Nonmarine Mollusks of 

Late Cretaceous Age 

From Wyoming, Utah 

and Colorado

GEOLOGICAL SURVEY PROFESSIONAL PAPER 254-B
Nonmarine Mollusks of 

Late Cretaceous Age 

From Wyoming, Utah 

and Colorado

By TENG-CHIEN YEN

A SHORTER CONTRIBUTION TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 254-B

Part I: A fauna from western Wyoming 

Part 2: Faunas from eastern Utah and 

western Colorado

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1954
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

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

Washington 25, D. C. - Price 60 cents (paper cover)
CONTENTS

Page

Part 1. A fauna from western Wyoming.____________________________________________-_._____-----___..---_-------_ 45

Abstract--_-__-_______________________-___-_______________________--_-__-__--_--_-----------_-----_ 45

Introduction._________________________--__________________________-_-_-___-____---------------.----- 45

Localities at which mollusks were collected-_______________________-_-_-_-__-__--__--------_---_-_------ 45

Geographic and ecologic interpretations— _-_______________________..___-__..-________---_---_-_--_--_----. 46

Distribution of characteristic species.__________________________________________________________________ J8

Age of the sequence near Cokeville..___-----__________________-__--_--__.--__--_-_--------_--_------ -- 49

Systematic descriptions.___________________________________________-___..--__-____--_--_-_---_-__..---- 50

References cited_______________________-_-__________________-__-_--______-____-_-----_----___--_--__ 59

Part 2. Faunas from eastern Utah and western Colorado.________-________________--_____________--____-_-_--___--_ 50

Abstract.._ ________________________________________________________________________________________ 59

Introduction _______________________________________________________________________________________ 5!)

Collection localities and their molluscan assemblages.___________________________________________________ 59

Systematic descriptions.._._--__-_-----_--__-.___________-._--_.--_____-____-______-___-_--_--_-____- 61

References cited.___________________________________________________________________________________ 64

Index.._____________-_______-_-_-_-____..__________.____._.-________-_.._--_____.-_____-_-__._--_.________.-_ 65

ILLUSTRATIONS

PLATE 17. Upper Cretaceous nonmarine mollusks from Wyoming. ___________________ _______________________ Following index

18, 19. Upper Cretaceous nonmarine mollusks from Utah and Colorado.__________________________________ Following index

in

NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH,

AND COLORADO

By TENG-CHIEN YEN 

PART 1: A FAUNA FROM WESTERN WYOMING

ABSTRACT

A series of shales and limestones is exposed in the vicinity 

of Cokeville, Wyo., which yields a rich molluscan fauna of 

nonmarine habitat. The molluscan fauna consists of species of 

pelecypods: Ostrea, Brachydontes, Corbula, CorbicuJa and Unio; 

and of gastropods: Mesoneritina, "HeHcina", Viripams, Campelotna, Liopla<codes, Valvata, Mesocochliopa, Parateinostoma, 

Parhydrobia, Pyrgulifera, PachychUoides, Zaptychius, Melampoides, RJiytophonts, Pliysa, Lymnaea, Gyrauhis, and Anisopsis. 

The lower part of the sequence contains a few species in common with the strata of the Bear River, together with several 

new species congeneric with those of that formation. The upper 

part yields fewer species in common with the Bear River, but 

more forms resembling closely those of the overlying deposits. 

One new genus and 16 new species and subspecies are described.

INTRODUCTION

The succession and differentiation of molluscan 

species during geologic time are well demonstrated by 

fossils collected in sequences of Cretaceous units within 

an area about 80 miles long near the western margin of 

Wyoming. The fossil contents are rich, adequate stratigraphic data are available, and, most important, the 

general habitat conditions are nearly uniform and 

do not seriously affect the faunal distribution.

These fossil-bearing zones are represented by beds 

of the Bear River formation exposed in the vicinity of 

Evanston, and by an unnamed sequence of f ossilif erous 

limestones and shales exposed within 20 miles of Cokeville. The unnamed sequence, provisionally called Unit 

C by Rubey (1950), is the chief basis of the present 

study.

This richly fossiliferous series of strata occupies a 

position overlying and underlying thick sequences of 

essentially noiifossiliferous variegated shales. The 

fossiliferous sequence has a maximum thickness of about 

2,500 feet near Cokeville, but thins northward to about 

450 feet near Auburn, Wyo. The variegated shales 

above and below the series increase in thickness in the 

opposite direction, from several hundred feet in the 

south to several thousand feet in the north.

Most of the fossiliferous rocks studied in the present 

paper are exposed within or near the Cokeville quadrangle, which was mapped by W. W. Rubey of the U. IS. 

Geological Survey. To him I am very much indebted 

for his generosity in supplying field information, including his original data on the thickness and lateral 

relations of the rock units.

Some fossil specimens used in the present work are 

from the collections of U. S. Geological Survey, and 

others were collected by the author in the summers of 

1949 and 1950. All are preserved in the paleontological 

collections of the U. S. National Museum.

The author greatly appreciates the grant received 

from the Office of Naval Research to carry on the present research. The work is conducted under ONR contract N9-onr-92601 with the Smithsonian Institution, 

Washington, D. C. To the authorities of the Smithsonian Institution, I am also grateful for their business 

management of the contract.

LOCALITIES AT WHICH MOLLUSKS WERE COLLECTED

The 12 localities treated in this work are assigned to 

three stratigraphic divisions, each of which contains a 

number of molluscan species. The distribution of the 

nonmarine species is given in the table on page 46.

Division I. The lowest and southernmost sequence 

chosen for comparison here is the Bear River formation 

in and near its type locality. Collections were made at 

two places, at several levels within the formation. 

These collections represent the Bear River inolluscaii 

fauna as it is now known and they include many more 

species than were listed by C. A. White in 1895.

Locality 11—NE^SW^i sec. 29, T. 14 N., R. 119 W., at the 

"Fossil Cut," in southeast of Evanston, Uinta County, Wyo. 

It is about 45 miles south-southeast of Sage Junction.

Locality 12—SE%SB^4 sec. 1, T. 16 N., R. 121 W., at the Sholl 

Hollow, about 8 miles north of Evanston, Wyo. It is about 18 

miles northwest of locality 11.

Division 2. The intermediate sequence, well exposed 

for a number of miles north to south of Cokeville, w^s 

called Unit C by Rubey (1950). The exposures in the 

following six localities yielded nonmarine mollusl'S. 

Localities 9 and 10 may represent the lower part of

45
46 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

the sequence, which yield a slightly different molluscan 

fauna as shown under column A of division 2 in the 

table.

Locality 5—SE%SB% sec. 17, T. 22 N., B. 119 W., about 2 

miles south of Antelope Creek, Lincoln County, Wyo. It is 5 

miles north of and about 500 feet stratigraphically below the bed 

at locality 4.

Locality 6—SE%SW}4 sec. 7, T. 26 N., B. 118 W., on north 

side near the mouth of the third Creek, Lincoln County, Wyo. 

It is 26 miles north of and about 1,000 to 1,100 feet stratigraphically lower than the bed at locality 5.

Locality 7—Near center sec. 32, T. 28 N., B. 118 W., Lincoln 

County, Wyo. It is 9 miles north of and about 100 feet stratigraphically below the bed at locality 6.

Locality 8—SE%SW% sec. 25, T. 28 N., B. 119 W., Graham 

coal mine, about 41 miles north of Sage Junction, Lincoln 

County, Wyo. It is 2 miles WNW of and 200 stratigraphically 

lower than the bed at locality 7.

Locality 9—SW%SB% sec. 7, T. 26 N., B. 118 W., east of the 

Muddy Creek, opposite mouth of Third Creek, Lincoln Coiinty, 

Wyo. It is in the same section and about 550 feet below the 

bed at locality 6.

Locality 10—SW%SW% sec. 36, T. 25 N., B. 119 W., on 

north side of Smiths Fork, 2 miles northeast of Cokeville, Lincoln County, Wyo. It is 11 miles south of and at approximately 

the same stratigraphic position as the bed at locality 9, and 15 

miles north of and approximately 1,600 feet stratigraphically 

lower than the bed at locality 5.

Division 3. The upper sequence, and provisionally 

called Unit E by Kubey (1950), consists of about 3,400 

feet of shales, limestones, and siltstones, locally interbedded with several bands of porcellanites. These 

strata crop out more or less continuously from near the 

head of Thomas Fork, 20 miles north of Cokeville, 

southward to the east side of the Crawford Mountains, 

25 miles south of Cokeville. In the northern half of its 

area, this sequence overlies red and variegated siltstones 

which in turn overlie the beds of division 2. Richly f ossilif erous beds occur at several levels within this division 

3 sequence, and the faunas indicate that the sediments 

were mainly of continental origin, with a few thin 

marine intercalations. The exposures of the following 

four localities yield rich faunas representing the nonmarine f acies of the sequence.

Locality 1—West-central sec. 7, T. 21 N., B. 119 W., road cut 

at Sage Junction, Lincoln County, Wyo. (Yen 1952a, p. 349.)

Locality 2—Near center sec. 7, T. 21 N., R. 119 W., near Sage 

Junction, Lincoln County, Wyo. It is about 700 feet stratigraphically lower than the bed at locality 1. (Yen, 1952a, 

p. 344.)

Locality 3—Near center sec. 17, T. 22 N., B. 119 W., 2 miles 

south of Antelope Creek and about % of a mile east of U. S. 

Highway 30 N, Lincoln County, Wyo. It is 5 miles north of 

and 300 feet stratigraphically lower than the bed at locality 2. 

(Yen, 1951, p. 11.)

Locality 4—SE% sec. 7, T. 21 N., B. 119 W., old coal mine 

near Sage Junction, Lincoln County, Wyo. It is in the same 

section and about 1,400 feet stratigraphically lower than the 

bed in locality 2. (Yen, 1952c, p. 1317.)

Stratigraphic distribution of molluscan faunas

Gastropoda, Prosobranchiata 

Neritidae

Helicinidae

Cyclophoridae

Viviparidae

L. endlichi.....-.-—. ....................

Valvatidae

Amnicolidae

P.lataitia................. ...............

TrocMsfira wyomingensis, n. gen., n. sp__ 

Pleuroceritidae

Ellobiidae

R. meeki ..... ............. .... ....... ....

Physidae

Lymnaeidae

Planorbidae

Pelecypoda 

Ostraeidae

Mytilidae

Corbulidae

Corbiculidae

Unionidae

17. belliplicaJtus ......... ...... ... ... ......

Division

1

X 

X

X

X 

X

X

X

X? 

X 

X

X

X

X

X

X 

X 

X

X 

X 

X 

X

X

X? 

X

X 

X

X 

X

X

X 

X

2

A

X

X 

X

X

X 

X 

X

X

X

X 

X

X

X 

X

B

X 

X

X

X

X 

X 

X 

X

X

X 

X?

X 

X

X 

X

X 

X

X?

X 

X

X

X 

X 

X

X 

X 

X

X

X 

X

3

X 

X

X

X

X 

X 

X

X

X

X

X 

X

X 

X

X

GEOGRAPHIC AND ECOLOGIC INTERPRETATIONS

The molluscan faunas of the three major divisions 

reveal that southwestern Wyoming in the beginning of 

Late Cretaceous time (Cenomanian)—our division 1— 

probably consisted of an estuarine area banked by low 

coastal land in the vicinity of Evanston and adjacent to 

a sea that lay to the southeast. Such estuarine conditions prevailed farther north in the Cokeville- area at
A FAUNA FROM WESTERN WYOMING

a later time (division 2), and brief marine invasions extended as far north as Antelope Creek, 12 miles south 

of Ookeville. This estuarine area changed gradually 

and became lowland on the coast through most of the 

time when division 3 was deposited. Probably woodland was plentiful, rivers and small lakes were present, 

with mountains and possibly volcanoes in the uplands 

to the west. There is evidence that the sea advanced 

northward and westward to Sage Junction (20 miles 

south of Cokeville) in the early part of this time, but 

such invasions were of brief duration and they had no 

noticeable effect on the distribution of molluscan fauna 

of the low coastal land nearby.

However, ecological conditions, as revealed by a study 

of molluscan faunas, seem to have formed somewhat 

more complicated patterns.

Division 1 is here represented by the Bear River formation. Both drifted assemblages and habitat assemblages of the molluscan faunas are common in these 

richly f ossilif erous beds. Habitat assemblages are emphasized in the present study because drifted assemblages are much less significant.

The Bear River formation is made up of a series of 

beds that indicate frequent oscillation between freshwater and brackish-water conditions. A detailed investigation of the paleoecology of the entire formation 

is beyond the scope of the present paper, and I confine 

my interpretation merely to a single band of soft gray 

calcareous shale, located in the lower third of the sequence exposed at the "Fossil Cut," which is overlain 

and underlain by dark shales containing coquinalike 

beds of Corbula, C&rbicula, and Pyrgulijera. The molluscan elements are so abundant as almost to be rockforming, and the contents of both shale beds clearly 

indicate drifted assemblages of estuarine forms.

The soft gray calcareous shale yields an assemblage 

of molluscan species that is rich both in varieties and 

individuals. It contains the following species:

Mesoneritina naticiformis 

M. stantoni 

"Helicina" cretacea 

Pseudarinla uniplica 

Viviparus couesi 

Campeloma macrospira 

Lioplacodes stachei 

L. s. attenuata 

Valvata praecursoris 

Mesocochliopa bearensis 

Parateinostoma altispirale 

Trochispira wyomingensis 

Pyrgulifera humerosa 

Pachi/chiloides macilenta 

Melatnpoides clarki 

Rhytophorus priscus 

Physa usitata 

Gyraulus sp. undet.

In addition to the above assemblage of gastropod" 

there are several imperfectly preserved specimens which 

are identified as species of Mesoglypterpes Yen, however, their definite specific status cannot be established 

on the specimens available at present. There are alro 

a few imperfect examples of Corbula engelmanni, and 

fragments of Unio belliplicatus, and traces of BracJivdontes. The oogonia of Charophycea are present in this 

soft gray calcareous shale deposit, but they are not 

abundant.

This assemblage is of fresh-water origin and is clearly 

one that might be expected in a natural community. 

Most of the species are represented by numerous ind; - 

viduals of both adult and younger stages; 12 of the 18 

species are aquatic prosobranchians, which are generally 

adapted to deeper water; the presence of 2 terrestrial 

species and 4 aquatic pulmonates, which are represented 

by far fewer individuals, may indicate an admixture of 

nearshore and land forms.

The theory that the fossil bed represents an original 

habitat area, where most of the above mentioned molluscan species lived and were buried, is supported by 

the mode of preservation of the shells. Compared with 

the mollusks found in the beds above and below, which 

are considered to be drifted assemblages, the shell remains in this bed are not so crowded as to be coquinalike, although they are numerous and most of them ar^ 

of smaller size. Large-shelled species such as Vivipan-s 

cousei and Campeloma macrospira are represented in 

the present collection by only 4 individuals of small 

size. It may be that the smaller shells are more readily 

buried in finer sediments at the bottom.

The components contained in this assemblage seem to 

indicate, further, that their habitat area was in tli 

lower part of the littoral zone in a more or less closed 

and quiet bay. On a gently sloping bottom, a rich 

growth of vegetation would flourish and soft mud would 

accumulate about the roots. These conditions would 

suit the living conditions of viviparoid and rissoid gastropods. Within this belt of littoral zone, the water 

was possibly about 20 to 30 feet deep, and probably 

saturated with calcium carbonate. Plenty of food and 

oxygen was available, and the temperature was nearly 

constant throughout the year. The vegetation had 

almost continuous growth, and the habitat was ertremely favorable for mollusks.

However, these conditions continued only a short thr^ 

before the environment changed back nearly to what it 

had been earlier. This is indicated by the overlying and 

underlying dark shales, which contain coquinalike assemblages. The bay was probably again open as it had 

been before, and the area was within the reach of high 

tide, which probably brought brackish-water forms in
48 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

quantity to be accumulated in this nearshore zone. At 

the same time, the movement of fresh water from inland 

streams became more rapid, and strong currents changed 

the kind of bottom sediments and destroyed the rich 

growth of vegetation, and therefore also the conditions 

favorable for the animal community.

Secondly, let us examine division 2, which is represented by the sequence exposed in the vicinity of Cokeville. This is an unnamed unit of 2,000 to 2,500 feet 

thickness. For the present purposes, a particular bed of 

dark argillaceous shale may be selected for comparison. 

This bed, which is within the upper part of the sequence, 

contains the following molluscan species, all of freshwater origin:

Unto vetustus 

Mesoneritina naticiformis 

M. stantoni

"Helicina" cokcvittensis 

Viviparus cokevillensis 

Campeloma cokevillenxis 

Lioplacodes staohei 

L. s. attentuata 

L. s. inflatus 

Valvata praecursoris 

Mesocochliopa cokerilletisis 

Parateinostoma, la tent is 

Pyrgidifera humerosa cokevillensis 

P. stantoni elongata 

PachychUoides macilenta 

P. m,. miniita 

Zaptychius haldemanni 

Physa usitata 

Physa cokeviUensis 

Physa globosa

This deposit yields a molluscan fauna similar in types 

to that previously described from division 1. Such 

similarity suggests that the paleoecological conditions 

were probably much the same. The presence of Unto 

vetu-stus and one more species of Lioplacodes indicate 

that the bottom was muddier and enabled these mollusks 

to survive. However, this assemblage contains a considerable number of congeneric species of Viviparus, 

Gam-peloma, Lioplacodes^ Mesoneritina, Parateinostoma, PyrguJifera, and Physa that are different from 

those in the soft gray calcareous shale of the Bear River 

formation. A comparison of the two assemblages indicates an evolutionary succession of the fauna, because 

only 6 species are common to both assemblages, and 

most of the species are different. These differences in 

the two faunas seem to reflect a difference in age, as that 

might be expected on purely stratigraphic evidence.

Thirdly, we may consider, as representative of division 3, a limestone bed exposed south of Leeds Creek, 

which occupies a stratigraphic position in the lower 

part of a 3,400-foot unit, at present unnamed but numbered L-5 in a recent publication (Yen, 1951, p. 11).

This fossiliferous bed yields the following assemblage 

of molluscan species:

Mesoneritina naticiformis 

M. stant&ni 

Lioplacodes stachei 

Valvata praecursoris 

Parateinostoma altispirale 

P. convexum 

P. contractum 

Parhydrobia cylindrica 

Gontobasis leedsensis 

Zaptychius cf. Z. haldemanni 

Rhytophorus cf. R. meeki 

Melampoides clarkii 

Anisopsis minutis 

Physa usitata 

Physa sp. undet. A 

Physa sp. undet. B

The variation of the above assemblage from those of 

the other two deposits seems to indicate a different habitat. However, all three habitats were undoubtedly fresh 

water and in the quiet littoral zone. More species of 

pulmonates and more numerous individuals, together 

with an abundance of rissoid gastropods, clearly imply 

shallower water or an inshore environment. These 

gastropods were associated with the aquatic plants of a 

lenitic or stillwater society, possibly of lacustrine origin. The two beds in divisions 1 and 2 have yielded 

broken shells of brackish-water species which suggests 

some marine connection, but no trace of such elements 

was found in the limestone bed of division 3; and probably the water here was entirely free of marine 

influence.

DISTRIBUTION OF CHARACTERISTIC SPECIES

The major sequences compared in the present study 

were included by geologists in earlier days in the Bear 

River formation. The conclusion was then sound 

enough, when collections had yielded many identical 

and seemingly identical species of mollusks from exposures within a distance of about 80 miles in southwestern Wyoming. Geological work in the western 

interior was then in its early stage and probably time 

did not permit detailed analysis and comparisc n of collections from such richly fossiliferous areas. A record 

of a few species in common, and in rocks of similar 

lithologic character, were generally take as sufficient 

evidence for an age assignment. Possibly differentiation of the faunas and of their environmental conditions 

was probably not then taken into serious consideration.

The foundation work was laid to which the present 

study is a supplement. On the basis of the molluscan 

species known at present, each of the three sequences 

has its own characteristic species. No doubt the number of such species may change with further studies
A FAUNA FROM WESTERN WYOMING 49

now in progress, but the differences among the three 

assemblages will remain as a fact not to be overlooked. 

Summarizing the species of each sequence, present records show 18 species common to and 32 species different 

between divisions 1 and 2; 8 species common to and 35 

species different between divisions 2 and 3. If we choose 

to emphasize only the characteristic species in each sequence, those not present in the other two, the differences are as follows:

Division 1, from the Bear River formation, yielded 

the following species not found in the other two 

sequences:

"Helieina" oretncea 

Vivipanis couesi 

Campeloma maerospira 

MesococMiopa bearensis 

Trocliispira wyominffensis 

Pyrgnlifera humerosa 

Pachychiloides cliry sail o idea 

Rhytophonis priscus 

R. meeki 

Lymnaea nitidula

Division 2, the sequence exposed in the vicinity of 

Cokeville, yielded the following characteristic species 

of mollusks:

"ffelicina" cokevillensis

Vivipanis cokevillensis

Campeloma cokevillensis

C. rubeyi

Lioplacodes stachei

L. s. in flatus

Mesocochliopa cokevillensis

Tortwtellina f" isoclina

Parateinostom-a latentis

Pyrgulifera humerosa cokevillensis

P. stantoni

P. s. elonffata

PacfiycMloid.es ookevillensis

P. macilenta minuta

"Auricula" neumayri

PJiysa cokevillensis

P. globosa

Division 3, the sequence exposed in the Leeds Creek 

area and near Sage Junction, contains the following 

species of gastropods which are not thus far known in 

the other two sequences:

Paratevnostoma convexum 

P. contractum 

Parhydrobia cylindrica 

Gowiobasis leedsensis 

PacJiychiloides turricula 

Anisopsis minutis

The difference between divisions 1 and 2 is clear. 

Most of the species are congeneric, and the differences 

are probably the result of evolutionary changes. Nearly 

one thousand specimens of Pyrgulifera humerosa, 

collected in and near the type locality of the Bear River

269438—53———2

formation, have been examined, and not a single specimen resembling P. stantoni has been found. Several 

hundred specimens of Pyrgulifera have been studied 

from collections made in the Cokeville area, and only 

P. stantoni and one variety of P. humerosa have been 

found in the lower part of the sequence, and of P. s. elongata in the upper part of the sequence. Moreover, four 

species of Pachychiloides occur in the Bear River, and 

one species and one subspecies are added to that genus 

in the upper part of the sequence in the Cokeville area. 

Moreover, the differences from divisions 2 and 3 are 

readily apparent, although the characteristic species in 

division 3 are not nearly so numerous as those in the 

other two divisions. The difference in habitat conditions must once more be stated in addition to the difference in species and in the size of the assemblages. Of 

course the entire sequence of division 3 has not been 

completely investigated, and additional data from f irther study may provide records that will reveal even 

greater differences.

AGE OF THE SEQUENCE NEAR COKEVILLE

In a recent paper (Yen, 1952 b, p. 761), I maintained 

and now still maintain that the Bear River formation 

was contemporary with the Cenomanian (Late Cretaceous) of standard European usage.

I have also related under previous headings of the 

present paper that the sequence exposed in the vicinity 

of Cokeville yields a molluscan assemblage very similar 

in kind and in ecological conditions to that of the Bear 

River formation. In examining all the known records, 

it is found that they have 18 species in common and 

32 species different. Most of the different species rre 

congeneric. The total number of species compared is 

aggregated from those collected at various levels in 

each sequence; that is, they are not the contents of any 

single fossil bed, such as that selected for purposes of 

the ecological interpretation just made. Moreover, 

Cokeville is only about 60 miles north of Evanston.

Available information indicates that the Bear River 

formation and the sequence exposed in the vicinity of 

Cokeville represent deposits of different ages. The 

Cokeville deposit does not seem to be a lateral extension of any part of the Bear River formation. Similar 

ecological conditions evidently produced similar kinds 

of molluscan assemblages, but they are considerably 

different in species. Such difference in species can most 

reasonably be explained by a difference in age, especially when the short distance between the two localities 

and the presence of a number of congeneric and closely 

related species is considered. However, the 18 species 

common to the two sequences seems to imply that th^y 

are not of greatly different ages.
50 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

A black ferruginous shale, which is exposed on Smiths 

Fork, 30 miles north of Cokeville at a stratigraphic position 2,100 feet below the base of division 2 beds, yields 

nonmarine mollusks that represent the top of the Lower 

Cretaceous in this area, as interpreted by me. This bed 

contains a few forerunners of the Bear River fauna, together with some Lower Cretaceous species. It seems 

logical to assume that the basal part of division 2 is 

probably contemporary with the upper part of the Bear 

River formation; that the major part of the division 2 

sequence is probably younger than the Bear River; and 

that during this time interval the new elements were 

evolved. However, the division 2 sequence is likely to 

be still within the Cenomanian stage (which constitutes 

the basal part of Upper Cretaceous) though possibly in 

its upper part.

SYSTEMATIC DESCRIPTIONS

GASTROPODA

Family NERITIDAE

Mesoneritina naticiformis (White), 1878

Plate 17, figure 24

Neritina naticiformis White, U. S. Geol. Survey Bull. 128, p. 49, 

pi. 6, figs. 10-12,1895; Mesoneritina naticiformis, Yea, U. S. 

Geol. Survey Prof. Paper 233-A, p. 14, pi. 2, fig. 2, 1951.

White's figures 10 and 11 were based on a specimen 

collected "20 miles north of Cokeville," which is probably the same as locality 8 of Division 2 mentioned in 

the present paper. His figure 12 was based on a specimen obtained near the mouth of Sulphur Creek of the 

Bear River formation. The Cokeville specimens show 

a laterally descending and somewhat dilated final part 

of the body whorl, but the Bear River specimens are 

more naticoid in outline. Additional specimens obtained from the two areas confirm such differences in 

shell features. However, because the forms of Neritinalike groups are known to be variable in shell features 

within specific limits they are treated here as one species. 

The specimens collected from Leeds Creek area resemble 

closely those from the Cokeville localities.

Figured specimen: USNM 108411.

Mesoneritina stantoni (White), 1895 

Plate 17, figure 23

Mesoneritina, stcmtoni, Yen, U. S. Geol. Survey Pro. Paper 233-A, 

p. 14, pi. 2, fig. 3, 1951.

This species and M. naticiformis were found in a soft 

gray calcareous shale in the Bear River formation and 

also at the localities of the Leeds Creek area. The type 

specimens were collected "20 miles north of Cokeville."

The single supra-peripherial carina seems to be a 

constant feature of the species and differentiates it from 

the associated M. naticiformis.

Figured specimen : USNM 108409.

Family HELICINIDAE 

"Helicina" cretacea Yen, n. sp.

Plate 17, figures 25-27

Shell of helicoid outline and small size, imperforate, 

having a moderately elevated spire and laterally descending body whorl. Whorls increasing moderately 

rapidly in size, scarcely convex and obtusely p,ngulated 

along the periphery. Apex obtuse and prominent, 

initial whorl rather smooth, and subsequent ones marked 

by distinct sharp and slightly curved riblines. Basal 

surface convex and bearing a similar kind of sculpture. 

Aperture subovate in outline. Curving riblines of 

growth probably indicate it was sinuated posteriorly. 

Umbilical callosity well developed.

Measurement (in millimeters) : Altitude of shell 3.0, width 

4.0; height of aperture 2.0, width 1.5; 4 whorls.

This species is characterized by its scarcely convex 

whorls, distinctly sharp riblines, and well-developed 

umbilical callosity. It resembles Helicina evar-stonensis 

(White), from the Evanston formation of Paleocene 

age, but it differs by its smaller size and ite distinct 

sculpture.

Holotype: USNM 108415; paratype: USNM 1084:6. 

"Helicina" cokevillensis, n. sp.

Plate 18, figures 5-7

Shell helicoid in outline and of small size, perforate 

in the young and imperforate in the adult, having a 

slightly elevated spire and laterally inflated boiy whorl. 

Whorls increasing rather rapidly in size, moderately 

convex and rounded at the periphery. Apex obtuse and 

prominent, initial whorl smooth and its subsequent ones 

bearing close and fine riblines. Basal surface moderately convex. Aperture subovate in outline and the 

unbilical callosity well thickened.

Measurements (in millimeters) : Altitude of shell 3.2, width 

5.5; height of aperture 2.0, width 3.0; 3y± whorls.

This species is readily separated from the preceding 

one by its large size, more convex whorls, more depressed 

spire, and finer sculpture.

Holotype: USNM 108417 ; paratype: USNM 10841?.

Family CYCLOPHORIDAE 

Fseudarinia uniplica Yen, n. sp.

Plate 17, figure 50

Shell sinistral, imperforate, subovate in outline, with 

elevated spire and narrowly dilated body whorl. Spire 

greater than the body whorl. WTiorls increase moderately rapidly in size, roundly convex and slightly 

shouldered below the suture. Aperture subovr.te in outline, descending in front, outer lip simple, parietal
A FAUNA FROM WESTERN WYOMING 51

margin thin but well defined, and columellar margin 

with twisted appearance at the lower end and bearing 

a well-developed plica.

Measurements (in millimeters) : Altitude of shell 2.1, width 

1.1; height of aperture 1.0, width 0.6; 4% whorls.

The species resembles Pseudarinia convexa Yen 

(1952, p. 352, pi. 1, fig. 21, 22, 24) in size and outline 

of shell, but it differs by the twisted appearance of its 

columellar margin and by bearing a well-developed 

plica on the inner lip.

This species is so far known only from the Bear 

Kiver formation, but congeneric species have been 

described from locality 2 of division 3.

Holotype: USNM 108419; paratypes: USNM 108420.

Family VIVIPAKIDAE

Viviparus couesi White, 1878

Plate 17, figure 1

Viviparus couesi White, U. S. Geol. and Geog. Survey Terr. 

Bull. 4, p. 717, 1878; U. S. Geol. Survey Bull 128, p. 59, pi. 

10, fig. 1, 1895.

White states (1895, p. 59) that this species was known 

only from the Bear Kiver formation near the mouth of 

Sulphur Creek and at 7 miles north of Evanston, and 

this still holds true. It is often found in association 

with Campeloma macrospira, but it differs from that 

species by its more ventricose outline of shell, more convex whorls and roundly curved lines of growth. The 

specimens in the present collection were obtained at the 

Shell Hollow, locality 12 of division 1.

Figured specimen: USNM 108421.

Viviparus coktvillensis Yen, n. sp. 

Plate 18, figure 8

Shell of moderate size for the genus, subovate in 

outline and apparently of thin shell substance, having 

a nearly mucronate apex, elevated spire, descending 

and moderately inflated body whorl; the spire is higher 

than the body whorl. Whorls increasing rather gradually in size, early ones gently and later ones more 

strongly convex. Surface marked by evenly and 

roundly curved lines of growth. Aperture pyriform, 

lip margin simple and thin, columellar margin slightly 

reflected. Umbilicus narrowly opened.

Measurements (in millimeters) : Altitude of shell 37.0, width 

23.2; height of aperture 15.6, width 13.0; 7 whorls.

It differs from the preceding species by its smaller 

size, with about same number of whorls, less convex 

whorls and less inflated body whorl.

Holotype: USNM 108426; paratypes: USNM 108427.

Campeloma macrospira (Meek), 1873

MelantJlo (Campeloma) macrospira Meek, U. S. Geol. and Geig. 

Survey Terr. Ann. Rept. for 1872, p. 487, 1873; U. S. Geol. 

Explor. 40th Par., Rept. v. 4, p. 179, pi. 17, figs. 17a b, 1877.

The type collections of the U. S. National Museum 

contain two lots for this species. A single specimen, 

which is marked as from the mouth of Sulphur Creek, 

has only a few early whorls preserved; another lot of 2 

specimens, recorded from the Bear River Valley, Wyo., 

but which I think were probably obtained from Shell 

Hollow 7 miles north of Evanston, because its matrix 

matches well with the examples I have collected from 

locality 12. This species is known only from the Be^r 

River formation.

Campeloma rubeyi Yen, n. sp. 

Plate 17, figure 3

Shell narrowly oblong and subfusiform in outline, 

having a highly elevated spire, and slightly oblique 

descending body whorl. Spire higher than the body 

whorl. Whorls increasing rapidly in size, coiling 

slightly obliquely in the later ones. Whorl surface 

gently convex and bearing fine and sinuous lines of 

growth. Aperture decidedly descending, ovately oblong in outline, somewhat produced at the base. Parietal 

margin well defined and moderately thickened.

Measurements (in millimeters) : Altitude of shell 46.0, width 

20.0; height of aperture 20.6, width 13.7; 6 whorls preserved 

(apical ones missing).

This species is readily distinguished from the preceding one by its more or less fusiform outline of shell, 

ovately oblong shape of aperture, and slightly obliquely 

coiling of the larger whorls.

Holotype: USNM 108424; paratypes: USNM 108425. 

Campeloma cokevillensis Yen, n. sp. 

Plate 17, figure 2

Shell broadly oblong in outline, having a conically 

elevated spire, descending and moderately inflated boiy 

whorL The spire is greater than the body whorl. 

Whorls increasing rather gradually in size, and coiling 

transversally and below the periphery of the preceding 

whorl. Whorl surface gently convex and bearing distinct sinuous lines of growth, which are clear indication 

of the presence of the characteristic.curvature of the 

outer lip margin. Aperture subovate in outline, p?.ristomal margin continuous if well preserved, and parietal wall thickened.

Measurements (in millimeters) : Altitude of shell 4216, width 

24.4; height of aperture 18.0, width 13.0; 6 whorls preserved 

(apical ones missing).
52 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

This species is easily differentiated from the preceding one by much broader outline of shell, less convex 

whorls and subovate aperture. It differs from Coumpelonia tnctcrospira by its smaller size, at least one whorl 

more, less convex whorls and its less broad outline of 

shell.

Holotype : USNM 108428; paratypes : USNM 108429. 

Lioplacodes stachei (White) 1895

Plate 17, figures 17, 20, 21

Lioplacodes starhei, Yen, U. S. Geol. Survey Prof. Paper 223-A, 

p. 14, pi. 2, figs. 4a-g, 1951.

This species seems to be common in the early Late 

Cretaceous formations in southwestern Wyoming. 

Average specimens found in the Bear River are smaller 

than those from the Cokeville and Leads Creek localities. The significance of this difference cannot be ascertained until the Bear River fauna is completely studied.

This species was assigned by White (1895, p. 58) to 

Charydrobia Stache, which constitutes a group of 

£fydrobia-\ike forms from the higher Upper Cretaceous 

rocks in the Balkans. However, the group of species 

found in southwestern Wyoming seems to resemble 

more closely in shape, size, and apertural features the 

genus Lioplacodes Meek, species of which are known 

from Lower Cretaceous to lower Tertiary rocks in the 

western interior.

Figured specimens : USNM 108430.

Lioplacodes stachei attenuata Yen, n. subsp. 

Plate 17, figure IS

This subspecies is readily separated from the typical 

form by its narrowly oblong outline, of shell, more 

highly elevated spire, and less inflated body whorl. 

These features are well shown in the young examples 

as well as in the fully matured stages and therefore it 

is considered to represent a distinct form, although it 

is obviously related to the typical form of the species.

Measurements (in millimeters) : Altitude of shell 14.5, width 

6.0; height of aperture 5.7, width 3.1; 7 whorls.

Measurements (in millimeters) of a figured specimen of 

Lioplacodes stachei: Altitude of shell 14.5, width 6.8; height of 

aperture 5.0, width 3.7; 7 whorls.

Holotype: USNM 108437; paratypes : USNM 108438. 

Lioplacodes stachei inflatus Yen, n. subsp. 

Plate 17, figure 19

This subspecies is characterized by its broadly subovate outline of shell, with early whorls increasing 

gradually and later ones more rapidly in size, coiiically 

elevated spire and dilated body whorl. These features

are well shown in both young and adult stages and distinguish this form from L. s. attenuata.

Measurements (in millimeters) : Altitude of shell 10.7, width 

6.0; height of aperture 5.0, width 3.7; 7 whorls. 

Holotype: USNM 108440; paratypes : USNM 108441.

Lioplacodes endlichi (White), 1878

'/OHj'ofeasi's endliclii White, U. S. Geol. and Geog. Survey Terr. 

Bull. 4, p. 716, 1878; Lioplax? endliclii, White, U. S. Geol. 

Survey Bull. 128, p. 60, pi. 10, figs. 4, 5, 1895.

The type lot contains four specimens, three of which 

represent this species; and a fourth one (fig. 6) of White, 

with only a few early whorls preserved, does not belong 

to the species. White noted that this species ir distinct 

from all other species of the Bear River fauna, but I 

have not yet been able to find identical speciiimis from 

the type locality.

Family VALVATIDAE 

Valvata praecursoris (White), 1895

Yalvata praecursoris, Yen, U. S. Geol. Survey Prof. Paper 233-A, 

p. 14, pi. 2, figs, la-g, 1951.

This species is common in the Upper Cretaceous sequences in southwestern Wyoming. The present collection contains a series of developmental stages that show 

the descending coiling of the later whorls and the deepening of the umbilicus. In some beds this secies is 

associated with a species of Gymiilus, but is easily distinguished by its tubular form of the whorls, circular 

aperture with continuous peristome, wide and deep umbilicus.

There are four specimens in the type lot, which were 

obtained 20 miles north of Cokeville. None of the four 

closely resembles a species of Crymulus.

Family AMNICOLIDAE

Mesocochliopa bearensis Yen, n. sp.

Plate 17, figures 36-38

Shell small, subglobose in outline, with elevated spire 

and narrowly inflated body whorl. Whorls increasing 

gradually in size in early ones and more rapidly in later 

ones, and separated by impressed suture. Whorl surface gently convex, but roundly convex on the base. 

Aperture subovate in outline, outer lip simple, parietal 

wall thin but defined, columellar margin short and bearing a prominent plica in a middle position on inner lip 

margin. Plica lying obliquely upward oil the inner 

wall. Umbilicus deep and widely open.

Measurements (in millimeters) : Altitude of shell 3.0, width 

2.8; height of aperture 1.5, width 1.6; 4% whorls. Altitude 

of shell 2.1; width 2.1; height of aperture 1.2, wHth 1.2; 4 

whorls.
A FAUNA FROM WESTERN WYOMING 53

This species is readily distinguished from Mesocochliopa cretacea Yen (1951, p. 5, pi. 1, figs. 6a-c) by its 

larger size and fewer whorls and its oblique and higher 

plica.

Holotype: USNM 108445; paratypes: USNM 108446.

Mesoeoehliopa eokevillensis Yen, n. sp. 

Plate 17, figures 34, 35

Shell small, and subglobose outline, with highly elevated spire and dilated body whorl. Spire higher than 

body whorl. Whorls increasing rapidly in size, slightly 

shouldered below the suture. Surface roundly convex 

and bearing fine lines of growth. Aperture descending, ovate in outline; outer lip thin and simple, inner 

lip bearing a plica at the junction of parietal and 

columellar margins. Umbilicus deep and widely open.

Measurements (in millimeters) : Altitude of shell 3.2, width 

2.7; height of aperture 1.5, width 1.5; 5% whorls.

Holotype: USNM 108447; paratypes : USNM 108448. 

"Tornatellina?" isoelina (White), 1895

Tornatellinaf isoelina White, U. S. Geol. Survey Bull. 128, p. 48, 

pi. 4, figs. -14, 15, 1895.

This is another rare species found only at the type 

locality, 20 miles north of Cokeville. The shape, size, 

and elevation of spire are much different from those of 

Mesocochliopa Yen, although the parietal wall is similarly dentated. More specimens are needed to determine the variation of its shell features and permit a 

generic assignment, although it seems certain that the 

species does not belong to Tornatellina Beck, which is a 

genus of Recent terrestrial gastropods distributed 

through the Pacific islands.

Parateinostoma altispirale Yen, 1951 

Plate 17, figure 22

Parateinostoma altispirale Yen, U. S. Geol. Survey Prof. Paper 

233-A, pi. 2, figs. 5a-d, 19&L

The specimens obtained in the Bear River formation 

at Fossil Cut (locality 11) agree well with this species, 

which was originally described from the Leeds Creek 

area north of Sage Junction. So far it has not been 

found at the Cokeville localities, where congeneric 

species are not uncommon. Its absence from the present 

record is probably due to incompleteness of collecting.

Figured specimen: USNM 108449.

Parateinostoma convexum Yen, 1951

Parateinostoma convexum Yen, U. S. Geol. Survey Prof. Paper 

233-A, p. 15, pi. 2, figs. 63a-c, 1951.

This species is known at present only from the beds 

exposed in the Leeds Creek area.

Parateinostoma contractum Yen, 1951

Parateinostoma, oontractum Yen, U. S. Geol. Survey Prof. Paper 

233-A, p. 15, pi. 2, figs. 7a-c, 1951.

This species is known only from the Leeds Creek area. 

Both this and the preceding species seem to be related 

to P. latentis (White), but they are decidedly different 

from each other.

This genus has been recorded only from the lower 

Upper Cretaceous rocks of southwestern Wyoming.

Parateinostoma latentis (White), 1895

Bythinella latentis White, U. S. Geol. Survey Bull. 128, p. 58, pi. 

10, figs. 10, 11, 1895.

The type specimens were collected 20 miles north of 

Cokeville.

This species differs from P. contractum (Yen, 1951, 

p. 15), but they are congeneric. Specimens from loc?lity 8 of division 2, show the unexpanded outer lip 

margin and less inflated body whorl.

Parateinostoma occulta (White), 1895

HydrobM occulta White, U. S. Geol. Survey Bull. 128, p. 57, pi. 

10, figs. 12, 13, 1895.

This species also was known only from "20 miles 

north of Cokeville," and I have found no additional 

specimens in more recent collections. Examination of 

the type specimens of this species and the preceding one 

reveals no reason for their generic separation, although 

P. occulta has a slightly more slender outline of shell 

and more convex whorls.

Parhydrobia cylindrica Yen, 1951

Parliydrobia cylindrica Yen, U. S. Geol. Survey Prof. Paper 

233-A, p. 15, pi. 2, figs. 8a-b, 1951.

This species is known only from its type locality, that 

is, locality 3 of division 3. It is a very striking form 

and may represent a distinct genus, but the available 

specimens do not justfy such a description.

Trochispira Yen, new genus

Shell more or less trochoid in outline, having elevated 

spire and inflated body whorl; whorls few, bearirg 

sculpture and increasing rapidly in size, coiling with 

the suture more or less along the periphery of the preceding whorl; aperture pyriform, descending, peri?- 

tomal margin more or less continuous and thickened; 

umbilicus more or less open but not deep.

Genotype: Trochispira wyomingensis Yen, 11. sp.

Trochispira wyomingensis Yen, n. sp.

Plate 17, figures 39-44

Shell trochoid in outline, small, with acutely elevated 

spire and laterally inflated body whorl. Spire about
54 •NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

equal in height to the body whorl. Whorls increasing 

rapidly in size, apex elevated and prominent, early 

whorls gently convex and later ones obtusely shouldered, bearing a set of 3 to 4 distinct spiral ridges on 

and below the periphery; basal surface slightly convex 

and appearing to be smooth. Aperture descending, 

ovately pyriform in outline; outer lip slightly angulated above, inner lip arched in the middle, parietal 

margin well defined, and columella somewhat oblique. 

Umbilicus narrowly open but not deep.

Measurements (in millimeters) : Altitude of shell 4.0, width 

3.8; height of aperture 2.1, width 2.1; 4 l/± whorls.

This species is characterized by its small size, trochoid 

outline of shell, and the few but distinct spiral ridges. 

The younger individuals have the umbilicus more widely 

open but not deep.

This species has so far been found only at locality 11 

of the Bear Biver formation where it was found in 

association with species of Mesoneritina, Viviparus, 

Campeloma, Lioplacodes, Valvata, MesocochUopa, 

Physa, Gyraulus, etc.

Holotype: USNM 108452 ; paratypes : USMN 108453.

Family PLEUBOCEBATIDAE 

Goniobasis leedsensis Yen, 1951

Goniobasi leedsensis Yen, U. S. Geol. Survey Prof. Paper 233-A, 

p. 16, pi. 2, figs. 9a-3, 1951.

This species has been so far recorded only from the 

localities of division 3, where it occurs abundantly in 

impure limestone beds. The shell features are very distinct and resemble those of some species of Melanoides. 

Its existence in a true fresh-water habitat seems to be 

well demonstrated by its association with other freshwater molluscan species and the complete lack of admixture of either brackish-water species or their fragmentary shells.

Pyrgulifera humerosa (Meek), 1860 

Plate 17, figures 12, 13

Melania humerosa Meek, Acad. Nat. Sci. Phila. Proc., v. 12, p. 

313, 1860; Pyrffulifera humerosa White, U. S. Geol. Survey 

Bull. 128, p. 55, pi. 8, figs. 1-3.

This typical form of the species has been recorded 

from the Bear River at localities 11 and 12. It has 

been found at several levels within the formation and 

its occurrence is most abundant. A preliminary field 

investigation shows that some varieties of this species 

were evolved at the times of deposition. However, a 

monographic study is probably the only means of working out the problem, interesting and important as may 

it be, but that is not within the scope of the present work.

Figured specimens: USNM 108454.

Pygulifera humerosa cokevillensis Yen, n. subsr 

Plate 18, figure 1

This subspecies differs from the typical form of the 

species by its much smaller size, finer and more closely 

spaced nodular constructions along the shoulder. This 

form lias been found only at locality 10 in lower part of 

division 2, in association with the following species and 

another larger but unnamed variety of P. hvmerosa.

Pyrgulifera stantoni White, 1895 

Plate 17, figures 14, 15

Pyrffulifera stantoni White, U. S. Geol. Survey Bull. 128, p. 57, 

pi. 9, figs. 1-3, 1895.

This species, as White has already pointed ou% differs 

from P. humerosa by its greater elongation and other 

features. He notes also that this species and some 

varieties of P. hutn^rosa were collected by Stp.nton in 

the Cokeville area. My investigations indicate that the 

typical form of P. humerosa seems to be found only in 

the strata exposed in vicinity of Evanston.

Available collections, including White's material, do 

not contain typical P. humerosa marked with a Cokeville locality, nor P. Stanford in the Bear River formation. The type lot of P. stantoni is marked "T% o Bear 

River, Cokeville," and the very young specimer figured 

by White is labelled as coming from 20 miles north of 

Cokeville. This very young example is very different 

from the young specimens of P. humerosa I lave collected from locality 11 of the Bear River formation.

Figured specimens : USNM 108456.

Fyrgulifera stantoni elongata Yen, n. subsp. 

Plate 17, figure 16; plate 18, figure 2

Shell elongately subfusiform in outline, imp^rforate, 

having an acutely turrited spire and narrowly inflated 

and descending body whorl. Whorls increasing rapidly 

in size, apical ones roundly convex and subsequent ones 

shouldered above. The shoulder is obtusely argulated. 

Surf acf smooth on the early whorls and bearing rib and 

spiral} nes on later ones. The rib lines are stror ger than 

the spiral lines, and they are in intersection over the 

surface of the whorls except on base of the body whorl. 

Aperture subovate, somewhat produced and slightly 

sinuous on the basal margin.

Measurements (in millimeters) : Altitude of shell 18.0, width 

7.0; height of aperture 7.5, width 5.0; 5 preserved whorls 

(apical part missing).

This subspecies has been found at both localities 6 and 

8 of division 2. At locality 8, it is represented mostly 

by young specimens, and at locality 6, it was found in 

association with varieties of P. stantoni that were unfortunately very much distorted and cannot be used for
A FAUNA FROM WESTERN WYOMING

definite identifications. This subspecies differs from the 

typical form by its much smaller size, more elongate 

outline of shell, and less prominent sculpture.

Holotype: USNM 108459; paratypes: USNM 108460. 

Pachychiloides cleburni (White), 1895

Plate 17, figures 4, 5

Goniobasis cleburni White in Powell's Kept. Geol. Uinta Mts., 

p. 122, 1876; Pachymelania cleburni, White, U. S. Geol. 

Survey Bull. 128, p. 51, pi. 7, figs. 1-3,1895.

This is a characteristic Bear Kiver species, and easily 

recognized by its large size of shell. It is abundant at 

locality 12. The sculpture is somewhat variable, but, in 

general, the rib ridges are rather distantly spaced, and 

in places are partly or entirely obsolete.

Figured specimens : USNM 108463.

Pachychiloides cokevillensis Yen, n. sp.

Plate 18, figures 3, 4

Shell narrowly elongate in outline, having a highly 

turrited spire, tapering toward apex gradually, and descending at the aperture. Whorls increasing rapidly in 

size, coiling much below the periphery. Surface gently 

convex, slightly shouldered below the suture, and bearing strong and well-spaced rib ridges. Aperture subovate in outline, and the peristomal margin is probably 

somewhat expanded at the base when it is perfectly 

preserved.

Measurements (in millimeters) : Altitude of shell 38.0, width 

11.0; height of aperture 9.0, width 8.0; about 10 whorls.

This species is readily separated from the preceding 

one by its smaller size, more elongate shape, and more 

closely spaced rib ridges. It has so far been found at 

locality 6 in the upper part of division 2.

Holotype: USNM 108465 ; paratypes: USNM 108466. 

Pachychiloides turricula (White), 1895"

Pachymelania turricula White, U. S. Geol. Survey Bull. 128, 

p. 53, pi. 7, figs. 14,15, 1895.

The type lot consists of a single specimen labelled 

from "Bear River near Sage." I have found no other 

specimens of this species in the early collection marked 

as coming from the mouth of Sulphur Creek. This 

seems to be a common species found in the lower part 

of the sequence exposed in the Leeds Creek area.

Pachychiloides chrysalis (Meek), 1871

Plate 17, figures 8, 9

Goniobasis chrysalis Meek, U. S. Geol. and Geog. Survey Terr. 

Ann. Rept. for 1870, p. 316, 1871; Pachymelania chrysalis, 

White, U. S. Geol. Survey Bull. 128, p. 53, pi. 7, figs. 6, 

7, 1895.

The type lot consists of two specimens figured by 

White, labelled as coming from Sulphur Creek. Another lot of three examples collected near Sage probably 

represent a different form. I have obtained specimens 

from locality 10 in the lower part of division 2, which 

seem to be identical with this species, although tl * 

sculpture is much worn. 

Figured specimen: USNM 108468.

Pachychiloides cf. P. chrysalloidea (White), 1876 

Plate 17, figures 6, 7

Goniobasis chrysalloidea, White in Powell's Rept. Geol. Uinta 

Mts., p. 123,1876; Pachymelania, chrysalloidea, White, U. S. 

Geol. Survey Bull. 128, p. 52, pi. 7, figs. 4, 5,1895.

This species was previously recorded only from its 

type locality, the Bear River near the mouth of Sulphvr 

Creek. The one specimen from 7 miles north of Evan"*- 

ton, mentioned by White, is an immature example of 

Pachychiloides clebwi. I have obtained severrl 

closely comparable specimens from locality 12, but identification can be settled only by having a few more 

perfectly preserved examples from the type locality to 

show the range of variation for comparison.

Pachychiloides macilenta (White), 1880 

Plate 17, figures 10, 11

Goniobasis macilenta White, U. S. Geol. and Geog. Survey Terr. 

12th Ann. Rept., p. 93, pi. 30, figs. 10, lOa, 1880; Pachymelania 

macilenta, White, U. S. Geol. Survey Bull. 128, p. 54, pi. 7, 

fig. 9, 1895.

The early collections contain specimens of this species 

both from the "Bear River Valley near mouth of 

Sulphur Creek," and the locality "8 miles north of 

Evanston." One young example is labelled "20 miles 

north of Cokeville." The type locality is 8 miles north 

of Evanston. I have obtained specimens from locality 

8 of division 2, and localities 11 and 12 of the Ber.r 

River formation.

Figured specimens: USNM 108472.

Family ELLOBIIDAE

Zaptychius haldemanni (White), 1878

Plate 17, figures 48, 49

Acella haldemanni, White, U. S. Geol. and Geog. Survey Terr. 

Bull. 4, p. 714, 1878; Fortacella haldemanni, White, U. S. 

Geol. Survey Bull. 128, p. 44, pi. 5, figs. 8-12, 1895.

The specimens of the type lot were collected from 

"Sulphur Creek, Bear River," and those of two othflots were from 20 miles north of Cokeville. I have 

obtained specimens from locality 11 of the Bear River 

formation, also at locality 8 of division 2 and locality 

3 of division 3. It seems to be a very common species in 

these zones.

Figured specimens: USNM 108474 and USNM 108476.
56 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

"Auricula" neumayri White, 1895

Auricula neumayri White, U. S. Geol. Survey Bull. 128, p. 41, 

pi. 5, fig. 1, 1895.

The type lot consists of a single specimen labeled 

"Cretaceous Bear River, 20 miles north of Cokeville, 

Wyoming." It is readily distinguished from species 

of Melanipoides and Rhytophorus by its higher spire, 

narrower outline of shell, and two distinct plicae on 

the more or less straight collumellar margin. No additional specimens from this general area belong to this 

species.

Melampoides clarki (White), 1895 

Plate 17, figure 51

Melampus clarki White, U. S. Geol. Survey Bull. 128, p. 42, 

pi. 5, figs. 2, 3, 1895; Melampoides clarki, Yen, U. S. Geol. 

Survey Prof. Paper 233-A, p. 16, pi. 2, fig. 12, 1951.

This species was originally described from a locality 

20 miles north of Cokeville. One of the two original 

lots (USNM 22335) contains two Physet-like, specimens 

and one resembling an imperfect "Auricula? nemna/yri, 

in addition to 5 specimens of M. clarki.

Figured specimen: USNM 108478.

Rhytophorus priscus (Meek), 1860

Melampus priscus Meek, Acad. Nat. Sci. Phila. Proc., v. 12, p. 315, 

1860; Rhytophorus priscus, White, U. S. Geol. Survey Bull. 

128, p. 43, pi. 5, figs. 4, 5, 1895.

The type lot was collected from the Bear River near 

mouth of Sulphur Creek. This species is so far known 

only from the Bear River formation.

Rhytophorus meeki White, 1876

Rhytophorus tneeki White in Powell's Kept. Geol. Uinta Mts. 

p. 118, 1876; White, U. S. Geol. Survey Bull. 128, p. 43, pi. 5, 

figs. 6, 7, 1895.

The type lot was collected from the Bear River near 

mouth of Sulphur Creek. It differs from R. prisons by 

its narrower outline of shell, its columellar plica being 

less strongly twisted and slightly higher in position.

Rhytophorus cf. R. meeki White, 1876

Rhytophorus cf. R. meeki, Yen, U. S. Geol. Survey Prof. Paper 

233-A, p. 16, pi. 2, fig. 11, 1951.

Specimens from locality 6 in the upper part of Division 2 and locality 3 of division 3, resemble R. meeki 

White. The specimens are too poorly preserved for a 

definite identification.

Family PHYSIDAE 

Physa usitata White, 1895

Pkysa usitata White, U. S. Geol. Survey Bull. 128, p. 47, pi. 6, 

figs. 8, 9, 1895; Yen, U. S. Geol. Survey Prof. Pap^r 233-A, 

p. 17, pi. 2, fig. 14, 1951.

The type locality of this species is 20 miles north of 

Cokeville. Two lots in the early collections represent 

this species; one is the type lot, another is labelled from 

"Bear River." I have obtained specimens at locality 

11 of the Bear River formation, and locality 8, of 

division 2, which is probably the same as the type 

locality.

Physa cokevillensis Yen, n. sp. 

Plate 17, figure 52

Shell ovately oblong in outline, of medium size for 

the genus, having an elevated spire and narrowly dilated body whorl. The spire is a little less than onethird the height of the entire shell. Whorls increasing 

rather gradually in early stages and rapidly in later 

stages; narrowly dilated at the body whorl, having its 

surface gently convex and bearing fine lines of growth. 

Aperture narrowly oblong in shape, outer lip thin and 

simple, parietal wall very thin and columellar margin 

slightly reflected.

Measurement (in millimenters) : Altitude of sh^ll 6.5-f, 

width 3.2; height of aperture 4.5, width 2.1; 4 whorls preserved.

This species differs from P. usitata by its much 

smaller size, ovately oblong outline and narrower aperture. Specimens were collected from locality 8 of division 2, but most of them are of immature individuals.

Holotype: USNM 108483 ; paratypes : USNM 1084?4.

Physa globosa Yen, n. sp. 

Plate 17, figure 53

Shell ovately globose in outline, of small size, having a conically elevated spire and dilated body whorl; 

the spire is smaller than the body whorl. Whorls increasing rather gradually on the spire but dilated on 

body whorl, which has the surface gently convex, 

slightly shouldered and bearing fine lines of growth. 

Aperture small, pyriform in shape, outer lip thin, and 

simple, inner lip thin and columella slightly reflected.

Measurements (in millimeters) : Altitude of shell 3.8, width 

2.8; height of aperture 2.2, width 1.8; 5 whorls.

The species differs from P. cokemllensis by its ovately 

globose outline, slightly shouldered whorls and small 

pyriform aperture.

Holotype: USNM 108485 ; paratypes : USNM 10848?.
A FAUNA FROM WESTERN WYOMING 57

Family LYMNAEIDAE 

Lymnaea nitidula (Meek), 1860

Melaniaf nitidula Meek, Acad. Nat. Sci. Phila. Proc., v. 12, p. 314, 

1860; Limnaea, nitidula, White, U. S. Geol. Survey Bull. 

128, pi. 6, figs. 1-3, 1895.

This species must be considered as doubtfully referred to Lymnaea. There are three lots in the early 

collection, two of them from ''Bear River near mouth of 

Sulphur Creek" and one from "Bear River Valley, 

Wyoming." I am unable to locate the lot White noted 

as collected by Stanton from "20 miles north of Cokeville." After examining the available specimens, I 

found them to differ from Lymnaea even in its broad 

sense. The lot collected from "Bear River Valley" 

contains specimens that may be referred to Lioplacodes.

Family PLANORBIDAE 

Gyraulus sp. undet.

Two lots of specimens, one from locality 11 of the 

Bear River formation, and another from locality 8 of 

division 2, represent this form. It is found in association with Vcrtvata praecursoris, and both of them are 

rather common in these beds. Gyraulus is easily distinguished from Valvata in that the whorls are closely 

coiled above the periphery, the body whorl is raised 

higher than the apical whorls and the aperture is semilunate in outline.

The specimens available do not reveal-features that 

would distinguish them from several species of Cryrcmlus, a genus known from late Jurassic to Recent times.

1 prefer to leave their specific status as undetermined.

Anisopsis minutis Yen, 1951

Anisopsis mintitis Yen, U. S. Geological Survey Prof. Paper 

233-A, p. 16, figs. 13a-c, 1951.

This species is known only from the beds exposed 

south of Leeds Creek. It is readily recognized by its 

more or less sunken apical whorls, nearly flattened or 

slightly concave base, and its bicarinated body whorl.

Several specimens collected from locality 8 of division

2 may be congeneric with this species, but differ by having the apical whorls more exposed. Only one of the 

specimens is well preserved in that lot, and it is preferable, therefore, to leave them as undetermined at 

present.

PELECYPODA

Family OSTREIDAE

Ostrea haydeni White, 1895

Ostrea liaydeni White, U. S. Geol. Survey Bulletin 128, p. 32, 

pi. 2, figs. 1, 2, 1895.

This species has been recorded from the Bear River 

formation and the sequence exposed north of Cokeville.

It is generally found in beds of brackish-water origin, 

but fragments are also found in true fresh-water beds. 

The admixture is evidently caused by drift frorc an 

estuarine area.

This one of the Bear River species that has never 

been well defined on account of the lack of well-preserved specimens, and the records of it must be considered as provisional. White's figure was based on an 

imperfect specimen, and I have found only fragments. 

However, it seems to have been a rather common species.

Family MYTILIDAE 

Brachydontes peali White, 1895

Brachydontes peali White, U. S. Geol. Survey Bull. 128, p. 33, pi. 

2, fig. 3, 1895.

The type specimen was probably from the sequence 

exposed "near Sage," south of Cokeville. It represents 

a young stage of the species. Most of the specimens 

identified as this species in the later collections consist 

of fragments of shells of various sizes, and they v/ere 

identified largely on the presence of radiating line? of 

sculpture. I have collected one specimen of an internal 

mold in association with some fragments of shell from 

locality 6 of division 2, which measures 37.0 mm, in 

length of shell and 21.0 mm in width. It apparently 

represents this species.

Family CORBTJLIDAE

Corbula pyriformis Meek, 1860

Plate 17, figures 59-61

Corbula (Potamomya) pyriformis Meek, Acad. Nat. Sci. P' ila. 

Proc., v. 12, p. 312, 1860; Corbula pyriformis, White, U. S. 

Geol. Survey Bull. 128, p. 38, pi. 4, figs. 5-9, 1895.

This species is commonly found at various levels within the Bear River formation. Most specimens found in 

the sequence exposed in the vicinity of Cokeville are 

smaller than usual but the significance of the difference 

in size is unknown.

Vokes (1945) proposed the genus Ursirivm for this 

species because of its possession of a chondrophore, its 

large size, deep lunule and escutcheon, and its pronounced pyrif orm shape of both valves and presence of a 

small but definite pallial sinus (p. 17). I examined all 

available specimens, including Vokes' specimens and the 

type lot of the species, and found that the anterior and 

posterior muscular impressions are slightly depressed 

but not so deep as to warrant special note; the pallial 

sinus, which is an obtusely angular curvature formed 

by the pallial line below the posterior muscular impression is not noticeably different from that of about 

half a dozen Kecent species of Cor'bula I have examined.
58 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

Besides, the differences in general shape and size are 

hardly features of generic importance.

Moreover, Yokes' figure of the left valve of Gorbula 

sulcata Lamarck, which is said to be a topotype from 

coast of Senegal, West Africa, shows considerable 

difference in hinge features from that given by Brugiere 

(pi. 230, fig. Ic), which was drawn from one of the 

original types. Bruguiere's illustration shows a small 

but distinct projecting structure on the left valve, and 

the presence of this feature has been confirmed by later 

authors. Try on, for instance, described it as a "projecting cartilage-process." Such a difference, as shown by 

the figures of Bruguiere, is particularly significant 

when Dr. Vokes so emphasized the importance of the 

absence of this chondrophore as a basic element in his 

treatment of subfamilies and genera of Corbulidae.

Figured specimens: USNM 108498.

Corbula engelmanni Meek, 1860 

Plate 17, figures 57, 58

Corbula (Potamomyaf) engelmanni Meek, Acad. Nat. Sci. Phila. 

Proc., v. 12, p. 312, 1860; Corlula engelmanni, White, U. S. 

Geol. Survey Bull. 128, p. 40, pi. 40, figs. 10, 11, 1895.

This species is commonly found at different levels in 

the Bear River formation, and also in the lower part of 

division 2. This species is characterized by its small 

size, subtriangular outline of shell, strong and elevated 

concentric riblines. The hinge structure is not known, 

but, judged by the external features of shell, the species 

resembles Gorbula zurcheri Eepelin, 1902 (p. 57, pi. 4, 

figs. 16-21), which is a species of Corbula as indicated by 

external features and the hinge.

Figured specimens: USNM 108493.

Family CORBICTTLIDAE

Corbicula durkeei (Meek), 1870

Plate 17, figures 54-56

Cyrena (Corbicula?) durkeei Meek, Am. Philos. Soc. Phila. 

Proc., v. 11, p. 431, 1870; CorUcula durkeei, White, U. S. 

Geol. Survey Bull. 128, p. 36, pi. 4, figs. 1-4, 1895.

This species is common in the Bear Eiver formation, but rather rare in the sequence exposed in the vicinity of Cokeville.

Specimens collected from locality 6 of division 2 are 

smaller than those found in the Bear Eiver. THy may 

represent a new variety, but the specimens in the collection are too poorly preserved to provide a characteristic description of the form.

Figured specimen; USNM 108499.

Family TTNTONIDAE

TInio vetustus Meek, 1860

Plate 17, figure 63

Unio vetustus Meek, Acad. Nat. Sei. Phila. Proc., v. T2, p. 312, 

I860; White, U. S. Geol. Survey Bull. 128, p. 38, pi. 3, figs. 

1-4, 1895.

This common Bear Eiver species, usually found in 

association with U. belliplicatus, is easily distinguished 

from that by having strong concentric riblines confined 

to the umbonal area, and fine lines of growth over the 

postumbonal surface; and the species may be u^ed generally as an index for local correlation of the Upper 

Cretaceous in southwestern Wyoming.

As White noted, the species is particularly common 

in the Bear Eiver at both localities 11 and 12 of division

1. It seems to be common also at locality 6 of division

2. but the specimens collected from that area are mostly 

distorted, and its specific identification cannot at present be definitely established. 

Figured specimen: USNM 108506.

Unio belliplicatus Meek, 1870 

Plate 17, figure 62

Unio belliplicattts Meek, Am. Philos. Soc. Phila. Proc., v. 11, 

p. 439, 1870; White U. S. Geol. Survey Bull. 128, F- 34, pi. 2, 

figs. 4-6, 1895.

This species is readily recognized by its prominent 

radiating plications on about the posterior two-thirds 

of the external surface. Its occurrence in the Bear 

River is abundant at various levels. However, it is 

not so common in the sequence exposed in the vicinity 

of Cokeville, where only fragmentary pieces of shells 

bearing the characteristic plications have been collected.

Figured specimen: USNM 108504.
REFERENCES CITED

Bruguiere, J. G., 1798, Tableau encyclopedique et nie'thodique 2,

Planches 93-286, Paris. 

Meek, F. B., I860, Descriptions of new fossil remains collected

in Nebraska and Utah, Proc. Acad. Nat. Sci. Phila., v. 12,

p. 308-315.

————1870, A preliminary list of fossils, collected by Dr. 

Hayden, etc.: Proc. Am. Philos. Soc. Phila., v. 11, p. 425-431.

——— 1871, Preliminary paleontological report consisting of 

lists of fossils with description of some new types: U. S. 

Geol. and Geog. Survey Terr., 4th. report, 287-318.

————1873, Preliminary paleontological report consisting of 

lists and descriptions of fossils, with remarks on the ages 

of rocks, etc.: U. S. Geol. and Geog. Survey Terr., 6th. annual report (for 1872), p. 431-541.

———1877, Paleontology: U. S. Explor. 40th Parallel, v. 4, pt.

1, p. 1-197, 17 pis.

Repelin, J., 1902, Description des faunes et des gisement du 

Ce'nomanien saumatre ou d'eau douce du Midi de la France: 

Arch. Mus. d'Hist.^nat Marseilles, tome 7 part 2.

Rubey, W. W. 1950, Alternate return log (of field trip), first 

day, August 9, 1950; Guide Book of 5th Geol. Field Conference of Wyoming.

Stache, Guido, 1889, Die liburnische Stufe und deren GrenzHorizonte: K. k. geol. Reichsanstalt Abh. Band 13, pt. 1.

Yokes, Harold E., 1945, Supraspecific groups of the pelecypod

family Corbulidae: Am. Mus. Nat. History Bull., v. 86, no. 1,

32 p. 4 pis. 

White, C. A., 1876, Invertebrate paleontology, in J. W. Pow?ll

Report on geology of eastern portion of Uinta Mountains,

p. 74-135.

———1878, Paleontological Papers, no. 6: U. S. Geol. and Geog. 

Survey Terr. Bull. 4, p. 707-719.

———1880, Contribution to invertebrate paleontology, no. 4: 

U. S. Geol. and Geog. Survey Terr., 12th. report, pt. 1, 

p. 49-103.

———1895, The Bear River formation and its characteristic

fauna: U. S. Geol. Survey Bull. 128, p. 1-86, 10 pis. 

Yen, T. C., 1951, Fresh-water mollusks of Cretaceous age from 

Montana and Wyoming: U. S. Geol. Survey Prof. Pajr^r 

233-A, pt. 2, p. 11-18,1 pi.

——— 1952a Fresh-water molluscan fauna from an Upper Cretaceous porcellanite near Sage Junction, Wyo.: Am. Jour. 

Sci., v. 250, p. 344-359, 1 pi.

——— 1952b, Age of the Bear River formation, Wyoming: Geil. 

Soc. America Bull., v. 63, p. 757-764.

———1952c, Ecological interpretations of Upper Cretaceous 

depositions near Sage Junction, Wyo.: Geol. Soc. America 

Bull., v. 63, p. 1317.

PART 2: FAUNAS FROM EASTERN UTAH AND WESTERN COLORADO

ABSTRACT

Fifteen collections of nonmarine mollusks are recorded from 

the Price River (Farrer and Neslen members) Mount Garfield, 

and Hunter Canyon formations exposed in the Books Cliffs 

coalfield area in eastern Utah and western Colorado. Three 

species of Unto and one of Tolotomops are described as new.

INTRODUCTION

Few late Cretaceous nonmarine molluscan faunas 

have been studied since Stanton's work, which was 

based on the collections made in San Juan Basin of 

Northern New Mexico, was published in 1916. In the 

late twenties, C. E. Erdmann and D.. J. Fisher investigated the coal fields of the Book Cliffs in eastern Utah 

and western Colorado, and as a result, several large collections of nonmarine fossils were made from some 

usually inaccessible localities in this extremely rugged 

country. As a report by Erdmann, Fisher and Reeside 

on the stratigraphic results of their investigations in 

this area is nearing completion, it seems appropriate to 

describe the nonmarine mollusks from their collections.

Most of the specimens have been preliminarily identified by Dr. T. W. Stanton, or by Dr. John B. Reeside, 

Jr., who collected some of the specimens. Most of the 

fossils were imbedded in sandstone or in sandy shale, 

which as usual contain rich f aunules but rather poorly 

preserved specimens; however, in a few localities, more 

perfectly preserved specimens permit description of 

.some new species.

COLLECTION LOCALITIES AND THEIR MOLLUSCAN 

ASSEMBLAGES

The present work deals with collections of nonmarine 

mollusks from the following five units in the Mesaverie 

group:

1. Price River formation:

USGS Mesozoic loc. 8140, in sec. 14, T. 13 S., R. 10 F, 

Deadmans Canyon, Wellington quadrangle, Utah; base 

of Price River formation, collected by F. R. and G. T*7. 

Clark, 1912. It contains the following species of mollusks:

Unio cf. U. prisons White

Unio cf. U. amarillensis Stanton

Unio sp. undet.

Sphaerium cf. S. planum Meek and Hayden

Tulotomops sp. undet.

Campeloma cf. C. amarillensis Stanton

USGS Mesozoic loc. 12247, about 1 mile above t\e 

Castle Gate on Price River; very near top of Castlega te 

sandstone; collected by E. M. Spieker and J. B. Reeside, 

Jr., 1923. It contains the following species of mollusks:

Unio sp. undet. 

Valvata sp. undet. 

Viviparus sp. undet. 

Tulotomops sp. undet. 

Lioplacodes sp. undet. 

Goniobasisf subtortusa Stanton

59
60 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

2. Farrer formation:

USGS Mesozoic loc. 13682, in SE^4 sec. 32, T. 20 

S., R. 20 E, Book Cliffs, Utah; about 390 feet above 

Sego sandstone; collected by D. J. Fisher, 1923. It contains the following species of mollusks:

Uiiio cf. U. brimliallensis Stantoii 

Unio cf. U. brachyopisthus Stantoii 

Unio amarillensi'S Stanton 

Tulotomops sp. undet. 

Campeloma amariUensis Stanton 

Amnicola sp. undet.

3. Neslen formation:

USGS Mesozoic loc. 13686, in sec. 18, T. 19 S., R. 23 

E., Diamond Canyon, north of Cisco, Utah; about 120 

feet above Sego sandstone; collected by R. M. Leggette, 

1926. It contains the following species of mollusks:

Unio sp. undet.

Corbula subtriffonalis Meek and Hayden

Tulotomops sp. undet.

Campeloma amariUensis Stanton

USGS Mesozoic loc. 13688, in sec. 10, T. 17 S., R. 24 

E., East Canyon, Westwater Creek, Utah; 304 feet above 

Sego sandstone; collected by R. M. Leggette, 1926. The 

collection contains the following species of mollusks:

Tulotomops sp. undet.

Campeloma cf. C. amariUensis Stanton

Amnicola sp. undet.

USGS Mesozoic loc. 13689, in sec. 24, T. 18 S., R. 23 

E., in a canyon off east side of Sulphur Canyon, Book 

Cliffs, Utah; collected by D. J. Fisher, 1926. It contains the following species of mollusks:

Unio sp. undet. 

Tulotomops laevibasalis Yen 

Campeloma sp. undet.

USGS Mesozoic loc. 13674, in sec. 2, T. 21 S., R. 18 

E., Horse Canyon, Utah; 340 feet above Castlegate 

sandstone; collected by D. J. Fisher, 1926. It contains 

the following species of mollusks:

Corbula, subtriffonalis Meek and Hayden 

Tulotomops laevibasalis Yen 

Campeloma amariUensis Stanton 

Lioplacodes sp. undet.

USGS Mesozoic loc. 13334, in NW% sec. 9, T. 20 

S., R. 17 E., Book Cliffs, Utah; 230 feet above top of 

Castlegate sandstone; collected by D. J. Fisher, 1925. 

It contains the following species of mollusks:

Unio sp. undet.

SpJiaerium cf. S. planum Meek and Hayden 

Tulotomops cf. T. laeribasalis Yen 

PJiysa sp. undet.

4. Mount Garfield formation:

USGS Mesozoic loc. 13970, in NW corner SW*4 sec. 

29, T. 7 S., R. 104 W., near Closure, Colorado; 40 feet

above highest Carbonera coal bed, and 375 fe^t above 

Sego sandstone; collected by C. E. Erdmann, 1927. It 

contains the following species of mollusks:

Unio pxeudendlicJii Yen 

Unio mesaverdensis Yen 

Unio paraholmesiawus Yen 

Unio sp. undet. 

Campeloma, sp. undet.

USGS Mesozoic loc. 4195 and 4197, in sec. £3, T. 11 

S., R. 98 W., about 4 miles SE of Palisade, Colorado; 

150 feet above the upper coal bed; collected by W. T. 

Lee, 1907. It contains the following species of 

mollusks:

SpJiaerium cf. S. planum Meek and Hayden 

Corbula subtriffonalis Meek and Hayden 

Tulotomops laevibasalis Yen 

Campeloma sp. undet. 

Mesolanistes recsidei (Stanton) 

Amnicola sp. undet. 

Pliusa sp. undet.

USGS Mesozoic loc. 4184—about 4 miles SE of Palisade, Colorado; 300 feet above upper coal bed of Grand 

Mesa coalfield; collected by T. W. Stanton, 1907. It 

contains the following species of mollusks:

Unio cf. U. brimhattensis Stanton

Unio amarillensis Stanton

Tulotomops sp. undet.

Campeloma cf. C. amariUensis Stanton

Lioplacodes sp. undet.

Amnicola sp. undet.

5. Hunter Canyon formation:

USGS Mesozoic loc. 4188, in sec. 1, T. 11 S., R. 98 

W., about 3 miles east of Palisade, Grand River, Colorado; collected by W. T. L'ee, 1907. It contains the 

following species of mollusks:

l&pJifieriu-Hi sp. undet.

Valvata, sp. undet.

Mesolanistes cf. H. reesidei (Stanton)

Campeloma, sp. undet.

Goniobasis cf. Or. eulimoid.es (Meek)

Goniobasis sp. undet.

Physa, sp. undet.

USGS Mesozoic loc. 4191, in sec. 26, T. 10 fi., R. 98 

W., head of Gulch, 1 mile east of Grand River, 2 miles 

below mouth of Plateau Creek, Colorado; collected by 

W. T. Lee, 1907. It contains the following species of 

mollusks:

Unio cf. U. prisons White

Tulotomops sp. undet.

Campeloma cf. C. amariUensis Stanton

USGS Mesozoic loc. 4214, in sec. 20, T. 13 S., P. 95 W., 

Oak Creek, near Delta, Colorado; "about 700 feet above
A FAUNA FROM WESTERN WYOMING ei

the base of Laramie:" collected by W. T. Lee, 1907. It 

contains the following species of mollusks:

Unip sp. undet.

Spliaerium sp. undet.

Tulotomops laevfbasalis Yen

Campeloma sp. undet.

Lioplacodes sp. undet.

Goniobasis? snbtortii-sa (Meek and Hay den)

Amnicoln sp. undet.

USGS Mesozoic loc. 4486, in sec, 20, T. 13 S., R. 95 W., 

near Hotchkiss, Colorado; "995 feet above base of coalbearing beds, and 500 feet below Wasatch or Kuby 

shales"; collected by W. T. Lee, 1907. It contains the 

following species of mollusks:

Unio cf. U. priscus Meek and Hayden 

Unio cf. U. amwillengis Stanton 

Unio cf. U. "britnkattemis Stanton 

Teredlna- sp. undet. 

Tulotomops sp. undet. 

Campel&ma sp. undet. 

Lioplacodes sp. undet.

SYSTEMATIC DESCRIPTIONS

PELECYPODA

Family UNIONIDAE

Unio cf. U. brimhallensis Stanton

Plate 18, figure 12

Unio torimhallensis Stanton, U. S. Geol. Survey Prof. Paper 98-R, 

pi. 81, fig. 7; pi. 82, fig. 1,1916.

Several specimens in the collection bear resemblance 

in general shape to Stanton's species, which was originally described from the Fruitland formation, but they 

are much smaller. They probably represent a distinct 

form, possibly related to the Fruitland species.

Figured specimen: USNM 108511.

Unio cf. U. brachyopisthus White 1876 

Plate 19. figure 32

Unio bracliyopistlms Stanton, U. S. Geol. Survey Prof. Paper 

98-R, p. 314, pi. 81, figs. 2, 3, 1916.

A single poorly preserved specimen resembles the 

species as illustrated by Stanton from the Fruitland 

formation, although the latter specimen is ovately 

rhomboid and it is somewhat larger.

Figured specimen: USNM 108512.

Unio paraholmesianus, n. sp. 

Plate 18, figure 9; plate 19, figure 31

Shell subelliptical to subovate, medium thick in substance, and having moderately convex valves. Beaks 

situated close to the anterior end and bear two broad 

radiating folds on the surface, which produce two 

prominent ridges extending anteriorly and posteriorly;

V-shaped sculpture is subregularly formed along both 

ridges over about two-thirds or more of the shell surface. The hinge features are not preserved in the specimens available.

Measurements (in millimeters) : length 48.0; height 30.0 (a 

young hut fairly well preserved specimen).

This species is readily recognized by its characteristic 

sculpture.

Holotype: USNM 108539; paratypes: USNM 108540 (figured), 

108541. 

Type locality: USGS Mesozoic loc. 13790.

Unio pseudendlichi, n. sp. 

Plate 18, figures 13, 14

Shell broadly subovate in outline, large and of thick 

substance. Valves moderately convex and bear distinct 

concentric lines of growth, conspicuous but irregulr.r 

bandings produced by the slightly convex and sharpedged basal margin at various resting stages. Hinge 

features not definitely known except for the presence of 

a prominent pseudocardinal and rather posteriorly 

placed laterals.

Measurements (in millimeters) : length 127.0, height 76.0.

The size of this species approaches that of Unio 

endlichi White, which was described from the Lance 

formation in Wyoming, but the species from the Mesaverde seems to have a more prominent pseudocardinal 

and smaller posterior laterals.

Holotype: USNM 108538.

Type locality : USGS Mesozoic loc. 13790.

Unio mesaverdensis, n. sp. 

Plate 18, figures 10, 11; plate 19, figures 33, 34

Shell ovately subtriangular in outline, of thick sul - 

stance and medium size. Valves strongly convex and 

bearing simple growth lines. Pseudocardinal on left 

valve larger than that on right, depth of correspoiidin g 

sockets likewise adjusted; single posterior lateral on the 

left valve is well developed to fit deep cavity bound by 

two laterals on the right. Anterior muscular impression 

much deeper than posterior one. Anterior protractor 

scar deep but small.

Measurements (in millimeters) : Length 68.2, height 49.5, 

convexity 38.0.

Holotype: USNM 108542.

Type locality: USGS Mesozoic loc. 13790.

Unio amarillensis Stanton

Unio amarillemis Stanton, U. S. Geol. Survey Prof. Paper 98-P, 

pi. 80, fig. 89, 1916.

This species is characterized by its small size and by 

having its V-shaped sculpture confined to the umbonrl
62 NONMARINB MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

area and the surface of its posterior slope. Its hinge 

structure is not known.

Several specimens in the present collection, which 

were found in the Farrer and Mount Garfield formations, seem to belong to this species, which was originally described from the Fruitland formation of New 

Mexico.

Unio cf. U. prisons Meek and Hayden

Plate 19, figure 30

Unio prisous Meek and Hayden, Acad. Nat. Sci. Philadelphia 

Proc., v. 8, p. 117,1856.

Several specimens of rather thin shell substance and 

light hinge structure, although they are incompletely 

shown, seem to be comparable with this common Upper 

Cretaceous species. The available valves, which are 

either much distorted or in the form of internal molds, 

do not permit definite identification to species.

Figured specimen : USNM 108578.

Family SFHAERIIDAE 

Sphaerium cf. S. planum Meek and Hayden

Sphaerium planum Meek and Hayden, Acad. Nat. Sci. Philadelphia Proc., v. 12, p. 175, 1860.

The size and general outline of several valves, represented by imbedded molds, show resemblance to this 

species, which has been recorded from the Lance and the 

Judith River formations in Wyoming and Montana. 

The available specimens are not identifiable definitely to 

species.

Sphaerium sp. undet.

Another form of Sphaerium^ slightly larger in size 

and somewhat more triangular in outline than S. f 

planwn occurs in the Price River formation. Only two 

internal molds of separate valves are available, and 

they cannot be identified to species.

Family CORBTJLIDAE 

Corbula subtrigonalis Meek and Hayden

Plate 19, figure 29

Corbula subtrigonalis Meek and Hayden, Acad. Nat. Sci. Philadelphia Proc., v. 8, p. 279, 1856.

A large number of specimens in one collection from 

the Mt. Garfield formation agree with this species which 

was originally described from Upper Cretaceous deposits in Wyoming and Montana.

Figured specimen: USNM 108536.

Family PHOLADIDAE 

Teredina sp. undet.

Plate 19, figures 9, 10

The specimens in the present collection consist of 

tubes only, so that their identity cannot be established

definitely. However, there is little doubt that such 

tubes indicate the presence of Teredina-like sp?,cies.

Figured specimen: USNM 108581.

GASTROPODA 

Family VAIVATIDAE 

Valvata sp. undet.

A single specimen imbedded in the matrix represents 

a species of Valvata from the Hunter Canyon formation. The specimen consists of a little more tl <vn three 

tubular whorls, and has a slightly elevated spire. The 

features of aperture and umbilicus are not shovm, therefore its specific identification cannot be established.

Family VIVIFARIDAE

Tulotomops laevibasalis, n. sp.

Plate 19, figures 24-26

Tulotoma thompsoni Stanton, U. S. Geol. Survey Prof. Paper 

98-R, p. 318, pi. 83, figs. 9-11, 1916 (not White 1876).

Shell of trochoid outline, imperforate, with conical 

spire and descending body whorl. Height of the spire 

slightly greater than that of body whorl. Whorls increasing rapidly in size, later ones coiling belo^ periphery. Whorl surface slightly convex, initiated with an 

almost mucronate apex and a roundly convex apical 

whorl. Faint angulation on shoulder of the third whorl, 

developing into a strong and heavy carina on si oulder of 

later whorls. A second equally heavy carina on body 

whorl marks edge of basal surface. Occasional tubercles 

on these spiral carinae of the last two whorls, but they 

never became very conspicuous. The basal rarface is 

nearly flat or slightly convex and bears no spiral carina. 

Aperture subovate in outline; outer lip biangulated, 

the angles being formed by the two strong carinae on the 

body whorl; parietal wall thickened and well defined, 

and columellar margin slightly arched.

Measurements (in millimeters) : Altitude 36.5, width 23.0; 

height of aperture, 15.5, width 14.0; 7 whorls.

This species is readily distinguished from T. thompsoni (White) by having only two instead of three, and 

lower spiral carinae with a few tubercles on th°. surface, 

and also by the absence of a ridge on the basal surface. 

These features are persistent in the Mesaverde specimens.

Holotype: USNM 108533; figured paratypes, USNM 108534; 

paratypes USNM 108535. 

Type locality: USGS Mesozoic loc. 13674.

Tulotomops sp. undet.

Several lots of specimens resemble T. laevibasalis 

in general outline, but they differ by their size and 

obscure sculptures. None of them is well enough pre-
A FAUNA FROM WESTERN WYOMING 63

served for definite identification to species and some of 

them may belong to T. laevibasalis.

Campeloma amarillensis Stanton 

Plate 19, figures 22, 23

Campeloma amarillensis Stanton, U. S. Geol. Survey Prof. 

Paper 98-R, p. 318, pi. 83, figs. 5-6, 1916.

This species is probably common in the Mesaverde 

group, although it was originally described from the 

Fruitland formation in New Mexico. Some specimens, 

even though imperfectly preserved, show broader body 

whorl and higher spire. Such differences are within 

the range of variation of the viviparous species of 

gastropods. Specimens of immature stages appear 

generally to have a subtriangular outline.

Figured specimen: USNM 108515.

Campeloma sp. undet. 

Plate 19, figures 11, 12

Some of the specimens consist of internal molds that 

are somewhat distorted. Some resemble Campeloma 

amarillensis in outline and size. These specimens can 

be recognized only as members of the genus. 

Figured specimens: USNM 108544.

Lioplacodes sp. undet. 

Plate 19, figures 13-17, 20, 21

Several lots of specimens resemble in outline and 

size some species of Lioplacodes, which have been recorded from Early Cretaceous to Early Tertiary deposits in the western interior. However, these 

specimens consist of internal molds and imperfect shells, 

and so cannot be identified to species.

A single specimen collected from the Hunter Canyon 

formation (USGS Mesozic loc. 4486) resembles Lioplacodes veternus Meek in outline, but is larger. Other 

specimens in the collection may represent other species 

of the genus.

Figured specimens: USNM 108584.

Family AMPUIIABIIDAE

Mesolanistes reesidei (Stanton)

Plate 19, figures 27, 28

Physa reesidei Stanton, U. S. Geol. Survey Prof. Paper 98-R. 

p. 319, pi. 83, figs. 12-13, 1916.

A single specimen seems to belong to this species, 

which was originally described from the Fruitland 

formation.

Since I described Mesolanistes in 1945, more specimens of this sinistral group of gastropods have come 

to my attention. The specimens are all distorted, and 

perfect outline of the shell has so far not been recorded, although a number of important shell features 

have been described.

Figured specimen: USNM 108562.

Family AMNICOLIDAE

Amnicola sp. undet. 

Plate 17, figures 45-47; plate 19, figures 1-4, 7

Several lots of specimens, most containing a single 

specimen, may belong in this genus, and a few of them 

are illustrated on plate 19.

A single specimen collected from the Mount Garfield 

formation (USGS Mesozoic loc. 4184) has a planc1*- 

bitoid initial whorl similar to that of Probythinella 

Thiele and Brannerillus Hannibal. It is illustrated by 

figures 1 and 2 of plate 19. This specimen represerts 

the earliest record of an amnicolid bearing a planorboid 

summit. It is a poorly preserved specimen, and more 

perfect examples may reveal it to be a distinct genus.

Figured specimen : USNM 108516.

Family PLETJROCERITIDAE

Groniobasis? subtortuosa (Meek and Hay den)

Plate 19, figures 5, 6

Melania subtortuosa Meek and Hayden, Acad. Nat. Sci. Phi'adelphia Proc., v. 9, p. 136; Goniobasisf subtortuosa Stanton, 

U. S. Geol. Survey Prof. Paper 98-R, p. 319, 1857, pi. 83, 

figs. 7, 8, 1916.

This species is characterized by its conoid screwshaped outline, with a strong carina along the periphery. Three specimens of immature stages collected 

from the Hunter Canyon formation seem to belong in 

it. The species was originally described from the 

Judith River formation in Montana, but it is also recorded from the Fruitland formation in New Mexico.

The generic assignment here is considered uncertain 

and the species is probably not a Goniobasis, but the 

material available does not permit more exact identification.

Figured specimen : USNM 108576.

Goniobasis cf. G. eulimoides (Meek) 

Plate 19, figure 8

A single specimen collected from the Hunter Canyon 

formation resembles G. eulimoides (Meek) in general 

outline and size. The species was originally described 

as a species of Hydrobia and from the Clear Fork of 

Powder River in Montana. Some of the specimens in 

the type lot of G. eulimoides show distinctly a curvature 

of the outer lip margin, which feature alone indicates 

that this species does not belong to Hydrobia, but more 

likely is a species of Goniobasis.

Figured specimen: USNM 108564.
64 NONMARINE MOLLUSKS OF LATE CRETACEOUS AGE FROM WYOMING, UTAH, AND COLORADO

Goniobasis sp. undet.

A single imperfect specimen seems to represent another species of Goniobasis in the Hunter Canyon formation. It is smaller than most species of the genus, 

and its whorl surface appears to be smooth rather than 

sculptured.

Family PHYSIDAE

Physa sp. undet. 

Plate 19, figures 18, 19

Three specimens, one each from the Neslen, the Mount 

Garfield, and the Hunter Canyon formations, represent 

species of Physa in the present collection. The general 

outline and size of the shell indicate that they may be 

three different species, but none of them is well enough 

preserved to show specific features. The specimen illustrated was collected from the Mount Garfield formation.

Figured specimen : USNM 108559.

REFERENCES CITED

Meek, F. B., and Hay den, F. V., 1856, Description of new species 

of Acephala and Gastropoda from the Teritary formations 

of Nebraska Territory: Acad. Nat. Sci. Phila. Proc., v. 8, 

p. 111-126.

———— 1857, Description of new species and genera of fossils: 

Acad. Nat. Sci. Phila. Proc., v. 9, p/117-14S.

1860, Description of new organic remains fro'n the Tertiary, Cretaceous, and Jurassic rocks of Nebraska: Acad.

Nat. Sci. Phila. Proc., v. 12, p. 175-185. 

Stanton, T. W., 1916, Nonmarine Cretaceous invertebrates of

the San Juan Basin: U. S. Geol. Survey Prof. Paper 98-R,

S09-319, 5 pis.

Stanton, T. W., and Hatcher, J. B., 1905, Geology End paleontology of the Judith River beds; U. S. Geol. Survey Bull.

257. 

White, C. A., 1876, Invertebrate paleontology, in J. W. Powell

Report on geology of eastern portion of Uinta Mountains,

p. 74-135. 

Yen, T. C., 1945, Notes on Cretareous fresh-water gastropods

of southwestern Utah: Acad. Nat. Sci. Philt. Notulae

Naturae, no. 160, p. 1-2, 1 pi.
INDEX

[Italic numbers indicate descriptions]

Page 

Acknowledgements.-.._______________________.___.-..._______ 45,59

altisptrale, Parateinostoma ____________._..._...._--___._____ 46,47,48, 53, pi. 17

amarillensis, Campeloma_._____-____._.-_-____...........__ 59,60, 63, pi. 19

Unio.. _——————.——— ——— ———— ——— ——— ____ -------.-__-_ 59,60,6^

Amnicola sp_. -.-------.--------------...-...........-.......--- 60, 61, 63, pis. 17,19

Anisopsis minutis— _______.._________________________— _ — — ____ 46,48,49,57

attenfuata, Lioplacodes stachei- _-_---____._______________________ 46,47,48, 52, pi. 17

Auricula neumayrL— _ _ _________________________________..._... 46,49,56

B

endlichi, Lioplacodes-- —-----...------------- .... —_._ — _ — — ——-—-_. 46,52

Unto-..-- ——.......................................................... 61

engelmanni, Corbula................ ____„_____._____ 46, 47, 58, p.. 17

Erdmann, C. E., collections by..._-----------.---------_-_------------___ 60

eulimoides, Goniobasis-__.___.„. —._____.. —..._.....—— 60, 6S, pj. 19

evanstonensis, Helicina..--------... _----...____-------_--.. — ___._-... — —. 50

F

Ferrer formation, molluscan faunaFisher, D. J., collections by..__

Bear River formation, molluscan fauna._______--__--_.___________ 45-46,47,48,49,50 G

bearensis, Mesocochliopa_____________________________________ 46,47, 49, 53, pi. 17

bellipicatus, UjiiO-.-.-.--.. .......____________.__._____________...... 46,47, 58, pi. 17 Geltena sp-____.__..._____ _— _._. — —____..——_- —————- — ---_- p'. 17

Brachydontes.- ___________________ —..........________............. 47 Geography,..____.._________._____._______..______.. 46-48

peali---.. .----.-.. — — . — .-.. —........................................ 46,57 globosa, Physa—------------------------------------------------ 46,48, 49,56, pf. 17

brachyopisthus, Unio.------- — ----- — - __________....______ 60,6^,pl.l9 Goniobasis eulimoides __________..______._______.____ 60, 63, p\ 19

Brannerillus---- _________________._____ — ___ — __—_____________________ 63 leedsensis.-------------------------------------------------------- 46,48,49,54

brimhallensis, Unio-___________________________......._.....__ 60, 61, pi. 18 subtortusa.---. ____......._______...._____....__._ 59, 61, 63, p'. 19

sp_——-_ ——— — - — —— ---- —— ------——----„ —— ------- —~-~. &\S4

G Gyraulussp-.—----- - -------------- - - --------- 46,47,52,51,57

Campeloma amarillensis-. ______________________.......____.._..... 59, 60,63,pi. 19 H

cokevillensis.-- ___._____......__________________..___ 46,48,49, 61, pi. 17

macrospira-__-_______._____........______._____ 46,47,49,5^,52 haldemanni, 7aptychius-.----. _______________..____ 46, 48, 55, pf. 17

rubeyi------ __._.__..._.______________________._......._....._. 46,49, 51, pi. 17 haydeni, Ostrea. _______ _____ — .. — _——————__ ————-———- 4(3,57

sp..-....— —..—-. —..-..-.--.-...-.......-......... 48,54,60,61, 63, pi. 19 Helkina cokeememis.- —-—— — — - —— — — ———— 46, 48, 49, 50, pi. 18

Charydrobia sp__.-.________________.________.._______.... 52 cretacea-.—..... .._...._____...________-_____ 46, 47, 49, 60, p?. 17

chrysalis, Pachychiloides-... __________________________ 46,55,pi. 17 evanstonensis--..... .____.__._______...______..——____ 50

chrysalloidea, Pachychiloides____....._____..._____.___ 46,49,55,pi. 17 humerosa, Pyrgulifera............ .______...___-_..____ 46, 49, 54, pT. 17

Clark, F. R., and G. W., collections by.—................................... 59 humerosa cokevillensis, Pyrgulifera..—-—_- — _—___--.—_— 46,48, 49, 64, p.. 18

clarki, Melampoides....-.----..________...___..__._.__. 46,47,48,56, pi. 17 Hunter Canyon formation, molluscan fauna..__...-----__.----.__-------...-- 6l>-61

cleburni, Pachychiloides—.... ......--..____________......._______ 46, 55, pi. 17 Hydrobia.____...___--...._-.---.._-...___---._._._.--__-.---__ 5:?, 63

Cokeville area, molluscan fauna__.-----...--_..._.__...---_.—________ 49

rocks.______-_------..._______.__.___...........___..__...._..._.. 49-50 I

cokevillensis, Campeloma.---.-- __________________.._....._.___ 46,48,49, 61, pi. 17

Helkina- _..._—__._____.___..__—_._———_____ _______ 46,48,49, 50, pi. 18 inflatus, Lioplacodes stachei-.. _____________—.——-—-.— 46, 48,49, 52, p.. 17

Mesocochliopa______.._....____________.________ 46,48,49,53,pi. 17 isoclina, Tornatellina.--.-........... ._______.______._ —— __ 46,4'),53

Pachychiloides----- _______...._...___._____......___ 46,49,55,pi. 18

Physa.---------------------------------------------------- 46,48,49,56, pi. 17 L

Pyrgulifera humerosa--—-- __----____________________ — _ — 46,48,49, 54, pi. 18

Viviparus------ ______________________..._____ __.... 46,48,49, 51, pi. 18 laembasalis, Tulotomops__...______..._____.._____... 60, 61, 63, 63, pT. 19

contractum, Parateinostoma--- —------------------------ ___________ 46,48,49,53 latentis, Parateinostoma.. -------------------------- _._.---___-_--. —. 46,48,49,53

convexa, Pseudarinia- _______ ___________________________._____ 51 Lee, W. T., collections by.________.__----- —— _—— — ——————- 611, 61

convexum, Parateinostoma... .-.-.----..________-.......-.-..--.... 46,48,49,53 Leeds Creek area, molluscan fauna... —— __—___ —— ___—-_._ — ---...___ 49

cretacea, Helkina.------------ ____-______________..._.______ 46,47,49, 50, pi. 17 leedsensis, Goniobasis................. ._____...——...__-__———— 46,48,49,5/J

Mesocochliopa.—---------------------- ___________.___.____._____... 53 Leggette, R. M., collections by._..__________._. — __— — __- — — ______ 60

CIor&.c;i.'a_ ______________________________ ..____________._______ ........______ 47 Lioplacodes.---- ___-_____________------__----_-_-----_.__------------- —... 53.57

durkee/_._.- — _ — _. — . — ———————_.______—————._____ 46, 58, pi. 17 endlichi...--------------------------------------------------------------- 45, 68

Corbula—--------------------.-__ — .___._———__ ——— __ ————_—______ 47 stachet................................................... 46,47, 48,49, 53, p\ 17

engelmanni-- ________________ — -._.________________.._.......___ 56,47, 58, pi. 17 attentuata.---------------------------------------------- 46, 47, 48, BS, pi. 17

pt/riformis-------------------------- ..-........_.................... 46,57,pl. 17 inflatus--..------—-.--- — - — - — --,--.--. — .-— 46, 48, 49, 52, p\ 17

subtrigonalis- ____-._.._____________.___......________________..... 60, 6S, pi. 19 veternus________-_--___...____-——____. — — - —.. —...--.-.__----_-_ 63

»Mfcate._ —— — — — — —- — — — . — „— — _..___..-_.- — — _____ 58 sp.-... —..-------. — -------------- — — --- 48, 54, 59, 61, 63, p.. 19

zurcheri— -.-.----_-.________.___-_...._.....-.___________..._________ 58 Lymnaea nitidula-------------------------- ___-_.---____---—..___----. 46,49,57

sp.______________________________________________ 57,58 sp______-_-___---_______—____ —— ----- —— - — -—————— 57

couesi, Viviparus-____________________________.__ 46,47,49, 61, pi. 17

cylindrica, Parftydro&za-..__________________..........._________.__....._ 46,48,49,53 M

D macilenta, Pachychiloides-- ___.._____._____....._- 46, 47, 48, 55, p.. 17

macilenta mimita, Pachychiloides----- _-....___------___-----.__ ———.__. 46,48,49

durkeei, Corbicula.--- __________________________________________________ 46, 58, pi.17 macrospira, Campeloma—-------------------------------------------- 46,47, 49, 61, 52

meeki,Rhytophorus.------- ____.. ——_—...___-_ —__—— — — — 46,48,49,56

E Melampoides clarki.. — ----------------------------------..-. 46, 47, 48, 56, pi. 17

sp__---------------------------- —— ------- — ---- —— ------ ————. —.- 56

Ecology..-.____ _ _ _ ____________________._____...________ 46-48 Melanoides sp._.__.__-...___———... ——————— -———————-———-- 54

elongata, Pyrgulifera stantoni.----—------------------------- 46, 48, 49, 54, pis. 17, 18 Mesaverde group, molluscana fauna.—— -_-_—--——_.----_-----------— .-.. 59-61

65
66 INDEX

Page 

mesaverdensis, Unto................................................. 60, 81, pis. 18,19

Mesocochliopa...............__............................................. 53

bearensis...................................................... 46,47,49, 52, pi. 17

cokevillensb........................................... -—-..46,48,49, S3, pi. 17

cretacea............................................. _______________... 53

sp———————.__ ——— ——— -_ __________--- —— __-_ — ——— __ 54

Mesoglypterpes sagensis-.-----------------.................................... pi. 17

sp..................................................................... 47,pi. 17

Mesolanistes............ _.____ — ___ —_—____ — __ -_ — _—___..._.... 63

reesidei....................................................____ 60, 83, pi. 19

Mesoneritina natidformis......................................... 46,47,48, 50, pi. 17

stantoni....................................................... 46,47,48, 50, pi. 17

sp— ......-........— — — .....--....„.....-....—................... 48,54

minuta, Pachychttoides macttenta........................................... 46,48,49

minutit, Anisopsis...... __.......____.__...._.___.__..-.....____ 46,48,49,57

Mount Garfield formation, molluscan fauna. —___ ——-_ — -____ —_.__... 60

N

natidformis, Mesoneritina.............. __________ — —..—_. 46,47,48, 50, pi. 17

Nelsen formation, molluscan fauna ______.........---.-.........._._._.... 60

NerUlna...................................................................... 50

neumayri, "Auricula"..................................................... 46,49,55

nitidula, Lymnaea......................................................... 46,49,57

O

occuha, Parateinosto ma......................................................... 46,55

Ostrea haydeni................................................................ 46,57

Pachychiloides chrysalis................................................. 46,55,pi. 17

chrysalloidea.-------............................................. 46,49,55, pi. 17

cleburni............................................................ 46,55, pi. 17

cokevillensis...................................................... 46,49,55,pi. 18

madlenta..................................................... 46,47,48.55,pi. 17

minuta............................................................ 46,48,49

turricula............................................................... 46,49,55

spp_ — - ——._....--- ——— .______. — ...-_____.-._______._- 49

Paraholmesianus Unto.............................................. 60, 61, pis. 18,19

Parateinostoma................................................................ 48

attispirale—.................................................. 46,47,48,56,pi. 17

contractum.......................................................... 46,48,49,53

consexum........................................................... 46,48,49,53

latentis.—.......................................................... 46,48,49,53

occulta.................................................................... 46,53

Parhydrobia cylindrka............. ____......________...___... 46,48,49,53

peali, Brachydontes............................................................ 46,57

Physa........................................................................ 56

cokesttlensis................................................... 46,48,49, 58, pi. 17

fflobosa........................................... 46, 48, 49, 56, pi. 17

utsitata-- —....................................................... 46,47,48,55

sp. A...——. — .._ — — — —— ———— — ——— ——— . ————— — ——— 48

sp. B.......—........................................................... 48

sp. ———— ————— ———— ————— ————— .——————__ 48, 54, 60, 84, pi. 19

planum, Sphaerium........................................................... 59, 82

praecursoris. Valvata................................................. 46,47,48.52,57

Price River formation, molluscan fauna.--______--___--_______-_--.-_-________ 59

priscus, Rhytophorus---------.......... _____._______.....___ 46,47,49,56

t7«io_ ——_.-_._-___._-_-__-_-__________-...--____ __.__,__. 59,61, 6S, pi. 19

Probythinella.................................................................. 63

Pseudarinia convexa... ____________________..._...____....___.___ 51

uniplica........... ...____—_________._____...... 46, 47, 50, pi. 17

pseudendlichi, Unto-...------------------------------------ GO, 81, pi. 18

Pyrgulifera.......... ...__-.___...._.___..._...._.._____..... 47

humerosa.........................................__._____-__._ 46,49, 54, pi. 17

cokevillensis.... — — .................................... 46,48,49, 54, pi. 18

stantoni........ ................................................. 46,49, 54, pi. 17

elongata............................................... 46,48,49, 54, pi. 17,18

sp.......——-___.._---..--______._........-.-_______........___________. 48

pyriformis, Corbula..-.......... ____________.______._...______ 46,57,pl. 17

Page 

Rhytophorus meeki.—.__-----_.-.-----..-_-.--.__——._.--_-_.-. 46,48,49,58

priscus......................................—..——.—.—-—-—-. 46,47,49,58

sp................-..----—- —. _____.___——.————————— 56

Rubey, W. W., cited.__._--.-..----------.-.--...-..-.— ........—-..._. 45-46

i, Campeloma.-................................................ 46,49,5/,pl. 17

sagensis, Mesoglypterpes................................———— — —————— pi. 17

Sphaerium planum........................................................... 59,61

sp..................................................................... 60,61,8?

Spieker, E. M., collections by.__-___..__-___._----.--———-----———— 59

stachei, Lioplacodes............................................ 46,47,48 49,52,'pl. 17

stachet attentuata, Lioplacodes.........................—.......... 46,47,48,5;.,pi. 17

stachei inflatus, Lioplacodes...--.................................. 46,48 49, 52, pi. 17

Stanton, T. W., collections by-..— —————— — ————— —— ———— — 60

stantoni, Mesoneritina...------------------.--.----.-.-...-----— 46,47.48,50,pi. 17

Pyrgulifera........... .......................................... 46,49,54,pi. 17

stantoni elongata, Pyrgulifera................................. 46,48,49, 54, pis. 17,18

Stratigraphic distribution of molluscan faunas, western Wyoming-.- — ——— 46 

subtortusa, Ooniobasis................................................ 59,61,ft*,pi. 19

subtrigonalis, Corbula-................................................ 60,8., pi. 19

sulcata, Corbula...............................................—.-..- — --_— 58

Teredinasp.............-----.----.----.---.------..—--——....— 61, ftS.pl. 19

Tornatellina................................. _____„—————-—————— 53

isodina..-.————— — -——.. —-————-———-—— 46, 49, 55

Trochispira...............-.............——..—...——————————... 5S

wyomingensis..............................—...........—. 46, 47, 49, 63, pi. 17

Tulotomops laevibasalis-..— ———— — ————..——— 60, 61, 62, 63, pi. 19

sp....—.....................———— ————————————— 59, 60, 61, ft?

turricula, Pachychiloides...— ........—. — ..................--............ 46, 49, 55

U

Unto amarillensis.---.-------------------------------- —--------------- .. 59, 60, 61

bellipicatus.................................................... 46, 47, 58, pi. 17

brachyopisthus.. —................................................ 60, 61, pi. 19

brimhallensb-.—......................................—........ 60, 81, pi. 18,

endlichi._____- — ——.--. —— —.,—_. ............ ———————— 61

mesaverdensis.......................................—————. 60, 61, pis. 18,19

paraholmesianus........................_____.-—————— 60, 61, pis. 18,19

priscus..-.-.-—...........................................—— 59, 61, 68, pi. 19

pseudendlichi......... —........................................... 60, 61, pi. 18

vetustus......................................................... 46, 48, 58, pi. 17

sp.—————— —— —— —— — —— — —— ——————————— 59, 60, 61

uniplica, Pseudarinia--............................................. 46, 47, 50, pi. 17

Unit C, molluscan fauna,-.-------——-- — - ——. —————— -———————— 45-46

Unit E, molluscan fauna.—---------------- ———. —————— -———————— 46

Ursirivussp......... .___—————..__———.——————————————— 57

usitata, Physa..........................................—............. 46, 47, 48, 58

V

Valvata.............................................-__————————————.. 57

praecurtsoris.---................................................ 46,47, 48, 5#, 57

sp—.—.—— — ————— ——————————————— 54, 59, 8«

veternus, Lioplacodes..... ... ____— — ___...— —————._———————.. 63

vetustus, Unto...........--.------.-------.-.--..---....----.--.---- 46, 48, 58, pi. 17

Viciparus cokevttknsis--.................................—.—.. 46, 48, 49, SI, pi. 18

couesi —.................................................... 46, 47, 49, 51, pi. 17

sp————— —————— ——— —————————————— 48,54,59

W

White, C. A., cited--.-- — -----------.----——-- — ------— — - 45

wyomingensis, Trochispira....................................... 46, 47, 49, 55, pi. 17

Yen, T. C., cited. 46

Reeside, J. B., Jr., collections by__—__...._._................. .___ 5 9

reesidei,Mesolanistes................................................... 60, 83, pi. 19

Zaptychtus haldemanni............................................. 46, 48, 55, pi. 17

zurcheri, Corbula.................................................. ——— — — 57
PLATES 17-19
	PLATE 17

FIGURE 1. Viviparus couesi White (p. 51). Locality 12. X 1.

2. Campeloma cokevillensis Yen (p. 51). Locality 8. X 1.

3. Campeloma rubeyi Yen (p. 51). Locality 10. X 1.

4, 5. Pachychiloides cleburni (White) (p. 55). Locality 12. X 1.

6, 7. Pachychiloides cf. P. chrysalloidea (White) (p. 55). Locality 12. X 2.

8, 9. Pachychiloides chrysalis (Meek) (p. 55). Locality 10. X 2.

10, 11. Pachychiloides macilenta (White) (p. 55). Locality 12. X 2.

12, 13. Pyrgulifera humerosa (Meek) (p. 54). Locality 12. X 1.

14, 15. Pyrgulifera stantoni White (p. 54). Locality 10. X 1.

16. Pyrgulifera stantoni elongata Yen (p. 54). Locality 8. X 4.

17. Lioplacodes stachei (White) (p. 52). Locality 8. X 2.

18. Lioplacodes stachei attentuata Yen (p. 52). Locality 8. X 2.

19. Lioplacodes stachei in flatus Yen (p. 52). Locality 8. X 2.

20, 21. Lioplacodes stachei (White) (p. 52). Locality 11. X 2.

22. Parateinostoma altispirale Yen (p. 53). Locality 11. X 8.

23. Mesoneritina stantoni (White) (p. 50). Locality 11. X 2.

24. Mesoneritina naticiformis (White) (p. 50). Locality 11. X 2.

25-27. "Helicina" cretacea Yen (p. 50). Locality 11. X 4.

28-30. Mesoglypterpes sp. undet (p. 47). Locality 11. X 4.

31-33. Mesoglypterpes cf. M. sagensis Yen. Locality 11. X 4.

34, 35. Mesocochliopa cokevillensis Yen (p. 53). Locality 8. X 4.

36-38. Mesocochliopa bearensis Yen (p. 52). Locality 11. X 8.

39-44. Trochispira wyomingensis Yen (p. 53). Locality 11. X 4.

45-47. Amnicolal sp. undet (p. 63). Locality 11. X 2.

48. Zaptychius haldemanni (White) (p. 55). Locality 8. X 4.

49. Zaptychius haldemanni (White) (p. 55). Locality 11. X 4.

50. Pseudarinia uniplica Yen (p. 50). Locality 11. X 8.

51. Melampoides clarki (White) (p. 56). Locality 11. X 4.

52. Physa cokevillensis Yen (p. 56). Locality 8. X 4.

53. Physa globosa Yen (p. 56). Locality 8. X 4.

54-56. Corbicula durkeei (Meek) (p. 58). Locality 12. X 1.

57,58. Corbula engelmanni Meek (p. 58). Locality 12. X 1.

59-61. Corbula pyriformis Meek (p. 57). Locality 12. X 1.

62. Unio belliplicatus Meek (p. 58). Locality 12. X 1.

63. Unio vetustus Meek (p. 58). Locality 12. X 1.

64. Geltenal sp. undet. Locality 12. X 1.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 254 PLATE 17

62

UPPER CRETACEOUS NONMARINE MOLLUSKS FROM WYOMING
GEOLOGICAL SURVEY PROFESSIONAL PAPER 254 PLATE 18

14

UPPER CRETACEOUS NONMARINE MOLLUSKS FROM UTAH AND COLORADO
PLATE 18

FIGURE 1. Pyrgulifera humerosa cokevillensis Yen (p. 54). Locality 10. X 2.

2. Pyrgulifera stantoni elongata Yen (p. 54). Locality 6. X 2.

3,4. Pachychiloides cokevillensis Yen (p. 55). Locality 8. XL

5-7. "Helicina" cokevillensis Yen (p. 50). Locality 8. X 1.

8. Viviparus cokevillensis Yen (p. 51). Locality 8. XL

9. Unio paraholmesianus Yen (p. 61). USGS Mesozoic locality 13970. X 1.

10, 11. Unio mesaverdensis Yen (p. 61). USGS Mesozoic locality 13969. X 1.

12. Unio cf. U. brimhallensis Stanton (p. 61). USGS Mesozoic locality 13682. X 1.

13, 14. Unio pseudendlichi Yen (p. 61). USGS Mesozoic locality 13970. X 1.
	PLATE 19

FIGURES 1, 2. Amnicola sp. undet (p. 63). USGS Mesozoic locality 4184. X 2.

3. Amnicola sp. undet (p. 63). USGS Mesozoic locality 4214. X 2.

4. Amnicola sp. undet (p. 63). USGS Mesozoic locality 4195. X 2.

5, 6. Goniobasis^ subtortuosa Meek and Hayden (p. 63). USGS Mesozoic locality 4214. X 2.

7. Amnicola sp. undet (p. 63). USGS Mesozoic locality 13682. X 2.

8. Goniobasis cf. G. eulomoides (Meek) (p. 63). USGS Mesozoic locality 4188. X 2.

9, 10. Teredina sp. undet (p. 62). USGS Mesozoic locality 4486. X 1.

11, 12. Campeloma sp. undet (p. 63). USGS Mesozoic locality 13969. X 1.

13-15. Lioplacodes sp. undet (p. 63). USGS Mesozoic locality 4214. X 1.

16, 17. Lioplacodes sp. undet (p. 63). USGS Mesozoic locality 4184. X 1.

18, 19. Physa sp. undet (p. 64). USGS Mesozoic locality 4195. X 1.

20, 21. Lioplacodes sp. undet (p. 63). USGS Mesozoic locality 4486. X 1-

22. Campeloma amarillensis Stanton (p. 63). USGS Mesozoic locality 4184. X 1.

23. Campeloma amarillensis Stanton (p. 63). USGS Mesozoic locality 13682. X 1.

24-26. Tulotomops laevibasalis Yen (p. 62). USGS Mesozoic locality 13764. X 1.

27, 28. Mesolanites reesidei (Stanton) (p. 63). USGS Mesozoic locality 4195. X 1.

29. Corbula subtrigonalis Meek and Hayden (p. 62). USGS Mesozoic locality 13764. X 1.

30. Unio cf. U. prisons Meek and Hayden (p. 62). USGS Mesozoic locality 4486. X 1.

31. Unio paraholmesianus Yen (p. 61). USGS Mesozoic locality 13970. X 1.

32. Unio brachyopisthus Stanton (p. 61). USGS Mesozoic locality 13682. X 1.

33, 34. Unio mesaverdensis Yen (p. 61). USGS Mesozoic locality 13969. X 1.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 254 PLATE 19

UPPER CRETACEOUS NONMARINE MOLLUSKS FROM UTAH AND COLORADO