Fossils From the 

Ordovician Bioherm at 

Meiklejohn Peak, Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 685
Fossils From the 

Ordovician Bioherm at 

Meiklejohn Peak, Nevada

By REUBEN JAMES ROSS, JR.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 685

Distribution of fossils in the bio her m and in 

flanking beds is documented. Species of 12 genera

of brachiopods and 2O genera of trilobites are

described. They compare closely with contemporary 

forms in Quebec and western Newfoundland

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1972
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS G. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 78-188321

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402 - Price $1.25 (paper cover)

Stock Number 2401-2048
CONTENTS

Abstract.._ __________________________________

Introduction. ________________________________

Previous work____________________________

Acknowledgments ____.___--__-_____.______

Stratigraphic setting._________________________

Petrology of bioherm, preliminary statement. 

Fossil collections.--_________.---_---__________

Collections from flanking beds__________________

Stratigraphic anomalies ________________________

Summary of fossil distribution______ ____________

Descriptions of fossils.________________________

Phylum Brachiopoda_.__-__-----_______-__

Class Articulata._____________________

Genus Orithidiuni- ________________

Genus Trematorthis _______________

Genus Pleurorthis--- ___-__.____-__

Genus Cyrtonotellct- _.__-_.________

Genus Phragmorthis- ______________

Genus Camerella.- ________________

Genus Idiostrophia ________________

Genus Ingria- __.__-_-______.___-_

Genus Isophragma. _______________

Genus Petroria- __________________

Genus Paucicostella- ______________

Genus Cuparius. _________________

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Phylum Arthropoda_______________

Class Trilobita_______---__---_

Genus Trinodus___________

Genus Shumardia- _________

Genus Carrickia, __________

Genus Carolinites- _________

Genus Glaphurus __________

Genus Nileus- _____________

Genus Peraspis- ___.---___- 

Genus Illaenus ____________

Genus Harpillaenus- _______

Genus Bathyurellus- _______

Genus Rayrnondites? ________

Genus Selenoharpes- _______

Genus Endymionia. ________

Genus Lehua.- ____________

Genus Pliomerops_ _______

Genus Kawina- ___________

Genus Xystocrania---------

Genus Heliomera-----------

Genus Miracybele- _________

Genus Apatolichas. ________

Pygidia of uncertain affinity. 

References cited___________-_--_---___-

Index_ __________________----------__-

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ILLUSTRATIONS

[Plates 1-18 follow index]

PLATE 1. Orthidium, Orthidium?, Trematorthis, and Pleurorthis.

2. Pleurorthis?, Cyrtonotella?, and Phragmorthis.

3. Camerella.

4. Camerella and Idiostrophia.

5. Idiostrophia.

6. Idiostrophia.

7. Idiostrophia.

8. Idiostrophia.

9. Idiostrophia and Ingria.

10. Ingria, Ingria?, Leptellina? or Taphrodonta?, Isophragma?, and Carrickia.

11. Petroria?, Cuparius, Shumardia, Carolinites, and Trinodus.

12. Carolinites, Glaphurus, Nileus, Peraspis?, and Illaenus.

13. Illaenus.

14. Illaenus and Illaenus?.

15. Harpillaenus and Bathyurellus.

16. Raymonditesl, Selenoharpes, Endymionia, proetid, Lehua, and Pliomerops.

17. Kawina, Xystocrania, Heliomera, and Miracybele.

18. Apatolichas, undetermined pygidia, Eopteria, undetermined edrioasteroid 

and Idiostrophia.

in
IV CONTENTS

Page 

FIGURE 1. Index map showing relative locations of bioherms at Meiklejohn Peak and

Aysees Peak, Nev_______________________________________________ 2

2 -6. Photographs:

2. Meiklejohn Peak showing the Eureka Quartzite and large bioherm_ 3

3. Scarp face of the main mass of the great bioherm below Meiklejohn

Peak___________------------_-_-----------_______________ 3

4. Exposed northwest end of bioherm_____.._____________________ 4

5. Showing sparry calcite encrustations of fossil skeletons and filling

of chambers of cephalopods-__-__-_---------_______________ 5

6. Showing thin laminae of fine lime wackestone separated by sparry

calcite __________________________________________________ 5

7. Photomicrographs of thin sections of wackestone and laminoid fenestrae__ 7

8. Photomicrographs of fossiliferous pocket in massive part of bioherm_____ 8

9. Photomicrographs of well-stratified limestone flanking bioherm sections

cut nearly parallel and perpendicular to layering.___________________ 9

10. Diagram showing relative positions of fossil collections from bioherm and

flanking beds of Meiklejohn Peak_ ________________________________ 10

11. Chart showing ranges of genera of trilobites and brachiopods in flanking

beds, in bioherm, and in both_____________________________________ 19

12. Diagram showing length of shell of Idiostrophia valdari Ross, n. sp. versus

apical angle, contoured according to number of specimens___ _________ 25

13. Diagram showing length of shell of Idiostrophia valdari Ross, n. sp. versus

number of costae, contoured according to number of specimens______ 25
FOSSILS FROM THE ORDOVICIAN BIOHERM 

AT MEIKLEJOHN PEAK, NEVADA

By REUBEN JAMES Ross, JR.

ABSTRACT

A great limestone bioherm, 270 feet thick, lies within the 

thin-bedded silty limestone of the lower member of the Antelope Valley Limestone (Pogonip Group) at Meiklejohn Peak, 

Nev. Fossils from the flanking beds show that the bioherm 

lies mostly within the Orthidiella zone, but the base of the 

bioherm may rest as low as the Pseudocybele nasuta zone of 

the upper Canadian. Fossils from both the bioherm and the 

flanking beds include trilobites, brachiopods, cephalopods, conodonts, gastropods, and a few pelecypods, ostracodes, bryozoans, 

and algae. However, the greatest volume of fossil debris is 

derived from the pelmatozoans.

Fossils from within the bioherm resemble those from similar 

limestone bodies in lower Middle Ordovician formations in 

Quebec and western Newfoundland. All shelly fossils in the 

bioherm are encrusted with sparry calcite, which may be 

algal in origin.

The 12 genera of brachiopods and 20 genera of trilobites of 

which species are described constitute only a part of the total 

fossile assemblage. They include Cyrtonotella, PhragmortMs, 

Raymondiiesl, and Plwmerops all genera that are expected 

in Chazy or younger strata. Petroria is described for the first 

time south of the United States-Canadian border. It is suggested that Paitcicostella of Quebec and Newfoundland is a 

synonym of Ingria of Nevada.

INTRODUCTION

This report deals with the fossils found from 1960 

through 1969 in the great early Middle Ordovician 

bioherm at Meiklejohn Peak, Nev., and in the silty 

flanking limestone. The bioherm is exposed on the 

southwest side of Meiklejohn Peak in the SW^NE^ 

sec. 21, T. 12 S., R. 47 E., Bare Mountain 15-minute 

quadrangle, Nevada (Ross, 1964, p. C25-C26). The base 

of this biohermal structure rests on silty limestones 

that are gradational from the Ninemile Formation into 

the lower member of the Antelope Valley Limestone. 

These beds include brachiopods and trilobites of the 

Pseudocyl>ele nasuta zone. Beds that lie above the bioherm and flank its higher sides carry brachiopods of 

the Orthidiella zone.

A considerably diverse fossil assemblage has been 

taken from the limestone of the bioherm as well as from

the thin-bedded silty limestone that flanks it. Although our knowledge of the fauna is far from complete, the trilobites and brachiopods obviously are 

very similar to those from Table Head and Lower 

Head, western Newfoundland (Whittington, 1963, 

1965; Cooper, 1965, p. 11-12), as well as to brachiopods 

listed from boulders in the Mystic Conglomerate and 

Levis Shale of Quebec (Cooper, 1956, p. 15, 31; Ross 

and Ingham, 1970, p. 400).

PREVIOUS WORK

During the stratigraphic work in southern Nevada 

in 1960, three small biohermal masses were discovered 

on the Nevada Test Site and adjacent Bombing and 

Gunnery Range in the lower part of the Antelope Valley 

Limestone. Subsequently, a similar but much larger 

bioherm was called to my attention by Cornwall in the 

Bare Mountain quadrangle, and both these occurrences 

were reported shortly thereafter (Ross and Cornwall, 

1961; Ross, 1964, p. C25-C26, pi. 1; Ross, 1967, pi. 11). 

Unfortunately, the bioherms on the gunnery range in the 

vicinity of Aysees Peak, east of Frenchman Flat, have 

not been comfortably accessible in recent years; but, 

repeated short visits have been made to the reef at 

Meiklejohn Peak in the Bare Mountain quadrangle

(% 1).

In 1966, R. H. Flower assisted in the work at the 

Meiklejohn Peak bioherm and collected a considerable 

number of cephalopods.

Several of the trilobites reported by Holliday (1942, 

p. 472) wrere obtained from the silty limestones that 

flank the bioherm at Meiklejohn Peak. These were identified by Holliday as Ectenonotus connemaricus 

(Reed), Ectenonotus marginatus n. sp.; Parapilekia 

beattyana n. sp., Pseudomera sp., and Niobe? feitleri 

n. sp.

The Bare Mountain quadrangle was mapped geologically by Cornwall and Kleinhampl (1960, 1961). 

Their map indicates the presence of a fault that cuts 

across the Ordovician section on the southwest side of
FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

FIGURE 1. Index map showing relative locations of bioherms at Meiklejohn Peak (M) and Aysees Peak (A),

Nev.

Meiklejohn Peak. This fault passes west of the main 

mass of the bioherm, cutting its coarsely calcarenitic 

apron (figs. 3, 10).

Although two small bioherms were found east of 

Frenchman Flat in 1960, their regional importance 

was not fully appreciated; their stratigraphic position 

is in the Ranger Mountains Member (Byers and others, 

1961, p. C108). The bioherm at Meiklejohn Peak is in 

the same stratigraphic position but a more generalized 

stratigraphic terminology has been used and the reef 

is considered to be high in the lower member of the 

Antelope Valley Limestone.

ACKNOWLEDGMENTS

H. R. Cornwall and F. G. Kleinhampl first called my 

attention to the bioherm at Meiklejohn Peak in 1960. 

Since then several paleontologists have visited this 

feature with me and have contributed much counsel 

and assistance; they include A. R. Palmer in 1960- 

61; G. A. Cooper, J. T. Dutro, Jr., R, S. Boardman, 

B. S. Nbrford, F. C. Shaw, and H. B. Whittington in 

1965; R. H. Flower in 1966 and N. F. Sohl in 1969.

The manuscript was read critically by Dr. Valdar 

Jaanusson, William T. Dean, and Michael Taylor, to

each of whom I am indebted for important comments 

and corrections. John L. Wray, Dr. Jaanusson, and 

Richard Rezak were particularly helpful in advising 

me on interpretation of carbonate petrology of the 

bioherm.

During my visit to Sweden in 1968, Dr. Valdar 

Jaanusson called attention to Idiostrophia in the Asaphus shale in the district of Toyen, where it had been 

called RhynchoneUa digitata by Brogger. Dr. Gunnar 

Henningsm0en of the Paleontological Museum in Oslo 

kindly permitted me to illustrate and describe Brogger's specimen for comparison with the myriad specimens of Idiostrophia found in the Meiklejohn bioherm. 

Dr. Jaanusson also showed me the somewhat younger 

but very similar Ordovician bioherms near Lake Siljan, Dalarna, in Sweden.

Part of grant GA-4020 from the National Science 

Foundation made possible the visit to areas of Swedish 

Ordovician exposure under the guidance of Dr. 

Jaanusson.

Through the efforts of colleagues, a more complete 

coverage of fossils in and around the bioherm has been 

possible. Ellis Yochelson identified the gastropods, 

Jean Berclan the ostracodes, Olgarts Karklins the bryozoans, and John Huddle the conodonts. A. J. Rowell 

of the University of Kansas has made a brief examination of inarticulate brachiopods with unusual results. 

Parablastoids were identified by James Sprinkle. John 

Pojeta, Jr., identified the pelecypods and Rousseau H. 

Flower the cephalopods.

STRATIGRAPHIC SETTING

The biohermal limestone at Meiklejohn Peak (fig. 

2) has been recorded as 163 feet thick and 68 feet above 

the base of the Antelope Valley Limestone (Ross, 

1964, p. C26). The original measurement of the section 

was taken across the bioherm on its thinned north 

side. It is actually about 270 feet thick in its thickest 

part (figs. 3, 4). About 20 collections of fossils have 

been made subsequently to those previously published 

by Ross (1964, p. C27-C28). Positions of these collections are shown diagrammatically in figure 10. The 

constituent fossils of each collection are listed below.

The bioherm is about 1,000 feet wide along the face 

of outcrop. Its other lateral dimension is not known. 

The main mass is devoid of clearly defined bedding. 

Locally, the limestone is a coarse bioclastic calcarenite 

composed of a wealth of megafossils brachiopods, 

trilobites, and gastropods, among others. Shells and 

carapaces are encrusted with thin calcitic deposits of 

a sparry nature. This sparry calcite seems to be the 

binder in the bioherm (fig. 5). It is seen to separate 

thin laminae of finer grained limestone (fig. 6) in
STRATIGRAPHIC SETTING

FIGURE 2. Meiklejohn Peak, as seen from the west-northwest at a distance of about 2 miles. The peak is composed of lightcolored Eureka Quartzite. The larger bioherm is in the lower slopes to the right.

FIGURE 3. Scarp face of the main mass of the great bioherm below Meiklejohn Peak, as seen from hill 4966 on the west 

side of Secret Pass (sec. 24, T. 12 S., 47 E., Bare Mountain quadrangle, Nevada). Bioherm is 270 feet thick; exposed 

lateral dimension approximates 1,000 feet. View looking northeast. Approximate position of fault indicated by dotted line.
FIGURE 4. Exposed northwest end of bioherm. Thin overlying beds bear brachiopods of the Orthidiella zone. Standing to left of small cave are 

L. A. Wilson and R. H. Flower (circled). Thin beds in left foreground butt against flank of biohermal mass and overlap its top. Thinned 

biohermal mass passes beneath viewer right of center. Contact between bioherm and flanking beds is obscured by postdepositional shearing.
STRATIGRAPHIC SETTING

FIGURE 5. Sparry calcite encrusts all kinds of fossil skeletons and fills chamber of cephalopods. Butt end of %-inch chisel

lies above sectioned nautiloid.

FIGURE 6. Thin laminae of fine lime wackestone separated by sparry calcite (laminoid fenestrae). This lithology is of great extent on northwest side in lower part of bioherm.

446-051 O - 72 - 2
6 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

other parts of the reef. Even the interiors of fossils, 

such as the chambers of cephalopods, seem to be encrusted.

Dr. Valdar Jaanusson (Thorslund and Jaanusson, 

1960, p. 31) has called attention to and on June 9,1968, 

showed me similar biohermal structures in the Ordovician Kullsberg Limestone at the Unkarsheden quarry, 

north of Rattvik, Dalarna, Sweden. Whittington (1963, 

p. 10-11) lias compared a white limestone boulder at 

Lower Head, western Newfoundland, to Upper Ordovician Swedish limestone that forms numerous similar 

reefs.

This Newfoundland boulder and the boulders recorded in the Levis Shale (Cooper, 1956, p. 14-15) 

near Quebec, and in the Mystic Conglomerate near 

Phillipsburg, Quebec (Cooper, 1956, p. 31), have 

yi< Ided similar faunas.

On Meiklejohn Peak, as in the "boulder" at Lower 

Head (Whittington. 1963, p. 11-12), some fossils are 

preserved in pockets or channels. But the trilobites are 

all disarticulated, and some brachiopods seem to have 

been abraded. Clearly, animals living on or in the bioherm wore subjected to physical destruction; as pointed 

out by Norman F. Sohl (oral commun., June 13, 1969), 

a thin northerly extension of the bioherm is a coarse 

bioclastic deposit of material derived from the main 

part of the bioherm. We found no recognizable megafossils in this deposit,

The nature of basal beds of this bioherm indicates 

that the bioherm did not slide into its present position 

from some other place. However, the bioherm seems 

to have acted as an extremely competent pod during 

late tectonic activity. As a result, the zone of contact 

with less competent flanking beds seems to have been 

sheared and is poorly exposed (fig. 4). In this respect, 

the small bioherms east of Frenchman Flat (Ross and 

Cornwall, 1961) are better preserved.

PETROLOGY OF BIOHERM, PRELIMINARY STATEMENT

No detailed petrologic analysis of the bioherm has 

been attempted. Thin sections of two samples from 

within the mass and one from flanking beds show important contrasts. Samples are from USGS collections 

D1991 CO, D2058 CO, and D19TO CO.

Collection D1991 CO is from a highly fossiliferous 

(brachiopods and trilobites) pocket in the main mass 

of the bioherm. Megascopically, shells and carapaces 

seem to be coated with coarse-grained calcite. Much 

bioclastic material is present. No stratified structure is 

apparent in the bioherm at this spot.

In thin section (figs. 7(7, 8), this sample (colln. 

D1991 CO) is a mixed-fossil wackestone grading to 

packstone in the terminology of Dunham (1962). Although brachiopod shells and parts of trilobite carapaces are conspicuous, most of the fossil material is 

pelmatozoan debris. Ostracodes are present.

Cavities filled with calcite spar are abundant. In one 

example, mud seems to have filled brachiopod shells 

and trilobite skeletons only partially so that the remainder of interiors are filled with spar (fig. 8B).

Some of the cavities resemble the fenestrae described 

by Tebbutt, Conley, and Boyd (1965, p. 4-12) and the 

bird's-eye structure shown by Shimi (1968) (fig. 1C).

Associated with these features are some laminoid 

fenestrae (Tebbutt and others, 1965, p. 4-12) that seem 

to have the same smooth particle-covered floors and 

irregular ceilings.

Although the three sections of sample D1991 CO 

from the seemingly unstructured part of the bioherm 

are different in detail, they share characteristics of a 

very high percentage of spar-filled voids and a layering which is very real, although obscure in some views.

Collection D2058 CO was taken from a strikingly 

laminated part of the bioherm (fig. 6), which is best 

developed in the lower levels. At this locality, laminae 

1-10 mm thick are composed of mixed-fossil wackestone separated by laminae of sparry calcite of considerable lateral extent. These sparry layers seem to 

have the smooth, particle-covered bottoms and irregular tops (figs. 7A, Z?, D) attributed to laminoid 

fenestrae. The stratified concentration of bioclastic 

debris in the wackestone is particularly noticeable (fig. 

7A). Most fragments are pelmatozoan. Trilobite and 

ostracode fragments, however, are conspicuous. Some 

of the sparry laminae contain zoned spar (fig. TJ.), 

which suggests that some secondary replacement has 

taken place. Under high magnification it is indeed clear 

that much of the spar resulted from replacement and 

crystal growth.

This sample (colln. D2058 CO) resembles that from 

the more massive part of the bioherm (colln. D1991 

CO) in its high percentage of spar, its basic layering 

of skeletal debris within wackestone, and its high percentage of pelmatozoan debris.

The features seen here have been interpreted by 

Shinn (1968) as supratidal or intertidal. Tebbutt, 

Coiiley, and Boyd (1965, p. 11-12) have offered a 

similar explanation for their existence.

These Ordovician bioherms seem to have been large 

mounds of calcite mud, mixed with skeletal fragments. 

Sorting of these fragments along crude layers indicates some sort of reworking, perhaps by waves. Pockets and channels filled with sorted brachiopod shells 

(USGS colln. D1968 CO) seem to have been present 

in the mound. Evidence of possible algal mats suggests that the surface was held together by filamentous
STRATIGRAPHIC SETTING

B D

FIGURE 7. Thin sections. X 6.5. A, Fenestrae and laminoid fenestrae in wackestone from massive part of bioherm (USGS 

colln. D1991 CO). B, Laminated mixed-fossil wackestone 

(USGS colln. D2058 CO; fig. 6) and laminoid fenestra with 

zones of spar. Note crude but obvious layering of fossil fragments in overlying wackestone. Pelmatozoan fragments compose most of fossil debris. C, Laminated wackestone (USGS 

colln. D2058 CO; fig 6) and laminoid fenestra. Although trilobite fragments are conspicuous most of fossil debris is 

pelmatozoan. D, Mixed-fossil wackestone and laminoid fenestra (USGS colln. D2058 CO; fig. 6).
FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

FIGURE 8. Thin sections through fossiliferous pocket in massive part of bioherm (USGS colln. D1991 CO). X 6.5. A (left), 

Mixed-fossil wackestone and spar-filled cavities. Trilobite is cranidium of Illaenus. B (right), Mixed-fossil packstone 

in which brachiopod shells are conspicuous. Cavities around and in shells filled with spar. Pelmatozoan fragments compose most of fossil debris.

algae in extremely shallow or intertidal waters and that 

these algae contributed to trapping additional mud.

In marked contrast is the lithology of the wellstratified limestone that flanks the bioherm. This rock, 

exemplified by USGS collection D1970 CO, is the 

source of abundant large trilobites, particularly Ectenonotus. It is dark gray and very fine grained to 

calcarenitic. Thin sections (fig. 9) show that it is also 

a mixed-fossil wackestone. However, it contains no 

spar-filled fenestrae or laminae. Fossil fragments lie 

in crude layers but show no sorting as to size or shape. 

Pelmatozoan fragments are the most abundant.

In some of the mudstone, abundant spherical bodies, 

three-tenths of a millimeter in diameter, are now composed of coarse calcite. These small bodies lack any 

internal structure such as one might expect in oolites 

or in fecal pellets.

There is no evidence that the skeletal material has 

been reworked after deposition; this fact suggests that 

the flanking beds were deposited in deeper water than 

the biohermal mudbanks and may have received periodic "showersv of animal remains swept from the 

top of the mudbanks.

These speculations are based on very few samples 

and lack the systematic coverage that the structure 

seems to warrant. They suggest that the animals 

populating this and correlative mudmounds in Nevada, 

Quebec, and western Newfoundland lived in very 

shallow water.

FOSSIL COLLECTIONS

Fossils collected from this area have great variety 

and have been examined by several specialists. Pelecypods have been identified by John Pojeta, bryozoans by Olgarts Karklins, conodonts by John Huddle, 

and ostracodes by Jean Berdan. Dr. Rousseau H. 

Flower has collected cephalopods from the reef and 

surrounding beds. Ellis Yochelson has collected and 

identified gastropods from this locality. The author is 

responsible for collection and identification of brachiopods and trilobites.

All collections shown in figure 10, except D1976 CO, 

DT40 CO, D2050 CO, and D1974 CO, whose fossils 

have not yet been identified, are listed below. These 

four collections were, however, included in figure 10 to 

show their position in relation to the other collections. 

The stratigraphically lowest collection is listed first. 

Stratigraphic position relative to the base of the bioherm is indicated, and it should be noted that the bottom of the bioherm is 68 feet above the base of the 

Antelope Valley Limestone. 

USGS colln. D1991 CO, Antelope Valley Limestone, 10 ft above

base of bioherm (78 ft above base of formation). 

Brachiopods:

Scliizanibon sp.

Pleurorthis sp.

Ortliidiella,'} sp.

Cuparius'i sp.

Idiostrophia conciliata Ross, n. sp.

Idiostrophia nuda Cooper
FOSSIL COLLECTION'S 9

FIGURE 9. Thin sections of well-stratified limestone (mixed-fossil wackestone) flanking bioherm (USGS colln. D1970 CO). X 6.5. 

A (left), Section cut nearly parallel to layering. B (right), Section cut perpendicular to layering. Large trilobite fragments 

conspicuous. Layers of fossil debris unsorted. Spar-filled spheres, 0.3 mm in diameter, not identified.

OrtMdiuml aff. O. flmbriatum Ulrich and Cooper 

Camerella cf. C. sp. 1 

Plectambonitid, indet. 

Trilobites: 

Nileus sp. 

Peraspis"! sp. 

Illaenus sp. c

Lelma aff. L. argus Whittington 

Batliyurellns sp. 4

Conodonts were studied by J. W. Huddle (written 

commun., Mar. 6, 1969), who commented as 

follows:

"Drepanodus sp___________

Drepanodus n. sp. D_________

Periodon aculeatus"? Hadding: 

cordylodus elementligonodina element. _____

falodus element__ _ 

oulodus element- _______

ozarkodina element- _ _ __

Tetraprioniodusl n. sp.:

ligonodina element. _ _ _ 

cordylodus elementroundya element. _______

Number

of 

specimens

1

1

19

7

15

7

7

6

12

3

Number

of 

specimens

2

1

1

2

7

Oistodus sp_______________________________

Oistodus sp_______________________________

Scandodus species.__________________________

Scandodus unicostatus Sweet and Bergstrom____ 

Scolopodus varicostatus Sweet and Bergstrom_ 

"This is a very interesting little fauna and quite puzzling. 

The Scolopodus and Scandodus species were first described 

from the Pratt Ferry [Formation of Cooper (1956)] but 

have since been found in older Middle Ordovician rocks in 

other Nevada sections. Periodon aculeatus appears in a number of Nevada sections of the Antelope Valley Limestone 

and is not restricted to the OrtJiidiella zone. The Tetraprioniodus'? is apparently a new species but a multi-element one. 

The cordylodus element was described from the Joins 

Formation by Mound (1965) as Cordylodus flexosus but 

his identification is incorrect.

"It is possible that the forms here referred to Tetraprioniodus'? are merely variable elements of a new more 

complex multi-element species of Periodon than P. aculeatus Hadding but as yet I don't know enough about multielement species to be sure. However, Mound did not report 

any Periodon sp. from the Joins Formation but did report 

the tetraprioniodus, roundya and cordylodus elements. This 

(D1991 CO) collection lacks the tetraprioniodus element
10

USGS FOSSIL COLLECTION NO.

0

Z L.

<

t- H.

. D1976 CO (cephalopods)

D2057 CO.

_D1975 CO 

.D2051 CO

VD2052 CO

.01993 CO 

.D818 CO

.D2056 CO

.0821 CO *D741 C0 

*D1974 CO (cephalopods)

D2049 CO

.D2055 CO

.01971 CO 

.D1970 CO

.D1994 CO

.D2053 CO

.D1978 CO

.D2054 CO

Hesperonomia

-500

-400

- 300

200

100

Ninemile Formation

FIGURE 10. Relative positions of fossil collections from bioherm (stippled) and flanking beds of Meiklejohn Peak (Ross,

1964, p. C24-C28).
FOSSIL COLLECTIONS 11

and the Joins Formation lacks the ligonodina element reported here. It will take a lot more collections to straighten out this taxonomy."

USGS colln. D1992 CO. Antelope Valley Limestone, in lower 20 

ft of bioherm, to east of other collections (approximately 

88 ft above base of formation). 

Brachiopods:

Idiostropliia sp. 

Orthidiella"! sp. 

Trilobites:

Nileus ? sp.

Kawina"! sp. (fragmentary cranidium) 

Ostracodes undet.

USGS colln. D19T2 CO, Antelope Valley Limestone, from float 

in bioherm 30 ft above its base (98 ft above base of 

formation). 

Brachiopods:

Lirlcameral cf. L. nevadensis Cooper 

Ingria cloudi Ulricli and Cooper 

Pleurorthisl sp. 

Trilobites:

Illaenus sp.

USGS colln. D1990 CO, Antelope Valley Limestone, approximately 45 ft above base of bioherm, Meiklejohn Peak 

and 113 ft above base of formation. 

Brachiopods:

Orthidium sp. 

Orthidiellal sp. 

PleurortMsl sp.

Ingria cloudi Ulricli and Cooper or Paucicostella sp. 

Liricamera sp.

Petroria cf. P. austrina Ross 

Onychoplecia"! sp. 

Pelecypods (John Pojeta, written commun., Apr. 30, 1969) :

Eopteria sp.

Cephalopods to be identified by R. H. Flower. 

Trilobites:

Illaenus sp. 

Ostracodes undet.

The Paucicostella of this collection resembles immature

specimens of Ingria cloitdi in convexity and outline but

differs in wider spacing of the few prominent costellae.

No interiors could be prepared.

USGS colln. D196G CO, Antelope Valley Limestone, 50 ft above

base of bioherm (118 ft above base of formation). 

Gastropod (Ellis Yochelson, written commun., Feb. 4, 

1969) :

"The specimen is a monoplacophoran, which seems to 

be slightly asymmetrical. No muscle scars are preserved but the shape is more similar to that of 

Cyrtoncllopsis than to other genera." 

Brachiopods:

Idiostrophia cf. /. paucicostata Cooper 

Onyclioplecial sp. 

Orthid, indet. 

Camerella sp. 2 

Cuparius sp. 

Trilobites:

Carolinltcs cf. C. killaryensis (Stubblefield) 

Bathyurellus sp. 3 

Kawina wilsoni n. sp. 

Illaenus sp.

sp. 

Dimeropyge-like trilobite

Ostracodes :

Hyperchilarinal sp.

USGS colln. D1973 CO, Antelope Valley Limestone, 60-65 ft 

above base of bioherm (128-133 ft above base of formation). 

Brachiopods :

Notorthisl sp.

Orthidium leUulum Ulrich and Cooper

Orthidium sp.

Orthidiella sp.

Trematorthis sp.

Pleurortliis beattyensis Ross, n. sp.

Cyrtonotellal aff. C. fasciculata Cooper

Camerella sp. 1

Ingria cloudi Ulrich and Cooper or Paucicostella n. sp.

Petroriat austrina Ross, n. sp.

Plectambonitid, possibly Syndielasma

Cuparius cardilatus Ross

Gastropods (Ellis Yochelson, written commun., Nov. 22, 

1968) :

"iArchinacella sp.

Hyolitlies sp.

Maclurites sp.

Tropidodiscus sp.

New genus cf. Raphistoma

Loxoplocus (Lopliospira) sp. (high spired)

Clathrospira sp.

Liospira sp. indet.

?Pycnomphalid gastropod

Clisospira sp. indet.

IHelicotis sp.

IMimospira sp.

Indet. genus aff. Trochonema 

Pelecypods :

Eopteria sp. (John Pojeta, written commun., Dec. 4,

1968) 

Pelecypod (John Pojeta, written commun., Apr. 30,

1969)

"This specimen is a bivalve of uncertain affinities it may be a conocardiid related to Eopteria."

Trilobites:

Trinodus sp. 1

Carolinites cf. C. killaryensis Stubblefield

N ileus aff. N. scrutator Billings

Illaenus sp. a (cf. I. auriculatus Ross)

Illaenus sp. d

Endymionia cf. E. meeki (Billings)

Kawina wilsoni Ross, n. sp.

Xystocrania pyriformis Ross, n. sp.

Undet. pygidium 1

Undet. pygidium 2

Conodonts (identified by J. W. Huddle, written 

commun., May 1, 1970) : Number

specimens

Acodus sp. of Bradshaw_-__------------------

Acodus sp____- -----------------------------

Acontiodus sp. ------------------------------

Drepanodus suberedus (Branson and Mehl) _____

Drepanodus sp. -----------------------------

Oepikodus sp.---. --------------------------

Oistodus lanceolatus Pander ______-_-_-----

Paltodus sp-. ------------------------------
12 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Periodon aculeatus Hadding: 

falodus element- _______

cordylodus element____

oistodus element______

ligonodina element_.__. 

roundya element-______

ozarkodina elementNumber

°f 

specimens

3

3

4

12

9

6

USGS colln. D2058 CO, Antelope Valley Limestone, lower 

member, from bioherm approximately 130 ft above its 

base (198 ft above base of formation). 

Brachiopods:

Pleurorthis beattyensis Ross, n. sp. 

Petrorial cf. P. austrina Ross, n. sp. 

Cuparius sp. 

Idiostrophia sp.

PaucicosteUa 1? sp. (possibly immature Ingria) 

Ingria sp. 

Trilobites:

Carolinites cf. C. genacinaca Ross

Bathyurellus sp. 3

Illaenus cf. I. auriculatus Ross

Conodonts (identified by J. W. Huddle, written commun.,

May 1, 1970):

Number

°f 

spc ~

Acontiodus sp____--________.

Drepanodus sp_______________

Drepanodus sy. (hooded form). 

Periodon aculeatus Hadding:

oistodus element_________

roundya element_ ________

cordylodus elementligonodina element- ______

ozarkodina elementOstracodes.

USGS colln. D1968 CO, Antelope Valley Limestone, 168 ft above 

base of bioherm (236 ft above base of formation). This 

collection and USGS colln. D740 CO include channel or 

crevice filling packed with hundreds of specimens of 

Idiostrophia. 

Brachiopods:

Ortliambonites cf. 0. minusculus (Phleger)

Idiostrophia, raldari Ross, n. sp.

Idiostrophia lenticularis Ross, n. sp.

Ingria cloudi Ulrich and Cooper 

Trilobites:

Glaphurus sp.

Illaenus cf. /. auriculatus Ross

Illaenus sp. b.

Illaenus sp. d.

Illaenus sp. e

Illaenus! sp. f

Harpillaenus sp.

Selenoharpes sp.

Endymionia cf. E. meeki (Billings)

Pliomerops sp. (pygidium)

Kawina icilsoni Ross, n. sp.

Xystocrania pyriformis Ross, n. sp.

Heliomera cf. H. albata Whittington

Apatolichas cf. A. jukesi (Billings)

10

13

13

17

9

Nileus sp. 

Carolinites sp. 

Ectcnonotus sp.

Gastropods (Ellis Yochelson, written commun., Nov. 22,

1968) :

cf. Clisospira n. sp. 

IHelicotis sp. 

cf. Helicotis sp.

"All specimens in this lot are atypical of normal 

gastropods in their direction of coiling. It is most 

unexpected to find so many like this. cf. Clisospira n. 

sp. is congeneric and possibly conspeciflc with two 

scraps in the museum collections. These were obtained 

from a large boulder in the Stanbridge Conglomerate 

near Mystic, Quebec. According to G. A. Cooper the 

youngest boulders are of Whiterock age." 

USGS colln. D1969 CO, Antelope Valley Limestone, 187 ft above

base of bioherm (255 ft above base of formation). 

Brachiopod:

Indet. genus (lacks interiors) 

Trilobites:

Illaenus sp. b 

Ectenonotus sp.

COLLECTIONS FROM FLANKING BEDS

USGS colln. D1994 CO, Antelope Valley Limestone, from 

flanking beds 173 ft above base of bioherm (241 ft abovo 

base of formation). 

Brachiopods:

Cyrtonotellal sp.

Phragmorthis sp.

Orthidiella sp.

Syntrophiid 

Trilobites:

Trinodus sp.

SJiumardia sp.

Ischyrophymal sp.

Pseudohystricurus sp.

Illaenus two spp.

Nileus sp.

Carrickia sp.

Carolinites angustagena Ross

Bathyurellus feitleri (Holliday)

Miracu~bele sp. 1 (Ross, 1967, pi. 8, figs. 24, 25)

Ectenonotus whittingtoni Ross

Protocalymene mcallesteri Ross 

Gastropod (Ellis Yochelson, written commun., Feb. 4,

1969) :

"Pleurotomariacean gastropod, indeterminate" 

The two most abundant genera in this collection are 

Ectenonotus and Illaenus.

Conodonts (identified by J. W. Huddle, written commun., 

May 1, 1970):

Acontiodus varicostatus Sweet and Bergstr6m___ 

Distacodus"? sp___ ---------------------------

Drepanodus"? sp_________--___--_------------

Oistodus parallelus Pander.________-_--__----

Oistodus sp_______---------------- ---------

Ozarkodina macrcdentatat Graves and Ellison-__ 

Paltodus sp_ ___-__-------------------------

Scandodus sp.------------------------------

Number

°f 

specimens

4

1

1

6

1

1

1

1
COLLECTIONS FROM FLANKING BEDS 13

USGS colln. D2054 CO, Antelope Valley Limestone, in beds 

flanking bioherm, 172 ft above base of bioherm (240 ft 

above base of formation). 

Trilobites :

Sclenoliarpes sp. 

Illaenus sp.

USGS colln. D1970 CO, Antelope Valley Limestone, muddy 

limestone flanking bioherm about 195 ft above base of 

bioherm (263 ft above base of formation). 

Brachiopods :

Anomalorthis sp. 

Orthidiella sp. 

Linguloicl, large species 

Trilobites : 

Nileus sp. 

Illaemis sp.

Kawina sp. (pygidium) 

Ectenonotus whittingtoni Ross

USGS colln. D1971 CO, Antelope Valley Limestone, from beds 

flanking bioherm, 207 ft above base of bioherm (275 ft 

above base of formation) . 

Brachiopods:

Anomalorthis sp. 

Orthidiella? sp. 

Cuparius sp. 

Camerellid, undet. sp. 

Trilobites:

Nileus aff. N. scrutator (Billings) 

Carolinites genacinaca Ross. 

Ectenonotus whittingtoni Ross.

Miracybele sp. 1 (Ross, 1967, p. D25, pi. 8, figs. 23-25) 

Protocalymene sp. 

Conodonts (identified by J. W. Huddle, written commun.,

May 1, 1970): 

Periodon aculeatus Hadding : Number

ligonodina elementcordylodus element. 

oistodus element___ 

Fragments. _______

Drepanodus n. sp______ _

specimens 

_ 6 

_ 2 

_ 1 

_ 4 

_ 1

USGS colln. D1978 CO, Antelope Valley Limestone, lower member, beds of flanking bioherm about 222 ft above base of 

bioherm (290 ft above base of formation). 

Brachiopods:

Orthidiella sp.

Orthambonites minusculus Phleger 

Trilobite:

Ectenonotus sp.

Conodonts (identified by J. W. Huddle, written commun., 

May 1, 1970): Number

of 

specimens

Belodina triangularis Stauffer__ _______________ * 1

Drepanodus suberectus (Branson and Mehl)_____ 4

Oistodus multicorrugatus Harris (twin form) _ __ 2 

Periodon aculeatus Hadding:

cordylodus element___________-___-______ 1

ligonodina element____ __________________ 4

roundya element___-____ _____-_--__-____ 2

ozarkodina element- ___-_____-_-_-_-_-_- 3

oistodus element._--___-_-______-__-___- 1

Scolopodus aff. S. inculptus (Branson and Mehl)_ 1

'Contamination (?).

USGS colln. D2055 CO, Antelope Valley Limestone, lower 

member, from beds flanking bioherm, 244 ft above base 

of bioherm (312 ft above base of formation). 

Brachiopods:

Orthidiella sp. 

Orthambonites sp. 

Asteroid ossicles

Conodonts (identified by J. W. Huddle, written commun., 

May 1, 1970): Nvmber

°f 

spdcimens

Acodus sp__-_______________________________ 1

Acontiodus sp____-______.___________________ 1

Acontiodus sp_----_______-__________________ 1

Distacodus cf. D. stola Lindstrom____________ 1

Drepanodus suberectus (Branson and Mehl)_____ 3

Drepanodus (hooded form)___________________

Drepanodus (winged form) ___________________

Oepikodus sp_______________________________

Oistodus longiramus Lindstr6m______ __________

Oistodus multicorrugatu(>:

Ribbed form___________________________ 2

Twin form.____________________________ 1

Periodon aculeatus Hadding:

roundya element.________-__--__-___-.__ 1

ligonodina element._____________________ 5

cordylodus element..--___-__--_-________ 3

ozarkodina element______________________ 1

USGS colln. D2057 CO, Antelope Valley Limestone, lower 

member, beds flanking bioherm; approximately 295 ft 

above base of bioherm (363 ft above base of formation). 

Unidentified cystid

USGS colln. D2048 CO, Antelope Valley Limestone, lower 

member, from beds 1 ft above thickest part of bioherm 

approximately 271 ft above base of bioherm (339 ft 

above base of formation). 

Brachiopods:

Orthidiella sp. 

Orthambonites sp.

Anomalorthis? sp. (pedicle valve, primitive type) 

Trilobite:

Undet. proparian protaspis 

Conodonts (identified by J. W. Huddle, written commun.,

May 1, 1970) : Number of 

specimens

Distacodus cf. D. stola Lindstr6m_______-___._- 1

Drepanodus? n. sp. (like that in D1993-CO)____ 2

Drepanodus n. sp. (also present in D1994-CO)__ 1 

Drepanodus sp..---------------------------- 1

Oistodus inclinatus Branson and Mehl _______ 1

Oistodus sp--.------------------------------ 2

Periodon aculeatus Hadding:

cordylodus form_ _____________________ 3

roundya form_________-___-_-_------__- 3

ligonodina form__.______________________ 1

f alodus ________________--___--------__- 2

Scolopodus sp------------------------------- 1

USGS colln. D2049 CO, Antelope Valley Limestone, lower member, from float derived from 2 to 3 ft of strata above 

thickest part of bioherm approximately 273 ft above 

base of bioherm (340 ft above base of formation). 

Sponge, undet. 

Brachiopods:

Hesperorthis? cf. H. matutina Cooper 

Camerellid indet.

446-051 O - 72 - 3
14 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

USGS colln. D2052 CO, Antelope Valley Limestone, lower member, 20-40 ft above highest part of bioherm approximately 290-310 ft above base of bioherm (358-378 

ft above base of formation). This collection contains 

a great representation of species; however, the presence 

of Phragmorthis and Leptellina suggested that it had 

been contaminated by float from higher on the mountain. A subsequent check of the locality shows that the 

only possible source of such contamination lies to the 

north and in a position that makes gravity induced contamination impossible.

Bryozoans (O. L. Karklins, written cominun., July 24, 

1970) :

"This collection contains several bryozoan specimens, 

six of which were thin sectioned. All specimens are poorly 

preserved: the skeletal material is recrystallized or replaced by silica. On the basis of the general appearance 

of the zoarial structure, five specimens can be assigned 

to one taxon, probably a nicholsonellid genus and one 

specimen to a different genus. The five "nicholsonellid-like" 

specimens appear to be the same or similar to those which 

occur in collection D821 CO (Meiklejohn Peak) and in the 

collection D2074-CO (lower Antelope Valley Limestone, 

Orthidiella zone, south of mouth of Keystone Canyon, 

Tybo quadrangle).

Ostracodes (Jean Berdan, oral commun., Nov. 20, 1970) : 

Eoleperditia aff. E. bivia (White) 

Eurychilina sp. 

Leperditellal sp. 

Brachiopods:

Anomalorthis cf. A. fascicostellatus Ross 

Orthambonites, two spp. 

OrtJiidiella sp. 

Cuparius sp.

Phragmorthis antiqua Ross, n. sp. 

Leptellina sp. (one specimen) 

Trilobites:

Nileus sp.

Ectenonotus cf. E. whittingtoni Ross 

Pseudomera sp. 

Raymonditesl n. sp. 

Remopleurides sp. 

Illaenits auriciilatus Ross 

Protocalymene sp. 

Kawina sp. (pygidium)

Pelmatozoans (identified by James Sprinkle, written commun., Nov. 7, 1969) : 

Blastoidocrinusl elongatus Sprinkle 

Blastoidocrinusl nevadensis Sprinkle

Conodonts (identified by J. W Huddle, written commun. 

May 1, 1970):

Drepanodus suberectus (Branson and Mehl).

Oistodus multicorrugatus Harris:

smooth f orm_______________________

type form __________________________

twin form__________________________

Oistodus aff. 0. venustus Stauffer__________

Pcriodon sp.:

cordylodus form_____________________

Scandodus sp___________________________

Scolopodus sp_. _________________________

Number 

specimens 

1

USGS colln. D821 CO, Antelope Valley Limestone, 315 ft above 

base of biohermal limestone (383 ft above base of formation). (See Ross, 1964, p. C28.) 

Brachiopods:

Orthidiella cf. O. longwelli Ulrich and Cooper 

Anomalorthis cf. A. fascicostellatus Ross 

Ortliam'bonites sp. 

Dasycladacean algae

Concerning the ostracodes from this collection, Jean M. 

Berdan (written commun., 1962) reported: "This collection contains Eoleperiditia sp. aff. E. bivia, Leper ditellal, 

Aparchites?, Ballardina simplex Harris, and unidentified 

small smooth ostracodes. Eoleperditia sp. aff. E. bivia and 

Ballardina simplex"? occur in the lower part of the Antelope Valley Limestone in Goodwin Canyon, in the Eureka 

District. The other forms listed here also occur in the 

Antelope Valley Limestone elsewhere in Nevada, but seem 

to have longer ranges. The form listed as Eoleperditia 

sp. aff. E. bivia is not E. bivia s.s., but a closely related 

species, which may prove to have stratigraphic value."

USGS colln. D741 CO, Antelope Valley Limestone, lower member, silty beds above highest part of bioherm. 

Brachiopods:

Orthidiella sp.

Anomalorthis sp. 

Trilobites:

Trinodus sp.

Nileus sp.

Ectenonotus sp.

Pseudomera sp.

USGS colln. D818 CO, Antelope Valley Limestone, 340 ft 

above base of biohermal limestone (408 ft above base of 

formation) (Ross, 1964, p. C27).

Brachiopods:

Orthidiella longwelli Ulrich and Cooper

cf. O. costellata Cooper 

Trilobites:

Agnostid

Dimeropygid 

Dasycladacean algae

USGS colln. D1993 CO, Antelope Valley Limestone, rubbly beds 

above bioherm, approximately 415 ft above base of 

formation. 

Brachiopods:

Orthidiella longwelli Ulrich and Cooper 

Ingria cloudi Ulrich and Cooper 

Trilobite:

Ectenonotus sp. 

Pelmatozoans:

Blastoidocrinus? sp. 

Conodonts (identified by J. W. Huddle, written commun.,

May 1, 1970):

Number of 

specimens

1

13

1

5

1

11

1

4

Drepanodus suberectus------ __________________

Drepanodus n. sp_______----------_---------

Oepikodus aff. 0. quadratus (Graves and Ellison)_ 

Oistodus sp---------------------------------

Oistodus sp---------------------------------

Oistodus parallelus Pander__________________

Panderodus sp.-.--.------------------------

Paltodus sp____-________------_------__---
COLLECTIONS FROM FLANKING BEDS 15

Number

°f 

specimens

Periodon aculeatus Hadding_ _________________ 14

roundya element 

cordylodus element 

ligonodina element

USGS colln. D2051 CO, Antelope Valley Limestone, lower member ; from float derived from top 20 ft of the member. 

Trilobite:

Pliomerops cf. P. canadensis (Billings)

USGS colln. D2056 CO, Antelope Valley Limestone, lower

member; from top 8 ft of lower member. 

Sponges:

Two genera undet.

USGS colln. D1975 CO, Antelope Valley Limestone, from float 

derived 420 ft above base of formation and from above 

bioherm.

Brachiopods:

Isophragma? sp. or Taphrodonta one sp.

Anomalorthis sp.

Orthidiella sp.

Desmorthis? sp. or Orthambonites? sp. (small)

Ingria doudi Ulrich and Cooper

Cuparius sp. 

Trilobites:

Bathyurellus sp.

Pseudomera sp. (pygidium, dissolved in order to obtain

free silicified specimen of Anomalorthis) 

Conodonts (identified by J. W. Huddle, written commun., 

May 1, 1970) :

Oistodus mullicorrugatus Harris:

Number

of 

specimens

ribbed. _________________________________ 1

smooth._______________________________ 2

two denticles,__________________________ 2

Periodon aculeatus Hadding:

ligonodina element._____________________ 2

Scolovodus sp._____________________________ 2

Several genera are worthy of note because of stratigraphic position. 8chi0anibon, Cyrtonotella, Phragmorthis, and Pliomerops are genera not previously reported 

as low as the OrtJiidiella zone in North America. Occurrences of three of these genera are in older strata 

in northwestern Europe. Valdar Jaanusson (written 

commun., May 25, 1970) has called attention to the 

occurrence of ScMzatribon in Tremadocian strata of 

northwestern Russia. He has further noted that the 

type species of Cyrtonotella came from the Kunda 

Stage (Llanvirn) of the Leningrad district and Estonia and that Cyrtonotella has been reported as early 

as the Langevoja Substage of the Volkhov Stage (Late 

Arenig). Pliomerops, according to Jaanusson, is not 

uncommon in Arenig strata in the Baltic region.

The identification of Ingria within the bioherm are 

questionable for lack of good interiors of valves; all

these specimens were identified initially as Paucicostella. But interiors of Paucicostella have never been 

described, and all known species come from correlative 

boulders in the Mystic Conglomerate of Quebec 

(Cooper, 1956, p. 31). Exteriors are virtually indistinguishable from those of immature shells of Ingria 

doudi which is present in beds flanking the bioherm. 

Inasmuch as no practical way has been found to distinguish Paucicostella from Ingria except that the 

former is found in reefs and the latter in flanking 

beds, they have been considered synonyms here.

Anomalorthis is ordinarily represented in the Ortliiclietta zone by a primitive species with very low 

cardinal area and rudimentary pseudospondylium. 

Here a species almost the same as A. fascicostellatus 

Ross is present as low as collection D2052 CO. This 

fact plus the presence of Phragmorthis in D2052 CO 

led me to consider that some float from higher on 

the mountain probably was included in this collection. 

Similarly, the discovery of a peculiar bathyurid pygidium tentatively assigned to Raymondites in the 

same collection and Pliomerops cf. P. canadensis in 

D2051 CO suggest possible contamination from above. 

However, Pliragmortliis is present as low as collection 

D1994 CO, and Pliomerops seems to be in the high 

part of the bioherm as high as collection D1968 CO.

Dr. A. J. Rowell kindly examined inarticulate brachiopods 

from two of the collections in the bioherm. His examination, 

he insists (written commun., Apr. 16, 1970), resulted in only 

a "quick list":

"Colln. D2058 CO:

Rliysotreia sp. Nov. 1.

Torynelasma, sp. A Nov.

Torynelasma sp. B Nov.

Conotreta sp.

IConotreta sp. B.

Eoconulus sp.

Glossellinid, gen. and sp. indet.

Dictyonites sp. (fragment)

Acrotretid gen. Nov. X sp. 1 

Colln. D1973 CO:

Rhysotreta sp. Nov. 1

Torynelasma sp. A Nov.

IConotreta sp. B

Acrotretid gen. Nov. sp. 1"

"Although generically very similar to the Pratt Ferry fauna, 

when one looks at the material closely there are consistent 

differences. I do not really know what they mean * * *."

It is of interest that conodonts from the Orthidiella zone 

over a wide area in Nevada have led J. W. Huddle (in Ross, 

1970) and others to remark on a resemblance to the Pratt 

Ferry beds of the Appalachians.

Concerning the conodonts listed on preceding pages, Huddle 

(written commun., May 1, 1970) comments:

"The abundance of Periodon in these collections agrees with 

what you called the lower member of the Antelope Valley 

at Ikes Canyon and in the Groom Range. It occurs through-
16 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

out the Fort Pena Formation and in title Pratt Ferry Formation, Ala., but has not been reported by Ethington from the 

section at Ibex, Utah. Periodon and Oepikodus are both members of the Atlantic Ordovician conodont fauna. Periodon may 

be restricted to certain facies."

SUMMARY OF FOSSIL DISTRIBUTION

The stratigraphic occurrences of fossils presented 

on the foregoing pages are summarized in figures 10 

and 11. Positions of collections relative to the bioherm are shown in figure 10. The distribution of 

genera is shown in figure 8.

Distribution at the species level is confusing and 

lacks stratigraphic continuity. Species, for instance, 

those of Idiostrophia' and Illaenus, are numerous and 

seem to be short, ranging. Nor do they provide a means 

of correlating with other areas, a circumstance already 

noted by Whittington (1965, p. 287-292) in discussions 

of Newfoundland and Quebec species.

The distribution of genera in the bioherm and flanking beds is shown in figure 11. Obviously some genera 

have been found only in the bioherm and others only 

in the flanking beds. Is this because of environmental 

control? Stratigraphic (temporal) control? Incomplete collecting? The answers to each of these questions is "partly, yes."

The genera collected only from the bioherm are:

Schizam'bon

Orthidium

Trematorthis

Notorthis"?

Pleurorthis

Gamerella

IdiostropJiia

Liricamera

Petroria

Onychoplecia,

Paucicostella (if not immature Ingria)

Eopteria

Glaphurus

Peraspis

Harpillaenus

Endymionia

Heliomera

Lehua

Xystocrania

Apatolichas

Several of these are known from very muddy limestone or shale in other parts of the Basin Kanges; they 

include Perns pis, Liricamera, Orthidium, Notortliisl, 

Trematortliis, and Xystocrania. Camerella is a widespread genus of many environments. Only Pleurorthis, 

Idiostrophia, Lehua, Paucicostella, Petroria, Eopteria, 

GJa-phurus, Endymionia, and Apatolichas seem to be 

"biohermal dwellers,' but even this limited list is unconvincing. Endymionia in Newfoundland occurs in a

shaly part of the Middle Table Head (Whittington and 

Kindle, 1963, fig. 3) as does Onychoplecia (Cooper, 

1956, p. 11) ; neither is found in the reef like boulder at 

Lower Head (Whittington, 1963), in which Lehua does 

occur. Petroria is found in sandy and argillaceous dolomites of the Skoki Formation of the Canadian Kocky 

Mountains (Norford, 1969, p. 21, 37).

The occurrence of a few brachiopod genera Pleurorthis, Idiostrophia, and Paucicostella seems to be related to pure limestone boulders or bioherms in conglomeratic deposits of the Levis Shale at Quebec City 

(Cooper, 1956, p. 15) and the Mystic Conglomerate 

at Phillipsburg, Quebec (Cooper, 1956, p. 31). How 

ever, the genera found in Nevada in both bioherip' 

and coevally deposited muddy limestone are represented in Quebec and Newfoundland boulders as well 

as or better than Pleurorthis, Idiostrophia, and Paucicostella.

A comparison of lists of trilobites found in the reeflike boulder at Lower Head, Newfoundland (Whittington, 1963), in the Table Head Formation (Whittington, 1965, p. 283-285), in the boulders of the Levis 

Shale (Whittington, 1965, p. 291), and in the Mystic 

Conglomerate (Whittington, 1965, p. 291) with those 

from the bioherm and flanking beds at Meiklejohn 

Peak shows a strong general resemblance. There are no 

obvious categories of "reef-dwellers" or "flank dwellers" in the areas of northeastern North America or in 

Nevada. As noted by Koss and Ingham (1970, p. 393), 

time and stage of evolution do not entirely explain 

the similarity of some of these fossil assemblages.

If, however, the biohermal surface were swept by 

storm waves which dumped skeletal debris into deeper 

flanking sediments, the fossils of the flanking beds 

should represent both the biohermal and flanking assemblages. Data shown in figure 11 support this possibility without completely confirming it. In the flanking beds are 35 taxa; 20 have not yet been found in 

the bioherm, but only 15 of these are generically determined. Of the 36 taxa found in the bioherm, 16 arp 

found in the flanking beds at Meiklejohn Peak and ?,11 

but the 10 noted above have been found in Nevada in 

beds comparable to the flanking beds.

Genera of brachiopods, pelecypods, and trilobites are 

tabulated in an attempt to discover reliable indices of 

the two environments. Number of genera is indicated 

in parentheses.

Known only from flanking

Known only from bioherm Known in bioherm and or comparable beds in 

(10) *n flanking beds (Iff) Nerada (5)

Paucicostella (unless Orthidiella Phragmorthis

synonym of Ingria) Trematorthis Anornalorthis

Pleurorthis Cuparius Hespei orthis

Idiostrophia N ileus Leptellina
SUMMARY OF FOSSIL DISTRIBUTION 17

r. , , t , Known only from flanking

Known only from bioherm Known in bioherm and or comparable beds in

(*°) in flanking beds (16) Nevada (5)

Petroria Illaenus

Onychoplecia BathyureUus Isophragma or

Lehua Kawina Taphrodonta

Endymionia Ingria

Glaphurus Carolinitcs

Eopteria Cyrtonotella

Apatolichas Trinodus

Orthambonites

Selcnoharpcs

Pliomerops

Ectenonotus

Heliomera

It is likely that PaucicosteHa is a synonym of Ingria ; 

that likelihood removes another genus from the 10 

seemingly restricted to the bioherm.

The list of five genera known only in flanking beds 

probably is more significant than the list of 10. Although at least four of the 10 genera are known elsewhere in beds that seem unrelated to bioherms, in this 

place they may be indices of an environmental contrast 

not yet understood.

Based on collections made to date, the contrast in 

generic assemblages exists, and will be modified by 

future collections. Why the contrast exists here and 

whether a similar contrast exists in Newfoundland 

and Quebec in coeval strata remains to be seen.

Regarding younger Ordovician bioherms in Sweden, 

Dr. Valdar Jaanusson has called my attention to Warburg's (1925, p. 413-416) tabulation in which she 

showed that none of 41 trilobite genera were restricted 

to bioherms and that only three of 119 species were 

so restricted.

DESCRIPTIONS OF FOSSILS

Phylum BRACHIOPODA 

Class ARTICULATA

Genus ORTHIDIUM Ulrich and Cooper, 1938 

Orthidium bellulum Ulrich and Cooper

Plate 1, figures 1-5

Orthidium bellttlum Ulrich and Cooper, 1938, Geol. Soc. America Spec. Paper 13, p. Ill, pi. 16F, figs. 19-26. 

Orthidium licllulum Ulrich and Cooper. Cooper, 1956, Smithsonian Misc. Colln., v. 127, p. 340, pl.30A, figs. 1-5.

Orthidium cf. 0. bellulum Ulrich and Cooper. Ross, 1970, U S.

Geol. Survey Prof. Paper 639, p. 54, pi. 1, fig. i.

Figured specimens. USNM 167177a, b.

Occurrence. USGS collection D1973 CO, 60-65 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak.

Discussion. Orthidium bellulum occurs low in the 

biohermal mass at Meiklejohn Peak and may be far 

more abundant than is apparent, Many specimens removed from the coarsely calcitic matrix are decorticated, like that illustrated on plate 1, figure 5; such

specimens cannot be identified with confidence, yet are 

representative of a large number.

O. leUulum, differs from 0. larnesi Ross in its greater width, shallower pedicle valve, and wider spacing 

of concentric lamellae. O. fimbriatum Cooper has 

ornamentation similar to that of O. lellulum, a deep 

pedicle valve like that of O. bamesi, and a sulcus in 

both the brachial valve and the pedicle valves.

O. belluhun occurs at Meiklejohn Peak low in the 

OrtMdietta zone. Listed by Cooper (1956, p. 127) from 

his RhysostrophM zone in the Toquima Range the 

species is one of several that show the Rhysostrophia 

zone to be synonymous with the Orthidiella and Anomalorthis zones; at Ikes Canyon, O. bettidwm, occurs 

516 feet below the top of the Antelope Valley Limestone (USGS colln. D1516 CO, Ross, 1970, p. 54) in 

an OrtMdieUa zone fauna.

Orthidium? aff. 0. fimbriatum Cooper 

Plate 1, figures 6-10

Two unusual brachiopod specimens have been found 

in the lowest beds of the bioherm at Meiklejohn Peak. 

These are unequally biconvex shells that have a strong 

sulcus in both valves, lamellose ornamentation, and 

faint radial ribbing.

Shells large for the genus, less than twice as wide as 

long. Greatest shell width near midlength; cardinal 

angles obtuse. Outline almost elliptical, with front 

margin obtusely indented at midline. Pedicle valve almost twice as deep as brachial valve. Surface very 

faintly costellate and concentrically lamellose. Costellae spaced about two per millimeter, lamellae about 

four per millimeter.

Pedicle valve with greatest convexity near prominent umbo. Sulcus begins at nmbo, deepening and widening anteriorly, involving about one-third width of 

valve at anterior margin. Flanks of valve convex. 

Umbo protrudes behind hinge. Cardinal area curved 

in lateral profile, apsacline.

Brachial valve evenly convex in both lateral and 

anterior profiles except for shallow median sulcus. 

Umbo inconspicuous.

No interiors available.

Measurements 01 figured specimens are given below. 

L/W indicates ratio of length to width. Parentheses 

indicate estimated measurement.

USNM Length 

(mm)

Width 

(mm)

Hinge 

width 

(mm)

Thickness 

(mm) L/W

167178b. 

167178a_

5. 1 

8. 3

8.5 ? 

13.3 (10.5) 6. 5

0. 6 

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FOSSIL USGS 

NO. COLLECTION 

Orthidiella 

Cuparius

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Selenoharpes 

Pliumerops

Eetenonatus

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Q Shumardia 

2 Ischyrophyma? 

33 Pseudohystncurus 

Carrz'rte'a 

O 

O 1 sp. Miracybele 

C mene ly Protoca 

3D

3D Anomalorthis 

^ species large Linguloid, 

UJ

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cystoid Unident. 

TI 

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^ matutina H. cf. Hesperorthis 

z Leptellina 

Pseudomera

DOm ? Raymotidites 

oW Remopleurides 

ho Blastmdocrinus? 

^ algae Dasycladacean 

Taphrodonta? or Isophragma? 

IIMIT member Middle 

Limestone Valley Antelope 

1

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GENERA OCCURRING IN BIOHERM (36) ?

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FIGUKE 11. Ranges of genera of trilobites and brachiopods in flanking beds, in bioherm, and in b
20 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Occurrence. USGS collection D1991 CO, 10 feet 

above base of bioherm. Antelope Valley Limestone, 

Meiklejohn Peak.

Discussion Because of lack of interiors, generic 

assignment of these specimens is very uncertain. The 

only other Ordovician species that combines the same 

kind of ornamentation and sulci in both valves is 

Orthidium finibriatum Cooper from the Table Head 

Formation of Newfoundland (Cooper, 1956, p. 340- 

341, pi. 31A, figs. 1-6). O fimbriatum is smaller and 

has closer spaced and stronger costellae and more widely spaced lamellae. The Nevada species is clearly not 

conspecific, but it almost certainly is congeneric. O. 

gemmicidum (Billings) has an accentuated sulcus on 

the brachial valve but lacks the deep sulcus in the pedicle valve (ITlrich and Cooper, 1938, pi. 16G).

Genus TREMATORTHIS Ulrich and Cooper, 1936

Trematorthis Ulrich and Cooper, 1938 Geol. Soc. America Spec. 

Paper 13, p. 112-113.

Trematorthis may be fairly common in the bioherm 

at Meiklejohn Peak. However, it is virtually impossible to distinguish it from Orthidiella under the best 

conditions of preservation unless one finds a specimen 

with pseudodeltidiimi intact. Such specimens are extremely rare. One specimen of Trematorthis was found 

in collection D1973 CO.

Trematorthis sp.

Plate 1, figures 11-14

Complete specimen probably immature. Semielliptical in outline, hinge width twice the length. Cardinal 

angles acute. Brachial valve sulcate; sulcus occupying 

50° sector. Costellae thin, subangular, spaced four to 

five per millimeter at front edge of shell that is 4.5 

mm in length. Costellae in at least three generations 

by bifurcation and implantation; have bundled appearance.

Ventral valve gently convex, subcarinate from beak 

to front margin. Cardinal area apsacline, almost catacline, very low; its altitude only 0.75 mm in shell 

4.5 mm long. Pseudodeltidium strongly arched.

Interiors of both valves unknown.

Measurements of figured specimen are given below. 

L/W indicates ratio of length to width. L/HW indicates ratio of length to hinge width.

USNM

Length

(mm)

Hinge

Width width

(mm) (mm) L/W L/HW

167l79a. 4. 5 7. 5 9. 1 0.6 0. 5

Occurrence. USGS collection. D1973 CO, lower 

member, 60-65 feet above base of bioherm, Antelope 

Valley Limestone, Meiklejohn Peak.

Discussion. Two pedicle valves (pi. 1, figs. 11, 12) 

may belong to this same species. Ornamentation is almost identical. One specimen (pi. 1, fig. 11) possesses a 

similar outline, but the other (pi. 1, fig. 12) mpre closely 

resembles Trematorthis masoni or Orthidiella longwelli in outline and convexity. Possibly neither belongs 

to Trematorthis. Characters of the interiors have not 

been ascertained.

Genus PLEITRORTHIS Cooper, 1956

This genus is known from the Mystic Conglomerate 

of Quebec (Cooper, 1956, p. 31, 329-332), from the 

Table Head Formation of Newfoundland (Cooper, 

1956, p. 11, 331-332), and from the Treiorwerth Formation of Anglesey, Wales (Bates, 1968, p. 134). Specimens described here are the first reported from Nevada; they were found low in the bioherm at Meiklp 

John Peak.

Pleurorthis beattyensis Ross, n. sp. 

Plate 1, figures 15-21

Shells almost semielliptical in outline, hinge equaling 

greatest width, length about six-tenths of the width. 

Surface fascicostellate; costellae numbering three to 

four in space of 1 mm at anterior margin, bundled into 

fasces of three to five costellae. Approximately 4 fasces 

in 5 mm at front margin. Valves almost equally biconvex in lateral view.

Pedicle valve very broadly convex in anterior view. 

Flanks flattened, particularly in the posterolateral 

parts. Valve broadly and faintly sulcate at anterior 

margin; greatest convexity between midpoint and low 

limbo. Pedicle muscle scars trilobed, confined to posterior quarter of shell.

Brachial valve initially sulcate, changing to very 

broadly and inconspicuously uniplicate. Moderately 

convex in lateral and anterior views; posterolateral 

flanks slightly concave. Interior not observed.

Measurements of figured specimens are as follows:

USNM Type Valve

Hinge ThickLength Width width ness Costel- 

(mm) (mm) (mm) (mm) lae

167180____ Holotype- Both. .15. 0 21. 6 24. 7 6. 2 4 fasces 

per 

5mm

167181a_ _ Paratype_ Brachial__13. 8 22. 8 22. 8 

167181b_._____do-__---_-do-____14. 6 22.0 22.0
DESCRIPTIONS OF FOSSILS 21

Occurrence. USGS collection D1973 CO, 60-65 feet 

above base of bioherm, Antelope Valley Limestone 

Meiklejohn Peak.

Discussion. Plcurorthis beattyensis closely resembles Pleurorthis fascicosteUatus Cooper in outline and 

profile, but it differs in being somewhat smaller and 

in having finer costellae in more pronounced fasces. 

P. convexa Cooper is a smaller, more convex species, 

but otherwise is similar.

Preservation of the Nevada specimens is not perfect. 

Decortication of the outer shell surface when specimens 

are broken from coarse calcitic matrix hinders a reliable census of the considerable variation these shells 

seem to show. Cooper (1956, p. 329-332) found that he 

could separate five species of PleurortMs in the Mystic 

Conglomerate; by use of similar criteria more than one 

might be distinguished here.

However, the importance of the occurrence is stratigraphic; it provides another in the growing number of 

links between the OrthidieHa zone of Nevada and the 

so-called Whiterock faunas of the east.

Pleurorthis? sp. 

Plate 2, figure 1

A single complete shell and three pedicle valves of 

moderate convexity and strongly fascicostellate ornamentation are tentatively assigned to Pleurortliis; one 

of the pedicle valves is illustrated as a matter of record. The anterior commissure seems to lack the uniplicate form common in the genus. Costellae are spaced 

about three per millimeter, but only half of the costellae seem to be involved in fascicles of which there are 

three to four in 5 mm along the margin.

Figured specunen. USNM. 167182.

Occurrence. USGS collection D1990 CO, 45 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak.

Genus CYRTONOTELLA Schuchert and Cooper, 1932

Oyrtonotetta Ulrich and Cooper. Cooper, 1956, Smithsonian 

Misc. Colln., v. 127, p. 318-319.

All specimens obtained from the bioherm are in a 

very nearly pure calcite matrix. It is therefore very 

difficult to separate one from the other in order to 

determine the character of structures inside the valves. 

It has not been possible to demonstrate the existence 

of a cardinal process or to determine if one is lacking. 

If a cardinal process is present in these specimens it 

seems more than likely that CyrtonotelU is represented.

The genus CyrtonotelU was reported from strata of 

Ashby, Porterfield, and Trenton age in the Appalachians, according to Cooper (1956, p. 319-326, chart 1).

Its possible occurrence within the Ortlridiella zone at 

Meiklejohn Peak is therefore unexpected in terms of 

age. Two species were reported by Williams (1962, p. 

105-106) from the Stinchar Limestone and from Ardwell and Balclatchie Mudstones, Girvan district, Scotland. The genus was also reported in Thailand (Hamada, 1964, p. 213-217). However, Dr. Valdar Jaanusson (written commun., May 25, 1970) has noted that 

Cyrtonotetta occurs in the strata of the Kunda and 

Volkhov Stages (Early Llanvirn and Late Arenig) in 

Russia and Estonia (Rubel, 1961).

Cyrtonotella? aff. C. fasciculata Cooper 

Plate 2, figures 2-6

Outline semielliptical, widest at hinge line; cardinal 

angles alate when preserved. Hinge width from 1.5 

to 1.8 times wider than long. Profile concavo-convex. 

Brachial valve bearing narrow sulcus within a sector 

of 65° ; sulcus much less pronounced at anterior margin 

than proximally. Pedicle valve moderately convex; 

greatest convexity close to beak.

Ornamentation fascicostellate. Medianly in a space 

of 5 mm at a radius of 5 mm, costellae number 12-14; 

and at a radius of 10 mm number eight. Finer costellae 

probably not fully preserved in any specimen of sample; therefore, rib count may be a little higher at 10 

mm radius.

Measurements of specimens are given below. Parentheses indicate estimated measurement.

USNM

Hinge Costellae in 5 mm Valve Length width 

(mm) (mm) At radius At radius 

5 mm 10 mm

167183a

167183b__-

167183c.___

167183f__._

167183e_.__

do

10. 8

9. 0

8. 0

9. 0

12. 0

14. 5+ __

16. 0

14. 0

(16.0) __

(20)

12

12

14

8

8

(10)

8

Occurrence. USGS collection D1973 CO, 60-65 feet 

above base of bioherm, lower member of Antelope 

Valley Limestone, Meiklejohn Peak.

Discussion. Latex casts of brachial interiors (pi. 2, 

fig. 2) were made after shell material was picked from 

matrix. This method does not lend itself to preparation of the brachiophores or the cardinal process which 

I have been unable to differentiate with certainty. 

Peeling of the shell by calcining proved ineffective because of the similarity of shell and matrix.

This species most closely resembles C. fasciculata, 

Cooper (1956, p. 320-321, pi. 41A) in size, outline, and 

ornamentation. Cooper's species has somewhat finer

446-051 O - 72 - 4
22 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

costellation and does not seem to be deeply concave. 

No other species has a coarse fasciculate costellation.

Genus PHRAGMORTHIS Cooper, 1956 

Phragmorthis is represented in beds flanking the reef 

at Meiklejohn Peak. This occurrence of the genus seems 

to be the oldest known. Specimens come from two 

collections D2052 CO and D1994 CO (fig. 7). In specimens from the stratigraphically older collection the 

"pseudospondylium" of the pedicle valve is only 

slightly developed, and the median septum of the 

brachial valve is about as strong as that in species 

of Skenidioides. In the stratigraphically younger specimens the pseudospondylium, thickened floor, and paired 

pallial trunks are well developed, but the median septum of the brachial valve lacks the exceptional height 

found in the type species, Phragmorthis buttsi Cooper. 

These Nevada specimens may be the ancestral forms 

of a genus previously known only from strata of 

Porterfield and younger age. Phragmorthis is another 

genus that may link the Orthidietta zone of Nevada 

with the Pratt Ferry beds of Alabama.

Phragmorthis antiqua Ross, n. sp. 

Plate 2, figures 7-18

Shells very small, wider than long, moderately convex for the genus. Anterior commissure angularly sulcate. Cardinal extremities right angled to obtuse. Lateral margin rounded; anterior margin indented medially. Surface fascicostellate; costellae spaced five to 

seven per millimeter at anterior margin.

Pedicle valve moderately deep; its greatest convexity close to beak and along midliiie forward; however, not markedly carinate. Flanks evenly rounded, 

not particularly swollen. Cardinal area apsacline; its 

width 2.5 times its altitude. Delthyrium narrow, almost parellel-sided. Dental plates receding. Pseudospondylium occupies one-third midleiigth of shell. Pallial trunks extend forward from dental plates close to 

margin. Area between trunks somewhat thickened.

Brachial valve creased by wide angular sulcus. Median septum distinct but low. Cardinal process highly 

variable in development; almost absent from some 

specimens but greatly thickened in others. Adductor 

scars composed of an anterior and posterior pair separated by median septum.

Measurements of figured specimens are given below. 

L/W indicates ratio of length to width. Parentheses 

indicate estimated measurements.

Occurrence. USGS collection D 2052 CO, Antelope

USNM

167184___ 

167185a__

167185b__.

167185c.._.

] 

Type Valve

Holotype___ Brachial___

_do Pedicle

L/ength 

(mm)

3. 1

2. 7

2. 1

2. 1

Width 

(mm)

5. 2 

4. 6

3.4

3. 6

Thickness 

(mm)

1. 3 

1. 3

1. 4

/I 0\

L/W

0.6

. 62

. 58

Valley Limestone, lower member, thin beds flanking 

bioherm, Meiklejohn Peak.

Discussion. Phragmorthis antiqua is characterized 

by its wide outline, moderate convexity, and low median septum in the brachial valve. The brachial sulcus 

is like that of P. buttsi Cooper, but is much wider than 

that of P. crussa. The median septum is not the enormous partition that Cooper (1956, pi. 146, fig. 36) illustrated for P. buttsi.

If this species were larger, the number of costellae 

per 1 mm at the front margin might be in the range 

of P. butttti, but they would not be as coarse as in P. 

crassa.

Phragmorthis antiqua differs from specimens collected in the stratigraphically lower collection D1994 

CO in its better development of the"pseudospondylium" of the pedicle valve. This structure is comparable 

to that of Anomalorthis. Because Anomalorthis also occurs in D2052 CO, it is very difficult to distinguish 

small specimens of Anomalorthis from Phragmorthis.

Genus CAMERELLA Billings (1859)

There are at least two species in the lower biohermal 

limestone at Meiklejohn Peak that defy final identification. Interiors are not available for these forms. 

They belong in a group that Ulrich and Cooper (1938) 

named Rhynchocamara, and that Cooper (1956, p. 

562), without explanation, placed in synonymy with 

CamereUa. There is a group of these shells, such as 

Camerella Ireviplicata Billings, which as suggested by 

Cooper (1956, p. 505) may be late Canadian in age. 

They have inflated brachial valves, and are costate only 

around the margin of the shell. In the bioherm at 

Meiklejohn Peak these shells demonstrate considerable 

variety of forms. Whether this variety represents one 

or two extremely variable species or a great many species can probably not be known with certainty.

These forms are associated with Idiostrophia in some 

collections. Although not found in the bioherm, Liricamem is from beds equivalent to those flanking the 

bioherm. Both of these genera are mimicked to some 

degree by varieties of the little Camerellas. Cooper 

(1956, p. 590, pi. 113A) described a small species and 

assigned it tentatively to Idiostrophial. This little form
DESCRIPTIONS OF FOSSILS 23

lacks the characteristically flattened sides of true Idiostrophia (Cooper, 1956, pi. 109 A-E), as do the shells 

of the small species of Camerella here under consideration. Some immature specimens of Idiostrophia, 

however, also lack such sides.

Camerella sp. 1 

Plate 3, figures 1-18

Outline ovoid to subcircular; longer than wide. 

Greatest width generally six-tenths of length from 

beak. Posterior surface smooth; costae present along 

anterior margin. Costae number 20-30, spaced two per 

millimeter. Commissure very gently uniplicate.

In lateral profile, pedicle valve evenly convex. In 

anterior view, flanks slope from rounded crest and 

steepen near margins. Umbo inconspicuous.

Brachial valve most markedly convex in posterior 

half. In anterior view increasingly convex from midline to margin.

Figured specimens. USNM 167186a-d.

Occurrence. USGS collection D1973 CO.

Discussion. There is considerable variation in relative thickness and apparent convexity of shells of this 

species. Some specimens (pi. 3, figs. 5-9, 15-18) might 

be grouped with Idiostrophia because of the flattened 

sides just anterior to the beak. This flattening is seemingly the result of unusual growth. One specimen 

(pi. 3, figs. 10-14) is of very low convexity and of subcircular outline and in these respects resembles a 

smaller specimen from USGS collection D1991 CO 

(pi. 4, figs. 1-t).

Camerella sp. 1 closely resembles but is narrower 

than G. siiblaecis (Ulrich and Cooper) (Ulrich and 

Cooper, 1938, p. 251, pi. 56E). Its costae are finer and 

more numerous than those of G. breviplicata Billings.

Camerella sp. 2 

Plate 4, figures 5-8, 14-17

Outline narrowly ovoid. Widest part of shell in front 

of midpoint. Pedicle valve the deeper; in lateral profile, greatest convexity of both valves behind midlength. Surface costate around anterior margin; costae 

number 10-15, spaced two per millimeter except in one 

specimen (pi. 4, figs. 14-17). Commissure slightly uniplicate.

Figured specimens. USNM 167l88a, b.

Occurrence. USGS collection D1966 CO.

Discussion. In number of costae, this species is similar to Camerella, breviplicata Billings but is narrower 

than that form. The largest specimen possesses a poorly 

defined fold and a sulcus composed of two costae; it is 

the only specimen with this feature. As a result, I have

considered that these specimens may be aberrant; if 

not, they probably represent yet another species.

Genus IDIOSTROPHIA Ulrich and Cooper, 1936

Idiostrophia Ulrich and Cooper, 1936, Jour. Paleontology, v.

10, no. 7, p. 631. 

Idiostropliia, Ulrich and Cooper, 1938, Geol. Soc. America Spec.

Paper 13, p. 249. 

Idiostropliia Ulrich and Cooper. Cooper, 1956, Smithsonian

Misc. Colln., v. 127, p. 587.

Cooper (1956, p. 587-588) has described the peculiar 

lateral ridges of the pedicle and brachial valves of 

Idiostrophia and has homologized them with the flanks 

of valves of Camerella. These lateral ridges and the 

triangular outline of the shell distinguish Idiostrophia. 

However, collections from the bioherm at Meiklejohn 

Peak prove that these characteristics may not be quite 

so pronounced in some specimens as Cooper's illustrations (1956, pi. 109, figs. 4, 6, 11, 12) suggest.

For instance, one collection (USGS colln. D1968 CO) 

has produced camerellid shells packed together in a 

limestone matrix like peanut brittle. A piece of limestone about the size of one's fist yielded 567 shells, of 

which 78 were broken and therefore were left out of 

consideration. These shells were sorted and measured 

in an effort to determine whether they represented one 

or several species. The results have been exceedingly 

disconcerting.

Some specimens are almost smooth, having poorly 

developed costae and very low flattened "lunulelike" 

sides. Others have strong costae and high "lunules." 

Some are wider than long, others longer than wide. 

Some have as many as 13 costae, others have none. Efforts to separate specimens according to these characteristics have produced no consistent clear-cut groupings. It is clear that study of a small sample would 

probably have resulted in designation of three or four 

species. The present large sample has produced many 

intermediate specimens between various extremes, discouraging any attempt to split the sample. And yet the 

specimens do show tendencies worth noting.

In general, all specimens are triangular in outline. 

Some have slightly convex lateral outlines, others have 

straight diverging sides, and another group has a distinctly flairing bell-shaped outline; in this last group 

the flattened "lunulelike" sides tend to have a concave 

outline.

Convexity is highly variable but may eventually 

prove to be one of the characteristics on the basis of 

which a division of the sample can be made. The small 

group of specimens that lack or have only a few poorly 

defined costae invariably have low convexity but may 

have almost any of the various outlines displayed by 

more strongly ribbed shells.
24 FOSSILS FROM THE ORDOVICIAN BIOHE'RM AT MEIKLEJOHN PEAK, NEVADA

Development of the flattened "lunulelike" sides is 

highly variable. In some specimens these sides are high 

and straight so that the shell resembles a sector of a 

thick disk. In others, the "lunules" are very low or nonexistent; a grouping based principally on presence or 

absence of the "lunules" clearly would not be a natural 

one.

Almost all specimens possess a distinct, though shallow, median intercostal groove on the brachial valve. 

None of the specimens from Meiklejohn Peak bear the 

strong median intercostal groove on both valves as is 

found in Idiostrophia perfecta and /. costata (Cooper, 

1956, pi. 109, A, B). Most of them do have such a 

groove on the brachial valve. A few such as /. paucicostata Cooper, /. plicata Cooper, and /. digitata 

(Brogger, 1882, p. 52, Tab. XI, fig. 2a-c), and /. nuda 

Cooper lack any such groove.

Only in the one coquinoid collection (USGS colln. 

D1968 CO) from the biohenn does one have difficulty 

determining what should or should not constitute a 

species. The shells probably were washed off the surface of the reef into a narrow crevice or channel. Yet 

some shells show signs of interference during growth, 

suggesting that they may have been packed close together in life. Such a highly competitive environment 

may have resulted in a high degree of variation out 

of which a few stable species evolved and spread.

Idiostrophia n. sp. A 

Plate 4, figures 9-13

Rliynclwnella digitata. Brogger, 1882, Die Silurischen Etagen 

2 uncl 3, p. 52, pi. XI, figs. 2, a, b, c.

This description is based on a single specimen, that 

illustrated by Brogger (1882, pi. XI, fig. 2).

Outline subtriangular, angle between sides about 

75°. Anterior margin evenly curved. In profile, valves 

equally and strongly convex. Flattened "lunulelike" 

sides well developed, somewhat concave, higher on brachial valve. Costae limited to anterior third of shell, 12 

in number, spaced one per millimeter.

Figured specimen. Paleontologisk Mus. (Oslo) No. 

47089.

Occurrence. Asaphus shale, Toyen district, Oslo. 

Stage 3cB. Within a short distance of the Palaeontological Museum, according to Dr. Gunnar Hemringsmoen (written commun., Feb. 4, 1970).

Discussion. This specimen was assigned by Brogger to RhynchoueUa digitata (von Leuchtenberg). 

Concerning this assignment and synonymy given by 

Brogger, Dr. Valdar Jaanusson (written commun., 

Feb. 2, 1970) commented:

Leuchtenberg's (1843) figure (very poor) and description of 

Terebratula digitata do not resemble Brogger's specimen at all. 

"T." digitata has only 5 costae along the anterior margin and 

this is not a juvenile feature since the shell has about the same 

size as the Norwegian specimen. The outline is triangular and 

the species may belong to Idiostrophia but as the types are 

lost the species digitata is a nomen dubium for all practical 

purposes. The specimen figured by Eichwald (1860, pi. 35, figs. 

12a, b), again, is different from Leuchtenberg's specimen as 

well as from the Norwegian specimen. It has a greater number 

of costae, a less clearly triangular outline, and a more convex 

dorsal valve. It might belong to Camcrella.

Both Eichwald (1860) and Brogger (1882) suggested that 

Terebratnla digitata Leuchtenberg, 1843, may be identical to 

Porambonites acuminatus Pander, 1830. Rubel (1961) has subsequently redescribed the latter species, and has designated a 

neotype. It is a CamereUa (or RJiyncliocamara if this genus is 

valid) and has nothing to do with either Leuchtenberg's species or Brogger's specimen.

It is interesting to note that Ccunerella, appears in 

North America in the Whiterock Stage and in the BaltoScandian area in the lowermost Kunda Stage (Hunneberg Substage or Expansus Limestone, BHIa).

Idiostrophia n. sp. A is larger than any of those 

from the bioherm at Meiklejohn Peak. In outline and 

number of costae it is similar to Idiostrophia perfecta 

and /. nuda\ both of those species have pronouncedly 

stronger convexity of the brachial valve; in 7. nuda 

the convexity is particularly strong close to the umbo. 

In /. perfecta a clear median intercostal groove is 

present on both valves, but the groove is lacking in 

/. n. sp. A.

The importance of Idiostrophia n. sp. A is in indicating a possible correlation between the Orthidiella 

zone and the Scandinavian section.

Idiostrophia lenticularis Ross, n. sp. 

Plate 5, figures 1-25

Shells of low convexity, lacking costae until more 

than 6 mm in length.

Angle between flattened sides 95°-100° in adult 

specimens. Brachial valve the more convex. Pedicle 

valve somewhat flattened near umbo, in lateral profile curving more sharply in front of middle. Brachial 

valve evenly curved in lateral profile. Flattened sides 

low, barely developed in shells more than 3.9 mm long. 

Costae very low and limited to peripheral 1 mm in 

shells more than 6 mm long. Costae number 10, spaced 

one per millimeter.

Holotype. 'VSTSM. 167189.

Pamtypes. USNM 167190a-e.

Occurrence. USGS collection D1968 CO, from 

crevice or channel filling, 168 feet above base of bioherm.
DESCRIPTIONS OF FOSSILS 25

Discussion. I have not yet been able to assemble 

complete series of growth stages for this species because of a gap between specimens 4.5 mm and 5.9 mm 

in length. Nonetheless, the four specimens (pi. 5, figs. 

6-15, 21-25, and USNM 167190e) are believed to be 

assignable immature forms. In these immature stages 

the anterior and lateral profiles are lenticular; in anterior profile the pedicle valve is more convex, particularly behind middle. Median groove on brachial 

valve in immature stages. Extremely faint costae present near center of shells.

Equally small and smaller shells of Idiostrophia 

valdari n. sp. already have several costae well developed (pi. 8, figs. 16-20). Both /. paucicostata and /. 

plicata have strongly developed "limulelike" flattened 

sides, quite different from the low sides of /. lenticularis. I. poUta (Billings) is very similar in outline but 

more convex in profile.

Idiostrophia valdari Ross, n. sp. 

Plates 6-8; plate 18, figures 16-20

The sample on which this description is based numbers about 350 specimens. As noted under the discussion of the genus this sample is exceedingly variable.

Outline subtriangular to bellshaped; valves almost 

equally convex in anterior profile. Brachial valve 

slightly deeper in lateral profile. Sides flattened to form 

a "limulelike" surface; angle of divergence between 

two sides ranges from 50° to 100°. Size of angle depends to some extent on length (size) of shell. (Fortysix percent have an angle of 60°-64°, IT percent are 

between 55° and 59°, 22 percent are between 65° and 

69°, 12 percent are 70°-T9°, and 3 percent are 

80°-100°.) Distribution relative to length of shell is 

shown in figure 12. Median intercostal groove present 

on brachial valve with few exceptions. Costae on anterior two-thirds of valves; in some specimens limited 

to anterior half. Costae number four to 13; number related in part to size (length) of shells as shown in fig13 and in part to angle between flattened sides. Eightytwo percent of the specimens fall in range of length 

1.0-5.4 mm. Sixty-three percent have seven to nine costae. Along front edge of shell costae may be spaced 

approximately one per millimeter.

Holotype. TJSNM. 167191 (pi. 18, figs. 16-20).

Paratypes. US'NM 167192a-m.

Occurrence. USGS collection D1968 CO. From 

crevice or channel filling on west side of bioherm, 168 

feet above base of bioherm.

Discussion. Idiostrophia valdari as described here

ANGLE BETWEEN SIDES

FIGURE 12. Diagram showing length of shell of Idiostrophia 

valdari Ross, n. sp. versus apical angle, contoured according to number of specimens.

may include more than one species. However, much 

more than the considerable amount of time already devoted to a possible subdivision would be required to 

discover consistent criteria on which to base separate 

species or subspecies.

/. valdaii differs from Idiostrophia perfecta Ulrich 

and Cooper in having fewer and somewhat coarser costae. /. costata Ulrich and Cooper is twice as long as the 

largest specimen of /. valdari and possesses much coarser costae. /. conciliata n. sp. has more numerous costae 

and is of larger size. /. nuda Cooper is almost twice 

the size of /. raldari and has a more convex brachial 

valve and more numerous costae which are limited to 

the anterior third of the shell. /. valdari is easily 

discernible from /. paucicostata and /. plicata which 

have fewer and less prominent costae.

3.0

4 5 6 7 8 9 10 11 12 13 

NUMBER OF COSTAE

FIGURE 13. Diagram showing length of shell of Idiostrophia 

valdari Ross, n. sp. versus number of costae, contoured according to number of specimens.
26 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Idiostrophia conciliata Eoss, n. sp. 

Plate 9, figures 1-7

Shell of medium to large size for genus, triangular 

in outline, width very slightly greater than length. 

Apical angle about 65°. Anterior margin broadly 

curved. Valves unequally biconvex, the pedicle valve 

slightly the deeper. Anterior commissure virtually 

straight. Posterior halves of valves smooth. Anterior 

part marked by 24 costae.

Pedicle valve more strongly convex in lateral than in 

anterior profile. Flanks between lateral ridge and commissure very narrow. Brachial valve about equally convex in lateral and anterior profiles. Flanks higher than 

those of pedicle valve.

Measurements of figured specimens are as follows.

USNM Type

Length Width ThickValve (mm) (mm) ness 

(mm)

167193______ Holotype.

167193a____. ParatypeBoth_____ 9.9 10.6 Brachial - 13. 9 16. 9

6. 4

7. 4

Occurrence. USGS collection D1991 CO, 10 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejolm Peak.

Discussion. This species more closely resembles 

Idiostrophia. perfects Ulrich and Cooper from the 

Mystic Conglomerate than any other known species. 

It differs from any other species in having more costae 

and in lacking the distinct median groove on both 

valves. Decortication and lack of interiors prevent a 

more complete description.

Genus INGEIA Opik, 1930

Ingria Opik. Ulrich and Cooper, 1038, Geol. Soc. America Spec.

Paper 13, p. 185. 

Ingria, Opik. Cooper, 1956, Smithsonian Misc. Colln., v. 127, p.

700, pi. 163B.

Ingria is abundantly represented in beds of muddy 

and silty limestone that flank the bioherms at Meiklejohn Peak east of the Nevada Test Site. Great numbers of silicified shells have been obtained from south 

of Frenchman Flat (USGS colln. D719 CO) where 

two varieties of /. cloiidl Ulrich and Cooper may have 

stratigraphic significance.

Within the bioherm at Meiklejohn Peak there occur large numbers of shells of smaller size that might 

be assigned tentatively to Paucicostella. Those under 

10 mm in length are concavo-convex, but larger specimens tend toward resupination, a characteristic of 

Ingria. It, therefore, is probable that Ingria is represented in the reef by immature or dwarfed individuals.

In his description of Paucicostella canadensis, 

Cooper (1956, p. 712) noted that it was also a resupinate shell with widely spaced major costellae, essentially like those of Ingria. Cooper (1956, p. 711) 

found no specimens that permitted satisfactory preparation of the brachial interior. I suggest the possibility that Paucicostella of Quebec and Newfoundland 

may be congeneric with Ingria of Nevada.

Ingria cloudi Ulrich and Cooper 

Plate 9, figures 8-19; plate 10, figures 1-4, 8, 9

Ingria cloudi Ulrich and Cooper, 1938, Geol. Soc. America 

Spec. Paper 13, p. 185-186, pi. 38B, figs. 4-8; pi. 570, 

figs. 17, 18, 20, 21, 23. 24.

Ingria cloudi Ulrich and Cooper. Cooper, 1956, Smithsonian 

Misc. Colln., v. 127, pi. 163B.

Several topotypic silicified specimens from the Nevada Test Site are illustrated for comparison with 

calcareous shells in the bioherm at Meiklejohn Peak. 

The calcareous shells (pi. 10, figs, 5-7, 10-13, 17) are 

much smaller than silicified adults and may be referable to Paucicostella.

The variability of Ingria cloudi has been noted by 

Cooper (1956, p. 700). There seem to be two main 

varieties in the collections from south of Frenchman 

Flat. One of these is quadrate (pi. 9, figs. 8-15) in outline and the other alate (pi. 9, figs. 16-19; pi. 10, figs. 

1-4, 8-9). It is doubtful if these two should be given 

rank of subspecies unless future statistical study shows 

significant differences, both morphologically and 

stratigraphically.

Figured specimens. USNM 167194a-d, 167195a-c, 

167l96a-b.

Occurrence. Antelope Valley Limestone, Eanger 

Mountains Member, along side of broad wash at exit 

from range, Ranger Mountains. Nevada coordinates, 

central zone: E. 726,700 feet, N. 740,700 feet, Frenchman Lake quadrangle, Nevada. USGS collection D719e 

CO, 100 feet below top of member. USGS collection 

D719h CO, 70 feet below top of member. USGS collection D719i CO, 60 feet below top of member (Ross, 

1964, p. C20; Byers and others, 1961) Nevada Test 

Site.

Antelope Valley Limestone, lower member, Nevada 

coordinates, central zone: E. 500,100 feet, N. 775,600 

feet, Bare Mountain quadrangle, Nevada. USGS collection D1975 CO, 420 feet above base of member. 

D1993 CO, 415 feet above base of formation in rubbly 

beds above bioherm. D1968 CO, in bioherm, 168 feet 

above its base. D1973 CO, in bioherm 60-65 feet above 

its base. D1990 CO, in biohorm 45 feet above its base, 

Meiklejohn Peak.

Discussion. Small specimens from the bioherm at 

Meiklejohn Peak resemble Paucicostella canadensis 

Cooper (1956, p. 712, pi. 172A, 173D). However, these
DESCRIPTIONS OF FOSSILS 27

specimens are virtually identical to immature stages 

of Ingria doudi which occurs silicified in muddy, silty 

strata flanking the bioherm. No satisfactory brachial 

interiors of the small calcareous specimens in the bioherm have been obtained.

Genus ISOPHRAGHMA Cooper, 1956

Isophragma? sp. 

Plate 10, figures 18, 20

A single incomplete silicified pedicle valve has been 

obtained from beds overlapping the great bioherm 

and this valve seems to be an immature specimen of 

Isophragma or Taphrodonta. The valve is only a little 

more than -i mm long; inasmuch as resupination of 

most species of Isophragma takes place beyond a 

radius of -i mm, that characteristic cannot be used 

to determine whether the little shell belongs to Isophragma or to Taphrodonta.

Dental lamellae poorly developed. Deltidium present. Callosities subperiphcral, forming sharp ridges 

steepest on distal side; ridge interrupted medially by 

double-pronged depression. This depression seemingly 

accommodated double septum of brachial valve.

Costellae subequal except for three that are more 

prominent, one median and a pair enclosing an angle 

of 50°. These three costellae appear in reverse as 

grooves on inside of valve. 

Figured specimen. USNM 167199. 

Occurrence. USGS collection D19T5 CO, near top 

of lower member, in beds overlying bioherm, 420 feet 

above base of formation, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. Only after additional collections are 

made can the correct relationships of this shell be 

determined. Whether Isophragma or Taphrodonta is 

represented, the occurrence of either is unexpected 

in the Orthidiella zone. The latter would provide one 

more tie between the Rhysostrophia zone of the 

Toquima Range and the Orthidiella zone.

Genus PETRORIA Wilson, 1926

Petroria Wilson, 1926, Canada Dept. Mines, Geol. Survey Bull.

44, Contr. Canadian Paleontology, p. 27-28. 

Petroria Wilson. Cooper, 1956, Smithsonian Misc. Colln., v.

127, p. 746-747.

The peculiar concentrically rugose surface described 

in Petroria rugosa Wilson (Wilson, 1926, p. 28) is 

shown in a far less pronounced fashion by shells from 

Meiklejohn Peak. The shell substance of the Nevada 

specimens seems to be fibrous and in shingled layers. 

Irregular silicification probably can produce the effect 

described in P. rugosa. I have not been able to observe 

any pseudopunctae. No interiors are available for the

Nevada species; therefore, generic assignment cannot 

be final.

It is now known that the original stratigraphic 

position assigned to this genus by Wilson (1926, p. 

29) was incorrect, Cooper (1956, p. 746) called attention to the probable mixing of collections from several 

horizons and to the association of Orthis marshalli 

Wilson and Plectorthis* sinuatis Wilson. He thought 

that O. marshalli should be assigned to Orthambonites 

and that Plectorthis* sinuatis looked very much like 

an Orthidiella. Aitken and Norford (1967, p. 188, 203) 

have shown that Petroria rugosa Wilson is indeed associated with Orthambonites marshalli (Wilson) in 

the Skoki and Out ram Formations; and, although 

they have not reassigned associated P.? smuatis to 

Orthidiella, such a reassignment is probably advisable.

At Meiklejohn Peak, Petroria seems to be present 

in the large bioherm. There it is included in the Orthidiella zone. Ortha-mbonites marshalli (Wilson), 

although not found in the bioherm, has been found 

to be a useful index to the Orthidiella zone in much of 

neighboring Nevada and California, as well as in 

Alberta and British Columbia.

Petroria? austrina Ross, n. sp. 

Plate 11, figures 1-5

Shell semielliptical in outline. Concavo-convex in 

lateral and anterior profiles. Hinge forming widest 

part of shell; cardinal angles acute in well-preserved 

shells, somewhat rounded in old or abraded specimens. 

Anterior commissure flexed centrally slightly near 

midline. Surface marked by very fine distant costellae; 

spacing averages about one per millimeter with much 

wider smooth interspaces.

Pedicle valve strongly convex in lateral profile with 

greatest convexity between midpoint and umbo. Umbo 

somewhat swollen. Posterolateral flanks convex in 

lateral view but somewhat concave in anterior profile. 

Anterior profile moderately convex; greatest convexity 

along midline. Cardinal area anacline, concave, wide 

and long (transversely). Deltidium arched.

Brachial valve markedly concave, particularly 

along midline posterior to midpoint, Posterolateral 

"ears" concave. Cardinal area hypercline, wide near 

notothyrinm. Chilidial plates large, completely filling 

gap in delthyrium above arched deltidium.

Measurements of figured specimens are as follows.

USNM Type

Length

Valve (mm)

Hinge

width

(mm)

Thickness

(mm)

Measured 

167200--.- Holotype--. Complete. .- 

167200a-.. Paratype.-.- Pedicle ...

13.3 4.5 On midline.

5.3 Transversely.

13.7+ 4.6 On midline.

5.7 Transversely.
28 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Occurrence. USGS collection D1973 CO, 60-65 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak.

Discussion. Despite our inability to demonstrate 

internal features of this species, the species is assigned 

with fair confidence to Petroria rather than to L,eptella. Although not possessing the strongly rugose 

surface of P. rugosct Wilson, it does have a similar 

"shingled' 1 layering of the shell. Externally, both P. 

rugosa and P.I anstrina resemble Leptefla very closely. 

Cooper (1956, p. 188-189) states that Leptella nevodensis has a pseudopunctate shell; no pseudopunctae 

are known in Petroria although that lack may be the 

result of preservation.

Petroria^: austrina is a larger and wider shell than 

P. rugosa; the pedicle valve is probably a little more 

convex.

Genus PAUCICOSTELLA Cooper, 1956

PaucicosteUa Cooper, 1956, Smithsonian Misc. Colln., v. 127,

p. 711-712.

According to the original description, no adequate 

brachial interiors of this monotypic genus have ever 

been obtained. In Nevada the bioherm at Meiklejohn 

Peak has yielded small shells (pi. 10, figs. 5-7, 10-13, 

17) that externally resemble PaucicosteUa canadensi-s. 

No brachial interiors can be developed on these specimens which also are identical to immature specimens 

of Ingria cloudi. Paucicostella is known from the 

Mystic Conglomerate of Quebec and the Table Head 

Formation of Newfoundland in strata correlative to 

the bioherm at Meiklejohn Peak. The possibility exists 

that Paucicostella. of eastern North America is synonymous with Ingria of Nevada. The shells in question 

are figured as Ing rial sp.

Genus CTJPARIUS Ross, 1971

Cuparius Ross, 1971, Smithsonian Contr. Paleobiology no. 3 

p. 125.

The ParamT)onites-\\k& syntrophopsid genus Cuparis is represented in the bioherm at Meiklejohn Peak 

by the type species, Cuparius cardilatus Eoss. The 

genus seems to be limited stratigraphically to the 

equivalents of the Ortliicliella zone and possibly to the 

lowermost AnomalortMs zone.

Cuparius cardilatus Ross 

Plate 11, figures 6-9

Cuparius cardilatus Ross, 1971, Smithsonian Contribut. Paleobiology No. 3, p. 125-128, pi. 1, figs. 1-8.

Figured, specimen. USNM 167201.

Occurrence. USGS collection D1973 CO, 60-65 

feet above base of bioherm, Antelope Valley Limestone, Meiklejohn Peak, Nev.

Discussion. A few specimens most of them fragmentary have been obtained now in the bioherm 

at Meiklejohn Peak. One of these (pi. 11, figs. 6-9) 

shares proportions of the types, but is a little larger 

than previously described specimens. It has also a 

slightly less convex pedicle valve. As would be expected in a large individual, the fold and sulcus originate behind the midpoint of each valve. Other features 

are the same as in the original types.

Cuparius sp. 

Plate 11, figure 17

A small pedicle valve was found in the bioherm at 

Meiklejohn Peak within the range of Cuparius cardilatus. It possesses a less transverse outline than that 

species but is a smaller, possibly an immature, shell. 

The pitting of the surface of the shell is not discernible in the inner layers.

Figured specimen. USNM 167202.

Occurrence. USGS collection D1966 CO, 50 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Phylum ARTHROPODA 

Class TRHOBITA

Genus TRINODUS McCoy, 1846

Trinodus McCoy. Ross, 1967, U.S. Geol. Survey Prof. Paper 

523-D, p. D8.

Trinodus sp. 1 

Plate 11, figures 15, 16

Trmodus'i sp. Ross, 1958, Jour. Paleontology, v. 32, no. 3, p.

564, pi. 83, figs. 5, 8. 

Trinodus sp. 1. Ross, 1967, U.S. Geol. Survey Prof. Paper 523-D,

p. D9, pi. 3, figs. 19, 20.

This species is rare. It is characterized by the muchexpanded third, or terminal, lobe of the pygidial axis.

Cephalic length and width about equal. Convex 

border bounded proximally by deep furrow. Strongly 

convex cheeks surmounted by glabella. Glabella lacks 

anterior transverse furrow and median pustule. Length 

of glabella two-thirds that of cephalon; its width onehalf that of cephalon and two-thirds its own length. 

Width of glabella across basal nodes almost six-tenths 

the cephalic width.

Pygidium as wide as or somewhat wider than long. 

Border bearing posterolateral spines. Median node, 

partly accidently removed during preparation on 

the illustrated specimen (pi. 11, fig. 16), lies along crest 

of second axial ring. Axis narrowest between second 

ring and terminal piece; axis widest at first segment, 

which is composed of two anterolateral nodes. Termi-
DESCRIPTIONS OF FOSSILS 29

nal piece almost circular in outline. Length of axis, 

including articulating half ring, between two-thirds 

and three-fourths the pygidial length. Width of axis 

at anterior nodes about half pygidial width; width of 

terminal piece about four-tenths pygidial width.

Figured specimens. USNM 167203a, b.

Occurrence. USGS collection D1973 CO, 60-65 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. This species, if it is a true species, seems 

to be represented by small specimens; therefore it may 

prove to be the immature stage of some other species. 

However, its stratigraphic position seems to be consistently low in the Antelope Valley Limestone in the 

Orthidiella zone.

Trinodus sp. 1 differs from T. clusus (Whittington) 

in possessing a narrower glabella and narrower pygidial axis. T. valmyensis has a shorter glabella and 

pygidial axis.

Genus SHTTMARDIA Billings, 1862

Shumardia sp. 

Plate 11, figure 10

Cephalon semicircular in outline. Glabella broadly 

rounded in front; its maximum width (trans.) at anterolateral lobes equals nine-tenths cranidial length (sagittal) and six-tenths its width (trans.). Posterior part 

of glabella semicylindrical. Combined length (sag.) of 

glabella and occipital ring equals nine-tenths length 

of cranidium. Anterolateral lobes, shaped like "teardrops," extending backward to point seven-tenths glabellar length from front. Occipital furrow straight; 

length of occipital ring equals less than four-tenths 

glabellar length (sag.). Axial furrows deep beside occipital ring and posterior part of glabella, shallowing 

after curving sharply around rears of anterolateral 

lobes; very faint at confluence with equally faint preglabellar furrow.

Figured specimen. USNM 167204.

Occurrence. USGS collection D1994 CO, in beds 

flanking bioherm, 173 feet above base of bioherm and 

211 feet above base of formation, Antelope Valley 

Limestone, Meiklejohn Peak, Nev.

Discussion. This species lacks the preglabellar sagittal furrow and obtusely pointed glabella found in 

Shumardia gmnulosa, Billings and in 8. exopthalma 

Ross. There seem to be no small basal glabellar lobes; 

the posterior part of the glabella not flanked by anterolateral lobes is short, for the genus. No pygidium has 

been identified to date and formal designation of the 

species is considered unwise.

Genus CARRICKIA Tripp, 1965 

Gonioplinjs Ross. Whittington, 1965, Harvard Univ. Mus. Comp.

Zoology Bull., v. 132, no. 4, p. 371. 

Curricula Tripp, 1965, Palaeontology, v. 8, pt. 4, p. 579-580.

Shaw, 1968, New York State Mus. and Sci. Service Mem.

17, p. 31.

This komaspid genus is far more widespread in Middle Orclovician deposits than was originally supposed. 

Although not common, it is here reported for the first 

time in southern Nevada in the beds flanking bioherms 

at Meiklejohn Peak. Whittington (1965, p. 371-372) 

has reported two species from the Table Head Formation in Newfoundland. Tripp has described species of 

Carrichia from the Albany Mudstone and from the 

Stinchar Limestone of the Girvan district in southern 

Scotland.

Carrickia sp. 1 

Plate 10, figure 19

This species closely resembles CarricMa breviceps 

(Billings) (Whittington, 1965, pi. 38, figs. 12, 15, 16; 

pi. 39, figs. 1, 2) in outline and convexity of the glabella 

and in the outline of the palpebral rims. The fixed 

cheeks are markedly wider than in C. breviceps or 

Gonioplirys prima. The outline of the glabella in 

Gonioplirys prima tapers more noticeably.

Only a single cranidium of this species has been collected from the flanking beds near the bioherm.

Figured specimen. USNM 167205.

Occurrence. USGS collection D1994 CO, lower 

member of Antelope Valley Limestone, 241 feet above 

base of formation, and 173 feet above base of bioherm, 

in flanking beds, Meiklejohn Peak, Nev.

Genus CAROLINITES Kobayashi, 1940

Dimastocephalus Stubblefielcl, 1950, Annals and Mag. Nat. History, ser. 12, v. 3, p. 344-345.

Carolinites Kobayashi. Stubblefielcl, 1950, Annals and Mag. Nat. 

History, ser. 12, v. 3, p. 451-452.

In his discussion of ill-fated Diniastocephalus, 

synonym Carolinites, Stubblefield (1950a, p. 341-344:) 

noted the great geographic spread of the genus from 

Tasmania through Utah to northern Ireland. Since 

then Carolinites has been reported in the Leningrad 

district by Balashova (1961, p. 130-131), in northeastern USSR by Chugaeva, Rozman, and Ivanova 

(1964, p. 11-13), in Newfoundland by Whittington 

(1965, p. 373), in Spitsbergen by Vallance and Fortey 

(1968), and in Argentina by Harrington and Leanza 

(1957, p. 141-142). W. T. Dean (written commun., 

May 8,1970) stated that Carolinites occurs in Arenigian 

strata in Turkey.

Stubblefield's (1950a, p. 341-344) discussion of the 

stratigraphic occurrence of Carolinites Tdllaryensis
30 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

revealed that the species was associated in Ireland 

with Ectenonotus, N ileus* IIIaemix, and other genera 

typical of the Table Head-Lower Head assemblages of 

Newfoundland and of the Ortlndiella zone in Nevada. 

Furthermore, the occurrence in Ireland was in peculiar lenses of brecciated limestone within a sequence 

of conglomerates and graptolitic shales. These limestone lenses may be related in origin to somewhat 

similar limestone bodies north of Elko, Nev., as well 

as to biohermal masses like that at Meiklejohn Peak. 

Carolinites ranges from the Pseudocybele zone into 

the Orthidiella zone in the Utah-Nevada area. Hintze 

(1952, p. 145) has reported C. killaryensis utahensis 

in the lowest Anomalorthis zone of western Utah. I 

have never found the genus in beds I considered 

younger than those of the OrtMdiella zone in Nevada, 

and I have found C. killaryensis in the area west of 

the Nevada Test Site, Nev., in the Orthidiella zone or 

highest Pseudocylele zone (USGS Colln. D1458 Co.) 

(Koss, 1967, p. Dll).

Known species include:

Carolinites 6«76osws Kobayashi

Garolinites killaryensis (Stubblefleld)

Carolinites genacinaca Ross

Garolinites killaryensis var. utahensis Hintze

Garolinites sibiricus Chugaeva

Garolinites angustagena Ross

Garolinites indentus Ross

Carolinites sp. indet. 1 (Whittington, 1965, p. 373,

pi. 39, figs. 3, 4, 11) 

Carolinites sp. indet. 2 (Whittington, 1965, p. 373-

374, pi. 39, figs. 7, 12, 13) 

Carolinites popovkiensis Balashova, 1961 

Carolinites macropthalma (Harrington and Leanza)

C. macropthalma (Harrington and Leanza, 1957, p. 

141-142) is believed to be of Caradoc age. Although 

Balashova (1961, p. 130) considered Carolinites 

popovkiensis to be Tremadocian, such an early age is 

highly unlikely (Valdar Jaanusson, written commun., 

May 25, 1970).

Carolinites cf. C. killaryensis (Stubblefleld) 

Plate 11, figs. 11,14; plate 12, figures 1-6

One of the most abundant species in the Meiklejohn 

bioherm is well represented by cranidia and free 

cheeks; only one pygidium is available.

Surface smooth, not pustulose.

Cranidium approximately twice as wide at posterior 

margin as sagittal length. Glabella widest (trans.) 

immediately in front of preoccipital nodes and 

slightly behind midpoint of glabella excluding occipital ring. Width of glabella almost 1.5 times its 

length (sag.), exclusive of occipital ring. Length

(sag.) of occipital ring about one-fourth length of 

glabella in front of occipital furow. Axial furrows 

barely impressed except where they separate preoccipital nodes from glabella. Preoccipital nodes positioned between occipital furrow and a point one-fourth 

glabellar length from occipital furrow. Eyes very 

large and bulbous. Genal spines flattened, of moderate 

length.

Pygidium semicircular in outline, strongly convex, 

dominated by robust axis of four distinct rings, terminal piece, and articulating half ring. Each ring and 

terminal piece impressed transversely by interpleural 

furrow. Terminal piece must have borne stout fairly 

upright spine, as indicated by round stump on solitary 

specimen. Terminal piece composed of fused axial ring 

and quarter sphere; posterior face very steep and 

flattened. Axis consumes one-half total anterior width 

(trans.) of pygidium. Pleurae prominent, bent steeply 

down distally to concave border. Front half of each 

pleura raised and bearing sharp node at flexure above 

border.

Figured specimens. USNM 167206a-e.

Occurrence. USGS collection D1966 CO, 50 feet 

above base of bioherm, D1973 CO, 60-65 feet above 

base of bioherm, Antelope Valley Limestone, Meiklejohn Peak, Nev.

Discussion. The species represented in the Meiklejohn bioherm most closely resembles Carolinites killaryensis (Stubblefield). Like that species it possesses 

wide fixed cheeks on the cranidiuni, wider than those 

of C. killaryensis utahensis Hintze. Like both Hintze's 

variety and Stubblefield's Irish species it has a stout 

spine on the terminal piece of the pygidium, but exact 

dimensions of this spine are unknown.

From Carolinites genacinaca, Ross, C. angustagena 

Ross, C. indentus Ross, C. sibincus Chugaeva, and C. 

l>ulbosus Kobayashi, the Meiklejohn form differs in 

its greater width of fixed cheeks. Only the two indeterminate Newfoundland species illustrated by Whittington (1965, pi. 39, figs. 3, 4, 11 and 7, 12, 13) rival 

the Nevada and Irish specimens in this regard; both 

the Table Head species have pustulose surfaces. The 

pygidium of neither is known with certainty.

Genus GLAPHTJRTJS Raymond, 1905

Glaphurus Raymond, 1905, Carnegie Mus. Annals, v. 3, p. 357-

359. 

Glaphurus Raymond. Ulrich, 1929, U.S. Natl. Mus. Proc., V.

76, art. 21, p. 42-46.

Glaphurus Raymond. Shaw, 1968, New York State Mus. and 

Sci. Service Mem. 17, p. 26.
DESCRIPTIONS OF FOSSILS 31

Glaphurus sp. 

Plate 12, figures 7-9

The genus Glaphurus is represented in the present 

collection by a single incomplete cranidium, which 

lacks anterior border and most of both fixed cheeks.

Surface of cranidium pustulose. Glabella broadly 

oval in outline, its width equaling more than ninetenths of its length exclusive of occipital ring. Widest 

part opposite glabellar micllength exclusive of occipital ring. Its height five-tenths of the glabellar 

width. Occipital ring strongly convex in lateral profile ; its sagittal length equals one-fourth of its length 

(sag.) of glabella exclusive of ring. Occipital furrow 

virtually straight in plan view, evenly deep. Glabellar 

furrows \p parallel axial furrows; front ends of this 

pair of furrows located opposite glabellar midpoint; 

back ends of furrows approach but do not reach occipital furrow. Median lobe of glabella between lateral 

furrows Ip constitutes two-thirds of glabella width. 

Lateral furroAvs 2p reduced to a pair of pits, each 

connected by shallow sill-like furrow to axial furrow. 

Furrows 2/> located opposite point almost four-tenths 

of glabellar length (sag.) from front. Only one pair 

of spine bases readily distinguished on glabella almost 

halfway from occipital furrow to glabellar midpoint. 

Axial furrows deep, confluent around front of glabella. Preglabellar field not completely preserved; 

seemingly gently sloping and probably short (sag.) 

for the genus.

Figured specimen. USNM 167207.

Occurrence. USGS collection D1968 CO, 168 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. Many of the interspecific distinguishing features are not preserved on this single cranidium, so that species' identity cannot be established until further collections are made. However, the outline 

of the glabella is more like that of Glaphurus 

pustulatus (Walcott) than like G. divisus Whittington. The anterior pair of glabellar furrows in G. 

divisus are openly connected to the axial furrows but 

they are reduced to pits in both this specimen and in 

G. pustulatus.

Stratigraphically, the occurrence of Glaphurus in 

the bioherm at Meiklejohn Peak is important in fortifying a link with the similar faunas at Lower Head, 

Newfoundland (Whittington, 1963), and in calling 

attention to a similar species in the Chazy Limestone 

of New York (Shaw, 1968, p. 26-28). Dr. Valdar 

Jaanusson (written commim., May 25, 1970) has noted 

that the oldest species "of Glaphurus hitherto described is G. coronatus Maximova from the Uskut

Stage (generally correlated with the Tremadocian) of 

the Siberian Platform" (Maximova, 1962).

Genus NILEUS Dalman, 1827

Nileus aff. N. scrutator Billings

Plate 12, figures 10-16

Nileus sp. Ross, 1967, U.S. Geol. Survey Prof. Paper 523-D,

p. D14, pi. 4, figs. 14, 15.

Cranidium of this species closely resembles that of 

N. scrutator Billings (Whittington, 1965, pi. 32, figs. 

1, 3) in course of facial sutures, position of median 

pustule, and convexity. Palpebral lobes separated from 

glabella by shallow, almost straight furrows. Width 

(trans.) of glabella between palpebral lobes eighttenths of cranidial length (sag.). Length (exsag.) of 

palpebral lobes one-third of cranidial length (sag.).

Pygidial length, six-tenths its width. Axis can be 

distinguished only, under optimum lighting, as low 

triangular rise; undefined by furrows or distinct break 

in slope. Border defined by very shallow furroAv; 

furrow deeper laterally than medially.

Figured specimens. USNM 167208a-e.

Occurrence. USGS collection D1971 CO, in flanking beds 207 feet above base of bioherm, D1973 CO, 

from bioherm 60-65 feet above its base, Antelope 

Valley Limestone, Meiklejohn Peak, Nev.

Discussion. This species differs from Nileus 

scrutator Billings in the lesser exsagittal length of its 

palpebral lobes; in Billings' species their length is 

between four-tenths and five-tenths that of the cranidium. Convexity of palpebral lobes and position of the 

eyes relative to the midlength (sag.) of the cranidium 

is the same. Width (trans.) of the glabella between the 

palpebral lobes relative to cranidial length is almost 

the same. The pygidimn of the Nevada species is somewhat narrower.

Genus PERASPIS Whittington, 1965

Peraspis? sp. 

Plate 12, figure 17, 18

Pygidium almost semicircular, of low convexity. 

Axis tapering to narrowly rounded terminal piece; 

axial segmentation very faint, seemingly seven rings 

plus terminal piece. Anterior \vidth (trans.) of axis 

equals one-third pygidial width and almost threequarters length (sag.) of axis. Pleural region evenly 

convex, bounded by shallow border furrow and convex 

border. Five pairs of interpleural furrows barely discernible. Width (exsag.) of border about one-sixteenth 

length (sag.) of pygidium.

Figured specimen. USNM 167209.
32 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Occurrence. USGS collection D1991 CO, Meiklejohn Peak, Nev.

Discussion. This pygidium closelv simulates that 

of Peraspis lineolata (Raymond) (Whittington, 1965, 

pi. 34, figs. 1, 6, 7, 10) and that of P. erugata Ross 

(1970, pi. 14, figs. 21, 22) in general outline and proportion. The border is markedly wider (exsag.) than 

in P. lineolata and is slightly wider than in P. erugata. 

Segmentation is fainter than in P. lineolata but about 

the same as in undecorticated specimens of P. erugata.

Genus ILLAENTTS Dalman, 1827 

Illaenus cf. I. aitriculatus Ross

Plate 12, figures 19-26; plate 13, figures 1-13; plate 14, figures

23-25

In dorsal view, cephalon broadly crescentic in outline ; its sagittal length a little less than half its width 

(trans.). Sagittal profile of cephalon an even curve, 

in effect the arc between radii bounding 160° angle. 

Smooth margin without raised border. Transverse profile between eye centers of low convexity, but steeply 

sloping (approximately 65°) below eyes. Glabella defined by shallow axial furrows of openly S-shaped 

outline; posterior part broadly convex outward with 

greatest width between greatest width of palpebral 

lobes; anterior part of furrows convex inward between 

front ends of palpebral lobes. Axial furrows terminate 

immediately in front of palpebral lobes. Defined length 

(exsag.) of glabella about seven-tenths its greatest 

width (trans.). One line through eye centers, width of 

each fixed cheek equals six-tenths width of glabella.

Facial sutures run backward with only slight divergence from palpebral lobes to cut posterior margin; 

cranidium wider at palpebral lobes than at posterior 

margin. In front of eyes, sutures run forward with 

very slight initial divergence, then curve more tightly 

inward before reaching transverse rostral suture. 

Features of rostrum and anterior doublure not known. 

Free cheeks steep sided with prominent posterolaterally 

directed lappets.

Thorax not known.

Pygidium transversely semielliptical in outline with 

pronounced anterolateral facets. Length (sag.) about 

four-tenths greatest width. Axis low, broadly triangular, defined by shallow axial furrows. Anterior width 

(trans.) of axis about one-third that of pygidium. 

Length (sag.) of axis about one-half that of pygidium. 

Doublure as in /. auriculatus.

Figured specim-ens. USNM 167210a-i.

Occurrence. USGS collection D1973 CO, 60-65 

feet above base of bioherm; and D2058 CO, 130 feet 

above base of bioherm, Meiklejohn Peak, Nev.

Discussion. The cephalon and cranidia of this 

species resembles those of Illaenus consol>rinus Whittington and Illaenus l>ucculentus Whittington. The 

lappets on the free cheeks of both those species are 

slenderer and extend backward farther to give the 

cephalon a more narrowly crescentic outline than that 

of this Nevada form.

The sigmoid curvature of the axial furrows on the 

cranidium is more pronounced in I. consobrmus but 

very similar in 7. l>ucculentm. I. fraternus Billings 

has somewhat similar axial furrows but a different 

lateral profile of the cranidium. 7. marginalis Raymond 

and 7. alreatus Raymond possess thickened borders on 

the anterior of the cranidium, as does 7. consimilis 

Billings.

An associated hypostome (pi. 13, fig. 4) is damaged, 

but otherwise can hardly be distinguished from that of 

7. consobrmus (Whittington, 1963, pi. 18, fig. 4) ; it 

possesses a shorter (sag.) posterior lobe than a smaller 

specimen assigned to Illanenus auriculatus (Ross) 

(Ross, 1967, pi. 5, fig. 15), a difference possibly attributable to stage of growth.

Although two kinds of pygidia are associated (pi. 

14, figs. 13-15 and pi. 13, figs. 5-8), the more transverse specimens which have pronounced anterolateral 

facets probably should be assigned to this species. 

These pygidia are almost identical to those of Illaenus 

auriculatus Ross in dorsal features and in shape of 

doublure (pi. 13, figs. 5-8). The pygidium of 7. consobrmus is relatively longer (sag.) than these and has 

less conspicuous facets.

The correlative sample on which the description of 

the species Illanenus auriculatus Ross (Ross, 1967, p. 

D16, pi. 5, figs. 1-32, 36, 40)) was based may be composed of immature individuals of the species described 

here.

Illaenus sp. to 

Plate 13, figures 14-19; plate 14, figures 1-6

Illaenus sp. ind. 2 of Whittington, 1963, Harvard Coll. Mus. 

Comp. Zoology Bull., v. 129, no. 1, p. 73-74, pi. 19, figs. 5, 

6, 8, 9.

Three cranidia, all damaged, bear a very close resemblance to an indeterminate species described by 

Whittington (1963, p. 73-74, pi. 19, figs. 5, 6, 8, 9) as 

Illaenus sp. ind. 2 from Newfoundland. The Nevada 

and Newfoundland specimens share similar axial furrows, similarly narrow steeply sloping preglabellar 

fields, raised bordering rims, and similar lateral profiles. Whittington's specimen bears a median glabellar 

node and palpebral rims; evidence is lacking for palpebral rims on the present cranidia; a faint median
DESCRIPTIONS OF FOSSILS 33

node is present on the smallest cranidium (pi. 13, figs. 

14-16).

Free cheek assigned to this species bears small eye, 

steep evenly rounded slopes, and a distinct border; 

border beveled to slope posteroventrally. Genal angles 

broadly rounded.

Figured specimens. USNM 167211a-d.

Occurrence. USGS collection D1968 CO, Meiklejohn Peak, Nev.

Discussion. Free cheeks of this species seem to lack 

the thin, sharp edged lappet found in Ulaenus cf. /. 

awiculatus Ross or the blunt genal protrusion of 

Ulaenus sp. f. In these regards it is probably similar to 

Ulaenus sp. ind. 2 of Whittington (1963, pi. 19, figs. 5, 

6, 8, 9).

Ilaenus sp. c 

Plate 14, figures 7-12

Two fairly large decorticated cranidia bear resemblances to those of Illaenus consobrinis Whittington 

and Illaenus sp. a, described above. They differ from 

both species in a more forward position of palpebral 

lobes, smaller palpebral lobes, more divergent posterior 

course of facial suture, and convexity of lateral profile. 

The profile (sag.) is virtually the arc of an 108° sector 

of a circle with radius approximating 15 mm.

Figured specimens. USNM 167212a, b.

Occurre?ice. [JSGS collection D1991 CO, Meiklejohn Peak, Nev.

Discussion. No coeval species from Newfoundland 

of Nevada possesses a less convex lateral cranidial profile. There is some indication that convexity decreases 

with increase in size in several species of Illaenus, but 

this is clearly not true of all species. No identifiable 

pygidia were found associated with the cranidia of 

Illaenus sp. c.

Two specimens, one very large and one very small, 

of Illaenus consimilis (Whittington, 1965, pi. 51, figs. 

1, 2, 5; pi. 50, figs. 2, 7, 9) have a similar low convexity 

of profile. In convexity they differ from other specimens of /. consimilis illustrated by Whittington (1965, 

pis. 50 and 51). /. consimilis possesses an anterior 

marginal rim on the cranidium and converging anterior 

facial sutures. The two cranidia of Illaenus sp. c differ 

in these two respects.

Illaenus sp. d 

Plate 14, figures 13-15

Pygidimn almost twice as wide as long, parabolic 

in outline. In profile, convexity of upper surfaces low, 

steepening strongly past vertical toward periphery. 

Margin lacking furrow or rim. Triangular outline of

axis delineated by faint axial furrows. Anterior width 

(trans.) of axis equals its length (sag.).

Figured specimen. USNM 167213.

Occurrence. USGS collection D1973 CO, D1968 

CO, Meiklejohn Peak, Nev.

Discussion. Two pygidia similar to that of Illaenus 

tumidifrons Billings (Whittington, 1963, pi. 15, fig. 

13) have been found in USGS collection D1973 CO 

where they are associated with Illaenus cf. /. auriculatus Ross, described above, for which the pygidial 

association is fairly certain. To date only one kind of 

cranidium has been recognized in this collection. There 

are only two pygidia of Illaenus sp. d as opposed to 

seven assigned to /. cf. /. auriculatus Ross.

Illaenus sp. e 

Plate 14, figure 16

Pygidium markedly transverse in outline, length 

(sag.) about one-third greatest width (trans.). Axis 

sharply triangular in outline, its anterior width 

(trans.) equaling its length (sag.). Convexity of axis 

very low. Convexity of pygidium increasing peripherally.

Figured specimen. USNM 167214.

Occurrence. USGS collection D1968 CO, Meiklejohn Peak, Nev.

Discussion. This pygidium resembles the pygidia 

of Illaenus alveatus Raymond, but it is presently impossible to assign it to an associated cranidium with 

any assurance. Associated are Harpillaenus sp., 

Illaenus cf. /. auriculatus Ross, and Illaenus sp. b.

Illaenus? sp. f 

Plate 14, figures 17-22

Two free cheeks bear prominent eyes and long stout 

genal spines directed laterally. Close to its base each 

genal spine curves forward. In smaller specimen, spine 

then curves backward slightly.

Figured specimens. USNM 167215a, b.

Occurrence. USGS collection D1968 CO, Meiklejohn Peak, Nev.

Discussion. Because these cheeks have a very short 

radius of curvature in lateral profile they were thought 

to belong to Harpillaenus. However, they seem to 

lack the thin anterior border found in cranidia of 

Harpillaenus, and other associated free cheeks have 

this feature. Also associated are cranidia tentatively 

identified as Illaenus cf. /. auriculatus Ross (pi. 14, 

figs. 23-25). Although not differing significantly from 

those of Illaenus cf. /. awiculatus, such cranidia in 

collection D1968 CO may represent a distinct species 

characterized by the peculiar free cheeks described 

here.
34 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Genus HARPHLAENTTS WMttington, 1963

This trilobite genus is represented by two very 

poorly preserved cranidia from the bioherm at Meiklejohn Peak. No pygidia have been found to ensure correct identification. The great width (trans.) of cranidium as compared with its shortness (sag.) is unequaled in other illaenids?.

Although species identity cannot be ascertained, the 

significance of the discovery is the provision of another paleontologic link between the biohermal deposit of southern Nevada and the "white limestone 

boulder at Lower Head," Newfoundland, from which 

Whittington (1963) described an extensive fauna. To 

date, the genus is known from no other lithologic type.

Harpillaenus sp. 

Plate 15, figures 1-9

Outline of complete cephalon not known. Cranidium 

almost semicircular in lateral profile. Greatest width 

of cranidium at palpebral lobes equals about 2.5 times 

diameter of lateral profile. Width of cranidium at 

posterior margin narrower than width at palpebral 

lobes by width (trans.) of palpebral lobes. Glabella defined by exceedingly faint axial furrows that fade out 

opposite fronts of palpebral lobes. Axial furrows better defined in decorticated specimens than on exterior 

of carapace. Glabella widest at posterior margin, narrows anteriorly. Width (trans.) of glabella at front 

equals eight-tenths of its width at posterior margin. 

Width of glabella between eye centers slightly less 

than four-tenths of greatest width (trans.) of cranidium.

In decorticated specimen shallow, transverse groove 

crosses glabella adjacent to posterior margin; this 

groove not a true occipital furrow. Median tubercle 

positioned between posterior ends of palpebral lobes. 

Facial sutures extend forward in curving converging 

courses to cross anterior margin and intersect rostral 

suture obliquely.

Shallow marginal furrow parallels rostral suture 

and bounds very narrow, faintly raised border. Courses 

of facial suture behind eye straight and diverging 

only slightly before crossing posterior margin.

Free cheeks bear long (exsag.) low eyes. Anterolateral surface curves steeply downward past vertical to 

narrow marginal furrow and narrow border like that 

on cranidium. Although no complete cephala are 

known, free cheeks must have provided bluntly pointed 

genal "horns."

Surface of cranidial carapace and free cheeks 

marked by strong, transverse, widely spaced Bertillon 

lines.

No thoracic or pygidial parts known.

Figured specimens. USNM 167216a-c.

Occurrence. USGS collection D1968 CO, in bioherm 168 feet above its base, lower member, Antelope 

Valley Limestone, Meiklejohn Peak, Nev.

Discussion. According to Whittington (1963, p. 

79), the surface of most of the median part of the 

cephalon of Harpillaenus arcuatus (Billings) is 

smooth. The subparallel transverse pattern marking 

the entire cranidial surface differentiates the Nevada 

species described here. In H. arcuatus the glabella is 

parallel sided and seems to carry a fairly distinct 

occipital ring; the Nevada species has an anteriorly 

narrowing glabella which has only a suggestion of 

occipital ring. The palpebral lobes appear to be closer 

to the posterior margin in the western specimens than 

in H. arcuatus. The outstanding difference is in shape 

of free cheeks which in H. arcuatus form enormous 

"horns." In the present species the "horns" are blunt 

and short.

It should be noted that two very different free cheeks 

(pi. 14, figs. 17-22) were also found associated and 

were thought to belong to this species of Harpillaenus 

because of the remarkable development of genal spines. 

These cheeks seem to lack a raised anterior border and 

therefore probably do not belong with the cranidia 

of Harpillaenus.

Genus BATHYURELLUS Billings, 1865

This genus is represented in the present collections 

by two cranidia and two pygidia. These four specimens 

come from three separate collections and represent 

three different species.

Bathyurellus feitleri (Holliday) was originally decribed on the basis of a pygidium from Meiklejohn 

Peak (Holliday, 1942); so far I have been no more 

successful than Holliday at establishing the correct 

cephalic parts.

Batliyurellus sp. 3 closely resembles a cranidium described as B. pogonipensis by Hintze (1952, p. 138, pi. 

10, fig. 14); unfortunately Hintze chose as his holotype a pygidium (pi. 10, figs, lla, b) which belongs 

to TJromystrum. The remaining specimens (Hintze, 

1952, pi. 10, figs. 1-19) probably all belong to a single 

species of BathyureUus^ and I suggest that future 

collections may show this species to be a synonym of 

B.feitlen (Holliday).

Batliyurellus feitleri (Holliday)

Plate 15, figures 10-12

Niolel feitleri Holliday, 1942, Jour. Paleontology, v. 16, p. 473, 

pi. 74, fig. 7.

This species is represented by a single pygidium in 

the beds flanking the bioherm. No cranidium was found 

associated.
DESCRIPTIONS OF FOSSILS 35

Figured specimen. USNM 167217.

Occurrence. USGS collection D1994 CO, from 

flanking beds 173 feet above base of bioherm, Antelope Valley Limestone, Meiklejohn Peak, Nev.

Discussion. This pygidium and that illustrated by 

Holliday closely resemble the specimen shown by 

Hintze (1952, pi. 10, fig. 17).

Bathyurellus sp. 3 

Plate 15, figures 17-19

A single cranidium closely resembles that illustrated by Hintze (1952, pi. 10, figs. 14a, b). It is 

similar in virtual lack of occipital furrow. It differs 

in having a longer (sag.) preglabellar field and narrower (sag.) anterior border.

Figured specimen. USNM 167218.

Occurrence. USGS collection D1966 CO, 50 feet 

above base of bioherm, Meiklejohn Peak, Nev. USGS 

collection D2058 CO, 130 feet above base of bioherm.

Discussion. This species occurs below Orthidiella at 

Meiklejohn Peak and yet its closest obvious relative 

is the species recorded by Hintze (1964, pi. 10, fig. 

14) from his zone M. Zone M has been correlated with 

the Anomalorthis zone.

Bathynrellus sp. 4 

Plate 15, figures 13-16, 20

One cranidium and one pygidium are the basis for 

this description, hardly a large enough sample on 

which to base a species description. Both specimens 

are damaged.

Much of the cranidial surface bears myriad small 

irregular to subcircular pits between well-developed 

Bertillon markings. Glabella almost semiovoid, sharply 

pointed in front, widest between fronts of eyes, somewhat constricted between rear ends of eyes, and widening immediately in front of occipital furrow. Width 

of glabella two-thirds its length. Preglabellar field 

long (sag.) for the genus, its length one-third that of 

glabella; field slopes at about 55° downward from 

glabellar base; preglabellar field broad, evenly convex, 

bounded anteriorly by shallow marginal furrow and 

border. Width (sag.) of anterior border not known.

Fixed cheeks virtually horizontal between eyes. Palpebral lobes semicircular, of length (exsag.) equaling 

four-tenths length (sag.) of glabella. Eye centers positioned a little behind midpoint of glabella. Fixed 

cheek behind palpebral lobes forming narrow (exsag.) 

descending triangle bounded posteriorly by narrow 

border furrow and narrow convex posterior border. 

Width (trans.) of cranidium at posterior border approximately twice sagittal length of glabella plus 

occipital ring.

Pygidium almost perfectly semicircular, its length 

(sag.) very slightly exceeding half its width. Length 

of axis a little more than seven-tenths sagittal length 

of pygidium; its anterior width slightly less than 

three-tenths pygidial width. Width (trans.) of axis 

equals two-thirds length of axis. Axis composed of 

three rings and bluntly rounded terminal piece. Radius 

of pleural field equals axial length posteriorly but increases toward anterolateral corners of pygidium. 

True marginal furrow lacking; border concave proximally and slightly convex distally. Proximal side of 

border slightly increased by distal ends of pleural and 

interpleural furrows.

Figured specimens. USNM 167219a, b.

Occurrence. USGS collection D1991 CO, 10 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. This species seems to differ from all 

others in the peculiar pitted texture of the outside of 

the cranidial carapace. The preglabellar field is longer 

sagittally than in any other known species. Unfortunately, the exact shape of the anterior border and 

of the occipital ring cannot be told from the available specimen. The pygidium has a longer axis and 

wider pleural field than in Bathyurellus nitidus; conversely the border of B. mtidu-s is much wider as is 

also that of B. teicherti. In fact, the pygidium of 

Bathyurellus sp. 4 approaches pygidia of Bathyurus 

in proportions. The pygidia of B. feitleri and the unnamed species illustrated by Hintze (1952, pi. 10, figs. 

12, 17, 19) are semiellipitical rather than semicircular 

in outline.

Genus RAYMONDITES Sinclair, 1944

Raymondites Sinclair. Whittington, 1953, Jour. Paleontology, 

v. 27, no. 5, p. 654-655.

Raymondites? sp. 

Plate 16, figures 1-6

This species is represented by two pygidia in the 

present collections.

Outline of pygidium nearly semicircular. Axis bearing an enormous spine based on anterior four rings 

of the axis. Length (sag.) of pygidium about sixtenths its width (trans.). Length (sag.) of axis about 

three-fourths length (sag.) of pygidium. Width 

(trans.) of axis equals about eight-tenths its length 

(sag.) and about one-third pygidial width (trans.). 

Axial segmentation indicated by furrows along sides of 

axis adjacent to axial furrows; only terminal piece 

defined by furrow completely across crest of axis. Axial 

furrows shallow but distinct, confluent and weak 

around broadly rounded posterior outline of axis.
36 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Exact shape and height of axial spine not known; 

minimum height of axial spine equals twice height of 

axis itself. Pleural fields of moderate convexity, crossed 

by four distinct pleural furrows which enter border 

but do not attain margin. Pleural furrow very faint, 

only anterior three discernible. Border of pygidium 

concave.

Proximally from border and almost parallel to it 

series of short furrows extends backward from each 

pleural furrow. A very short faint similar furrow also 

present on anterior pleural band of first pygidial segment. Furrow from fourth pleural furrow extends upward toward tip of axis rather than parallel to border. 

These peculiar furrows seem to correspond to ventral 

inner edge of doublure.

Figured specimens. USNM 167220a, b.

Occurrence. USGS collection D2052 CO, Meiklejohn Peak, Nev.

Discussion. The lack of cephalic parts prevents 

positive identification of these pygidia. Raymondites 

ingalli Raymond bears a long stout spine on the 

pygidium (Wilson, 1947, pi. II, figs. 15, 16; Whittington, 1953, pi. 69, figs. 16, 17, 21) which interrupts only 

the posterior axial segments. Whittington's illustration 

(1953, pi. 69, fig. 21) shows suggestion of furrow 

corresponding to inner edge of doublure. Raymondites 

trispinosus Wilson (1947, pi. II, fig. 8) also bears a 

spine on the pygidial axis. But both these species of 

Raymondites have narrow, strongly convex pygidial 

axes with prominent terminations, whereas the present 

species has a wide, terminal piece of low relief.

I have found no reference to a bathyurid with a 

comparable pygidium.

Proetid pygidium 

Plate 16, figure 16

A small, probably transitory, pygidium of proetid 

character was found in beds above the bioherm but it 

has no assignable cephalic parts. Its outline semielliptical; length (sag.) about six-tenths its width 

(trans.). Axis composed of three rings plus sharply 

rounded terminal piece; terminal piece bears trace of 

anterior segment at crestline. Axial outline tapering 

posteriorly. Axial furrows shallow but distinct, confluent around posterior of axis. Pleural platforms 

gently convex, crossed by three pairs of pleural and 

interpleural furrows. No distinct border.

Figured specimen. USNM 167222.

Occurrence. USGS collection D2052 CO, Meiklejohn Peak, Nev.

Genus SELENOHARPES Whittington, 1950

Seleno7iarpes Whittington, 1950, monograph of the British 

trilobites of the family Harpidae: Palaeontographical Soc., 

p. 10.

Selenoharpes sp. 

Plate 16, figures 7, 8

Two fragmentary cephalons of /Selenoharpes were 

obtained high in the bioherm at Meiklejohn Peak; they 

are not adequate for species identification.

Cephalon semielliptical in outline. Its greatest width 

opposite occipital furrow equals 1.6 times the cephalic 

length (sag.). Length of prolongations not known. 

Glabella narrow, its length (sag.) about forty-eight 

one-hundredths that of cephalon (sag.). Glabellar 

width at lobes \p equals six-tenth glabellar length 

(sag.). Eyes located opposite front eight-tenths of 

glabella, distant from axial furrow more than half way 

to the proximal edge of cheek roll. Inconspicuous alae 

of the same length (exsag.) as glabellar lobes \p; the 

width (trans.) of each ala about three-tenths total 

width glabella.

Outline of proximal edge of cheek roll almost 

straight across in front of preglabellar field, curving 

fairly sharply to rear in front of eyes. Course of girder 

evenly curved across front; course not known on prolongations. Brim concave, its width (sag.) equaling 

one-third length (sag.) of cephalon.

Figured specimens. USNM 167221a, b.

Occurrence. USGS collection D1968 CO, 168 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev. USGS collection D2054 CO.

Discussion The fragmentary nature of the two 

available specimens obviously prevents formal identification or complete description of this species. The glabella is narrower than in 8elenoharpes mtilis Whittington (1963, pi. 2, fig. 7), yet wider than in S. singularis 

Whittington (1965, pi. 8). The outline of the proximal edge of the cheek roll is like that in 8. singularis 

not the evenly rounded curve of 8. vitilis. The sagittal 

length of the glabella relative to the overall sagittal 

length of cephalon is longer than in S. vitilis and 8. 

fraqilis (Raymond) but shorter than in 8. singularis. 

The critical course of the girder relative to the prolongations cannot be observed. The eyes appear to be 

farther from the glabella than in either 8. vitilis or 8. 

singularis.

Although this Nevada species seems to differ from 

the three Table Plead species, it is obviously very similar to all of them. It is in the similarity of Table 

Head species, shared by a high percentage of the 

fauna, that the stratigraphic importance of the Meiklejohn specimens lies.
DESCRIPTIONS OF FOSSILS 37

Genus ENDYMIONIA Billings, 1865 

Endymionia cf. E. meeki (Billings)

Plate 16, figures 9-15, 18

This species is represented by three fairly mature 

and one immature cranidia in present collections.

Figured specimens. USNM 167223a-c 167225.

Occurrence. USGS collection D1968 CO, 168 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev. One immature cranidium from 

USGS collection D1973 CO, 60-65 feet above the base 

of bioherm, same locality.

Discussion. The Nevada specimens resemble most 

closely the type of Endymionia meeki, illustrated by 

Whittington (1965, pi. 15, figs. 19, 23, 24). However, 

no median glabellar tubercle is present. Endymionia 

raymondi (Whittington, 1965, pi. 15, figs. 21, 22, 25) 

differs markedly in greater cramdial width (trans.), 

steepened preglabellar field, and virtual lack of flattened border on the cranidium.

I have found it almost impossible to distinguish E. 

meeki from E. schucherti Raymond except for the difference in position of the glabellar tubercle. The tubercle is immediately in front of the occipital furrow in 

E. schucherti and near the midlength of the glabella in 

E. meeki. It is possible that the tubercle can be seen 

only in decorticated specimens.

The importance of the Nevada specimens is the provision of another link with the "Whiterock" provincial 

faunas of Quebec and western Newfoundland.

Genus LEHUA Barton, 1916 

Lehua aff. L. argus Whittington

Plate 16, figure 17

Single incomplete cephalon in present collections 

closely resembles that of Lehua argus Whittington 

(1963, p. 84-86, pi. 23, figs. 1-4, 6, 8, 9). Glabella of 

Nevada specimen almost parallel-sided. Lateral glabellar furrows 3p sigmoid, running inward then backward, then posteroproximally.

Figured specimen. USNM 167224.

Occurrence. USGS collection D1991 CO, 10 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. The single cranidium of Lehua differs 

from that of L. argus in the sigmoid trace of glabellar 

furrows 3;; and in the uniform width of the glabella. 

In other respects it is virtually indistinguishable from 

L. argus.

The stratigraphic importance of Lehua lies in establishing the presence in the bioherm at Meiklejohn Peak 

of yet another species very similar to one from the biohermal limestone of Lower Head, Newfoundland 

(Whittington, 1963, p. 84-86).

Genus PLIOMEROPS Raymond, 1905

Pliomerops is represented in the beds above the 

bioherm (USGS colln. D2051 CO) by a cranidium 

and partial thorax, two cranidia, and two pygidia and 

in the bioherm by one pygidium (USGS colln. D1968 

CO). Pliomerops is generally considered to be a guide 

to strata of Chazy or younger age in the Appalachian 

region (Shaw, 1968, p. 88-89).

As noted by Whittington (1961, p. 917), Pliomerops 

differs from Pseudomera

in the absence of a median pit in the preglabellar furrow, the 

shallow lateral glabellar furrow 3p that commences in the preglabellar furrow, the more rounded outline of the anterior 

margin of the glabella, the presence of 18 thoracic segments, 

and the absence of pits or a U-shaped furrow in the triangular 

terminal piece of the pygidial axis.

Valdar Jaanusson (written commun., May 25, 1970) 

has collected specimens of Pliomerops from the Mountain Lake Member of Cooper (1956) of the Bromide 

Formation in the Arbuckle Mountains (along Oklahoma Highway 99, 3 miles south of Fittstown, Okla., 

top of Harris' zone 49).

As noted by Shaw (1968, p. 89), P. senilis (Barrande) occurs in strata of Llanvirn age in Bohemia. 

Dean (1966, p. 284-287) has redescribed Pliomerops 

escoti (Bergeron), an Arenigian species from France. 

This last species bears considerable resemblance to 

Canadian (Arenig) pliomerids of Utah.

The stratigraphic range of Pliomerops s.s. probably 

is not as restricted in North America as it seems to be 

in the Appalachian region.

Pliomerops sp. 

Plate 16, figures 19-24

Specimens are poorly preserved in compact silty 

limestone which defies proper preparation.

Glabella semicircular in anterior outline, widest at 

front. Occipital ring of same width sagittally and 

exsagittally; curved forward medianly. Occipital furrow continuous across glabella, curving forward medianly. Lateral glabellar furrows Ip cross almost onethird of glabella; proximally, ends curve backward 

very slightly. Lateral furrows 2p oriented transversely 

straight, crossing a little more than one-third glabella. 

Lateral glabellar furrows 3p originate in front of 

fossulae and run somewhat posteroproximally so that 

proximal ends are alined with ends of furrows \p 

and 2p. Axial furrows deep, intersecting preglabellar 

furrow at fossulae. Preglabellar furrow deepest at 

fossulae, shallowing medially. No median pit in preglabellar furrow, but a faint median muscle scar 

seems to produce indentation on front of decorticated 

odabella.
38 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

On cranidium, each palpebral rim, bounded proximally by distinct furrow, extends along facial suture 

from point slightly in front of lateral glabellar furrow Ip forward to point opposite middle of lateral 

glabellar lobe 3p. Posterior course of facial suture 

fairly straight, runs laterally and slightly posteriorly 

to cross border furrow and border in front of genal 

angle and opposite front half of lateral glabellar 

lobe Ip. Fixed cheeks coarsely pitted.

Single incomplete specimen retains cranidium, parts 

of free cheeks, and most of thorax. Posterior part of 

thorax badly damaged. Remaining thoracic segments 

number 16, possibly 17.

Pygidium composed of five axial rings and five 

pairs of digitate pleurae. Posterior triangular terminal 

piece of axis completely enclosed by proximal part of 

posterior pair of pleurae. Pleurae flexed abruptly downward so that distal ends approach the vertical.

Figured specimens. USNM 167226a, b.

Occurrence. USGS collection D2051 CO, Meiklejohn Peak, Nev.

Discussion. Pseudomera and Ectenonotus have previously been reported from beds flanking and immediately above the bioherm at Meiklejohn Peak. The discovery of Pliomerops in these beds was unexpected and 

adds support to the belief that "Whiterock" beds are 

at least partly of Chazy or Marmor age.

The specimens described here probably belong to a 

new species of Pliomerops. In P. canadensis (Billings) 

the palpebral furrow extends farther backward, lateral 

glabellar furrows %p are not as deeply cleft, and lateral 

furrows Ip are shorter (exsag.). In all these respects 

the Nevada specimens more closely resemble P. senilis 

(Barrande). On the pygidia of P. canadensis and P. 

senilis, the fifth axial ring is separated from its pleurae 

by axial furrows; lack of separation in the pygidia 

from Meiklejohn Peak may be due to a different degree 

of decortication.

Pliomerops sp. 

Plate 16, figure 25

A single poorly preserved pygidium is illustrated 

as a matter of record. Lacking cephalic parts, no 

generic assignment can be made with confidence. Although similar in form to pygidia of Pseudo'mera, this 

pygidium lacks the U-shaped furrow on the terminal 

piece of the axis. It therefore resembles Pliomerops 

more than Pseudomera.

Figured specimen. USNM 167227.

Occurrence. USGS collection D1968 CO, 168 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Genus KAWINA Barton, 1916

Kawina wilsoni Ross, n. sp.

Plate 17, figures 1-16

Surface very finely granular with widely scattered 

large pustules. Glabella strongly convex, widest at lateral lobes \p. Greatest width (trans.) nearly equals glabellar length (sag.), exclusive of occipital ring. In lateral view anterior of glabella slightly overhangs preglabellar furrow; median lobe highest between backs 

of lateral lobes 2^>, sloping backward steeply into occipital furrow. Lateral glabellar furrow ~Lp S-shaped, 

but curvature of S adjacent to axial furrow not pronounced and somewhat variable; proximal ends of furrows not reaching occipital furrow. Furrows 2p and 

3p evenly spaced at sides, joining axial furrows at right 

angle, running inward with gentle backward curve 

very nearly parallel to each other. Furrow 3p the shortest. Occipital furrow almost straight or very slightly 

concave on forward side at midline of glabella; laterally curving backward the slightest amount to accommodate posterior of lateral glabella lobes \p. Occipital ring low, of slight convexity, widest (sag.) 

near middle, narrowing laterally. Axial furrow not so 

deep as occipital furrow but deeper than preglabellar 

furrow. Border in front of preglabellar field exceptionally narrow. Palpebral lobe located close to axial furrow and opposite anterior "corner" of lateral glabellar 

lobe Ip. Anteriorly, facial suture closely parallels axial 

furrow, crosses border furrow opposite lateral glabellar furrow 3;?, and turns abruptly along outer edge of 

border. Posteriorly, facial suture runs laterally almost 

parallel to posterior border furrow before turning 

sharply to cross posterior border at right angle. Width 

(trans.) of posterior fixed cheek equals one-half width 

(trans.) of occipital ring. Posterior border narrow 

(exsag.) adjacent to axial furrow, doubling in width 

(exsag.) where crossed by facial suture.

Pygidium with low broadly triangular axis, composed of articulating half ring, three rings, and a 

minute triangular terminal piece. Apical angle of 

"axial triangle" approximately 60°. Articulating furrow straight across; first ring furrow very gently convex forward; second ring furrow slightly convex 

backward. Pleurae paddle shaped, outlined by interpleural furrows; tips bluntly rounded. Posterior pair 

fused to enclose axis.

Bolotype. 'USm/L 167228a.

Paratypes. 'USm/L 167228b-h. 

Occurrence. USGS collection D1973 CO, 60-65 

feet above base of bioherm, D1966 CO, 50 feet above 

base of bioherm, D1968 CO, 168 feet above base of bioherm, Antelope Valley Limestone, Meiklejohn Peak, 

Nev.
DESCRIPTIONS OF FOSSILS 39

Discussion. The sharp convexity of the glabella in 

anterior profile distinguishes this species from Kawina 

limbata Whittington, K. arnoldi Whittington, Cydonocephalus griphus Whittington, C. protificus (Billings), 

C. mercurius (Billings), C. prominulus Whittington, 

C. torulus Whittington, and C. scrobiculus Whittington. In this respect, it most closely resembles Kawina 

vulcanus (Billings). In lateral profile the greater 

convexity of the glabella separates K. wilsoni from 

K. arnoldi Whittington and all species of Cydonocephalus; in side view K. vulcanus and K. ? chazyensis 

(Raymond) are more sharply convex at the rear of 

the glabella.

The spacing of lateral glabellar furrows is virtually 

the same as in Kawina arnoldi and K. ? chazyensis but 

differs from all other described species of Kawina or 

Cydonocephalus. The pygidium is almost identical 

to that described by Whittington (1963, p. 95, pi. 

31, figs. 2, 3, 6, 7) as Kawinal sp. It differs markedly 

from the pygidium of K. arnoldi in the size and shape 

of the terminal piece.

Genus XYSTOCRANIA Whittington, 1965

Xystocrania Whittington, 1965, Harvard Univ. Mus. Comp.

Zoology Bull., v. 132, no. 4, p. 412. 

Nieszkowskia Schmidt. Shaw, 1968, New York State Mus. and

Sci. Service Mem. 17, p. 81.

Xystocrania is probably divisible into two groups of 

species. One of these groups is characterized by very 

weak, almost obsolete, lateral glabellar furrows 2p and 

3p and an erect midglabellar spine. The included species are X. perforator (Billings) (Whittington, 1965, 

p. 412, pi. 61), X. cf. X. perforator (Billings) (Ross, 

1970, p. 89, pi. 17, figs. 3-7, 10) and X. unicornica 

(Hintze, 1952).

The second group of species has lateral glabellar 

furrows 2p and 3 p well defined and rising from the 

axial furrows virtually at right angles; the crest of the 

glabella is considerably involved in the base of the 

median spine. The base of the spine is located in front 

of the proximal ends of furrows Ip and approximately between the proximal ends of furrows 2p. This 

group includes Xystocrania glaucus (Billings) and X. 

cf. X. glaucus (Billings) (Whittington, 1965, p. 414- 

415, pi. 62, figs, l-A, 6, 8, 9), X. pyriformis Ross, n. sp., 

and X. satyrus (Billings) (Shaw, 1968, p. 81-82, pi. 

13, figs, 1, 5, 6, 10,12,13,15-17). No pygidia are known 

for any of these species.

The stratigraphic ranges of these two groups of 

species are very similar. The first seems to occur in muddy limestones and calcareous mudstones, whereas the 

occurrences of the second may be related to purer limestones of a biohermal f acies. This suggestion as it relates to X. glaucus needs further testing.

Xystocrania pyriformis Ross, n. sp. 

Plate 17, figures 17-20

Glabella almost pear shaped in lateral view, its 

crest drawn out to form subconical base of median 

spine. Exact length of stout spine not known. Glabellar 

width (trans.) greatest across lateral lobes Ip, narrowing rapidly. Base of median spine centered between 

proximal ends of furrows 2/?. Front of glabella overhanging preglabellar furrow. Lateral glabellar furrows start very slightly above axial furrows. Furrows 

Ip, S-shaped, proximal ends not reaching occipital 

furrow. Furrows 2p and 3p gently curved, 3p, the 

shorter. Distance along axial furrow from occipital 

furrow to Ip longer than from \p to 2^»; distance 

from 2/> to ?>p still shorter. Occipital ring widest sagittally. Eye located opposite back half of lateral glabellar lobe 2/?.

Holotype. T3ST$M. 167229.

Occrurence. USGS collection D1968 CO, 168 feet 

above base of bioherm, D1973 CO 60-65 feet above 

base of bioherm, Antelope Valley Limestone, Meiklejohn Peak, Nev.

Discussion. Xystocrania pyriformis, as noted under 

the generic description, differs from X. perforator in 

stronger development of the lateral glabellar furrows 

2/? and 3/?. It more closely resembles X. glaucus (Billings) from the lower Table Head Formation and X. 

satyrus (Billings) from the reef limestones of the 

Chazy Limestone (Shaw, 1968, p. 81, table 5) in the 

strength of all glabellar furrows and in the peculiar 

modification of the glabellar crest to form a base for 

the great median spine. In X. satyrus the spine must 

have been raked backward to some extent; in X. 

pyriformis it is more erect. In X. glaucus from the 

Mystic Conglomerate (Whittington, 1965, pi. 62, figs. 

4, 8, 9), the spine seems to have been raked a little 

less than in X. satyrus, whereas in X. cf. X. glaucus 

from the Lower Table Head Formation (Whittington, 

1965, pi. 62, figs. 1-3, 6) it is directed as in X. pyriformis. The glabellar crest of this Lower Table Head 

species is not so much involved in the spine base as 

it is in X. pyriformis.

Genus HELIOMERA Raymond, 1905

Heliomera Raymond Whittington, 1965, Harvard Univ. Mus. 

Comp. Zoology Bull., v. 132, no. 4, p. 416-417.

Two incomplete cranidia represent Heliomera in 

the collections from Meiklejohn Peak. Neither is 

worthy of unquestioned species designation. Heliomera 

has not previously been reported in western North 

America; it joins several genera from the great bioherm that have been known for many years from
40 FOSSILS FROM THE ORDOVICIAN BIOHE'RM AT MEIKLEJOHN PEAK, NEVADA

biohermal limestones of western Newfoundland and 

southern Quebec.

Heliomera cf. H. albata Whittington 

Plate 17, figures 21-25

The incomplete larger cranidium was unfortunately 

further damaged in preparation so that the critical 

lateral glabellar lobe 3/? was partly ground away at the 

distal end; this lobe was originally distinctly L-shaped 

and is still faintly L-shaped, as described in Heliomera 

albata by Whittington (1963, p. 86). However, the Lshape is not as pronounced as in the Newfoundland 

specimens.

The second and smaller cranidium may not belong to 

the same species,, because it seems to lack the L-shape 

in lateral glabellar lobe 3/?. However, Whittington 

(1963, pi. 24, figs. 1-13) has shown that in immature 

cranidia this feature is not developed so well as in 

larger specimens. Inasmuch as the two cranidia were 

taken from the same piece of limestone, one probably 

is an immature specimen and the other a more mature 

example of the same species.

Figured specimens. USNM 167230a, b.

Occurrence. IJSGS collection D1968 CO, 168 feet 

above base of bioherm Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Genus MlRACYBELE Whittington, 1965

The specimen illustrated here is possibly assignable 

to Cybelumis Levitskii 1960. However, no pygidia of 

the type distinguishing Cybelurus have been found in 

any Nevada strata.

Miracybele and Cy'behirus are closely related and 

lived at about the same time. However, species assigned to Cylelurus by Levitskii (1962) have 18-24 

axial rings on the pygidium, as compared with the 

14-15 in Miracy'bele mim (Billings). Further, pygidial 

pleurae in Cy'belurus planifrons Semenova, type spe-' 

cies, are flattened and divided by pleural furrows in 

a manner reminiscent of Pilekia. Pleurae in Miracybele mira are slender and graceful.

Pygidia similar to those of Miracy~bele mira have previously been reported from strata correlative with 

those of the bioherm at Meiklejohn Peak (Koss, 1967, 

pi. 8, figs. 23-25).

Whether differences in pygidia should be given 

generic rank is a question that may not be resolved 

until Spitsbergen faunas have been studied by Kichard 

Fortey and until the trilobites of the Albany Mudstone of Ayrshire, Scotland (Koss and Ingham, 1970, 

p. 395-396), have been described by Ingham and this 

author.

Miracybele sp. 1 

Plate 17, figure 26

Miracybelel sp. 1. Ross, 1967, U.S. Geol. Survey Prof. Paper

523-D, p. D25 pi. 8, fig. 23. 

Aff. Miracy'bele sp. 1. Ross, 1970, U.S. Geol. Survey Prof.

Paper 639, p. 92, pi. 18, fig. 6.

A fairly complete cranidium from beds flanking the 

great bioherm at Meiklejohn Peak bears a remarkable 

resemblance to a species found in Spitsbergen (Richard Fortey, written commun., Apr. 4, 1969).

Cranidium 2.5 times as wide as long (sag.). Posterior 

margin of cranidium curved backwards laterally. 

Fixigenal spines stout. Glabella expanding forward 

from occipital furrow to frontal lobe, but slightly 

constricted opposite lateral furrows 4/>. Glabella width 

at frontal lobe almost 1.5 times its width at occipital 

furrow and 1.25 times width (trans.) of occipital 

ring. Occipital ring longest (sag.) at midline and 

bearing a faint median tubercle. Lateral glabellar furrows Ip deepest proximally, oriented transversely and 

connected to axial furrows. Glabellar furrows 2p and 

3p reduced to elongate transverse pits not connected 

to axial furrow. Furrows 1^>, 2p, and 3/> equally 

spaced forward from occipital furrow. Glabellar furrow 4:p oriented anteroproximally to posterodistally, 

also reduced to elongate pit without obvious connection to axial furrow. In decorticated specimens furrows 2?? may show a shallow connection with axial 

furrow, and furrows 3p and 4/> may be connected at 

their distal ends with shallow furrow in form of Y 

connected to axial furrow. Frontal lobe of glabella 

poorly defined on exterior of carapace; its anterolateral 

bounds indicated by narrow creaselike intersection of 

preglabellar furrow and axial furrow. Preglabellar 

furrow extremely faint; in decorticated specimens 

transverse median pit lies in furrow and is joined by 

faint sagittal median furrow creasing front of glabella. 

Unlike other species of Miracybele this species bears 

only a flattened transverse depression in place of 

median pit and no trace of sagittal crease oh exterior 

of carapace. Anterior border, possibly analogous to 

preglabellar field, broad (exsag.), gently convex, barely 

differentiated from frontal lobe of glabella, on cranidium bounded laterally by axial furrows.

Posterior border of cranidium bounded proximally 

by deep, narrow furrow confluent with occipital fur- 

 row. Border rounded subtubular, continuous with 

stout fixigenal spines. Fixed cheeks slope steeply away 

from eye lobes, which stand much higher than glabella 

and opposite glabellar furrows 2p. Eye ridges run 

inward and forward to intersect axial furrows opposite lateral glabellar furrows 3p. Surface of fixed 

cheeks finely pitted, except for eye ridges.
DESCRIPTIONS OF FOSSILS 41

Figured specimen. USNM 167231.

Occurrence. USGS collection D1971 CO, in beds 

flanking bioherm 207 feet above base of bioherm, 

Antelope Valley Limestone, Meiklejohn Peak, Nev. 

This species has also been found in USGS collection 

D727 CO (Ross, 1967, p. D25, pi. 8, fig. 23) and in 

USGS collection D1603 CO (Ross, 1970, p. 92, pi. 18, 

fig. 6).

Discussion. This species differs from Miracybele 

mira (Billings) in reduction of its lateral glabellar 

furrows 2/?, 3p, and 4p to elongate pits and in the poor 

definition of the preglabellar furrow. It differs from 

a new imdescribed species found in the Albany Mudstone of the Girvan district, Scotland, and from a 

species figured as Pliomerops by Nikolaisen (1961, 

pi. 2, fig. 4) for the same reasons.

These Nevada specimens from the Orthidiella zone 

are similar to forms discovered in the Middle Ordovician of western Spitsbergen (Richard Fortey, 

written commun., Apr. 4, 1969) and listed from the 

Upper Limestone Division of the Valhallfonna Formation by Vallance and Fortey (1968).

Genus APATOLICHAS Whittington, 1963

Apatolichas Whittington, 1963, Harvard Coll. Mus. Comp. 

Zoology Bull., v. 129, no. 1, p. 104-106.

Apatolichas cf. A. jukesi (Billings) 

Plate 18, figures 1-8

Cranidial proportions virtually same as in A. 

jukesi (Billings); however, differences seem to exist 

in definition of furrows on glabella.

Lateral glabellar furrows Ip faintly defined on 

outer surface of carapace. Axial furrow behind eye 

lobe indicated by break in slope rather than by smooth 

crease, running almost straight back from eye lobe to 

occipital furrow. Similarly defined furrow delineates 

front side of occipital lobe; this furrow originates at 

intersection of longitudinal and occipital furrows, 

running outward and very slightly forward almost 

parallel to lateral glabellar furrow Ip, resulting in 

triangular occipital lobe.

Figured specimens. USNM 167232a-c.

Occurrence. USGS collection D1968 CO, 168 feet 

above base of bioherm, Antelope Valley Limestone, 

Meiklejohn Peak, Nev.

Discussion. Whittington (1963, pis. 32, 34) has 

shown clearly that definition of various furrows on 

the glabellae of Apatolichas jukesi is a function of 

maturity of the individual as well as of mode of preservation. The smaller the specimen the better defined are 

the glabellar lobes. And in decorticated cranidia the

inner molds show furrows much more clearly than 

those on the outside of the carapace.

None of the Nevada specimens are well preserved. 

Eyes are broken from them all. Partly decorticated 

specimens show the furrows well (pi. 18, figs. 3-5), but 

large specimens still bearing the outer carapace seem 

to show traces of furrows better than examples from 

Newfoundland. The difference is so slight and inconsistent that it cannot be used with confidence to 

differentiate the Nevada and Newfoundland specimens. When pygidia are found for the Nevada material 

they may provide the means of distinction.

The genus is so far known only in biohermal limestone at Lower Head, Newfoundland (Whittington, 

1963) and in the bioherm at Meiklejohn Peak, Nev.

PYGIDIA OF UNCERTAIN AFFINITY

Undetermined pygidium 1 

Plate 18, figure 9

Pygidium transversely subelliptical in outline, of 

moderate convexity; its length (sag.) equals six-tenths 

its width (trans.). Axis short, poorly defined posteriorly. Length of axis (sag.) a little more than sixtenths that of pygidium. Width of axis (trans.) onequarter that of pygidium and two-thirds length (sag.) 

of axis. Three very faintly defined axial rings plus 

terminal portion. Axial furrows very distinct along 

sides of axis. Pleural regions bounded by shallow 

border furrow and border of very low convexity. 

Width of border (sag.) about one-fifth length of 

pygidium.

Figured speci?nen. US^'M 167233.

Occurrence. USGS collection D1973 CO, Meiklejohn Peak, Nev.

Discussion. This pygidium is associated with Illaenus, Nileus, Carolinites. Kawina, and Xystocrania. 

It is unlikely that it could be assigned to any of them; 

its general form is vaguely similar to pygidia of the 

nileid Peraspis.

Undetermined pygidium 2

Plate 18, figures 10-12

Pygidium semicircular, evenly convex, bearing short 

bluntly rounded axis. Length (sag.) of pygidium 

about six-tenths its width (trans.). Length of axis 

about seven-tenths length of pygidium (sag.); width 

(trans.) of axis three-tenths that of pygidium and 

2/3-3/4 its own length (sag.). In decorticated specimens axial rings faintly defined; four rings plus terminal piece. Pleural regions evenly convex, curving 

downward more steeply toward margin; lacking furrow and border. Surface marked by concentric Bertillion lines.
42 FOSSILS FROM THE ORDOVICIAN BIOHERM AT MEIKLEJOHN PEAK, NEVADA

Figured specimens, USNM 167234a-c.

Occurrenc. USGS collection D1973 CO, Meiklejohn Peak, Nev.

Discussion. No cramdium to which this pygidium 

can be assigned has been found associated with it. 

The pygidium bears close resemblance to other unassigned forms illustrated by Koss (1951, pi. 30, figs. 

12, 13, 16) and by Hintze (1952, pi. XV, figs. 18a. b).

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INDEX

Acknowledgments_------------_._...... 2

Acodus sp.-.. - ___-__ 11,13

Acontiodus varicostatus.__ _.__ __._ __ 12 

sp._......-..-._---_---_-.-.-.-........ 11,12,13

AcTOtretid-................................... 15

acukatus, Periodon................... 9,12,13,14,15

acuminatus, Porambonites.... ...__.._.________ 24

Agnostid trilobite............................ 14

Albany Mudstone.........._............ 29,40,41

albata, Heliomera....................... 12, 40; pi. 7

alveatus, Ittaenus.............................. 32,33

angustagena, Carolinites---. ................... 12,30

Anomalorthis. ............................. 15,16,22

fascicostellatus............................. 14,15

zone..._-..---.-.-.-................. 17,30,35

sp..................................... 13,14,15

Antelope Valley Limestone.......... 1,2,9,11,12,14

antigua, Phragmorthis .... ............. 14, 22; pi. 2

Aparachites.................................__ 14

j4patoZ.chas.-_...--.--.--....--..--..-..... 16,17,4^

jukeai............................... 12, #; pi. 18

Archinacella sp............................... 11

arcuatus, Harpittaenus........................ 34

Ardwell Mudstone._........................ 21

argus, Lehua............................ 9, 37; pi. 16

arnoldi, Kawina.............................. 39

Arthropoda..- ............................. 28

Articulata.................................... 17

Asaphus shale.. __._ ..__ ____ __ 2,24

auriculatus, Illaenus..... 11, 12, 14, 32, 33; pis. 12-14

austrina, Petroria ^ ............. 11, 12, 27; pi. 11

B 

Balclatchie Mudstone_...................... 21

Ballardina simplex............................ 14

barnesi, Orthidium............................ 17

Bathyurellus................................ _ 17,34

feitleri.......................... 12, 34, 35; pi. 15

nitidus------.--------.------..-------...-- 35

pogonipensis.............................. 34

teicherti................................... 35

sp. 3.---.-.-.-...----........ 11, 12, 34, 35; pi. 15

sp. 4.-.....____.._._..__._.._.__.... 9, 35; pi. 15

sp.__._._ .............................. 15

Bathyurus.................................... 35

beattyana, Parapilekia... ______________________ 1

beattyensis, Pleurorthis............... 11, 12, SO; pi. 1

bellulum, Orthidium... _________________ 11, 17; pi. 1

Belodina triangular is.......

bivia, Eoleperiditia. ________

Blastoidocrinus elongatus... 

nevadf nsis.............

sp................

Brachiopoda.__._... 

breviceps, Carrickia.....

breviplicata, Camerella. 

Bromide Formation.. 

buccukntus, Illaenus... 

bulbosus, Carolinites--. 

buttsi, Phragmorthis....

Camerella................................ 16, 22, 24

breviplicata................................ 22

sublaevis.................................. 23

sp.l......................... 9, 11, 23; pis. 3, 4

sp. 1................................. 11, 23; pi. 4

[Italic page numbers indicate descriptions and major references]

Page 

Camerellid. -____...---..-.--___-__-_-______-. 13

canadensis, Paucicostella..... ................ 26, 28

Pliamerops. ........ ..................... 15, 38

cardilatus, Cuparius. .................. 11, 28; pi. 11

Carolinites.... ............................ 17, 29, 41

angustagena ...... ......................... 12, 30

bulbosus. ................................. 30

genacinaca... -------------------------- 12,13,30

indentus. ................................. 30

killaryensis- ............... 11, 29, 30; pis. 11,12

utahens is. 

macropthalma.

sibiricus . 

sp. I..... 

sp. 2...-

------------.-.-----.- 30

...................... 30

- --_ - 30

...................... 30

...... .... .- 30

-- -----. - 30

sp.....-_._- - - -- ----- 12

Carr.efcia. --_..-_---_-__ ---------------------- 29

breviceps... ............................... 29

sp. !.__.. ._.-._-_-_------------------- 29; pi. 10

sp _..-- - 12

Chazy Limestone __ -___ _ - 31, 39

chazyensis, Kawina. .......................... 39

Clathrospirasp. .............................. 11

Clisospira .... ................................. 12

C.OMG!!, Ingria. .----.... 11, 12, 14, 15, 26, 28; pis

clusus, Trinodus..-. --------------------

cojiciliata, Idiostrophia. --------------- 8, 25, 26

cojinemaricus, Ectenonotus . . . -----------

Co»o«re.asp. B. ...............- .--...

sp. ------ _ .....----.--..-..-----.-

consimilis, Illaenus. .... .................

consobrinus, Illaenus--. .................

convexa, Pleurorthis. ............-.-.....

Cordylodus fiexosus... ... . ...............

coronatus, Glaphurus. ... ----------------

costata, Idiostrophia.-----------------.--

costellata, Orthidiella. ...................

crassa, Phragmorthis-.---..----------.--

cardilatua .. -.-- .11,28; 

sp.-_-_ ---------- 8,11,12,13,14,15,28;

Cybelurus. ----------------------------------

planifrons __ ..___.--___-----------------

Cydonocfphalus -------------------------------

griphus. ----------------------------------

mercurius.. -------------------------------

prolificus ---------------------- --- --------

pro m inulus .......-.-.-..-...-.--.-.------

scrobiculus.- ------------------------------

torulus --- -------------------------------

Cyrtonellopsis- .............-...--.--------.--

Cyrtonotella -..-. -.------------- 15,

fasciculata- ._.-.-. ---.-. 11, 

sp .... .__-. - --- -

. 9, 10 

29

; pi. 9 

1

15 

15

32,33

32,33 

21 

9 

31

24,25 

14 

22 

16,28

pi. 11

pi. 11 

40 

40 

39 

39 

39 

39 

39 

39 

39 

H

,17,21 

; p. 2 

12

D

Description of fossilsDictyonif.es sp__ _____.- __.--___.____-_- 15

digitata, Idiostrophia .... ....-...--.-.---- 24

Rhynchonella. ------- _ ........... -- 2,24

Terebratula _____ -._. ------ - -- 24

Dimastocephalus.. ---------------------------- 29

Dimeropyge-like trilobite...- -------------- 11

Dimeropygid trilobite. 

Distacodus stola--------

sp.

Page 

14 

13

12

divisus, Glaphurus.--------------------------- 31

Drepanodus----------------------------------- 13,14

suberectus.... -------- ------------ 11,13,14

n.sp. D. 9

sp_ 9,11,12,13

E 

Ectenonotus ........................ 8,12,17,30,38

connemaricus.---------------------------- 1

marginatus_-_.. ---------------------- 1

whittingtonL-------------------------- 12,13,14

sp._----------------------------------- 12,13,14

elongatus, Blastoidocrinus-.---.... -------- 14

Endymionia ----------------------------- 16,17,37

meeki.. - - 11,12,37; pi. 16

raymondi.-------------------------------- 37

schucherti--------------------------------- 37

Eoconulus sp---_---------- ---------------- 15

Eoleperiditia bivia... ------------------------ 14

sp

Eopteria--. -------------------------------- 16> 17

sp

erugata, Peraspis--.-.---------- --- ------------ 32

escoti, PUomerops.-------. -------------------- 37

Eurychilina sp. ------------------------------- -^

exopthalma. Shumardia- ------------------ 29

fascicostellatus, Anomalorthis---.---- ------- 14,15

Pleurorthis ---- ---------------------- 21

fasciculata, Cyrtonotella----------------- 11, 2Z;pl. 2

/eitfen, Bathyurellus-- --------- 12, 34, 35; pi. 15

Niobe.-- --------------------------------- I' 34

fimbriatum, Orthidium ---------------- 9, i7, pi. 1

flexosus, Cordylodus ------------------------ 9

Fort Pena Formation.--.-..------------------ lfi

Fossil collections------ - - ---------- 8

Fossil descriptions.----.---------------------- ^

Fossil distribution, summary..--------------- ^

fragilis, Selenoharpes.-....-..- -------- 36

fraternus, Illaenus-.------------------------ 32

G

gemmiculum, Orthidium- ... - .

genacinaca, Carolinites- ---------

Glaphurus----- ------ -----------

coronatus-. -----------------

dwisus-------------- --- -- 

pustulatus----. --- - --- --- 

SP---- - -------- - 

glaucus, Xystocrania. -----------

Glossellinid- ___ - 

Goniophrys- ------------ --- -----

prima. ---- - ----- -------

granulosa, Shumardia------ --

griphus, Cydonocephalus. -------

20

12, 13, 30

. 16,17,30

31

31

31

12, 31, pi. 12

39

15

29

29

39

H

Harpillaenus. 

arcuatus- - 

sp 2' 33'

45

l " 15
46 INDEX

Page

Helicotissp................................... 11,12

Heliomera................................. 16,17,39

albata.............................. 12,40, pi. 17

Hesperorthis.................................. 16

matutina.................................. 13

Hyolithes sp..___-_-__...-...-..-.... 11

Hyperchilarinasp............................. 11

Idiostrophia........................... 2,12,16,22,23

conciliata....................... 8,25,2b'; pi. 9

costata.................................... 24,26

digitate................................... 24

lenticularis......................... 12,24; pi. 6

nuda ................................. 8,24,25

paucicostata............................ 11,24,25

perfecta................................ 24,25,26

plicata-.................................. 24,25

polita..................................... 26

valdari-.......................12,25; pis. 6-8, 18

n. sp. A --------_.....--.-.....-..- 24; pi. 4

sp 11,12

niaenus...-...................... 12,16,17,30,32,41

alveolus................................... 32,33

auriculatus............ 11,12,14, 32, S3; pis. 12-14

bucculentus............................... 32

consimilis................................. 32,33

consobrinus............................... 32,33

fraternus.................................. 32

marginalis................................ 32

tumidifrons............................... 33

sp. a__ ....._-----_.--.--.__ 11,33

spb.-. . .- 12,32,33; pis. 13,14

sp. C -.----------.....--.-----....-9,33; pi. 14

sp. d . _. ...... 11,12,33; pi. 14

sp. e._.______..._.._.. 12,33; pi. 14 

sp. f.__- ---.................. 12,33; pi. 14

sp.-.-----.----------.------.-------.-. 11,13,32

inclinatus, Oistodus........................... 13

inculptus, Scolopodus......................... 13

indentus, CaroUnites.......................... 30

ingalli, Raymondites........................... 36

Ingria............................... 15,16,17, t6, 28

doudi............... 11,12,14,15,26,28; pis. 9,10

sp. . _. 12,28

Ischyrophyma sp_....__.....---.---....... 12

Isophragma................................ 15,17,27

sp................................ 16,27; pi. 10

Joins Formation____....__........... 9,1

jukesi,Apatolichas.................... 12,41; pi. lg

Kawina.................................... 17,38,41

arnoldi.................................... 39

chazyensis................................. 39

limbata................................... 39

vulcanus.................................. 39

wUsoni.. .................... 11,12,38; pi. 17

sp.................................. 11,13,14,39

killaryensis, CaroUnites......... 11, 29, SO; pis. 11, 12

utahensis, CaroUnites...................... 30

Kullsberg Limestone......................... 6

lanceolatus, Oistodus.......................... n

Lehua..................................... 16,17,37

argus............................... 9, 37; pi. 16

lenticularis, Idiostrophia................. 12, 24;pl. 5

Leperditetta................................... 14

sp. . . __.._._ 14

Leptella...................................... 28

nevadensis................................ 28

Leptettina.................................... 14,16

sp. .. .-.... ........... 14

Levis Shale of Quebec....-..-.-.....-.....-- 1,6,16

limbata, Kawina.............................. 39

lineolata, Peraspis............................ 32

	Page 

Liospira sp-..--..._............._-------- 11

Liricamera.................................... 16,22

nevadensis................................ 11

sp........................................ 11

longiramus, Oistodus.......................... 13

longwelli, Orthidiella.......................... 14,20

(Lophospira) sp., Loxoplocus.................. 11

Lower Head assemblage of Newfoundland.... 30

Loxoplocus (Lophospira) sp................... 11

M 

Maclurites sp................................. 11

macrodentata, Ozarkodina...................... 12

macropthalma, CaroUnites..................... 30

marginalis, Illaenus........................... 32

marginatus, Ectenonotus...................... 1

marshalli, Orthambonites...................... 27

Orthis.................................... 27

masoni, Trematorthis.......................... 20

matutina, Hesperorthis........................ 13

mcallesteri, Protocalymene..................... 12

meeki, Endymionia................. 11,12, 37; pi. 16

mercurius, Cydonocephalus.................... 39

Mimospira sp............._...__---------- 11

minusculus, Orthambonites.................... 12,13

mira, Miracybele.............................. 40,41

Miracybele..-................................. 40

mira...................................... 40,41

sp 1................................... 12,13,40

Mountain Lake Member.....__.__........ 37

multicorrugatus, Oistodus................... 13,14,16

Mystic Conglomerate of Quebec--....--.-.--- 1,

6,16,16,20,26,28,39 

N

nasuta, Pseudocybele zone.. 

nevadensis, Blastoidocrinus.

Leptella...............

Liricamera.............

Nieszkowskia..............

............. 1

............. 14

. _ 28 

............. 11

.. ... 39 

NOeus.................................. 16,30,31,41

scrutator............... ......... 11,13, SI; pi. 12

sp............................. 9,11,12,13,14, 31

Nlnemile Formation_................._... 1

Niobefeitleri.................................. 1,34

nitidus, Bathyurellus.......................... 35

Notorthis..................................... 16

sp........................................ 11

nuda, Idiostrophia........................... 8,24,25

O

Oepikodus.................................... 16

quadratus................................. 14

sp........................................ 11,13

Oistodus inclinatus............................ 13

lanceolatus................................ 11

longiramus................................ 13

multicorrugatus........................ 13,14,16

parallelus................................. 12, 14

venustus.................................. 14

sp........... . 9,12,13,14

Onychoplecia.................................. 16,17

Sp.......-. . - 11

Orthambonites.............................. 14,17,27

marshalli................................. 27

minusculus............................... 12,13

ap..................................... 13,14,16

Orthid, indet............................... 11

Orthidiella.............................. 16,20,27,36

costellata.................................. 14

longwelli............------------------- 14,20

zone. - - ---. 1,9,14,16,17,21,22,24,27,29,30,41

sp............................. 8,11,12,13,14,15

Orthidium.................................... 16,17

barnesi.................................... 17

bellulum............................ 11, 17; pi. 1

fimbriatum........................... 9, 17; pi. 1

gemmiculum.............................. 20

sp................................. .... 11

Orthis marshalli..........

Outram Formation......

Ozarkodina macrodentata.

Page

27

27

12

Paltodus sp___..--__._------__.. 11,12,14

Panderodus sp.. --... ._._ 14

p^rallelus, Oistodus........................... 12,14

Parapilekia beattyana........................ 1

paucicostata, Idiostrophia................. 11,24,25

Paucicostella............. ......... 11,16,16,17,26,28

canadensis.............. ...._.--...-.... 26, 28

sp...... ._ . . 12

Peraspis................................... 16,31,41

erugata................................... 32

lineolata.................................. 32

sp - 9, SI; pi. 12

perfecta, Idiostrophia....................... 24,26,26

perforator, Xystocrania........................ 39

Periodon...................................... 16,16

acukatus......................... 9,12,13,14,16

sp..... 9,H

Petroria...................................... 17,27

austrina........................ 11,12, 27; pi. 11

rugosa.................................... 27,28

sinuatis................................... 27

Phragmorthis........................... 14,16,16,22

antiqua............................. 14,22; pi. 2

bJittal..................................... 22

crassa..................................... 22

sp.. 12

Pikkia....................................... 40

planifrons, Cybelurus......................... 40

Pleetambonitid ~ 9,11

Plectorthis sinuatis............................ 27

Pleurorthis ........... ...................... 16,20

benttyensis....................... 11,12,20; pi. 1

convexa................................... 21

fascicostellatus............................ 21

sp.-.-------------_---___ 8,11, SI; pi. 2

plicata, Idiostrophia........................... 24,26

Pliomerops............................. 16,17,37,41

canadensis................................ 16,38

escoti...-...-..^.-...................... 37

senilis.................................... 37,38

sp.. 12, 37, 38; pi. 16

pogonipensis, Bathyurellus.................... 34

polita, Idiostrophia............................ 26

popovkiensis, CaroUnites....................... 30

Porambonttes acuminatus.................... 24

Pratt Ferry Formation... _._._ _ 9,16,22 

Previous work....------.----.-- ----------- 1

prima, Ooniophrys............................ 29

Proetid pygidium....-.-.----.------------ 36; pi. 16

prolincus, Cydonocephalus..................... 39

prominulus, Cydonocephalus.........-...-.--. 39

Protocalymene mcallesteri...................... 12

sp... ............ -- - 13,14

Pseudocybele nasuta zone.--- ------------ 1

zone-------------------------------------- 30

Pseudohystricurus sp ... .- 12 

Pseudomera................................... 37,38

sp...... 1,14,16

pustulatus, Olaphurus......................... 31

Pycnomphalid gastropod..... .-. ... 11 

Pygidia of uncertain affinity - ------- 4t

pyriformis, Xystocrania.... ......... 11,12,39, pi. 17

Q 

quadratus, Oepikodus...............--.....--.- 14

R 

Ranger Mountains Member ....---- 2

Raphistoma.-......---.................---- H

raymondi, Endymionia........................ 37

Raymondites...................-..........- 14,15,35

ingalli.......................------------- 36

trispinosus..................-------------- 36

sp...... 35; pi. 16
INDEX 47

Page 

Remopleurides sp...__----------_._. 14

Rhynchocamara............................... 22,24

Rhynchonella digitata............__...._-.- 2,24

Rhysostrophia zone.-.........._...-.....-..- 17,27

Rhysotreta sp.._..__....._. .-...-.- 15

Tugosa, Petroria............................... 27,28

S

satyrus, Xystrocrania.......................... 39

Scandodus unicostatus......................... 9

Seandodus sp______......_....._... 9,12,14

Schizambon................................... 15,16

sp.

schucherti, Endymionia........................ 37

Scolopodus inculptus ......................... 13

varicostatus............................... 9

sp. .............. . ...... 13,14,15

scrobiculus, Cydonocephalus................... 39

scrutator,NUeus.................... 11,13,31; pi. 12

Selenoharpes.................................. 17,35

fragilis ................................. 36

singularis................................. 36

vttaig..................................... 36

sp----. - -. - - 12,13,36; pi. 16

senilis, Pliomerops............................ 37,38

Shumardia.................................... 29

 ezopthalma................................ 29

granulosa................................. 29

sp....................---... 12,29; pi. 11

siblricus, Carolinites........................... 30

simplex, Ballardina........................... 14

singularis, Selenoharpes....................... 36

sinuatis, Petroria.............................. 27

Plectorthis................................ 27

Page 

Skenidioides.................................. 22

Skoki Formation............................. 16,27

Stinchar Limestone.._______.___._ 21,29 

stola, Distacodus.............................. 13

Stratigraphic anomalies_.___________ 15 

Stratigraphic setting__-___............. 2

suberectus, Drepanodus.................... 11,13,14

sublaevis, Camerella........................... 23

Summary of fossil distribution__...._.... 16

Syndielasma.................................. 11

Syntrophiid.-----.--....--.---.-----.------- 12

Table Head assemblage of Newfoundland_. 30 

Table Head Formation of Newfoundland_. 20,

28,29,39 

Taphrodonta............................... 15,17,27

teicherti, Bathyurellus......................... 35

Terebratula d^itata............................ 24

Tetraprioniodus............................... 9

torulus, Cydonocephalus...................... 39

Torynelasma sp. A...--...-.....-..--...... 15

sp...--.....- -. .. . .- 15

Treiorwerth Formation.__.__.. 20 

Trematorthis.................................. 16,20

masoni ................................. 20

sp..-...---..--...-.--.......-.--..- 11, 20; pi. 1

triangularis, Belodina......................... 13

Trilobita............ .....-.-.--..-....- 28

Trinodus..................................... 17,28

clusus.................................... 29

valmyensis................................ 29

sp. I............................... 11, 28; pi. 11

sp- 12,14

Page 

trispinosus, Raymondites...................... 36

Trochonema................................... 11

Tropidodiscus sp_.....__.___........... 11

tumidifrons, Illaenus.......................... 33

U

Undetermined pygidium 1_________ 41; pi. 18 

Undetermined pygidium 2_...._.._. 41; pi. 18

unicornica, Xystocrania....................... 39

unicostatus, Scandodus........................ 9

Uromystrum.................................. 34

utahensis, Carolinites killaryensis.............. 30

valdari, Idiostrophia............... 12, 25; pis. 6-8, 18

Valhallfonna Formation.___....__..... 41

valmyensis, Trinodus.......................... 29

varicostatus, Acontiodus....................... 12

Scolopodus................................ 9

venustus, Oistodus............................. 14

vitilis, Selenoharpes........................... 36

vulcanus, Kawina............................. 39

W 

whittingtoni, Ectenonotus................... 12,13,14

wilsoni, Kawina.................... 11,12, 38; pi. 17

Xystocrania................................ 16,39,41

glaucus................................... 39

perforator................................. 39

pyriformis...................... 11,12, 39; pi. 17

satyrus................................... 39

unicornica................................ 39

U. S. GOVERNMENT PRINTING OFFICE : 1972 O - 446-051

PLATES 1-18

Contact photographs of the plates in this report are available, at cost, from U.S. Geological 

Survey Library, Federal Center, Denver, Colorado 80225.
PLATE 1

[All illustrations are stereophotographs]

FIGURES 1-5. Orthidium bellulum Ulrich and Cooper (p. 17).

USGS colln. D1973 CO X 6. 

1-4. Complete shell; views of exterior of brachial valve, exterior of pedicle

valve, anterior both valves, and left side of both valves. USNM 167177a. 

5. Brachial valve, decorticated. USNM 167177b. 

6-10. Orthidium? aff. O.fimbriatum Cooper (p. 17).

USGS colln. D1991 CO. 

6-9. Complete shell; views of exterior of brachial valve, exterior of pedicle

valve, anterior of both valves, and right side of both valves, X 3. USNM

167178a.

10. Pedicle valve, X 4. USNM 167178b. 

11-14. Trematorthis sp. (p. 20).

USGS colln. D1973 CO.

11. Pedicle valve, X 3. USNM 167179b.

12. Pedicle valve, X 3. USNM 167179c. 

This valve may belong to a different species.

13. 14. Complete shell; views of exterior of brachial valve and of posterior, 

t showing deltidium, X 5. USNM 167179a. 

15-21. Pleurorthis beattyensis Ross, n. sp. (p. 20).

USGS colln. D1973 CO, X 1.

15-18. Complete shell, holotype; views of exterior of brachial valve, right 

side of both valves, exterior of pedicle valve, and anterior of both valves. 

USNM 167180. The exterior has been excavated to show muscle scars 

in fig. 17.

19. B.achial valve, paratype; exterior. USNM 167181a.

20. r rachial valve, paratype. USNM 167181b.

21. Pedicle vilve, paratype; external mould. USNM 167181c.
PROFESSIONAL PAPER 685 PLATE 1

ORTHIDIUM, ORTHIDIUM1, TREMATORTHIS, AND PLEURORTHIS
PLATE 2

[All illustrations are stereophotographs]

FIGURE 1. Pleurorthist sp. (p. 21).

USGS eolln. D1990 CO, pedicle valve, X 2. USNM 167182. 

2-6. Cyrtonotellat aff. C. fasciculate Cooper (p. 21). 

USGS colln. D1973 CO.

2. Brachial valve; latex cast of interior excavated in attempt to unearth 

cardinalia, X 2. USNM 167183a.

3. Brachial valve; exterior partly excavated to show position and proportions 

of notothyrial platform and median septum, X 2. USNM 167183b.

4. Brachial valve; exterior, X 3. USNM 167183c.

5. Pedicle valve; exterior, X 2. USNM 167183e.

6. Brachial valve; exterior, X 2. USNM 167183d. 

7-18. Phragmorthis antique Ross, n. sp. (p. 22).

USGS colln. D2052 CO.

7-9. Brachial valve, holotype; exterior, and anterior views, X 6. USNM 167184. 

10-12. Brachial valve, paratype; exterior, interior, and anterior views, X 6.

USNM 167185a. 

13, 14, 16. Pedicle valve, paratype; exterior, interior, and anterior views X 10.

USNM 167185b. 

15, 17, 18. Pedicle valve, paratype, damaged; exterior, interior, and anterior

views, X 10, USNM 167185c. Interior view shows pallial trunks.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 2

PLEURORTHIS1?, CYRTONOTELLA1, AND PHRAGMORTHIS
PLATE 3

[All illustrations are stereophotographs]

FIGURES 1-18. Camerella sp. 1 (p. 23).

USGS colln. D1973 Co, X 4. 

1-4. Complete shell; views of brachial exterior, pedicle exterior, anterior,

and right side. USNM 167186a. 

5-9. Complete shell, tumid form, with posterolateral sides somewhat

flattened; views of pedicle exterior, brachial exterior, anterior, posterior,

and right side, USNM 167186b. 

10-14. Complete shell, depressed, subcircular form; views of brachial

exterior, pedicle exterior, anterior, posterior, and right side. USNM

167186c. 

15-18. Complete shell, with flattened periphery; views of brachial, pedicle,

anterior, and left side. USNM 167186d.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE

CAMERELLA
PLATE 4

[All illustrations are stereophotographs]

FIGURES 1-4. Camerella cf. C. sp. 1 (p. 23).

USGS colln. D1991 CO, views of exterior of brachial valve, exterior of

pedicle valve, anterior, and right side, X 5, USNM 167187. 

5-8, 14-17. Camerella sp. 2 (p. 23).

USGS colln. D1966 CO, X 5. 

5-8. Complete shell; views of brachial valve, pedicle valve, anterior, and left

side. USNM 167188a. 

14-17. Complete shell; views of brachial valve, pedicle valve, anterior, and

left side, USNM 167188b. 

9-13. Idiostrophia n. sp. A (p. 24).

Asaphus shale, Toyen district, Oslo, Norway. Stage 3c/3; views of exterior of 

brachial valve, exterior of pedicle valve, anterior, posterior, and right 

side, X 4, Paleontologisk Mus. (Oslo) No. 47089.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 4

CAMERELLA AND IDIOSTROPHIA
PLATE 5

[AH illustrations are stereophotographs]

FIGURES 1-25. Idiostrophia lenticularis Ross, n. sp. (p. 24). 

USGScolln. D1968CO.

I-5. Complete shell, holotype and largest specimen discovered; views of 

pedicle exterior, brachial exterior, right side, anterior (upside down) 

and posterior (upside down), X 4, TJSNM 167189.

6-10. Complete shell, paratype and smallest specimen discovered; views 

of brachial exterior, pedicle exterior, right side, anterior, and posterior, 

X 7, USNM 167190a.

II-15. Complete shell, paratype; views of brachial exterior, pedicle

exterior, right side, anterior, and posterior, X 6, TJSNM 167190b. 

16-20. Complete shell, paratype, large specimen almost lacking costae;

views of brachial exterior, pedicle exterior, right side, anterior, and

posterior, X 4, USNM 167190c. 

21-25. Complete shells, paratype, small specimen bearing few faint

costae; views of brachial exterior, pedicle exterior, right side, anterior,

and posterior, X 6, USNM 167190d.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 5

IDIOSTROPHIA
PLATE 6

[All illustrations are stereophotographs]

FIGURES 1-20. Idiostrophia valdari Ross, n. sp. (p. 25).

USGS colln. D1968 CO. All specimens on this plate are of the narrow 

variety.

I-5. Paratype; views of pedicle valve exterior, brachial valve exterior, 

right side, posterior, and anterior, X 5. USNM 167192a. Costae are 

relatively coarse in this specimen.

6-10. Paratype; views of brachial valve exterior, pedicle valve exterior, 

right side, posterior, and anterior, X 6. USNM 167192b.

II-15. Paratype; views of brachial valve exterior, pedicle valve exterior,

right side, posterior, and anterior, X 5. USNM 167192c. Costae are

relatively fine and limited to front of shell. 

16-20. Paratype; views of brachial valve exterior, pedicle valve exterior,

right side, posterior, and anterior, X 7. USNM 167192d. A fairly small

specimen.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 6

IDIOSTROPHIA
PLATE 7

[All illustrations are stereophotographs]

FIGURES 1-20. Idiostrophia valdari Ross, n. sp. (p. 25).

USGS colln. D1968 CO. Most specimens illustrated on this plate are 

somewhat wider than average with fewer than average number of 

costae.

I-5. Paratype, a large specimen; views of exterior of brachial valve, 

exterior of pedicle valve, right side, anterior, and posterior, X 5. USNM 

167192e.

6-10. Paratype; views of exterior of brachial valve, exterior of pedicle 

valve, right side, anterior, and posterior, X 5. USNM 167192f.

II-15. Paratype, a relatively small specimen; views of exterior of brachial 

valve, exterior of pedicle valve, right side, anterior, and posterior, X 7. 

USNM 167192g.

16-20. Paratype; views of exterior of brachial valve, exterior of pedicle 

valve, right side, anterior, and posterior, X 6. USNM 167192h.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 685 PLATE 7

IDIOSTROPHIA
PLATE 8

[AH illustrations are stereophotographs]

FIGURES 1-20. Idiostrophia valdari Ross, n. sp. (p. 25). 

USGS colln. D1968 CO, paratypes.

I-5. Complete specimen with strongly flared outline; views of exterior of 

brachial valve, exterior of pedicle valve, right side, anterior, and posterior, X 5. USNM 167192L

6-10. Complete specimen, with moderately flared outline; views of exterior 

of brachial valve, exterior of pedicle valve, right side, anterior, and 

posterior, X 5. USNM 167192J.

II-14. Complete specimen, with flared outline; views of exterior of

brachial valve, exterior of pedicle valve, right side, anterior, and

posterior, X 5. USNM 167192k. 

16-20. Complete specimen, immature; views of exterior of brachial valve,

exterior of pedicle valve, right side, anterior, and posterior, X 7

USNM 1671921.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 685 PLATE 8

IDIOSTROPHIA
PLATE 9

[All illustrations are stereophotographs]

FIGURES 1-7. Idiostrophia conciliata Ross, n. sp. (p. 26).

USGS colln. D1991 CO. 

1-4. Holotype, complete specimen; views of exterior of brachial valve,

exterior of pedicle valve, anterior, and left side, X 3. USNM 161793. 

5-7. Paratype, large brachial valve with numerous costae; views of exterior,

anterior, and right side, X 2. USNM I67193a. This shell is split close

to beak. 

8-19. Ingria cloudi Ulrich and Cooper (p. 26).

From lower member of Antelope Valley Limestone, along wash south of 

Frenchman Flat. Nevada coordinates, central zone: E. 726,700 ft; 

N. 740,700 ft, Frenchman Lake quadrangle, X 1.5. 

8, 9. Brachial valve; exterior and interior. USNM 167194d. USGS colln.

D719e CO, 100 feet below top of lower member. Cardinal process is

broken in this specimen. 

10, 11. Complete specimen, with wide outline; views of brachial and pedicle

valves. USNM 167l94a. USGS colln. D719e CO. 

12, 13. Complete specimen with subquadrate outline; views of brachial and

pedicle valves. USNM 167194b. USGS colln. D719e CO. 

14, 15. Brachial valve; exterior and interior views. USNM 167194c. USGS

colln. D719e CO. 

16, 17. Brachial valve of alate outline; exterior and interior views. USNM

167195c. USGS colln. D7l9i CO, 60 feet below top of lower member. 

18, 19. Complete shell of alate outline; views of exterior of brachial and

pedicle valves. USNM 167195a. USGS colln. D719i CO.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 9
PLATE 10

[All illustrations are stereophotographs]

FIGURES 1-4, 8, 9. Ingria cloudi Ulrich and Cooper (p. 26).

Lower member of Antelope Valley Limestone, south of Frenchman

Flat. (Ross, 1964, p. C20, pi. 1)

1, 2. Complete specimen; views of exterior of brachial and pedicle 

valves, X 1.5, USNM 167195b. USGS colln. D719i CO, 60 feet 

below top of lower member.

3, 4. Broken specimen, transverse outline; views of exterior of brachial 

and pedicle valves, X 3, USNM 167196b. USGS colln. D719h, 70 

feet below top of lower member.

8, 9. Badly damaged specimen showing extremely alate outline; views 

of brachial and pedicle valves, X 3, USNM 167196a. USGS collin. 

D719h CO, 70 feet below top of lower member 

5-7, 10-13, 17. Ingria? sp. (p. 28).

Main mass of bioherm, Antelope Valley Limestone, at Meiklejohn 

Peak. These specimens may be assignable to Paucicostella.

5. Pedicle valve, X 3, USNM 167197a. USGS colln. D1973 CO.

6. Pedicle valve, X 3, USNM 167197b. USGS colln. D1973 CO.

7. Pedicle valve, X 2, USNM 167197c. USGS colln. D1973 CO.

10. 12. Pedicle valve; exterior and posterior views, X 4, USNM 

167197d. USGS colln. D1990 CO.

11. Brachial valve, X 2, USNM 167197e. USGS colln. D1990 CO. 

13. Pedicle valve, X 3, USNM 167197f. USGS colln. D1990 CO. 

17. Pedicle valve, X 6, USNM 167197g. USGS colln. D1968 CO. 

14-16. LeptelUna? sp. or Taphrodonta? sp. (not described).

USGS colln. D2052 CO. Views of exterior of brachial valve, exterior of

pedicle valve, and anterior, X 4, USNM 167198. 

18, 20. Isophragma? sp. (p. 27).

USGS colln. D1375 CO. Exterior and interior of pedicle valve, X 5,

USNM 167199. This specimen may belong to Taphrodonta. 

19. Carrickia sp. 1 (p. 29).

USGS colln. D1994 CO. Cranidium; dorsal view, X 10, USNM 167205
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 10

INGRIA, INGRIA1, LEPTELLINA1 OR TAPHRODONTA1, 

ISOPHRAGMA1, AND CARRICKIA
PLATE 11

[All illustrations are stereophotographs]

FIGURES 1-5. Petroria austrina Ross, n. sp. (p. 27).

USGS colln. D1973 CO. X 3. 

1, 2. Holotype, complete shell; views of exteriors of brachial and pedicle

valves. USNM 167200. 

3-5. Paratype, pedicle valve; views of exterior, anterior, and right side.

USNM 167200a. 

6-9. Cuparius cardilatus Ross (p. 28).

USGS colln. D1973 CO. Large complete shell; views of exterior of brachial 

valve, exterior of pedicle valve, anterior, and left side, X 2. USNM 

167201. 

10. Shumardia sp. (p. 29).

USGS colln. D1994 CO. Cranidium; dorsal view, X 10. USNM 167204. 

11-14. Carolinites cf. C. killaryensis (Stubblefield) (p. 30).

11. 13, 14. Cranidium; left lateral, anterior, and dorsal views, X 3. USNM 

167206a. USGS colln. D1966 CO.

12. Pygidium; dorsal view, X 6. USNM 167206b.

USGS colln. D1973 CO. Note base of upright spine on combined crests 

of fourth axial segment and terminal piece. 

15, 16. Trinodus sp. 1 (p. 28).

USGS colln. D1973 CO, X 10.

15. Cephalon; dorsal view. USNM 167203a.

16. Pygidium; dorsal view. USNM 167203b. 

17. Cuparius sp. (p. 28).

USGS colln. D1966 CO. Pedicle valve, showing pitted exterior of shell, X 4. 

USNM 167202.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 11

PETRORIAt, CUPARIUS, SHUMARDIA, CAROLINITES, AND TRINODUS
PLATE 12

[All illustrations are stereophotographs]

FIGURES 1-6. Carolinites cf. C. killaryensis (Stubblefield) (p. 30). USGS colln. D1973 CO,

X 4.

1, 2, 5. Cranidium; dorsal, anterior, and left lateral views, USNM 167206c. 

3, 4. Free cheek, left (genal spine broken off); lateral and dorsal views,

USNM 167206d. 

6. Free cheek, right (part of genal spine preserved); dorsal view, USNM

167206e. 

7-9. Glaphurus sp. (p. 31).

USGS colln. D1968 CO. Cranidium; dorsal, anterior, and lateral views,

X 7, USNM 167207. 

10-16. Nileus aff. TV. scrutator Billings (p. 31).

All from USGS colln. D1973 CO except fig. 15.

10-12. Cranidium; dorsal, anterodorsal, and lateral views, X 2, USNM 

167208a.

13. Pygidium; dorsal view, X 2, USNM 167208b.

14. Pygidium; dorsal view, X 4, USNM 167208c.

15. Pygidium; dorsal view, X 1.5, USNM 167208d. 

USGS colln. D1971 CO.

16. Cranidium; dorsal view, X 3, USNM 167208e. 

17, 18. Peraspis? sp. (p. 31).

USGS colln. D1991 CO. Pygidium; dorsal and lateral views, X 1, USNM

167209. 

19-26. Illaenus cf. /. auriculatus Ross (p. 32).

USGS colln. D1973 CO. 

19-22, 26. Cephalon; dorsal, anterior, left lateral, right lateral, and anteroventral views, X 2, USNM 167210a. 

23-25. Cranidium; dorsal, anterior, and lateral views, X 3, USNM 167210b.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 12

CAROLINITES, GLAPHURUS, N ILEUS, PERASPIS!, AND ILLAENUS
PLATE 13

[All illustrations are stereophotographs]

FIGURES 1-13. lllaenus cf. I. auriculatus Ross (p. 32).

I-3. Cranidium; dorsal anterior, and lateral views, X 3, USNM 167210c. 

USGS colln. D1973 CO.

4. Hypostome; ventral view, X 5, USNM 167210d. USGS colln. D1973 CO.

5. Pygidium; dorsal view, excavated to show extent of doublure, X 2,

USGS colln. D1973 CO. USNM 167210e. 

6-8. Pygidium; dorsal, posterior, and lateral views, X 2, USNM 167210f.

USGS colln. D2058 CO. 

9, 10. Free cheek; dorsal and lateral views, X 3, USNM 167210g. USGS

colln. D1973 CO.

II-13. Free cheek; dorsal, lateral, and anterior views, X 5, USNM

167210h. USGS colln. D2058 CO. 

14-19. lllaenus sp. b (p. 32).

USGS colln. D1988 CO. 

14-16. Cranidium; lateral, dorsal, and anterior views, X 6, USNM

16721la. 

17-19. Free cheek; dorsal, lateral, and anterior views, X 4, USNM

16721Ib.
PROFESSIONAL PAPER 685 PLATE 13

ILLAENUS
PLATE 14

[All illustrations are stereophotographs]

FIGURES 1-6. Illaenus sp. b (p. 32).

USGS colln. D1968 CO.

1-3. Cranidium; lateral, dorsal, and anterior views, X 1, USNM 167211c. 

4-6. Cranidium; dorsal, lateral, and anterior views, X 4, USNM 16721 Id. 

7-12. Illaenus sp. c (p. 33).

USGC colln. D1991 CO, X 1.

7-9. Cranidium; dorsal, lateral, and anterior views, USNM 167212a. 

10-12. Cranidium; dorsal, lateral, and anterior views, USNM 167212b. 

13-15. Illaenus sp. d (p.. 33).

USGS colln. "D1973 CO.

Pygidium; dorsal, lateral, and posterior views, X 1, USNM 167213. 

16. Illaenus sp. e (p. 33).

USGS colln. D1968 CO.

Pygidium; dorsal view, partially excavated, X 2, USNM 167214. 

17-22. Illaenus sp. f (p. 33).

USGS colln. D1968 CO, X 4. 

17, 18, 20. Free cheek, right; dorsal, anterior, and lateral views, USNM

167215a. 

19, 21, 22. Free cheek, badly damaged, left; dorsal, anterior, and lateral

views, USNM 1672l5b. 

23-25. Illaenus cf. /. auriculatus Ross (p. 32).

USGS colln. D1968 CO, Cranidium; dorsal, anterior, and lateral views, 

X 2, USNM 1672101. This Cranidium is associated with free cheeks 

designated Illaenus sp. f.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 14

ILLAENUS AND ILLAENUS1
PLATE 15

[All illustrations are stereophotographs]

FIGURES 1-9. Harpillaenus sp. (p. 34).

USGS colln. D1968 CO.

1-3. Cranidium; dorsal, anterior, and lateral views, X 3, USNM 167216a. 

4-6. Cranidium; lateral, dorsal, and anterior views, X 2, USNM 167216b. 

7-9. Free cheek; dorsal, lateral, and anterior views, X 5, USNM 167216c. 

10-12. Bathyurellus feitleri (Holliday) (p. 34).

Pygidium; dorsal, posterior, and lateral views, X 1, USGS colln. D1994 CO.

USNM 167217. 

13-16, 20. Bathyurellus sp. 4 (p. 35).

USGS colln. D1991 CO.

13-15. Cranidium; dorsal, lateral, and anterior views, X 2, USNM 167219a. 

16. Same specimen enlarged to show surface ornamentation, X 5, USNM

167219a.

20. Pygidium; dorsal view, X 1, USNM 167219b. 

17-19. Bathyurellus sp. 3 (p. 35).

USGS colln. D1966 CO. 

Cranidium; dorsal, anterior, and lateral views, X 1, USNM 167218.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 15

HARPILLAENUS AND BATHYURELLUS
PLATE 16

[All illustrations are stereophotographs]

FIGURES 1-6. Raymondites? sp. (p. 35).

USGS colln. D2052 CO.

1-3. Pygidium; dorsal, posterior, and lateral views, X 1, TJSNM 167220a, 

4-6. Pygidium; lateral, dorsal, and posterior views, X 5, TJSNM 167220b. 

7, 8. Selenoharpes sp. (p. 36).

TJSGS colln. D1968 CO.

7. Latex cast of partial cephalon; dorsal view, X 3, TJSNM 167221b.

8. Cephalon, damaged; left side only, X 4, TJSNM 16722la, 

9-15. Endymiunia cf. E. meeki (Billings) (p. 37).

TJSGS colln. D1968 CO, X 4.

9-11. Cranidium; dorsal, lateral, and anterior views, TJSNM 167223a. 

12-14. Cranidium; dorsal, lateral, and anterior views, TJSNM 167223b. 

15. Cranidium; dorsal view, TJSNM 167223c.

16. Proetid pygidium (p. 36).

USGS colln. D2052 CO. 

Dorsal view, X 10, TJSNM 167222.

17. Lehua aff. L. argus Whittington (p. 37).

USGS colln. D1991 CO. 

Cephalon, damaged; dorsal view, X 1, USNM 167224.

18. Endymionia cf. E. meeki (Billings) (p. 37).

USGS colln. D1973 CO.

Cranidium, immature; dorsal view, X 10, USNM 167225. 

19-25. Pliomerops sp. (p. 37, 38).

19-21. Pygidium; dorsal, posterior, and lateral views, X 1.5, USNM

167226b. USGS colln. D2051 CO. 

22-24. Cranidium; dorsal, anterior, and lateral views, X 1.5., USNM

167226a, USGS colln. D2051 CO. 

25. Pygidium; dorsal view, X 1, USNM 167227.

USGS colln. D1968 CO.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 16

RAYMONDITES1, SELENOHARPES, ENDYMIONIA, PROETID, 

LEHUA, AND PLIOMEROPS
PLATE 17

[All illustrations are stereophotographs]

FIGURES 1-16. Kawina wilsoni Ross, n. sp. (p. 38).

1-3. Cranidium, holotype; dorsal, anterior, and lateral views, X 3, USNM 

167228a. USGS colln. D1968 CO.

4. Pygidium, paratype; dorsal view, X 3, USNM 167228b. USGS colln. 

D1968 CO.

5. 6, 8. Cranidium, paratype; dorsal, lateral, and anterior views, X 2,

USNM 167228c. USGS colln. D1968 CO. 

7, 9, 10. Cranidium, paratype; anterior, dorsal, and lateral views, X 2,

USNM 167228d. USGS colln. D1968 CO.

11. Pygidium, paratype; dorsal view, X 5. Latex cast of damaged specimen. USNM 167228f. USGS colln. D1973 CO.

12. 13, 16. Cranidium, paratype; dorsal, lateral and anterior views, X 1, 

USNM 167228e. USGS colln. D1968 CO.

14. Pygidium, paratype; dorsal view, X 5, USNM USGS colln. D1973 

CO. USNM 167228g.

15. Pygidium, paratype; dorsal view, X 2, USNM 167228h. USGS colln.

D1966 CO. 

17-20. Xystocrania pyriformis Ross, n. sp. (p. 39).

USGS colln. D1968 CC. 

Cranidium, holotype; dorsal, anterior, ventral, and lateral views, X 2,

USNM 167229. 

21-25. Heliomera cf. H. albata Whittington (p. 40).

USGS colln. D1968 CO. X 5.

21, 22. Cranidium; dorsal and lateral views, USNM 167230a. 

23-25. Cranidium; anterior, lateral, and dorsal viewts, USNM 167230b. 

26. Miracybele sp. 1 (p. 40).

USGS colln. D1971 CO. 

Cranidium; dorsal view, X 3, USNM 167231.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE 17

KAWINA, XYSTOCRANIA, HELIOMERA, AND MIRACYBELE
PLATE 18

[All illustrations are stereophotographs]

FIGURES 1-8. Apatolichas cf. A. jukesi (Billings) (p. 41).

USGS colln. D1968 CO.

1, 2. Cranidium; dorsal and anterior views, X 4, USNM 167232a. 

3-5. Cranidium; dorsal, anterior, and lateral views, X 4, USNM 167232b. 

6-8. Cranidium; dorsal, anterior, and lateral views, X 3, USNM 167232c. 

9. Undetermined pygidium 1 (p. 41).

USGS colln. D1973 CO. 

Dorsal view, X 6, USNM 167233. 

10-12. Undetermined pygidium 2 (p. 41). 

USGS colln. D1973 CO.

10. Dorsal view, X 1, USNM 167234a.

11. Dorsal view, X 1, USNM 167234b.

12. Dorsal view, X 4, USNM 167234c.

13. Undetermined pygidium No. 3 (not described).

USGS colln. D1970 CO. 

Dorsal view, X 3, USNM 167235.

14. Eopteria sp. (not described). 

USGS colln. D1990 CO. 

Lateral view, X 3, USNM 167236.

15. Undetermined edrioasteroid, X 3, USNM 167237.

USGS Colln. D1990 CO. (not described). 

16-20. Idiostrophia valdari Ross, n. sp. (p. 25).

USGS colln. D1968 CO.

Complete shell, holotype; views of exterior of brachial valve, exterior of 

pedicle valve, right side, anterior, and posterior, X 6, USNM 167191.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 685 PLATE IB

APATOLICHAS, UNDETERMINED PYGIDIA, EOPTERIA, 

UNDETERMINED EDRIOASTEROID, AND IDIOSTROPHIA