DEPARTMENT OF THE INTERIOR

BULLETIN

UNITED STATES

GEOLOGICAL SURVEY

 No. 128

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1895
.eg
UNITED STATES GEOLOGICAL SUBVEY

CHARLES IX AVALCOTT, DIRECTOR

THE

BEAR RIVER FORMATION

ITS CHARACTERISTIC FAUNA

BY

OHAELES A.-WHITE

WASHINGTON

(5-OVERNMKNT PRINTING OFFICE)

CONTENTS.

Page.

Letter of transinittal........................................................ 9

Outline of this paper........................................................ 11

Historical statement........................................................ 13

Taxononiic position of the Bear River formation.......................'...... 20

Probable causes of former errors concerning taxonomic positiou.............. 24

Geographical extent of the formation.. ..........................\.......... 26

Description of species....................................................... 32

Biological discussion...... .................................................. 63

The Bear River fauna compared with other American fossil faunas ........... 70

The geographical and time range of Pyrgulifera............................. 84

5

ILLUSTRATIONS.

Paga

PLATE I. Sketch map showing areas occupied by Bear River formation...... 28

II. Ostreidte, MytilidiB, and Unionidte................................. 88

III. TJniomdse ......................................................... 90

IV. CyrenidsB and Corbulidro .......................................... 92

V. Auriculidss.............................i .......................... 94

VI. Limnieidse, Physidte, Neritidaj, and Helicidm 1..................... 96

VII. Melaniidte ........................................................ 98

VIII. Melaniidre ........................................................ 100

IX. MelaniidjB ........................................................ 102

X. Viviparidiie, RissoidiE, and Chara ....................I.............. 104

XI. Ostracoda ......................................................... 106

LETTER OF TRANSMITTAL.

WASHINGTON, D. C., March 20,1895.

SIR: I have the honor to transmit herewith the manuscript and. illustrations of a paper on the Bear Eiver formation and its characteristic, 

fauna.

Very respectfully, C. A. WHITE.

Hon. CHARLES D. WALCOTT, ;

Director of the United States Geological Survey.

OUTLINE OF THIS PAPER.

The object of this bulletin is the correction of an essential error 

which has long prevailed among geologists concerning the taxonotoic 

position of one of the North American Cretaceous formations; that 

is, its object is to present a summary of the facts which show the entire 

separateness from the Laramie formation of that series of nonmarine 

strata which has heretofore been known as the Bear Eiver Laramie, 

with which formation the Bear Eiver series of strata has long been 

confounded. To this end the Bear Eiver series is denned as a distinct 

formation, stratigraphically, geographically, and paleontologically, and 

its taxonomic position is stated in detail.

The subject is discussed historically, and with reference to the published results of the work of all the geologists who have written upon 

it. The work of correcting the error referred to and of properly characterizing the Bear Eiver formation, having been accomplished upon a 

paleontological basis, all the known fossils of this formation are herein 

described and figured. Comparisons are also made of its fauna with 

those of other nonmarine formations of this and other "continents, and 

relevant biological questions are discussed.

11

THE BEAR RIVER FORMATION AND ITS 

CHARACTERISTIC FAUNA.

BY CHARLES A. WHITE.

HISTORICAL STATEMENT.

When we consider the geographical extent of that great interior

region of North America which has been traversed and reported upon 

by geologists during the past forty years, the difficulty with which, 

former explorations and investigations were attended, the complex displacements which the strata of great areas in that region have suffered, 

and the newness of the geological problems which the early investigators encountered there, it is not strange that errors concerning the 

taxonomy of formations should occasionally have been made. Such 

errors have, however, been remarkably few, and most of these are justly 

excusable for the reasons just indicated.

One of the most important errors of the kind referred to is that which 

relates to the Bear River formation, the position of which, with relation 

to its associated formations, as has lately been shown, has been erroneously stated, or conceded without question, by every geologist who 

examined it during a period of twenty years immediately following its 

discovery. After that time some doubt was entertained as to the correctness of the currently accepted views of its relative position, the most 

definite of which were those published by myself and presently to be 

mentioned; but a detailed statement of what now appears to be a correct solution of the problem was first published by Mr. T. W. Stanton 

in 1892. 1

Because of the former general acceptance of the error referred to, it 

became incorporated with American geological literature, and was consequently accepted by the geologists of other parts of the world who 

have had occasion to discuss formations whose fossil faunas more or 

less completely resemble those of the Laramie and Bear River formations.

It being the principal object of this bulletin to state further what is 

now regarded as the true taxonornic position of the Bear Eiver formation, and to publish descriptions and figures of all the known fossil

1 Am. Jour. Sci., 3d ser., Vol. XLIII, pp. 98-115*

13
14 THE BEAK RIVER .FORMATION. [BOLL. 128.

forms which, characterize it, the following historical account of the 

growth and prevalence of opinion concerning it is essential to a proper 

understanding of the subject.

In the year 1859 Mr. Henry Engelmanu, geologist to the United States 

exploring expedition in charge of Captain Simpsori, discovered a series 

of strata constituting an important section at a locality in southwestern 

Wyoming, upon the bank, and near the mouth, of Sulphur Creek, a 

tributary of Bear River. All except one of the members of this section, exclusive of the greatly unconformable overlying Tertiary strata 

which occur in the same neighborhood, were recognized as of marine 

origin, and at least one of these was fou'nd to be coal-bearing. The nonmarine member of this section was found to contain abundant remains 

of a molluscan fauna which was quite distinct from any then known in 

North America. The fact was recognized, however, that this fauna contains specific forms which are similar to certain members of the fauna 

of the Lignite formation occurring in the French Department of the 

Mouths of the Rhone, which fauna Matheron had a few years previously 

published and referred to the Tertiary.

During the fifteen years following the year of their discovery those 

nonmarine strata in southwestern Wyoming were generally spoken of 

by geologists as the Bear River estuary beds, because it was generally 

believed that they were of estuarine origin. Later explorations, however, have revealed their presence at other localities in Wyoming, and 

at still others in the adjoining part of Idaho, which are so widely separated from one another as to show that the formation has greater geographical extent than may reasonably be expected of a true estuariue 

deposit. Furthermore, no kno\Arn fact, other than the evident brackishwater character of the branchiferoue members of its fauna, is suggestive of its estuarine origin.

During the time mentioned, also, no one seems to have expressed any

doubt of the Tertiary age of these strata, because their fossil fauna, 

although consisting of species which were then new to science, included 

types which were at that time regarded by all geologists as characteristic of the Tertiary. This view was supposed to be supported by the 

stratigraphical relation of these strata to the other members of the 

same section. That is, they were believed to constitute the latest member of the section in which they were found to occur, and to overlie 

unmistakably Cretaceous strata; but these facts will be more fully 

stated further on.

About the year 1876 those nonmarine strata which had been discovered at various and widely separated localities in the great interior 

region, and which are now properly referred to the Laramie^ began to 

be generally recognized as constituting one great formation, and the 

nonmarine strata of the Bear River Yalley district, herein specially 

referred to, came to be generally known as the Bear River Laramie. 

This name was applied to those strata because they were thought to
WHITE.] HISTORICAL STATEMENT. 15

have been contemporaneous''!n origin with the true Laramie, and to hold 

the same taxonomic position with relation to other formations, although 

it was well known that their inolluscan fauna is very different from that 

of the Laramie.

Soon after the recognition of the integrity of the great Laramie formation throughout a great geographical area, and the discovery in its 

strata of Mesozoic as well as Cenozoic types of fossils, differences of 

opinion arose among geologists as to whether it is properly assignable 

to the Tertiary or to the Cretaceous. These differences of opinion had 

reference also to the Bear Eiver formation, because it was then believed 

to be a part of the Laramie, but the question thus raised was one of 

geological age only, and did not extend to the subject of the relation 

of the Bear Eiver strata to other members of the section in which they 

were then known to occur.

The first published account of the Bear Eiver strata was given by

Messrs. F. B. Meek and Henry Engelmann, jointly, in I860; 1 and later 

in the same year Mr. Meek published descriptions of some of the fossils 

which characterize them.2 In these publications both authors unhesitatingly assigned the strata in question to the Eocene Tertiary.

No other publication concerning them seems to have appeared until 

1869, when Dr. F. V. Hayden inserted a paragraph containing a reference to them in one of his official reports upon another region.3 In this 

paragraph he expressed the opinion that they are of Tertiary age, and 

proposed to include in one and the same group the coal-bearing strata 

of the Sulphur Creek section, those near Evanston, and those at Coalville, Utah, giving that incongruous assemblage the name Bear Eiver 

group.4 .°

In 1870 Dr. Hayden published a short article containing a minute 

description, accompanied by figures, of the nonmarine strata originally 

discovered by Mr. Engelrnann, now called the Bear Eiver formation, in 

which publication he continued to assign them to the Tertiary.5

In the same volume, and immediately following the article of Dr. 

Hay den's just mentioned, Mr. Meek catalogued and described a number 

of new species of fossils, among which are some that were obtained 

from the Bear Eiver formation at and near the first discovered locality. These Mr. Meek assigned to the Tertiary without comment or 

qualification.

In his official report for 1870, Dr. Hayden republished the substance 

of his article in the Proceedings of the American Philosophical Society, 

just referred to, in which he again assigned the Bear Eiver formation 

to the Tertiary, stating its position to be at the top of the Sulphur

J Proc. Acad. Nat. Sci. Phila., Vol. XII, pp. 126-131.

'Ibid., pp. 308-315.

3 Prelim. Eept. TJ. S. Geol. Surv. Colorado and New Mexico, p. 91.

a The Bear Eiver group, a3 proposed by Dr. Hayden, embraced strata now known to belong to three 

separate formations; I retain the name for those only which pertain to one of them; that is, for those 

to whii/h the name "Bear lliver" has been most generally applied.

& Prpc. Am. Philos. Soc., Vol. XI, pp. 420-425, pi. xii
16 THE BEAR RIVER FORMATION. [BULL. 128.

Creek section. This volume of reports contains also a chapter by Mr. 

Meek 1 concerning the fossils which were collected from various formations by Dr. Hayden during the previous year, in which he assigned 

to the Tertiary all the species that were obtained from the Bear Eiver 

formation.

In Dr. Hayden's official report for 1871 Mr. Meek again catalogued 

the fossils from the Bear Eiver formation under the head of Tertiary;2 

and in the same year Mr. T. A. Conrad referred this formation to the 

Lower Eocene. He seems to have done this solely because of the 

type-character of its fauna,:J as he had never visited the region in 

which it occurs.

In 1872 Mr. Meek, in company with Dr. H. M. Bannister, visited 

Bear Eiver Valley, and specially studied the section which is exposed 

along Sulphur Creek, near its mouth, and which, as before mentioned, 

includes, besides a great thickness of marine strata, those of nonmarine origin which have just been mentioned as having been first discovered by Mr. Engelmaun. The results of this study were published 

by Mr. Meek in 1873,4 in connection with which publication he gave a 

figure of the section referred to, accompanied by a detailed description 

of its members. In this publication he continued to catalogue the fossils 

of the Bear Eiver formation under the head of Tertiary, but in his 

remarks upon these strata he for the lirst time expressed some doubt 

upon this point, and suggested that they might "belong to the Upper 

Cretaceous." -It is evident, however, that he was still of the opinion 

that their position is at the summit of the Sulphur Creek section, and, 

therefore, above all the undisputed Cretaceous strata which constitute 

its other members.

The character of his discussions concerning the paleontology of the 

Bear Eiver formation in this and in previous publications shows that

the doubt referred to was not entertained on account of any evidence

afforded by the fossils obtained from those strata, all of which he 

regarded as of Tertiary types, but he seems to have been influenced by 

the fact that dinosaurian remains had then for the first time been discovered in strata, now known to belong to the Larainie formation 

proper, which until then had been by all geologists regarded as of Tertiary age, as also had been the Bear Eiver formation.

Upon the geological sheet of the general atlas of the United States 

Geological Exploration of the Fortieth Parallel, which shows the district traversed by Bear Eiver, the strata which are now known to be 

properly referable to the Bear Eiver formation are indicated as belonging to the Laramie, and the areas which they occupy are colored upon 

that sheet in the same manner as are the true Laramie areas. This 

atlas was published in 1876, and the geology of the Bear Eiver district

1 Fourth Ann. Eept. TJ. S. Geol. and Geog. Surv. Terr., pp. 149-153.

2 Fifth Aim. Kept. TJ. S. Geol. and Geog. Surv. Terr., p. 376.

3 Am. Jour. Sci., 3d ser., Vol. I, pp. 381-383.

4 Sixth Ann. Eept. U. S. Geol. and Geog. Surv. Terr., pp. 451-454.
WHITE.] HISTORICAL STATEMENT. 17

represented by it is understood to be the joint work of Messrs. Clarence 

Kiiig and S. F. Enimons.

In his final report, also, Mr. King assigned the Bear River strata in 

question to the Laramie; 1 and he correlated those of the originally 

discovered locality, near the mouth of Sulphur Creek, with the uppermost beds of the true Laramie at Black Buttes. Mr, Emmons, also, 

in his final report, assigned the same strata to the Laramie.2

At this time the belief already mentioned had become general; that 

is, that the Bear River formation, notwithstanding the material difference of its fossil fauna from that of the great formation which then 

began to be known by the name of Laramie, was contemporaneous with 

the latter, and that both hold the same relation to overlying and underlying formations. For these and other reasons the Bear River formation began, as already stated, to be known as the Bear River Laramie, 

the evident object of that special designation being only to indicate a

recognition of the faunal difference between it and the great Laramie 

formation.

The final report of Mr. Erigelniann was not published until 1876, 3 

sixteen years after he had submitted it to Captain Sirnpson, and the 

same length of time after he had published his original report. At the 

time of the later publication discussion as to the true geological age 

of the Laramie formation, including the Bear River strata, had become 

somewhat prevalent, some contending for their Tertiary and some for 

their Cretaceous age. Apparently influenced by these discussions, 

Mr. Engelmann, in revising his final report, expressed the belief that the 

Bear. River strata are of Cretaceous age, although in his original article, published jointly with Mr. Meek (loc. cit.), the opinion that they are 

of Tertiary age is plainly stated, and in the later publication he cites no 

new fact that might have caused a change of opinion.

Mr. Meek's final report to Captain Simp son on the fossils of the Bear 

River formation is contained in the same volume with that of Mr. 

Engelmann (op. cit.), and in his discussion of the"m he too was disposed 

to assign them to the Cretaceous, but he nowhere indicates a belief that 

the taxonomic position of the Bear River formation is not the same as 

that of the true Laramie. In his last published writing 4 he expressed 

the same opinion which he had formerly held, namely, that the Bear 

River strata are equivalent to the Laramie. In this last work of his he 

also described and figured several of the characteristic species of the 

Bear River formation.

It was in 1876, also, that Maj. J. W. Powell, who had in the previous 

year personally examined the geology of the district embracing the 

lower portion of Sulphur Creek Valley and the adjacent portion of Bear

1 U. S. Geol. Explor. Fortieth Par., Vol. I, p. 373 and map iii, 1878. 

* Ibid., Vol. II, p. 327,1877.

3 See^impson's Report on the Great Basin of Utah, pp. 247-336,1876.

4 TJ. S. Geol. Explor. Fortieth Par'.. Vol. IV, p. 163,1877.

Bull. 128 -2
18 THE BEAR EIVER FORMATION. [BULL. 128.

Eiver Valley, published his views of the Bear River formation. 1 He 

accepted the conclusions which Mr. Meek had reached concerning the 

order of superposition of the members of the Sulphur Creek section, and 

published a verbatim copy of Meek's description of it. In this publication Major Powell treated the Bear Eiver strata as equivalent to his 

Point of Eocks group, which is equivalent to the Laramie, both of which 

he assigned to the Cretaceous; but he placed the Bear Eiver strata at 

the summit of the Sulphur Creek section, as all the other geologists 

had previously done. In the same volume I described several of the 

characteristic molluscan species of the Bear Eiver formation.2

In certain of my writings which were published in 1877 and 1878 I 

assigned the strata which I now designate as the Bear Eiver formation, 

as well as the coal-bearing beds near Evanston, which are also found 

in Bear Eiver Valley, to the great Laramie formation. 3 Both of these 

assignments, however, having been erroneous, a part of the conclusions 

which were reached in their discussion were necessarily erroneous also.

The results of some extended Held observations made by myself in 

Colorado, Utah, and Wyoming were published in 1879.4 In the part of 

that publication which relates to the geology of Bear Eiver Valley I 

expressed the views which I then held concerning the relation to the 

Laramie formation of the Bear Eiver strata and of the Evanston coalbearing beds. These views were similar to those expressed in my publications of the two previous years, except that in the later publication 

1 suggested that the Bear Eiver strata are probably older than the Laramie ; but I based this opinion upon the fact that the characteristic types 

of the Bear Eiver fauna are much less like those of any Tertiary, or.iiow 

living North American, fauna than are those of the Laramie. In 1883 5 

I repeated the expression of this opinion as to the greater age of the 

Bear Eiver strata, but my views were not in either case fully stated.

In 1879 Dr. A, C, Peale twice published results of his examination of

the geology of a portion of western Wyoming,6 in which publications he 

showed that the Bear l^iver formation has a greater geographical extent 

than was before known. He found these strata occupying a belt of 

country of varying width, lying partly in Wyoming and partly in Idaho, 

and extending northward from the place of their original discovery to 

the forty-third parallel of north latitude, a distance of about 100 miles. 

Besides this, he reported the existence of a narrower and shorter belt 

lying parallel with the other a few miles farther eastward.

Most of the strata throughout the district examined by Dr. Peale, as 

well as those of the first discovered locality, have been much displaced by orogenic movements, in consequence of which the structural

1 Geology of the TJinta Mountains, p. 158. 

"Ibid., pp- 118,122,123.

3 Bull. TJ. S. Geol. and Geog. Surv. Terr., Vol. Ill, pp. 607-014. Idem, Arol. IV, pp. 707-724. 

4 Eleventh Ann. Kept. U. S. Geol. and Gcog. Surv. Terr., pp. 161-172. 

6 Third Ann. Kept. TJ. S. Geol. Surv., p. 430.

6 Eleventh Ann. Kept. TJ. S. Geol. and Geog. Surv. Terr., pp. 511-644; and map accompanying the 

Twelfth Ann. Kept. Alao, Bull. TJ. S. Geol. and Geog. fcurv. Terr., Vol. V, pp. 195-200.
WHITE.] HISTORICAL STATEMENT. 19

geology there is often found to be obscure. Doubtless because of this 

obscurity he failed to see any reason to oppose the then prevalent 

opinion that the Bear Kiver formation is referable to theLararaie epoch, 

and reported that formation as overlying a series of strata which he 

assigned to the Cretaceous, but-he admitted that he found no paleoutological evidence of their Cretaceous age.

In 1877 and 1878 Prof. Orestes St. John examined the geology of a 

portion of western Wyoming and the adjacent part of Idaho, his district lying immediately north of the one examined by Dr. Peale, but 

the results of his work were not published until 1882. 1 In this report 

he shows that the Bear River strata, which, following the then prevalent custom, he assigned to the Laramie, occupy considerable areas in 

the district examined by him, one of them being a northward continuation of the principal belt reported on by Dr. Peale. These areas show 

a northward continuation of the Bear Siver formation of about 40

miles more than was shown by the results of Dr. Peale's observations, 

and they seem to mark the extreme northern limit of the formation.

The structural geology of Professor St. John's district is even more 

obscure than is that of Dr. Peale's, but he seems to have had little 

difficulty in recognizing the separate identity of the formations which 

exist there. The difficulty of determining their taxonomy, however, 

was increased over that of other portions of the Bear Kiver district by 

the apparent absence of any marine Cretaceous strata associated with 

the Bear Kiver strata which he found there.

From 1881 to 1885, inclusive, I published, several articles in which reference is made to certain of the characteristic fossils of the Bear RiVer 

formation.2 In all of those publications, with the partial exception of 

my review of the nonmarine fossil inollusca, already mentioned, the 

fossils of that formation are so referred to as to convey the idea of its 

equivalency to the Laramie.

During the preparation of my review of the North American Cretaceous formations, which was published in 1891,3 1 found it necessary 

to discuss the Laramie formation in that connection. While reviewing 

the literature and paleontology of that portion of my subject and con-

' Twelfth Ann. Eept. TJ. S. Geol. and Geog. Surv. Terr., Part I, pp. 175-269 and map.

'The following statement of the titles and places of publication of these articles, in addition to 

similar references in preceding footnotes, is given for the purpose of making bibliographical reference 

to the subject of this bulletin as complete as practicable:

Tanganyika'shells. Nature, Vol. XXV, pp. 101,102.

On certain conditions attending the geological descent of some North American types of fresh-water 

gill-bearing niollusks. Am. Jour. Sci., Vol. XXIII, pp. 382-385.

Newmolluscan forms from the Laramie and Green Kiver groups, with discussion of some associated 

forms hitherto known. Proc. U. S. National Museum, Vol. V, pp. 94-99, pis. 3 and 4.

A review of the nonmanno fossil mollusca of North America. Third Ann. Eept. U. S. Geol. Surv., 

pp. 411-550, pis. 1-32.

Contributions to invertebrate paleontology, No. 4; Fossils of the Laramie group. Twelfth Ann. Eept. 

"U. S. Geol. and Geog. Surv. Terr., Part I, pp. 49-103, pis. 20-30.

The genus Pyrgulifera Meek and its associates and congeners. Am. Jour. Sci., Vol. XXIX, pp. 

277-280. .

s Bull. U. S. Geol. Surv. No. 82.
20 THE BEAR. RIVER FORMATION. [BULL. 128.

sidering the statements there made in connection with the results of 

my personal visits to Bear Kiver Valley, I became more than ever convinced that the Bear River formation is older than the Laramie, and 

that it would somewhere be found overlain by Cretaceous strata. This 

opinion I expressed on page 153 of the work referred to.

THE TAXONOMIC POSITION OF THE BEAR RIVER FORMATION.

The considerations mentioned in the last one of the preceding paragraphs seemed to demand an immediate and determined attempt to 

solve the question of the relative position of the Bear River strata. 

'Therefore, in the field season of 1891 Mr. Stanton accompanied me to 

the Bear River Valley, and together we reviewed its geology up to the 

point where my previous investigations had ceased. It being then 

impracticable for me to continue field work, I left him to pursue the 

investigations alone, the results of which he embodied in the article 

already referred to, 1 and his principal conclusions are also stated on 

the following pages. This article was accompanied by one prepared 

by myself, which contained a statement of the principal facts mentioned 

on the preceding pages.2

The results of Mr. Stanton's investigations show that the Bear River 

formation, instead of occupying a position at the top of the North 

American Upper Cretaceous series, as it was formerly supposed to do, 

and as does the Laramie formation, lies beneath the greater part, if 

not the whole, of that series. That is, he has determined its position 

as beneath the Colorado formation and above that series of Jurassic 

strata which occurs within a large part of the interior region of North 

America and which are generally regarded as of Upper Jurassic age. 

The following table, copied from Mr. Stanton's article before referred 

to, represents the section as determined by him in the Bear River district. It shows not only the position of each of its members with

relation to one another, but also their relation to the complete Upper 

Cretaceous section of the great Rocky Mountain region:

1 Am. Jour. Sci., Vol. XLIII, pp. 98-115, February, 1892. 

'Ibid., pp. 91-97.
WHITE.] TAXONOMIC POSITION.

Mr. Stanton's Sear River general suction.

21

Tertiary.

Cretaceous.

Jurassic.

Wasatch.

Laramie.

Montana,

Colorado.

Bear River.

Dakota?

Beleinnites 

beds.

Conglomerates, coarse sandstones, and shales, 

with coal at the base.

Wanting, or included in the above.

Not positively identified.

Shales and coal-bearing sandstones. Thickness not less than 2,500 feet.

Very fossiliferous, argillaceous, and calcareous 

shale, alternating with thin beds of sandstone.

Conglomerates and coarse sandstones. Thickness of last two 2,500 to 4,000 feet.

Thin-bedded, sandstones and sandy shales.

The following table shows the equivalency of the members of Meek and 

Hayclen's Upper Missouri Cretaceous section with those which are now 

generally recognized as constituting the Upper Cretaceous series as it 

occurs in the great Rocky Mountain region and in the Green Eiver basin, 

in Wyoming. The names of these members are mentioned in the foregoing table by Mr. Stantou, bub the comparison is made in the following 

table for the conveuience of those who are more familiar with the older 

than with the later names:

%

Nomenclature of Upper Cretaceous series.

Meek and Hayden's TTppe;r M'issoiiri section.

Judith Eiver beds (Laramie).

Fox Hills group. 

Fort Pierre group.

Niobrara group. 

Fort Ben ton group. '

Dakota group.

Jurassic.

Upper Cretaceous section of Rocky Mountain 

 region, etc.

Laramie.

Montana.

Colorado.

Dakota.

Jurassic.
22 c THE BEAR RIVER FORMATION. [BOLL. 128.

Notwithstanding the evident accuracy of Mr. Stanton's determinations as to the relative position of each of the members of the Bear Eiver 

section, there are still some unsolved questions relating- to the exact 

taxonomic position of the Bear Kiver formation proper and of the unfossiliferous conglomerates and sandstones which underlie it and overlie 

the Belemnite-bearing Jurassic beds; that is, the following questions 

may justly be propounded: Is the Bear Eiver formation of later, contemporaneous, or earlier origin than the Dakota formation ? If of earlier 

origin, is it of Upper Cretaceous, Lower Cretaceous, or Jurassic age*? 

Are the conglomerates and sandstones just mentioned of Jurassic age; 

are-they referable to the Dakota formation, or do they represent some 

formation of intervening agel Discussions of these questions must, of 

course, have reference to both stratigraphy and paleontology.

Unfortunately, stratigraphical indications upon the subject are confined to the order of superposition of the members of the Bear River 

section as it has been determined by Mr. Stanton, because all of them, 

including the unquestioned Jurassic, are apparently strictly conformable with one another, and there is therefore no physical indication of 

a time hiatus between any of them.

The apparently strict conformity of the conglomerates and sandstones with the Belemnite-bearing, and therefore marine, Jurassic 

strata, which they overlie, offers at least a suggestion that the former 

may represent the noumarine upper division; that is, the "Atlantosaurus beds" of the Jurassic as it is developed in Colorado and Wyoming. 

This fact as to conformity, however, offers little or no more than a suggestion, because the Dakota formation is equally conformable with the 

Jurassic wherever contact between them has been observed. Therefore all known indications are quite as much in favor of Mr. Stantou's 

suggestion of the Dakota age of those sandstones and conglomerates as 

they are of their Jurassic age. His opinion that they are probably 

equivalent to the Dakota, also accords with that of the members of the 

Fortieth Parallel Survey. No direct paleontological aid is available for 

the solution of this question, because those conglomerates and sandstones have not yet furnished any fossils.

While the Bear Eiver formation is an abundantly fossiliferous one, 

paleontological indications of its geological age are indefinite for several 

reasons, among which are the following: No other fossils have been 

found in it than those which are described and figured in this bulletin, 

except some imprints of angiosperrnous leaves, which, although identifiable as such, are too fragmentary for satisfactory illustration. No 

vertebrate fossils are known to exist in. any of its strata, although some 

scattered cycloid fish scales have been found in immediately overlying 

shales. Its invertebrate fauna, as a whole, is very different from any 

other known North American fauna, and, besides this, such of its 

faunal types as are like those which occur in other North American 

strata have had a long geological time range. For example, Jurassic
WHITE.] TAXONOMIC POSITION. 23

nonmarine inolluscan remains have been discovered in Colorado and 

Wyoming 1 which belong to types qnite as modern iu character as are 

any of those of the Bear River fauna, and not an inconsiderable part of 

the types of both the faunas referred to are found among now living mollusca. Therefore, so far as the Bear River fauna is now known, and 

when it is considered with reference to other North American faunas, 

it seems to afford very little, if any, intrinsic paleontological evidence 

as to whether it is of Cretaceous or Jurassic age.

At two localities, however, Mr. Stanton found the few fragmentary 

imprints of aiigiosperinous leaves jfcist referred to, which, although too 

imperfect for specific designation, are plainly of the general character 

of such plant remains as are common in Upper Cretaceous strata, and 

they are unlike any that are known in either the LoAver Cretaceous or 

the Jurassic strata of North America. This, so far as it goes, may be 

regarded as an intrinsic paleontological indication of the Upper CretaceoUS age of the Bear River formation, and allies it with the Colorado 

and Montana formations. Furthermore, it is shown on following pages 

that several of the molluscan members of the Bear River fauna are so 

closely similar to forms which occur in the Colorado formation as to 

suggest their specific identity. This still further indicates the affinity 

of the Bear River formation with the overlying members of the Upper 

Cretaceous series.

On the other hand, wherever the Dakota and Colorado formations 

have been found in contact, their strata are not only conformable, but 

in certain districts their paleontological relation 2 to each other has been 

found to be quite as intimate as is that of the Bear River formation 

with the Colorado, which has just been mentioned. Such conditions 

seem to preclude the probability of the existence of an intermediate 

series of strata in either case.

This apparent intimacy of relationship of the Colorado formation 

with both the Dakota and Bear River is suggestive of the contemporaneity of origin of the two latter formations; but we are here met 

with the fact that the faunal characteristics of the two formations are 

very different from each other, 11 although both are of nonmarine origin. 

Therefore, to assume the contemporaneity of origin of the Bear River 

and Dakota formations is to assume that their discordant aquatic faunas 

were developed independently and in .separate hydrographic basins. 

This is not improbable, but we have yet no proof of it.

On the other hand, there seems to be no discovered direct proof that 

the nonmarine Bear River strata do not represent the early part of the 

Colorado epoch, which is represented by marine strata only in those

'See Bull. U. S.'Geol. Surv. No. 29, 1886.

'- So far as the Dakota formation is concerned, it is the marine portion only that is here referred to, 

such, for example, as those found in Kansas and Texas. For remarks upon these marine Dakota 

strata and their fossils see Proc. TJ. S. Nat. Museum, Vol. XVII, pp. 130-138,1894.

3It is true that a species of Pyrgulifera has lately been discovered iu Dakota strata, as will be more 

fully 7iiontioned on a following page, but it is the difference between the'Dakota and Bear Eiver faunas, 

each ns a whole, that is here referred to.
24 THE BEAR RIVER FORMATION. [nou,128.

districts where the Dakota formation is distinctly recognizable at its 

base. An indirect suggestion that the Bear River formation is separate 

from the Colorado is, however, furnished by the section in "Weber Valley, 

about 30 miles southwestward from the Sulphur Creek section. The 

Jurassic is distinctly represented in Weber Valley, and the Colorado 

formation is there apparently complete, even to its base. Between 

these two formations there are two series of strata, in neither of which 

have,any fossils been found. The lower one of these formations Mr. 

Stanton regards as equivalent to the conglomerates and sandstones of 

his Bear Eiver general section, as shown on page 21, and as possibly 

equivalent to the Dakota formation. The upper one he thinks is probably equivalent to the Bear Eiver formation. 1 If these suggestions 

shall prove to be correct, they will indicate that the deposition of the 

Bear Eiver formation was already completed at the beginning of the 

Colorado epoch, and the fact will also indicate a greater southern extension of the Bear Eiver formation than is now certainly known.

The questions propounded on page 22 are therefore still unanswered 

or answered only in part; but in view of the facts which I have stated 

and of Mr. Stanton's determinations, I do not now hesitate to assign 

the Bear Eiver formation to the Upper Cretaceous, and to designate its 

position as at or near the base of that series. This assignment also 

accords with the reputed age of a formation in Hungary 2 whose fauna 

is more nearly like that of the Bear Eiver formation than any other 

known.

PROBABLE CAUSES OF FORMER ERRORS CONCERNING TAXONOMIC POSITION, ETC.

Because the views concerning the position of the Bear Eiver formation with relation to other formations which have been controverted 

upon the .preceding pages have been held by so large a number of 

observers, including some of the ablest of North American geologists,

it is proper to offer some explanatory, if not apologetic, suggestions as 

to the causes of the origin and long continuance of those erroneous 

views. These causes evidently relate in part to the great disturbance 

which the Bear Eiver strata have suffered and to other physical conditions, and in part to erroneous preconceived paleoutological opinions.

For a long time after the discovery by Mr. Engelmannof the section 

of strata near the mouth of Sulphur Creek, strata equivalent to those 

of that part of it which is now known as the Bear Eiver formation were 

not known to occur elsewhere, and if was upon the examination of this 

section only that the views referred to were originally formed. All the 

strata of the Sulphur Creek section are greatly disturbed, a large part

'Bull. TJ. S. Geol. Surv. No. 106. p. 46,1893.

'See Tausch (Leopold von). TJeber die Fauna der niclit-marineii Ablagerungen der oberen Kreide 

des Csingerthales l>ei Ajka im Bakony, TIngarn. Abliandl. Iv.-k. geol. Keichsanstalt, Bund XII, 

No. 1, Wion, 1886.

See also Oppenhehn (Paul). TJeber einige Brack wasser- und Binnen-Molluskeu aiis der Kreide und 

dem EociiuTJugarns. Zeitschr. Deutach. geol. Geaell., Band XLIV, Heft 4. Berlin, 1892.
WHITE.] PROBABLE CAUSES OF FORMER ERRORS. 25

of them standing vertical or nearly so, and others are inclined at various 

angles. Besides this, they are now known to be traversed by faults 

which are so much obscured that their character or even their existence was hardly demonstrable before the facts brought out by Mr. 

Stanton were applied to the study of the strata of that district. Furthermore, the Sulphur Creek section is exposed only within a small 

neighborhood, where it is closely surrounded by a broad expanse of 

unconformably overlying Tertiary strata. These Tertiary strata so completely cover the strata which are or originally were continuous with 

those of the section as to make it impracticable to trace any of the 

latter continuously more than a short distance.

It. is only in the district which extends northward from Sulphur Creek 

that any other than the original discoveries of liear Eiver strata have 

been certainly made. When this district began to be examined the 

work was necessarily done in a desultory manner, because the geolo 

gists who did the work were attached to topographical surveying' parties, to whose movements theirs were subordinated. The difficulties of 

travel were also great, because pack and riding animals were the only 

means for conveying persons and for transporting supplies. In addition to the disadvantages just mentioned, these geologists were necessarily influenced in their judgment by the published views of those 

who had previously reported upon the Sulphur Creek section. They 

found the Bear Eiver and associated formations everywhere nearly or 

quite as much disturbed as they are at the Sulphur Creek locality, and 

in their necessarily hasty examinations they did not discover the error 

that had been made there.

Besides the difficulties imposed by the conditions just mentioned, 

one of the most important elements in the solution of the question 

involved seems to be entirely absent from the whole district in which 

the Bear Eiver formation occurs. That is, the reports which have 

been made by various geologists upon western Wyoming and adjoining 

parts of Utah and Idaho indicate that no true Laramie strata exist in 

any part of the district where those of the Bear Eiver formation occur. 

Therefore, those observers were all the more ready to accept the Bear 

Eiver strata as representing the Laramie. Further confusion was 

caused by erroneous identification of some of the marine Cretaceous 

strata of the Sulphur Creek section. That is, in the region surrounding the Bear Eiver district the rnolluscan faunas of the equivalents of 

the Colorado and Montana formations, respectively, present so many 

differences from those faunas as they are known farther eastward that 

the strata of the Sulphur Creek section which are now known to belong 

to the Colorado formation were believed to belong to the later Montana 

formation.

Although .the greatly disturbed aud obscured condition in which the 

strata of the Bear Eiver aud its associated formations were found was 

the primary cause of the erroneous conclusion as to their order of super-
26 THE BEAR EIVER FORMATION. [BULL. 128.

position which was reached by the geologists who first investigated 

them, it can not be denied that the then prevalent paleontological views 

are largely responsible for it. That is, none of these investigators seem 

to have doubted that such types as those which are included in the 

Bea.r Eiver fauna are characteristic of, and peculiar to, the Tertiary. The 

fact also that the Bear River strata are of noninariue origin evidently 

had some influence in favor of assigning them to the Tertiary, because 

at that time little was known of the existence m North America of nonmarine strata earlier than those of Tertiary age. Moreover, they found 

the Bear River strata occupying a position at one end of the exposure 

of a series of strata which contain unquestionable marine Cretaceous 

fossils, 1 and believing these nonmarine strata to be of Tertiary age, they 

necessarily assumed that they overlie their associates of marine origin.

In the light of all the facts noAv known, it seems strange that the 

wide difference between the fauna of the Bear River strata and that of 

the Lararnie did not cause more distrust of the idea which was then 

entertained that they were of contemporaneous origin, especially because 

it was this discordance of faunal characteristics which finally suggested 

to me the investigations that have resulted in assigning the Bear River 

formation to a much earlier epoch than that of the Laramie.2 Still, the 

full extent of the fauual difference referred to was not known to the 

first investigators of those formations, and the difference which was 

then known to exist was, they thought, probably due"to the division of 

the waters of the Laramie epoch either into different faunal areas or 

into different hydrographic basins. It is also just to add that while the 

principal error which has been discussed on the preceding pages was 

largely due to erroneous paleontological views, it is equally true that 

without the aid of paleontology that error could not have been refuted.

Finally, in putting forth this explanation of what is regarded as the 

true taxonomic position of the Bear River formation^ it is proper to say 

that the conclusion reached is largely based upon the knowledge of 

facts and principles bearing both directly and indirectly upon this subject which has accumulated since the work of the earlier investigators 

was accomplished. Besides this, the district occupied by the Bear 

River formation, wjiicli was a Avilderness when they began their investigations, is now traversed by two railroads, and all parts of it are readily 

accessible for study.

GEOGRAPHICAL EXTENT OF THE FORMATION.

Having discussed the separate identity and stratigraphical relations 

of the Bear River formation, it remains to consider the geographical 

area which it occupies, or within which its strata are known to occur.

'See Mr. Mcek's figure of the Sulphur Creek section, Ann. Kept. TL S. Geol. and Geog. Surv. Terr, for 

1872, p. 451. /Vlso Mr. Stanton's reproduction of the same, Am. Jour. Sci., Vol. XLIII, p. 102, Feb., 1892.

"See Third Ann. Kept. U. S. Gool. Surv., p. 430,1883; Eleventh Anu. Eept, U. S. Geol. and Geog. Surv. 

Terr, for 1877, p. 2-17,1879; and Bull. U. S. Geol. Surv. No. 82, p. 153,1891.
WHITE.] GEOGRAPHICAL EXTENT. 27

Our knowledge of the true limits of this area has hitherto been, and to 

some extent still is,indefinite or uncertain for three reasons: First, 

those strata Avere not until lately fully differentiated from the Larainie; 

second, among the fossils which have from time to time been obtained 

in various districts other than that in which the Bear Eiver fauna was 

originally discovered are some which so closely simulate certain Bear 

Bi ver species that they have been erroneously identified with them, thus 

giving origin to erroneous reports concerning the geographical extent 

of the Bear Eiver formation; third, all the smaller, but nevertheless 

important, details of the geology of the great region in which the Bear 

Eiver strata are now known to occur have not yet been fully worked 

out. The first reason has already been discussed, and it is desirable to 

consider the other two.

The former belief, which has just been indicated, and which was also 

mentioned by me in a previous publication, 1 that Bear Eiver strata exist 

in certain districts of eastern and southern Utah, never resulted in the

accumulation of such facts as would warrant a definite indication of 

the outlines of the areas in which they were supposed to occur. This 

belief was based upon the assumed identity of certain species of fossil 

shells which from time to time reached the hands of paleontologists 

from various persons who had visited the districts referred to. A part 

of these reputed identifications were wholly erroneous, as has been 

shown by the discovery of essential differences of structure; but in 

other cases, even when the essential structure of the whole shell is 

known, the identity is so apparently real that it is difficult or impracticable to prove it otherwise.

The cases of assumed identification which are now certainly known 

to be erroneous were due to reliance upon the external form of the shells 

examined, and those cases, concerning which there is still some doubt, 

were due to a want of strong specific features in the shells of. all the 

members of the genus to which they belong. It will be sufficient for 

my present purpose to mention one case each of these two kinds.

A case of total error of identification is that of a gasteropod species, 

of which many specimens were received from different localities in 

Utah. These shells in outward aspect resemble typical forms of Pyrgulifera humerosa even more closely than do some of its unquestionable 

varieties, and upon this external character alone the identification was 

based, the interior features not having been then ascertained. Subsequently, however, these shells were found to possess folds upon the 

coluinella like those which characterize Adinetopsis. This character, of course, not only requires their reference to another species, 

another genus, and another family, but it indicates a marine instead of 

a uonmarine origin for the fauna to which it belongs.

1 Am. Jour. Sc.i., 3d ser., Vol. X.LI.TI, p. 97, February, 1892.
28 THE BEAR RIVER FORMATION. [BULL. 128.

A case of still questionable identification is that of a species of Corbicula or Cyreria which, although its essential details of structure are 

known, it is difficult to describe as different from Corbicula durJceei. 

The doubt here implied whether the shell in question is a Corbicula or 

a Cyrena is due to the absence or obliteration of transverse stride upon 

the lateral teeth of the specimens received. The discrepancy in this 

case was thought to have been due to obliteration, because those striae 

are often obliterated, and are never so conspicuous upon the shells of 

Corbicula durlteei as they usually are upon North American species of 

Corbicula.

These two species, Pyrgulifera Jmmerosa and Corbicula durJceei, are 

two of the most conspicuous and characteristic of the members of the 

Bear River fauna, and the forms just mentioned, which so closely simulate them, are now known to .have been obtained from the Colorado 

formation and to be members of its marine fauna. Moreover, in the 

districts Avhere they were found later investigations have failed to 

reveal the presence of any strata which con tain unmistakable members 

of the Bear River fauna. 1

In connection with the description on following pages of the species 

which constitute the Bear River fauna, some suggestions are made 

as to the possibility that certain of them may have survived into the 

Colorado epoch, and that in such cases the apparent identity may be 

real, the Corbiculoid species just referred to being one of them. The 

forms in question, however, being such as present comparatively few 

salient specific characteristics, and also such as occur with little variation in formations of different ages, the evidence they furnish is not 

entirely satisfactory.

In connection with the subject of assumed identification of. Bear 

River species at localities far distant from the district in which they 

wore originally discovered, it is desirable to refer to the i'auna of the

Dunvegan series of strata Avhich occur in Canada, especially those of 

the valley of Peace River. Through the kindness of Mr. J. F. Whit- 

"eaves, paleontologist to the Geological Survey of Canada, I have been 

able to compare a small suite of those fossils with the large collections 

of the Bear River fauna now in the United States National Museum. 

The species Avhich most resemble members of the Bear River fauna are 

one each of the following genera: Corbula, Corbicula, Modiola (Brachydontes), and Ostrea.

Some of these Dunvegan specimens of Ostrea are exceedingly like 

some of those which are found in the Bear River strata. They are also 

much like some of those found in various other formations, as well as 

some living forms. The Modiola is very like the M. multilinigera of 

Meek, and consequently very like the form in the Bear River formation

1 It should bo obse.rved that these errors are the result of museum study O7ily of the fossils iu question. The same investigators who made them c.ould not have doue so if they had then had the opportunity of field work iu connection with their paleonlological study.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. I

Scale of Miles

SKETCH MAP SHOWING AREAS OCCUPIED BY BEAR RIVER FORMATION.
WHITE.] GEOGRAPHICAL EXTENT. 29

to which on a following page I have proposed the conventional name 

of M. pealei.

The Dunvegan Corbicula is quite variable in shape and marginal 

outline, but some of the specimens are so nearly like those of C. durlceei 

that they would hardly be regarded as specifically different if found 

associated with genuine specimens of that species in Bear Biver strata. 

Other specimens are so closely like those forms of Corbicula or Cyrena 

which have been mentioned as occurring in the Colorado formation 

that one can not say how they differ specifically.

Of all the species obtained from .the Duuvegan strata the one which 

most deserves attention in this connection is the Corbula. This is so 

exceedingly like C.pyriformis that if found associated with unquestionable members of the Bear River fauna one would hardly be justified in 

separating it. Still, in the absence of such association, and in view of 

the general want of salient features in the shells of Corbula by which

the species may be discriminated, I think one is justified in rejecting 

this Dun vegan form as a specific representative of C. pyriformis.

The other species of Dunvegan fossils which were sent me for examination by Mr. Whiteaves belong to the genera Goniobasis, JSeritina, 

Unio, Corbula?, and Mactra?, but none of them is identifiable with any 

member of the Bear Biver fauna. I therefore regard the Dunvegan 

fauna, although allied to that of the Bear Biver formation, as in no 

such sense identical with it as would imply a true geological equivalency of the formations respectively containing them. Besides this, the 

Canadian geologists are disposed to regard the Dunvegan and Belly 

Biver series of strata as belonging to one and the same horizon, and 

the position to which they assign the latter is somewhat later than that 

which has now been determined for the Bear Biver formation.

It is evident from the foregoing explanations that the Bear Biver 

fauna is not represented as a fauna beyond the limits of the district 

which is indicated by the accompanying sketch map (PI. I), and it is 

probable that no really specific member of it exists beyond those limits.

For the third of the reasons mentioned on page 27 why our knowledge of the area occupied by the Bear River formation has been imperfect, it has not been found practicable to prepare for this bulletin 

a satisfactory detailed geological map of the district in question. 

The accompanying sketch map, however, embraces the extreme limits 

of the district in which the Bear Biver strata have been certainly 

recognized, audits shaded portions indicate the areas within which they 

have be<tfi observed or confidently assumed to exist.

These areas are in part copied from map 2 of the.Twelfth Annual 

Beport United States Geological and Geographical Survey of the Territories, which is based upon the reports of Dr. A. C. Peale and Prof. O. 

St. John, and in part from maps 2 and 3 of the atlas of the United 

States Geological Exploration of the Fortieth Parallel. The outlines 

of the areas which upon the copied portions of the two Fortieth
30 THE BEAK RIVER FORMATION. [BULL. 128.

Parallel maps are designated Larainie are somewhat modified and 

restricted upon the sketch copy here presented, to make them accord 

with observations made by Mr. Stanton and myself. Those which are 

copied from the map by Dr. Peale and Professor St. John have been 

largely verified and identified by Mr. Stanton as Bear Biver areas up 

to 20 miles north of Cokeville. Northward from that point all.the 

areas which are designated Laraniie upon the last-named map are 

those which are confidently assumed to be occupied by Bear Eiver 

strata, although the fact of that identity has not yet been verified by 

collections of fossils from all of them.

The shape, position, and limitation of those shaded areas bear no 

necessary relation to the limits of the Bear Eiver formation as it was 

originally deposited. Those original limits have not yet been even 

approximately determined, and it is not likely that they will ever be 

much more definitely known. Their present limitation, as it is shown 

by their respective outlines upon the map (PL I), is due to causes which 

have transpired since their deposition took place. That is, it has been 

accomplished by the great disturbance which the strata of the whole 

district have suffered, by the outflow of great masses of volcanic rock, 

and by the extensive erosion and denudation which followed those 

events. These areas therefore represent only minor portions of the 

Bear Eiver formation as it was originally deposited.

While it is evident that this formation as it was originally deposited 

occupied a larger total area than that which would be indicated by a 

line merely circumscribing tl'at group of comparatively small irregular 

areas, we have now no satisfactory evidence that its original limits 

extended much, if any, beyond the limits of the district which is 

represented by the accompanying map, and which, for convenience in 

these discussions, I designate the Bear Eiver district. It is true that

a part of the region surrounding1 the district is occupied by Tertiary 

sedimentary deposits, and a smaller part by post-Cretaceous lava outflows, either of which would have covered from view any Bear Eiver 

strata which may have existed there. Still, there are some other 

localities in the surrounding region at which equivalents of either a 

part or all of the marine strata of the Sulphur Greek section exist, but 

no equivalents of the Bear Eiver strata have been paleontologically 

recognized in association with them, and in most of these cases there is 

no physical indication of their existence.

One of the most important of these localities is in the valley of 

Weber Eiver, about 30 miles southwestward from the mouth of Sulphur 

Creek. Here, as has already been stated on page 24, the marine members of the Sulphur Creek section are well represented, and among 

them are certain strata which possibly represent the Bear Eiver formation. This question, however, can not be decided without the discovery 

of its characteristic fossils, and its southern limit may therefore be 

provisionally supposed to lie somewhere between Sulphur Creek and 

Weber Valley,,
WHITE.] GEOGEAPHICAL EXTENT. 31

Another important locality at which equivalents of the marine 

members of the Sulphur Creek section occur is at Flaming Gorge, 

Green. River, and in the district extending east and west from that 

river along the north flank of the Uinta Mountains. This district 

embraces the boundary line between Colorado and Wyoming, and is 

from 50 to 70 miles eastward from the Sulphur Creek section. In this 

district the full series of strata from the Jurassic to the Laramie formation, inclusive, are exposed in the same order and in the same general 

condition that they are found to present throughout the Rocky Mountain region, but no trace of the Bear River formation is found among 

them.

The other exposures of the equivalents of the marine members of the 

Sulphur Creek section within the region surrounding the Bear River 

district are few in number, and less complete and important than are

those of the two districts just referred tp. Still, they are characteristic, but at none of them has any trace of the Bear River faun a been 

discovered, and no strata have there been recognized that may reasonably be referred to the Bear River formation.

It has already been shown that the supposed identity with members 

of the Bear River fauna of certain fossil forms found in eastern and 

southern Utah is fallacious. Furthermore, Mr. Stantou, who has carefully examined the geology of those regions for that purpose, was 

unable to find there any trace of the Bear River formation, even when 

representatives of the other members of the Sulphur Creek section were 

present.

In consideration of all the facts presented -in the foregoing paragraphs, it seems quite unlikely that the Bear River formation ever 

occupied a much, if any, larger area than is represented by the extreme 

limits of the accompanying sketch map. This geographical isolation ot 

the Bear River formation is still further emphasized by the comparison 

of its fauna with other North American fossil faunas which is presented 

on following pages. Its taxonomic isolation is ak-io apparent because 

of its absence from all known sections of strata which occur beyond 

the geographical limits which have been designated.
DESCRIPTION OF SPECIES.

MOLIAJSC.A.

OQNOHIFERA.

Family OSTREID/E.

Genus OSTEEA Linnaeus.

OSTREA HAYDENI n. S.

Plate II, figs. 1,2.

Oatrea ? White, Eleventh Ann. Kept. U. S. Geol. and Goog. Snrv. Terr., p. 242.

Among the collections which from time to time have been obtained 

from, the Bear Eiver formation are numerous examples of a small oyster 

belonging to the typical section of the genus Ostrea. These are so 

closely like specimens which have been found in the Colorado, Montana, and Laramie formations, respectively, that it is impracticable to 

describe them in terms which would not apply nearly or quite as well

to those forms. Their resemblance to certain specimens of the young 

of the living Ostrea virginica is also quite as close as it is to the fossil 

forms just mentioned. For these reasons the x>ropriety of giving a 

separate specific name to this fossil form might well be questioned, but 

I have decided to do so because it will add to the convenience of discussing the formation in which the shells occur and the fauna as a 

whole which characterizes it. The name which I have chosen is given 

in memory of Dr. F. V. Hayden, whose collections contained the first 

discovered specimens.

Although several others of the various species which, constitute the 

fauna of the Bear Eiver formation, especially those whose congeners 

are brackish-water denizens, are found in immediate association with 

this little oyster, it is usually confined to separate thin layers, which in 

some cases it almost entirely constitutes. Its geographical distribution, however, has been found to be nearly or quite coextensive with 

the present known limits of the formation. 

32
WHITE.] DESCRIPTION OF SPECIES. 33

The small size of all the discovered specimens, the largest not much 

exceeding 50ram in length, gives one the impression that they are all 

immature, but the average size is about the same at all the localities 

at which they have been discovered, some of Avhich are more than 100 

miles apart. The shells are therefore regarded as mature notwithstanding their small size.

The localities at which this form has been found to be more abundant 

than at any others are 20 miles north of Ookeville, 7 miles north of 

Evanston, and near the mouth of Sulphur Creek.

Family MYTILID^B. 

Genus MODIOLA Lamarck.

MODIOLA PEALEI n. s, 

Plate II, fig. 3.

Compare Modiola (Brachydontes) multilinigera Meek, 1873, Ann. Eept. U. S. Geol. and

Geog. Surv. Terr! Tor 1872, p. 492. 

Compare Volsella (Bracliydoriies) multilinigera White, 1880, Twelfth Ann. Eept. U. S.

Geol. and Geog. Surv. Terr. N p. 18, pi. ii, fig. 3.

Among the collections which have been obtained from the Bear River 

formation are numerous fragments of a Modiola which in all observable characteristics closely resembles the M. multilinigera of Meek, the 

original specimens of which came from the Colorado formation. Indeed 

this Bear River form so closely resembles the one just mentioned that' 

it would not be. unreasonable to refer them to one and the same species 

if it were certainly known that the deposition of the Bear River forma-, 

tion was, as it seems to have been, followed immediately by that of the, 

Colorado formation. Because of this doubt and of the imperfection of 

the Bear River specimens, which is so great as to make it impracticable 

to clearly diagnose them specifically, I prefer to give them a separate 

name, as I have done in the case of the oyster with which they are 

associated. For this purpose I have selected the name of Dr. A; G. 

Peale, because he was among th'e first geologists to examine the Bear 

River formation after its discovery by Mr. Bngelmann, and his collections contained the.first observed specimens of this form.

Fig. 3 on PI. II is of a young and imperfect example, somewhat 

enlarged. The forementioned characteristics of the shell have been 

observed mostly by means of fragments of larger examples.

Mr. Stanton obtained imperfect specimens of this form at several 

localities, and its geographical distribution is apparently the same as 

that of Ostrea liaydeni. 

Bull. 128 3
34 THE BEAR RIVER FORMATION. [BULL. 128.

Family UNIONID^B.'

Genus UNTO Retzius.

UNIO BELLIPLICATUS Meek.

Plate II, figs. 4, 5, 6.

Unio bellipUcattis Meek, 1870, Proc. Am. Philos. Soc., Vol. XI, p. 439.

Unio (Lexopleurus) belliplicatus Meek, 1871, Ann. Rept. U. S. Geol. aud Geog. Surv.

Terr, for 1870, p. 294. 

Unio lelfyilicatus Meek, 1873, Ann. Rept. U. S. Geol. and Geog. Surv. Terr, for' 1872,

p. 478. 

Unio Ielliplicatu8 Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV, p. 165, pi.

16, fig. 4,4a. ' . . 

Unio belliplicatus White, 1879, Ann. Rept. U. S. Geol. and Geog. Surv. Terr, for 1877, p.

242. 

UnioMliplicatvs White, 1883, Third Ann. Rept. U. S. Geol. Surv. p. 430, pi. 6, figs. 1,2,3.

1 The following is Mr. Meek's description of this form, copied from 

Vol. IV of the reports of the United States Geological Exploration of 

the Fortieth Parallel, pp. 165-166:

Shell attaining a medium size, transversely subovate, the widest part being a little 

in advance of the middle, moderately convex, generally less than twice .as long as 

high; anterior margin short, rather regularly rounded; posterior margin obliquely 

subtruncated, with a more or less convex outline, most prominent below, where it 

is obtusely subangular or abruptly rounded into the base; dorsal outline nearly 

straight, or more or less arched; base broad semiovate, being most prominent in 

advance of the middle, in large specimens generally a little sinuous posteriorly; 

beaks much depressed, or scarcely rising above the cardinal margin, oblique, and 

placed near the anterior end, not eroded; hinge moderately long, with cardinal and 

lateral teeth, so far as known, much as in U. vetustus. Surface ornamented by a 

series of very regular, distinctly defined, and generally simple plications, which 

commence very small, and closely approximated along the dorsal margin just before 

the beaks, and after slight curves radiate and descend obliquely toward the posterior 

basal margin, increasing in breadth and becoming more obtuse as they descend and 

diverge, and at last in large specimens becoming obsolete before reaching the margins; while another more or less similar series of plications sometimes originates along 

the cardinal margins behind the beaks, and descends obliquely backward and downward, so as to connect with those of the first-mentioned series along the posterior 

umbonal slopes at very acute angles, somewhat like we see on species of Goniomya. 

Marks of growth moderately distinct, becoming sometimes stronger or subinibricating near the margins.

The dimensions of this species were given by Mr. Meek iii inches, the 

approximate metric equivalents of which are: Length, 70mm ; height, 

38mm ; thickness, 20mm. Later collections show that the species is very 

variable not only in size but in proportional dimensions, some being 

much more convex aud some much shorter than others. This is in 

part shown by the figures on PI. II; but other specimens in the collections, which, however, are too imperfect for satisfactory illustration, 

show the great variations just mentioned.

The plications also vary considerably in character, being much 

stronger upon the more robust specimens than upon others. In such
WHITE.] DESCRIPTION OF SPECIES. 35

cases they often occupy a larger part of the anterior surface of the shell 

than is usual in other cases. It was upon the character of these plication s that Mr. Meek at one time proposed to separate this species as the 

typical representative of a subgenus under the name of Loxopleurus, 

but this proposition he afterwards abandoned. The peculiar character 

and direction of these plications constitute a striking feature of this 

species, but they really consist of a blending of concentric and radiating 

folds, which, when occurring separately, constitute ordinary features 

of ornamentation among the Uniones.

This species has a wide geographical distribution in the Bear Eiver 

formation ; but it has been found more abundant at the locality near 

the mouth of Sulphur Creek than at any others.

UNIO VETUSTUS Meek.

Plate III, figs. 1, 2, 3, 4.

Unio vetustus Meek, 1860, Proc. Acad. Nat. Sci. Phila., Vol. VIII, p. 117.

Unio vetustus Meek, 1876, Simpson's Kept. Great Basin of Utah, p. 359, pi. v, figs. 12,

a, b. 

Unio vetustm Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV, p. 164, pi.

16, figs. 5, a, b, c. 

Unio vetustus White, 1883, Third Ann. Kept. U. S. Geol. Surv., p. 430, pi. 7, figs. 1-4.

The following is Mr. Meek's description of this species, as given in 

Vol. IY of the reports of the United States Geological, Exploration of 

the Fortieth Parallel (loc. cit.):

Shell of about medium size, transversely subovate or subelliptic, the widest part 

being anteriorly, though young examples are narrower, with dorsal and ventral margins more nearly parallel, rather thin and moderately convex, about twice as long 

as high; base forming a long semi-elliptic or serai-ovate curve in adult shells, but 

usually straighter in the young; posterior margin rather narrowly rounded below in 

large specimens and obliquely truncated in small examples; dorsal margin nearly 

straight, excepting in large shells, where it is more arched; anterior margin short 

and rounded; beaks depressed, not eroded, placed near the anterior, very neatly 

ornamented with small, perfectly regular, concentric ridges and furrows, that generally end abruptly behind at a small, oblique, linear, posterior umbonal ridge 

extending backward and downward, while midway between this and the cardinal margin, there is a second similar ridge; other portions of the surface merely 

marked with lines of growth, which sometimes assume a subinibricating appearance 

near the free margins. Hinge of moderate length, with two cardinal teeth in the 

left valve, the posterior one being larger than the other; lateral teeth long and 

nearly straight (cardinal teeth of right valve unknown); scars of anterior muscles 

deep and irregularly pitted.

The dimensions of this species, like those of the preceding one, were 

given by Mr. Meek in inches, the approximate metric equivalents of 

which are: Length, 100inm ; height, 53mm ; thickness, 27mm. , This species, 

however, is very variable in its proportional dimensions as well as in 

marginal outline, These differences are in part shown by the figures 

on PL III,
36 THE BEAR RIVER FORMATION. [BULL. 128.

The concentric ridges upon the umbones, which are mentioned by Mr. 

Meek, are in some cases quite as distinct as they are upon U. belliplicatus before, they diverge as radiating folds. Indeed the surface markings of very young specimens of both species were evidently often 

closely similar.

Both Mr. Meek and myself at one time thought this form to be identical with one which, occurs in the upper part of the Laramie, and with 

another which occurs in the lower part of the Wasatch formation. 

These were U. prisons Meek and Hayden, from near Fort Union, J3. 

Dak., and U. mendax and U. rectoides White, from the base of the 

Wasatch formation in Utah. It is true that these forms are closely 

similar t6 U. vetustus when the great variation of the latter is taken 

into consideration, but there are recognizable differences between them. 

Besides this, U. vetustus is now known to belong to a much older stratigraphical horizon than do the other forms mentioned. It is therefore 

regarded as inexpedient to give them all the same name, even if it were 

still more difficult to discriminate between them.

The geographical distribution of this species within the Bear Eiver 

formation is the same as that of U. belliplicatus, and they are usually 

found in intimate association. Both have, been found more abundant 

at the Sulphur Creek locality than elsewhere.

Family CYRENID^E.

Genus CORBICULA Megerle.

CORBICULA DURKEEI Meek.

Plate IV, figs. 1, 2, 3, 4.

Cyrena (Corbicula?) durkeei Meek, 1870, Proc. Am. Philos. Soc. Phila., Vol. XI, p. 431. 

QorMcula (Veloritina) durkeei Meek, 1872, Ann. Rept. U. S. Geol. and Geog. Surv. Terr.

for 1870, p. 294. 

Corbicula ( Feloritina) durkeei Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol.

IV, p. 167, pi. 16, figs. 6, a, b, c, d, o, f, g. 

Corbicula (Veloritina) durkeei White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 437,

pi. 8, figs. 8, 9,10,11.

The most complete diagnosis of this species given by Mr. Meek occurs 

in Vol. IV of the reports of the United States Geological Exploration 

of the Fortieth Parallel, pp. 167-168, which is as follows:

Shell attaining a large size, thick, trigonoid-subcordato, gibbous, oblique, with 

length exceeding somewhat the height, most convex a little in advance of and above 

the middle, and cuneate postero-ventrally; posterior dorsal slope long, straight, 

or slightly convex in outline from the umbones to the angular or subangular posterior basal extremity; basal margin sem-iovate in outline, being most prominent 

anteriorly; anterior margin short, descending very abruptly from the beaks, with a 

slightly concave outline above, and rounding regularly iuto the base below; beaks 

elevated, gibbous, obliquely incurved, contiguous, and placed about halfway between 

the middle and the anterior ead, or sometimes nearly over the latter; posterior 

umbonal slopes prominently rounded, with posterior dorsal margins inflected or 

incurved, so as to form a profound, broad concavity, or sulcus, along their entire 

length, as the two valves are seen united; lunule in most cases deep, but generally
WHITE.] DESCRIPTION OP SPECIES. 37

without well-defined margins; ligament short, narrow, and so deeply seated in the 

broad dorsal concavity as not to be visible in the side view when the valves are 

united; surface only showing moderately distinct lines of growth; hinge strong; 

cardinal teeth oblique, excepting the anterior one, which ranges nearly vertically; 

lateral teeth elongated, and only very minutely striated, or very nearly smooth, the 

posterior one of the left valve being sometimes mainly formed by the beveling of 

the inflected edge of the valve instead of standing out at right angles from an erect 

margin; pallial lines with a short, very shallow sinus, immediately under the ovate, 

shallow, and oblique scar of the posterior abductor muscle; anterior muscular impression deeper, slightly smaller than the other, and ranging nearly vertically.

As was his custom, Mr. Meek gave the dimensions of this shell in 

inches, the approximate equivalents of which are: Length, 47mm ; height, 

39mm ; thickness, 28mm.

This species, as was noticed by Mr. Meek in connection with its original publication, and as is shown by the figures on PL IV, is very variable in its proportions and marginal outline. Indeed the extremes 

which in this respect are observable among a large series of specimens 

are so great that if no intermediate forms were discovered no one would 

hesitate to assign them to different species. The recognition of this 

extreme interspecific variation led me to assign to this species some 

examples of a closely similar shell which were found near the north 

fork of Virgin River in southern Utah. 1 It has since been ascertained, 

however, that those specimens came from the lower part of the Colorado formation, and that its faunal associates are of distinctly marine 

character.

There is another form, possibly belonging to the same southern Utah 

species, which was obtained from, the Colorado formation in the valley 

of Sulphur Creek near where the strata of the Bear River formation 

are exposed, and where it was associated with a fully marine fossil 

fauna. To this* form I first gave the name of Cyrena (Veloritina) 

erecta, but afterwards referred it to the Cyrena securis of Meek.2

The form obtained from southern Utah was referred to C. durlceei, 

not:only because its own characteristics are similar to those of that 

species, but because some of its associates so closely simulate other 

Bear River species that I then thought them identical, although they 

are now known to be different. The form discovered in the valley of 

Sulphur Creek, while I recognized its close similarity to Corbicula 

durkeei, I regarded as belonging to a different genus and species. I 

accordingly referred it to the marine genus Cyrena, because I could 

discover no striation of the lateral teeth, \vhich character is absent in 

Cyrena and present in all known North American fossil forms of Corbicula, and because the specimens were found as members of a distinctly 

marine fauna, while the associates of Corbicula durlceei are fresh-water 

and brackish-water forms.

Still, the striation of the lateral teeth of Corbicula durJceei is never 

strongly marked, and it has not been fully demonstrated that those of

1 U. S. Oeog. Surv. West of the One Hundredth Merid., Vol. IV, p. 207, pi. xxi, fig. 13,1877. 

2 Eleveuth Ann. Kept. TJ. S. Geol. aiid Geog. Surv. Terr., p. 281), pi. 3, figs. 2, a, b, c, 1879.
38 THE BEAR EIVER FORMATION. [BULL. 128.

Cyrena securis were not at least indistinctly striate. These facts lead 

to a suggestion similar to that which was made in the case of Modiola 

pealei on a preceding page. That is, they make it reasonable to inquire 

whether the forms found in the Colorado formation in southern Utah 

and in Sulphur Creek Valley in southwestern Wyoming may not have 

been genetically derived from Corbicula durTceei by survival from the 

brackish waters in which the Bear River formation was deposited into 

the marine waters of the Colorado formation. This suggestion of 

course implies that there may have been continuous sedimentation in 

the production of the Bear Eiver and Colorado formations. This condition has not yet been demonstrated, but it is known that the Colorado 

formation rests immediately upon the Bear Eiver strata, and no facts 

are yet known that forbid the supposition that sedimentation was, at 

least in part, continuous from the former to the latter formation.

Mr. Meek proposed the subgeneric name Veloritiua 1 for this shell, 

and this designation has been generally used by American authors. It 

will be seen, however, that the characters which he designates as subgeneric are the unusual proportional height of the shell and the depression of the dorsal margin. The interspecific variations which have 

been mentioned, and which are in part shown by the figures on PL IV, 

are such as to include forms in which these characters are entirely 

absent. This fact renders of doubtful value any subgeneric designation 

as regards this species.

It is worthy of remark that although Corbicula durlteei is so abundant in the Bear Eiver formation it is the only representative of the 

family Cyrenidae that has yet been found in its strata.

This species is one of the most abundant and characteristic of the 

members of the Bear Eiver fauna. It is particularly plentiful 7 miles 

north of Evauston, and also near the mouth of Sulphur Creek, but its 

geographical range is throughout the whole extent of the formation so

far as its strata have been examined.

Family OORBULID^E.

Genus COEBULA Bruguiere.

CORBULA PYRIFORMIS Meek.

Plate IV, figs. 5, 6, 7, 8, 9.

Corbula (Potamomya) pyriformis Meek, 1860, Proc. Acad. Nat. Sci., Vol. XII, p. 312. 

Corlula (Anisorliynclws) pyriformis Meek, 1872, Ann. Rept. U. S. Geol. andGeog. Surv.

Terr, for 1871, p. 292. 

Corbula (Anisorliynchus) pyriformis Meek, 1876, Simpsori's Rept. Great Basin of Utah,

p. 361, pi. 5, figs. 9, 10. 

Corbula (Anisorhynchus) pyriformis Meek, 1877, U. S. Geol. Explor. Fortieth Parallel,

Vol. IV, p. 170, pi. 17, figs. 2, a, h, c, d. 

Corbula pynformis White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 441, pi. 8, figs.

12-16.

1 For its diagnosis see U. S. Geol. and Geog. Surv. Terr., Vol., IX, p. 161, 1876.
WHITE.] DESCRIPTION OF SPECIES. 39

Mr. Meek's most complete description and discussion of this form is 

contained in Vol. IT.of the reports of the United States Geological 

Exploration of the Fortieth Parallel, pages 170 to 174. The following 

is a copy of his description:

Shell attaining a large size; rather thick, oval-subpyriform, nearly equivalve, very 

gibbous in the central and anterior regions, and much more compressed, narrowed, 

and produced posteriorly; beaks elevated, nearly equal, incurved, and placed more> 

or less in advance of the middle; anterior sidfe generally truncated obliquely forward above, from the beaks to near the middle, thence rounding abruptly to the 

base; posterior side much attenuated, and usually slightly truncated at the immediate 

extremity; dorsal margin generally much concave in outline behind the beaks, and 

provided with a well-defined marginal carina, extending in each valve from the beaks 

nearly to the posterior extremity, and between these carinae with a deeply excaArated 

lanceolate escutcheon; basal margin deeply rounded in the central and anterior 

region, and more or less sinuous in outline behind the middle; lunule deeply an.d 

rather largely impressed, without being always distinctly denned, though it is sometimes margined by a subangular ridge on each side. Surface ornamented with concentric ridges and-furrows, most regularly and strongly defined on the umbonal region, 

and gradually becoming more irregular and less distinct toward the basal margin, or 

in some cases entirely fading away, so as to leave only the lines of growth over the 

whole exterior. Hinge with the tooth of the right valve rather thick, prominent, 

subtrigonal, striated, and a little curved upward; cartilage-pit deep and trigonal; 

hinge of left valve with pit and cartilage-process, presenting the usual characters; 

pallial line with apparently a small shallow sinus; posterior muscular impression 

very faintly marked; anterior muscular impression generally well defined, subovate, 

attenuated, and curving backward above where they connect with the small scars of 

the pedal muscles.

This species varies considerably in form as well as in surface-markings. In some 

'specimens the whole surface is nearly smooth or only marked with obscure lines of 

growth, while in others the most gibbous part of the valves and the umbones are 

marked with very regular, distinct, concentric ridges and furrows. In still others 

the ridges and furrows are exceedingly irregular and very strongly marked. There 

are also more or less marked differences in the elevation of the beaks, the convexity 

of the anterior region, and the proportional length of the attenuated posterior 

extremity; yet all of these varieties blend together by such slight shades of difference that it seems impossible to find constant characters by which they can be 

separated specifically.

This species is an unusually large one for the genus Oorbula, besides 

which it is unusually obese. The length of one of the larger examples 

is 40mm ; height, 29mm j and thickness, 26mm.

Mr. Meek regarded this form as representing a subgenus under Corbula, and he adopted for it Conrad's MS. name, Anisorhynchus; l but, 

as Mr. Meek has himself shown, it possesses no features which properly separate it from true Corbula. It is a conspicuous member of the 

Bear River fauna, not only because of its large size, bat because of its 

abundance. Its geographical range is throughout the whole known 

extent of the formation, but it is most abundant at the locality 7 miles 

north of Evanston and at tbe one near the mouth of Sulphur Creek.

1 For Mr. Meek's diagnosis of Anisorhynchus, see U. S. Geol. aud Geog. Surv. Terr., Vol. IX, p. 241, 

1876.
40 THE BEAR RIVER FORMATION. [nuLL.128. 

CORBULA ENGELMANNI Meek.

Plate IV, figs. 10,11.

Corbula (Potamomya?) enf/elmanni Meek, 1860, Proc. Acad. Nat. Sci. Phila., Vol. XII,

p. 213. 

Corbula engelmanni Meek, 1876, Shnpson's Rept. Great Basin of Utah, p. 362, pi. 5,

figs. 13, a, b. . . 

Corbula (Anisorhynchus?) engelmanni Meek, 1877, U. S. Geol. Explor. Fortieth Parallel,

Vol. IV, p. 174, pi. 17, figs. 1, la.

All the larger collections of fossils that have been obtained from the 

Bear Eiver formation contain a greater or less number of specimens of 

the form to which Mr. Meek gave the name Corbula engelmanni. Ever 

after its first publication, however, he felt much doubt whether it was 

really distinct from G. pyriformis, and I also have been disposed to regard 

this form as the young of that species, but there are certain facts which 

still suggest the separate specific identity of G. engelmanni,'a>mong which 

are the following: First, the outline of the form to which the name 

C. engelmanni has been applied rarely if ever fully agrees with that of 

G. pyriformis of similar size, as it is indicated by the lines of growth on 

adult specimens of the latter; second, the strong convexity of the valves 

and the incurving of the beaks which are characteristic of C. pyriformis are not observable on any of the shells which have been referred to 

G. engelmanni; third, no forms have been discovered which in size 

and shape are intermediate between G. engelmanni and - C. pyriformis; 

fourth, the form G. engelmanni bears, a much closer resemblance to 

the G. nematophora Meek of the Colorado formation than it does to 

C. pyriformis.

The last-named fact suggests a genetic survival of the form G. engelmanni from the waters in which the Bear Eiver formation was deposited

into those of the Colorado formation, the case thus suggested being 

similar to those which have been suggested on preceding pages for Ostrea 

haydeni, Modiola pealei, and Gorbicula durheei.

 This form generally occupies different layers from those in which 

G. pyriformis prevails, and is frequently found in the same layers with 

Unio belliplicatus and U. vetustus. It is widely distributed in the Bear 

Eiver formation, and is somewhat plentiful at some of the localities, but 

it is never so abundant as is C. pyriformis.

Genus COEBULOMYA Nyst.

CORBULOMYA TAUSCHII n. S.

' Plate IV, figs. 12,13. '

Shell of moderate size, generally suboval, but sometimes subtrihedral 

in marginal outline; front somewhat narrowly rounded; base broadly 

convex; posterior narrowly rounded but not attenuated nor much 

extended; dorsal border slopin g with little con vexity from the uinbones to
WHITE.] DESCRIPTION OF SPECIES. 41

the posterior margin; anterior obliquely truncate; lunule rather large, 

moderately deep, and margined by a more or less distinct angulation. 

Surface marked by somewhat distinct lines of growth and by small, 

irregular, concentric folds. Posterior tooth of the left valve strong, 

anterior one small, cartilage pit large. Teeth of the right valve 

unknown. . ' . . Length of the largest valve in the collection, which is suboval in 

marginal outline, 29uim ; height, 20lllln . Length of another example, 

which is subtrihedral in marginal outline, 22min ; height, 17mm . The 

latter example is not referred to this species with entire confidence.

If only the hinge . structure of this shell is considered, it is difficult 

to say how it differs from typical Corbula; but I refer it to Corbulomya 

because of its generally suboval marginal outline, its thin test, and its 

want of the posterior extension or attenuation and of the postero-dorsal 

caring, which usually characterize true Corbula.

The specific name is given in honor of Dr. Leopold von Tauscb, of 

Vienna, who has done so much to make known the Hungarian fossil 

fauna, which in many respects so much resembles that of the Bear 

Eiver formation.

This species was discovered at only one locality, which is near Sage 

Station, in Twin Creek Valley, Wyoming; but it was found associated 

with several characteristic species of the Bear Eiver fauna.

GASTEROPODA. 

Family

Genus AURICULA Lamarck.

AURICULA NEUMAYRI n. s.

Plate V, fig. 1.

Shell small, subfusiforin ; spire, short; volutions about six in number, 

those of the spire convex, the last one large, elongate, and subterete; 

suture moderately impressed; columella bearing three folds, all of 

which are prominent, but the middle one* strongest and most nearly 

transverse in direction, the anterior one smallest; outer lip plain, moderately thickened in the adult, but sharp in immature examples. Aperture comparatively narrow and narrowly rounded in front, but ending 

anteriorly in a sharp angle. Surface marked by lines of growth which 

are often strong and somewhat irregular.

Length, I2mm ; diameter, 5mm.

In its generic characteristics this form so nearly agrees with typical 

species of Auricula that, although its antiquity is suggestive of a 

generic difference in the animal, I do not see how the shell can with 

propriety be referred to any other genus. It is also an interesting fact 

that the family AuriculidiB is so fully represented in this formation as 

it is shown to be by the presence of this and the four following species.
42 THE BEAR RIVER FORMATION. [BULL. 128.

The specific name is given in memory of the late Prof. M. Eeumayr, 

of Vienna, whose important works upon the nonmariiie fossil fauna of 

Austria-Hungary are well known.

The geographical range of this species was doubtless coextensive 

with other members of the fauna, but the only examples yet known 

are those which Mr. Stantou discovered at the locality 20 miles north 

of Cokeville, Wyo.

Genus MELAMPUS Montfort.

MELAMPUS CLARKII u. s.

Plate V, figs. 2, 3.

Shell small, subovateor subfusiform; spire short, its apex prominent; 

volutions five or six in number, those of the spire narrow and convex, 

that of the apex deflected or reversed; the body volution comprising 

much the greater part of the bulk of the shell, broadest at its distal 

part and tapering toward its proximal end; suture impressed and 

accompanied at its proximal side by a slightly impressed revolving line; 

.aperture narrow, rounded in front and sharply angular-behind; outer 

lip thin; inner lip more or less calloused and bearing three teeth; the 

upper tooth prominent, narrow, and inclining a little forward; middle 

tooth also prominent and inclining a little backward; the anterior tooth 

small and situated near the front of the aperture. Surface smooth or 

marked by more or less distinct lines of growth.

The largest specimens discovered are from 4 to 6ram in length. They 

appear to be mature or nearly so, but it is probable that the species 

attains a greater size than the discovered specimens indicate.

The only specimens discovered were obtained by dissolving in acid 

the pieces of impure limestone which were obtained by Mr. Stantou 20 

miles north of Cokeville, Wyo., where they were associated with Tortacella haldemani and several other minute forms herein described.

The specific name is given in honor of Prof. W. B. Clark, of Johns 

Hopkiiis University.

It is probable that the animal which constructed the shells here 

described was not really congeneric with those living forms which are 

classed under the genus Melainpus, but the features presented by these 

fossil shells are so nearly like those of the shells of living species of 

Melainpus that I am not able to satisfactorily refer it to any other genus. 

It is evidently congeneric with the Melampus antignus of Meek, from 

the brackish-water Cretaceous deposit near Coalville, Utah.
WHITE.] DESCRIPTION OP SPECIES. 43

Genus BHYTOPHOBTJS Meek.

RHYTOPHORUS PRISCUS Meek.

Plate Y, figs. 4, 5.

Melampus prisons Meek, 1860, Proc. Acad. Nat. Sci. Phila., Vol. XII, p-. 315. 

Rhytophoru's prisons Meek, 1872, Ann. Kept. U. S. Geol. and Geog. Surv. Terr., p. 478. 

Rhytophorus prisons Meek, 1876, Simpson's Rept. Great Basin of Utah, p. 364, pi. 5, figs.

4, a, b. 

Rhyt02)lioru8 priscusMotik, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV, p. 175, pi.

17, figs. 6,6a. 

Rhytophorusprisons White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 44, pi. 8, figs. 2,3.

Although Mr. Meek gave the generic name Rhytophorus to this form 

in 1872, and it was so used by himself and others during the following 

years, IIO diagnosis Of the genus was published until 1877, when it 

appeared in Yol. IV of th e reports of the United States Geological 

Exploration of the Fortieth Parallel, page 175. The same page also 

contains Mr. Meek's description of the species, as follows: '

Shell obovate, about once and a half as long as wide; spire depressed-conical; 

whorls about five, convex, or faintly subangul.ir; last one large, somewhat shouldered 

above, and taperiu-g below the middle; suture well defined; surface marked by rather 

obscure lines of growth, and the small, regular, vertical, or slightly oblique folds, 

which are distinct *on the volutions of the spire, and around the upper edge of the 

body-whorl, but obsolete on, all the surface below this; aperture narrow, angular 

above, and apparently very narrowly rounded below; outer lip sharp and apparently 

smooth within; columella provided with one rather strong oblique fold below, and 

a much smaller, less oblique one about half-way up the aperture.

Length of Mr. Meek's type specimen, 22mm ; diameter of the same, 

18inm. Some examples, however, which Mr. Stanton found near Sage 

Station, about 60 miles north of Sulphur Creek, where the species was 

originally discovered, show that it sometimes reached a much larger 

size. One of these specimens, when perfect, was not less than 30mm in 

length.

This species has been found at only the two localities just mentioned, 

but it is probable that its geographical range was coextensive with the 

formation.

EHYTOPHORUS MEEKII White.

Plate V, figs. 6, 7.

Rhytophorus meeki White, 1876, PoAvell's Repfc. Geol. Uinta Mts., p. 118.

Rhytophorus meeki White, 1880, Twelfth Ann. Rept, U. S. Geol. and Geog. Surv.

Terr., p. 82, pi. 30, figs. 8, a, b. 

Rhytophorus meeki White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 444, pi. 8,

figs. 4, 5.

Shell subfusiform; spire moderately extended, its length a little less 

than one-third the entire length of the shellj volutions about six in 

number, those of the spire convex, the last one large, elongate, subterete; suture impressed, and upon the proximal side of and near it
44 THE BEAK EIVER FORMATION. [BOLL. 128.'

there is an almost equally impressed revolving narrow furrow which 

has the appearance of a second suture; posterior fold of the columella 

well developed; the anterior one small. . Surface marked by ordinary 

lines of growth, and also, upon the spire, by numerous small varices or 

longitudinal folds which cross the volutions in a direction slightly 

oblique to the axis of the shell, but nearly parallel to the lines of 

growth. These varices appear on only the distal portion of the last 

volution, but they cross the entire exposed portion of the volutions of 

the spire.

Length of the most perfect of the type specimens, 20mm ; diameter, 

9ram ; but other specimens have a length of about 25"nu .

There is some reason to believe that this form is only a variety of 

R. prisons Meek; but the difference between typical examples of the 

two forms as they have heretofore been recognized is so great that it is 

still thought inexpedient to place them together.

Typical examples of K. meeU have as yet been found only at the 

locality near the mouth of Sulphur Creek.

Genus TORTACELLA gen. nov.

Shell slender, resembling in outward form that of the genus Acella 

Haldeman, but, unlike the shells of that genus, it bears two more or 

less prominent oblique folds upon its columella; outer lip plain, slightly 

thickened in the adult state; aperture elongate, rounded in front and 

sharply angular or narrowly subtruncate behind. Type, the Acella 

haldemani of White, which is at present the only species known

TORTACELLA HALDEMANI White.

Plate V, figs. 8, 9,10,11,12.

Acella haldemani White, 1878, Bull. U. S. Geol, and Geog. Surv. Terr, Vol. IV, p. 714. 

Acella haldemani White, 1880, Twelfth Ann. Kept. U. S. Geol. and Geog. Surv. Terr.,

p. 84, pi. 30, figs. 9, a, b.

Acella Italdemani White, 1883, Third Ann. Kept. U. S. Geol. Surv., p. 445, pi. 6, figs. 

18, 19.

Shell very small and very slender; spire much extended, longer than 

the aperture; volutions very obliquely coiled, about six in number, 

those of the spire broadly convex, or with a tendency to become flattened at the middle, the last one comparatively large but not ventricose; aperture elongate and narrow, especially behind, a little obliquely 

rounded and sometimes slightly expanded at the front, sometimes 

narrowed at the middle by the slight flattening of the volutions just 

mentioned. Surface marked by numerous fine raised lines, visible 

under a lens, which correspond in direction to the lines of growth and 

which are separated by spaces of about equal width with the lines. The 

direction of these lines is only slightly oblique to the axis of the shell. 

Outer.lip slightly thickened in adult specimens, the two columellar 

folds of about equal size, situated near each other at the mid length of 

the inner lip.
WHITB.I DESCRIPTION OF SPECIES. 45

Length of adult example, 6nim ; diameter of the last volution, a little 

less than l£mm .

All the specimens of this species which the collection contains have 

been obtained in the condition of chalcedonic pseudomorphs 1 by dissolving in acid pieces of the impure limestone layers in which they, 

together with many other small shells, were embedded. They have not 

been discovered in any other condition, and without the aid of the pro-- 

cess which has just been mentioned it is not likely that this species 

would have been discovered. Even by this means it was not until lately 

discovered that it bears two folds upon the columella and that it therefore does not belong to the genus Acella, to which it was originally 

assigned.

Family LIMN.EID^E.

Genus LIMM1A Lamarck,

LIMNJEA NITIDULA Meek.

Plate VI, figs. 1, 2, 3.

Melania ? nitidula Meek, 1860, Proc. Acad. Nat. Sci. Phila., VoL XII, p 314. 

Limncea (Limnophysa) nitidula Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol.

IV, p. 181, jl. 17, figs. 5, 5a. 

Limncea (Limnophysa) nitidula White, 1883, Third Ann. Kept. U. S. Geol. Surv., p. 445,

pi. 6, tigs. 15, 16.

The following is Mr. Meek's description of this species as given in 

Yol. IV of the reports of the United States Geological Exploration o,f 

the Fortieth Parallel, p. 181:

Shell small, ovate-subfusiform; spire conical, moderately elevated; volutions about 

six. and a half, convex, last one forming two-thirds of the entire length; suture well 

denned; aperture sub-ovate, narrowly rounded below and angular above, scarcely 

equaling one-half of the length of the shell; columella apparently with only a very 

small fold, and showing by the side of the inner lip below appearances of a small 

umbilical indentation. Surface marked by fine, rather obscure lines of growth, with 

(on some specimens) exceedingly faint traces of microscopical revolving striie.

Length, 10ram ; diameter of the last volution, 5ram.

Ever since the first publication of this species more or less doubt has 

prevailed as regards its specific and generic characters, the locality and 

formation from which it was first obtained, and the identity of the type 

specimens. I have hitherto been somewhat disposed to regard it as 

identical with the form which is described on a following page under 

ine name of Charydrobia stachei, and I should therefore have rejected it 

 from this summary of the fauna of the Bear River formation if it were 

not that a considerable number of specimens have lately been obtained 

which conform well to the original description as published by Mr. 

Meek. The specimens believed to be those which were thus originally 

used by him are figured on PI. VI. They are preserved in the collections of the United States National Museum, accompanied by a label in

'For an explanation of this condition, see Kept. U. S. Nat. Museum for 1892, p. 265.
46 THE'BEAR RIVER FORMATION. [BULL. 128.

Mr. Meek's handwriting, referring them to this species. The examples 

figured by Mr. 'Meek in Vol. IV of the reports of the United States 

Geological Exploration of the Fortieth Parallel, and copied by me in 

the Third Annual Eeport of the United States Geological Survey, are 

unlike these specimens, and unlike any form known to me in the Bear 

Eiver fauna, and they do not answer to Mr. Meek's description.

This species was originally discovered at the long-known locality near 

the mouth of Sulphur Creek, but specimens have since been obtained 

at other localities. Mr. Stanton found some exam pi es-of it at the locality 20 miles north of Cokeville, which were embedded in thin layers of 

impure limestone, from which they were obtained in the condition of 

"chalcedonicpseudomorphsby its solution in acid, in the manner already 

mentioned.

The distance between that locality and the one at which this form 

was originally discovered is about 100 miles, which indicates that it has 

a wide range within the geographical limits of the formation.

 Genus PLANORBIS Miiller. 

Subgenus GYRAULUS Agassiz. 

PLANORBIS PR^CURSORIS n. s. 

Plate VI, figs. 4, 5, 6, 7.

Compare with P. (G-.) milUaris White, Third Aim. Rept. U. S. Geol. Surv., p. 447, 

4)1. 28, figs. 10, 11. . '

Shell minute, subdiscoidal, the upper side flattened, sometimes slightly 

convex and sometimes'very slightly concave, lower side umbilicate; 

volutions almost regularly rounded and about four or four and one-half 

in number; aperture nearly round, only slightly oblique to either the

plane or diameter of the coil. Surface marked only by lines of growth.

Diameter of coil of the largest example obtained, 3"1111 ; diameter of 

aperture, about I"1111 .-

This little shell is^jp. typical example of the section of the genus Planori is, to which Agassiz gave the name Gyraulus. It differs from the 

form which Dr. Hayden found in Jurassic strata at the southwest base 

of the Black Hills, to which Meek and Hayden gave the name P. ( r.) 

vetimius, in not having a depressed spire and in showing a less rapid 

increase in the size of the volutions. The P. (G.} militaris White (loc. 

cit.) which was obtained from the Wasatch formation of Utah more 

nearly resembles this form than does any other fossil form with which " 

it need be compared, but because there is so much difference in the 

geological age of the formations from which they respectively come, and 

because the faunal associates of each are wholly different, the probability of the two" forms being specifically identical is not considered.

The presence of this form in the Bear River strata near the mouth 

of Sulphur Creek has been known for several years, but satisfactory
WHITB.] DESCRIPTION OF SPECIES. 47

examples of it have only lately been obtained. These were found by 

Mr. Stanton at the locality 20 miles north of Cokeville, and were 

obtained by dissolving in acid fragments of the layer of impure limestone, which has been mentioned in connection with the description of 

Tortacella haldemani and other species.

Its presence at localities so widely separated indicates that it had a 

wide distribution within the geographical limits of the formation in 

which it occurs.

Family 

> Genus PHYSA Draparnaud. 

PHYSA USITATA n. s. 

Plate VI, figs. 8, 9.

pjiysa ? White, 1883, Third Ann. Kept. U. S. Geol. and Geog. Surv. Terr., p. 

449, pi. 6, fig. 17. :

A collection of fossils which I obtained several years ago from the 

Bear Eiver strata, near the mouth of Sulphur Creek, contained a single 

specimen of Physa, of which I afterwards published a figure (loc. cit.), 

but to which I then thought it inadvisable to apply a separate specific 

name. The collections which Mr. Stauton made in 1891 contain several 

other specimens of this form, two of which are figured on PI. VI. All 

of these, like the one originally discovered, are imperfect, but they 

represent a typical species of the genus. Indeed, the proportions and 

general aspect of this shell are such that it is difficult to say how it 

differs specifically from certain well-known fossil and living species of 

Physa. It especially resembles those specimens of the common North 

American living species P. gyrina Say which have a comparatively 

short spire. Because of this close similarity to published species I 

have heretofore hesitated to give a separate name to this form, but I 

do so in this case for the sake of convenience in characterizing and 

discussing the fauna of the Bear Eiver formation, and because it is 

presumably different from any published form. It is an interesting 

factthat this, the oldest species of Physa yet discovered in North America, should so closely resemble forms that are now living upon this 

continent.

All the discovered specimens of this form have been obtained in the 

condition of chalcedoriic pseudomorphs by dissolving fragments of 

the embedding limestone in acid, as has been stated in connection with 

the description of preceding species.

Mr. Stanton's specimens were obtained at the locality 20 miles north 

of Cokeville, about 100 miles from the place at which the species were 

originally discovered. This fact indicates that it was generally distributed within the geographical limits of the formation in which it occurs,
48 THE BEAR RIVER FORMATION. [BULL. 128,

Family HELICID/E. 

Genus HELIX Linnaeus.

Plate VI, fig. 13.

Among the numerous small silicified shells obtained by dissolving in 

acid fragments of the fossiliferous limestone layer which Mr. Stanton 

discovered at the locality 20 miles north of Cokeville, Wyo., is a single 

small specimen which seems to be referable to some one of the sections 

into which the original genus Helix has been divided. The specimen 

is too incomplete for satisfactory diagnosis, and it is mentioned and 

figured here only for the purpose of giving as full a statement as possible of the fauna of the Bear River formation. It resembles the form 

which Dr. Stache has referred with doubt to the H. cretacea of von 

Tausch. 1

Genus TORNATELLHSTA Beck.

TORNATELLINA? ISOCLINA 11. S.

Plate VI, figs. 14, 15.

Shell short, narrowly umbilicate, but the umbilicus often nearly or 

quite covered by a thin layer of callus, subfusiforin or subglobose; spire 

short, its sides nearly straight; apex acute; volutions about seven in 

number, convex, the last one extending considerably forward at the 

aperture, rounded on the anterior side, from which it is narrowly 

rounded into the small umbilicus; aperture moderately large, but 

because of the imperfection of the specimens its shape is not fully

known; outer lip plain; inner lip with a thin layer of callus, and upon

the body of the shell at the inner side of the aperture there is a single, 

slightly raised, angular, revolving ridge, which extends backward 

within the shell and forward upon the inner lip, but it is hardly visible when the outer lip is complete; suture impressed. Surface marked 

by ordinary lines of growth.

The length of the largest example obtained was, when perfect, about 

10mm ; diameter of the last volution, 7£min .

It is doubtful whether this shell really belongs to the .genus Tornatellina, but its characteristics, so far as they are observable, agree more 

nearly with those of that genus than with those of any other shell 

known to me.

Mr. Stanton found the only known examples at the locality 20 miles 

north of Cokeville, Wyo. They are in the condition of chalcedonic 

pseudomorphs, and were .obtained by dissolving in acid fragments of 

the thin layers of impure limestone containing them.

'See Abhandl. K.-k. gcol. ReioUsanstalt, Wien, Band XIII, p. 167, pi. 4, fig. 30, 188,9,
WHITE.] DESCRIPTION OF SPECIES. 49

Family NERITID^E.

Genus NERITINA Lamarck.

NERITINA NATICIFORMIS White.

Plate VI, figs. 10, 11,12. '

Neritina naticiformis White, 1878, Bull. U. S. Geol. and Geog. Surv. Terr., Vol., IV,

p. 715. 

Neritina naticiformis White, 1880, Twelfth Ann. Rept. U. S. Geol.^and Geog. Surv.

Terr., p. 89, pi. 30, figs. 3, a, b. 

Neritina naticiformis White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 430, pi. 7,

figs. 5, 6.

Shell small, young examples subglobose and resembling Natica in 

general aspect, but adult examples expanded and subovoid in outline; 

spire moderately prominent; volutions four and a half Or five in number, convex, a little more narrowly rounded at the posterior than at the 

anterior side, those of the spire rounded into the depressed suture, the 

last one in adult shells very large, the expansion being greatest in front; 

inner lip of moderate breadth, flat or slightly concave, its inner margin 

moderately sharp, slightly concave, toothless; outer lip thin; aperture 

large, suboval. Surface plain or marked by faint, fine, close-set, 

revolving lines, visible only under a good lens.

Antero-posterior diameter, llmm ; transverse diameter, 8mm.

This species was originally described (loc. cit.)from young examples, 

and the description was therefore not quite accurate. The examples 

used in the foregoing description were brought by Mr. Stanton from 

the locality 20 miles north of Cokeville, in Wyoming. They have been 

obtained in the condition of chalcedouic pseudomorphs by dissolving 

fragments of the embedding limestone in acid in the manner already 

mentioned in connection with the description of other species.

It has been found only at the locality just mentioned and at the one 

near the mouth of Sulphur Creek, but these two localities being 100 

miles apart, it is reasonable to suppose that its dispersion was nearly 

or quite equal to the geographical limits of the formation in which it

occurs.

NERITINA STANTONI n. s.

Plate VI, figs. 16, 17, 18.

Shell small, spire slightly elevated or sometimes nearly flat; volutions about four in number, flattened upon the distal side and broadly 

rounded upon the proximal side. The place of meeting of the two 

sides, which is the periphery of the shell, is more or less angular, and 

in typical examples is marked by a small revolving carina, which is 

sharp and prominent upon all the volutions, but it becomes obsolete 

near the outer lip of adult examples'. Upon some examples evidently 

belonging to this species the carina is obsolete upon all parts, but the 

Bull. 128 4
50 THE BEAR RIVER FORMATION. [BULL. 128.

subangularity at that part of such shells, together with their general 

characteristics, leaves no reasonable doubt that they, too, belong to this 

species. Inner lip not very broad, plain ; aperture moderately expanded, 

broadly truncate posteriorly and somewhat narrowly rounded in front; 

outer lip thin. Surface marked by distinct lines of growth, and upon 

one of the examples two broad revolving bands of color- marking is still 

preserved.

Antero-posterior diameter of the largest example discovered, 9mm ; 

transverse diameter, 6mm .

This species- was found by Mr. Stanton in the thin layer of impure 

limestone at the locality 20 miles north of Cokeville, in Wyoming, where 

it was associated with N. naticiformis and other forms, which were 

obtained by dissolving fragments of the limestone in acid. He also 

obtained it in the ordinary condition from the locality near Sage Station, 

in the valley of Twin Creek.

Family 

Genus PACHYMELANIA gen. nov.

Shell elongate, compact; test strong or more or less massive, which 

is largely owing to the deposit of callus upon the inner surface ; volutions moderately convex or flattened, marked by longitudinal varices 

or revolving lines or by both, and both may be strong or obsolete, the 

last volution not inflated; suture distinct; aperture subovate, its posterior angle, which would otherwise be acute, is usually made obtuse 

by the deposit of callus, but the callus is not protuberant nor very 

thick; anterior portion of the aperture extended and rounded, outer 

lip sinuous, slightly thickened; inner lip covered with a layer of callus 

of moderate and nearly uniform thickness; coluinella arcuate.

These shells resemble the Cerithiidse in aspect, but they are excluded

from that family by the absence of any notch or canal in any part of 

the aperture. They differ from Melanopsis in this respect and in wanting a protuberance of callus upon the inner lip, although they somewhat 

resemble some forms of that genus in other respects. The character 

of the anterior portion of the last volution is much like that of Goniobasis Lea, to which genus both Mr. Meek and myself have referred it 

in former publications, but it differs from that genus in the moderate 

massiveness of the test and in a general habitus which is readily observable but difficultly describable. None of the species yet known shows 

any tendency to the production of spines or even of strong nodes. Type, 

the Goniobasis cleburni of White.

The only American species which I at present certainly refer to this 

genus are those which are described in the following paragraphs, all of 

which are members of the fauna of the Bear River formation. Few 

European fossil forms seem to be cogeueric with these, but it is probable that at least a part of the species published by Dr, Q, StaQhe and
WHITE.] DESCRIPTION OF SPECIES. 51

Dr. L. von Tausch and referred by them to Goniobasis are properly referable to this genus. 1 The characteristics of the living Melania (Sermyla) 

admirabilis Smith from Lake Tanganyika, in Africa, very closely resemble those of Pachymelania; but the test of that species appears to be 

less massive, than is that of typical forms of this genus, and its aperture 

is not so much produced in front. The fact of such a resemblance is, 

however, an interesting one, because the African species is there associated with Pyrgullfera, as Pachymelania is thus associated in the Bear 

River formation.

PACHYMELANIA CLEBTJRNI White. 

Plate VII, figs. 1,2,3.

Goniobasis clcburni White, 1876, Powell's Rept. Geol. Uiuta Mts., p. 122.

Goniobasis deburni White, 1880, Twelfth. Ann. Kept. U. S. Geol. and Geog. Surv. Terr.,

p. 91, pi. 30, figs. 4, a, b, c, d.

Goniobasis deburni White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 460, pi. 6, 

figs. 4, 5. 6.

Shell moderately large, tapering regularly from the apex, the sides of 

the spire being gently convex; volutions of adult shells ten or more in 

number, regularly increasing in size, the sides of those of the spire 

gently convex or nearly flat, the anterior half of the last volution 

broadly convex; aperture obliquely subovate in outline. .Surface.of 

the spire marked by numerous strong, slightly curved longitudinal 

ridges or varices, slightly stronger at the middle than at the ends, 

which extend from suture to suture in a direction a little oblique to the 

axis of the shell. Surface of the anterior side of the last volution 

marked by coarse, slightly raised revolving lines, and traces of smaller 

revolving lines are sometimes seen upon the spire, but these are seldom 

strong enough to crenulate the varices. The varices usually become 

obsolete near the aperture of adult shells, and in some cases they are 

obsolete upon one or more of the last volutions of the spire.

This species was first discovered at the locality near the mouth of 

Sulphur Creek, but it has been found at most of the localities at which 

fossils of the fauna of the Bear River formation have been obtained. 

Its distribution may therefore be regarded as equal to the geographical extent of the formation.

PACHYMELANIA CHRYSALIS Meek. 

Plate VII, figs. 6, 7. Compare also with 8,12, 13.

Goniobasis chrysalis Meek, 1871, Ann. Rept. IL S. Geol. and Geog. Surv. Terr, for 1870,

p. 316. 

Goniobasis chrysalis White, 1880, Twelfth Ann. Rept. U.'S. Geol. and Geog. Surv.

Terr., p. 91, pi. 30, figs. 6, a, b. 

Goniobasis chrysalis White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 460, pi. 6,

figs. 13, 14.

»See Abhandl. K.-k. geol. Reich^natalt, Wjen, Band XJII, Heft I, 1889. Also idem. Band XII, JTo.l, 1886, ' ' - - . -
52 THE BEAR RIVER FORMATION. [BULL. 128.

The following is Mr. Meek's original description of this species 

(loc. cit.):

Shell generally almost cylindrical below the middle, but more abruptly tapering 

 above, volutions six or seven, flattened, with the upper margin thickened, last one 

not angular, and scarcely larger than the next above it; suture well denned.

Surface ornamented by distinct vertical cost;.e, often ranged nearly in tbe same 

line all the way up the spire; these are partly interrupted by an effort to form three, 

or rarely four, obscure revolving lines or ridges, the upper of which is larger and 

more prominent than tbe others, which character, with the slightly enlarged upper 

ends of the vertical costte, causes the thickened appearance of the upper margins of 

the volutions; several other slender and more distinct revolving lines also occur on 

the under side of the last turn. Aperture somewhat rhombic-ovate.

Mr. Meek's specimens were all small, and at the locality where the 

species was first discovered no other than small specimens have been 

found. He gives the length as about 17mm ; diameter, 5mm . Among 

the collections which were brought by Mr. Stanton from other localities, 

however, are specimens evidently belonging to this species which when 

perfect were not less than 25mm in length. The longer and more slender 

specimens are sometimes bent or distorted.

This form is generally found associated with P. deburni and C. chrysalloidea, and its distribution seems to be throughout the whole geographical extent of the formation.

PACHYMELANIA CHRYSALLOIDEA White. 

Plate VII, figs. 4, 5.

Goniolasis chrysaUoidea White, 1876, Powell's Rept. Geol. Uinta Mts., p. 123. 

Goniolasis chrysalloidea White, 1880, Twelfth Ann. Rept. U. S. Geol. and Geog. Surv.

Terr., p. 92, pi. 30, tigs. 5, a, b. 

Goniobasis chrysalloidea White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 462, pi.

6, figs. 11,12.

Shell of medium size, gradually tapering from the last volution to the 

apex; volutions about seven or eight, those of the spire slightly convex, 

the last one broadly rounded to the anterior end; suture impressed, the 

apparent impression being increased by the projecting fold of the distal 

border of each volution, which is appressed against the next preceding 

one. Surface marked by more or less distinct longitudinal, slightly 

bent ridges or varices, which are crossed by several revolving lines that 

appear only on the ridges,' and not between them, giving the ridges a 

knotted or crenulated appearance; anterior surface of the last volution 

also marked by distinct raised revolving lines.

Length of the most perfect of the original type specimens, 28mm ; 

diameter of the last volution, 9mm ; but some specimens since obtained 

are somewhat more slender.

This species is* closely related to both G. deburni and G. chrysalis, 

with both of which forms it is associated. It differs from the latter in 

its much larger size, much greater apical angle, straighter sides of the
WHITE.] DESCRIPTION OF SPECIES. 53

spire, and in the details of its ornamentation. It differs from G. clel)urni in its smaller size, the more distinct crenulation of its longitudinal 

varices or folds, and in possessing the revolving fold-like projection of 

the distal border of its volutions which has been mentioned in the. 

description.

The locality at the mouth of Sulphur Creek and the one 7 miles north 

of Evanston are the only localities that have yet furnished recognized 

specimens of this species, and all of the specimens are in an imperfect 

condition.

PACHYMELANIA TURBICULA n. s.

Plate VII, figs. 14, 15.

Shell rather small and slender; apex acute; sides of the spire nearly 

straight; volutions of the spire moderately convex and marked by 

numerous longitudinal varices which have a tendency to range themselves in continuous lines; the ends of the varices of the one volution 

not quite reaching those of the next preceding and succeeding volu 

tious gives the shell the appearance of having an unusually deep suture; 

the anterior volutions of the spire are marked by four depressed revolving lines, giving the varices a crenulated appearance, but these lines 

are obsolete or absent on the smaller volutions. The surface of the 

anterior part of the last volution is marked by four or five raised revolving lines, which diminish in strength toward the axis.

The largest and best specimen discovered is imperfect at the proximal 

end, and its full length is therefore unknown; it probably reached a 

length of 16mm and a diameter of 6mm at the last volution. This form 

somewhat resembles the young of P. cleburni, but it differs conspicuously in having a smaller apical angle and in having its sides straight 

along its entire length. Its longitudinal varices are also much more 

generally disposed in continuous lines.

Mr. Stanton obtained this species at the locality near the mouth of 

Sulphur Creek and at the one near Sage Station.

There are many specimens referable to Pachyinelania in the collections obtained from the Bear River formation, mostly small examples, 

which one finds it difficult to assign to any of the species just described 

because of the recognizable intersp.ecific variation in the case of all of 

them. This fact, together with the remarkable variation of the associated Pyrgulifera liumerosa which is to be pointed out on following 

pages, suggests the possibility that some of the forms of Pachymelauia 

just described are only varieties of some of the others, but so far as these 

forms are now known they all seem, to be worthy of full specific recognition. One of the varieties referred to, found by Mr. Stanton at the 

locality near Sage Station, in the valley of Twin Creek, probably represents a variety of P. chrysalis, but the specimens are so constant in 

their characteristic differences Irom that form that I have hesitated to 

refer them, to it. This variety is well represented by figs. 12 and 13, 

on PI. VII-
54 THE BEAR RIVER FORMATION/ [BULL. 128.

PACHYMELANIA? MACILENTA White. 

Plate VII, fig 9. Compare also with 10,11.

Gonioltasis macllenta White, 1880, Twelfth Ann. Kept. U. 8. Geol. and Geog. Surv.

Terr., p. 93, pi. 30, figs. 10, a. 

Goiiiobasis macile'nta White, 1883; Third Ann. Rept. U. S. Geol. Surv., p. 462, pi. 6,

fig. 12.

Shell comparatively small, slender 5 test thinner than is usual with 

typical species of Pachyinelania; sides of the spire straight or slightly 

concave; volutions ten or more in number, uniformly increasing in size, 

the distal border of each so appressed against the next preceding one 

that their flattened sides form the continuous surface of the straight 

sides of the shell. Surface marked by the linear suture and by lines of 

growth which are gently sinuous and have a general direction approximately corresponding to the axis of the shell. Near the distal border 

of each volution there is usually to be observed in well-preserved examples a more or less distinct revolving impressed line which simulates a 

second suture.

Numerous examples of this species have been discovered, but they 

are all more or less broken and imperfectly preserved. The shape of 

the aperture is therefore known only by the outline of the volutions 

and the direction and character of the lines of growth which are observable upon the volutions. All of these characters are consistent 

with those which distinguish Pachyinelania.

Most of the specimens discovered are small, the largest indicating 

that adult examples reached a length of 25mm and a diameter of 7""11 

for the last volution. The principal reason for doubt that this shell 

belongs to Pachyinelania is the comparative thinness of the test. In

tliis respect it more nearly resembles Goniobasis, to which genus I have

hitherto referred it. A chalcedonic pseudoinorph of a young shell 

which I refer to this species shows that the minute apical volutions 

were distinctly convex, but that they became flattened before the shell 

had reached a millimeter in length. The colmnella of this example, 

not being distinctly arcuate, suggests its relation to Eulimella, but 

there is no indication of a reversal, or even of distortion, of the apical 

volutions. It is probable that tigs. 10 and 11 on PI. VII represent 

another species, but I am not now able to satisfactorily diagnose them 

as specifically different from. P. ? macilenta.

This species was first discovered at the locality near the raouth of 

Sulphur Creek, but it has since been found at most- of the localities 

which have furnished fossils of the Bear Eiver fauna. It therefore 

appears to have as great a geographical distribution as has any other 

member of that fauna.
WHITE.] DESCRIPTION OF SPECIES. 55

Genus PYEGULIFBEA Meek.

This genus has been the subject of so much discussion and the only 

known American representatives of it are so characteristic of the Bear 

Eiver formation that it is thought advisable to give Mr. Meek's generic 

diagnosis here and to discuss the genus and its geographical distribution 

and chronological range more at length on following pages. The following is the diagnosis as published by Mr. Meek in Vol. IV of the 

reports of the United States Geological Exploration of the Fortieth 

Parallel, page 176, but it requires some .modification to admit certain 

forms since properly referred to this genus; such, for example, as those 

upon which the shouldering of the volutions and the strong surface 

features mentioned by Mr. Meek are not well developed:

Shell subovate, thick, imperforate; spire produced, turreted; volutions angular, 

shouldered, and nodular above; surface typically, with vertical ridges and revolving 

markings; aperture suboyate, faintly sinuous, but not notched or distinctly angular 

below; outer lip prominent in outline below the middle, retreating at the base, and 

subsinuous at the termination of the shoulder of the body-volution above; peristome 

continuous; inner lip a little callous below, and thickened all the "way up, but without a protuberant callus above, sometimes with a shallow umbilical furrow along ita 

outer margin below.

With the single exception to be mentioned further on, neither this. 

nor any nearly related genus is yet known in North America beyond 

the limits of the Bear River formation. All the other known species 

of Pyrgulifera are mentioned on following pages under the general head 

of "The geographical and time range of Pyrgulifera."

PYR&ULIFERA HUMEROSA Meek. 

Plate VIII, figs. 1,27 3,47 5,6,7,8,9,10,11, and Plate IX, figs. 4,5,6, 7,8.

Melania humerosa Meek, 1860, Proc. Acad. Sci. Phila., Vol. XII, p. 313.

Pyrgulifera humerosa Meek, 1872, Ann. Kept. U. S. Geol. and Geog. Surv. Terr, for 1871,

p. 376 (no description). 

Pyrgulifera humerosa Meek, 1876, Simpson's Kept. Great Basin of Utah, p. 363, pi. 5,

figs. 6, a, b, c. 

Pyrgulifera humerosa Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV, p.

176, pi. 17, figs. 19,19a, and Avoodcut.

Pyrgulifera humerosa White, 1882, Nature, Vol. XXV, p. 101. 

Pyrgulifera humeroaa White, 1882, Proc. U. S. Nat. Museum, Vol. V, p. 98, pi. 3, figs.

10,11,12. 

Pyrgulifera humerosa White, 1883, Third Ann. Eept. U. S. Geol. Surv., p. 469, pi; 6, figa.

4, 5, 6. 

Pyrgiilifera humerosa Tausch, 1884, Sitzungsber. K. Akad. Wiss., Band XC, p. 60, PI. I,

figs. 1-3.

Pjjrguiifera humerosa White, 1885, Am. Jour. Sci., Vol. XXIX (2), p. 278. 

Pyrgulifera humerosa Tausch, 1886, Abhandl. K,-k. geol. Reichsanstalt, Band XII, p. 4.
56 THE BEAR RIVER FORMATION. [BULL. 128.

The following is the specific description published by Mr. Meek on 

pages 176-177 of Vol. IV of the reports of the United States Geological 

Exploration of the Fortieth Parallel:

Shell attaining a rather large size, moderately solid, ovate-suhfusiform; spire 

prominent, distinctly turreted; volutions five and a half to about seven, angular and 

strongly shouldered, the upper surface being flattened or a little concave, with 

usually a slight outward slope from the suture to the angle or shoulder, where it 

meets the vertical outer surface nearly at, right angles; last or body-volution large, 

or generally composing about two-thirds the entire bulk and length of the shell; 

suture well denned by the prominence and angularity of the volutions, but not 

channeled. (Surface of each turn ornamented by about ten to fifteen rather strong, 

vertical, or slightly oblique folds, or coatee, each of which terminates in a small, 

nodular projection at the shoulder above, so as sometimes to impart a subcorouate 

appearance to the same, while they all become nearly or quite obsolete below the 

middle of the body-volution; vertical costte crossed by smaller, but quite distinct 

revolving, raised lines, or small ridges, some four to six of which may be counted on 

the outer surface of each turn of the spire, and about ten on the body-volution, 

where they increase in size downward; upper flattened surface of the volutions 

generally only marked by the moderately distinct lines of growth seen below; aperture obliquely rhombic-subovate, being higher than wide', rounded subrectangular 

above, and narrowed and more or less angular, with a slight sinus or notch at the 

connection of the outer and inner lips near the middle below; coluinella arcuate; 

inner lip, in mature specimens, rather thick all the way up, but more so below, 

where it is somewhat reflected and margined by a slight, revolving, umbilical furrow, with usually an angular outer margin; outer lip sharp, prominent near the 

middle, and retreating below and at the angle of the Avhorls above.

The length of Mr. Meek's principal type specimen, which is one of 

the largest yet discovered, is 41mm ; breadth of its last volution, 23mm. 

There is, however,'much difference in size and proportions among the 

multitude of specimens that have been collected.

Mr. Meek's description applies completely to his type specimen and 

to much the greater part of the many hundreds of specimens which have 

been discovered in the Bear River formation. A few of these, however, 

show such variations of form and ornamentation that no one would 

hesitate to assign them to different species if they were not associated 

with intermediate forms and by them more or less closely connected 

with the great mass of typical forms. Figs. 1 to 10 on PI. VIII represent what may be regarded as typical forms, and figs. 4 to 8 on PI. IX 

represent some of the varieties referred to.

The greatest amount of variation that has been observed is found 

among the specimens collected by Mr. Stauton at the Cokeville locality, 

where most of the specimens figured on PI. IX which show material 

variation were obtained. The variation consists mainly in the modification of surface features and ornamentation, but there is also some 

variation of general shape. The coincidence of the two kinds of variation is, however, only exceptional.

Figs. 1, 2, and 3 on PI. IX represent a form which differs so much 

from all the others that I have thought it expedient to give it the 

separate specific name which heads the following description. I do this 

more as a matter of convenience than because of any belief that there
WHITE.] DESCRIPTION OF SPECIES. 57

is in the Bear River formation more than one true species of Pyrgulifera. That is, it is evident that all the varieties just referred to, including the one last mentioned as well as the typical forms of P. humerosa, 

were intimately associated with one another while living; and I think 

it is also evident that they all freely interbred. If this was the case, 

each form was not only potentially but actually ancestral to representatives of all the other forms, and therefore, according to my understanding of the character and limitation of a species, all these forms 

are properly included in one specific group.

No member of the Bear River fauna is more conspicuous than is 

Pyrgulifera humerosa. Its geographical distribution is throughout the 

known extent of the formation, but it has been found especially abundant at the locality near the mouth of Sulphur Creek and at the one 7 

miles north of Evanston, in southwestern Wyoming.

PYROULIFERA STANTONI n. s. 

Plate IX, figs. 1,2,3.

Among the specimens obtained at the Cokeville locality by Mr. 

Stanton are some examples of Pyrgulifera which have already been 

referred to as differing so much from typical forms of P. humerosa that 

I think it expedient for geological, but riot necessarily for biological, 

purposes to give them a separate name. The principal difference 

between these specimens and typical examples of P. humerosa is their 

greater elongation, less distinct shouldering of the volutions, the somewhat greater prominence of the longitudinal varices, and less distinctness of the revolving lines. Typical examples of P. humerosa, as well 

as the other varieties referred to in connection with the description of 

that species, were found associated in the same layers with this form, 

and few examples*have been discovered which may be regarded as 

intermediate between them.

The type specimens of P. stantoni are represented by figs. 1 and 2. 

Fig. 3 represents a form which, while it is here referred to P. stantoni, 

seems to be intermediate between them and the more elongate examples of P. humerosa.

Family RISSOID^E. 

Genus HYDROBIA Hartmaun.

BVDROBIA QCCULTA 11. S.

Plate X, figs. 12,13.

Shell very small, elongate, minutely perforate at the base; apex 

slightly obtuse; volutions six or seven in number, rounded, those of 

the anterior half of the shell a little more oblique to its axis than are 

those of the posterior half; suture impressed; aperture subovate, 

extended in front by the obliquity of the last volution. Surface 

marked only by lines of growth.
58 THE BEAU RIVER FORMATION.

Length, 3nim ; breadth of last volution, lmi".

Several examples of this little shell, like those of several of the other 

species which are described in this bulletin, were discovered in the condition of chalcedonic pseudomorphs among the debris resulting from 

an acid solution of fragments of impure limestone found by Mr. Stanton 

at the locality 20 miles north of Cokeville. It seems to be properly 

referable to Hydrobia, but the apical angle of the spire is less than is 

usual with species of that genus, and the apex is also a little more 

obtuse.

Genus BYTHINELLA Moquin-Tandon.

BYTHINELLA LATENTIS n. s. 

Plate X, figs. 10, 11.

Shell very small, moderately elongate, its sides gently convex, base 

imperforatej volutions five in number, convex; suture impressed ; surface marked only by lines of growth j aperture not much expanded, 

subcircular or suboval in outline, obtusely angular posteriorly.

Length, hardly reaching 3mm ; diameter of'the last volution, linm , or a 

little less.

This little shell was found associated with the preceding species, and 

was obtained from its embedding limestone matrix in the same manner. 

It has been found at no other locality than the one 20 miles north of 

Cokeville, and if they had not been changed from their original condition to that of chalcedonic pseudomorphs it is not likely that they 

would ever have been discovered.

Genus CHAEYDEOBIA Stache.

CHARYDROBIA STACHEI n. s.

Plate X, figs. 7, 8,9.

Shell large for a species of this genus, subfusiform; volutions about 

six in number, regularly convex; aperture subovate in outline, narrowly 

rounded in front, narrow and subangular behind; umbilical fissure more 

or less distinct. Surface plain.

Length of the largest example discovered, 13mm ; breadth of the last 

volution of the same, G£nmi .

Specimens of this shell,- like those of several others already described, 

were obtained in the condition of chalcedonic pseudomorphs by dissolving in acid the fragments of impure limestone in which they were 

imbedded. This form has been by some collectors confounded with 

Limncea nitidula, but it is distinctly different from that species, and 

there seems to be no good reason to doubt that it is properly referable 

to the genus Charydrobia Stache. Indeed it bears a close resemblance 

to the type of that genus, C. characearum, as figured by Stache on PI. 

V, Abhandlungen der K.-k. geologischen Eeichsanstalt, Band XIII.
WHITE.] DESCRIPTION OF SPECIES. 59

This species has been found only at the locality near the mouth of 

Sulphur Creek and at the one 20 miles north of Cokeville. It is probable, however, that it had a general distribution in the Bear River 

formation.

Family VIVIPARID^E.

Genus VIVIPABUS Montfort.

VIVIPARUS COUESI White.

Plate X, fig. 1.

Campeloma 1 Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV, p. 181,

pi. 17, figs. 15,1 >a.

Viviparus cones I White, 1878, Bull. U. S. Geol. and Geog. Surv. Terr., Vol. IV, p. 717. 

Viviparus couesi White, 1880, Twelfth Ann. Eept. U. S. Geol. and Geog. Surv. Terr.,

p. 99, pi. 30, fig. 1, a. 

Viviparns couesi White, 1883, Third Ann. Eept. U. S. Geol. Snrv., p. 467, pi. 8, fig. 1.

Shell very large when fully adult; volutions six or seven, convex, the 

distal side, of the last one especially, abruptly rounded to the suture, 

giving it a somewhat shouldered aspect there, while the outer side is 

broadly convex arid sloping gently forward and inward; suture deeply 

impressed, the apparent depth being increased by the great convexity 

of the volutions. Surface marked by the ordinary lines of growth, no 

revolving marks of any kind having been detected. The lines of 

growth indicate that the margin of the outer lip is nearly straight, as 

is usual with all species of this genus, this feature being one of those 

which distinguish shells of this genus from those of Campeloma. Inner 

lip somewhat thickened by callous and reflexed at the proximal or 

anterior end, but not covering the umbilical fissure there, which is moderately large. The precise shape of the aperture is unknown, but the 

outline of the volutions shows that it was suboyate.

No perfect examples have been discovered, but the largest one yet 

obtained would, if perfect, measure about 65mm in length; full Avidth 

of body volution, 3Smm .

The apical portion of a specimen of this species was described and 

figured (loc. cit.) by Mr. Meek under the generic name of Campeloma, 

but he gave it no specific name. His specimen, however, like the type 

specimen figured on PL X, shows by its nousinuous lines of growth 

that it had the straight outer lip of Viviparus and not a sinuous one 

like Campeloma.

Mr. Meek's specimen came from the locality near the mouth of Sulphur Creek. The type specimen figured on PI. X came from the 

locality 7 miles north of Evanston. The species has not been certainly 

identified at any other locality.
60 THE BEAR RIVER FORMATION. [uuLL.128.

Genus CAMPELOMA Kafinesque.

OAMPELOMA MACROSPIRA Meek.

Plate X, figs. 2,3.

Melantho (Campeloma} macrospira Meek, 1873, Ann. Rept. U. S. Geol. and Geog. Surv.

Terr, for ] 872, p. 478. 

Campeloma macrospira Meek, 1877, U. S. Geol. Explor. Fortieth Parallel, Vol. IV,

p. 179, pi. 17, figs. 17, a, b. 

Campeloma macrospira White, 1880, Twelfth Ann. Rept. U. S. Geol. and Geog. Surv.

Terr., p. 102, pi. 30, figs. 2, a. 

Campeloma macrospira White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 469, pi. 8,

figs. 6,7.

The following is Mr. Meek's description of this form as published by 

him in 1877 (loc. cit.):

- Shell ovate, of medium size; volutions about five or six, convex, increasing rather 

gradually in size and without revolving ridges or angularities; spire moderately 

prominent, conical, and not eroded at the apex; suture distinct, in consequence of 

the convexity of the volutions; surface with fine, obscure, slightly sigmoid lines of 

growth; aperture ovate; inner lip somewhat thickened below.

The length of Mr. Meek's type specimen, which is figured on PI. X, 

is 44"im ; breadth of the last volution of the same, 28mni .

Specimens of this species have been found at most of the localities 

at which the Bear River formation has been recognized, and its geographical distribution was apparently equal to that of the formation.

Genus LIOPLAX Troschel.

LlOPLAX? ENDLICHI White.

Plate X, figs. 4,5.

Goniolasis endlichi White, 1878, Bull. U. S. Geol. and Geog. Surv,. Terr., Vol. IV, p. 716. 

Goniobasis endhchi White/1880, Twelfth Auu. Rept. U. S. Geol. and Geog. Surv; Terr.,

p. 92, pi. 30, figs. 7, a, b, c. 

Goniobasis (Lioplax?) endlichi White, 1883, Third Ann. Rept. U. S. Geol. Surv., p. 463,

pi. 7, figs. 7,8.

Shell moderately elongate-conical, sides of the spire straight, or 

slightly concave; volutions six or seven in number, convex, the larger 

ones showing an obsolete angularity at the middle 5 suture well defined 

and appearing unusually deep, because of the prominent convexity of 

the volutions; aperture subovate in outline,its distal end angular, its 

front somewhat narrowly rounded; outer lip apparently sharp; inner 

lip with a thin reflected callus which is more developed anteriorly than 

posteriorly. Surface marked by fine distinct lines, which give it a cancellated appearance under a lens. A few of the revolving lines are 

stronger than the others, and these are observable without the aid of 

a lens.

Length, about 22mm ; diameter of the last volution, llmm.
WHITE.] DESCRIPTION OF SPECIES. ' 61

This form has been found only at the locality 7 miles north of Evanston, Wyo. It was evidently not an abundant species, but it is distinctly 

different from any other recognized member of the Bear Kiver fauna. 

There is, however, reason to doubt that the extent of variation to which 

the surface markings were subject were as great as has been indicated 

in former publications. The foregoing description may therefore be 

regarded as applying only to the specimens which are represented on 

PI. X by figs. 4 and 5. Two imperfect examples were found associated 

with those which in the publication quoted at the head of this description I have referred to this species and figured in connection with the 

others, but I am not q-uite satisfied as to their specific identity Avith 

Lioplax? endlicki. One of these doubtful specimens is represented by 

fig. 6. The revolving raised lines upon these doubtful specimens are 

much stronger than they are upon the typical examples, but the fine 

revolving and longitudinal lines the presence of which the lens reveals 

are of the same character in both cases. This fact makes me hesitate 

to separate them under different specific names, although I think it possible that this may be made necessary by future discoveries.

This species is evidently referable to the family Yiviparidai, and its 

sinuous outer lip suggests its affinity with Campeloma, but in the subangular character of its volutions and the presence of revolving markings, as well as in general aspect, it resembles ihsLioplax subcarinata, 

of Say, a species now living in North American fluviatile waters. These 

features have suggested its reference to that genus, although nothing 

is known of its most distinctive shell feature, the structure of the 

operculum.

MOLLUSOOIDEA.,

It is hardly to be expected that the Molluscoida would be represented 

in a nonmarine fauna like that of the Bear Kiver formation, but some 

traces of a Bryozoan form have been found attached to shells of Corbula 

pyriformis which were obtained at the Sulphur Creek locality. They 

are too imperfect for description, or even for satisfactory determination, 

but they probably belong to the genus Membranipora of Blainville.

A-NNULOSA.. . CRUSTACEA.

The residue resulting from an acid solution of the pieces of impure 

limestone which were obtained by Mr. Stanton from near Cokeville, 

Wyo., and which have been already several times mentioned in connec- 

,tion with the foregoing descriptions, was found to contain numerous 

specimens of silicified shells of Ostracoda. A quantity of this residue 

was sent for examination to Prof. T. Eupert Jones, of London, whose 

exhaustive studies of these minute crustaceans are everywhere known, 

and he found it to contain an. .unexpectedly large number of forms,
62 THE BEAR RIVER FORMATION. [BULL. 128.

These proved to be of so much, interest that he has published an illustrated article concerning them in the London Geological Magazine. 1

In this collection of Bear Eiver Ostracoda Professor Jones has recognized twelve species and seven genera, of which the following is a

list:

Cypris purbeckensis E. Forbeg. M. simplex n. 8. 

Cypridea tuberculata Sowerby, Cythere inonticula n. 8.

var. wyorningensis. Cytheridea truncata n. s. 

Potamocypris affinis, n. s. C. tennis n. s. 

Matacypris consobrina n. s. Cytherideis ;e<iualis u. s. 

M. subcordata n. s. C. impressa n. s. 

M. cuneiformis n. s.

The unusually large number of both genera and species thus represented and the wide geographical and considerable chronological range 

assigned to some of .them by Professor Jones make it desirable that all 

the recognized forms of this Bear Eiver Ostracoda fauna should be represented in this bulletin. They are therefore all figured on PI. XI, the 

figures all being copies from Professor Jones's, original publication, but 

it is not thought necessary to republish specific descriptions of the 

several forms.

It will be seen by the foregoing list that all except two of these forms 

are described by Professor Jones as new. One of these two he regards 

as a variety of Cypridea tuberculata Sowerby, and the other as identical 

with Cypris purbeckensis E. Forbes, both species having been originally 

described from the Purbeck division of the English Jurassic. It is an 

interesting fact that the fresh-water Jurassic fauna of Colorado2 contains a species of Cypris which Professor Jones refers doubtfully to 

C. purbeckensis i and that Metacypris consobrina and M. subovata of the 

Bear Eiver fauna are closely related to M. forbesii as it occurs in the 

Colorado Jurassic. Others of these Bear Eiver Ostracoda, however, 

are related to members of later faunas.

Professor Jones observes that nearly all these Bear Eiver Ostracoda 

represent either fresh-water or estuarine forms, but that two or three of 

them represent marine forms. This fact is not really discordant with 

the nonmarine character of the associated mollusca. Some of the species 

of the latter class have living representatives which are capable of 

thriving in waters of full marine saltness as well as in those which are 

much less saline, and it is not unreasonable to suppose that those Ostracoda were capable of thriving under similar differences of condition of 

habitat.

PLANT REMAINS.

Certain of the Bear Eiver strata contain an admixture of much carbonaceous matter, and in some of them impure lignite has been found. 

This matter having been of vegetal origin, it is presumable that an

abundant flora existed contemporaneously with the deposition of the

 _ . - - _

1 See Geol. Mag., new ser.,Decade III, Vol. X, pp. 385-391, pi. XT, London, 1893, 

»See Bu}!, T7. S. Geol. Swy. JTo. 29, p. 24,1886.'
WHITE.] BIOLOGICAL DISCUSSION. 63

formation, but it is nevertheless true that plant remains in a classifiable 

condition are extremely rare in its strata. The only remains of this 

kind yet discovered are some minute Chara fruits and the few fragmentary imprints of dicotyledonous leaves which are mentioned on page 22. 

Although the latter are too imperfect for satisfactory description and 

illustration, there can be no question of their dicotyledonous character, 

nor can there be any doubt that they represent an abundant flora. The 

Chara fruits have been studied and published by Prof. F. H. Knowlton,1 

the following being a copy of his description:

CHARA STANTONI Knowlton. 

Plate X, figs. 14,15,1G.

"Fruit (Sporostegium), oblong-elliptical in general outline, slightly 

smaller at the apex, obtuse, nearly one-fifth longer than wide; length, 

0.63mm ; diameter, 0.4Smm. Number of spirals as observed in side view, 

eight or nine; cells furrowed, separated by thin, low, projecting ridges."

BIOLOGICAL DISCUSSION.

The existence of remains of great vertebrate faunas during all the 

other known epochs of the Mesozoic era makes it certain that important 

faunas of that kind existed contemporaneously with the deposition of 

the Bear River formation. Indeed, that such a fauna existed in the 

immediate vicinity of, and in .part within, the body of water in which 

its deposition took place may be legitimately inferred, but up to the 

present time no vertebrate remains are known to have been discovered 

in any strata that are certainly referable to this formation. Therefore 

all further reference .to a vertebrate fauna must be omitted from a biological discussion of the Bear River formation on this occasion.

That an abundant flora, mainly dicotyledonous, existed during the 

Dakota epoch is well known, and if, as the evidence now seems to indicate, the Dakota epoch preceded the Bear River epoch, we may assume 

that an equally important flora existed while the Bear River formation 

was in process of deposition. Indeed such an assumption would be 

hardly less rational if it should yet appear that the Bear River is older 

than the Dakota formation. Still, we have only the indefinite evidence 

of the existence of a Bear River flora that has been mentioned on a 

preceding page. That is, besides the comparatively large amount of 

carbonaceous matter which certain of the Bear River strata contain, 

all the plant remains yet discovered in any of them are a few fragmentary imprints of leaves and a few Chara fruits. Therefore, while we 

can not doubt that a great and varied flora existed during the Bear 

River epoch, and within the Bear River district, we can not now discuss 

its existence as an ascertained biological fact.

XVIII, P|>- 14H43> BiQfiniingtQn, I^d,, 1893.
64 THE BEAR RIVER FORMATION. (BULL 128.

This necessary exclusion of vertebrates and plants leaves only the 

invertebrate fauna to be considered in a biological discussion of the 

Bear Kiver formation. This invertebrate fauna, so far as it is yet 

known, is represented concisely by the following classified list of the 

species, all of which are described and figured on the plates accompanying this bulletin:

The invertebrate fauna of the Bear River formation.

MOLLUSOA.

CONCHIFEEA.

Family OSTREID^. 

Genus OSTREA Linnaeus.

Family MYTILIDyE.

Genus MODIOLA Lamarck.

Family UNIONILXE.

Genua UNIO Retzius.

Ostrea haycleni White.

Modiola pealei W.

Unio belliplicatus Meek. 

U. vetustus M.

Corbicula durkeei M.

Corbula pyriformis M. 

C. en gel man ni M.

Corbulomya tauschii W.

Auricula neumayri W.

Melampus clarkii W.

Rhytophorus priscus M. 

R. meekii W.

Family CYRENIDJE. 

Genus CORBICULA Megerle.

Family COBBULHX2E. 

Genus CORBULA Bruguiere.

Genus -CORBULOMYA Nyst.

GASTEROPODA.

Family AURIC ULID^E. 

Genus AURICULA Lamarck. 

Genus MELAMPUS Montfort. 

Genus RHYTOPHORUS Meek.

Tortacella haldemani W.

Limnsea nitidula M.

Genus TORTACELLA White. 

.; Family LIMNJSnWB.

Genus LIMN^EA Lamarck. 

.-.Genus PLANORBIS Miiller. 

Planorbis (Gyraulus) prsecursoris W.

Family PHYSID^.

Genus PHYSA Praparnaud, 

Physa usitata W, .
WHITE.] BIOLOGICAL DISCUSSION. 65

Family HELICIDJ5.

Geima HELIX Linnseus. 

Helix? !

Genus TORNATELLINA Beck. 

Toruatellina? isoclina White.

Family NERITIDJ3.

Geuus NERITINA Lamarck. 

Neritina naticiformis W.

N. stantoni W.

Family MELANIID^E.

Genus PACHYMELANIA White.

Pachymelania cleburni W. 

P. chrysalis Meek. 

P. chrysalloidea W. 

P. turricula.W.

P?macilentaW.

Genus PYRGUUFERA Meek. 

Pyrgulifera humerosa Meek.

P. stantoni ~W.

Family RISSODXE.

Genns HYOROBIA Hartmauu. 

Hydrobia occulta White.

Genus BYTHJ.NKIVLA Moquin-Taudoii.

Bythinella latentis W.

Genus CHAKYDROBIA Stache. 

Charydrobia stachei W.

Family VIVIPARID^E.

Genus VIVIPARUS Montfort. 

Viviparus couesi W.

Genus CAMPELOMA Rafinesque.

Campeloma macrospira M.

Genus LIOPLAX Troschel. 

Lioplax? endlicbi 'W.

MOLLUSCOIDEA.

Genus MBIMBRANIPORA BLiinville. 

Membrau ipora ? ?

ANNULOSA. 

CRUSTACEA. 1

When one finds it necessary to compare different fossil faunas with 

one another, it is desirable to know as definitely as practicable whether 

in each case the fauna is a full one: in other words, it is desirable to 

know whether all the forms of which a given fauna under investigation 

was originally composed are probably represented by discovered fossil 

remains. It has just been shown that the Bear Eiver fauna includes 

no known vertebrates, and the foregoing list shows that, with the

1 See the list of the Bear River Ostracoda on page 62.

Bull, 128 5
66 ' THE BEAR RIVER FORMATION. [BULL. 128.

exception of the Ostracoda just mentioned, its known invertebrate 

fauna consists wholly of mollusca.

Examining this list with reference to the known general character 

and composition of living faunas, we do not observe any necessarily 

material discrepancy among the branchiferous forms, nor any among 

those of either the littoral or the palustral pulmoniferous forms; that 

is, these divisions of the mollusca are often no more fully represented 

among living nonmarine faunas than they are in the foregoing list. 

There are, however, no specimens among all the collections that have 

yet been made from the Bear Eiver strata which, can with entire confidence be referred to the land pulmoniferous mollusca, and only two 

species have been discovered which are provisionally so referred.

It sliould be borne in mind, in this connection, that remains of land 

mollusca can reach sedimentary entombment only by accidental transportation, while remains of aquatic mollusca have generally been 

entombed Avhere they lived. Therefore it is probable that the land 

mollusca were well represented in the district surrounding the waters 

in which the Bear Eiver formation was deposited. Still, the forementioned discrepancy among the collections of Bear Eiver fossils exists, 

and it will be further referred to or indicated in following discussions. 

It will also in part be shown by a comparison of the foregoing list with 

the lists of other faunas which are given on following pages.

The foregoing statements make it apparent that in discussing the 

fauna of the Bear Eiver formation we are not only practically confined 

to the mollusca, but we are confined to a certain few families. Furthermore, applying the accepted criteria of past aqueous conditions, we 

find that all these molluscan forms fall into the nonmarine category; 

that is, they are forms the living congeners of which are denizens of 

either brackish water or fresh water or of the land, there being no representatives among them of forms that now live exclusively in marine

waters.

It is clearly apparent, from an examination of the important and 

somewhat numerous collections of the Bear Eiver molluscan fossils 

which have been brought to the National Museum, that forms which 

represent all the varieties of habitat just referred to, including remains 

of both branchiferous and pulmoniferous mollusca, are intimately commingled in at least a part of the Bear. Eiver strata. This fact is 

especially apparent to the geologist who has himself collected the fossils of that formation. The collector of fossils from the Bear Eiver 

formation also observes that the layers which contain Ostrea haydeni 

contain comparatively few other forms, and that such purely fresh-water 

forms as Unio, Yiviparus, etc., are rarely, if ever, commingled with 

them. It is true, however, that some of the forms which are found in 

intimate association with the Ostrea are also found in similar association 

with those which we call purely fresh-water forms; but this is taken to 

indicate that the associate forms referred to were capable of thriving
WHITE.] BIOLOGICAL DISCUSSION. 67

in both saline and fresh waters, while the Ostrea could exist only in 

saline waters, and the Unio, Viviparus, etc., only in fresh waters.1

This apparently, and in part really, incongruous commingling of the 

fossil remains which constitute the Bear River molluscan fauna is of 

special interest in connection with its study, and the probable causes of 

it have also a general relation to the possible geographical dispersion 

of specific and generic molluscan forms, which subject also will in part 

be discussed on following pages.

The remarks which I propose to make upon both these subjects will 

be better understood by some explanatory references to certain of the 

principles and criteria upon which they are based and which are tacitly 

understood by geologists, although they are rarely enunciated in their 

writings.

Ill discussing the evidence of past aqueous conditions, which by comparison with present conditions are known to have attended the production of the various sedimentary formations of the earth, it has 

become customary among geologists to apply the term nonmarine to 

those bodies of water which are either fresh or less saline than are the 

oceans and the seas which directly and freely communicate with them. 

It has also become customary to apply the same term to the fossil faunas 

which present inherent evidence of having existed in such bodies of 

water, as well as to the form'ations which were deposited in them. In 

some cases the entire aquatic fauna whose remains are found to characterize a given uonmarine formation is composed of such forms as 

plainly indicate that the waters in which they lived and in which that 

formation was deposited were wholly fresh. In other cases the fossil 

remains indicate that the waters were more or less saline, and in still 

others there is a commingling, or an association, of forms which are 

properly regarded as characteristic of fresh and saline waters, respectively. Eeference is here made especially to the mollusca, because it 

is with the remains of those animals more than with remains of any 

others that the geologist has to deal in his investigations of the distinguishing characteristics of nonmarine formations.

The remarks here offered are also restricted to such nonmarine 

deposits as have been laid down in more or less broad bodies of water, 

those which may have been deposited in tiuviatile waters not being at 

present considered. A large proportion of the now living denizens of 

fresh waters inhabit rivers and streams, and such was doubtless the case 

in former geological epochs; but fltiviatile deposits are so extremely 

rare among geological formations that little reference need be made to 

them in discussing those of nonmarine origin.

In the case of formations which are unhesitatingly referred to a freshwater origin all the contained fossil remains of branchiferous mollusca

1 The frequent association of specimens of Pyrgulifera and Pachymelania with Ostrea haydeni 

suggests that these Melanians lived congenially with the Ostrea. A similar association of Melaniu 

with Ostrea and Anoinia has been observed in the Laramie formation.
68 THE BEAR RIVER FORMATION. [BULL. 128.

are those which pertained to forms whose living congeners are incapable 

of thriving in waters containing an appreciable amount of salt; but 

among the faunas of other nonmarine formations there is usually a 

B greater or less number of forms whose living congeners are capable of 

adapting themselves to both brackish and fresh waters. Furthermore, 

certain forms, such as Ostrea and Anomia, for example, are not unfrequently found among nonmarine faunas, although all known living 

members of these families are, and doubtless all their members always 

have been, incapable of permanent existence in waters which do not 

contain an appreciable amount of salt, while they are capable of thriving as well in waters of full marine saltness as they are in brackish 

waters.

It is the branchiferous mollusca that have been particularly referred 

to in the preceding paragraphs. These, of course, require constant 

aqueous submergence, and, as a rule, their remains were immediately 

entombed in the sediments of the waters in which they lived, those 

sediments having constituted the strata in which their remains are 

found. It is usually the case, however, that a nonmarine fossil fauna 

contains a greater or less proportion of the remains of pulmoniferous 

mollusca, including those of terrestrial, as well as those of littoral and 

palustral, habittit. Fossil remains of all, or a part, of these three 

kinds of pulmoniferous mollusca are so generally found commingled 

with those of the various kinds of branchiferous mollusca that, as a 

rule, one expects to find more or less of such remains in every nonniarine formation.

The littoral pulmoniferous mollusca here referred to are such forms as 

the Auriculidse; for example, which live in the shallows, or within reach 

of the spray, of saline waters only, and it is a significant fact that 

fossil congeners of these mollusca have been found only in association 

with other evidence than that afforded by the structure of their shells

that the deposits containing them were, at least in part, laid down in 

brackish waters. Those referred to as palustral pulmouiferous mollusca 

are such forms as the Physidre and Limnoeidae, for example, which live 

in the shallow fresh waters of ponds and marshy shores. No explanation as to the conditions of habitat of land mollusca is deemed necessary, 

but it may be remarked that the sedimentary entombment of their 

remains was always more or less accidental.

Applying these general statements to the Bear River formation, we 

do it with reference to that commingling of remains of fresh-water and 

brackish-water branchiferous, and of littoral and palustral pulmoniferous, mollusca which has just been referred to and which was more 

definitely stated in a previous paragraph. The very large proportion 

of the members of the Bear Eiver rnolluscan fauna, which indicates a 

brackish-water habitat, and the general distribution of those forms 

throughout the whole formation, leave no room for reasonable doubt 

that it was deposited in a brackish-water lake or sea which was more
WHITE.] BIOLOGICAL DISCUSSION. 69

or less completely cut off from open marine waters. One therefore 

naturally desires to inquire what were the conditions under which the 

commingling was accomplished.

Such an inquiry is appropriate not only in the case of the Bear River 

formation, but equally so in the case of many other nonmarine formations, as may readily be seen by the commingling of fresh-water and 

brackish-water forms in their respective fossil faunas. The great Laramie formation, with which the Bear Eiver formation was formerly confounded, presents a case of this kind which is all the more remarkable 

because of the great geographical extent of the area which it occupies. 

Unfortunately, however, our present knowledge of the subject is so 

meager that such an inquiry can result in little more than a few suggestions.

Such a commingling of molluscan remains as is observed in the case

of the Bear Eiver fauna may imply, first, that they were accidentally 

brought together; second, that the species which they represent lived 

together in one and the same congenial habitat; or, third, that fresh and 

brackish waters periodically alternated upon certain portions of the 

great aqueous area within which the formation was deposited.

We may, as already intimated, properly assume that many of these 

Bear Eiver species were capable of living in waters of varying degrees 

of saltness, and therefore that a large proportion of the whole fauna 

lived and thrived together, and consequently that their remains were 

entombed together. We may also" assume that by the action of winds, 

or of inflowing or other currents, the shells of pulmoniferous mollusca 

were frequently drifted out into the open waters, where they sank and 

became intoinbecl among the shells of gill-bearing forms.

We can not, however, assume that such branchiferous forms as Ostrea 

liaydeni on the one hand and Unio belliplicatus, U. vetustus, and Vimparus couesii on the other were capable of living and thriving together. 

Therefore any promiscuous commingling of such categories of forms 

as these must have been accidental, but we must assume that their 

respective prevalence in alternating layers has been the result of alternation of saline and fresh waters that is, an alternation of congenial 

conditions for each within certain portions of the great aqueous 

area in which the formation was deposited.

If there were any evidence that the shells of the fresh-water branchiferous members of the Bear Eiver fauna were drifted to the places of 

their entombment, the question as to the cause of their commingling 

with the brackish-water forms would be a simple one, but these shells 

are too heavy to have been drifted by any current that would not have 

produced in the sedimentary deposits ample evidence of its action, and 

no such evidence has yet been discovered. Moreover, the conditions 

of their entombment and preservation, together with their general distribution throughout the formation, present as good evidence that the 

mollusca which they represent lived and died where their remains are 

found as there.is in the case of the brackish-water forms.
70 THE BEAR RIVER FORMATION. [BULL. 128.

The general character of the Bear Kiver molluscau fauna indicates 

that the average saltness of the body of water in which it lived, although 

variable in different parts, as already mentioned, was practically the 

same from, the beginning to the end of the epoch. A supply of fresh 

water to the Bear Kiver sea of course came from surface drainage, but 

what was the source of its supply of salt and how that general average 

was maintained we can only conjecture. It may have been that a sufficient amount of salt was retained from the marine waters which prevailed over the same area during the preceding epoch, and that this 

was sufficiently supplemented by surface drainage and evaporation to 

balance the loss by outflow, or it may have been that 'supplies of salt 

came by periodical incursion of waters from an adjacent marine area; 

but we have no conclusive evidence on any of these points.

That there were the numerous alternations of fresh and saline areas 

in various parts of the Bear Kiver sea which have been mentioned, and 

that these alternations occurred at intervals during the whole epoch of 

its existence, is sufficiently obvious. The long duration of that epoch is 

indicated by the aggregate thickness of the Bear Kiver formation, 

which is about 3,000 feet. It is also obvious that the influx of river 

freshets is not sufficient to explain these alternations of fresh with 

brackish waters,because in the strata containing the fresh-water forms 

there are no sufficient physical indications that such freshets occurred. 

Besides this, the condition of those fossils and of the strata in which 

they occur is such as to indicate that a fresh-water fauna became 

established in certain parts of the Bear Kiver sea and thrived there 

until the congeniality of its habitat was destroyed or it was shifted to 

other parts by the afflux of saline water. It is natural to infer that the 

main portion of such a body of water as was the Bear Kiver sea was at 

all times too saline for fresh-water inollusks to thrive in, and to assume

that such mollusks found a congenial habitat only along certain portions of its borders. 1

Such a shifting of conditions of habitat as has just been mentioned 

was necessarily due to shifting physical conditions, chief among which 

were probably changes in the surrounding drainage system and in the 

bottom and shore-line of the Bear Kiver sea.

THE BEAR RIVER FAUNA COMPARED WITH OTHER AMERICAN

FOSSIL FAUNAS.

It has been shown that the Bear River fauna, so far as it is known, 

consists wholly of invertebrates, and that with the exception of some 

Ostracod crustaceans they are all mollusks. For the present purpose 

there is no necessity for comparing this invertebrate fauna with much 

the larger part of the fossil faunas of North America further than to

.'Observations hitherto made of the Bear Kiver formation do not forbid such an assumption, but 

both fresh-water and brackish-water forms have been found so distributed throughout the broad 

Laramie formation as seemingly to forbid the assumption that the former lived only along the borders 

of the Laramie aea.
WHITE.] COMPARISON OF FAUNAS. 71

demonstrate the fact of its nonuiarine origin. Besides this, iionmarine 

fossils are of such rare occurrence in Paleozoic formations that comparisons of the Bear Kiver fauna must necessarily be confined to the 

known Mesozoic and Cenozoic faunas. It will be sufficient for the 

present purpose to compare it with that of the Laramie formation, 

those of the Wasatch, Green Kiver, and Bridger formations collectively, that of the Dakota formation, and that of the upper part of the 

Jurassic as it is kuown in Colorado and Wyoming, beginning with the 

fauna of the last-named strata.

The fresh-water Jurassic invertebrate* of Colorado and Wyoming. 1

MOLLUSCA. 

CONCH1FERA.

Family UNIONID^.

Genus UNJO Retains. 

Unio felchii White. 

U. toxonotns W.

U. macropisthus W. ' 

U. iridoides W. 

U. lapilloides W. 

U. steward! W.

GASTEROPODA.

Family

Genus LIMN^EA Lamarck. 

Limnsea ativnncula W. 

L. consortis W. 

L. ? accelerata W.

Genus PJLANOKBIS Miiller.

Planorbis veturnus Meek and Hayden?

Genus VOKTICIFEX Meek. 

Vorticifex stearnsii W.

Family VALVATID^E.

Genus VALVATA Miiller. 

Valvata scabrida M. anclH. ?

CRUSTACEA.

OSTRACODA.

Metacypris forbesii Jones. 

Metacypris ? 

Darwinula leguminella Forbes. 

Cypris purbeckensis? F. 

Cypris ? 

Cypris ? .

1 This list is compiled from Bulletin Xo. 29 of the IT. S. Geological Survey. The following species, I 

which are included with Jurassic forms in that bulletin, are omitted from this list because they came 

from a more northern region, and it is not yet certain that they really came from the Jurassic : Unio 

nucalis Meek and Hayden, Viviparus gilli M. and H., Lioplacodes veternus M. and H., and Neritina 

nebrascensis M. and H. These omissions, however, will not affect the comparisons of this fauna with 

that of the Bear liiver formation which are made in this bulletin.
72 THE BEAR RIVER FORMATION. [BULL. 128.

Upon examination of the foregoing list of Jurassic mollusca two 

significant facts are apparent: First, they are all of such forms as are 

without hesitation referred to a fresh-water habitat; second, although 

they are specifically distinct from any others, they are all closely related 

to species which occur in several other fresh-water formations of later 

age as well as to fresh-water species which are now living. These facts, 

together with the absence from the Jurassic fauna of brackish-water 

inolluscan forms, which is shown by the foregoing list, and the further 

fact that it is mainly such forms as were capable of living in brackish 

water that characterize the Bear Eiver fauna, render a comparison of 

the two faunas of comparatively little value for present purposes.

The foregoing, remarks apply to the mollusca, but there is an interesting relationship between the Ostracoda of the Bear Eiver formation 

and those of the Jurassic strata of Colorado and Wyoming. The character of this relationship may be seen by comparing the closing entries 

of the preceding list with the list of the Bear Eiver Ostracoda on page 

62, and also by comparing the figures of the latter on PI. XI of this bulletin with those of the former on PL IV of Bulletin No. 29 of the United 

States Geological Survey.

This relationship of the Bear Eiver Ostracoda to those of the freshwater Jurassic of Colorado is very interesting, because certain of the 

forms in each case are respectively similar, and because no similar 

forms are yet known in any other of the North American formations. 

It is hardly probable, however, that much important geological information will be derived from these facts, especially in view of the extreme 

rarity of the Ostracoda in all the known North American faunas of 

the later formations. Indeed, they are so rare in those formations that 

it has not been thought necessary to enumerate them in the following 

lists.

The known invertebrate fauna of the Dakota formation is so meager

that only a limited comparison between it and that of the Bear Eiver 

fauna can be made; but the fact that the Dakota formation is the only 

one besides the Bear Eiver which contains a species referable to Pyrgulifera makes such a comparison desirable. I have elsewhere shown 

that of the invertebrate fossils which have been published as having 

been obtained from the Dakota formation, a part are plainly remains of 

denizens of marine waters, and that the others are remains of denizens 

of either brackish or fresh waters.1

No member of the Bear Eiver fauna being regarded as indicating a 

marine habitat, the names of only the fresh-water and brackish-water 

species of the Dakota invertebrates are given in the following list:

 See "Notes on the invertebrate fauna of the Dakota formation, with descriptions of new mollusoan 

'forms." Ann. Kept. U. S. National Museum for 1892, pp. 131-138 and one plate.
WHITE.] COMPARISON OF FAUNAS. 73

Invertebrate fauna of the Dakota formation.

MOLLTJSCA. 

CONOHIFEEA.

Family UNIONID^E. 

Genus MARGAIUTANA Schnmacner.

Margaritana nebrascensis Meek.

Genus UNIO Retzius. 

Unio barbouri White.

U. ? W.

Family CORBICULID^E.

Genus CORBICULA Miihli'eldt.

Cyveua [Corbicula?! dakotaeusis Meek aud Haydeu.

Family CORBULID^.

Genus COKBULA Bruguiere. 

Corbula hicksii W.

GASTEEOPODA.

Family CERIPHASIIDyE. 

Genus GONIOBASIS Lea.

Goniobasis jetf'ersonensis W. 

G. ? W.

Family MELANIID2E.

Genus PYRGULIITERA Meek. 

Pyrgulifera meekii W. *

Family VIVIPABIDJE.

Genus A^IVIPARUS Montfort. 

Viviparus hicksii W.

Although, with the exception of Margaritana, all the genera of the 

foregoing list of Dakota species are represented in the Bear Eiver 

fauna, the Dakota fauna as a whole is not such as to suggest the 

equivalency of the two formations. There are, however, two significant 

facts to be observed in this connection. First, there is stratigraphical 

evidence that there is no great difference in the geological age of the 

Bear Eiver and Dakota formations; second, in America only these two 

formations are known to contain remains of Pyrgulifera.

The next noninarine fauna in ascending chronological order with 

which the Bear Eiver fauna may be compared is that of the Upper 

Cretaceous Dunvegan series of Canada, the fauna of which has been 

briefly discussed on pages 28 and 29. It was there shown that the 

character of the fauna, although it includes some molluscan forms 

which are closely related to certain members of the Bear Eiver fauna, 

is not such as to indicate an identity of the formations which respectively contain those faunas. Besides this, the Dunvegan fauna is not 

yet known to contain any of the molluscan genera which are especially 

characteristic of the Bear Eiver fauna.
74 THE BEAR RIVER FORMATION. [BULL. 128.

It is not tliougi.it necessary to compare the Bear Eiver iaima with 

that of the Belly Eiver series of Canada, because of the close faunal 

relationship of that series with the Laramie formation.

The fauna with which, above those of all other North American formations, it is desirable to compare the Bear Eiver fauna is that of the 

great Laramie formation, this being the one with which the Bear Eiver 

formation has long been confounded. The following is a list of the 

invertebrate species which are now assigned to the Laramie fauna 

proper. It is given here for comparison with that of the Bear Eiver 

fauna, which is given on pages 64 and 65.

Invertebrate fauna of the Laramie formation. l

MOLIAJSCA. 

CONCHIFEEA.

Family OSTREID^. 

Genus OSTREA. Linmens:

Ostrea glabra Meek and Hayden.

O. subtrigoualis Evans and Shumard.

Family ANOMIID^.

Genus ANOMIA Linnaeus. 

Anomia micronema Meek.

A. gryphorhynchus M.

Family MYTILIDJS.

Genus MODIOLA. Lamarck.

Modiola (Brachydoiites) regularis White.

M. (B.) laticostata W.

Family UNIONID^E.

Genns ANODONTA Cuvier. 

Anoclonta parallela W. 

A. propatoris W.

Genus UNIO Retains. 

Unio aldrichi W. 

U. brachyopisthus W". 

U. couesii W. 

U. cryptorhynchus W. 

U. dan* M. and H. 

U. deweyanus M. and H. 

U. endlichi W. 

U. goniambononatus W. 

U. gonionotus W. 

U. holmesianus W. 

U. primsevus W. 

U. priacus M. and H.

1 In compiling this list I have, of course, omitted the species which belong to the Bear Eiver fauna, 

all of which were formerly referred to the Laramie. The following species were also formerly referred 

to the Laramie, but I have omitted them from this list because I now understand them to belong to 

the overlying Wasatch formation, in the list of which they will appear on a following page: Unio 

mendax White, Pisidium saginatuin W., Haoroeyclis spatiosa Meek and Hayden, Helix (Spatula?) 

sepulta W., JET. (Trlodopsis?) evanstonensls W.\ Hydrobia recta W., and H. utahensis W.
\vitiTE.] . COMPARISON OF FAUNAS. 75

U. proavitus White. \ ;

U. proplieticus W.

U. senectua W.

U. subspatulatns Meek.

.Family CYRENIDvE.

Genus SPH^ERIUM Scopoli.

Sphairium formosum Meek and Haydeu.

S. planum M. arid H.

S. recticardiriale M. and H.'.

S. subellipticum M. and H.

Genus COKBICUI.A Mergerle. 

Corbicula augheyi W. 

C. berthoudi W. 

C. cardiniajformis W. 

C. cleburni W. 

C. cytheriformis M. and H. 

C. fracta M. 

C. macropistha W. 

C. nebrascensis M. and H. * 

C. obesa W.

C. occidentalis M. aud H. 

C. planumbonata M. 

C. subelliptica M. and H. 

C. ttmbonella M.

Family COEBULID^:.

Genus CORBULA. Brnguiere.

Corbula subtrigonalis M. and H. 

C. undifera»M.

GASTEEOPODA.

Family 

Genns LIMX/EA Lamarck. 

Limnaea (Pleurolimntea) teuuicarinata M.

Genns PLANORBIS Miiller.

Planorbis amplexus M. and H.

P. convolutus M. and H.

P. kauabensis W. ' .

P. planoconvexus M. and H.

Family PHYSID^E.

Genns PHYSA. Draparnand. 

Physa copei W.

P. telix W.

P. kanabensis W.

Genus HUMNUS Adanson. 

Bulinus atavus W.

B. longiusculus M. and H. 

B. rhomboideus M. andH. 

B. snbelongatns M. and H.

'No representative of the Auricnlidte, which family is HO well represented jn the Bear River fauna, 

has been found in the Laramie formation. Therefore this list begins with the Limn tei dtp.
76 THE BEAR RIVER FORMATION. [BULL. 128.

Family ANCYLID^E.

Genus ACROLOXUS Beck. 

Acroloxus minutus Meek and Hayden.

Family VITRINID.E.

Geuus VITRI.NA Draparnand.

Vitrina? obliquaM. and H.

Genus HYALINA Agassi/.

Hyalina? occideutalis M. and H.

Family HELICID.E. 

Genus HELIX Linnibus.

Helix (Strobilia?) kauabensis White. 

H. vetustus M. and H.

Genus THAUMASTUS Albers.

Tliaumastus limmeiforinis M. and H.

Genus COLUMXA* Perry. 

Columna teres M. and H. 

C. vermicula M. and H.

Family NERITIDJE.

Neritina (Velatella) baptista W.

N. bruneri W. . - '

N. volvilineata W.

Family CERITHIIDJG.

Genus CERITHIDEA Swainson. 

Cerithidea nebrascensis M. and H.

Family MELANIIDJE.

Genus MELANIA Lamarck. 

Melania insculpta Meek. 

M. wyomingensis M.

Genus MELANQ'PSIS Ferussac.

Melanopsis americana W.

Family CERIPHASIID^.

Genus GONIOBASIS Lea. 

Goniobasis convexa M. and H. 

G. gracilenta M. and H. 

G. invenusta M. and H. 

G. omitta M. and H. 

G. nebrascensis M. and H:. 

G. subliBvis M. and II. 

G. tenuicarinata M. and H.

Geutis CASSIOPELLA White. 

Cassiopella turricula W.

Family RISSOID^.

Genus HYDROBIA Hartmann.

Hydrobia anthonyi M. and H.

H. eulimoides M.

H. subconica M.

H. warrenana M. and H. .
WHITE.] COMPARISON OF FAUNAS. 77

Genus MICROPYRGUS M. 

Micropyrgus minutulus Meek and' Hayden.

Family VIVIPARID^. 

Genus VIVIPARUS Montfort

Viviparus conradi M. and H. 

V. leai M. and H. 

V. leidyi M. and H. 

V. peculiaris M. and H. 

V. plicapressus White. 

V. prudentius W. 

V. raynoldsianus M. and H. 

V. vetustus M. and H. 

V. trochifonnis M. and H. 

V. ionicus W.

V. panguitchensis W.

Genus TuLOTOMA Haldeman.

Tulotoraa tbonipsoni W.

Genus CAMPELOMA Kafinesque.

Campeloma multilineata M. and H.

C. multistriata M. and H.

C. producta W. .

C. vetula M. and H.

Family VALVATTD^E.

Genus VAT, VAT A Miiller. 

Valvata montanaensis Meek. 

V. parvula M. and H. 

V. subumbilicata M. and H.

ANNTJLOSA.

INSECTA.

Corydalites fecundum Scudder. 1

It will be seen that with the exception of some insect egg masses the 

Laramie invertebrate fauna as'represented by the foregoing list consists 

entirely of molluscan remains. Doubtless some such fresh-water and 

brackish-water crustaceans as are known to have existed in late Cretaceous and early Tertiary time lived in the Laramie sea, and the 

discovery of remains of the Ostracoda especially might have been 

expected, but no such remains have yet been discovered. In comparing 

the Laramie fauna with the Bear Eiver fauna, so far as both are now 

known, we are therefore confined to the mollusca.

Beginning this comparison with the Conchifera, we find a good degree 

of similarity so far as genera and families are concerned, and no striking contrast between them is observed except as regards the number 

of species which represent certain of the genera, Unio and Corbicula, 

for example, and the absence of Anomia from all the Bear Kiver collec1 These remains consist only of egg masses.
78 THE BEAR RIVER FORMATION. [BULL. 128.

tions, while that genus prevails in the Laramie. The only types among 

the Bear Eiver Corichifera which need be contrasted with any of those 

of the Laramie are those which are represented by Unio belliplicatus 

and Corbula pyriformis, respectively. This contrast, however, is one 

only, or mainly, of unusual size and obesity in the case of the Corbula, 

and of external ornamentation in the case of the Unio.

The contrast between the Bear Eiver and Laramie faunas is much 

greater as regards the Gasteropoda. Upon beginning a comparison of 

the members of this class of the Mollusca, as represented by the Bear 

Eiver and Laramie faunas, we are met by the entire absence of the 

AuriculidaB from the Laramie fauna, although that family is represented 

in the Bear Eiver fauna by five species and four genera. This contrast 

is still more conspicuous because two of those genera are yet known 

only in the Bear Eiver fauna.

The pulmoniferous mollusca are much more fully and variously represented in the Laramie fauna than they are in. the Bear Eiver fauna. 

This is especially the case with those of land habitat, the paucity of 

whose remains in the Bear Eiver fauna has already been pointed out. 

The suggestion has also been made that this paucity was due to a want 

of favorable conditions for the preservation of their remains in the Bear 

Eiver sediments. Whatever may have been the facts, in this case, the 

few pulmoniferous mollusca whose remains have been discovered in the 

Bear Eiver strata were of such a character as to be not inconsistent 

with such a fauna as that of the Laramie. Therefore the observable 

contrast between the Bear Eiver arid Laramie faunas, as regards the 

pulmoniferous mollusca exclusive of the Auriculidae, is one of fullness 

and paucity of representation rather than of diversity of types.

The two Bear Eiver species of the NeritidaB, and two of the three 

Laramie species belonging to that family, differ too little in generic 

characteristics from other Cretaceous, Tertiary, and living forms to

attract particular attention, but one of the Laramie species, Neritina 

(Velatella) baptista, belongs to an extinct subgenns. This 1 subgenus is 

not yet known to occur in the Bear Eiver fauna, but it is found in that 

of the immediately overlying Colorado formation, and it probably 

existed somewhere during the Bear Eiver epoch.

As regards fauna! types, the most conspicuous contrast between the 

Laramie and Bear Eiver faunas is observable in the family Melaniidee. 

In the Laramie fauna the genera Melania, Goniobasis, Cassiopella, and 

Melauopsis are represented, but no representative of any of those 

genera is known in the Bear Eiver fauna. 1 In the latter fauna, as it 

is now known, the family Melaniida3 is represented by only two genera, 

Pyrgulifera and Pachymelania, neither of which genera is known to 

occur in any other North American fauna. The conspicuous contrast

'It is true that some authors have referred certain forms to Melanopsis which are congeneric witli 

Pyrgulifera humerosa, and that I have formerly referred those Bear Kiver species to Goniobasis which 

I now assign to I'achymelania, but the true generic characteristics of those forms are shown on preceding pages of this bulletin.
WHITE.] COMPARISON OF FAUNAS. 79

between the Laramie and Bear Kiver faunas which is thus presented 

by the Melaniid^e is made still more conspicuous by the abundance of 

individual shells of the different species of those genera in the Bear 

River strata, and by the fact that those species are among the most 

characteristic members of the Bear River fauna.

The remaining members of the Laramie fauna to be compared with 

the Bear River fauna are all branchiferous gasteropods. They belong 

to genera which occur also in the Bear River fauna or to closely allied 

genera. Therefore this part of the Laramie fauna does not present a 

strong contrast to the Bear River fauna, except as regards the greater 

number of Laramie species, especially of the Viviparidae. These correspondencies between the Laramie and Bear River faunas are not, 

however, of such a character as necessarily to suggest the geological 

equivalency of the formations containing them; and besides this, the 

contrasts which have been mentioned are inconsistent with such 

equivalency.

The Wasatch, Green River, and Bridger formations come next in 

geological age to the Laramie among JSTorth American nonmarine formations, and they are by all geologists referred to the Eocene. All 

three of these formations are so intimately connected with one another, 

both by faunal similarity and the ranging of certain species from one 

to another, that for the present purpose the molluscan faunas of all of 

them will be represented together in the following list. It will also 

be seen by the footnotes accompanying the list that certain of the 

fresh-water Laramie species range up into the lowest of these three 

formations.

Tlie Molluscan fauna of the Wasatch, Green River, >and Bridger

formations.

CONCHIFERA.

Family UNIONID^E.

Genus UNIO Retzius. 

Unio clinopisthus White. 

U. haydeni Meek. 

U. mendax W. 

U. rectoides W. 

U. shoshonensis W. 

U. teUinoides Hall. 

U. washakiensis M.

Family CYRENID/E.

Genus SPH^ERIUM Scopoli. 

Splnerium formosum Meek and Hayden. 1

Genus PISIDIUM Pfeiffer. 

Pisidium sagiuatum W.

'Survival from the Laramie epoch. '
80 THE BEAR RIVER FORMATION. [BULL. 128.

GASTEROPODA.

Family LIMN^EID/E.

Genus LIMN.EA Lamarck. 

Limnaea minuscula AVhite. 

L. similis Meek. 

L. vetusta M.

Genus PLANOKBIS Miiller. 

PlaBorbis sequalis W.

P. cirratus W.

P. convolutus Meek and Hayden. 1

P. militaris W.

P. spectabilis M.

P. utahensieM.

Family PHYSID^E.

Genus PHYSA Draparnaud. 

Physa bridgerensis M.

P. bullatula W. 

P. kanabensis W.' 

P. pleuromatis W.

Genus BULINUS Adanson.. 

Bulinus atavus W. 1

Family ANCYLID^.

Genus ACROLOXUS Beck. 

Acroloxus actinophorus W.

Family VITRINID^E-.

Genus MACKOCYCLIS Beck.

Macrocyclis spatiosa M. and H.

Family .HELICID^E.

Genus HELIX LiuniBiis.

Helix (Triodopsis?) evanstouensis W. 

H. (Arianta?) riparia W. 

H. (Aglaia?)peripheriaW.

H. (Patula?) sepulta W. 

H. veterna M. and H.

Family PUPIDyE.

Genus PUPA Lamarck. 

Pupa leidyi M. 

P. arenula W. 

P. atavuncula W. 

P. incolata W.

Family SUCCINID^E.

Genus SUCCINKA Draparnaud. 

Succinea papillispira W.

Family. CERIPHASIID2E.

Genus GONIOHASIS Lea. 

Goniobasis filifera W. 

G. nebrascensis M. and H. 1 

G. teuera Hall. 

G. tenuicarinata M. and H. 1

1 Survival from the Laramie epoch.
WHITE.] COMPARISON OF FAUNAS. 81

Family KISSOIDJL

, Genus HYDROBIA Hartmanu. 

Hydrobia recta White. 

H. utakensis W.

Genus BYTHINELLA Moquin-Tandou.

Bythinella gregaria Meek.

Genus MICROPYRGUS Meek.

Micropyrgus miuutulus Meek and Hayden. 1

Family VIVIPARID^E.

Genus VIVIPARUS Moutfort. 

Viviparus nauns W. 

V. paludinteformis Hall. 

V. trOchiformis M. and H. 1 

V. wyomingensis M.

' The foregoing list of Eocene noumarine mollusca lainly shows that 

any comparison of the fauna which it represents with the Bear Eiver 

fauna must be mainly one of contrast; and the contrast is all the greater 

because of the absence from this later fauna of any other than purely 

fresh-water forms. It is also apparent that this fauna is not only closely 

related to the fresh water and land portion of the Laramie fauna by a 

consider able number of specifically identical forms, but it is also closely 

related to the living fresh-water and land molluscan fauna of Forth 

America by the generic identity of a very large majority of its members. On the contrary, the Bear Eiver fauna contains only half a dozen 

forms that can be regarded as closely related to any of the species 

enumerated in the foregoing list, these being in part palustral pulmoniferous and in part fresh-water branchiferous mollusca. Geologically 

such a.comparison has the effect of showing that the Bear Eiver fauna, 

which was originally assigned to the Tertiary, is conspicuously different from any North American Tertiary fauna.

In making a general comparison of the Bear Eiver fauna with the 

other nonmarine fossil faunas of North America, as represented by the 

three foregoing lists and the remarks which accompany them, it is desirable to recall attention to those features of the Bear Eiver fauna by 

which it differs conspicuously from all the others. Eeference is here 

especially made to the Auriculidae and -Melaniidae, because it is the 

members of these two families that give the Bear Eiver fauna its most 

distinctive character. This faunal character is all the more conspicuous because, of the six genera which represent those two families, only 

two of them' are known in any other North American fauna, either 

fossil or recent. To the geological investigator this faunal character 

of the Bear Eiver formation is physically conspicuous, because of the 

comparative abundance of the shells of some of the species belonging 

to the two families just mentioned.

1 Survival from the Laramie epoch.

Bull. 128 6
82 THE BEAR RIVER FORMATION. [BULL. 128.

Iii view of the similarities and contrasts between such faunas as have 

been discussed in the preceding paragraphs, one is naturally led to an 

inquiry as to their causes. It is not to be expected that all such inquiries can be satisfactorily answered, but the following facts and suggestions are deemed worthy of consideration.

Marine waters have been of world-wide extent ever since life began 

to exist in them, and interruptions of their physical continuity during 

the whole.course of geological time have never been more than partial 

or local. It is therefore easy to comprehend how unbroken genetic lines 

of descent may have occurred in marine waters throughout the whole 

range of geological time. It is, however, much more difficult to understand how such lines of descent could have been preserved in the case 

of nomnarine faunas, especially those of their fresh-water branchiferous 

members, because a change to dry land or to a saline condition of habitat would have been fatal to them. This difficulty is increased when 

we take into consideration the fact that fresh-water molluscau faunas 

similar to those now living have abounded ever since the earlier epochs 

of Mesozoic time, and that many of them contain forms so closely like 

members of living faunas that it is often impracticable to clearly diagnose them as specifically different. Equally embarrassing is the further fact that the greater part of the ancient ichthyic types which have 

survived to the present day are found among fresh-water fishes.

In view of numerous facts brought out by paleontological investigation, there seems to be no room for reasonable doubt that in the course 

of geological time many forms have been developed independently, or 

along separate genetic lines, the fossil remains of which present no 

features by which they can be satisfactorily assigned to separate genera; 

and it is even conceivable that some of the admitted fossil species have 

had a similarly independent origin. As a rule, however, I think it 

necessary to assume that closely similar fossil faunas, or important 

divisions of the same, Lave a more or less close genetic relationship, 

notwithstanding the frequent difficulty of understanding how such a 

relationship could have been maintained.

In a former publication ' I have suggested that genetic lines of descent 

of fresh-water branchiferous animals could have been, and in most cases 

probably were, preserved by means of the persistence of rivers from 

epoch to epoch of geological time, thus securing a continuance of congenial aquatic habitat through a series of geological epochs; that is, 

in the process of time lakes inhabited by branchiferous fresh-water 

faunas naturally became drained by the corrasive deepening of the 

channels of their outlets, but those faunas found a congenial habitat in 

the resulting fluviatile waters, which debouched either into other lacustrine waters or more or less directly into the sea.

This theory of the manner of genetic descent of fresh-water faunas 

seems to apply well to the fresh-water and laud portion of the Laramie

1 Third Ann. K«pt. U. S. Geol. Surv., p]>- 75-80, 1883.
WHITE."] COMPARISON OF FAUNAS. 83

molluscan fauna, and also to the whole fauna of the Wasatcli, Green 

Biver, and Bridger formations as represented by the foregoing list. 

The collective fauna of the three last-named formations shows an intimate relationship to the Laramie fauna, not only by a general similarity 

of types but by identity of certain of the species. It i s therefore natural 

to infer that the fauna of these Eocene formations was, at least in part, 

derived by direct genetic descent from the earlier Laramie fauna.

Furthermore, because so large a part of the generic and subgeneric, 

as well as more general, types of fresh-water and land niollusca of those 

Eocene formations, and also of the Laramie, are identical with forms 

which are now living in the great area drained by the Mississippi Biver 

system, it is equally natural to infer that the latter were derived by 

direct descent from their' Eocene and Laramie congeners; that is,it is 

assumed 'that the fluvial perpetuation of the outlet or outlets of the 

Laramie sea conveyed its fresh-water fauna in part to the Eocene lakes

and in part retained it in fluviatile waters, some of which are flowing 

to-day as a part of the Mississippi drainage system. This view also 

finds support in abundant geological evidence that after the Laramie 

epoch no marine waters prevailed over that great interior portion of the 

continent in which the formations referred0 to occur.

It is much more difficult to understand how the 'Laramie sea may 

have obtained its fresh-water fauna than how its distinctive types 

may have been genetically perpetuated; and it is equally difficult to 

understand how genetic lines of descent could have been so perpetuated from those Jurassic and Bear Biver faunas, which are represented 

by the foregoing lists, as to connect with the faunas of subsequent 

epochs, or with those of the present time. Although we necessarily 

assume that a part of such lines have been maintained continuously, 

each through the whole or a part of those geological epochs, it is evident that others of them would have become diverged from the main 

lines of succession and destroyed by some of those physical changes 

which marked the successive epochs.

In view of the facts which have been set forth on the precedingpages, I think we may reasonably as surne that one of those divergent 

lines terminated in the Bear Biver fauna; that is, at the close of the 

Bear Biver epoch the area which its noninarine waters had occupied 

having become overspread by the marine Avaters in which the Colorado 

formation was deposited, it is not probable that any fluvial outlet of 

the former nouinarine waters was perpetuated, and there was therefore no provisional habitat in which the Bear Biver fauna might have 

been preserved. It was probably in this way that the distinguishing 

types of that fauna became extinct, together with-others of its members which were not so specially characteristic of it.

It was-suggested on preceding pages that certain members of the 

Bear Biver fauna which were more able than others to live in strongly 

saline waters survived in the succeeding marine waters of the Colo-
84 THE BEAR RIVER FORMATION. [BULL. 128.

rado formation. This may really have been the case, but such a fact 

would not necessarily affect the suggestion that, the typical Bear Eiver 

forms, which were doubtless unable to thrive in waters of full marine 

saltness, were extinguished in the manner indicated. 

> While the foregoing suggestions as to the fate of those typical forms' 

are evidently rational, and probably indicate the true, course of events 

in that case, no observations hitherto made warrant any definite sug- 1 

gestion as to their ancestry. This lack of suggestive information 

emphasizes the fact that the fauna which they characterize is unique 

among the North American fossil faunas.

THE GEOGRAPHICAL AND TIME RANGE OF PYRGULIFERA. '

It has been shown on preceding pages that the Bear Eiver fauna, as a 

whole, is unique among North American fossil faunas, and also that 

those of its members which especially and conspicuously characterize 

it are so different from any of the members of other North American 

faunas that one is hardly justified in offering any suggestions as to their 

ancestry or progeny; and little can be suggested concerning their more 

remote faunal relationship.

The most conspicuous "generic type among these characteristic 

members of the Bear Eiver fauna is Pyrgulifera, and peculiar interest 

attaches to this genus because of the remarkable cases of b'6th geographical and chronological isolation which it presents in the different 

parts of the world where it is known. In Nor^h America this genus has 

not only the extremely limited time range which has been explained, 

but, with the exception of a single specimen, evidently referable to this 

genus, which was lately discovered in Dakota strata in Nebraska, its 

known geographical distribution is confined to a comparatively narrow belt of country which does not exceed 150 miles in length. This 

genus is also known to occur in several of the nonmarine fossil faunas of 

Europe, and to be represented by living species in Africa, but beyond 

this it is not known to have a representative in any other fauna, nor in 

any other parts of the world.

The species constituting the European faunas in which Pyrgulifera 

occurs have been published by various authors and at various times 

and places, but a good summary of them, so far as the needs of the 

present discussion are concerned, may be obtained from the publications 

of M. Philippe Matheron,1 Prof. Dr. Paul Oppenheim,2 and Dr. Leopold 

von Tauscb,3 especially the latter.

'Catalogue methodique et descriptif des corps organis6s fossiles du department des Bouches-duRhone et lieux circonvoisins, Marseille, 1842.

sTJeber einige Brackwasser- und Binnen-Mollusken aus der Kreide unti dem Eociin Ungarns. Zeit 

schr.Deutsch.geol. Gesell., BandXLIV, Heft 4, Berlin, 1892.

31. TJeber die Fauna dor nicht-marinen Ablagerungen der oberen Kreide des Csingerthales bei Ajka 

im Bakony (Veszprimer Comitat, Ungarn); und iiber einige Conchylien der Gosaumergel von Aigen 

bei Saltzburg. Abhandl. K.-k. geol. Reichsaustalt. Band XII, No. 1, pp. 1-30, pis. i-iii, AVien, 1886

2. Ueber einige Conchylien aus dem Tanganyika-See und deren t'ossile Verwaiidte. Sitzungsber 

K. Akad. Wiss., Ahtheil. I, Juli Heft, Wien, 1884.

3. Ueber die Fossilieu von St. Briz in Sudsteierruark. Verhandl. K.-k. geol. Keichsanatalt, No, 9 

Wieu, 1888.
WHITE.] GEOGRAPHICAL ANF TIME RANGE OF PYRGULIFERA. 85

The European noninarine faunas referred to occur respectively in the 

following formations: The Lignitic' formation of southern France, the 

coal-bearing Upper Cretaceous strata near Ajka in western Hungary, 

the nonmarine portion of the Gosau formation, of the northeastern Alps, 

the St. Briz deposit in southern Styria, and in probable equivalents of 

certain of those formations in other parts of Europe. Ten species of 

Pyrgulifera are recognized by Dr. von Tausch and Professor Oppenheiin 

among those faunas. The following list shows the names by which 

they designate them:

Pyrgulifera aciuosa Zekeli. P. Imuierosa Meek.

P. ajkaensis Tausch. P. lyra Matheron.

P. ariuata Matheron. P. pichleri Hoernes.

P. glabra Hantken. P. rickeri Tausch.

P. graclata Rolle. « P. striata Tausch.

Although the faunas just mentioned, each as a whole, are quite different from, one another, Dr. von Tausch has shown that certain of the 

species of Pyrgulifera range from one formation to another. For 

example, he has shown that Pyrgulifera pichleri and P. acinosa, are found 

associated together in both the Gosau and Ajka formations, and also 

that both P. armata and P. lyra, occur together in the Ajka formations 

as well as in the Lignitic formation of southern France, where they 

were originally discovered by Matheron.

The discovery of a forni in the Ajka formation which can not be 

distinguished from typical examples of Pyrgulifera humerosa, the most 

characteristic species of the Bear River formation, is very remarkable. 

It is sufficiently difficult to understand how Pyrgulifera, or any other 

nonmarine genus of branchiferous mollusca, could have become so dispersed from one genetic center as to occupy isolated areas on separate 

continents, but it is still more difficult to believe that the North American P. humerosa represents the European form ancestrally, or vice 

versa. I am therefore inclined to believe that, notwithstanding the 

apparent identity of the Ajka and Bear River forms, they originated 

independently.

Still, such a distribution and commingling of species as Dr. von 

Tausch has shown to occur in Europe is usually accepted by geologists 

as indicating a more or less direct genetic relationship between the 

faunas which respectively contain them, and consequently as indicating at least an approximate contemporaneity of origin for the formations which those faunas characterize. It is consistent with these 

views to regard the Ajka, Gosau, and French Lignitic formations as 

having been at least approximately contemporaneous in their origin. 

There being no reason to doubt the Upper Cretaceous age of the Ajka 

and Gosau formations, this view of the question requires the reference 

of the Lignitic formation of southern France to the same age, notwithstanding its original reference to the Tertiary. In short, with only 

one exception, there seems to be no reason to doubt the Upper Cre-
86 THE BEAK RIVER FORMATION. [suit. 128.

taceous age of any of the European strata, which contain the remains 

of any of the known species of Pyrgulifera.

The exception referred'to is that of the St. Briz deposit in southern 

Styria, in which is found the Pyrgulifera gradata of Eolle. Although 

some geologists have entertained doubts as to the true age of the St. 

Briz deposit, several important facts favor its reference to the base.of 

the Tertiary, to Avhich horizon both Dr. Tausch and Professor Oppenheim refer them. Admitting the Tertiary age of this deposit, the time 

range of Pyrgulifera in Europe, although somewhat longer than it is 

known to have been in America, seems to have been confined to the 

upper part of the Upper Cretaceous and the base of the Tertiary.

Briefly summarizing the foregoing statements concerning the geographical and time range of the genus Pyrgulifera, we observe that it 

is at present known to occur only in ~N orth America, Europe, and 

Africa, and that its earliest appearance is not known to have been earlier than the Upper Cretaceous period.

In North America it is known only in one formation, which belongs 

at or near the base of the Upper Cretaceous. This formation is found 

only in the interior portion of the continent, where it occupies a comparatively small area.

In Europe it is found only in the southern portion of the continent, 

and its time range is apparently from near the middle of the Upper 

Cretaceous to the base of the Tertiary, inclusive.

In Africa it is known only by, living forms, which have yet been 

found only in Lake Tanganyika.1

'The following publications contain discussions of the molluscan fauna of Lake Tanganyika:

Proc. Zool. Soc. London for 1879, p. 348; for 1880, p. 344; for 1881, pp. 276, 558.

Annals Mag. Mat. Hist., 5th ser., Vol. VI, p. 425, London, 1880.

Jour. do.conch..Paris, for 1881, pp. 105,277.

Nature, Vol. 'XXV, pp. 101-102,- 218, 1881.

Proc. U.S.Nat.-Mus., Vol. V (for 1882), pp. 94-99, 1883.

Am. Jour. Sci., 3d ser., Vol. XXIX, pp. 277-280, 1885.

Sitzungsb. K. Akad. Wiss. Abthcil I, Juli Heft, AV'ien, 1884.
PLATE II

87
E II.

OSTKEA HAYDENI (p. 32).

Fig. 1. Lower valve: exterior view. 

Fig. 2. Upper valve; interior view.

MODIOLA PEALEI (p. 33).

Fig. 3. Imperfect right valve.

UNTO BELUPUCATUS (p. 34).

Fig. 4. Left valve of usual form. 

Fig. 5. Another left valve, more elongate. 

Fig. 6. Dorsal view of a left valve. 

All natural size.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. II

OSTREID>£, MYTILID/E, AND UNIONID/E,
PLATE III
PLATE III.

UNIO VETUSTUS (p. 35).

Fig. 1. Interior view of a left valve.

Fig. 2. Exterior view of a right valve.

Fig. 3. Dorsal view.

Fig. 4. Exterior view of a large, broad left valve.

All natural size. 

90
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. Ill

UNIONID/E.
T6

vi i a A! 
PLATE IV.

* CORBICULA DURKEKI (p. 36).

Figs. 1,2. Lateral views. 

Fig. 3. Front view. 

Fig. 4. Dorsal view.

CORBULA PYKIFORMIS (p. 38).

Figs. 5, 6, 7. Lateral, dorsal, and front views, respectively, of a typical example. 

Fig. 8. Interior view of a right valve. 

Fig. 9. Interior view of a left valve.

CORBULA ENGKLMANNI (p. 40).

Fig. 10. Lateral view of a right valve. 

Fig. 11. Lateral view of a left valve.

CORBULOMYA TAUSCHII (p. 40).

Fig. 12. Lateral view of the left valve of the»type specimen. 

Fig. 13. Similar view of a left valve, probably belonging to this species. 

All of natural size.

92
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. IV

CYRENID/E AND CORBULID/E.
PLATE V.

93
PLATE V.

AURICULA NEUMAYIU (p. 41). 

Fig. 1. Apertural view; enlarged.

MELAMPUS CLARKII (p. 42).

Fig. 2. Apertural view; enlarged.

Fig. 3. Similar view of an imperfect specimen; enlarged.

x KHYTOPHORUS PRISCUS (p. 43).

Fig. 4. Apertural view; natural size (after Meek).

Fig. 5. Opposite view of the same specimen (after Meek).

KHYTOPHORUS MEEKII (p. 43).

Fig. 6. Apertural view of a large specimen; natural size. 

Fig. 7. Opposite vie\v of another example; natural size.

TORTACELLA HALDEMAXI (p. 44).

Fig. 8. Lateral view of a typical example; enlarged.

Fig. 9. Apertural view of a more slender example; enlarged.

Fig. 10. Apertural view of an imperfect example; enlarged.

Figs. 11,12. Copies of the figures originally published, but which did not show

the columella folds. 

94
U. S. GEOLOGICAL SURVEY BULLETIN NO. 123 PL. V

10

AURICULID/E.
PLATE VI.

95
PLATE VI.

LlMN^A SITIDULA (p. 45).

Figs. 1,2. Copies of Mi-. Meek's unpublished figures; enlarged.

Fig. 3. Apertural view of one of Mr. Meek's type specimens; natural size.

PLANORBIS (GYRAUMJS) PUJSCURSORIS (p. 46).

Figs. 4, 5. Apical views. 

Fig. 6. Umbilical view. 

Fig. 7. Peripheral view, showing aperture. 

All enlarged.

 i

PHYSA USITATA (p. 47).

Fig. 8. Lateral view of a type specimen.

Fig. 9. Lateral view of another type specimen, partially crushed. 

Both natural size.

.NERITINA NATICIFORMIS (p. 49).

Figs. 10, 11. Upper and under views of separate examples; natural sixe. 

Fig. 12. Lateral view of one of the original type specimens; much enlarged.

HELIX? ? (p. 48). 

Fig. 13. Lateral view of the only discovered example; much enlarged.

TORNATELLINA? ISOCLINA (p 48).

Fig. 14. Lateral view of the type specimen; enlarged.

Fig. 15. Foreshortened view of the same specimen, showing the small umbilicus.

NERITINA STANTONI (p. 49).

Fig. 16. Lateral view of an adult example; enlarged.

Fig. 17. Apical view of the same, showing that the specimen has been slightly 

compressed. 

Fig. 18. Lateral view of a young example; much enlarged.

96
U. S. GEOLOGICAL SURVEV BULLETIN NO. 128 PL. VI

17 16

10 11

13

LIMNEID/E, PHYSID/E, NERITID/E AND HELICID/E(?).
PLATE VII

Bull. 128 7

97
PLATE VII.

PACHYMELANIA CLEBURNI (p. 51).

Figs. 1, 2. Lateral views of typical examples; natural size.

Fig. 3. Similar views of an example showing obsolescence of longitudinal varices.

PACHYMELANIA CHRYSALLOIDEA (p. 52).

Figs. 4, 5. Lateral views of the type specimens; natural size. 

PACHYMELANIA CHRYSALIS (p. 51).

Figs. 6, 7. Lateral views of typical examples; enlarged. 

Figs. 8, 12, 13. Possibly varieties; natural size.

PACHYMI!LANIA? MACILENTA (p. 54).

Fig. 9. Lateral view of typo specimen; enlarged. 

Figs. 10, 11. Possibly varieties; natural size.

PACHYMELANIA TUKRICULA (p. 53). 

Figs. 14, 15. Lateral views of the type specimen; enlarged.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. VII

10

MELANIID/E.
PLATE Till.
PLATE VIII.

PYRGULIFERA HUMEROSA. (p. 55).

Figs. 1, 2. Lateral views of Mr. Meek's type specimen. 

Figs. 3, 4, 5, 6. Lateral views of typical forms. 

Figs. 7, 8. Lateral views of an unusually elongate example. 

Figs. 9, 10. Two examples showing an umbilicate fissure. 

Fig. 11. A very young example; enlarged.

All natural size. 

100
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. VIII

MELANIID/E.
PLATE IX

101
PLATE IX.

PYRGULIFEUA STAXTOXI (p. 57).

Figs. 1, 2. Lateral views of typical examples. 

Fig. 3. A similar view of another example.

PYRGULIFERA HUMEROSA (p. 55).

Fig. 4. Lateral view of an example having the volutions more than usually rounded

and the nodules obsolete. 

Fig. 5. Lateral view of another example showing a somewhat similar ronnding of

the volutions of the spire. 

Fig. 6. Another example having a prominent shoulder to the volutions, hut only a

slight development of nodules. 

Figs. 7, 8. Two examples showing ahsence of longitudinal varices and a continuous

carina at the humeral angle.

PYRGULIFERA (PARAMELANIA) DAMONI. 

Fig. 9. A copy of Mr. Smith's original figure. (For comparison.)

PRYGULIFERA (PARAMET,ANIA) CRASSIAXGUI.ATA. 

Fig. 10. A copy of Mr. Smith's original figure. (For comparison.)

All of natural size. ' 

102
U. 8. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. IX

MELANIIDXE.'
PLATE X

103
PLATE X.

VlVIPARUS COUESI (p. 59).

Fig. 1. Lateral view of the type specimen; natural size. 

CAMPELOMA MACROSPIRA (p. 60). 

Figs. 2, 3. Lateral views of the type specimen; natural size.

LlOPLAX? EXDLICHI (p. 60).

Figs. 4,5. Lateral views of the two type specimens.

Fig. 6. Lateral view of the apical portion of a specimen possibly belonging to

this species. 

All natural size.

CHARYDROBIA STACHEI (p. 58).

Fig. 7. Apertural view of a- typical example. ^ 

Figs. 8, 9. Lateral views of two other examples.,, 

All enlarged.

BYTHINKLLA LATENTIS (p. 58). 

Figs. 10,11. Lateral views of the type specimens; much enlarged.

HYDROBIA OCCULTA (p. 57).

Figs. 12,13. Lateral views of the type specimens; much enlarged. 

CHAR A STANTONI (p. 63).

Fig. 14. Lateral view of a nutlet. 

Fig. 15. Basal view of the same. 

'Fig. 16. Transverse section.

All greatly enlarged. i 

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U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. X

11

VIVIPARID/E, RISSOID/E, AND CHARA.
PLATE XI.

105
PLATE XI.

METACYPRIS CONSOBRINA- (p. 62). 

Fig. 1. a, Carapace, left valve shown; &,' edge view; c, end view.

METACYPRIS SUBCORDATA (p. 62). 

Fig. 2. a, Left valve shown; Z>, edge view; c, end view.

METACYPRIS CUNEIFORMIS (p. 62).

Fig. 3. a, Right valve shown; 1), edge view; c, end view. 

CYTHEIUDEA TRUNCATA (p. 62). 

Fig. 4. a, Left valve shown; 1>, ventral edge.

CYPRIDEA TUBERCULATA VAR. WYOMINGENSIS (p. 62).

Fig. 5. a, Right valve shown; 1), ventral edge. 

Fig. 6. a, Left valve shown; 6, ventral, edge.

CYTHERIDEA TENUIS (p. 62). 

Fig. 7. a, Left valve shown; &, edge view.

POTAMOCYPRIS AFFIN1S (p. 62).

Fig. 8. a, Right valve shown; &, ventral edge.

 »

METACYPRIS SIMPLEX (p. 62). 

Fig. 9. a, Right valve shown; Z>, edge view; c, end view.

CYPRIS PURBECKENSIS (p. 62). 

Fig. 10. a, Carapace, right valve shown; 1), edge view.

CYTHERIDBIS /EQUALIS (p. 62). 

Fig. 11. a, Carapa.ce, left valve shown; 1), edge view.

CYTHERIDEIS IMPRESSA (p. 62). 

Fig. 12. a, Right valve shown; 1), edge view.

CYTHERE MONTICULA (p. 62).

Fig. 13. a, Left valve shown; 6. edge view.

Figures and explanations copied from Professor Jones's original publication : Geol. Mag., new ser., Decade III, Vol. X, pp. 385-391, pi. xv, 

London, 1893.

All figures enlarged 20 diameters. 

106
U. S. GEOLOGICAL SURVEY BULLETIN NO. 128 PL. XI

3 C

10« 10

,«- 12' 13'

OSTRACODA.
INDEX.

Acella haldemani .......................... 44

Armnlosa.................................. 61

Auricula ncumayri ..................... 41, 64, 94

Bear Elver fossils, list...................... 64-65

Bridger formation, fossils of............... 79-81

Bythinella latentis..................... 58,65,104

Campeloma macrospira ................ 60, 65,104

Chara stantoni............................ OR, 104

Charydrobia cbaracoarum.................. 58

stacliei.......................... 45,58,65,104

Colorado Jurassic invertebrates, list....... 71

Conrad, T. A., on age of the Bear River

formation.......................... 16

Corbictila durkcei- -............ 28, 29,36, 37, 64, 92

pyriformis ............................. 29, 40

Corbula engelmauni.................... 40,64,92

nematopbora........................... 40

pyriformis .......................... 38, 64, 92

Corbulomya tauscbii.................... 40,64,92

Crustacea.................................. 61

Cypridea tuborculata var. Wyoniingensis. 62,106 

Cypris purbeckensis...................... 62,106

Cyrena erecta.............................. 37

securis................................. 37

Cythere monticula ........................ 62,106

Cytheridea tennis......................... 62,106

truncata .............................. 62,106

Cythericleis cequalis....................... 62.106

impressa.............................. 62,106

Dakota fossils, list......................... 73

Dunvegan fauna compared "with Bear

River.............................. 28-29

Emmons, S. F., on age of Bear Eiver formation............ ..................a6-17

Engeltnann, Henry, discovery of Bear

River formation by ................ 14

on age of tbe Bear River formation .... 15,17

Engelmann, Henry, P. B. Meek and, first 

publication concerning Bear River 

formation by....................... 15

Fossils, Bear River formation, list......... 64-65

Colorado and Wyoming Jurassic, list.. 71 

Dakota formation, list.................. 73

Laramie formation, list................. 74-77

Wasatch, Green .River, and Bridger formations, lif.t........................ 79-81

Fresb water Jurassic invertebrates, list... 71 

Goniobasis chrysalis ....................... 51

cbrysalloidea........................... 52

cleburni................................ 51

endlicbi................................ 60

macileuta .......... ................... 54

Green River formation, fossils of........... 79-81

Hayden, P. V., on age of tbe Bear River

formation.......................... 15

Fage. 

Helix ? ?.........,.................... 48,96

cretacea................................ 48

Hydrobia oeculta ...................... 57, 65,104

Jones, T. Rupert, identification of Bear

- River fossils by.................... 61-62

Jurassic invertebrates, list................. 71

King, Clarence, on age of Bear River formation ............................. 16-17

Laramie fossils, list........................ 74-77

Limnea nitidula...................... 45,58,64,96

Lioplax? endlicbi................ .. 60,61,65,104

Matacypris coiisobrina..................... 62

cunoiformis ............................. 62

simplex................................ 62

snbcordatn,.....i....................... 62

Matheron, P., cited ......................... 84

Meek, T?. B., on ago of tbe Bear River formation .......................... 15,16,17

Meek and Hayden's'TJpper Missouri section 

compared with Upper Cretaceous 

section of Rocky Mountain region. 21 

Melampiis antigiuis ........................ 42

clarkii .............................. 42, 64,94

prisons................................. 43,44

Melania admirabilis........................ 51

nitidula................................ 45

humerosa ....................... '. ...... 55, 57

Melantbo macrospira ...................... 60

Membranipora? ? .................... 65

Metacypris consobrina..................... 104

, cuneiformis............................ 106

forbesii ...'........................-..-. 62

simplex............. v ................. 106

subcordata............................. 104

subovata............................... 62

Modiola multilinigera. ...... ...........'.... 28,33

pealei................... 28-29,33,38,40,64,88

Molluscoidea............................... 61

Neritina naticiformis ................... 49, 65,96

stantoni ............................ 49,65,96

Oppenheim, P., cited ...................... 84

Ostracoda.................................. 61-62

Ostrea baydeni................... 32,33,40,64,88

virginica............................... 32

Pachymelaiiia, generic description......... 50

chrysalis............................ 51, 65,98

cbrysalloidea ....................... 52, 65, 98

cleburni............................. 51,65, 98

macilenta ........................... 54, 65, 98

turriculla ........................... 53, 65, 98

Peale, A. C., on extent and age of the Bear

River formation.................... 18-19

acknowledgments to ................... 29

Physa usitata........................... 47,64,96

gyrina................................ 47

107
108 INDEX.

Page. 

Planorbis militaris....................... 46

prsecursoris ......................... 46,64, 96

veturnus.............................. 46

Plant remains............................ 62

Potamocypris affinis..................... 62,106

Powell, J. W., on age of Bear River formation ........................... 17-18

, Pyrgulifera, generic description......... 55

geographical and time range of...... 84

. crassiangulata....................... 102

damoni...-v .......................... 102

liumerosa.............. 27,28,53,55,65,100,102

stantoni............................ 57, 65,102

Eliytophorus meekii.................... 43,64,94

priscus.............................. 43, 64,94

Section of Bear River strata prepared by . Mr. T. W. Stanton............... 21

Stantou, T. "W., geologic position of Bear 

River formation first correctly 

stated by......................... 13

Bear River general section preparedby 20-21 

work on Bear River formation by.... 22-24

St. John, Orestes, work done on the Bear

River formation by.............. 19

acknowledgments to................. 29

Tausch, Leopold von, cited on fauna of a 

Hungarian formation probably 

equivalent to Bear River......... 24

cited on occurrence of Pyrgulifera.... 84-85

Tornatellina ? isoclina................... 48,65,9*5

Tortacella, generic description........... 44

haldemani .......................... 44,64,94

TJnio belliplicatus- -.................. 34,36,64, 88

mendax.............................. 36

priscus............................... 36

rectoides........'..................... 36

vetustus ......................... 35, 36,64,90

Viviparus couesi. -..................... 59,65,104

Wasatch formation, fossils of............ 79,81

White, C. A., former views on age of Bear

River formation.................. 18,19

Whiteaves, J. F., acknowledgments to... 28 

Wyoming Jurassic invertebrates, list.... 71