic and mottled with gray and various 

light shades of red. Near the base an at intervals throughout the series are very, 

dark-red or purplish layers of arenac ous shale or fine-grained sandstones. The 

thickness is about 1,000 feet. No fossi s were found by Cross, from whose description the facts noted above were derive , but the formation was referred by him to 

the Carboniferous, because of a simi arity to the Arkansas sandstone, of known 

Carboniferous age. The beds overlyi g the Fountain formation are the Morrison 

formation, the same series by which the Wyoming formation is followed in the 

Denver Basin. East of the Pikes Pea quadrangle, however, another series resembling the Wyoming comes in above th Fountain formation, intervening between it 

and the Morrison formation. Becaus the. Fountain formation seems to represent 

a distinct series underlying the W oming beds, the name " Wyoming" was 

introduced for the younger series in he Denver Basin monograph. At the same 

time I suspect that in local sections pa .t of even the typical Wyoming is equivalent 

to the Fountain. Hayden also regar ed this series as distinct from the Red Beds, 

as indicated in. the passage quoted a ove, which, however, refers to the exposures 

west of Colorado Springs. 

a U. S. Geol. Geog. Surv. Terr., ighth] Ann. Rept., for 1874, 1876, p. 42. 
188 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Stevenson cites the following section from Beaver Creek a few miles northeast 

of Canyon: 

• Section on Beaver Creek. 

Feet. 

1. Sandstone, soft, blood-red, shaly above, conglomerate below 100 

2. Gypsum 100 

3. Sandstone, soft, mostly deep-red, with layers of gray, somewhat micaceous, shows much cross bedding and is entirely unaltered. It is conglomerate throughout, but especially so at the base, where for several 

hundred feet it contains pebbles as large as a hen's egg and completely agatized. The coarseness of the material diminishes regularly to the top, where it is comparatively fine in grain. Estimated 

thickness 2, 500 

The locality of this section is within or just outside the area of the Pikes Peak 

quadrangle, and the strata which Stevenson refers to the Triassic probably belong 

in the Fountain and Morrison formations. The thickness of the lower series, 2,500 

feet, which is only estimated, is much greater than Cross cites for the Fountain beds, 

and it is possible that in it are included some of the Wyoming series, which is supposed to intervene between the Fountain and the Morrison east of the quadrangle. 

At the same time Gilbert allows the Fountain formation a thickness of 2,100 feet in 

the Pueblo quadrangle near by. 

South of Canyon the Red Beds and Paleozoics are again concealed for a short 

distance, but reappear on the eastern side of the Wet Mountains southwest of Pueblo 

in an area which is represented in the Hayden atlas under the Lower Carboniferous 

and Triassic colors. A portion of this area is included within the Pueblo quadrangle, 

where the beds designated as Lower Carboniferous and Triassic on the Hayden maps' 

are called by Gilbert the Millsap limestone and the Fountain formation, these names 

being, of course, borrowed from the Pikes Peak quadrangle, which lies northwest of 

the Pueblo quadrangle and corners with it. As I have already suggested, the upper 

half at least of Gilbert's Millsap is without much doubt the equivalent of the original 

Millsap, but because there is a considerable thickness• of the Ordovician Fremont 

limestone at Canyon it seems possible that the lower portion may be older. 

Gilbert refers the Fountain formation to the Juratrias period and describes it as 

consisting of coarse, deep-red sandstone containing a considerable admixture of clay. 

In the upper half of the series are many beds of red and 'chocolate-brown shale, in 

the lower part are conglomerates. The lowest bed seen is a coarse conglomerate 

containing pebbles and bowlders of gneiss, schist, and granite similar to those of the 

adjacent Archean. The thickness near Beulah is '2,100 feet. The top of the series 

is not there seen, but the missing beds are probably thin. The Fountain formation 

here, as farther north, and like the Wyoming formation of the Denver Basin, is 

succeeded by the Morrison formation. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 189 

This is the last of the Paleozoics mapped in the Hayden atlas along the mountain front in Colorado (except the Sangre de Cristo Ran e) and all but the last of the !.

Triassic, though a small area of the latter is represented at the southern extremity of 

the Greenhorn Mountains. Part of this tract is embraced by the Walsenburg quadrangle, where Hills has mapped the "Triassic" beds under the name of the Badito formation, which, however, he places somewhat doubtingly in the Carboniferous. The 

upper half of this formation consists of brick-red sandstones about 100 feet in thickness, generally massive, but sometimes shaly. It is supi3osed by Hills to correspond 

to part of the Fountain formation. The lower half consists of about the same thickness of very coarse conglomerate of a brownish-red color. In the Sangre de Cristo 

Range, according to Hills, the stratigraphic section corresponds very nearly with 

that at the southern extremity of the Greenhorn Mountains, except with respect to 

the thickness of the conglomerate. There is in each case about the same amount of 

capping red sandstone, but the coarse conglomerate and sandstone upon which it 

rests attains, in the Sangre de Cristo Range, a thickness of several thousand feet. 

Like the Fountain beds both in the Pueblo and in the Pikes Peak quadrangle, the 

Badito formation is succeeded by the Morrison formation, which here, as usual, 

probably is more or less closely the equivalent of the Jurassic of the Hayden atlas. 

The sequence described by Hills in the Walsenburg folio and the comparisons 

made by him with the Sangre de Cristo Range make it ]most appear as if in the 200 

feet of strata exposed in that area the dividing line between the Wyoming and 

Fountain formations was contained, part of the Badito elonging to one and part to 

the other formation. If the upper or brick-red portion of the Badito formation be 

really the equivalent of the Wyoming formation, then he latter, greatly reduced in 

bulk, must be present in the Sangre de Cristo Range, a oint of some interest in the 

distribution of that formation. Of course on this suppbsition it would be the lower 

and not the upper portion of the Badito which is equivalent to the Fountain. However, it seems to me a little more probable, from the fct that the Wyoming formation is apparently absent in the Pueblo quadrangle and over so much of the Sangre 

de Cristo Range, that the brick-red sandstone of the Walsenburg quadrangle does 

not really represent it, but is a local manifestation of the Maroon formation. 

South of the Wet Mountains the line of outcrop is taken up by the Sangre de 

Cristo Range, composed largely of the Arkansas sandstone, whose age is Upper 

Carboniferous. The Triassic and even the Jurassic seem here to be absent, concealed, it is safe to say, beneath the overlapping Cretaceous. The Paleozoics of the 

Sangre de Cristo Range are discussed in a separate section. 

The relation of these formations lying along the Front Range to one another 

and to the Red Beds in the interior mountain region, and also their geologic age, are 

questions in the highest degree perplexing. 
190 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In central Colorado the Maroon formation, variable in color and in the details 

of its lithology, but uniform as to its general character, is over considerable areas 

followed by what seems to be a distinct series, characterized by a persistent brickred color. This is the Triassic series of most writers. The evidence derived from 

fossils is, unfortunately, lacking, as these beds have proved for the most part unfossiliferous in Colorado; but, basing their opinion upon .whatever evidence was available, most geologists who have examined the strata on both sides of the Front Range 

agree in correlating the bright-red series of the eastern flank with the similar though 

quite differently associated beds of the western flank. This is true of Peale, Marvine, Hayden, Hague, Emmons, King, and. others. Emmons, indeed, uses for a. 

formation in the Tenmile district the same formational name which was employed for 

the Red Beds in the Denver Basin, viz, Wyoming formation. It seems necessary, 

therefore, to adopt as probably correct this correlation, in which all seem to concur, 

until the final paleontological test can be applied. If Cross and Hayden were correct 

in their statements relative to the Fountain beds, we have in that formation the 

equivalent of the Maroon conglomerate of the interior region. 

Considering the Red Beds as I have traced them through the work of others 

from the north to the south line of Colorado, there appear to be two distinct series, 

showing a certain amount of system and regularity in their development and distribution. The lower of these, the Fountain formation of Cross, is probably of 

Carboniferous age. Its greatest development is southward. The other is the 

Wyoming formation, whose age still remains in dispute, but is probably Triassic, 

though Darton has brought evidence, which ought not to be disregarded, tending to 

show that it is equivalent to the " Permian" of the Mississippi Valley. If this is so 

the overlap of this series upon the Carboniferous assumes especial importance, but 

it would militate against the correlation with the "Triassic" of the west side of the 

Front Range, supposed to be the same as the Dolores formation of southwestern 

Colorado in which the remains of Triassic vertebrates have been found. 

In the Sangre de Cristo Range the sandstones and conglomerates which carry 

Carboniferous fossils attain a thickness of 5,000 feet. Endlich has there given these 

strata the name "Arkansas sandstone," and they are without much doubt equivalent 

to the Maroon formation of central Colorado. It seems highly probable that the 

beds which Hills included in his Badito formation in the Wet Mountains only 20 miles 

to the east, though but 200 feet in thickness, belong to the same series. This area 

seems to be disconnecteda to the north and to the south. 

Another disconnected area of probably the same series occurs in the Pueblo 

quadrangle immediately north. Here it reaches a thickness of 2,100 feet, increased 

a The word disconnected is employed in the sense of "without visible connection." Probably all these areas are 

continuous under cover except the Manitou Park basin, which in the true sense is disconnected. 
RECAPITULATION OF PALEOZOIEC FORMATIONS. 191 

from 1,000 feet in the Pikes Peak quadrangle, a d speculation is permissible as to 

whether the Fountain formation of Gilbert may not include some portions of the 

Wyoming series, which appears to have no eq ivalent in Gilbert's section. His 

description, however, is more applicable to the M roon than to the Wyoming formation. The apparent absence of the Wyoming fo mation in this area is in line with 

its apparent absence over the southern portion of the Elk Mountains and in the 

Sangre de Cristo Range. In the Pikes Peak qu drangle to the northwest a considerable amount of these beds exists. Cross refer the Fountain beds in this area to 

the Carboniferous, especially on account of their resemblance to fossiliferous strata 

on the Arkansas River, 50 miles to the west. Thes can be no other than the Arkansas 

sandstone of EndliCh's reports. Cross measures 1,000 feet of these beds. Gilbert 

recognizes the Fountain formation in. the Pueb o quadrangle, and assigns to it a 

thickness of 2,100 feet. Hills, in the Walsenburg uadrangle, finds a greatly reduced 

thickness, only 200 feet, the upper half a brick-r d sandstone, which he compares to 

the Fountain formation, the lower half a brown conglomerate, which he compares to 

the sedimentaries of the Sangre de Cristo Range. Here, again, it must be the 

Arkansas sandstone which is meant. Thus the comparison made by Cross would 

indicate that the Fountain beds were the same as the Arkansas sandstone, while that 

of Hills would imply that it was a distinct series overlying the Arkansas sandstone. 

The upper division of Hills's Badito formation by its character and position in the 

section suggests the Wyoming formation, but as that series appears to be absent both 

from the: Sangre de Cristo Range and in the Pueblo and Pikes Peak quadrangles it 

seems more probable that this brick-red member is only a locally differentiated phase 

of Fountain sedimentation. The thickness of the Fountain in the Pueblo quadrangle is 

somewhat startlingly out of proportion to that in the Pikes Peak and Walsenburg 

districts, but the series with which it is supposed to be equivalent in the Sangre de 

Cristo Range and in central Colorado attains a. thickness of 4,000 to 5,000 feet, and 

the difference here is probably due to an unconformityi with the overlying Wyoming 

series, of which the marked overlap of the latter is additional evidence. 

The area to the east and south of the Pikes Peat quadrangle is likewise 

disconnected, and the same is true of the series as i appears in the Manitou Park 

Basin. It occurs again in the Garden of the Gods, wh re Hayden reports about 1,000 

feet, and it also exists in Perry Park, though Lee does not discriminate any definite 

thickness there. The great variation in thickness of the Wyoming formation in 

different sections in the Denver Basin is probably partly due to undifferentiated 

masses of Fountain beds included in their basal portions. The Carboniferous series 

of King, together with the one supposed to be Primordial, apparently is another 

recurrence of these beds. Taken together they measure 850 feet, and the 

Carboniferous beds carry fossils. 
112 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The "Triassic" or Wyoming formation seems to possess greater continuity, but 

apparently it does not extend much south of Colorado Springs, not being found in 

the Manitou Park Basin, in the Pikes Peak quadrangle, in the Wet Mountains, or 

in the Sangre de Cristo Range. 

The distribution of these formations would indicate unconformities by overlap 

(and probably by erosion) between the Millsap and Fountain, between the Fountain 

and Wyoming, and between the Wyoming and Morrison formations. 

In the San Juan region the sediments representing Upper Carboniferous or 

Pennsylvanian time are classed as the Molas, Hermosa, and Rico formations. The 

region from which the Hermosa and Rico formations were first described is the 

Rico Mountains, but a knowledge of its characters and variations over a much 

more extended area was drawn upon in framing the first description. The Hermosa 

formation, which has a thickness of 1,800 feet, is susceptible in the Rico region of a 

three-fold division. The lowest division consists chiefly of greenish-gray sandstones 

and shales, the latter being sometimes nearly black. The middle member is characterized by many bands of massive, dark-gray limestone, often highly fossiliferous 

and alternating with sandstones and conglomerates. The upper division is predominantly a complex of shales, with occasional limestones. The constituents of the 

Hermosa section vary largely from point to point, and the subdivisions which were 

there practicable can not, be distinguished over large areas. The lower division at 

Rico contains about 800 feet. The beds resting on the Ouray limestone are shales 

and impure limestones. Above this are gray grits or sandstones alternating with 

gray shales and several beds of black shale and thin, impure limestone. The middle 

division is made up very largely of blue, bituminous limestone carrying many fossils 

and occurring in massive beds from 5 to 100 feet in thickness, separated by shales 

and sandy shales. This division has a thickness somewhat in excess of 600 feet. 

The upper division contains some bands of limestone similar to those of the middle 

division, bat they are thin and unimportant in comparison. Its strata are mainly 

black and gray shale alternating with green grits and sandstones. Occasionally 

reddish sandstones are observed, and two black shales are present in the lower third. 

The top of the upper division and of the Hermosa as a whole is well defined from 

the base of the next higher formation. The topmost member consists of about 30 

feet of fine-grained, mica-bearing green shales, immediately above which conies a 

red, sandy, fossiliferous limestone of the Rico formation. 

The Rico formation is a part of the Red Beds series of southwestern COlorado. 

This series is rather a uniform one lithologically, and somewhat ,sharply defined 

from the Hermosa formation below, but the upper portion has been found to contain 

Triassic fossils, while at the base a well-marked Carboniferous fauna occurs. The 

upper limit of the Rico formation is arbitrarily taken about 300 feet above its base, 
RECAPITULATION OF PALEOZOIC FORMATIONS. 193 

for within these limits the Carboniferous fauna is known to occur. Thus defined it 

is made up of sandstones and conglomerates, with intercalated shales and sandy, 

fossiliferous limestones. Lithologically the Rico formation resembles the Dolores 

formation, which immediately overlies it, and which contains the median unfossiliferous portion of the. Red ,Beds, as well as the upper portion, which carries Triassic 

fossils. "The general characters of the Rico formation in the vicinity of Rico are, 

first, its calcareous nature, in which it resembles the strata above and below; second, 

the very arkose character and the coarseness of its sandstones, in which respect it 

differs from the Hermosa and resembles the Dolores; and, third, its chocolate or 

dark-maroon color, which contrasts sharply with the gray or green of the Hermosa, 

and which is more or less distinct from the bright vermilion of the Dolores. "The 

bulk of the formation is made up of sandstones and sandy shales, composed of such 

materials as are derived from the disintegration of granite. The sandstones are 

mostly coarse or conglomeratic." Intercalated with the sandstones and shales, 

which are for the most part very calcareous throughout, there are several beds of 

impure limestone, some an earthy gray and others sandy and red in color. 

In the Engineer Mountain quadrangle the Hermosa formation is underlain by 

beds of no considerable thickness but of rather mar ed lithology which Cross has 

differentiated and named the Molas formation. His d scription of this series can be 

condensed as follows: 

The Molas beds were not included in the original definition of the Hermosa 

formation, although the Hermosa was said to rest on the Ouray limestone. In the 

localities examined before that definition was formulated there was, in fact, a hiatus 

in the observations, the thin Molas beds being noWhere well exposed. The best 

section of the formation thus far observed is situated on the southwest slope of the 

Needle Mountains, on the south side of Tank Creel. At that locality there is a 

continuous section about 75 feet in thickness, representing the whole formation as 

there developed between the Ouray limestone and the Hermosa complex. There is 

no distinct stratification in the section. At the base is a zone of gradation into the 

Ouray limestone, for the upper zone of the latter is much broken up with the red 

calcareous mud of the Molas filling the interstices. This filling of the formation is 

very common. For some feet above this transition zone there is a chaotic mixture 

of chert and limestone fragments, with not a few of bluish or white quartzite, but 

none of granite or schist. In all the lower part of the formation much of the 

material is an impure limestone, reddish in color, but with the saccharoidal texture 

of the Ouray. It is probably a limestone sand-rock. The matrix in which the 

fragments of chert, quartzite, and limestone are held is a red, marl-like material. 

There are in places indications that a calcareous mud was broken up before consolidation, and was worked over with the fragments of foreign rocks. Gradually the 

14364—No. 16-03 13 
194 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

section becomes more and more sandy, but chert fragments were found almost up 

to the fossiliferous limestone of the Hermosa. 

This formation is especially characterized by its deep-red, friable, sandy strata, 

which are variably calcareous and often shaly. They are seldom very distinctly 

bedded, and disintegrate so rapidly on weathering that good exposures are rare. In 

the lower part of the formation dark chert nodules abound, often making a large 

part of flat lentils or discontinuous layers. Many of the cherts carry a- Lower 

Carboniferous invertebrate fauna, like that at the top of the Ouray limestone. In 

a single locality in the Needle Mountains quadrangle some thin limestones contain a 

fauna of Upper Carboniferous age, which is elsewhere discussed. 

The Molas formation is distinguished on lithologic grounds because it records 

a preceding interval of erosion, by which formations of Mississippian age were in 

large measure destroyed, and in a subordinate degree because of certain faunal 

peculiarities which further collections may or may not affect. 

Above the Rico formation come the Juratrias formations, which are the Dolores 

Red Beds, 1,600 feet in thickness, the La Plata sandstones, 250 feet or more, and the 

McElmo shales and sandstones, having a total thickness of nearly 900 feet. 

Comparing this series with that in the Elk Mountains, where, in the Crested 

Butte quadrangle, the geographically nearest detailed section occurs, we do not 

find the same patent equivalence, either in the rock groups themselves or in the 

formation names employed for them, which was a feature of the central Colorado 

sections.,, However, the Hermosa formation bears comparison in many ways with 

the lower portion of the Maroon conglomerate, though it evidently consists of finer 

materials and contains a larger proportion of shales and limestone. The lower 

member of the Maroon measures 2,000 feet, and the Hermosa 1,800 feet, with a 

maximum of 2,000 feet. The Weber formation of the Crested Butte has no distinctly marked equivalence in the San Juan, unless it be the Molas formation, which 

is somewhat different ]ithologically. There is, however, a certain resemblance 

between the fauna of the Weber and the rather distinctive faunas at the base of the 

Hermosa formation, which would indicate that the Weber formation had a correlate 

in the San Juan region, if not a very distinct one lithologically. 

The lithologic and color changes from the lower to the upper division of the 

Maroon formation have a counterpart in the change from the Hermosa formation to 

the maroon-colored Rico formation. While the Maroon of the typical area has a 

maximum thickness of 2,500 feet, this character is qualified by the fact that the 

thickness in the southern part of the Crested Butte area is very much decreased. 

The Dolores formation has apparently no lithologic equivalence in the Crested Butte 

region, but it greatly resembles the bright-red Triassic sandstone which overlies the 

Maroon at Lenado Canyon, near Aspen, and the Wyoming sandstone, which overlies 
RECAPITULATION OF PALEOZOIC FO MATIONS. 195 

the Maroon in the Tenmile and Leadville districts. I is not clear, however, that 

this bright-red series may not after all be present in th Crested Butte quadrangle, 

for in the northern portion, where the greatest thicknes of the Maroon occurs, the 

rocks of this formation are bleached and greatly me morphosed (Crested Butte 

folio). Nevertheless, one would expect some equivale t of the Dolores formation 

to appear, with its characteristic color character, in t e southern portion of the 

Crested Butte area, unless it were cut out, owing to the re-Gunnison unconformity. 

In the Dolores River region the Upper Carbonife ous, according to Peale, in 

whose accounts almost the only descriptions of the Paleo oic strata of this region are 

found, consists of light-yellowish and greenish shaly s ndstones and a space filled 

with shaly sandstones and perhaps bands of limestone, t e whole amounting to 3,500 

feet. This series rests upon a blue limestone about 300 eet in thickness, referred to 

the Subcarboniferous, and is overlain by the " Permian." This has at its base 300 

feet of yellowish and black shales and sandstones, with g psum and salt, and 700 feet 

of pink and red shales, with conglomerate, the sandst' nes becoming light colored. 

near the base and containing gypsum. The upper bed f the Permian is unlike the 

lower and unlike the rest of the Carboniferous, and a it seems to partake of the 

character of the Red Beds above, it appears more appro riate to unite it with Peale's 

Triassic, the lower portion possibly being joined wit the Carboniferous, which 

would then have a thickness of 3,800 feet. 

Lithologically this series appears to be the equivalent of the Hermosa formation 

of the San Juan region, while by the Red Beds above, the Dolores and La Plata 

formations are represented. The Rico formation, w hi h forms a part of the San 

Juan Red Beds, appears to be missing, or to have lost so} ewhat its distinctive color, 1

for Peale describes no brownish or maroon-colored bed in his Permian or Triassic 

series. The nearest instance is the blood-red sandstone and shale of his Trias, 

which are over 700 feet up in the Red Beds. This point is interesting, and it is to 

be regretted that the evidence by which a satisfactory .onclusion can be reached is 

lacking. If, however, my correlation of the Rico with t e upper part of the Maroon 

is justified, by which the thickness is reduced from 2,50 feet in the Crested Butte to 

300 feet in the San Juan region, its complete disappearance in the Dolores region is

, not surprising. The fact mentioned by Eldridge, that the upper Maroon is greatly 

diminished in thickness in the southern part of the Crested Butte quadrangle, is 

distinctly favorable to its correlation with the Rico. the upper portion of Peale's 

Permian, taken with his Triassic, and possibly in places ith a portion of his Jurassic, 

are the probable equivalent of the Dolores and La Plat formations, as the Jurassic 

is of the McElmo, but iese formations appear to be of educed thickness in Peale's 

area. 

The Carboniferous of Peale, even without the 300 feet of " Permian " which I 
196 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

have united with it, is very much thicker than the Hermosa formation. This may 

be due to the recognized unconformity by which the Hermosa (or the Hermosa plus 

the Molas formation) was preceded, but it may result from an unconformity by 

which I suspect it was followed. The sharp faunal break between the Hermosa and 

the Ricch formations suggests an unrepresented time interval between them. This 

fact, the greatly increased thickness in the Dolores River region, and the fauna from 

. the upper beds there, which is unlike that of the Rico and still different from that of 

the Hermosa, all favor the hypothesis, if not of an unconformity between the 

authentic Hermosa and Rico formations, at least of a period of nondeposition during 

which, in areas adjacent, as in the Dolores River region, sedimentation was going on. 

The possibility of the Rico being represented by the series referred by Peale, to the 

Carboniferous is so remote, from the evidence at hand, as to need no discussion. 

The fact that the upper portion of the " Permian " is described by Peale as 

overlapping upon the Archean serves as a warrant at the same time for subdividing 

the beds grouped by him and fcr correlating the upper portion with the " Triassic" 

Red Beds overlapping elsewhere in Colorado. 

Compared with the Crested Butte section, Peale's Upper Carboniferous seems to 

equal the lower member of the Maroon conglomerate, the upper member of which 

may have no equivalent in the Dolores River region. Almost the same difficulties 

here arise as in the suggested correlation with the San Juan Carboniferous, and the 

same facts must be used to meet them, though their application rests upon the 

correctness of my correlation of the upper and lower Maroon with the Rico and 

Hermosa formations, respectively. If the Dolores Carboniferous equals both 

the lower and upper Maroon, wholly or in part, my correlation of the Maroon 

with the Rico and Hermosa formations will probably be in error, the slender 

evidence at hand for the correlation of the Dolores and Crested Butte areas will 

have been misinterpreted, and the lithologic character of the Maroon will have 

proved very variable, but its general thickness more constant. 

In addition it must be pointed out that while the upper Maroon seems to be 

absent in the Dolores River region, the Red Beds of the latter (including most of 

Peale's Permian and most of his Trias) are wanting in the Crested Butte ivegion. 

Peale's Jurassic, with probably the upper members of his Triassic, are the equivalent of the Gunnison formation, and while they show somewhat reduced dimensions 

in Peale's area, the discrepancy is not so great as when compared with the equivalent I 

formations in the San Juan region. 

The geology of the Uinta Mountains is described chiefly in two reports, one by 

Emmons, the other by Powell. King also recapitulated and rearranged Emmons's 

account in his general geologic discussion of the area covered by the survey under 

his charge. Powell's survey was conducted along the Green and Colorado rivers; 
RECAPITULATION OF PALEOZOIC FORMATIONS. 197 

his correlations are with the Grand Canyon • section, and his nomenclature in large 

part that employed by Gilbert for strata in northern Arizona. Similarly, Emmons's 

survey was westward, along the fortieth parallel, through the Uinta Range and into 

the Wasatch Range. His comparisons are, therefore, with the Wasatch section, and 

the same nomenclature is employed. I have elsewhere considered at some length 

the three sections thus bound together in the literature, and need only repeat the 

outlines of the previous discussion. 

Powell's section, which was made in the eastern en of the Uinta Range, is more 

detailed than that of King and Emmons. The basal me ber of the sedimentary series 

is the Red Creek quartzite, a formation of very great t *ckness, which will doubtless 

prove to be of Algonkian or pre-Cambrian age. 

Above the Red Creek quartzite, and separated from it, according to Powell, by 

an important unconformity, is another great siliceous formation, the Uinta sandstone, 

which has a thickness of over 12,000 feet. The Uinta sandstone is followed by the 

Lodore, Red Wall, lower and upper Aubrey, and Shiilarump groups, whose characters may be summarized somewhat as follows: 

The Uinta group consists of sandstones and sandy shales, and is very ferniginous 

throughout, the general color being red and brown. Conglomeratic horizons are 

occasionally found in the series, and at its junction With the Red Creek quartzite 

there is a basal conglomerate. The thickness is 12,500 feet. 

The Lodore group is said to rest unconformably upon the Uinta sandstone. It 

is 460 feet thick, and composed of soft sandstones and shales, with conglomerates at 

the, base. Carboniferous fossils have been found in th se beds (Powell). 

The Red Wall group consists of cherty limestone o the north flank of the Uinta 

Mountains, while on the south flank many sandstones are intercalated with the calcareous beds. A measured section in the Uinta 1VIoun ins gives the entire thickness 

as 2,400 feet, but it is elsewhere stated as 2,000 feet.a 

The lower Aubrey group consists of soft sandston s and intercalated limestones. 

The thickness found in a detailed section in the Uinta Mountains is 800 feet. It is 

elsewhere stated as 1,000 feet. 

The upper Aubrey in the Uinta Mountains is composed of two members, a 

massive, homogeneous, gray sandstone called the Yampa sandstone, and above it a 

cherty limestone for which the name Bellerophon limestone is employed. The Yampa 

sandstone has a thickness of a thousand feet or more. The Bellerophon limestone is 

150 to .200 feet in thickness. The thickness of the u per Aubrey is also given a4 

1,000 feet, and in a detailed section 1,575 feet was mea ured. 

The- Shinarump group is given a thickness of 1,8 0 feet in the Plateau province 

section, and consists in the Uinta Mountains of shales and soft sandstones. In the 

a Powell's Rept. Geol. Uinta Mountains, 76. 
198 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

section made at Flaming Gorge, in the.Uinta Mountains, the series comprises 1,095 

feet of shales and sandstones containing much gypsum and weathering in many 

colors, but with prevalent tints of brown and chocolate.' It is succeeded by the Red 

Beds series, consisting of the. Vermilion Cliff, White Cliff, and Flaming Gorge 

groups, which, together with the Shinarump, Powell places in the Juratrias. 

The Uinta series of Powell is usually called by King the Weber quartzite. The 

Lodore, Red Wall, Lower Aubrey, and Upper Aubrey groups are collectively cited 

by King as the Upper Coal Measures. The upper limit of King's Upper Coal 

Measure series is evidently precisely that of Powell's Upper Aubrey group, both 

being determined by the Bellerophon limestone; but it can not be said with equal 

certainty that both drew the line between the Uinta sandstone and the overlying 

beds at exactly the same point. From 200 to 500 feet of Powell's Shinarump group 

are subtracted by King under the name of the Permo-Carboniferous series. The 

rest of the Shinarump, together with the White Cliff and Vermilion Cliff groups of 

Powell, are King's Triassic; the Flaming Gorge group his Jurassic, etc. 

Several disagreements are found between Powell's and King's accounts of the 

geology of this area, the chief of which are as follows: Powell describes a great 

unconformity between the Uinta sandstone and the Lodore group, which was not 

observed by the geologists of the Fortieth Parallel Survey. The combined thickness 

of the four groups, which taken together form the Upper Coal Measure series of 

King, is over 5,000 feet,a while King assigns to that series a thickness of but from 

2,000 to 2,500 feet. Finally, Powell refers the Uinta sandstone to the Devonian, 

while by King's correlation it would be Pennsylvanian. Powell's correlation implied 

in the use of the name Red Wall, would make the Uinta sandstone probably preCarboniferous in age, since the base of the true Red Wall is Lower Mississippian.b 

I am forced to conclude, therefore, that Powell's correlation is erroneous, that of 

Emmons and King being probably correct, and that the upper part of the Uinta 

sandstone at -least is of Pennsylvanian age, the overlying beds being, of course, still 

younger. This conclusion seems to be demanded by the following facts: 

1. Because Emmons traced the Uinta sandstone westward into the Wasatch 

Range, finding its equivalent to be the Weber quartzite, the age of which, as determined by fossils, is Pennsylvanian. 

2. Because the supposed Red Wall limestone at Gypsum and Cataract canyons 

furnished a few fossils probably indicating Upper Carboniferous. 

3. Because a Pennsylvanian fauna was found at the very base of the Upper Coal 

Measures of King. 

a As determined by Powell's detailed section, which would naturally be supposed to be more exact than the statement 

in round numbers made elsewhere. 

bin the Grand Canyon region both Meek, Walcott, and Frech agree in a general way in referring the lower portion of 

the Red Wall to the Mississippian series, and our collection also contains Mississippian fossils from it. 
RECAPITULATION OF PALEOZOIC ORMATIONS. 199 

4. Because very fragmentary evidence from the 

that its upper portion is also of Pennsylvanian age. 

Powell obtained a few species from the Red Wall 

yons in eastern Utah which while apparently indicatin 

very diagnostic. They are Chwtetes milleporaceus, S 

Campophyllum sp. King also cites SyringoPora as o 

a horizon somewhat higher than the fauna referred 

Carboniferous fossils were found in the Lodore gro 

they were. Apparently none were collected. King 

Seminula subtilita, and Meekella striaticostata, adding 

obtained from the Upper Coal Measures system in the 

60 feet of heavy beds of the Weber." a The locality i 

at Ute Peak, and the stratigraphic horizon should be 

its of King's Weber and Powell's Uinta series are tak 

some doubts might remain in spite of the corals found 

Spiriferina, Seminula, and especially the llfeekella, i 

the Lodore group, or in any event the Red W all 

Carboniferous. 

The Uinta sandstone has been said to be essential 

instances of the occurrence of fossils are known; a 

occurrence and lithology seem to render the assignme 

original horizon probable. Half of a Spirifer of the 

Agassiz, the impression of a crinoid column at the he 

men of Spirifer cameratus from the Bench region, ne 

entire paleontologic evidence. Spirifer cameratus i 

iferous type. The.Spirifer imbrex could hardly be 

while, in view of local conditions, even the crinoid col 

indicating the same period. The paleontologic evide 

of the correlation by stratigraphy of the Uinta sands 

with the Weber quartzite of the Wasatch Range, w 

Carboniferous age. 

Another matter of disagreement between King 

refers his Shinarump group to the Juratrias, the low 

King's Permo-CarboniferouS series. Powell's Shi 

King's Permo-Carboniferous is reported as from 20 

the Permo-Carboniferous the geologists of the For 

some fossils which were identified as .111-yalina {resew 

sp., Bakewellia parva, Pleurophorus sp., and ilfacrod 

inta sandstone itself indicates 

at Cataract and Gypsum canUpper Carboniferous are not 

ringopora multattenuata, and 

curring west of Ute Peak, at 

to below. Powell says that 

p, but does not specify what 

*tes Spiriferin,a kentuekyensis, 

"These are the lowest forms 

Uinta, and are collected within 

west of the canyon of Lodore 

n the Lodore group if the limn at the same level. Though 

by Powell, the evidence of the 

unmistakable, and shows that 

group, belongs in the Upper 

unfossiliferous. Only three 

I were from debris, but their 

t to the Uinta sandstone as the 

imbrex type found near Mount 

d of Bear River, and a speci-

✓Geode Canyon, comprise the 

distinctly an Upper Carbonower than the Carboniferous, 

imn may be taken as probably 

ce, therefore, is confirmatory 

one, at least in its upper part, 

ich is known to be of Upper 

and Powell is that the latter 

✓portion of which constitutes 

arump measures 1,800 feet. 

to 500 feet. Near the top of 

ieth Parallel Survey obtained 

ling subguackrata), Myalina n. 

n sp. If correctly identified, 

a U. S. Geol. Expl. 40th Par., Rept., vol. , p. 145. 
200 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

this fauna would indicate the Carboniferous period without question; but recent collections from the Permo-Carboniferous of the Wasatch Mountains have raised a 

doubt as to whether the age is really Paleozoic or Mesozoic. 

The Paleozoic section of central Colorado has a maximum thickness of 7,120 feet, 

made up as follows: Sawatch quartzite (Cambrian), 604 feet at Eagle River; Yule 

limestone (Ordovician), 400 feet at Aspen; Parting quartzite (Devonian?), 90 feet at 

Crested Butte; Leadville limestone (Devonian and Mississippian), 525 feet at Crested 

Butte; Weber shale (Pennsylvanian), 1,000 feet at Aspen; and Maroon formation 

(Pennsylvanian), 4,500 feet at Crested Butte. In addition to this we have the brickred series of Red Beds, commonly referred to the Trias, which measures 2,600 feet 

at Aspen. There are in this series, however, a number of time breaks and some 

erosional unconformities. The most important instance of the latter is at the top 

of the Leadville limestone. 

An interesting parallel can be drawn between the Paleozoic section of central 

Colorado and that of the Wasatch Mountains of Utah, one also which will aid in 

determining the relation of the former with the Uinta Mountain section. Except in 

thickness, the Cambrian series of the Wasatch Range is not unlike the Cambrian of 

Colorado. The Cambrihn in each case is followed by a limestone of Ordovician age— 

the Ute limestone in Utah and the Yule limestone in Colorado. This again is 

succeeded by a quartzite series—the Ogden quartzite in Utah and the Parting quartzite in Colorado, the age of which is suspected to be Devonian. Then also, in both 

areas, follows a limestone of Mississippian age—the Wasatch limestone of the Wasatch 

section and the Leadville limestone of Colorado. In Colorado a Devonian series is 

included with the Leadville limestone, which I believe to have no equivalent in the 

Wasatch section. The geologists of the Fortieth Parallel Survey found Upper Carboniferous fossils down to 5,400 feet below the top of the Wasatch limestone. We 

may consider, therefore, that the lower 1,600 feet are of Mississippian age and the 

upper 5,400 feet of Pennsylvanian age. The Mississippian portion of the Leadville 

limestone can be correlated, not only by its lithology and position in the section, but 

also almost conclusively by its fauna, with the Mississippian portion of the Wasatch 

limestone. If the sedimentation which produced the Wasatch limestone was not 

entirely uninterrupted, the series is at least more complete than that in Colorado, 

for above the beds whose fauna warrants a correlation with the Leadville limestone 

succeeded others with an upper Mississippian fauna, which were either never 

deposited upon the Leadville, or, as I believe more probable, have been lost by 

erosion. 

The Leadville limestone is succeeded by shales and limestones, unfortunately 

called the Weber limestone, or Weber shales, which occupy the same position in the 

section as the upper portion of the Wasatch limestone. Above the Weber in Colo-
RECAPITULATION OF PALEOZOIC FORMATIONS. 201 

rado follows the Maroon formation, and above the Wasatch limestone the Weber 

quartzite, both siliceous series of like geologic position and thickness. The Upper 

Coal Measures and Permo-Carboniferous of the Wasatch section have no obvious 

equivalents in Colorado, while the equivalence of the Wyoming formation in the 

Wasatch Mountains is similarly obscure. 

The geologic section of the Wasatch Mountains and that of central Colorado are 

thus seen to be very similar. They also show this striking difference—that nearly 

all the formations are thinner, and many of them much thinner, in Colorado. As a 

marked exception to this prevalent rule, the Maroon formation of Colorado and the 

Weber quartzite of Utah have essentially the same mass namely, 4,000 or 5,000 feet 

in each case. 

There is another possibility, however, which may of be entirely passed over. 

If the Weber limestone and Weber shale of Colorado tand for the Pennsylvanian 

portion of the Wasatch limestone, this series is reduced from 5,400 feet in Utah to a 

maximum of about 1,000 feet in Colorado, while in the Uinta Mountains it does not 

occur at all or has lost its calcareous nature. That it does change character to a 

considerable extent seems probable: The upper Mississippian fauna, whose presence 

would indicate less extensive erosion if not uninterrupted sedimentation in Utah 

during the transition from Lower to Upper Carboniferous time, was found not in 

the Wasatch but in the Oquirrh Mountains, where the lithologic series is somewhat 

different. This fauna is conjectured to correspond in the Wasatch limestone to an 

indefinite horizon not far below that assumed to ma -k the division between the 

Mississippian and Pennsylvanian. In the Oquirrh M untains, however, the beds 

immediately following are not limestone, but alternat ons of limestone containing 

Coal Measure fossils and quartzite, in which the siliceous beds predominate. Either 

these must be the upper Wasatch of the Wasatch Range, or else the upper 

Wasatch is missing.a King also instances changes from a calcareous to a siliceous 

phase in certain beds of the upper Wasatch. The variations in thickness of the 

lower member of the Maroon formation in several sections in which I have correlated it have suggested _to me that a period of erosion or nondeposition may 

have intervened between it and the upper Maroon This fact, taken with the 

tendency of the upper Wasatch to pass over into siAceous phases, would seem to. 

justify entertaining the suggestion that the upper Wasatch may be equivalent to the 

Weber limestone and shale combined with the lower Malroon, and the Weber quartzite 

itself equivalent to the upper Maroon only. This, ho ever, seems less likely than 

that the Maroon and Weber quartzite and the upper asatch and Weber limestone 

are equivalent. 

While there is little direct evidence supporting this view, I believe that the 

a provided, of course, that the upper portion of the Wasatch of Pennsylvanian age. 
202 

• 

CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

diminution in thickness of these strata as they pass eastward is due to the absence of 

increasing amounts of sediment, probably the effect of erosion. That this agency 

had a dominant share in reducing the Mississippian (Leadville) limestone to its 

present dimensions I have no doubt; while the fact that the series along the Front 

Range, which the earlier geologists thought to be unbroken and complete, has been 

shown, as work increased in detail and refinement, to be most incomplete and 

interrupted, lends color to such an explanation for the whole. 

It is indeed possible that another interruption or unconfcamity occurs within 

the Upper Carboniferous. The thinning of the upper Wasatch from 5,400 feet 

in the Wasatch Mountains to 100 feet (Weber limestone), for instance, in the Crested 

Butte quadrangle, would indicate, if not actual erosion, at least somewhat exceptionally unequal deposition, while the overlap of the Maroon beds upon the granite 

is not without significance. Variation in the lower Maroon, as elsewhere discussed, has led to a somewhat similar suspicion relative to the division between it 

and the upper member. It also appears to me highly probable that an interruption 

in sedimentation, if not actual erosion, intervened between the Maroon series and 

the Triassic above it. 

From the evidence at hand it seems impossible not to accept the correlation by 

Emmons and King of the Uinta sandstone and the Weber quartzite. The correlation 

of the Weber quartzite of Utah and the Maroon formation of Colorado, thus suggested 

by a comparison of the geologic sections of the two areas, seems to be partially 

expressed by Emmons in employing the term Weber formation for the lower half of 

the series which, in the Tenmile and Leadville districts, represents the original 

Maroon formation. It is the Weber quartzite of Utah and the Maroon formation of 

Colorado that in approaching each other are supposed to pass into the Uinta sandstone. One point of difference is the red color of the typical Maroon and the general 

whitish tint of the Weber quartzite. However, the Maroon seems to lose most of its 

color in the Leadville and Tenmile districts, while the eastern exposures of the Uinta 

sandstone have the brownish tint which is supposed to characterize it. 

Since the Weber and Maroon formations maintain so uniform a thickness (from 

4,000 to 5,000 feet) both in Utah and Colorado, it is a matter of surprise that the 

-Uinta sandstone should reach a thickness of 12,000 feet and more, and the first 

inference would be that the Uinta sandstone represents something more than these 

formations. It can, however, hardly represent the whole Paleozoic series of Colorado. 

The differences existing between the Uinta sandstone and the varied sediments 

of the different Paleozoic horizons of Colorado are differences both of character and 

of thickness. If the supposition be entertained that the Uinta sandstone represents 

the entire Paleozoic series of Colorado, the differences of character become more 

pronounced; if only the Maroon formation, differences of. thickness. The former 
RECAPITULATION OF PALEOZOIC ORMATIONS. 203 

hypothesis, on the whole, seems to me altogether un enable. The Paleozoic series 

in Colorado as it now stands is so incomplete that th column in its entirety would 

probably far exceed even the great thickness of the U nta sandstone. This becomes 

obvious from the consideration that the Maroon form tion represents only a moiety 

of Carboniferous time, yet it alone is half as thi k as the Uinta. Again, the 

supposition is incredible that all Paleozoic time coul be represented by a uniform 

series of sediments like the Uinta sandstone. Much more incredible is it that the 

Uinta represents a frequently interrupted and eroded eries. 

The Cambrian quartzites, though at most but 600 feet in thickness in Colorado, 

are expanded to 12,000 feet in the Wasatch. It wou d seem likely that this series 

is represented in the Uinta Mountains by considerabl thicknesses a proportional to 

its intermediate position, and it is admissible that the Parting quartzite, or even the 

siliceous Yule limestone, may be represented there b modified and less important 

measures; but the persistence of the Leadville as a li estone horizon is so striking 

that I should hesitate to adopt any mere hypothesis hich demanded its local mutation into sandstones and conglomerates. It seems t me more probable, however, 

that a period of uplift and erosion during Carbonifer us time destroyed in the Uinta 

area the older sediments, perhaps already thinned by revious erosion, down into the 

Cambrian beds; and that upon the base thus formed as spread the waste so similar 

in character to the much older sediments that it now as the casual aspect of a single 

continuous series. Which of the two erosion epochs whose occurrence during Carboniferous time I have tentatively hypothecated perfo med this work, it is impossible 

to say. If the one which intervened between Lead ille sedimentation and that of 

the Weber limestone, whose existence seems to be es ablished, it is evident that the 

Uinta sandstone must include, besides the Weber q rtzite and Maroon formation, 

thicknesses of shales and sandstones representing th Pennsylvanian portion of the 

Wasatch limestone, unless the latter is conceived to e entirely lacking in the Uinta 

Mountains of Colorado. The absence of the Pennsylv nian Wasatch might, however, 

be accounted for by the suppositious unconformity b tween the Maroon and Weber 

formations of Colorado, owing to which also the 5,40 feet of upper Wasatch wedge 

out to a few hundred in that State. If this erosion w re performed or consummated 

by the still more hypothetical occurrence which has een suggested between the two 

divisions of the Maroon itself, these calcareous bed of the upper Wasatch, as well 

as the Mississippian ones and even part of the Mar on-Weber series itself, would 

appear to be equally unrepresented. On the other h nd, it is possible that the whole 

of the Uinta sandstone may be of Pennsylvanian age 

a Peale remarks, under the caption " Silurian Age: ' " There was a much reater development in Mr. Marvine's di strict 

and further details will be found in his report." (Hayden's U. S. Geol. Geogr. Surv. Terr., [8th] Ann. Rept., for 1874, 1876, p. 

110.) It is not clear whether this refers to the Silurian as a whole or to ne or several of the divisions which Peale 

recognizes. Most of his Silurian series (probably 600 feet) is Cambrian (Saw tch quartzite) and his statement is somewhat 

favorable to the hypothesis adopted above. Marvine's district lay to the n rth and northwest of that of Peale. Unfortunately his report never came to publication. 
204 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In this case the unconformity between the Red Creek and Uinta formations 

would correspond to that which follows the Leadville limestone in central Colorado.a 

This supposition would be most favorably entertained in connection with the 

hypothesis that the Pennsylvanian portion of the Wasatch limestone becomes transformed in the Uintas into sands and clays, while the several hypothetical unconformities within the Pennsylvanian series of Colorado, and especially that above the 

Maroon beds, might be appealed to as the cause of the diminished representation in 

that region. That the Wasatch limestone of ' Utah or the Weber limestone of Colorado is represented in the Uinta Mountains seems to me rather doubtful, the probability being that the Maroon-Weber series rests directly upon the pre-Carboniferous, 

chiefly Cambrian, quartzites, with the Wasatch limestone on one hand and the Lead­

\dile and Weber limestones on the other wedging out convergingly in the direction 

of the Uinta Mountains. The overlap of the Maroon-Weber series upon the Cambrian in the Uinta Mountains would then be but another expression of the same 

readjustments by which in the Crested Butte quadrangle it came in contact with the 

Archean. 

While it is true that no unconformities are known within the Uinta sandstone, 

they may have escaped detection because of the uniform composition of the series 

and the difficulty of tracing individual beds. 

Accepting provisionally the correlation of the Maroon-Weber series of Colorado 

with the upper portion of the Uinta sandstones, the correlation of the Wyoming 

formation (the so-called " Triassic") in the Uinta section and the determination of 

its geologic age are beset with still greater uncertainties. 

Powell's Jurassic of the Uinta Mountains is clearly the same as that of King, 

and King expresses absolute certainty of the Jurassic of the Front Range being the 

same as that of the Uinta Mountains. Between the Jurassic and Maroon formations 

in central Colorado is found the Wyoming formation, whose average thickness 

seems to be 1,500 feet (it is possibly 2,600 feet at Aspen). Within equivalent limits 

in the eastern end of the Uinta Range, according to Powell's section, are his 

Carboniferous and part of his Mesozoic groups, comprising the Lodore group, with 

a thickness of 465 feet; the Red Wall group, with a thickness of 2,460 feet; the Lower 

Aubrey group, with a thickness of 805 feet; the Upper Aubrey, with a thickness of 

1,575 feet; the Shinarump, with a thickness of 1,095 feet; the Vermilion Cliff, with a 

thickness of 615 feet; and the White Cliff, with a thickness of 1,025 feet. The whole 

comes to a total. of 8,090 feet. 

It has elsewhere been remarked that though Powell gives a combined thickness 

of over 5,000 feet to his Carboniferous groups in the Uinta Mountains, King allows 

aThis unconformity would have to be invoked to account for the absence of the Ogden quartzite and of the Wasatch 

and I.Tte limestones. In default of evidence as to the age of the Red Creek quartzite it might be taken as equivalent to the 

Cambrian series of the Wasatch Mountains. 
RECAPITULATION OF PALEOZOIC F I RMATIONS. 2 05 

but 2,000 or 2,500 feet to the same series, together wit an additional 200 to 500 feet 

taken from Powell's Mesozoic. King's Triassic is fixe at 2,000 feet, while Powell's 

Shinarump, Vermilion Cliff, and White Cliff groups aggregate 2,785 feet, from 

which, however, must be deducted 200 to 500 feet to r present the lower portion of 

the Shinarump, assigned by King to the Carboniferous. 

Two posdbilities, in default of decisive evidence, pr sent claims for consideration. 

The hypotheses that the Wyoming formation represent either the Carboniferous or 

the Triassic can be supported by evidence. If the Wy oming beds be placed as the 

equivalent of the " Upper Coal Measures " of the Ul to Mountains, it must needs 

follow that its age would be Carboniferous and that th Triassic of the Uinta Mountains would be absent from central Colorado. Regarding the former deduction, it 

will be recalled that Knight found Carboniferous fossil, in King's Triassic near the 

Colorado-Wyoming line, and Darton reports a similar occurrence in the Wyoming 

formation of the Front Range. To be sure, in Knight' case only the lower half of 

beds mapped Triassic by King are proved to be Car i oniferous, but it might have 

the appearance of forcing the correlation to cut off t e upper 800 feet as Triassic, 

especially since the upper beds are similar lithologic lly and appear to have been 

deposited in unbroken succession. Further, some of he faunal assemblages found 

by Knight are strongly suggestive, in the abundance o Bellerophon and Dentalium, 

of the fauna of the Bellerophon limestone, and of one hick occupies a similar position at the top of the Aubrey series in the Grand Cany s n region. Powell describes 

this formation as being an indurated calcareous sand tone on the south side of the 

Uinta Range (p. 55), so that the lithologic as well as t a e faunal facies of the beds in 

Wyoming are suggestive of the Bellerophon limesto e. Darton's evidence is less 

complete, but tends in the same direction. He identifie s at Morrison, near the top (?) 

of the Wyoming formation, strata having the same li hologic character and similar 

invertebrate fossils to the Carboniferous Red Beds of the Black Hills. Over much 

of the State the Red Beds (Wyoming formation) are without determinable fossils, 

except for the two occurrences just mentioned., Unco a formably above them rests the 

Jurassic (Morrison and Gunnison formations). Thou. h commonly referred to the 

Triassic. these strata, therefore, might really be Car oniferous, so far as intrinsic 

evidence is concerned, and equivalent to the Upper Coal Measures of the Uinta Mountains. Indeed, Emmons states of the Wyoming forma ion that if any Permian exists 

in Colorado that series probably represents it. The a sence of the Shinarump, Vermilion Cliff, and White Cliff groups of Powell's Uinta ountain section (the Triassic 

of King) might readily be accounted for by the er sion which preceded Jurassic 

sedimentation. In southwestern Colorado the Carboni erous is followed by a formation (the Dolores) which has the characteristics and p sition of the Triassic in other 

parts of the State, which Cross and Spencer affirm t be the same as the Triassic 
206 CARBONIFEROUS FORMATIONS AND FAUNAS. OF COLORADO. 

of the Rocky Mountain province, and which carries Triassiver,tebrates. If, however, the paleontologic evidence produced by Knight and by Darton, which is by no 

means unassailable, be admitted, it is evident that the two series are not the same. 

However, it has already been remarked that the Wyoming beds appear to be absent 

in the Crested Butte quadrangle and generally over the southern end of the Elk 

Mountains, the Mosquito Range, and the Sangre de. Cristo Range, so that its absence 

' in the San Juan is not unanticipated; while that area is geographically so related 

to the Colorqdo Canyon and Uinta Mountains, where Triassic beds are found, that 

the presence there of the Triassic need not be an objection, even if the series is 

absent over the rest of the State, as it must be if the Wyoming beds are really 

Carbpniferous. 

On the whole, however, the evidence seems to me stronger that the "Red 

Beds" of Colorado are really Triassic, and represent the Shinarump, Vermilion, and 

White Cliff groups of the Uinta section, or parts of them. The apparent absence 

elsewhere in Colorado of the "Upper Coal Measures" of the latter area can be 

accounted for in another way. 

If the Maroon formation represents the upper portion of the Uinta sandstone 

and the Wyoming formation the Triassic of the -Uinta Mountain section, where the 

Wyoming beds rests upon the Maroon, as in the Leadville and Tenmile districts, or 

when the Jurassic occupies a similar position, as it does in the Crested Butte district, 

it is evident that the Upper Coal Measure series of King must be absent. Many 

observers agree that the Wyoming formation succeeds the Maroon in apparently a 

perfectly continuous manner, and the same with their supposed correlates in different 

parts of the State. Yet along the Front Range and in southwestern Colorado the 

supposed Triassic series overlaps upon the Archean and indicates important isostatic 

readjustments in which the conduct of the strata in northwestern Colorado may find 

a rational explanation. Furthermore, the faunal break in the San Juan region 

between the Rico and Dolores, in which Permian and probably portions of Carboniferous and Triassic time are apparently missing, together with the variability seeming to exist, such that the upper division of the Maroon formation, 2,500 feet thick 

in the Crested Butte quadrangle, is reduced to 300 feet (Rico formation) in the San 

Juan region and is entirely absent in the Dolores River region, are indications of an 

uncomformity, or at least of very abnormal conditions of deposition. There is some 

evidence, however, that the Upper Coal Measure series is represented in Colorado. 

Both the fauna itself, while no correlation can be based upon it, and the lithologic 

association with reddish sandy limestones and white sandstone of the fossils cited 

by King from Ute Peak, in the eastern end of the Uinta Mountains, are suggestive of 

the fossiliferous horizons in the Red Beds as they occur on the flanks of the Front 

Range, just north of the Colorado line. The similarity in a general way of the fauna 
RECAPITULATION OF PALEOZOIC FORMATIONS. 207 

recently found by Knight in the Triassic of this area to that of the Bellerophon 

limestone has already been remarked. The Jurassic codes only 800 feet above these 

Carboniferous horizons in Knight's section, and it is necessary to conclude either 

that the Triassic is wanting at this point, and erroneously represented thete by King, 

that it is represented by these upper 800 feet, even though they are lithologically 

like the Carboniferous beneath and apparently continuous with it, or that the.Triassic, nowhere in this area determined by fossils, is really Carboniferous, the series 

being in fact a unit determined as to age by the Carboniferous faunas occurring 

invariably in the lower portion. Probability, in my judgment, as already remarked, 

weighs more heavily in favor of• regarding the Carboniferous and "Triassic' of this 

region as two separate series, the upper one correlated with the Triassic of more 

distant areas where Triassic fossils are found. 

The interesting discovery by Knight, above referred to, I believe to represent 

the Carboniferous which King describes as comprising 1,500 feet on the west side 

of the Front Range, the same thickness as all of Knight's Red Beds below the 

Jurassic. The absence of the Triassic at this point, if, as seems rather more probable, it is not represented by the upper unfossiliferous series, is by no means without 

precedent, and is easily to be accounted for by the erosion period which preceded 

the Jurassic sediments. It appears not improbable that some of the sediments now 

supposed to represent the Maroon formation should really be assignedlo this division (i. e. King's Upper Coal Measures). The Weber rits and Maroon formation 

of the Tenmile district, for example, lack at least the distinctive color of the 

original Maroon, as does the corresponding series on E4gle River. 

As regards the general similarity of the two forma ions in Colorado, a similarity 

which is not obvious when only the section given by Po ell is considered, reference 

may be made to White's remark that his Lower Ca oniferous so resembles the 

underlying Uinta sandstone, and his Middle Carboniferus the Lower, that in some, 

cases it was difficult to distinguish them. -

Emmons states in the Tenmile folio that .the Weber formation of that area represents in a general way the Weber quartzite of Utah and the Lower Aubrey group of 

Arizona. This implies that the Aubrey sandstone, the Weber quartzite, and the 

Weber grits or lower Maroon, are of the same age. As a corollary they would 

probably represent the upper portion of the Uinta sandstone. There seems to be no 

reason why the upper and lower Maroon should not be made two distinct, possibly 

as to age two rather different, series. That the Weber grits and Maroon beds of the 

Tenmile district represent a higher horizon than the Maroon series of the Crested 

Butte district, seems to me altogether out of the question, because, for one reason, 

the fauna of the Weber grits is so similar to that of the lower Maroon that a correlation of them can probably be made on this evidence alone. That the Maroon series 
208 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

alone of the Tenmile district overlies the Maroon of the Crested Butte district seems 

also improbable and is contradicted by the nomenclature which Emmons employs. 

They are much rather to be considered equivalent. It would, therefore, furthermore 

result from Emmons's correlation that the Maroon of the Tenmile district (the upper 

Maroon of the Crested Butte district) occupies in this section the position of the 

Aubi-ey limestone of the Grand Canyon section and the Upper Coal Measures of the 

Uinta Mountain and Wasatch Mountain sections. I have elsewhere discussed the 

evidence which, while not conclusive, indicates that the Upper Coal Measure limestone of the Wasatch Mountains, the series called by the same name in the Uinta 

Mountains, and the Aubrey limestone, if not the Aubrey sandstone, of the Grand 

Canyon, should be correlated. Whether this series is represented by the upper 

Maroon beds of Colorado, or is represented in the State at all, are points upon which 

there is, so far, little direct evidence. The fauna found by Knight just over the line 

in Wyoming, as already remarked, suggests the Bellerophon limestone of the Uinta 

section. It is probable that these beds extend into Colorado. From the upper 

division of the Maroon in the Crested Butte quadrangle, and from the Maroon of the 

Tenmile quadrangle, scarcely any fauna deserving the name is known. The species 

that have been found, however, do not greatly disagree with the fauna of the Rico 

formation, which is supposed to represent the horizon of the upper Maroon. The 

Rico fauna is superficially somewhat similar to that obtained by Knight, but it is 

doubtful if a complete study of the latter will result in many instances of perfect 

specific identity. The Rico fauna is also very different from that of the upper 

Aubrey group of the Grand Canyon. Though the opinion is expressed with hesitation, it seems probable to me that the upper Maroon is not equivalent to the Upper 

Coal Measures of the Wasatch and Uinta sections (the Aubrey limestone of the Grand 

Canyon section), but joined with the lower Maroon (the Weber grits) is equivalent 

to the upper part of the Uinta sandstone and to the Weber quartzite. As to whether 

the Aubrey sandstone should be correlated with the Weber quartzite and lower 

Maroon series, as Emmons suggests, and with them be merged in the Uinta sandstone, 

or overlies the horizon of the Uinta sandstone, I am in doubt. The opinion has 

elsewhere been expressed that its horizon .was above the Uinta, but there is very 

little evidence upon this point. In any event it is not to the Weber grits, but to 

the Maroon series of the Tenmile section, or to both combined, that the Aubrey 

sandstone is probably equivalent. 

It is necessary, however, to give some further consideration to the tentative 

correlation of the Weber quartzite and the Maroon series of Colorado implied in the 

nomenclature employed by Emmons in the Leadville monograph and elsewhere and 

strongly enforced by a comparison of the Paleozoic series of Colorado and of the 

Wasatch Mountains. The fauna of the Weber quartzite is not well known. It has a 
RECAPITULATION OF PALEOZOIC TORMATIONS. 209 

brachiopod facies and is quite different from the fauna of the upper Maroon as 

exemplified by the Rico formation. It is, in fact, more like the fauna of the lower 

Maroon, but at the same time contains many novelties. No satisfactory estimate of 

this evidence can be made pending a careful study of the Weber fauna, which I hope 

to make at some future time. If the differences prove to be as important as they 

at first appear, the paleontologic correlation of the 111troon and Weber series would 

hardly be justified. It is possible to suppose that the Maroon series is absent in Utah, 

or that it, combined with the Weber limestone, is repesented by the upper portion 

of the Wasatch limestone and that its horizon is below the Weber quartzite. In 

that event the simultaneous occurrence of these two series in the Uinta Mountains 

would adequately account for the Uinta sandstone, even if it became necessary to 

refer to the Carboniferous the whole of that great series. On the other hand, a 

provincial influence may possibly be cited to account for the faunal peculiarities 

noted above and others corresponding to them. It is !necessary to consider that the 

waters of the Mississippian sea extended into Utah and possibly as far west as the 

Sierra Nevada, but in the elevation which preceded the first Pennsylvanian sediments 

this area must have been analyzed into a more compoSite geography. The Pennsylvanian faunas of Colorado have every appearance of being provincially related to 

those of the Mississippi Valley. The faunas of Pennsylvanian age found to the 

west and southwest, however, are sufficiently different and novel to suggest that the 

post-Mississippian elevation, if it did not establish a barrier between the Colorado 

and Utah seas, at least aroused influences sufficiently rtent to modify the faunas of 

the two areas. 

I.shall permit myself, before closing, a few words upon the nomenclature of the 

Carboniferous formations of Colorado, deprecating not so much that many names 

have been employed, but that some have been used in several senses and some have 

been imported from such a distance that the correlation intimated must have been 

originally doubtful and is now perhaps more than dotibtful. 

Of Mississippian age we have the Leadville limestone of central Colorado, the 

Millsap limestone of the Front Range, and the Ouray limestone of southwestern 

Colorado. While I believe that the Leadville, Millsap, and Ouray limestones, .so 

far as their Mississippian faunas are concerned, and for that matter the Red Wall, 

Wasatch,a and Madison limestones, can be correlated, the employment for them of 

distinct formational names seems to be a field matter of geologie propriety and to 

be judged only from that point of view. I think, however, that it would have been 

better, in view of the fact that the Leadville and Ouray limestones contain a fauna 

of Devonian as well as one of Mississippian age, if two formations, instead of one, 

a I mean only the lower or Mississippian portion of the Red Wall and Wasatch limestones and only the Red Wall 

limestone of the Grand Canyon. 

14364—No. 16-03-11 
210 CARBONIFEROUS FORMATIONS AND FAUNAS 01 COLORADO. 

had been discriminated. Indeed, had this fact been known when these formation 

names were first proposed it is possible that this course would have been adopted. 

For the Upper Carboniferous formations in the Uinta Mountains we have the 

Uinta sandstone, the Lodore group, the Red Wall limestone, and the Upper and 

Lower Aubrey groups. The names Red Wall and Aubrey are adopted from the 

Grand Canyon region, and, as the correlation of the Red Wall group is certainly 

erroneous and that of the Aubrey still doubtful, it appears to me that these names 

should be abandoned for this area. 

In central Colorado we have the Weber formation, the Maroon formation, and 

possibly the Wyoming formation. I take it that the use of the name Weber records 

the attempted correlation with the Weber quartzite of the Wasatch Range, by which 

formation the name was long preoccupied. It is doubtful if the Weber formation of 

Colorado can be correlated with the Weber quartzite of Utah, and certainly the two 

formations can not be considered the same geologic unit. Indeed, the Maroon 

formation is much more probably to be correlated with the Weber quartzite, 

a fact which perhaps finds partial expression in the later expansion of the term 

" Weber formation" in Colorado so as to include the lower half of the Maroon 

formation (vide the section of the Tenmile folio). This step has made the free use 

of the term " Weber" impossible in discussions of Colorado geology, and it seems to 

me that the name can not be too quickly laid aside in this connection. Endlich's term, 

"Arkansas sandstone," which was given to the more or less exact continuation into the 

Sangre de Cristo Range of the Maroon conglomerate of the Elk Mountains, seems 

to have been generally overlooked. We have now the Weber quartzite (of the 

Wasatch Mountains), the Uinta sandstone, the. Maroon conglomerate, the Arkansas 

sandstone, the Fountain formation, the Badito formation, and the Hermosa formation 

in use for parts or variations of the whole of about the same series of strata. All 

these names, and especially the Maroon and Arkansas, b will need careful consideration 

whenever a recension of this nomenclature or further detailed work involving this 

series is attempted. The variability of the Maroon beds is such, however, especially 

in view of the disconnected character of the areas of outcrops, as to justify, if not to 

demand, numerous local appellations. 

The opinion that in the Rocky Mountain region the Archean mountains of to-day 

represent island masses which have never been completely submerged has had the 

support of eminent geologists from the time that the Rocky Mountains first became 

the subject of geologic study,, and probably no one has given the matter more 

thoughtful investigation than S. F. Emmons, or more frequently and ably advocated 

this view. The conception, I think, has its origin in the very obvious overlap of many 

a As the term was first used in the Anthracite-Crested Bntte folio. • b The proposal of the Badito formation might have been avoided by more fully ascertaining the relations of the beds, 

so called, with the Fountain formation or the Arkansas sandstone. 
RECAPITULATION OF PALEOZOIC FORMATIONS. 211 

of the sedimentaries, especially of the Red Beds, upon the Archean, and their failure 

to cross the summits of the ranges, and was developed from the theory that the existing 

Paleozoic series (for it is only to Paleozoic time that these remarks refer) represents 

more or less uninterrupted sedimentation. Similarly, in discussions of the subject, 

Paleozoic time has been for the most part lightly touched upon and treated in general 

terms as if the conditions which prevailed were in the main uniform. Writing in 

1893 of the Micky Mountains of Colorado,a Emmons recognized five great marine 

transgressions, the post-Archean, the post-Algonkian, the late Paleozoic, the late 

Jurassic, and the post-Cretaceous. The first disturbanIce recognized subsequent to 

the Algonkian therefore is placed in the late Paleozoic, 4nd probably this conclusion 

is connected with the occurrence in the conglomerates of the Maroon formation in 

the Elk Mountains of pebbles containing Carboniferous fossils. Again, in the Tenmile folio, published in 1898,b he remarks that deposition was more or less continuous from the Upper Cambrian to the Trias, without evidence of any change in the 

relations of the sea bottom to the successive sediments, and that the first orogenic 

disturbance probably occurred in the Jurassic. 

Much evidence has now accumulated, however, tending to show that the Paleozoic 

series is anything but continuous and complete. This is indicated by the frequency 

of unconformities, sometimes by erosion, sometimes bx overlap, by the thinness of 

the remaining beds, and by their unequal distribution. That some of the intervals 

were of protracted duration is shown by the extent of the time break between 

apparently consecutive formations. The often much greater gaps indicated where 

different Paleozoic formations rest directly upon the granite is probably not so much 

the product of a single erosion period or a single transgression as the sum of a 

number of briefer ones and the resultant of a complicated series of movements. The 

permanence of these Archean islands seems to me to involve an a priori improbability, 

from the fact that they must have been reduced almos to sea level long before the 

immeasurable stretch of Paleozoic time had elapsed, so, that even slight oscillations, 

which during so long a period could hardly have failed to occur, would have sufficed 

to submerge them. 

That the Paleozoic series in Colorado is really an extremely disconnected one 

is shown by the number and extent of the gaps that are known to occur in it, and 

an intimation of this is to be fouud in the greatly reduced thickness of the preCarboniferous series, considered as a whole and in relation to areas farther east and 

farther west. The Cambrian so far as it is known is represented by only a few hundred feet, all of which belongs to the Upper Cambrian. All Lower and Middle Cambrian time appears to be unrepresented. The Ordoviciian must be approached with 

a Int. Geol. Cong., Comt. Rend., 5th seas. (1891), 1893, p. 404. 

b U. S. Geol. Bury., Geol. Atlas United States, folio 48, 1898. 
212 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

caution, because enough is known to raise many questions in regard to it, but too 

little to answer them. 

In the interior there is only the inconsiderable thickness of the Yule limestone, 

with perhaps the Parting quartzite, by which it seems possible that only a small 

portion of Ordovician time can be represented. In the Pikes Peak quadrangle Cross 

has discriminated the Manitou limestone, the Harding sandstone, and the Fremont 

limestone, all of Ordovician age. The faunas of the Harding and Fremont are those 

of the upper Ordovician (Trenton), and I doubt if the lowest Ordovician is represented. Another gap would then exist between the highest Cambrian and the lowest 

Ordovician bed. Cross notes an unconformity of overlap between the Harding sandstone, and I can not believe that this unconformity, or the movements which caused 

it, were restricted to the immediate region of the Pikes Peak quadrangle. It can 

probably safely be said of the Ordovician that it is now represented by fragments, 

and that deposition was affected (and possibly the present existence governed) by 

contemporaneous movements. The Upper Silurian appears to be entirely wanting 

in Colorado, and most of the Devonian as well. The latter period is very doubtfully 

represented by the Parting quartzite, whose age is not definitely known, and certainly 

by the lower part of the Ouray and Leadville limestones, whose fauna belongs to the 

upper Devonian. No rocks were formed, then, from the end of Ordovician to 

toward the end of Devonian time, or if formed they were also swept away again. 

The, upper portion of the Ouray and Leadville limestones carries a MisSissippian 

fauna, and while the faunal break is what one might almost call absolute, the lithological indications are that sedimentation was continuous from the Devonian. But 

the sharp faunal break and the fact that apparently in places, as along the Front Range 

the upper limestone with the Mississippian fauna exists without the lower, would 

-seem here again to indicate an overlap and possibly an interval of erosion or nondeposition. The upper portion of the Ouray and Leadville limestones is of Mississippian age. Its upper limit is marked by an erosional unconformity, and the paleontological evidence indicates that only lower Mississippian time is represented. The 

middle (?) and upper Mississippian, and probably part of the Pennsylvanian, are 

wanting through erosion or nondeposition. The lower part of the Hermosa (and the 

Molas formation where present), which succeeds the Ouray, I am disposed to correlate 

with the Weber shale and the Weber limestone, which follow the Leadville limestone. 

Their deposition appears to have been consecutive with that of the rest of the Hermosa 

and with the lower Maroon and the Weber grits, which I also correlate. At the same 

time the Maroon sediments transgress the Weber series, and in fact all the earlier 

Paleozoics, and in the Crested Butte quadrangle and elsewhere lap over upon the 

Archean. There is also a certain individuality about the lower Hermosa and the 

Weber faunas, while the conglomerates of the lower Maroon contain pebbles of 
RECAPITULATION OF PALEOZOIC FORMATIONS. 213 

limestone with Upper Carboniferous fossils. The fauna of the pebbles, however, 

is not that of the Weber limestone (and of course not that of the Leadville), but of the 

Maroon itself. Between the Hermosa (= the lower Maroon) and the Rico (supposed 

to equal the upper Maroon) another interval may exist. This is indicated by the faunal 

change between the Hermosa and Rico formations, by the much greater thickness of 

the Hermosa in Sinbads Valley, and the presence in it upper portion of a fauna different from that of the typical Hermosa. Evidence favorable to this, however, may 

exist in the color change to the dark-red Maroon beds,' and in the great number and

1 size of the Archean bowlders which their conglomerates contain. Between the Rico 

and the upper Maroon formation on one hand, and the brick-red Dolores of the San 

Juan, the Triassic of Aspen and elsewhere in Colorado, and the Wyoming formation 

of the Tenmile district on the other, another important interval, probably accompanied by erosion, seems to have occurred. This is indicated by the probable 

absence of the Permian and possibly of portions of the Pennsylvanian series between 

the Rico and Dolores beds, and by the overlap of the " Triassic " upon the Archean 

at a number of points, and is implied in the suggested correlation of the section in the 

Uinta Mountains with that of central Colorado. Owing to it the whole Carboniferous 

series in the Uinta Mountains above the Uinta sandstokie is missing elsewhere in Colorado,a and the upper Maroon from a thickness of 2,500 feet in the northern part of the 

Crested Butte quadrangle is greatly reduced in the ruthern, becomes only 300 feet 

in the San Juan (Rico formation), and is apparently missing altogether in the Dolores 

River region. I may have misread the paleontologic and other evidence in some 

cases, and have erred in correlating the Colorado sections with one another and with 

those of the Uinta and Wasatch mountains (though the latter correlation is certainly 

borne out by numerous collateral circumstances), but the existence of an unconformity 

and time break following the Leadville horizon can hardly be questioned. Now, it 

seems to me that the conditions under which neither erosion was carried forward nor 

sedimentation going on (except for abyssal tracts which can probably be left out of 

the discussion) must have been rather exceptional, and that their existence over large 

areas ana permanence through protracted periods of time must have been of rare 

occurrence. The apparent conformity in. Colorado in local sections of Paleozoic 

formations showing important differences of geological age would then indicate 

either protracted erosion and complete baseleveling or slight elevation and shorter 

periods of exposure to atmospheric forces. Somewhat as it is true that the oldest 

mountains are the lowest, may it almost be said that the greatest unconformities, 

those involving the most extensive territory and the longest periods, are least apparent. Where the areas which have been tilted are extensive, the angular unconformity between the existing and the succeeding sediments is often imperceptible. Where 

a unless they are represented in the northern part of the State by sediments now supposed to belong to the MaroonWeber series. 
214 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the elevated surface has been reduced by protracted erosion to a base-level, erosional 

unconformity in local exposures is largely obscured. 

I shall venture to say but little about Paleozoic time earlier than the Carboniferous. It seems to me, however, that the evidence, briefly and partially submitted, indicates that conditions were not uniform in successive epochs, and that 

sedimentation was not continuous during Paleozoic time; that it was not only 

interrupted, but one might almost say was reversed. Indeed, the evidence coming 

before me seems to indicate uniform contemporaneous conditions, sediments, and 

faunas over remarkably extensive areas in the West, with changes to other contemporaneous conditions equally widespread. It is possible that some of the present 

Archean areas were islands during Cambrian time, yet too much weight should 

not attach itself to the siliceous character and basal conglomerate, for the wide 

distribution of moderately coarse conglomeratic material not linearly along a coast 

but apparently in an areal sheet is a common geologic occurrence. On the other 

hand, the different calcareous beds I conceive, accepting the common interpretation, to represent moderately deep clear waters. I can not believe in the formation of. reasonably pure calcareous sediments close to an Archean land mass save 

as an exceptional occurrence. The overlap of a limestone series upon the A rchean 

or Algonkian, as noted in the case of the Ouray limestone of the San Juan region, is 

significant in indicating important hypsometric changes. 

I would conclude, from the foregoing considerations, not that there were no 

land masses during Paleozoic *time, but that they were independent, and not necessarily continuous from period to period; and that the consideration of geographic 

conditions should be epochal, while to speak of them in connection with Paleozoic 

time as a whole is fallacious. But the accumulation of many more facts, both in 

stratigraphy and in paleontology, is necessary to complete the evidence. While perhaps an opinion has been expressed regarding early Paleozoic conditions stronger and 

in more general terms than the facts really warrant, it is my belief that during Leadville time at least the questionable Archean islands were submerged beneath a widespread Mississippian sea. This opinion rests chiefly upon the persistent lithologic 

and paleontologic characters displayed by the rocks of this period. The Waverly 

horizon occurs in a large number of our Western States. It is nearly everywhere 

a limestone formation, and everywhere characterized by essentially the same fauna. 

This is quite true of the Waverly horizon of Colorado—the Leadville limestone. It 

seems likely that the proximity to land, if such existed, would be indicated by a 

change in the sedimentation if not in the fauna. Nowhere does this seem to be the 

case in Colorado. The small isolated area of Paleozoic outcrop in Manitou Park and 

the long strip in the Mosquito Range are frequently accounted for as having been 

bays and inlets, but the character of the fauna seems to be essentially the same as 
RECAPITULATION OF PALEOZOIC FORMATIONS. 215 

that of open water, with similar calcareous sediments. For my own part, these and 

similar phenomena, such as the fragmentary occurrence of the Sawatch quartzite and the 

Yule limestone described by the Van Diests, near San Luis, are more naturally 

explained as remnants of strata that once were continuous over the Archean. In the 

matter of faunal characters the Leadville limestone at Leadville and the Millsap 

limestone of the Front Range possess characters in common which distinguish them 

in some degree from the other Mississippian faunas of Colorado; but since they occur 

on opposite sides of the long Archean tract of the Colorado range, it seems to me very 

doubtful whether this fact can be taken as indicating local conditions due to adjacence 

to land masses. On the other hand, the difference of the Ordovician section along 

the Front Range and in the interior may afford ground for argument in favor of the 

existence of a barrier between them during Ordovician time. Yet it would little 

surprise me, if a careful study of the faunas of both areas were made, to find that 

the difference is not so great as now appears, and that it is due rather more to lack 

of uniformity in what has been removed than to lack of uniformity in what was 

originally deposited. 

Attention has several times been called in geologic works to the thinning visible 

throughout the Paleozoic series in passing eastward from central Utah to the Front 

Range. This is noticeable even in following the different Paleozoic formations in 

the State of Colorado. I would attribute this not to a normal thinning or compression of the larger series, but to the removal or nondeposition of sediments at 

many horizons. An instance in point seems to be the absence in Colorado of the 

upper part of the Mississippian portion and part of the Pennsylvanian portion of 

the Wasatch limestone of Utah.a 

It is a rather significant fact that so many of the formations thin toward the 

east, and seems to indicate that about the present position of the Front Range, or 

possibly east of it, exists a permanent line of weakness which has been repeatedly 

elevated, eroded, and submerged. This has a certain bearing upon a question which 

has often recurred to me as needing explanation. If, as many believe, mountain or 

land masses and marine basins have in their general outlines always existed, and if, 

as seems little doubtful, the elastic rocks which form masses of the continental 

bodies have as their ultimate source the original Archean basement, together with 

such additional supply as is afforded by volcanic extrusions, or obtained from the 

atmosphere in the formation of carbonates, it must follow that the original Archean 

continents were of as large size as the existing ones, unless the land masses were 

then much higher or the marine basins shallower. The latter proposition seems, 

indeed, a probable one. If, however, the Archean masses represent permanent 

a The reality of this instance depends of course upon the correctness of my correlation of the Colorado rocks with 

those of Utah. 
216 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

areas of weakness, which were continually being pushed up and eroded, a constant 

source of material would be afforded by comparatively limited tracts. There certainly seems to be evidence to favor such a hypothesis with regard to the Archean 

area represented, by the Rocky Mountains of Colorado, and possibly similar 

conditions existed, with regard to the other notable Archean areas. Somewhat as a 

corollary to this would be the supposition that these areas were not permanently 

above water, and though repeatedly elevated were sometimes depressed. In the 

Rocky Mountains these movements seem to have involved such large surfaces that 

their effect upon the strata is often not apparent, except as indicated by overlap or 

by the comparison of sections widely separated from one another. The great 

amount of disturbance which the strata in Colorado have undergone would also aid 

in concealing local evidence of unconformity. 
FAUNAL EVIDENCE AND COR ELATION. 

MISSISSIPPIAN. 

In Colorado, and generally throughout the West the Upper and Lower Carboniferous faunas are well differentiated. In Colorad o the only Mississippian horizon is that of the Leadville limestone and its equivaJ ents, the Ouray and Millsap 

limestones. This formation contains at many points a characteristic Upper Devonian 

fauna in its lower part, and at the top a fauna equall distinctive of Carboniferous 

time. This is true of the Crested Butte region, the an Juan region, and the beds 

at Salida. At some points only the Devonian fauna s known, and at others only 

the Mississippian; but in view of the scanty character of our collections from many 

of the areas, the expectation is reasonable that if caref 1 search be made both faunas 

will be found at some of the points at which only one s now known. 

The Mississippian fauna of the Leadville limeston • represents the early portion 

of Mississippian time, and is related to the faun'a which occurs with such wonderful 

persistency throughout the West. It is closely similar to the fauna of the Cuyahoga 

shale of Ohio and the Chouteau limestone of Missouri, and this relationship has been 

generally recognized. Of this further proof need ha dly be offered than the faunal 

lists themselves. The evidence both of species an of genera is quite clear in 

indicating the early Mississippian. 

In Colorado we have no upper Mississippian fa nas. This is true of a large 

part of the western country, even where early Missis ippian rocks are known. On 

the other hand, at a few points, unmistakable faunas f the Genevieve period have 

been found, so that there is no reason to believe tha these rocks and faunas have 

never been deposited in the W est. In Colorado the e is satisfactory evidence that 

the Leadville limestone was followed, though probab y not directly, by a period of 

elevation and erosion; and I believe that the absence of Genevieve faunas, both in 

Colorado and elsewhere in the West, is in large meas re accounted for through the 

same circumstance. In the Leadville limestone, ther fore, so far as its fossils have 

come into my hands, I believe that Genevieve time is not represented, nor probably 

Keokuk or upper Burlington. The Leadville fauna, a cording to my interpretation, 

represents, in the Carboniferous, Kinderhook, and po sibly lower Burlington time. 

I have spoken of the Leadville fauna as a unit. I fact, collections from different 

disconnected areas show rather strong local groups of species. This is no doubt in 

part due to local differences in the condition of enviro ment. It is in part the result 

of the scantiness of many of our collections. Mississi pian faunas have been found 

in Colorado, in the San Juan region, in the Crested B tte quadrangle, in the Aspen 

district, in the Leadville district, at Salida, at Canyon in the Pikes Peak quadrangle, 

217 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

218 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

at Perry Park, and in the Upper Carboniferous (?) conglomerate of Larimer County. 

I shall proceed to speak separately of each local group of faunas. 

SAN JUAN REGION. 

ColleVtions were made in the San Juan region at nine localities (stations 2379, 

2380, 2381, 2382, 2384, 2385, 2386, 2387, 2388), and contain 32 species. The material 

was obtained, part of it in place (from the top of the Ouray limestone), part from 

cherts and cherty limestones lying loose upon areas of Ouray outcrop, and part from 

chert bowlders included in the unconformably overlying red shale of the Hermosa 

formation. The fauna is in every case essentially the same. The local faunas of 

this region represented in our collections are exhibited in the following table: 

TABLE La—Table showing distributson of Mississippian species in the Ouray limestone of the San Juan region. 

2379. 2380. 2381. 2382. 2384. 2385. 2386. 2387. 2388. Total. 

CcELENTERATA. 

Zaphrentis tantilla X x 2 

Zaphrentis? sp. a X X 2 

Menophyllum ulrichanum X X x X X 6 

Syringopora surcularia X ECHINODERMATA. 

Rhodocrinus sp X 1 

Platycrinus sp x x 2 BRYOZOA. 

Fenestella serratula? x x 2 

Fenestella cf. filistriata X 1 

Fenestella sp x X 2 

Batostomella sp X 1 

Fistulipora? sp x 1 BRACHIOPODA. 

Rhipidomella pulchella X x X X 4 

Orthothetes inaNualis x x x x x 5 

Chonetes illinoisensis X X 2 Productella concentrica X 1 

Productus semireticulatus var X X X X 4 

Productus parviformis X 1 

Productus hevicostus X x 2 

Spirifer centronatus x X X X 4 

Spirifer peculiaris? x (?) 2 

Spiriferina solidirostris? X X X X 4 

Seminula sp X 1 

Eumetria marcyi? X X 2 

Camarotcechia metallica X - 1 PELECYPODA. . Crenipecten hallanus x 1 

Myalina arkansasana? X X X 3 

Myalina keokuk X 1 • GASTEROPODA. 

Platyceras paralium? X x X 3 

Orthonychia formosa? x ' 1 

Straparollus utahensis x 1 

Bellerophon sp x 1 TRILOBITA. 

Phillipsia peroccidens x 1 

a For a description of the localities indicated by number in this table see locality register, pp. 519-532. 
 

 

 

 

 

 

 

 

FAUNAL EVIDENCE AND CORREL TION. 219 

This fauna is so closely similar to that from the VV a atch limestone of Utah and 

the Madison limestone of the Yellowstone National Pa k that detailed comparisons 

stratigraphic, together with the direct and indirect pal 

Though the age of the fossils from station 2385 is not ntirely unassailable, yet the 

sasana?. 

imperfectly identified, with an early Mississippian 

can well be omitted. A somewhat alien feature is the 

The identification is not certain, but the as °elation of this form, thus 

ontologic evidence, raises it 

fauna is reasonably sure. 

resence of Myalina arkanalmost above suspicion. This form, to which it will e necessary to refer later, 

while possibly belonging to a somewhat distinct horiz n, nevertheless forms a part 

of and is of the same geological age as the regular Our Mississippian fauna. 

CRESTED BUTTE QUADRANGL 

The fossils here considered were collected in conne tion with the areal work for 

the Anthracite-Crested Butte folio.a Ten local collec ions (stations 2350 to 2359) 

and 15 species constitute the available data. The local representation and distribution of species can be seen in the accompanying table. 

TABLE II. b—Table showing distribution of Mississippian species in t e Leadville limestone of the Crested 

Butte district. 

2350. 2351. 2352. 2353. 23 . 2355. 2356. 2357. 2358. 2359. Total. 

CELENTERATA. 

Zaphrentis tantill a 

Zaphrentis ? sp. a 

3yringopora aculeata 

Byringopora surcularia 

x 

x 

X x 

X 

X x 

X 

f 

2 

1 

1 

BRACHIOPODA. 

Rhipidomella pulchella 

Drthothetes innqualis 

Productus semireticulatus var 

X 

1 

1 

1 

3pirifer centronatus 

3pirifer centronatus var 

3pirifer peculiaris ? 

3yringothyris carteri 

x X X 

X x X 

X 

X 

6 

1 

1 

1 

GASTEROPODA. 

3traparollus luaus 

-itraparollus ophirensis 

Loxonema ? sp 

Bellerophon sp 

x 

x 

x 

X 

X X 

x 

3 

1 

2 

1 

The most diagnostic assemblage of species occurs :t station 2358. The assignment of this fauna to a period in the Mississippian o der than the Genevieve will 

hardly, I think, excite objection. The other local colle tions are less extensive and 

in general less diagnostic, but so far as they are signiii cant indicate essentially the 

a U. S. Geol. Surv., Geol. Atlas U. S., folio 9, 1894. 


b For a description of the localities indicated by number in this table ee locality register, pp. 519-532. 

220 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

same geologic age and agree with the stratigraphic evidence which assigns them to 

the same formation. Taken as a whole, this fauna is closely related to that of the 

San Juan region, and like it is allied to the Waverly fauna of the Wasatch limestone 

and the Madison limestone. Nine of its fifteen species occur in the San Juan region, 

while the others are found associated with the San Juan species in other areas. 

ASPEN DISTRICT. 

The Aspen collections are very scanty. They were obtained from the Leadville 

limestone in that vicinity by Mr. Manuel and A. Lakes, and were originally examined 

by C. D. Walcott, whose identifications, quoted from Lakes's paper,a are as follows: 

1. Syringopora sp. Turtleout Park, Aspen Mountain. 

2. Zaphrentis sp. Turtleout Park, Aspen Mountain. 

3. 	Sponges in oolitic limestone. Head of Keno Gulch, Aspen Mountain, above the "Grand Pacific" 

mine. 

4. Pleurotomaria sp. Turtleout Park, Aspen. 

5. Straparollus sp. Turtleout Park and Frying Pan. 

6. Euomphalus sp. Frying Pan Creek, near Aspen. 

The following table, based upon my own determinations, shows the local faunas 

and the specific distribution: 

TABLE IIIb.—Table showing distribution of Mississippian species in the Leadville limestone of the Aspen 

district. 

2362. 2363. Total. 

CcELENTERATA. 

Zaphrentis ? sp. a 2 

Syringopora aculeata 1 

BRACHIOPODA. 

Productus cf. pustulosus 

GASTEROPODA. 

Straparollus ophirensis x (?) 2 

Straparollus utahensis (?), (?) 

Loxonema 9 sp x 1 

The geologic age of this fauna is not entirely apparent independently, though it 

contains suggestions of the Waverly faunas .of the Wasatch Mountains and the Yellowstone National Park. As it occurs at the same horizon (in the Leadville limestone) as the more extensive faunas of the Crested Butte and San Juan areas, their 

evidence can safely be employed to supplement that which is intrinsic. 

•.Colorado State School of Mines, Bienn. Rept. for 1886, 1887, p. 60. 

b For a description of the localities indicated by number in this table see locality register, pp. 519-532. 

• 
FAUNAL EVIDENCE AND CORRELATION. 221 

LEADVILLE REGION. 

The material studied by me is that collected in the early eighties in the course 

of the areal work for the Leadville monograph.a Since that time no new collections 

have been made, though it is possible that the old ones have suffered in some slight 

degree from loss. The fossils under immediate consideration came from the Blue or 

Leadville limestone, which is eponymous of this region. It comprises ten species, 

from seven localities, a meager and unsatisfactory fauna. The fauna and its different 

local facies can be seen from the accompanying table: 

TABLE IV. 5—Table showing distribution of Mississippian species in the Leadville limestone of the Leadville 

district. 

2372. 2373. 2374. 2375. 2376. 2377. 2378. Total. 

CCELENTERAT 

Zaphrentis ? sp. b 

BRACHIOPODA. 

Orthothetes innqualis 

Spirifer sp. a 

Spirifer sp. b x 

Seminula subquadrata ?6 

Eumetria woosteri 

9 

X 

X 

X 

(?) 

1 

5 

3 

(?) 

2 

1 

x x 

(?) 

x 

PELECYPODA. 

Myalina arkansasana ? 

Conocardium sp 

GASTEROPODA. 

Straparollus cf. spergenensis x 

All of these collections are recorded as from the Blue or, as it has since been 

called, the Leadville limestone; and with slight exceptions the physical character of 

the matrix and the fossil faunas which they carry are correspondingly similar. "The 

only fossils obtained from this horizon were found in the extreme upper part of the 

formation, either in the limestone itself or in chert nodules, which are found scattered over its weathered surface." C This statement occurs in the Leadville monograph, and the following specific list, drawn up by R. P. Whitfield, is appended 

(page 66); 

Euomphalus sp. cf. Eu. spergenensis. Spirifera (Martinia) lineata. 

Spiriferina sp., probably new, resembling Sp. Spirifera rockymontana. 

kentuckyensis. Streptorhynchus crassus (crenistria). 

Athyris subtilita. Cyathophylloid corals, resembling Zaphrentis, or 

Pleurophorus oblongus. Cyathaxonia cynodon. 

Productus costatus. 

a Geology and mining industry of Leadville, Colo., by S. F. Emmons: U. S. Geol. Surv., Mon., vol. 12, 1886. 

h For a description of the localities indicated by number in this table see locality register, pp. 619-532. 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 66. 
222 CARBONIFEROUS FORMATIONS. AND FAUNAS OF COLORADO. 

The differences between my list and that in the Leadville monograph must in 

part be charged to the element of personal equation in the matter of identification, 

in which the unfortunate condition of preservation in the present case allows unusual 

latitude, and in part probably to losses from the collection since the publication of 

the report. My table shows the present condition of the collection. 

list but not in mine, for of these species nothing has come to hand which would 

rifera lineata, 

in any likelihood receive these identifications. My reasons for differing from the 

published identifications are in most cases given in the description 'of the species. 

In a previous statement I had 'reference to the species 

and possibly also Spirifera rockymontana, which occur in the earlier 

Produetus eostatus, SpiFrom the faunal list above quoted the conclusion was drawn that, the Blue limestone is of Mississippian age. " While most of the forms are common to the Coal 

Measures of the East, the first mentioned is there found in the Lower Carboniferous. 

For this reason, and because this form and the SPirferina do not occur in any of the 

higher beds, it seems justifiable to assume that this horizon represents the Lower 

Carboniferous of this district." a Although 'this conclusion is, I believe, a correct 

one, it hardly seems justified by the faunal list, which is composed chiefly of Upper 

Carboniferous species, even though there are present a form of Euomphalus like 

Etc. spergenensis and a new species of Spiriferina (which is said to resemble the 

Coal Measure Sp. kentuckyensis) not found in the beds below, unless, indeed, the 

term Lower Carboniferous is not employed as a division of the time scale equivalent to Mississippian, but simply indicates the lower part of the Carboniferous, an 

equivocal and altogether objectionable usage. 

Of the general age of the Blue limestone as belonging to the Lower rather than 

to the Upper Carboniferous I have little doubt. The fact hinted at in the monograph, that there is a distinct faunal break (brought out more strongly in my lists 

than in the earlier ones) between the Blue limestone and the formation next above, 

iliana 

is certainly significant. The presence of a retzioid of the type of 

occurrence, however, the absence of characteristic and common Upper Carboniferous 

conclusive; but as it is, the value of this evidence is somewhat diminished. This 

would, if the determination were based upon adequate material, be almost 

Eumetria vern,euspecies, the affinity and sometimes identity with Mississippian forms of such as are 

present, together with the stratigraphic and zoological relations of this fauna with 

other Mississippian faunas of Colorado, seem to me to be satisfactory evidence of its 

Mississippian age at least. 

I will proceed to consider the fauna, species by species, in its bearing upon the 

age of the Blue limestone as Lower rather than Upper Carboniferous. Orthot/etes? 

sp. more nearly resembles forms occurring in the lower portion of the Mississippian 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 66. 
FAUNAL EVIDENCE AND CORRELATION. 223 

series than the familiar Pennsylvanian Derbya crassa or even the Neo-Mississippian 

•forms. The Semi/n/0a present resembles the Chester form S. subquadrata more than 

S. subtilita, common in the Upper Car boniferous, but the evidence of the present 

material in its relation to both these species can only be regarded as slight. Spirifer 

sp. is of a type which is unknown in our Upper Carboniferous faunas, and one so 

rare that I am acquainted with but two others similar to it---Spiraferina acicubfera 

Rowley, which was found at the very base of the Mississippian series, viz, in the 

Louisiana limestone of the Chouteau group of .Missouri, and Spirifer sch,ucherti 

Rowley, found in the Lower Burlington limestone at Louisiana, Mo. Regarding 

Eumetria? sp., as previously stated, if this fossil could be definitely identified as 

Eu. marcyi or Eu. altirostris, the evidence thus afforded would be of considerable 

moment. As I personally regard the identity of this shell with one or other of the 

species mentioned as highly probable, I still attach importance to its presence in this 

fauna. Ifyalina arkansasan,a? seems to be more nearly allied to the Chester form 

than to any occurring in the Upper Carboniferous, not even excepting Naiadites 

elongates. Euomphahts cf. spergenensis has its closest and indeed its only close allies 

in the Mississippian series, and I can recall no form in the Upper Carboniferous, 

and especially no common form, to which it could be referred. The other species of 

the Leadville have essentially no weight in the present discussion. The intrinsic 

evidence, therefore, is almost invariably in favor of referring the Leadville limestone 

to the Lower Carboniferous, and its cumulative force is considerable. But the age 

of the Leadville limestone at Leadville need not be, and indeed should not be, 

determined independently of the Carboniferous faunas of other areas. 

Geographically and in the correspondence of geologic section the Paleozoic 

deposits at Leadville are closely related to those of Aspen. The fauna from the 

Leadville limestone at Leadville, however, is less similar to that of the Leadville 

limestone at Aspen or in the Crested Butte quadrangle than to that of the Paleozoic 

exposures of the Front Range. Indeed, only a single species, doubtfully identified, 

of those at Leadville occurs either at Aspen or in the Crested Butte quadrangle, and 

but two are found to be common to the Leadville and the San Juan, Crested Butte, 

and Aspen faunas. As I shall subsequently point out in detail, a much closer relation 

exists between the Leadville fauna and that of the Front Range Mississippian, and 

the faunas of this group are rather markedly different from those of central Colorado.a 

Neither can the age in the Mississippian of this typical Leadville fauna be considered 

apart from the evidence of the related faunas which I have yet to consider. Therefore the discussion of this point will be deferred to a somewhat later and more 

advantageous place. 

a While these statements are true for the collections in hand, the latter are so scanty and presumably so imperfectly 

represent the whole fauna that they may not accurately express the real faunal relations. 
2.24 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

SALIDA. 

Only two Mississippian collections are present from Salida, and only four species 

are represented. The correlative force of this fauna, therefore, is very slight indeed. 

As, however, it was derived from the horizon of the Leadville limestone, and as all 

the species save one occur in the Crested Butte quadrangle, and that one, a Seminula, 

is similar to a species occurring in the Madison limestone, it will be safe to unite 

these localities with the Leadville limestone fauna. It should be remarked, however, that its affinities appear to be with the group of faunas obtained at Aspen and 

in the San Juan and Crested Butte areas rather than with the faunas of the typical 

Leadville limestone at Leadville, or those of the Front Range. 

TABLE V. a--Table showing distribution of Mississippian species in the Leadville limestone of Salida and the 

Monarch district. 

2360. 2361. Total. 

CcELENTERATA. • 

Syringopora aculeata X 

Syringopora surcularia x 1 

BRACHIOPODA. 

Spirifer centronatus x x 

3eminula claytoni X 1 

CANYON. 

The fossils in this group are from the vicinity of Canyon, and were collected 

by T. W. Stanton. Part of the material came from the Harding's quarry locality, 

and were mentioned by C. D. Walcott,b being identified as Spirifera rockymontana 

and Athyris subtilita. In view of the geologic proximity of the localities and the 

identity of the faunas, these collections might appropriately have been considered 

with those collected by Whitman Cross from the Pikes Peak quadrangle. I have, 

however, kept them separate. The fauna, which is preserved in chert, comprises 

only six species, and was derived from two localities. The following table shows its 

distribution and' local representation: 

a For a description of the localities indicated by number in this table see locality register, pp. 519-532. 

b Geol. Soc. Am., Bull., vol. 3, 1892, p. 157. 
FAUNAL EVIDENCE AND CORRELATION. 225 

TABLE VI.a—Table showing distribution of Mississippian species in the Millsap limestone in the vicinity of 

Canyon. 

2366. 2370. Total. 

BRACHIOPODA. 

Orthothetes insaqualis (?) 

Spirifer centronatus 

Spiriferina solidirostris x 

Cramena subelliptica var. hardingensis 

(?) 

' 2 

' 1 

PELECYPODA. 

Myalina arkansasana? 

GASTEROPODA. 

Pleurotomaria ? sp. a 

Considered by itself the age of this fauna is not very add- from the species collected, but so far as they go the indications are for the Mississippian epoch, and the 

lower part of it. This fauna is related to that of the Millsap limestone of the Pikes 

Peak quadrangle, to the Mississippian limestone of Perry Park, and also to the 

Leadville limestone of Leadville. It will be more satisfactory to consider the combined evidence from the faunas of all these areas than to review each separately. 

PIKES PEAK QUADRANGLE. 

The collections considered in this group were made by Whitman Cross in the 

course of stratigraphic work for the Pikes Peak folio. They came from the Millsap 

limestone at its exposures in Garden Park in the southern part of the quadrangle. 

The fauna, which consists of but four species from as many localities, is shown in 

the following table: 

TABLE VII.ot—Table showing distribution of Mississippian species in the Millsap limestone in Garden Park 

in the Pikes Peak quadrangle. 

2365. 2368. 2369. 2371. Total. 

BRACHIOPODA: 

Spirifer centronatus x x X x 4 

Spiriferina solidirostris? X 1 

Cransena subelliptica var. hardingensis I. x x X 3 

PELECYPODA. 

Myalins arkansasana '9 X 

In its geographic and faunal relations the localiti s in the Pikes Peak quadrangle 

are essentially the same as those from near Canyo , and the same comments that 

were offered there apply here also. 

a For a description of the localities indicated by number in this to • le see locality register, pp. 519-532. 

14364 No. 16-03----1 
226 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PERRI PARK. 

Only two collections from Perry Park have come to hand. One of these was 

made by Whitman Cross, the other was examined through the courtesy of W. T. Lee. 

The following table shows the distribution and faunas by localities: 

TABLE VIII.a—Table showing distribution of Mississippian species in the Millsap limestone in Perry Park. 

2367. 2389. Total. 

BRACHIOPODA. 

Orthothetes inuqualis 

Spirifer centronatus 

Spirifer sp. b 

Spiriferina solidirostris x 

Seminula subquadrata 9 

Crannna subelliptica var. hardingensis 

PELECYPODA. 

Myalina arkansasana? 

Streblopteria media 

CRUSTACEA. 

Leperditia sp 

Beyrichia sp 

Though all too scanty, the faunal evidence indicates the closest relation as 

existing between the Perry Park outcrops and those about Garden Park and Canyon. 

Every species but one of those found at the latter locality appears also at the former. 

The relation of these faunas with those found at Leadville and the other Colorado 

areas will be discussed after considering the last somewhat peculiar collection of 

Mississippian forms. 

LARIMER COUNTY. 

This fauna is based upon impressions made from casts of shells contained in 

some pebbles in the conglomerate' occurring 32 miles west and 18 miles north of 

Greeley, Colo. The collection was made by Prof. L. C. Wooster some time prior to 

July, 1880. The locality .(station 2364) is in Larimer County, east of the Front 

Range, apparently near the point at which the Cache la Poudre River deboudies 

from the mountains, or possibly somewhat north of that stream. The horizon is 

probably that of the Red Beds. Among the impressions obtained in the manner 

described is that upon which White based the species Eumetria woosteri. Associa Fora description of the localities indicated by number in this table see locality register, pp. 519-532. 

b Cannon, writing in 1892 (Colorado Sci: Soc., Proc., vol. 4, pp. 224-234), describes the occurrence of Carboniferous 

fossils in loose chert bowlders widely distributed along the Front Range. The character of the rock and the circumstance 

that no fossiliferous Carboniferous strata, except the Millsap limestone, are known along the eastern flank of the range, 

save in the Sangre de Cristo Mduntains and near the Wyoming line, make it probable that this formation was their source. 

The occurrence in this case is similar to that which furnished the fossils described by White, except that the latter were 

found in an ancient conglomerate and these in recent gravels, which, however, may possibly be partially formed from the 

destruction of the conglomerate. 
FAUNAL EVIDENCE AND CORRELATION. 227 

ated with this species White cited Spirifer rockymontanus Marpou, Spiriferina 

ph,yllum, rudis 

octoplicata 

Measures.b The list of species identified by me is as follows : 

Sow., 

CCELENTERATA. 	

White and St. John, and he refers the whole to the age of the Coal 

Spirigera subtilita Hall, Hemipronites crenistria 

Spirifer sp. la 

Phillips, and AxoSeminula humilis? . Zaphrentis? sp. C. 

Eumetria woosteri. BRACHIOPODA. 

DASTEROPODA. 

Orthothetes 

Pleurotomaria? sp. b. Spirifer centronatus. 

With material which is not only scanty but preserved in the fashion that this is, 

the same precision is not attainable as in more abundant normal examples, and it will 

be noticed that I have departed from White's identifications in many instances. My 

reasons for doing so are stated in the description of species in each case. Considered 

apart from the form described as Eametria woosteri, the evidence is not conclusive; 

but the absence of characteristic Coal Measure forms and the presence of such as 

Spirifer centronatus and Seminula humilis directs a decision favorable to the Lower 

Carboniferous age of the fauna. 

Eumetria woosteri, although its generic position on internal and strictly generic 

characters can not be ascertained, is a form to which nothing similar has yet been 

recorded from Upper Carboniferous strata, but which is very closely allied to several 

species occurring some in the Kinderhook and others in the St. Louis and Chester 

divisions of the Lower Carboniferous, and forming together a group of shells 

peculiarly Mississippian in expression. It may be that subsequent discoveries will 

enlarge the range of Eumetria and the other types involved, but at present at least 

the evidence, coincident in every species, indicates the Lower Carboniferous age of 

this fauna. I think, too, that the age indicated is basal Lower Carboniferous. 

Eumetria woosteri appears to be on the whole more closely related to the Kinderhook than to the Chester species of _Eumetria, and I am disposed to believe that it 

will prove a synonym of Eametria altirostris. Strands of evidence more or less 

tenuous proceeding from the species Orthothetes inmqualis?, Spirifer centronatus, 

and Seminula humilis all tend to the same conclusion, and justify the provisional 

reference of this fauna to a position somewhere in the Kinderhook or the Osage division of the Mississippian. Most of the species which I have identified are found also 

in the Millsap limestone farther south or in the Leadville limestone at Leadville. It 

seems very likely, therefore, that the rock from which these impressions were made 

was derived from the same horizon that furnished the fossils from those localities. 

The sharpness of the detail of the impressions and their nature as such even suggests. 

b U. S. Geol. Geog. Surv. Terr., Cont. to Pal., Nos. 2-8, author's edition, July, 1880, p. 134. 
228 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

that the original bowlders were siliceous or cherty, in which material all our fossils 

belonging to the faunas mentioned are preserved. 

SUMMARY. 

The Lower Carboniferous faunas of Colorado can be separated on intrinsic 

evidence into two groups, the first of which embraces,those from the Ouray limestone 

of the San Juan region and the Leadville limestone of the Crested Butte, Aspen, 

and Salida localities, the other embraces those from the Leadville limestone at 

Leadville, the Milisap limestone of Canyon, Garden Park, and Perry Park, and the 

Red Beds conglomerates near the northern border of the State. Where small collections are made at different points from a large and varied fauna it would follow 

that comparatively few species would be common to any two of them. This seems 

true, both as to condition and result, of our Mississippian collections from Colorado. 

On the whole, however, both groups of faunas show considerable homogeneity. 

The chief question is how far they are distinct from each other. The fauna of the 

San Juan and Crested Butte collections is clearly that which has several times been 

described from the Wasatch limestone of Utah and the Madison limestone of the 

Yellowstone Park and Montana. It occurs also in the Chouteau limestone of 

Missouri and the Waverly group (Cuyahoga shale) of Ohio, and its geological age is 

probably chiefly upper Kinderhook and lower Burlington. It may at least safely be 

asserted that it is older than the Genevieve period. The fauna of the other group 

of localities has a more unusual facies. Considering the meager character of the 

collections, this fauna is rather unusually homogeneous. The faunas from Garden 

Park and Canyon are practically identical. Five of the eleven species found at Perry 

Park occur also in Garden Park, and these five include the abundant species. Four 

of the seven species from the Red Beds conglomerate occur at Perry Park or at 

Garden Park. Five of the nine species found at Leadville were obtained in the Front 

Range beds, and only two occur in the far more abundant faunas of the San Juan and 

Crested Butte regions. At the same time, though the Leadville fauna is much more 

similar to those of the Front Range than to those of central and southwestern 

Colorado, there are certain well-marked peculiarities, as, for instance, the abundance 

along the Front Range of Cranwna subelliptica var. hardingensis, which is not known 

at Leadville. The Front Range group of faunas, therefore (including Leadville), is 

rather peculiar—to what extent may be gathered from the fact that from a total of 

nineteen species but four occur in the San Juan and Crested Butte group, the resemblance being especially with the faunas of the San Juan region. The fossils at Canyon, Garden Park, and Perry Park occur in cherty bands or nodules, bright red on 

the outer surface, but whitish, purplish, or buff within. From their occurrence and 

preservation there is reason to believe that the impressions from Larimer County 

were made from cherty bowiders. Most of the Leadville fossils occur in siliceous 
FAUNAL EVIDENCE AND CORRELATION. 229 

segregations of nearly black color, while many of those from the San Juan region 

are inclosed in.cherty of a nearly white tint. Thus the collections having this rather 

puzzling facies are characterized by their cherty matrix. While the fauna of the 

'San Juan, Crested Butte, and other areas occurs at a number of points both north, 

east, south, and west of central Colorado, I do not recall the Front Range association 

of species from any other point: It is the grouping of these species rather than the 

species themselves that is novel. Considered individually, each member of this fauna 

th,etes inequalis, S_pirifer centronatus, S_piriferina solidirostris, Seminula humilis, 

is found elsewhere or has close allies, especially in the early Mississippian. Orthoand 

Streblopteria media are found in the Waverly faunas. The nearest allies of Spirifer 

sp. b occur the one at the very base of the Kinderhook, the other at the base of the 

Burlington in the Mississippi Valley.. Cran.Tna subetliptica var. hardingensis is 

allied to upper Devonian and Waverly forms. Eumetria woosteri might be either 

rata? 

lower or upper Mississippian. 

sippian, not far, in fact, from that of the other group. The geologic evidence tends 

the whole, I should estimate the horizon of this fauna as in the Eo- or Meso-Missisunmistakably to the same conclusion. The identity of the Leadville limestone of 

are Genevieve species, but have allied forms in the early Mississippian. On 

Straparollu,s cf. spergenensis and Seminula subquadLeadville with beds at Aspen and in the Crested Butte quadrangle has been rather 

generally asserted by geologists than doubted by anyone, yet the fauna of the 

typical Leadville limestone is distinctly unlike that of the Crested Butte quadrangle. Its fauna allies it closely with that of the 1VIillsap limestone. The faunas 

of the Millsap limestone along the Front Range are correlated with that of the Leadville limestone at Leadville by paleontologic evidence. The latter is correlated with 

those of the Leadville limestone at Aspen and in the Crested Butte quadrangle by 

stratigraphic evidence, and these again with the Ouray limestone of Colorado by 

paleontologic evidence. The two groups of Mississippian faunas of Colorado, both 

by stratigraphy and paleontology, are placed at about the same horizon. Their 

difference in facies is partly due to the incompleteness of our collections, but partly 

to the selection of local environment, which was possibly somehow connected with 

cherty segregation. Most authors have considered central Colorado to have been the 

site of a number of large islands occupying the position of the present Archean 

mountain masses. One asks the question whether the peculiarities of the faunas at 

Leadville and the Front Range are connected with these conditions. This is possibly 

the case. But it should be borne in mind that this fauna is a marine one, so that its 

habitat could hardly have been a landlocked basin. Besides which, all the species 

found occur elsewhere themselves or have closely allied forms. The physical condition could•not have been in the nature of a barrier, for the faunas of the Elk and 

San Juan Mountains are found to the north, south, and east of this area. So far as 
 

2 30 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

I can see, the peculiarities of the Leadville and Front Range facies indicate merely 

contemporaneous variation in local marine conditions, or slight difference in geologic 

age. They have absolutely no necessary bearing upon the question of land and 

water areas in Colorado during their deposition, but from the persistent lithologic 

character of this horizon as a nearly pure limestone we may infer that land areas of 

any size could not have been near at band. 

TABLE IX.—Summary table for comparing the distribution of Mississippian species in the San Juan, Salida, 

Crested Butte, Aspen, Leadville, Perry Park, Pikes Peak, Canyon, and Larimer County areas. 

San - ju ,. Salida. Crested 

Butte. Lead- Perry Pikes. Can- Larimer Aspen. vile. Park. Peak. yon. County. 

CcELENTERATA. 

Zaphrentis tantilla 2 5 


Zaphientis ? sp. b 


Zaphrentis ? sp. c 


Zaphrentis ? sp. a 2 2 2 


Menophyllum ulrichanum 5 


Syringopora aculeata 1 1 


Syringopora surcularia 1 


. ECHINODERNATA. 

Rhodocrinus sp 1 


Platycrinus sp 2 


BRYOZOA. 

Fenestella setTatula ? 2 


Fenestella cf. fllistriata 1 ... 


Fenestella sp 2 


Batostoraella sp 1 


Fistulipora ? sp 1 


BRACHIOPODA. 

Rhipidomella pulchella 


Orthothetes insequalis 4 (?) 1 (?) 


Chonetes illinoisensis 2 


. Productella concentrica 1 - -.-


Productus semireticulatus var 4 1 


Spirifer sp a 


Spirifer sp b 


Syringothyris carteri 


Seminula claytoni 


Seminula subquadrata ? 


Seminula humilis? 


Eumetria woosteri (?) : 


Productus parviformis 1 


Productus cf. pustulosus 1 


Productus lnvicostus 2 


Spirifer centronatus 4 6 


Spirifer centronatus var 1 


Spirifer peculiaris? 2 


Spiriferina solidirostris ? 4 


Seminula 9p 1 


Crannna subelliptica var. hardingensis 2 


Eumetria marcyi? 2 


Camarotcechia metallica , 1 


1 
 

 

FAUNAL EVIDENCE AND CORRELATION. 231 

TABLE IX.—Summary table for comparing the distribution of Mississippian species in the San Juan, Salida, 


Crested Butte, Aspen, Leadville, Perry Park, Pikes Peak, Canyon, and Larimer County areas—Cont'd. 


San 

Juan. Salida' 

Crested 

Butte. Aspen. vine. 

Lead- Perry 

Park. Pikes 

Peak. Canyon. Larimer 

County. 

PELECYPODA . 

Crenipecten hallanus 

Streblopteria media 1 

Myalina arkansasana 9 3 2 1 1 1 

Myalina keokuk 1 

Conocardium sp 

GASTEROPODA. 

Platyceras paralium " 3 

Orthonychia form(isa ? 

Straparollus luaus 3 

Straparollus ophirensis 2 2 

Straparollus utahensis 1 (?) 

Straparollus cf. spergenensis 

L)xonema? sp 2 1 

Pleurotomaria ? sp. a -

Pleurotomaria ? sp. b 1 

Bellerophon sp • 1 1 

CRUSTACEA. • 

Phillipsia peroccidens 1 

Leperditia sp 

Beyrichia sp 1 

PENNSYLVANIAN. 

Very far the larger portion of our collections from Colorado belong to the Upper 

Carboniferous. They come mainly from three distinct and separate areas—from the 

San Juan area, from the Crested Butte quadrangle and its vicinity, and from Leadville and its adjoining district—but we have a few fossils from all the Upper Carboniferous areas of Colorado except the Front and Sangre de Cristo ranges. 

UINTA MOUNTAIN REGION. 

About the paleontology of the Uinta Mountains in Colorado very little can be. 

said. The large faunas cited in Powell's Geology of the Uinta Mountains a came from 

beyond the borders of the State, in Utah, though the same horizons, characterized 

by the same faunas, doubtless extend to the eastern end of the range. The faunas 

identified by White, however, are different from any of the formational faunas known 

in Colorado. We have collections from but three stations in the Uinta Mountain 

area in Colorado, and the faunas in each case are so scanty as to be without weight in 

the matter of correlation. The species collected are as follows: 

Euph,ernus subpapillosus is from near the South Fork of the Vermilion and near 

the east base of Diamond Peak, Colorado (station e189). These fossils were not found 

a U. S. Geol. Geog. Surv. Terr., Powell's Rept. Geology Uinta Mountains, 1876. 
232 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

in place, and occur in the form of internal casts. Their probable horizon is the 

Bellerophon limestone, at the. top of the Upper Aubrey group. The identification 

is by C. A. White, who refers to the specimens on page 92 of Powell's Uinta 

Mountains volume. 

Lophoph,yllum, preundum and Rhombopora lepidodendroides are from station 

2191, overlooking Yampa River. The locality of this collection is not very definite, 

and the horizon is unknown, but without much doubt is lower than the Bellerophon 

limestone, almost certainly somewhere in King's Upper Coal Measure series. I can 

not find that these fossils have ever been referred to in literature. 

Prismopora triangulata and Spiriferina kentueleyensis are from Yampa Plateau, 

northwestern Colorado (station 2330). The identification of Prismopora triangulata 

is that of C. A. White, who figured this specimen in 1880.a I can not find that this 

occurrence has been elsewhere mentioned. His figures, somewhat enlarged, are 

reproduced on Pl. I of the present volume. He states that the' horizon is the 

middle division of the Carboniferous series, which he correlates with the Lower 

Aubrey group. Unless I am mistaken in supposing the Uinta sandstone to represent the Maroon formation, this horizon is not that called Middle.Carboniferous by 

the other Hayden geologists, but is considerably higher. These fossils are inadequate 

not only to indicate more than the Upper Carboniferous age of the rocks furnish., 

ing them, but also to supply a means of correlation with other sections in Colorado. 

GRAND RIVER REGION. 

We have Carboniferous collections from a number of points in the Grand River 

region of Colorado, but they are in most cases quite scanty. The most complete 

collections are those made at Glenwood Springs, but, unfortunately, few of these 

can be satisfactorily located in the standard geologic section. It is probable that 

they came from the Weber limestone or its equivalent. Our collections are 7 in 

number, and contain a fauna of 25 species. The distribution of this fauna by 

localities can be seen in the accompanying table: 

a U, S. Geol. Geog. Surv. Terr., Cont. to Pal. (author's edition), 1880, p. 131, pl. 33, figs. 3.-3e. 
 

 

 

 

FAUNAL EVIDENCE AND CORRELATION. 233 

TABLE X.a—Table showing distribution of Pennsylvanian species in the vicinity of Glenwood Springs. 

2193. 2193a. 2326. 2329. 2329a. 2329b. Total. 

CCELENTERATA. 

Lophophyllum profundum (?) (?) 

HELMINTHA. 

Spirorbis sp - x 1 

BRYOZOA. 

Rhombopora lepidodendroides x 

BRACHIOPODA. 

Lingula sp 

Orbiculoidea sp 

Rhipidomella pecosi x 1 

Orthotichia schuchertensis x 1 

Derbya crassa • X 1

Chonetes 1] emingi x x x 3 

Chonetes geinitzianus x 1 

Productus inflatus x 1 

Marginifera ingrata x 1 

Marginifera muricata x 1 

Spirifer ca:rneratus x x 2 

Spiriferina kentuckyensis x 1 

Seminula, subtilita x x 2 

Cleiothyris orbicularis x 1 

GASTEROPODA. , 

Aclisina stevensiana? x 1 

Loxonema parvum? x 1 

Strophostylus cf. nanus x . 1 

Soleniscus cf. paludiniformis x 1 

Pleurotomaria? ef. carbonaria 'x 1 

Worthenia? sp. h x , 1 

Phanerotrema sp x 1 

CRUSTACEA. 

Beyrichia sp X 1 

Stations 2326, 2329, and 2329a can safely be referred to the Weber formation,b 

since they occur from 100 to 200 feet above the Leadville limestone. Unluckily, 

these are the most restricted in the number of species of the entire collection, but 

they show the Pennsylvanian age of this horizon, and, as far as they go, agree with 

the fauna of the Weber formation found elsewhere. The faunas of 2193a and 2329b 

also agree fairly well with the Weber fauna, and perhaps represent that horizon. 

The collection from 2193a is of interest in that it supplied the specimens of Orthotichia the first instance of the occurrence of Orthotichia in North 

America, unless Orthis resupinoides Cox is incorrectly referred to Sellizophoria. 

The fauna from 2193 is also an interesting one. It consists chiefly of very small 

gasteropods not found in the other collections at this locality, or indeed elsewhere in 

a For a description of the localities indicated by number in this table, see locality register, pp. 519-532. 

b As the Weber is defined in the Crested Butte folio; this is the Weber shale or base of the Weber formation of the Tenmile and Leadville districts. 
234 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Colorado. However, possibly the same species occur in the unidentifiable forms 

preserved as internal casts in chest, which I have cited simply as minute gastropods 

in the lists from the Leadville, San Juan, and Crested Butte areas. These shells are 

all of extremely small dimensions, a circumstance which, taken with their not very 

perfect preservation, has made their specific identification difficult and uncertain. 

Into this geographic division also probably fall four collections made near the 

junction of the Grand and Eagle rivers. Station 2190 is on Grand River; 1 mile 

below Eagle River. Here was obtained only Conularia crustula ?. I can find no 

reference to this collection in published reports, and its horizon is not known. 

Probably this material was collected by Marvine; whose report upon the Grand 

River region, owing to his death, was never published. 

From station 2192 we have only Pleurophorus angulatus Q. This locality, which 

could not have been far from station 2190, is described on pages 242 and 243 of the 

Hayden annual report for 1873,a and the fossils were collected from bed No. 12 of 

the section. The horizon seems to be near the top of the Weber shales, or just at the 

base of the Maroon formation. The other fossils mentioned besides the Pleurophorus 

have not come to hand. 

Of station 2325 all that is known is that it is located on Grand River in north 

western Colorado. The description of station 2324 is still less exact, the label reading " Ranch west of Camp 59." The latter collection appears to have been made by 

Marvine, and the fossils probably were not included in any published report. 

From station 2324 we have Chonetes mesolobus, Chonetes flem,ingi, ilfargimfera 

haydenensis, Marginifera muricata, Spirifer cameratus, and Seminula subtilita. 

From station 2325 appears only Jfarginifera haydenensis. The latter species is not 

found elsewhere in Colorado, save only at station 2324, and the preservation is so 

exactly alike in the two lots as to arouse the suspicion that they are really parts of 

the same original collection. In point of preservation these fossils, which are 

weathered free and more or less covered with a reddish coating, are different from 

any of our Colorado material, and I suspect that the labels may be wrong, and that 

they may not have come from Colorado at all. 

Really the scanty collections from stations 2288 and 2289, together with the few 

collections made in connection with the stratigraphic work of the Leadville monograph and the Tenmile folio, should be considered here; but I find it more advantageous to include them in the discussion of the Leadville fossils. From station 

2288 we have only Spirifer rockyrnontanus, and from station 2289 only SpirVer 

rockymontanus and Spirifer boonensis ?. With this scanty and unsatisfactory 

collection the paleontologic evidence from the Grand River region concludes. 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874. 
FAUNAL EVIDENCE AND CORRELATION. 235 

ELK, MOUNTAIN REGION. 

The Crested Butte quadrangle is that whose northwestern corner is made by the 

intersection of the one hundred and seventh meridian and the thirty-ninth parallel. 

It is a 15-minute quadrangle.. The areal geology, which forms part of the subjectmatter of the Anthracite-Crested Butte folio.,a was surveyed by G. H. Eldridge, by 

whom most of the collections studied were made. Two Upper Carboniferous formations are recognized in the Anthracite-Crested Butte folio. The lower one is called 

the Weber formation and the other the Maroon conglomerate. The Weber formation consists of shales and thin limestones, and varies in thickness from 100 to 550 

feet. The Maroon conglomerate measures 4,500 feet, and is subdivided into two 

portions. The lower division, which is 2,000 feet thick, is derived from the waste 

of older sedimentary deposits; the upper, which contains 2,500 feet, is largely 

derived from the waste of granites. Both series contain thin limestone beds. 

Thirty-three collections in all were obtained from the Upper Carboniferous beds 

of the Elk Mountain region, and thirty of these were made in connection with the 

areal work of the Anthracite-Crested Butte folio. These are from stations 2290­

2300, 2302-2308, 2310-2321. The following stations occur in the Weber limestone: 

2307, 2308, '2312-2316, and 2320. The remainder occur in the lower portion of the 

Maroon conglomerate, though the position of 2302 and 2303 is not quite certain. No 

fauna is at present known from the upper Maroon. The fossils from 2306, however, 

can not properly be included with the Maroon fauna, since they were derived from 

pebbles in one of the Maroon conglomerates where their presence is only secondary. 

In the accompanying table the local faunas are set down, and in the two final columns 

the composite faunas of the Weber formation and of the lower portion of the Maroon 

conglomerate. 

a U. S. Geol. Surv., Geol. Atlas U. S., folio 9, 1894. 
236 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XI.a— Table showing the distribution of Pennsylvanian species in the Crested Butte district, and their 

range, so far as known, in the Weber limestone and lower portion of the Maroon formation. 

• 2244 2245 2280 2290 2291 2292 2293 2294 2295 2296 2297 22982299 2300 2302 2303 2304 2305 2301 

--,--

PROTOZOA. 

Fusulina cylindrica ... 

CcELENTERATA. 

Lophophyllum profundum 

Campophyllum torquium 

Chmtetes milleporaceus 

Cladopora sp 

Monilipora prosseri 

BRYOZOA. 

Prismopora serrata, 

BRACHIOPODA. 

Derbya crassa 

Chonetes flemingi 

Chonetes mesolobus 

Productus semireticulatus var. herrn°. 

sanus 

Productus gallatinensis 

Productus cora • ... .... ... 

X 

Marginifera muricata 

Marginifera wabashensis var 

Spirifer boonensis / / • • • ..... 

Spirifer rockyraontanus 

Spirifer cameratus 

Squamularia perplexa 

Spiriferina kentuckyensis 

Seminula subtilita x x x .... .... x X 

Hustedia mormoni 

Pugnax utak x 

Dielasma bovidens 

PELECYPODA. 

Aviculopecten ? interlineatus - - • • •• - ' 

SCAPHAPODA. 

Dentalium subluve ..... .... ... 

GASTEROPODA. 

Euomphalus catilloides 

Bellerophon crassus ... ... .... .... .... .... .... ... 

Minute gasteropods - .... .. - . - - -

CRUSTACEA. ' 

Phillipsia trinucleata 

a For a description of the localities indicated by number in this table see locality register, pp. 519-532. 
FAUNAL EVIDENCE AND CORRELATION. 237 

TABLE XI.—Table showing the distribution of Pennsylvanian species in the Crested Butte district, and their 

range, so far as known, in the Weber limestone and lower portion of the Maroon formation—Continued. 

Weber Maroon 2307 2308 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 lime- formaPROTOZOA. 

Fusulina cylindrica x 

Fusulina cylindrica var. ventricosa ? 

CCELENTERATA. 

Lophophyllum profundum 

Zaphrentis gibsoni 

Campophyllum torquium 

Amplexus sp 

Chaatetes milleporaceus 

Cladopora, sp 

Monilipora prosseri 

ECHINODERMATA. 

ArchEeocidaris cratis x 

Eocidaris halliana ? 

HELMINTHA. 

Spirorbis arietina 

Enchostoma sp 

BRYOZOA. 

Stenopora tuberculata 

BRACHIOPODA. 

Derbya crassa 

Chonetes fiemingi 

Chonetes mesolobus 

Productus semireticulatus var. hermosanus 

Productus inflatus 

Productus cora 

Marginifera lasallensis 

Marginifera muricata 

Marginifera wabashensis var 

Marginifera ingrata 

Spirifer rockymontanus 

Spinier cam eratus 

Squamularia perplexa 

Spiriferina campestris 

Spiriferina kentuckyensis 

Seminula subtilita 

Hustedia mormoni 

Pugnax utah 

Dielasma bovidens 

PELECYPODA. 

Aviculopecten occidentalis 

Aviculopecten ? interlineatus 

Myalina cuneiformis 

SCAPHAPODA. 

Dentalium subinve 

GASTEROPODA. 

Euomphalus catilloides 

Bellerophon crassus 

Minute gasteropods 

stone. tion. 

1 4 

1 

x 

1 2 

1 

1 

1 

x x 

x 

x 2 3 

x 2 1 

5 

1 3 

1 

x 	 1 5 

1 2 

2 

2 

1 

1 

1 

10 

3 

2 

(?) 	 (?) 

x 

1 

1 

2 

CRUSTACEA. 


Phillipsia trinucleata (?) 

238 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The fauna of the Weber formation, with its Fusulinas and other species, is 

clearly of Upper Carboniferous age. Without a sharp break between the upper and 

lower faunas there is yet a certain distinct lack of agreement. The Weber formation ­

has a total of 21 species and the Maroon a total of 28 species, yet they have only 8 

species in common. The same facts can .be expressed in a different and somewhat 

less relative manner. The two formations have a combined fauna of 41 different 

species. Of these, 8 are common, and 33 peculiar to one formation or the other. 

The fraction-48T, or the percentage 19.51, may be taken as expressing in a general 

way the degree of affinity of the two faunas. This, however, fails in accuracy, for in 

the case of species common to both formations no account is taken of instances of 8 

and 5 occurrences in one, balanced by only 1 in the other. Such faunal peculiarities as 

exist are brought out so clearly by the table that it seems hardly necessary to indicate 

them here. It may be remarked, however, that the echinoids are not. present in 

the Maroon conglomerate, nor any of the Mollusca, save only 1 species, in the Weber 

limestone, and that Productus inflatus, liarginifera lasallen8i8?, AL ingrata, Spirifer 

rockymontanus,and.Spiriferina campestris are nearly or quite peculiar to the Weber, 

and Chonetes mesolobus, Productus semireticulatus var. hermosanus, P. cora, _Margin,ifera muricata, Spi2Ver cameratus, Squamula/ria perplexa, Spiriferina kentuckyensis, Seminula subtilita, Hustedia mormoni, and Pugnax utah, to the Maroon. 

In working over these collections my attention was attracted to the circumstance 

that the large Producti and the smaller species, chiefly belonging to the genus 

ilfarginifera, seldom appeared in the same local assemblage. In some instances, 

however, the 3farginiferae and the large Producti do so occur, and in the case of 

stations 2312 and 2313 the two types were found stratigraphically within 10 feet of 

each other. The selective agency, therefore, whether stratigraphic or environmental, 

was not unvarying in its action. 

Mention is made in the Anthracite-Crested Butte folio of the occurrence of 

Upper Carboniferous fossils in pebbles of the Maroon conglomerates. The collection from station 2306 seems to be an instance of this. The fauna consists of 

Ch,mtetes milleporaceus, Productus cora, llfarginVera wabashensis var., ,S'quamularict 

perplexa, Seminula subtilita, and Hustedia mormoni, and it is surprising to note that 

its affinities are distinctly with the other indigenous faunas of the Maroon, and not 

with those of the Weber formation or of the Leadville limestone. 

Collections from three stations not made in connection with the areal work of 

the Crested Butte quadrangle are included in the table. These are stations 2244, 

2245, and 2280. The collection from station 2244, which is on Rock Creek, was 

made by J. J. Stevenson, and probably is from the hoi izon of bed No. 1 in his Rock 

Creek section.a A considerable fauna is cited by Stevenson as occurring in this bed, 

a U. S. Geog. Geol. Surv. W. 100th Mer., Rept., Vol. III, p. 362. 
FAUNAL EVIDENCE AND CORRELATION. 239 

only two species of which, however, remain. The stratigraphic horizon appears to 

be in the Maroon conglomerate, and the fauna mentioned by Stevenson agrees rather 

with that of the lower member of the Maroon than with the Weber. But, as I have 

already pointed out in the stratigraphic division of my report, the occurrence in the 

middle of Stevenson's section of duplicated Cretaceous beds inspires a doubt as to the 

mutual relations of the rest of the section. 

The material from station 2245 appears to have been collected by W. H. Holmes, 

but there is evidently a mistake in the locality- given in the National Museum Register, and I can find no published section with which it is connected. The locality, 

though uncertain, is with great probability in the Elk Mountains. The evidence 

of the fauna 'would tend to place the horizon of this collection in the Maroon 

conglomerate. 

Station 2280 is in the section made by Peale at a point southeast of Italian Peak, 

described on page 251 of the [Seventh] Annual Report of the United States Geological and Geographical Survey of Territories for 1873, 1874. The collection, which 

includes six species, comes from bed No. 11 of the section, and Peale cites the same 

forms under different but synonymous names. The stratigraphic horizon is clearly 

in the Maroon series, and the fauna also agrees with that of the lower Maroon. • In 

the final columns of the table, which show the composite faunas of the Weber and 

Maroon formations, stations 2244 and 2280 but not 2245 are included. 

SOUTH PARK AREA. 

Just as in the Elk Mountain region practically all the collections studied came 

from a limited area, that of the Crested Butte quadrangle, s• in the South Park 

region all the fossils examined were obtained in its northern portion, the Leadville 

district. 

The localities represented in the accompanying table are 31 in number, and are 

chiefly in the Tenmile and Leadville districts. The Tenmile district lies between 

meridians 106° 8' and 106° 16' 8" W.. and parallels 39° 22' 57" and 39c 30' 25" N. 

It does not strictly form apart of the South Park region. The arc a of the Leadville 

district is somewhat less precise, but includes the mineral-bearing tract near Leadville, in the northern part of the Mosquito Range. • 

The geology of the Tenmile district is described in the Tenmile folio a and that 

of the Leadville district in the Leadville monograph. The areas of the Tenmile and 

Leadville districts are geographically almost continuous. The same rocks occur in 

both, and the geology of both was described by S. F. Emmons. It has therefore 

seemed to me best to consider the faunas of both areas in the same place. 

a U. S. Geol. Surv., Geol. Atlas U. S., folio 48, 1898. 

b U. S. Geol. Surv., Mon., vol. 12, 1886. 
240 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The same formations occur in both areas, as I have already said, but the nomenclature adopted in the Tenmile folio differs from that of the Leadville monograph, 

which preceded it by twelve years. The Upper Carboniferous formations of the 

Leadville monograph are called the Weber shales, the Weber grits, and the Upper 

Coal Measures. In the Tenmile folio these are called the Weber shales, the Weber 

grits, and the Maroon formation. In fact, the Weber shales and Weber grits are 

united as the Weber formation. Above the Weber grits a third formation is discriminated as the Wyoming formation, whose age may be Carboniferous, but is not 

definitely known. In addition to this, two of the linaestones included in the sandstones and conglomerates of the Weber and Maroon formations proved of sufficient 

local importance to receive distinct names. The Robinson limestone below and the 

Jacque Mountain limestone above are assigned as the bounding beds of the Maroon 

formation.. It will be noticed that the geologic sequence here is similar to that in 

the Crested- Butte quadrangle, but though the same names have been employed in 

some cases, and apparently the same formations differentiated, the names are used 

in a somewhat different sense, a course which is to be deprecated as very confusing. 

For the lowest Pennsylvanian horizon in the Leadville and Tenmile districts 

the name Weber shale has been adopted, as I have already said. The formation in 

this area has a thickness of about 300 feet, and consists of calcareous and argillaceous 

shales alternating with quartzitic sandstone. The Weber grits have an average 

thickness of 2,500 feet, and consist of sandstones and conglomerates, with a few thin 

shales and doloniitic limestones. The source of this material is said to be the 

Archean. The Maroon formation is similar to the Weber grits in constitution, but 

contains a larger proportion of shales and limestones. The latter are nonmagnesian. 

Its limits are taken as the Robinson limestone below and the Jacque Mountain limestone above, and its thickness 1,500 feet. The Wyoming formation consists of 

brick-red sandstones 1,500 feet in thickness. No fossils are known from it. 

Twenty -eight collections were obtained in the Leadville and Tenmile districts, in 

connection with the work for the .Tenmile folio and Leadville monograph. These 

are stations 2250-2277, inclusive, of which 2260, 2261, 2272, 2273, 2274, 2275, and 

2276 are from the Tenmile district, the rest from the Leadville district. Stratigraphically these have been distinguished as lower, middle, and upper Weber, Robinson 

limestone, and Maroon formation. 'The lower Weber corresponds to • the Weber 

shale of the two reports above mentioned, the middle and upper Weber to the 

Weber grits formation. The Robinson limestone forms the division between the 

Weber grits and the Maroon formation: The Maroon is, in a general way, the same 

as the Upper. Coal Measures of the Leadville monograph and the upper division of 

the Maroon of the Crested Butte folio, the lower division of the Maroon finding 
FAUNAL EVIDENCE AND CORRELATION. 241 

its equivalent in the Weber grits of the Leadville and Tenmile districts. To the 

Weber shales belong collections from stations 2250, 2251, 2252, 2253, 2257?, 2258, 

2264, 2267, and 2277; to the middle Weber those from stations 2262, 2263; to the 

upper Weber stations 2269, 2272, 2275, and 2276; to the Robinson limestone stations 

2260, 2261, 2273, and 2274; and to the base of the Maroon formation station 2270, 

Stations 2254, 2255?, 2259?, 2265, 2266, and 2268 are referred merely to the Weber, 

and the horizon of 2256 and 2271 was not definitely determined. Of these, all the 

collections from the Robinson limestone and all but one from the upper Weber are 

derived from the Tenmile district, from which we have no collections representing 

either the lower or the middle Weber. 

Most of this material was studied by R. P. Whitfield, who made the paleontological determinations for the Leadville monograph. It has all been reworked and 

the identification's brought into harmony with those of the other Colorado collections. 

I have agreed with the identifications recorded in the Leadville monograph in some 

cases, but in others have ventured to depart from them. It would hardly be profitable, especially since I am in accord with Whitfield's determinations of the ages of 

the different formations, to make a comparison of the two series of, faunal lists further than this, adding that some of the material appears to have been lost since it 

was originally studied. In addition to what appear to be losses from the collection, 

many of the local lots have been thrown together, so that frequently a number of 

different locality labels were found accompanying a single set of specimens. It was 

of course impossible to separate these into their original groups, and no attempt was 

made to do so. In the following table are included not only the species collected 

during the field work for the Leadville monograph and Tenmile folio, but also those 

from two- other stations in the same neighborhood, 2281 and 2288, both of which are 

believed to belong in the Weber shale: 

14364—No. 16-03 16 
242 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XII.a—LTable showing distribution of Pennsylvanian species in the Leadville and Tenmile districts, and 

their range in the lower, middle, and upper Weber formation, Robinson limestone, and Maroon formation. 

22501 22512252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 226' 

— -

ECHINODERMATA . 

A rchEeocidaris cratis 


ArchEeocidaris ornata .... ... 


Archwocidaris trudifer ? 


Eocidaris halliana? .... ........ .... .... ... 


BRYOZOA. . 

Rhombopora lepidodendroides 


Fenestella sp . 


Polypora cf. distincta . 


Polypora whitei var. insculpta • . 


Polypora n. sp .... .... .... .... .... .... .. 
 • Septopora delicatula , .x 

Stenopora cestriensis ........ .... .... .... 

BRACHIOPODA. . . 

Lingula. carbonaria ........ . .... .. . . 

Lingula? sp. (indeterminable) . , . ---• --- ---- --- •••• ---- •—• ---- ---- -----

Orbiculoidea manhattanensis 

Rhipidomella pecosi 

Derbya crassa 

Meekella striaticostata 

Chonetes geinitzianus 

Productus semireticulatus var. hermosanus - x . .. ... . 

Productus inflatus x ---- ---. x x .... .... x .... (?) .... .... ... .... ... x .... x x ... 

Productus cora 

Productus nebraskensis 

Productus sp. b 

Marginifera ingrate 

Spirifer rockymontanus 

Spirifer sp. (indeterminable) .. . ... .... .... .... .... .... ..... x ... 

Squamularia perplexa • 

Seminula subtilita - - - - X X x (?) ...... . . x .... ... 

PELEcYPonA. 

Aviculopecten rectilaterarius . . . .. .... 


Acanthopecten carboniferus ..... ... ....... .... .... .,.. .... ... 


Myalina wyomingensis 


Aviculopinna? peracuta 


Nucula ventricosa ? ....... . ..... . ..... .... .... .... .... x .... ... - .. - - -. - - •• - - - -


Nucula sp. (indeterminable) 
 ' 

GASTEROPODA. 

Minute gasteropods .... 

o 

CRUSTACEA. 

Beyrichia sp x .. 

Leperditia sp - Bairdia cf. cestriensis . .... .... .. . .... .... .... .... .. ' • - - ' ' ' 

Kirkbya sp - •-;- ---- •••• •--- •.:::... -• 

Phillipsia trinucleata -

Phillipsia major 

For a description of the localities indicated by number in this table, see locality register, pp. 519-532. 
FAUNAL EVIDENCE AND CORRELATION. 243 

TABLE XII.—Table showing distribution of Pennsylvanian species in the Leadville and Tenmile districts, and 

their range in the lower, middle, and upper Weber formation, Robinson. limestone, and Maroon formation— 

Continued. 

I Weber Robin- Weber .„,, Weber son Maroor 2270 22711 2272 2273 2274 2275 2276 2277 2281 2288 2289 lower, —d upper. lime- base. , dle. I stone. i 

ECHINODERMATA. 

,rchwocidaris ornata .1 

BRYOZOA. 

thombopora lepidodendroides 

BRACHIOPODA. 

,ingula carbonaria 

iingula tighti x 1 

Angula ? sp. (indeterminable) 1 

orbiculoidea manhattanensis 2 

thipidonaella pecosi , 1

)erbya crassa 2 

,honetes geinitzianus 3 

'roductus semireticulatus var. hermosanus x 2 1 1 

'roductus infiatus x x X 5 1 

'roductus cora (?) x x X 2 

'roductus nebraskensis x x 2 

farginifera ingrata . 

pirifer boonensis? . x 

pirifer rockymontanus • x x x x 

quamularia perplexa (?) ... 1 1 

, eminula subtilita x x x................. 3 2 3 

PELECYPODA. 

Lviculopecten rectilaterarius .1 

I:ntolium ? sp x 1 

(yalina wyomingensis 1 

Lviculopinna ? peracuta 1 

lacrodon obsoletus x 1 

lacrodon tenuistriatus 9 x • 'leurophorus occidentalis ? (?) 1 

GASTEROPODA. 

uconispira taggarti x 1 

'hanerotrema cf. grayvillense x 

Vorthenia ? marcouiana ? .. . .... . ... ..... ... ..... .... .... x . I 

Vorthenia ? sp. a x 1 

,oxonema sp x 1 

trophostylus remex x 

tulimorpha chrysalis (?) 

finute gasteropods . 1 

tellerophon crassus x X 1 

tellerophon percarinatus ? x 1 

tellerophon sp. (indeterminable) 

'atellostium raontfortianum (?) 

CEPHALOPODA. 

. )omatoceras sp - / 
 CRUSTACEA. 
 ' 

'hillipsia major 
244 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The preceding table shows the local distribution of species of the Upper Carboniferous strata of the Leadville region. The last five columns show their range in 

the five stratigraphic divisions which have been recognized. They indicate two 

somewhat different and contrasting, though both Upper Carboniferous, faunas. 

One of these is exemplified by the fossils of the Weber shales. To the other those 

of the upper-division of the Weber belong. The fauna now known from the Robinson limestone is a meager one. Thus far the evidence does not indicate that the 

Robinson fauna differs essentially from that of the upper Weber. The middle 

division of the Weber also has furnished a very limited fauna. All of its species 

are common to the contiguous formations, both above and below, and there is no 

evidence for uniting it with one rather than another, or for retaining it as coordinate 

with either. The upper fauna is especially characterized by the number of its 

pelecypod and gasteropod species, which were obtained, however, in large. part at 

a single locality. 

The difference in facies between the Weber shales and the middle and upper 

Weber is as marked in this case as in the corresponding formations of the Crested 

Butte region. While only 4 species of the true Mollusca have been found in the 

Weber shales in this area, almost the entire brachiopod representation is centered 

there, only 7 species being found in the four upper stratigraphic divisions. Even 

among these the most numerous representation is in the Weber shale, the only 

instance where the range is nearly uniform being in the species Seminula subtilita. 

However, while the Weber shale has perhaps been sufficiently collected to warrant 

the belief that its main features are known, this is far less true of the upper beds of 

the section. 

Comparing the formational faunas of the Leadville area after the same method 

that was employed with those of the Crested Butte region, the following facts 

appear: In the case of the lower and upper Weber, these two formations have a 

joint fauna of 35 species, of which only 5 are contained in common. The relation of 

these faunas will then be expressed by the fraction .y5-6 or by the percentage 14.3. 

If, however, the lower Weber is contrasted with all the series above, the percentage 

is raised to 16.2, for the total fauna is 37 and the common species 6. 

The Leadville area is related to the Crested Butte region geologically and 

geographically, and a general faunal agreement can be traced. In both areas the 

fauna characteristic of the Rico formation of the Animas region is wanting, as will 

appear later. When the faunas of the different divisions of the Carboniferous in the 

Leadville region are tabulated with those of the Crested Butte region a certain correspondence in the abundance and range of species is disclosed. The evidence thus 

obtained indicates that the Weber shale of the Leadville region is the representative 

of the Weber formation of the Crested Butte region, and that the upper member of 
FAUNAL EVIDENCE AND CORRELATION. 245 

the Weber grits formation, car-lying with it probably the Robinson limestone and 

possibly the middle Weber, corresponds to the Maroon conglomerate. This correspondence is not so close as to be striking, and many departures can easily be pointed 

out; but I feel, that we have data very far from full as to the faunas of these formations. 

A comparison of the faunas of all the formations from which we have any adequate 

collections can be made by consulting the summary tables at the end of this chapter. 

Station 2281 probably is bed 38 in Peale's section No. 18, which was made from 

the mouth of the canyon of Fourmile Creek westward to Horseshoe Mountain.a 

This locality is in the Leadville district, and the horizon can safely be put at the 

Weber shales. The fauna also agrees with this identification. 

Station 2288 appears to be that mentioned by Peale on page 242 of the same 

report. The locality is probably near the Tenmile district. The horizon is rather 

uncertain, but appears to be the Weber shale,s, from the stratigraphic evidence, 

while the fauna itself is too limited to afford a clue. 

The collection from station 2289 is data cited on page 369, of the third volume of 

the reports of the Wheeler snrvey.b The section was made on the forks of Eagle 

River, a locality which I have been unable to identify exactly, but which appears to 

be not far northwest of the Tenmile district. The horizon is bed 19 of the local section, whose relations with the standard one are as difficult to ascertain as the position 

of the locality upon the map. As it occurs in the middle of a great sandstone series, 

I suppose that it comes about on the horizon of the Robinson limestone, just above 

or just below the division between the Weber grits and the Maroon formation. The 

fauna is. too scanty to afford evidence on this point. 

As our collections contain no fossils from the Front Range and Sangre de 

Cristo regions, I will proceed to give the faunal evidence from the San Juan region, 

SAN JUAN REGION. 

A wholly disproportionate amount of material in our Colorado collections was 

obtained from the small area of Carboniferous strata exposed in the Rico Mountains 

and in the valley of the Animas River in the southwestern part of the State. This. 

area is partly covered by the Durango, Rico, Engineer Mountain, Needle Mountains,. 

and Silverton quadrangles, and is shown on sheets 4 and 15 of the Hayden atlas of 

Colorado.c Most of the material obtained was collected by Whitman Cross, A. C. 

Spencer, and others associated with them. 

The geologic section in the Rico Mountains has been described by Cross and 

Spencer,a but generally, it may be said, with reference to the larger area in which 

a U. S. Geol. Geog. Surv. Terr., [Seventh] Ann. Rept., for 1873, 1874, p. 227. 

1J. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, 1875. 

c U. S. Geol. Geog. Surv. Terr, Geol. Geog. Atlas Colorado, 1877. 

d Geology of the Rico Mountains, Colorado: U. S. Geol. Surv., Twenty-first Ann. Rept., pt. 2, pp. 7-165. 
246 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

previous studies had been made and over which the same formations extend with 

only local variations. They recognized two formations of Upper Carboniferous age, 

the Hermosa and the Rico formations; but Cross has recently discriminated a third, 

the Molas formation, which is a thin stratum of red shale intermediate between the 

Hermosa formation and the Ouray limestone. 

The Molas formation is best known in the Needle Mountains quadrangle, where 

it has a thickness of only about 75 feet. It is a series of shales, but contains bands 

of diverse texture and material, among them being some of impure limestone 

and, some sandy. The color is an intense red, often strongly mottled with lighter 

tints, which occasionally are nearly white. It contains pebbles and small bowlders of 

chert, some of them fossiliferous. The fossils are the same species which occur in 

the Mississippian fauna of the upper part of the Ouray limestone, where the'cherts 

without doubt had their origin. The base of the Molas often contains bowlders of 

Ouray limestone of considerable size. The upper surface of the Ouray is more 

or less stained with the Molas, whose material and color appear to have worked 

down into cracks and crevices between partly loosened blocks of the older formation. 

Some of the impure limestqne beds of the Molas are fossiliferous. The collections 

so far obtained from the formation are but 3 in number, with a total of 6 species. 

The, stations are 2186, 2187, and 2188. 

The Hermosa formation consists of limestones, shales, and sandstones, and has 

a maximum thickness of 2,000 feet. Its characters are very inconstant, and while 

a threefold division was made in the Rico region, by reason of the segregation of 

the limestones into the middle portion, this could not be effected satisfactorily elsewhere. The lower division, composed mainly of shales, is, roughly speaking, 700 

feet in thickness. The central division, or heavy limestone series, is 500 feet thick, 

while the upper or transition member, of sandy and limy shales, is about 800 feet 

thick. In all, 71 collections were obtained from the Hermosa formation, and most of 

them have been located in one or another of the three stratigraphic subdivisions. The 

following stations are located in the lower series: 2197, 2198, 2209, 2213, 2214, 2247, 

2279, and 2284. In the middle series are the following stations: 2202, 2211, 2212, 

2217, 2220, 2222, 2223, 2224, 2225, 2228, 2229, 2235, 2236, 2237, 2246, 2249, 2282, 

2286, 2287, 2301, 2332, 2333, 2334, and 2335; and in the upper series are the following: 2200, 2201, 2203, 2204, 2205, 2207, 2208, 2210, 2216, 2218, 2219, 2221, 2226, 

2231, 2232, 2238, 2239, 2240, 2241, and 2283. 

Upon these stratigraphic subdivisions and upon the collections designated is 

based the following tabular statement, which shows the distribution of the Molas 

and Hermosa species by localities and in the final three columns their vertical range. 

Details of local representation, distribution, and range can, therefore, be secured 

from this source and from the register of localities appended. 
FAUNAL EVIDENCE AND CORRELATION. 247 

TABLE XIII. a—Table showing distribution of Pennsylvanian species in the San Juan region, and their range 

in the Molas and lower, middle, and upper Hermosa formations. 

1 2186 2187 2188 2196 2196a 2196b 2196c 2197 2198 2199 2200 2201 22021 2203 2204 22051 2206 2207 2208 2209 

• 

PROTOZOA. 

Fusulina'cylindrica x 

CELENTERATA. 

LophophylluM profundum 

Campophyllum torquium 

Chntetes milleporaceus 

Monilipora prosseri X 

ECHINODERMATA. 

ArchEeocidaris triplex? 

BRYOZOA. 

Fistulipora carbonaria 

RhOnThopora lepidodendroides. 

Polypora, sp. b 

Septopora sp 

x 

x 

BRACHIOPODA. 

Rhipidomella pecosi 

Derbya crassa 

Productus semireticulatus Var. 

hermosanus 

Productus infiatus 

Productus gallatinensis 

Productus cora * 

Productus punctatus 

Productus nebraskensis* 

Productus sp. a 

Marginifera muricata 

Marginifera wabashensis var 

Spirifer boonensis ? 

Spirifer rockymontanus 

Spirifer cameratus 

Squamulariaperplexa 

Seminula subtilita* 

Dielasma bovidens 

(?) 

x 

X X 

x 

X 

x 

X x 

X 

X 

X 

• X 

x 

x 

x 

x 

x 

X X 

X X 

x 

X X 

x 

PELECYPODA. 

Acanthopecten carboniferus* 

Myalina subquadrata ?* 

Myalina perniformis? 

Pseudomonotis hawni* 

Aviculopinna ? peracuta 

Clmnomya leavenworthensis 

Allerisma terminale 

Schizodus sp 

Edmondia subtruncata 

x 

x 

9 

x 

GASTEROPODA., 

Euconispira bicarinata 

Patellostium montfortianum 

x 

CEPHALOPODA. 

Tainoceras sp 

a For a description of the localities indicated by number in this table see locality register, pp 519-532. 

* Also found in Rico formation. 
 

 

 

 

• • 

 

 

- - - 

 

- - 

 

248 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XIII.—Table showing distribution of Pennsylvanian species in the San Juan region, and their range 

in the Molas and lower, middle, and upper Hermosaformations—Continued. 

1 I I 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221,2222 22232224 2225 2226 2227 222,8 2229 

I • ' 

PROTOZOA. 

Fusulina cylindrica x x x .... .... .... .... . .x I .... .... 

CCELENTERATA. 

Lophophyllum profundum , 


Zaphrentis gibsoni .......... .... .... .. .... .... ........ .... .... .... .. . .... .... . . 


Amplexus sp 


Chtetes milleporaceus 7 


ECHINODERMATA. 

Eupachycrinus? sp , 

BRYOZOA. 

Fistulipora carbonaria • .... .... .. .... .... .... .... .... 


Rhombopora lepidodendroides. , .... ... .... ... . ... , 


Fenestella sp • x.... . ... .... 


Stenopora carbonaria x 


Stenopora? sp .... X . . ... .... .... .... .... ... . 


Leioclema? sp . ........... .... .... .... .... 


BRACHIOPODA. - Derbya crassa 

Meekella striaticostata / 

Chonetes flemingi var. verneuilianus ---- •-• •••• ---• •••• ---- ---- -•-- -•-- - Chonetes mesolobus* , .. . x .... . -

Productus semireticulatus var. • 

---- — "" --'• — - ---

hermosanus 

Productus iniiatus x 

Productus gallatinensis x . 

Productus pertenuis9 (?) •- • • • _ .. 

Productus cora* x X x .... .7 ..1 x .... (?) .... .... .... .... - - -

Productus ndbraskensis* x x . .... .... .... .... .... 

Productus sp. b ... 1 . 

Marginifera wabas.hensis var • x .... .... .... .... .... .... .... .... ... 

Marginifera ingrata x 

Spirifer boonensis9 � x x - - • - - • •• • - - - - - - - - - - - - — 

Spirifer rockymontanus 

Spirifer cameratus x x x .. .... .... .... .... .... ... ... ... ... 

Squamularia perplexa • x ...x x x x x x.. . 

Amboccelia planiconvexa 

Spiriferina campestris 

Spiriferina kentuckyensis 

Seminula subtilita * .... 

PELECYPODA. 

Aviculopecten occidentalis * 

Aviculopecten pellucidus 

Aviculopecten rectilaterarius . 

Acanthopecten carboniferus* • 

Streblopteria tenuilineata - " -

Modiola? subelliptica .... .... ' 

Chcenomya leavenworthensis . 

Leda bellistriata? 

Edmondia ? Sp • " 

Cypricardinia carbonaria 

* Also found in Rico formation. 
 

 

FAUNAL EVIDENCE AND CORRELATION. 249 

•TABLE XIII.—Table showing distribution of Pennsylvanian species in the San Juan region, and their range 

in the 3folasuand lower, middle, and upper Hermosa formations—Continued. 

2210 2211 2212 I 2213 2214 2215 2216 2217 2218 2219 2220 22211 2222 2223 2224 2225 2226 22272228 2229 I _— — 1 

SCAPHOPODA. I 

Dentalium sublaeve x ... 

GASTEROPODA. • • 

Worthenia? lasallensis? .... .... .... .... 1.... . . Naticopsis altonensis* 1 ' 

Strophostylus subovatus? ? I 

Platyceras parvum

Minute gasteropods x x Bellerophon crassus* 

Bellerophon percarinatus ? 

Patellostium montfortianum ... .... ........ .... I .... 

Patellostium bellum 

Euph emus nodocarinatus ... - - - - - - - - - - • • 

CRUSTACEA. 

Phillipsia trinucleata 

Leperditia sp x I 

2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2246 2247 2249 2279 2282 2283 2289 

PROTOZOA. 

Fusulina cylindrica x x 

SPONGIA. 

Hyalostelia sp . .... . .. .... .... .... .... . .... .... .... • Hystriospongia? sp 

CcELENTERATA. 

Lophophyllum profundum • 

Amplexus sp . .._ ... .... Leptopora winchelli 

ECHINODERMATA. 

Archocidaris ornate X ..1 .... .... 

• HELMINTHA. 

Conularia crustula 

BRYOZOA. 

Rhombopora lepidodendroides .... .... - ... .. - - X . — - - ... - - - .. ... Prismopora sp x - - — .... .... .... .... ... •--- "•- ---- Polypora sp. b x-- - - - - - • - - - " ' - - - - - ' 

BRACHIOPODA. 

Derbya crassa X ..... .... . x Chonetes mesolobus* x Productus semireticulatus var. 

hermosanus X .... .. . Productus inflatus X ...... .... .... .... ... ... ... Productus gallatinensis X . Productus cora * X .... .... .... .... . ,... .... .... Productus punctatus 

Productus nebraskensis * 

Spirifer boonensis? x x x .... . - • • (?) Spirifer cameratus 

Squamularia perplexa , x Am beccelia planiconvexa

Seminula subtilita* x X x - ... x x .. - - x x x x x - - - . .. .. x * Also found in Rico formation. 
• • • •• 

250 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XIII.—Table showing. distribution of Pennsylvanian species in the San Juan region, and their range 

in the Molas and lower, middle, and upper Hermosa formations—Conthlued. 

PELECYPODA. 

Aviculopecten occidentalis* 

Acanthopecten carboniferus* 

Modiol a? subelliptica 

SCAPHOPODA. 

Dentalium sublEeve 

GASTEROPODA 

Naticopsis monilifera * 

Platyceras parvum 

Bellerophon crassus * 

PROTOZOA. 

Fusulina cylindrica 

SPONGIA. 

Hyalostelia sp 

Hystriospongia ? sp 

CCELEN TERAT A . 

Lophophyllum profundutn 

Campophyllum torquium 

Zaphrentis gibsoni 

Amplex us sp 

ChEetetes milleporaceus 

Leptopora winchelli 

ECHINODERMAT A . 

Archwocidaris triplex 

Archuocidaris ornata 

Eupachycrinus ? sp 

HELMINTH A . 

Conularia crustula ? 

BRYOZOA. 

Fistulipora carbonaria 

Rhombopora lepidodendroides 

Prismopora serrata 

Prisraopora sp 

Fenestella cf. tenax 

Fenestella sp 

Polypora cf. cestriensis 

Polypora whitei var. insculpta 

Polypora n. sp 

Polypora sp. a 

Polypora sp. b 

Septopora sp 

Chainodictyon laxum 

Stenopora carbonaria 

Stenopora? sp 

Leioclema ? sp 

1 1 1 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2246 2247 2249 2279 2282 2283 2284 

X 


X 


, • -

X 

x 

Hermosa. 

2286 2287 2301 2309 2322 2323 2327 2328 2331 2332 7553 2334 2335 2339 Molas. 

Lower Middle Upper 

x 

1 

2 

1 

X 1 

(?) 

x 

1 

1 

* Also found in Rico formation. 
FAUNAL EVIDENCE AND CORRELATION. 251 

TABLE XIII.— Table showing distribution of Pennsylvanian species in the San Juan region, and their range 

in the Molas and lower, middle, and upper Hermosaformations—Continued. 

Hermosa. 

2286 2287 23012309 2322 2323 2327 2328 2331 2332. 2333 2334 2335 2339 Molas. 

I 

Lower Middle Upper 

BRACHIOPODA. 

Rhipidomella pecosi 

Derbya crassa 

Meekella striaticostata 

><' 

Chonetes flemingi var. verneuilianus 

Chonetes mesolobus * 

Productus semireticulatus var. 

hermosanus X x X 6 

Productus inflatus 

Productus gallatinensis 

Productus pertenuis ? 

Productus cora * 

Productus punctatus 

Productus nebraskensis * 

X X 

1 

4 

2 

1 

2 

7 

(?) 

Productus sp. a 

Productus sp. b 

Marginifera wabashensis var 

Marginifera ingrata 

Spirifer boonensis 

Spinier rockymontanus 

Spirifer cameratus 

Squamularia perplexa 

Amboccelia planiconvexa 

Spiriferina campestris 

Spiriferina kentuckyensis 

Seminula subtilita * 

X 

X 

X 

X 

(?) 

X X 

1 

1 

1 

4 

4 

•2 

9 

2 

13 

4 

PELECYPODA. 

Aviculopecten occidentalis * 

Aviculopecten pellucidus 

Aviculopecten rectilaterarius . 

Acanthopecten carboniferus*... 

Streblopteria tenuilineata 

Modiola? subelliptica 

Myalina subquadrata? * 

Myalina perniformis9 

Pseudomonotis hawni * 

2 

1 

1 

4 

2 

1 

2 

Aviculopinna? peracuta 

Chwnomya leavenworthensis 

Allerisma terminale 

1 

2 

1 

Schizodus sp 

Leda bellistriata, 

Edmondia subtruncata 

1 

1 

2 

Edmondia ? sp 

Cypricardinia carbonaria 

1 

1 

SCAPHOPODA 

Dentalium sublmve 2 

Dentalium sp 1 

GASTEROPODA. 

Worthenia? lasallensis? 

Naticopsis altonensis* 

Naticopsis monilifera* • 

• 

* Also found in. Rico formation 
252 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XIII.— Table showing distribution of Pennsylvanian species in the San Juan region, and their range 

in the Molas and lower, middle, and upper Hermosa formations—Continued. 

Hermosa 

'2286 2287 2301 2309 232'2 23232327 2328 2331 2332 2333 2334 2335 2339 Molas. 

Low erlMiddle Upper 

G AST EROPODA--continued 

Strophostylus subovatus 

Platyceras parvum 

Euomphalus catilloides 

Minute gasteropods 

Bellerophon crassus* 

Bellerophon giganteus? 

Bellerophon percarinatus ? 

Patellostium montfortianum 

x 

1 

1 

1 

1 

1 

1 2 

Patellostium bellum * 1 

Euphemus nodocarinatus 

CEPH A LOPODA 

Tainoeeras sp 

CRUTFACEA. 

Phillipsia major 

Phillipsia trinucleabt 

Leperditia sp 

x 

* Also found in Rico formation. 

The Rico formation is part of the regular Red Beds. Its thickness is assumed to 

be 300 feet, because this portion of the Red Beds contains Carboniferous fossils. For 

a distance above this horizon no fossils are found, while at the top Triassic vertibrates occur. The Rico formation is made up of sandstone and conglomerate, with 

included shales and sandy, fossiliferous limestones. Our collections from the Rico 

formation are 12 in number, and the total fauna known consists of 39 species. 

The stations at which Rico fossils have been obtained are 2248, 2337, 2340, 2341, 

2342, 2343, 2344, 2345, 2346, 2347, 2348, and 2349. The Rico fauna is so different 

from that of the Hermosa formation that it has been deemed best to represent it on 

a separate table, from which the local distribution of the species can readily be 

ascertained. A comparison of the Rico with the Hermosa fauna can be made by 

means of the asterisks, which are attached in both tables to species common to the 

two formations. 
 

 

 

 

 

 

 

 

 

 

 

 

 

FAUNAL EVIDENCE AND CORRELATION. 253 

TABLE XIV.a--Showing distribution of Pennsylvanian species in the Rico formation of the San Juan region. 

2248. 2337. 2340. 2341. 2342. 2343. . 2344. 2345. 2346. 2347. 2348. 2349. Total. 

BRACHIOPODA. 

Chonetes mesolObus* X 

Chonetes geinitzianus X 1 

Productus cora * x x X 5 

Productus nebraskensis * (?) (t) 

Seminula subtilita * x X 6 

PELECYPODA. 

Aviculopecten occidentalis* 

Acanthopecten carboniferus* 

x x x � a 

1 

Myalina wyomingensis x X X X 

Myalina subquadrata? * x X X x Myalina perattenuata

Posidoniella pertenuis ? 

Pseudomonotis hawni* x 1 

Pseudomonotis equistriata 

Pseudomonotis kansasensis x 

x 

1 

1 

Pseudomonotis sp 

Monopteria polita 

Monopteria alata 

Monopteria longispina 

Aviculopinna nebraskensis

Allerisma terminale 

x 

X 

1 

1 

1 

1 

Sedgwickia topekensis 

Schizodus cuneatfis ? 

Schizodus meekanus 

X ' X 

X 

3 

1 

Schizodus pandatus ? 

Pleurophorus subcostatus 

Pleurophorus occidentalis ? 

Edmondia gibbosa 

Astartella ? gurleyi 

x 

(?) 

X 

X 

X 

x 5 

1 

3 

1 

GASTEROPODA. 

Euconispira sp. a

Euconispira sp. b 

Worthenia ? marconiana ? 

1 

Loxonema plicatum 

Loxonema ? peoriense 

Naticopsis altonensis* 

Naticopsis monilifera * 

Strophostylus remex 

Bulimorpha chrysalis

Bellerophon crassus* 

Patellostium bellum * 

(?) 

x 

x 

X 

X 

x 

x 

X 

2 

Euphemus nodocarinatus x X I x -x 

a For a description of the localities indicated by number in this table, see locality register, pp. 519-532. 

* Species marked by an asterisk occur also in the Hermosa formation. 

The fauna of the Molas formation known is very limited, and will he found represented in the first of the final columns of Table XIII. Isolated from other fact:, 

there might exist some doubt from the present faunal evidence whether the Molas 

formation belonged in the Lower or in the Upper Carboniferous, though I think 

that even so it would be placed by most paleontologists in the higher series. Com-
254 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

paring its fauna with that of the basal Hermosa I find that three of its six species do 

not appear there. The most abundant species in the Molas, however----Spirifer 

boonensis and Seminula subtilita—are also especially abundant in the base of the 

Hermosa, and the somewhat peculiar variations are the same in each case. Not 

enough is yet known of the Molas fauna to assure a safe opinion, but I expert that 

it will prove to be closely related to that of the basal Hermosa. Lithologically, 

however, the Molas is a distinct thing, and it may be that the fauna will show corresponding modifications. This is, indeed, already indicated to a certain extent. 

On the other hand, while the Molas fauna shows a distinct relationship with that 

of the Hermosa formation, it is completely disconnected with the 'Mississippian 

fauna of the Ouray limestone, not a single species apparently passing into it from 

below. In view of this fact, of the .unconformity which preceded it, of the independent significance of its fauna, and of its affinity with that of the Hermosa, the 

Pennsylvanian age of which is clear, it seems that the Molas formation also can 

safely be placed in the Upper Carboniferous. 

The fauna of the lower Hermosa is less numerous than that of either of the 

upper divisions or of the Rico formation. Only 20 species have been obtained from 

it, while the middle has furnished 42, the upper 49, and the Rico 40. It is also less 

varied, and is predominantly a brachiopod fauna. In the middle division a number 

of gasteropod species appear, while the upper, in addition -to brachiopods and gasteropods, has a considerable force of pelecypods. The number of brachiopod species 

remains in a general way nearly constant, there being 12 in the lower Hermosa, 17 

in the middle, and 13 in the upper; but by reason of the accession of other types, 

especially of the true Monusca, they hold a regularly diminishing ratio to the entire 

fauna. Thus. they rate at 60 per cent in the lower Hermosa, 40.5 per cent in the 

middle, and 26.5 per cent in the upper. In the Rico formation only 5 species have 

been found, and they represent only 12.5 per cent of the entire fauna. The Mollusca 

are at the same time increasing in proportion, passing from 10 to 26.2 and 46.9 per 

cent of the entire fauna in the different divisions of the Hermosa and to 87.5 in the 

Rico formation. 

The collections from the lower member of the Hermosa formation were all 

obtained from its basal portion. In areas where the Molas formation appears their 

occurrence is just above its upper boundary, and where the Molas has, not been dis 

tinguished they were found within about 50 feet or less of the Ouray limestone, whose 

upper beds contain, -as I have already shown, a fauna of Mississippian age. The 

fauna exhibited by these collections is of Upper Carboniferous age. There is, therefore, a great faunal break between the base of the Hermosa formation and the Ouray 

limestone, corresponding to the unconformity by which they are known to be separated. The time interval indicated by this faunal break is a long one, representing 

much of Mississippian time and probably encroaching upon the ensuing Pennsyl-
FAUNAL EVIDENCE AND CORRELATION. 255 

vanian. The general age of the base of the Hermosa formation is, fortunately, quite 

without the range of speculation. The presence of such characteristic forms as 

Fusulina cylirarica, Derbya eras8a, Chonetes fiemingi var. verneuilianus, Productus 

n,ebrctskensis, .31-argi/nifera wabashensis var., S 

. pir?er earn eratus , Squamularia perplema,

and Seminula subtilita stamps this fauna as Upper Carboniferous. 

The lower Hermosa fauna is probably closely related to that of the Molas forination, though the latter is too imperfectly known to permit much to be said of it with 

safety. It is also related to the fauna of the middle Hermosa, yet retains a certain 

individuality of facies which renders its recognition in the San Juan region easier 

than that of either of the overlying divisions. The table shows that Ch. flemingi var. 

verneuilianus, Productus infiatus, Productus gallatinensis, and Productus sp. b. do not 

range into the middle and upper Hermosa, and that Productus semireticulatus var. 

herm,osanus, Productus punctatus, Spirifer rockymontanus, and a number of other 

species found above do not occur in the lower. In working through the collection, 

however, I was more impressed by the abundance, persistence, and distinctive form . 

of S_pirefer boonensis ., though the latter sometimes occurs abundantly at higher 

levels, and of the small Productus gallatinensis. Aside from the brachiopods the 

fauna of the lower Hermosa has little in common with the division above. Such 

species belonging to other groups as are found there appear as a rule to be peculiar 

to it. 

Expressing the relation between the three divisions of the Hermosa formation and 

the Rico formation numerically, as has been done in other cases, by taking the ratio 

of the combined fauna of two adjacent divisions to the species common to both, 

the relation between the lower and middle beds is expressed by the number 19.2, 

between the middle and upper by 21.3, and between the upper Hermosa and the 

Rico by 12.8. Similarly, the relation between the Rico formation and the Hermosa a 

taken as a whole is 9.9, somewhat less, as one would expect, than that existing 

between it and the upper division alone. While this form of comparison is not 

without significance it is doubtful whether a numerical expression ever adequately 

represents the relation between two faunas in stratigraphic paleontology, while sometimes it is evidently misleading. One defect, which might perhaps be remedied, is 

that it overlooks the element of abundance in individual local occurrences or persistent repetition of local occurrence. The most serious defect is that it expresses in 

regard to faunas their total similarity or difference resulting from the two factors of 

evolutionary development and of the 'selective action of environmental conditions, 

while it is for one of these chiefly that the paleontologist would find expression. The 

other in most cases could be safely overlooked. At all events, to correctly understand the geologic relations of faunas, as well as the geographic, it is necessary 

a Two of the species common to the Rico and Hermosa formations have not been recognized in the upper Hermosa. If 

they are regarded as having a continuous range and are counted in with the other upper Hermosa species, this relation 

would be expressed by the number 15.4. 
256 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

that these two independent interacting factors be as far as ,practicable differentiated. • 

A method which would give mathematical expression to both these forces separately, 

ilk instead of to their resultant, would be very useful. Qualified as must be their 

acceptation, the figures just given indicate a less intimate relation between the 

Hermosa and Rico formations than between the several members of the Hermosa. 

In 'whatever way the two faunas be viewed a marked difference in facies must be 

granted. As in the, Dolores River region at Sinbads Valley the supposed equivalent, 

of the Hermosa greatly exceeds in thickness the typical sections, and as its, upper 

beds contain a fauna at once different from that of the Rico formation, and only 

in a less degree from that of the Hermosa, it would appear as if the faunal break 

between the Hermosa and Rico formations, and to a certain extent the marked 

lithologic change which it accompanies, were the expression of a period of 

nondeposition or erosion represented in other areas by sediments and faunas not 

found in the San Juan. 

It has been noted that the fauna of the lower division of the Hermosa also has a 

certain individuality of facies; but it appears frcan the consideration of corresponding horizon in,other regions adjacent that the species which our collections indicate 

might serve'. to distinguish the lower from the middle. division are not as sharply 

limited in range as in the San Juan. Possibly the reason that a faunal break seems 

to exist in the San Juan region is that there the collections from the lower Hermosa 

were all made at the very base, some 600 or 700 feet of strata intervening between 

them and the middle division. 

Ouray.—It would be difficult to say whither the small, isolated Carboniferous 

area -about Ouray would more appropriately be included with the San Juan or with 

the Dolores River region. I have, however, decided to discuss the few collections 

from Ouray in connection with the former. , 

The Ouray limestone is not exposed at Ouray in such a manner that its stratigraphic relation to the Upper Carboniferous formations could be satisfactorily made 

out. I was not sufficiently acquainted with the upper part of the Paleozoic section 

in the San Juan to determine on lithologic evidence (for the Rico fauna was not found 

at Ouray) the position there of the Rico horizon. ' Therefore, while it is safe to say 

that the Ouray collections came from the equivalent of the Hermosa formation, their 

position relative to either the top or the base of the section was not determined. I 

am of the opinion, however, that the collection made on the west side of the valley 

represents a higher horizon than those made on the east side. The latter, while containing some of the forms supposed to characterize the lower Hermosa—as, for instance, 

Productus injlatus and Productus gallatinensis—contain certain others, such as 

Spir?fer rockymontanus, rather distinctive of the upper divisions. The same is true 

of the collection from the west side of the valley, from which it appears that the 

differences distinctive of the lower and middle divisions of the Hermosa formation in 
FAUNAL EVIDENCE AND CORRELATION. 257 

the San Juan region are less strongly marked ill other areas. I believe, however, that 

the collections on the east side of the valley probably belong to the horizon of the 

lower Hermosa of the San Juan region and the Weber formation of the Crested Butte 

region. The accompanying table shows the local distribution of the species found 

near Ouray. 

TABLE XV. a— Table showing distribution of Penimylranian species in the Ifermos(! formation at °tally. 

2191. 2195a. • 2195b. 2195c. Total. 

Fusulina eylindriea 

PROTOZOA. 

x 3 

CampophyIlum torquium 

((1O.ENTERATA. 

Archwocidaris ourayensis 

Archreoeidaris cratis 

ECIIINODERMATA. • 

x 

BRACHIOPODA. 

Derbya crawl 

Chonetes flemingi 

Productus gallatinensis 

Productus inflatus 

Produetus semireticulatus var. hermosanuc 

Productus cora 

Productus nehmskensis 

x 

x 

x 

3 

.) 

1.ki rgin i fent ingrata 

Spirifer boonensis' 

Spirifer rock ymontanu 

Spirifer cameratus 

Squamularia perplexa 

Seminula subtilita 

x 

1 

1 

1 

1 

3 

PELECYPODA. 

Aviculopeeten sp. b 

Streblopteria tenuilineata x 

CRUSTACEA. 

Phillipsia major 

a For a description of the localities indicated by number in this table see locality register. pp. M9-532. 

DOLORES RIVER REGION. 

A single collection from Sinbads Valley (station 2285) is all we have to represent 

the Carboniferous strata of the Dolores River region. Its horizon is in the stratigraphic equivalent of the Hermosa formation, about 100 feet below the Red Beds. 

The following species have been identified: 

1m ph, ph yllum profundum. Cluenomya leavenworthensie. 

selmehertensis. F,dmondia mortonensis? 

Enteletes hemiplieatus. ?Natieopsis altonensis. 

Chonetes granulifer. Euomphalus catilloides. 

Produetus portloelcianus. Worthenia tabulates? 

Productus semireticulatus, var. hermosanus? Bellerophon perearinat us. 

Spirifer cameratus. 

14364—No. 16-03---17 
258 ('ARnws.riFEROVS, FORMATIONS AN I) FAUNAS OF COLORADO. 

This is clearly not the Rico fauna. and its affinities are rather with those of the 

middle and upper portions of the Hermosa formation. It presents, however, a di, 

tinctly different facies from any portion of the Hermosa, as will be seen from t lip 

fact that Enteletes hemiplicat rts, ChwieteN gramtl "ler, Proditelet portlocki(in 

Einamdia mortanensiR?, and Worthen ia ta/m/ota? are not known to occur in that 

formation. In Sinbads Valley the Hermosa, or what is supposed to be that forumtion, has a much greater thickness than in the San Juan region. This collection. 

therefore, which comes from near the top of the formation in Sinbads Valley, presumably represents a higher horizon than any portion of the Hermosa in the San 

Juan region and also a lower horizon than the Rico formation. These facts, taken 

in connection with the rather marked faunal break and lithologic change between 

the typical Rico and Hermosa, are all favorable to the supposition that in the San 

Juan a period of erosion or nondeposition intervened between those two series of 

sediments, represented by the upper beds in Sinbads Valley and indicated by the 

different facies of their faunas. 

SUMMARY. 

Probably of greater interest than the relation to one another of the faunas of 

the different formations of the same section are the relations of the faunas of forumtions in the different sections which have been studied in different portions of the 

State. The only sections represented by collections adequate to make such a comparison are those of the San Juan region, Crested Butte district, and Leadville and 

Tenmile districts, the last two being considered together. To this end I have prepared a summary table, giving the composite faunas of the several formations 

recognized in these three regions. The character of the local faunas from which the 

composite list, is made up is shown in the tables dealing individually with the 

different regions. 

TABLE X VI.—Summary table for comparing the Upper Carboniferous formational faunas of the San Juan, 

Crested Butte, and Leadville and Teamile districts. 

San Juan. Crested Butte. I Leadville and Tenmile. 

Hermosa. Weber. 

Low-1 Mid. 

er. I die. Up. 

per. 

Maroon. RobinLow- Mid- Up- son. I Marth)". er. die. I per. Weber. 

I:( ITOZO A . 

Fusulina cylindrien 4 4 1 4 

Fusulina eylindriea var. ventrieosa. " 

SPONG I A. 

Hyalostelia sp 1 

Hystriospongia ! sp 1 

C(ELENTERATA. 

Lophophyllum profundum 3 

Campophyllum torquium 1 1 2 
 

FAUNAL EVIDENCE AND CORRELATION. 259 

TABLE X VI. —Summary table for comparing the Upper Carboniferous formational faunas of the San Juan, 

Crested Butte, and .Leaetvilte and Tenmile districts—Continued. 

San Juan. Crested Butte. Leadville. 

Hermosa. Weber. 

Robin- Molas. Weber. Maroon. [ Low- Mid- u.__ Mnroon. Low- Mid- Up- Up son. — 

er. dle. per. er. d le. per. 

CCELENTERATA—continued. 

Amplexus sp 1 1 1 


Zaphrentis gibsoni -, 1 .. 


1 Cladopora sp ..

Leptopora winchelli 

Monilipora prosseri 2 

Chsetetes milleporaceus 1 � 1 

ECHINODERMATA. 

Archuocidaris ornata 

Eupachycrinus ? sp 

1 � 

1 �
 

1 �
 

Archnocidaris cratis 

Archnocidaris trudifer ? 


�
 

Archwocidaris triplex ? 


Eocidaris halliana ? 


HELMINTHA. 

Spirorbis arietina 2 

Conularia crustula (?) 

Enchostoma sp 1 

BItYOZOA. 

Fistulipora carbonaria 1 

Rhombopora lepidodendroides •1 1 

Prismopora serrata 1 

Prismopora sp 1 

Fenestella cf. tenax 

Fenesteila sp 

Polypora cf. distincta 

Polypora cf. cestriensis 

Polypora whitei var. insculpta 

Polypora n. sp 

Polypora sp. a 1 Polypora sp. b 1 

Septopora delicatula 

Septopora sp 

Chainodietyon laxum 1 � 

Stenopora cestriensis 

Stenopora carbonaria 1 � 

Stenopora tuberculata 

Stenopora ? sp 

Leioclema ? sp 

BRACHIOPODA. 

lAngula carbonaria 1 � 

Lingula tighti .1 

Orbiculoidea manhattanensis 2 

Rhipidomella pecosi 1 

Derbya crassa 3 3 2 2 

Chonetes flemingi 

Meekella striaticostata 1 � 

2 

Chonetes flemingi var. verneuilianus 

Chonetes geinitzianus R 
 

260 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

TABLE XVI.—Summary table for comparing the Upper Carboniferous formational faunas of the San Juan, 

Crested Butte, and Leadville and Tenmile districts--Continued. 

San Juan. Crested Butte. Leadville. 

Hermosa. Weber. 

Moles. Robin- Lower. Middle. 

Upper. 

Weber. Maroon. Lower. Middle. Upper. son. Maroon. 

ER.A.CHIOPODA—continued. 

Chonetes mesolobus 

Productus semireticulatus var. hermosanus 4 6 

2 

5 

2 .� 

2 1 1 

Productus inflatus 3 1 5 1 

Productus gallatinensis 4 (?) 

Productus cora 4 9 1 3. 2 

Productus pertenuis ? 1 

Productus nebrdskensis 1 7 2 

Productus punctatus 2 2 

Productus sp. a 1 1 

Produetus sp. b 

Marginifera lasallensis ? 

Marginifera muricata 5 

Marginifera wabashensis var 1 1 2 

Marginifera ingrata 1 2 

Spirifer boonensis ? 1 4 3 

Spirifer rockymontanus 4 4. 1 

Spirifer cameratus 2 6 3 

Squamularia perplexa 9 4 9 1 

Spiriferina campestris 1 

Spiriferina kentuckyensis 1 1 

Amboccelia planiconvexa 2 

Seminula subtilita 13 8 10 3 2 3 ...... 

jiustedia mormoni 3 

Pugnax utah 2 

Dielasma bovidens 1 

PELEC YPODA. 

.Aviculopecten occidentalis 2 (?) 

Aviculopecten rectilaterarius 1 1 

Aviculopecten ? interlineatus 1 

Aviculopecten pellucidus 1 

Acanthopecten carboniferus 4 

Streblopteria tenuilineata 2 

Entolium? sp 

Modiola ? subelliptica 1 

Myalina wyomingensis 

Myalina subquadrata ? 

Myalina cuneiformis 

Myalina perniformis 1 

Pseudomonotis hawni (?) 

Aviculopinna ? peracuta 1 

Leda bellistriata 9 1 

Nucula ventrieosa ? 

Nucula sp 

Edmondia subtruncata 2 

Ed mondia ? sp 1 

Schizodus sp 1 

Cypricardinia carbonaria 1 

Macrodon tenuistriatus? 

Macrodon obsoletus 1 

Pleurophorui occidentalis? 1 
'FAUNAL EVIDENCE AND CORRELATION. 261 

TABLE XVI. —Summary table for comparing the Upper Carboniferous formational faunas of the San ..Tuan, 

Crested Butte, and Leadville and Tenmile districts—Continued. 

San Juan. Crested Butte. Lead' ille 

Hermosa. Weber. 

Molas. Weber, Maroon. Low- Robin- Maroon. Low- Mid- Up Mid- Up- son. er. dle. per. • er.- dle. per. 

PELEcYpoDA—continued, 

Allerisma terminale 1 


Chunomya leaven worthensis 2 


SCAPHOPODA, 

Dentalium sublceve 2 


Dentalium sp 1 


GASTEROPODA. 

Platyceras parvum 1 1 


Strophostylus remex 


Strophostylus subovatus? �
 

Naticopsis altonensis 1 


Naticopsis monilifera..... 


Worthenia? lasallensis? 1 


Worthenia? marcouiana? 1 


Worthenia? sp. a 1 


Phanerotrema cf. grayvillense 1 


Euconispira taggarti 


Euconispira bicarinata 


Loxonema sp • 1 


Bulimorpha chrysalis 


Euomphalus catilloides 1 


Minute gasteropods 1 1 2 


Bellerophon crassus 1 1 1 


Bellerophon giganteus? 1 


Bellerophon percarinatus? 1 1 


Patellostium montfortianum 
 2' 


Patellostium bellum 1 


Eupheraus nodocarinatus 

CEPHA LOPO D A . 

Tainoceras sp 1 
 . 


Doraatoceras sp 2
 

CRUSTACEA. 

Phillipsia major 


Phillipsia trinucleata 


Leperditia sp 1 


Kirkby-a sp 


Bairdia cf. cestriensis 


Beyrichia sp 


In the above table are given the composite faunas of the Molas and of the lower, 

middle, and upper Hermosa formations in the San Juan region, of the Weber formation and of the lower member of the Maroon in the Crested Butte district, and of 

the lower, middle, and upper Weber, of the Robinson limestone, and of the Maroon 

formation in the Leadville and Tenmile districts. • The fauna of the Rico formation 

of the San Juan region has not been found elsewhere in Colorado, and it did not 

seem necessary to introduce it for comparison. The fauna of the upper Maroon or 
262 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the Crested Butte district is not known, and those of the middle Weber, Robinson 

limestone, and Maroon formation of the Leadville and Tenmile districts are very 

imperfectly known. 

A comparison of the sections of these three areas without the aid of paleontologic evidence would indicate that the Hermosa formation, and possibly the Molas 

of the San Juan and the Weber and Maroon formations of the Crested Butte and 

Leadville districts, are in a general way equivalent. The correctness of this correlation is borne out by the distribution and range of species shown in the table. The 

species which characterize the lower Hermosa are present in the Crested Butte and 

Leadville districts, in the Weber formation of the one and the lower Weber or 

Weber shale of the other. The agreement in range of individual species with that 

in the San Juan is, as might be anticipated, somewhat greater in the case of the 

Crested Butte district than in the Leadville district. This may be entirely due to 

geographic separation, or it may be partly owing to a possible mixing in the Leadville collections of specimens from different geologic horizons. The evidence for 

suspecting that this may have occurred consists in the fact that several, and in some 

cases a large number, of different locality labels were found with single lots of 

fossils. 

There seems to be evidence for believing that the lowest Pennsylvanian deposits 

in the San Juan, Crested Butte, and Leadville areas were essentially synchronous. 

It also seems to be true that essentially the same fauna occurs in the Hermosa formation of the San Juan region, the Weber and lower Maroon formations of the Crested 

Butte, and the Weber shale and Weber grits of the Leadville district. Of the fauna 

of the upper Maroon in the Crested Butte district and of the Maroon in the Leadville 

district we know nothing in one case and very little in the other. I have entertained 

the hypothesis that the Rico formation of the San Juan region is equivalent to the 

upper Maroon formation of the Crested Butte, but unfortunately no paleontologic 

evidence exists to prove or disprove this conjecture, as has just been said. The 

Maroon formation of the Leadville district corresponds in its position in the section 

to the upper division of the Maroon in the Crested Butte. Only one determined 

species, Productus cora, is known from the Maroon formation of the Leadville area, 

and it occurs in both the Hermosa and Rico formations. In the Robinson limestone, 

which is taken as the base of the Maroon formation, or as the dividing line between 

mularia perplexa, Seminula subtilita, Strophostylus remex, 

the Maroon and Weber grits, five species are known: Spirifer rockymontanus, Squaand Bellerophon crassus. 

Of these, Strophostylus remex is found in the Rico but not in the Hermosa, Seminula 

subtilita 

montanus 

then somewhat against my hypothesis, but the evidence can not be regarded as conand 

and 

Bellerophon crassus 

Squamularia perplexa 

in both Rico and Hermosa, and 

only in the Hermosa formation. The case stands 

Spirifer rocky­
FAUNAL EVIDENCE AND CORRELATION. 263 

elusive, especially in view of the variation in the matter of range of species exhibited 

in the Leadville and San Juan regions in the case of the earlier formations. 

A general comparison of the geologic column as shown in sections in Colorado, Utah, and Arizona has led me to consider the existence of nonsequence of sediments and life at several horizons in the Carboniferous of these areas. As indicated 

by variations in geologic sections, one of these occurs at the top of the Leadville 

and the Ouray limestone, another between the Weber limestone and the Maroon 

formation, a third between the two divisions of the Maroon, and a fourth between 

the Maroon and Wyoming formations. The unconformity and erosion found between 

the Leadville limestone and the overlying Pennsylvanian sediments find faunal 

expression in Colorado in a complete change of invertebrate life and in the absence 

of faunas of late Mississippian age. Another striking though not equally strong 

faunal break is found between the Hermosa and Rico formations, and is further 

borne out by the existence in Sinbads Valley of a greatly thickened series resembling 

the Hermosa, which has at its top a fauna more like the Hermosa than the Rico 

fauna, yet not entirely the same as either. As the Rico formation is supposed to 

represent the upper Maroon and the Hermosa the lower Maroon, there is some 

substantial faunal evidence favorable to the third hypothetical interruption. No 

invertebrate fauna is known from the Trias of Colorado, whose age is determined by 

vertebrate remains found in the San Juan. As I believe that the Rico fauna is not 

so young as the Permian, it is probable that a long interval occurred between the 

Maroon and Wyoming sediments. The reduction in thickness of the Pennsylvanian 

portion of the Wasatch limestone from 5,400 feet in Utah to 1,000 feet and less in 

its supposed equivalent in Colorado, the Weber limestone, suggests that in Utah beds 

are contained in the Wasatch which are absent in Colorado. Part of this thinning 

might be ascribed to the ascertained unconformity which preceded the Weber limestone of Colorado and which can probably safely be said to be more extensive there 

than in Utah. On the other hand, it is necessary to consider the possibility of an 

interruption between the Weber limestone and the Maroon series, the supposed representative in Colorado of the Weber quartzite which succeeds the Wasatch limestone 

of Utah. It is not possible to consider here the faunas of the Wasatch limestone 

and Weber quartzite. The faunas of the Weber limestone of the Crested Butte and 

of the Weber shale of the Leadville district have an expression sufficiently 

distinctive and are sufficiently different from those above to lend some color to such 

a hypothesis, though doubtless not to prove it. But the faunal evidence tends to 

correlate the Molas and basal Hermosa formation on one hand with the Weber limestone and the Weber shale, and also the persistence over most of the San Juan of the 

limestones which occur at the base of the Hermosa affords a feature of lithologic 

correspondence.. Many of the distinctive forms of the lower Hermosa are found 
264 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

lower in the beds of the other areas, and a faunal change of about the same value 

separates it from the fauna of the middle Hermosa. This last is, however, partly due 

to the fact that the fauna of the lower Hermosa was in almost every case found at the 

base of the series, with a considerable thickness intervening between it and the fossil 

iferous horizons of the middle Hermosa. If the Weber limestone and the Maroon 

formation were not deposited consecutively, it is probable that a similar interruption 

intervened between the lower and the middle Hermosa. This does not, however, 

seem to find support from observations in the field, and it is important to mark that 

in a numerical expression the fauna of the lower Hermosa is but little more different 

from that of the middle than is the middle from the upper division, though certain 

features of the brachiopod representation give it a more distinct facies. 

With regard to the age of the Pennsylvanian formations of Colorado compared 

with the better-known sections of the Mississippi Valley, I believe that the Hermosa 

formation, the Weber and the lower Maroon formations, and the Weber shale and 

Weber grits come very early in Pennsylvanian time and are probably older than 

any beds of the Kansas and Nebraska sections. The opinion that these formations 

represent very early Pennsylvanian time is supported by the fact that a number of 

species, as, for example, Productus gallatinensis, and especially the Bryozoa, are 

either identical with Mississippian forms or closely related to them. The belief that 

these formations are older than the oldest beds of the Kansas section, or at least are 

to be correlated with them, finds support not only in the same facts, joined to this 

other, that apparently a long period of early Pennsylvanian time is unrepresented in 

the Kansas section, but also from the following considerations, many others similar 

to which could probably be mentioned. The genus Meekella occurs in the Fort 

Scott limestone (2) a almost at the base of the Kansas section, while in Colorado it is 

known at but two localities and is not very characteristic. Enteletes, which is 

abundant well down in the Kansas section in the Iola limestone (16), is not known in 

Colorado, except at one locality, Sinbads Valley, whose horizon is supposed to be in 

the Hermosa formation, but higher than any of the Hermosa beds of the San Juan 

region. Ch,onetes m.esolobus is abundant in Colorado, but is restricted to the early 

portion of the section in Kansas, extending no higher than the Parsons limestone (6). The same is true of Chonetes flemingi, which is abundant in Colorado, 

and though having a long range in Kansas seems to be the an'ecedent type of Ch. 

granulifer, which does not make its appearance until about the Lecompton limestone (22). This species is not known in Colorado except at Sinbads Valley, where 

its horizon appears to be considerably above the top of the Hermosa formation in 

the San Juan. Productus semiretieulatus var. h,erm,osanus, which distinguishes the 

upper divisions of the Hermosa formation, is found only in the lower portion of the 

a The numerals refer to the beds in the general section of Upper Carboniferous rocks of Kansas. 
FAUNAL EVIDENCE AND CORRELATION. 265 

Kansas section, while the variety of Productus semireticulatus common in the Kansas 

section is not found in Colorado at all except possibly at Sinbads Valley. Productus 

infiatus, on the other hand, which is rather characteristic of the lower division of 

the Hermosa formation, is extremely rare in the Kansas section. The same is 

true of Productus gallettinensis. Spirifer rockyrnontanus and Spirifer boonensis(P), 

which, being of the Keokuk group of spirifers, may be considered rather 

Mississippian than Pennsylvanian types, though found abundantly in the Mississippi Valley at horizons I believe to be older than the Kansas section, 

do not occur in the latter at all. They are abundant in Colorado, arid generally 

throughout the' Rocky Mountains. Spiriferina campestris also, which is all but 

identical with the Mississippian Spiriferina spinosa, is not known in the Kansas 

section. Considerable other evidence might be adduced, but enough has been 

given to be significant. The evidence of the gasteropods and pelecypods is less 

clear, but in the main it bears out that of the brachiopods and Bryozoa, which have 

just been hastily referred to. However, as these types are less common than the 

brachiopods, their range is less completely known, and as they are more often poorly 

preserved and more difficult to identify they are not as a rule as practicable for 

evidence. A possible contradiction to the tendency of the foregoing evidence may 

exist in Pseudomonotis h,awni, a single doubtful instance of which is found in the 

Hermosa formation, while in Kansas it seems not to come in until toward' the close 

of the section. Other species of Pseudomonotis, however, appear earlier, as, for 

instance, Pseudomonotis equistriata, which is present in the Iola limestone (16). It 

seems to me, however, that there is abundant 'evidence to prove that the Hermosa 

formation and its correlates (except the upper portion exposed in Sinbads Valley) 

are not younger than the lower portion of the Kansas section, and that they probably 

are somewhat older. I might add that I believe this to be true of a large part of the 

Upper Carboniferous of the West, and that its more or less unfamiliar fades is often 

due to its being older than the well-known faunas of the Upper Coal Measures of 

the Mississippi Valley. 

Owing to the faunal break between the Hermosa and Rico formations, and to 

other evidence already several times referred to, I believe that sedimentation was 

not continuous in the San Juan region from one period to the other. It will be 

necessary, therefore, to discuss the age of the Rico fauna independently. Several 

years ago, when I think it may be said that less was knoWn of the sequence in Kansas 

and Nebraska, I had occasion to consider this same question, and reached the 

conclusion that the Rico period occurred late in the ansas section, not so late as 

the Marion formation, but about at ;the time of Pro ser's Neosho and Chase, the 

Permo-Carboniferous of Meek and Hayden, which he includes with the Marion to 

constitute the "Permian" of the Mississippi Valley. y conclusions at that time 
266 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

were in a measure expressed by Cross and Spencer in their report upon the geology 

of the Rico Mountains.a Considering the Rico fauna in the light of later evidence 

and further studies, I am disposed to think that I placed its age distinctly too late in 

'the Kansas section. 

In my early effort to correlate the Rico formation, which resulted in assigning 

. it to about the horizon of the Neosho and Chase formations of the Kansas section, 

the lines of evidence chiefly considered were the relative abundance of the brachiopods to the true Mollusca, and the range in the formations discussed by Prosser of 

such genera and species as seemed to have special significance. Prosser, as is well 

known, treated only the upper portion of the Kansas section,5 and the evidence of 

individual genera and species in the matter of correlation proved rather conflicting. 

Considerable weight was given the relative representation of the brachiopods, because 

their gradual disappearance seemed an important feature in the changes which 

marked the progression from the Wabaunsee to the Marion fauna. I held the 

opinion at the time, however, that this circumstance would be of only local significance unless it proved to be a part of the fanreaching vital changes that resulted in 

the extinction of nearly all the Paleozoic types of brachiopods. 

Later publications upon the earlier faunas of the Kansas section and further 

studies of my own have made it possible to reconsider the faunal evidence of the 

Rico upon a somewhat different basis, but with a result nearly as unsatisfactory. 

Except for Chonetes mesolobus the brachiopods of the Rico afford no evidence in 

point, for ,Seminula subtilita, Productus nebraskensis, Productus cora, and Chonetes 

glaber range from bottom to top of the Kansas series. Chonetes mesolobus, however, 

there appears not to pass beyond the Parsons limestone (No. 6). On the other 

hand, in the Sinbads Valley collection, the horizon of which is supposed to be below 

the Rico, we have characteristic Enteletes hemiplicatus, which does not appear in 

Kansas until the Iola limestone (No. 16), and Chonetes granulifer, which is 'first seen 

in the Lecompton limestone (No. 22) 

Among the Rico pelecypods are a few forms whose evidence may be considered. 

Pseudomonotis equistriata first appears in Kansas in the Iola limestone (No. 16), 

Pseudomonotis hawni in the Eskridge shales (No. 37), and Pseudomonotis kansasensis 

notis hawni, 

in the Garrison formation (No. 39). 

striata, 

be correlated with the top of the Kansas section (Marion formation), nor yet with its 

The absence of 

is introduced in the Iola (No. 16), and 

in the Eskridge shales (No. 37).c 

Bakewellia is -to be noted in the Rico fauna, which should hardly 

ilfyalina subquadrata, 

Bulimorpha chrysalis, 

like Pseudomonotis equilike Pseudomoa U. S. Geol. Surv., Twenty-first Ann. Rept., pt. 2, 1900, pp. 15-165. 

bJour. Geol., vol. 3, 1895, pp. 682-705 and 764-800. Geol. Soc. Am., Bull,, vol. 6, 1895, pp. 29-54. Jour. Geol., vol, 5, 

1897, pp, 1-16, 148-172. Kansas Univ. Quart., vol. 6, pp. 149-175, 1897. 

The range of species in the Kansas section can not be regarded as completely known, and the statements above are 

only approximations. 
FAUNAL EVIDENCE AND CORRELATION. 267 

very base. I feellittle disposed to defer the evidence of other species to Chonetes 

mesolobus, though the range of the latter in Kansas is confirmed by many observations. Compromising the somewhat conflicting evidence of the Rico genera and 

species and holding in view that of the Hermosa fauna, I think that the age of the 

Rico can hardly be earlier than the Iola limestone (No. 16) nor older than the Eskridge shales (No. 37). I am disposed to think that its age is somewhat intermediate 

between these two limits, or about the horizon of the Deer Creek; Hartford, and 

Howard formations, though this opinion is set down with diffidence and with a realization of the very slender evidence upon which it rests. ' 

Comparison between the faunas of Colorado and those of the Mississippi Valley 

with a view to correlation presupposes that both areas were connected with the same 

zoological basin, so that the same faunas had access to each simultaneously. The 

occurrence in Colorado of so many species identical with those in the Mississippi Valley 

leaves little doubt that this was the case. If land existed in Colorado during Upper 

Carboniferous time, or between Colorado and the Mississippi Valley, it could hardly 

have been sufficiently extensive to form a barrier to the migration of species from 

one to the other, or to shut off either area so that it was subjected to peculiar 

conditions checking or diverting the course of faunal evolution. 
DESCRIPTIONS OF SPECIES. 

Many works dealing with the geology of Colorado contain lists of fossils varying 

in extent and in the degree of care with which they appear to have been prepared, 

and the, evidence thus conveyed I have used as far as it seemed safe and as far as it 

bore upon my subject. 

Believing, however, that contradictions result from compilations of lists of 

species made by different individuals at different times, I shall employ in this portion of my discussion only such evidence in the way of collections of fossils as has 

come under my own observation. Deserving somewl- at different consideration are 

those works of paleontologic rather than geologic character which carry authority 

for the identifications made in them in the shape of descriptions and illustrations of 

species. In works of this sort the following species have been cited from Colorado: 

Eu_pitemus subpapillosus,a Prismopora trian,gulata,b Lophoph,yllum profundum var. 

sauridens,e llfargimife2.a muricata,a Oleioth,yris orbieularis,e Eueonispira taggarti 

Patellostium, cntrayense,g Nyalina euneiformis,4 Seminula subtilita,i and Eumetria 

woosteri.j 

Of these citations the original material in most cases has come under my observation and is included in the discussion of species and of • faunal evidence. The 

originals of lophophylbum _profundum var. sauridens, Cleiothyris orbieularis, and 

Seminula subtilita, however, have not come to hand. The two latter I have recognized in Colorado, though not from the locality of original citation. Lop hophyllum 

profundum also I have cited from the State, though not the variety sauridens, which 

may, however, be included in the material referred to the central form. 

a As Bellerophon subpapillosus from northwestern Colorado. White, U. S. Geol. Geog. Sum Terr., Twelfth Ann: 

Rept., for 1878, pt. 1, 1880, p. 138, pl. 34, fig. 3a. 

b As Ptilodictya triangulate from Yampa Plateau, northwestern Colorado. White, op. cit., p. 131, p1. 33, figs. 3a-e. 

cAs Lophophyllum proliferum var. sauridens from Rock Creek, Lake County, Colo. White, U. S. Geog. Geol. Bury. 

W. 100th Mer., Rept., vol. 4, 1877, p. 101, pl. 6, figs. 4a-d. 

dAs Produetus muricatus from Rock Creek, Lake County, Colo. White, U. S. Geog. Geol. Sum W. 100th Mer., Rept.. 

vol. 4, 1877, p. 120, pl. 8, figs. 4a-c. 

e As Spirigera planosuleata from Rush (probably misprint for Rock) Creek, Lake County, Colo. White, U. S. Geog. 

Geol. Surv. W. 100th Mer., Rept., vol. 4, 1877, p. 143, p1. 10, figs. 5a-d. 

f As Pleurotomaria taggarti from near Horseshoe Mountain, South Park, Colorado. Meek, U. S. Geol. Geog. Surv. 

Terr., [Seventh) Ann. Rept., for 1873, 1874, p. 231. 

g As Bellerophon ourayensis from Ouray, Colo. Gurley, New Carb. Foss., Bull. No. 2, 1884, p. 8. 

h From Ouray, Colo. Gurley, New Carb. Foss., Bull. No. 1, 1884, p. 4. 

As Athyris subtilita from the Sierra la Plata. Newberry, 13. S. Expl. Exped. from Santa Fe to Grand and Green 

rivers, 1876, p.-138. 

./ As Betzia woosteri from 18 miles north of Greeley. White, U. S. Geol. Geog. Sury Terr., Bull., vol. 5, 1879, p. 215. 

268 
DESCRIPTIONS OF SPECIES. 269 

MISSISSIPPIAN SPECIES. 

PROTOZOA. 

In the Aspen monograph Spurr cites a a number of foraminiferal genera from the 

upper portion. of the Leadville limestone of that region. These as determined by 

sissippian, and it may be mentioned in this connection that in 1899 I cited a small 

laria 

Mr. Bagg include 

L. parkerina. 

It is of interest to find so large and varied a fauna of this character in the Missp. similar to 7: 

Endoth,yra 

gibbosa, _Bigenerina 

sp., Nodosinella 

sp., 

sp. near X. 

ValvuUna sp., and 

priscilla 

Lagena 

Dawson, 

sp. near 

Textuvariety of Endothyra in a similar faunal association from the Madison limestone of 

Yellowstone National Park. 

None of the fossils mentioned by Spurr have come under my observation. 

Locality and horizon.—Leadville limestone; Aspen, Colo. 

CCELENTERATA. 

° ZAPHRENTIS Rafinesque, 1820. 

ZAPHRENTIS TANTILLA Miller. 

1891. Zaphrentis tantilla. Miller, Adv. Sheets Geol. Surv. Indiana, 17th Rept., p. 11, pl. 1, figs. 23, 24. 

Chouteau limestone: Near Sedalia, Mo. 

1892. Zaphrentis tantilla. Miller, Geol. Surv. Indina, 17th Rept., p. 621, pl. 1, figs. 23, 24. 

Chouteau limestone: Near Sedalia, Mo. 

1895. Zaphrentis tantilla. Keyes, Missouri Geol. Surv., vol. 4, p. 111. (Date of imprint, 1894.) 

Kinderhook limestone: Sedalia, Mo. 

Burlington limestone: Louisiana and Hannibal, Mo. 

These pretty little corals seem to be nearer to a form from the Chouteau limestone to which Miller gave the name Zaphrentis tantilla than to any other of our 

American species. 

In shape they are conical, elongate, moderately curved. A few constrictions 

of growth can sometimes be observed, but usually the form is smooth and tapering. 

Externally this species is distinguished by its small size and its regular and slender 

shape. It scarcely ever attains a diameter of over 10 mm., and more often it is only 

5 or 6 mm. The greatest observed length is 17 mm., and in this instance the diameter was only about 7 mm. In an example of 10 mm. diameter there are about 32 

primary septa whose expanded inner ends unite to form a thick wall about the rather 

large fossula. The latter is centrally situated, but extends to the corallum wall and 

contains at least one septum The septa are thickened at their outer ends also and 

cemented into a massive stereoplasmic wall. The thickened ends and the free intera U. S. Geol. Surv., Mon., vol. 31, 1898, p. 29. 
270 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

mediate portion divide each septum into three nearly equal parts. Embedded in the 

thick outer wall appear to be small secondary septa, but these do not project into 

the central cavity. There are a few dissepimental plates developed. 

It will be recalled that Z. tantilla has 24 septa at a diameter of 0.1 inch, but in 

a larger specimen there are said to be 30. In this respect, therefore, the Colorado 

form is fairly representative, but it may show some difference in the character of 

the fossula and in the matter of the secondary septa. 

Locality and horizon.—San Juan region (stations 2379, 2384); Ouray limestone. 

Crested Butte district (stations 2351, 2352, 2353, 2355, 2358); Leadville limestone. 

ZAPHRENTIS' sp. a. 

I am prevented by the fragmentary character and small amount of the material 

representing this species from identifying or giving a full description of it. The 

shape is elongate conical and the curvature slight. It is sometimes marked by strong 

concentric furrows. The largest fragment seen measures over 30 mm. in diameter. 

There are from 40 to 50 septa, which are of equal length and reach nearly, though 

probably not quite, to the center. Their inner portions are thick, but near the periphery they suddenly become more slender. At this point also they are usually united 

by sheets of massive dissepimental tissue which, appearing nearly simultaneously, form 

a more or less continuous circular wall. Between this and the epitheca, which is thin 

and delicate, the septa and dissepiments are also thin. Dissepimental tissue is fairly 

abundant. The fossula is strongly marked, though not large. In one instance at least 

it seems to be completely surrounded by the bent ends of the adjacent septa, and it 

usually contains one or two of the septa within it. The effect of the structures above 

described is to produce two zones, the inner one characterized by the massive nature 

of its structures; the other by their delicacy. As a result, the outer zone is often 

more or less broken away. Specimens occur in three conditions, some being entire, 

some retaining only the massive central portion, about which in others a more or less 

incomplete zone of the finer tissue without its outer wall is preserved. In fact, in 

one specimen all three states can be observed. Where only the inner zone remains 

(a condition in which it might easily be mistaken for a complete coral), a free specimen 

is seen to be covered with numerous saucer-shaped facets or, as it were, inverted 

blisters. 

I can hardly think that this coral is a proper representative of Zaphrentis, but am 

uncertain where to refer it. It has points in common with Campo_phyllum and is 

possibly related to that genus. 

Locality and horizon.—San Juan region (stations 2379, 2381); Ouray limestone. 

Crested Butte district (stations 2352, 2353); Leadville limestone. Aspen district 

(stations 2362, 2363); Leadville limestone. 
DESCRIPTIONS OF SPECIES. 271 

ZAPHRENTIS? sp. b. 

At Leadville (station 2374) occurs a form which is certainly a zaphrentoid coral, 

but regarding whose affinities it is impossible to affirm anything definite, so little in 

the way of structure, beyond the mere presence of septa, being discernible. In 

general form these corals are nearly straight and exhibit extreme inequalities of 

growth. The greatest diameter found• in our material is 12 mm., and the length 

must have been 30 mm. or more. The number of septa I have not been able to 

ascertain. 

Locality and horizon.—Leadville district (station 2374); Leadville limestone. 

ZAPHRENTIS? sp. c. 

This is the Axophyllum rudis of White.a As the impression is that of the outside of the corallum, preserving only the shape, neither the genus nor the species 

can be ascertained. 

Locality and horizon.—Pebbles of Millsap limestone (?) in the Red Beds conglomerate, Larimer County (station 2364). 

MENOPHYLLUM Milne Edwards and Haime, 1850. 

MENOPHYLLUM ULRICHANUM 11. sp. 

Pl. I, figs. 1, 2. 

1900. Streptelasma sp. (pars) Girty, U. S. Geol. Surv., Twentieth Ann. Rept., pt. 2, p. 38. 

Ouray limestone: Durango quadrangle (not Crested Butte region), Colorado. 

At several localities in the Mississippian strata of southwestern Colorado a wellcharacterized zaphrentoid coral occurs in considerable abundance. A somewhat 

careful search amongst our series of American forms has only led to the conviction 

that the species is as yet an undescribed one. Its generic affinities seem to be clearly 

with the genus lifenoph,yllum. Several years ago I described from Yellowstone 

National Park a species. of Illenophyllum whose horizon can not be far different from 

that to which the Colorado specimens belong. ilfeno_phyllum excavatum is, up to the 

present, the only member of the genus known from American strata; nevertheless, the 

descriptions of some of the forms referred to Zaphrentis are such as to warrant the 

suspicion that they really belong to the less common type. .1Ifeno_ph,yllum ulrichanum 

differs from M. excavatum, as it differs from most of the American species of 

Zaphrentis, in the large number of its septa. With due consideration to its smaller 

size, it may be said to rival in this regard Zaphrentis multilamella, Z. stansburyi, 

and Z. excentrica, all which forms, it will be remembered, are peculiar to our Rocky 

Mountain faunas. 

a U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, 1879, p. 215. 
272 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

lifeno_phyllum ulrichanum may be described as follows: Corallum simple, turbinate, small, rapidly expanding, and rather strongly curved. Marked by numerous 

irregularities of growth, resulting in concentric expansions and constrictions. The 

principal septa are thin and about 48 in number. There are smaller secondary septa 

alternating with them, which are, however, not to be observed below the calice. 

The septa below the calyce are so thickened _with stereoplasma as to form a nearly 

solid mass, and the constituent rays on this account can there scarcely be counted. 

Dissepimental tissue and tabulw appear to be entirely wanting. The principal 

fossette is large and joins the convex side of the corallum. The secondary fossulw 

are much smaller, but the tripartite arrangement of the septa is a distinctly marked. 

character. There are 13 principal septa in the divisions on either side of the 

principal fossette and 22 in the division directly -opposite it. The numbers here 

given, as well as the total number cited above, are derived from the calycinal cast 

figured on Plate I. In other examples of no greater size the number of septa 

developed, both primary and secondary, is fully one-fogrth greater than in this 

example. There seems to have been a solid (I), elevated, concentric platform in 

the center of the calice into which the principal fossula was deeply and strongly 

excavated. The corallum walls on the inside between the septa seem to have had a 

finely and rularly pitted surface, as is seen from the pustulose edges of a siliceous 

internal cast (fig. 2) of the calice of a specimen belonging to this species. 

utrichanum is smaller than X. ewcavatum, more rapidly expanding and more 

strongly curved. It also differs in, the much greater number of its principal septa. 

Simpson has recently described two genera of Zaphrentoid corals which appear 

to be closely allied to lifenophylbum. I refer to lifeniscophyllum and Triploph,yllum 

The resemblance is so strong, in fact, as to suggest that the latter, if not the former, 

is a synonym for Edwards and Hahne's genus. 

I avail myself of this opportunity to rectify an error into which I fell in the 

course of describing the Devonian fauna of the Ouray limestone, the only one which 

it was at that time known to contain. 

Corals were obtained from the Ouray limestone at two stations. At one of 

these in the Crested Suttee quadrangle (Gunnison 145a) they were found associated 

with the characteristic Ouray fauna. The other station was in the Durango quadrangle and the horizon occurred at the top of the Ouray limestone. In this case 

these fossils were found by themselves, unassociated with other species. Not knowing at that time that the upper portion of the Ouray limestone, locally at least, represented Mississippian time and contained a characteristic fauna of that age, I included 

these fossils in the Ouray fauna. I furthermore included those from both ;ocalities 

under a single heading as sStreptelasma sp., failing to observe differences which are 

clearly seen on reexamination. The specimens from the top of the Ouray from the 
DESCRIPTIONS OF SPECIES. 273 

locality on the east side of the Animas River, then called Durango 286, but now cited 

as station 2388, can be referred with little doubt to the species just described as 

ilfenophyllum ulrich,anum. 

The brief description accompanying the title Streptelasma sp., while based mainly 

upon the coral belonging to Heno_phylbum ulrich,anum, unfortunately- includes characters possessed by both species, and as a whole it will apply to neither. The only 

feature recorded from the Devonian form is that of the septa meeting in the center 

and being twisted. The other form possesses the characters of If. ulrichanum as 

cited above. The number of septa is greater than in the specimen figured on. Pl. I, 

but it is not greater than in other characteristic examples. The number cited in the 

earlier reference is from 60 to 64, and there is an alMost equal number of secondary 

septa. • 

The Devonian species is a larger and more slender form with perhaps 34 septa 

which are • differently arranged from those of 111: ulrichanum. Dissepimental tissue 

and tabulte are developed in moderate degree. This form would, I believe,.better be 

placed with Zaphrentis. 

Locality and horizon.— San Juan region (stations 2379, 2382, 2384, 2386, 2388); 

Ouray limestone. 

SYRINGOPORA Goldfuss, 1826. 

SYRINGOPORA ACULEATA Girty.. 

1899. Syringopora aculeata. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 509, pl. 67, figs. 5a, 5b. 

Madison limestone: Yellowstone National Park. 

The material presented does not retain its structures for satisfactory study, but 

in the size of the corallities, mode of growth, and such few characters as are' available, the fossils from Colorado agree with the types. 

Locality and horizon.-Crested Butte district (station 2359); Leadville limestone. Aspen district (station 2363); Leadville limestone. Salida region (station 

2260); Leadville limestone. 

SYRINGOPORA SURCULARIA Girty. 

1899. Syringopora surcularia. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 510, pl. 67, figs. 4a, 4b. 

Madison limestone: Yellowstone National Park. 

Several large fragments of this form were collected at Salida (station 2358) and 

a small one at Crested Butte (station 2360). The structures in both cases are poorly 

preserved, but the specimens probably belong to the species cited above. 

A specimen from the Rico region (station 2381) referred to S. surcularia occurs 

as external casts in chert. The corallites have a diameter of about 2.5 mm., and 

much resemble those of S. surcularia, but of course, strictly speaking, they are 

14364—No. 16-03 18 
274 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

indeterminable. The surface is shown to be prettily marked with delicate growth 

lines. 

gopora 

Crested Butte district (station 2358); Leadville limestone. Salida region (station 

2260); Leadville limestone. 

Possibly the fossil referred to among the Upper Carboniferous forms as 

L ocality and horizon.—San 

sp. belongs to S. surculcuria. 

Juan region (station 2381); Ouray limestone. 

SyrinECHINODERMATA. 

RHODOCRINUS Miller, 1821. 

RHODOCRINUS sp. 

Although the stems and plates of crinoids are by no means rare in the Lower 

Carboniferous limestones and cherts of the San Juan region, only a single complete 

specimen has come to hand. This was obtained from a locality in the Engineer 

Mountain quadrangle and probably belongs to the genus Rhodocrinus. It is preserved • as a cast (external and internal), but the definition of the plates is poorly 

shown, and their number and arrangement has not been made out. I have been 

unable to ascertain the exact specific relationship of this crinoid, but it appears to 

belong in the same group as Rh. kirbyi. The height is about 14 mm. and the diameter 11 mm. The general shape was, cylindrical, the base and top being nearly flat, 

and the lateral surfaces normal to them. The lateral and upper surfaces were ornamented with knobs and prominent protuberances. 

L ocality and horizon.—San Juan region (station 2382); Ouray limestone. 

PLATYCRINUS Miller, 1821. 

PLATYCRINUS sp. 

In the Engineer Mountain quadrangle (stations 2382 and 2385) occur several 

convex subpyramidal plates, the largest having a diameter of 10 mm., which are 

probably the basal plates of some unidentified species of Platycrinus. 

L ocality and horizon.—San Juan region (stations 2382 and 2384); Ouray limestone. 

BRYOZOA. 

FENESTELLA Lonsdale, 1839. 

FENESTELLA sp. 

Portions of fronds of fenestelloid bryozoa are not uncommon in the material 

collected in the San Juan region. They are, however, fragmentary and poorly 

preserved. At least three forms have been discriminated, and though I have not 

ventured to identify them definitely, the species are mentioned with which they seem 

to be nearly related. 
DESCRIPTIONS OF SPECIES. 275 

One of these, which occurs at station 2382 and probably also at station 2385, is 

allied to F. serratula Ulrich. It is characterized by its regular, fine mesh, and in 

this regard has about the proportions of the latter species, but seems to differ in 

having the dissepiments nearly as large as the branches, and not depressed, as they 

are represented in the figures of the type specimens. The fenestrules are subrectangular and somewhat longer than wide. The reverse side is covered with strongly 

elevated pustules on both branches and dissepiments. There are from 5 to 6 zocecia 

opposite two fenestrules. 

Another form, one whose closest allies I am unable to point out, is found at station 2382, and probably also at station 2386, where it is abundant. The branches 

divide frequently so that the fenestrules are of unequal size. Their shape is elliptical, with length about twice the breadth, to nearly circular. There are about 11 in 

the space of .10 mm. The dissepiments are nearly as wide as the branches themselves, and both seem to lack ornamentation of any kind. The zoweia are small and 

numerous, about 4 occurring opposite each fenestrule. When compared with the 

species last described, this one is larger and coarser, without the pustules with which 

the surface of the other is covered, •and with comparatively smaller and more 

numerous zocecia. 

There. is also a third species which seems to be intermediate between Elimitaris 

and F filistriata. It is represented by an external cast of the reverse side, which 

shows the surface to be ornamented with delicate but sharp stria. The fenestrules 

are rectangular in shape, three or four times as long as wide, and with some 8 or 9 

in a space of 10 mm. The dissepiments are much more slender than the branches. 

This species also occurs at station 2382. 

_Locality and horizon.—San Juan region; Ouray limestone. 

BATOSTOMELLA Ulrich, 1890. 

BATOSTOMELLA sp. 

In the San Juan region a few imperfect specimens were obtained which probably 

can be referred to the genus Batostomella. The material is so poor that no specific 

identification is suggested. 

Locality and horizon.—San Juan region (station 2382); Ouray limestone. 

FISTULIPORA McCoy, 1849. 

FISTITLIPORA ? sp. 

From the cherts at station 2382 in the San Juan region a specimen was obtained 

showing, as an external cast, a large ramose zoarium of what was probably a fistuliporoid bryozoan. It is of course indeterminable. 

Locality and horizon.—San Juan region (station 2382); Ouray limestone. 
276 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

BRACHIOPODA. 

RHIPIDOMELL A Oehlert, 1891. 

RHIPIDOMELLA PULCHELLA Herrick. 

1888. Orthis vanuxemi var. pulchellus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 38, pl. 5, fig. 9. 

Waverly group: Licking County, Ohio. 

1895. Orthis vanuxemi var. gracilis. Herrick, Geol. Surv. Ohio, Rept., vol. 7, pl. 21, fig. 9. 

Kinderhook: Granville, Ohio. 

1899. Rhipidoniella michelini. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 521. 

Madison limestone: Yellowstone National Park. 

This is a small, poorly characterized form, not materially different from several 

other representatives of the genus, and it may perhaps include what are only small 

or immature examples of some of the larger species such as Rh. oweni. All of 

my specimens, however, are small, rarely exceeding 15 mm. in greatest diameter. 

They are often somewhat transverse. The striation is very fine (about 20 strife in 

the space of 5 ram.) and appears to be tubulose and spinose. A form which is 

believed to be the same occurs in the Madison limestone of Yellowstone National 

Park, and I at one time identified it as Rh. michelini. A similar and probably 

identical species is found in the Cuyahoga shale of northern Ohio, and to a closely 

related, if not identical form, occurring at a somewhat higher horizon in central Ohio, 

Herrick has given the name Orthis vanuxemi var. _pulch,ella, which I have adopted 

for the Colorado form under discussion. 

Locality and horizon.—San Juan region (stations 2379, 2382, 2384, 2385); Ouray 

limestone. Crested Butte district (station 2358); Leadville limestone. 

ORTHOTHETES Fischer, de Waldheim, 1829. 

ORTHOTHETES INIEQUALIS Hall. 

1858. Orthis inequalis. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 490, pl. 2, figs. 6a-c. 

Chemung group: Burlington, Iowa. 

1865. Streptorhynchus inequalis. Winchell, "lead. Nat. Sci. Philadelphia, Proc., p. 117. 

Marshall group: Weymouth, Medina County, Ohio, 80 feet below conglomerate. 

1870. Hemipronites inequalis. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 251. 

Waverly group: Newark and. Granville, Ohio; near Shafers, Pa. 

1877. Streptorhynchus equivalvis. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 252, 

p1.4, figs. 1, 2. 

Waverly group: Ogden and Logan canyons, Utah. 

1883. Streptorhynchus .Tquivalvis. Hall, Rept. New York State Geol. for 1882, pl. (11A) 42, figs. 20-23. 

Waverly group: Burlington, Iowa. 

1892. Orthothetes inequalis. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 9A, figs. 20-23. 

Kinderhook group: Burlington, Iowa. 
DESCRIPTIONS OF SPECIES. 277 

1899. Orthothetes inwqualis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 522, pl. 68, fig. 3a. 

Madison limest,ne: Yellowstone National Park. 

1900. Orthothetes inwqualis. Weller, Acad. Sci. St. Louis, Trans., vol. 10, p. 66, pl. 1, fig. 18. 

Chonopectus sandstone: Burlington, Iowa. 

1901. Orthothetes inwqualis. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 159, pl. 14, figs. 16-18. 

Kinderhook: Bed 4, Burlington, Iowa. 

1901. Orthothetes inwqualist . Weller, Acad. Sci. St Louis, Trans., vol. 11, p. 195, pl. 19, fig. 

Kinderhook: Bed 7, Burlington, Iowa. 

The material representing Orth,othetes in the San Juan region, recently added to 

our collections, far exceeds in quantity all that had been previously obtain • d from 

other portions of the State, and of course, though often fragmentary, offer a much 

more complete presentation of the specific characters. I believe that I a. safe in 

referring all of this material to the same species. Nevertheless, because of i s scanty 

representation in all the areas but one, each set ,of specimens will be Co a sidered 

separately. 

In the San Juan region, as just intimated, the form seems to be rather a lentiful 

at a number of localities, I feel little hesitation in expressing the opinio that it 

is the same species which, in studying the fauna of the Madison limes a ne (of 

Yellowstone Park) I referred to Orthothetes inwqualis. The form is of medi m size, 

transversely semicircular, with subquadrate cardinal angles. The dorsal valve is 

moderately inflated, the ventral slightly concave or nearly plane. The vent .al area, 

which is not very high, makes a more or less acute angle with the general s rface of 

the valve. The ventral beak is small and ill defined, but produces in the cardinal 

outline a broadly obtuse-angular shape. The surface is crossed by numer a us, very 

slender radiating striae, the spaces between which, considerably wider han the 

elevations themselves, are traversed by delicate concentric striae. The radiating 

striae vary considerably in coarseness, but usually show a pretty regular alt • mating 

inequality, especially on the lower areas of the shell. The number of striae cries in 

different individuals from 9 to 14 in 5 mm., depending somewhat upon the p rt of the 

shell in which the measurement is taken. The same range of variation occurs i Yellowstone Park, and as it can frequently be found at one locality with the inte mediate 

conditions abundantly represented, this character does not, in my judgment, urnish a 

satisfactory basis for subdivision into species or even varieties in this case. In the 

matter of size a transverse diameter of 40 mm., though not infrequent, is a o ove the 

average. 

From the Crested Butte region there is only a single specimen, an i i perfect 

external cast of a ventral valve. It differs from characteristic specimens o Derbya 

crassa in being much larger and having the striation finer and somewhat lass alternating. It agrees in all the characters preserved with Orthothetes inmquali as seen 

in specimens from the Madison limestone. 
278 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The only specimen observed in the Leadville region consists of an imperfect 

external cast of a ventral valve. The generic position of this shell can not of course be 

exactly determined. Comparing the surface ornamentation with that of Derbya crassa, 

it is seen to be more finely striate; the striaa are not so strikingly alternating, and 

seem not to be crossed by strong concentric crenulations. So far as these characters 

are exhibited, it agreps with the shell from the Crested Butte region (station 2356) 

identified as Orthothetes inwqualis, and it may readily belong to the same species. 

' The conformation of the valve is similar to that of Derbya kaskaskiensis, but the 

striation is finer and less alternating than in the prevailing form of the Chester 

species. I can discover no intrinsic reason for holding it separate from the other 

forms referred to Orthothetes inwqualis. 

The only specimen representing this species from the Larimer County locality 

(station 2364) is an impression of an internal cast of the dorsal valve. It can not, of 

course, be determined whether this form is an Orthothetes or a Derbya. As far as 

the material permits one to judge, it might be referred with almost equal propriety 

to either Orthothetes inmqualis or Derbya kaskaslo,"ensis. Derbya crassa, with which 

Whitea identifies it, is distinguished from the Mississippian species just mentioned, 

among other differences, by the character of the concentric crenulations, which 

are stronger and more crowded. This feature, however, is not preserved in the 

impression before me, but there is a marked difference between the internal 

structural characters shown by this impression and those possessed by the specimens 

of D. crassa, which are illustrated by Meekb and by White.c It seems improbable, 

therefore, that this impression is that of a specimen of Derbya crassa, and as it does 

not differ materially from characteristic representatives of Orthothetes inwqualis from 

the Rico region and from Yellowstone National Park, I have referred it provisionally 

to that species. 

Our material from Canyon consists of two small internal casts, both probably of 

dorsal valves. If a Derbya, they would. probably be nearest related to the common 

D. crassa, but the hinge plate, the impression of which is retained in the better 

specimen, is less powerful and somewhat differently formed. In this particular it is 

similar to the impression from Larimer County (station 2364), but it is more finely 

striated and much smaller. In its size, which is but 18 mm. in transverse diameter, 

shape, and surface characters, though imperfectly shown, this form rather strongly 

recalls Orthothetes lens, but here again the cardinal structures are in disagreement, 

chiefly in the matter of the socket plates, which are nearly parallel to the cardinal 

line in one case, but which in typical O. lens are directed to it at an angle of about 

45°. On the whole it seems less likely that this form is a Derbya and related to D. 

a U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, 1879, p. 215. 


bU, S. Geol. Surv. Nebraska, etc., 1872, p1. 5, fig. 10b. 


e Indiana, Dept. Geol. Nat. Hist., Thirteenth Rept., 1884, pl. 26, figs. 9, 11. 

DESCRIPTIONS Ok` SPECIES. 279 

crassa and D. kaskaskiensis than that it is allied to Orthothetes inwqualis, a d I am 

prepared to believe that it is probably conspecific with the strophomenoids f om the 

Rico, Crested Butte, and other areas. 

Locality and horizon.—San Juan region (stations 2379, 2381, 2382, 238 , 2385); 

Ouray limestone. Crested Butte district (station 2356); Leadville limestone. Leadville district (station 2377?), Leadville limestone. Canyon (station 2366?), Millsap 

limestone. Castle Rock quadrangle (station 2367?); Millsap limestone. Pebbles 

of Millsap limestone (?) in the Red Beds conglomerate, Larimer County (station 

2364). 

CHONETES Fischer de Waldheim, 1830. 


CHONETES ILLINOISENSIS Worthen. 


1858. Chonetes logani. Hall, Geol. Surv. Iqwa, vol. 1, pt. 2, p. 598, pl. 12, figs. la-e, 2. (No C. logani 


N. and P., 1855.) 

Burlington limestone: Burlington, Iowa; Quincy, Ill. 

1860. Chonetes illinoisensis. Worthen, Acad. Sci. St. Louis, Trans., vol. 1, p. 571. 

Crinoidal Mountain limestone: Quincy, Ill. 

1863. Chonetes illinoisensis. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 5. 

Yellow sandstone and Burlington limestone: Burlington, Iowa. 

1865. 	Chonetes illinoisensis. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 116. 

Marshall group: Rockford, Ind.; Licking County, Ohio. 

Burlington limestone: Burlington, Iowa. 

1868. Chonetes illinoisensis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 3, p. 505, pl. 15, 

figs. 8a, b. 

Burlington limestone: Jersey County, Ill.; Burlington, Iowa. 

Kinderhook group; Wassonville, Iowa. 

1870. 	Chonetes illinoisensis. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 251. 

Waverly group: Rockville, Ohio. 

1877. Chonetes loganensis. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 253, p1. 4, 

fig. 9. 

Waverly group: Logan Canyon, Wasatch Range, Utah. 

1888. Chonetes illinoisensis. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 35, pl. 3, fig. 21. 

Waverly group: Licking County, Ohio. 

1890. Chonetes illinoisensis. Herrick, Geol. Soc. Am., Bull., vol. 2, p. 48, pl. 1, fig. 16. 

Keokuk: Scioto County, Ohio. 

1895. Chonetes illinoisensis. Keyes, Missouri Geol. Surv., vol. 5, p. 53. (Date of imprint, 1894.) 

Lower Burlington limestone: Louisiana and Ash Grove, Mo. 

1899. Chonetes illinoisensis. Weller, Acad. Sci. St. Louis, Trans., vol. 9, p. 15, pl. 4, fig. 10. 

Vermicular sandstone: Northview, Webster County, Mo. 

1899. Chonetes loganensis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 525, pl. 68, figs. 5a to 5c. 

Madison limestone: Yellowstone National Park. 

1900. Chonetes illinoisensis. Weller, Acad. Sci. SL Louis, Trans., vol. 10, p. 67, pl. 1, fig. 14. 

Chonopectus sandstone: Burlington, Iowa. 

1901. Chonetes sp. cf. C. illinoisensis. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 151. 

Kinderhook: Bed 3, Burlington, Iowa. 
280 CARBONIFEROUS FORMATIONS AND 'FAUNAS OF COLORADO. 

In a discussion of Ch. loganemis-based upon specimens from the Madison limestone of Yellowstone Park, I called attention to the almost exact correspondence 

between that species and one which had previously been described under the name 

of Ch. illinoisensis, but nevertheless retained Hall and Whitfield's name. I had 

not, nor have I now, any doubt of the identity of these two species, and have here 

definitely thrown into synonymy the name proposed for the Utah representatives. 

The material from Colorado, though not very plentiful or well preserved, is 

referred to this species with considerable confidence. 

Locality and horizon.—San Juan region (stations 2379, 2381); Ouray limestone. 

PRODUCTELLA Hall, 1867. 

PRODUCTELLA CONCENTRICA Hall. 

1857. Productus concentricus. Hall, New York State Cab. Nat. Hist., 10th Rept., p. 180. 

Chemung sandstone: Burlington, Iowa. 

1858. Productus shumardianus (pars). Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 499, pl. 7, fig. 1 (not 

pl. 3, fig. 9). 

Chemung group:' Burlington, Iowa. 

1858. Productus concentricus. Hall, Geol. Surv., Iowa, vol. 1, pt. 2, p. 517, pl. 7, fig. 

Chemung group: Burlington, Iowa. 

1860. Productus cooperensis: Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 640. 

Chouteau limestone: Cooper County, Mo. 

1862. Producta concentrica. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 411.. 

Marshall group: Pointe Aux Barques, Mich. 

1865. Producta concentrica. Winchell, Acad. Nat. Sci. Philadelphia, Proc.., p. 114. 

Marshall group: Northern and southern Michigan; Burlington, Iowa; Rockford, Ind. 

1865. Producta cooperensis. Winchell, Acad. Nat: Sci. Philadelphia, Proc., p. 115 (not Winchell, 1870) . 

Bed No. 1: Burlington, Iowa. 

1869. Producta concentrica. Winchell, Safford's Geol. Tennessee, p. 443. 

Shales just above Black Shale: Hickman and Maury counties, Tennessee. 

1870. Producta concentrica. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 249. 

Waverly group: Tennessee; Sciotoville, Ohio. 

1883. Productella shumardiana. Hall; Rept. New York State Geol. for.] 882, p1. (17) 48, fig. 

Sandstone: Burlington, Iowa. 

1888. Productus concentricus. Herrick, Sci.- Lab. Denison Univ., Bull., vol. 3, p. 33, pl. 6, fig. 1,6. 

.Waverly group: Licking County, Ohio. 

1888. Productue (Productella) shumardianus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 32, p1. 

7, fig. 18; pl. 12, figs. 6, 43. 

Waverly group: Licking County, Ohio. 

1892. Productella shumardiana. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 17, fig. 7. 

Yellow sandstone: Burlington; -Iowa. 

1899. Productella concentrica ? Weller, Sci. St. Louis, Trans., vol. 9, p. 17. 

Vermicular sandstone: NorthView, County, Mo. 
DESCRIPTIONS OF SPECIES. 281 

1899. Productella cooperensis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 528, pl. 68, figs. 8a-8e, 

9a, 9b. 

Madison limestone: Yellowstone National Park. 

1901. Productella concentrica. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 184, pl. 16, figs. 12-14. 

Kinderhook: Bed 6, Burlington, Iowa. 

There are but two specimens in our collections from Colorado which represent 

this species, both of them small and imperfect. They are not referred without reservation to Productella concentrica, for lack of conclusive evidence, but at the same time 

I know of no reason for mistrusting the identification. 

In discussing the synonymy of this species in 1896 I expressed the opinion that 

Productella skumardiana and P. concentrica are distinct, but that the former is probably identical with P. pyxidata. Some ambiguity is probably introduced into this 

utterance, and into those of Winchell and Herrick as well, from the fact that under 

the name Productus shulnardiconts two species were probably included by Hall. One 

of these is represented by figure 9 of plate 3 among the Hamilton fossils and the 

other by figure 2 of plate 7 among those of Chemung age. The former was obtained 

from Clarksville, IVIo., and the latter from Burlington, Iowa. It matters not that 

Hall was in error in regard to the age of these fossils. They came from very different localities and from somewhat different horizons. In the case that these two forms 

thus differently derived are, as an inspection of the figures would lead one to believe, 

specifically different, I propose to restrict the name P. shumardiana to the Clarksville form, which is the first figured in the plates and the first mentioned in the text. 

With the disposition of P. skamardiana, whether it is retained as a distinct form or 

is placed in the synonymy of P. pyxidata or of P. subalata, I am not now concerned. 

I believe, however, that the Burlington form.of P. shumardiana is only a dorsal valve 

of a specieS which is described from the same place under the name of P. concentrica. 

This conclusion is one which can be absolutely vindicated only by a comparison of 

the types themselves. The collateral evidence, however, seems to me all but convincing, since in one case we have specimens from different localities and different 

horizons which excellent figures show to be different and in the other specimens from 

the same locality and the same horizon which excellent figures show to be the same. 

The opinion is still entertained that P. cooperensis is a synonym for P. concentrica 

and that Winchell's identification of it from Sciotoville is based upon a distinct though 

related species. 

Locality and horizon.—San Juan region (station 2379); Ouray limestone. 
282 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PRODUCTITS Sowerby, 1814. 

PRODUCTU S SEMIRETICULATUS var. 

1847. Productus semireticulatus (pars). De Koninck, Monog. du Gen. Prod. et Chon., p. 83, p1. 8, figs. 

la-h; pl. 9, figs. la-m; pl. 10, figs. la-d. 

Carboniferous: Harrisville, Bagdad, Cuyahoga, Zanesville, Flint Ridge, Greensburg, and Antrim, 

Ohio; near Louisville, Ky.; near St. Louis and St. Charles, Mo.; Leavenworth, on the Missouri River; Long Creek, Crawfordsville, and near New Harmony, Ind.; Sparta, Ill.; Bolivia, 

South America. 

1858. 	Productus semireticulatus. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 637. 

1863. Productus semireticulatus. Davidson, Geol. Soc. London, Quart. Jour., vol. 19, p. 174, pl. 9, figs. 

20, 21. 

Lower Carboniferous limestone: Windsor, Brookfield, Shubenacadie, East River, Debert River, 

Minudie, Pugwash, near Amherst, Boulardarie, Cape Breton, Horton Bluff, Grays River, etc., 

Nova Scotia. 

1865. Producta semireticulata. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 115. 

Marshall group: Weymouth, Medina County, Ohio; Orange, Cuyahoga. County, Ohio. 

1868. Productus semireticulatus. Dawson, Acadian Geology, p. 296, pl. 97a, b. 

Carboniferous limestone: Windsor, Brookfield, Shubenacadie, East River, Debert River, Minudie, Pugwash, near Amherst, Boulardarie, Cape • Breton, Horton Bluff, Grays River, etc., 

Nova Scotia. 

1869. Producta semireticulata. Winchell, Safford's Geol. Tennessee, p. 442. 

Immediately above black shale: Manchester, Cannon County, Tenn. 

1870. Producta semireticulata. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 249. 

Waverly group: Newark, Sciotoville, Rockville, and Vinton County, Ohio; near Shafers, 

Venango County, Pa. 

1877. Productus semireticulatus. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 267, 

pl. 5, figs. 5, 6. 

Lower Carboniferous limestone: North of Snowstorm Hill, Dry Canyon, Oquirrh Mountains, 

Utah. 

1878. Productus semireticulatus. Dawson, Acadian Geology, 3d ed., p. 296, figs. 97a, 97b. 

1888. Productus semireticulatus. Heriick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 31, pl, 1, fig. 26; 

pl. 6, fig. 11; pl. 10, figs. 6, 6a. 

Waverly group: Licking County, Ohio. 

1897. 	Productus semireticulatus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 30. 

Lower Coal Measures: White County, Ark. 

Marshall shale: Stone County, Ark. 

Fayetteville shale: Searcy County, Ark. 

Boone chert: Seamy County, Ark. " 

1899. Productus semireticulatus. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 535, pl. 69, figs. 8a-d. 

Madison limestone: Yellowstone National Park. 

1900. Productus semireticulatus. Weller, Acad. Sci. St. Louis, Trans., vol. 10, p. 70, pl. 1, figs. 5, 

Chonopectus sandstone: Burlington, Iowa. 
DESCRIPTIONS OF SPECIES. 283 

In a report published in 1899 dealing with some Carboniferous fossils from 

considerably from the type represented by the figures. These same varieties occur, 

for the most part, in the limestones of Burlington and Keokuk age in the Mississippi 

reticulatus, 

Yellowstone National Park I recognized the cosmopolitan species 

material thus identified showed a wide range of variation, some of it departing 

several individuals of which were figured. Mention was made that the 

Productus semiValley, and have there been distinguished by different specific names. The material 

from the Park, being both scattered, scanty, and often fragmentary, did not lend 

itself to nice specific discriminations. Nevertheless, I believe that subdivisions 

should then have been made. 

The Colorado material is still more imperfect than that from. Yellowstone Park, 

but does not embrace as widely divergent types. At the same time, I am not confident that two species or varieties may not be present. The same form or forms are 

found in Yellowstone Park and in.the lower Mississippian faunas of the Mississippi 

Valley. It is doubtful if any of these Mississippian forms, commonly identified with 

P. semireticulatus, show precise specific identity with the dominant type of the Upper 

Carboniferous, and at least there is nothing in the fauna of the Hermosa formation, 

so far as it has been brought to light, with which a critical comparison would justify 

identifying the fossils which form the subject of these notes. 

In the matter of synonymy I have brought together all, or at least the most 

important citations of American Mississippian forms, not so much to imply that 

they are all one species, or the same as my Colorado material, but to indicate that, 

as I believe to be the case, these Mississippian forms are distinct from the Pennsylvanian ones. 

Locality and horizon.—San Juan region (stations 2379, 2381, 2382, 2384); Ouray 

limestone. Crested Butte district (station 2354); Leadville limestone. 

PRODUCTUS PARVIFORMIS Girty. 

1899. Productus parviformis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 536, pl. 68, figs. 6a-6d. 

Madison limestone: Yellowstone National Park. 

At one locality in the San Juan region (station 2381) occurs a form in some 

abundance which I believe can be safely identified with Productus parviformis. The 

only difference which I am able to point out consists in the fact that the individuals 

from Colorado are apt to be a trifle undersized. 

Locality and horizon.--San Juan region (station 2381); Ouray limestone. 

PRODUCTUS cf. PITSTULCISUS Phillips. 

1836. Producta pustulosa. Phillips, Geol. Yorkshire, vol. 2, p. 216, pl. 7, fig. 15. 

Mountain limestone: Bolland; Florence Court. 

1857. Productus pustulosus. Davidson, Pal. Soc.; British Carb. Brach., pt. 5, p. 168, pl. 41, figs. 1-6; 

p1. 42, figs. 1-4. 
284 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1857. Carboniferous limestone: In England at Bolland, Settle, Kendal, Isle of Man, Derbyshire, etc.; 

in Scotland at Cat Craig, near Dunbar. 

Calciferous slate and Carboniferous limestone: In Ireland, Bundoran, Ballyduff, Carrigaline, 

Lisnapaste, Millejent, Tankardstown, Florence Court, Little Island, shores of Lough Gill,_ 

valley of the Maine, Hook, St. Doolas, near Dublin, etc. 

On the Continent at Vise and Tournay, etc., in Belgium; Ratingen, in Prussia; and also in 

America. ' 

Of this species there is bu a single specimen, somewhat fragmentary and poorly 

preserved. It had previoxisly been identified as P. nevaclensis, but can hardly be a 

true representative of Meek's species. It is almost certainly of the pustulosus type, 

but strictly speaking may not belong to that species. It much resembles the form 

figured by Davidson on plate 42, fig. 4, of his monograph (loc. cit.). It is a rather 

large shell, with a distinct though not deep median. sinus, crossed transversely by 

closely arranged, concentric corrugations, and roughened by numerous fine pustules 

or spine bases (?). 

This species is evidently related to the species from the Madison limestone which 

I identified as P. scabriculus Martin, but seems to be specifically distinct. It is 

unlike any form known to occur in the Ouray limestone (Devonian) or in the Hermosa formation (Pennsylvanian). 

Locality and horizon.—Aspen district (station 2362); Leadville limestone. 

PRODUCTUS L4EVICOSTA White. 

1860. Productus lxvicostus. White, Boston Soc. Nat. Hist., Jour., vol. 7, p. 230. 

Burlington limestone: Burlington, Iowa. 

1874. Productus prattenianus (= ? P. lxvicostus). White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. Invert. Foss, p. 17. 

1875. Productus prattenianus (pars.). White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, 

p. 113. (Entire volume published in 1877. ) 

Subcarboniferous: Mountain Spring, Lincoln County, Nev., and below Ophir City, Utah. 

1877. productus lamicostusf Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 266, 

pl. 5, figs. 7, 8. 

Lower Carboniferous limestone: North of Snowstorm Hill, Dry Canyon, Oquirrh Mountains, Utah. 

(?) 1887. Productus sp.? compare prattenianus. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 18, 

fig. 4. 

`Waverly sandstone: Newark, Ohio. 

.1895. Productus lxvicostus. Keyes, Missouri Geol. Surv., vol. 5, p. 41, pl. 38, fig. (Date of imprint 

1894.) 


Kinderhook group: Louisiana, Mo. 


Burlington group: Louisiana, Mo. 


1899. 	Productus l.vicosta. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 534, pl. 69, figs. 9a-9c. 

Madison limestone: Yellowstone National Park. 

1900. Productus Levicosta. Weller, Acad. Sci. St. Louis, Trans., vol. 10, p. 71, pl. 1, figs. 1, 

Chonopectus sandstone: Burlington, Iowa. 
DESCRIPTIONS OF SPECIES. 285 

In the San Juan region (at stations 2379 and 2382) occurs somewhat scantily a 

little Productus of the cora type which, because of its associations, I have referred 

to P. la3vicosta. It resembles in every essential specimens from Yellowstone Park 

belonging to. White's species, and is chiefly peculiar for its rarity and its small size. 

Twelve millimeters is the transverse diameter of the largest specimen seen, and only 

three or four have come to hand. Into the synonymy of this species I have introduced several references withdrawn from the Pennsylvanian species, P. cora. Probably several other citations of P. cora (or P. prattenianus) from Mississippian horizons 

should be removed to the synonymy of this species. It is possible, however, that 

Productus lwvicosta is a synonym of P. cora. 

Locality and horizon.—San Juan region (stations 2379, 2382); Ouray limestone. 

SPIRIFER Sowerby, 1815. 

SPIRIFER CENTRONATITS 

1865. Spirifera centronata. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 118. 

Marshall group: Cuyahoga Falls and Akron, Ohio. 

1874. Spirifer centronata. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. Invert. Foss., p. 17. 

Subcarboniferous: Mountain Spring, Old Morman road, Nevada. 

1875. Spirifer centronatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 86, pl. 5, 

figs. 8a-8c. (Whole volume published in 1875.) 

Subcarboniferous: Mountain Spring, Old Morman road, Nevada. 

1875. Spirifera (Trigonotreta) biplicata. (Hall?) Meek, Pal. Ohio, vol. 2, p. 290, pl. 14, fig. 5. 

Waverly group: Richfield, Ohio; Iowa. 

1877. Spirifera centronata. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 254, pl. 4, 

figs. 5, 6. 

Near base of Wasatch limestone (Waverly?) : Dry Canyon, Oquirrh Mountains; Logan and 

Ogden Canyons, Wasatch Range, Utah. 

1899. Spirifer centronatus. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 547, pl. 70, figs. 3a-3d. 

Madison limestone: Yellowstone National Park. 

1901. Spirifer centronatus. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 163, pl. 14, figs. 3-4. 

Kinderhook: Bed 4, Burlington, Iowa. 

This species is more abundant than any other in the faunas from Colorado, 

which I regard as of Mississippian age. It occurs in abundance in the San Juan, 

Crested Butte, and Canyon regions, and amongst the impressions from Larimer 

County, but it has not yet been identified at Leadville or at Perry Park. With some 

exceptions the Colorado material possesses somewhat coarser ribs than that from 

Yellowstone Park or the specimens from Utah figured by White and by Hall and -

Whitfield, but it agrees with perhaps the majority of typical representatives of the 

species from the Cuyahoga shale of northern Ohio. The latter show a certain 

amount of range in this particular, quite sufficient to embrace both forms. 

The variety with coarse striae might pass without challenge for a form from the 

Hermosa formation which I have identified as Sp. boonensis. 
286 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Among the impressions from Larimer County both a coarsely and a finely 

striated variety can be distinguished. These specimens were identified by White a 

as Sp. rockyrnontanus. Marcou's name certainly represents a very variable type, 

to judge by his figures, even if it does not include more than a single species. 

These specimens, however, have unusually fine ribs, even for the Waverly species, and 

I know no Spirifer in the Upper Carboniferous resembling them in other respects 

which equals them in this. A similar form occurs in the Hermosa formation, but 

bescen,s, 

outlined, as well as in other particulars. 

ever; are not unlike 

those shells have coarser ribs and are comparable rather to 

• In the Crested Butte region this species occurs in relative abundance. The 

and the coarse variety of 

Sp. subxqualis, 

Sp. centronatus. 

but they differ in having the sinus more sharply 

The fine-ribbed specimens, howSp. keokuk, Sp. increcoarsely ribbed type predominates, and one specimen is so large and coarsely plicated 

that I have separated it as a distinct variety. 

In the whitish cherts from. near Canyon, Garden Park, and the vicinity, this species has been collected at nearly every locality and frequently occurs in great abundance. The shape varies from subquadrate to subtriangular. The hinge line is as 

long as the width of the shell and usually somewhat longer. There are 3 to 7 plications in the sinus, according to size, and from 12 to 17 lateral ones. The latter frequently manifest a tendency to be broad and flattened instead of sharply rounded, as 

is characteristic of Sp. centronatus, and occasionally those nearest the fold or sinus 

are distinctly bifurcated. Bifurcation of the lateral plications of typical 

alone can be seen, but on well-preserved specimens the radiating ones appear and 

system of minute radiating and concentric strive. In most cases the concentric striae 

natus 

they then seem to be nearly as strongly marked as the others. 

itself is not unknown, though it is not common. The surface is marked by a 

Sp. centroThe material from the San Juan region is so similar to that from the Madison 

limestone of Yellowstone Park, and associated with a fauna s9 manifestly allied to 

that which accompanies the latter, that I feel no doubt of their specific identity with 

one another or with typical Sp. centronatus from Ohio. 

Locatity and horizon.—San Juan region (stations 2379, 2381, 2382, 2384); Ouray 

limestone.. Crested Butte district (stations 2350, 2352, 2354, 2355, 2356, 2357); Leadville limestone. Salida region (stations 2360, 2361); Leadville limestone. Canyon 

(stations 2366, 2370); Millsap limestone. Pikes Peak quadrangle (stations 2365, 

2368, '2369, 2371); Millsap limestone. Castle Rock quadrangle (station 2367); 

Millsap limestone. Pebbles of Millsap limestone (?) in the Red Beds conglomerate, 

Larimer County (station 2364). 

a U. S. Geol. Geog. Surv. Terr., Bull.. vol. 5, 1879, p. 215. 
DESCRIPTIONS OF SPECIES. 287 

SPIRIFER sp. a. 

The only material at present in the collection which could have served as 

evidence for the appearance of Spirifer rockymontanus in the faunal list of the Blue 

limestone given in the Leadville monograph,a consists of two imperfect specimens 

from station 2377. They are mere fragments of external casts, consisting of a 

group of radiating stri, none of the finer ornamentation having been preserved. 

From the curvature of the surface and the character of the plications I judge that 

these impressions were made by a Spirifer. The species is most likely of the imbrex 

type, as the latter is defined by Hall and Clarke. The sinus was very faintly 

bounded and elevated, and contained, if its limits are correctly ascertained, four or 

five plications. These are too fine and too numerous to afford much probability 

that this form is identical with Sp. rockymontanus, Sp. keokuk, or Sp. in•crebescens, 

and an exact identification is clearly impossible. The plications are no finer than in 

a fine example of Sp. centronatus, such, for instance, as one of the impressions from 

Larimer County, but if really belonging to the Waverly species they are particularly 

large specimens with plications unusually slender for the size of the shells. 

Locality and horizon.—Leadville district (station 2377); Leadville limestone. 

SPIRIFER sp. b. 

In the "Blue limestone" of the Leadville region, a small SpirVer is found, frequently in considerable abundance. It is this form which appears in the faunal list 

of the Leadville monograph as Spin:ferina sp. probably new, cf. Sp. kentuckiensis.a 

The unfortunate preservation of this form renders it difficult of study, and its 

generic position is still somewhat uncertain. It occurs in a matrix of chert and 

therefore but little can be done in the way of manipulation. The shell substance has 

been completely removed or is otherwise so altered that it can not be told whether 

the structure was punctate or merely fibrous. The cavity thus left has in many cases 

been coated with a rusty or siliceous deposit, which often entirely obscures the 

superficial markings. 

The shape is that of Spiiriferina and of the Delth,yris group of spirifers. The 

shell is transverse, semicircular. The cardinal angles seem to be rounded and the 

hinge line is thus a little shorter than the width of the shell below. The area of the 

ventral valve is rather high and incurved. The fold and sinus are moderately broad 

and high, and are marked respectively by a median groove and ridge which can be 

clearly seen in most specimens. The, fold and sinus are otherwise simple. The sides 

are marked by 5 or 6 simple strong plications. Large representatives of this species 

have a transverse diameter of at least 24 mm. 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 66. 
288 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In neither valve is a septum developed, and the dorsal as well as the ventral 

shell is furnished with dental plates. In most ventrals, though the dental plates are 

moderately strong, there is no trace, even, of a septum. In others, a shallow groove, 

which can sometin, es be made out, proves that this structure was sometimes present, 

although insignificant. Several specimens agree in showing that the dorsal valve 

possessed dental plates developed to almost as great a degree as in the ventral one. 

No apical callosity can be seen. 

The surface is practically free from radiating or concentric stri. Sometimes 

varices of growth occur, and often a marginal band of varying width is marked by 

concentric lamellosities, but most of the surface is essentially smooth in this regard. 

It is, however, shown to be finely pustulose or spinose. This is clearly seen in casts 

of the exterior. In one specimen the holes which the spines have left in the matrix 

are closed by tiny plugs of rock, the shells matter being represented by rings of 

white about them. This would seem to indicate that the spine was hollow. Another 

example, equally favorable, shows only rows of perforations. Several other specimens, while disclosing the spinose character of the surface in an unmistakable manner, do not give clear evidence as to whether the spines were solid or hollow, but the 

opinion resulting from a careful study of all the material is that they were hollow. In 

the specimen first mentioned they are arranged in alternating concentric rows, the 

lateral distance lietween any two adjacent elements in the same row being distinctly 

less than the diagonal distance between those in adjacent rows. Along the anterior 

margin, where overlapping lamellae occur, they are more crowded and irregular. In 

other shells they are sometimes closely arranged and irregular, but usually 'a quincunx assemblage can be made out. The shape of the spines is oval or elliptical for 

the most part, with often a linear projection at one end or the other, and in less distinct preservation the surface of the cast looks to be traversed by very fine interrupted striae. 

The affinities of this shell are puzzling. The absence of a septum and the presence of well-developed dental lamellW in the dorsal valve would seem to forbid its 

being referred to Spiriferina in spite of the superficial resemblance to members of 

that genus. If admitted into the Spiriferina group, however, it would, by reason 

of its surface, be more closely allied to Sp. spinosa than to the kentuckyensis section, 

but as to its specific distinctness from Sp. s_pinosa itself there can be no question. 

The spines are finer and more numerous, and the fold and sinus show a median 

groove and ridge, not to mention differences in shape and others of a like nature. 

But besides these superficial differences its structural onek, already pointed out, are 

of a sufficiently fundamental character to bar it from the genus Spiriferina altogether. 

It seems, therefore, that its place should be sought among the true spirifers. It does 

not, however, agree satisfactorily with any of the six divisions of Spirifer recog-
DESCRIPTIONS OF SPECIES. 289 

nized by Hall and Clarke. It can evidently not be grouped with the radiati nor 

with the lam,e4losi, nor yet with the great group of the aperturat ", while the 

glabrati are too unlike in every way to require consideration. Howev r, this shell 

seems to show a certain parallel development in internal structure with artiniopsis 

of the glabrati, as in that genus both valves possess dental lamellae With the 

ostiolati many points of similarity exist. "Many of the middle Dev nian representatives," say Hall and Clarke, a " bear a low, median sulcus on the fold, which 

may be accompanied by a broad, very faint, indistinct plication appare t only near 

the anterior of the sinus." Some species have the plications covered ith elongate 

pustules (Sp. granulosus and Sp. marcyi) or erect granules (Sp. riper) and in Sp. 

parryanus the minute elongate pustules are arranged upon the summit of distinct, 

fine, radial striae (Hall and Clarke). Another character, which is f re uently met 

with in this group, is the callosity developed in the apex of the delthyri m. 

In general configuration the form under discussion agrees with the. ostiolati 

even to the extent of showing a median groove on the fold and a c rresponding 

elevation in the sinus, but the ostiolati are characteristically large and stout shells, 

while this is a very small one. 

The surface ornamentation may be conceived to be the same, but aft r examining 

the surface of a number of the ostiolate spirifers, I am led to believe that the granules 

or pustules are related to the superficial layers of the shell and are s lid, while in 

the form under comparisod they are believed to be hollow. In this f rm the callosity characteristic of the tiolati is not known to occur, nor, I belie e, are there 

found in the ostiolati the d ntal lamellae which seem to be a constant ature of its 

internal structure. The e idence, therefore, seems on the whole to eparate this 

form from the ostiolati. .ts affinities are, indeed, possibly closer ith the fimbriati than with any other group. If my conclusions regarding the ch racter of its 

surface tally with fact, namely, that the spines are simple and hollow, t would fall 

by reason of this and other characters within the unicispinei division o that group. 

strong plications. However, the surface of the 

to division in the fold and sinus. Of the two subsections recognized by Hall and 

Clarke this species belongs undoubtedly to type 

cispinei, 

It agrees in its short hinge line, spinose surface, and simple plications ith the 

among which certain forms, as for instance 

a, 

unicispinei 

or 

Sp. vanuxemi, 

the crispus 

is closely mellate, the 

type, ecause of its 

exhi it a tendency 

unllamellae bearing fimbriw of crowded spines, while the surface of SpirVe sp. b shows 

no regular concentric lamellae, and, though the spines are in concentric r ws, they are 

inclined to be distributed at regular and comparatively distant interva s. A structural difference of some importance consists in the dental lamellae of th dorsal valve 

a Pal. New York, vol. 8, pt. 2,1894, p. 29. 

14364—No. 16-03 19 
290 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

of Spirifer sp. b, structures which do not occur in Sp. cris_pus, Sp. van,uxemi, and 

their allies. 

On the whole it seems more probable that this form is a true Spirifer, a survivor, 

possibly, of the earlier type abundant in Silurian and early Devonian time, one 

which departs so far from its nearest allies, the unicispinei, that it can hardly with 

propriety be referred to the same subordinate group. Indeed, if the appearances 

described are real 'characters of the shell, and of this I have little doubt, it can only 

be regarded as an aberrant member of any of the groups recognized by Hall and 

Clarke, and should other species possessing similar characters be brought to light, I 

believe they would better be recognized as an independent section. The salient 

characters of this form which would probably apply in large measure to the whole 

subsection are its small size, primitive shape (like that of Delthyris), short hinge 

line, spinose surface (the spines not being mounted upon the edges of concentric 

lamelloa, which are in fact practically absent),a the absence of a septum in the ventral 

valve, and the presence of dental lamellae in both valves. 

The stratigraphic significance of this species depends chiefly upon which spiriferoid group it is conceived to be closest allied to. In my own view its affinities 

with any of the known groups of American spirifers is so remote that its bearing in 

that relation can not yet be estimated. In this connection attention may be called to 

Sp. agelaius Meek, which may possibly be based upon small or immature shells of this 

species. The similarity is not so great as to be impressive, but our lack of knowledge 

regarding the minutiae of Meek's species does not permit a decision in the negative. 

The most closely allied species which I have been able to find, however, is a little shell 

from the Louisiana limestone of Missouri, described by Rowley under the name Spirifer 

or Spinferina acieubfera.b This species also is a spine-bearer, but as its internal 

structures are not known no comparison with the Colorado form can be made in this 

direction. It is improbable that Rowley's species is a true ASPirferina. Rowley 

has recently described another little shell which is externally similar to the form 

from the Leadville limestone. I refer to Spirifer sch,uch,erti c which was found in 

the Lower Burlington limestOne at Louisiana, Mo. Though a somewhat smaller 

form, the essential superficial resemblance is marked, but it is uncertain whether the 

internal characters would show an equal agreement. 

In configuration this species simulates the form referred to Spir?ferina 

irostris, though it differs from the latter in every essential particular. The two 

forms can usually be discriminated even superficially, however, as.S_pirVer sp. b has 

rounded cardinal angles and a more distinct median plication on the fold and sinus, 

a The surface ornamentation evidently varies somewhat in different individuals in regard to the shape of the spines, 

their abundance, and arrangement, but all specimens agree in showing the essential absence of lamellose striae as a 

normal system of surface ornamentation and the abundance of minute, simple, hollow spines. 

Am. Geologist, vol. 12, 1893, p. 307, p1. 14, figs. 13, 14. 

c Ara. Geologist, vol. 25, 1900, p. 261, p1. 5, figs. 15, 16, 17, 59. 
DESCRIPTIONS OF SPECIES. 291 

which are also proportionately a trifle broader. In surface ornamentation, shell 

structure, and internal characters the two forms are widely different. 

The preceding remarks are based upon abundant but unsatisfactory material 

from the Leadville region. There has lately come into my hands a block of chert 

from Perry Park, Colo., upon whose surface numerous specimens of this species 

occur. They are all internal casts, but present the characters superficial and structural of the Leadville form, although ranging considerably s aller in size. The 

lithologic appearance of these fossils from Perry Park is identically that of the 

the Canyon material, and at first sight the little Spiriferina of the latter locality 

might be mistaken for the small Spirifer of the former. Closer examination, however, shows them to be entirely distinct. Even the punctation, traces of which are 

distinctly preserved upon the cherty casts from Canyon, are lacking upon those 

from Perry Park. 

Among the impressions taken at the Larimer County locality are those of two 

small spiriferoid shells which are believed to belong to this species, although I 

originally placed them with Spiraferi/na solidirostris? . As: the impressions were 

made from external casts, their generic position is a matter of conjecture. They 

are of moderate size, with a transverse diameter of about 14 mm. The ventral valve 

is gibbous and the area appears to be high and incurved. There are six. ribs each 

side of the median sinus, which is somewhat broad and shallow, with a small median 

plication. In one specimen the surface appears to be smooth, but in the other it is 

marked by a number of lamellose varices of gro th. 

Neither Spiriferina spinosa nor Sp. campest shows a Aalf-developed rib within 

the sinus, and, if the impressions belong to Sp iferina at all, this character would 

seem to ally them rather with the lamellose sec on of the genus. There, however, 

inequalities of growth in the nature of varices are comparatively rare, and these 

impressions also seem to show a shell without lam Bose surface ornamentation. They 

much resemble the form from the San Juan and 'rested Butte regions which I identified as S_pliriferi/na soliclirostris, but the median ib of the sinus is distinctly stronger, 

and the surface seems not to have been marked ith 'concentric lamellae. They are 

also similar to Sp. kentuckyensi 8, but are disting shed by being less sharply plicated, 

while the sinus is shallower and the median ri more strongly expressed, perhaps, 

pestris 

sharply plicated and having 

sinus. 

than in that common Coal, Measure species. W 

ferina octoplicata, 

White. From 'that 

which, as 

species " the impres 

a very distinct rib i 

identified by him, 

ite refers these specimens to 

ions differ considerably, being less 

believe to be the same 'as 

the middle of a shallower, broader 

Sp. camSpiriIt is much more likely at the delicate spin se ornamentation of Spi7Ver sp. b 

should not have been retain upon the casts or eceived upon the impressions, than 

a As identified by White at S to Fe, etc. 
292 CARBONIFEROUS FORMATIONS AND FAUN AS OF COLORADO. 

that the delicate but relatively stronger ornamentation of S_piriferina solidirostris 

should have been lost. As the impressions agree with the shells referred to 

Spirifer sp. b in other characters, I regard their specific identity, though not certain, as still rather probable. 

Locality and horizon.—Leadville district (stations 2372, 2373, 2375, 2377, 2878); 

Leadville limestone. Castle Rock quadrangle (station 2367); Millsap limestone. Pebbles of Millsap limestone (?) in the Red Beds conglomerate, Larimer County (station 

2364). 

SPIRIFER PECULIARIS Shumard? 

1855. Spirifer? peculiaris. Shumard, Geol. Rept. Missouri, p. 202, pl. C, figs. 7a, b. 

Cheming group: Chouteau Springs, Cooper County, Mo. 

1874. Spirifer (Martinia) peculiaris. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. 

Invert. Foss., p. 17. 

Subcarboniferous: Mountain Spring, Old Mormon road, Nevada. 

1875. Spirifer (Martinia) peculiaris. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, 

p. 90, pl. 5, figs. 7a, b. (Whole volume published in 1877. ) 

Subcarboniferous! Mountain Spring, Old Mormon road, Nevada. 

1895. Spirifera peculiaris. Keyes, Missouri Geol. Surv., vol. 5, p. 79. (Date of imprint 1894. ) 

Kinderhook limestone: Chouteau Springs, Missouri. 

1899. Reticularia (?) peculiaris. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 557, pl. 70, figs. 8a, 8b. 

Madison limestone: Yellowstone National Park. 

1901. Spirifer peculiaris? Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 165, pl. 14, figs. 6-9; p. 198, 

pl. 20, fig. 1. 

Kinderhook: Beds 4 and 7, Burlington, Iowa. 

This species was described by Shumard from the Chouteau limestone of Missouri. Later it was identified by White at Mountain Spring, Old Mormon road, 

Nevada. I recognized it in the Madison limestone .of the Yellowstone National Park 

region, and it also reappears in the fauna under discussion. Shumard evidently 

regarded his reference of this form to Spirifer as doubtful, and White placed it in 

the Martinia section of the genus. I referred it with a query to Reticularia, but in 

typical material from the Chouteau limestone the presence of neither septa nor dental 

lamellae is indicated in either valve, in which it differs widely from our Lower 

Carboniferous Reticulariae. It certainly differs considerably from the dominant 

Carboniferous types of 

suborbicularis 

doubt specifically identical with one another, that the forms from Nevada, Colorado, 

formis 

While all probably belong to the 

and Sp. suborbicularis, 

type. 

Spirifer, 

which constitute what Hall and Clarke designate the 

and seems to be most closely allied to 

subcardiformis section and are with little 

Sp. subcardiand Yellowstone Park are correctly referred to Sp. peculiaris I now believe to be 

doubtful. 

At all the localities in the West at which this form has been collected it seems 
DESCRIPTIONS OF SPECIES. 293 

to be comparatively rare, and the fossils which have thus far come into my hands 

are few in number and not in good condition. One important distinction resides in 

the fact that Sp. peculiaris is marked as to its surface by regular, closely arranged, 

concentric lamella, while the Western specimens appear to be quite smooth. They 

probably constitute an undescribed species, but it seems wiser to await more abundant 

material before making detailed comparisons or assigning a new name. So far as 

the available specimens, which are very variable, are characteristic, this form can 

scarcely belong to Sp. suborbicularis or to Sp. subcardiformis, and in general configuration, at least, it most closely resembles Sp. peculiaris. 

In the above remarks, wherever the Colorado material is involved, I have had in 

mind especially that from the Crested Butte region. From the San Juan region but 

two very imperfect examples have so far come to hand. One of these is so poor as 

to render its relation to Sp. peculiairis no more than a probability, while the other, 

though probably of the suborbicularis type, shows a distinct median rib in the ventral 

sinus, a character which I have yet observed neither in typical Sp. peculiaris nor in 

the material provisionally allowed to remain under the same name. 

Locality and horizon.--San Juan region (stations 2382, 2384?), Ouray limestone. 

Crested Butte district (station 2358); Leadville limestone. 

SYRINGOTHYRIS Winchell, 1863. 

SYRINGOTHYRIS CARTERI Hall. 

1857. Spirifer carteri. Hall, New York State Cab. Nat. Hist., 10th Rept., p. 170. 

Waverly sandstone: Licking County, Ohio. 

1860. Spirifer (Cyrtiar) hannibalensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 647. 

Lithographic limestone: Marion County, Mo. 

1863. Syringothyris typa. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 7. 

Base of Burlington limestone: Burlington, Iowa. 

1865. Syringothyris cuspidatus. Meek, Acad. Nat. Sci. Philadelphia, Proc., p. 275. 

1867. Syringothyris cuspidatus. Meek, Am. Jour. Sci., (2), vol. 43, p. 407. 

1870. Spirifera carteri. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 252. 

Waverly group: Sciotoville and Rockville, Ohio; near Shafers, Pa. 

1870. Syringothyris typa. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 252. 

Waverly group: Newark and Sciotoville, Ohio; near Shafers, Pa. 

1875. Spirifer carteri. Meek (partim), Pal. Ohio, vol. 2, p. 285 (not his figures—S. texta Hall). 

Waverly group: Ohio. 

1877. Spirifer cuspidatus? Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 87, pl. 3, figs. 11, lla. 

Carboniferous or Devonian limestone: White Pine Mountains, Treasure Hill, Nevada. 

1884. Syringothyris cuspidata. Walcott (not Martin), U. S. Geol. Surv., Mon., vol. 8, p. 219, pl. 3, 

fig. 11. 

Lower Carboniferous: Eureka district, Nevada; near Clendenin, Mont. . 

1888. Syringothyris cuspidatus. Herrick (partim), Sci. Lab. Denison Univ., Bull., vol. 3, p. 41, pl. 1, 

fig. 7; pl. 2, fig. 17 (not pl. 5, figs. 4-7—S. herricki). 

Waverly group: Licking County, Ohio. 
294 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. • 

1890. 	Syringothyris carteri. Schuchert, 9th Ann. Rept. New York State Geol., p. 30. 

Bedford shale: Bedford, Ohio. 

Waverly sandstone: Licking County, Ohio. 

Chouteau limestone: Marion and Pike counties, Mo. 

Kinderhook group: Burlington, Iowa. 

Burlington group: Burlington, Iowa. 

Lower Carboniferous: White Pine Mountains, Richmond Mountain, Eureka district, Nevada; 

near Clendenin,. Mont. 

1893. Syringothyris typa. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 8, 48, 50; fig. 40 on p. 48; 

pl. 26, figs. 6, 7, 10; pl. 27, figs. 1-3. (Advance distribution in fascicles.) 

Burlington limestone: Burlington, Iowa. 

1894. Syringothyris typa. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 30, figs. 1, 2. 

Burlington limestone: Burlington, Iowa. 

1895. Syringothyris carteri. Keyes, Missouri Geol. Surv., vol. 5, p. 87, pl. 40, fig. 10. (Date of imprint, 

1894.) 

Burlington limestone: Springfield, Mo. 

1895. Syringothyris hannibalensis. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pl. 25, figs. 33-35. 

Chouteau limestone: Pike County, Mo. 

1895. Syringothyris typa. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 8, 48, 50; pl. 26, figs. 6, 7, 

10; pl. 27, figs. 1-3. 

Burlington limestone: Burlington, Iowa. 

1899. Syringothyris carteri. Weller, Acad. Sci. St. Louis, Trans., vol. 9, p. 20, pl. 4, figs. 5, 6. 

Vermicular sandstone: Northview, Webster County, Mo. 

1899. Syringothyris carteri. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 558, pl. 71, figs. la-lc. 

Madison limestone: Yellowstone National Park. 

So far as the charaCters of each can be made out, the dorsal valve of this shell 

agrees with what may be regarded as typical specimens of S. carteri, but the ventral valve seems to be more erect than the corresponding one of that species. The 

same is true when comparison is made with the specimen from the White Pine 

mining region which was figured by Meek (1877, loc. cit.), but the latter is somewhat 

distorted by crushing. Other' specimens from the White Pine district show a similar 

erect habit. 

Locality and horizon.—Crested Butte district (station 2358); Leadville limestone. 

SPIRIFERINA d'Orbigny, 1847. 

SPIRIFERINA SOLIDIROSTRIS White? 

Pl. I, figs. 3, 4. 

1860. Spirifer solidirostris. White, Boston Soc. Nat. Hist., Jour., vol. 7, p. 232. 

Carboniferous: Burlington, Iowa. 

1865. Spiriferina solidirostris. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 120. 

Base of Burlington limestone: Burlington, Iowa; Hamburg, Ill. 

1870. Spiriferina solidirostris. Winchell, Am. Phil. Soc., Proc., vol. 11, p. 252. 

Waverly group: Newark, Sciotoville, and Rockville, Ohio. 
DESCRIPTIONS OF SPECIES. 295 

1888. Spiriferina solidirostris. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 47, pl. 1, fig. $ (?); 

pl. 2, figs. 9-11; pl. 5, fig. 13. 

Waverly group: Licking County, Ohio. 

1895. Spiriferina solidirostris. Herrick, Geol. Surv. Ohio, Rept., vol. 7, pl. 21, fig. 13. 

Burlington: Ohio, 

1899. Spiriferina solidirostris. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 71, fig. 10a. 

Madison limestone: Yellowstone National Park. 

1901. Spiriferina solidirostris. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 198, pl. 20, figs. 2-4. 

Kinderhook: Bed 7, Burlington, Iowa. 

This species is found in the San Juan and the Canyon areas and in each it is 

rather an abundant form. It is rather constant in the characters shown and can be 

briefly described as follows: 

Shell of medium size, transverse. The width of a large specimen is about 20 

mm. and the length 11 mm., but the average size is considerably less. The fold and 

sinus are rather narrow and deep but usually show a tendency toward division. 

Accordingly, the fold is centrally flattened or even slightly grooved, and the sinus 

shows a corresponding condition. The lateral plications are simple and strong. In 

large specimens six of these are found on each side of the sinus and five on the fold, 

but in smaller examples these numbers are diminished by one. The area of the 

ventral valve is high, but it is sometimes nearly flat, and at others more strongly 

incurved. The surface is marked by numerous regularly disposed concentric 

lamellw, which become stronger and more crowded near the margin. Their 

edges appear delicately fluted, a circumstance which can doubtless be interpreted as 

indicating that they bore spinous fimbriw. The punctation is rather coarse and 

very abundant. The ventral valve is provided with a strong median septum and also 

with strong dental lamellw. 

This forth is probably identical with part of the material from Yellowstone Park 

which I identified in 1896 as 8:29. solidirostris. The fossils then in hand were few and 

poor and I now suspect that more than a single species was involved. The specimen 

figured at that time has more numerous and more slender ribs than the Colorado 

type, but some of the other specimens approach it closely. 

Spiriferina solidirostris Q would much resemble Sp. s;ubelliptica at the same 

size in general configuration and in the character of its surface ornamentation, but 

McChesney's species does not show a faint median plication on fold and sinus. A 

common form in the Waverly group at Sciotoville, Ohio, which can probably be 

identified with Sp. depressa Herrick, also resembles the Colorado form in general 

appearance, but it is without a median plication, and the lamellose concentric striae 

are considerably coarser. Another related form is Sp. subtexta White, but the latter 

is too little known for comparisons to be of value. It seems to have a simple fold 

and sinus, which should distinguish it from the Colorado form, but it must be 
296 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

borne in mind that this character is often very obscure in the latter as well. A similar resemblance seems to exist also with Sp. elarksvillensis, but that. species, too, 

has never been figured and is little known. Spiriferina kentuckyensis approaches 

this Colorado form in many ways. It differs in being usually smaller and much 

more mucronate. The plications and intervening grooves are slightly sharper and 

the concentric lamellae a trifle finer. But the most marked and constant character 

is the extended and often mucronate hinge line. 

This form seems at first to be the same as that from the Leadville region 

described as Spirifer sp. b, but a closer examination removes any question of their 

identity. In their internal structure as well as in the details of their surface ornamentation they are quite distinct. 

Locality and horizon.—San Juan region (stations 2379, 2381, 2382, 2385); Ouray 

limestone. Canyon (station 2366); Millsap limestone. Pikes Peak quadrangle 

(station 2371); Millsap limestone. Castle Rock quadrangle (stations 2367, 2389); 

Millsap limestone. 

SEMINULA McCoy, 1844, emend. Hall and Clarke, 1893. 

SEMINULA CLAYTONI Hall and Whitfield. 

1877. Athyris claytoni. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 256, pl. 4, figs. 

15-17. 

Lower Carboniferous limestone (Waverly?) : Little Cottonwood, 800 feet east of Reed and 

Benson's mine, Wasatch Range, Utah. 

1897. Seminula claytoni. Schuchert, U. S. Geol. Surv., Bull. No. 87, p. 378. 

From the vicinity of Salida (loc. 2361) several specimens of Seminula have been 

collected. They seem to have been abundant, and, so far as their crushed condition 

admits the forming of a conclusion, can be referred to S. claytoni White. They 

appear to represent one of the large oval forms with little or no fold and sinus, and 

resemble also the species which I described from the Madison limestone as Seminula 

immatUra. S. claytoni is larger than S. immatura and with a less distinct sinus. 

In these particulars the Colorado material is nearer the former than the latter species. 

S. claytoni occurs associated with Sp. centronatus and probably belongs to the 

same fauna of which S. immatura is a member. I rather look to see the two species 

proved synonymous, but it seems better to await more conclusive evidence before 

abandoning the latter name. 

Locality and horizon.—Salida region (station 2361); Leadville limestone. 

SEMINULA SUBQUADRATA Hall ?. 


P1. I, fig. 5. 


1858. Athyris subquadrata. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 703, p1. 27, figs.2a-d; p. 708, fig. 118. 


Kaskaskia limestone: Chester, Ill.; Crittenden County, Ky. 
DESCRIPTIONS OF SPECIES. 297 

1877. Athyris subquadrata? Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 271, pl. 

5, figs. 19, 20. 

Wasatch limestone: Snowstorm Hill, near Dry Canyon, Oquirrh Mountains, Utah. 

1886. Athyris subquadrata. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 453, p. 440, 

fig. 2. 

Mill Creek limestone, Upper Coal Measures: Wilkesbarre, Pa. 

1886. Athyris subquadrata. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p. 269, fig. 2. 

Mill Creek limestone, Upper Coal Measures: Wilkesbarre, Pa. 

1891. Athyris subquadrata. Whitfield, New York Acad. Nat. Sci., Ann., vol. 5, p. 585, pl. 14, figs. 1-3. 

Maxville limestone: Newtonville and Maxville, Ohio. • 

1893. Seminula subquadrata. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 95, pl. 47, figs. 7-9, 15, 

16; pl. 84, figs. 30, 31. (Advance distribution in fascicles.) 


Chester limestone: Crittenden County, Ky. 


St. Louis limestone: Spergen Hill, Ind.; Pella, Iowa. 


Kaskaskia limestone: Chester, Ill. 


1894. 	Seminula subquadrata. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 35, figs. 13, 15. 


Chester limestone: Crittenden County, Ky. 


St. Louis limestone: Pella, Iowa. 


1895. Athyris subquadrata. Keyes, Missouri Geol. Surv., vol. 5, p. 92. (Date of imprint, 1894.) 

Kaskaskia limestone: St. Mary, Mo. 

1895. Seminula subquadrata. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 95, pl. 47, figs. 7-9, 15, 

16; p1. 84, figs. 30, 31. 


Kaskaskia limestone: Chester, Ill.; Crittenden County, Ky. 


St. Louis limestone: Pella, Iowa; Spergen Hill, Ind. 


1895. 	Athyris subquadrata. Whitfield, Geol.•Surv. Ohio, Rept., vol. 7, p. 472, pl. 10, figs. 1-3. 

Maxville limestone: Newtonville and Maxville, Ohio. 

1897. Athyris subquadrata. Weller, New York Acad. Sci., Trans., vol. 16, p. 258, p1. 18, fig. 16. 

(Date of volume, 1898.) 

Batesville sandstone: Batesville, Ark. 

Near the top of the Blue limestone, at several localities in the Leadville region, 

a species of Seminula occurs in some abundance (especially at station 2375). None of 

the fossils of this formation are well preserved or in a condition favorable for study, 

and the seminulas have suffered equally with the rest. Suspending for the moment 

the discussion of the generic position of this form, it will be desirable to comment 

upon its specific characters and its relation to the species to which I have referred it. 

My specimens show considerable variety in size, the largest observed having a 

length of probably 20 mm., the others ranging to half that or less. These inequalities 

in size evidently correspond to differences in age. The shape is subquadrate to 

subcircular, the width being about the same as the length, or usually a trifle greater. 

The upper portion of the contour is made by approximate right lines, extending 

• 	 perhaps halfway down the figure. The inferior outline is either regularly curved or 

subrectilinear, depending somewhat on the degree of development of the fold and sinus. 

The feature last mentioned is faint, but can usually be ascertained. It is apt to be 
298 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

narrow and shallow, a linear median depression. None of the shell sexamined attain 

stages of that species. Comparison has been made with specimens characteristic of 

either the size or the development of fold and sinus of mature examples of 

quadrata, 

Serninula subquadrata 

but they follow, with agreement singularly exact, the young and adolescent 

from Pope County and from Chester, Ill. , and the closest 

S. subagreement was found. 

This form somewhat resembles the rounder specimens of Cranwna subelliptica 

var. hardingensis, and suggests a doubt of the generic reference, which probably 

would not otherwise be questioned. No specimen perfect enough to retain such 

characters which is at the same time certainly a dorsal valve has been observed, but 

this valve seems to have had no internal structures of a septal nature. The ventral 

valve shows two rather weak dental plates. 

farther apart, and the umbonal portion has not, seemingly, the peculiar and characensis 

discernible fold and sinus. In the ventral valve the plates are less strong as a rule and 

Compared with less elongate specimens of 

this shell is smaller and more quadrate, and it possesses a faint though distinctly 

Cranwn,a subellipticct var. hardingteristic conformation of the terebratuloids. 

At Perry Park (station 2367) there occurs in considerable abundance a small 

species of Seminula that I believe can be referred only to the species to which the 

material from Leadville belongs. None of the examples from Perry Park are as 

large as the larger ones from Leadville, but with such as are of their own size they 

agree completely. This identification is in a measure confirmed by the circumstance 

that these shells at both localities occur associated with a peculiar and, probably new 

species of Spirifer. These specimens might be placed with Seminula humilis or with 

S. wasatchensis, but probably with less precision. The ventral beak of S. humilis 

is larger and more tumid, and where the thick shell is removed the internal cast 

shows the presence of a deep rostral cavity, imparting to these molds a different 

shape from those from Perry Park, for the specimens from that locality occur in this 

condition. 

Soninula itamilis and S. wasatchensis, of which mention is made above, are 

closely similar, and were it not that the latter is founded upon a solitary specimen 

whose horizon is still in doubt and may be very different from that of S. humilis I 

would not hesitate to throw them together. 

Although Seminula subquadrata was described from rocks of Genevieve age, and 

although it was especially abundant during that period, the identification of it in the 

upper beds of the Leadville limestone can not be considered as entirely diagnostic of 

their geologic age, since a very similar shell occurs in the Cuyahoga shale of Ohio, 

which probably belongs to the Osage period. 

Locality and horizon.—Leadville district (stations 2375, 2377, 2378); Leadville 

limestone. Castle Rock, quadrangle (station 2367 ?); Millsap limestone. 
DESCRIP IONS OF SPECIES. 299 

SEMINU A HUMILIS Girty?. 

1899. Seminu/a humilis. Girty, U. S. Geol. .urv., Mon., vol. 32, pt. 2, p. 565, pl. 71, figs. 6a-6c. 

Madison limestone: Yellowstone Nati nal Park. 

ing to the genus 

diameter of 11 mm., which probabl 

tilita

fold nor sinus is developed. This 

The impression upon which 

a in the fauna from Larimer 

Seminula. The be 

kite based his determination of 

ounty is a small, nearly circular shell, having a 

k is small, depressed, and incurved4,nd neither 

represents a dorsal valve of a specimen belongpression agrees very closely with d rsal valves 

Se#tinula subof the little shell which I described nder the name of S. humilis. At t e same time 

it can not be distinguished from do sal valves of the same dimensions f the type 

of the numerous varieties of 

quadrata. 

dorsal valve is less noticeable than 

which, in the Perry Park and Lea 

proportionally obscure in young sp 

While it shows no evid 

Semin tict subtilita 

the corresponding one of the ventral, and it is 

ville regions, I have referred to 

cimens; and doubtless immature shells of some 

nce of a fold, in them also that feature of the 

assume the same form, biut certainly 

Sern,inula subit is very different from the commo mature type of S. subtilita. 

Locality and h,orizon.—Pebble of Millsap limestone (?) in the Red Beds conglomerate, Larimer County (station 2364). 

EMINULA Sp. 

In the San Juan region a sing e tiny Seminula has been collected., Its entire 

length is but 6 mm., and because o its probable immaturity and its solitary occurrence it has scarcely seemed wort y of more than mention, without an attempt to 

refer it to any described species. 

Locality and horizon.—San Ju n region (station '2381); Ouray limestone. 

CRANAN Hall and Clarke, 1893. 

CRAN.ZENA SUBELL TICA var. HARDINGENSIS B. var. 

P1. I, figs. 8-10. 

As Hall and Clarke figure but o not describe Cranwna subelliptica, the following 

description, based upon a series of upward of 50 specimens from the tTpe locality, 

Sciotoville, Ohio, may not be with ut value: 

Shell large, ovate. Outline egular. Curvature evenly rotund, without fold 

or sinus. Shell substance thick, undantly punctate. Surface marked by numerous, more or less distinct growth li es. 

Cranwna subelliptica is diffic It to describe effectually because it is largely 

lacking in distinctive characters. While in shape it is always longer than wide, 

a U. S. Geol. Geo . Sury Terr., Bull., vol 5, 1879, p. 215. 
300 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the specimen figured by Hall and Clarke has these dimensions unusually unequal; 

nor are the sides, as a rule, straightened, as in the type specimen. Older examples 

are proportionately more elongate than young ones. The ventral valve does not 

project as far beyond the dorsal as in many species of Dielama, and the beak is not 

attenuate nor strongly incurved. The recurved pedicle sheath is often well 

developed. 

The common shape of this species is more like that of Cryptonella eudora. 

Indeed, as tile fossils from Licking County, Ohio, which have been identified with 

the latter, come from almost the same horizon in the Waverly as the Sciotoville beds, 

I feel some confidence that they belong to this species. Should this prove to be the 

case, it would be well to restrict the name eudora to the Devonian species and place 

Cryptonella eudora (pars) in the synonymy of Cranwna subelliptica. 

Cfianwna subelliptica resembles Cr. iowensis in the closest manner, and I am not 

sure that, if similarly preserved, it would be easy to distinguish them. Cl iowensis 

is apt to be more highly arched, with the beaks of both valves more attenuate and 

produced. The surface is smoother and less interrupted by appreciable lines of 

growth. The blunt, clumsy form of the beaks in Cr. subelliptica is rather noticeable 

and characteristic. 

In both Cr. subelliptica and Cr. iowensis the hinge plate is large and similarly 

formed. It connects posteriorly with the end of the valve and is supported by the 

strong socket walls with which it is united. In Cr. subelliptica at least its posterior 

extremity is adnate to the floor of the valve for a short distance or even seems to be 

mounted upon a short, low septum. It is deeply concave, and often with an 

incomplete heart-shaped section. Usually it is divided by two radiating carinw into 

three portions, only the central one having a homologue in Dielasma. The shape is 

pentagonal, the two anterior angles being formed by the two carinw just mentioned, 

which run out at the margin and project in the form of crura. The hinge plate 

converges with the bottom of the valve posteriorly, the anterior extremity being 

often a considerable distance away. The hinge plate is not divided in either Cr. 

iowensis or Cr. subelliptica, as illustrated by Hall and Clarke's figures.a I have not 

been able to ascertain*the characters of the loop in this species with satisfaction. It 

seems to be short, with short diverging crura and short ascending 

If we may rely upon Cr. iowensis and Or. subelliptica as criteria, it seems to be 

rather characteristic of this genus that the brachial valve is marked by rather strong 

muscular impressions situated near together and anterior to the end of the hinge 

plate. On internal casts three grooves, diverging anteriorly, are usually clearly 

visible, inclosing the scars between their anterior ends. The central groove evidently represents an incipient median septum, which in Cr. subelliptica at least is 

a Pal. New York, vol. 8, pt. 2, 1894, p. 297, fig. 215. 
DESCRIPTIONS OF SPECIES. 301 

developed posteriorly and supports the hinge plate. Its anterior extremity divides 

the median pair of muscles. The inner surface of the hinge plate of Dielasma is 

' often marked by transverse flutings, and this structure has, therefore, naturally 

been interpreted as a surface of muscular attachment, beneath which it has sometimes been considered the viscera were lodged. The analogy between Cranwna 

and Dielasma is so strong throughout that the conclusion seems warranted that a 

pair of muscles, leaving scars too faint to be often preserved, was attached to the 

bottom of the shell anterior to the hinge plate in Dielasma, just as in CramTna, 

and that the hinge plate in Cranwna, which is also fluted, bore other muscles, as 

is supposed to be the case in Dielasma. 

Hall and Clarkea correctly describe the hinge plate of these dielasmatoid forms, 

but their figures are misleading in that the most enlarged and elaborate ones fail 

to show this structure at all, while in the smaller ones it is inconspicuous and 

somewhat slurred. over. For example, in the figure of Eunella sullivanti, the type 

species of Eunella (fig. 23 of pl. 80), the crura spring almost immediately from the 

posterior wall of the valve, and one would infer that the hinge plate was either 

absent or an inconsiderable structure. The same feature is shown in Eunella 

lincklmni (fig. 30 of same plate), where nothing resembling the cardinal plate 

seems to be present. That a similar condition obtained in Cranwna one would be 

led to infer from the figure of the type species, Cr. romingeri (fig. 16 on same 

plate). 

I have referred to Cranwna, Cranwina subelliptica, which Hall and Clarke 

described as a Cryptonella, because it seems to have the characteristic brachidium 

of Cranena and because it seems to be so closely allied to Cranwna iowensis. 

It resembles the latter not only in the general physiognomy of the shell, but in 

the structure of the hinge plate and the shape, strength, and arrangement of the 

muscle scars of the dorsal valve. In fact, there seems to be the closest agreement throughout between these two forms. For my own part, I incline to lay 

greater stress upon the structure of the hinge plate than upon minor crural characters and to ran Cranwna with Eunella as a subgenus of Oryptonella, rather 

than allow it to o cupy that position with regard to Dielasma. 

The specimens from Colorado, while often abundant, are so imperfect as to 

preclude a satisfactory determination. The generic characters, so far as I have 

elliptica. 

been able to ascertain them, agree with those of 

I feel cdnsiderable assurance that the shell is not a 

Cranwna iowensis 

Dielasma. 

and Cr. subFor all 

Some examples halve the same broadly oval form which characterizes that species, 

nella, Cranwna, ca' Eunella. 

I am able to determine, however, it might be a representative of either 

a Pal. New York, vol. 8, pt. 2, 1894, p. 297. 

In specific character it approaches Cr. subelliptica. 

Crypto­
302 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

but others are more elongate than even the type specimen of Cr. subelliptica, 

which, as has been said, is somewhat unusual in that regard. For the present, 

therefore, I refer the Colorado species as a -variety of Cranwna ,subelliptica, though 

better preserved and more perfect specimens may show that it should be removed 

to another species or even another genus. However, its generic affinities can be 

limited to three closely allied subgeneric groups, a circumstance which, with its 

specific affinities, does not deprive it of stratigraphic significance. In fact, in 

connection with the associated species, I attach some importance to its presence, as 

it indicates an age certainly not so late as the Coal Measures and probably earlier 

than the Genevieve period. Its associated fauna can scarcely be Devonian, 

and on the whole the evidence of this species points to the earlier half of the 

Mississippian era. 

Locality and horizon.—Canyon (stations 2366, 2370); Millsap limestone. Pikes 

Peak quadrangle (stations 2365, 2368, 2371); Millsap limestone. Castle Rock quadrangle (stations 2387, 2389); Millsap limestone. 

EUMETRIA Hall, 1863. 

EimIETRIA WOOSTERI White. 

Pl. I, figs. 11, 11a. 

1879. Retzia woosteri. White, U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, p. 215. (Some copies 

dated 1880.) 

Carboniferous: 18 miles north of Greeley, Colo. 

1880. Retzia woosteri. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 134, pl. 34, figs. 8a, b. 

Coal Measures: 32 miles west and 18 miles north of Greeley, Colo. 

1883. Retzia woosteri. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 134, pl. 34, figs. 8a, b. 

Coal Measures: 32 miles west and 18 miles north of Greeley, Colo. 

1898. Eumetria woosteri. Weller, U. S. Geol. Surv., Bull. No. 153, p. 283. 

Founded upon an impression taken from a mould in a bowlder in a conglomerate 

in Larimer County, some 50 miles from Greeley, Colo., it is unfortunate that this 

species was ever the recipient of a distinctive name. The type and only authentic 

specimen occurs with a fauna which White referred to the Coal Measures, but which 

I feel satisfied is of MiSsissippian age, and Eu. woosteri itself is of a distinctly Mississippian type. Nothing comparable to it known from the Upper Carboniferous, 

while it is so similar to Eu. marcyi and Eu. altirostris that it is almost certainly a 

synonym of one or other of these species. Weller a states that Eu. altiro8tris is 

distinguished from Eu. marcyi by having a more acute and more erect beak, coarser 

plications, and the slight sinus with its stronger median furrow. These characters, 

• a Acad. Sci. St. Louis, Trans., vol. 10,1900, p. 75.. 
DESCRIPTIONS OF SPECIES. 303 

if constant, would "tisfactorily differentiate the Kinderhook from the Genevieve 

species, but at the same time Eu. altirostris is so rare a form that the limits of its 

variation can scare* be said to be known. 

Eu. woosteri cloely resembles Eu. marcyi, but it is in, even more close agreement 

with Ea. altirostris. Its general shape is more elongate than in Shumard's rotund 

species; the ventral beak is more slender, though it can not be described as more 

erect; the ribs are somewhat coarser than is common in Eu. marcyi, but they are not 

without parallel in fssils referable to that species. There is present a sinus, a character which. I have as yet not observed in the Genevieve form. 

Comparing it with Eu. altirostris as represented by Weller's figures and discription, Eu. woosteri is found to agree very closely in size, though the shape is somewhat more broadly ovate. The beak seems to be almost equally acute, but is prob= 

ably more strongly incurved. The ribs are a little finer and slightly greater in number. There is a sinus but no strong median furrow. It seems highly probable that 

Eu. woosteri is a synonym of Eu. altirostris, but I retain both names awaiting further 

evidence. 

species. 

Park, which I have identified with 

tedia) mormoni. 

The form from the San Juan region of Colorado and from the Yellowstone National 

White compare this species with 

There can be no doubt that 

Eu. verneuitiana, 

Retzia utak, 

Eu. woosteri 

evidently a slip for 

differs from 

is distinct from the latter 

Eu. woosteri 

Retzia (Husin 

being smaller, with finer stri, and, so far as is known, in lacking a sinus. 

In the Leadville district (at station 2375) was found a fossil which seems to be a. 

retzioid brachiopod. It is an imperfect external cast of one valve, in which only the 

impressions of rigid striae are presented to view, the finer ornamentation, if any 

existed, having beet' lost. It 'is larger and more numerously striated than Hustedia 

mormoni, and seem to be rather of the Eumetria type. It appears to present the 

general characters of Eu. woosteri, and though slightly smaller than the type specimen, and with ribs somewhat coarser and more broadly rounded, it appears, like it, 

to have had a sinus, faint indications of which are still retained. 

On the whole, i is probable that this shell is an Eumetria and closely related to 

Eumetria woosteri, to which I have provisionally referred it, but its relations with 

Eu. marcyi and Eu. altirostris are also close. 

Locality and h,orizon.—Leadville district (station 2375); Leadville limestone. 

Pebbles of Milisap ljmestone in the Red Beds conglomerate, Larimer County (station 

2364). 

EUMETRIA MARCYI Shumard? 

1852. Terebratula serpent .na. Owen (not de Koninck), Geol. Surv. Wisconsin, Iowa, and Minnesota, 

pl. 3A, fig. 13. (See specimens in U. S. Nat. Mus. Cat. Invert. Foss., 17955.) 

Carboniferous: S unk River, Iowa. 
304 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1854. Terebratula marcyi. Shunaard, Marcy's Expl. Red River of Louisiana, p. 177, pl. 1, figs. 4a, b. 

Carboniferous. Washington and Crawford counties, Ark. 

1858. Retzia verneuilana. Hall, Albany Inst., Trans., vol. 4, p. 9. 

St. Louis limestone: Bloomington and Spergen Hill, Ind. 

1858. Retzia verneuliana. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 657, pl. 23, figs. la-d. 

Warsaw limestone: Spergen Hill and Bloomington, Ind. 

1858. Retzia vera. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 704, pl. 27, figs. 3a, b. 

Kaskaskia limestone: Chester, Ill. 

1858. Retzia vera var. costata. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 704, pl. 27, figs. 3a, b. 

Kaskaskia limestone: Chester, Ill. 

1863. Eumetria vera,. Hall, New York State Cab. Nat. Hist., 16th Rept., p. 55, pl., figs. 1-3, and p. 59. 

1863. Eumetria verneuili. Hall, New York State 'Cab. Nat. Hist., 16th Rept., p. 55, fig. 2. 

1882. Eumetria verneuilana. Whitfield, Am. Mus. Nat. Hist., Bull., vol. 1, p. 50, pl. 6, figs. 28-30. 

St. Louis group: Spergen Hill, Paynters Hill, and Bloomington, Ind.; Alton, Ill. 

1883. Eumetria verneuiliana. Hall, Geol. Surv. Indiana, 12th Rept., p. 335, p. 29, figs. 28-30. 

St. Louis group: Spergen Hill, Lanesville, and Bloomington, Ind. 

1884. Retzia radialis. Walcott (non Phillips) (pars), U. S. Geol. Surv., Mon., vol. 8, p. 220, pl. 7, 

figs. 5-5e. (?) 

Upper Devonian: Eureka district, Nevada. 

Lower Carboniferous: Eureka district, Nevada; Little Belt Mountains, near Clendenin, Mont. 

1889. Retzia marcyi. Miller, North Amer. Geol. and Pal., p. 366. 

Kaskaskia group. 

1893. Eumetria vera. Hall and Clarke, Pal. New York, vol. 8, lat. 2, p. 117, pl.• 51, figs. 36, 37. 

(Advance distribution in fascicles.) 

Chester group: Crittenden County, Ky. 

1893. Eumetria verneuiliana. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 117, pl. 51, figs. 13-26, 34, 

35; pl. 83, figs. 26, 27. (Advance distribution in fascicles. ) 

St. Louis group: Spergen Hill, Ind.; Greene County, Mo. 

1894. Eumetria verneuiliana. Hall and Clarke, Int. Study of Brach., pt 2, pl. 37, figs. 1-4, 6, 10. 

St. Louis group: Spergen. Hill, Ind. 

1894. Eumetria vera var. costata. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 37, figs. 5, 11. 

Chester limestone: Chester, Ill.; Crittenden County, Ky. 

1894. Eumetria vera. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 37, figs. 8, 12. 

Chester limestone: Crittenden County, Ky. 

1895. Retzia vera. Keyes, Missouri Geol. Surv., vol. 5, p. 95. (Date of imprint, 1894.) 

Kaskaskia limestone: St. Marys, Mo. 

1895. Retzia verneuiliana. Keyes, Missouri Geol. Surv., vol. 5, p. 95. (Date of imprint, 1894.) 

St Louis limestone: St. Louis, Mo. 

1895. Eumetria vera var. costata. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pl. 51, figs. 27-33. 

Chester limestone: Crittenden County, Ky.; Chester, Ill. 

1895. Eumetria vera. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 117, pl. 51, figs. 36, 37. 

Chester group: Crittenden County, Ky. 

1895. Eumetria verneuiliana. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 117, pl. 51, figs. 13-26. 

34, 35; pl. 83, figs. 26, 27. 

St. Louis group: Spergen Hill, Indiana; Greene County, Mo. 
DESCRIPTIONS OF SP CIES. 305 

1897. Eumetria verneuila a. Weller, New York Acad. Sci., Trans., vol. 16, p. 259. (Date of volume 

1898.) 

Batesville sandsto e: Batesville, Ark. 

1899. Eumetria verneuilia a. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 560, pl. 68, figs. 12a-12b. 

Madison limestone: Yellowstone National Park. 

Just as in the h gher beds of the Mississippi n series in the Mississippi Valley 

two species of Eum tria were early recognized, o e a large form with coarse strive, 

the other smaller a d with finer ornamentation, o in the material from Colorado a 

similar condition is ound to exist, and although i has been general of late to unite 

Eu. vera and Eu. v n,euiliana into one species, I feel indisposed to follow a similar 

course in treating th • specimens under discussion. 

species which includ s the names 

tria woosteri. 

Eumetria mareyi. 

The coarsely strated form from Colorado has been accordingly referred to 

The nely striated one I have distinguished from it under the name 

n so doing and in adopting here the common synonymy of that 

Eumetria verneuiliana (which my specimens espeEumecially resemble) an. Eumetria very (to which Ea. woosteri is closely; allied), I am 

aware that my cours• is not altogether consistent, but I am hopeful at least that the 

distinctions which o iginally led to the proposal of these specific names wilj. be found 

significant of differ nces of geologic age or geographic occurrence. I have not at 

hand, however, the ossi]s and stratigraphic data upon which to establish an opinion 

or rest a proof of th validity and relationship of Eumetria altirostris, Eumetria vera, 

Eumetria verneuilia a, Eumetria mareyi, and Eumetria woosteri, and their synonymy, 

and hardly venture o disturb the status quo by an invalid attempt at betterment. 

The smaller variety has so far been found in Colorado only in the San Juan 

region. It is a comparatively rare form, and the specimens collected are so fragmentary that only g neral comparisons are possible. 

The largest spe r imen has a length, probably, of not more than 12 mm., and has 

at the margin 8 or 9 strite in the space of 5 mm. These fossils, as far as I am, able 

to judge, agree ver closely with examples of the same size from Spergen Hill, 

Indiana, representi g Ett. verneuiliana, although a larger series of more perfect 

specimens may sho that the. Colorado form should not be referred to Hail's species. 

As the fauna ith which this form occurs in Colorado is with little doubt of 

Osag age, the ran e of Eu. venteuiliana is somewhat increased in a downward 

direc ion by this id ntifieation. Yet since at least one representative of the genus 

(Eu. ltirostris) is k own in the Kinderhook, it is much more a matter for surprise 

that he line of des ent should have been interrupted by the apparent absence of 

Eum trig from the Osage of the Mississippi Valley, than that it should have come 

to li ht in the Osag faunas of the Rocky Mountain region. 

his seems to b the form which in the Madison limestone of Yellowstone Park 

I cited under the sa e specific name, Eumetria verneuiliana. It differs considerably 

14364—No. 1 03 20 
306 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

from the Kinderhook species, Eu. a/tirostris, being smaller, more finely striated, 

and apparently without a sinus or strong median furrow therein. 

Locality and horizon.—San Juan region (stations 2381, 2382); Ouray limestone. 

CAMAROTCECHIA Hall and Clarke, 1893. 

CAMAROTCECHIA METALLICA White. 

1874. Rhynchonella metallica. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. Invert. 

Foss., p. 20. 

Carboniferous (Coal Measures): Old Potosi mine, Lincoln County, Nev. 

1875. Rhynchonella metallica. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 129, p1.10, 

figs. 10a-d. (Whole volume published in 1877. ) 

Carboniferous: Old Potosi mine, Lincoln County, Nev. 

1877. Rhynchonella pustulosa? Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 257, 

pl. 4, figs. 12-14. 

Waverly group: Logan Canyon, Wasatch Range, Utah. 

1899. Camarotcechia metallica. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 540, pl. 69, figs. 3a-3e. 

Madison limestone: Yellowstone National Park. 

In the San Juan region (at station 2382) occurs a form which, though it is represented by scanty and rather imperfect material, is referred with some confidence to 

Camarotcechia metallica. At all events, with but little doubt it is the same form which 

I identified with that species in the Madison limestone of Yellowstone Park. I 

believe, too, that the type specimen of C. metallica is not of Upper Carboniferous 

age, as stated in the original description, but belongs really to the Madison fauna. 

Locality and horizon.—San Juan region (station 2382); Ouray limestone. 

PELECYPODA. 

CRENIPECTEN Hall, 1883. 

CRENIPECTEN HALLANUS Walcott. 

1884. 	Crenipecten hallanus. Walcott, U. S. Geol. Surv.. Mon., vol. 8, p. 231, pl. 8, figs 7-7c. 

Lower Carboniferous: Eureka district, Nevada. 

At, locality 2382 in the San Juan region were found two specimens, imperfect 

internal and external casts, of a rather large pectinoid shell which probably belongs 

to the species Crenipecten, hallanus Walcott. The striae are rather coarse, much 

more so, for instance, than in the related Cr. winchelli. They are somewhat irregularly alternating, and are crossed by numerous delicate, somewhat flexuous, imbricating lamellose 

Cr. hallanus was described from strata in the Eureka district, Nevada, which 

I believe to be of Osage age, and so can not be far from the horizon at which the 

material from Colorado was obtained. 

Locality and horizon,.---San Juan region (station 2382); Ouray limestone. 
DESCRIPTIONS OF SPECIES. 307 

STREBLOPTERIA McCoy, 1851. 

STREBLOPTERIA MEDIA. 

Pl. I, fig. 13. 

1888. Streblopteria media. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 56, pl. 3, figs. 4, 8, 9; 

pl. 1, figs. 13, 19; pl. 7, figs. 2, 6. 

Waverly group: Licking County, Ohio. 

1895. Streblopteria media. Herrick, Geol. Surv. Ohio, Rept., vol. 7, pl. 24, figs. 16, 17. 

Cuyahoga shale: Moots Run, Ohio. 

From the Milisap limestone of Perry Park was obtained a single specimen of a 

pectinoid shell which so closely resembles Herrick's description and figures of St. 

media that the identification with that species is made with some confidence. The 

shape, which is well shown by the illustration, agrees very closely with the right 

valve figured by Herrick as fig. 8 of pl. 3. The chief points of difference which I 

have been able to detect are not important. Possibly the posterior wing of my specimen is a trifle larger, and the outline under the anterior wing does not project as it 

is seen to do in Herrick's figure, but more nearly approaches a straight line. The 

surface appears to be almost smooth, being interrupted only by obscure concentric 

lines and corrugations. The anterior wing, however, has a few coarse, indistinct, 

radiating striae. 

Locality and horizon.—Castle Rock quadrangle (station 2389); Milisap limestone. 

MYALINA de Koninek, 1844. 

MYALINA ARKANSASANA Weller ?. 

1897. Myalina arkansana. Weller, New York Acad. Sci., Trans., vol. 16, p. 262, p1. 19, figs. 16, 17. 

(Date of volume, 1898. ) 

Batesville sandstone: Batesville, Ark. 

This species has been identified in the San Juan, Canyon, and Leadville districts, 

in Colorado, and a form believed to be the same occurs in the limestones of St. 

Louis age at Pella, Marion County, Iowa. The Colorado material upon which the 

following brief description is based is in every case preserved in a cherty matrix; 

it is often obscure and unfavorable for study. 

The shape is modioliform. The axis is oblique, and there is a distinct anterior 

lobe. The posterior outline is entire and subrectilinear. The anterior extremity is 

rounded; the posterior-superior angle obtuse and not projecting in an alate or 

mucronate extension. The surface appears for the most part nearly smooth, though 

obscure, ill-defined, concentric markings can be made out. Toward the anterior end, 

however, these gradually become stronger and develop into sharp, regularly spaced 

ridges. 
308 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The specimens from the San Juan region, though abundant, are indistinct. 

They appear to belong to the same species as those from Leadville and Canyon. 

Certain differences in their occurrence and lithology have led me to suspect that 

M arkansasana occupies a horizon different and somewhat higher than that at 

which the majority of Mississippian, species were found in this (San Juan) area. It 

need not necessarily, however, represent more than a different facies of the same 

fauna. 

Although the Leadville material is very impel feet, its characters lend themselves 

to a similar identification. This species appears in the faunal list of the Leadville 

monograph as Pleuroph,orus oblongus.a With this identification I can in no wise 

agree. The latter shell has a subquadrate, this a subtriangular, shape. The one is 

abruptly truncated behind, while in this species the posterior slope is strongly 

inclined to the cardinal line. The surface, too, is marked by rather prominent and 

regularly disposed lamellae of growth, while in Pl. oblongvs the striae seem to be 

finer and more crowded. The preservation of the types of Pl. oblongus, however, 

is not such as to faithfully portray the surface characters of that species. 

I was at one time disposed to refer my Colorado material to Modiola? nevadensis 

Walcott, but it can be distinguished from that species by the greater prominence of 

its umbonal ridge and by the presence of a faint though distinct sinus just in front 

of the latter in the anterior third of the shell. The shape of the two forms, however, 

is closely similar. . The same characters will serve to distinguish my specimens from 

ilboldola? subelliptica, which so closely resembles X. p nevadensis that the possibility 

is entertained that they will subsequently prove to be identical. 

arkansasana very closely resembles certain shells from the Pottsville series 

and Lower Coal Measures of the Appalachian region which I have been accustomed 

to refer to Naiaelites elongatus Dawson. The latter can sometimes be distinguished 

by having the posterior cardinal angle more nearly quadrate and by having the surface marked by finer, sharper striae, but these characters may not hold good in every 

case. The general resemblance is certainly very marked. 

The fossils from Pella mentioned above can probably be safely identified with 

M. arkansasana, and afford a satisfactory basis for comparison. From these and 

from Weller's figures the Colorado form differs in having the axis slightly• less 

oblique and the anterior lobe larger and better defined, producing a gentle emargination in front of the umbonal ridge. These differences are slight in degree, and I am 

not sure that the two forms should be separated by more than a varietal distinction, 

if so much. 

The characters which Weller points out as distinguishing his species from 

yalina swallowi hold good when the latter is compared with the specimens from 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 66. 
DESCRIPTIONS OF SPECIES. 309 

Colorado which I have identified with arkansasana, with this exception—that the 

sinus above referred to does produce a slight emargination, giving the- inferior 

border a somewhat sinuate outline, which is, however, much less strongly marked 

than in it swallowi. 

While I have identified these Colorado shells with a certain degree of confidence 

with a form occurring in the Genevieve division of the Missi ippian Carboniferous, 

the evidence thus afforded for correlation should not be ove estimated. Modioloid 

and aviculoid shells of this general type are common throu hout upper Devonian 

and Carboniferous time and are distinguished for their varia ility. Herrick figures 

several closely similar shells from the Waverly group of Ohi . identified as Myalina 

inichiganensis (pl. 4, fig. 6) and Jiodiola waverlyensis (pl. fig. 10),a and others, 

described or undescribed, doubtless occur.b The evidence of this species, therefore, 

must be accepted with caution. 

Locality and horizon.—San Juan region (stations 238 , 2385, 2387); Ouray 

limestone. Leadville district (stations 2372, 2377); Leadvi le limestone. Canyon 

(station 2366); Millsap limestone. Pikes Peak quadrangle (station 2371); Millsap, 

limestone. Castle Rock quadrangle (station 2367); Millsap li estone. 

MYALINA KEOKUK Worthen. 

Pl. I, fig. 12. 

1875. Myalina keokuk. Worthen, Geol. Surv. Illinois, Rept., vol. 6, p. 52 , p1. 30, fig. 5. 

Keokuk limestone: Keokuk, Iowa; Warsaw, Nauvoo, and Hamilto , Ill. 

1895. Myalina keokuk. Keyes, Missouri Geol. Surv., vol. 5, p. 117. (Dat of imprint, 1894.) 

Keokuk limestone: Bonaparte, Iowa; St. Francisville, Mo. 

My material consists of a single specimen from the S. n Juan region (station 

2382). It has something the shape of a parallelogram, havi g the anterolateral and 

posterolateral margins nearly straight and parallel, and th superior margin, also 

rectilinear, cutting them at an acute angle. The inferior m rgin is. rounded. The 

axis is strongly inclined to the cardinal line. The anterolat ral margin is recurved 

so that it is concealed beneath the shell when the latter is vie ed from above. The, 

umbonal portion, though enlarging below, is thin, much elev ted, and projecting. 

This species resembles X. congeneris, M. sanetiludovi and M. keokuk, but 

especially the latter, by reason of its elevated and proj cting umbo. In size, 

however, it is in accord rather with jlf. sanctiludovici, and a the three species mentioned above are very similar to one another, I am not alto ether satisfied that my 

identification is the best one. 

Locality and horizon.—San Juan region (station 2382); Ou y limestone. 

a Sci. Lab. Denison Univ., Bull., vol. 3, 1888. 

b A distinct but evidently related species has recently been described by Weller un er the name of Lithophaga minute: 

(Acad. Sci. St. Louis, Trans., vol. 11, No. 9, p. 168, pl. 15, fig. 19). 
310 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

CONOCARDIUM Bronn, 1835. 

CONOCARDIUM sp. 

One specimen of Conocardium has come to hand, but it is too poor for identifimum, 

cation. It is one of the forms with an elongated posterior portion like 

only in the Leadville region. 

Locality and horizon.—Leadville 

but it is fully three or four times larger than that species. It is so far known 

district (station 2375); Leadville limestone. 

C. catastoGASTEROPODA. 

PLATYCERAS Conrad, 1840. 

Keyes, following European usage, advocatesa the employment for this group of 

Paleozoic shells of the name given by Montfort to a closely similar type of living 

ones. He states,' "the two genera last mentioned [Capulus and Platyceras] are practically coextensive, and, since the first has precedence of more than thirty years, it 

should be used instead of the second." It is admitted on all hands that the recent 

Capuli are closely related to the Platycerata, but it seems to me improbable that the 

same type has survived without change in its generic characters from middle or possibly early Paleozoic to recent time. The circumstance that the Capuli are fairly 

abundant at the present day, and that the Platycerata enjoyed their maximum 

development during the middle Paleozoic, declining rapidly in the Mississippian,c and 

being comparatively rare during most of the Carboniferous and Mesozoic, at least 

lends color to this view. I therefore propose to retain the Paleozoic Capuli under a 

name distinct from their living representatives. Regarding the eligibility of the 

name Platyceras, Keyes further states:d " Even if the group to which Conrad gave the 

name Platyceras were a valid one, it is very questionable whether the term could 

stand, inasmuch as it has been pre-occupied for three-quarters of a century. It has 

long been known that Geoffrey in 1764 proposed for a genus of Coleoptera the name 

Platyceras, a term which was later employed by Latreille, and which continues to 

the present day in good usage as originally proposed." I find, however, that the 

spelling given by both Bronn

ceras, 

it has long been known. 

Platyceras 

as Keyes cites it, but 

being thus removed, I shall retain, it in the force and significance in which 

Platycerus. 

e and Scudderf for the Coleopterous genus is not 

The objection to the employment of Conrad's 

Platya Missouri Geol. Surv., vol. 5, 1894, p. 164 et seq., and in d Ibid., p. 164. 

other publications. e Index Palnontologicus, pt. 1, Stuttgart, 1848, p. 992. 

b Ibid. f U. S. Nat. Museum, Bull. 19, 1882, p. 251. 

Ibid., p. 172. 
DESCRIPTIONS OF SPECIES. 311 

PLATYCERAS PARALI1TM White and Whitfield? 

1862. Platyceras paralium. White and Whitfield, Boston Soc. Nat. Hist., Proc., vol. 8, p. 302. 

Chemung group: Burlington, Iowa. 

1865. Platyceras paralium. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 131. 

Lithographic limestone: Clarksville, Mo. 

1888. Platyceras sp. (cf. P. paralium). Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 92, pl. 1, fig. 

23 (fig. 22?). 

Waverly group:. Licking County, Ohio. 

1889. Platyceras paralium. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 294. 

Kinderhook group: Burlington, IOwa. 

1890. Capulus paralius. Keyes, Am. Geol., vol. 6, p. 9. 

1890.. Capulus paralius. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 166, pl. 2, figs. la, b. 

Kinderhook beds: Des Moines and Marshall counties, Iowa; Lodi, Ohio. 

1895. Capulus paralius. Keyes, Missouri Geol. Surv., vol. 5, p. 174, pl. 53, figs. la-d. Date of 

imprint, 1894. ) 


Chouteau limestone: Seda'lia, Mo. 


Burlington limestone: Louisiana, Mo. 


The material from Colorado consists of three specimens from as many localities 

in the San Juan region, and it occurs entirely in the form of internal casts. These 

show a loosely coiled, laterally compressed shell, without any traces of longitudinal 

plications. It is the form which, occurring in the Madison limestone of Yellowstone 

Park, was briefly described in my report upon the Madison fauna, as Platyceras 

form d. As pointed out in that place, a shell of this type has been figured by Keyes 

under the name of Caputus _paralius,a although it seems to differ rather widely from 

the type specimen of that species represented by fig. la of the same plate. The 

Colorado material, while attaining a size considerably greater than that from 

Yellowstone Park, is still not quite as large as shown in fig. ld. 

Locality and Horizon.—San Juan region (stations 2381, 2382, 2385); Ouray 

limestone. 

ORTHONYCHIA Hall, 1843. 

ORTHONYCHIA FORMOSA Keyes? 

1888. Platyceras formosum. Keyes, Am. Phil. Soc., Proc., vol. 25, p. 242, pl. —, figs. 8, 9. 

Kinderhook group: Marshall County, Iowa. 

1890. Capulus formosus. Keyes, Am. Geol., vol. 6, p. 9. 

1890. Capulus formosus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 164, pl. 2, fig. 8. 

Kinderhook beds: Marshall County, Iowa. 

1892. Orthonychia formosum. Keyes, Am. Geol., vol. 10, p. 276. 

1895. Orthonychia formosum. Keyes, Missouri Geol. Surv., vol. 5, p. 189, pl. 53, fig. Date of 

imprint 1894.) 


Kinderhook group: Marshall County, Iowa. 


Burlington limestone: Louisiana, Mo. 


a Missouri Geol. Surv., vol. 5, 1894, p1. 53, fig ld. 
312 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The only specimen in the collection is an internal cast which shows a rapidly 

expanding, slightly curved, conical shell, the apex of which has been broken away. 

Though somewhat larger, it resembles in general shape Keyes's figure of Orthonychia 

formo8a, but the lobation is considerably more indistinct than in his type, and I am 

unable to state definitely whether, as in it, there are exactly five lobes or not. 

Locality and horizon. —San Juan region (station 2382); Ouray limestone. 

STRAPAROLLUS Montfort, 1810. 

STRAPAROLLUS LUXUS White. 

1875. ,Euomphalus luxus. White,.U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 94, pl. 5, 

figs. 13a, b. (Whole volume published in 1877.) 

Subcarboniferovs: Ophir City, Utah. 

1877. Euomphalus laxus. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 260, pl. 4, 

figs. 24, 25. 

Near base of Wasatch limestone (Waverly): Dry Canyon, Oquirrh Mountains, and Logan 

Canyon, Wasatch Range, Utah. 

My material represents for the most part only internal casts, but, fortunately, 

some specimens show clearly that the peritreme was carinated and had a section 

comparable to that of Straparollus luxus. The rise of the spire is also about the 

same, and a comparison with the type and other typical specimens leaves little doubt 

that the Colorado form is conspecific. The latter attains a greater size than has yet 

been observed in St. luxus from the typical area. Some specimens show a major 

radius of 35 mm., and one has been observed still larger. 

A direct comparison of the_ types of the two species leads me to believe that 

Straparollus luxus is probably a synonym of StraparoUus subplanus Hall (Weller 

incorrectly refers the latter to Phanerotinus),a and Straparollus luaus should also be 

examined in the same connection. This species is abundant in the Crested Butte 

region, where alone it has so far been brought to light. 

Locality and horizon.—Crested Butte district (stations 2352, 2355, 2357); Leadville limestone. 

STRAPAROLLUS OPHIRENSIS Hall and Whitfield. 

1877. Euomphalus (Straparo llus) ophirensis. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., 

vol. 4, p. 261, p1. 4, figs. 26, 27. 

Waverly group: Dry Canyon, Oquirrh Mountains, Utah. 

This species has been identified at three localities, two of them (stations 2362 

and 2363) being in the Aspen region, the other (station 2352) in the Crested Butte 

region. The specimens from Frying Pan Creek (station 2362) are identified with 

some confidence. A less degree of assurance is felt regarding two small imperfect 

examples from station 2352 and some very fragmentary specimens from station 2363. 

aU. S. Geol. Surv., Bull. No. 153, p.'420. 
DESCRIPTIONS OF SPECIES. 313 

Locality and horizon.—Crested Butte district (station 2352) ; Leadville limestone. 

Aspen district (stations 2362, 2363?); Leadville limestone. 

STRAPAROLLUS UTAHENSIS Hall and Whitfield. 

1877. Euomphalus (Straparollus) utahensis. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., 

vol. 4, p. 259, p1. 4, figs. 20-23. 

Near base of Wasatch limestone (Waverly): Dry Canyon, Oquirrh Mountains, Ogden, and 

Logan canyons, Wasatch Range, Utah. 

1899. Straparollus utahensis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 573, pl. 66, figs. 10a-10c. 

Madimn limestone: Yellowstone National Park. 

This species is represented in the Aspen region by a single specimen. It is 

mostly exfoliated, but there is evidence of a carination centrally located on the upper 

surface of the peritreme. This specimen also differs from similar casts of St. luxes 

by reason of its depressed spire, which is lower than the outer volution. These 

characters ally it to St. utahensis, though it attains a much greater size than has yet 

been observed in that species. It shows a major axis of 60 mm., and the outer 

volution is 32 mm. thick. Straparollus utaliensis should be compared with St. roberti, 

to which it is closely related. 

Two specimens from the San Juan region (station 2381), though not well preserved, 

can be referred with considerable certainty to this species. 

Locality and horizon.—San Juan region (station 381); Ouray limestone. Aspen 

district (station 2362?); Leadville limestone: 

STRAPAROLLITS cf. SPERGENENSIS Hall. 

1856. Euomphalus spergenensis. Hall, Albany Inst., Trans., vol. 4, p..19. 

St. Louis limestone: Spergen Hill and Bloomington, Ind. 

1882. Euomphalus spergenensis. Whitfield, Am. Mus. Nat. Hist., Bull., vol. 1, p. 69, pl. 8, figs. 16-19. 

St. Louis group: Spergen Hill, Paynters Hill, Bloomington, and Ellettsville, Ind. 

1883. Euomphalus spergenensis. Hall, Geol. Surv. Indiana, 12th Rept., p. 350, pl. 31, figs. 16-19. 

St. Louis group: Spergen Hill, Lanesville, and Bloomington, Ind. 

1895. Straparollus spergenensis. Keyes, Missouri Geol. Surv., vol. 5, p. 159. ' (Date of imprint 1894.) 

St. Louis limestone: St. Louis, Mo. 

This form has been found only in the Leadville region and the identification 

adopted is that suggested in the list of Blue limestone species given on page 66 of 

the Leadville monograph.t! A few specimens obtained from the Leadville limestone 

show indeed a close resemblance to St. spergenensis. They vary considerably among 

themselves in the rise of the spire, but the limits ascribed to Hall's species in this 

particular are not exceeded. The more elevated ones are like the specimen figured 

by Whitfield (loc. cit., pl. 8, figs. 16, 17, 18), but there are others which, if not 

deformed by compression, have the spire nearly flat, closely corresponding to the 

types of the species (fig. 19) and to the dominant form at Spergen Hill. 

a U. S. Geol. Surv., Mon., vol. 12, 1886. 
314. CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

While these shells are similar to the Genevieve species, St. spergenensis, they 

show fully as close resemblance to St. ammon of the Kinderhook and lower Burlington periods, or they might be regarded as a slightly undersized variety of St. 

macromphalus Win., also of the Kinderhook; and it is quite possible that they are 

only immature specimens of some such species as St. luaus, the younger stages of 

which they closely imitate. 

Locality and Itorizon.—Leadville district (stations 2374, 2376); Leadville 

limestone. 

LOXONEMA Phillips, 1841. 

LOXONEMA? sp. 

This rather striking form has been observed at three localities. Two of these 

(stations 2350 and 2358) are in the Crested Butte region; the other (station 2363) in 

the Aspen region. Though the material obtained is so poor as to render even its 

generic reference uncertain, there is considerable probability that in each occurrence 

the species is the same. It is a large, elongate, spiral shell, with a diameter below 

of perhaps 35 mm. or more and an altitude of certainly not less than 60 mm. 

There must have been seven or eight whorls. The surface appears to have been 

smooth. A similar and perhaps identical form occurs in the Chouteau limestone of 

Pettis County, Mo. 

Locality and h,orizon.—Ciested Butte district (stations 2350, 2358); Leadville 

limestone. Aspen district (station 2363); Leadville limestone. 

PLEUROTOMARIA Defrance, 1824. 

PLEUROTOMARIA ? sp. a. 

Shell small; greatest diameter, 10 • mm. Spire low, probably not exceeding 

7 mm. from the middle of the inferior portion to the apex. Whorls, probably 

three or four. Umbilicus, probably closed. Peritreme, flattened above (for about 

2.5 mm. near the aperture) and gently sloping downward. There is a strong 

angulation where the return contour begins, the remainder of the outline being 

formed by a. rather full curve. A short distance below the angulation, where the 

surface is still nearly vertical, two ridges, probably representing a comparatively 

broad band, are seen. The upper, which is the stronger, is about 1.5 mm. below 

the angulation. 

A single specimen, an internal cast, is all that has yet been discovered of this 

species. No serious effort has been made to determine its specific affinities, and 

it is probably indeterminable. It is certainly distinct from the Pleurotomarict 

represented• by an impression from Larimer County. 

Locality and ltorizon.—Canyon (station 2366); Millsap limestone. 
DESCRIPTIONS OF SPECIES. 315 

P EUROTOMARIA ? Sp. b. 

As mentioned by White,a am ng the impressions from Larimer County is one of 

a small gasteropod shell. It co sists of about four volutions which are flattened 

above and angulated. The spire is high. This shell may be a pleurotomarioid, but 

in general configuration it prese is many features in common with a form described 

by White as11facrocheilina anguli era. It is much smaller than that species, however, 

and more slender, and probably as derived from a much earlier geologic period. 

Locality and horizon.—Pe bles of Millsap limestone (?) in the Red Beds 

conglomerate, Larimer (County ( tation 2364). 

BELL OPTION Montfort, 1808. 

BELLEROPHON sp. 

At station 2350 in the Cres d Butte district and station 2381 in the San Juan 

region single specimens of Bello phon have come to hand, representing, not improbably, the same species. As one specimen is an internal cast and the other is completely embedded in chert, but few characters of importance can be ascertained. 

The species seems to be a large ne and the axial diameter of the larger specimen (at 

the aperture) is about 40 mm. ; t e longitudinal, 45 mm. It somewhat resembles Bel 

lerophon crassus and probably ca be referred to the genus Bellerophon, sensu stricto. 

Locality and h,orizon.—Sa Juan region (station 2381); Ouray limestone. 

Crested Butte district (station 23 0); Leadville limestone. 

CRUSTACEA. 

PHILLIPSIA Portlock, 1843. 

PHILLIPSIA P ROCCIDENS Hall and Whitfield. 

1877. Proetus peroccidens (pars). Hall' and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, 

p. 262, pl. 4, figs. 31, 32, 30 (?) (non figs. 28, 29=Phillipsia loganensis). 

Waverly group: Ogden and Logan canyons, Wasatch Range, and Dry Canyon, Oquirrh 

Mountains, Utah. 

1887. Proetus peroccidens (pars). Vogd • s, New York Acad. Sci., Ann., vol. 4, p. 79. 

Waverly group: Ogden, Logan Canyon, Wasatch Range, and Dry Canyon, Oquirrh Mountains, Utah. 

In discussing Proetus toga sis in 1899 b I expressed a doubt as to the propriety 

of referring to P. peroccidens c rtain cephalic shields which, though associated with 

the pygidia characteristic of th t species, are yet very different in the character of 

their surface ornamentation. T e pygidium of P. peroccidens, it may be remarked, 

is highly ornamented with rows of nodes or pustules, while the surface of P. logam,-. 

aU . S. Geol. Geog. Surv. Terr., Bull., vol. 5, 1879, p. 215. b U. S. Geol. Surv., Mon., vol. 32, pt. 2, 1899, p. 578. 
316 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

ensis is smooth. The cephala referred by Hall and Whitfield to P. peroccidens, 

however, while correspondingly larger than the pygidium upon which P. loganensis 

is based, and though occurring on the same slab as the types of P. peroccidens, are 

yet entirely without the ornamentation of the latter species. 

During the past few years I have handled more or less material containing this 

fauna, and in it have noticed on several occasions a large cephalic shield ornamented 

with numerous prOminent nodes. At station 2382, in the San Juan region, one 

of these ornamented cephala, is associated with an ornamented pygidium clearly 

belonging to the species P. peroccielens, while in Yellowstone Park the smooth heads 

and pygidia occur together. It seems quite conclusive, therefore, that part of 

P. peroccidens as defined by Hall and Whitfield, and all of that species as defined 

by myself, must go with P. loganensis. These changes in synonymy have been 

made in the list preceding this discussion. 

This species, in view of the large number of segments in the axis of the'pygidium, the distinctness of the lateral lobes of the glabella, and the strong circular 

basal lobes, should, it seems, be properly referred to the genus Ph,illipsia. 

Locality and horizon.—San Juan region (station 2382); Ouray limestone. 

LEPERDITIA Rouault, 1851. 

LEPERDITIA sp. 

Two specimens of ostracodes, one a Leperditia, the other a Beyrichia, were 

found in the Millsap limestone at Perry Park (station 2389). The material is both 

scanty and imperfect, but since these were the only ostracodes obtained from this 

horizon it has seemed worth while to make some record of their presence. 

The single Leperditia is preserved as an internal cast. It is a small left valve 

having a width of about 2 mm. and a height of 11 mm. The convexity is Moderate. 

The anterior end is somewhat narrower than the posterior. The posterior outline 

appears to have little or nothing of a back ward swing, but is rather regularly 

rounded, meeting the ventral outline possibly somewhat abruptly. There are indications of a large, round, subcentral, muscular imprint, but I am not sure that what 

appears to be such is not an accidental character of the rock. The ocular tubercle I 

have been unable to distinguish. 

Locality and horizon.—Castle Rock quadrangle (station 2389); Millsap limestone. 

BEYRICHIA McCoy, 1844. 

BEYRICHIA sp. 

Like the preceding, this species, of which a single specimen has been found, is 

represented as an internal cast in white chert, in which the fossils of this horizon 

chiefly are found. The shell, which is -a right valve, is quite a small one, having a 
DESCRIPTIONS OF SPECIES. 317 

width of only about 1 mm. and a height of one-half mm. The shape is transversely 

elliptical, there being very little difference in height apparent between the two ends. 

The median lobe is small, circular, strongly marked, and has about three-fifths of the 

shell anterior to it. A deep furrow bounds it centrally, giving off a branch which 

extends a short distance toward the anterior end and disappears, thus marking off, but 

imperfectly, an anterior lobe considerably larger than the small circular one. The 

dorsal portion of the cast is flattened, the anterior abruptly elevated and ridge-like. 

Locality and horizon.—Castle Rock quadrangle (station 2389); Millsap limestone. 

PENNSYLVANIAN SPECIES. 

PROTOZOA. 

FUSULINA Fischer de Waldheim, 1830. . 

FUSULINA CYLINDRICA Fischer de Waldheim. 

1830. Fusulina cylindrica. Fischer de Waldheirn, Oryct. du Gouv. Moscou, pl. 13, figs. 1-5. 

(Another edition of this work which I have not seen appeared in 1837. Probably to this 

edition the usual references, p. 126, pl. 18, apply, as they do not to the early one. 

1858. Fusulina cylindrica. Meek and Hayden, Acad. Nat. Sci. Philadelpia, Proc., p. 260. 

Carboniferous: Valley of the Kansas River, Kansas. 

1859. Fusulina cylindrica. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 24. 

Coal Measures: Kansas. 

1861. Fusulina cylindrica. Newberry, Ives's Colorado River Expl. Exped., p. 129. 

Coal Measures: Kansas. 

1864. Fusulina cylindrica. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, p. 14, 

pl. 1, figs. 6a-i. 

Coal Measures: Ohio to Kansas and Southwestern Nebraska, and South to Texas.. 

1864. Fusulina cylindrica? Meek, Pal. California, vol. 1, p. 4, pl. 2, figs. 2, 2a. 

Carboniferous: Bass's ranch, Shasta County, Cal. 

1866. Fusulina cylindrica. Geinitz, Carb. and Dyas in Nebraska, p. 71, tab. 5, fig. 5. 

Upper Coal Measures: Plattsmouth, Nebr. 

1872. Fusulina cylindrica. Meek, U. S. Geol. Surv. Nebraska, p. 140, pl. 1, fig. 2; pl. 2, fig. 1; p1. 5, 

figs. 3a, b; p1. 7, figs. 8a, b. 

Upper Coal Measures: 2i miles west and 1 mile southeast of Nebraska City; Bennett's Mill, 

Wyo.; Rock Bluff, Plattsmouth, Bellevue, and Omaha City, Nebr. 

1877. Fusulina cylindrica. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 96, pl. 6, 

figs. 6a2 b. 

Carboniferous: Wasatch Range, south of Spanish Fork; Uiyabu Pass, Gosute Range; near 

Beckwith Spring, Cedar Range; near the mouth of Spanish Fork Canyon; southeast of Mount 

Nebo; all in Utah. 

1877. Fusulina cylindrica. Whiteaves, Geol. Surv. Canada, Rept. Prog., 1875-76, p. 97. 

Carboniferous or Permian: Rear of Fort St. James, Stewarts Lake, British Columbia. 

1884. Fusulina cylindrica. White, Geol. Surv. Indiana, 13th Rept., p. 116, p1. 23, figs. 1-3. 

Coal Measures: Ohio to California; limestone roof of coal K, Lodi, Fountain County, Ind. 
31.8 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1887. Fusulina cylindrica. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 50, pl. 3, fig. 20. 

Coal Measures: Flint Ridge, Ohio. 

1891. Fusulina cylindrica. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 245. 

Lower Coal Measures: Des Moines, Iowa. 

1894. Fusulina cylindrica. Keyes, Missouri Geol. Surv., vol, 4, p. 102, pl. 12, figs. 1 a—c. 

Coal Measures: Kansas City and Lexington, Mo. 

1899. Fusulina cylindrica. Smith, Kansas Acad. Sci., Trans., vol. 16, p. 64, figs. 1-4. 

1900. Fusulina secalica. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 10, p1. 1, figs. 1, lb. 

Upper Coal Measures: Kansas. 

The genus Fusulina experienced a long range in the Carboniferous strata of Colorado, although it is possibly less abundant at the lower horizons than at the upper. 

The lowest ascertained occurrence of the genus is at Ouray, where it is plentiful 

at an horizon about 100 feet above some beds with fossil plants, the evidence of 

which, though not conclusive, would favor correlating them with the lower portion 

of the Lower Coal Measures as developed in the Pennsylvania section. In the San 

Juan region also Fusulina is found toward the base, as well as near the top, of the 

Carboniferous section, and a range probably of 2,000 feet must be assigned to it in 

this area. A similar range is indicated by its occurrence at Leadville. 

It is difficult to correctly estimate the shape and size of these small bodies, as 

they lie promiscuously diffused through the rock in which they are embedded, but 

examples from the same locality seem to be in essential agreement with each other 

in the particulars named, while, with the exception of a station in the Crested Butte 

region (2312), all the occurrences noted appear to belong to the same species. This 

opinion, however, is based upon their agreement in external characters and lacks the 

corroboration of microscopic study.a 

The prevailing form in the Colorado collections is rather small and spindle shaped, 

with an axial diameter of from 3 to 4 mm. and a radial diameter of from 1.5 to 2 mm. 

While there seems to be but little variation in F. cylindrica as it appears at different localities, specimens from the San Juan region often attain a larger size than 

elsewhere. 

It is doubtless true that wherever this species has been found it is abundant, 

but this circumstance probably proceeds from the fact that owing to its minute size 

it attracts attention only when present in large numbors. But if its rarer occurrences were known it would perhaps be found to be rather continuously represented 

in the rocks than, as seems now, at remote but prolific intervals. 

Beede employs the name Fusulina secalica instead of the more familiar one 

proposed by Fischer, the specific portion of the combination being due to Say. The 

latter originally referred his types, which were obtained on the Missouri River near 

the Platte, to lites, but it is clear that he had a species of FlintUna. In view 

a Microscopic study of these shells, as far as it has been carried by me, tends to confirm the opinion that they belong 

to one species. 
DESCRIPTIONS OF SPECIES. 319 

of our inadequate knowledge of the fossils which Say called Miliolites secalicus, it 

seems to me inadvisable at present to substitute it for the name in current use. 

Furthermore, since Say states that M. secalicus has a length of three-tenths of an 

inch and a diameter of one-sixteenth, it appears that his species is larger and differently proportioned from the one under discussion. 

It may not be out of place to mention at this point that evidence exists of the 

presence of foraminifers other than Fusulina in the Colorado Carboniferous. Near 

Ouray (station 2195b) minute shells whose foraminiferal nature is very probable 

occur in considerable numbers. As they are known only in thin sections, and as 

identification in this condition is very difficult, it seemed unprofitable to continue 

their investigation. 

Locality and horizon.—San Juan region (stations 2199, 2208, 2210, 2211, 2213, 

2221, 2227, 2232, 2233, 2235, 2237, 2286, 2339); lower, middle, and upper portions of 

the Hermosa formation. Ouray (stations 2194, 2195b, 2195c); Hermosa formation. 

Crested Butte district (stations 2290, 2293, 2305, 2308, 2321); Weber limestone and 

Maroon formation. 

FUSITLINA CYLINDRICA var. VENTRICOSA Meek and Hayden ? 

1858. Fusulina cylindrica var. ventricosa. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 261. 

Carboniferous: Juniata and Manhattan, Kans. 

1859. Fusulna cylindrica var. ventricosa. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 24. 

Coal Measures: Manhattan and Juniata, Kans. 

1873. Fusulina ventricosa. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 560, pl. 24, fig. 8. 

Coal Measures: Fulton and Peoria counties, Ill. 

1874. Fusulina ventricosa. Meek. Am. Jour. Sci. (3) , vol. 7, p. 484. 

In the Crested Butte region (station 2312) occurs a form of Fusulina in moderate abundance which differs considerably from the type common in the rest of the 

collection. It is smaller and in shape nearly spherical. Its axial diameter is under 

1 mm. and its radial diameter is somewhat less. 

This form seems rather closely related to that figured by Meek and Worthen 

under the name of Fusulina ventricosa, although it is very much smaller. I mistrust 

that the F. ventricosa of their reference may not be the same as that to which the 

name F. cylindrica var. ventricosa was originally applied. 

Locality and horizon.—Crested Butte district (station 2312); Weber limestone. 

SPONGIA. 

HYALOSTELIA Zittel, 1878. 

HYALOSTELIA sp. 

Crossing the surface of a slab of limestone from near Molas Lake in the Silverton quadrangle (station 2279) are large numbers of an unusual fossil which I at first 
320 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

took to be Productus spines, but which, it seems, can be properly referred only to .a 

sponge of the genus Hyalostelia. These -bodies consist of nearly straight, smooth, 

slender, cylindrical rods of several sizes, all, or nearly all, lying in the same direc 

tion, contiguous and superimposed. Some of the largest have a diameter of but 

little less than 0.5 mm., and one of them has been traced to a length of 82 mm. In 

this distance the taper is almost imperceptible. Besides the large rods there are 

others of almost hair-like proportions, and altogether of both sorts there must be 

many. hundred. No anchoring hooks or other peculiar terminal formations have 

been observed. While most of the spicules have a nearly or exactly identical direction, a few fine and fragmentary ones are directed more or less transversely to them. 

There can be little doubt that these bodies are the basal. tuft of a sponge. of a. type for 

which the name Ilyalostelia was proposed. No spicules of different type have been 

observed, the shorter ones being cylindrical like the larger and doubtless but frag-• 

tnents of them. 

_Locality and horizon.—San Juan region, Silverton quadrangle (station 2279); 

lower portion of the Hermosa formation. 

HYSTRIOSPONGIA Ulrich, 1890. 

HYSTRIOSPONGIA I sp. 

From the same station which furnished the specimen of Hyalostelia just mentioned another quite different sponge was obtained. It occurs in a, calcareous black 

shale, on the surface of which it appears as a superficial entanglement of spicules, 

with a circular shape and a diameter of about 20, mm. The spieules are so meshed 

together that it is impossible to make out their characters as completely as desirable. 

They seem to consist of fine, slender, rod-like elements, having a radial direction. 

No trifid spicules have been observed, but such might readily escape notice. 

Locality and horizon.—San Juan region, Silverton quadrangle (station 2279); 

lower portion of the Hermosa formation. 

CCELENTERATA. 

LOPHOPHYLLUM Milne-Edwards and Haime, 1850. 

LOPHOPHYLLUM PROFUNDUM Milne-Edwards and Haime. 

1851. Cyathaxonia profunda. Milne-Edwards and Haime, Monog. des Polyp. Foss., p. 323. 

Carboniferous: Flint Ridge; Ohio. 

1860. Cyathaxonia profunda. Milne-Edwards, Hist. Nat. Corr., vol. 3, p. 331. 

Carboniferous: Ohio, 

1860. Cyathaxonia prolifera. McChesney, Desc. NeW Spec. Pal. Foss., p. 75. 

Coal Measures: Widely distributed in the Western States. 

1865. Cyathaxonia prolifera. McChesney, Illustrations New Spec. Foss., p1. 2, figs. 1-3. 
DESCRIPTIONS OF SPECIES. 321 

1866. Cyathaxonia (?) sp. Geinitz, Carb. and Dyas in Nebraska, pp. 65, 66, tab. 5, figs. 3, 4. 

Upper Coal Measures: Plattsmouth, Nebr. 

1868. Cyathaxonia prolifera. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 1, pl. 2, figs. 1-3. 

Coal Measures: Springfield, Ill. 

1872. Lophophyllum proliferum. Meek, U. S. Geol. Surv. Nebraska, p. 149, pl. 5, figs. 4a, b. 

Upper Coal Measures: Nebraska City and Rock Bluff, Nebr.; Springfield and Lasalle, Ill.; 

Texas. 

1873. Lophophyllum proliferum. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 560, pl. 24, 

fig. 1. 

Upper Coal Measures: Springfield, Ill. 

1876. Lophophyllum proliferum. White, Powell's Rept. Geol. Uinta Mountains, p. 88. 

Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

1884. Lophophyllum proliferum. White, Geol. Surv. Indiana, 13th Rept., p. 118, pl. 23, figs. 6, 7. 

Coal Measures: Indiana; Illinois; Iowa. 

1887. Cyathaxonia prolifera. Foerste, Sci. Lab. Denison Univ., Bull., vol. 2, p. 86, pl. 7, figs. 15a-c. 

Coal Measures: Flint Ridge and Bald Hill, Ohio. 

1888. Lophophyllum profunda. Foerste, Sci. Lab. Denison Univ., Bull., vol. 3, p. 136. 

Coal Measures: Flint Ridge, Ohio. 

1888. Lophophyllum proliferum. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 225. 

Lower Coal Measures: Des Moines, Iowa. 

1890. Lophophyllum profundum. Worthen, Geol. Surv. Illinois, Rept., vol. 8, p. 79, p1. 10, figs. 14, 14a. 

Coal Measures: Lasalle, Ill. 

1894. Lophophyllum proliferum. Keyes, Missouri Geol. Surv., vol. 4, p. 115, pl. 13, figs. 8a, b. 

Upper Coal Measures: Kansas City, Mo. 

1897. Lophophyllum proliferum. Smith, Am. Phil. Soc., Proc., vol. 35, p. 25. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

1900. Lophophyllum profundum. Beede, Univ. Gedl. Surv. Kansas, Rept., vol. 6, p. 17. 

Upper and Lower Coal Measures: Fort Scott, 1VIarmaton, Bourbon County, Thayer, Olathe, 

Kansas City, Lawrence, Lecompton, Topeka, McFarland, Grand Summit, Kans. 

This species has been identified at nine localities, but it is represented for the 

most part by only one or two specimens at each. The material is not only scanty 

but it is frequently fragmentary. It shows a high degree of variation in essential 

points, such that in some examples, especially in the younger stages, it is not even 

clear whether a pseudo-columella has been developed or not. In some specimens many 

interseptal plates are present, in others none at all—at least in the sections examined. 

Sometimes the septa are almost diagrammatic in their regularity and arrangement; 

at other times they are contorted and their extremities connate into varying groups. 

Occasionally the latter irregularity is carried to an extreme. Perhaps the most 

diagnostic character consists in the number of the septa, and upon this basis it 

is possible to distinguish two groups among the specimens examined. In one of 

these there are about 21 primary septa, in the other from 24 to 30. Alternating 

with these, especially in the calicinal portion of the corallum, can sometimes be seen 

an equal number of shorter secondary septa. Specimens from stations 2222, 2302, 

14364—No. 16-03-----21 
322 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and possibly 2329b belong to the group with 21 septa. To the other belong specimens furnished by stations 2202, 2204, 2233, 2241, 2285, and 2299. I am in doubt 

about the bearing which more extensive collections would have in the matter of the 

validity of the two groups which my material indicates, whether it would establish 

them as distinct species or varieties, or demonstrate that they are only mutations of 

a single radical. I have placed all with the well-known L. profundum, but it is with 

a feeling of dissatisfaction at this disposition. 

Locality and horizon.—San Juan region (stations 2202, 2204, 2222, 2233, 2241); 

middle and upper portions of the Hermosa formation. Dolores River region, Sinbads Valley (station 2285); Hermosa formation. Crested Butte district (stations 

2299 ?, 2302, 2319); Maroon formation. Grand River region, Glenwood Springs 

(station 2329b?). Uinta Mountain region, overlooking Yampa River (station 2191). 

AMPLEXUS Sowerby, 1814. 

AMPLEXUS sp. 

Only two specimens of this species have yet been found, both from the San Juan 

region, but each from a different locality. One, from the mouth of Hermosa Creek 

(station 2242), is nearly indeterminable, but it probably belongs to the same species 

as the other, which was found near Deadwood Gulch in the Rico quadrangle (station 

2222). 

The latter is small, conical, and wnere the diameter measures 7 mm. has 18 septa 

which reach about halfway to the center. There is no dissepimental tissue, the 

remaining cavity being dissected by tabulw. 

The characters shown by this material indicate that it belongs with the genus 

Amplexus rather than with Zaphrentis or CampophylLum. The only known species 

of Amplexus from,the Upper Carboniferous of America is A. zaphrentiformis White, 

young specimens of which, when sectioned at the same stage, differ materially from 

the form under consideration. The septa are somewhat more numerous, reach quite 

to the center, and inclose a large, well-marked fossula. I would scarcely be justified, 

therefore, in regarding these fossils as representatives of White's species. 

This coral quite strikingly resembles, in some particulars, the species which 

Beede described as Amplexus westi,a but that form, as Beede has since shown,b is 

clearly a member of the genus Lophoph,yllum. 

Locality and horizon.—San Juan region (stations 2222, 2241); middle and upper 

portions of the Hermosa formation. Crested Butt district (station 2316); Weber 

limestone. 

a Kansas Univ. Quart., vol. 7, 1898, p. 17. 

b Univ. Geol. Surv. Kansas, Rept., vol. 6, 1900, p. 18. 
DESCRIPTIONS OF SPECIES. 323 

CAMPOPHYLL UM Milne-Edwards and Hahne 1850. 

CAMPOPHYLLUM TORQUIUNI Owen. 

1852. Cyathophyllum (vermieularef). Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 4, fig. 2, 

Carboniferous limestone: Near mouth of Keg Creek. 

1852. Cyathophyllum torquium. Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 4, fig. 2. 

Carboniferous limestone: Near mouth of Keg Creek. 

1852. Cyathophyllum flexuosum (?). Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 4, figs. 

3a, b. 

Carboniferous limestone: Near mouth of Keg Creek. 

1872. 	Campophyllum torquium. Meek, U. S. Geol. Surv. Nebraska, p. 145, pl. 1, figs. la-d. 

Upper Coal Measures: Rock Bluff and Cedar Bluff, Nebraska; Iowa. 

Coal Measures: Illinois. 

1884. Campophyllum torquium. White, Geol. Surv. Indiana, 13th Rept., p. 119, pl. 23, figs. 10-13. 

Upper Coal Measures: Iowa; Missouri; Nebraska; Illinois; Indiana. 

1894. Campophyllum torquium. Keyes, Missouri Geol. Surv., vol. 4, p. 107, pl. 12, figs. 7a-e; p1. 13, fig.7. 

Coal Measures: Kansas City, Mo. 

1900. Campophyllum torquium. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 19, pl. 4, fig. 1; pl. 

5, figs. 1-4_ 

Coal Measures: Kansas City, Jefferson, Douglas, and Chautauqua counties, Kans. 

The fossils representing this species are in no instance abundant, and they are 

usually in a poor condition of preservation. They can probably safely be referred, 

however, to the common C. torquium. 

Locality and horizon.—San Juan region (stations '2206, 2208); upper portion of 

Hermosa formation. Ouray (station 2194); Hermosa formation. Crested Butte 

district (stations 2291, 2298, 2312); Weber limestone and Maroon conglomerate. 

ZAPHRENTIS Rafinesque, 1820. 

ZAPHRENTIS GIBSONI White. 

1884. Zaphrentis gibsoni. White, Geol. Surv. Indiana, 13th Rept., p. 117, pl. 23, figs. 4, 5. 

Coal Measures: Vermilion County, Ind. 

White calls attention to the fact that the genus Zaphrentis, which occurs so 

abundantly in the earlier Carboniferous and throughout the Devonian, is very rare 

in strata of Upper Carboniferous age. Only three specimens in our collections 

from Colorado can be referred to Zaphrentis, and each was found at a separate 

locality. They are in mutual agreement in having 35 somewhat alternating septa, 

but present minor differences in regard to rate of enlargement, prominence of the 

fossula, amount of interseptal tissue, etc. As these points are susceptible of considerable variation within the limits of a single species, they do not in this instance, 

it seems to me, call for a subdivision of the small group of forms presented for 
324 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

study. As these agree, in all the points mentioned by White in his description, 

with Z. gibsoni, I have referred them to that species without much hesitation. 

Locality and horizon.—San Juan region (stations 2216, 2332); middle and upper 

Hermosa. Crested Butte district (station 2312); Weber limestone. 

MONILIPORA Nicholson and Etheridge, 1879. 

MONILIPORA PROSSERI Beede. 

1898-. Aulopora prosseri. Beede, Kansas Univ. Quart., vol. 7, No. 1, p. 18. 

Upper Coal Measures: Lyndon, Osage County, Kans. 

1900. Aulopora? prosseri. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 23, pl. 3, fig. 2; pl. 4, fig. 2. 

Upper Coal Measures: Lyndon, Osage County; Lecompton and near Twin Mounds, Douglas 

County, Kans. 

This form occurs in large masses in some thin limestones outcropping along the 

Silverton road in the Engineer Mountain quadrangle (station 2199). It agrees in so 

many particulars with Aulopora2 prosseri, as the latter is represented in Beede's 

illustrations and descriptions., that it probably belongs to the same species. 

Beede calls attention to the large size to which coralla of this species sometimes 

attain, citing one colony which, though incomplete, measured 22 inches across. At 

the Colorado locality a growth, belonging apparently to a single colony, formed a bed 

from 3 to 6 inches high, which covered an area of 9 square feet and probably considerably more. While the size of the colony in these instances is suggestive rather of 

the genus Syringopora, the manner of growth is different, for instead of consisting of 

long, nearly parallel corallites connected by stolonal arms, the individuals are short 

and variously directed. They bud persistently, and I judge, although the imperfect 

manner in which the specimen is seen embedded in matrix may be misleading, that 

with few exception each corallite gave off two buds at a time, and perhaps more than 

once. There results a thick entanglement of corallites pointed in various directions; 

and though the component units are short and not connected and supported by 

stolonal growths, as in Syringopora, they contrive to build up a colony, as has been 

said, of several inches in height and very great spread. They are no doubt enabled 

to do this through the circumstance that the cell walls are excessively thickened, 

so that the lower portion of the corallites are nearly, possibly entirely, closed in 

this manner. It is naturally by concentric deposition that the walls are thickened; 

and as all the layers are not of quite the same consistency, weathered specimens 

sometimes present an appearance which simulates the well-known internal structure 

of Syringopora, but here the lines which might be mistaken for infundibuliform 

tabula are invariably completely circular, which is rarely the case in Syringopora, 

and they are parallel to the walls instead of converging to the center. The real 

structure, as' unmistakably shown in thin sections, is with the inner space, though 
DESCRIPTIONS OF SPECIES. 325 

much diminished through the thickening of the walls, uninterrupted by partitions. 

The average diameter is 2 mm. or less, as in typical AuloporaY prosseri, the 

shape is tubular rather than campanulate, and, indeed, the agreement in many 

particulars is close. On the other hand, there are important differences, among 

which may be mentioned the apparent absence from my material of tabula and 

pseudosepta, and the fact that the corallum of typical Aulopora? prosseri is described 

as prostrate and bifurcating, while in that before me the corallum is certainly not 

prostrate; for instead of having a thickness of from 3 to 7 mm., as I judge to be the 

case in the eastern form, it is ten times that, or 6 cm., and more; nor is the growth, 

so far as I have made out, so much bifurcating as that the corallites put forth 

simultaneously two lateral buds, each of these two others, and so on. 

In the Coal Measures of Kansas occurs a form which is probably congeneric 

with this one, although the species is different. The mode of growth is more regular 

increase is by budding, and two offshoots are as a rule developed simultaneously. 

The corallites are not generally connected by stolons, but occasionally root-like 

than in the Colorado form, and the general appearance is much like that of 

pora. 

processes are put out somewhat as in 

The corallites are long, erect, and approximately parallel. The mode of 

_Eridoph,yllum. These seem to be invariably 

Syringosolid and are of a different character from the stolonoid process which connects the 

incipient bud with its parent. The cell walls are extensively thickened. In the 

aperture of weathered specimens, where the wall is thinner than in the older portions, 

there call frequently be made out a number of indistinct septa or pseudosepta. The 

interior is otherwise entirely without structures in most cases, but in a few instances, 

for a limited space, the cavity is intersected by numerous closely arranged, slightly 

concave tabula. 

It seems to me that the three forms here mentioned belong to the same generic 

group. The mode of growth is rather different in the original Aulopora? _prosseri and 

ally identical with Beede's species, is intermediate in this regard. The syringoporoid 

the form last mentioned, which I have no doubt has often been identified as 

pora multattennuata 

colony must also have had a similar creeping growth in its earlier stages. I have 

not observed pseudosepta or tabula in the Colorado specimens, but the former are, 

McChesney, but the Colorado form, which may not be specificSyringoas a rule, to be seen only in weathered examples, while a large number of syringoporoid specimens from Kansas were examined before the tabulation was observed. 

The generic relations of all three forms is, I believe, with llfonih:pora. This is 

particularly evident in the case of Aulopora? prosseri, though the tabulation, rare in 

the latter, seems to be unknown in that genus. The growth of the syringoporoid 

colonies is also unlike that of Monili_pora, but may be a development of it. All 

these species need to be thoroughly studied and revised, but it is my belief at present 
326 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

that it would be departing from their obvious relationships to discriminate them by 

more than specific rank. 

Several years ago I described under SYyringoporaa two species, that present certain close resemblance to some forms for which Grabau about the same time proposed 

the generic name Ceratopora. Structurally my species seem to belong to Grabau's 

genus, but they differ in their mode of growth in the same manner that Syringopora 

does from Aulopora and the erect forms tentatively referred to ifonilipora do from 

the typical ones. The parallelism in growth shown by these species is significant, 

and seems to me to indicate that this character should be given only secondary 

importance. I am not sure but that my original reference of those species was 

and 

correct. Strangely enough, Grabau does not discuss the relationship of his 

topora 

real. Nicholson placed 

Ceratopora 

with either 

a new family which he called the Moniliporidee. This seems to me 

Aulopora 

Monilipora 

or Syringopora. 

in the Auloporidva, but Grabau erected for it 

Yet this relationship seems to me very 

Geraaltogether superfluous. 

On a slide from the Crested Butte region (station 2290) prepared for the microstarted to grow. The other was a later and apparently more prosperous attempt to 

scopic study of the form referred to 

like colonies are shown which probably belong to the form described above from 

more abundant material. In one case the youthful colony had been completely covered over and probably inclosed by the 

Chwtetes milleporaceus, 

Ch,wtetes upon whose massive corallum it had 

two young Auloporacolonize upon the same Chwtetes. Both incidents are transcribed upon the same thin 

section. The individual corallites in this instance are about 2 mm. in diameter and 

appear to be without septa, septal spines, or tabular. The walls are so much thickened as to leave an insignificant aperture in the center, the wall substance being 

radially fibrous. 

Associated with the auloporoid at both localities are numerous minute bodies, 

some of which resemble spicules so closely as to suggest that they may be of organic 

origin. They may, however, be only segregations of calcite (of which substance 

they now consist) without organic beginnings. The largest probably does not exceed 

1 mm. in length. The shape is irregularly elongate with one end usually larger than 

the other, and with the length some four or five times the greatest breadth. In 

other words, the outline is straight and tapering, with one end bluntly and irregularly rounded, and the other more or less pointed, but it is interrupted by spinous 

projections of considerable size, so that these bodies present an almost endless variety 

of shapes, and it is extremely difficult to frame a generalized description of them. 

They can scarcely be considered echinoid spines even if they are organic at all, and 

the general appearance is rather that of Gorgonia spicules. If the organic nature of 

a v. S. Geol. Surv., Mon., vol. 32, pt. 2, 1899, pp. 507, 510. 
DESCRIPTIONS OF SPECIES. 327 

these objects could be demonstrated, their evidence might be of value in its bearing 

upon the disputed point as to whether Aulopora really does belong, as has been 

claimed, to the Alcyonarian corals. At least the evidence would be in force to the 

extent that these forms are related to Aulopora. 

Another specimen from the Crested Butte region (station 2303) which probably 

belongs to the same species, though consisting of but a few corallites, yet seems to 

shed light upon the means by which extensive coralla are built up by these more 

or less disconnected tubes. In this specimen, in which the growth is more clearly 

shown through combined silicification and weathering than in the others, some of 

the corallites are closely proximate and, where in contact, develop strong concentric 

rugoe, which alternate in the two individuals adjacent to one another, and so in 

a measure interlock. These projections appear to be somewhat radiciform, and 

to a certain extent resemble the structures which form a distinguishing character 

of the genus Eridoph,yllum. 

In this specimen, as in those previously described, the corallites have a diameter 

of about 2 mm.; the walls are thickened, and tabula and septa appear to be absent. 

Locality and horizon.—San Juan region (station 2199); Hermosa formation. 

Crested Butte district (stations 2290, 2303); Maroon conglomerate. 

LEPTOPORA Winchell, 1863. 

LEPTOPORA WINCHELLI White. 

1879. Leptopora winchelli. White, U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, p. 211. 

Carboniferous: Near the forks of Logan River, in Bear River Range, northern Utah. 

1880. Leptopora winchelli. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 121, pl. 34, fig. 11a. 

Carboniferous: Near the forks of Logan River, in Bear River Range, northern Utah. 

If the single specimen obtained were in a more perfect condition it is possible 

that it would prove distinct from the species described by White. It has a somewhat irregular semicircular shape, with a diameter of about 45 mm., and seems to 

have been attached to a large specimen of Platyceras nebraskense. The constituent 

cells vary greatly in size. Some of the larger ones have a diameter of almost 5 mm., 

rather larger than anything in the material described by White. The height of the 

corallum seems to be insignificant compared with its lateral expansion, but some of 

the corallites must have had a length of at least 5 mm. There appear to have been 

no tabula, and no septa have been observed on the thin cell walls. 

Locality and horizon.—San Juan region (station 2279); lower portion of Her-

• mosa formation. 
328 CARBONIFEROUS FORMATIONS AND. FAUNAS OF COLORADO. 

CLADOPORA Hall, 1852. 

CLADOPORA sp. 

The specimens referred to under this name consist of two hemispherical masses 

having a diameter of about 5 mm., composed of numerous cells, the larger of which 

are about 1 mm. in diameter. The cell walls are thin, perfofate, and appear to be 

faintly fluted longitudinally. No tabula have been noticed. Except for the latter 

character these growths might pass for a small globular species of Favosites, but they 

more probably represent either the terminal or the initial portions of a rare and 

undescribed form, of which we have specimens from Graham, Young County, Tex., 

and also from the Trans-Pecos region, Texas. The latter has a dendritic shape, the 

larger branches attaining a diameter of 20 mm. These Texas specimens in general 

appearance resemble coralla in the Devonian which have been commonly referred a 

to the genus Striatopora, but they show more points of affinity with the type species 

of 

opora, 

cells open slightly upward and outward without the inferior projection or lip of 

Striatopora, 

Cladopora 

Cladopora 

which is easily lost by attrition, but they also lack the thickened apertures of 

or the stereoplasmic (?) apertural deposit of 

which would most likely be preserved. In their present condition the 

than with that of. Striatopora. They lack the projecting lip of 

Striatopora. 

CladThe figures of many American species of Striatopora strongly suggest that they 

properly belong rather to Cladopora. 

Locality and horizon.—Crested Butte district (station 2305); Maroon conglomerate. 

CH2ETETES Fischer de Waldheim, 1830. 

CFLETETES MILLEPORACEUS Milne-Edwards and Haime. 

1851. Chatetes milleporaceus. Milne-Edwards and Haime, Monog. des Polyp. Foss., p. 272. 

Carboniferous: Cumberland Mountains, Tennessee; Newburg, near Evansville, on the Ohio. 

1860. Chatetes milleporaceus. Milne-Edwards, Hist. Nat. des Corr., vol. 3, p. 271. 

Carboniferous: United States. 

1876. Chatetes milleporaceus. White, Powell's Rept. Geol. Uinta Mountains, p. 88. 

Red Wall group: Gypsum Canyon, Colorado River, Utah. 

Lower Aubrey group: Split Mountain Canyon, Green River, Utah. 

1877. Chwtetes milleporaceus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 98, pl. 

6, fig. 2a. 

Carboniferous: Virgin Range, southwest of St. George, Utah. 

1894. Chwtetes milleporaceus. Keyes, Missouri Geol. Surv., vol. 4, p. 123, pl. 14, figs. 12a, b. 

Upper Coal Measures: Glasgow, Mo. 

1900. Chwtetes milleporaceus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 25, pl. 2, figs. 11,11b. 

Coal Measures: Girard; very abundant in the Oswego limestone, Kansas. 

a Proctor's Kentucky Geol. Surv.; Kentucky Fossil Corals, Davis, 1885, Pt. II. Rominger's Geol. Surv. Michigan; Lower 

Peninsula, vol. 3, pt. 2. 1876. 
DESCRIPTIONS OF SPECIES. 329 

This species is very abundant at several localities in the Crested Butte region 

and it hats also been found in the San Juan region. It is massive in its growth, 

and my specimens indicate that the corallum attained a large size. The cells are 

small, seldom reaching 0.5 mm. in any diameter. They are usually considerably 

less. They present an almost infinite variety in the matter of shape, often having 

reentrant sides, but with the angles almost always rounded. Tabula are present, 

but great variation has been remarked in the intervals at which they occur. In 

some specimens they are regularly distributed and about 0.25 mm. apart. Such 

examples seem to represent the normal type of Ch. milleporaceus. In others they 

are at one place close together, at another quite distant, varying largely in the 

interval of occurrence, and in still others they can not be detected at all. Part 

at least of this variation can, I think, be ascribed to obliteration through mineralizing agencies, for the tabula are thinner than the walls, which are regularly 

preserved, but it is possible that there is considerable real structural variation as 

well. Periods of alternate growth and inactivity seem to have been an occasional feature in the life history of these colonies, which gives the corallum a 

banded appearance, and near the plane of inanition tabulation seems to be most 

frequent. The walls are thick and fibrous, the fibers being directed at right 

angles to the cell axes. 

a definite variety or possibly even a distinct species. 

sufficient, provided they are not due to the agencies of fossilization, to constitute 

poraceus 

It would seem that our collections show the presence of true 

in Colorado, with variations from the normal type, which may be deemed 

Ch,mtetes milleLocality and horizon.—San Juan region (stations 2196, 2228); middle portion 

of the Hermosa formation. Crested Butte district (stations 2290, 2306); Maroon 

conglomerate. ECHINODERMATA. 

ARCHAOCIDARIS Meek, 1872. 

ARCHIEOCIDARIS OURAYENSIS n, sp. 

Pl. I, fig. 14. 

The character of this species is well shown by the accompanying figure. It 

consists of a slender axis, slightly over 1 mm. in diameter, upon which are thickly 

clustered rather short, large spines which have a diameter almost as great as the axis 

itself. They are subcylindrical, bluntly pointed, inclined upward, and sometimes 

gently curved. 

The basal and distal portions of the style are unknown. 

This species is so unlike any other American form that comparisons with them 

are scarcely necessary. Its characteristic features so far as known are, of course, 

the very large size and close arrangement of the lateral spines. 

Locality and horizon.--Ouray (station 2194); Hermosa formation. 
330 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

ARCILEOCIDARIS TRIPLEX White? 

1881. Archwocidaris triplex. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., 

Appendix, p. xxii, pl. 4, figs. 3a-c. 

Carboniferous: New Mexico. 

1895. Archirocidaris triplex. Keyes, Iowa Acad. Sci., Proc:, vol. 2, p. 191. 

Upper Coal Measures: New Mexico. 

This species has been found at only one locality, and the identification is unsatisfactory because of the fragmentary character of the material. This consists entirely 

of spines of unusually large proportions. The diameter is 4-i mm. just above the 

ring and is still greater distally. When complete the length could hardly have been 

less than 12 mm., and it may have been greater. Comparatively small spinules project from the principal style at intervals of about 8 mm. On one important feature 

I have been unable to assure myself the character of the cross section. Of course 

near its base the style is cylindrical. Some small weathered fragments appear to be 

three-cornered, but in sections brought to view on the broken faces of the matrix 

this feature is less distinct. Here they usually show one or two flattened sides, with 

the rest of the outline circular. In the largest and most perfect specimen the spinules 

appear to be arranged in rows, which are sufficiently 'far apart to admit of but about 

three in the circumference. This would seem to indicate that the style was originally 

three-sided. The spines in the two rows in view are nearly but not quite opposite. 

Those in the same row are about 8 mm. apart, somewhat less than in the typical 

specimen of A. triplex, and the articulating ring is transverse, instead of, as in it, 

oblique. The nearest described species, next to A. triplex, is A. megastylus, but my 

specimens show many more spinules than are exhibited in Keyes's figures, and the 

articulating ring is much more projecting. The species also closely resembles 

A. eratis, but it is very much more robust, and the spinules appear to be considerably finer. 

_Locality and horizon.—San Juan region, Needle Mountains quadrangle (station 

2188); Molas formation. 

ARCKZEOCIDARIS TRUDIFER White ? 

1874. Archeocidaris trudifer. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. Invert. 

Foss., p. 17. 

Carboniferous (Coal Measures): Camp Apache, Arizona. 

1876. Archrocidaris trudifer. White, Powell's Rept. Geol. Uinta Mountains, p. 89. 

Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

1877. Archxocidaris trudifer. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 104, pl. 6, 

figs 8a, b. 

Carboniferous (Red Wall limestone): Camp Apache, Arizona. 

1895. Archaocidaris trudifer. Keyes, Iowa Acad. Sci., Proc., vol. 2, p. 191. 

Lower Carboniferous: "Camp Apache," Arizona. 

1900. Archeocidaris trudifer. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 47, pl. 8, fig. 10. 

Upper Coal Measures (Topeka limestone): Topeka, Kans. 
DESCRIPTIONS OF SPECIES. 331 

A single specimen, not very perfect, which resembles A. trudVer closer than 

any described species except, perhaps, A. edgarensis. The figures of these two 

species are so similar as to suggest that both names were proposed for the same 

specific type. 

Locality. —Leadville district (station 2265). 

ARCH.EOCIDARIS ORNATA Newberry. 

1861. Archrocidaris ornatus. Newberry, Ives's Colorado River Expl. Exped., p. 116, pl. 1, figs. 2. 3, 3a. 

Upper Carboniferous limestone: Banks of Colorado River. 

1877. Archuocidaris ornatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 104, pl. 6, 

fig. 7. 

Carboniferous: Ojo del Oso, near Fort Wingate, N. Mex. 

1895. Archuocidaris ornatus. Keyes, Iowa Acad. Sci., Proc., vol. 2, p. 191. 

Carboniferous: Ojo del Oso, N. Mex. 

One good specimen from the San Juan region (station 2235) is clearly the form 

which White identified with Newberry's species. At the two other localities the 

material is too imperfect to admit of a conclusive identification. 

Locality and horizon. —San Juan region (station 2235); middle portion of Hermosa formation. Leadville district (stations 2265, 2267); base of the Weber formation. 

A RCH2EOCIDARIS CRATIS White. 

1876. Archuocidaris cratis. White, Powell's Rept. Geol. Uinta Mountains, p. 109. 

Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

1880. Archwocidaris cratis. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 130, pl. 33, fig. 2a. 

Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

1895. Archnocidaris cratis. Keyes, Iowa Acad. Sci., Proc., vol. 2, p. 188. 

Coal Measures (Lower Aubrey) : Utah. 

This species is abundant near Ouray (station 2195b) and in fair preservation. 

Fragments of what is doubtless the same form were collected in the Leadville region 

(station 2265) and in the Crested Butte region (station 2307). This species is related 

to one described and figured by Keyes a as A. megastylus Shumard, and it would be 

little surprising if the one form should be traced into the other. The interambulacral 

plates have almost precisely the same characters in both, but the spines of A. megastylus are much larger and less spinose than the type known as A. cratis. It should 

be noted, however, that in the latter species the large spines or portions of spines 

have fewer subsidiary spinules than the smaller ones or portions. 

Locality and horizon. Crested Butte district (station 2307); Weber limestone. 

Leadville district (station 2265). Ouray (station 2195a); Hermosa formation. 

a Missouri Geol, Surv., vol. 4, 1894, p. 129, p1. 15, figs. 2a, 2b. 
332 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

EOCIDARIS Desor, 1858. 

EOCIDARIS HALLIANA Geinitz ? 

1866. Eocidaris hallianus. Geinitz, Carb. and Dyas in Nebraska, p. 61, tab. 5, figs. 1 a, b, 2 a, b. 

Upper Coal Measures: Nebraska City, Nebr. 

1872. Eocidaris hallianus. Meek, U. S. Geol. Surv. Nebraska, p. 152, pl. 7, figs. 9 a—d. 

Upper Coal Measures: Nebraska City, Nebr. 

1894. Archuocidaris hallianus. Keyes, Missouri Geol. Surv., vol. 4, p. 129. 

Upper Coal Measures: Kansas City, Mo. 

1895. Archuocidaris hallianus. Keyes, Iowa Acad. Sci., Proc., vol. 2, p. 190. 

Upper Coal Measures: Kansas City, Mo.; Nebraska City, Nebr. 

The material collected has suffered so much from weathering that a satisfactory 

identification is not possible. The fossils have been referred to Geinitz's species 

largely on account of their minute size. 

Locality and horizon.--Leadville district (station 2265). Crested Butte district 

(station 2320); Weber limestone. 

EUPACHYCRINUS Meek and Worthen, 1865. 

EITPACHYCRINIJS? sp. 

This identification rests upon a single imperfect specimen. Its generic position 

can not be determined with certainty, but it is of interest as being the only crinoid 

in the collections examined. 

Locality and horizon.—San Juan region (station 2221); upper portion of the 

Hermosa formation. 

HELMINTHA. 

CONULARIA Miller, 1821. 

CONULARIA CRUSTULA White? 

1880. 	Conularia crustula. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 170, pl. 42, fig. 4a. 

Coal Measures: Kansas City, Mo.; near Taos, N. Mex. 

1881. Conularia crustula. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., Appendix 

p. xxviii, pl. 3, figs. 4a, b. 

Carboniferous: Near Taos, N. Mex. 

1894. Conularia crustula. Keyes, Missouri Geol. Surv., vol. 5, p. 219, pl. 35, fig. 2. 

Upper Coal Measures: Kansas City, Mo. 

1897. 	Conularia conf. crustula. Smith, Am. Phil. Soc., Proc., vol. 35, p. 41. 

Coal Measures: Scott County, Ark. 

Crushed and imperfect specimens of Conularia appear in our collections from 

two localities. In their present condition it would be difficult to reach a trustworthy 

conclusion as to their relations to each other and to other forms; they seem to belong 

to a single species, namely, that to which White gave the name Oonularia crustula. 
DESCRIPTIONS OF SPECIES. 333 

Both specimens attain a size unusual for C. crustula and must have had a 

diameter of 25 mm. and a length proportional. The strive seem to be without ornamentation and are about 1 mm. apart on one specimen and 0.8 mm. on the other. 

Except for being of somewlat larger proportions these specimens are quite 

similar to C. crustula. In comparison with C. roeperi, however, the only other 

member of the genus known from the Upper Carboniferous, they are much smaller, 

more tapering, and with strive which are at the same time more distant and are 

sigmoidally curved instead of neai-ly straight. 

_Locality and horizon. San Juan region (station 2239?), upper part of the 

Hermosa formation. Grand Riv[er region, Grand River, 1 mile below Eagle River 

(station 2190). 

ENCHOSTOMA Miller, 1896. 

ENCHOSTOMA sp. 

At a station in the Crested Butte region (station 2313) occurs in considerable 

abundance an organism which I feel little hesitancy in referring to Miller's genus. 

Specimens have the bluish colo- and shining phosphatic surface which are both 

striking and distinctive. In occurrence they are much flattened, and cross the 

surface of the limestone blockS in ribbon-like strips whose edges are parallel. 

No tendency to taper is apparert in the specimens studied, but at the same time 

no specimens of any considerable length have come under my observation. The 

breadth rarely exceeds 3.5 mm., d sometimes measures but 2 mm. 

Miller believes these organisms to be the remains of mollusks and allied to the 

Conulariidw. Whatever be the nities of Con,ularia, I am convinced that those of 

Enchostoma are with the polych tous annelids. The tube, which is the only portion of thd organism yet discove4ed, affords but a slender support for a conclusion 

upon this point, but a suggestive resemblance, if no more, can be pointed out 

between the Paleozoic shells under discussion and the living genus Hyalinacea. The 

latter inhabits a smooth, gently t pering, incomplete, cylindrical tube, composed of 

chitinous material, from which hat of Ench,ostoma differs chiefly in being more 

massive and made up of phospha e of lime ( ?) in concentric laminve. 

Locality and horizon,.—Crest d Butte district (station 2313); Weber limestone. 

SPIRORBIS Lamarck, 1801. 

SPIRORBIS ARIETINA Dawson. 

1871. 	Spirorbis arietina. Dawson, Geol. Surv. Canada, Rept. Prog., 1866-1869, p. 14, fig. —. 

Carboniferous: Near New Glasgoi-, Nova Scotia. 

The Colorado shells referre to 8pirorbis arietina attain a rather large size for 

the genus. They are sinistral, a d composed of four or five turns, the first two or 

three of which are in contact, forming a rather high spire with a broad, deep 
334 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

umbilicus, and the last one or two free and irregularly bent. The cross section is 

circular. The surface seems to be marked with regular, very fine, transverse 

strim, and toward the aperture by a few irregular, transverse wrinkles. Wellpreserved surfaces are also seen to be, minutely papillose, or occasionally appear as 

if the crests of the striae were minutely crenulate. 

The data thus briefly set down are derived largely from the material from 

station 2311. Though specimens occur more abundantly at station 2310, the preservation is much less satisfactory. Nevertheless the species is believed to be the same 

at both. 

My material, while attaining a somewhat greater size than that shown by 

Dawson's figure of Spirorbis arietina, agrees with that species in so many particulars 

as to lead me to believe that if not actually identical with it, it is at least very closely 

related. 

This form differs from that occurring at Glenwood Springs in being larger and 

in appearing to lack the longitudinal strive -of that species. The latter is also closecoiled throughout and the final portion is not free as in Sp. arietina. At the same time 

I am not sure that an abundance of good material would show that they are distinct. 

Locality and horizon.—Crested Butte district (stations 2310, 2311); Maroon 

formation. 

SPIRORBIS sp. 

This form occurs in abundance at Glenwood Springs, and in an excellent state of 

preservation. It forms small, rather regularly conical sinistral shells, consisting of 

two or three volutions and having a moderately high spire. The larger. specimens 

have a diameter of 2 mm. The surface is crossed by numerous delicate transverse 

striae, and also by fine, wavy, probably inosculating, revolving ones. The tube shows 

additional irregularities, chiefly of a concentric kind, due to growth. The surface 

ornamentation, though minute, is very pretty and very well shown. 

This form is probably distinct from that referred to Sp. arietina. It is as a rule 

considerably smaller, and specimens of the latter seem to lack the surface markings 

of this one, though not being so well preserved that character may have been obscured 

in them. 

Locality.—Grand River region, Glenwood Springs (station 2193). 

BRYOZOA. 

FISTULIPORA McCoy, 1849. 

FISTULIPORA CARBONARIA Ulrich. 

1884. Fistulipora carbonaria. Ulrich, Jour. Cincinnati Soc. Nat. fist., vol. 7, p. 45, pl. 3, figs. 1, la. 

Upper Coal Measures: Kansas City, Mo. 

1895. Fistulipora carbonaria. Keyes, Missouri Geol. Surv., vol. 5, p. 16. (Date of imprint 1894.) 

Upper Coal Measures: Kansas City, Mo. 
DESCRIPTIONS OF SPECIES. 335 

This species is represented by a zoarium which had an irregular shape and a 

submassive growth. The thickness is about 12 mm. and the greatest diameter 

26 mm. Ulrich's description and figures, which I will not quote here, so closely 

represent the c aracters of m specimen as I have made them out, that the I y identification is offe ed with some confidence. 

Locality and horizon.—San Juan region (stations 2207, 2213); upper and lower 

portions of the Hermosa formaton. 

STE OPORA Lonsdale, 1844. 

STENOPORA CARBONARIA Worthen. 

1875. Chwtetes? carbonaria. Worthen, Geol. Surv. Illinois, Rept., vol. 6, p. 526, pl. 32, fig. 5. 

Coal Measures: St. Clair County, Ill. 

1887. Stenopora carbonaria. Foerste, ,ci. Lab. Denison Univ., Bull., vol. 2, p. 85, pl. 7, figs. 13a-c. 

Coal Measures: Bald Hill and Flint Ridge, Ohio. 

1888. Stenopora carbonaria. Foerste, Sci. Lab. Denison Univ., Bull., vol. 3, pl. 8, figs. 13a-c. 

1890. Stenopora carbonaria. Ulrich, 0-eol. Surv. Illinois, Rept., vol. 8, p. 445, pl. 73, figs. 8, 8a. 

Coal Measures: Caseyville, Ill.; ;Lawrence, Kans.; Ohio. 

Two specimens of this form have come to hand. They seem to belong to the 

well known Stenopora carbonaria. 

Locality and horizon.—San Juan region (station 2213); lower portion of the 

Hermosa formation. 

STENOPORA CESTRIENSIS 

1890. Stenopora censtriensis. Ulrich, qeol. Surv. Illinois, Rept., vol. 8, p. 442, pl. 74, figs. 7, 7a. 

Chester group: Chester, Ill. 

1895. Stenopora cestriensis. Keyes, Missouri Geol. Surv., vol. 5, p. 16. (Date of imprint 1894.) 

Kaskaskia limestone: Chester, Ill. 

This species is represented by two specimens in a fairly good state of preservation. They agree with Ulrich's description of St. cestriensis and differ from the 

related form, St. tuberculatus, n the characters pointed out by him, viz, "the cells 

are smaller, their individual alts more clearly defined; the acanthopores more 

conspicuous, and the zooecial 1 yers at least twice as thick." 

Locality.---Leadville distri t (station 2265). 

STEN FORA TTJBERCULATA Prout. 

1859. Flustra tuberculata. Prout, Auld. Sci. St. Louis, Trans., vol. 1, p. 447, pl. 17, figs. 3-3f. 

Second Archimedes limestone: Barrett Station, St. Louis County, Mo. 

1860. Cyclopora polymorpha. Prout, cad. Sci. St. Louis, Trans., vol. 1, p. 578. 

Chester limestone: Pope Count, Ill. 

1866. Oyclopora polymorpha. Prout,. Geol. Surv. Illinois, Rept., vol. 2, p. 421, pl. 21, figs. 5-5b. 

Chester group: Pope County, Ill. 
336 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1890. Stenopora tuberculata. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 441, fig. 17. 

Chester group: Chester, Ill. 

St. Louis limestone and Warsaw beds. 

1895. Stenopora tuberculata. Keyes, Missouri Geol. Surv., vol. 5, p. 15. (Date of imprint 1894.) 

St. Louis limestone: Barrett Station, Mo. 

Kaskaskia limestone: Chester, Ill. 

This form is represented by two excellent specimens. They agree very closely 

with Ulrich's description of Prout's species, and although the latter is especially abundant in and characteristic of rocks of the Genevieve epoch, and the present material seems to be of Upper Carboniferous age, they probably can safely be referred 

to the same species. 

_Locality and Horizon.—Crested Butte district (station 2312); Weber limestone. 

STENOPORA 2 sp. 

are probably at least generically distinct. 

clerna 2 

The shape of the zoarium is discoid, almost flat, more or less flexuous. DiameAssociated with the form which I have distinguished under the title of 

sp. occur two other zoaria of a general appearance closely similar, but which 

Leioter about 10 mm., thickness inconsiderable. Mesopores practically absent. Autopores small, angular, 6 or 8 in a space of 2 mm. Walls thin. Acanthopores 

probably present. Diaphragms probably absent. 

Though in general appearance similar to Leioclema 2 sp. with which this form 

is associated, it can be distinguished without difficulty by reason of its much smaller 

cells and practical absence of mesopores. 

Locality and horizon..—San Juan region (station 22211; upper portion of the 

Hermosa formation. 

LEIOCLEMA Ulrich, 1882. 

LEIOCLEMA 2 sp. 

At station 2221 in the San Jaan region occurs in considerable abundance a form 

of whose generic position I am much in doubt, but which I have placed provisionally 

with Leioclerna. The zoaria are small and extremely thin. The shape is that of a 

disk, slightly depressed in the center and more or less flexuous. The diameter is 

usually under 12 mm. and the thickness inappreciable. The cells are minute, subcircular or petaloid in shape, and separated by abundant mesopores, which have an 

angular outline. They radiate in an almost horizontal position from the center of 

the colony. Acanthopores seem to be absent, and the height of the zocecia is so 

slight as to suggest that diaphragms also are lacking. Certainly none have been seen. 

Locality and horizon.—San Juan region (station 2221); upper portion of the 

Hermosa formation. 
DESCRIPTIONS OF SPECIES. 337 

CHAINODICTYON Foerste, 1887. 

CHAINODICTYON LAXUM Foerste. 

1887. Chainodictyon laxum. Foerste, Sci. Lab. Denison Univ., Bull., vol. 2, pp. 81 and 87, pl. 7, figs. 

8a—c. 

Coal Measures: Flint Ridge, Ohio; Seville, Ill. 

1888. Chainodictyon laxum. Foerste, Sci. Lab. Denison Univ., Bull., vol. 3, p. 135. 

A poorly preserved fragment is all that we have of this strongly characterized 

species, but its affinities are probably as stated above. 

Locality and horizon.-2---San Juan region (station 2332); middle portion of the 

Hermosa formation. 

SEPTOPORA Prout, 1859. 

SEPTOPORA DELICATULA Ulrich. 

1890. Septopora delicatula. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 634, pl. 64, figs. 5, 5a. 

Lower Coal Measures: Seville, Ill. 

This species is represented by very fragmentary and scanty material, but tau 

identification is probably correct. 

Locaity.L—Leadville district (station 2265). 

SEPTOPORA sp. 

A single very imperfect specimen of this species has come to hand. It is specifically distinct from the form noticed above, and is possibly related to S. cestriensis 

Prout. 

Locality and horizon.—San Juan region (station 2207); upper portion of the 

Hermosa formation. 

POLYPORA McCoy, 1845. 

POLYPORA WHITEI var. INSCULPTA Ulrich. 

1889. Polypora whitei var. eximia (in error for insculpta). Miller's North American Geol. and Pal., 

317 

1890. Polypora whitei var. insculpta. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 600, pl. 62, fig. 1. 

Upper Coal Measures: Springfield, Ill. 

At station 2331 on the Animas River in the San Juan region, a prolific locality 

for Bryozoa, was obtained a small fragment of a Polypora whose characters, so far 

as they are shown, ally it closely to P. whitei var. insculpta. A form which is 

possibly identical with that from the San Juan occurs in the • Leadville region at 

station 2265. 

Locality and horizon.—San Juan region (station 2331); Hermosa formation. 

Leadville district (station 2265). 

14364—No. 16-03 22 
338 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

POLYPORA cf. DISTINCTA Ulrich. 

1890. 	Polypora distincta. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 603, pl. 61, figs. 7, 7a. 

Upper Coal Measures: Springfield, Ill. 

This is a rather coarse form, characterized by somewhat lax and irregular growth. 

The branches are strong, and connected by dissepiments which are slender, short, 

and situated at distant intervals. The zocecia are arranged in four, possibly in five, 

longitudinal rows. Their apertures have eleyated margins and they manifest a 

certain tendency toward, or appearance of, dimorphism, for, scattered among the 

regular zooecia, are a number of others which are often *of smaller size, or, when 

equal, seem by their proximity to them to be arranged in groups of two. The nonporiferous side has not been seen. 

This form is not identical with P. distincta but is probably no more than a 

variety. It is also allied to P. gracilis Ulrich. 

Locality.—Leadville district (station 2265). 

POLYPORA cf. CESTRIENSIS Ulrich. 

1890. Polypora cestriensis. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 594, pl. 55, figs. 4-4b; pl. 60, 

figs. 7-7c. 

Chester group: Chester, Kaskaskia, and near Anna, Ill.; Litchfield and Sloans Valley, 

Kentucky. 

1895. Polypora cestriensis. Keyes, Missouri Geol. Surv., vol. 5, p. 29. (Date of imprint, 1894.) 

Kaskaskia limestone: Ste. Genevieve, Mo. 

This is a coarsely reticulated form with elongate elliptical fenestrules. The 

zocecia are in four rows. The nonporiferous side is ornamented with sharp but 

rather fine longitudinal striae. The poriferous side also is marked by ridges which 

pass between the zocecia and in some degree define them. 

Locality and horizon.—San Juan region (station 2331); Hermosa formation. 

POLYPORA n. sp. 

This form is represented by a fragment of a frond from the Leadville region, 

and by two fragments, each from a different locality in the San Juan region, which 

probably belong to the same species. My material is too fragmentary and ill preserved to permit a detailed description of what is probably a new species. 

The frond is rather coarsely reticulate with thick branches and short, thin dissepiments. The fenestrules are elongate elliptical. The branches are carinated on 

the nonporiferous side and marked by moderately fine, sharp strias. The zocecia 

are in three or four rows and their apertures have elevated margins. 

Locality and horizon.—San Juan region (stations 2331 ?, 2332); middle portion 

of the Hermosa formation. Leadville district (station 2268). 
DESCRIPTIONS OF SPECIES. 339 

POLYPORA sp. a. 

This species occurs associated with that provisionally identified as P. cestriensis 

Ulrich. It resembles the latter in many particulars, the chief difference which the 

scanty and imperfect material exhibits being that the unidentified form is distinctly 

more finely reticulated. As in P. cestriensis, there are four rows of zocecia, and the 

nonporiferous side is marked with sharp, fine striw. 

Locality. and horizon.—San Juan region (station 2331); Hermosa formation. 

POLYPORA sp. b. 

Another undetermined species of Poly_pora is found at station 2235 in the San 

Juan region. The frond is rather rapidly enlarging, the branches thick, the dissepiments thin and long. The fenestrules are nearly square or subcircular. The only 

specimen observed shows the poriferous side where the zocecia are seen to be 

arranged in about four rows. 

Locality and horizon.—San Juan region ( tations 2205, 2235); middle portion 

of the Hermosa formation. 

FENESTELLA Lon dale, 1839. 

FENESTELLA cf. TEN x Ulrich. 

1888. Fenestella tenax. Ulrich, Sci. Lab. Denison Univ., 11., vol. 4, p. 71. 

Waverly group: Cuyahoga County, Ohio. 

1890. Fenestella tenax. Ulrich, Geol. Surv. Illinois, Rept , vol. 8, p. 546, pl. 51, figs. 2-2e. 

Warsaw beds: Monroe County and Warsaw, Ill. 

Chester group: Chester and Kaskaskia, 111.; Sloan Valley, Ky. 

1895. Fenestella tenax. Keyes, Missouri Geol. Surv., vol. 5, p. 24. (Date of imprint, 1894.) 

Kaskaskia limestone: Chester, Ill. 

This species is already credited with a long range, since it is found from 

the Waverly group into the Chester, and t is will be considerably increased if 

the present identification proves correct, as s not unlikely. This form presents 

a very fine, regular network, in which the issepiments are more slender than 

the branches. The latter are marked by co paratively strong, sharp, flexuous, 

longitudinal striae. There are about five zo cia opposite two fenestrules, which 

are subrectangular upon the nonporiferous sid and elliptical upon the other. 

Locality and horizon.—San Juan region (s ation 2331); Hermosa formation. 

FENESTELL sp. 

This form, which is probably the same the San Juan and Leadville regions 

(stations 2221 and 2265, respectively), is indet rminable from the material in hand. 

It differs from that briefly described as tenax in having the fenestrules 

nearly square or subcircular, the dissepim nts thicker, and the nonporiferous 
340 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

face granulose instead of striated. These observations are based entirely upon 

the Leadville specimen. 

Locality and horizon.—San Juan region (station 2221); upper portion of the 

Hermosa formation. Leadville district (station 2265). 

PRISMOPORA Hall, 1881. 

PRISMOPORA TRIANGULATA White. 

Pl. I, fig. 5. 

1878. Ptilodictia triangulata. White, Acad. Nat. Sci. Philadelphia, Proc., p. 35. 

Coal Measures: Danville, Ill. 

1879. Ptilodictia triangulata. White, U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, p. 214. 

Carboniferous: Yampa Plateau, northwestern Colorado. 

1880. Ptilodictia triangulata. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, 

pt. 1, p. 131, pl. 33, figs. 3a-c. 

Coal Measures: Danville, Ill.; Yampa Plateau, northwestern Colorado; and region southward 

from Yellowstone National Park. 

1881. Ptilodictia triangulata. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., 

Appendix, p. xxiv, pl. 4, figs. 2a-c. 

Carboniferous: Cebolla Creek and Coyote Creek, New Mexico. 

White described this species from Danville, Ill., in 1878, and the year following 

published an identification, with comments and figures, from the Yampa Plateau, in 

northwestern Colorado. Although specimens belonging to the genus Prismopora 

appear in our collections from several stations, those identified by White are the 

only ones which I have placed with Pr. triangulata, and his figures, drawn from 

a Colorado specimen, have been used to illustrate the species. 

The illustration on Pl. I represents the specimen as somewhat enlarged. The 

real size of the branches between the nodes varies from 2 to 1.5 mm. 

Locality and horizon.—Uinta Mountain region, Yampa Plateau (station 2330) ; 

middle division of the Carboniferous. 

PRISMOPORA SERRATA Meek. 

1875. Ptilodictya (Stictopora) serrata. Meek, Pal. Ohio, vol. 2, p. 327, pl. 20, fig. 4. 

Lower Coal Measures: Flint Ridge, Ohio. 

1887. Prismopora serrata. Foerste, Sci. Lab. Denison Univ., Bull., vol. 2, p. 75, pl. 7, figs. 6a-c. 

Coal Measures: Bald Hill and Flint Ridge, Ohio. 

This species occurs in some abundance near Rock Creek (station 2245) and in 

the San Juan region (station 2331), and a single fragmentary specimen has also been 

collected at Rico (station 2301). The edges are often flexuous, but sometimes 

nearly straight. The branches are of larger size than the specimen by which 

Pr. triangulata is represented. The zoomia are small and evenly distributed. 

Locality and horizon.—San Juan region (stations 2301, 2331); middle part of the 

Hermosa formation. Crested Butte district (station 2245). 
DESCRIPTIONS OF SPECIES. 341 

PRISMOPORA P. 

This form probably belongs to a yet und: scribed species, but it is represented, 

unfortunately, by only extremely imperfect m. terial. The branches are larger than 

in Pr. triangulata, the zocecia larger and mor • closely arranged. It resembles Pr. 

serrates in the size of its branches, but has the ocecia a little larger and considerably 

more closely arranged. 

Locality and horizon.—San Juan region (station 2236) ; middle portion of the 

Hermosa formation. 

RHOMBOPORA eek, 1872. 

RHOMBOPORA LEPIDODE DROIDES Meek. 

1866. Stenopora columnaris (pars). Geinitz, Carb. und Dyas in Nebraska, p. 66. (Not Schlotheim, 

1813. ) 

Upper Coal Measures: Nebraska City, Bennetts, nd Wyoming, Nebr. 

1872. Rhombopora lepidodendroides. Meek, U. S. Geol. Surv. Nebraska, p. 141, pl. 7, figs. 2a-f. 

Upper Coal Measures: Nebraska City, Bennet I:, Wyoming, Rock Bluff, and Plattsmouth, 

Nebr.; Kansas; Iowa; Missouri; Illinois. 

1875. Rhombopora lepidodendroides. White, U. S. Geo . Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 

99, pl. 6, figs. 5a-d. (Whole volume publishe o in 1877.) 

Carboniferous: West face of Oquirrh Range, n r "E. T. City," Utah, and at confluence of 

White Mountain and Black rivers, Arizona. 

1884. Rhombopora lepfdodendroidea. Ulrich, Jour. •incinnati Soc. Nat. Hist., vol. 7, p. 27, pl. 1, 

figs. 1-1b. 

Upper Coal Measures: Kansas City, Mo.; Nebraska City and Wyoming, Nebr. 

1887. Rhombopora lepidodendroidea. Foerste, Sci. La.. Denison Univ., Bull., vol. 2, p. 73, pl. 7, 

figs. 3a, b. 

Coal Measures: Flint Ridge and Bald Hill, Ohio 

1887. Rhombopora . Foerste, Sci. Lab. Denison Univ., Bull., vol. 2, p. 74, p1. 7, figs. 5a-c. 

Coal Measures: Flint Ridge, Ohio. 

1888. Rhombopora lepidodendroides. Keyes, Acad. Na . Sci. Philadelphia, Proc., p. 225. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Rhombopora lepidodendroidea. Keyes, Missouri Geol. Surv., vol. 5, p. 35, p1. 33, figs. 4a, b.. 

(Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1896. Rhom,bopora lepidodendroides. Smith, Am. Phil. Soc., Proc., vol. 35, p. 237. 

Upper Coal Measures: Poteau Mountain, India Territory. 

1896. Rhombopora lepidodendroides. ,Smith, Leland S nford Junior Univ., Pub.; Cont. Biol. Hopkins 

Seaside Lab., No. 9, p. 27. 

Upper Coal Measures: Poteau Mountain, India • Territory. 

This name, as I have used it here and as t has often been employed in literature, 

probably stands rather for a group of for s than for a single consistent species. 

To reduce to proper scientific status the col ections from Colorado, and much more 
342 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

the citations in literature, would be a task of difficulty even if it could be accomplished at all in an acceptable manner without more abundant and better preserved 

material than most of that which has come into my hands. 

.R/wrnbopora le_piclodendroides is very abundant at station 2215 in the San Juan 

region, and it seems to be common also at 2281 in the Leadville region. 

Locality and h,orizon,.—San Juan region (stations 2186, 2215, 2235); Molas formation and middle portion of the Hermosa formation. Leadville district (stations 

2265, 2281); base of the Weber formation. Grand River region (station 2329b). 

Uinta Mountain Region, overlooking Yampa River (station 2191). 

BRACHIOPODA. 

LINGULA Bruguiere, 1792. 

LINGULA CARBONARIA Shumard. 

1858. Lingula carbonaria. Shumard, Acad. Sci. St. Louis, Trans., vol.1, p. 215. 

Coal Measures: Clark County, Mo. 

1873. Lingula mytiloides? Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 572, pl. 25, fig. 2. 

Coal Measures: Illinois. 

1887. Lingula umbonata? Herrick (non Cox), Sci. Lab. Denison Univ., Bull., vol. 2, p. 144, pl. 14, 

fig. 2. 

Coal Measures: Flint Ridge, Ohio. 

1899. Lingula mytiloides? Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 575. 

Upper Coal Measures: Atoka quadrangle, Hartshorne, Ind. Ter.; roof shale of the Grady or 

Hartshorne coal. 

I have only one specimen of this form, and it is too imperfect to be identified with 

certainty. It seems to belong to the type of shell often referred in this country to 

Lingula mytiloides Sowerby. This type differs from Sowerby's figures in being 

smaller and as a rule more quadrate before and behind. It is probable that Shumard's 

Lingula carbonaria was founded upon a shell belonging to this group, for his descripbonaria 

for which 

tion answers to it quite closely. It might be well, therefore, to employ 

racy of published figures, none of the identifications of Cox's species are correct. 

Lingula umbonata? 

for American shells of the 

L. carbonaria 

Herrick (non Cox) is probably another example of the species 

was proposed. Indeed, if one may depend upon the accumytiloides type. 

Lingula carWhite,' Keyes,b and Beede c appear to have had in hand a slender elongate form of a 

shape differing materially from that depicted by Cox's figure. Judging from the 

literature, therefore, I would look to find four species involved—the slender form 

figured by White et al. as L. umbonata, L. umbonata as figured by Cox, L. carbona Geol. Surv. Indiana, Thirteenth Rept., 1884, p. 120, pl. 25, fig. 14. 


b Missouri Geol. Surv., vol. 5, 1894, p. 38, pl. 35, fig 4. 


c Univ. Geol. Surv. Kansas, Rept., vol. 6, 1900, p. 54, pl. 8, fig. 5. 

DESCRIPTIONS OF PECIES. 343 

aria figured by Meek as L. mytiloides, and . tighti Herrick. But the study of 

these forms is most difficult and but little profi ble. 

Locality and horizon.—Leadville district station 2264?); base of the Weber 

formation. 

LINGULA TIGHT' errick. 

1887. Lingula tighti. Herrick, Sci. Lab. Denison Univ., ull., vol. 2, p. 43, pl. 4, fig. 5 

Coal Measures: Flint Ridge, Ohio. 

This species is found at but one locality. t is there-very abundant, though not 

well preserved. The material studied is as a r le much smaller than L. carbonaria, 

which has been identified at another locality in the Leadville area, but the essential 

difference resides in the fact that it is a more sl nder and elongate form, with a shape 

which is rather subelliptical than subquadrat . Most of the material referred to 

this species is also smaller than the specimen figured by Herrick, but one or two 

examples from the same locality and apparentl belonging to the same specific type 

are nearly of normal size. It is possible, ho ever, that we have here only young 

shells of L. carbonaria. 

This species is very abundant in the Ling la bed of station 2227. One peculiarity of the occurrence at this locality is th t in most instances both valves are 

found in conjunction. 

In addition to the material belonging to t e genus Lingula, whose specific identification has been attempted as above, severa occurrences of indeterminable specimens may be noted, e. g., Glenwood Springs, tation 2193a. 

Locality and horizon.—Leadville district station 2277); base of the Weber formation. 

ORBICULOIDEA d' rbigny, 1850. 

ORBICITLOIDEA MANHATTANEN IS Meek and Hayden. 

1859. Discina manhattanensis. Meek and Hayden, Aca . Nat. Sci. Philadelphia, Proc., p. 25. 

Upper Coal Measures: Kansas River, opposite M nhattan, Kans. 

1892. Orbiculoidea manhattanensis. Hall and Clarke, I t. Study of Brach., pt. 1, pl. 5, fig. 12. 

Coal Measures: Riley County, Kans. 

1892. Orbiculoidea manhattanensis. Hall and Clarke, P 1. New York, vol. 8, pt. 1, pl. 4E, fig. 20. 

Coal Measures: Riley County, Kans. 

1900. Orbiculoidea manhattanensis. Beede, Univ. Geol Surv. Kansas, Rept., vol. 6, p. 56, pl. 8, figs. 

2-2b. 

Upper Coal Measures: Wabaunsee formation, bl ck shale in wagon-road cut east side of Blue 

Mount, Manhattan, Kans. 

Of this species but few specimens have r ome to hand, and they are crushed and 

fragmentary. The best preserved example a dorsal valve, affords the following 

data: 

The shape is of course nearly circular, ith a diameter of about 15 millimeters. 
344 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The apex is one-half a diameter or a little more from the margin and the height is 

about 2 millimeters. The surface is marked by sharply elevated, thread-like stria, 

3 or 4 in a distance of 1 millimeter, with flat interspaces. The latter when exfoliated 

show faint, fine, radiating lines. Other specimens show that this species attained a 

diameter considerably exceeding that stated. 

The measurements and other characters mentioned above, though necessarily 

somewhat lacking in accuracy by reason of the imperfect nature of my material, 

indicate that this form is probably that described by Meek and Hayden as Discina 

manhattanensis. 

Locality and horizon.—Leadville district (stations 2252, 2264); base of the 

Weber formation. 

ORBICULOIDEA sp. 

Near Glenwood Springs (station 2193a) a small species of Orbictdoidea occurs in 

considerable abundance. Without intermediate forms I do not feel justified in 

any other known species. It may be briefly described as follows: 

ternensis, 

The apex is one-third of a diameter, or a little less, from the margin, and the height 

referring it to the same species as the shells which I have identified as 

The nearly circular outline has a diameter which rarely exceeds 5 millimeters. 

nor have I been able to satisfy myself that it can properly be referred to 

0. manhatis sometimes as great as 2 millimeters. In the ventral valve the slit is strongly 

marked and reaches from near the center to halfway to the circumference. 

The surface is marked by comparatively strong, somewhat irregular, closely 

arranged, concentric stria. 

Locality.—Grand River region, Glenwood Springs (station 21930 

RHIPIDOMELLA Oehlert, 1887. 

RHIPIDOMELLA PECOSI Marcou. 

1858. February. Orthis pecosii. Marcou, Geol. North America, p. 48, p1. 6, figs. 14-14b. 

Mountain Limestone: Pecos Village, N. Mex. 

1858. June. Orthis carbonaria. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 218. 

Middle Coal Measures: Lexington, Mo. 

1864. Orthis (sp. undet.). Meek, Pal. California, vol. 1, p. 10, p1. 2, figs. 5-5c. 

Carboniferous: Bass's Ranch, Shasta County, Cal. 

1872. 	Orthis carbonaria. Meek, U. S. Geol. Surv. Nebraska, p. 173, pl. 1, figs. 8a-8c. 

Upper Coal Measures: Rock Bluff and Nebraska City, Nebr.; Iowa; Kansas; Illinois. 

Middle Coal Measures: Lexington, Mo. 

1873. Orthis, carbonaria. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 571, pl. 25, fig. 4. 

Upper Coal Measures: Lasalle, Ill. 

1875. Orthis pecosii. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 125, pl. 9, figs. 

5a-5e. ( Volume appeared as a whole in 1877. ) 

Carboniferous: Santa Fe, N. Mex. 
DESCRIPTIONS OF PECIES. 345 

1883. Orthis carbonaria. Hall, Rept. New York State G 1. for 1882, pl. (7) 37, figs. 1-4. 

Coal Measures: Springfield, Ill. 

1883. Orthis pecosi. Kayser, Richtofen's China, vol. 4, p. 177, pl. 24, fig. 1. 

Upper Carboniferous: Lo-Ping, China. 

1884. Orthis pecosii. Waagen, Paleontologica Indica, ser. 13, voi. 1, p. 573, pl. 56, figs. 13a-13e. 

Lower Productus limestone: Salt Range, Amb., In la. 

1884. Orthis pecosi. White, Geol. Surv. Indiana, 13th Re t., p. 129, pl. 32, figs. 20-22. 

Coal Measures: Horse Shoe of Little Vermilion and Garret's Mill, Vermilion County, Ind.; Vermilion County, Ill. 

1892. Rhipidomella pecosi. Hall and Clarke, Pal. New Yo k, vol. 8, pt. 1, pp. 210, 226, pl. 7, figs. 1-4. 

Coal Measures: Near Springfield, Ill. • 

1895. Orthis pecosii. Keyes, Missouri Geol. Surv., vol. 5, 64. (Date of imprint, 1894.) 

Coal Measures: Kansas City, Mo. 

1896. Orthis pecosii. Smith, Am. Phil. Soc., Proc., vol. , p. 237. 

Upper Coal Measures: Poteau Mountain, Ind. T. 

1900. Rhipidomella pecosi. Beede, Univ. Geol. Surv. Kan , Rept., vol. 6, p. 90. 

Upper and Lower Coal Measures: Fort Scott, Kans. City, Eudora, Lawrence, Lecompton, Kans. 

My material is, as a rule, rare and not wel preserved, but the species has been 

obtained from near Glenwood Springs (station 2 29b) in fair abundance and preservation. Specimens attain a size greater, somewh t, than that figured by Marcou, and 

a length of 14 millimeters seems to be about n rmal for the specimens seen by me, 

which agree in this and other particulars, so far as I have been able to ascertain, 

with the species as it is represented in 'the Miss ssippi. Valley. 

A very poor specimen from Leadville (stat on 2259), which seems to have been 

originally identified as Derbya crassa, probably belongs to this species. 

Locality and horizon.—Leadville district (st tions 2259, 2264); base of the Weber 

formation. Grand River region, Glenwood springs (station 2329b). San Juan 

region (2186?); Molas formation. 

ORTHOTICHIA Hall an Clarke, 1892. 

ORTHOTICHIA SCHUCHE TENSES n. sp. 

Pl. I, figs. 16 to 6b. 

Shell of medium size, transverse. Dorsa valve strongly convex; beak large 

and incurved; area small (?); fold broad and s arcely appreciable; anterior outline 

emarginate. 

Ventral valve smaller and shallower than the dorsal; beak probably incurved 

and not quite as projecting as the other; sinus broad and strong, especially toward 

the front. This valve is provided with a rat er thick, but not very high, median 

septum reaching about one-third the distance t ward the anterior margin, and by a 

pair of strong dental 

The surface is marked by very slender, qual, radiating stri.ae and by much 

stronger ones regularly distributed among the . The latter are discontinuous and 
346 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

outlined by such deep grooves that they appear to be depressed below the general 

surface. This peculiarity is stronger upon the ventral valve than on the dorsal, 

where it appears upon the lateral areas, but scarcely at all over the median portion. 

There is but one other species of this genus known from the Western Hemisphere, 

the South American form, Orthotichia morganiana. To this my species is related, 

but I feel no doubt as to their being specifically distinct. The fold and sinus of 

0. morganiana I take to be less strongly marked, and the surface, as shown by 

specimens in my possession, is distinctly different. It shows a feature common to 

many species of Orthoids, consisting of individual striae somewhat more prominent 

than the rest, terminating abruptly and running out into a small spine, but does not 

possess the heavy, short, depressed strias which probably are to be associated with a 

similar origin, but which form such an unusual character of my shell. 

The species described by Cox as Orthis resu_pinoides has much the same configuration as the Colorado form, but seems to lack the peculiarities of its surface 

ornamentation, besides which Hall and Clarke refer Cox's species to the genus 

Sehizophoria, so that further comparisons of course are unnecessary. 

I know of no other species with which this is likely to be confused. 

A single small specimen from Sinbads Valley has been referred to the same 

species as that from Glenwood Springs (though it may be merely a young example 

of En,teletes), and it discloses 'characters of the area which were concealed in the 

material from the type locality. In this example, which has a length of but 14 millimeters (the type is 26 millimeters long), the beaks of the two valves are about on a 

level when the shell is looked at from the side. The area of the dorsal valve in this 

position is nearly vertical; that of the ventral starts out in a nearly horizontal direction. The areas of both valves are small, slightly curved, and contain large, open, 

triangular foramina. That of the ventral valve is higher and more strongly curved 

than is that of the dorsal. 

_Locality and horizon.—Grand River region, Glenwood Springs (station 2193a). 

Dolores River region, Sinbads Valley (station 2285); top of the Hermosa formation. 

ENTELETES Fischer de Waldheim, 1830. 

ENTELETES HEMIPLICATITS Hall. 

1852 Spirifer hemiplicata. Hall, Stansbury's Exped. to Great Salt Lake, p. 409, pl. 4, figs. 3a, b. 

Carboniferous: Missouri River, near Weston. 

1859. Spirifer hemiplicata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 28. 

Upper Coal Measures: Near Leavenworth, Kans. 

1866. Rhynchonella angulata. Geinitz (non Linne), Carb. and Dyas in Nebraska, p. 37, tab. 3, figs. 1-4. 

Upper Coal Measures: Bennett's Mill and Nebraska City, Nebr. 

1866. Syntrielasma hemiplicata. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 323, fig. 36; 

p. 324, fig. 37. 

Upper Coal Measures: 12 miles north of Vandalia, Ill.; eastern Kansas, northern Missouri, 

western Iowa. 
DESCRIPTIONS OF SPECIES. 347 

1872. Syntrielasma hemiplicata. Meek, U. S. Geol. Surv. Nebraska, p. 177, pl. 6, figs. la, b; pl. 8, figs. 

12a, b. 


Upper Coal Measures:. Nebraska City, Wyo., and Bennett's Mill, Nebr. 


Coal Measures: Illinois, Iowa, Missouri, Kansas. 


1873. Syntrielasma hemiplicata. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 571, pl. 26, 

fig. 20. 

Upper Coal Measures: 12 miles north of Vandalia, Ill. 

1882. Camerophoria giffordi. Worthen, Illinois State Mus. Nat. Hist., Bull. No. 1, p. 39. 

Middle Coal Measures: Near Alta, Peoria County, Ill. 

1883. Camerophoria gitiordi. Worthen, Geol. Surv. Illinois, Rept., vol. 7, p. 318, figs. a-c. 

Middle Coal Measures: Near Alta, Peoria County, Ill. 

1883. Syntrielasma hemiplicata. Kayser, Richtofen's China, vol. 4, p. 179, pl. 24, figs. 2, 3. 

Upper Carboniferous: Lo-Ping, China. 

1884. Syntrielasma hemiplicata. White, Geol. Surv. Indiana, 13th Rept., p. 131, pl. 26, figs. 15-18. 

Coal Measures: Indiana. 

1892. Enteletes hemiplicata. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 12, figs. 18-21. 

Coal Measures: Winterset, Iowa; Kansas City, Mo. 

1892. Enteletes hemiplicata. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pp. 215, 226, pl. 7A, figs. 44-52; 

Upper Coal Measures: Kansas City, Mo.; Winterset, Iowa. 

1895. Syntrielasma hemiplicata. Keyes, Missouri Geol. Surv., vol. 5, p. 76, pl. 39, figs. 8a-d. (Date of 

imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1900. Enteletes hemiplicata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 91, pl. 12, figs. 6, 6b. 

Upper Coal Measures: Kansas City, Independence, Iola, Edwardsville, Eudora, Lawrence, 

Lecompton, Topeka, Kans. 

Though not occurring elsewhere in our Colorado collections, this species is found 

in considerable abundance at Sinbads Valley (station 2285). The specimens are 

badly crushed, but appear to be typical in every way. 

Locality and horizon,.--Dolores River region, Sinbads Valley (station 2285); 

top of the Hermosa formation. 

DERBYA Waagen, 1884. 

DERBYA CRASSA Meek and Hayden. 

1852. Orthis umbraculum I Hall, Stansb. Exped. Great Salt Lake, p. 412, pl. 3, fig. 6. 

Carboniferous: Missouri River, above Fort Leavenworth. 

1852. Orthis umbraculum f Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 5, fig. 11. 

Carboniferous: Missouri River, near mouth of Keg Creek, and at Council Bluffs. 

1852. Orthis arachnoidea. Roemer (non Phillips), Kreid. von Texas, p. 89, pl. 11, figs. 9a, b. 

Carboniferous: San Saba Valley, Tex. 

1857. Orthis arachnoidea. Hall, Mexican Boundary Survey, pl. 20, fig. 3. 

1858. Orthisina crassa. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 261. 

Coal Measures: Leavenworth, Kans. 

1858. Orthis crenistria. Marcou, Geol. North America, p. 49. 

Mountain limestone: Pecos Village, New Mexico. 

1859. Orthisina crassa. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Coal Meaaures: Leavenworth, Ksns. 
348 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1859. Orthisina umbraculum? Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Fort Riley and Cottonwood Creek, Kans. 

1860. Orthis lasallensis. McChesney, Desc. New Pal. Foss., p. 32. 

Upper Coal Measures: Lasalle, Ill. 

1860. Orthis richmonda. McChesney, Desc. New Spec. Pal. Foss., p. 32. 

Coal Measures: Twelve miles northwest of Richmond, Mo. 

1860. Orthis pratteni. McChesney, Desc. New Spec. Pal. Foss., p. 32. 

Coal Measures: Charboniere, Mo. 

1861. Streptorhynchus umbraculum. Newberry, Ives's Colorado River Expl. Exped., p. 125. 

Upper Carboniferous (Cherty limestone): Canyon of Cascade River near the junction of the 

Colorado Chiquito with the Colorado; at Agua Azul; east of Fort Defiance; at Santa Fe; at 

Ojo Vernal, and on Cottonwood Creek, Kansas. 

1864. Hemipronites crassus. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, p. 26, 

pl. 1, figs. 7a-d. 

Coa Measures: Leavenworth, Kans. 

1865. Orthis richmondi. McChesney, Illustrations New Spec. Foss., pl. 1, figs. 5a-c. 

1865. Orthis lasallensis. McChesney, Illustrations New Spec. FcAs., pl. 1, figs. 6a, b. 

1866. Orthis crenistria. Geinitz (non Phillips), Carb. and Dyas in Nebraska, p. 46, pl. 3, figs. 20, 21. 

Upper Coal Measures: Bellevue and Plattsmouth, Nebr.; Stage Bb, at Bennett's mill, southwest 

of Nebraska City; Stages VP', Cc", Ccv, at Nebraska City. 

1868. Hemipronites crassus. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 28, pl. 1, figs. 5a-c. 

Coal Measures: 12 miles northeast of Richmond, Mo. 

1868. Hemipronites lasallensis. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 28, pl. 1, figs. 6a, b. 

Upper Coal Measures: Lasalle, Ill. 

1872. Hemipronites crassus. Meek, U. S. Geol. Surv. Nebraska, p. 174, pl. 5, figs. 10a-c; pl. 8, fig. 1. 

Upper Coal Measures: Nebraska City, Bennett's Mill, Wyo.; Cedar Bluff, Rock Bluff, Plattsmouth, Bellevue, Omaha, Peru, Rulo, and Brownsville, Nebr. 

Coal Measures: Kansas; Iowa; Missouri; Illinois. 

Chester limestone: West Virginia. 

1873. Hemipronites crassus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 570, pl. 25, fig. 12. 

Upper Coal Measures: Lasalle, Ill. 

1875. Hemipronites crenistria. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 124, pl. 

10, fig. 9a. ( Whole volume published in 1879.) 

Carboniferous: Meadow Creek, south of Fillmore; Star District, Picacho Range; North Fork of 

Lewiston Canyon, Oquirrh Range; below Ophir City, Kanab Canyon, Wasatch Range; pass 

between Rush and Cedar valleys; and east side of Mount Nebo, Utah; top of Grass Mountain, 

Ely Range; Fossil Hill; Camp Apache; Old Potosi Mine; Tenney's ranch; Kaibab Plateau; 

and at confluence of White Mountain and Black rivers, Nevada. 

1876. Hemipronites crenistria. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey Group: Near Echo Park, and at confluence of Grand and Green Rivers, Utah. 

Upper Aubrey Group: Beehive Point, near Horseshoe Canyon, Utah. 

1883. Streptorhynchus richmondi. Hall, Rept. New York State Geol. for 1882, pl. (10) 40, figs. 10, 11. 

Coal Measures: Iowa. 

1884. Hemipronites crassus. White, Geol. Surv. Indiana, 13th Rept., p. 129, pl. 26, figs. 4-11. 

Coal Measures: Lodi, Eugene, Perrysville, Merom, Big Creek, and New Harmony, Ind. 
DESCRIPTIONS OF SPECIES. 349 

1884. Derbyia crassa. Waagen, Palwontologia Indica, ser. 13, vol. 1, p. 592. 

1887. Hemipronites crassus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 50, pl. 2, fig. 19. 

Coal Measures: Flint Ridge, Ohio. 

1888. Streptorhynchus crenistria. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 229. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Streptorhynchus crassum. Whitfield, New York Acad. Sci., Ann., vol. 5, p. 580, pl. 13, figs. 

11, 12. 

Maxville limestone: Ohio. 

1892. Derbya crassa. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 17, figs. 1-4, 9. 

Upper Coal Measures: Kansas City, Mo.; Winterset, Iowa. 

1892. Derbya crassa. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 10,figs. 10, 11; pl. 11A, figs. 

28-33; pl. 11B, figs. 23, 24; pl. 20, figs. 12, 13. 

Upper Coal Measures: Near Kansas City, Mo., and Winterset, Iowa. 

1893. Streptorhynchus crassum. Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 468, pl. 9, figs. 11, 12. 

Maxville limestone: Ohio. 

1895. Streptorhynchus crenistria. Keyes, Missouri Geol. Surv., vol. 5, p. 67, pl. 38, figs. 8a-h. (Date 

of imprint 1894. ) 

Coal Measures: Kansas City, Clinton, and Lexington, Mo. 

1896. Derbya crassa. Smith, Leland Stanford Junior Univ. Pub.; Cont. Biol. Hopkins Seaside Lab., 

No. 9, p. 28. 


Upper Coal Measures: •Poteau Mountain, Indian Territory. 


Lower Coal Measures: Conway County, Ark. 


1896. 	Derbya crassa. Smith, Am. Phil. Soc., Proc., vol. 35, p. 238. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

Lower Coal Measures: Conway County, Ark. 

1900. 	Derbya crassa. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 62, pl. 8, figs. 11, 11b. 

Upper and Lower Coal Measures: Fort Scott, Kansas City, Lawrence, Topeka, Kans. 

This species appears in our collections at many localities, but it is usually rather 

rare. Though abundant in the Crested Butte region (stations 2307 and 2320), at 

Glenwood Springs (2193a), and at Ouray (2195a), it is somewhat crushed and poorly 

preserved. Specifically it agrees with the Mississippi Valley variety in every 

essential. 

The material from Leadville is both scanty and poor, and the identification in 

one or two cases may not be correct. 

_Locality and horizon.-San Juan region (stations 2197, 2203, 2219, 2220, 2233, 

2246, 2247, 2284, 2332); throughout the Hermosa formation. Crested Butte district 

(stations 2280, 2293, 2303, 2307, 2320); Weber limestone and Maroon formation. 

Leadville district (stations 2250, 2252, 2265, 2275); upper and lower portions of the 

Weber formation. Ouray (station 2195a); Hermosa formation. Grand River region, 

Glenwood Springs (station 2193a). 
350 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

MEEKELLA White and St. John, 1868. 

MEEKELLA STRIATICOSTATA COX. 

1857. Plicatula striato-costata. Cox, Owen's Geol. Surv. Kentucky, Rept., vol. 3, p. 568, pl. 8, fig. 7. 

Coal Measures: Providence, Hopkins County, Ky. 

? 1858. Orthisina shumardiana. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 183. 

Lower Permian: Valley of Cottonwood, Kans. 

1858. Orthisina missouriensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 219. 

Upper Coal Measures: Dallas, Mo.; Kansas. 

? 1859. Orthisina shumardiana. Meek and Hay(len, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Fort Riley, Kans. 

1859. Orthisina missouriensis. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Leavenworth, Kans. 

? 1859. Streptorhynchus (Orthisina) shumardianus. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 395. 

Permian sandstone: Guadalupe Mountains. 

? 1863. Orthisina occidentalis. Swallow, Acad. Sci. St. Louis, Trans., vol. 2, p. 82. 

Upper Coal Measures: Caldwell County, Mo. 

1866. Orthis striato-costata. Geinitz, Carb. and Dyas in Nebraska, p. 48, Tab. 3, figs. 22-24. 

Upper Coal Measures: Crescent City, Iowa. 

1868. Meekella striato-costata. White and St. John, Chicago Acad. Sci., Trans., vol. 1, pp. 120, 122, figs. 

4-6. 

Coal Measures: Iowa. 

1872. Meekella striato-costata. Meek, U. S. Geol. Surv. Nebraska, p. 175, pl. 5, figs. 12a-c. 

Upper Coal Measures: Nebraska City, Bellevue, Plattsmouth, Otoe City, and Aspinwall, Nebr.; 

Kentucky; Iowa; Missouri; Illinois. 

1873. Meekella striato-costata. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 571, pl. 26, 

fig. 21. 

Upper and Lower Coal Measures: Caseyville and various localities in Illinois. 

1875. Meekella striato-costata. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 126, 

pl. 9, figs. 4a-e. (Volume published as a whole in 1877.) 

Carboniferous: Camp Cottonwood, Lincoln County, Nev.; Tenney's ranch, Kaibab Plateau, 

Arizona; Kanab Canyon; Meadow Creek, south of Fillmore; Le.Verkins Creek, and at cliff 

east of Belleview, Utah. 

1876. Meekella striatocostata. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey Group: Confluence of Grand and Green rivers, Utah. 

1883. Streptorhynchus (Meekella) striatocostata. Hall, Rept. New York State Geol. for 1882, pl. (10) 40, 

figs. 18-23. 

1883. Meekella striatocostata. Kayser, Richtofen's China, vol. 4, p. 178, pl. 23, fig. 8. 

Upper Carboniferous: Lo-Ping, China. 

1884. Meekella striatocostata. White, Geol. Surv. Indiana, 13th Rept., p. 130, pl. 26, figs. 12-14. 

Coal Measures: Western part of Vigo County, Ind. 

1892. Meekella striatocostata. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 17, figs. 10-13. 

Upper Coal Measures: Winterset, Iowa; Lawrence County, Kans. 
DESCRIPTIONS OF SPECIES. 351 

1892. Meekella striatocostata. Hall and Clarke, Pal. New York, vol. 8, pt. 1, p. 265, p1. 10, figs. 18-23; 

pl. 11B, figs. 20-22. 

Upper Coal Measures: Winterset, Iowa; Lawrence County, Kans. 

1895. Meekella striatocostata. Keyes, Missouri Geol. Surv., vol. 5, p. 68, pl. 39, figs. la-c. (Date of 

imprint 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1900. Meekella striatocostata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 65, pl. 12, figs. 9-9c. 

Upper and Lower Coal Measures: Fort Scott, Olathe, Kansas City, Eudora, Lawrence, Lecompton, Topeka, Beaumont, Grand Summit, Kans. Widely distributed but moderately rare 

throughout the Coal Measures and base of the Permian. Abundant near base of Permian. 

Shells referable to the genus feekella have been collected at three localities, but 

I am dissatisfied, I confess, with the specific disposition which their unfavorable 

condition has led me to make of them. At Deadwood Gulch in the San Juan region 

(station 2229), specimens are abundant but fragmentary. At the two other points they 

are rare and also fragmentary. At the former occur specimens which can without 

impropriety, so far as their imperfect condition permits judgment, be placed with 

Cox's Meekella striaticostata. From this type there is deviation in several directions, 

a very noticeable phase of which consists in a varying obsolescence of the longitudinal 

plications, and accompanying it of a manifestation by the striae of a strong tendency 

to grow straight and parallel, instead of being arranged in a somewhat pinnate manner 

as in the typical variety. In some of these specimens, also, the striation is much finer 

than in typical examples. 

At Silver Creek (station 2309), also in the San Juan, the only specimen obtained 

shows a form with high area whose surface lacks all but the faintest traces of plications 

and is covered with fine, straight striae which are more or less regularly unequal. 

A still different type is found in a dorsal valve from Leadville (station 2254). 

Here the striae are coarse when compared with the last, but, like them, are rigid and 

parallel. Plications, provided they have not been obliterated by crushing, are almost 

obsolete. Where the crest of each would probably be situated, one of the striae is 

exaggerated, the intermediate ones numbering six or eight. 

I judge that there are two species or varieties involved in this collection, or 

possibly three, but the small amount and wretched condition of my material prevents 

ascertaining their respective limits or their mutual relations. It was apparently for 

a form similar to those with faint plications and straight, parallel striae that Swallow 

proposed the name Orthisina shurnardiana, and this name, it seems to me, it would 

be well to retain, at least in a varietal sense. 

Locality and horizon.—San Juan region (stations 2229, 2309 ?); middle portion 

of the Hermosa formation. Leadville district (station 2254). 
352 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

CHONETES Fischer de Waldheim, 1830. 

CHONETES FLEMINGI Norwood and Pratten. 

PI. I, figs. 17, 18, 18a. 

1854. Chonetes flemingii. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2 S.), vol. 3, p 

26, pl. 2, figs. 5a-c. (Imprint of whole volume, 1855.) 

[Coal Measures] : Ten miles northwest of Richmond, Mo. 

1859. Chonetes fiemingi (f). Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 390. 

White Pekmian limestone: Guadalupe Mountains. 

1891. Chonetes fierningi. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 247. 

Lower Coal Measures: Des Moines, Iowa. 

1892. Chonetes fiemingi. Hall and Clarke, Pal. New York, vol. 5, pt. 1, pl. 15B, fig. 1. 

Coal Measures: Illinois. 

1895. Chonetes fiemingi. Keyes, Missouri Geol. Surv., vol. 5, p. 54, pl. 38, figs. 6a, b. (Date of imprint, 

1894.) 

Upper Coal Measures: Kansas City, Mo. 

In identifying this species, comparison has been made with a rather extensive 

series from the Mississippi Valley. I feel little hesitation in referring both sets of 

specimens to the same species, which I take to be Chonetes fiemingi Norwood and 

Pratten. The latter has been regarded by Schuchert and Weller as a synonym for 

Ch. variolatus d'Orbigny. 

sinus, by having seven instead of four spines on either side of the beak, by having 

guished from 

neuilianus 

led by Norwood and Pratten's work to conclude that 

My study of this material aroused the suspicion that 

were proposed for divergent variations of the same type. One would be 

Ch. verneuilianus by being larger, less strongly marked by fold and . 

Ch. fiemingi 

Ch. fiemingi 

could be distinand Ch. vermore numerous striae (150 instead of 100), and by the pitted character of the surface 

lying between them. The difference in number of striae might be largely offset by 

size, so that this factor would probably have to be disregarded in discriminating the 

two species. 

In the collections examined, although they had been for the most part identified 

with Ch. verneuilianus, I find that almost all the material can be correctly referred 

only to Ch. fiemingi. In regard to size, of course the greatest diversity occurs, but 

in almost every instance specimens were found which attained a much larger size 

than that cited by the authors of CA. rerneuilian,us. Exception must, however, be 

made in favor of a small collection of about a dozen specimens from Casey ville, 

Ill., to which reference will be made later on. These specimens are all small, very 

few attaining a greater transverse diameter than 7 mm. 

It was not in every case possible to ascertain the number of spines possessed by 

each specimen, but almost always more than four could be counted on even the 

smaller examples. As many as nine have been observed, but the most common 
DESCRIPTIONS OF SPECIES. 353 

number is six or seven. Even in specimens of the same size and apparently the 

same age, differences occurred in the number and arrangement of the spines developed, 

at least in the number which could be ascertained. There was also great variation 

in the plicated or sinuate condition of the shell. The dominant type had a strong 

sinus of about the degree of development shown in Norwood and Pratten's figures of 

Ch. flemingi, but variation extended on the one hand to an incipient obsolescence of 

plication and on the other to a condition as strongly folded, in some instances, as 

Ch. verneuilianus, where figured in the original description. Another point of variation which may be mentioned here is in the proportions of the shell, which ranges 

from distinctly transverse to subquadrate, and in the prolongation of the cardinal 

extremities. A transverse shape, produced cardinal line, and a deep fold and sinus 

usually go together in this species, so far as my observations extend. 

The number of stria developed depends, of course, in large measure upon the 

size of the shell, but in the size of the stria and the number occurring in a given 

space no considerable variation was observed. They do vary appreciably, however, 

in the strength with which they are developed, in some cases being raised and strong 

and in others obsolescent. This differenCe can not be ascribed to erosion, as in 

many cases the delicate concentric growth lines could be detected. These are unlike 

the even, threadlike, concentric ,stria covering the coarser radiating ornamentation 

on many Lower Carboniferous members of the genus, but are rather irregular and 

minutely lamellose. 

The pittings between the stria mentioned by the authors in connection with Ch. 

gemingi could be seen in most of the specimens examined, though, of course, 

preservation plays an important part in concealing and revealing such minute 

characters. 

Much the greater part of the material examined, therefore, seems to belong 

rather to Ch. fiemingi than to Ch. verneuilianus. In several instances a few 

individuals, especially by reason of increased gibbosity and an exaggerated development of fold and sinus, approach the limits occupied by the species Chi. verneuilianus. 

Whether they are true representatives of that species is still a matter of doubt in my 

mind, but if they can be correctly so identified, I think one name might well be 

reduced to varietal import, as every gradation seems to occur between the two types. 

In view of these observations Ch. .flerningi would more properly be retained as the 

specific appellation, not only because it has priority among the species described by 

Norwood and Pratten, but because it seems to be the abundant and dominant type of 

which the other is but a variant. 

The small variety from Caseyville mentioned above is transverse, with well 

developed sinus, hinge line much longer than the width of the shell below, and with 

slightly obsolescent stria. 

14364—No. 16 03 23 
354 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The Colorado collection consists for the most part of large shells, with strong 

strife and slight development of sinus. The shape is generally subquadrate. The 

width is greater, though not very much so, than the length, and the hinge line is but 

slightly extended. Exception must be made, however, 'of a few poorly preserved 

specimens from station 2213 in the San Juan region, which are smaller and more 

gibbous than the others and have a strongly impressed ventral sinus. These latter 

have been referred to Oh. Item ingi var. verneuilianus. Ch. ,flemingi is rather 

abundant at Glenwood 'Springs, the form being small and with indistinct sinus. 

Locality and horizon.—Crested Butte district (stations 2293, 2313, 2315); Weber 

limestone and Maroon formation. Grand River region (station 2324), Glenwood 

Springs (stations 2193a, 2326, 2329b). Ouray (station 2194); Hermosa formation. 

CHONETES FLEMINGI var. VERNEUILIANUS. 

1854. Chonetes verneuilana. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 26, p1. 2, figs. 6a-c. (Imprint of whole volume 1855). 

Coal Measures: Charboniere, Mo. 

1859. Chonetes verneuiliana. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Manhattan, Kans. 

1861. Chonetes verneuiliana. Newberry, Ives's Colorado River Expl. Exped., p. 128. 

Upper Carboniferous: Cherty limestones on banks of the Colorado River, 100 miles northwest 

of San Francisco Mountain. 

1872. Chonetes verneuilana. Meek, U. S. Geol. Surv. Nebraska, p. 170, p1. 1, figs. 10a, b. 

Upper Coal Measures: Plattsmouth, Nebr.; Kansas; Iowa; Missouri; Illinois. • 

1883. Chonetes verneuili. Hall, Rept. New York State Geol. for 1882, pl. (16) 47, figs, 20-21. 

Coal Measures: Western States. 

1884. Chonetes verneuilianct. White, Geol. Surv. Indiana, 13th Rept., p. 128, pl. 25, figs. 7, 8. 

Coal Measures: Every county in the Coal Measures of Indiana. 

1892. Chonetes verneuiliana. Hall and Clark, Int. Study of Brach., pt. 1, pl. 20, figs. 5, 6. 

Coal Measures: Illinois. 

1892.. Chonetes verneuiliana. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 6, figs. 20, 21 

Coal Measures: Illinois. 

1900. Chonetes verneuilianus. Beede, Geol. Surv. Kansas, Rept., vol. 6, p. 72, pl. 9, figs. 4-4c. 

Lower and Upper Coal Measures: Bronson, Bourbon County, Kansas City, Buffalo Mound, 

Wabaunsee County, Kans. 

A few poorly preserved specimens from station 2213 in the San Juan region 

have been provisionally placed with Ch. ilemingi var. verneuilianus. They differ 

from the form identified as Ch. flemingi in being smaller, more transverse, and 

furnished with a deeper sinus. 

Locality and horizon.—San Juan region (station 2213); lower portion of Hermosa 

formation. 
DESCRIPTIONS OF SPECIES. 355 

CHONETES GEINITZIANUS Waagen. 

Pl. I, figs. 19, 19a. 

1866. Chonetes glabra. Geinitz, Carb. and Dyas in Nebraska, p. 60, tab. 4, figs. 15-18 (not C. glaber 

Hall, 1857.) • 

Dyas: Nebraska City, Nebr. 

1869. Chonetes glabra. Toula, Sitzb. der Kais. Akad. der Wissench. Wien, 1. Abth., vol. 59, p. 442. 

Carboniferous limestone: 10 miles from Cochabamba, Bolivia. 

1872. Chonetes glabra. Meek, U. S. Geol. Surv. Nebraska, p. 171, pl. 4, fig. 10; pl. 8, figs. 8a, b. 

Upper Coal Measures: Nebraska City, Nebr.; Atchison, Kans. 

1874. Chonetes glabra. Derby, Cornell Univ. (Science), Bull., vol. 1, No. 2, p. 43, pl. 8, figs. 11, 14,1.5, 19. 

Coal Measures: Bomjardim and Itaituba, Brazil, and Cochabamba, Bolivia. 

1876. Chonetes glabra. Derby, Mus. Comp. Zool., Bull., vol. 3, p. 280. 

Coal Measures: Yampopata, 

1884. Chonetes geinitziana. Waagen, Paleontologica Indica, ser. 13, vol. 1, pp. 616, 621. 

1888. Chonetes lxvis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 229, pl. 12, figs. 3a, b. 

Lower Coal Measures: Des Moines, Iowa. 

1889. Chonetes geinitzanus. Miller, North American Geol. and Pal., p. 339. 

1891. Chonetes levis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 246. 

Lower Coal Measures: Des Moines, Iowa. 

1892. Chonetes lsvia. Keyes, Iowa Acad. Sci., Proc., vol. 1, pt. 2, p. 22. 

Lower Coal Measures: Near Des Moines, Iowa. 

1894. Chonetes lavis. Keyes, Missouri Geol. Surv., vol. 5, p. 55, pl. 37, figs. 5a, b. 

Upper Coal Measures: Kansas City, Mo. 

1900. Chonetes glaber. Bbede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 68, pl. 9, fig. 2. 

Upper Coal Measures: Topeka. 

When Waagen proposed Chonetes geinitzianus for this species to replace the 

older name first given it by Geinitz, he pointed out that Chonetes glaber, used by 

the latter, had long been preoccupied by Chonetes glaber Hall.a While Chonetes 

geinitzianus has not yet come into use among American paleontologists, there can 

be no question about the propriety of adopting the name. 

The repregentation of Chonetes geinitzianus in our collections is often scanty 

and the preservation poor. About the only identifications which are believed to be 

unquestionable are at two localities in the Leadville district (stations 2267 and 2268). 

The form at Empire Gulch in the Leadville district (station 2264) is extremely abundant, but so poorly preserved as to make a certain identification impossible. A 

single specimen of small size from near Glenwood Springs can probably be referred 

here. 

In the San Juan region (at station 2243, which is believed to be in the Rico 

formation) Chonetes geinitzianus is found in moderate abundance. The specimens, 

however, are rather undersized. 

a New York State Cab. Nat. Hist., 10th Rept., 1857, p. 117, figs. 1-8. 
356 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

It is, perhaps, deserving of notice that this species is largely restricted, so far as 

our collections indicate, to the Leadville region. 

Locality and horizon.—San Juan region (station 2343); Rico formation. Leadville 

district (stations 2257?, 2264?, 2265 ?, 2267, 2268); base of the Weber formation. 

Grand River region, Glenwood Springs (station 2329b). 

CHONETES GRANULIFER Owen. 

1852. Chonetes granulifera. Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 583, pl. 5, fig. 12. 

Carboniferous limestone: Near mouth of Keg Creek. 

1854. Chonetes smithii. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, p. 24, 

pl. 2, figs. 2a-c. (Entire volume bears imprint of 1855. ) 

Coal Measures: Belleville, Ill. 

1854. Chonetes granulifera. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Joiir., (2), vol. 3, p. 24., 

(Entire volume bears imprint of 1855. ) 

Coal Measures: Belleville, Ill.; Keg Creek, Missouri. 

1858. Chonetes mucronata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 262. (Not C. 

mucronatus Hall, 1843.) 

Upper Coal Measures: Near Fort Riley, Kans. 

1859. Chonetes mucronata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Fort Riley and CottonwoOd Creek, Kansas. 

1864. Chonetes mucronata. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172; p. 22, 

pl. 1, fig. 5a-c. 

Coal Measures: Near Fort Riley, Kans. 

1866. Chonetes mucronata. Geinitz, Carb. and Dyas in Nebraska, p. 58, tab. 4, figs. 12-14. 

Upper Coal Measures: Bennett's Mill and Nebraska City, Nebr. 

1869. Chonetes mucronata. Toula, Sitzb. der Kais. Akad. der Wissensch. Wien, 1 Abth., vol. 59, p. 442. 

Carboniferous limestone: Ten miles from Cochabamba, Bolivia. 

1872. Chonetes granulifera. Meek, U.S. Geol. Surv. Nebraska, p. 170, pl. 4, fig. 9, pl. 6, fig. 10; pl. 8, 

fig. 7. 

Upper Coal Measures: Nebraska City, Wyoming, Bennetts Mill, Plattsmouth, Bellevue, and 

Omaha, Nebr.; Kansas; Missouri; Iowa. 

Coal Measures: Illinois. 

1873. Chonetes smithii. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 570, pl. 25, fig. 11. 

Coal Measures: St. Clair County, Ill. 

1875. Chonetes granulifera. White, U: S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, pt. 1, p. 122, 

pl. 9, figs. 8a-c. (Entire volume bears imprint 1877.) 

Carboniferous (Upper Aubrey limestone) : Kanab Canyon, Arizona. 


1876. Chonetes granulifera. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 


Lower Aubrey Group: Confluence of Grand and Green rivers, Utah. 


1891. Chonetes granuliferus. Beecher, Am. Jour. Sci., (3), yol. 41, p. 357, pl. 17, fig. 15. 

Coal Measures: Manhattan, Kans, 

1892. Chonetes smithi. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 15B, fig. 12. 

Coal Measures: Illinois. 

1894. Chonetes granulifera. Keyes, Missouri Geol. Surv., vol. 5, p. 56. 

Upper Coal Measures: Kansas City, Mo. 
DESCRIPTIONS OF SPECIES. 357 

1900. Chonetes granulifer. Beede, Univ., Geol. Surv. Kansas, Rept., vol. 6, p. 69, pl. 9, figs. 1-1c. 

Coal Measures: Common throughout Coal Measures; from Kansas City to Topeka and Manhattan, Grand Summit, etc., Kans. • 

1900. Chonetes granulifera. Knight., Univ. Wyoming, Wyoming Exp. Sta., Bull. No. 45, pl. 3, fig. 2. 

In all the collections examined but a single specimen of this form, so common at 

certain horizons in the Mississippi Valley, has come to hand. It seems, however, to 

be a characteristic example of Owen's well-known species. 

- Locality and horizon.—Dolores River region, Sinbads Valley (station 2285); top 

of the Hermosa formation. 

CHONETES MESOLOBUS Norwood and Pratten. 

Pl. I, figs. 20, 21,' 22, 23. 

1855. Chonetes mesoloba. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour. (2), vol. 3, p. 27, 

pl. 2, figs. 7a—c. 

Coal Measures: Belleville, Ill.; Charboniere, Mo. 

1875. Chonetes mesoloba. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, pt. 1, p. 123, 

p1. 9, fig. 7a. (Entire volume published in 1877.) 

Carboniferous: Confluence of White Mountain and Black rivers, Arizona. 

1883. Chonetes mesoloba. Hall, Rept. New Yqrk State Geol. for 1882, pl. (16) 47, fig. 22. 

Coal Measures. 

1887. Chonetes mesoloba. Herrick, Sci. Lab. Denison Univ.,1 Bull., vol. 2, p. 49. 

Coal Measures: Flint Ridge, Ohio. 

1888. Chonetes mesoloba. Keyes, Acad. Nat. Sci. Philadelphia,Proc., p. 228. 

Lower Coal Measures: Des Moines, Iowa. 

1892. Chonetes mesoloba. Hall and Clarke, Int. Study of Brach., pt. 1, p1. 20, fig. 7. 

Coal Measures: Illinois. 

1892. Chonetes mesoloba. Hall and Clarke, Pal. New York, Vol. 8, pt. 1, pl. 16, fig. 22. 

Coal Measures: Illinois. 

1894. Chonetes mesoloba. Keyes, Missouri Geol. Surv., vol. , p. 53. 

Upper Coal Measures: KanSas City, Mo. 

1899. Chonetes mesolobus. Girty, U. S. Geol. Surv., Ninetee th Ann. Rept., pt. 3, p. 576. 

Upper Coal Measures: Atoka quadrangle. 

1900. Chonetes mesolobus. Reede, Univ. Geol. Surv. Kansas Rept., vol. 6, p. 71, pl. 9, figs. 3, 3b. 

Lower Coal Measures: Fort Scott and Bronson, Bour n County, Kans. 

The Colorado representatives of this well-ch racterized species are quite typical 

in every way. It is not found at many localities, nor usually in great numbers, but 

at station 2343, which is on Dolores River, the Rico formation, it occurs in 

abundance. Two different types of shell can be istinguished, one small in size and 

with strong lobation, the other large, with t two sulci of the ventral valve 

tending toward evanescence. Specimens from s tion 2238 in the San Juan region 

represent the latter variety. I am disposed to a vocate the distinction by a varietal 
358 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 


name of this large faintly lobate type, especially if, as I believe to be the case, it 

can be correlated with circumstances of range or distribution. 

_Locality and horizon.—San Juan region (stations 2226, 2233, 2238, 2343); upper 

part of the Hermosa formation, Rico formation. Crested Butte district (stations 

2293, 2308); Maroon formation. Grand River region (station 2324). 

PRODUCTUS Sowerby, 1814. 

PRODUCTUS SEMIRETIC17LATUS var. HERMOSANiTS n. var. 

Pl. II, figs. 1 to lc, 2 to 2b, 3 to 3b, 4 to 4b. 

Although representing a type which has sometimes probably been referred to 

Productus costatus Sowerby, I believe the material in hand to be more closely related 

to Productus semireticulatus Martin. Meek a seems to doubt the existence of typical 

P. costatus in this country, and cites an opinion of Davidson to the effect that some, 

at least, of the American shells referred to it are more nearly allied to Martin's species. Although the material from Colorado is probably not identical with the form 

which called forth the remarks just quoted, they tend to corroborate the opinion with 

which the discussion of this species here opens. 

The striae usually number from 8 to 10 in the space of 10 mm. over the median 

portion of the shell, and are equal and regular, but anteriorly they are apt to be unequal and irregular. In this region they are often coarser owing in large measure, I 

believe, to the increased size of the shell, their number remaining about the same and 

their size proportionally augmented. It is not rare, however, to find two or more striae 

coalescing anteriorly into a single larger one, nor, on the other hand, is the bifurcation 

of strive toward the anterior margin of rare occurrence. The former process is sometimes regarded as characteristic of Productus costatus, but in the present form it takes 

place only in a limited degree, and a much greater number of striae are found around 

its margin than is the ease in P. costatus. Sowerby11 cites only 18 in the original 

description, while in this form 50 or more is a common number. In point of fact 

however, neither Sowerby's description nor figures indicate that the large size and 

small number of the striae of P. costatus is due to coalescence, and the reverse seems 

to be the case. The spines developed in this species, except upon the ears, though of 

large size, are comparatively few in number. 

On the other hand, though certainly resembling it in many ways, this is not the 

common form in the Pennsylvanian rocks of the Mississippi Valley which passes 

under the name of Productus sonireticulatus. It is in general somewhat smaller, 

more inflated‘ and incurved, with fewer and larger spines, and ears which are at the 

same time more extended and inrolled. These differences seem to me sufficiently 

constant and well marked to have at least varietal value, and I have distinguished, by 

the term h,ermosanus, the western form possessing them. This species is related to 

a U. S. Geol. Surv. Nebraska, 1872, p. 159. b Min. Conch., vol. 6, 1829, p, 115, p1. 560, fig. 1. 
DESCRIPTIONS OF SPECIES. 359 

Productus spiralis Waagen, from India, and to Productus d'Orbigny,. but 

is clearly distinct from either. It is also very closely allied to the form I have 

designated as P. inflat'us McChesney, which is little more than a variety, and the 

two apparently intergrade completely. This statement, however, might have to be 

modified if all the material were in perfect preservation. 

In its typical condition Productus semireticulatus var, kern ,osanus is largely 

confined in Colorado to the San Juan region.. The stations at which well characterized material has been obtained are, in the San Juan region, 2204, 2207, 2210, 2236, 

2241, 2243, 2302, 2331, 2333, 2335, in the Leadville region, 2262, and in the Crested 

Butte, 2245 and 2293.. Most of the other identifications rest upon intermediate 

gradations between it and P. infiatus, or upon imperfect and scanty material. In 

the San Juan region the two forms seem to be well distinguished and it is in other 

areas where P. infiatus is the prevailing form that intermediates mostly occur. 

P. infiatus displays more of a tendency to graduate into P. semireticulatus var. 

hermosanus, than into P. infiatus, and in some cases the, coarser forms of P. infiatus 

latus 

referred to the other. 

when associated with the finely striated variety have been placed with 

This species also occurs in the Mississippi Valley, where its horizon seems to be 

var. hermosanus when, had they been found alone, they might have been 

P. semireticuat the base of and just below the Upper Coal Measures of the. Kansas section. It 

thus is an earlier form than the typical, or at all events the best-known, variety of 

P. semireticulatus, and is probably its progenitor. The latter is as yet not known to 

occur in Colorado. 

The identification of this form in the fauna from Sinbads Valley is doubtful. 

Locality and horizon.-San Juan region (stations 2200, 2204, 2207, 2210, 2226 ?, 

2236, 2241, 2243, 2331, 2333, 2334, 2335); middle and upper portions of the Hermosa 

formation. Crested Butte district (stations 2245, 2291, 2293, 2300, 2302, 2304); 

Maroon formation. Leadville district (stations 2252, 2259, 2262, 2264, 2265, 2266, 

2275); lower, middle, and upper portions of the Weber formation. Ouray (station 

2194); Hermosa formation. Dolores River region, Sinbads Valley (station 2285); 

top of the Hermosa formation. 

PRODUCTUS INFLATUS McChesney. 

P1. III, figs. 1 to lb, 2, 2a, 3. 

1860. Productus inflatus. McChesney, Desc. New Spec. Pal. Foss., p. 40. 

Carboniferous limestone: Leavenworth, Ind. 

1865. Productus inflatus. McChesney, Illustrations New Spec. Foss., pl. 6, figs. la-c. 

1868. Productus inflatus. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 27, pl. 6, figs. la-c. 

Carboniferous limestone: Leavenworth, Ind. 

Shell of medium size, very gibbous, transversely subquadrate. Ventral valve 

highly inflated, the posterior portion being more strongly flexed than the anterior. 
360 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Beak small, incurved, projecting but slightly beyond the hinge line. Ears rather 

large, extended, vaulted. Sinus broad and shallow, distinct though not strong. 

Dorsal valve slightly concave over the visceral portion. After attaining a length 

of about 20 mm. the curvature is strong and sudden, and subsequent growth follows 

that of the other valve. The visceral cavity is of considerable height, sometimes as 

much as 15 mm., but usually a little less. 

The surface is marked by numerous fine, even, wire-like, radiating striae, and 

posteriorly, over about one-third its length, by concentric wrinkles. The spines are 

few and distant, though large. They are scattered over the surface, sometimes in 

more or less regular quincunx arrangement. Often one or two of the striae are 

interrupted by each spine as it develops, to reappear in a bifurcated condition, three 

or four originating at each spine base. 

reticulatus 

in 

mentation. In the more typical examples of 

the conformation of the shell, and the chief distinction concerns the surface ornaThis form closely resembles the one which I have designated as 

var. hermosa/nus. I am unable to point out any differences of significance 

Productus inflatus 

Procluctus semithe concentric 

wrinkles and radiating striae are much finer and the spines smaller and more numerous. As many as 15 or 16 striw occur in the space of 10 mm., while in Productus 

semireticulatus var. herinosanus only 9 or 10 are found in the same distance. Variation from this proportion in P. inflatus, however, is rather toward coarseness than 

fineness, and the two forms intergrade so that, while well-characterized examples can 

be readily distinguished, others are found which it is difficult to discriminate, identification with one species seeming to present equal claims with the other. 

sanus, 

the difference in range which our Colorado collections indicate. 

This form occurs also in the Mississippi Valley, and I have identified it at Rock 

Productus inflatus 

but I doubt if it should be accorded higher recognition unless on account of 

is certainly a good variety of P. semireticulatus var. hermoBluff, Nebr., Bellevue, Nebr., and at Sumner, Kans. A form which is probably the 

same is found also at Sneedville, Tenn., and 14 miles east of Cumberland Gap, Tenn. 

The fossils from Colorado are somewhat larger than those from Kansas and Nebraska, 

while the Tennessee collection shows a still smaller and somewhat more coarsely 

striated variety. 

I am uncertain as to the correct identification of this species. The form from 

Colorado and that from the localities in Kansas and Nebraska just mentioned are, I 

have little doubt, the same. Except for being a trifle larger, this type answers 

closely to McChesney's description of Productus inflatus, but this author fails to give 

exact data regarding the size of the striae in the form he was describing. The shell 

from Sneedville is possibly more typical than that from beyond the Mississippi. As 

I have already stated, it is smaller and somewhat more coarsely striate, and I am not 

satisfied that it is conspecific with the latter. 
DESCRIPTIONS OF SPECIES. 361 

The affinities of the Colorado form with Derby's Brazilian species, ProductaN 

chandlessi, are very close. I have compared my specimens with a small collection 

from Itaituba, Brazil, and except for one particular the two types seem to be identical, and perhaps the form under discussion would better have been referred, as a 

variety, to P. chandlessi than to McChesney's species. The difference referred to is 

that the Brazilian form has the anterior areas of the shell nearly or quite smooth, the 

stria becoming obsolete over the additions of later growth. P. inflatus also closely 

resembles P. boliviensis of d'Orbigny. The prolongation of the hinge line into 

projecting, enrolled ears is not as marked as in that species. Another closely allied 

form is P. cora var. mogoyoni of Marcou, and I look to see all three appear some day 

in synonymy. There can be no doubt that they are at least intimately related. 

Locality and korizon.—San Juan region (stations 2209, 2213, 2233, 2247); lower 

portion of the Hermosa formation. Crested Butte district (station 2313); Weber 

limestone. Leadville district (stations 2250, 2253, 2254, 2257, 2259 ?, 2265, 2267, 

2268, 2271, 2275, 2281); abundant in the lower portion of the Weber formation, rare 

in the upper portion. Ouray (stations 2195, 2195a, 2195b); Hermosa formation 

Grand River region, Glenwood Springs (station 2193a). 

PRODUCTUS GALLATINENSIS Girty. 

Pl. III, figs. 4, 4a, 5, 6 to 6b, 7, 8, 8a. 

1899. Productus gallatinensis. Girty, U. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 533, pl. 68, figs. 11a-11d, 

7a-7c. 

Madison limestone: Yellowstone National Park. 

Ventral valve very convex, strongly enrolled longitudinally, especially toward 

the beak, which is sometimes placed anterior to the posterior outline of the shell. 

Anterior portion nearly vertical, and but slightly curved. The sides also are nearly 

vertical, slightly converging toward the vault, which is broad and flattened, sometimes with even a shallow, slightly perceptible sinus. The anterior view would thus 

be subquadrate in outline. Hinge line as long as the shell in front, the ears being 

small and quadrate. 

The shape of the dorsal valve is semicircular or subquadrate. It is nearly flat 

over the visceral region, strongly geniculate peripherally, the margin being normal 

to the flattened portion of the shell. Ears small, quadrate, marked off by grooves 

near the hinge line converging to the beak. Visceral area crossed by strong, fine, 

concentric wrinkles. 

The surface is ornamented with fine, strong, rigid, radiating stri, which number 8 to 10 in the space of 5 mm. The visceral region of both valves is crossed for 

some distance by fine, strong, concentric wrinkles, and in the ventral valve the outer 

portions of the shell are furnished with a small number of spines which are proportionately rather large, and sometimes assume, when sufficiently numerous, a more or 

less regular quincunx arrangement. 
362 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Transverse diameter at the hinge line of a moderate-sized individual, 19 mm. 

Length from hinge line to anterior margin, 15 mm. 

In its shape and proportions this shell belongs to a series of forms among which 

I have distinguished five varieties or species besides the one in question. These six 

species are naturally assembled into two groups, one with fine striae, the other with 

coarse. Each group in turn separates into three minor units, chiefly by reason of 

difference in size, and this is very readily accomplished because the differences are 

strong and not bridged over by intermediate examples. Size, however, is not the 

only particular, though it is the most obvious one, in which differences can be found. 

Correspondence in size in the two series of forms is striking, so that, assuming 

this feature as the basis of division, three units would result, each having a coarse 

and a fine variety. I am not satisfied what importance should attach to the differences marking these six types, but feel that they are sufficiently strong to deserve 

notice of some sort. I have, therefore, severally referred these forms or phases to -

species already in the literature which they either resemble or with which they are 

identical, thus admitting them to a rank which subsequent investigation may con 

siderably diminish. 

It surprised me to find this form, which I originally described from strata of 

Mississippian age in Yellowstone National Park, reappearing in association with an 

unmistakable Coal Measure fauna, but after a careful comparison of two rather 

extensive suites of specimens I am unable to point out characters of even varietal 

value by which they can be distinguished. Only inconsiderable differences, chiefly 

between individuals, can be discovered, and their identity is practically complete so 

far as shown by my material, which is both abundant and well, preserved. 

This form answers very closely to Swallow's description of Productus boonensis, 

and I suspect, now thitt its range seems to extend up into the Coal Measures, that 

my name will prove a synonym. It is impossible, however, to decide this point 

without authentic specimens of P. boonensis with which to make comparisons. 

Occasionally, among the material examined, one specimen or two will take on 

almost the proportions of P. parvformis, which differs from P. gallatinensis in little 

but size. 

Locality and horizon.—San Juan region (stations 2197, 2213, 2216 ?, 2233, 2247, 

2284); lower portion of the Hermosa formation. Ouray (station 2195a); Hermosa 

formation. Crested Butte district (station 2245). 

PRODUCTUS PORTIAOCICIANUS Norwood and Pratten. 

1854. Productus portlockianus. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 15, pl. 1, 'figs. 9a-c. (Whole volume published in 1855.) 


Coal Measures: Grayville, White County, Ill.; Charboniere, Mo. 


In Sinbads Valley, at station 2285, occurs a form which is identified with some 

confidence with Norwood and Pratten's Productus portlockianus. This species has 
DESCRIPTIONS OF SPECIES. 363 

generally been considered a synonym of Productus costatus Sowerby. The identification of American forms with Sowerby's species has often been made with protests 

and reservations on the part of authors, and in most cases can be justified only by 

allowing very broad specific limits to the European. form. Meeka clearly doubts 

the correctness of his identification of- Nebraska specimens, and quotes Davidson to 

the effect that the American forms referred to P. costatus are in fact more closely 

allied to P. sem,ireticulatus. With this I am ready to concur, and the widely distributed shell identified with that species as a variety in Colorado is perhaps more 

nearly in agreement with P. costatus, as identified by American paleontologists, than 

with the form commonly referred to P. sonireticulatus. P. portlockianus comes 

closer to true P. costatus than the form which gave rise to the comments of Meek 

just mentioned, but I think it can not be strictly referred to Sowerby's species. 

therefore propose to revive Norwood and Pratten's name for the form. 

Locality and horizon.---Dolores River region, Sinbads Valley (station '2285); 

top of the Hermosa formation. 

PRoDucTus sp. b. 

P1. III, figs. 9-9b, 10, 11. 

This form has been found at but two localities. Eight specimens from a station 

in the San Juan region, and .a few poorly preserved and doubtfully determined 

examples from another in the Leadville region, constitute all the available material, 

which is insufficient to disclose completely the specific characters of the type to which 

it belongs. For this reason and because in shape and other general characters it 

resembles a group of Producti, already sufficiently described, viz, P. semireticulatus 

var Itermosanus, P. inflatu8, P. gallatinensi,s, and Marginifera, no formal description 

will here be given. 

Productus sp. b most resembles, perhaps, the Colorado form of P. infiatus. It 

is distinguished by its smaller size, being only about 30 mm. across the hinge line, 

and by the fact that the ventral valve is narrower and more rounded, and without 

the mesial sinus which marks the larger shell. The surface ornamentation seems to 

be about the same. Productus sp. b resembles the form from Sneedville, Tenn., 

which has also been referred to P. infiatus. The latter-, as already noticed, is 

smaller than the Nebraska type of McChesney's species and much smaller than the 

Colorado representative. Productus sp. b, however, has considerably finer strife and 

is without a mesial sinus so far as observed. 

In size and shape dorsal valves are closely similar to the dorsal valve which I 

have identified as .Marginifera lasallensis, but the striation is much finer. It also 

resembles P. gallatinensis, but is larger and stands midway between that species 

and P. in flatus, 

a U. S. Geol. Silrv. Nebraska, 1872, pp. 159, 160. 
364 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The dorsal valve, of which a figure is given on Pl. III, fig. 9, in the nodulose 

surface ornamentation presents a character not found in the species above mentioned, 

but this example shows mainly the inner surface of the shell. 

Locality and horizon.—San Juan region (station 2214); base of Hermosa formation. Leadville district (station 2259). 

PRODUCTUS CORA d'Orbigny. 

Pl. IV, figs. 1-1b, 2-2a, 3-3a, 4-4b. 

1842. Productus cora. D'Orbigny, Voyage dans l'Amerique Meridionale, Pal., p. 55, pl. 5, figs. 8-10. 

Carboniferous: Above Patapatani, on an island in Lake Titicaca; Yarbichambi. 

1845. Productus lyelli. De Verneuil, Lyell's Travels in North America, vol. 2, p. 221. 

Mountain limestone: Windsor, Horton Bluff, Shubenacadie, Gays River, Debert River, Minudie, 

and Cape Breton., 

1847. Productus cora: De Koninck, Soc. Roy. d. Sci. Liege, Mem., vol. 4, p. 148, pl. 4, fig. 4, a, b; 

pl. 5, fig. 2, a, b, c, d. 

Lower Carboniferous limestone of Vise, of Chokier, and of Ratingen; in the shales of the 

median &age near Tournay, and in the Upper Carboniferous slates of Epinoy near Binche 

(Hainaut) ; banks of the Missouri; Kendal, Westmoreland; Lowick; Yorkshire; Derbyshire; 

Ireland; banks of the Wilji, an affluent of the Taroussa; on the banks of the Louja in the 

district of Medynsk, province of Kalouga; beyond Cosatchi-Datchi on the eastern side of the 

Urals, near Sterlitamack, between Perm and Serebriansk; on the west side of the same chain 

from Kachira on the Oka, and from Unja near Kosimof; Flint Ridge, Zanesville, Guernsey 

County (Ohio); between New Harmony and Mount Vernon (Indiana); Windsor (Nova Scotia); 

Leavenworth, Ind.; on the Bolivian plateau, above Patapatani; in one of the islands of Lake 

Titicaca, and at Yarbichambi, South America. 

1847. Producta cora. De Koninck, Recherches sur les Animaux Fossiles, pt. 1, p. 50, pl. 4, figs. 4a, b; 

pl. 5, figs. 2a-d. 

Carboniferous: Guernsey County, Flint Ridge, and Zanesville, Ohio; between New Harmony 

and Mount Vernon, Ind.; Leavenworth, Ind.; Windsor, Nova Scotia; Bolivia, etc., South 

America. 

1848. Productus martini. Christy, Letters on Geology, pl. 5, figs. 6, 8, 9. 

[Carboniferous]: Pinckneyville, Ill. 

1848. Productus sp. Christy, Letters on Geology, pl. 5, fig. 1. 

Sandstone above the Black shale, Elk River, Tennessee. 

1852. Productus semireticulatus. Hall, Stansbury's Exped. Great Salt Lake, p. 411, p1. 3, figs. 3, 5a, b. 

Carboniferous: Near Fort Laramie; and Flat Rock Point and other places in the neighborhood 

of Great Salt Lake. 

1852. Productus cora. Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pp. 103, 136, pl. 5, fig. 1. 

Carboniferous: Missouri River, below mouth of Little Platte River. 

1852. Productus cora. Roemer, Kreid. von Texas, p. 90. 

Carboniferous: San Saba Valley, Texas. 

1854. Productus cora. Marcy's Expl. Red River of Louisiana, p. 176. 

Carboniferous: Washington and Crawford counties, Ark. 
DESCRIPTIONS OF SPECIES. 365 

1854. Productus cora. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, p. 6. 

(Entire volume appeared in 1855.) 

Mountain limestone: Chester, Rosielam, and Warsaw, Ill.; near Richmond, Mo.; Carrsville, Ky. 

1854. Productus prattenianus. Norwood, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, p. 17, pl. 1, 

figs. 10a-d. (Entire volume appeared in 1855.) 

Coal Measures: Crossing of Big Nemahaw River, about 85 miles northwest of St. Joseph, Mo. 

1855. Productus cora. Salter, Belcher's "Last of the Arctic Voyages," p. 387, pl. 36, fig. 12. 

Carboniferous: Top of Exmouth Island. 

1855. Productus lyelli. Dawson, Acadian Geology, p. 219, fig. g. 

Lower Carboniferous limestone: Nova Scotia. 

1858. Productus cora. Marcou, Geol. North America, p. 45, pl. 6, figs. 4, 4a. 

Mountain limestone: Tigeras Canyon of San Antonio; Pecos Village; summit of Sierra de Sandia, 

New Mexico. 

1859. Productus prattenianus. Meek and HaYden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Coal Measures: Indian Creek and Leavenworth, Kans. 

1863. Productus cora. Davidson, Geol. Soc. London, Quart. Jour., vol. 19, p. 174, p1. 9, figs. 22, 23. 

Lower Carboniferous limestone: Windsor, Horton Bluff, Shubenacadie, Gays River, Cape 

Bi-eton, Pugwash, eastward of Cumberland, Lennox Passage, McKenzie's Mill, at eastern 

extremity of Wallace Harbor, etc., Nova Scotia. 

1866.. Productus flemingi. Geinitz, Carb. und Dyas in Nebraska, p. 52, tab. 4, figs. 1-4. (Not P. 

flemingi de Koninck.) 

Upper Coal Measures: Bellevue, PlattOrnouth, and Nebraska City, Nebr. 

1866. Productus koninckianu4? Geinitz, Carb. und Dyas in Nebraska, p. 53, tab. 4, fig. Not P. 

koninckianus de Verneuil. 

Upper Coal Measures: Nebraska City, Bennett's Mill, Nebr. 

1866. Productus calhounianus. Geinitz, Carb. und Dyas in Nebraska, p. 53. (Not P. calhounianus 

Swallow). 

Upper Coal Measures: Diamond Spring, Santa Fe, in Kansas. 

1866. Productus cora. Geinitz, Carb. und Dyas in Nebraska, p. 50. 

Carboniferous limestone and shales: Germany, Belgium, England, Ireland, Spain, Russia, 

North America, Bolivia, etc. Belleview, Plattsmouth, Nebr. 

1868. Productus cora. Dawson, Acadian Geology, p. 297, figs. 98a, b. 

Carboniferous limestone: Windsor, Horton Bluff, Shubenacadie, Gays River, 1VIinudie, Cape 

Breton, Pugwash, east coast of Cumberland, Lennox Passage, McKenzie's Mill, Wallace 

Harbor, etc., Nova Scotia. 

1869. Productus cf. cora. Toula, Sitzb. der Kais. Akad. der Wissensch, Wien, 1 Abth., vol. 59, 

p. 441. 

Carboniferous limestone: 10 miles from Cochabamba, Bolivia 

1872. Productus prattenianus. Meek, U. S. Geol. Surv. Nebraska, p. 163, pl. 2, figs. 5a-c; pi. 5, fig. 13; 

pl. 8, figs. 10a, b. 

Upper Coal Measures: Nebraska City, Bennetts Mill, Cedar Bluff, Plattsmouth, Bellevue, and 

Omaha, Nebr.; Kansas, Iowa, Illinois. 

Lower Coal Measures: Illinois. 

1874. Productus cora (?). Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 49, pl. 2, fig. 17; 

pl. 6, fig. 17. 


Coal Measures: Itaituba and Barreirinha, Brazil. 

366 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1875. 	Productus prattenianus (pars). White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, 

p. 113, pl.' 7, figs. la-c. (Entire volume published in 1877. ) 

Carboniferous: Near Sante Fe and Zandia Mountains, New Mexico; Piloncillo Range near 

Gavilan Peak, and at the confluence of White Mountain and Black rivers, Arizona; Egan 

Range, 35 miles south of Egan Pass; Fossil Hill, White Pine County; Robert's Creek Range, 

Lander County, and top of Grass Mountain, Ely Range, 35 miles north of Pioche, Nev.; 

near Beckwith Spring, Cedar Range; near top of Mount Nebo, and west face of Oquirrh 

Range, Utah. 

1876. Productus prattenianus. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

1876. Productus cora. Derby, Mus. Comp. Zool., Bull., vol. 3, p. 281. 

Coal Measures: Yampopata. 

1877. Productus prattenianus. Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 72, pl. 7, fig. 7. 

Carboniferous: Fossil Hill, White Pine district; Railroad Canyon, Diamond Mountains, Nevada. 

1878. Productus cora. Dawson, Acadian Geology, 3d edition, p. 297, fig. 98. 

Carboniferous limestone: Windsor, Horton Bluff, Shubenacadie, Gays River, Minudie, and Cape 

Breton, Nova Scotia; Pugwash, on the eastern coast of Cumberland; Lennox Passage; 

M'Kenzie's Mill, at.eastern extremity of Wallace Harbor, etc. 

1884. Productus cora. White, Geol. Surv. Indiana, 13th Rept., p. 126, pl. 26, figs. 1-3. 

Coal Measures: Fountain, Vermilion, Parke, Montgomery, Clay,, Owen, Pike, Dubois, and 

Warrick counties, Ind. 

1884. Productus cora. Waagen, Palaeontologia Indica, ser. 13, vol. 1, p. 677, pL 66, fig. 3; pl. 67, 

figs. 1, 2. 

Productus limestone: Katta, Omarkheyl, Shekh Budin, and Jabi, India. 

1886. Productus cora. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. 1885, p. 452; p. 440, figs. 1, la. 

Mill Creek limestone. 

Upper Coal Measures: Wilkesbarre, Pa. 

1886. Productus cora. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, p. 268, figs. 1, la. 

Mill Creek limestone. 

Upper Coal Measures: Wilkesbarre, Pa. 

1887. Productus cora. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 47, pl. 2, fig. 26. 

Coal Measures: Flint Ridge, Ohio. 

1888. Productus cora. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 227. 

Lower Coal Measures: Des.Moines, Iowa. 

1895. Productus cora. Keyes, Missouri Geol. Surv., vol. 5, p. 47, pl. 37, figs.2a-c. (Date of imprint 

1894.) 

Coal:Measure:8: Calhoun and Kansas City, Mo. 

1896. 	Productus cora. Smith, Am. Phil. Soc., Proc., vol. 35, p. 238. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

? Archimedes limestone: Independence County, Ark. 

? Marshall shale: Independence and Stone counties, Ark. 

? Fayetteville shale: Independence County, Ark. 

1896. ?Productus cora. Smith, Leland Stanford Junior University Pub., Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 28. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 
DESCRIPTIONS OF SPECIES. 367 

? Archimedes limestone: Independence County, Ark. 

? Marshall shale: Independence and Stone counties, Ark. 

? Fayetteville shale: Independence County, Ark. 

1900. Productus cora. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 75, pl. 11, figs. 1-1f. 

Upper Coal Measures: Kansas City, Eudora, Lawrence, Lecompton, Topeka, Geary County, 

Melvern, Osage County. 

The shells which I have referred to this species vary much in size, but agree in 

being finely, often flexuously, striate, with occasional large spines projecting at right 

angles from the surface. There are from 15 to 18 or more strive in the space of 10 

millimeters. The hinge line is nearly as wide as any portion of the shell in front, the 

ears large, quadrate, and marked by coarse wrinkles, which are sometimes continued 

more or less strongly 'over the visceral portion of the valves. This is especially the 

case in the dorsal valve. 

The largest example noted must have had a transverse diameter of nearly 65 millimeters with a length of nearly 80 millimeters. An average specimen of the larger 

sort would measure about 45 millimeters across. 

This is the form to which Norwood in 1854 gave the name Productus prattenianus. 

These shells differ materially from d'Orbigny's figures of Productus cora, but it is 

almost certain that his figures are altogether misleading, and the resume of the 

matter given by Waagen is a very plausible argument for considering that the South 

American form is the same as that for which Productus prattenianus was proposed. 

It has therefore been found necessary to, employ the earlier published but less 

perfectly defined term. 

Productus cora is rare in the Rico formation. Four localities have furnished 

each a specimen. So far as the collections at hand indicate, the form which is found 

in the Rico does not differ materially from that occurring in the lower formation. 

Locality and horizon.--San Juan region (stations 2196, 2196a, 2200, 2204, 2205, 

2208, 2209, 2210, 2213, 2216, 2219, 2221 ?, 2222, 2233, 2239, 2248, 2331, 2332, 2334, 

2335, 2340, 2341, 2342, 2344); abundant in the lower, middle, and upper portions of 

the Hermosa formation, rarer in the Rico formation, Crested Butte district (stations 

2300, 2302, 2306, 2313, 2317); Weber limestone and Maroon formation. Leadville 

district (stations 2254, 2257, 2259, 2268, 2270 ?, 2271, 2275, 2281); lower and upper 

portion of the Weber formation, and base of the Maroon formation ( ?). Ouray 

(stations 2194, 2195a); Hermosa formation. 

PRODUCTUS PERTENUIS Meek? 

1866. Productus cancrini. Geinitz, Carb. and Dyas in Nebraska, p. 54, tab. 4, fig. 6. (Not P. cancrini 

de Verneuil, 1843.) 

Upper Coal Measures: Nebraska City, Nebr. 

M72. Productus pertenuis. Meek, U. S. Geol. Surv. Nebraska, p. 164, pl. 1, figs. 14a-c; pl. 8, figs. 9a-d. 

Upper Coal Measures: Nebraska City and Brownville, Nebr. ; Grasshopper Creek, 12 miles west 

of Leavenworth and Atchison, Kans. 
368 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1898. Productus pertenuis. Drake, Am. Phil. Soc., Proc., vol. 36, p. 404, pl. 9, figs. 8-10. Reprinted 

without change of date, page, etc., in Leland Stanford Junior Univ. Pub.; Cont. Biol. Hopkins 

Seaside Lab., No. 14. 

Lower Coal Measures: 4 miles north of Vinita. 

Upper Coal Measures: Cavinol group: McClellan ford on the Verdigris River. Poteau Group: 

6 miles west of South Canadian. 

Permian division: Upper bed of sandstone, 4 miles west of McDermitt; Pawhuska sandstone, 5 

miles west of Cushing. 

Lower Carboniferous limestone (Boston group) (St. Louis-Chester): 5 miles southeast of Adair. 

1900. Productus pertenuis. Beede, Univ. Geol. Surv. Kansas, Rept:,. vol. 6, p. 83, pl. 9, figs. 5-5c. 

Upper Coal Measures: Kansas City, Eudora, Lawrence, Lecompton, Topeka, Kans. 

This species is very rare in the collections examined. Comparison has been 

made with the type, and the identification here noted is probably correct, so far as 

can be determined from a single not too perfect Specimen. 

Locality and horizon.—San Juan region (station 22240; middle portion of the 

Hermosa formation. ' 

PRODUCTUS PUNCTATUS Martin, 

1809. Anomites punctatus. Martin, Petrf. Derb., p. 8, pl. 37, fig. 6. 

1836. Productus punctatus f Morton, Am. Jour. Sci., (1), vol. 29, p. 153, pl. 26, fig. 38. 

Coal Measures: Ohio Valley. 

1838. Productus semipunctata. Shepard, Am. Jour. Sci., (1), vol. 34, p. 153, fig. 9. 

Limestone: Peru, Ill. 

1847. Productus punctatus. De Koninck, Monog. du Gen. Prod. et Chon., p. 123, pl. 12, figs. 2a-k. 

Carboniferous: Zanesville, Ohio; Eddyville and Louisville, Ky. 

1854. Productus punctatits. Shumard, Marcy's Expl. Red River of Louisiana, p. 175, pl. 1, fig. 5; pl. 2, 

fig. '1. 

Carboniferous: Washington County, Ark. 

1854. Productus punctatus. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, p. 19. 

(Entire volume published in 1855.) 


Mountain limestone: Warsaw, Ill, 


Coal Measures: 12 miles northwest of Richmond, Mo.; near Caseyville, 


1858. Productus punctatus. Marcou, Geol. North America, p. 48, pl. 6, fig. 2. 

Mountain limestone: Tigeras, Pecos Village, and in the Sierra de Mogoyon, New Mexico. 

1860. Productus tubtdospinus. McChesney, Desc. New Spec. Pal. Foss., p. 37. 

Coal Measures: Western States. 

1865. Productus tubulospinus. McChesney, Illustrations New Spec. Foss., pl. 1, figs. 10, 11. 

1866. Productus punctatus. Geinitz, Carb. and Dyas in Nebraska, p. 55.. 

Carboniferous limestone: Bellevue and Plattsmouth, Nebr. 

1868. Productus punctatus. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 27, pl. 1, figs. 10, 11. 

Upper and Lower Coal Measures: Throughout the Western States. 

1872. Productus punctatus. Meek, U. S. Geol. Surv. Nebraska, p. 169, pl. 2, fig. 6; pL 4, fig. 5. 

Upper Coal Measures: Nebraska City, Bennetts Mill, Wyoming, Rock Bluff, Plattsmouth, and 

Bellevue, Nebr.; Illinois; Iowa; Missouri. 


Lower Coal Measures: Missouri; Iowa; Illinois. 


Lower Carboniferous: Missouri; Iowa; Illinois. 

DESCRIPTIONS OF SPECIES. 369 

1873. Productus punctatus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 569, pl. 25, fig. 13. 

Upper and Lower Coal Measures: Illinois. 

1875. Productus punctatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 114, pl. 7, 

figs. 2a-c. (Entire volume published in 1877.) 

Carboniferous: At and near top of Grass Mountain, Ely Range, 35 miles north of Pioche, Nev. 

1876. Productus punctatus. White, Powell's Rept. Geol. Uinta Mountains, IN 89. 

Lower Aubrey Group: Confluence of Grand and Green rivers, Utah. 

1878. Productus sp. allied to P. punctatus. Etheridge, Geol. Soc. London, Quart. Jour., vol. 34, p. 630. 

Carboniferous: Feilden Isthmus, latitude 82° 43/. 

1882. Productus punctatus. White, Geol. Surv. Indiana, 11th Rept., p. 373, p1. 42, figs. 1-3. 

Coal Measures: Newport, Ind. 

1883. Productus punctatus. Hall, Rept. New York State Geol. for 1882, pl. (19) 50, figs. 14-16. 

1883. Productus rogersi. Hall, Rept. New York State Geol. for 1882, pl. (19) 50, figs. 17, 18. 

Coal Measures. 

1884. Productus punctatus. White, Geol. Surv. Indiana, 13th Rept., p. 124, pl. 27, figs. 1-3. 

Coal Measures: Vermilion, Vigo, Sullivan, Vanderberg, Dubois, Warrick, and Pike counties, Ind. 

1887. Productus punctatus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 48, pl. 2, fig. 29. 

Coal Measures: Flint Ridge, Ohio. 

1892. Productus punctatus. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 22, figs. 9, 10. 

Coal Measures: Mississippi Valley. 

189. 	Productus punctatus. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 17A, fig. 21; pl. 19, figs. 

14-18. 

Upper Coal Measures: Near Kansas City, Mo.; Missouri. 

1895. Productus punctatus. Keyes, Missouri Geol. Surv., vol. 5, p. 51. pl. 37, figs. la-c. (Date of 

imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1896. 	Productus punctatus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 239, pl. 22, fig. 7. 

Lower Coal Measures: Conway County, Ark. 

Lower Carboniferous: Several localities in Arkansas. 

1900. Productus punctatus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 87, pl. 10, figs. 3-3c; 

pl. 11, fig. 3. 

Upper Coal Measures: Kansas City, Turner, Lawrence, Lecompton, Topeka, Moline. 

1896. Productus punctatus. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 29, pl. 22, fig. 7. 


Lower Coal Measures: Conway County, Ark. 


Lower Carboniferous: Several localities in Arkansas. 


The collections examined indicate that this is a rather ri're fossil in the Colorado 

Carboniferous. The identification at station 2221 in the San Juan region is doubtful 

on account of the poor character of the material, a single very small, exfoliated 

specimen. 

Locality and horizon.—San Juan region (stations 2204, 2241, 2334, 2335); middle 

and upper portion of the Hermosa formation. 

14364—No. 16-03-24 
370 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PRODUCTUS NEBRASKENSIS Owen. 

Pl. V, figs. 1, 2, 2a. 

1852. Productus nebrascensis. Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 584, pl. 5, fig. 3. 

Carboniferous limestone: Bellevue, Missouri River, Nebr. 

1854. Productus rogersi. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, p. 9, 

pl. 1, figs. 3a-c. (Whole volume appeared in 1855. ) 

Coal Measures: Near Huntsville, Mo. 

1854. Productus nebrascensis. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 21. (Whole volume appeared in 1855.) 

Coal Measures: Crossing •of Big Nemaha, Nebraska Territory. 

1856. Productus rogersi. Hall, Pacific Railroad Rept., vol. 3, p. 104, pl. 2, figs. 14, 15. 

Carboniferous limestone: Pecos Village, N. Mex. 

1859. Productus rogersi. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Kansas River Valley, below mouth of Blue River, Kansas. 

1860. Productus asperus. McChesney, Desc. New Spec. Pal. Foss., p. 34. 

Coal Measures: Lasalle and Springfield, Ill. 

1861. Productus rogersi. Newberry, Ives's Colorado River Expl. Exped., p. 121. 

Coal Measures: Pecos Village and Kansas. 

1865. Productus asper. McChesney, Illustrations New Spec. Foss., pl. 1, figs. 7 a-b. 

1866. Strophalosia horrescens. Geinitz, Carb. and Dyas in Nebraska, p. 49. (Not S. horrescens of 

Murchison, Verneuil, and Kayser.) 

Coal Measures: Bellevue, Plattsmouth, Nebraska City, and Bennett's Mill, Nebr. 

1868. Productus nebrascensis. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 24, pl. 1, figs. 7a-b. 

Coal Measures: Lasalle and Springfield, Ill. 

1872. Productus nebrascensis. Meek, U. S. Geol. Surv. Nebraska, p. 165, pl. 2, fig. 2; pl. 4, fig. 6; pl. 

5, figs. 11a-c. 

Upper Coal Measures: Nebraska City, Wyoming, Bennett's Mill, Rock Bluff, Plattsmouth, 

Bellevue, and Omaha, Nebr. 

1873. Productus nebrascensis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 569, pl. 25, fig. 8. 

Coal Measures: Sangamon and Lasalle counties, Ill. 

1875. Productus nebrascensis. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 116, 

pl. 8, figs. 3a-d. (Whole volume published in 1877.) 

Carboniferous: Camp Apache and Carrizo Creek, Maricopa County, Ariz.; Rubyville, Schell 

Creek Range, and top of Grass Mountain, Ely Range, Nevada; Meadow Creek, south of 

Fillmore, Utah. 

1876. 	Productus nebrascensis. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: Confluence of Grand and Green rivers. 

1877. 	Productus nebrascensis. Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 65. 

1883. 	Productus asperses. Hall, Rept. New York State Geol. for 1882, pl. (19) 50, figs. 5-7. 

Coal Measures: Lasalle, Ill. 

1884. Productus nebrascensis. White, Geol. Surv. Indiana, 13th Rept., p. 122, pl. 24, figs. 7-9. 

Coal Measures: Fountain, Vermilion, Parke, and Vigo counties, Ind. 
DESCRIPTIONS OF SPECIES. 371 

1886. Productus nebrascensis, Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 453, 

fig. 4c; p. 440, figs. 4 4b. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Productus nebrascensis? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p. 268, figs. 4, 4b. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Productus nebrascensis. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 49, pl. 2, fig. 30. 

Coal Measures: Flint Ridge, Ohio. 

1892. Productus nebrascensis. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 22, fig. 7. 

Coal Measures: Lasalle, Ill. 

1892. Productus nebrascensis. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 19, figs. 5-7. 

Coal Measures: Lasalle, Ill. 

1895. Productus nebrascensis. Keyes, Missouri Geol. Surv., vol. 5, p. 48, pl. 37, figs. 3a-c. (Date of 

imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1900. Productus nebrascensis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 84, pl. 9, figs. 7-7f. 

Upper Coal Measures: Kansas City, Turner, Eudoia, Lawrence, Lecompton, Topeka, Manhattan, and Grand Summit, Kans. 

In our collections the representation of this species is practically confined to the 

Durango quadrangle and to the Leadville district. In these two areas it has been 

found at a number of localities, and seems to be fairly abundant, though it is not 

often well preserved, owing to the character of its surface ornamentation. Because 

of the circumstance last mentioned, some of the identifications may possibly represent 

specific affinity, rather than strict specific identify. 

Herrick identifies with Productus nebraskensis certain shells from the Waverly 

group in Licking County, Ohio.a His figures represent at least two and possibly 

three species, none of which is closely related to P. nebraskensis. The large form 

shown on his pl. 1 is, I believe, a species which is rather abundant at Sciotoville, 

Ohio. Meek described and figured it as Productus sp.' Winchell probably referred 

to it as Productus cooperensis ?.c It is related to Productus blairi, but is probably 

new. The name Productus winchelli is here proposed for it. 

The small form figured by Herrick on pl. 3 as Productus nebraskensis seems to 

belong to the semireticulatus type, and is possibly related to P. wortheni. 

Locality and horizon.-San Juan region (stations 2200, 2204, 2205, 2207, 2209, 

2210, 2213, 2215, 2239, 2240, 2248 ?, 2333); lower, middle, and upper portions of the 

Hermosa formation, and in the Rico formation. Leadville district (stations 2254 ?, 

2267, 2268, 2271, 2281); base of the Weber formation. Ouray (station 2195b); Hermosa formation. 

a Sci. Lab. Denison Univ., Bull., vol. 3, 1888, p. 31, p1. 1, fig. 24; pl. 3, figs. 25 (?), 25a. 

bGeol. Surv. Ohio, Rept., vol. 2, pt. 2, 1875, p. 282, p1. 10, figs. 4a-4c. 

c Am. Phil. Soc., Proc., vol. 12, 1870, p. 249. 
372 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PRODUCTUS sp. a. 

Pl. V, fig. 3. 

This species has a very scanty representation among our collections, four fragmentary specimens from three localities in the San Juan region, being all the material 

that has so far come to hand. The shape of the ventral valve appears to be not 

unlike that of P. semiretierulatus var. hermosanus, but the beak is as a rule more 

tapering. There is a more or less distinct sinus. The posterior portion is crossed 

by rather faint, irregular wrinkles. The strive are sharp but nodulose, and somewhat discontinuous, especially about the ears. They thus present a wavy, irregular 

appearance. The nodules formed in many cases the bases of small spines. 

The dorsal valve is more regular and finely reticulated, the spaces between the 

striae and wrinkles forming little pits. 

At one time I was disposed to place this form with that which Marcou identified 

as P. pyxidatus de Koninck, but this course seems hardly prudent in view of his 

rather meager, poor, and conflicting figures and description. 

There can be no doubt that his identification with de Koninck's species, if his 

figures even approach accuracy, is altogether incorrect. 

Locality and horizon.—San Juan region (stations 2208, 2328, 2335); middle and 

upper portions of the Hermosa formation. 

MARGINIFERA Waagen, 1884. 

MARGINIFERA LASALLENSIS Worthen ?. 

Pl. V, figs. 4-4a. 

1873. Productus lasallensis. Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 569, pl. 25, fig. 9. 

Upper Coal Measures: Lasalle, Ill. 

1892. Productus (Marginifera) lasallensis. Hall and Clarke, Int. Study of Brach., pt. 1, pl. 22, 

fig. 15. 

Upper Carboniferous: Lasalle, Ill. 

1892. Productus (Marginifera) lasallensis. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pl. 17A, 

fig. 13. 

Upper Carboniferous: Lasalle, Ill. 

The form which I have referred to Worthen's species is represented by one good 

dorsal valve and by fragments of three ventrals. The latter are almost too poor to 

serve for description or as a guide in identifying the species, but the dorsal seems 

to be identical in its diagnostic characters with the corresponding valve of P. 

lasallensis. 

Viewed from its convex or inner side this specimen may be described as follows: 

In shape it is transversely semielliptical, hinge line about 28 mm. long, ears quadrate, defined by two shallow radiating grooves. There is a distinct, though not very 
DESCRIPTIONS OF SPECIES. 373 

strong, mesial depression. The visceral area is but slightly convex. After attaining a length of about 15 mm. the shell assumed a strong downward growth, so that 

the peripheral portion lies almost perpendicular to the plane of the visceral area. 

The surface is crossed by rather coarse radiating strive, 10 or 12 in the space of 10 

mm., and the entire visceral portion is traversed by fine concentric wrinkles. 

In size the shell corresponds to Productus sp. b, but is much more coarsely 

striate. It resembles in striation as well as shape both 

mosanus 

than the other. 

We have two authentic specimens of 111 

and lifarginifera niuricata, but is much smaller than the one and much larger 

lasallensis from Lasalle, Ill., with which 

P. sernireticulatus var. her-­

collections from Pawnee City, Nebr., Fort Scott, Kans., and Graham, Young County, 

Tex., agree in every way. The collections from Kansas, Nebraska, and Texas I do 

not hesitate to refer to the same species as the shell from Illinois which Worthen 

has identified as M. lasallensis. These specimens, however, do not agree with 

which all these specimens possess in some degree, and which is usually well marked. 

sis 

Furthermore, he has restored his fragmentary specimen in such a manner as to make 

Worthen's figures and description in several particulars. He states that /IL 

is without concentric wrinkles over the posterior portion of the shell, a character 

lasallena larger shell than any seen by me, and to give it a very alate shape, while the hinge 

line of the specimens I have studied is but little extended. 

The Colorado examples present a close superficial agreement with this, as I 

regard it, characteristic material, but the true Productus lasallensis clearly belongs 

to Waagen's genus 31-arginifera, while I doubt if my material does. Still, the latter 

is too imperfect to permit me to satisfy myself upon this point. Were it not for 

this important difference I would refer the Colorado specimens without hesitation to 

Worthen's species, so close is their general agreement. 

Locality and horizon.—Crested Butte district (station 2316?), Weber limestone. 

MARGINIFERA MURICATA Norwood and Pratten. 

Pl. V, figs. 5, 5b, 6, 6b, 7. 

? 1852. Productus flem'ingii. Roemer (non de Koninck), Kried. von Texas, p. 89, pl. 11, figs. 8a, b. 

Carboniferous: San Saba Valley, Texas. 

1855. Productus muricatus. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 14, p1. 1, figs. 8a-e. (Not P. muricatus Phillips.) 

Coal Measures: Fishhook Creek, Pike County, Ill.; 6 miles northwest of Richmond, Mo. 

1857. Productus muricatus. Cox, Geol. Surv. Kentucky, Rept., vol. 3, p. 573, pl. 9, fig. 6. 

Coal Measures: Union County, 111.; Lewisport, Hancock County, Ky.; Gallatin County, Ill. 

1876. Productus muricatus. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: Near Echo Park, Utah. 

1877. Productus muricatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 120, pl. 8, 

figs. 4a-c. 


Carboniferous. Rock Creek, Lake County, Colo. 

374 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1887. Productus muricatus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 49. 

Coal Measures: Flint Ridge, Ohio. 

1888. Productus muricatus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 228. 

Lower Coal Measures: Des Moines, Iowa. 

1900. Productus longispinus. Knight, Univ. Wyoming, Wyoming Exp. Sta., Bull. No. 45, pl. 3, fig. 10. 

The form which, in Colorado, I have identified with 71farginifera muricata, may 

be described as follows: 

Shell rather small, semicircular. Ears small, quadrate, and not prolonged. 

Hinge line about equal to the greatest width. Curvature moderate, not so great as 

in 111. splendens. Surface marked by concentric nodose wrinkles, strongest on the 

ears, and by coarse, somewhat nodose stri, which number about 25 on a mediumsized shell. It is entirely covered at short intervals by small spines springing from 

the ribs. The transverse diameter is usually from 16 to 19 mm. 

The dorsal valve is semicircular in shape with quadrate ears. The latter are 

upturned, when looking at the interior of the valve, and defined by two ascending 

and diverging ridges. The shell is nearly flat over the visceral portion, but a 

geniculation occurs about 10 mm. from the beak. 

The shells agree closely with what I consider typical M. muricata from the 

Mississippi Valley, but with this exception, that while specimens of the latter are 

(so far as my experience goes) nearly uniform as regards the size of the striae, those 

from Colorado vary from a degree of fineness comparable with the latter to considerably coarser. The Colorado form is also somewhat more strongly arched. I have 

considered the advisability of distinguishing these coarse occidental shells by a varietal 

name, but as they occur in immediate association with the typical form into which 

they merge by insensible gradations, it seemed sufficient merely to call attention to 

the circumstance in an informal manner. 

In addition to variation in the matter of striation, which has already been 

referred to as occurring among these shells, variation, often of local occurrence and 

appearing in most of the specimens from a station, has been noticed in size, abundance of spines, and other matters. 

It is possible that imperfectly preserved material may have given rise to misapprehension as to the degree of variation in some particulars, as, for example, the 

abundance of spines, but, on the other hand, it may be that with more perfect 

material I would have felt justified in discriminating subdivisions among the fossils 

here assembled into a single group. 

Schucherta retains Norwood and Pratten's name for this species, because Productus 

muricatus Phillips, which has priority, is. regarded by many as a synonym for P. 

costatus Sowerby. This course violates the rule, once a synonym always a synonym, 

and can scarcely be allowed, but Norwood and Pratten's name will still hold if 

Waagen's genus MarginVera, of which it is a representative, be accorded generic 

S. Geol. Surv., Bull. No. 87, 1897, p. 327 (P. muricatus). 
DESCRIPTIONS OF SPECIES. 375 

standing. Hall and Clarke° rather discredit the significance of the characters upon 

which illarginifera is founded, and if their view is correct, a new name will have to 

be sought for this species. 

I have tentatively added to the usual synonomy Roemer's identification with 

P. flemingi of a shell from Texas. The figures of the Texan form are certainly 

suggestive of Norwood and Pratten's species. 

Locality and Horizon.—San Juan region (station 2196a); Hermosa formation.. 

Crested Butte district (stations 2244, 2245, 2280, 2292, 2297, 2316, 2318); Weber 

limestone and Maroon formation. Grand River region (station 2324), Glenwood 

Springs (station 2326). 

MARGINIFERA WABASHENSIS Norwood and Pratten var. 

Pl. V, figs. 8, 8a. 

1854. Productus wabashensis. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 13, pl. 1, figs. 6a-d. (Imprint of whole volume, 1855.) 


Coal Measures: Near New Harmony, Ind. 


I have experienced great difficulty in reaching a decision satisfactory to myself 

in regard to the forms belonging to the group for which Waagen proposed the name 

Ilfarginifera, not only in the matter of discriminating species, but in determining the 

name which should be employed for them. 

In 1854 Norwood and Pratten described three species of Productus belonging 

to this group whose mutual specific relations are very close. They were given the 

names P. muricatus, P. splendens, and P. wabashensis. 

• Meek 6 places all three species in the synonymy of P. longispinus Sowerby, following Davidson's judgment in this, though, it is apparent, doing violence to his own, 

at least in the case of P. muricatus. Waagen e recognizes P. wabashensis and 

P. splendens as independent species, each of them valid and distinct from P. 

longispinus. Frech d regards P. wabashensis and P. splendens as identical, but as 

certainly distinct from Sowerby's species. 

There can, I think, be no doubt but that P. muricatus is distinct not only from 

P. splendens and P. wabashensis, but from P. longispinus. P. splendens and 

P. wabashensis are much more closely akin to each other than is either of them to 

spinus. 

though Davidson! included under 

P. muricatus; 

Although Sowerby 

nor can there be much doubt that they also are distinct from 

a Pal. New York, vol. 8, pt. 1, 1892, p. 331. 

b U. S. Geol. Surv., Nebraska, 1872, p. 161. 

e described his species as "indented in the middle," and 

P. longispinus shells which are both evenly convex 

P. longic Geol. Surv. India, Mem. Pal. Ind., 13th series, vol. 1, 1887, p. 715. 

d Lethaa Geognostica, 1. theil, 2. band, 2. lieferung, 1899, desc. pl. 47c, fig. 14. 

e Min. Conch., vol. 1, 1814, p. 154. 

.f Pal. Soc., Mon. British Carb. Brach., pt. 5, 1857, p. 145, pl. 35, figs. 5-17. 
376 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and divided by a sinus, neither Sowerby's nor Davidson's figures of the type specimen 

show a sinus. Their figures as well as their descriptions indicate that the hinge line 

is no wider than the body of the shell. The ventral valve seems not to have been 

very highly arched, to judge by the figures, though Sowerby says that the " reflexed 

margin is entirely lost, etc." The ribs are not mentioned in the original description 

nor represented in the figures, but Davidson's figure shows them to be as prominent 

as in the average specimen. They vary from 30 to 50 in number, according.to this 

author. Norwood and Pratten mention 30 as occurring in P. splendens. They are 

usually more or less obsolete, however, and the sinus is typically deep and the ears are 

produced. Frech states that though related to P. longispinus, P. splendens can 

easily be distinguished by reason of its fainter striation and more strongly expressed 

are specifically distinct. 

muscular and visceral markings. Waagen finds that typical specimens of 

fera, 

found in different genera even. At all events it will be safe to conclude that they 

spinus 

and according to his view, therefore, 

are practically entirely without the internal ridges characteristic of 

P. longispinus and P. splendens would be 

IfarginiP. longiAnother species whose relationship with P. splendens is certainly close, and 

whose name, in case of identity proved, would supersede that proposed by Norwood 

and Pratten, is P. capacii d'Orbigny. Waagen expresses the opinion that this species 

is distinct from P. splendens, and with this I am content to agree, although, being 

without specimens with which to make comparisons, a conclusive judgment can not 

be formed. One difference manifest at first sight from the figures is the inflation of 

the posterior portion of cllOrbigny's shell by which it is brought to project far 

ensis 

beyond the hinge line. In this particular 

Turning now to the relationship of 

described below, which is certainly distinct from 

P. splendens 

P. capacii, is close to 

and 

P. splendens. 

P. wabashensis, 

Iliarginifera haydenone would 

not long hesitate to conclude from Norwood and Pratten's figures that the two 

species are clearly distinct. Meek, however, after examining good specimens of P. 

wabashensis from the original locality, concludes (loc. cit.) that the figures of that 

species are quite defective in representing the cost, and if one considers the 

difference in proportion shown by the figures of the original reference between the 

dorsal and ventral views of the same specimen, it seems clear that the outline, too, is 

not to be trusted. 

I have before me some specimens "from below the coal" at Wabash cut-off, 

New Harmony, Ind., which I suppose can be considered as coming from the original 

locality and as representing the typical phase of P. wabashensis. They show a 

broad, highly arched form, with strong median sinus and slightly extended ears. 

The beak is small and transgresses the hinge line but little. Concentric wrinkles 

are almost wanting; the striae are fine and obsolescent, and the surface supports a 
DESCRIPTIONS OF SPECIES. 377 

few comparatively large scattering spines. This form has a wide distribution in 

the Mississippi Valley, and I have remarked it in Indiana, Illinois, Iowa, Missouri, 

and Kansas. It undergoes many variations in minor particulars, but seems everywhere to retain the same general expression. Many specimens occur in which the 

shape is not alate and the hinge line is no longer than the shell below. It is usually 

difficult to determine whether this is due to breakage or is the natural shape, but in 

some cases it can hardly be accidental. Oftentimes the curvature, instead of being 

regularly arcuate, is angulated, the flattened visceral portions giving onto the lateral 

parts by a sort of geniculation. The two forms occur together at the New Harmony 

locality mentioned above, and are associated at most of the points from which collections have been obtained. The strive, which are never very strong, sometimes 

become so faint that the shell looks almost smooth. In many cases they are apparent 

over the posterior portion of the shell and become obsolete toward the margin. 

More rarely they are obsolete over the visceral portions of the shell. The sinus is 

often strong, but its variation is considerable. The peculiar submarginal ridges of 

_MarginVera are distinct in some specimens, but apparently lacking in others. I 

have not been able to find them in my material from the type locality. Although 

the shells examined are thus variable, the variation is so inconstant that I would not 

feel satisfied to distinguish any of them as separate species. In most cases, however, it is possible without much difficulty to discriminate between individuals with 

regular curvature and those which are geniculate. I will provisionally make a 

division of these shells upon this basis, distinguishing the geniculate ones as a variety 

without, however, giving it a name. The other group is of course the typical one. 

In Colorado only the geniculate variety has as yet been found, and it seems to 

be, as a rule, rather rare. My specimens, which are for the most part in not very 

good condition, agree closely with those from the Mississippi Valley. They add 

nothing to the facts shown by the latter, and deviate only so far as that they are 

generally a little undersized. 

Another feature of these shells which may be worthy of mention is that I have 

observed many ventral valves to be covered externally, sometimes nearly all over, 

but especially on the posterior portion, by a rough superficial deposit, which gives 

them a peculiar scaly appearance. This has been noticed at several localities in the 

Mississippi Valley. I believe that it is not of mineral origin, but it may be parasitic. 

Of Product/us splendens also I have specimens from a number of localities in 

Kansas. They are of a nearly uniform type, one whose characters correspond faithfully with those ascribed to P. splendens by Norwood and Pratten. The shell is 

broad, strongly arched, often with the visceral area nearly flat and merging with a 

geniculation into the lateral portions, this character being well shown by Norwood 

and Pratten's figures.a The sinus is deep, the ears well extended, concentric wrinkles 

Loc. cit., p1, 1, figs. 5c, 5d. 
378 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

faint, strive almost obsolete, spines few and scattering, development of submarginal 

ridges strong. 

From this it will be seen that P. wabashensis, especially that variety of it which 

is characterized by a geniculate curvature, is very similar indeed to P. splendens, 

for P. splendens was founded upon a geniculate shell, just as P. wabashensis was 

founded upon an arcuate one. But in the case of P. splendens the variation to an 

arcuate type appears to be less frequent and less pronounced than that in 

ensis 

can be recognized as a distinct species, because of its smaller size, its generally more 

On the whole, I believe that 

to a geniculate one. 

P. wabashensis, together with its geniculate variety, 

P. wa,bash,­

distinct striation, and its less persistent disposition to develop the Ilfarginifera type 

of structure. To many, doubtless, it will seem that the geniculate variety of 

P. wabashensis should not be separated from P. splendens, and to others, recognizing the near relationship of the former with the type to which the name strictly 

pertains, that the species should lapse to P. splendens as a full synonym. For my 

own part, as far as my experience extends, it would justify the recognition of these 

small shells, with their evanescent marginiferoid characters, as at least a variety 

distinct from P. splendens. The distinction between the arcuate and geniculate 

phases of P. wabashensis is a minor one and probably not worthy of varietal 

recognition. 

The peculiar beveled condition of the dorsal valve which is present in all these 

forms, but especially in M. 8plendens, was noticed by Norwood and Pratten and 

shown in their figures.a The formation of this truncated rim is correlated with the 

development of the internal submarginal ridges upon which, chiefly, Waagen founds 

his genus Maxginfera. These occur largely on the dorsal valve and on the sides of 

the ventral valve. Where specimens possessing this structure are found weathered 

free, the outer or peripheral portions of the shell are usually broken away, so that 

they have the appearance of being abruptly terminated at this point. A specimen 

of this sort is illustrated by Norwood and Pratten (fig. 5a). Their figure, representing a section through the shell, seems to be a constructive one, based upon the 

abbreviated condition just.mentioned. The dorsal valve, when complete, instead of 

terminating with the beveled portion and leaving the ventral valve to project 

beyond, is, as one would expect, prolonged from the inner margin of the bevel, the 

prolongation conforming with that of the opposite valve and being almost in contact 

with it. 

In Colorado a certain tendency toward localization seems to characterize the 

distribution of shells of this group, a feature which, though it may be somewhat 

influenced by doubtful identifications of poor material, without doubt possesses some 

a Loc. cit., p1. 1, figs. 5b and 5c. 

• 
DESCRIPTIONS OF SPECIES. 379 

reality. It is unusual for two species to be associated in the collection from a single 

station, and even a certain amount of individuality is manifested in the different 

areas represented in our collections. 

The discussion of this species opens with the citation of the original reference 

of Margi/nifera wabashen8is, which is a sort of contradiction, since I do not consider 

the form in hand quite the same as Norwood and Pratten's species. The uncertainty 

I am under regarding their true relations must explain this action. 

Locality and horizon. —San Juan region (stations 2196, 2197, 2198, 2220, 2323); 

lower and middle portions of the Hermosa formation. Crested Butte district 

(stations 2302, 2303, 2306, 2316); Weber limestone and Maroon formation. 

MARGINIFERA INGRATA D. sp. 


Pl. V, figs. 12, 12a, 13, 13b. 


? 1875. Productus longispinus. White (non Sowerby), (pars) U. S. Geog. Geol. Surv. W. 100th Mer., 


Rept., vol. 4, p. 118, pl. 8, figs. 5c, d (not figs. 5a, b), (imprint of entire volume 1877). 

Carboniferous: East of 1Vtinersville and at Meadow Creek, south of Fillmore, Utah; Camp Cottonwood, Old Mormon road, Lincoln County, Nev.; near Santa Fe, N. Mex. 

? 1877. Productus longispinus. Meek (non Sowerby), U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 78, 

pl. 8, figs. 4, 4a. 

Carboniferous limestone: Fossil Hill, White Pine district, Nevada. 

I am uncertain of the specific relationships of this little shell and of the importance which should be attached to the characters which I am about to recount. 

Because of the former consideration, I have decided to describe it as a new species, 

and becapse of the latter I do so with some misgivings. The form which I shall take 

as my type is found in great abundance at station 2259 in,the Leadville region, but it 

occurs there only in the condition of casts. It is small, transverse, subrectangular. 

A transverse diameter of 15 mm. and a longitudinal of 11 mm. is somewhat above the 

average. The. curvature is strong, the ears distinct, large, quadrate, and somewhat 

upturned. The surface is marked by strong, moderately fine strite, about 7 in the 

space of 5 mm., and by fine, regular" concentric wrinkles over the posterior half of the 

shell. The spines are small and rather numerous. Mesial sinus absent. Submarginal ridges persistently well developed. 

This species can be distinguished from M. waba,shensis var. by reason of the 

strength of its strhe and concentric wrinkles, its lack of a mesial sinus, and its regular instead of geniculate curvature. 

From IL muricata it can be distinguished by being smaller, with larger, more 

distinct ears, finer striae, and much fewer spines. 

The features mentioned in the description, especially the strong wrinkles and 

striae conjoined with the absence of a sinus are relied on to distinguish this form 

from the other American species. 
380 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 


A form from Little Ella Hill (station 2253) in the Leadville region, which is 

illustrated by figs. 12 and 12a of Pl. V has been placed somewhat doubtfully with 

ingrata. It has a faint sinus and is less strongly arched than in the typical variety. Of the latter, the figured specimen shows an indistinct mesial depression, due 

in part, at least, to compression and fracture, and the concentric wrinkles and radial 

striae are unnaturally faint, because they appear upon an internal cast. It is very 

from Nevada identified by Meek in the same manner. 

Hermosa formation. Ouray (station 2195); Hermosa formation. Leadville district 

spinus 

probable that the shell from Sante Fe, N. Mex., identified by White as 

Locality and horizon.—San 

Sow., belongs to the species above described; rather less so the similar form 

Juan region (station 2225); middle portion of the 

P. longi­

(stations 2251 ?, 2253, 2259); base of the Weber formation. Crested Butte district 

(stations 2312, 2315); Weber limestone. Grand River region, Glenwood Springs 

(station 2193a). 

MARGINIFERA HAYDENENSIS 11. Sp. 

Pl. V, figs. 9 to 9c, 10 to 10b, 11 to 11a. 

Shell small. Ventral valve strongly curved and inclined backward, so that the 

posterior portion overhangs the hinge line, which is in some examples half way 

between the posterior outline and the front edge of the shell. The posterior portion 

is usually flattened, and the curvature geniculate. The width varies from about 

equal to the length to somewhat greater. The vault of the shell is large. The ears 

are usually small, but sometimes are large; quadrate, upturned. A more or less distinct mesial sinus is a persistent feature. Surface marked by longitudinal stri, 

which vary from strong to almost obsolete, and are very irregular. They are wavy, 

sometimes bifurcate or fasciculate, often nearly obsolete over the anterior half of the 

shell. Posterior portion marked by rather regular, faint, concentric wrinkles. 

Spines comparatively large and moderately numerous. 

Dorsal valve much smaller than the ventral, transverse, with flattened, recurved 

ears defined by ridges. Surface almost without ornamentation, concentric wrinkles 

being sometimes present, striae rarely. Submarginal ridges developed often to an 

exaggerated degree. 

Some examples of this shell are almost unique in the extent to which the posterior portion overhangs the hinge line, but others are far from displaying this 

peculiarity as well as the specimens figuyed. This peculiarity seems to arise from 

the condition of strong fore and aft curvature combined with the late period at which 

are especially close. The stria of the South American shell are said to be coarse, 

sl's 

the submarginal ridges are initiated. The character above noted allies 

while in this they are certainly fine. 

with M. capacii, d'Orbigny, and indeed, its affinities with that species generally 

_31: h,aydenen­
DESCRIPTIONS OF SPECIES. 381 

21. haydenen,sis in some of its phases resembles X. wabashensis, especially the 

geniculate variety. One, the least characteristic specimeh seen, can not be distinguished, except for size, from geniculate shells belonging to X. wabashensis, but 

average, and certainly well characterized, examples are smaller, less transverse, 

much more inflated, and with stronger submarginal ridges. The Colorado specimens 

referred to M. wabashensis are all, as I have taken occasion to remark, of the geniculate type, and somewhat smaller than is common in the Mississippi Valley. They 

are extremely similar to M. h,aydenensis when the latter is in its least typical expression, but they do not assume the characters of typical A1. haydenensis, and probably 

as a rule—certainly in many cases—begin the development of submarginal ridges at a 

much earlier period of their growth. Since the shell preserved in the average specimen is terminated by the submarginal ridges, the form referred' to AL wabashensis 

would be less highly arched and would very much less transgress the hinge line than 

typical Al. haydenensis. 

Locality.—Grand River region (station 2324), Grand River (station 2325). 

SPIRIFER Sowerby, 1815. 

SPIRIFER BOONENSIS Swallow ?. 

Pl. VI, figs. 1-1b, 2, 2a, 3. 

1860. 	Spirifer boonensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 646. 

Lower Coal Measures: Boone, Randolph, and Monroe counties, Mo. 

The Upper Carboniferous spirifers in our collection from Colorado can be 

assembled into three specific groups. One of these belongs to the type usually 

referred to Sp. carneratus Morton. Another is the form for which Marcou proposed 

the name Spirifer rockymontanus, and which Hall almost simultaneously described 

as Sp. opimus. The third I have referred rather doubtfully to Sp. boonensis Swallow. It is distinguished from Sp. rockymontanus by being larger and by having an 

extended hinge line. The largest specimen of Sp. rockymontanus observed by me 

has a transverse diameter of 26 mm., and the average individual has dimensions 

considerably less. A large specimen of Sp. boonensis measures 40 mm., though this, 

too, is somewhat above the average. 

Sp. boonensis, or the form which I have referred to that species, is of the imbrew 

type, transverse, with more or less extended cardinal extremities. Growth in older 

specimens is often by anterior and anterolateral additions, which gives the shell a 

subquadrate shape, but the hinge line remains characteristically its longest diameter. 

There are 4 to 6 plications on the fold and 3 to 5 on the sinus, with 12 or 13 lateral 

ones. These are crossed by a system of very fine imbricating concentric and radiating striae, the latter being frequently the more prominent. 

Sp. boonensis is known only from the original description, and it has not been 
382 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

figured. My identification can not, therefore, be considered conclusive. The Colorado shell agrees with Swallow's description in many particulars, but also presents 

divergencies from it. For instance, the hinge line in Sp. boonensis is said to be 

longer, shorter, or equal to the greatest width of the shell, but in the specimens 

from Colorado this dimension is, I believe, always greater than any other. Swallow 

also finds no signs of longitudinal strive, but these are always minute and faint, and 

might easily have been obliterated in his material. Sp. boonensis, furthermore, 

is described as being below the medium size, which is not true of the Colorado type, 

and as Sp. boonensis is compared by its author to Sp. opimus without any discrepancy 

in this regard being referred to, I judge that the typical material was considerably 

smaller than that now in my hands. 

In the comparison alluded to, Sp. boonensis is said to differ from Sp. opirnus " in 

the form of the area, the greater number and arrangement of the plications on the 

mesial fold and sinus, and the much greater number on the sides, and I find no signs 

of longitudinal striae." It is probable that the absence of longitudinal stria noted 

is due to individual peculiarities or to imperfect preservation. Hall describes Sp. 

opimus as having 8 to 10 simple plications, a statement which, as shown by his 

figures, should be modified so as to mean on either side of the fold or sinus. Swallow, 

however, could scarcely have understood it thus and written the words quoted above. 

Discounted in this way the differences pointed out by Swallow largely disappear, 

and one is almost ready to believe with Keyes that Sp. boonensis belongs in the 

synonymy of Sp. opimus Hall= Sp. rockymontanus Marcou. In this case the form 

under discussion probably represents an unrecorded species, for I believe that it 

should be distinguished from Sp. rockymontanus, and am acquainted with but one 

other Coal-Measure species which invites comparison. I refer to Sp. organensis, to 

which it seems closely allied. The latter, however, is larger, with more numerous 

plications both on fold and sinus and on the sides, the lateral ones, moreover, being 

disposed in fascicles of three or four. The last statement, quoted from Shumard, 

taken in connection with the rest of the description, would lead to the suspicion that 

Sp. organensis was a synonym of Sp. cameratus Morton, were it not for the somewhat obscure remark to be met with just beyond, that the stria are not arranged in 

fascicles as in the latter species. 

The affinities of the form which I have provisionally referred to Sp. boonensis, 

with the Waverly species Sp. centronatus, are very close. This is so true that it 

would not be easy on intrinsic characters to distinguish typical examples of the 

latter species from the Cuyahoga shale of Ohio, from the fossils occurring in Colorado. Sp. centronatus is usually a little smaller, a little more alate and mucronate, 

with two or three more lateral plications, while the minute surface ornamentation, 

though of the same character, seem to be somewhat coarser and stronger. On the 
DESCRIPTIONS OF SPECIES. 383 

surface of Sp. centron,atus the fine concentric striae dominate the radiating ones, but 

in Sp. boonensis the radiating striae seem to be dominant. However, these differences are by no means marked, and although exhibited by the few more perfect 

examples which have come before me, it is doubtful if they would be maintained in 

even the limited measure in which they there obtain, in a more extended series. 

Our collections show that this species is found at a number of localities, and the 

evidence seems to indicate that it is seldom associated with Sp. rockymontanus. My 

material is not satisfactory, as often but a single individual is known from a locality, 

and the preservation poor. Yet I believe that in most cases the determinations 

made would be substantiated if more abundant and better preserved specimens could 

be obtained. This species is especially abundant in the San Juan region, and its 

most typical representatives are found at the base of the Hermosa formation and in 

the Molas formation. Two examples from the base of the Hermosa are figured on 

Pl. VI. 

Locality and horizon.-San Juan region (stations 2187, 2197, 2201, 2202?, 2205, 

2209, 2213, 2214, 2219, 2243, 2246, 2247, 2284 ?, 2331 ?, 2332, 2334); Molas formation, 

lower, middle and upper portions of the Hermosa formation. Ouray (station 2194); 

Hermosa formation. Crested Butte district (station 2245). Grand River region, 

North Fork of Eagle River (station 2289); base of the Maroon formation. 

SPIRIFER ROCKYMONTANUS Marcou. 

Pl. XVI, figs. 4, 4a, 5, 5a, 6, 6a, 7, 7c. 

1858. (March.) Spirifer rockymontani (pars). Marcou, Geol. North America, p. 50, pl. 7, figs. 4c-4e, 

(non 4-4b?). 

Mountain limestone: Tigeras, N. Mex. 

1858. (December.) Spirifer opimus. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 711, pl. 28, figs. la, b. 

Coal Measures: Ohio, Maryland, Iowa, etc. 

1860. Spirifer subventricosa. McChesney, Desc. New Spec. Pal. Foss., p. 44. 

Coal Measures: Big Creek, Indiana, near New Harmony. 

1861. Spirifer rockymontani. Newberry, Ives's Colorado River Expl. Exped., p. 127. 

Upper Carboniferous limestone: New Mexico. 

1865. Spirifer subventricosa. McChesney, Illustrations New Spec. Foss., pl. 1, figs. 4a, b. 

1868. Spirifera opimus. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 35, pl. 1, figs. 4a, b. 

Coal Measures: Big Creek, near New Harmony, Ind. 

1874. Spirifera opima. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 15, pl. 1, fig. 4; pl. 2, 

fig. 7; pl. 4, fig. 12. 

Coal Measures: Bomjardim, Paredao, and Itaituba, Brazil. 

1875. Spirifer (Trigonotreta) opimus? Meek, Pal. Ohio, vol. 2, p. 329, pl. 19, figs. 14a, b, c, d, (e?). 

Coal Measures: Ohio, Illinois, Iowa, Missouri, West Virginia, and Rocky Mountains. 

1875. Spirifer rockymontanus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 134, 

pl. 11, figs. 9a-d. (Whole volume published in 1877. ) 

Carboniferous: North Fork of Lewiston Canyon, Oquirrh Range, and on west face of Oquirrh 

Range, Utah; near Santa Fe, N. Mex. 
384 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1876. 	Spirifer rockymontanus. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: Split Mountain Canyon and near Echo Park, Utah. 

Upper Aubrey group: Beehive Point, near Horseshoe Canyon, Utah. 

1877. Spirifer (Trigonotreta) opimus? Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4; p. 88, pl. 9, fig. 6. 

Carboniferous limestone: Six miles south of Promontory Station, Promontory Mountains, Railroad Canyon, Moleen Peak; Mount Nebo in Utah; Fossil Hill, White Pine district. 

1879. 	Spirifer rockymontanus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 32. 

Lower Coal Measures: White County and Crawford County, Ark. 

See also Spirifer keokuk. 4 -

1883. Spirifera opima. Hall, Rept. New York State Geol. for 1882, pl. (31) 56, figs. 4-7. 

Coal Measures: Iowa; Brazil, South America, 

1887. Spirifera opima. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 44, pl. 2, fig. 23. 

Coal Measures: Flint Ridge, Ohio. 

1888. Spirifera rockymontana. Keyes, Ac,ad. Nat. Sci. Philadelphia, Proc., p. 231. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Spirifera rockymontana f Whitfield, New York Acad. Sci., Ann., vol. 5, p. 584, pl. 13, fig. 20. 

Maxville limestone (Chester) : Newtonville, Ohio. 

1893. Spirifer opimus. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 27, 39, pl. 31, figs. 4-7. 

(Advance distribution in fascicles. ) 

Coal Measures: Bomjardim, Brazil. 

1894. Spirifer opimus. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 27, figs. 12, 13. 

Coal Measures: Iowa. 

1895. Spirifera rockymontana. Keyes, Missouri Geol. Surv., vol. 5, p. 84. (Date of imprint 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1895. Spirifer opimus. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 27, 39, pl. 31, figs. 4-7. 

Coal Measures: Iowa; Bomjardina, Brazil. 

1895. Spirifera rockymontana f Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 471, pl. 9, fig. 20. 

Maxville limestone (Chester): Newtonville, Ohio. 

1899. Spirifer rockymontanus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 578. 

Upper Coal Measures: McAlester quadrangle; Atoka quadrangle. 

From a study of Marcou's figures, I am inclined to believe that he had in hand 

two distinct species when Spirifer rockymonta/n,us was described. Figs. 4c, 4d, 

and 4e clearly represent a shell of the type which commonly passes under the name 

proposed by Marcou, and which Hall described as Sp. opimus. But the larger 

specimen figured by Marcou represents a different sort of shell. It has many bifurcating ribs, and is perhaps one of the short-hinged varieties of Sp. cameiatus or its 

allies, such as sometimes occur. I propose to restrict the name 

tanus 

and the Rocky Mountains. It has been found at many stations in Colorado, but 

name in its customary significance. 

Spirifer rockym,ontanus 

to shells of the type of Marcou's figures 4c, 4d, and 4e, thus retaining the 

has a wide distribution, both in the Mississippi Valley 

Spirifer rockymonseems to be especially abundant in the Leadville region. Specimens having all the 

characters of mature Sp. rockymontanus vary much in size. There are usually five 
DESCRIPTIONS OF SPECIES. 385 

or six plications on the fold and about ten lateral ones. The cardinal extremities 

are characteristically rounded. 

Locality and horizon-San Juan region (stations 2196, 2196b, 2196c, 2202, 2222, 

2223, 2229, 2323); middle portion of the Hermosa formation. Ouray (station 2195, 

2195a, 2195b); Hermosa formation. Crested Butte district (stations 2245, 2308, 

2315); 'Weber limestone. Lead ville district (stations 2253, 2254, 2259, 2261, 2267, 

2268, 2271, 2281, 2288, 2289 ?); base of the Weber formation and in the Robinson 

limestone. Grand River region (station 2288, 2289); bAe of Weber formation and 

base of the Maroon formation (?). 

SPIRIFER CAMERATUS Morton. 

1836. Spirifer cameratus. Morton, Am. Jour. Sci., (1), vol. 29, p. 150, pl. 2, fig. 3. 

Coal Measures: Ohio Valley. 

1852. Spirifer triplicata. Hall, Stansbury's Exped. Great Salt Lake, p. 410, pl. 4, figs. 5a-e. 

Carboniferous: Missouri. River above Weston. 

1852. Spirifer fasciger? Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 5, fig. 4. Not. Sp. 

fasciger Keyserling.) 

Carboniferous: Missouri River, near mouth of Keg Creek, and Plattsburg, Mo. 

1852. Spirifer meusebachanus. Roemer, Kreid. von Texas, p. 88, tab. 11, figs. 7a-c. 

Carboniferous: San Saba Valley, about 20 miles below the old Spanish forts, Texas. 

1852. Spirifer ineguicostatus f Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 586, pl. 5, fig. 6. 

(See specimens in U. S. Nat. Mus., Cat. Invert. Foss., 17954. ) 

Carboniferous limestone of Iowa: Skunk River,? Iowa. 

1856. Spirifer cameratus. Hall, Pacific Railroad Rept., vol. 3, p. 102, pl. 2, figs. 9, 12, 13 

Carboniferous: Pecos Village, N. Mex.. 

1858. Spirifer striatus var. triplicatus. Marcou, Geol. North America, p. 49, pl. 7, fig. 3. 

[Mountain limestone] : Abundant in the Rocky Mountains, especially at Pecos Village, at Tigeras, 

on the summit of the Sierra de Sandia, at Great Salt Lake, and at Vancouver Island. 

? 1858. Spirifer rockymontani (pars). Marcou, Geol. North America, p. 50, pl. 7, figs. 4-4b. 

Mountain limestone: Tigeras, N. Mex. 

1858. Spirifer cameratus. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 709, pl. 28, figs. 2a, b. 

Coal Measures: Ohio; Illinois; Iowa; Missouri; Nebraska; Santa Fe and Pimas Village, N. Mex. 

? 1859. Spirifer cameratus. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 27. 

Upper Coal Measures: Kansas. 

1859. Spirifer cameratus. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 391. 

Permian sandstone and White limeStone: Guadalupe Mountains. 

1861. Spirifer cameratus. Newberry, Ives'sColorado River Expl. Exped., p. 127. 

Upper Carboniferous limestone: Santa Fe and Peco8 Village, N. Mex. 

1866. Spirifer cameratus. Geinitz, Carb. and Dyas in Nebraska, p. 44. 

Carboniferous limestone: Bellevue and Plattsmouth, Nebr.; stage B, b1-, Nebraska City, and 

stage B b, b. Bennetts Mill, northwest of Nebraska City. 

1868. Spirifer. Rogers, Geol. Rept. Pennsylvania, vol. 2, pt. 2, p. 833, fig. 694. 

Western Coal Measures. 

14364-No. 16 03 25 
386 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1872. 	Spirifer cameratus. Meek, U. S. Geol. Surv. Nebraska, p. 183, pl. 6, fig. 12; pl. 8, fig. 15. 

Upper Coal Measures: Nebraska City, Nebr. 

Coal Measures: Eastern Ohio; West Virginia; Pennsylvania; Iowa; Kansas; Texas; New Mexico. 

1873. Spirifer cameratus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 573, pl. 25, fig. 7. 

Coal Measures: Illinois. 

1873. Spirifer, young of S. cameratus f Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, pl. 25, 

figs. 6a-c. 

Coal Measures. 

1874. Spirifer camerata. Derby, Cornell Univ., (Science.) Bull., vol. 1, No. 2, p. 12, pl. 1, figs. 1, 3, 

6, 9, 14; pl. 4, figs. 2, 15; pl. 4, fig. 5; pl. 5, fig. 11. 

Coal Measures: Bornjardim and Itaituba, Brazil. 

1875. Spirifer cameratus. Toula, Neues Jahrbuch Mineral., p. 240, pl. 7, fig. 3. 

Permo-Carboniferous: West coast of Spitzbergen. 

1875. Spirifer cameratus. Toula, Sitzb. der Kais. Akad. der Wissen. Wien, p. 543, pl. 2, figs. 2a, b. 

Carboniferous limestone: Nova Zembla. 

1875. Spirifer cameratus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 132, pl. 10, 

figs. la-d. (Whole volume published in 1877.) 

Carboniferous: Fossil Hill, White Pine County; Ely Range; Old Potosi mine, Lincoln County, 

and Egan Range, 35 miles south of Egan Pass, Nevada; Camp Apache, Maricopa County; Salt 

River; confluence of White Mountain and Black rivers; and Canyon Butte, Arizona; Oquirrh 

Range, near Camp Floyd; Lake Range on Fairfield road; west face of Oquirrh Range; North 

Fork of Lewiston Canyon, Oquirrh Range; cliff east of Bellevue; Meadow Creek, south of 

Fillmore; North Star district; Picacho Range; near Beckwith Spring, Cedar Range; Rock 

Canyon, Wasatch Range, near Provo; and Virgin Range, southwest of St. George, Utah. 

1876. Spirifer cameratus. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey Group: Confluence of Grand and Green rivers, Utah. 

1876. Spirifer cameratus. Newberry, Macomb's U. S. Expl. Exped. Santa Fe to Grand and Green 

rivers, p. 138. 

Upper Carboniferous: New Mexico and Utah. 

1876. Spirifer camerata. Meek, Simpson's Expl. Great Basin, Utah, p. 353, pl. 2, figs. 3a, b. 

Yellow limestone (Upper Carboniferous ?): Summit Spring Pass, east of Zuni Valley, etc. 

1877. Spirifer (Trigonotreta) cameratus. Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 91, pl. 9, 

figs. 2, 2a. 

Carboniferous limestone: Fossil Hill, White Pine district; Ruby Group, Nevada. Also, latitude 

39° 331 north, longitude 115° 12' west. 

1880. Spirifer cameratus. White, 2d Ann. Rept. Dept. Stat. and Geol. Indiana, p. 517, pl. 8, fig. 3. 

Coal Measures: Waterman, Parke County, Ind. 

1881. Spirifera camerata. White, Geol. Surv. Indiana, 10th Rept., p. 149, pl. 8, fig. 3. 

Coal Measures: Waterman, Parke County, Ind. 

1883. Spirifera camerata. Hall, Rept. New York State Geol. for 1882, pl. (32) 57, figs. 9-15. 

Coal Measures: Ohio; Illinois; Iowa; Missouri, etc. 

1884. Spirifer cameratus. White, Geol. Surv. Indiana, 13th Rept., p. 132, pl. 35, figs. 3-5. 

Coal Measures: Indiana. 

1887. Spirifer camerata. Herrick, Sci. Lab. Denison. Univ., Bull., vol. 2, p. 45, pl. 2, fig. 22. 

Coal Measures: Flint Ridge, Ohio. 

1888. Spirifera camerata. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 230. 

Lower Coal Measures: Des Moines, Iowa. 
DESCRIPTIONS OF SPECIES. 387 

1893. Spirifer cameratus. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 26, 38, pl. 32, figs. 9-15. 

(Advance distribution in fascicles.) 

Coal Measures: Ohio; Illinois; Missouri; Iowa. 

1894. Spirifer cameratus. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 26, figs. 7, 8. 

Coal Measures: Missouri; Illinois. 

1895. Spirifera camerata. Keyes, Missouri Geol. Surv., vol. 5, p. 83, pl. 40, figs, 5a-c. (Date of 

imprint, 1894.) 

Coal Measures: Clinton, Kansas City,. and Lexington, Mo. 

1895. Spirifer cameratus. Hall and Clarke, Pal. New York, vol.. 8, pt. 2, pp. 26, 38, pl. 32, figs. 9-15. 

Coal Measures: Ohio and Illinois; Missouri; Iowa. 

1896. 	Spirifer cameratus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 241. 

-Upper Coal Measures: Sebastian County, Ark.; Poteau Mountain, Indian Territory. 

Lower Coal Measures: Conway County, Ark. 

1896. Spirifer cameratus. Smith, Leland Stanford Junior Univ., Pub.; Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 31. 

Tipper Coal Measures: Sebastian County, Ark.; Poteau Mountain, Indian Territory. 

Lower Coal Measures: Conway County, Ark. 

1898. Spirifer cameratus. Beede, Kansas Univ. Quart., vol. 9, p. 21, pl. 5. 

1900. Spirifer cameratus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 99, pl. 12, figs. 5-5e. 

Upper Coal Measures: Kansas City, Lawrence, Lecompton, Topeka, Grand Summit, Kans. 

This species, like the preceding, has a long range and an extended distribution 

both in the Mississippi Valley and the Rocky Mountains. In Colorado it is frequently present, but has not yet come to light in the Leadville region. 

Among the material referred to this species variation more or less marked has 

been noticed' in the fineness of the striae and the degree to which they are gathered 

into fascicles. Nevertheless it has not been found practicable to establish satisfactory 

subdivisions. Most of the material examined, however, is imperfect in one way or 

another. 

_Locality and horizon.-San Juan region (stations 2198, 2200, 2201, 2205, 2210, 

2213, 2216, 2233, 2239, 2246, 2284, 2331, 2332); lower, middle, and upper portions of 

the Hermosa formation. Ouray (station 2194); Hermosa formation. Crested Butte 

district (stations 2293, 2303, 2305); Maroon formation. Grand River region (station 

2324), Glenwood Springs (stations 2329a, 2329b). Dolores River region, Sinbads 

Valley (station 2285); top of the Hermosa formation. 

SQUAMULARIA Gemmellaro, 1899. 

The name Reticularia was proposed by McCoy in 1844 a as a distinct genus, to 

which he gave the following characters: 

" General character.-Hinge line shorter than the width of the shell; cardinal area 

triangular; cardinal angles very obtusely rounded; mesial fold very slightly raised, 

or none; surface ornamented with either fine longitudinal or transverse striae, or 

most usually reticulated by both; dental lamellw perfectly parallel. 

a Synopsis Characters Carb. Limestone Foss. Ireland, Dublin, 1844, p. 142. 
388 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

very marked group, distinguished by its small size, reticulated or striated surface, 

McCoy, in which genus I formerly placed them, although they obviously formed a 

cata, S. lineata, S. microgemma, S. reticulata, S. decussata, 

or striated surface combined with the general form and cardinal area of 

"This beautiful little group includes all those spirifers analogous to the 

etc., having a reticulated 

Martinia 

S. imbriand very remarkably by the entire absence of the mesial fold in most of the species 

(in the one or two species which possess a trace of the mesial fold it is very slightly 

elevated). But the internal structure which I have recently seen in three of the 

species presents a very distinct and important character; the dental instead 

of converging toward the beak, as in all the other forms of Spirifer, are in those 

perfectly parallel to each other and to the central septum, in their whole length, 

thus confirming by a very interesting internal peculiarity the easily recognizable 

external characters. The genus is Carboniferous and Devonian." 

The term Reticularia seems to have gained but little acceptance, and the species 

distinguished under it were for the most part merged with the genus Spirifer. 

Waagen, however, in 1887 employed the name in a full generic sense, assigning 

distinctive characters both externally and internally. The distinctive external characters of this group mentioned by this author are the general orbicular shape, short 

hinge line, and the surface ornamentation, consisting of hollow, double-barreled 

spines. " Internally," he says, " the ventral valve is without any partition; neither 

dental plates nor a median septum is present. The muscular impressions are situated in an elongately oval groove. In the dorsal valve also not a trace of any partitions can be found; no septum nor shelly support of the dental sockets has been 

observed by me. A hinge plate does not exist."a 

In 1892 Hall and Clarke commented upon the term Reticularia as follows, assigning to it the same characters as Waagen: b 

" Reticularia (op. cit., pp. 128, 142). First species cited, Terebratula imbricata 

Sowerby=-Anomites lineatus Martin = Spirifer lineatus of authors. Shells of this 

type have the short hinge and the smooth or gently plicated surface characterizing 

ffartinia, and like the latter have neither dental plates nor septa on the interior. 

The name is based upon a species whose surface is covered with concentric fimbrite 

of double-barreled spines bearing single rows of lateral spinules, and must probably 

be restricted to this type of exterior, as in the more strongly plicated of the fimbriated spirifers the surface spines are simple." 

These authors, however, reduce the value of this term below that of a subgenus, 

and employ it as a collateral or synonymic title for the group of spirifers which they 

call "the duplicispinei." To this group Hall and Clarke refer "S. jimbriatus Conrad, 

S. subundiferus Meek and Worthen, of the Hamilton group; S. hirtus White and 

Whitfield, of the Choteau limestone; S. pseudolineatas Hall, of the Kinderhook and 

Keokuk groups; S. setigerus Hall, S. lineatus Martin, and S. perplexes McChesney, 

a Mem. Geol. Surv. India, Palmontologia Indica, Salt Range Fossils, vol. 1, 1887, p. 538. 

b Pal. New York, vol. 8, pt. 2, 1894, p. 20. 
DESCRIPTIONS OF SPECIES. 389 

of the Coal Measures." Now, it is evident that internally the shells included under 

Reticularia by McCoy are very different from those which the usage of Waagen and 

of Hall and Clarke embrace. McCoy in 1854, commenting upon Spinfer lineatus, 

speaks again of the dental lamellae and septa of Reticularia in the following terms: 

"This species, from the peculiar structure of the surface and the slight divergence 

of the dental lamella3 with their strong mesial septum, was originally combined in 

my Synopsis (of Garb. Foss.) with the S. imbricata, S. reticulata, S. microgernma, 

etc., into a little group called Reticularia. There is a fine submedial impressed 

line, apparently a fracture, visible in many specimens from the beak to the front 

margin." a 

Waagen, after quoting this passage, says: 

" Now, it does not seem to me probable that the British specimens of Reticularia 

possess an internal structure different from that of the specimens from Vise, with 

which the Indian specimens entirely agree. It seems far more probable that there 

has occurred a mingling of different things by McCoy, and that he described the 

above characters from a specimen of lifartiniopsis, or something like it. Nevertheless, it would be very desirable to learn more particularly about these British fossils."6 

Examining our American species of this type, I find that the Mississippian 

forms, without exception, so far as my examination goes, possess internal structures 

as described by McCoy, while the Upper Carboniferous ones are structureless,.as in 

the group described by Waagen and by Hall and Clarke. The species referred to 

Reticularia by McCoy were found in strata of the age of our Mississippian series, 

while Waagen's material from India came from high up in the Upper Carboniferous, 

or Permian. It thus appears that the groups of shells characterized by these internal 

differences are characterized also by a difference of occurrence in the geologic 

column. Hall and Clarke evidently handled species of both stratigraphic occurrences 

and representatives of both types of internal structure, but apparently they passed 

over these, to me, important distinctions in favor of a certain agreement in genpral 

external expression. 

I think there can be no doubt to which group the term 1?eticula/ria was originally 

applied, and I propose to restrict it to the original implication and to employ a 

distinct term for the shells without septa or dental lamellae, as Waagen has described 

Reticularia. 

I had, in manuscript, proposed for this group a distinctive name, when there 

came into my hands a work by Gemmellaro,c in which he proposes the name 

Squarnulana for some fossils very similar to those which it was my purpose to 

include •in a new genus. A full and, in the main, literal translation of Gemmellaro's 

remarks upon Squamulana is here appended. 

a British Paleozoic Rocks and Fossils, Sedgwick and McCoy, Cambridge, 1854, p. 430. 


b Loc. cit., p. 538. 


C La Fauna dei Calcari con Fusulina, fasc. 4, pt. 1, p. 325, Palermo, 1898-99. 

390 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

In the Fusulina limestones of Sicily there is found a group of spiriferoids which 

differs from the known genera. These fossils have an ornamentation which in some 

ways recalls that of Athyris. However, the complete absence of dental and septal 

plates, and the form of the brachial apparatus, which I was able to observe in two 

specimens, have convinced me that they differ from that genus; while, on the other 

hand, they are more closely allied to the Martiniw and the Reticulariw. These 

spiriferiods, to which I give the generic name Squamulamia, have the following 

characters. 

They are thick shells, imperforate, and ornamented with thin, concentric laminae, 

narrowly undulated, squamose, fringed, and imbricated one above the other. Here 

and there, at nearly equal distances, some of these laminae are thicker, more prominent, welt-like, and with margins more distinctly fringed. The surface of the shell 

shows numerous scars and imprints of spines, particularly distinct on the edge of the 

varices. The hinge line, which is much shorter than the major breadth of the shell, 

is slightly arched. The area is often indistinct. Beneath the beak of the ventral 

valve is seen the delthyrium, which is triangular and narrow. The epidermis is not 

punctate. 

They have no dental or septal laminae whatever. The crural plates start from 

the hinge margin of the dorsal valve, more specially from the internal face of the 

dental fossettes. These plates at first diverge, forming an elbow, and then converge 

toward the median line, approaching each other so as to circumscribe in the internal 

subapical region a space with pentagonal outline. Having come close together and 

almost in contact, they give rise to the descending laminae, which extend parallel along 

the median line as far as the anterior third of the length of the dorsal valve. Thence 

they diverge toward the sides, to give rise to the formation of the laterally directed 

spiral cones. The latter are large enough almost to fill the internal cavity of the 

shell, and are the result of broad gyrations, few in number. 

The relationship of the Squamulariw with the ilfartinice and the Reticulariw is 

close, but not so intimate that they can be embraced within the same generic limits. 

The 111-artiniw have a punctate epidermis, and never present the ornamentation peculiar to these fossils. When they are provided with lamellose, concentric striae, as, for 

example, llfartinia lamellosa Gemm., these strive are neither fringed nor wavy, and, 

with the exception of llfartinia distefanoi, lack spines. As regards their brachial 

apparatus also there are differences. In the _Martini w th crural plates converge 

abruptly toward the median line, and leave between them in the rostral region a 

larger or smaller triangular space. The descending lamine are close together for a 

short distance, and then diverge toward the sides to give rise to the spiral cones, 

which are rather small. 

As regards their affinity with the Reticulariw, there is some analogy:in the conformation of the various parts of the apical region and in the sum total of their 
DESCRIPTIONS OF SPECIES. 391 

ornamentation, but certainly this analogy is of no importance in view of the diversity that exists between the characteristic structure of the shell surface of these 

species and that of the Squamulariw. As regards their internal characters, the 

spiral cones of the Reticulariw ordinarily have the apex directed toward the hinge 

line, and in the species in which it is turned sideways, as in the Squamularice, the 

crura do not form an elbow, but, on the contrary, have very nearly the same direction 

as in 3fartinia, that is to say, they converge directly toward the median line, leaving 

in the internal infra-apical region a larger or smaller triangular space, and the 

descending laming do not run parallel for a long distance, but, having approached 

each other, suddenly diverge toward the sides, and give rise to the spiral cones. 

ularia rotundata 

San Benedetto, in the vicinity of Palazzo-Adriano, in the province of Palermo. 

These fossils belong to two species, to which I have given the names of 

The SquamUlariw 

Gemm. and 

were found in the compact Fusulina limestone of the Rock of 

Squamularia dieneri Gemm. 

SquamThe first species described, which must be taken as the type, is Squamularia 

rotundata Gemm., and upon its characters accordingly rests the validity of Gemmellaro's genus. It is quite evident that this author did not apprehend the more 

obvious differences which distinguish Beticularia from his species of Squamularia, 

and that he considered McCoy's genus to be devoid of dental lamella and septa. If 

the characters by which he sought to distinguish Squamularia from Reticularia are 

valid, there can be no doubt but that the forms referred by him to Beticularia 

constitute a yet undescribed genus. But I very much doubt the importance of the 

characters to which Gemmellaro calls attention, and believe that the real characters 

of distinction are the septa and dental plates which are present in Beticularia and 

absent in Squamularia. This opinion seems to be confirmed by Schellwien, who 

regards Squamularia as a synonym of Reticularia, the latter name evidently being 

employed in the sense in which Waagen and Hall and Clarke interpret it. 

To Squamularia, therefore, would belong all of Waagen's species of Reticular' ia 

and also those of Gemmellaro himself, together probably with most American, 

European, and Asiatic Upper Carboniferous types that have been included by authors 

under McCoy's genus. More specifically with regard to our American species, 

Squamularia will include only, so far as I know, the two Upper Carboniferous 

forms Becticularia perplexa McChesney and Reticularia guadalupensis Shumard, 

both of which I have examined and know to be without septa or dental lamellae. 

To Reticularia will belong the Mississippian species R. Clara Swallow (?), R. 

cooperensis Swallow, R. lineatoi des Swallow (?), R. pseudolineata Hall, B. setigera 

Hall, R. temeraria Miller ( ?), R. tenuispinata Herrick, and R. translate Swallow (?). 

These Mississippian forms are usually characterized by two powerful dental plates 

in the ventral valve, and a median septum in both dorsal and ventral valves. The 

dorsal septum varies in degree, being sometimes low and sometimes moderately high. 
392 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

The dental lamellae are often not quite parallel, as they are described by McCoy in 

Reticularia, but this difference I can not regard as of prime importance. The type 

of Reticularia, as already pointed out by Hall and Clarke, will have to be taken as 

R. imbricata Sowerby, the first species included by McCoy under his genus. 

Squamularia and Reticularia stand related to one another very much as do 

_,Ilartinia and llfartinio_psis, but with this difference, that while the Reticulariw with 

internal plates precede those without, the Martinias with internal structures were a 

late development. 

Hall and Clarke, as already mentioned, do not apparently give Reticulairia the 

place of even a subgenus, while Waagen allows it full generic rank. It seems to 

me that the names liartinia, Martiniopsis, Reticularia, and Squamularia stand about 

on a par in genetic station, and while I am in doubt about their value as full generic 

groups, it seems to me that they should at least be considered subgenera of Spirifer. 

SQUAMTJLARIA PERPLEXA McChesney. 

Pl. VI, figs. 8, 8a, 9 to 9b, 10, 10a, 11 to 11c. 

1855. Spirifer lineatus. Shumard, Missouri, Geol. Surv., p. 216. (Not Sp. lineatus Martin.) 

Coal Measures. 

1856. Spirifer lineatus. Hall, Pacific Railroad Rept., vol. 3, p. 101, p1. 2, figs. 6-8. (Not Sp. lineatus 

Martin, 1809.) 

Carboniferous: Pecos Village, N. Mex. 

1858. Spirifer lineatus. Marcou, Geol. North America, p. 50, pl. 7, figs. 5-5c. (Not Sp. lineatus 

Martin.) 

Mountain limestone: Pecos Village and Tigeras, N. Mex. 

1859. Spirifer lineatus. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 28. 

Upper Coal Measures: Leavenworth, Kans. 

1860. Spirifer perplexa. McChesney, Desc. New Pal. Foss., p. 43. 

Upper Coal Measures: Almost every part of the country where rocks of that age occur. 

1861. Spirifer lineatus. Newberry, Ives's Colorado River Expl. Exped., p. 127. (Not Sp. lineatus 

Martin.) 

Upper Carboniferous: Cherty limestone west of Little Colorado River; vicinity of Santa Fe, 

N. Mex. 

? 1864. Spirifer lineatus. Meek, Pal. California, vol. 1, p. 13, pl. 2, figs. 6-6d. 

Carboniferous: Bass's Ranch, Shasta County, Cal. 

1866. Spirifer lineatus. Swallow, Acad. Sci. St. Louis, Trans., vol. 2, p. 408. (Not Sp. lineatus Martin.) 

Coal Measures: Mississippi Valley. 

1866. Spirifer lineatus var. perplexa. Swallow, Acad. Sci. St. Louis, Trans., vol. 2, p. 408. 

Coal Measures: Mississippi Valley. 

1866. Spirifer lineatus var. striato-lineatus. Swallow, Acad. Sci. St. Louis, Trans., vol. 2. p. 408. 

Upper and Middle Coal Measures: Missouri. 

1872. 	Spirifer lineatus? Meek, U. S. Geol. Surv. Nebraska, pl. 2, figs. 3a, b. 

Upper Coal Measures: Platte River, Nebraska. 
DESCRIPTIONS OF SPECIES. 393 

1874. Spirifera (Martinia) perplexa. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 16, pl. 3, 

figs. 27, 39, 40, 45, 50; pl. 8, fig. 13, 

Coal Measures: Bomjardim and Itaituba, Brazil, and River Pichis, Peru. 

1881. Spirifera (Martinia) lineata? White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Appendix, p. xii. 

Coal Measures: Upper Mississippi River region. 

1882. Spirifer (Martinia) lineatus. White, Geol. Surv. Indiana, 11th Rept., p. 372, pl. 42, figs. 4-6. 

Coal Measures: Eugene, Ind. 

1884. Spirifer (Martinia) lineatus. White, Geol. Surv. Indiana, 13th Rept., p. 133, pl. 27, figs. 4-6. 

Coal Measures: Fountain, Park, Vermilion, Vigo, Sullivan, Gibson, Pike, Knox, Posey, Vanderburg, and Warrick counties, Ind. 

1886. Spirifer lineatus? Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 453. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Spirifer lineatus? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, p. 269. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Spirifera (Martinia) lineata? Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 46, pl. 1, figs. 

13a-c. 

Coal Measures: Flint Ridge, Ohio. 

1888. Spirifera lineata. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 230. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Spirifer (Martinia) lineata. Whitfield, New York Acad. Sci., Ann., vol. 5, p. 603, pl. 16, figs. 3-5. 

Coal Measures: Hocking County, Ohio. 

1893. Spirifer lineatus. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 10, 11, 17, 21, 30, 39, pl. 38, 

figs. 2, 4, 7, 8. (Not Sp. lineatus Martin.) (Advance distribution in fascicles.) 

Coal Measures: Iowa. 

1894. Spirifera perplexa. Keyes, Missouri Geol. Surv., vol. 5, p. 84. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1895. Spirifera (117artinia) lineata. Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 488, pl. 12, figs. 3-5. 

Coal Measures: Hocking County, Ohio. 

1895. Spirifer lineatus. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 10, 11, 17, 21, 30, 39, pl. 38, 

figs. 2, 4, 7, 8. (Not Sp. lineatus Martin. ) 

Coal Measures: Iowa. 

1899. Reticularia perplexa. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 577, pl. 72, 

fig. la. 

Upper Coal Measures: McAlester quadrangle. 

1900. Reticularia perplexa. Beede, Univ. Geol. Surv. Kansas, Rept., p. 102, pl. 12, figs. 4-4c. 

Upper and Lower Coal Measures to base of Permian: Fort Scott, Iola, Lawrence, Topeka, Kans. 

This species is more numerous, if not more widely distributed, perhaps, than any 

in the collection, having been found at no less than 30 localities. While perfect and 

well-preserved examples could scarcely be mistaken, in practice it has not always 

been found an easy matter to distinguish individual specimens when poorly preserved 

or imperfect, or both, from Soninula subtilita, or in the case of young examples, 

from Amboccelia planiconvexa. The peculiarities of surface ornamentation, which in 

exfoliated specimens or even in internal casts can usually be relied on to distinguish 
394 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

this species, are sometimes so obscured that the shell appears quite smooth. Very 

small shells in this condition bear a strong resemblance to Amboccelia planiconvexa, 

the character which was most used in distinguishing them being the convexity of 

the dorsal valve. Some of the specimens from the forks of Cement Creek, in the 

Crested Butte quadrangle (station 2318), especially, I rather suspect, if more perfectly 

preserved would prove to be large examples of Amboccelia. 

McChesney states that this species seldom attains a greater diameter than fiveeighths of an inch. This is true as a rule in the collection studied, but specimens have 

been noted both from Colorado and the Mississippi Valley which measure 20 mm. 

(over three-fourths of an inch) and more. Considerable variation has also been noted 

in frequency of the bands of spines with which the surface was covered. In some 

specimens the spinous >rows are less than 1 mm. apart, and in others they are separated by intervals of 3 mm. Usually the widely spaced bands are found upon the 

larger-sized specimens. All degrees occur between specimens with distant bands 

and those with proximate ones, and I believe that this character can not be given 

even varietal value. 

Locality and horizon.-San Juan region (stations 2196, 2196a, 2196b, 2196c, 2197, 

2202, 2208, 2213, 2220, 2221, 2222, 2223, 2224, 2225, 2233, 2238, 2283, 2286, 2301, 

2332); lower, middle, and upper portions of the Hermosa formation. Ouray (station 

2194); Hermosa formation. Crested Butte district (stations 2245, 2291, 2292, 2293, 

2297, 2299, 2300, 2303, 2305, 2306, 2316, 2318); Weber limestone and Maroon formation. Leadville district (stations 2260, 2272 ?); upper part of Weber formation and 

Robinson limestone. 

AMBOCCELIA Hall, 1860. 

AMBOCCELIA PLANICONVEXA Shumard. 

1855. Spirifer planoconvexa. Shumard, Missouri Geol. Surv., p. 202. 

Upper Coal Measures: On Missouri River, near mouth of Platte River. 

1859. Spirifer planoconvexa. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 28. 

Upper Coal Measures: Manhattan, Juniata, and Leavenworth, Kans. 

1860. Ambocelia gemmula. McChesney, Desc. New Pal. Foss., p. 41. 

Coal Measures: Peoria and Bureau counties, Ill. 

1864. Spirifer (Martinia) planoconvexa. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, 

No. 172, pt. 1, p. 20, figs. a-e, ibidem, 1865, pl. 1, fig. 3. 

Coal Measures: Manhattan and Upper Mill Creek, Kansas. 

1866. Spirifer plano-convexa. Geinitz, Carb. and Dyas in Nebraska, p. 42, tab. 3, figs. 10-18. 

Upper Coal Measures, Plattsmouth, Nebraska City, Nebr. • 

1868. Martinia planoconvexa. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 34, p1. 1, 3a-c. 

Coal Measures: Peoria and Bureau counties. Ill. 
DESCRIPTIONS OF SPECIES. 395 

1872. Spirifer (Martinia).planoconvexus. Meek, U. S. Geol. Surv. Nebraska, p. 184, pl. 4, figs. 4a, b, 

pl. 8, figs. 2a, b. 

Upper Coal Measures: Nebraska City, Bennett's Mill, Wyo.; Cedar Bluff, Rock Bluff, Plattsmouth, Brownville, Otoe City, Rulo, Bellevue, and Omaha, Nebr. 

Coal Measures: Iowa; Missouri; Kansas; Pittsburg, Pa.; West Virginia. 

1874. Spirifera (Martinia) planoconvexa. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 19, 

pl. 8, figs. 12, 16, 18; pl. 9, fig. 7. 

Coal Measures: Bomjardim and Itaitdba, Brazil, and Pichis River, Peru. 

1875. Spirifer (Martinia) planoconvexus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, 

p. 135, pl. 10, figs. 3a-c. (Whole volume published in 1877.) 

Carboniferous: Near Santa Fe, N. Mex.; Elko Mountain, Nevada. 

1884. Spirifer (Martinia) planoconvexa. White, Geol. Surv. Indiana, 13th Rept., p. 134, p'. 32, figs. 

23-24. 

Coal Measures: Indiana. Occurs from Virginia to Utah and New Mexico. 

1887. Spirifera (Martinia) planoconvexa. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 46, pl. 1, 

fig. 12. 

Coal Measures: Flint Ridge, Ohio. 

1893. Amboccelia planoconvexa. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 58, pl. 39, figs. 10-15. 

(Advance distribution in fascicles.) 

Coal Measures: Springfield, Ill.; Manhattan, Kans. 

1894. Amboccelia planoconvexa. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 31, figs. 14-17. 

Coal Measures: Illinois; Kansas. 

1895. Spirifera planoconvexus. Keyes, Missouri Geol. Surv., vol. 5, p. 85. (Date of imprint, 1894). 

Upper Coal Measures: Kansas City, Mo. 

1895. Amboccelia planoconvexa. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 56, pl. 39, figs. 10-15. 

Coal Measures: Springfield, Ill.; Manhattan, Kans, 

1900. Amboccelia planoconvexa. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 101. 

Upper and Lower Coal Measures: Fort Scott, Fredonia, Eudora, Lawrence, Lecompton, Topeka, 

Emporia, Kans. 

Small shells more or less closely resembling this species were collected at several 

localities. The nature of the surface ornamentation or other characters has convinced me that they are merely young individuals of Reticularia, with large forms of 

which they, are in most cases associated. Occasionally the evidence was less conclusive than others, but using such characters as the fossils still retained, I have identified A. planiconvexa at but two localities, where, however, its presence is tolerably 

certain. It is nevertheless possible that this species has really a somewhat better 

representation than I was led to believe. It is abundant at station 2282 in the San 

Juan region (Rico quadrangle, Sandstone Mountain section). 

Locality and horizon.--Sanjuan region (stations 2220, 2282); middle portion of 

the Hermosa formation. 
396 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

SPIRIFERINA d'Orbigny, 1847. 

SPIRIFERINA CAMPESTRIS White. 

1874. Spiriferina spinosa f. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 23, pl. 6, figs. 

8, 13, 14. 

Coal Measures: Itaituba, Brazil. 

1874. Spiriferina spinosa var. campestris. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. 

Invert. Foss., p. 21. 

Carboniferous Coal Measures: Near Santa Fe, N. Mex.; Camp Cottonwood, Lincoln County, Nev. 

1875. Spiriferina octoplicata. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 139, 

pl. 10, figs. 8a-c. (Whole volume published in 1877: ) 

Carboniferous: Near Santa Fe, N. Mex.; Camp Cottonwood, Lincoln County, Nev. 

1877. Spiriferina sp. undet. Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 84, pl. 8, fig. 5, 5a, 5b. 

Carboniferous limestone: Railroad Canyon, Diamond Mountains, Nevada. 

1877. Spiriferina gonionota. Meek, ibidem, at end of description (p. 85). 

Carboniferous limestone: Railroad Canyon, Diamond Mountains, Nevada. 

1884. Spiriferina cristata. Walcott (pars), U. S. Geol. Surv., Mon., vol. 8, p. 218, pl. 18, fig. 13 (not 

fig. 12). 

Lower Carboniferous: On the east slope of a small conical hill on the east side of Secret-Canyonroad Canyon, Eureka district, Nevada. 

Upper Carboniferous limestone: Western slope and foothills of Diamond Peak, Eureka district, 

Nevada. 

1896. Spiriferina cristata. Smith (pars), Am. Phil. Soc., Proc., vol. 25, p. 242. 

Lower Coal Measures: Conway County, Ark., SW. of NW. / of sec. 29, T. 6 N., R. 16 W. 

Upper Coal Measures: Sebastian County, Ark., sec. 12, T., 8 N., R. 32 W. 

Poteau Mountain, Indian Territory. 

1896. Spiriferina cristata. Smith (pars), Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins 

Seaside Lab., No. 9, p.. 32. 

Lower Coal Measures: Conway County, Ark., SW. I of NW. / of sec. 29, T. 6 N., R. 16 W. 

Upper Coal Measures: Sebastian County, Ark., sec. 12, T. 8 N., R. 32 W. 

Poteau Mountain, Indian Territory. 

The presence in our Upper Carboniferous faunas of members of the genus 

Spiriferina possessing two quite different types of surface ornamentation has been 

long, though imperfectly, known. One type which is much the more common has 

the ribs crossed by numerous fine, concentric, lamellose, imbricating striae or crenulations. It was for a widely distributed representative of this division that Shumard 

proposed in 1855 the specific name Spiriferina kenhcckyens;s.cc In the other type, 

which is rarer, the concentric markings are comparatively inconspicuous and the 

surface is more or less abundantly covered with postules or short spiniform projections. For a species of this type Meek suggested, in 1877, the name Spiriferina 

gonion,ota,b although, as the surface ornamentation of his typical specimen was not 

shown, he laid stress rather upon other characters in discriminating it from the 

a First and Second Ann. Rept. Geol. Surv. Missouri, pt. 2, p. 203. 


bUU. S. Geol. Expl. 40th Par., Rept., vol. 4, 1877, p. 84, p1.8, figs. 5, 5a, 5b. 

DESCRIPTIONS OF SPECIES. 397 

more common ,Sp. kentuckyensis. The shells which Derby,a in 1874, and Walcott,' 

in 1884, in the one case from Brazil and in the other from Nevada, identified as Sp. 

spinosa, and also that from New Mexico which White c published in 1875 under the . 

name of Sp. octoplicata, undoubtedly belong here. As the year previous, in a 

preliminary report upon the collections of the One Hundredth Meridian Survey, 

pestris, 

White had distinguished this form from 

Nevada, and Texas, and includes the types of Meek, of White, and of WalThe material studied by me consists of fossils from Colorado, New Mexico, 

it has been retained here, but in a specific sense. 

Sp. spinosa by the varietal name earncott. The species may be briefly described as follows: The shell is rather large, 

transverse, the hinge line being usually as broad or a little broader than the 

width of the shell below. Dorsal valve moderately convex, ventral valve rather 

elevated with a high area, which is more or less strongly incurved. Fold and sinus 

simple; on either side are four or five lateral plications. The latter are thin, high, 

and subangular, and so are the reverse plications and also the fold and sinus, which 

are only distinguished by being somewhat more elevated than the others. The 

surface is essentially smooth. Several concentric growth lines, more or less elevated 

and lamellose, are frequently present, but they are sometimes practically absent, and 

never in frequency and regularity produce an effect similar to the lamellose ornamentation of shells of the type of Spiriferin,a kentuckyensis and its allies. These 

markings are usually inconspicuous, and the most striking character of the surface 

consists in its being covered by numerous rather coarse and sparse hollow spines, 

which, either by nature or by accident, are seen to be open at the outer end. The 

spines are more thickly distributed in some individuals than in others, but the range 

of variation is not excessive. In some, though not in all, a number of spines in the 

ventral sinus are serially arranged and more or less connected by a delicate ridge. 

Nothing to correspond with this has been noticed on the fold. The surface under 

different conditions of preservation presents appearances so unlike that I was nearly 

misled into subdividing the species into at least two groups varietally distinct. The 

outer shell layer, which is retained only on well-preserved specimens, seems to be 

itself impunctate, and often completely masks the punctate structure of the shell 

below. It is nearly smooth, except for the tubular excrescences above referred to, 

being marked by delicate, almost invisibly fine growth lines. Under slightly 

different conditions of preservation the appearance of the surface is very much 

changed, and the shell appears to be covered by innumerable closely set minute 

spinules, which are both much smaller, more numerous, and more thickly arranged 

than the large ones on the preceding. This appearance seems to be due to the 

removal of the delicate superficial layer and with it the larger spines. The spinules 

a Cornell Univ., Bull., vol. 1, No. 2, 1874, p. 23, p1. 6, figs. 8, 13, 14. 


b U . S. Geol. Surv., Mon., vol. 8, 1884, p. 218, pl. 18, fig. 13. 


0 U. S. Geog. Geol. Sum W. 100th Mer., Rept., vol. 4, 1877, p. 139, pl. 10, figs. 8a-8c. 

398 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

are evidently related to the punctate structure of the shell, each of the spinules 

representing a pore. Whether they are merely the tiny plugs of calcite which 

filled the perforations in the shell, the latter having been worn from about them, 

or whether the shell projected around each aperture in the shape of a minute 

tube, I have not been able to assure myself, but I am inclined to the latter opinion. 

The differences just pointed out are so striking and in the main so uniform that 

at first I was for recognizing the shells which were characterized by them as 

distinct species. Later, associated with shells of the first type were found a 

number of individuals intermediate between it and the other, and continued search 

resulted in finding on some specimens of Spiriferhia spinosa, a species in the 

closest degree related to that under discussion, both kinds of surface developed 

in patches upon the same valve, the one condition clearly resulting from the other 

by a process of erosion. I think, therefore, that there is no room for doubt that 

the appearances described are conditioned entirely by preservation. The intermediate style of markings mentioned consisted of a surface thickly covered with 

fine spinules, among which at intervals were distributed larger ones of the usual 

size, the impunctate, striated, outer layer having been removed without destroying 

the larger spines. Often when the shell is silicified the outer layer is missing 

and the coarsely punctate structure is brought prominently to view. The shell 

then has a reticulated, almost spongy appearance. This is the condition of the 

type specimen of Spiriferina gonionotus. The specimen from Camp Cottonwood 

figured by White as Sp. octoplicata and the other material from the same locality 

resemble Meek's type very closely. These specimens are not silicified but exfoliated, showing only the strongly punctate shell structure. The other specimen 

figured by White is from Santa Fe, N. Mex. It and the rest of our Santa Fe 

material shows only the minute, closely set spinules. The specimen figured by Walcott was collected from the Pancake Mountains, north end of Coal Hill, White Pine 

County, Nev. It is silicified and shows the large spines and, indistinctly, the 

coarsely punctate shell structure. Other specimens from Coal Hill have the surface 

better preserved, but in the matter of shape are less perfect. Some of them show 

the large spinules, impunctate outer layer, and fine concentric markings above 

referred to, and others are intermediate between the two main types of preservation 

which I have been able to distinguish, having the large spines of the one distributed 

among the fine spinules of the other. My Colorado material is also exfoliated, but 

belongs with little doubt to this division of the genus. The type specimen of Sp. 

gonionotus is somewhat peculiar in its shape, and differs from the rest of the material by some of the same characters by which Meek sought to distinguish it from 

Sp. kentuckyensis and Sp. octoplicata. These are chiefly its highly inflated valves 

and prominent fold, which, projecting in front, gives to the outline a rather mark-
DESCRIPTIONS OF SPECIES. 399 

edly triangular shape. The usual outline of the dorsal valve is transversely subsemicircular, but Meek's specimen agrees with others from the same region in so 

many ways that I am disposed to regard its peculiarities as of an individual nature 

and due in part to old age. It is with considerable personal confidence, therefore, 

that I refer all this material to Sp. campe,stris. 

the type specimen was removed, he was not able to avail himself of these characters 

in making comparisons. The differences pointed out by Meek are veritable ones, 

but if 

plicata 

Meek sought to distinguish 

I 

by reason of certain differences in shape. As the surface ornamentation of 

am not at fault in referring to his species other material from Nevada and 

Sp. gonionotus from Sp. kentuckyensis and Sp. octoadjacent territory, they are not constant and must be referred to individual peculiarities. On the other hand, on the same supposition, well-preserved specimens 

among the other material show surface characters which distinguish this species 

without a trace of doubt from Sp. kentuckyensis and possibly also from Sp. octoplicata. 

White identifies specimens originally described as Sp. spinosa, var. compestris with 

only a variety of 

explained, I believe that their absence is owing to circumstances of preservation. 

tuckyensis 

the spines which characterize Norwood and Pratten's species. As I have already 

Sp. octoplicata. 

and recognizes its affinities with 

Sp. octoplicata. 

He very correctly regards his material as distinct from 

He believes that his specimens differ in lacking 

Sp. spinosa, which, he considers, may be 

Sp. kenThe form from Itaituba, Brazil, which Derby identifies with Sp. spinosa, probably 

belongs in the synonymy of White's species. One of his specimens showed very 

distinctly a rib in the sinus of the ventral valve, a character which he justly remarks 

is not found in Sp. spinosa, nor does it occur in the material of. Sp. gonionota which 

has been studied by me. He further states regarding the surface ornamentation that 

it shows traces of spines, but not of the regular concentric lamellae characteristic of 

Sp. spinosa. The latter, however, is evidently a lapsus calami, for this is a character 

by which Sp. spinosa is distinctly not characterized. Walcott also identifies his 

fossils with Sp. spinosa, figuring a specimen from the Coal Measures and one 

from the Chester to support this view, but he refers Sp. spinosa to Sp. cristata as a 

direct synonym and places Sp. kentuckyensis Shum. in the same category. It is not 

unlikely that the identification of this form with. Norwood and Pratten's species is 

correct, but while it superficially resembles Sp. kentuckyensis, the character of the 

surface ornamentation is so unlike that there can be no question about the propriety 

of recognizing them as distinct species. The relations of Sp. kentuckyensis and Sp. 

cristata have been discussed in another place. It seems probable that iSp. cristata 

does not belong to the spinose section of the genus, a point upon which L have been 

unable certainly to inform myself; but if it does, and not otherwise, comparisons 

between Sp. campestris and Sp. cristata will be in order. These, however, I am at 
400 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

present in no position to undertake, lacking characteristic material of the foreign 

species, and the same is true of Sp. octoplicata, which is of the same type as Sp. 

campestris and which the latter seems to resemble closely. 

The shape and surface ornamentation of Sp. campestris simulate those of Sp. 

spinosa in the closest manner. In fact, after studying the available material of both 

forms I find no constant or considerable differences by which they are to be distinguished. The evidence seen certainly indicates that Sp. campestris White is the same 

as Sp. spinosa N. and P., but I retain a distinct name for the Coal Measure species, 

fearing lest comparisons of more abundant or more favorable material will disclose 

differences which have escaped my notice. I believe, however, that the Chester species 

will be found to range into the Pennsylvanian and that these citations of Upper Carboniferous representatives will come to rest in the synonymy of Sp.- spinosa. 

Locality and horizon.—San Juan region (station 2219); upper portion of the 

Hermosa formation. Crested Butte district (station 2315); Weber limestone. 

SPIRIFERINA KENTUCKYENSIS Shumard. 

1852. Spirifer octoplicata f Hall, Stansbury's Exped. Great Salt Lake, p. 409, pl. 4, figs. 4a,b. (Not Sp. 

octoplicata Sow..) 

Carboniferous: Missouri River, near Weston. 

1855. Spirifer kentuckensis. Shumard, Missouri Geol. Surv., p. 203. 

Coal Measures: On the Missouri River near Weston, and Grayson County, Ky. 

1856. Spirifer kentuckensis. Hall, Pacific Railroad Rept., vol. 3, p. 102, pl. 2, figs. 10, 11. 

Carboniferous: Pecos Village, N. Mex. 

1859. Spirifer kentuckensis. Meek and- Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 27. 

Upper Coal Measures: Leavenworth, Kans. 

1866. Spirifer laminosus. Geinitz, Carb. and Dyas in Nebraska, p. 45, tab. 3, figs. 19a-d. (Not Sp. 

laminosus McCoy. ) 

Upper Coal Measures: Plattsmouth and Nebraska City, Nebr. 

1872. Spiriferina kentuckensis. Meek, U. S. Geol. Surv. Nebraska, p. 185, pl. 6, figs. 3a-d; p1. 8, figs. 

11a, b. 

Upper Coal Measures: Nebraska City, Nebr. 

Coal Measures: Kentucky; Illinois; Missouri; Iowa; Nebraska; Kansas; Texas; New Mexico. 

1876. Spiriferina kentuckensis. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower and Upper Aubrey Group: Confluence of Grand and Green rivers, Utah. 

1877. Spiriferina kentuckensis. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 138, p 

10, figs. 4a-c. 

Carboniferous: Santa Fe, N. Mex.; Meadow Creek, south of Fillmore, Utah; Camp Apache, Ariz. 

1883. Spirifera, (Spiriferina) kentuckiensis. Hall, Rept. New York State Geol. for 1882, pl. (36) 61, figs. 

14-16. 

Coal Measures. 

1884. Spiriferina kentuckensis. White, Geol. Surv. Indiana, 13th Rept., p. 135, pl. 35, figs. 13, 14. 

Middle and Upper Coal Measures: Vermilion, Vigo, Knox, Gibson, Posey, Vanderburg, Dubois, 

and Spencer counties, Indiana. 

1888. Spiriferina kentuckensis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 231. 

Lower Coal Measures: Des Moines, Iowa. 
DESCRIPTIONS OF SPECIES. 401 

1893. Spiriferina kentuckiensis. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 52, ". 29, fig. 17; pl. 

36, figs. 14-16. (Advance distribution in fascicles.) 

Coal Measures: Vinton County, Ohio; Illinois. 

1894. Spiriferina kentuckiensis. Keyes, Missouri Geol. Surv., vol. 5, p. 86. 

Upper Coal Measures: Kansas City and Lexington, Mo. 

1895. Spiriferina kentuckiensis. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 52, pl. 29, fig. 17; pl. 

36, figs. 14-16. 

Coal Measures: Vinton County, Ohio; Illinois. 

1896. 	Spiriferina cristata. , Smith (pars), Am. Phil. Soc., Proc., vol. 35, p. 242. 


Lower Coal Measures: Conway County, Ark. 


Upper Coal Measures: Sebastian County, Ark., and Poteau Mountain, Indian Territory. 


1896. Spiriferina cristata. Smith (pars), Leland Stanford Junior Univ. Publ., Cont. Biol. Hopkins 

Seaside Lab., No. 9, p. 32. 

Lower Coal Measures: Conway County, Ark. 

Upper Coal Measures: Sebastian County, Ark., and Poteau Mountain, Indian Territory. 

1900. Spiriferina cristata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 96. 

Upper and Lower Coal Measures: Fort Scott, Bronson, Bourbon County, Thayer, Kansas 

City, Lawrence, Lecompton, Topeka, Kans. 

In connection with the preceding species attention was called anew to the fact 

that there are at least two distinct types of Spiriferina occurring in our Coal Measure 

strata, one, like Spiriferina spinosa Hall, of the Chester, with pustulose or spinose 

ornamentation, the other with fine imbricating concentric striae. 

The form described by Hall as Sp. octoplicata Sow. ? which may be regarded as 

the type of Sp. kentuckgensis Shumard, certainly belongs to the striated group. 

Spiriferina kentuckyensis has often been placed in the synonymy of Sp. cristata 

Schlotheim. 

The original description of Sp. cristata a gives no clue to the minuter surface 

• ornamentation of that species, and the figures only imperfectly disclose it. The 

specimens examined by me, which seem to be most nearly typical of Schlotheim's 

species, come from the middle Zechstein of Posneck, Thuringia. The identification was made by Geinitz. This material resembles Schlotheim's figures, both in 

general configuration and in surface ornamentation. The latter is rather variable. 

It seems to consist of concentric lamellose striae, in s me specimens so distant as to 

answer to the growth lines of Sp. gonionotus, and in others so close together that 

they exhibit the type of ornamentation seen in Sp. entuckyensis, but never in the 

specimens examined is there any development of the pustulose ornamentation characteristic of Sp. gonionotus, even when the concentri markings are as distant as in 

that species. The intervening spaces are left nearly smooth; and the punctation is 

so fine as to be scarcely discernible. Thus it would. s em that Sp. cristata belongs to 

the division of Sp. ken,tuckyensis rather than to that of Sp. gonionotus and Sp. spinosa. 

a Schlotheim, 1816. Beitr. zur Naturg. der Versteinerungen; 'Con. Bay. A ad. der Wissensch. zu Mtinchen,Denkschr., 

p. 28, pl. 1, figs. 3a, 3b, 3c. 

14364—No. 16-03--26 
402 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

On the other hand Davidsona while describing the surface of Sp. octoplicata 

Sow. as pustulose, refers it to Sp. cristata in a varietal relation. Supposing that 

Davidson knew the characters of the real cristata, one would from this be led to infer 

that the latter was also of the pustulose division of the genus. Similarly the form 

identified by King b as Sp. cristata in his monograph on the Permian fossils of England, seems to be at least a coarsely punctate, and possibly a pustulose species. Some 

of his expressions undoubtedly refer to the punctate structure of the shell, but others 

perhaps involve the surface ornamentation. Furthermore he states:c . " Having 

examined in Mr. J. de C. Sowerby's collection the originals (from Derbyshire) of 

the figures in the 'Mineral Conchology' [of Sp. octoplicata], the only difference I could 

perceive is that they are wider than any examples which have occurred to me of the 

present species." Since King noticed characters so minute as the punctate shell 

structure, it seems probable that the less microscopic surface ornamentation would 

not have escaped his observation, and as Davidson, who also examined the original 

specimens of Sp. octoplicata, describes that species in such terms as to leave no doubt 

that it belonged to the spinose type of spiriferinas, as just noted, it would appear 

that the shells which King believed to be identical with Schlotheim's species were also 

of the same character. 

If Sp. cristata belongs to the spinose section of the genus, there can be no doubt 

that Sp. kentuckyensis is specifically distinct. If, on the other hand, it is of the 

type of Sp. kentuckyensis, I still believe Shumard's species to be worthy of at least 

ensis 

varietal position. A comparison of well-characterized specimens of 

Schlotheim's species, reveals several points of difference. The most constant and 

hinge extremities and appears rarely, if ever, to have the cardinal diameter proimportant of these seem to be the following: 

with our European material, which is premised to truthfully represent 

Sp. cristata is typically rounded at the 

Sp. kentuckylonged into mucronate points, as is frequently the case in the American species. Its 

plications are sharper and higher, and the furrows dividing them deeper than in our 

own form, while the concentric imbricating striie are never, even when most closely 

set, as evenly disposed and as thickly crowded. 

While Spiriferina kentuckyensis is perhaps no more than varietally distinct from 

the material from Posneck identified as Sp. cristata, because I am still somewhat in 

doubt, for reasons 'given above, as to what the surface ornamentation of typical Sp. 

cristata really is, Shumard's name is provisionally retained in full specific import. 

Locality and horizon.—San Juan region (stations 2220, 2322); middle portion of 

Hermosa formation. Crested Butte district (station 2295); Maroon formation. Uinta 

a British Fossil Brachiopoda, vol. 2, 1858-63, p. 38. 

b Monograph Permian Foss. England, 1850, p. 127. 

c Loc. cit., p. 128. 
DESCRIPTIONS OF SPE IES. 403 

• Mountain region, Yampa plateau (station 2330); mid, le division of the Carboniferous. 

Grand River region, Glenwood Springs (station 23.9b). 

- SEMINUL A McCoy, 1844, emend. II 11 and Clarke, 1893. 

SE MINULA SUBTILITA all. 

PL VII, figs. 1 to lb, 2, 2a, 3, 3a, 4-7, a, 8-10. 

1842. Terebratula roissyi. D'Orbigny (non L'Eveille) , Voyage ans l'Amerique Meridionale, Pal., p. 46. 

Carboniferous: Yarbichambi. 

1852. Terebratula plano-sulcata. Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 5, fig. 9. 

Carboniferous limestone: Near Council Bluffs. 

1852. Terebratula subtilita. Hall, Stansbury's Exped. Great S lt Lake, p. 409, pl. 2, figs. la, b, 2a, b. 

Carboniferous: Missouri River, near Weston. 

?1853. Terebratula subtilita. Shumard, Marcy's Expl. Red Riv • r of Louisiana, Thirty-second Congress, 

Second session, Senate Doc. No. 54 (reprinted several Imes with different pagination), p. 202, 

pl. 4, fig. 8. 

Carboniferous: Washington County, Ark. 

1855. Terebratula subtilita. Schiel, Pacific Railroad Rept., vol. 2, p. 108, pl. 1, figs. 2a, b. 

Carboniferous limestone: 8 miles west of Westport. 

1856. Terebratula subtilita. Hall, Pacific Railroad Rept. vol. 3 p. 101, pl. 2, figs. 3-5. 

Carboniferous: Pecos Village, N. Mex. 

1857. Terebratula (?) subtilita. Davidson, Mon. British Carb. rach., Pal. Soc., p. 18, pl. 1, figs. 21, 22. 

Carboniferous: Mayen Wais, England. 

1858. Terebratula plano-sulcata. Marcou, Geol. North Americ , p. 52, pl. 6, figs 8, 8b. 

Mountain limestone: Tigeras, N. Mex.; Ohio; Indiana; Illinois; Kentucky; Arkansas. 

1858. Terebratula roysii. Marcou, Geol. North America, p. 51, pl. 6, figs. 10, 10b. 

Mountain limestone: Salt Lake City, Utah; El Paso, C ihuahua; headwaters of the Rio Colorado Chiquito. 

1858. Terebratula subtilita. Marcou, Geol. North America, p. 2, pl. 6, figs. 9-9f. 

Mountain limestone: Sierra Madre; Sierra de Magoyo ; Great Salt Lake; Tigeras and Pecos 

Village, N. Mex.; summit of Sierra de Sandia and Sierra de Magoyon; El Paso, Chihuahua; 

junction of rivers San Pedro and Gila, Arizona; so rtes of Rio Colorado Chiquito; Shasta 

County, Cal.; Vancouver Island. 

1858. 	Terebratula subtilita. Hall, Geol. Surv. Iowa, vol. 1, pt. p. 714. 

Coal Measures: Ohio; Indiana; Illinois; Iowa; Missouri; Kansas; Nebraska; and Pecos Village, 

N. Mex. 

1859. Spirigera subtilita. Meek and Hayden, Acad. Nat. Sci. hiladelphia, Proc., p. 28. 

Upper Coal Measures: Kansas. 

1860. Athyris subtilita. Davidson, Mon. British Carb. Brach., Pal. Soc., p. 86, pl. 1, figs. 21, 22; p1. 

17, figs. 8-10. 

Carboniferous: Mayen Wais, England; Tournay, Belgiu 

1861. Athyris subtilita. Salte'r, Geol. Soc. London, Quart. Jou ., vol. 17, p. 64, pl. 4, fig. 4. 

Carboniferous: Isthmus of Copacabana, in the Lake of Titicaca. 

1861. Athyris subtilita. Newberry, Ives's Colorado River Exp . Exped., p. 126. 

Upper Carboniferous: Cherty limestone on banks of olorado between Little Colorado aria 

Diamond rivers; Pecos Village, east of Santa Fe. 
404 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1862. Terebratula (?) subtilita. Davidson, Mon. British Carb. Brach., Pal. Soc., p. 217, pl. 17, figs. 8-10. 

Carboniferous limestone: Bolland; Kendal in Westmoreland. 

1866. Athyris subtilita. Geinitz, Carb. and Dyas in Nebraska, p. 40, tab. 3, figs. 7-9. 

Upper Coal Measures: Omaha City, Plattsmouth, Bennett's Mill, and Nebraska City, Nebr. 

1869. Spirifera (Athyris) subtilita. Toula, Sitzb. der Kais. Akad. der Wissensch. Wien, 1. Abth., vol. 

59, p. 438, pl. 1, fig. 5. 

Carboniferous limestone: 10 miles from Cochebamba, Bolivia. 

1872. Athyris subtilita. Meek, U. S. Geol. Surv. Nebraska, p. 180, pl. 1, fig. 12; pl. 5, fig. 8; pl. 8, fig. 4. 

Upper Coal Measures: Nebraska City, Bennett's Mill, Wyo.; Cedar Bluff, Rock Bluff, Plattsmouth, Bellevue, and Omaha, Nebr. 

Coal Measures: Illinois; Missouri; Iowa; West Virginia; Ohio; Kansas; Pecos Village, N. Mex. 

1873. Athyris subtilita. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 3, p. 570, pl. 25, fig. 14. 

Coal Measures: Illinois. 

1874. Athyris subtilita. Derby (pars), Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 7, pl. 1, figs. 5, 8 

(not fig. 7 = Spirigerella derbyi); pl. 3, figs. 8, 16, 19; pl. 6, fig. 2; pl. 9, fig. 4. 

Coal Measures: Bomjardim, Itaitdba, and Paredao, Brazil. 

1875. Spirigera subtilita. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 141, p1. 10, 

figs. 6a-c. (Whole volume published in 1877.) 

Carboniferous: Carizo Creek, Maricopa County; Camp Apache; Tenney's Ranch; Kaibab Plateau; confluence of White Mountain and Black rivers; Grass Mountain, 35 miles north of 

Pioche, and foothills of Dragoon Mountains, Arizona; Fossil Hill, White Pine County, and 

Camp Cottonwood, Nev.; 15 miles south of St. George; near Ophir City; Rock Canyon, 

Wasatch range, near Provo; and near Minersville, Utah. 

1876. 	Spirigera subtilita. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: Confluence of Grand and Green jivers, and near Echo Park, Utah. 

Upper Aubrey group: Beehive Point, near Horseshoe Canyon, Utah. 

1876. Athyris subtilita. Meek, Simpson's Expl. Great Basin, Utah, p. 350, pl. 2; figs. 4a, b. 

Coal Measures: Yellow limestone, Humboldt Mountains. 

1876. Athyris subtilita. Newberry, Macomb's U. S. Expl. Exped. Santa Fe to Grand and Green rivers, 

p. 138. 

Upper Carboniferous: On the Colorado; west of the San Francisco Mountains; junction of Grand 

and Green rivers; in the Sierra la Plata; at Santa Fe; Pecos. 

1876. Athyris subtilita. Derby, Mus. Comp. Zool., Bull., vol. 3, p. 279. 

Coal Measures: Yampopata, Brazil. 

1876. Athyris subtilita., Meek, U. S. Geol. Geog. Surv. Terr., Bull., vol. 2, pl. 355, pl. 1, figs. 2, 2a. 

Carboniferous: Katlahwoke, Rocky Mountains. 

1877. Athyris subtilita. Meek, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 83, pl. 8, figs. 6, 6a. 

Carboniferous limestone: Ruby group; Moleen Peak, near Humboldt River, Nevada. 

1884. Athyris subtilita. White, Geol. Surv. Indiana, 13th Rept., p. 136, pl. 35, figs. 6-9. 

Coal Measures: Indiana. 

1887. Athyris subtilita. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 44, pl. 1, figs. 18 (16a-c?). 

Coal Measures: Flint Ridge, Ohio. 

1887. Athyris subtilita. De Koninck, Ann. du Musee Royal d'Histoire Naturelle de Belgique, vol. 14, 

p. 73, pl. 18, figs. 1-4, 7-10, 12-28; pl. 19, figs. 47-56. 

1888. 	Athyris subtilita. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 231. 

Lower Coal Measures: Des Moines, Iowa. 
DESCRIPTIONS OF SPECIES. 405 

1891. Athyris subtilita. Whitfield, New York, Acad. Sci., Ann., vol. 5, p. 604, pl. 16, figs. 7-9. 

Coal Measures: Hocking County, Ohio. 

1893. Seminula subtilita. Hail and Clarke, Pal. New York, vol. 8, pt. 2, p. 95, figs. 66, 67 on p. 95, 

and figs. 58, 59 on p. 86; pl. 47, figs. 17-31. (Advance distribution in fascicles.) 

(?) Chester limestone: Caldwell County, Ky.; Chester, Ill. 

Coal Measures: Manhattan and 1Viiami County, Kans.; Kansas City and Chariton County, Mo.; 

Coppers Creek, and Winterset, Iowa; Ohio. 

1894. Seminula subtilita. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 35, figs. 16-19. 

Coal Measures: Chariton County, Mo.; Winterset, Iowa; near Kansas City, Mo. 

1895. Athyris argentea. Keyes, Missouri Geol. Surv., vol. 5, p. 92, pl. 39, figs. 11a-d. (Date of imprint 

1894.) 

Coal Measures: Kansas City, Lexington, and Clinton, Mo. 

1895. Seminula subtilita. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 95, figs. 66, 67, and 58, 59 

on p. 86; pl. 47, figs. 17-31. 

Coal Measures: Manhattan, Kans.; Coppers Creek, Iowa; Chariton County, Mo.; Winterset, 

Iowa; Miami County, Kans.; Kansas City, Mo.; Ohio. 

(?) Chester limestone: Caldwell County, Ky.; Chester, Ill. 

1895. Athyris subtilita. Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 488, pl. 12, figs. 7-9. 

Coal Measures: Falls Township and Webb Summit, Hocking County, Ohio. 

1896. Athyris subtilita. Smith, Am. Phil. Soc., Proc., vol. 35, p. 241. 

Upper Coal Measures: Sebastian County, sec. 12, T. 8 N., R. 32 W., Arkansas; Poteau Mountain, Indian Territory. 

(?) Burlington or Lower Keokuk: Boone chert, Stone County, N. W. 1 sec. 9, T. 14 N., 

10 W., Arkansas. 

1896. Athyris subtilita. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside Lab.. 

No. 19, p. 31. 

Upper Coal Measures: Sebastian County, Ark., sec. 12, T. 8 N., R. 32 W. ; Poteau Mountain, Indian 

Territory. 

(?) Burlington or Lower Keokuk: Boone chert, Stone County, Ark., N. W. sec. 9, T. 14 N., 

R. 10 W. 

1900. Seminula argentea. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 105, text-fig. 3c. 

Upper and Lower Coal Measures: Marmaton Station, Bourbon County, Iola, Kansas City, Eudora, 

Lawrence, Lecompton, Topeka, Manhattan, Grand Summit, Kans. 

1900. Seminula argentia. Knight, Univ. Wyoming, Wyoming Exp. Sta., Bull. No. 45, pl. 3, fig. 6. 

As shown by our collections, this seems to be the most universally distributed 

species of the entire Carboniferous fauna. It has been found at over fifty stations. 

Although many variations are to be seen in the material examined, it has not been 

found practicable to establish lines by which specific or varietal groups shall te 

defined. There are some forms which have a nearly circular outline. Others are 

elongate. In some the sinus is shallow and broad; in others narrow and deep; and 

in certain smaller types it is little more than a depressed line. The latter, though 

occurring alone, may probably be correctly regarded as young examples of the larger, 

more strongly characterized shells. Yet all this variety of form seems to be without 
406 CARBOITIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

break or interruption, but, on the contrary, variety passes into variety by the easiest 

gradations. 

Young specimens are often nearly circular in shape, with the elements of fold 

and sinus almost imperceptible, and from certain localities such specimens only have 

come to hand. They sometimes assume much the aspect of the later forms of development of the genus Oleiothyris. I have identified Oleiothyris among the fossils 

examined in the case of only two specimens, but possibly among the shells just mentioned may occur representatives of this genus which their superficially exfoliated 

condition has prevented my recognizing as such. 

Keyes and Schuchert have used for this species the specific term argentea, proposed by Shepard fourteen years before Hall's Terebratula subtilita was described. 

Relegating, for the time, the question whether Terebratula argentea, with its poor 

description and execrable figures, should replace T subtilita, which was well figured 

and adequately described, it is by no means certain that Shepard's species is the same as 

that described by Hall, or even congeneric with it. There is little evidence to be derived 

from the original citation, and none has been produced outside, save the statement 

by Keyes, that Seminula subtilita is the commonest species at the locality where T. 

argentea was first found. This circumstance is of importance, but scarcely, it seems 

to me, of character sufficiently conclusive to warrant the replacement of Hall's name, 

which has a definite meaning, for one whose significance is still vague and uncertain. 

The small size, rotund shape, and elevated beak of the form represented by Shepard's 

figures seem to indicate, rather than Seminula subtilita, some other shell, perhaps 

Reticularia perplexa, to which the two lines of casual description equally apply. 

Shepard's mention of this shell is formulated in the following words: "It embraces 

occasionally * * * a small species of Terebratula, whose surface is delicately 

striated, and of a silvery white color and strong pearly luster." 

Schuchert includes in the synonymy of this species Terebratula antisiensis and 

T. peruviana, both of d'Or bigny, which antedate Hall's description by ten years. 

If he is correct in this, one of these names may have to be substituted for Seminula 

subtilita, unless it develops that Shepard's fofm is the same species. 

It is not improbable that S. ca_putserpentis Swallow, S. singletoni Swallow, 

S. hawni Swallow, S. charitonensis Swallow, and S. diferentius McChesney, all of 

which were described subsequently to S. subtilita, belong in the synonymy of this 

species. I also believe that with Seminula subtilita, or, at any rate, with the genus 

Seminula, belong the shells which Marcoua identifies as Terebratula planosulcata 

Phillips and 

thyris, sc. Cl. roissyi. 

2196c, 2201, 2202, 2204, 2205, 2209, 2211, 2213, 2214, 2216, 2219, 2220, 2222, 2223, 2224, 

Locality and horizon.—San 

T. royssii l'Eveille, though these have usually been placed with 

Juan region (stations 2186, 2187, 2196, 2196a, 2196b, 

Cleioa Geol. North America, Ziirich, 1858, pp. 51, 52, pl. 6, figs. 8, 8a, 8b, and figs. 10, 10a, 10b. 
DESCRIPTIONS OF SPECIES. 407 

2229, 2231, 2233, 2236, 2237, 2239, 2240, 2242, 2243, 2246, 2247, 2248, 2249, 2284, 2309, 

2323, 2331, 2332, 2337, 2340,,2341, 2342, 2349); Molas formation, lower, middle, and 

upper portions of the Hermosa formation, and in the Rico formation; Ouray (stations 2195, 2195a, 2195b); Hermosa formation. Crested Butte district (stations 

2244, 2245, 2280, 2291, 2'293, 2297, 2298, '2299, 2303, 2305, 2306, 2318); Weber limestone and Maroon formation. Leadville district (stations 2252, 2254, 2259, 2261, 

2262, 2263, 2264 ?, 2267, 2273, 2274, 2275); lower, middle, and upper portions of the 

Weber formation, and in the Robinson limestone. Grand River region (station 

2324), Glenwood Springs (stations 2193a, 2329). 

CLEIOTHYRIS King, 1850. 

CLEIOTHYRIS ORBICULARIS McChesney. 

1860. Athyrus orbieularis. McChesney, Desc. New Pal. Foss., p. 47. 

Coal Measures: Western States. 

? 1860. Spirigera missouriensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 650. 

Coal Measures: Montgomery and Chariton counties, Mo. 

1866. Athyris planosulcata. Geinitz, Carb.. and Dyas in Nebraska, p. 42. 

Coal Measures: Omaha City, and Plattsmouth, Nebr. 

1874. Athyris sublamellosa. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 10, pl. 2, figs. 

9-12; pl. 3, figs. 15, 21, 29; pl. 6, fig. 16; pl. 9, figs. 5, 6. 

Coal Measures: Bomjardim and Itaituba, Brazil. 

1875. Spirigera planosulcata. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 143, pl. 

10, figs. 5a-d. (Whole volume published in 1877.) 

• 	 Carboniferous: Santa Fe, N. Mex., Rush Creek, Lake County, Colo. 

1897. Cleiothyris orbicularis. Schuchert, U. S. Geol. Surv., Bull. No. 87, p. 182. 

? 1897. Cleiothyris missouriensis. Schuchert, U. S. Geol. Surv., Bull. No. 87, p. 182. 

In its representation in American strata the genus Cleiothyris is restricted, so 

far as known, to the Carboniferous period. Throughout the existence of this type 

it follows few lines of variation, but within certain limits and in a few particulars 

these shells are very variable. The most obvious character is that of size, and it is 

at the same time the least significant. 

A number of specific names have been proposed for American representatives of 

the genus, but experience shows that it would be difficult to establish the validity 

of many of them if reference were had only to the uniformity and persistence of 

differential characters. 

In the Upper Carboniferous representatives of the Cleiothyris group are usually 

small of size and in numbers rare. The first specific name proposed for a 

Pennsylvanian Cleiothyris is Athyris orbicularis McChesney, which was published 

early in 1860. In the same year, though probably subsequent to the publication of 
408 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Athyris orbieularis,a Swallow described Spirigera missouriensis, basing his description 

upon what I feel confident was the same type of shell. The reasons for this conclusion 

are as follows: 

McChesney states that his shell is closely allied to Athyris sublamellosa Hall, 

and that it had sometimes been referred to Terebratula planosuleata of Phillips. Both 

the species mentioned belong to the Cleiothyris group of Athyris, and, as the general 

character of the description indicates the configuration and surface ornamentation of 

Cleiothyris, it is practically certain that Athyris orbicularis belongs to that group. 

Furthermore, I find in the collections of the U. S. National Museum a species of 

Cleiothyris which bears Worthen's identification with Cl. orbicularis, and at the 

same time permits McChesney's description to be applied to it. 

Swallow's description of Spirigera missouriensis would of itself lead one to 

infer that he had in hand shells of the Cleiothyris type, and such an inference receives 

corroboration from the circumstance that it is said much to resemble Cl. hirsuta Hall. 

To be sure, it is said to differ from that species in being ornamented with lamella 

instead of the spines, which are, of course, a distinctive character of Cleiothyris, but 

the lamellae are described as imbricating, transversely costate, and as leaving granular ridges in falling off, details all of which indicate that the lamellae were spiniferous. It is true, also, that the structure is described as punctate, but the same 

character is ascribed to several species of Semiriula described under the names of 

Spirigera ch,aritonensis and Sp. hawni. Furthermore, among the museum collections are specimens of a Cleiothyris from Chariton County, one of the localities cited 

by Swallow, which answer to his description in most particulars and yet clearly • indicate the subgeneric group to which they belong. 

The descriptions of Cl. orbicularis and Cl. missouriensis certainly indicate closely 

similar shells, and the specimens in our collections which seem to best represent each 

of those species I would feel no hesitation in referring to the same. Indeed, I find 

it impossible to discriminate between the Pennsylvanian representatives of Cleiothyris 

that have come under my observation, and must refer all to a single species. These 

thyris 

facts, and a consideration of the narrow limits of variation habitually shown in 

the same species. 

identified with 

It is probable that the Upper Carboniferous form from Brazil which Derby 

as a whole, lead me to regard 

Cl. sublaniellosa Hall can be referred to this species, though the 

Cl. orbicularis and Cl. missouriensis as one and 

CleioSouth American shells attain a somewhat unusual size. It seems pretty certain that 

the shells from Nebraska which Geinitz identifies as .Athyris planosuleata also belong 

here, and those from the west referred by White to the same species, after an examination of his specimens, I do not hesitate to add to this synonymy. 

a McChesney's publication was reviewed in the Am. Jour. Sci. for March, 1860. Swallow's paper was presented for 

publication in the St. Louis Acad. Sci. on July 2d of the same year. 
DESCRIPTIONS OF SPECIES. 409 

The relations of Cl. orbicularis and Cl. sublamellosa are of the closest. I find 

that the characters pointed out by McChesney to distinguish them can not be 

generally relied upon, and only hold good in selected cases. The only distinction 

which I have been .able to observe in the material examined is that the Pennsylvanian 

species seems to be, as a rule, somewhat more transverse than the older form, but I 

doubt if to this difference alone could be given specific significance, even if it proves 

to be a constant one. I am, therefore, prepared to see McChesney's name orbioularis 

succeed to Hall's sublamellosa for this species. 

Under the name of Spirigera planosuleata White has already cited this species 

from Colorado, from Rush (Rock) Creek, in Lake County. I am not sure that the 

material upon which this identification rests has come into- my hands, but I have it 

from other areas in the shape of two small, not very perfect shells, each from a separate station. The larger of these is less than 8 mm. in diameter, and therefore somewhat below the average size of Mississippi Valley specimens, but otherwise I see no 

characters by which to distinguish them. 

McChesney's original description of Cl. orbicularis, to which access is usually 

difficult, I have cited below in full. 

4 4 ATHYRUS ORBICULARIS (n. S.). 

"Shell subcireular or varying from transversely subelliptical to subovately 

elongate, moderately gibbous. Dorsal valve. less than the ventral, depressed convex, 

rarely slightly elevated in front; beak closing the foramen of the opposite valve. 

Ventral valve convex, strongly gibbous toward the beak; front sometimes flattened, 

but without true sinus; beak prominent, slightly incurved, and vertically or somewhat obliquely truncated by a circular foramen. 

" Surface distinctly marked by concentric lamellose bands of growth. 

"This species is closely allied to A. sublamellosa of Hall (Geol. Rep. Iowa, 

p. 702), from which it is easily distinguished by having a larger ventral than dorsal 

valve, while in that the dorsal valve is much the largest, and by the much greater 

elevation or thickening of the ventral valve toward the beak. 

" It has sometimes been referred to Terebratula piano-suleata of Phillips, from 

which it differs in being a less rotund shell, and in the much less gibbosity or inflation of its ventral valve toward the front of the shell, as well as in other respects. 

"Geological position and localities: In Coal Measures, particularly the upper 

portion, extensively distributed in the Western States." 

Locality.—Grand River region, Glenwood Springs (station 2193a). 

DIELASMA King, 1850. 

DIELASMA BOVIDENS Morton ?. 

Pl. VII, figs. 11,11a. 

1836. Terebratula bovidens. Morton, Am. Jour. Sci., (1), vol. 29, p. 150, pl. 2, fig. 4. 

Coal Measures: Ohio Valley. 

1856. Terebratula millepunctata. Hall, Pacific Railroad Rept., vol. 3, p. 101, pl. 2, figs. 1, 

Carboniferous: Pecos Village, N. Mex. 
410 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1858. 	Terebratula millepunctata. Hall, Albany Inst., Trans., vol. 4, p. 35. 

Upper Carboniferous: Topeka, Kans. 

1858. 	Terebratula bovidens? Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 711. 

1859. Terebratula millepunctata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 26. 

Upper Coal Measures: Leavenworth, and near Indianola, Kans. 

? 1859. Terebratula elongata. Shumard (non Schlotheim), Acad. Sci. St. Louis, Trans., vol. 1, p. 392. 

Permian: Guadalupe Mountains, 

1861. Terebratula geniculosa. McChesney, Desc. New. Spec. Pal. Foss., p. 82. 

Coal Measures: Lasalle, Ill. 

1865. 	 Terebratula geniculosa. McChesney, Illustrations New Spec. Pal. Foss., pl. 1, fig. 2. 

1869. 	 Terebratula bovidens. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 37, pl. 1, figs. 2a-c. 

Coal Measures: Lasalle, Ill. 

1872. 	 Terebratula bovidens. .Meek, U. S. Geol. Surv. Nebraska, p. 187, pl. 1, figs. 7a-d, pl. 2, fig. 4. 

Upper Coal Measures: Plattsmouth, Nebr.; Indian Creek, Kansas; Lasalle, Ill.; New Mexico. 

Coal Measures: Ohio, Iowa, Missouri, Kansas, Illinois. 

1873. Terebratula bovidens. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 572, pl. 25, fig. 15. 

Upper and Lower Coal Measures: Illinois. 

1874. Dielasma? bovidens. White, U. S. Geog. Geol. Surv. W. 100th Mer., Prelim. Rept. Invert. Foss., 

p. 21. 

Carboniferous (Coal Measures): (Far West.) 

1877. Terebratula (Dielasma) bovidens. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, 

p. 144, pr 11, figs. 10a-c. 

Carboniferous: Near Santa Fe, N. Mex.; a few miles south of St. George, Utah; top of Grass 

Mountain, Ely Range, 30 miles north of Pioche, Nev. 

1884. Terebratula bovidens. White, Geol. Surv. Indiana, 13th Rept., p. 137, pl. 32, figs. 17-19. 

Coal Measures: Perrysville, Eugene, Newport, Lodi, and Terre Haute (west of), Indiana; 

Posey, Warrick, Perry, and Crawford counties, Ind. 

1893. Dielasma bovidens. Hall and Clarke, Pal.. New York, vol. 8, pt. 2, pp. 295, 296, fig. 213; pl. 81, 

figs. 29-35. (Advance distribution in fascicles.) 

Upper Carboniferous limestone: Kansas City, Mo.; Harrison County, Mo.; southern Indiana. 

1894. Dielasma bovidens. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 53, figs. 21-25. 

CarbOniferous limestone: Harrison County, Mo. 

1895. Terebratula bovidens. Keyes, Missouri Geol. Surv., vol. 5, p. 105. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1895. Dielasma bovidens. Hall and Clarke, Pal. New York, vol. 8, pt. 2, pp. 295, 296, fig. 213; pl. 81, 

figs. 29-35. 

Tipper Carboniferous limestone: Kansas City, Mo.; southern Indiana; Harrison County, Mo. 

1897. 	Terebratula hastata. Smith, Am. Phil. Soc., Proc., vol. 35, p. 30. 

Lower Coal Measures: Conway County, Ark. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

1900. 	Dielasma bovidens. Beede, Univ. Geol. Surv.. Kansas, Rept., vol. 6, p. 95. 

Upper Coal Measures: Kansas City, Eudora, Lawrence, Lecompton, Topeka, Grand Summit, Kans. 

This species is rare in the collections from Colorado. It has been found at but 

three localities, each of which has furnished a single specimen. Two of these are 
DESCRIPTIONS OF SPECIES. 411 

imperfect and the other is not quite typical so that it can not be said to have been 

certainly found in the State at all so far as our collections are concerned. 

Locality and horizon.—San Juan region (station 2196c?); Hermosa formation. 

Crested Butte district (stations 2245, 2280); Maroon formation. 

HUSTEDIA Hall and Clarke, 1893. 

HUSTEDIA MORMONI Marcou. 

Pl. VII, figs. 12, 12a, 13. 

1858 (February). Terebratula mormoni. Marcou, Geol. North America, p. 51, pl. 6, figs. 11-11e. 

Mountain limestone: Salt Lake City, Utah. 

1358 (June). Retzia punctilifera. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 220. 

Upper Coal Measures: Audrain and Howard counties, Mo.; below mouth of Platte River, 

Nebraska; near Manhattan, at Willowsprings, on Santa Fe road, and headwaters of Verdigris 

River, Kansas. 

1859. Retzia mormoni. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 27. 

Tipper Coal Measures: Manhattan and Leavenworth, Kans. 

1860. Retzia subglobosa. McChesney, Desc. New Spec. Pal. Foss., p. 45. 

Upper Coal Measures: Menard, Mason, Fulton, Peoria, Tazewell, Knox, and Marshall counties, Ill. 

1864. Retzia compressa. Meek, Pal. California, vol. 1, p. 14, pl. 2, figs. 7-7c. 

Carboniferous: Bass's Ranch, Shasta County, Cal. 

1865. Retzia subglobosa. McChesney, Illustrations New Spec. Pala Foss., pl. 1, fig. 1. 

1866. Retzia mormoni. Geinitz, Carb. and Dyas in Nebraska, p. 39, tab. 3, fig. 6. 

Upper Coal Measures: Plattsmouth, Nebr. 

1868. Retzia punctulifera. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 32, pl. 1, figs. la-c. 

Upper Coal Measures limestone: Menard, Mason, Fulton, Peoria, Tazewell, Knox, and Marshall 

counties, Ill. 

1872. 	Retzia punctulifera. Meek, U. S. Geol. Surv. Nebraska, p. 181, pl. 1, fig. 13; pl. 5, fig. 7. 

Upper Coal Measures: Rock Bluff, Plattsmouth, and Nebraska City, Nebr. 

Coal Measures: Nebraska; Kansas; Illinois. 

1874. Eumetria punctulifera. Derby, Cornell Univ., (Science) Bull., vol. 1, No. 2, p. 4, pl. 8, figs. 

4, 5, 7, 8, 10; pl. 9, fig. 3. 

Coal Measures: Bomjardim and Itaituba, Brazil, and Pichis River, Peru. 

1875. Retzia mormonii. White, U. S. •Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 141, pl. 10, 

figs. 7a-c. (Whole volume published in 1877.) 

Carboniferous: Near Santa Fe, New Mex.; top of Grass Mountain, Ely Range, 30 Miles north of 

Pioche, Nev. 

1875. Terebratula mormoni. Marcou, Acad. Sci. St. Louis, Trans., vol. 3, p.. 252. 

1883. Retzia compressa. Kayser, Richthofen's China, vol. 4, p. 176, pl. 22, figs. 1-4. 

Upper Carboniferous: Lo-Ping, China. 

1884. Retzia radialis. Walcott (non Phillips) (pars), U. S. Geol. Surv., Mon., vol. 8, p. 220, pl. 7, figs. 

5f-h (not figs. 5-5e). 

Upper Carboniferous: Eureka district, Nevada. 
412 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1884. Retzia mormonii. White, Geol. Surv. Indiana, 13th Rept., p. 136, pl. 35,figs. 10-12. 

Coal Measures: Indiana. 

1888. Retzia mormoni. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 231. 

Lower Coal Measures: Des Moines, Iowa. 

1893. Hustedia mormoni. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 120, fig. 106; pl. 51, figs. 

1-9. (Advance distribution in fascicles.) 

Coal Measures: Near Kansas City, Mo. 

1894. Hustedia mormoni. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 37, figs. 13-20. 

Coal Measures: Near Kansas City, Mo. 

1895. Hustedia mormoni. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 120, fig. 106; p1. 51, 

figs. 1-9. 

Coal Measures: Near Kansas City, Mo. 

1895. Retzia mormoni. Keyes, Missouri Geol. Surv., vol. 5, p. 95, pl. 41, figs. 2a-c. (Date of imprint 

1894.) 

Upper Coal Measures: Kansas City and Lexington, Mo. 

1896. Retzia radialis. Smith (non Phillips), Am. Phil. Soc., Proc., vol. 35, p. 241. 

Upper Coal Measures: Sebastian County, Ark., and Poteau Mountain, Indian Territory. 

1896. Retzia radialis. Smith (non Phillips), Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside Lab., No. 9, p. 31. 

Upper Coal Measures: Sebastian County, Ark., and Poteau Mountain, Indian Territory. 

1900. Hustedia mormoni. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 103, pl. 9, figs. 10-10d, 

pl. 10, fig. 3. 

Upper Coal Measures: Fort Scott, Iola, Kansas City, Lawrence, Lecompton, Topeka, Beaumont, ' 

Kans. 

This also is one of the rarer species in our Colorado collections. Though abundant in the Elk Mountains at station 2280, but few individuals have been collected 

elsewhere. 

Locality and horizon.—Crested Butte district (stations 2280, 2297, 2303, 2306); 

Maroon formation. 

PUGNAX Hall and Clarke, 1893. 

PUGNAX UTAH MarCOU. 

Pl. VII, figs. 14-14b. 

1852. Terebratula pugnus. Roemer, Kreid. von Texas, p. 89. 

Carboniferous: San Saba Valley, Texas. 

1858. (February) Terebratula uta. Marcou, Geol. North America, p. 51, pl. 6, figs. 12-12c. 

Mountain limestone: Near Salt Lake City, Utah. 

1858. (June) Rhynconella (Camarophoria) osagensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, 

p. 219. 

Upper Coal Measures: Missouri and Kansas. 

1859. Rhynchonella uta. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 27. 

Upper Coal Measures: Manhattan, Kans. 

1861. 	Rhynchonella uta. Newberry, Ives's Colorado River Expl. Exped., p. 128. 

Upper Carboniferous: Near mouth of Little Colorado River. 
DESCRIPTIONS OF SPECIES. 413 

1861. Rh,ynchonella species. Salter, Geol. Soc. London, Quart. Jour., vol. 17, p. 64, pl. 4, fig. 5. 

Carboniferous: Isthmus of Copacabana, Lake Titicaca. 

1866. Camarophoria globulina. Geinitz, Carb. and Dyas in Nebraska, p. 38, tab. 3, fig. 5. (Not C. 

globulina Phillips.) 

Tipper Coal Measures: Bennett's Mill and Nebraska City, Nebr. 

1872. Rhynchonella osagensis. Meek, U. S. Geol. Surv. Nebraska, p. 179, pl. 1, figs. 9a, b, pl. 6, figs. 

2a, b. 

Upper Coal Measures: Nebraska City, Nebr. 


Coal Measures: Iowa, Missouri, Kansas. 


Upper Middle, and Lower Coal Measures: Illinois. 


1873. Rhynchonella osagensis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 571, pl. 26, 

fig. 22. 

Coal Measures: Danville, Ill., and Fulton County, Ill. 

1875. Rhynchonella uta. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 128, pl. 9, 

figs. 2a-c. (Whole volume published in 1877.) 

Carboniferous: North Fork of Lewiston Canyon, Oquirrh Range, and at Meadow Creek, south of 

Fillmore, Utah. 

1884. Rhynchonella uta. White, Geol. Surv. Indiana, 13th Rept., p. 132, pl. 25, fig. 6. 

Coal Measures: Indiana. 

1891. Rhynchonella uta. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 247. 

Lower Coal Measures: Des Moines, Iowa. 

1893. Pugnax uta. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 204, pl. 60, figs. 39-42. 

(Advance distribution in fascicles). 

Coal Measures: Manhattan, Kans. 

1894. Pugnax uta. Hall and Clarke, Int. Study of Brach., pt. 2, pl. 44, figs. 17-19. 

Coal Measures: Manhattan, Kans. 

1895. Rhynchonella uta. Keyes, Missouri Geol. Surv., vol. 5, p. 103, pl. 41, fig. 7. (Date of imprint, 

1895.) 

Upper Coal Measures: Kansas City and Lexington, Mo. 

1895. Pugnax uta. Hall and Clarke, Pal. New York, vol. 8, pt. 2, p. 204, pl. 60, figs. 39-42. 

Coal Measures: Manhattan, Kans. 

1897. Rhynchonella uta. Smith, Am. Phil. Soc., Proc., vol. 35, p. 30. 

Upper Coal Measures: Sebastian County, Ark., and Poteau Mountain, Indian Territory. 

1900. Pugnax utah. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 93, pl. 12, figs. 7-7c. 

Upper. Coal Measures: Bronson, Bourbon County, Kansas City, Iola, Olathe, Lawrence, Lecompton, Topeka, Beaumont, Grand Summit, Kans. 

This. also is a rare species, having been found at but two localities. 

Locality and horizon.—Crested Butte district (stations 2280, 2305); Maroon 

formation. 
414 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PELECYPODA. 

AVICULOPECTEN McCoy, 1851. 

AVICULOPECTEN OCCIDENTALIS Shumard. 

Pl. VIII, fig. 1. 

1855. Pecten occidentalis. Shumard, Missouri Geol. Surv., p. 207, pl. C; fig. 18. 

Coal Measures: Near Plattsburg, Clinton County, Mo. 

1858. Pecten cleavelandicus. Swallow, Ackl. Sci. St. Louis, Trans., vol. 1, p. 184. 

Permian: Valley of South Cottonwood, Kansas. 

1861. Pecten occidentalis. Newberry, Ives's Colorado River Expl. Exped., p. 128. 

Coal Measures: Banks of the Stranger, above Easton, Kans. 

1864. Aviculopecten ? Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 192, p. 50, 

pl. 2, fig. 10. 

Permian: Near Chapman's Creek, 18 miles above Fort Riley, Kans. 

1866. Aviculopecten occidentalis. Meek and Worthen, Geol. Surv. Illinois, Rept. , vol. 2, p. 331, pl. 27, 

figs. 4, 5, 5a. 

Upper Coal Measures: Saline Creek, Gallatin County, Ill. 

1866. Pecten missouriensis? Geinitz, Carb. and Dyas in Nebraska, p. 35, tab. 2, fig. 18. 

Upper Coal Measures: Nebraska City, Nebr. 

1872. Aviculopecten occidentalis. Meek, U. S. Geol. Surv. Nebraska, p. 191, pl. 9, fig. 10. 

Upper Coal Measures: Rock Bluff, Bennett's Mill, Wyoming, and Nebraska City, Nebr.; Illinois, Missouri, Iowa, Kansas, Kentucky. 

Coal Measures: Black Hills, Dakota. 

1876. Aviculopecten occidentalis. White, Powell's Rept. Geol. Uinta Mountains, p. 90. 

Lower Aubrey group: 2 miles above Belleview, Utah. 

1877. Aviculopecten occidentalis. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 146, 

pl. 12, figs. 8a, b. 

CarboniferouF: Camp Apache, Ariz. 

1884. Aviculopecten occidentalis. White, Geol. Surv. Indiana, 13th Rept., p. 143, pl. 28, fig. 2. 

Coal Measures: Pike and Gibson counties, Ind. 

1886. Aviculopecten occidentalis. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 455, 

fig. 5a, p. 442, fig. 5. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Aviculopecten occidentalis. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 

2, p. 270, fig. 5, p. 271, fig. 5a. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1891. Aviculopecten occidentalis. White, U. S. Geol. Surv., Bull. No. 77, p. 29, pl. 4, fig. 1. 

Permian: Military Crossing, Baylor County, Tex. 

1894. Aviculopecten occidentalis. Keyes, Missouri Geol. Surv., vol. 5, p. 110, pl. 42, fig. 3. 

Upper Coal Measures: Plattsburg and Kansas City, Mo. 

1897. Aviculopecten occidentalis. Smith, Am. Phil. Soc., Proc., vol. 35, p. 34. 

Lower Coal Measures: Conway County, Ark. 
DESCRIPTIONS OF SPECIES. 415 

1899. Aviculopecten occidentalis. Girty, U. S. Geol. Surv., Nineteenth Ann.. Rept., pt. 3, yp. 578. 

Upper Coal Measures: McAlester quadrangle; Atoka quadrangle. 

1900. Aviculopecten occidentalis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 114, pl. 13, fig. 7. 

Upper Coal Measures: Turner, Eudora, Lawrence, Topeka, Wabaunsee County, Kans. 

1900. Aviculopecten occidentalis. Knight, Univ. Wyoming, Wyoming Exp. Sta., Bull. No. 45, pl. 3, fig. 3. 

This species is rare and small in the collections from the Hermosa formation, but 

in those frpm the Rico formation it is usually both large and fairly abundant. 

The specimens from station 2219, in the Rico quadrangle, are poorly preserved, 

and some of them look much as if they might belong to Lima rehfera. The fact 

can not, however, be satisfactorily ascertained, and since some of the specimens certainly do not belong, to that species, it seems best to give the others no separate 

record. 

Locality and horizon.—San Juan region (stations 2219, 2231, 2337, 2340, 2341, 

2342, 2347); middle portion of the Hermosa formation and common in the Rico formation. Crested Butte district (station 2317 ?), Maroon formation. 

AVICULOPECTEN PELLUCIDUS Meek and Worthen. 

1860. Aviculopecten pellucidus. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 455. 

Coal Measures: Adams County, Ill. 

1866. Aviculopecten pellucidus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 327, pl. 26, figs. 

5a, b. 

Lower Coal Measures: Adams County, Ill. 

Only one specimen of this species has come to hand, and that broken. In its 

small size and cancellated surface ornamentation the specimen resembles Meek and 

Worthen's species, but a satisfactory identification is not possible. 

Locality and h,orizon.—San Juan region (station 2221); upper portion of the 

Hermosa formation. 

AVICULOPECTEN RECTILATERARITJS COX. 

1857. 	Avicula recta-laterarea. Cox, Geol. Surv. Kentucky, vol. 3, p. 571, pl. 9, fig. 2. 

Coal Measures: Union County, Ky.; Gallatin County, Ill. 

1898. Aviculopecten rectilaterarius. Drake, Am. Phil. Soc., Proc., vol. 36, p. 405, pl. 9, fig. 6. Reprinted 

without change of date, page, etc., in Leland Stanford Junior University Pub.; Cont. Biol. 

Hopkins Seaside Lab., No. 14. 

Upper Coal Measures, Poteau group: In shale overlying the Mayberry coal at the mines 4 miles 

northwest of Poteau, Ind. T. 

1900. Aviculopecten rectilaterarius. Beede, Univ. Geol. Surv. Kansas, Rept., vol., 6, p. 15. 

Upper Coal Measures: Leavenworth, Wyandotte County, Kans. 

None of the material is well preserved, and from station 2226 (in the Rico quadrangle) but a single specimen was obtained. The fossils from Leadville received the 

same identification in the monograph of that region.a 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 67.

.
416 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

_Locality and horizon.—San Juan region (station 2226); upper portion of the 

Hermosa formation. Leadville district (station 2264); base of the Weber formation. 

AVICITLOPECTEN ? INTERLINEATUS Meek and Worthen. 

Pl. VIII, fig. 3. 

1860. Aviculopecten interlineatus. Meek and Worthen, ACad. Nat. Sci. Philadelphia, Proc., p. 454. 

Upper Coal Measures: Lasalle, Ill. 

1866. Aviculopecten interlineatus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 329, pl. 26, 

fig. 7a, b. 

Upper Coal Measures: Lasalle, Ill. 

1877. Aviculopectenf interlineatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 149, 

pl. 11, fig. 3a. 

Carboniferous: Confluence of White Mountain and Black rivers, Arizona. 

1884. Aviculopecten(f) interlineatus. White, Geol. Surv. Indiana, 13th Rept., p. 145, pl. 30, fig. 9. 

Coal Measures: Indiana(?). 

1891. Aviculopecten interlineatus. Whitfield, New York Acad. Sci., Ann., vol. 5, p. 604, p1. 16, figs. 10, 11. 

Coal Measures: Hocking. County, Ohio. 

1894. Aviculopecten? interlineatus. Keyes, Missouri Geol. Surv., vol. 5, p. 112, pl. 42, fig. 6. 

Upper Coal Measures: Kansas City, Mo. 

1895. Aviculopecten interlin,eatus. Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 489, p1. 12, figs. 10, 11. 

Coal Measures: Falls Township, Hocking County, Ohio. 

1900. Aviculopecten interlineatus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 116, pl. 13, fig. 6. 

Upper Coal Measures: Kansas City, Kansas. 

. This well-marked species is represented by but two specimens, as usual each 

from a different locality. Both valves are present, one of which (the left) is shown 

by fig. 3 on Pl. VIII. Each of the broad concentric bands is terminated below by a 

thin, high ridge vertical to the surface, and there art number of intermediate ridges 

which are considerably smaller and less prominent. 

The right valve has much the shape of the right valve of A. occidentals. It differs 

from the left in having the anterior ear narrower and bounded below by a deep sinus. 

The surface is marked by broad concentric bands and delicate sublamellose striae, but 

seems to lack the elevated ridges by which the opposite valve is characterized. The 

strive are more or less wavy and irregular. There are also indications of very faint, 

irregular, intermittent, radiating ribs which, though visible without a glass, can 

only be seen in a favorable light. 

While the shape of the right valve of this species is very like the corresponding 

one of A. occidentalis, the difference in surface characters is such that, when 'once 

noted, there is little danger of mistaking one for the other. 

_Locality and horizon.—Crested Butte district (station 2293); Maroon formation. 
DESCRIPTIONS OF SPECIES. 417 

AVICULOPECTEN sp. a. 

P1. VIII, fig. 2. 

Of this little shell we have only the specimen which is illustrated by fig. 2 of Pl. 

VIII. I have not been able to refer it satisfactorily to any of our numerous pectinoid 

species, but it seems to be closely related to A. coxanus Meek and Worthen. I would 

scarcely consider it identical with the Nebraska form which Meek identified with A. 

coxanus, but it so closely resembles the figure of the original reference that I would 

probably have referred it to Meek and Worthen's species if it were not that in their' 

figure the ears are clearly shown to be marked with radiating ribs, a character which 

my specimen does not possess. Besides this character, it differs from the Nebraska 

form in having the striae finer and more crowded. Of these, there are 17 or 18 in the 

space of 5 mm. They are thin and sharp, somewhat alternating, and separated by 

intervals slightly greater than their own thickness. There are also faint concentric 

growth lines, and these are the only markings which appear upon the rather broad 

ears. 

Locality and h,orizon.—Ouray (station 2194); Hermosa formation. 

AVICULOPECTEN sp. b. 

From Ouray we have a single specimen of an undetermined but fine and striking 

species of Aviculopecten. The fossil is crushed and very imperfect, and its configuration can not be ascertained. It is a large shell, however, and must have had a 

length of 45 mm. or more. The surface is marked by coarse, regular, somewhat 

flattened, rigid ribs, of which near the outer margin there are about 6 or 7 in the 

space of 10 mm. They are separated by flat shallow grooves about as wide as, or 

sometimes a little wider than, the intervening ribs. The whole is crossed at intervals 

of about 1 mm. by very regular, Lrongly lamellose concentric striae. 

This is a fine, large, and well-characterized species, and, as far as I have ascertained, it is as yet undescribed. 

Locality and horizon.—Ouray (station 2194); Hermosa formation. 

ACANTHOPECTEN new subgen. 

This name is proposed to receive Aviculopecten carboniferus Stevens, and while 

at present no higher significance is assigned to it than as subgeneric to Aviculopecten 

(or possibly Lima) it is not improbable that it will subsequently be found to take 

rank as an independent genus. 

The large, angular plications of this species and its spinose rim and growth lines 

give it an expression so strongly marked that even upon the consideration of its 

superficial characters I would be disposed to separate it from the more usual types 

referred to Aviculopecten, and Meek, who was, I believe, the first to suggest that it 

14364—No. 16-03 27 
418 CARBONIFEROUS' FORMATIONS AND FAUNAS OF COLORADO. 

belonged to a hitherto undescribed genus, pointed out characters which, if not the 

result of imperfect preservation, as seems unlikely, would certainly entitle it to such 

a position. He says "The only specimens of this species I have seen consist 

entirely of what seems to be the thin outer layer of the shell, in which there appears 

to be a prismatic structure, as seen by the aid of the microscope and a strong transmitted light. They show no flattened cardinal plate, but a furrow along the inner 

side of the hinge margin of each valve. The cardinal plate or area was doubtless 

composed, as in other cases, of the inner laminated portion of the shell, that has 

been destroyed during the fossilizing process; if not, it would seem to be a new 

genus."a 

The very characteristic spines with which Acanthopecten, is armed, projecting 

from the surface and from the margin, are suggestive of a genus to be developed at 

a much later geologic period, Spondylus, in which the spines often play an important part in the matter of surface ornamentation. 

ACANTHOPECTEN CARBONIFERUS Stevens. 

1858. Pecten carboniferus. Stevens, Am. Jour. Sci., (2), vol. 25, p. 261. 

Coal Measures: Crooked Creek, Marion County, Ill. 

1863. Pecten broadheadii. Swallow, Acad. Sci. St. Louis, Trans., vol. 2, p. 97. 

Upper Coal Measures: Harrison County, Mo. 

1866. Pecten hawni. Geinitz, Carb. and ryas in Nebraska, p. 36, tab. 2, figs. 19a, b 

Coal Measures: Nebraska City, Nebr. 

1872. Aviculopecten carboniferus. Meek, U. S. Geol. Surv. Nebraska, p. 193, pl. 4, fig. 8; pl. 9, figs. 4a, b. 

Upper Coal Measures: Nebraska City, Nebr. 

Coal Measures: Iowa; Illinois; West Virginia. 

1874. Aviculopecten carboniferus. Meek, Am. Jour. Sci., (3), vol. 7, p. 489. 

1884. Aviculopecten carboniferus. White, Geol. Surv. Indiana, 13th Rept., pt. 2, p. 144, pl. 28, figs. 5-6. 

Coal Measures: Lick Branch, near Silverwood, Fountain County, and in Vermilion County, Ind. 

1887. Aviculopecten carboniferus. Herrick, Sci: Lab. Denison Univ., Bull., vol 2, p. 67, pl. 3, fig. 13. 

Coal Measures: Flint Ridge, Ohio. 

1894. Aviculopecten carboniferus. Keyes, Missouri Geol. Surv., vol. 5, p. 111, pl. 43, figs. 4a, b. 

Upper Coal Measures: Kansas City, Mo. 

1897. Avicalopecten carboniferus. Smith, Am. Phil. Soo., Proc., vol. 35, p. 33. 

Lower Coal Measures: White and Conway counties, Ark 

1900. Aviculopecten carboniferus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 117, pl. 13, fig. 9. . 

Upper Coal Measures: Kansas City, Turner, Eudora, Lawrence, Lecompton, Topeka, Kans. 

This strongly characterized species, seems to be rare in the Colorado Carboniferous faunas. It has been found at buLt few localities, and is represented by no more 

than a single specimen at each. 

Locality and Horizon.-San Juan region (stations 2204, 2205, 2226, 2238, 2342); 

upper portion of the Hermosa formation and in the Rico formation. Leadville 

region (station 2259). 

a U. S. Geol. Surv. Nebraska, 1872, p. 194. 
DESCRIPTIONS OF SPECIES. 419 

ENTOLIUM Meek, 1865. 

ENTOLIUM ? sp. 

There is only one specimen representing this species. It is too poor for determination, and is considered here only because it seems to form the basis for the 

identification which is recorded in the faunal list of the Leadville monograph.a 

locality and horizon.—Leadville district (station 2275); upper portion of the 

Weber formation. 

STREBLOPTERIA McCoy, 1851. 

STREBLOPTERIA TENUILINEATA Meek and Worthen. 

1860. Pecten tenuilineatus. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 452. 

Upper Coal Measures: South line of Clinton County, Ill. 

1866. $rebloptericif tenuilineata. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 334, pl. 26, 

figs. 9a, b. 

-Upper Coal Measures: South line of Clinton County, Ill. 

We have this species from three localities, but it is represented by only a single 

specinien at each. The material is fragmentary as well as scanty, so that it is identified with some doubt. The surface appears to be the same in all, but is best shown 

by the example from station 2221 (Rico quadrangle, Sandstone Mountain), which is 

as to other characters very imperfect. Even with a glass only faint concentric striae 

can be made out, which partake rather of the nature of growth lines than of ornamentation. A small area on the specimen from Ouray (station 2195b), shows very 

fine radiating striae, which may be due to shell structure, or possibly to mineralization. The largest and most perfect specimen is that last mentioned. In size and 

configuration it closely resembles the right valve of Streblopteria tenuilineata. The 

anterior ear, however, shows some faint markings which might be interpreted as ribs 

if it could be shown that they are not accidental. This character rather suggests the 

form Euchondria neglecta Geinitz, but the shape is not right for that species. A 

smaller somewhat less perfect example from station 2216 (Rico quadrangle, Sandstone Mountain) has the shape of the larger one just mentioned, but the anterior ear 

is clearly seen to be marked with rather la mellose concentric strive without a trace of 

ribs. I am not confident, owing to the fragmentary character of one of the specimens that all three belong to the same species, but those from stations 2216 and 2195b 

are probably conspecific with each other and with the species cited above. 

Locality and horizon.—San Juan region (stations 2216, 2221); upper portion of 

the Hermosa formation. Ouray (station 2195b); Hermosa formation. 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 70. 
420 CARBONIFEROUS FORMATIONS AND FAUNAS. OF COLORADO. 

MODIOLA Lamarck, 1801. 

MODIOLA ? SUBELLIPTICA Meek. 

1866. Clid9phorus (an. Pleurophorus) occidentals Genitiz Carb. and Dyas in Nebraska, p. 23, tab. 2, 

fig. 6. (Not Pleurophorus occidentalis M. & II., 1858.) 

Upper Coal Measures: Nebraska City, Nebr. 

1872. Madiolaf subelliptica. Meek, U. S. Geol. Surv. Nebraska, p. 211, pl. 10, fig. 5. 

Upper Coal Measures: Nebraska City, Nebr.; Riverside, 3 miles below Atchison, Kans. 

1881. Pleurophorns subcostatus. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., 

Appendix, p. xxvii, pl. 3, fig. 8. 

Carboniferous: Coyote Creek, New Mexico. 

1900. Mocliola subelliptica. Beede, TJniv. Geol. Surv. Kansas, Rept., vol. 6, p. 136. 

Upper Coal Measures: Topeka, Kans. 

This form is represented by only two specimens found each at a different 

locality. It is probable that it does not belong, strictly speaking, to the genus 

Ifodiola, but it is so thin and delicate that characters of hinge and muscle scars are 

not shown. 

species. 

tatus I 

the Hermosa formation. 

The form from New Mexico which White identifies with 

Locality and horizon.—San 

am convinced, from a direct comparison of specimens, belongs with this 

Juan region (stations 2221, 2233); upper portion of 

Pleurophorus subcosMYALINA de Koninck, 1844. 

MYALINA CUNEIFORMIS Gurley. 

Pl. VIII, figs. 14-17. 

1883. 	Myalina cuneiformis. Gurley, New Carb. Foss., Bull. No. 1, p. 4. 

Upper Carboniferous: Ouray, Colo. 

Through the courtesy of the geological department of the University of Chicago, 

I have been enabled to examine the type specimens of Ilyalina cuneiformis and to 

illustrate the species partially from Gurley's original material. 

The original description of M. cuneiformis is given in the following terms: 

"Shell small, nearly or quite equivalve, long, narrow, attenuated with prominent 

straight subangular umbonal ridge extending from the small, sharp-pointed terminal 

beaks across the shell to the posterior basal margin, attaining its greatest prominence 

about one-fourth of the length of the shell from the beaks, where the thickness of 

the shell is equal to two-thirds its greatest width. 

" Cardinal margin nearly straight, extending almost half the length of the shell 

and gracefully curving into the posterior margin, which is slightly flattened and 

oblique, regularly rounding down and around, joining the anterior basal margin just 
DESCRIPTIONS OF SPECIES. 421 

anterior to the posterior extremity of the umbonal ridge, from thence the basal 

margin passes in a straight line to the beaks. 

"The anterior basal area is nearly straight, flat, broad,Islightly giping and very 

much depressed, a great portion of the surface being almost on the same plane with 

the umbonal ridges. 

"Surface marked by fine concentric lines of growth, which are barely perceptible 

along the more prominent parts of the shell. 

" Length, 15 mm. ; breadth, 5.5 mm; greatest thickness, 4 mm. 

"This species somewhat resembles M. perattenuata, M. & H., but is readily 

distinguished from that shell by its more angular and prominent umbonal ridge, 

flattened, depressed anterior basal area, and by being more attenuated. 

"Position and locality.—From a hard, dark micaceous sandy shale belonging to 

the Upper Carboniferous series and probably equivalent to the Middle Coal Measures, 

Ouray, Colo." 

With the types of both species before me the differences pointed out by Gurley 

by which M. euneiformis might be distinguished frau M. perattenuata do not in the 

main hold good, though for the present at least I shall retain his species as distinct. 

11/1. perattenuata ­seems to have the umbonal ridge directed at a slightly less acute 

angle with the hinge line. It is possibly proportionally more elongate and has the 

posterior cardinal angle better marked. This portion of the shell has the appearance 

of being truncated (if the present specimens are not imperfect). The shape of 

M. perattenuata, in other words, approaches a parallelogram, that of M. euneiformis 

a triangle. 

At station 2314 in the Crested Butte region were collected several slabs of black 

limestone abundantly covered with a small species of Mallina in fragments and entire 

valves, which is closely related to IL euneiformis Gurley. The geologic horizon 

is also probably the same. Though a number of individuals were collected, all the 

material is so badly weathered that only one or two specimens are at all available for 

illustration, while the entire series affords but an unsatisfactory concept of the species. 

Since examining the types of. Gurley's species I am somewhat more inclined to 

doubt the correctness of the identification of these Crested Butte fossils than when 

dependence was placed upon his description alone. I have not, however, altered the 

identification originally set down, but leave the decision as to its correctness to be 

decided by more complete material. 

The configuration which my specimens originally possessed can at present only 

be estimated, but so far as I can judge the angle between the umbonal ridge and the 

hinge line is somewhat less acute than in the types. 

Locality and horizon.—Originally described from the lowest exposed Carboniferous beds at Ouray, probably the same as station 2195. Crested Butte district (station 

2314); Weber limestone. 
422 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

MYALINA WYOMINGENSIS Lea. 


Pl. VIII, figs. 8, 9, 10, 11, 12, 13. 


1853. Modiola wyomingensis. Lea, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 2, p. 205, pl. 20, fig. la. 


Coal Formation: Wilkesbarre, Pa. 

1886. Modiola wyomingensis. Claypole, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p. 247. 

Lower Coal Measures: Wilkesbarre, Pa. 

1898. Myalina wyomingensis. Weller, U. S. Geol. Surv., Bull. No. 153, p. 365. 

Shell of medium size; shape, subtriangular to subquadrangular. Hinge line 

straight, long; beak nearly but not quite terminal. Umbonal ridge well marked, 

meeting the hinge line at an angle of about 45°. Anterior outline sinuate, converging below with the umbonal ridge, which becomes less elevated in this direction. 

The posterior outline is often nearly straight in its upper portion and parallel with 

the anterior margin, but it is more strongly curved below and its junction with the 

anterior outline is subangular. The shape of such a specimen resembles that of a 

parallelogram. In some examples, however, the hinge line is proportionately longer, 

and the posterior margin makes a more or less regular, obliquely directed curve 

from the hinge line to its union with the anterior outline. The shape resulting is 

subtriangular, and all gradations exist between the two. Variation precisely similar 

is seen in Myalina permiana Swallow. The elongated form Swallow describes as 

M. permiana; to the triangular one he gave the name M. concava. This fact has 

been pointed out by Meek and Hayden," who place the latter species in the synonymy of the former. I do not consider this variation of specific importance in the 

case of M. wyomingen,sis, and certainly it seems no more than varietal in the case of 

M. permiana. 

The surface seems to be marked by lamellose striae, which are particularly prominent on the peripheral areas of the shell. 

This species is closely related to 211. permiana and shows many points of resemblance. At first, indeed, I identified my material with Swallow's species with but 

little reserve, but a critical revision has compelled me to recall this decision. The 

differences which distinguish them reside chiefly in the anterior portion of the shell. 

In M. permiana the umbones are terminal and the umbonal ridge is so near the 

anterior outline that where the chief emargination of the latter occurs the umbonal 

ridge actually overhangs the shell margin. In ilf. wyomingensis the umbones are 

not quite terminal and there is always a more or less well-developed anterior lobe. 

The anterior outline is farther from the umbonal ridge in the upper part of the 

shell, and the anterior side there falls away less abruptly than is the case below, 

where, though the ridge is not so high, it slopes off to the plane of the shell edge in 

° Smithsonian Cont. Knowledge, vol. 14, No. 172, 1865, p. 52. 
DESCRIPTIONS OF SPECIES. 423 

a direction nearly normal to the latter. The anterior lobe seems to be always more 

or less developed, and though the extreme form in one direction comes close to 

M. permiana, it is even then strong enough to differentiate the two. 

M. wyomingensis also resembles M. aviculoides, but a comparison of my material 

with the type specimens of the latter leaves me convinced that they are distinct. I 

need only point out the strong curve of the umbonal ridge at its upper end and its 

direction below for most of its length at nearly right angles to the hinge line. Other 

points of variance will readily be seen by comparing the figures of the two species. 

But perhaps the most similar form is M. swallowi McChesney, which is a modioliform shell much resembling AL wyomingensis in shape, but with a sharper backward 

sweep of the umbonal ridge. In Lea's species also the junction of the cardinal and 

the posterior outline is angular, while in McChesney's form the posterior outline merges 

imperceptibly into that of the cardinal margin. However, no comparison with 

swallowi seems to be necessary, because there is evidence for believing that it is 

generically distinct. It has a rather strong individuality of expression when compared with other specimens of Illyalina, and certainly seems to show structural differences which make its removal from de Koninck's genus desirable. Meek a was, I 

believe, the first to call attention to this fact. Specimens from several localities 

preserved as internal casts show that this form does not possess the massive striated 

hinge plate which characterizes Alyalina, but that, on the other hand, the cardinal 

margin is thin and linear, with a long cartilage groove. It would seem, therefore, 

that M. swallowi should be removed from _31yalina. - It can be referred, provisionally at least, to Maiola. 

I hardly need compare with M. kansasensis, which, while it is somewhat similar, 

lacks the interior lobe of Lea's species and is distinguished from all others known to 

me by the fluted lamellae with which the surface is covered. 

The preceding description and comparisons are based upon material from the 

Rico formation of the San Juan region which I had prepared to publish as a new 

ensis, 

ensis, 

species when fortunately there came into my hands the types of 

I find that my Rico fossils, which possibly hold about the same geologic horizon as 

the Pennsylvania fauna; agree in the closest manner with the types of 

duced at this place typical figures for comparison. 

Lea's species whose characters have so long been problematical, I have not introearly opportunity to redescribe, refigure, and discuss from the type material all of 

which Lea described in 1853, from the Northern Anthracite field of Pennsylvania. 

and I can not consider their specific identity as doubtful. As I shall seek an 

ilyaUna wyomingX. wyomingwyomingensis is extremely abundant at Scotch Creek (station 2340). 

What I take to be the same form occurs also at Graham, Young County, Tex., and 

a17. S. Geol. Surv. Nebraska, etc., 1872, p. 202. 
424 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

at Beaumont, Butler County, Kans. A single specimen from the Leadville region 

also has been referred here. It can not be identified with certainty, but seems to be 

nearest to 31. wyomingmsi,s. 

_Locality and horizon.--San Juan region (stations 2340, 2341, 2342, 2345, 2349); 

Rico formation. Leadville district (station 2257); base of the Weber formation. 

MYALINA SUBQUADRATA Shumard.? 

Pl. VIII, figs. 6, 7. 

1855. Myalina subquadrata. Shumard, Missouri Geol. Surv., p. 207, Pl. C, fig. 17. 

Upper Coal Measures: On Missouri River, 2 miles below the mouth of the Little Nemaha. 

1864. Myalina subquadrata. Meek and Hayden. (pars), Smithsonian Cont. Knowledge, vol. 14, No. 

172, p. 32. 

Coal Measures: Leavenworth City, Kans. 

1866. Myalina subquadrata. Geinitz, Carb. and Dyas in Nebraska, p. 27, tab. 3, figs. 25, 26: 

Upper Coal Measures: Nebraska City, Nebr. 

1872. Myalina subquadrata. Meek, U. S. Geol. Surv. Nebraska, p. 202, pl. 4, fig. 12; pl. 9, fig. 6. 

Upper Coal Measures: Nebraska City, Bennetts Mill, and Bellevue, Nebr. 

1884. Myalina subquadrata. White, Geol. Surv. Indiana, 13th Rept., p. 140, pl. 29, figs. 1, 2; p1. 30, 

figs. 1, 2. 

Upper Coal Measures: Knox, Gibson, and Posey counties, Ind. 

1886. Myalina subquadrata. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 456; 

p. 446, fig. 15; p. 454, fig. 15a. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Myalina subquadrata. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p.4 273, fig. 15a; p. 274, fig. 15. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1895. Myalina subquadrata. Keyes, Missouri Geol. Surv., vol. 5, p. 118, pl. 44, figs. la, b, 2a, b. 

(Date of imprint, 1894.) . 

Upper Coal Measures: Kansas City, Mo. 

1900. Myalina subquadrata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 138, pl. 16, figs. 10, 10b. 

Carboniferous: Kansas City, Melvern (Osage County), Topeka, Lawrence, Kans. 

1900. Myalina subquadrata. Knight, Univ. Wyoming, Wyoming Exp. Sta., Bull. No. 45, pl. 3, fig. 1. 

This well-known and widely distributed species is represented in several of the 

collections examined, and by a number of specimens. In the Rico formation of the 

San Juan region it is abundant and attains a large size, especially on the Dolores 

River (station 2343) and on Scotch Creek (station 2340). I have identified it also in 

the Hermosa formation of the same region, in Big Percent Creek (station 2200), and 

on the west side of the Animas Valley (station 2205). In the Hermosa formation, 

however, it is represented by .a few small shells, fragmentary and poorly preserved. 

Associated with the larger specimens at station 2205 an isolated left valve was found 

having a smaller size and a more oblique shape. The length along the hinge line is 

only 13 mm. and the axis is inclined to the hinge at an angle of about 450. The. gen-
DESCRIPTIONS OF SPECIES. 425 

eral appearance of the shell is quite unlike .M. s• bquadrata, but the growth lines on 

mature subquadrata show that certain of its you ger stages must hate closely resembled the shell under discussion, even suggesting the form commonly referred to M 

swallowi. I have therefore provisionally inclu ed this specimen under the common 

title of Myalina subquadrata, though a different course might have resulted from the 

consideration of more complete material. 

Most of this material exhibits departures more or less extensive from the type 

for which the name was originally proposed, an4 I am not sure that they can appropriately be considered to belong to Shumard's species, except as well-marked varieties. Two diverse types are shown by figs. 6 arid 7 of Pl. VIII. In one case it was 

necessary, as indicated in the figure (7), to considerably restore the originally broken 

specimen, but the lines of growth have been followed as faithfully as possible, and 

the shape represented is probably close to the priginal. 

Locality and horizon.—San Juan region (stations 2200?, 2205?, 2340, 2341, 2342, 

2344, 2345); upper portion of the Hermosa f?rmation, and abundant in the Rico 

formation. 

MYALINA PERATTENUATA eek and Hayden ? 

1858. Myalina (Mytelus) perattenuata. Meek and Hayden, Albany Inst., Trans, vol. 4, p. 77. 

Permian: Smoky Hill Fork, Kansas and Missouri rivers. 

1859. Myalina (Mytilus) perattenuata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 28. 

Upper Coal Measures: Smoky Hill River, Kansas. 

1864. Myalina perattenuata. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, p. 32, 

pl. 1, figs. 12a, b. 

Coal Measures: Opposite the northern boundary of Missouri on the Missouri River. 

1866. Myalina perattenuata. Geinitz, Carb. and Dyas in Nebraska, p. 27, pl. 2, figs. 10, 11. 

1873. Myalina perattenuata. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 582, p1.26, fig. 11. 

Coal Measures: Springfield, Illinois. 

1891. Myalina perattenuata. White, U. S. Geol. Surv., Bull. No. 77, p. 28, pl. 4, figs. 13-15. 

Permian: Goodwin Creek and Military Crossing, Baylor County, Tex.; Camp Creek, Archer 

County, Tex. 

1895. Myalina perattemtata. Keyes, Missouri Geol. Surv., vol. 5, p. 118. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1900. Myalina pera,ttenuata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 141, pl. 16, fig. 

Upper Coal Measures: Topeka, Kans. 

After eliminating the types referred 'to klyalina subquadrata and to IL 

wyomingensis several specimens remain, unfortunately in not very good condition, 

which resemble Meek and Hayden's species cited above. The shell, however, is a 

large one, as the fact that the larger examples exceed 100 mm. in length will attest. 

Some of these also approach M. exasperata Beede. Doubtless, were the material less 

imperfect, it would be possible to make a more satisfactory determination, and the 

identification might not in every case be Myalina perattenuata. 

Locality and horizon.—San Juan region (stations 2337, 2340); Rico formation. 
426 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

MYALINA PERNIFORMIS COX ? 

1857. Myalina pernaformis. Cox, Geol. Surv. Kentucky, vol. 3, p. 569, pl. 8, fig. 8. 

Coal Measures: Providence, Hopkins County, Ky. 

At station 2187 was obtained a single specimen of Myalina which I have referred 

to Myalina perniformis. Its somewhat crushed condition prevents a satisfactory 

reference. The shape and size, which gives a measurement of 31 mm. in the longest 

diameter, are almost precisely those of perniformis as illustrated by Cox. The 

surface is largely exfoliated. The portions which remain, however, lead me to 

believe that it did not have the strong concentric, almost fimbriating, lines of growth 

described by Cox. My specimen is related also to M. a_pach,esi and M perattenuata, 

but it is nearest X. perniformis. It also resembles the species which I have referred 

to 111. cuneiformis Gurley, but differs from it in having the umbonal ridge slightly 

less oblique to the hinge line, and in having a somewhat more quadrate shape. 

Locality and horizon.--San Juan region (station 2187); Molas formation. 

POSIDONIELLA de Koninck, 1885. 

POSIDONIELLA PERTENUIS Beede? 

1895. _Nacunopsis carbonaria. Keyes, Missouri Geol. Surv., vol. 5, p. 108, p1. 43,. fig. 9 (date of 

imprint 1894). 

Upper Coal Measures: Kansas City, Mo. 

1899. Posidonomya pertenuis. Beede, Kansas Univ. Quart., vol. 8, p. 127, pl. 32, fig. 5. 

Coal Measures: From near the dam at Lawrence, Kans., and from the same stratum at Camerons 

Bluff, 3 miles up the river. 

1900. Posidonomya? pertenuis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 136, pl. 19, fig. 5. 

Upper Coal Measures: Lawrence, Kans. 

This form is represented by a single specimen obtained at station 2341 in the 

Rico formation (Scotch Creek). Although not very perfectly preserved, the characters, made out as well as possible, would indicate that this specimen in its specific 

relations is very close to that which Keyes figures as Placunopsis carbonaria (see synonymy). Beede has called attention to the fact that this shell is quite unlike the form 

to which Meek and Worthen gave the name P. carbonaria. Although the latter is 

characteristically ornamented with radial markings, Meek and Worthen themselves 

figure a shell as Pl. carbonaria (their fig. 2b), which seems to be smooth, and which 

has, moreover, much the shape of Keyes's specimen. It would appear very much 

as if Meek and Worthen's fig. 2b and possibly also their fig. 2d belonged to the 

same species as the one figured by Keyes, and that this type were distinct from P. 

carbonaria. Beede also suggests that P. carbonaria of Keyes may belong to the 

species which he describes as Posidonomya? pertenuis. P. pertenuis is represented 

by Beede's figure as being a rather elongate form, and as Keyes's figure shows a 

nearly circular one the difference in shape is somewhat against this view. Never-
DESCRIPTIONS OF SPECIES. 427 

theless I have accepted it provisionally in identifying my Colorado specimen. The 

latter has a length of 33 mm. and a width slightly greater. The shape is thtu shown 

to be a little transverse, and it is nearly bilaterally symmetrical. The convexity is 

moderate and is greatest just below the beak, which is small, incurved, and but 

slightly projecting. The hinge line, which is straight and about 18mm. long, merges 

easily into the nearly circular outline. 

Comparing this specimen with Keyes's figure the straight hinge line seems to be 

a trifle longer and the beak incurved instead of erect. Supposing it to be the opposite valve the shape is otherwise nearly identical. 

Both of these-forms differ, from the type of P. pertenuis in being more nearly 

circular. My specimen differs also in having the hinge line represented on both sides 

of the beak. 

Inasmuch as the structural characters of these forms are not known, and as 

dependence has to be placed in determining their generic position upon their general 

configuration, it seems that they would be more correctly referred to Posidoniella 

than to Posidonomya. 

Locality and horizon.—San Juan region (station 2341); Rico formation. 

PSEUDOMONOTIS Beyrich, 1862. 

PSEUDOMONOTIS HAWNI Meek and Hayden. 

1858. Monotis hawni. Meek and Hayden, Albany Inst., Trans., vol. 4, p. 76. 

Permian: Near mouth of Smoky Hill Fork of Kansas River and Helena, Kans. 

1859. Monotis hawni. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 28. 

Upper Coal Measures: South of Kansas Falls, Smoky Hill River, and Cottonwood Creek, Kansas. 

1864. Eumicrotis hawni. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, p. 54, 

131- 2, figs. 5a-c.. 

Permian: Near mouth of Smoky Hill Fork of Kansas River and between there and Council 

Grove; also on Cottonwood Creek, Kansas. 

1884. Eumicrotis hawni. White, Geol. Surv. Indiana, 13th Rept., p. 142, pl. 30, fig. 10. 

Upper Coal Measures: Indiana. 

1886. Eumicrotis hawni. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 455. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Eumicrotis hawni. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, p. 271. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1899. Pseudomonotis cf. hawni. Beede, Kansas Univ. Quart., vol. 8, No. 2, p. 83, pl. 19, figs. 1-1f. 

Upper Coal Measures: Turner, Wyandotte County, Kans.; Clement°, Topeka, Lawrence, Kans. 

1900. Pseudomonotis hawni. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 132, p1. 13, figs. 11-11c; 

pl. 15, figs. 1-1f, 2, 2a. 

Upper Coal Measures: Turner, Lawrence, near Topeka, Kans. 

Four representatives of this species were found at station 2341 (Scotch Creek) in 

the Rico formation, and it seems to be fairly abundant there. This material has 

been compared with the types of Meek and Hayden's species and the identification 
428 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

is believed to be correct. A single poorly preserved specimen which appears to 

belong to the same species was found in the Hermosa formation on the west side of 

Animas Valley (station 2205). 

Locality and horizon.—San Juan region (stations 2205?, 2342); upper portion of 

the Hermosa formation and in the Rico formation. 

PSEUDOMONOTIS EQUISTRIATA Beede. 

Pl. VIII, fig. 5. 

1899. Pseudomonotis hawni equistriata. Beede, Kansas Upiv. Quart., vol. 9, p. 82, pl. 18, figs. 3-3b. 

Upper Coal Measures: Turner, Wyandotte County, Kans.' 

1900. Pseudomonotis hawni equistriata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 134, pl. 14, 

figs. 3-3b. 

Upper Coal Measures: Turner, Kans. 

Of this form but one specimen has come to hand. It differs from that referred. 

to Ps. kansasensis chiefly in being more convex and in having its striae persistently 

and regularly unequal, and from Ps. hawni in having them finer and with much less 

disparity between the coarser and the finer ones. The species to which this specimen belongs seems to be closely related to, if not identical with, Beede's 

monotis hawni 

Locality and horizon.—San 

var. equistriata. 

PSEUDOMONOTIS KANSASENSIS 

Juan region (station 2342); Rico formation. 

Beede. 

PseudoPl. VIII, fig. 4. 

1858. Monotis radiates. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 187. 

Upper Permian: Smoky Hill Fork, Kansas. 

1866. Avicula speluncaria. Geinitz, Carb. and Dyas in Nebraska, p. 28, tab. 2, fig. 12. 

Upper Coal Measures: Nebraska City, Nebr.: Council Grove, Kans. 

1872. Pseudomonotis radialisY Meek, U. S. Geol. Surv. Nebraska, p. 201, pl. 9, fig. 

Upper Coal Measures: Nebraska City, Nebr. 

1887. Cf. Pseudornonotis radialis. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 145, pl. 14, 

fig. 26. 

Coal Measures: Flint Ridge, Ohio. 

1899. Pseudomor,otisf tenuistriata. Beede, Kansas Univ. Quart., vol. 8, p. 81, pl. 18, figs. 1-1d; pl. 19, 

fig. 3. 

Upper Coal Measures: Turner, Wyandotte County, Kans.; Topeka, Kans.; Auburn, Shawnee 

County, Kans. 

1900. Pseudomonotis kansasensis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 133, pl. 14, figs. 

1-1d. 

Upper Coal Measures: Turner, Topeka, Auburn (Shawnee County), Kans. 

Only one specimen has come to hand representing this species, which seems to 

be the one Beede described as Pseudomonotis? tenuistriata, but it differs from typical 
DESCRIPTIONS OF SPECIES. 429 

examples in being more contracted at the hinge line and in having the anterior ear 

more clearly defined. In the synonymy of this form probably belongs Pseudomo 

notis radialis Phillips? of Meek, .and possibly also Avicula speluneularia Geinitz, 

as suggested by Meek. 

Some of the figures given by Meek and Worthen of a form which they referred 

to Plaeunopsis with the specific name P. ca/rbonariaa so much resemble Beede's figures 

of Pseudomonotis kansasensis as to suggest that the former species is generically, if 

not specifically, related to the latter. I am unable to make direct comparisons with 

specimens, as the Illinois form is not represented in our collections. 

Locality and horizon.—San Juan region (station 2342); Rico formation. 

PSEUDOMONOTIS sp. 

This species is represented primarily by a specimen of medium size and preser 

vation from Marguerite Creek (station 2344) in the Rico formation, but to it I have 

also referred two smaller and less perfect examples from two other stations in the 

same formation. 

monotis hawni 

elongate species, having a length of about 19 mm. and a transverse diameter at the 

widcst point of about 15 mm. At the hinge line the width is 10 mm. 

In shape this shell much resembles the form which Beede described as 

var. equistriata and figured on pl. 14 of his report.5 It is a narrow, 

PseudoThe posterior ear is flattened and scarcely distinguished by a gentle sinuosity in 

the outline. The anterior ear is rather inflated and it is defined by a very distinct 

emargination or notch. The posterior outline is nearly straight in its upper portion, 

which meets the hinge line at a slightly obtuse angle. It has a gentle outward curve 

below, and the inferior outline is strongly rounded. The anterior outline is withdrawn 

into a well-marked sinus beneath the anterior ear. The shell is rather strongly 

inflated. 

The surface is marked by a number of moderately distinct wrinkles of growth. 

The ribs are very obscure, somewhat alternating in size, and not distributed with 

precise regularity. There are 8 or 9 in the space of 5 mm. 

The foregoing description is derived from the large example already mentioned. 

The two other specimens are much smaller and much less perfect. Their length is 

slightly over 10 mm. The shape, as well as it can be determined, is similar to that 

of the larger example whose description has just been given. The surface seems to 

be without radial ribs. 

The nearly obsolete character of the surface ornamentation in these specimens 

might seem to indicate that they are right valves, but the shape and strong convexity. 

a Geol. Surv. Illinois, Rept., vol. 5, 1873, pl. 27, figs. 2b and 2d. 

b Univ. Geol. Surv. Kansas, Rept„ vol. 6, 1900, p. 134, p1. 14, fig. 3. 
430 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

may be taken as evidence that this is not the case. They seem to be quite distinct 

from any American species'yet described. 

Locality and horizon.—San Juan region (stations 2341, 2344, 2345); Rico formation. 

MONOPTERIA Meek and Worthen, 1866. 

MONOPTERIA POLITA White. 

1880. 	Anthracoptera polita. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 166, p1. 42, figs. 5a, b. 


Coal Measures: Major's Mill, Vermilion County, Ill. 


1895. 	Monopteria sp. Keyes, Missouri Geol. Surv., vol. 5, pl. 46, fig. 10. (Date of imprint, 1894. ) 

Upper Coal Measures. 

I have long harbored a belief, to which I now venture to give expression, that 

Anthracoptera polita White properly belongs to the genus Monopteria. The recent 

exposition of Araiadites (= Anthracoptera), which we owe to Dr. Wheelton Hind,a 

makes it highly probable that a shell with the configuration shown by White's figures 

does not belong in Dawson's genus, and in the same characters this fossil strongly 

suggests the genus to which it is now referred. This resemblance and the associations which arise from it have received some expression in geologic literature. I 

have no doubt that the shell figured by Keyes as Monopteria sp. is a representative 

of Anthracoptera polita, and Beede and Rogers practically suggest a generic relationship when describing llionopteria 2 subalata by comparing their form with White's 

species. The former, it may be remarked, seems to be correctly referred to 

but I would suggest that it is possibly founded upon young specimens of 

teria 

spina. 

undeveloped in its younger stages, taking on the alate condition gradually on advancif one may judge by its shape and by the other characters noted by its authors, 

The growth lines in that form indicate that the auricle is comparatively 

M. longiMonoping to maturity. Immature shells of X. longispina as outlined by growth lines on 

larger individuals have exactly the shapes of the types of M. subalata. 

I have identified lifonopteria polita in the Rico formation, where it is associated 

with another shell ,believed to represent X. alata Beede. The relatiopship of these 

species appears to be so close, however, that they should hardly be regarded as more 

than varietally distinct. At the same time I would be unwilling for the present to 

admit that they were specifically the same. 

Locality and horizon.—San Juan region (station 2342); Rico formation. 

MONOPTERIA LONGISPINA COX. ' 

1857. 	Gervilla longispina. Cox, Geol. Surv. Kentucky, vol. 3, p. 568, pl. 8, fig. 6. 

Coal Measures: Providence, Hopkins County, Ky. 

a Mon. on Carbonicola, Anthracomya, and Naiadites; Paleontograph. Soc., 1894-1896. 
DESCRIPTIONS OF SPECIES. 431 

1894. Monoptera longispina. Keyes, Missouri Geol. Surv., vol. 5, p. 114, p1. 43, fig. 1. 

Upper Coal Measures: Kansas City, Mo. 

1900. Limopteria longispina. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 127, pl. 16, fig. 6. 

Upper Coal Measures: Kansas City, Turner, Lawrence, .Kans. 

The form which I have referred to Monopteria longispina has been found, only in 

the Rico formation, and it is represented at station 2341 (Scotch Creek) by two very 

imperfect specimens. The accuracy of the identification is pialified by the character 

of the material. 

The strongly curved umbonal ridge and prolonged posterior portion of this form 

give it a shape much resembling that of M. marian and X. longispina, but the 

retracted anterior margin would prevent its reference to the first-named species. 

Locality and horizon.—San Juan region (station 2341); Rico formation. 

MONOPTERIA ALATA Beede. 

P1. IX, fig. 3. 

1898. Monopteria gibbosa alata. Beede, Kansas Univ. Quart., vol. 7, p. 189, fig. 5. 

1900. Limopteria alata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 130, pl. 5, fig. 5. 

Upper Coal Measures: Turner, Lawrence, Kans. 

Shell small, subpentagonal. Hinge line straight, about once and one-half as 

long as the width below. The body of the shell is marked by two angulations, the 

anterior one almost perpendicular to the hinge line, the other diagonally directed, 

nearly bisecting the angle thus formed. The anterior angulation is near the margin 

of the shell, which falls away very rapidly along this line. The anterior outline, 

therefore, is subrectilinear and is inclined to the hinge line at but little more than a 

right angle. An abrupt curve connects it with the inferior outline, which is also 

subrectilinear and nearly parallel to the hinge line. Where it intersects the diagonal angulation there is another sharp turn to a direction nearly normal to that which 

it had formally been pursuing. Continuing thus for a short distance it begins to 

assume a backward course, and, with a sigmoid curve, joins the superior outline. 

The posterior alation thus formed is strong, but broad and blunt. The surface is 

marked by numerous fine, regular, sublamellose striae, crowded in the upper regions 

of the shell, but becoming spaced peripherally. The description just given is drawn 

up from the only specimen which has thus far been found. The fact that the body 

of the shell in this form is short and nearly erect instead of bending backward into a 

pina 

direction more or less parallel with the hinge line, distinguishes it from 

and M. marian, and also to a less degree from .111: s-ubalata and M. gibbosa, 

.111. longis­­and 

allies it more especially with X. alata and AL polita. I at one time regarded this 

form as representing a new variety subordinate to /IL polita, but now feel that it 

should not be distinguished from IL alata. Although it is true that certain differ-
432 CARBONIFEROTJS FORMATIONS . AND FAUNAS OF COLORADO. 

ences can be pointed out between my specimen and Beede's figure, they hardly seem 

to exceed such as might be reasonably ascribed to difference in age or to individual 

peculiarity. Certainly the expression of the two shells is very similar. On the 

other hand, the relationship between M. polita and 1W. alata is so close, at least in so 

far as it finds expression in external form, that I doubt whether the latter should be 

considered more than a varietal aspect of White's species. 

Locality and horizon.—San Juan region (station 2342).; Rico formation. 

AVICULOPINNA Meek, 1867. 

AVICIJLOPINNA ? PERACUTA Shuma rd. 

Pl. IX, figs. 1, 2. 

1858. Pinna peracuta. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 214. 

Upper Coal Measures: Iowa Point, Nebraska; Kansas. 

11360. Pinna adamsi. McChesney, Desc. New Spec. Pal. Foss., p. 74. 

Coal Measures: Lasalle, Ill. 

1872. Pinna peracuta. Meek, U. S. Geol. Surv. Nebraska, p. 198, pl. 6, figs. lla,b. 

Upper Coal Measures: Bennett's Mill, Wyoming; Nebraska City, Plattsmouth, Rock Bluff, and 

Bellevue, Nebr. 

Coal Measures: Iowa, Nebraska, Kansas, Missouri, and Illinois. 

1875. Pinna peracuta (?). White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 151, p1. 

11, fig. 5a. (Whole volume published in 1877.) 

Carboniferous: Near Relief Spring, Ariz. 

1884. Pinna peracuta. White, Geol. Surv. Indiana, 13th Rept., p. 145, pl. 28, figs. 1, 2. 

Upper, Middle, and Lower Coal Measures: Indiana. 

1886. Pinna peracuta. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol.. 2, pt. 2, p. 272, 

fig. 12; P. 273, fig. 12a. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Pinna peracuta. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 455; p. 444, fig. 

12; p. 454, fig. 12a. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1892. Aviculopinna peracuta. Hyatt, Boston Soc. Nat. Hist., Proc., vol. 25, p. 388. 

1895. Pinna peracuta. Keyes, Missouri Gebl. Surv., vol. 5, p. 116, pl. 45, figs. 2a, b (date of 

imprint, 1894). 

Upper Coal Measures: Kansas City, Mo. 

1899. Pinna peracuta. •Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 579. 

Upper Coal Measures: McAlester quadrangle; Atoka quadrangle. 

1900. Pinna peracuta. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 144, pl. 17, figs. 3, 3b. 

Upper Coal Measures: Kansas City, Lawrence, Topeka, Kans. 

Meek described _Aviculopinna in 1864,a designating for its type Pinna prisca 

Munster= Avicul a pinnceformis Geinitz.b He says. of the genus (loc. cit. p. 212): 

"The typical species is an elongated, thin, nearly or quite equivalve shell, with 

the narrow tapering general form and very long hinge line of Pinna; from 

a Am. Jour. Sci., (2), vol. 37, 1864, p. 212. h Dyas, p. 77;'p1. xiv, figs. 1, 2, 3, and 4. 
DESCRIPTIONS OF SPECIES. 433 

which it differs in not having its beak terminal, but set back some distance from 

the rather obtusely pointed anterior extremity. The beaks, however, are depressed 

and scarcely distinct from the cardinal margin, and the general aspect of the shell 

seems to be intermediate between that of Pinna and Avicula fffooliola." 

At the time of writing Meek was unacquainted with the constitution of the shell 

in Aviculo_pinna, but later a he found that in the case of A. americana, a name 

which he proposed for Avicula pinnVormis Geinitz (non. Geinitz, 1866), the very 

thin substance of the shell had a prismatic structure "like that of other types of the 

Aviculidw." There is, in fact, an inner nacreous layer covering at least part of 

the shell, but this had probably disappeared, through leaching, in the specimens 

examined by Meek. 

It seems generally to have escaped recognition that Hyatt b in 1892 referred 

Pinna peracuta Shumard to Meek's genus _Aviculopinna, and at the same time he 

recorded having observed both the prismatic and the nacreous layers in that species. 

The latter were found to be " not present at the posterior part of one specimen of 

A. peracuta for at least one-half of the entire length, as estimated." He was not, 

however, able to study the distribution of the nacreous layer satisfactorily. 

One who reads Hyatt's brief discussion of the Pinnidze above referred to can 

not but be struck by the closeness which Aviculopinna maintains to the nomenclaturally older genus Pinna. 

The character chiefly relied on by Meek as differentiating Aviculopinna from 

Firma appears to have been the nonterminal position of the beaks of the latter genus 

and the attendant condition of possessing a small anterior lobe. Hyatt remarks 

regarding this feature in Pinna: 

" Unfortunately the apex in all specimens of the Pinnidie is destroyed by attrition. This is doubtless due to the habit of living partly buried in the sand. There 

is therefore no way of proving that the umbones are absolutely terminal, as has been 

generally asserted in all descriptions. The umbones are doubtless more nearly terminal than in Aviculopinna, but it is not safe to go beyond this assertion * * *."C 

The fact that while all recent shells have lost the beak and anterior lobe a 

number of Carboniferous specimens have been found retaining them is significant, 

and would appear either to support Hyatt's statement or else to indicate that 

the habits of these. Paleozoic shells were different from those of their living 

representatives. 

As already noticed, Hyatt found the nacreous layer in Aviculopinna ? peracuta 

to be absent for at least half the length, while in Pinna the fibrous layer alone often 

occupies more than half the entire length.a 

He describes the outer layer of the shell of Pinna as fibrous, while that of 

Aviculopinna is spoken of as prismatic, indicating a distinction which is more 

a Am. Jour. Sci., (2), vol. 44, 1867, p. 282. Ibid., p. 337. 

b Proc. Boston Soc. Nat. Hist., vol. 25, 1892, p. 338. d Ibid., p. 336. 

14364—No. 16 03 
434 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

strongly suggested in his remark that Aviculopinna is " a true Aviculoid, both on 

account of the anterior wing and also because, as stated by Meek, his Aviculopin,na 

americana has the prismatic layer which is characteristic of this group." What 

Meek does say in the passage referred to is that " it has the prismatic shell structure 

of the allied Pinna and Avicula groups." Agreeing with this expression, nearly 

all general treatises describe the shell of both the Aviculidae and the Pinnithe as 

prismatic. 

Between shells referred to Aviculopin,na? peracuta and Aviculo_puma some 

well-marked and constant differences are maintained. Perhaps the most obvious of 

these is the character of the surface ornamentation, Aviculopinna? _peracuta being 

nearly smooth, while the Aviculopinnas are marked by strong, equally distant, 

lamellose projections. The direction of these, and the shape of the posterior 

extremity also seems to constitute a rather constant differentiating character, since 

in Aviculopinna? peracuta the posterior cardinal angle is more or less acute, while 

in Aviculopinna it is sometimes obtuse, giving the outline below a backward swing. 

The apex in Aviculopinna? peracuta has never, I believe, been observed, so that 

,it is not known whether the beaks were terminal or not. The convexity of the 

valves probably does not form a reliable character, since in these shells the 

curvature is often modified by compression. 

It appears that the shell structure of Pinna and Aviculopinna are practically 

identical, the relative extent of the nacreous and prismatic layers not differing 

materially in the fossil and living forms. The nacreous layer in Aviculopinna appears 

to be entire, and this circumstance would ally the genus rather with Atrina than with 

Firma itself. The accepted difference as to the position of the umbones in the two 

genera, on the strength of which chiefly the genus Aviculinna was proposed, can not 

now be proved, and is perhaps not real. On the other hand, the surface ornamentation 

of Aviculopinna is not known in either Pinna or Atrina, and seems to be quite 

characteristic of that group, and to a less degree the straight, inferior margin and 

regular slowly enlarging shape and the linear thickening along the cardinal border. 

It seems to me, therefore, that the uniting of Firma or Atrina and Aviculopirma is not 

to be considered. 

tive in the relative extent of it compared with the prismatic layer. In the gradual 

regular enlargement of the shell, and in possessing a cardinal thickening, this species 

pinna in the undivided condition of its nacreous layer, while there is nothing distincAviculo_pin,nal peracuta seems to agree with Atrina and Aviculois allied to Aviculopinna and differs from Pinna and Atrina. The nearly smooth 

surface and extended cardinal line distinguish it strongly from the Aviculo_pinna 

group, but the unplicated, unstriated surface distinguishes it from the living Pinna 

and 

pinna? peracuta 

Atrina, almost equally with the lamellose striation of 

seems to be more closely allied to. Aviculopinna 

Aviculopinna. Aviculoand Atrina than to 
DESCRIPTIONS OF SPECIES. 435 

Pinna, and I will for the present accept Hyatt's assignment of it to the former genus. 

The persistent differences in shape and surface between Aviculopinna? peracuta and 

the other Aviculopinnw would serve to discriminate two groups under Aviculopinna, 

and they seem to me as constant and important as those upon which Sulcatopinna 

was based. It should be remarked, however, that Pinn,a includes both shells having 

an acute posterior cardinal angle, like Aviculopinna _peracuta, and an obtuse one, like 

the other Aviculopinnw. 

A very imperfect specimen of Aviculopinna? peracuta has been obtained from 

the Hermosa formation in the San Juan region. It has the smooth surface and 

elongate hinge line, with forward sloping growth lines, which characterize that 

species in the Mississippi Valley. The convexity, which may have been reduced by 

flattening, is in this specimen very slight, while the maximum height is 48 mm. 

Another still more fragmentary example has been obtained from the Weber 

formation of the Leadville district. Its surface ornamentation is not retained, so 

that an estimate can not be formed of its original shape. It appears to have been 

a large, long form with subparallel upper and lower margins, and I doubt if it is 

conspecific with the form from the San Juan. The shell, so far as preserved, is 

composed largely, perhaps wholly, of a rather thick prismatic layer. 

Locality and horizon.—San Juan region (station 2205); upper portion of the 

Hermosa formation. Leadville district (station 2257); base of the Weber formation. 

AVICULOPINNA NEBRAS1ENSIS Beede. 

P1. IX, figs. 1, 2. 

1901. Aviculopinna nebrascensis. Beede, Kansas Acad. .Sci., Trans., vol. 17, p. 186, pl. 13, fig. 1-1d. 

Permian: Gage County, Nebr. 

The collections from Colorado occur in a dark, siliceous limestone of the Rico 

formation,, where the species is quite abundant. In size, some of the specimens must 

have been at least 8 inches long—as large as the ordinary Pinna peracuta. The 

growth lines are of course parallel to the lower and posterior margins of the shell, 

and are separated by intervals more or less proportional to its dimensions. They are 

very crowded, somewhat indistinct, and occupy but ft small space along the inferior 

margin, disengage themselves when they assume an upward direction, and end 

abruptly at the hinge line, which they meet at an angle of about 60°. Where paral 

lel to the posterior margin, they are regularly spaced (about 1 mm. apart), and their 

lamellose character is well shown. This appearance is present when the shell has a 

diameter of about 35 mm. The shell substance is seen to be composed of two layers, 

the outer one being distinctly prismatic, the prisms of course normal to the two 

surfaces, and an inner one, which in these specimens is coarsely crystalline. The 

surface of contact between these two structural elements is naturally one of cleavage, 
436 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

and it frequently happens that the outer layer adheres to the matrix and the inner 

to the internal cast of specimens. The direction of the growth lines indicates that 

the posterior outline is that of Aviculopinna, having a backward swing and an 

obtuse posterior cardinal angle. This feature is liable to variation, the posterior outline in some specimens being more nearly a right angle. The one phase is represented by fig. 1 of Pl. IX, and the other by fig. 2. In restoring the outline, which 

has been done in the case of these two figures, it is difficult to estimate from the 

existing parts what shape the missing ones would have had; and consequently I suspect that the backward sweep in fig. 1 is represented as somewhat too great. The 

shell in fig. 2 is largely exfoliated, but one small fragment shows the surface to have 

been marked with spaced lamellae like that represented by fig. 1. 

This shell resembles quite closely the figures given by Beede of the species from 

the Nebraska Permian, which he describes as Aviculopinna nebrasken,8is. Certain 

differences in detail of shape are obvious, but they hardly, it seems to me, validate 

the recognition of my Colorado specimens as belonging to a distinct species. 

Locality and h,orizon.—San Juan region (stations 2341, 2342); Rico formation. 

CHANOMYA Meek, 1864. 

CHJENOMYA LEAVENWORTHENSIS Meek and Hayden. 

1858.. Allorisma f leavenworthensis. Meek and Hayden, Acad. Nat. Sci. Philadelphia, Proc., p. 263. 

Coal Measures: Leavenworth, Kans. 

1864. Chammya leavenworthensis. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, 

p. 43, pl. 2, figs. la-c. 

Coal Measures: Leavenworth, Kans. 

1866. Allorisma leavenworthensis. Geinitz, Carla. and Dyas in Nebraska, p. 15. 

1872. Chanomya leavenworthensis. Meek, U. S. Geol. Surv. Nebraska, p. 216, pl. 2, fig. 9. 

Upper Coal Measures: Rock Bluff, Nebr.; Leavenworth, Kans. 

Coal Measures: Iowa, Missouri, Illinois. 

1895. Chanomya leavenworthensis. Keyes, Missouri Geol. Surv., vol. 5, p. 131. (Date of imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

1900. Chamomya leavenworthensis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 172, pl. 19, figs. 

3-3b. 

Upper Coal Measures: Kansas City, Lawrence, Kans. 

Two specimens from station 2200 (Big Percent Creek, in the San Juan region) 

by their general configuration and widely gaping posterior extremities leave little 

doubt of their generic relationship. They are, however, considerably crushed, and 

there is an element of specific uncertainty in their identification. Similarly tinctured with doubt is the identification of a single small specimen from station 2219 

(south of Marguerite Draw). Another isolated specimen from Sinbads Valley (station 2285), imperfect, though rather well preserved, probably belongs to the same 

species as the above. 
DESCRIPTIONS OF SPECIES. 437 

Locality and horizon.—San Juan region (stations 2200, 2219?); upper portion 

of the Hermosa formation. Dolores River region, Sinbads Valley (station 2285); 

top of the Hermosa formation. 

ALLERISMA King, 1844. 

ALLERISMA TERMINALE Hall. 

Pl. IX, figs. 4, 5, 6. 

1852. Allerisma terminalis. Hall, Stansbury's Exped. to Great Salt Lake, p. 413, pl. 2, figs. 4a, b. 

Carboniferous: Big Blue River. 

1852. Allorisma regularis I Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, pl. 5, fig. 13. 

Carboniferous: Missouri River at Wayne City. 

1858. Allorisma subcuneata. Meek and Hayden, Acad. Nat. Sci. Philadelphia, t:(-; p. 263. 

Upper Coal Measures: Leavenworth, Kans. 

1860. Allorisma ensiformis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 656 

Coal Measures: Clay, Mo. 

1864. Allorisma subcuneata. Meek and Hayden Smithsonian Cont. Knowledge, vol. 14, No. 172, p. , 

pl. 1, figs. 10a, b. 

Coal Measures: Leavenworth, Kans. 

1866. Allorisma subcuneata. Geinitz, Carb. and Dyas in Nebraska, p. 14. 

Upper Coal Measures: Plattsmouth and Wyoming, Nebr. T Kansas. 

1872. Allorisma subcuneata. Meek, U. S. Geol. Surv. Nebraska, p. 221, pl. 2, figs. 10a, b. 

Upper Coal Measures: Rock Bluff, 2i miles southwest of Nebraska City, Wyoming, and Plattsmouth, Nebr.; Leavenworth and Atchison, Kans. 

Upper and Lower Coal Measures: Illinois. 

1875. Allorisma subcuneata (var. ). White, U. S. Geog. Geol. Surv. W. 100th Mc_ , Rent., vol. 4, pd 

155, pl. 12, figs. 7a, b. (Whole report published in 1877.) 

Carboniferous: Near Agua Azul, N. Mex. 

1876. Allorisma subcuneata. White, Powell's Rept. Geol. Uinta Mountains, p. 91. 

Lower Aubrey Group: Confluence of Grand and Green Rivers, Utah. 

1881. Allorisma subcuneata? White, 2d Ann. Rept. Dept. Stat. and Geol. Indiana, p. 518, pl. 8, 

figs. 1, 2. 

Coal Measures: Edwardsport, Knox County, Ind. 

1884. Allorisma subcuneata. White, Geol. Surv. Indiana, 13th Rept., p. 148, pl. 31, figs. 1-3. 

Coal Measures: Indiana. 

1886. Allorisma subcuneata. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 457, 

fig. 10a, p. 444, fig. 10. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Allorisma subcuneata. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p. 272, fig. 10, p. 276, fig. 10a. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Allorisma subcuneata. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 34, pl. 4, figs. 1, 2. 

Coal Measures: Flint Ridge, Ohio. 

1895. Allorisma subcuneatum. Keyes, Missouri Geol. Surv., vol. 5, p. 129, pl. 47, figs. 5a-c. (Date of 

imprint, 1894.) 


Upper Coal Measures: Kansas City, Mo... 

438 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1900. Allorisma subcuneatum. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 169,. pl. 20, figs. 1-lb. 

Upper Coal Measures: Westport (Missouri), Kansas City, Mont Ida ( Anderson County), 

Lawrence, Leconapton, Topeka, Elniont, Grand Summit, Kans. 

This form seems to have appeared in literature under a number of different 

names, several of which have chronological priority over Allerisma subcuneatum. 

Weller is doubtless correct in referring Ph,oladomya elongates Morton to Allerisma, 

and it seems likely that it is the same form which was subsequently described by 

Meek and Hayden. Allerisma terminate Hall also antedates A. subcuneatum,, and 

was, I am confident, proposed, for the same specific type. Meek suggests that 

A. ensiformis Swallow is probably a synonym of A. subcuneatum, and several others 

of Swallow's names may also prove to be. synonyms. A. capax Newberry is 

probably distinct. 

The first described of these forms was A. elongatum, and I believe that this 

name will ultimately supplant the more familiar A. subcuneatum. I have used 

Allerisma terminate for this species, while regarding it as 'highly probable that the 

other names were proposed for it, because this is the only instance in which I have 

been able to convince myself of their identity by direct comparison of material. 

Allerisma terminate was described from the same region as A. subeuneatum and 

seemingly from the same horizon and the same beds. When the type specimen of 

A. terminate is compared with the types of A. subcuneatum and other typical mate 

rial, it becomes clear that it is only a smaller example of the same species, somewhat 

distorted by pressure. The specimen shows compression in an unmistakable manner. 

The direction in which the force was applied is from above, and the effect upon the 

valves have been to lessen their height, exaggerate their convexity, and to thrust 

the umbones forward from their natural position so as almost to overhang the anterior edge of the shell. 

Allerisma terminate is abundant in the Rico formation, especially at station 

2342, some of the specimens attaining a large size. Associated with the normal type 

is a comparatively much shorter form, an example of which is represented by fig. 

6 of Pl. IX. It is possible that this should be regarded as a distinct variety. 

In its proportions it approaches the specimen from New Mexico which White figured 

as Allerisma subcuneatum var. The latter is possibly a little more elongate and is 

more strongly corrugated by concentric ridges, though this difference is likely due to 

preservation. From the Hermosa formatioh a small imperfect specimen has come to 

hand. It is like White's specimen in the particular of its strongly rugose surface, 

but is perhaps a trifle more elongate, and though considerably smaller than fully 

grown A. terminate probably had, when complete, about the same proportions. 

Locality and horizon.—San Juan region (stations 2204, 2342); rare in the upper 

portion of the Hermosa formation, and abundant in the Rico formation. 
DESCRIPTIONS OF SPECIES. 439 

SEDGW ICKIA McCoy, 1844. 

SEDGWICKIA TOPEKENSIS Shurnard? 

1858. Leptodomus topekaensis. Shumard, Acad. Sci.. St. Louis, Trans., vol. 1, p. 208. 

Coal Measures: Missouri River bluffs, a short distance below mouth of Kansas River. 

1864. Sedgwickia topekaensis? Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14,.No. 172, p. 40, 

figs. A, B. 

Coal Measures: Leavenworth City, Kans. 

1891. Sedgwickia topekaensis. White, U. S. Geol. Surv., Bull. No. 77, p. 26, pl. 4, fig. 11. 

Permian: Goodwin Creek, Baylor County, Tex. 

1895. Allorisma topekaensis. Keyes, Missouri Geol. Surv., vol. 5, p. 128. (Date of imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

1900. Sedgwickia topekaensis. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 171, pl. 20, fig. 3. 

Upper Coal Measures: Topeka, Kans. 

Two poorly preserved specimens from the mouth of Marguerite Creek (station 

2345) seem to belong to tlis species. They resemble very closely, as far as their 

characters are shown, the' specimen figured by Meek and Hayden as belonging to 

Shumard's species. 

_Locality and horizon.--San Juan region (station 2345); Rico formation. 

SCffZODUS King, 1844. 

SCHIZODUS CUNEATUS Meek? 

Pl. 9, fig. 10. 

1875. Schizodus cuneatus. Meek, Pal. Ohio, v ol. 2, p. 336, pl. 20, fig. 

Lower Coal Measures: Putnam Hill and Flint Ridge, Ohio. 

1886. Schizodus cuneatus? Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 456, fig. 9a, 

p. 442; fig. 9. 

-Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Schizodus cuneatus? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, p. 

275, fig. 9. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Schizodus cuneatus (?). Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 42, pl. 4, fig. 23. 

Coal Measures: Flint Ridge, Ohio. 

1896. Schizodus cuneatus. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 35. 


Upper Coal Measures: Crawford County, Ark. 


Lower Coal Measures: Conway County, Ark. 


1896. 	Schizodus cuneatus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 245. 

Upper Coal Measures: Crawford County, Ark. 

Lower Coal Measures: Conway County, Ark. 

This species has been found at three localities and seems not to be rare. It is a 

large shell and closely resembles Meek's type in its shape. The latter, however, is 
440 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

said to be "compressed," meaning, it is inferred, not very convex. My Colorado 

specimens, however, are strongly arched and show more modeling about the anterior 

portion than is seen in Meek's figure, the umbones being well defined. These shells 

also resemble Schizodus ovatus, but aside from being very much larger they have the 

umbones less central than that species. 

Locality and horizon.—San Juan region (stations 2340, 2341, 2342); Rico formation. 

SCHIZODUS MEEKANU S Girty. 

1871. Schizodus wheeleri (pars). Meek, U. S. Geol. Surv. Nebraska, p. 209, pl. 10, figs. la, b, c, d (and 

le, if?). 

Upper Coal Measures: Adams and Union counties, Iowa. 

1894. Schizodus wheeleri (pars). Keyes, Missouri Geol. Surv., vol. 5, p. 123, pl. 46, figs. 3a, b. 

Upper Carboniferous (Upper Coal Measures): Kansas City, Mo. 

1899. Schizodus meekanus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 583, pl. 72, figs. 

7a-7c. 

Upper Coal Measures: Atoka quadrangle. 

One large elongate specimen from station 2337, in the San Juan region, agrees 

closely with the types of this species. The identification is made with some confidence. 

Locality and horizon.—San Juan region (station 2337); Rico formation. 

SCHIZODUS PANDATUS l irty ? 

1899. Schizodus pandatus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 583, p1. 72, fig. 5a. 

Upper Coal Measures: McAlester quadrangle. 

In the red calcareous sandstones of the Rico formation, from which collections 

were made at stations 2340, 2346, and 2348, shells belonging to the genus Schizodus 

are extremely abundant. The preservation is unfortunately so poor that I am unable 

to ascertain definitely whether one or a larger number of species are present. 

Some of the more perfect specimens, however, seem to have the shape of Schizodus 

pandatus, and to that species I have referred the whole collection, except a few specimens from station 2340, identified as Schizodus cuneatus. In fact, it may be said of 

the whole representation of Schizodus that the shells are too poorly preserved or too 

fragmentary to permit of wholly satisfactory identification. 

Locality and horizon. —San Juan region (stations 2340, 2345, 2346, 2348); Rico 

formation. 

SCHIZODUS sp. 

At station 2205, on the west side of the Animas Valley, in the San Juan region, 

a single specimen of Schizodus was obtained. Both valves are preserved, but both 

are more or less crushed, and the original shape can only be ascertained by a process 

of estimation. It is one of the suborbicular types with, however, a well-marked 
DESCRIPTIONS OF SPECIES. 441 

posterior truncation. The maximum transverse diameter is only about 15 mm., and 

the shell resembles the type referred by Meek to Schizodus rossicus de Vern. ? a more 

perhaps than any other. Schizodus symmetricus Calvin ° is another similar though 

larger species, and Sch. ajinis Herrick c is also closely related. 

Locality and horizon.—San Juan region (station 2205); upper part of Hermosa 

formation. 

NUCULA Lamarck, 1801. 

NUCULA TENTRICOSA Hall ? 

1858. 	Nucula ventricosa. Hall, Geol. Surv. Iowa,' vol. 1, pt. 2, p. 716, pl. 24, figs. 4, 5a, b. 

Coal Measures. 

1872. 	Nucula ventricosa. Meek, U. S. Geol. Surv. Nebraska, p. 204, pl. 10, figs. 17a—c. 

Upper Coal Measures: Nebraska City and Rock Bluff, Nebr. 

Lower Coal Measures: West Virginia. 

Coal Meaures: Illinois. 

1882. Nucula ventricosa. White, Geol. Surv. Indiana, 11th Rept., p. 371, pl. 42, figs. 9, 10. 

Coal Measures: Sullivan County, Ind. 

1884. Nucula ventricosa. White, Geol. Surv. Indiana, 13th Rept., p. 146, pl. 27, figs. 9, 10. 

Coal Measures: Sullivan County, Ind. 

1888. Nucula ventricosa. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 233. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Nucula ventricosa. Keyes, Missouri Geol. Surv., vol. 5, p. 121, pl. 45, figs. 3a, b. (Date of 

imprint, 1894.) 

Lower Coal Measures: Clinton, Mo. 

Upper Coal Measures: Kansas City and Gentry, Mo. 

1896. Nucula ventricosa. Smith, Leland Stanford Junior Univ. Publ. ; Cont. Biol. Hopkins Seaside Lab., 

No. 9, p. 35. 

Lower Coal Measures: Conway County, Ark. 

1896. Nucula ventricosa. Smith, Am. Phil. Soc., Proc., vol. 35, p. 245. 

Lower Coal Measures: Conway County, Ark. 

1900. Nucula ventricosa. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 150, pl. 22, figs. 9, 9b. 

Upper Coal Measures: Kansas City, Rosedale, Turner, Topeka, Grand Summit. 

Indeterminable generically but probably a Nucula, Schizodus, or an Edmondia, 

this is the only material at present in the collection upon which the identification of 

Nucula ventricosa in the lists of the Leadville monograph a could_ have been based. 

Locality and horizon.—Leadville district (station 2255); Weber formation (?). 

aGeol. Surv. Illinois, Rept., vol. 5, 1873, pl. 26, figs. 17a-e, 18. 

bState Univ. Iowa Lab. Nat. Hist., Bull., vol. 1, p. 176, pl. 2, figs. 3a, b. 

a Sci. Lab. Denison Univ., Bull., vol. 2, 1887, p. 41, pl. 4, figs. 22, 22a. 

dU. S. Geol. Surv., Mon., vol. 12, 1886, p. 70. 
442 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

LEDA Schumacher, 181'T. 

LEDA BELLISTRIATA Stevens? 

1858. Leda bellistriata. Stevens, Am. Jour. Sci., (2), vol. 25, p. 261. 

Coal Measures: Danville, Ill.; Summit, Ohio. 

1858. Nucula (Leda) kazanensis. Swallow, Acad. Sci. St. Louis, Trans., vol. 1, p. 190. Not N. 

kazenensis Verneuil, 1845). 

Upper and Lower Permian: Valley of Cottonwood and near Smoky Hill Fork, Kansas. 

1858. Leda bellistriata. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 717, pl. 29, figs. 6a—d. 

Lower Coal Measures: Illinois. 

1862. Leda bellistriata. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 419. 

Marshall group: Moscow, Mich. 

1865. Leda bellistriata. Winchell, Acad. Nat. Sci. Philadelphia, Proc., p. 128. 

Marshall group: Hillsdale, Mich. 

1866. Nucula kazanensis. Geinitz, Carb. und. Dyas in Nebraska, p. 20, pl. 1, figs. 33, 34. 

1869. Leda bellistriata, Winchell, Safford's Geol. Tennessee, p. 444. 

Shales just above Black Shale: Hickman and Maury counties, Tenn. 

1870. Leda bellistriata? Winchell, Am. Phil. Soc., Proc., vol. 11, p. 256. 

Waverly group: Tennessee. 

1884. Nuculana bellistriata. White, Geol. Surv. Indiana, 13th ,Rept., p. 146, pl. 31, figs. 8, 9. 

Coal Measures: Vermilion, Sullivan, Vanderburg, and Warrick counties, Ind. 

1887. Nuculana bellistriata. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 40, pl. 4, fig. 26. 

Coal Measures: Flint Ridge, Ohio. 

1888. Nuculana bellistriata. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 232. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Nuculana bellistriata. Keyes, Missouri Geol. Surv., vol. 5, p. 122, p1. 45, figs. 4a, b. (Date of 

imprint, 1894.) 

Upper Coal Measures: Gentry and Kansas City, Mo. 

1896. Nuculana aff. bellistriata. Smith, Leland Stanford Junior Univ. Publ.; Cont. to Biol. Hopkins 

Seaside Lab., No. 9, p. 35. 

Upper Coal Measures: Scott County, Ark. 

1896. Nuculana aff. bellistriata. Smith, Am. Phil. Soc., Proc., vol. 35, p. 245. 

Upper Coal Measures: Scott County, Ark. 

1900. Nuculana bellistriata. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 148, pl. 20, figs. 14, 14b. 

Upper Coal Measures: Kansas City, Rosedale, Lawrence, Topeka, Kans. 

Two specimens from station 2219 in the San Juan region belong to the genus 

Nuculana, but as they appear in the shape of internal casts an exact specific identification is impossible. I have referred them to our common Coal Measures species, 

with which their general configuration accords. 

Locality and horizon.—San Juan region (station 2219); upper portion of the 

Hermosa formation. 
DESCRIPTIONS OF SPECIES. 443 

MACRODON Lycett, 1845. 

MACRODON OBSOLETUS Meek. 

1871. Macrodon obsoletus. Meek, Rept. Regents Univ. West Virginia. 

Lower Coal Measures: Monongahela County, W. Va. 

1875. Macrodon obsoletus. Meek, Pal. Ohio, vol. 2, p. 334, pl. 19, fig. 9. 

Coal Measures: Newark, Ohio. 

1886. Macrodon obsoletus. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 456, fig. 19. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Macrodon obsoletus. Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vu.. 2, pt. 2, 

p. 275, fig. 19. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Macrodon obsoletus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 31, pl. 4, fig. 19. 

Coal Measures: Flint Ridge, Ohio. 

1891. Macrodon obsoletus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 249. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Macrodon obsoletus. Keyes, Missouri Geol. Surv., p. 120, p1. 46, fig. 1. (Date of imprint, 1894. ) 

Upper. Coal Measures: Kansas City, Mo. 

1896. Macrodon obsoletus. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside 

Lab., No. 9, .13. 34. 

Upper Coal Measures: Sebastian County, Ark.; Poteau Mountain, Indian Territory. 

1896. Macrodon obsoletus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 244. 

Upper Coal Measures: Sebastian County, Ark.; Poteau Mountain, Indian Territory. 

1900. 	Macrodon obsoletus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 147, pl. 20, fig. 13. 

Upper Coal Measures: Olathe, Turner, Lawrence, Kans. 

This species is represented by three specimens from one locality in the Leadville 

region. The identification is the same as that recorded in the Leadville monograph.a 

Locality and horizon,.—Leadville district (station 2275); upper portion of the 

Weber formation. 

MACRODON TENUISTRIATUS. Meek and Worthen ? 

1866. Arca striata. Geinitz, Carb. and Dyas in Nebraska, p. 20, tab. 1, fig. 32. (Not Mytilites striata. 

Schlath., 1817. ) 

Upper Coal Measures: Nebraska City, Nebr. 

1866. Macrodon tenuistriata. Meek and Worthen, Chicago Acad. Sci., Proc., vol. 1, p. 17. 

Upper Coal Measures: Springfield, Ill. 

1872. 	Macrodon tenuistriata. Meek, U. S. Geol. Surv. Nebraska, p. 207, pl. 10, figs. 20a, b. 

-Upper Coal Measures: Nebraska City, Nebr.; Springfield, Ill.; Iowa. 

Lower Coal Measures: Illinois. 

1873. Macrodon tenuistriatus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 576, pl. 26, 

fig. 4. 

Upper Coal Measures: Springfield, Ill. 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. '70. 
444 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1887. Macrodon tenuistriata. Herrick, .Sei. Lab. Denison Univ., Bull., vol. 2, p. 31. 

Coal Measures: Flint Ridge, Ohio. 

1888. Macrodon (allied to) tenuistriata. Herrick, Sci. Lab. Denison Univ., Bull., vol. 4, pl. 10, fig. 15. 

Waverly group: Cuyahoga Falls, Ohio. 

1895. Macrodon tenuistriatus. Keyes, Missouri Geol. Surv., vol. 5, p. 10. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1896. Macrodon tenuistriatus. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Sehside 

Lab., No. 9, p. 34. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

1896. Macrodon tenuistriatus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 244. 

Upper Coal Measures: Poteau Mountain, Indian Territory. 

This' species is represented by a single poor specimen which seems to have been 

the basis for the citation of this species in the lists of the Leadville monograph.a 

Locality and horizon.—Leadville district (station 2275); upper portion of the 

Weber formation. 

PLEUROPHORUS King, 1844. 

PLEUROPHORUS SUBCOSTATUS Meek and Worthen. 

Pl. IX, figs. 11, 12. 

1865. Pleurophorus subcostatus. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 246. 

Upper Coal Measures: North branch of Saline Creek, Gallatin County, Ill. 

1866. Pleurophorus subcostatus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 347, pl. 27, 

figs. 2, 2a. 

Upper Coal Measures: North branch of Saline Creek, Gallatin County, Ill. 

1887. Pleurophorus subcostatus f Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 35, pl. 4, figs. 16, 16a. 

Coal Measures: Flint Ridge, Ohio. 

1900. Pleurophorus subcostatus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 161, pl. 20, figs. 11-11b. 

Upper Coal Measures: Kansas City, Mo. 

phorus 

of specific discrimination seem to be the best under existing conditions, but they are 

far from satisfactory. The material from each locality is generally scanty, and the 

That part of the material in our collections which belongs to the genus 

has proved most perplexing. The dispositions which I have made in the way 

Pleuropreservation varies both in character and degree of perfection. I have not been able 

to satisfy myself in what measure the many differences which have been noted are 

due to preservation and what to specific differentiation. 

The prevailing form in the Rico formation is closely related to Pl. subcostatus. 

Two examples of this form are shown on Pl. IX, figs. 11 and 12. These specimens, 

however, are smaller than others occurring in the black siliceous limestone of this 

formation, while in the red calcareous sandstones they grow still larger, some individuals attaining a width of 43 mm., agreeing with the smaller forms, meanwhile, 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 70. 
DESCRIPTIONS OF SPECIES. 445 

in shape and other ascertained characters. These shells are remarkable for their 

straight and nearly parallel dorsal and ventral outlines, the latter being sometimes 

slightly concave, the small size of the portion of the shell anterior to the umbones, 

and the truncate posterior. The posterior edge is subrectilinear and inclined to 

the hinge line at an angle of about 60°. This truncated appearance, though not 

possessed by Meek and Worthen's figures, is noted by them as sometimes being a 

character of the species. Internal casts show the long cardinal tooth and the 

large anterior muscular scar characteristic of the genus, and in addition a faint 

posterior scar. 

A small specimen from the mouth of Margueriste Creek (station 2345) has the 

shell partly preserved. It is considerably smaller even than the examples figured, 

but it is otherwise in agreement, save that the umbonal ridge is stronger and the convexity relatively greater. The shell itself is distinctly ribbed. There is a sharp 

ridge, near the hinge line, the superior margin being strongly beveled and nearly 

horizontal when seen from above. Below this ridge there are three others which 

are sharp but not very prominent, the third one being on the diagonal angulation. 

So far as I can make out, these ridges do not extend to the interior of the thick shell. 

In all the characters noted, these shells are closely similar to Pl. subcostatus, but they 

are very much larger. The form from the red sandy bed above referred to, 1 at one 

time identified with Pl. tail, partly on account of their large size, but they differ 

from that species in being higher in proportion to their width and in having the 

posterior outline less oblique to the subparallel superior and inferior margins. In 

their existing preservation it can not be told whether these large shells have the 

radiating ridges which have been observed in the smaller ones, but if so there can be 

little doubt that they are distinct from Pl. tali. 

_Locality and horizon.—San Juan region (stations 2340, 2341, 2342, 2345, 2346); 

Rico formation. 

PLEUROPHORUS ANGULATUS Meek and Worthen? 

1865. Pleurophorus? angulatus. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 247. 

Coal Measures: Wabash Cut-off, near New Harmony, Ind. 

1875. Pleurophorus? angulatus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 6, p. 529, pl. 33, 

fig. 5. 

Upper Coal Measures: Wabash Cut-off, near New Harmony, Ind. 

This form has straight and nearly parallel dorsal and ventral margins. The 

posterior edge is subrectilinear and inclined to the cardinal line at an angle of about 

60°. The posterior inferior angle is rather sharply rounded. The portion of the 

.shell anterior to the umbones occupies about one-sixth of the entire width. The 

umbonal ridge is well marked, but no radiating ribs have been observed. The surface 

is ornamented by fine concentric striae. The anterior muscular scar is strongly 

marked. The width is about 17 mm. and the height about half as much. 
446 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 


In shape this form resembles that identified as Pl. subcostatus,,but it is a less 

elongate shell, the anterior portion is a ,trifie more prominent, and it lacks the 

radiating ribs which cross the upper and posterior half of shells of that species. 

This form seems to be of the type of Pl. 'angulatus, but differs in being much 

larger and proportionately less transverse, in having the anterior end slightly less 

produced, and the anterior muscular scar more deeply marked. 

Locality and horizon.—Grand River region, below mouth of canyon of Eagle 

River (station 2192); base of Weber forTation. 

PLEUROPHORITS OCCIDENTALIS Meek and Hayden? 

1858. Pleurophorus occidentalis. Meek and Hayden, Albany Inst., Trans., vol. 4, p. 80. 

Permian: In Nebraska, on Missouri, opposite north Missouri boundary. 

1859. Pleurophorus occidentalis. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 396. 

White Permian limestone: Guadalupe Mountains. 

1864. Pleurophorus occidentalis. Meek and Hayden, Smithsonian Cont. Knowledge, vol. 14, No. 172, 

p. 35, pl. 1, figs. 11a, b. 

Coal Measures: Nebraska, nearly opposite northern boundary of Missouri. 

1866. Clidophorus pallasi. Geinitz, Carb. und Dyas in Nebraska, p. 23, tab. 2, fig 3, 4. (Not Mytilus 

pallasi de Vern., 1845.) 

Upper Coal Measures: Nebraska City, Nebr., light gray limestone of Wyoming, 7 miles north 

of Nebraska City. 

1866. Clidophorus occidentalis. Geinitz, Carb. und Dyas in Nebraska, p. 23, pl. 2, fig. 6. 

Upper Coal Measures: Stage C. civ, Nebraska City, Nebr. 

1872. Pleurophorus occidentalis? Meek, U. S. Geol. Surv. Nebraska, p. 212, pl. 10, fig. 12. 

Upper Coal Measures: Otoe City, Nebr.; Nebraska City, Nebr.; Grayville, Ill. 

1891. Clidophorus occidentalis. White, U. S. Geol. Surv., Bull. No. 77, p. 27, pl. 4, fig. 3. 

Permian: Goodwin Creek, Baylor County, Tex. 

Of this form but a single not too perfect example has come to hand, and it is 

identified with some doubt. It is small, with a width of about 11 mm. and a height 

somewhat less than half as great. The general shape much resembles the Nebraska 

shell which Meek figures as Pl. occidentalis, and with that species I have provisionally 

identified it. The dorsal and ventral margins are nearly straight and converge somewhat anteriorly. The posterior end is rather evenly rounded. The umbones are so 

much inclined forward that they project nearly as. far as the small anterior portion. 

The curvature is regular, and there is no distinct umbonal ridge. About halfway 

between the cardinal line and a diagonal joining the anterior superior and posterior 

inferior angles there, is a well-marked radial rib, with possibly traces of one or two 

others below (?). The surface is marked by very tine concentric striae. 

The cardinal edge is angulated as in the shell referred to Pl. subcostatus, so that 

a narrow strip of shell along the hinge line is horizontal when the valve is viewed 

from above. 

Probably with this species belongs a very imperfect specimen from the Lead. 
DESCRIPTIONS OF SPECIES. 447 

ville region which was likewise identified as PI. oceidentalis for the Leadville mono 

graph.° In general configuration it closely resembles the specimen previously 

described, but has the surface above the umbonal ridge (if one were present) crossed 

by five or six delicate radial ribs, with two or three others of equal strength below. 

Locality and horizon.—San Juan region (station 2343); Rico formation. Lead 

vine district (station 2275?), upper portion of the Weber formation. 

EDMONDIA de Koninck, 1844. 

EDMONDIA GIBBOSA Geinitz (non Astarte gibbosa McCoy). 

Pl. IX, figs. 7, 8, 9. 

1866. Astarte gibbosa. Geinitz, Carb. and Dyas in Nebraska, p. 16, tab. 1, .figs. 23, 24. 

Upper Coal Measures: In the gray limestone of Plattsmouth, Nebr. 

There are in the collection several specimens representing a form to which that 

described by Geinitz as Astarte gibbosa McCoy, seems to be, among available literature, the nearest related. Characteristic specimens of this form are found in the 

Rico formation at stations 2340 and 2341, and it seems to be represented by several 

young examples at station 2342. The specimens collected at stations 2340 and 2342 

are in the closest agreement, just as are those from the Hermosa formation at stations 

2204 and 2205 which I have identified as E subtruncata. 

The Colorado material is in the ,form of internal casts, upon which a number of 

low concentric folds are all that is left of the surface sculpture, but in shape, convexity, etc., it agrees with some finely preserved specimens from Graham, Young 

County, Tex., which are referred with confidence to the same species. Here the 

shell is seen to be ornamented with prominent lamellose concentric ridges, regularly 

disposed at intervals, with more or less inconspicuous growth lines intervening. 

The shell is rather tumid, suborbicular in shape, with the posterior outline slightly 

flattened, giving it a subtruncate appearance. 

This species differs from Edmondia subtruneata, which it resembles in A general 

way in shape and possibly in surface ornamentation. It is smaller, more gibbous, 

and longer in proportion to its width. 

The fossils from Colorado and Texas correspond closely to Geinitz's figures and 

description, and probably represent the same form with which he was dealing, but it 

is doubtful if the latter was correctly referred by him to McCoy's species. 

This identification should not be confused with Edmondia gibbosa Swallow, which 

is probably quite different. 

Locality and horizon.—San Juan region (stations 2340, 2341, 2342?), Rico 

formation. 

a U. S. Geol, Siirv., Mon., vol. 12; 1886, p. 70. 

• 
448 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

EDMONDIA MORTONENSIS Geinitz ? 

1866. Astarte mortonensis. Geinitz, Carb. and Dyas in Nebraska, p. 17, tab. 1, fig. 26. 

Upper Coal Measures: Nebraska City, Nebr. 

1898. Edmondia mortonensis. Weller, U. S. Geol. Surv., Bull. No. 153, p. 243. 

One specimen from Sinbads Valley (station 2285) is the only example of this 

species known in our Colorado collections. It presents many points of resemblance 

to the shell which Geinitz figures under the name of Astarte mortonensis. It is 

marked by strong, equally spaced lamellzc, whose course is straightened and subrectilinear posteriorly. My shell differs from that figured in being less elongated 

transversely. 

Locality and horizon.—Dolores River region, Sinbads Valley (station 2285); top 

of the Hermosa formation. 

EDMONDIA SUBTRUNCATA Meek. 

1872. Edmondia subtruncata. Meek, U. S. Geol. Surv. Nebraska, p. 215, pl. 2, fig. 7. 

Upper Coal Measures: Rock Bluff, Nebraska; Atchison, Kans. 

Lower Coal Measures: Illinois. 

1895. Edmondia subtruncata. Keyes, Missouri Geol. Surv., vol. 5, p. 127. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1899. Edmondia subtruncata z Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 580. 

Upper Coal Measures: Atoka quadrangle. 

Two specimens have come to hand, one collected between Hermosa Creek and 

Animas Valley (station 2205) and the other on the west side of Animas Valley (station 

2204). They are unfortunately rather crushed, but seem to belong to the species above 

cited. These are large shells with a transverse diameter of at least 43 mm. 

Locality and horizon.—San Juan region (stations 2204, 2205); upper portion of 

the Hermosa formation. 

EDMONDIA ? sp. 

At station 2219, in the San Juan, occurs a rare but very interesting lamellibranch 

shell, which is unlike any that I have met with or seen recorded from our American 

Carboniferous faunas. Unfortunately, the five specimens in our collection are too 

imperfect to permit its generic affinities to be ascertained. It is probably no true 

representative of the genus Edmondia. 

In size this shell is small, having a width of about 12 mm. and a height of 

10 mm. The shape is similar to that of an Edmondia or a Xracula. It is strongly 

gibbous, the eccentric umbones are oblique, produced, and incurved. The general 

shape is transversely elliptical and the outline is curved. There is a strong emargination (of the outline) below the umbones on the side nearer the anterior end. The 

superior margin on the other side, or hinge line, is nearly straight. It begins with 
DESCRIPTIONS OF SPECIES. 449 

the tip of the umbone, and sloping downward 

posterior curvature. The most elevated portion 

by two indistinct diverging lines, which have the 

area the curvature is rapid in its descent upon ei 

The surface is marked by strong, regular, c 

or denticulate over the body of the shell, but 1 

prominence until they become continuous radiati 

markings of which they are elsewhere a subordi 

The ornamentation and configuration of this 

Carboniferous genus with which I am acquainte 

the hinge characters could be ascertained so as 

and it is possible that better preserved material 

modification even of the description which I hay 

_Locality and Itorizon.—San Juan region (s 

Hermosa formation. 

CYPRICARDINIA La 

CYPRICARDINIA CARBON 

1871. Cypricardinia? carbonaria. Meek, Acad. Nat. Sci. P 

Lower Coal Measures: Newark, Ohio. 

1875. Cypricardinia? carbonaria. Meek, Pal. Ohio, vol. 2, 

Lower Coal Measures: Newark, Ohio. 

1887. Cypricardinia (?) carbonaria. Herrick, Sci. Lab. De 

17, 18. 

Coal Measures: Flint Ridge, Ohio. 

1895. Pleurophorus oblongus. Keyes, Missouri Creol. Sur 

imprint 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1900. Cypricardinia? carbonaria. Beede, Univ. Geol. Sury 

Upper Coal Measures: In the Oolite at Rosedale and 

There are a few specimens from station 22 

San Juan which probably belong to Meek's spe 

resemble the. Waverly form Cypricardinkt scitul 

his figures, the specimen represented by fig. 8 

Pleurophorus oblongus is a member of the ge 

representative of the species under discussion. 

identified as Pl. oblongus. 

gradually merges with the strong 

f the shell is central. It is bounded 

'r origin at the umbone. From this 

her side. 

ncentric ridges, which are crenulate 

terally the crenulations increase in 

g ribs, and dominate the concentric 

ate feature. 

shell taken together are unlike any 

. It is to be regretted that none of 

o determinate its generic position, 

ban that before me may lead to the 

thus far been able to draw up. 

ation 2219); upper portion of the 

arck, 1801. 

RIA Meek. 

iladelphia, Proc., p. 163. 

p. 342, pl. 19, figs. 8a, b. 

ison Univ., Bull., vol. 2, p. 35, pl. 4, figs. 

., vol. 5, p. 125, pl. 46, fig. 8. (Date of 

Kansas, Rept., vol. 6, p. 164, pl. 20, fig. 16. 

Turner, Kans. 

9 south of Marguerite Draw in the 

ies cited above. They also closely 

of Herrick. If one can rely upon 

f pl. 46, which Keyes identifies as 

us Cypricardinia and possibly a 

It almost certainly is incorrectly 

_Locality and Itorizon.—San Juan region (station 2219); upper portion of the 

Hermosa formation. 

14364—No. 16 03 29 
450 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

ASTARTELLA Halls 1858. 

ASTARTELLA GURLEYI White. 

1878. Astartella gurleyi. White, Acad. Nat. Sci. Philadelphia, Proc., p. 35. 

Coal Measures: Danville, Ill. 

1880. Astartella gurleyi. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 166, pl. 42, figs. 6a—b. 

Coal Measures: Danville, Ill. 

A single specimen from the Rico formation, found at station 2343, seems to 

belong to Astartella? gurleyi, which it certainly closely resembles in configuration. 

I think it highly probable that if the hinge characters of this species were known, it 

would be found to belong to the genus 	Microdon. 

Locality and horizon.—San Juan region (station 2343); Rico formation. 

SCAPHOPODA. 

DENTALIIDiE. 

Owing, doubtless, to their comparative rarity and unimportance, the Paleozoic 

Scaphopods have been recipient of less investigation than any other group of the 

Mollusca. 

Although, upon the system of sculpture and upon the conformation of the 

tube, recent Dentlia have been divided into a number of subordinate or subgeneric 

groups, these divisions have not, it is believed, been applied to the fossil forms 

occurring in our American Paleozoics. Many of the characters employed in 

distinguishing the recent forms would be difficult to ascertain in the imperfect 

preservation usually seen in fossils, and one whole class of them, the pOsterior 

notches and slits not infrequently characterizing the more recent Dentaliidm, have 

not beep recorded as occurring in their Paleozoic representatives. The system of 

surface ornamentation, therefore, seems to afford the most available basis for 

subdivision, and among the Carboniferous forms two, and perhaps three, different 

types of surface ornamentation can be recognized; a, surface crossed by longitudinal ribs or stri; b, surface crossed by transverse, usually oblique, annulations 

or striae; c, surface smooth or with growth lines only. 

For forms characterized by surface of the first type it seems clear that the 

name Dentalium, sensu stricto, should be employed. For shells having surface 

ornamentation of the second type the name Plagioglypta has recently been proposed. 

I am in doubt as to the propriety of referring shells of the third type to Plagiogtypta; 

still more doubtful of the propriety of withdrawing them under a new name or of 

referring them to one of the genera or groups already established, as, for instance, to 

Lxvidentalium. The distinction between striations and growth lines, if they have 
DESCRIPTIONS OF SPECIES. 451 

the same trend, is not always an easy one to maintain in practice with fossils, 

and when the vicissitudes of preservation are taken into the reckoning it seems that 

to distinguish the third type of surface from the second would be to rob the classification, of much of its utility. Therefore I am at present disposed to refer species 

whose surface is smooth or marked simply by growth lines to Plagioglypta. 

DENTALIUM (sensu stricto) Linnaeus, 1740. 

The species from American Carboniferous rocks which belong here are three 

in number. They are Dentabium aeutisuleatum, Dentalium, missouriense, and 

Dentalium subleve. 

DENTALIUM SUBLAEVE Hall. 

1858. Dentalium obsoletum. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 724, pl. 29, figs. 16, 17, 17a. 

Coal Measures. 

1877. Dentalium sublxve. Hall, Miller's Am. Pal. Foss., p. 244. 

1891. Dentalium sublave. Keyes, Acad. Nat. Sci. Philadelphia, Proc.', p. 252. 

Lower Coal Measures: Des Moines, Iowa. 

Three different localities have furnished each a poor specimen of a Dentalium which 

probably all• belong to the same species. I have identified them with some hesitancy 

with Dentalium sublwve. Hall's brief description leaves the reader in ignorance of 

many characters of prime importance, and his figures yield but little additional to his 

description. The surface represented by the principal figures seems to be crossed 

by a large number of fine, closely arranged, longitudinal striae, but the enlarged ornamentation shown by him consists of sharp, slender ridges, separated by intervals two 

or three times their own width. If the enlargement is veracious, the Colorado form 

eatum, 

marked by numerous rather closely set, not very prominent, ribs, which are separais certainly not 

eter of about 7 millimeter, tapers gradually, and is slightly curved. The surface is 

The shell from Colorado is rather large and massive. It has a maximum diamdescribed not long since by Gurley.a 

Dentalium subkeve, which is then probably the same as D. aeutisulted by shallow grooves of about the same width as the striae. There seem to be 

about 10-15 striae in a space of 5 mm. Rather strong oblique growth lines are 

also visible. 

This species is possibly the same as one which occurs in the Cisco division of the 

Carboniferous, near Graham, Young County, Tex. The two species are very similar, but the Texas form is practically straight, while that from Colorado is slightly 

bent. The Texas form, when mature, becomes large and heavy, attaining a length of 

some 250 or 300 mm., and is the one mentioned below as similar to Dentalium sp. 

a New Carb. Foss., Bull. No. 1, p. 7, 1883. 
452 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Thus it is possible that Dentalium so. and this form referred to D. sublwve may 

prove to be the same. 

Locality and horizon.—San Juan region (stations 2219, 2238); upper portion of 

the Hermosa formation. Crested Butte district (station 2303); Maroon formation. 

DENTALIUM sp. 

At station 2287, in the southern portion of the Silverton quadrangle, occur rather 

plentiful fragments of an organism which, though not altogether problematical, is 

none the less interesting. I have little doubt that it is a Dentalium of an unusually 

large size. The largest fragment is 85 mm. long and not less than 20 mm. in 

diameter. As the shell substance is in places at least 8 mm. thick, the complete 

diameter of this portion of the shell was probably 25 or 30 mm. The fragment 

shows but little taper, and the shell must have been, when entire, of almost unexampled size and massiveness. The central portion, where exposed to view, is 

unchambered, and the shell can not, therefore, be an orthoceratoid, unless the 

fragment represents only the chamber of habitation. The microscopic structure is 

distinctly molluscan and agrees especially with Dentalium. In the Cisco division 

of the Carboniferous, near Graham, Young County, Tex., an equally large Dentalium, 

of a possibly undescribed species, is found. A single incomplete specimen of this 

form measures 200 ram. in length, and other shorter pieces of larger size indicate 

that it must have attained a length of 300 mm. and more. The diameter of these 

large fragments is upward of 30 mm. and the shell is 4 or 5 mm thick. There is 

no doubt about the affinities of the Texas form, whose existence relieves a reference 

to Dentalium of the specimen from Colorado of most of its incredible features. 

Locality and horizon.—San Juan region (station 287); middle portion of the 

Hermosa formation. 

PLAGIOGLYPTA Pilsbry, 1900. 

venusta 

groups are distinguishable, the 

lia known up to the present time. Among these species two, and possiby three 

To 

Unique among our Carboniferous 

Plagioglypta 

group. 

belong, probably, all the other American Carboniferous 

annulistriata 

Dentalia 

group, the 

in the strength of its annular markmeekiana group, and the 

Dentaings stands Meek and Worth6n's species, Plagioglypta annulistriata. It is too 

striae which traverse 

striata 

marked a form to require comment here, and is .the only representative of the 

associated 

character to its surface. With 

group, to which it lends its name. Much finer and less conspicuous are the 

Pl. primaria, Pl. canna, Pl. grandwiva, 

Plagioglypta meekiana, 

Ph. meekiana in the 

yet still distinct enough to give 

meekiana 

and Pl. granvillensis. 

group can probably be 

annuliAs Pl. 
DESCRIPTIONS OF SPECIES. 453 

grandwva and Pl. granvillensis have not been figured at all, nor the surface of. Pl. 

primaria, it is impossible to form a just estimate of this character or of their affinities. 

Pl. granvillensis may belong in the annulistriata group. The two other species 

probably go with Pl. meekiana. I am in some slight uncertainty as to the proper 

location of Pl. canna. If it is marked 13y longitudinal striae, as White's description 

states, it belongs without doubt to Dentalium, but in the type specimen there are no 

indications of such striae which are not so faint and so occasional' that they might not 

be due to chance or to expectant imagination. As the transverse growth lines are 

clearly preserved in one specimen, it would seem that the longitudinal markings also, 

surface, and constitute what may be desirable to separate as a distinct subdivision 

glypta 

and designate the 

if present, would be visible. For this reason I place 

Plagioglypta venusta 

in the meekiana 

venusta 

group. 

and 

group. At the famous Spergen Hill locality occurs in 

Pl. illinoisensis are described as having a smooth 

Dentalium canna with Plagiosome abundance a dentalioid shell, probably Pl. venusta, whose surface appears to 

be entirely without markings. Whether its characters have been obscured or 

destroyed by attrition or fossilization I find myself at present unable to decide. 

The surface of Pl. annulistriata is in strong contrast to that of Pl. meekiana, 

although the difference is one of degree merely. Intermediate between them in this 

particular stands Pl. undulata, the type of Plagioglypta, and Dr. Pilsbry, whom I 

have had the honor to consult in this matter, advises me that, according to its 

original extension, both Carboniferous forms can be admitted into his genus. 

It still remains a debatable question what should be done with the venusta type. 

It certainly does not appear to have the characters of Plagioglypta, much less of 

Dentalium, and if what is recorded of this species and of Pl. illinoisensis is \Teri • 

table, neither can properly be admitted into either of these genera. It is doubtful 

if Lxvidentalium ranges back into Paleozoic time, and it therefore seems inadvisable 

to place them with that genus. Perhaps the course open to the least objection is to 

refer them as a separate and doubtful subdivision to Plagioglypta pending the 

absence of determinative data. 

GASTEROPODA. 

EUCONISPIRA Ulrich, 1897. 


EIJCONISPIRA TAGGARTI Meek. 


P1. X, figs. 9, 9a. 


1874. Pleurotomaria taggarti. Meek, U. S. Geol. Geog. Surv. Tern, [Seventh] Ann. Rept., for 1873, 


p. 231. 

Carboniferous: Canyon of Four-Mile Creek, Colorado. 

1880. Pleurotomaria taggerti. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 

p. 140, pl. 34, figs. la, b. 


Carboniferous: Near Horseshoe Mountain, South Park, Colo. 

454 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Of this species our collections from Colorado still contain only the specimen for 

which the name Pleurotomaria taggarti was originally proposed. It scarcely seems 

necessary at this place to repeat Meek's excellent description, but the figures 

published by White are shown on Pl. X. 

Locality and horizon.--Leadville distiict (station 2281); base of the Weber 

formation. 

EUCONISPIRA BICARINATA McChesney. 

1860. Pleurotomaria bicarinata. McChesney, base. New Spec. Pal. Foss., p. 90. (Not P. bicarina,"a 

Sowerby, 1818.) 

Coal Measures: Lasalle, Ill. 

1860. Pleurotomaria turbiniformis. Meek and Worthen, Acad. Nat. Sci. Philad.4phia, Proc., p. 461. 

Upper Coal Measures: Lasalle, Ill. 

1866. Pleurotomaria turbiniformis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 359, 

pl. 28, figs. 8a—c. 

Upper Coal Measures: Lasalle, Ill. 

1884. Pleurotomaria turbiniformis. White, Geol. Surv. Indiana, 13th Rept., p. 160, pl. 32, figs. 7, 8. 

Upper Coal Measures: Lasalle and Paris, Ill.; Vigo County, Ind. 

1894. Pleurotomaria turbiniformis. Keyes, Missouri Geol. Surv., vol. 5, p. 135, pl. 48, figs. 6a, b. 

Upper Coal Measures: Kansas City, Mo. 

1897. Euconispira turbiniformis. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt 2, 

pp. 949,956, figs. d, e, on p. 1080. 

Upper Carboniferous: Kansas City, Mo. 

Of this species we have a single specimen from the Hermosa formation whicti is 

not very perfect but shows sufficient characters to make possible a specific determination of considerable accuracy. After a comparison with authentic specimens of 

Pleurotomaria turbiniformie from the original locality, the conclusion has been 

reached that the two forms are with but little doubt identical. 

Meek noted that his name Pl. turbiniformis had been proposed for the same species 

as Pl. bicctrinata McChesney, which antedates it by several months, but his reason 

for retaining Pt. turbiniformis, that the name Pl. bicarinata is thrice preoccupied, 

is invalidated by the removal of that species to another genus. 

Locality and horizon.—San Juan region (station 2196b); Hermosa formation. 

EUCONISPIRA sp. a. 

This form in size and configuration• very closely resembles Eu. biearinata, but 

several differences can be pointed out which indicate that it should be considered a 

distinct species. The single specimen representing it was obtained from the red 

sandy beds of the Rico formation. The surface ornamentation is almost entirely 

obscured, but there are in places certain markings, which may be accidental, that 

might be interpreted as indicating that the surface was traversed by a small num-
D SCRIPTIONS OF SPECIES. 455 

ber of rather coarse revolvi g ridges. The underside of the shell, moreover, is 

somewhat strongly concave, w ile that of Eu. bicarinata is gene ally convex 

Locality and horizon.—Sa Juan region (station 2340); Rico formation. 

EITCONISPIRA sp. b. 

This species is derived fr na the same locality and horizon a. the preceding. It 

attains a rather large size, an is distinguished from the other s embers of the genus 

noted here by the lowness of i spire and the rapidity of its exp. nsion. The largest 

speeimen seen has a diamete of 45 mm. One whose diarne er is 28 ram. has a 

height of probably not over 15 mm. The base is concave. The s i rface ornamentation 

is entirely obscured. 

Locality and horizon.--S n Juan region (station 2340); Ric• formation. 

PHA EROTREMA. Fischer, 1885. 

PHANEROTREMA cf. GRAYVILLENSE Norwood and P rotten. 

1855. Pleurotomaria grayvillensis. orwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 

3, p. 75, pl. 9, figs. 7a, b. 

Coal Measures: Grayville, Ill.; near mouth of Rush Creek, Posey ounty, Ind.; Shawneetown and Galatia, Ill. 

1866. Pleurotomaria grayvillensis. Oeinitz, Carb. and Dyas in Nebraska, p. 9 tab. 1, fig. 9. 

Upper Coal Measures: Nebraska City, Nebr. 

1872. 	Pleurotomaria grayvillensis. Meek, U. S. Geol. Surv. Nebraska, p. 233, pl. 11,. fig. 9. 

Upper Coal Measures: Nebraska City, Nebr.; Illinois, Kentucky, Io a, Missouri, Kansas. 

Lower Coal Measures: Illinois and West Virginia. 

1879. Pleurotomaria grarillensis. White, U. S. Geol. Geog. Surv. Terr., Bul ., vol. 5, p. 219. 

Carboniferous: Wild Band Pockets, northern Arizona, 15 miles south f om Pipe Spring. 

1880. Pleurotomaria grayvillensis. White, U. S. Geol. Geog. Surv. Terr., Tw lfth Ann. Rept., for 1878,_ 

pt. 1, p. 140, pl. 34, fig. 5a. 

Upper Carboniferous: Wild Band Pockets, northern Arizona, 15 miles south from Pipe Spring. 

1888. Pleurotomaria grayvillensis. Keyes, Acad. Nat. Sci. Philadelphia, Pro s ., p. 238. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Pleurotomaria grayvillensis. Keyes, Missouri Geol. Surv., vol. 5, p. 141 (date of imprint 1894). 

Lower Coal. Measures: Kansas City and Pleasant Hill, Mo. 

1897. Ph,anerotrema grayvillense. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt. 2, 

p. 952. 

This species is represented by two small shells resenablinl Phanerotrema grayvillense, but they are too poorly preserved to be determined ith certainty. They 

form the basis for the appearance of Pleurotomaria grayvillemis in the faunal list of 

the Leadville monograph.a 

Locality and horizon.--Leadville district (station 2275); upper portion of the 

Weber formation. 

a U. S. Geol. Sure., Mon., vol. 12, 1886, p. 70. 
456 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

PHANEROTREMA sp. 

Near Glenwood Springs, at station 2193, a small collection was obtained which 

indicates the presence at that place of an interesting and extensive fauna. The 

fossils are chiefly gastropods and are of very minute size. As I have indicated, the 

fauna, if carefully collected, would probably prove an extensive one. It would also 

be difficult to study. As the entire shell is very small, the surface ornamentation is 

almost microscopic, and, unless well preserved, can not satisfactorily be made out. 

Fortunately the preservation at this locality is generally good. I have discriminated 

about six species in the material collected and suspect that there may be several 

others. Without doubt these represent only a small proportion of the entire fauna. 

I have found it sufficiently difficult to arrive at approximate determinations of 

these species, to believe that many of them are new. No new names have been proposed, however, because it seems that a miniature fauna, such as this is, should be 

studied only from especially abundant and especially perfect material. 

One of the most abundant types among the gasteropods is a little Phanerotrema 

which is related to Ph. grayvilleme and Ph. constrietum. Many species of this group 

have been considered, but none with which this can be satisfactorily identified. 

The height is between 3 and 4 mm., and the diameter nearly the same. The 

height of the spire is 2 mm., or a little over. There are about 4 volutions. The 

lower portion of the outer whorl is marked by a number of comparatively large 

striae, which also transgress upon the flattened periphery. This striated portion is 

succeeded by a broad, flat slitband whose direction is nearly vertical. Above the 

slitband is a carina which constitutes the most prominent portion of the entire 

peritreme. It is probably somewhat nodose. The upper portion of the peritreme 

declines from the vertical by an angle of about 45°. It is slightly concave and 

appears to be without ornamentation. Just below the suture is a row of small nodes 

or possibly a nodose revolving ridge. Most of the strive marking the lower portion 

of the peritreme are of course covered over by the succeeding volution, but a few 

of the upper ones are left exposed. 

Locality.—Grand River region, Glenwood Springs (station 2193). 

WORTHENIA de Koninck, 1883. 

WORTHENIA TABULATA Conrad? 

1835. Turbo tabulata. Conrad, Geol. Soc. Pennsylvania, Trans., vol. 1, pt. 2, p. 267, pl. 12, fig. 1. 

1842. Pleurotomaria tabulata. Conrad, Acad., Nat. Sci. Philadelphia, Jour., (1), vol. 8, p. 272. 

Carboniferous: Inclined plane of the Allegheny Mountains. 

1858. Pleurotomaria tabulata. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 721, pl. 29, figs. 12a, b. 

, Coal Measures: Pennsylvania, Indiana, and Illinois. 

1881. Pleurotomaria tabulata. White; Dept. Stat. and. Geol. Indiana, 2d Ann. Rept., p. 519, pl. 18, figs. 

4, 5. 

Coal Measures: Rush Creek, Posey County, Ind. 
DESCRIPTIONS OF SPECIES. 45 7 

1884. Pleurotomaria tabulata. White, Geol. Surv. Indiana, 13th Rept., p. 160, pl. 32, figs. 4, 5. 

Upper Coal Measures: Rush Creek, Posey County; Wagon-defeat Creek, Sullivan County, and 

Warrick County, Ind. 

1895. Pleurotomaria tabulata. Keyes, Missouri Geol. Surv., vol. 5, p. 142. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1897. Worthenia tabulata. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt. 2, pp. 

949, 950, 953. 

This type is represented by a single •specimen from Sinbads Valley. It is 

reduced nearly to the condition of an internal cast, but probably can be referred to 

Conrad's species. 

Locality and horizon.—Dolores River region, Sinbads Valley (station 2285); top 

of the Hermosa formation. 

WORTHENIA ? LASALLENSIS Worthen? 

1890. Murchisonia lasallensis. Worthen, Geol. Surv. Illinois, Rept., vol. 8, p. 141, pl. 25, figs. 7, 7a. 

Upper Coal Measures: Lasalle, Ill. 

In using for this form the name of Worthen's species, I desire to indicate a 

resemblance rather than to express an identification, for the single specimen which 

has so far come to hand is too poor to permit a determination of that degree of 

accuracy. The surface ornamentation is entirely obscured, but the shape and size 

are those of Murchisonia lasallensis. It might almost as well be referred to 

Murchisonia Cerebra White, but it is a smaller form with deeper indented sutures. 

This species has been placed with the genus Worthenia because of its configuration 

alone. It is certainly not a Murchisonia, and while it departs somewhat widely from 

the type represented by the species tabulata and subscalaris, the range is no greater 

than that shown by the related genus Lophos_pira. As already intimated, I have not 

been able to examine representatives of this species in which the essential generic 

characters are shown. 

Locality and horizon.—San Juan region (station 2217); middle portion of the 

Hermosa formation. 

WORTHENIA ? MARCOUIANA Geinitz ? 

1866. Murchisonia marcouiana. Geinitz, Carb. and Dyas in Nebraska, p. 11, tab. 1, fig. 16. 

-Upper Coal Measures: Rock Bluff, Nebr. 

1899. Murchisonia marcouiana. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 588. 

Upper Coal Measures: McAlester quadrangle, Indian Territory. 

The form which I have referred to Worthenia marcouiana seems to be abundant 

in the Rico formation at stations 2340 and 2345. The condition of preservation of 

my material does not favor an identification of the greatest accuracy. 

At station 2275, in the upper part of the Weber grits in the Tenmile district, 

occurs a specimen which probably answers to Murchisonia sp. in the list of the 

Leadville monograph." It seems to belong to this species. 

aU. S. Geol. Surv., Mon., vol. 12, p. 70. 
458 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

I have placed lfurchisonia marcouiana in the genus Worthenia with some hesitation. It clearly belongs to the group of Pleurotomaria, and is more nearly related, 

to Worthenia than it is to Ilfurchisonia. 

Locality and horizon.—San Juan region (stations 2340, 2345); Rico formation. 

Leadville district (station 2275); upper portion of the Weber formation. 

WORTHENIA ? sp. a. 

This form was identified as Ilturch,isonia sp. in the list of the Leadville monograph,a and it is too poorly preserved to be determined with certainty. Even its 

generic position is a matter of doubt. It is one of those forms with a lofty spire 

and very gradual taper. Its dimensions must *have been 24 mm. in height, with a 

proximal diameter of about 8 mm. The peritreme appears to have been carinated, 

and I judge that its specific relations are near the two species just discussed. 

Locality and horizon.—Leadville district (station 2275); upper portion of the 

Weber formation. 

WORTHENIA ? sp. b. 

This form is allied to the species which Geinitz b described under the name of 

Jifurchisonia nebraskensis, but it is certainly specifically distinct. It is much smaller, 

as will appear from the fact that the entire height is only about 2 mm. The width 

is nearly half as much, and there are 6 volutions. It has therefore proportionally 

a somewhat lower spire than Al. nebraskensis, and the sutures, are less oblique 

to the axis. The shape of the peritreme- is strongly arched but not subangular. 

The surface of the final volution is crossed by four thin elevated ridges, which are 

about equal distances apart. The upper one is near the suture, but the others are 

disposed very much as in IL nebraskensis. The lower side of the peritreme is crossed 

by several revolving ridges, which are less prominent than the ones above. While 

there are four of the latter on the final volution, there are but three on that which 

precedes it. 

I am by no means sure that this form possessed a slit band and its position with 

the Pleurotomariidm is therefore uncertain. If this structure is really present it 

probably occurs on the periphery between the two lower strong revolving ridges. 

Even if it belongs to Pleurotomaria, however, I am doubtful whether it should be 

referred to the genus Worthenia. 

Locality.—Grand River region, Glenwood Springs (station 2193). 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 70. 

b carb. and Dyas in Nebraska, 1866, p. 12, pl. 1, fig. 17 
DESCRIPTIONS OF SPECIES. 459 

PLEIJROTOMARIA Defrance, 1824. 

PLELIROTOMARIA ? Cf. CARBONARIA Norwood and Pratten. 

1855. Pleurotomaria carbonaria. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 

3, p. 75, p1. 9, fig. 8. 

Coal Measures: Rockcreek, Williamson County, Ill. 

1888. Pleurotomaria carbonaria. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 239. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Pleurotomaria carbonaria. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 253. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Pleurotomaria harii. Miller, Geol. Surv. Indiana, Adv. Sheets, 17th Rept., p. 83, pl. 14, figs. 3, 4. 

Upper Coal Measures: Kansas City, Mo. 

1892. Pleurotomaria harii. Miller, Geol. Surv. Indiana, 17th Rept., p. 693, pl. 14, figs. 3, 4. 

Upper Coal Measures: Kansas City, Mo. 

1895. Pleurotomaria carbonaria. Keyes, Missouri Geol. Surv., vol. 5, p. 138. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1896. Pleurotomaria harii. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 40. 

Lower Coal Measures: Conway County, Ark. 

1896. Pleurotomaria harii. Smith, Am. Phil. Soc., Proc., vol. 35, p. 250. 

Lower Coal Measures: Conway County, Ark. 

This shell, of which we have one specimen only, is so small that it seems almost 

grotesque to compare it with the robust species mentioned above. It has, nevertheless, much the proportions and markings of Pl. P carbonaria and Pl. Pbeckwithiana. 

It is a somewhat more depressed type than either of those mentioned, but in the 

relative coarseness of its stria it can be compared with the former species rather 

than with the latter. The height is about 0.5 mm. and the diameter possibly a trifle 

greater. There are three volutions. The peritreme is highly and regularly convex 

and marked by a number of subequal revolving striae which are somewhat finer and 

more crowded on the lower than on the upper portion of the peritreme. The slit 

band appears to be situated about medially. 

Locality.—Grand River region, Glenwood Springs (station 2193). 

ACLISINA de Koninck, 1881. 

ACLISINA STEVENSIANA Meek and Worthen? 

1866. Turriiella, Q stevensana. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 382, pl. 27, figs. 

8-8a. 

Upper Coal Measures: North Branch Saline Creek, Gallatin County, Ill. 

1895. Aclisina stevensana. Keyes, Missouri Geol. Surv., vol. 5, p. 202. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo. 

One of the species occurring in the gasteropod fauna found near Glenwood 

Springs is an elongate, turreted shell with three or four revolving ,striae, which 
460 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

closely resembles Aclisina stevensiana Meek and Worthen. We have only a few not 

very perfect examples of this species and all of its characters can not be made out. 

The height of one specimen is about 2 mm., and the greatest diameter about 0.75 

mm. This specimen has 6 whorls. 

Locality.—Grand River region, Glenwood Springs (station 2193.) 

LOXONEMA Phillips, 1841. 

LOXONEMA. PARVUM COX? 

1857. Chimnitzia parva. Cox, Geol. Surv. Kentucky, vol. 3,. p. 567, p1. 8, figs. 3, 3a 

Coal Measures: Daviess County, Ky. 

1898. Loxonema parvum. Weller, U. S. Geol. Surv., Bull. No. 153, p. 335. 

This is a pretty little species, but we have of it only a single specimen. The 

length is somewhat over 2 mm. and the greatest diameter about 1 mm. The volutions are 6 in number, the rate of expansion is rather rapid, and the final volution at 

the aperture makes up about one third the full length of the shell. The ornamentation consists of moderately strong longitudinal costs, of which there are about 11 on 

one side of the volution next the last. The aperture is rather large. 

This shell in size, shape, and ornamentation is very similar to Cox's species, 

Lox9nema parvum. It differs in having the sutures between the volutions more 

nearly horizontal, and in the fact that the volutions themselves instead of being 

convex are much flattened. 

Locality and horizon.—Grand River region, Glenwood Springs (station 2193). 

LOXONEMA PLICATUM Whitfield. 

1882. Loxonema plicatum. Whitfield, New York Acad. Sci., Ann., vol. 2, p. 231. 

Coal Measures: Carbon Hill, Hocking County, Ohio. 

1891. Loxonema plicatum. Whitfield, NeW York Acad. Sci., Ann., vol. 5, p. 601, pl. 15, figs. 14, 15. 

Coal Measures: Carbon Hill, Hocking County, Ohio. 

1895. Loxonema plicatum. Whitfield, Geol. Surv. Ohio, Rept., vol. 7, p. 486, p1..11, figs. 14, 15. 

Coal Measures: Hocking County, Ohio. 

The two not very perfect specimens which I have referred to Loxonerna plicatum 

are certainly nearly related to Whitfield's species, even if not specifically identical 

with it, as is believed probable. They much resemble in shape the form which I 

identified as Loxonema peorien8e, but even as internal casts preserve traces of the 

characteristically notched or rugose surface ornamentation. 

Locality and horizon.—San Juan region (stations 2342, 2344); Rico formation. 

LOXONEMA ? PEORIENSE Worthen. 

Pl. X, fig. 8. 

1884. Loxonema peoriense. Worthen, Illinois State Mus. Nat. Hist., Bull. No. 2, p. 7. 

Coal Measures: Peoria County, Ill. 

1890. Loxonema peoriense. Worthen, Geol. Surv. Illinois, Rept., vol. 8, p. 139, pl. 23, figs. 10, 10b. 

Coal Measures: Peoria County, Ill. 
DESCRIPTIONS OF S ECIES. 461 

This form has been found at two localities the Rico formation, stations 2345 

and 2342, at the latter of which it is fairly co on. The Colorado specimens are 

are elsewhere, possibly with 

closely similar to Worthen's species and are pro 

ense is 

American Carboniferous representatives of 

Locality and horizon. —San 

so different in the character of its surfa 

Streptacis 

Juan region (st 

Meek. 

Lox 

e ornamentation from at least our 

ably identical. 

Lions 2342, 2345); Rico formation. 

ema as to suggest that its affinities 

Loxonema peori­

• LOXONEMA 

The only specimen representing this species is unfortunately very imperfect. 

It seems to be a rare form, more nearly relate to Loxonema halli Norwood and 

Pratten than to any with which I am acquainted. 

Locality and h,orizon.—Leadville district ( ation 2275); upper portion of the 

Weber formation. 

PLATYCERAS Con d, 1840. 

PLATYCERAS PARVUM Swallow. 

Pl. X, figs. 1, la, 2 2a. 

1858. 	Capulus parvus. Swallow, Acad. Sci., St. Louis, Tra s., vol. 1, p. 205. 

Coal Measures: Valley of the Verdigris, Kans. 

1872. 	Platyceras nebrascensis. Meek, U. S. Geol. Surv.. Ne raska, p. 227, pl. 4, figs. 15a, b. 

Upper Coal Measures: Three-fourths of a mile west f Nebraska City Landing, Nebr. 

Middle Coal Measures: Illinois. 

1875. Platyceras nebrascense. White, U. S. Geog. Geol. Su v. W. 100th Mer., Rept., vol. 4, p. 159, pl. 

12, figs. 5a—d (Whole volume published in 1877.) 

Carboniferous: Near, Santa Fe, N. Mex. 

1884. Platyceras nebrascene. White, Geol. Surv. Indiana, 1 th Rept., p. 159, p1. 32, figs: 15, 16. 

Coal Measures: Eugene, Edwardsport, and New Ha ony, Ind. 

1890. Capulus parvus. Keyes, Am. Geol., vol. 6, p. 9. 

1890. Capulus parvus. Keyes, Acad. Nat. Sci. Philadelphi , Proc., p. 177, pl. 2, figs. 14a—c. 

Upper Coal Measures: Indiana; Iowa; Nebraska; K nsas; and New Mexico. 

1895. Capulus parvus. Keyes, Missouri Geol. Surv., vol. 5, p. 180, pl. 54, figs. 5a, b. (Date of imprint, 

1894.) 

Upper Coal Measures: Kansas City, Mo. 

Only two specimens in the collections were ound representing this species, but 

one of them is the largest individual I have eves seen belonging to it. It measures 

no less than 35 mm. across the base, and its long st diameter is 47 mm. 

Keyes. places Platyceras n,ebraskense Meek i the synonymy of Capulus parvus 

Swallow. Swallow's description seems to appl to Platyceras n,ebraskense, and the 

figures given by Keyes of a specimen supposed o be the type of Pl. parvum certainly look as if the original might have been young example of Meek's species. 

On the other hand, we have the statement by Me k, " This species resembles more or 
462 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

less nearly several of th9se described from different horizons in the Western States, 

but after a critical comparison I have been unable to identify it with any of them.". 

It is, therefore, with hesitation that I adopt the synonymy suggested by Keyes. My 

reasons for using the generic term Platyceras instead of Octpulus will be found stated 

on a previous page of this report. 

Locality and horizon.—San Juan region (stations 2218, 2279); lower and upper 

portions of the Hermosa formation. 

STROPHOSTYLUS Hall, 1859. 

STROPHOSTYLITS cf. NANUS Meek and Worthen 

1860. 	Platyostoma nano. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 463. 

Upper Coal Measures: Springfield, Ill. 

1861. Naticopsis nana. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 148. 

1866. Naticopsis nana. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 365, pl. 31, figs. 4a, b. 

Upper Coal Measures: Springfield, Ill. 

1875. Naticopsis nana. White, U. S. Geog. Geol. Surv. W. 100th Mer. Rept., vol. 4, p. 159, pl. 12, figs. 

4a, b. (Whole volume published in 1877.) 

Carboniferous: Camp Cottonwood, near Spring Mountain, Lincoln County, Nev. 

1884. Naticopsis nana. White, Geol. Surv. Indiana, 13th Rept., p. 162, pl. 36; figs. 6, 7. 

Middle and Upper Coal Measures: Indiana. 

1888. Naticopsis nana. Herrick, Sci. Lab. Denison Univ., Bull., vol. 4, pl. 11, fig. 8. 

Coal Measures: Fultonham, Ohio. 

1891. Naticopsis nana. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 257. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Strophostylus nana. Keyes, Missouri Geol. Surv., vol. 5, p. 196. (Date of imprint, 1894. ) 

• Upper Coal Measures: Clinton and Kansas City, Mo. 

1896. Naticopsis nana. Smith, Leland Stanford Junior Univ. Publ.; Cont. Biol. Hopkins Seaside Lab., 

No. 9, p. 40. 

Upper Coal Measures: Sebastian County, Ark. 

1896. 	Naticopsis nana. Smith, Am. Phil. Soc., Proc., vol. 35, p. 250. 

Upper Coal Measures: Sebastian County, Ark. 

This little form probably finds its closest American ally in Strophostylus nanus 

Meek and Worthen, which, though itself a small species, is fairly gigantic when 

compared with its Colorado relative. The latter rarely exceeds 2 mm. in height, 

but in configuration it' greatly resembles the larger shell. The spire is depressed. 

There are three' volutions, increasing rapidly in size, but the final one is probably 

not as inflated as in typical S. nanus. 

Locality and horizon.—Grand River region, Glenwood Springs (station 2193). 
DESCRIPTIONS OF SPECIES. 463 

STROPHOSTYLUS SUBOVATUS Worthen 

Pl. X, figs. 3, 3a. 

1873. Naticopsis subovatus. Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 595, pl. 28, fig. 9. 

Upper. Coal Measures: Lasalle, Ill. 

1898. Strophostylus subovatus. Weller, U. S. Geol. Surv., Bull. No. 153, p. 615. 

This identification is based upon a single specimen, which is distinguished from 

St. remex by its lower spire and more rapidly enlarging yolution.s. It is much 

smaller than fully grown St. subovatus, but resembles it in shape closer than any 

other form with which I am acquainted. 

Locality and horizon.—San Juafi region (station 2217 ?); middle portion of .the 

Hermosa formation. 

STROPHOSTYLUS REMEX White. 

Pl. X, figs. 4, 4a, 5 to 5b. 

1876. Naticopsis remex. White, Powell's Rept. Geol. Uinta Mountains, p. 109. 

Lower Aubrey group: Confluence of Grand and Green rivers, Utah. 

1880. Naticopsis remex. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, p. 

139, pl. 34, fig. 6a. 

Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

1883. Naticopsis remex. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, p. 

391, pl. 34, fig. 6a. 

Middle Carboniferous: Confluence of Grand and Green rivers, Utah. 

1891. Naticopsis remex. White, U. S. Geol. Surv., Bull. No. 77, p. 24, pl. 3, fig. 10. 

Permian: Military Crossing and Goodwin Creek, Baylor County, Tex. 

1895. Strophostylus remex. Keyes, Missouri Geol. Surv., vol. 5, p. 197, pl. 55, figs. 7a, b. Date of 

imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

This form occurs in the Rico formation at station 2345 and is abundant at station 

2340. An imperfect specimen from the Leadville region (station 2273) seems to 

belong to this species. Some of the smaller individuals approach St. nanus. 

Locality and horizon.—San Juan region (stations 2340, 2345); Rico formation. 

Leadville district (station 2273); Robinson limestone. 

NATICOPSIS McCoy, 1844. 

NATICOPSIS ALTONENSIS McChesney. 

1865. Natica altonensis. McChesney, Illustrations New Spec. Foss., pl. 2, figs. 14a, b. 

Coal Measures: Alton, Ill. 

1868. Naticopsis altonensis. McChesney, Chicago Acad. Sci., Trans., vol. 1, p. 50, pl. 2, figs. 1 4a—e . 

Coal Measures: Alton, Ill. 
464 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1873. Naticopsis altonensis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 595, pl. 28, figs. 

11a, 11b. (Naticopsis altonensis? on description of plates.) 

Coal Measures: Macoupin County, Ill. 

1881. Naticopsis altonensis. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., Appendix, p. xxxv, pl. 3, fig. 6a. 

Carboniferous: Near Taos, N. Mex. 

Only four specimens have been referred to this species, and they are, unfortunately, in an imperfect condition. One of them, from station 2223, in the Rico 

quadrangle, closely resembles the elongate shell upon which the original description 

was based. It is, however, considerably larger, having a length of not less than 55 

mm., and possibly belongs to the variety which Meek and Worthen figured under 

the varietal name of giganteus.a Another shell, from station 2340 in the same 

area, is more compact and has the shape depicted by Meek and Worthen's figures 

11a and 11b, which they identify as N. altonensis? It is about the size of the 

specimen represented by these figures and is smaller than the example preiriously 

mentioned. 

Two shells from Sinbads Valley, whose mutual relations are not quite certain, 

have been doubtfully identified with N. altonensis. They are internal casts, not very 

perfect at that, and their real affinities are obscure. It is possible that one of them 

may be a Soleniscu8, related to S. ponderosas. 

Locality and horizon,.--San Juan region (stations 2226, 2340); middle portion of 

the Hermosa formation and in the Rico formation. Dolores River region, Sinbads 

Valley (station 2285); top of the Hermosa formation. 

NATICOPSI5 MONILIFERA White. 

1880. Naticopsis monilifera. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 

1, p. 168, pl. 42, figs. 3a—c. 

Upper Coal Measures: Pleasant Hill, Cass County, Mo. 

1881. Naticopsis monilifera. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vol. 3, Supp., Appendix, p. xxxiv, p1. 3, figs. 3a—d. 

Carboniferous: Near Taos, N. Mex. 

1895. Pleurotomaria monilifera. Keyes, Missouri Geol. Surv., vol. 5, p. 144. (Date of imprint, 1894. ) 

Upper Coal Measures: Pleasant Hill and Kansas City, Mo. 

My specimens are so much exfoliated as to •be reduced almost to the condition 

of internal casts. The beaded ornamentation on the upper portion of the peritreme 

near the suture line is plainly visible, but otherwise, from such evidence as is available, I judge that the surface was without ornamentation. In general conformation 

these specimens are in the closest agreement with White's figures and descriptions, 

and as they also agree with the specimen from Taos, N. Mex., which he figures as 

N. monilifera, it is with little hesitation that they are referred to that species. 

a Geol. Surv. Illinois, Rept., vol. 5, 1873, p1. 28, figs. 12a, 12b. 
DESCRIPTIONS OF SPECIES. 465 

Although the shell, aside from the ornamental feature just mentioned, appears 

to be plain, yet, thinking that such characters might be obscured by the exfoliated 

condition which prevails, I at first identified these specimens as Pleurotomaria? 

spironona M. and W. They much resemble that species in shape, and might readily 

be mistakenly referred to it in their present condition. My material was compared 

with exfoliated specimens of Pl. ? s_pironona from Menard County, Ill. (identification by Worthen), and close agreement was found. The one fairly constant 

character that I can point out is that in Pl. ? spironema the beading is stronger and 

more elongate in a direction perpendicular to the suture. 

Keyes places this species with Pleurotomaria because he thinks that some time 

it will be shown to possess a slit band, though the type specimen seems to be without 

that character. I do not see, however, that matters are improved by this course, as 

a Pleurotomaria without a slit band is certainly more anomalous than a Xaticopsis 

with a row of ornamental nodes. Accordingly I have replaced it with the genus to 

which it was ascribed by White. 

_Locality and ltorizon.—San Juan region (stations 2231, '2342, 2345); Hermosa 

and Rico formations. 

EUOMPHALUS Sowerby, 1812. 

EUOMPHALUS CATILLO1DES Conrad. 

1842. lnachus catilloides. Conrad, Acad. Nat. Sci. Philadelphia, Jour., (1), vol. 8, p. 273. 

Coal Measures. 

1858. Euomphalus rugosus. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 722, pl. 29, figs. 14a—c. 

Coal Measures: Illinois. 

1866. Serpula (Spirorbis) planorbites. Geinitz, Carb. and Dyas in Nebraska, p. 3, tab. 1, fig. 6. 

Upper Coal Measures: Nebraska. 

1872. Straparollus (Euomphalus) rugosus. Meek, U. S. Geol. Surv. Nebraska, p. 230, pl. 6, figs. 5a, b 

pl. 11, figs. 4a, b. 

Upper Coal Measures: Nebraska City, Rock Bluff, Aspinwall, and Cedar Bluff, Nebr. 

Coal Measures: Kansas; Missouri; Iowa; Illinois. 

1873. Straparollus (Euomphalus) subrugosus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, 

p. 607, pl. 29, fig. 11. 

Coal Measures: Springfield, Ill. 

1874. Euomphalus rugosus. Meek, Am. Jour. Sci., (3), vol. 7, p. 583. 

Coal Measures: Illinois. 

1884. Euomphalus (Straparollus) subrugosus. Walcott, U. S. Geol. Surv., Mon., vol. 8, p. 255, p1. 18, 

fig. 19. 

Lower Carboniferous: Eureka district, Nevada. 

1884. Euomphalus rugosus. White, Geol. Surv. Indiana, 13th Rept., p. 161, pl. 32, figs. 11, 12. 

Coal Measures: Indiana. 

1888. Euomphalus rugosus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 241. 

Lower Coal Measures: Des Moines, Iowa. 


14364—No. 16 03 30 

466 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

1891. Straparollus catilloides. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 255. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Straparollus catilloides. Keyes, Missouri Geol. Surv., vol. 5, p. 160. (Date of imprint, 1894.) 

Upper Coal Measures: Kansas City, Mo.; Atchison, Kans. 

There can be little doubt that the shell described by Hall as Euomph,alus rugosus, 

and to which Meek and Worthen afterwards gave the specific name ,s-ubrugosus, is 

the same for which Conrad had already proposed the name Inachus catilloides, a 

circumstance which was, I believe, first pointed out by Keyes. Eu. catilloides has 

been recognized at but three localities in Colorado and is represented by only four 

specimens in all. 

Locality and horizon.—San Juan region (station 2333); middle portion of the 

Hermosa formation. Crested Butte district (station 2298); Maroon formation. 

Dolores River region, Sinbads Valley (station 2285); top of the Hermosa formation. 

BU-LIMORPHA Whitfield, 1882. 


BULIMORPHA CHRYSALIS Meek and Worthen. 


Pl. X, figs. 6, 6a, 7, 7a. 


1866. Polyphemopsis chrysalis. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 267. 

Lower Coal Measures: Hodges Creek, Macoupin County, Ill. 

1873. Polyphemopsis chrysalis. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 5, p. 596, pl. 28,. 

fig. 7. 

Coal Measures: Hodges Creek, Macoupin County, Ill. 

1889. Bulimorpha chrysalis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 300. 

1891. Bulimorpha? chrysalis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 264. 

Lower Coal Measures: Des Moines, Iowa. 

The form which has been referred to B. chrysalis is not abundant, and identification has not in every case been accomplished with complete satisfaction. Though 

slight differences have been observed, this species has been identified at stations 2342, 

2345, and 2347, all of which are in the Rico formation. At station 2271, in the Leadville district, occurs a somewhat larger though otherwise very similar shell, which 

the faunal list of the Leadville monograph a suggests may belong to this species. 

Locality and horizon.--San Juan region (stations 2342, 2345, 2347); Rico formation. Leadville district (station 2271). 

SOLENISCUS Meek and Worthen, 1860. 

SOLENISCUS cf. PALUDINIFORMIS Hall. 

1858. Macrocheilus paludinteformis. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 719, pl. 29, fig. 10. 

Lower Coal Measures: Des Moines Valley, Iowa. 

1884. Soleniscus (Macrocheilus) paludinwformis. White,. U. S. Nat. Mus. Proc., vol. 6, p. 187, pl. 8, fig. 17. 

Carboniferous: Indiana. 

a U. S. Geol. Surv., Mon., vol. 12, 1886, p. 67. 
DESCRIPTIONS OF SPECIES. 467 

1884. Soleniscus (Macrocheilus) paludinwfonmis. White, Geol. Surv. Indiana, 13th Rept., p. 154, p1. 34, 

fig. 17. 

Coal Measures: Vermilion County, Ind. 

1888. Macrocheilus paludinwformis. Herrick, Sci. Lab. Denison Univ., Bull., vol. 4, p1. 11, fig. 10. 

Coal Measures: Fultonhara, Ohio. 

1889. Soleniscus paludinEeformis. Keyes, Am. Nat., vol. 23, p. 423, pl. 20, fig. 16. 

1889. Soleniscus paludinwformis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 308. 

1891. Soleniscus paludinwformis. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 262. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Soleniscus paludinwformis. Keyes, Missouri Geol. Surv., vol. 5, p. 211. (Date of imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

Of this species we have a single representative which, when complete, had a 

length of about 5 mm. There are 5 volutions visible, the lower one of 'which 

is inflated and comprises well-nigh two-thirds of the entire length. The spire is 

and has a slightly higher spire. 

somewhat attenuated. In general character this shell is very close to 

formi8 

very much smaller, however, the Colorado specimen is probably a trifle more slender 

Locality.—Grand 

Hall, especially the form figured by White under that name. Besides being 

River region, Glenwood Springs (station 2193). 

S. paludiniMINUTE GASTEROPODS. 

At several stations collections were made consisting almost entirely of minute 

gastropods in sufficient abundance to give character to the strata. Although they 

are too imperfect to be identified, and no serious attempt to do so has been made, 

the circumstance is perhaps worthy of mention. At station 2213 in the Durango 

quadrangle and 2294 in the Crested Butte quadrangle they occur in chert bands 

and are quite numerous; at 2296, also in the Crested Butte, in a limestone 

conglomerate; at 2269, in the Leadville district, they are common, but not equally 

abundant. It is possible that station 2193, near Glenwood Springs, from which a 

number of minute gastropod forms have been obtained, is on the horizon of one or 

other of the stations above mentioned. The fossils from the former are in a fair 

state of preservation and have been provisionally identified with known species. 

Locality and horizon.—San Juan region (stations 2212, 2213); lower and middle 

portions of the Hermosa formation. Crested Butte district (stations 2294, 2296); 

Maroon formation. Leadville district (station 2269); upper portion of the Weber 

formation. 
468 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

BELLEROPHON Montfort, 1808, emend. Waagen, 1884. 

BELLEROPHON CRASSUS Meek and Worthen. 

1860. Bellerophon crassus. Meek and Worthen, Acad. Nat. Sci. Philadelphia, Proc., p. 458. 

Lower Coal Measures: Pittsburg, St. Clair County, Ill. 

1866. Bellerophon crassus. Meek and Worthen, Geol. Surv. Illinois, Rept., vol. 2, p. 385, pl. 31, figs. 

16a, b. 

Lower Coal Measures: Pittsburg, St. Clair County, Ill. 

1875. Bellerophon crassus. White, U. S. Geog. Geol. Surv. W. 100th Mer. Rept., vol. 4, p. 157, pl. 12, fig. 

la. (Whole volume published in 1877.) 

Carboniferous: Camp Cottonwood, near Spring Mountain, Nev. 

1884. Bellerophon crassus. White, Geol. Surv. Indiana, 13th Rept., p. 157, pl. 33, figs. 1, 2. 

Upper Coal Measures: Sullivan and Posey counties, Ind. 

1886. Bellerophon crassus ( var.)? Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 457. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Bellerophon crassus (var.)? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt 

2, p. 277. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Bellerophon (cf. crassus). Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 20, pl. 5, fig. 6. 

Coal Measures:. Flint Ridge, Ohio. 

1891. Bellerophon crassus. White, U. S. Geol. Surv., Bull. No. 77, p. 26. 

Permian: Military Crossing, Baylor County, Tex. 

1895. Bellerophon crassus. Keyes, Missouri Geol. Surv., vol. 5, p. 151, pl. 50, figs. la, b. (Date of 

imprint, 1894.) 

Upper Coal Measures: Kansas City and Lexington, Mo. 

1896. Bellerophon crassus. Smith, Leland Stanford Junior Univ. Publ., Cont. Biol. Hopkins Seaside 

Lab., No. 9, p. 39. 

Lower Coal Measures: Conway County, Ark. 

1896. Bellerophon crassus. Smith, Am. Phil. Soc., Proc., vol. 35, p. 249. 

Lower Coal Measures: Conway County, Ark. 

1897. Bellerophon crassus. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3; pt. 2, p. 853. 

Coal Measures. 

1899. Bellerophon crassus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 592. 

As almost all the specimens of this species occur in the form of internal casts, 

it can scarcely be said that the identification suggested above is worthy of entire 

reliance. At the same time they agree with specimens of B. crassus from the 

Mississippi Valley similarly preserved in all the characters of which their imperfect 

condition permits recognition. It is not at all improbable, however, that among the 

smaller shells referred to this species there are some which should be placed with 

other groups, especially with Ruphemus. 

Locality and h,orizon.—San Juan region (stations 2216, 2217, 2234?, 2340, 

2341, 2342); middle and upper portions of the Hermosa formation and in the Rico 

formation. Crested Butte district (station 2293); Maroon formation. Leadville 
DESCRIPTIONS OF SPECIES. 469 

district (stations 2273, 2275); upper portion of the Weber formation and in the 

Robinson limestone. 

BELLEROPHON GIGANTEUS Worthen? 

1884. Bellerophon giganteus. Worthen, Illinois State Mus. Nat. Hist., Bull. No. 2, p. 8. 

Lower Coal Measures: Monroe County, Ill. 

1890. Bellerophon giganteus. Worthen, Geol. Surv. Illinois, Rept., vol. 8, p. 143, pl. 25, figs. 5, 5a. 

Lower Coal Measures: Monroe County, Ill. 

1897. Bellerophon giganteus. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt. 2, p. 853. 

1899. Bellerophon giganteus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 592. 

At station 2338 in. the Rico formation occurs a Bellerophon of so large size that I 

have tentatively referred it to B. giganteus Worthen. This species was founded 

upon an internal cast and no determinative characters are known except its shape 

as such and its large size. The character last mentioned seems to have even less 

specific significance among the Bellerophontacea than in other groups. Among what 

seem to be mature examples well-known species show unusual variation in this 

regard. For instance, in the case of B. pereankatus, which is not often a large form 

and where an axial diameter of 25 mm. would not, perhaps, be under the average, an 

example now before me, apparently belonging to the same species, would have had, 

if perfect, a dimension of over 100 mm. So that as far as known B. giganteus 

might well be an unusual example of one of the well-known species. 

•The specimens from Colorado are much broken, but some of them must have 

attained a size much greater than ordinary. Another specimen in our collections 

which, so far as my material permits me to judge, is the same species as that from 

Colorado is said to have been found at Alton, Ill., and in the Coal Measures. The 

following notes are taken from the Colorado material. Fully grown specimens 

probably had a diameter of at least 85 mm. measured in the plane of revolution: A 

transverse section near the aperture is not a regular curve, but rather has the shape 

of a Gothic arch, being somewhat pointed at the top with a raised slit band. The 

surface is marked by rather strong transverse striae or sublamellose growth lines 

which bend backward more or less strongly as they approach the band. The shell is 

thick and massive, and the interior section is not far from a regular curve, the difference of contour between the inside and the out residing entirely in a median thickening of the shell. In the earlier stages the outside curvature also seems to be 

regular. There is some evidence for believing that B. giganteus? together with B. 

crassus and B. steven,sianus represent a single ontogenetic type. The chief, seemingly 

the only, points of difference between B. giganteus? and what may be called typical B. 

crassus is its large size and its keeled dorsum, but younger specimens of the former do 

not present the carinate condition and are of course of smaller dimensions. What I 

have reason to believe are young specimens of B. crassus are about the size and 
470 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

shape of B. stevensianus, while the growth lines are stronger and more regular than 

in the mature form. I am prepared to believe that half-grown shells of G. gigantetts? 

can not be distinguished from B. crassus, and that young specimens of B. crassus 

(and probably of the large form also) are indistinguishable from B. stevensianu,s. 

As regards the specific relationship of the Colorado (and the Illinois) form with 

Worthen's species, it is evident that an internal cast of the former would have the 

rounded contour of the latter, and the large size of both lends probability to the 

identification. It need not be pointed out, however, that B. giganteus differs in 

shape from the form provisionally referred to it, at least in that it is a more rapidly 

expanding and somewhat more flaring type. The circumstance that Worthen's 

specimen is an internal cast and perhaps otherwise not well preserved, while the 

aperture of my own is defective, widens the field of individual judgment. 

Locality and horizon.—San Juan region (station 2287); middle portion of the 

Hermosa formation. 

BELLEROPHON (sensu strictu) PERCARINATUS Conrad? 

1842. Bellerophon percarinatus. Conrad, Acad. Nat. Sci. Philadelphia, Jour., (1), vol. 8, p. 268. 

Coal Measures: Inclined plane of the Alleghany Mountain, in'black shale overlying the stratum 

of coal No. 7, Huntingdon, Pa. (?). 

1855. Bellerophon percarinatus. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 74, pl. 9, figs. 4a-c. 

Coal Measures: Grayville, Ill.; Posey County, Ind., 5 miles below New Harmony. 

1872. Bellerophon percarinatus. Meek, U. S. Geol. Surv. Nebraska, p. 227, pl. 11, .fig. 14. 

Upper Coal Measures: Nebraska City and Brownville, Nebr.; Grayville, Ill.; Illinois, Iowa, 

Missouri. 

Lower Coal Measures: West Virginia. 

1884. Bellerophon percarinatus. White, Geol. Surv. Indiana, 13th Rept., p. 158, pl. 33, figs. 9-14. 

Coal Measures: Indiana. 

. Bellerophon percarinatus. Claypole, Proc. and Coll. Wyoming Hist. and Geol. Soc., vol. 2, pt. 2, 

p. 246. 

Lower Coal Measures: Wilkesbarre, Pa. 

1887. _Bellerophon percarinatus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 17, pl. 2, fig. 14. 

Coal Measures: Flint Ridge, Ohio. 

1888. Bellerophon percarinatus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 234. 

Lower Coal Measures: Des Moines, Iowa. 

1895. Bellerophon percarinatus. Keyes, Missouri Geol. Surv., vol. 5, p. 153, pl. 50, figs. 2a-f. (Date 

of imprint 1894.) 

Upper Coal Measures: Kansas City, Mo. 

1897. Bellerophon percarinatus. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt 2, 

p. 853. 

Coal Measures. 

1899. Bellerophon percarinatus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 592. 

The material studied, though poorly preserved, is sufficiently well characterized 

to show that it certainly belongs to the group of Bellerophon pqrearinatu-9. Whether 
DESCRIPTIONS OF SPECIES. 471 

it belongs precisely to that species or to the closely related B. harrodi I am not able 

to say. The species seems to be abundant in the Hermosa formation at station 2327. 

Locality and horizon.— San Juan region (stations 2217, 2327); middle portion of 

the Hermosa formation. Leadville district (station 2275); upper portion of the 

Weber formation. Dolores River region, Sinbads Valley (station 2285); top of the 

Hermosa formation. 

PATELLOSTIUM Waagen, 1880, emend. Ulrich, 1897. 

PATELLOSTIUM OURAYENSE Gurley. 

Pl. X, figs. 10 to 10b. 

1884. Bellerophon, ourayensis. Gurley, New Carb. Foss., Bull. No. 2, p. 8. 

Upper Carboniferous: Ouray, Colo. 

1899. Patellostium ourayense. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 589. 

It is unfortunate and somewhat surprising that among the collections examined, 

many of which must have come from the same horizon, and some from near the type 

locality of Patellostium ourayense, which Gurley described without figures in 1884, 

no representative of that species has come to hand. Through the courtesy of the 

depaitrnent of geology of Chicago University, however, I am enabled to figure the 

typical specimen of that species which will be found represented by figs. 10, 10a, 10b 

of Pl. X. The original description of Patellostium ourayense, quoted in full, is as 

follows: 

" Shell medium size, subglobose, moderately expanding, slightly depressed laterally. Aperture reniform, arcuate. Umbilicus distinct, rather small. Lip conforming to the general direction of the growth of the shell, thin, slightly reflexed at 

the junction with the inner whorl. Lip divided into two lobes by a shallow mesial 

sinus formed by the ge qtle backward curve of the margin as it approaches the center 

of the lip. 

" Mesial band consisting of a sharply raised smooth ridge which is scarcely more 

than a prominent well-developed revolving line. 

Surface marked by several sparsely arranged revolving striae which become 

very numerous and crowded close to the mesial band, there being seven strife within 

a space of 2 millimeters on each side of the mesial band, while on the remaining portion to the umbilicus there are only five striw occupying a space of about 5 millimeters in width. These lines increase by implanation with the growth of the shell. 

There are numerous fine, sharply defined transverse lines of growth which 

curve gracefully backward as they approach the carina. These lines of growth are 

equal y as prominent as the revolving striae, and terminate a short distance from the 

sharp raised mesial band. The revolving striae and transverse lines of growth give 

the s rface a rather coarse imbricate appearance, although in crossing each other the 

lines re uninterrupted. 

This species has the general form of B: steven,sanus McChesney, possessing 

the 1 erally depressed sides and sharply raised mesial band seen in that form, but 

differ ng very materially in the ornamentation. 
472 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

" Position and locality.—From a hard, dark micaceous sandy shale belonging 

to the Upper Carboniferous series and probably equivalent to the Middle Coal 

Measures, Ouray, Colo." 

A comparison of the terms of this description with the type specimen shows 

several inaccuracies of expression and one or two additional points to which I desire 

to call attention. The statement describing the mesial band is misleading, for that 

structure is not smooth but crossed by distinct sublamellose strive, and it is many 

times as large as the revolving lines which cross the surface of most shells of this 

group. In fact, it is proportionately as large if not a little larger than it is usual 

for the slit band to be. The surface ornamentation consists of transverse and 

revolving elements which, however, are different in character from one another. 

The revolving lines are sharply elevated, threadlike striae which in the specimen in 

hand, are irregular in size and distribution, so that in it the two sides of the shell are 

differently marked. As shown by the figure (fig. 10), the strive which traverse the 

left side, some 5 or 6 in number, while irregularly distributed, are in every case 

separated by intervals many times their own width. Between these I think there 

can be discerned traces of much finer revolving lines. On the other side, the striae 

are somewhat finer and crowded near the band, but the outer or umbilical portion of 

this side is marked similarly to the other. Both sides, where the inner end of the 

whorl is about to be lost in the aperture,' are marked alike by fine, crowded strite, 

among which some, more or less regularly distributed, are larger and stronger than 

the others. On the whole, the surface of the average specimen probably consisted 

of fine, crowded, revolving lines with larger ones at intervals. Transversely, the 

shell is marked by many fine-growth lines and by rug, which are not only much 

coarser than the revolving strive, but different in character, inasmuch as they are 

poorly defined instead of being sharply and suddenly elevated. They seem to be 

ianum, 

are directed as in the original description, but both can be traced quite to the slit 

elevated medially and somewhat flattened laterally, the shape of the section is rather 

similar to the rugose elevations which form so marked a character in 

band. The vault of the shell is not of the rounded, circular type, but, being 

but are more numerous and much less prominent. Growth lines and strive 

P. montfortthat of a Gothic arch. 

This species is related to P. bellum and P. nodocostatum, but seems to be distinct 

from either. I have compai-ed the type specimen of P. ourayense with a large series 

of specimens from Rulo, Nebr. which probably can be referred to P. bellum, 

and am able to point out the following differences: The peritreme of P. bellum is 

flattened on top with a circular section, while that of P. ourayense is compressed and 

pointed at the slit band. The surface ornamentation is very similar in the two 

species. It differs chiefly in that the transverse rug are stronger and more sharply 
DESCRIPTIONS OF SPECIES. 473 

defined in P. helium, being, in fact only slightly different from the revolving striae 

with which they regularly decussate, forming indistinct nodes at the points of intersection. The revolving striae in P.. bellum are somewhat stronger and coarser, while 

the transverse markings go nearly straight across instead of being curved, with a 

backward inclination. The slit band also is marked by strong rug alternating with 

those of the lateral surface, while the slit band of P. ourayense, though marked by 

strive, is but slightly rugose. 

Locality and horizon.—Near Ouray at about the same locality and horizon as 

station 2195. 

PATELLOSTIUM MONTFORTIANUM Norwood and Pratten. 

1855. 	Bellerophon montfortianus. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour., (2), vol. 3, 

p. 74, pl. 9, figs. 5a-c. 

Coal Measures: Galatia, Ill., and 5 miles below New Harmony, Ind. 

1866'. Bellerophon montfortianus. Geinitz, Carb. und Dyas in Nebraska, p. 8, tab. 1, fig. 13. 

Coal Measures: Nebraska City, Nebr. 

1866. Bellerophon interlineatus. Geinitz, Carb. und Dyas in Nebraska, p. 8, tab. 1, fig. 14. 

Coal Measures: Nebraska City, Nebr. 

1872. 	Bellerophon montfortianus. Meek, U. S. Geol. Surv. Nebraska, p. 225, pl. 11, figs. 15 (12?). 

Upper Coal Measures: Nebraska City, Nebr. 

Coal Measures: Nebraska, Kansas, Iowa, Missouri, and Illinois. 

Lower Coal Measures: West Virginia. 

1876. 	Bellerophon montfortianus. White, Powell's Rept. Geol. Uinta Mountains, p. 92. 

Upper Aubrey Group: Confluence of Grand and Green rivers, Utah. 

1887. Bellerophon montfortianus. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 19, pl. 2, fig. 1; pl. 5, 

fig. 8. 

Coal Measures: Flint Ridge, Ohio. 

1888. Bellerophon montfortianus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 235. 

Lower Coal Measures: Des Moines, Iowa. 

1891. Bellerophon montfortianus. White, U. S. Geol. Surv., Bull., No. 77, p. 26, pl. 3, figs. 15, 16. 

Permian: Goodwin Creek, Baylor County, Tex. 

1891. Bellerophon montfortianus. Keyes, Acad. Nat. Sci. Philadelphia, Proc., p. 254. 

Lower Coal Measures: Des Moines, Iowa. 

1895.. Bellerophon•montfortianus. Keyes, Missouri Geol. Surv., vol. 5, p. 151. (Date of imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

1897. Patellostium montfortanus. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt. 2, 

p. 854. 

Coal Measures. 

1899. Patellostium, montfortianum. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 589. 

Though the material representing this species is imperfect, the identification may 

be considered fairly reliable in some cases. A poorly preserved individual found at 

station 2275 in the Tenmile district has been referred to P. montfortianum with 

doubt. It may be a very large example of P. bellum. 
474 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Locality and horizon..—San Juan region (stations 2204?, 2221 ?, 2327); upper 

portion of the Hermosa formation. Leadville district (station 2275?); upper portion 

of the Weber formation. 

PATELLOSTIUM BELLUM Keyes. 

1895. Bellerophon belles. Keyes, Missouri Geol. Surv., vol. 5,.p. 148, pl. 50, fig. 7. (Date of imprint 

1894.) 

Upper Coal Measures: Kansas City, Mo. 

1899. Patellostium nodocostatum. Girty (non Gurley), U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 

3, p. 590. 

Upper Coal Measures: Atoka quadrangle. 

The material representing this species is so very scanty, fragmentary, and poorly 

preserved that I find myself unable to identify it with the accuracy desirable. That 

from the Hermosa formation (Rico quadrangle, Sandstone Mountain, station 2217), 

though the surface ornamentation is partially obscured, is close to P. hellin, and 

probably better material would sanction the identification. From the Rico formation 

but two specimens have been obtained. One from station 2340 is practically indeterminable, but probably is conspecific with the other. The specimen from station 

2337 seems to be somewhat different from the form obtained from the Hermosa 

formation. It shows a small area of surface in fairly good preservation, whose 

ornamentation differs from that of P. bellam in having the transverse strive finer and 

sharper and the revolving striae finer and more nearly equal. It is possible, therefore, that the Patellostiuin which occurs in the Hermosa formation is not the same 

as that from the Rico formation. 

On a former occasion I ventured to throw Patellostiuni helium Keyes into the 

synonymy of P. nodocostatum Gurley, basing the opinion upon Gurley's description 

on one hand and on the other upon specimens from Rulo, Nebr., thought to belong 

to P. helium. Through the courtesy of the department of geology of Chicago 

University I have enjoyed the privilege of examining the types of Gurley's species 

of Bellerophon, and now feel compelled to reverse the judgment expressed at that 

time. In view of its intimate relations with several of. Gurley's species, the small 

figure and brief description of Keyes afford an inadequate conception of P. helium. 

Nevertheless the Rulo specimens are still believed to belong to that species. From 

these P. noclocostatain differs in having the transverse stripe somewhat stronger an d 

the revolving striae finer. The latter, therefore, instead of being equal to the transverse ones, as in P. hellin, and merging with them at the intersection into indistinct 

nodes, are in P. nodocostatum considerably finer and cross the transverse ridges 

without becoming confluent. They become, in fact, stronger and more prominent 

on their crests. 

The ornamentation of P. textiliforme is similar to that of P. nodocostatum, but 
DESCRIPTIONS OF SPECIES. 475 

it is upon a much smaller scale, the striae, both revolving and transverse, being finer 

and consequently more numerous. The statement that in this species the transverse 

striae do not cross the slit band is certainly erroneous. In some specimens, owing 

apparently to abrasion, they are partially removed on this portion of the shell, but 

in general they seem to be about as prominent on the slit, band as over the more 

lateral areas. It is possible that P. bellum, which was obtained from Kansas City, as 

was also P. textiliforme, may belong to the same species. In that case the form 

from Rulo and the present material would represent an undescribed form. 

The surface of the form from the Rico formation, to which reference has been 

made above, is more like that of P. bellum than of the other American species I have 

seen, and if it proves to be different from P. benzin?, as seems likely, it is probably 

a new variety. 

Locality and h,orizon.—San Juan region (stations 2217,2337, 2340); middle portion 

of the Hermosa formation and in the Rico formation. 

EUPHEMUS McCoy, 1862, emend. Waagen, 1880. 

EUPHEMUS NODOCARINATUS Hall. 

1858. Bellerophon nodocarinatus. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 723, pl. 29, figs. 15a-c. 

Coal Measures: Illinois and Iowa. 

1884. Bellerophon nodocarinatus. White, Geol. Surv. Indiana, 13th Rept., p. 159, pl. 33, figs. 3-5. 

Coal Measures: New Harmony, Ind. 

1886. Bellerophon nodocarinatus? Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 457, 

fig. 13. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1886. Bellerophon nodocarinatus? Heilprin, Proc. and Coll. Wyoming Hist. and Geol. Soc. vol. 2, 

pt. 2, p. 277, fig. 13. 

Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

1887. Bellerophon nodocarinatus. Herrick, Sci. Lab.' Denison Univ., Bull., vol. 2, p. 18, pl. 3, fig. 3. 

Coal Measures: Flint Ridge, Ohio. 

1895. Bellerophon nodocarinatus., Keyes, Missouri Geol. Surv., vol. 5, p. 152, pl. 50, figs. 4a-c. (Date 

of imprint, 1894. ) 

Upper Coal Measures: Kansas City, Mo. 

1897. Euphemus nodocarinatus. Ulrich, Geol. Nat. Hist. Surv. Minnesota, Final Rept., vol. 3, pt. 2, 

p. 855. 

1899. Euphemus nodocarinatus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 592. 

With. the exception of stations 2340 and 2344 in the Rico formation, the 

specimens which I have referred to Eu. nodocarinatus are preserved as internal 

casts. Even those which show the characteristic revolving striae are not sufficiently 

complete so that I am able to determine whether they are strictly identical with Eu. 

carbon,arius, with Eu. subpapillosus, with Eu. inspeciosus, or with Eu. nodocarinatus. 

Of the casts, some specimens represent, perhaps, young examples of Bellerophon 

crass 11,8. 
476 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Some of this material must belong, I think, to the carbonarius-subpapillosus 

type, but a part, that from stations 2340 and 2344 especially, seems nearer to Eu. 

in,speciosus and Eu. nodocarinatus. 

Locality and horizon.—San Juan region (stations 2217 ?, 2340, 2344, 2345, 2349); 

middle portion of the Hermosa formation and in the Rico formation. 

EUPHEMUS SUBPAPILLOSUS White? 

1876. Bellerophon carbonarius var. subpapillosus. White, Powell's Rept. Geol. Uinta Mountains, p. 92. 

Upper Aubrey Group: Beehive Point, near Echo Canyon, and near Echo Park, Utah. 

1879. Bellerophon subpapillosus. White, U. S. Geol. Geog. Sum Terr., Bull., vol. 5, p. 218. 

Carboniferous: Wild Band Pockets, northern Arizona, 15 miles south of Pipe Spring. 

1880. Bellerophon subpapillosus. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, 

pt. 1, p. 138, pl. 34, fig. 3a. • 

Upper Carboniferous: Northwestern Colorado and northern Arizona. 

1883. Bellerophon subpapillosus. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, 

pt. 1, p. 138, pl. 34, figs 3a. 

Upper Carboniferous: Northwestern Colorado and Northern Arizona. 

1899. Euphemus subpapillosus. Girty, U. S. Geol. Surv., 19th Ann. Rept., pt 3, p. 592. 

The only specimens referred to this species are those from the Uinta Mountains, which were so identified by White. Although they are mere casts, so that 

I have been able to see none of the surface ornamentation, from their size and 

configuration it seems not improbable that White's identification may be correct. 

carinatu,s, 

rank. 

posed to give this type, for which White proposed only a varietal name, full specific 

Some of the exfoliated specimens which have been placed with 

Locality and horizon.

or even with Bellerophon crassus 

—Uinta Mountain region, near the south fork of the Vermay, however, belong here. I am disEuph,emus nodomilion and near the east base of Diamond Peak (station 2189); Bellerophon lime 

stone at the very top of the Carboniferous. 

CEVHALOPODA. 

DOMATOCERAS Hyatt, 1891. 

DOMATOCERAS sp. 

It is probable that the same species occurs at both. the localities cited below, 

though the condition of my material does not permit me to speak with confidence. 

The fornyis not determinable from the specimens in the collections. 

Locality and h,orizon.---Leadville district (stations 2275 and 2276); upper portion 

of the Weber formation. 
DESCRIPTIONS OF SPECIES. 477 

TAINOCERAS Hyatt, 1883. 

TAINOCERAS sp. 

A single specimen, crushed in shale and macerated, has been found. It is 

evidently related to T. occidentalis Swallow, but it is too poorly preserved to admit 

of identification. 

Locality and horizon.—San Juan region (station 2201); upper portion of the 

Hermosa formation. 

CRUSTACEA. 

PHILLIPSIA Portlock, 1843. 

PHILLIPSIA MAJOR Shumard. 

1823. Trilobus. Say, Long's Exped. to Rocky Mountains, vol. 1, p. 148 (folitnote). 

Missouri River, 5 miles below Council Bluffs. 

1858. Phillipsia major. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 226. 

Upper Coal Measures: Clinton County, Mo.; Valley of Verdigris, and 12 miles south of Lecompton on the Santa Fe road, Kansas. 

1872. Phillipsia major. Meek, U. S. Geol. Surv. Nebraska, p. 238, pl. 3, figs. 2a-c. 

Upper Coal Measures: Bellevue and Plattsmouth, Nebr.; Clinton County, Mo.; Vermilion 

River, 12 miles south of Lecompton, Kans. 

1887. Phillipsia major. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 60. 

Upper Coal Measures: Kansas. 

1887. Phillipsia major. Vogdes, New York Acad. Sci., Ann., vol. 4, p. 85, pl. 3, fig. 14. 

Upper Coal Measures: Clinton County, Mo.; Valley of the Verdigris River, 12 miles south of 

Lecompton on the Santa Fe road, Kansas; Kansas City, Mo.; Bellevue, Nebr. 

1891. Phillipsia major. Hare, Kansas City Scientist, vol. 8, p. 33, pl. 1, figs. 5, 8a-c. 

Coal Measures: Kansas City, Mo. 

1895. Phillipsia major. Keyes, Missouri Geol. Surv., vol. 4, p. 238, pl. 32, figs. 8a-e. (Date of imprint, 

1894.) 

Upper Coal Measures: Kansas City, Mo. 

1897. Trilobus. Harris, Am. Pal., Bull., vol. 1, p. 382 (112). 

Sandstone of the Missouri; near. Engineer Cantonment. 

This species has been identified at three localities, but at each only one specimen 

was found. They are very imperfect, being more or less crushed and exfoliated. 

Differences have been noted which, were the material better and more abundant, 

might have justified me in discriminating two groups where now I recognize but one. 

The form from Ouray, especially, shows characters which, if constant, should separate 

it from the two other specimens, which are mutually more alike. Herricka casts doubt 

upon Meek's identification, in his Nebraska report, of Shumard's species. The 

Colorado forms are of the type figured by Meek, but show departures which might, 

with adequate material, prove varietal, or even specific. 

a Loc. cit., p. 60. 
478 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Locality and horizon.—San Juan region (station 2332); middle portion of the 

Hermosa formation. Ouray (station 2195); Hermosa formation. Leadville district 

(station 2257); lower portion of the Weber formation. 

PHILLIPSIA TRINUCLEATA Herrick. 

Pl. X, figs. 15, 16. 

1887. Phillipsia trinucleata. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 64, pl. 1, fig. 23; 

pl. 2, fig. 32; p1. 3, fig. 21. 

Coal Measures: Flint Ridge, Ohio. 

1888. Proetus trinucleatus. Vogdes, New York Acad. Sci., Ann., vol. 4, p. 81, pl. 2, figs. 7-9. 

Waverly group [in error]: Flint Ridge, Licking County, Ohio. 

Two or three specimens from Colorado seem to belong to Herrick's species cited 

above. None of the material is very good and that from station 2297 in the Crested 

Butte district and from station 2210 in the Durango quadrangle of the San Juan 

region is so imperfect that I am not certain that it is conspecific with the others. 

Locality and horizon.—San Juan region (station 2210); upper portion of the 

Hermosa formation. Crested Butte district (station 2297l); Maroon formation. 

Leadville district (stations 2259, 2265); Weber formation. 

LEPERDITIA Rouault, 1851 

LEPERDITIA sp. 

Ostracoda belonging to the genus Leperclitia are very abundant at station 2212 

in the San Juan region, and station 2269 in the Leadville region. The most perfect 

material is that from the San Juan region. The prevailing form is a transversely 

elongate, nearly equilateral shell, which rarely attains a width of 2 millimeters. The 

latter dimension is a little less than twice as great as the height. The eye spot must 

be very small or very obscure, and I have not been able to detect it with certainty. 

The surface appears to be quite smooth and solid. 

It is possible that among the shells included under this title more than a single 

species may exist. 

Locality and horizon.—San Juan region (station 2212); middle portion of the 

Hermosa formation. Leadville district (station 2269); upper portion of the Weber 

formation. 

BAIRDIA McCoy, 1844. 

BAIRDIA sp. 

But a single species belonging to this genus has been described from American 

Carboniferous rocks, Bairdia cestriensis Ulrich,a and though from a higher horizon, 

a Cincinnati Soc. Nat. Hist., Jour., vol. 13, p. 210, pl. 17, figs. 6a-c, 7a, b. 
DESCRIPTIONS OF SPECIES. 479 

the Colorado form is of the same general type. It is, however, without much doubt 

a distinct species, but since only a single specimen has come to hand I do not feel 

justified in giving it a new name. The length is about 1.5 mm., thus making it larger 

than the Mississippian species, and it is also more transverse. The posterior extremity 

is probably not as pointed as the older specimen figured by Ulrich (fig. 6), and much 

less so than the younger one (fig. 7). The upper and lower margins are nearly 

rectilinear and parallel, though they gradually converge toward the anterior margin, 

which is rather regularly and strongly rounded. 

This species occurs associated with several ostracode forms at Empire Hill in 

the Leadville district (station 2265), a locality which, with larger collections, would 

probably furnish an extensive fauna of this group. In addition to the types 

mentioned here under a separate heading, still another very minute form is found 

whose relations I have not been able to make out. 

Locality and horizon.--Leadville district (station 2265). 

BEYRICHIA McCoy, 1844. 

BEYRICHIA sp. 

This form is extremely abundant at Glenwood Springs (station 2193). The 

following brief description is offered: 

The width is usually from 1 to 1.5 mm., and this dimension is from one and 

one-half to twice the height. The upper margin is long and straight. The ends are 

strongly, and the inferior margin gently, rounded. • The posterior end of the hinge 

line is more or less angular. The shape is nearly symmetrical with respect to a 

vertical axis. Somewhat anterior to the middle, as it appears, the shell is divided 

by a deep, strong sulcus, which is vertical to the hinge and has a length about 

one-third as great as the height of the shell. Not far anterior to this another fainter 

groove can usually be detected. The lower ends of these two depressions are 

sometimes seen to be deflected and to unite, thus inclosing a small median lobe. The 

surface is delicately and beautifully hachured. 

This species appears to be one of the simple Beyrichian types related to B. arcuata 

of the Carboniferous rocks of Great Britain. 

A closely related and possibly identical form is found at Empire Hill, in the 

Leadville district. My material is very scanty, and at the same time somewhat 

imperfect, so that I have not entirely assured myself as to the relations of these two 

forms. 

Locality.—Grand River region, Glenwood Springs (station 2193). Leadville 

district (station 2265). 
480 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

KIRKBYA Jones, 1869. 

KIRKBYA sp. 

Of this form a single specimen has been discovered. The shell has a subcentral 

protuberance and two or three heavy concentric furrows. The surface is coarsely 

reticulate. 

It is evidently related to Kirkbya plicata Jones and Kirkby, and is probably 

identical with that species. 

Locality and horizon .—Leadville district (station 2265); Weber formation. 
PLAT H] S. 

14364—No. 16 03 31 
 481 

PLATE I. 

PLATE I. 

Page. 

FIG. 1. MENOPHYLLUM ULRICHANUM 271 

A nearly perfect specimen, slightly broken at the tip, showing the rapid expansion and 

curved shape chara.cteristic of the species. 

Side view. Somewhat turned toward the eye, actual curvature diminished by perspective. 

Ouray limestone: Cascade Creek, in the Engineer Mountain quadrangle (station 2379). 

FIG. 2. MENOPHYLLUM ULRICHANUM 271 

A cast in chert of the calice of an individual belonging to this species. 

Cast seen from above. The relation of the primary to the secondary septa, the main 

fossula (that in the center), the two secondary fossuke (especially that on the left) , and 

the tripartite arrangement of the septa resulting therefrom, are well shown. 

Ouray limestone: Canyon Creek, in the Needle Mountains quadrangle (station 2386). 

FIG. 3. SPIRIFERINA SOLIDIROSTRIS ? 294 

A small dorsal valve preserved as a cast in chert, considerably enlarged. The punctate 

character of the shell is well shown by the pustules on the cast, The specimen is too 

young to show clearly the slight median division of the fold. 

Specimen seen from above. 

Millsap limestone: Perry Park (station 2389). 

FIG. 4. SPIRIFERINA SOLIDIROSTRIS ? 294 

A somewhat larger ventral valve, similarly preserved and also enlarged. The incipient 

plication in the middle of the sinus is shown in this individual, also the impression of 

the median septum and dental 

Specimen seen from above. 

Millsap limestone: Perry Park (station 2389). 

FIG. 5. SEMINULA SUBQUADRATA? 296 

Small example; larger specimens closely resemble Seminula subquadrata Hall. 

Ventral valve seen from above. 

Leadville limestone: Leadville district, Oolite mine, Leadville (station 23751. 

FIG. 6. CRANZENA SUBELLIPTICA 299 

An example from the typical locality, presenting the usual characters. Preserved chiefly 

as an internal cast, with small fragments of the shell adhering. 

Dorsal view of specimen. 

Waverly group: Sciotoville, Ohio. 

FIG. 7. CRAN/ENA SUBELLIPTICA 

Another example preserved as an internal cast, having the usual shape and size and showing 

many of the structural features of the genus. 

Dorsal view. This specimen shows the two dental lamellae of the ventral valve. The 

broken part at the right is along one of these. The posterior portion of the cast of the 

dorsal valve has been chiseled away so as to show the hinge plate with its two carinEe, 

which project as the two limbs of the crura. 

Waverly group: Sciotoville, Ohio. 

484 

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CARBONIFEROUS FOSSILS OF COLORADO. 

DESCRIPTION OF PLATE I—CONTINUED. 485 

Page. 

FIG. 8. CRAN/ENA SUBELLIPTICA var. HARDINGENSIS 299 

A ventral valve of somewhat near the average shape and size, preserved in chert. Other 

specimens are more rotund. 

Specimen seen from above, showing the two dental lanaelloe. 

Millsap limestone: Harding's quarry, Canyon, Colo. (station 2370). 

FIG. 9. CRANIENA SUBELLIPTICA var. HARDINGENSIS 299 

Dorsal valve of the same species. 

Specimen (an internal cast) seen from above. A very faint median septum is shown; 

the marks on either side are connected with the muscular attachment. Near the 

posterior margin appear the cavities left by the socket plates. 

Millsap limestone: Garden Park, Colo. (station 2365). 

FIG. 10. CRAN/ENA SUBELLIPTICA var. HARDINGENSIS 299 

Ventral valve of somewhat more than the average size and proportionate length. 

Specimen seen from above. This example also is preserved as an internal cast in chert. 

Millsap limestone: Garden Park, Colo. (station 2371). 

FIGS. 11 AND 11a. EUMETRIA WOOSTERI 302 

Type and original specimen figured by White. Artificial impression from a natural mold. 

Fig. 11. Ventral view. 

11a. Side view. 

Pebbles in the Wyoming sandstone (?), 32 miles west and 18 miles north of Greeley, Colo. 

(station 2364 ). 

FIG. 12. MYALINA KEOKUK 309 

A left valve believed to belong to this species. Preserved as a cast in chert. 

Specimen seen from above. 

Ouray limestone: Near Cascade Creek, Engineer Mountain quadrangle (station 2382). 

FIG. 13. STREBLOPTERIA MEDIA 307 

An isolated right valve referred to Herrick's species. 

Specimen seen from above. 

Millsap limestone: Perry Park, Colo. (station 2389). 

FIG. 14. ARCHIEOCIDARIS °CRAVENS'S 329 

A somewhat imperfect specimen partially embedded in matrix, showing the peculiar 

and characteristic ornamentation. 

Specimen seen from the side, and somewhat enlarged. 

Hermosa formation (?): Ouray, Colo. (station 2194). 

FIG. 15. PRISMOPORA TRIANGULATA 340 

A group of specimens partially embedded in limestone. This is the specimen originally 

figured by White. 

Specimen somewhat enlarged, showing the external characters of the species. 

Middle division of the Carboniferous series: Yampa Plateau, northwestern Colorado. 

FIG. 16 TO 16b. ORTHOTICHIA SCHUCHERTENSIS 345 

The most perfect specimen obtained, preserving both valves. 

Fig. 16. Ventral view. The shape and peculiar surface characters are well shown, 

also the septum and strong dental plates of the ventral valve. 

16a. Anterior view, showing the shape and relations of the valves and the somewhat 

different character of their surface ornamentation. 

16b. Side view of the same. 

Weber shale: Glenwood Springs, Colo. (station 2193a). 
486 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 

Page. 

FIG. 17. CHONETES FLEMINGI 352 

A specimen showing the customary characters. 

Ventral valve. 

Near Grand River, Colo.(?) (station 2324). 

FIGS. 18 AND 18a. CHONETES FLEMING' 352 

Another specimen of slightly different shape. 

Fig. 18. Ventral view. 

18a. Dorsal view. 

Near Grand River, Colo.(?) (station 2324). 

FIGS. 19 AND 19a. CHONETES GEINITZIANUS 355 

One of the better preserved specimens belonging to this species. 

Fig. 19. Ventral view. 

19a. Dorsal view. 

Weber shale: Leadville district (station 2267). 

FIG. 20. CHONETES MESOLOBUS 357 

A specimen in which the lobation is moderately strong. 

Ventral view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2238). 

FIG. 21. CHONETES MESOLOBUS 357 

Another specimen, somewhat more alate than the preceding, and with the lobation less 

strongly marked. 

Ventral view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2238). 

FIG. 22. CHONETES MESOLOBUS 357 

A large specimen in which the lobation is obsolescent. 

Ventral view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2238). 

FIG. 23. CHONETES MESOLOBUS 357 

An example in which the characteristic lobation is very faint. 

Ventral view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2238). 
PLAT IHIL 

PLATE II. 

Page. 

FIGS. 1 TO lc. PRODUCTUS SEMIRETICULATUS var. HERMOSANUS 358 

A very characteristic specimen. The ears are somewhat broken away. 

Fig. 1. Ventral valve seen from above. 

la. Anterior view. 

lb. Posterior view. 

lc. Side view. 

Hermosa formation: Between Hermosa Creek and Animas Valley, Durango quadrangle 

(station 2204). 

FIGS. 2 TO 2b. PRODUCTUS SEMIRETICULATUS var. HERMOSANUS 358 

Another somewhat smaller specimen of the type common in the Hermosa formation. 

Fig. 2. Ventral valve seen from above. This figure represents the specimen too much 

tilted downward and forward. 

2a. Anterior view of the same. 

2b. Side view. The pose of the specimen is not quite correct, the near cardinal angle 

being evidently somewhat depressed from the line of sight. 

Hermosa formation: Hermosa Creek (?), Durango quadrangle (station 2333). 

FIGS. 3 TO 3b. PRODUCTUS SEMIRETICULATUS var. HERMOSANUS 358 

A rather small dorsal valve which is somewhat imperfect. 

Fig. 3. Specimen seen from above. Possibly the cardinal angles should be restored as 

more projecting. 

3a. Side view. 

3b. Posterior view. 

Hermosa formation: Animas River, Durango quadrangle (station 2335). 

FIGS. 4 TO 4b. PRODUCTUS SEMIRETICULATUS var. HERMOSANUS 358 

Ventral valve of a finely striated type more or less intermediate between this species and 

Productus inflatus, to which, on the whole, I am disposed to regard it as nearer related. 

Fig. 4. Specimen seen from above. 

4a. Posterior view. 

4b. Side view. 

Weber formation: Weston Gulch, Leadville district (station 2268). 

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CARBONIFEROUS FOSSILS OF C LORADO. 

PLATE III. 

PLATE III. 

Page. 

FIGS. 1 TO lb. PRODUCTUS INFLATUS 359 

A typical ventral valve of the form referred to McChesney's species. 

Fig. 1. Specimen seen from above. 

la. Side view. 

lb. Posterior view. 

Weber formation (?): Horseshoe Mountain, Leadville district (station 2281). 

FIGS. 2 TO 2a. PRODUCTUS INFLATUS 359 

A ventral valve in which the cardinal angles have been broken away. 

Fig. 2. Specimen seen from above. The figure shows the striae as proportionally too coarse. 

2a. Posterior view. 

Weber formation (?): Horseshoe Mountain, Leadville district (station 2281). 

FIG. 3. PRODUCTUS INFLATUS 359 

A specimen in which both valves are retained in place. 

Dorsal view. 

Weber formation (?): Horseshoe Mountain, Leadville district (station 2281) . 

FIGS. 4 AND 4a. PRODUCTUS GALLATINENSIS 361 

A specimen of the ordinary size and character. 

Fig. 4. Anterior view. 

4a. Side view. 

Hermosa formation: Near Cascade Creek, in the Engineer Mountain quadrangle (station 2247). 

FIG. 5. PRODUCTUS GALLATINENSIS 361 

Another characteristic specimen, somewhat smaller than the foregoing and of unsymmetrical growth. 

Posterior view. The specimen is represented as too much tilted forward, by which the 

height appears unnaturally diminished. 

Hermosa formation: Near Cascade Creek, in the Engineer Mountain quadrangle (station 

2247). 

FIG-S. 6 TO 6b. PRODUCTUS GALLATINENSIS 361 

Another ventral valve belonging to this species 

Fig. 6. Anterior view. 

6a. Posterior view. In this case also the tilting of the specimen causes the height 

to appear less than it should be. 

6b. Side view. 

Hermosa formation: Bear Creek, in the Durango quadrangle (station 2213). 

FIG. 7. PRODUCTUS GALLATINENSIS 361 

A large ventral valve, somewhat distorted through compression. 

Posterior view. 

Hermosa formation: San Juan region (station 2233). 

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CARBONIFEROUS FOSSILS OF COLORADO. 

DESCRIPTION OF PLATE III—C NTINUED. 491 

Page. 

FIGS. 8 AND 8a. PRODUCTUS GALLATINENSIS 361 

A dorsal valve belonging to this species. 

Fig. 8. Specimen seen from above. 

8a. Side view. 


Hermosa formation: Bear Creek, in the Durango quadang e (station 2213). 


FIGS. 9 TO 9b. PRODUCTUS sp.b 363 

A ventral valve from which the shell has been largely exf liated. 

Fig. 9. Specimen seen from above. 

9a. Side view, in which the pose is not quite satisfact ry. 


9b. Posterior view. 


Hermosa formation: Bear Creek, in the Durango quadranle (station 2214). 


FIG. 10. PRODUCTUS sp.b 363 

An interior of a dorsal valve referred to this species. 

Side view. 

Hermosa formation: Bear Creek, in the Durango quadran-le (station 2214). 

FIG. 11. PRODUCTUS sp.b 363 

Interior of a somewhat smaller dorsal valve. 

Specimen seen from above. 

Hermosa formation: Bear Creek, in the Durango quadrangle (station 2214). 

PLAT IV. 

PLATE IV. 

Page. 

FIGS. 1 TO lb. PRODUCTUS CORA 364 

A large dorsal valve from the Rico formation. 

Fig. 1. Specimen seen from above., 

la. Posterior view. 

lb. Side view. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIGS. 2 AND 2a. PRODUCTUS CORA 364 

A large dorsal valve from the Hermosa formation. A specimen in which a number of 

conformable shelly layers are seen, possibly representing parts of several superposed 

individuals. 

Fig. 2. Specimen seen from above. The striae are represented as somewhat too coarse 

in this figure. 

2a. Side view. The striae in this figure are shown in their natural relation to the 

size of the shell. 

Hermosa formation: Sandstone Mountain, Rico quadrangle (station 2216). 

FIGS. 3 AND 3a. PRODUCTUS CORA 364 

Another ventral valve from the Hermosa formation, more coarsely and regularly striated 

than the last. It is somewhat crushed by pressure. 

Fig. 3. Specimen seen from above. The figure shows the anterior end of the specimen 

tilted too far downward. 

3a. Side view of the same. 

Hermosa formation: Bear Creek, Durango quadrangle (station 2213). 

FIGS. 4 AND 4b. PRODUCTUS CORA. 364 

A ventral valve of a small, -finely striated variety, probably considerably broken in its 

anterior portion. 

Fig. 4. Specimen seen from above. 

4a. Posterior view. 

4b. Side view. 

Hermosa formation: Big Percent Creek, Durango quadrangle (station 2300). 

494 
PROFESSIONAL PAPER NO. 16 PL. IV U. S. GEOLOGICAL SURVEY 

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CARBONIFEROUS FOSSILS OF COLORADO. 

PT AT H] V. 

PLATE V. 

Page. 

FIG. 1. PRODUCTUS NEBRASKENSIS 370 

A small, well-preserved, and very characteristic specimen belonging to this species. 

Dorsal view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2239). 

FIGS. 2 AND 2a. PRODUCTUS NEBRASKENSIS 370 

Another somewhat larger but imperfectly preserved example. 

Fig. 2. Ventral view. 

2a. Side view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2239). 

FIG. 3. PRODUCTUS sp. a 372 

A very imperfect ventral valve, which shows the irregular and interrupted character of 

the striae, and in some cases the scars left by the bases of small spines which have been 

broken off. 

Specimen seen from above. The restored outline is wholly hypothetical, as no specimen 

has been seen which was entire. 

Hermosa formation: Animas River, Durango quadrangle (station 2335). 

FIGS. 4 AND 4a. MARGINIFERA LASALLENSIS? 372 

The interior of a dorsal valve. 

Fig. 4. Posterior view. The figure represents the specimen as somewhat less symmetrical 

than it really is. 

4a. Side view of the same. 

Weber formation: Gulch near Double Top, Crested Butte quadrangle (station 2316) 

FIGS. 5 TO 5b. MARGINIFERA MURICATA 373 

A specimen of the coarsely ribbed variety, considerably exfoliated. 

Fig. 5. Specimen seen from above. 

5a. Side view. 

5b. Anterior view. 

Maroon formation: Cement Creek, Crested Butte quadrangle (station 2318). 

FIGS. 6 TO 6b. MARGINIFERA MURICATA 373 

Another example of the common type similar to the last. This is the specimen figured by 

White in 1877. The present figures are to a certain extent enlargements. 

Fig. 6. Specimens seen from above. 

6a. Side view. 

6b. Posterior view. 

Maroon formation: Near the head of Rock Creek, Elk Mountain region (station 2244). 

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PROFESSIONAL PAPER NO. 16 PL. V U. S. GEOLOGICAL SURVEY 

2a 2 

5b 

7 

6a 

� � � 9b 

� 

9c ga 9 9a 8 

11. 

10 oa 1 Cb 11 

rogi 131', 

12a 13a 13b 

13 12 

CARBONIFEROUS FOSSILS OF COLORADO. 

THE MERIDEN GRAVURE CO. 

PLAT IH VI. 

PLATE VI. 

Page 

FIGS. 1 TO lb. SPIRIFER BOONENSIS ? 381 

A young typical specimen belonging to this species. 

Fig. 1. Dorsal view. 

la. Ventral view. 

lb. Side view. 

Hermosa formation: Bear Creek, Durango quadrangle (station 2214). 

FIGS. 2 AND 2a. SPIRIFER BOONENSIS ? 381 

A mature but imperfect example of this species. This is a large shell, but represented 

by the figures which are somewhat enlarged as out of proportion with the preceding 

illustrations. 

Fig. 2. Dorsal view. 

2a. Side view. 

Hermosa formation: Bear Creek, Durango quadrangle (station 2214). 

FIG. 3. SPIRIFER BOONENSIS ? 381 

A ventral valve embedded in rock, which may perhaps belong to this species. It comes 

from a higher horizon in the Hermosa formation than the typical form shown by figs. 

1 and 2. 

Specimen seen from above. 


Hermosa formation: South fork of Hermosa Creek, Durango quadrangle (station 2201). 


FIGS. 4 AND 4a. SPIRIFER ROCKYMONTANUS 383 

A large specimen belonging to this species. 

Fig. 4. Dorsal view. 

4a. Side view. 

Weber shale: South of head of Empire Gulch, Leadville district (station 2267). 

FIGS. 5 AND 5a. SPIRIFER ROCKYMONTANUS 383 

A somewhat smaller specimen than the foregoing, in which the median furrow on the 

fold is larger and stronger than the lateral ones. 

Fig. 5. Dorsal view. 

5a. Side view. 

Weber shale: South of head of Empire Gulch, Leadville district (station 2267). 

FIGS. 6 AND 6a. SPIRIFER ROCKYMONTANUS 383 

A smaller but very characteristic individual, in which the fold is numerously plicated. 

Fig. 6. Dorsal view. 

6a. Side view. 

Hermosa formation: Near southern edge of Engineer Mountain quadrangle (station 2249). 

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1 a 

2 2 

3 

4 4a 

5 5a 

6 

8 

6a 

sa 

7 7a 

• 9a 

7C 

9h 

11 11 b lic Ica 10 

CARBONIFEROUS FOSSILS OF COLORADO. 

DESCRIPTION OF PLATE VI—CONTINUED. 501 

FIGS. 7 TO 7c. SPIRIFER ROCKYMONTANUS 

Page. 

383 

A specimen somewhat larger than the last, well preserved, and very characteristic. 

Fig. 7. Dorsal view. 

7a. Ventral view. 

7b. Side view. 

7c. Anterior view. In this figure the accidental varix of growth is too prominently 

represented. 

Weber formation (?): Horseshoe Mountain, Leadville district (station 2281). 

FIGS. 8 AND 8a. SQUAMULARIA PERPLEXA 392 

A rather large specimen belonging to this species. 

Fig. 8. Dorsal view. 

8a. Side view. 

Maroon formation: Punch Gulch, Crested Butte quadrangle (station 2291). 

FIGS. 9 TO 9b. SQUAMULARIA PERPLEXA 392 

A specimen smaller than the foregoing, but of more nearly the usual dimensions. 

Fig. 9. Ventral view. 

9a. Side view. 

9b. Dorsal view. 

Hermosa formation: Deadwood Gulch, Rico quadrangle (station 2224). 

FIGS. 10 AND 10a. SQUAMULARIA PERPLEXA 392 

A specimen somewhat larger than the last, but from the same locality. This example is 

not quite symmetrical in its growth. 

Fig. 10. Dorsal view. 

10a. Ventral view. 

Hermosa formation: Deadwood Gulch, Rico quadrangle (station 2224). 

FIGS. 11 TO 11C. SPIRIFERINA KENTUCKYENSIS 400 

A very small example which may belong to Shumard's species, but is possibly varietally 

different. 

Fig. 11. Dorsal view. 

11a. Anterior view. 

11b. Posterior view. 

11c.Side view. 

Hermosa formation: Rico quadrangle (station 2322). 

PLATE VII. 

PLATE VII. 

Page. 

FIGS. 1 TO lb. SEMINULA SUBTILITA 403 

A slightly unsymmetrical specimen from the lowest Upper Carboniferous horizon of the 

San Juan region. Represented by the figures as somewhat enlarged. 

Fig. 1. Dorsal view. 

la. Side view. 

lb. Anterior view. 

Hermosa formation: Bear Creek, Durango quadrangle (station 2214). 

FIGS. 2 AND 2a. SEMINULA SUBTILITA 403 

A small and presumably immature specimen from the same locality and horizon as the 

foregoing. 

Fig. 2. Dorsal view. 

2a. Front view. 

Hermosa formation: Bear Creek, Durango quadrangle (station 2214). 

FIGS. 3 AND 3a. SEMINULA SUBTILITA 403 

A large and characteristic specimen. 

Fig. 3. Dorsal view. 

3a. Side view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2239). 

FIG. 4. SEMINULA SUBTILITA 403 

A small and somewhat peculiar specimen belonging to this species. 

Dorsal view. 

Hermosa formation: Cliff south of Carson Creek, Durango quadrangle (station 2211). 

FIG. 5. SEMINULA SUBTILITA 403 

A slightly unsymmetrical specimen of smaller size than the original of fig. 3. 

Dorsal view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2239). 

FIG. 6. SEMINULA SUBTILITA 403. 

A specimen somewhat similar to the original of fig. 4, but a trifle larger. 

Dorsal view. 

Hermosa formation: Animas River, Durango quadrangle (station 2246). 

FIGS. 7 AND 7a. SEMINULA SUBTILITA 403 

In unusually gibbous specimen. 

Fig. 7. Dorsal view. 

7a. Side view. 

Hermosa formation: Lower end of Animas Park (station 2243). 

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CARBONIFEROUS FOSSILS OF COLORADO. 

DESCRIPTION OF PLATE VII—CONTINUED. 505 

Page. 

FIG. 8. SEMINULA SUBTILITA 403 

A specimen from the highest known Carboniferous horizon in the San Juan region somewhat distorted by pressure. 


Dorsal view. 


Rico formation: Scotch Creek, Rico quadrangle (station 2342). 


FIG. 9. SEMINULA SUBTILITA 403 

A small specimen of this species. 

Dorsal view. 

Hermosa formation: Hermosa Creek, Durango quadrangle (station 2239). 

FIG. 10. SEMINULA SUBTILITA 403 

A rotund specimen with fold and sinus less strongly marked than usual. 

Dorsal view. 

HermOsa formation: Sandstone Mountain, Rico quadrangle (station 2216). 

FIGS. 11 AND 11a. DIELASMA BOVIDENS 409 

An immature or not very characteristic representative of the species to which it is doubtfully referred. 

Fig. 11. Dorsal view. 

11a. Side view. 

Formation (?): Rock Creek, Elk Mountains. 

FIGS. 12 AND 12a. HUSTEDIA MORMONI 411 

A characteristic specimen. 

Fig. 12. Side view. 

12a. Ventral view. 


Maroon formation: Southeast of Italian Peak, Elk Mountain region (station 2280). 


FIG. 13. HUSTEDIA MORMONI 411 

A somewhat smaller specimen than the preceding, slightly distorted by pressure. 

Dorsal view. 

Maroon formation: Southeast of Italian Peak, Elk Mountain region (station 2280). 

FIGS. 14 TO 14b. PUGNAX UTAH 412 

A characteristic specimen. 

Fig. 14. Ventral view. 

14a. Anterior view. 

14b. Side view. 

Maroon formation: Southeast of Italian Peak, Elk Mountain region (station 2280). 

PLAT IH] T III. 

PLATE VIII. 

Page. 

FIG. 1. AVICULOPECTEN OCCIDENTALIS 414 

Internal cast of a right valve referred to this species. 

Specimen seen from above. 

Rico formation: Silver Creek, Rico quadrangle (station 2347). 

FIG. 2. AVICULOPECTEN sp. a 417 

Internal cast of a left valve, somewhat enlarged. 

Specimen seen from above. 

Hermosa formation: Ouray, Colo. (station 2194). 

FIG. 3. AVICULOPECTEN ? INTERLINEATUS 416 

A right valve belonging to this species. 

Specimen seen from above. 

Hermosa formation: Ouray, Colo. (station 2194). 

FIG. 4. PSEUDOMONOTIS KANSASENSIS 428 

A left valve of the type referred to this species. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 5. PSEUDOMONOTIS EQUISTRIATA 428 

A specimen representing the type referred to this species. 

Shell seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 6. MYALINA SUBQUADRATA? 424 

Left valve showing one variety of shape assumed by the fossils from Colorado. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 7. MYALINA SUBQUADRATA? 424 

A left valve of different shape from the preceding but associated with it. Possibly these 

two shells are not really conspecific. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 8. MYALINA WYOMINGENSIS 422 

A small left valve. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

FIG. 9. MYALINA WYOMINGENSIS 422 

A larger left valve of a somewhat different shape from the preceding. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

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11� 

7 

CARBONIFEROUS FOSSILS OF COLORADO. 

DESCRIPTION OF PLATE VIII—CONTINUED. 509 

Page. 

FIG. 10. MYALINA WYOMINGENSIS 422 

A large left valve whose shape resembles fig. 8. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

Fm. 11. MYALINA WYOMINGENSIS 422 

A large left valve of a still different shape. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

FIG. 12. MYALINA WYOMINGENSIS 422 

A small left valve somewhat similar to fig. 10. 

Specimen seen from above. 

Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

FIG. 13. MYALINA WYOMINGENSIS 422 

A specimen from Texas which seems to belong to this species, and which closely 

resembles the original of fig. 11. 

Right valve seen from above. 

Cisco division of the Upper Carboniferous: Graham, Young County, Tex. 

FIG. 14: MYALINA CUNEIFORMIS 420 

One of the type specimens of this species which I am enabled to figure through the 

courtesy of the geological department of the University of Chicago. 

A right valve seen from above. 

Hermosa formation (?) : Ouray, Colo. (Probably about the same locality and horizon as 

station 2195. ) 

FIG. 15. MYALINA CUNEIFORMIS 42Q 

Another type specimen, also loaned by the University of Chicago. 

Right valve; specimen seen from above. 

Hermosa formation (?) : Ouray, Colo. (Probably about the same locality and horizon as 

station 2195. ) 

Fm. 16. MYALINA CUNEIFORMIS 420 

Right valve from the Crested Butte region referred to Gurley's species. 

Specimen seen from above. 

Weber formation: Branch of Cement Creek, Crested Butte quadrangle (station 2314). 

FIG. 17. MYALINA CUNEIFORMIS 420 

Another specimen from the same locality as the preceding. The originals of both figures 

are very imperfect, and the shape represented is, to a considerable extent, a matter of 

restoration. 

Specimen seen from above. 

Weber formation: Branch of Cement Creek, Crested Butte quadrangle (station 2314). 

PLAT1-i: IX. 

 

 

PLATE IX. 


Page. 

FIG. 1. AVICULOPINNA NEBRASKENSIS J 435 

A rather small specimen in which both valves are preserved nearly jn place. 

Left valve seen from the side. The specimen is very imperfect, and restoration has been 

made as far as possible from growth lines. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 2. AVICULOPINNA NEBRASKENSIS 435 

Right valve of a much larger specimen than the preceding. Outline restored from the 

lines of growth, showing a shape somewhat different from the small specimen, the 

original of fig. 1. 


Side view. 


Rico formation: Scotch Creek, Rico quadrangle (station 2342) . 


FIG. S. MONOPTERIA ALATA 431 

The only specimen in the collection referred to this species. 

Shell seen from the side. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 4. ALLERISMA TERMINALE 437 

The type specimen upon which Hall's species was based. The obliquity of this specimen 

is clearly the result of compression, and the species is, I feel little doubt, the same 

which Meek and Hayden subsequently described as Allerisma subcuneatum. 

Left valve seen from the side. The papillose surface which this specimen retains is 

present on well-preserved examples of A. subcuneatum. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 5. ALLERISMA TERMINALE 437 

A right valve whose size is much smaller than is sometimes attained by this species. 

Side view. 

Rico formation: Scotch Creek, Rico quadrangle (station 2342). 

FIG. 6. ALLERISMA TERMINALE 437 

A small left valve whose size and proportions suggest that it may possibly be a distinct 

species or variety. 


Specimen seen from the side. 


Rico formation: Scotch Creek, Rico quadrangle (station 2342). 


FIG. 7. EDMONDIA GIBBOSA 4 447 

A right valve preserved as an internal cast, and not very perfect. 

Side view. 

Rico formation: Scotch Creek, Rico quadrangle (station 2341). 

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CARBONIFEROUS FOSSILS OF COLORADO.