Late Cenozoic 

Molluscan Faunas 

From the High Plains

GEOLOGICAL SURVEY PROFESSIONAL PAPER 337
Late Cenozoic 

Molluscan Faunas 

From the His:h Plains

By DWIGHT W. TAYLOR

GEOLOGICAL SURVEY PROFESSIONAL PAPER 337

Description of mo Husks from nine Pliocene and 

Pleistocene faunas of the High Plains region 

and interpretation of their stratigraphic and 

ecologic significance

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1960
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

The U.S. Geological Survey Library has cataloged this publication as follows :

Taylor, Dwight Willard, 1932-

Late Ceiiozoic molluscan faunas from the High Plains. 

Washington, U.S. Govt. Print. Off., 1959.

iv, 94 p. illus., 4 plates, tables. 30 cm. (U.S. Geological Survey. 

Professional paper 337)

"Description of mollusks from nine Pliocene and Pleistocene faunas 

of the High Plains region and interpretation of their stratigraphic and 

ecologic significance."

Bibliography: p. 83-86.

1. Mollusks, Fossil. 2. Paleontology Cenozoic. 3. Paleontology 

U.S. High Plains region. I. Title. (Series)

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

Washington 25, D.C. - Price 31 (paper cover)
CONTENTS

Page

Abstract- __________________________________________ 1

Introduction _______________________________________ 1

Acknowledgments. _ __________________________________ 2

Methods. __________________________________________ 2

Collecting methods. _____________________________ 2

Environmental interpretations of sediments ________ 3

Environmental interpretations of fossil mollusks _ _ _ _ 3

Previous work__________________________________ 4

Principles of paleoecologic interpretation-__________ 4

Difficulties of paleoecologic interpretation._________ 5

Specific identification of shells ____________________ 5

Recognition of limiting factors____________________ 5

Inadequacy of habitat and distributional data__-__- 7

Unsatisfactory taxonomy._______________________ 8

Methods of faunal interpretation _________________ 8

Age determination ______________________________ 9

Faunal dating__________________________________ 9

Local faunas.______ ____________________________ 10

Comparison of faunas. _______________________________ 11

Summary of faunal sequence _________________________ 14

Correlation of North American ages with Lyellian epochs. 18

Summary of depositional and biological sequence. __ 18

Correlation ____________________________________ 19

Description of local faunas___________________________ 22

Buis Ranch local fauna__________________________ 22

Saw Rock Canyon local fauna____________________ 22

Red Corral local fauna._________________________ 25

Rexroad local fauna..____________________________ 27

Bender local fauna-_ ____________________________ 31

Sand Draw local fauna__________________________ 32

Dixon local fauna_____________________________ 36

Page

Sanders local fauna____________--_--_-_--_______ 40

Deer Park local fauna-__________________________ 41

Recent mollusks from northern Nebraska,_____________ 42

Localities- _ ____________________________________ 42

Habitats_____-___------------------------------ 43

Species found at the northern Nebraska localities- _ _ 44

Systematic descriptions._____________________________ 44

Class Pelecypoda.__-____--_____--_------_-----_ 45

Family Unionidae___________________________ 45

Family Quadrulidae_---_-_--------__-------- 45

Family Sphaeriidae_________________________ 45

Class Gastropoda.______________________________ 48

Family Valvatidae______________-_---_---___ 48

Family Viviparidae_____________-__--__--___ 49

Family Hydrobiidae-_____-_----_-------_--_- 49

Family Carychiidae.________________________ 51

Family Lymnaeidae_________________________ 52

Family Planorbidae._____--_-___-_----___-__ 56

Family Ancylidae____________------___---___ 61

Family Physidae__________________________ 62

Family Strobilopsidae-_-__----------------_- 65

Family Pupillidae_ ________________________ 67

Family Valloniidae________________________ 76

Family Cionellidae_____________-------______ 77

Family Succineid.ae_________-_-__----_--____ 77

Family Endodontidae___________-__----_-___ 79

Family Limacidae_ _________-_-____----_-___ 80

Family Zonitidae___________________________ 80

Family Polygyridae_________________________ 82

Literature cited---__________-____-_------_------_--_ 83

Index.__________________________-___--_-----_-____ 87

ILLUSTRATIONS

[Plates follow index]

PLATES 1-4. Late Pliocene and Pleistocene mollusks from the High Plains.

FIGURE 1. Summary of late Cenozoie faunal, climatic, and lithologic sequences in southwestern Kansas, and correlation of 

other local faunas from the High Plains-__________--___________--___-----_----_----_---.------------

2. Frequency distributions of Pliocene Gastrocopta cristata group________--_____-_-___------_-------------

TABLES

TABLE 1. Abundance or occurrence of gastropods in collections of Saw Rock Canyon local fauna._-_---_---_---------

2. Stratigraphic occurrence of mollusks of some late Cenozoie faunas in the High Plains__________-----_-_---

3. Summary of data from table 2_ _______________________________________---__-___----_----------------

4. Faunal similarities-___________________________________________________________--_----_--_----------

5. Distribution of thermally significant species in late Pliocene and early Pleistocene faunas of the High Plains-_

6. Correlation of middle Pliocene to lower Pleistocene deposits in Italy and the High Plains. ______------------

ni

Page

15

68

Page 

3

12

13

13

13

21
IV CONTENTS

Page 

TABLE 7. Comparison of Blancan and Recent molluscan faunas of southwestern Kansas, by habitats__ ___-_-_-_____-_-__ 24

8. Habitat indications of mollusks of Saw Rock Canyon local fauna.-_____.________________-__-.--___-_--___-_ 25

9. Habitat indications of mollusks of Red Corral local fauna________________________________________________ 26

10. Comparison of mollusks of Red Corral local fauna with Recent mollusks from Palo Duro Canyon, Tex., by

habitats__ _____-________________________________________________-_-_______...-_-_--_---_-_.---.-___.--- 26

11. Locality occurrence of mollusks of Rexroad local fauna____________________________--_-----_-----_ _______ 29

12. Habitat indications of mollusks of Rexroad local fauna__-__________________________-------------------__- 30

13. Habitat indications of Bender local fauna______ ______________________ _______ __________-____-_-___-__--_ _ 32

14. Habitat indications of mollusks of Sand Draw local fauna________________________________________________ 35

15. Comparison of Sand Draw local fauna and Recent mollusks from northern Nebraska.,_^_______-___-_________ 36

16. Occurrence of supposed Nebraskan index fossils.________________________________________________________ 38

17. Habitat indications of mollusks of Dixon local fauna_____________________________________________________ 39

18. Comparison of mollusks of Dixon local fauna with those living in Kingman County, Kans., by habitats._______ 39

19. Habitat indications of mollusks of Sanders local fauna_________________.__________ ---------_-__---_----_ 41
LATE CENOZOIC MOLLUSCAN FAUNAS FROM THE HIGH PLAINS

By D. W. TAYLOR

ABSTRACT

Mollusks are described from nine late Cenozoic assemblages 

in the High Plains region: the late middle Pliocene Buis 

Ranch local fauna of northwestern Oklahoma; the late 

Pliocene Saw Rock Canyon, Rexroad, and Bender local faunas 

of southwestern Kansas; the late Pliocene Red Corral local 

fauna of the Panhandle of Texas; the early Pleistocene Dixon, 

Deer Park, and Sanders local faunas of southern Kansas; and 

the early Pleistocene Sand Draw local fauna of north-central 

Nebraska. In nearly all assemblages associated mammals 

provide an independent age determination. The control provided by fossil mammals and stratigraphie succession permits 

evaluation of the mollusks for age determination and correlation. Vertebrates and mollusks are complementary, and never 

antagonistic, in giving age and ecologic information.

The late Pliocene and Pleistocene faunal sequence of southwestern Kansas and northwestern Oklahoma is especially 

significant for regional and intercontinental correlation because 

it is the most nearly complete sequence known from such a 

small area. Collecting the great number of specimens and 

species which represent these faunas has been possible by 

washing large quantities of fossiliferous matrix through 

screens. Eeologic interpretation of the mollusks is combined 

with other information from the vertebrates and inferences 

from the depositional sequence to summarize the late Pliocene 

and Pleistocene climatic and faunal sequence of southwestern 

Kansas.

Fossils from three horizons in the Rexroad formation indicate a relatively long interval in which the climate was warmtemperate, equable, and relatively moist. Above these assemblages the depositional and erosional sequence, and several 

faunas, indicate 4 periods of erosion and deposition of coarse 

clastic sediments in cool climates separated by 3 periods of 

deposition of finer materials during warmer climates. The 

alternate warm and cool climates are correlated with the 

Mississippi Valley interglacial and glacial ages. The Ballard 

formation, which is separated from the Rexroad formation by 

an erosional unconformity and contains the earliest evidence 

of marked climatic cooling, is correlated with the earliest 

Pleistocene sediments of the area in central Italy selected by 

the 18th International Geological Congress as definitive for the 

Pliocene-Pleistocene boundary.

The successive phases in the history of North American 

land mammals which have been called the Blancan, Irvingtonian, and Rancholabrean ages can be correlated with the 

Pliocene and Pleistocene sequence of southwestern Kansas, 

and thus indirectly with the glacial-interglacial intervals of 

the Mississippi Valley. The Blancan is late Pliocene and 

early Pleistocene. The Blancan-Irvingtonian boundary is

about in the middle of the Kansan age, and the IrvingtonianRancholabrean boundary about in the middle of the Illinoian 

age.

INTRODUCTION

In the spring of 1936 M. K. Elias visited a Civilian 

Conservation Corps quarry in Meade County, southwestern Kansas. Questioning the workmen about the 

possible occurrence of fossil bones;,-he was given specimens which he brought to the University of Kansas. 

Claude W. Hibbard and a University of Kansas Museum of Vertebrate Paleontology field party, acting 

on this information, returned to the area in 1936 

(Hibbard, 1941, p. 81). Fossils collected at this 

original locality and exploration of the Meade County 

region in general subsequently have produced almost 

an overabundance of paleontological riches. Intensive 

study by Hibbard and parties from the University 

of Kansas (1936-46) and University of Michigan 

(1947 to date) has resulted in the discovery of the 

most nearly complete sequence of late Pliocene and 

Pleistocene faunas in a small area known anywhere. 

The washing technique developed by Hibbard (1949c) 

is largely responsible for this great success in collecting; the method permits rapid recovery of 90 

percent or more of the bones and shells in a fossiliferous deposit. The various animal groups so obtained birds, mammals, salamanders, frogs, toads, 

lizards, snakes, turtles, fishes, and mollusks provide 

a basis for reconstructing in considerable detail the 

changes in climate and animal life during the late 

Cenozoic.

This paper is concerned primarily with the description and interpretation of the late Pliocene and early 

Pleistocene molluscan faunas of southwestern Kansas. 

Several other assemblages are included for the sake 

of completeness: the early Pleistocene Dixoii local 

fauna from south-central Kansas and the Sand Draw 

local fauna from north-central Nebraska; and the 

middle Pliocene Buis Ranch local fauna from northwestern Oklahoma. In ecologic and stratigraphie discussion of the faunas both vertebrate and invertebrate 

evidence is considered. Thus although the systematic
LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

paleontologic description is limited to the mollusks, 

the faunal interpretations are synthetic.

Earlier work on the various faunas is summarized 

under the description of each. The history of this 

study may be noted here, however. As a member of 

a University of Michigan Museum of Paleontology 

field party under Hibbard in the summer of 1950 I 

had opportunity to see at firsthand the process of 

mass screen-washing of fossils, to learn the advantages and disadvantages of the method, and to study 

the local stratigraphy of southwestern Kansas and 

western Oklahoma. In the summer of 1953,1 collected 

Pleistocene and Recent mollusks and stratigraphic 

data in northern Nebraska for 2 weeks and spent 

another week in southwestern Kansas to see newly 

discovered faunal sites. Detailed examination of the 

fossils was made at the University of Michigan in 

1952-53, University of California from 1953-55, and 

the U.S. National Museum in 1955-56.

ACKNOWLEDGMENTS

All landowners freely gave permission to work and 

collect on their property. For this aid thanks are 

due Oscar Booth, Orville Galbraith, Ray Keim, Frank 

Law, and Loyd Schnabel, of Ainsworth, Nebr.; H. 

C. Bender, Plains, Kans.; Arthur D. Sanders and 

Jack T. Sanders, Meade, Kans.; Mrs. Gladys Dixon, 

Spivey, Kans.; and Richard Dixon, Cleveland, Kans.

The line drawings of plate 1 are by Miss Joan 

Sischo, University of California Museum of Paleontology.

E. S. Richardson, Jr., Chicago Natural History 

Museum, C. W. Collinson, Illinois Geological Survey, 

and Henry van der Schalie, University of Michigan 

Museum of Zoology, loaned material for examination.

H. B. Herrington, Keene, Ontario, Canada, identified the Sphaeriidae and gave ecologic interpretations 

of them.

The systematic treatment of several groups of gastropods has benefited from discussions with P. F. 

Basch and J. B. Burch, University of Michigan Museum of Zoology, J. P. E. Morrison, U.S. National 

Museum, and H. E. Walter, Liberian Institute of 

Tropical Medicine, Harbel, Liberia.

D. E. Savage, University of California Museum 

of Paleontology, contributed advice and stimulating 

discussion of the principles of correlation, stratigraphy, and mammalian paleontology.

Most of all I am indebted to Claude W. Hibbard, 

University of Michigan Muecum of Paleontology. He 

introduced me to the late Cenozoic sequence of southwestern Kansas and northwestern Oklahoma in 1950, 

and since that time has collaborated closely by securing funds for sorting fossils and by contributing 

advice and criticism.

METHODS

COLLECTING METHODS

The fossil mollusks reported here were collected 

almost entirely by the washing technique described 

by Hibbard (1949c). Poorly consolidated or unconsolidated sediments with surface exposures of fossils 

were collected in as large pieces as practicable. After 

thorough drying (especially important with clay or 

marl sediments) the matrix was washed through a 

16-mesh screen. It was found desirable to station 

someone with a finer screen downstream from the 

washers to catch small fossils which passed through 

the 16-mesh screen and floated away. The small fossils 

which did not float were lost. Use of a smaller mesh 

would insure recovery of all the fossils, but this slows 

washing and also hinders sorting by leaving more 

matrix in the washers.

Adult shells of only 3 of the species considered here 

will pass through the 16-mesh screen: CarycJiium 

exiguum, Gastrocopta Jiolzingeri, and Vertigo milium. 

In addition the shells of other species of Gfastrocopta, 

such as G. cristata and G. procera, may pass through 

the screens if the shells are slightly smaller than the 

mean or if there are bent wires in the screens which 

create larger gaps than usual. Not all these smaller 

shells will go through the screens, however, because 

only the minor axis is less than the mesh size. Shells 

which are kept flat on the bottom or sides of the 

washers will tend to stay in them, while those which 

are agitated and turn perpendicular to the screen will 

pass through.

In rewashing the 16-mesh concentrate in the laboratory, it was found that only CarycJiium and Gastrocopta Jiolzingeri passed through a 20-mesh screen. 

Probably, therefore, the relative abundances for these 

species are low.

The advantage of washing matrix is that an essentially complete representation of the fossil fauna is 

obtained. By this method Hibbard (1949c) has obtained several faunas including amphibians, reptiles, 

birds, mammals, mollusks (including snail eggs) and 

ostracodes, as well as the zygospores of CJiara.

In collecting it was found that the larger shells 

were particularly fragile. This is partly because they 

are relatively weaker than small shells, and partly 

because they are more likely to have become cracked 

or broken in the ground or in the removal of blocks 

of matrix. Accordingly, surface exposures were usually examined for the larger shells before collecting 

matrix for washing. Large shells found in the washers were removed as soon as possible.
METHODS

The amount of matrix needed to give a fair sample 

of the fossils is large, probably at least 20 sacks (about 

2,500 Ibs), as suggested by Hibbard (1949c, p. 11). 

The completeness of representation may be increased 

by sampling from several spots in the fossiliferous 

locality. Table 1 shows relative abundance of the 

species in University of Michigan collections from the 

Saw Rock Canyon locality, with the forms reported 

by Frye and Leonard (1952) added for comparison. 

It should be noted that all collections were made in 

the same way by C. W. Hibbard and that as nearly 

as possible the same spot was sampled. The combined 

1950-52 collections naturally have more material and 

more species than those of the 1947 collection. The 

chief conclusion is that no single collection contains 

all species present, and that a large amount of matrix 

should be washed.

TABLE 1. Abundance or occurrence of gastropods in collections 

of Saw Rock Canyon local fauna

[A, abundant (>250); C, common (41-250); S, scarce (6-40); R, rare (1-5); 

X, occurrence]

Species

University of 

Michigan collections

1947

S

S 

C

c 

c

s 

s

R 

R

R

R 

R

R

1950,1952

R

A 

S 

R 

C 

A

A 

A 

A 

A

S

S 

S

s

R 

A

R 

C 

C 

R

S 

R

Reported 

by Frye 

and 

Leonard 

(1952, 

p. 151, 

Seward 

County 

locality)

X 

X 

X 

X

X 

X 

X 

X

X 

X 

X

X 

X

X 

X

X 

X

X

ENVIRONMENTAL INTERPRETATIONS OF 

SEDIMENTS

The present study is primarily paleontologic and 

stratigraphic, but two probable inferences from a 

study of the sediments supplement the fossil evidence. 

These interpretations are that gravel deposits in 

southwestern Kansas imply a greater volume of stream 

flow at the times when they were laid down and that 

caliche indicates a semiarid climate more probably 

mesothermal than microthermal.

The six Pliocene and Pleistocene formations of 

southwestern Kansas and western Oklahoma, from the

Ogallala to the Vanhem formation, each grade from 

gravel and coarse sand at the base to finer sediment 

at the top. The coarse basal gravels differ from one 

unit to another, however, not only in composition but 

in grain size (Byrne and McLaughlin, 1948, p. 80), 

although the finer sediments are similar. These differences suggest not only changes in stream carrying 

power within a depositional interval, but also differences in maximum carrying power between these intervals. The early Pleistocene coarse sand and pebble 

gravel units [Angell member of the Ballard formation, and the Stump Arroyo member of the Crooked 

Creek formation] are coarser than the sand and grit 

in the base of the Rexroad formation and include rocks 

of Rocky Mountain provenance. Such records of transport of more and coarser material than is being moved 

by the Cimarron River today suggest greater precipitation in the Rocky Mountains and probably also 

in the Plains.

The origin of caliche has been studied by Brown 

(1956). He concluded that in the northeastern Llano 

Estacado caliche recorded lime enrichment of the Chorizon of pedocal soils in an eolian aggrading profile. 

Such lime enrichment occurs in soils of both subhumid 

and semiarid environments. Caliche is left behind 

by evaporation, therefore a warmer climate will favor 

such precipitation but is not necessary. The more 

frequent occurrence and more conspicuous development of caliche in the southern than in the northern 

High Plains further strengthens such an idea. Following is part of Brown's summary concerning the 

origin of caliche (Brown, 1956, p. 14) :

The mechanics of formation appear to be as follows: The 

wind and rain bring in all the materials that form the soil 

and its associated caliche and deposit these materials on the 

soil surface. The CaCO3 and silica gel are leached downward 

by percokiting rainwater and deposited as a subsurface 

evaporite, largely as molds around roots and organisms that 

separated the clastic particles. This inception of lithiflcation 

may be interrupted and the deposits destroyed by descending 

water following subsequent heavy rains, but eventually they 

will become permanent.

ENVIRONMENTAL INTERPRETATIONS OF FOSSIL 

MOLLUSKS

Since almost the first days of paleontology, fossil 

mollusks (especially those of the Cenozoic) have been 

used as a basis for inferring the conditions under 

which rocks were laid down. The early discovery 

that the distribution patterns of many living animals 

and plants changed radically in the Pleistocene contributed greatly to the theory of glaciation. The uniformitarian assumption has been made that the habitat 

preferences of species have been the same throughout 

their span of existence from then until now. Pond
LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

snails of today lived in ponds of the Pleistocene; clams 

of gravelly stream beds have always preferred these 

situations. This basis for interpreting the local habitat of fossil shells remains unquestioned and valuable.1 

The story is otherwise with the inferences of past 

climates, however. Workers have disagreed as to how 

specifically one can interpret former climates and too 

little attention has been given to the large number 

of factors which make up climate.

PREVIOUS WORK

Many earlier attempts at paleoecologic interpretations of Pleistocene fossils and deposits have been of 

dubious value, or so generalized as to be of little help 

to geologists and stratigraphers. This circumstance 

has been the result of uncertain stratigraphic position 

of fossils, inadequate data on pre-Wisconsin physical 

features, and the fact that so many of the known 

fossils represent animals of little paleoecologic value 

horses, bison, camels, and wide-ranging snails. Probably for these reasons Flint (1947, p. 52-1) was led 

to the pessimistic conclusion that "* * * the ecologic 

interpretations placed on most of the plants and animals in the record manifestly can never be more than 

approximate at best. In consequence few major inferences as to Pleistocene climates rest on fossil evidence 

alone. The chief value of fossil data is in strengthening inferences drawn from evidence of quite other 

kinds".

Flint's conclusion is valid for most previous work 

on the Pleistocene. More detailed work on stratigraphy and fossils, particularly in nonglaciated regions of now semiarid climates, will almost surely 

yield significant information on climatic changes unobtainable from physical features. The study and joint 

use of various animal groups, and collection of adequate samples of material, is a prerequisite for these 

results, however. Reliance on only one group, such 

as mollusks or mammals, cannot help but give an 

incomplete and hence distorted picture.

Only four general reviews of the ecological applications of Pleistocene nonmarine mollusks are known 

to me those of Shimek (1913), Geyer (1922), Baker 

(1937), and Eiseley (1937).

Shimek's paper is useful for information on the 

depositional environment of loess, and especially for 

comparison of fossil assemblages and drift shells from 

modern lakes and streams. Subsequent information 

has outmoded his conclusions on stratigraphic and 

climatic interpretations, however.

Geyer's (1922) essay "Die Quartarmollusken und 

die Klimafrage" (Quaternary mollusks and climate)

1 For summaries see Baker (1937) and Yen (1951).

is a searching study of the subject which unfortunately 

seems to have passed unnoticed by American paleontologists. The paper deals with German postglacial 

nonmarine mollusks, and attempts to answer the 

question: "Have climatic changes taken place between 

the Pleistocene and the present, and in what direction 

have they occurred?-' (p. 73).

Geyer's conclusions are that the climate suggested 

by the fossils as a whole was moist and oceanic, for 

there are occurrences in central Germany of species 

now living only closer to ocean coasts. Furthermore, 

there are today associations of species with different 

climatic requirements, but these associations are now 

found in western rather than in central Europe. In 

general, however, a fossil assemblage can give only a 

picture of local conditions of environment humidity, 

vegetation, soil, and microclimate which have nothing to do directly with climate. Geyer's ideas are 

discussed in more detail later in this section.

Baker's (1937) summary of Pleistocene nonmarine 

mollusks is valuable chiefly for the section on habitat 

interpretation. That dealing with climatic inference 

sums up Baker's general conclusions, but lacks an adequate treatment of the method involved. "Mollusca 

as indicators of time"" overrates the stratigraphic utility of the group. Baker recognized as species and 

subspecies shell forms which are only ecological variants, and relied too heavily on the completeness of 

the geological record.

Eiseley (1937), like Geyer, dealt with the application of mollusks to archeology. He discussed problems 

of a smaller scale than those of this report, problems 

which arise late in the Pleistocene.

PRINCIPLES OF PALEOECOLOGIC INTERPRETATION

It should again be emphasized that paleontologists 

make an assumption that species have been influenced 

in former periods by the same limiting factors and 

to the same degree as they are now. Species certainly 

could have changed in this respect, and one must 

always be aware of the possibility. In the late Cenozoic molluscan faunas studied in this paper, evidence 

for such changes is rare and doubtful.

The generally accepted principles used in the interpretation of late Cenozoic fossil mollusks may be 

summed up as follows: Interpretations based on fossil 

shells are governed by the present-day distribution 

of the various species, and their association with each 

other and with various kinds of habitats and climates. 

Fossil shells similar to those of living forms are assumed to represent the same species. Furthermore, 

these species are believed to have been subject to the 

same limiting: factors of distribution then as now.
METHODS

DIFFICULTIES OF PALEOECOLOGIC INTERPRETATION

Attempts to apply these principles encounter several 

difficulties: Some groups of mollusks are not identifiable by shell alone; recognition of limiting factors 

is most uncertain; habitat and distributional data are 

poor for many species; taxonomy of living nonmarine 

mollusks is unsatisfactory for many groups.

SPECIFIC IDENTIFICATION OF SHELLS

In most nonmarine mollusks the shell is the basis 

for specific identification, although not for classification of higher categories. In some families, such as 

the Pupillidae, the shell is probably a much better 

guide than are anatomical data. In other groups, 

however, such as the Zonitidae, Succineidae, and Hydrobiidae, shells are of distinctly secondary value 

and may not be characteristic of species or even genera. 

In the late Cenozoic faunas of the High Plains the 

Succineidae are the only common group with this 

disadvantage.

RECOGNITION OF LIMITING FACTORS

Unfortunately there is no experimental evidence 

determining limiting factors of distribution. Inferences as to what they may be must come from knowledge of the geographic distribution of the species and 

from collecting experience. Isolated occurrences may 

also be especially valuable in giving clues to such significant factors.

Virtually all previous workers concerned with factors determining distributions of nonmarine mollusks 

within an accessible area have seen them in part or all 

of the interacting complex of soil, climate, and vegetation. Other factors may be significant, but there is 

no good evidence for their operation as yet.

Geyer (1922) contended that the distribution of 

nonmarine mollusks is governed primarily by moisture. Occurrence and abundance of species are determined by the modifying effects 011 climate of local 

environment, topography and drainage. He stated 2

( P. ra-ri):

In attempts at solving climatic problems (my own not excepted), the concept of climate was regarded one sidedly. 

It was essentially the same as temperature. Climate, however, is a multi-faceted and complex quantity. Warmth is 

certainly a necessity for all life, bnt only one aspect of climate. 

It affects the worldwide distribution of mollusks, but in our 

homeland f Germany] mollusks depend more obviously on 

water than on temperature. What Diels said about plants 

may be applied to mollusks without restriction: 'Water determines the organism's possibility of existence. It directs its 

growth and is the most important factor which influences and

1 Translated from the original German.

bounds its habitat on the earth. Thus the reproduction and 

hence the continuity, indeed the physiognomy of whole floras 

(and faunas) depends on water. But it also decides, in an 

infinite number of cases, the significance of a species within 

an association, its dispersal ability in a region and therefore 

the limits of its natural distribution.' Land snails are 'moist 

air animals.' Their life processes go on under the direct 

influence of water. Winter temperatures are unimportant as 

limiting factors; the snails hibernate in the soil like plants. 

During the summer warmth, however, there are interruptions 

by drought.

Whatever the sun and clouds grant to the earth does not act 

directly on the biosphere (perhaps aside from light, which 

affects the color of mollusks), but only through the medium 

of the soil the local habitat. It is not the amount of rain 

which falls from the clouds that the organisms receive. They 

benefit from only as much as the soil can hold and pass on. 

Likewise snails live not by the radiant heat of the sun, which 

they quickly avoid in most cases, but by the warmth which 

the soil has taken up and transmits to them. Climate is the 

source of energy for life; soil is the transmitter, storage 'battery, and transformer.

In studying the climate with the help of mollusks, then, one 

must turn primarily to the soil on which they lived. Soil, 

however, is just as complex a quantity as climate. Furthermore, these two factors, climate and soil, interact, displace 

and supplement each other reciprocally, so that their influence 

on the biota is very difficult and often impossible to analyze 

and determine separately. How much warmth and moisture 

can tJie soil absorb for storage and transmission? That is 

the first question for all climatic research. In this way all 

other influences are considered: geographic position (latitude, 

elevation, and distance from the sea), formation, condition, 

and structure of the soil, angle of inclination and direction 

(exposure and insolation), irrigation, precipitation, humidity, 

wind, vegetation, cultural stage of the landscape and most recent geological history. In summary, the ecological bases of 

molluscan life must be determined as far as circumstances 

permit. They may be divided into local environmental and 

climatic factors. Only if the habitat is known can the influence of climate be sought.

The mediating influence of the soil bars us, he said, 

from being able to determine much about climate. 

What we see is the resultant of many factors working 

together.

The local habitat demands adaptation. Stable species join 

it through selection, the variable ones by modification to given 

circumstances. The adaptation influences the faunal composition. Thus each locality will give its assemblage a special 

aspect according to the mixture of species and ecological 

forms. From the aspect of a fossil assemblage the significant 

local conditions can be determined which have given this characteristic. They hare nothing to do directly ivith the climate. 

(Geyer. 1922, p. 88.)

Geyer"s conclusions from the German nomiiarine 

mollusks probably hold true for parts of North America, and for many mollusks. But there are many different patterns of distribution among the species 

studied in this report, some of which seem controlled 

by temperature extremes, others by soil and available
6 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

moisture. These patterns may be grouped most broadly 

into five categories, with subdivisions for some.

The first category includes widespread species found 

over all or nearly all of North America; they are as 

follows:

Sphaerium striatinutn (Lamarck)

lacustre (Muller) 

Pisidimn compression Prime

casertanum (Poll)

nitidum Jenyns 

Fossaria obrussa Say

dalli Baker

Gyraulus parvus (Say) 

Helisoma anceps (Menke) 

Vertigo ovata Say 

Euconulus fulvtis (Muller) 

Hawaiia minuscula (Binney) 

Zonitoides arboreus (Say)

The second cateory includes eastern species found 

commonly over North America east of the Rocky 

Mountains. Some range barely west of the Mississippi 

River, others are common on the Plains.

Six species of this second category are characteristically northeastern, found in the general area of 

New England and the Great Lakes. They are as 

follows:

Sphaerium sulcatum (Lamarck) 

Bulinmea megasoma (Say) 

Ferrissia rivularis (Say)

parallela (Haldeman) 

Stagnicola exllis (Lea)

reflexa (Say)

The other species are more generally distributed:

Sphaerium transversum (Say)

partumeium (Say)

securis (Prime) 

Marstonia decepta (Baker) 

Carychium exiguum (Say) 

Helisoma trivolvis (Say) 

Planorbula armigera (Say) 

StroMlops labyrinthica (Say) 

Gastrocopta armifera (Say)

holsingeri (Sterki)

tappaniana (Adams) 

Pupoides alMlabris (Adams) 

Vertigo milium (Gould) 

Vallonia parvula Sterki 

Retinella wheatleyi (Bland)

rhoadsi (Pilsbry) 

Stenotrema leai (Binney)

The third category is made up of northern species 

found over northern North America. The southern 

boundary of distribution is generally east-west, with 

an extension southward in the Rocky Mountains. 

Some species of this group are Holarctic. They are 

as follows:

Valvata tricarinata (Say)

lewisi Currier 

Stagnicola palustris (Muller)

caperuta (Say) 

Gyraulus circumstriatus (Tryon)

deflectus (Say) 

Armiger crista (Linnaeus) 

Promenetus ea-acuous (Say)

unibilicatellus (Cockerell) 

Physa sJcinneri Taylor

gyrina Say

Apleaca hypnorum (Linnaeus) 

Vallonia pulchella (Muller) 

Cionella- lubrica* (Muller) 

Discus cronkhitei (Newcomb) 

Nesovitrea elcctrina (Gould)

A modified northern distribution pattern may be 

found in Vallonia gracilicosta of the Rocky Mountains, northern Great Plains, and southwestern United 

States.

The fourth category is southern. The few species 

with southern distributions show considerable variation 

in their ranges and are as follows:

Widespread throughout the southern United States:

Gastrocopta pellucida hordeacella (Pilsbry) 

Vallonia perspectiva Sterki

Southwestern, south-central, central, and southeastern United States:

Gastrocopta procera (Gould) 

Helicodiscus singleyanus (Pilsbry)

Southwestern and south-central United States: 

Stagnicola bulimoides techella Haldeman

South-central and central United States: 

Gastrocopta cristata (Pilsbry and Vanatta)

Erratic or poorly known.

Acroloxus coloradensis (Henderson) 

Ferrissia meeMana (Stimpson) 

Physa anatina Lea 

Pupoides inornatus Vanatta 

Oxlyoma retusa (Lea)

The species with eastern distribution range onto 

the Plains varying distances. Some, such as Helicodiscus parallelus, may be found in the High Plains 

where there are scattered patches of trees. Others, 

like Strobilops, are narrowly restricted to areas with 

humus and dead wood. The distributions of these 

species are probably governed by available moisture, 

soil, and frequency of drought. This is essentially 

Geyer's view. The species of northern distribution, 

however, can hardly be so governed, for otherwise they 

would range south in the humid and geographically 

accessible Mississippi Valley or Eastern United States 

generally. For this reason, as well as for others mentioned below, summer extremes of temperature prob-
METHODS

ably govern the southern limits of these forms. By 

the same token, it would seem that species of southern 

distribution (such as Gastrocopta, pellucida hordeaceUa) are prevented from going north by winter extremes of temperature.

This thesis that the species of northern and southern 

distributions are limited by temperature extremes receives support from three other sources: ranges in 

mountains, ranges in the Coastal Plain, and relict or 

isolated occurrences.

The northern species (with the possible exception 

of Valvata) have southern extensions of range in the 

Rocky Mountains. The absence of such a pattern for 

Valvata could be explained by rarity of the necessary 

permanent quiet water habitat. The fact that other 

aquatic species do not have such a pattern in the 

Appalachian Mountains can also be readily explained 

by the scarcity of pond habitats.

On the Atlantic Coastal Plain several species show 

narrow range extensions. This Coastal Plain extension of ranges is to be expected if temperature were 

acting as a distributional barrier. Elsewhere hot summers or cold winters keep these species apart, but 

along the coast the ocean acts as a moderating influence 

and the ranges overlap in a narrow belt. Geyer's 

interpretation of such patterns might have been that 

greater moisture was responsible, but taking the ranges 

as wholes into consideration it seems that the more 

equable temperatures of an oceanic climate are significant rather than any possibly greater moisture. On 

the west side of a continent, as in Germany, humidity 

may change more obviously than temperature extremes. 

On the Atlantic Coastal Plain of the United States 

temperature extremes are more apparent than any other 

factor in limiting ranges of these northern and southern species.

Alexander (1952, p. 54) stated:

A striking feature of the New Jersey land snail fauna is the 

presence of typically northern species living in association 

with typically southern species. This anomalous combination 

of species can be explained by the fact that New Jersey is 

located on the central part of the Atlantic coast where some 

northern species approach the southern limit of their distribution and some southern species reach the northern limit of 

their distribution. Certain species belonging to these diverse 

elements can be found together only in this state.

Northern species extending southward in a narrow 

coastal strip are Pupilla muscorum and Cionella lubrica. A southern species reaching its northern limit 

in New Jersey is Gastrocopta pellucida hordeacella. 

Concerning the distribution of this last form, Pilsbry 

(1948, p. 914) wrote:

The northward extension along the Atlantic coast is very 

narrow, discontinuous so far as known, and perhaps mainly 

confined to the coastal islands.

There is only one known joint occurrence of Cionella 

lubrica and Gastrocopta pellucida hordeacella, at Cape 

May, N. J., and perhaps also in the Rexroad local 

fauna (fossil) of southwestern Kansas.

Another northern species with a Coastal Plain range 

extension southward is Promenetus exacuous.

Several isolated occurrences of species further suggest temperature extremes as range-limiting factors. 

These relict occurrences are of fresh-water species well 

south of their present northern distribution.

In Meade County, southwestern Kansas, the constant 

temperature and summer-cool waters of an artesian 

spring provide a habitat suitable for Promenetus exacuous (Leonard, A. E., 1943, p. 235). The nearest 

occurrences of the species are in the Rocky Mountains 

to the west and in northern Nebraska to the north.

In Cherry County, Nebr., a similar cool spring supported Valvata tricarinata and Gyraulus deflectus 

(this paper). Other permanent water bodies of equal 

depth were examined without finding these species. 

Probably they are able to live here because the water 

is warmed little if at all during summer hot spells. 

In the High Plains these species may not live in the 

United States except in unusual habitats such as this 

one. Their nearest occurrences are to the northeast, 

in eastern South Dakota.

For the various reasons given above, therefore, it 

seems that temperature extremes are factors limiting 

the ranges of species with generally northern or southern distributions. Many other species, however, are 

probably more influenced by a complex interaction of 

soil, vegetation, and climate.

At least two species have distributions which do not 

seem controlled by any of these factors: Bulimnea 

megasoma and Acroloxus coloradensis. Their ranges 

are not well known, but enough collecting has been 

done to suggest they are erratic. Why these species, 

formerly so widespread on the Great Plains, are now so 

restricted is unknown. Perhaps they are largely analogous to Anisus pattersoni, which was also abundant 

on the Plains during the Pleistocene but apparently 

became extinct in North America during the Wisconsin

Inasmuch as these two Recent species (Bulimnea 

megasoma and Acroloxus coloradensis) seem significantly affected by unknown influences, it is unwise to 

use them in paleoclimatic interpretations.

INADEQUACY OF HABITAT AND DISTEIBUTIONAL

DATA

Throughout this paper only general and vague 

conclusions about local habitat and climate have been 

possible. This reflects the lack of knowledge concern-
LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

ing ecology and distribution of many species. Habitatdata are lacking or so scanty for a number of species 

that they have been grouped under the "uncertain" 

category in charts showing faunal habitat indications. 

Further collecting, especially on the High Plains, will 

enable considerably more detailed climatic interpretations than are possible now.

Stratigraphic ranges of species also reflect the inadequate amount of collection. Further work will of 

course considerably advance such knowledge, particularly in the fluviatile groups such as Viviparidae, 

Pleuroceridae, and Unionidae. At the present time in 

the Great Plains, Oligocene and middle Pliocene mollusks are essentially unknown, Miocene mollusks entirely unknown, and lower Pliocene forms known only 

from the Laverne local fauna.

Extensions of the known geological range of Eecent 

species have been and will be common, but it is pertinent to point out also that several species described 

as fossils have been subsequently found living. Hendersonia occulta, Discus macclintocki, and now PJiysa 

skinneri were all originally thought to be extinct Pleistocene species, but have later been collected alive.

UNSATISFACTORY TAXONOMY

Many, perhaps most of the species dealt with in this 

paper are well known so far as their classification and 

distinguishing characters are known. In many other 

parts of North America, however, the percentage of 

satisfactorily classified species is much less. In the 

High Plains the poorly known groups are chiefly 

Planorbidae, Succiiieidae, Physa,, and Fossaria* but 

other areas can add more. Pleistocene and late Tertiary paleontology is nearly always dependent upon a 

knowledge of Eecent species, and hence must lag 

where large parts of the living fauna are poorly 

known.

METHODS OF FATJNAL INTERPRETATION

The preceding summaries of the principles and 

difficulties of paleoecologic interpretation show the 

basis on which individual species can be interpreted. 

Two other complementary approaches are also useful: 

comparison of the fossil assemblage with the living 

fauna of the region around the fossil locality and 

comparison of the fossil assemblage with a similar 

living fauna. In these methods the fauna as a whole 

is considered, and the ever-present danger of overemphasizing single species can be avoided.

Comparison, with Recent fauna nearby. In comparing the fossil and Recent assemblages from the samearea, one inevitably uses negative evidence to some 

extent. Usually some fossil species are not living

nearby, and some Eecent species are unknown in the 

fossil fauna. Reliability of conclusions depends upon 

the thoroughness of collecting, and one must not read 

too much into a poorly sampled fauna. If the Recent 

fauna near the fossil locality is reasonably well sampled, then the presence of fossil species living only 

in other areas is significant. Degree of significance 

will vary with the accuracy to which the distributions 

of the locally extinct species are known. Inasmuch 

as a fossil assemblage is usually known from one or a 

very few localities, the absence from it of certain 

species is much less noteworthy than absence from 

the better known Recent fauna.

Comparison with a similar Recent fauna. Many 

fossil assemblages which differ from the fauna living 

locally are like a living assemblage elsewhere. The 

reasonable inference can then be made that the environment of the fossil site was formerly like that 

where the species are now living. This same principle 

may be applied more broadly in the case of earlier 

Tertiary or Mesozoic faunas, and comparison made 

between genera or pairs of closely related species. This 

approach is not strictly applicable to most of the assemblages studied in this report, howrever, for there 

are many fossil associations of species not living 

together today.

One such association, which occurs in several of the 

Blancan faunas, is that of Stagnicola ca.perata and 

Promenetus umbilicatellus, both northern species, with 

the southern Stagnicola, bulimoides techella. Probably 

only a moderate reduction in number and duration 

of summer hot spells would permit the northern forms 

to move south. The association is not inexplicable, 

but does show that strict comparison with living assemblages may be inadequate.

An even more striking example is the association 

of Physa skinneri and Stagnicola bulimoides techella 

in the Sanders local fauna. The limits of distribution 

in the Great Plains of these two species are hundreds 

of miles apart. Physa skinneri is known only as far 

south as southern Manitoba; Sta.gnicola bulimoides 

techella barely reaches Nebraska, where it is known 

from a single locality in the southernmost part of the 

state. Elsewhere in North America, the two species 

have been found closer together. In Utah Physa skinneri is known from the Hint a Mountains, in the northeastern part of the state; Stagnicola bulimoides techella is known from central Utah, but at much lower 

elevations. Although the ranges of these species are 

closer in Utah than in the Great Plains, the contrast 

in habitats is still as great. The Sanders local fauna, 

containing both these now widely separated species,
METHODS 9

cannot be compared closely with modern molluscan 

associations.

AGE DETERMINATION

Two methods of dating faunas by fossil evidence 

can be used in the late Cenozoic. The more general 

approach is purely faunal, based on restricted or overlapping ranges. The second method is less widely 

applicable, but of perhaps greater value for the Pleistocene. By inference of former climatic conditions, 

a fauna may be placed with some precision in a known 

glacial-interglacial sequence.

One fundamental premise should also be stated here: 

all lines of available evidence bearing on the age of a 

fauna must be considered. This principle would seem 

too obvious to need pointing out, but nevertheless has 

sometimes been ignored.

FAUNAL DATING

In using the method of restricted or overlapping 

ranges, animals with short vertical but wide geographic ranges are of course most valuable. In the 

present state of paleontological knowledge, this fact 

means that mammals are the most useful group. Mollusks as a whole are less reliable in the faunas under 

consideration, but their great abundance means they 

are potentially helpful.

Associated mammals and mollusks have not yet 

yielded contradictory conclusions, although often one 

group gives evidence which the other lacks. An example of the complementary use of mollusks and mammals is as follows: The Saw Rock Canyon and 

Rexroad local faunas can scarcely be distinguished by 

mollusks, but the mammals show a considerable difference. The mollusks indicate an ecological similarity 

between the two faunas, while the mammals demonstrate time difference. Southwestern Kansas probably had an essentially uniform climate throughout 

the late Pliocene. The mollusks did not change visibly, 

while the mammals did.

Lyell (1833, p. 47-49) was perhaps the first to recognize the principal differences in stratigraphic utility 

of mollusks and vertebrates. He stated:

Although the bones of mammalia in the tertiary strata, and 

those of reptiles in the secondary, afford us instruction of the 

most interesting kind, yet the species are too few, and confined to too small a number of localities, to be of great importance in characterizing the minor subdivisions of geological formations. * * * We shall revert in the sequel to the 

curious fact, that in tracing back these series of tertiary deposits, many of the existing species of testacea accompany us 

after the disappearance of all the recent mammalia, as well 

as the fossil remains of living species of .several other classes. 

We even find the skeletons of extinct quadrupeds in deposits 

wherein all the land and freshwater shells are of recent 

secies.

508945 O 60 2

The following points summarize these differences 

between mollusks and mammals as shown by the late 

Pliocene and early Pleistocene faunas of the High 

Plains considered in this paper.

Mollusks evolve more slowly than mammals. From 

a stratigraphic standpoint they are therefore less 

valuable, but are more useful for paleoecologic inferences. In the special case of the Pleistocene epoch, 

when major f aunal shifts took place, some mollusks 

may be especially valuable in refined dating within 

a known climatic sequence because of their sensitivity 

to climatic change.

Mollusks are smaller, commoner, and occur in denser 

populations than do mammals. For this reason they 

are more abundant and more easily collected as fossils.

The shells of mollusks usually provide the chief 

basis for specific identifications, although not for generic or familial classification. Thus the fossils in their 

usual state have nearly all the characters used in 

determination of living forms. Mammal skeletons 

are readily disarticulated and broken, and many individual bones may be useless for identification of 

species.

Mollusks are restricted in their powers of dispersal 

and generally show endemism in major physiographic 

regions. The present-day f aunal regions east and west 

of the Rocky Mountains, for example, appear to have 

been in existence during the Pliocene also. Correlation between these two regions is thus impracticable 

on the basis of specific identity of mollusks. Most 

mammals, more vagile and with less temporal range, 

offer the most precise means of correlation.

Dating from climatic inference. A second method 

of dating Pleistocene fossil assemblages is based on 

their ecologic interpretation. This method is potentially more precise than other paleontologic means, 

but depends upon an established sequence into which 

an assemblage may be fitted. This method may also 

be more versatile as well as more precise. For example, 

once a sequence of climatic changes has been verified 

for a given region, any group of fossils from which 

adequate environmental inferences can be drawn can 

be placed in this sequence. The late Pleistocene and 

Recent climatic history of western Europe is based on 

fossil pollen and inferred vegetational changes; in 

theory an assemblage of amphibians, snails, or beetles 

could be dated if their ecologic implications were 

precise enough to permit placing them in the sequence.

In the Great Plains region there is no such established sequence of Pleistocene climatic changes. Although a number of climatically significant faunas 

have been described from southwestern Kansas and 

northwestern Oklahoma by C. W. Hibbard and co-
10 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

workers, the record is far from complete. The relative 

ages of the described assemblages are fairly well 

known, but documentation of a sequence of climatic 

changes is hardly continuous. Plotting the curve of 

Pleistocene climate in southwestern Kansas requires 

more points than are now available.

Furthermore, the exact correlation of the faunas of 

southwestern Kansas and northwestern Oklahoma in 

terms of glacial events is unknown. Whether a certain 

fauna represents a very late glacial age, when continental glaciers were in existence but waning, for 

example, is speculative. The known stratigraphic succession of faunas and their ecologic interpretations 

permits only allocation to a given glacial or interglacial age.

Although the record is incomplete, the amount of 

data is sufficient to suggest climatic trends, and certain 

similarities between parts of the Pleistocene record 

are striking. A working hypothesis is warranted, 

as a generalization about information now available 

and as an aid to future work. This hypothesis is that 

the glacial-interglacial climatic changes are cyclic.

Cyclic climatic changes. A cyclic pattern of glacialinterglacial climatic changes cannot be confirmed fully 

from the record in southwestern Kansas. The confirmation is partial, however, and all of the known 

data are consistent with the hypothesis that these 

changes were cyclic from the Nebraskan to Sangamon 

ages. Although progressive uplift of the Eocky Mountains during the Pleistocene presumably affected the 

climate, evidence of this is not clear.

Consideration of the physical and climatic events 

of the Pleistocene in southwestern Kansas and northwestern Oklahoma as a cyclic pattern was prompted 

by Stokes' (1955) stimulating hypothesis of oceanic 

control of glacial-interglacial alterations. Consistent 

evidence from many parts of the world and of many 

different kinds is needed to confirm Stokes' hypothesis. 

The evidence from Kansas and Oklahoma is scarcely 

definitive, even though significant. Nevertheless implications of the ocean-control hypothesis fit the known 

faunal and stratigraphic succession in southwestern 

Kansas better than ideas about Pleistocene climates 

deduced from other theories.

The following sequence of glacial-interglacial 

changes fits the available information from southwestern Kansas and northwestern Oklahoma to a 

hypothetical cycle. The cycle is intended to apply 

only to this local area.

1. Late glacial age. Summers much cooler than now; 

winters no colder, perhaps slightly warmer; precipitation little if at all greater but much more effective.

(Kansan Cudahy fauna, Illinoian Berends and Butler 

Spring local faunas; Wisconsin Jones local fauna).

2. Early interglacial age. Climate warm-temperate, 

semiarid. Summers much as today; winters much 

milder; precipitation about the same or slightly less. 

(Yarmouth Borchers local fauna; Sangamon Cragin 

Quarry local fauna).

3. Middle interglacial age. Climate probably warmtemperate, semiarid. A massive, indurated caliche 

layer about a foot thick formed during part of each 

of the three interglacial ages.

4. Late interglacial age. Summers much cooler than 

now; winters very much warmer; precipitation greater 

in amount and effectiveness (Aftonian Sanders local 

fauna; Sangamon Jinglebob local fauna).

The Sand Draw and Dixon local faunas, discussed 

elsewhere in this paper, do not fit this pattern well. 

Probably their geographic location some distance from 

the other local faunas is partly, but not entirely responsible. Perhaps a smaller Rocky Mountain rain 

shadow, or a different climatic regime during the Nebraskan age, explain their peculiarities.

Eelation of the present day climate to this cycle 

is uncertain. The living molluscan fauna is poorer 

in species than any of the known fossil assemblages, 

and suggests that the present fauna is geologically 

unusual. If some phase of the hypothetical climatic 

cycle is similar to the present climate, this phase is 

probably somewhere between the late glacial and early 

interglacial stages.

LOCAL FAUNAS

The term "local fauna" is used by vertebrate paleontologists to designate an assemblage of fossils from one 

locality, or from several closely grouped localities 

which are demonstrably stratigraphically equivalent or 

nearly so. It is a group of fossils local in both time 

and space. Advantages of this term are as follows:

It provides a designation for fossils which can be 

independent of formation names. A faunal name taken 

from a rock unit may become either inappropriate or 

misleading as the fossiliferous unit is subdivided or 

restricted. Exceptions to the general policy of distinct 

faunal names are those where long usage makes the 

change to a distinct name undesirable (as Barstow 

local fauna, Barstow formation) and those where the 

rock unit is named later than the fauna (as Rexroad 

local fauna, Rexroad formation).

Such a locally restricted name does not imply a 

doubtful correlation. A term applied to several widely 

separated assemblages runs the grave risk of major 

restriction or dismemberment as more data become 

available. Only rarely can more widespread localities 

be shown to be contemporaneous by special methods
COMPARISON OF FAUNAS 11

such as the association of the Cudahy fauna with the 

petrographically distinct Pearlette ash bed.

The name per se implies no special age. Leonard 

(1950) called the mollusks associated with the Pearlette ash bed the "Yarmouthian molluscan fauna." With 

changed age assignment Frye and Leonard (1952) 

termed the same assemblage the "Kansan molluscan 

fauna." A Kansan age seems probable, but nevertheless the later name is still open to the objection of 

special age implication. Other disadvantages are that 

the name cannot include other groups of animals, such 

as mammals, and that the name does not indicate its 

actual geographic restriction to the central Great 

Plains region. Here the noncommittal term Cudahy 

fauna seems clearly preferable.

A widespread or thick formation may have a different time range in different areas. Assemblages grouped 

as a fauna from separate localities in such a formation 

may be far from contemporaneous. Use of a number 

of local faunas would obviate a "fauna" which is 

gradually dismembered and restricted in age as more 

precise information becomes available. A specific 

example of a unit containing faunas of markedly different ages is the Rexroad formation of southwestern 

Kansas. Three distinct assemblages from this unit are 

recorded in the present paper.

Elias, too, (1942, p. 134-136) discussed this question 

of independent faimal and floral names, arriving at 

opposite conclusions. The reasons set forth above 

seem to me to outweigh any possible advantages of 

Elias's proposed method of a unified rock-faunal terminology. Van Houten, too (1944) has discussed the 

question of faunal nomenclature, concluding that a 

geographic name independent of stratigraphic terminology is convenient and desirable.

COMPARISON OF FAUNAS

Table 2 shows the occurrence and range of the species in eight faunas. These data are summarized in 

table 3. Indices of taxonomic similarity are given in 

table 4.

First appearances of species show two marked discontinuities : Saw Rock Canyon-Rexroad and RexroadSand Draw. The first of these is considered not 

significant because it is almost surely in large part 

or entirely a result of inadequate sampling. The Rexroad local fauna is known from several localities, the 

Saw Rock Canyon local fauna from a single locality 

with little diversity of habitats.

The Rexroad-Sand Draw discontinuity is at least 

partly climatic. Many species first known from the 

Sand Draw local fauna probably represent northern 

species driven south by glacial advance. Extinction

of some Rexroad species may be due to climatic change 

also. (See table 5.)

Last appearances of species are most apparent in 

the Bender and Sanders local Kaunas. Cooler climates 

associated with formation and advance of the Nebraskan and Kansan continental glaciers seem reasonable 

explanations for these.

Indices of faunal similarities (table 4) reveal the 

following significant points: The Saw Rock Canyon, 

Red Corral, and Rexroad local faunas are markedly 

similar to one another; the Sand Draw, Dixon, and 

Sanders local faunas are markedly similar to one 

another; the Bender local fa ana is most similar to 

the Rexroad and Sanders; the Pleistocene fauna most 

similar to the Rexroad is the Sanders.

Apparent ranges and occurrences of individual species may be affected by sampling error, as well as by 

local habitat differences and by regional causes. The 

differences considered significant, and possible causes, 

are discussed below.

Vertigo ovata is known from the Clarendonian Laverne local fauna, Hemphillian Buis Ranch local 

fauna, and from numerous Pleistocene faunas. In the 

Rexroad and Saw Rock Canyo:i local faunas, however, 

it is replaced by V. hibbardi. This may be an example 

of temporary ecological replacement, for both species 

are of similar size and both probably had similar 

habitats. A possible explanation is that V. hibbardi 

arrived in the region of southern Kansas (either by 

migration or evolution) at the end of the Hemphillian, 

largely eliminated V. ovata in the area, and was in 

turn driven out by the first glaciation. V. ovata is a 

eurythermal species as shown by its wide range; 

perhaps V. hibbardi was not.

Gastrocopta rexroadensis and Polygyra rexroadensis 

are not known from faunas later than the Rexroad 

and Bender but do not necessarily indicate a late Pliocene age. Neither species is common enough to be 

reliable as a stratigrahic indicator. G. rexroadensis 

was not found in University of Michigan collections 

at localities from which it is reported.

Twenty-nine late Pliocene species are not known 

from earlier deposits. This ms,y be entirely the result 

of incomplete collecting.

Gastrocopta cJiauliodonta is known only from three 

faunas which are dated Nebraskan or Aftonian on 

independent grounds. Collecting in earlier and later 

faunas seems sufficiently adequate to establish its local 

restriction to the lower Pleistocene, for it is a relatively common species. It may be a species which 

lived to the north in the late Pliocene and was forced 

southward by glaciation.
12 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

TABLE 2. Stratigraphic occurrence of mollusks of some late Ceno zoic faunas in the High Plains 

[Occurrences outside the faunas listed are not necessarily in the High Plains. Occurrence of specifically unidentified forms and uncertain occurrences are omitted]

Species

Promenetus kansasensis (Baker) _

Hawaiia minuscula (Binney)

Bulimnea megasoma (Say)

compressum Prime

nitidum Jenyns. _

Promenetus umbilicatellus (Cockerell)

inornatus Vanatta _

Sphaerium striatinum, (Lamarck)

Vallonia gracilicosta Reinhardt

Valvata tricarinata (Say)

Vertigo ovata Say _

Zonitoides arboreus (Say) _

Strobilops sparsicostata Baker_

Ferrissia rivularis (Say)

Stagnicola caperata (Say)

Gastrocopta rexroadensis Franzen and Leonard

Vertigo hibbardi Baker

Gastrocopta franzenae Taylor

Marstonia crybetes (Leonard)

Gastrocopta paracristata Franzen and Leonard

Deroceras aenigma Leonard _

Fossaria dalli (Baker) _ _ _

Gastrocopta holzingeri (Sterki)

tappaniana (Adams)

Helicodiscus singleyanus (Pilsbry)

Helisoma anceps (Menke)

Marstonia decepta (Baker)

Physa anatina Lea

Stagnicola bulimoides techella (Haldeman)

Strobilops labyrinthica (Say) _ _ _

Vallonia perspectiva Sterki

Vertigo milium (Gould)

Gastrocopta pellucida hordeacella (Pilsbry)- _ _

Polygyra rexroadensis Taylor.

Carychium exiguum (Say) _ -

Cionella lubrica (Muller)

Ferrissia parallela (Haldeman)

Nesovitrea electrina (Gould)

Retinella rhoadsi (Pilsbry)

wheatleyi (Bland)

Stagnicola exilis (Lea)

Gastrocopta scaevoscala Taylor

cristata (Pilsbry and Vanatta) _

Vallonia parvula Sterki

Gastrocopta chauliodonla Tavlor

Acroloxus coloradensis (Henderson)

Aplexa hypnorum (Linnaeus)

Ferrissia meekiana (Stimpson)

Fossaria obrussa (Say)

Physa gyrina Say

skinneri Taylor

Planorbula armigera (Say) _

Sphaerium partumeium (Sav)

sulcatum (Lamarck)

transversum (Say)

Vallonia pulchella (Muller)

Valvata lewisi Currier

Gastrocopta procera (Gould)

Helicodiscus parallelus (Say)

Helisoma trivolvis (Say)

Oxyloma retusa (Lea)

Sphaerium lacustre (Muller)

Stagnicola reflexa (Say)

Stratigraphic occurrence

Pre-Buis 

Ranch 

local 

fauna

XXXXXXXXXXXXXXXXX

Buis 

Ranch 

local 

fauna

X

X

X 

X 

X

Saw 

Rock 

Canyon 

local 

fauna

X

X 

X

X

X 

X

X

xxxxxxxxxxxxxxxxx

Red 

Corral 

local 

fauna

X

X 

X

X

X

X

X 

X

X

X

X 

X

X 

X

X 

X

Rexroad 

local 

fauna

X

X 

X

X

X 

X 

X

X

xxxxxxxxxxxxxx

X 

X

xxxxxxxxxxx

Bender 

local 

fauna

X

X 

X

X

X

X 

X 

X

X 

X

X 

X

X

X

X 

X

X

Sand 

Draw 

local 

fauna

X 

X

XXXXXXXXXX

X 

X

X 

X 

X

X 

X

X 

X 

X

X

X 

X

X

xxxxxxxxxxxxx

Dixon 

local 

fauna

XXXXXXXXXXX

xxxxxx

X

X 

X

X 

X 

X

X

X 

X 

X

X

X

X 

X

X 

X

X

xxxx

X

xxxxxx

Sanders 

local 

fauna

X

X 

X

X 

X

X

X

X 

X 

X

X 

X

X

X

X 

X

X

X

X

X

Late 

Pleistocene

XXXXXXXXXXXXXXXXX

X 

X

XXXXXXXXXXXXX

xxxx

X

X

xxxxxxxxxxxxxxx

X

Recent

XXXXXXXXXXXXXXX

X 

X

xxxxxxxxxxxx

xxxxxxx

X

X

xxxxxxxxxxxxxxxxxx
COMPARISON OF FAUNAS 

TABLE 3. Summary of data from table 2

13

Occurrence

Buis Ranch local fauna.--.- ___

Saw Rock Canyon local fauna____ 

Red Corral local fauna

Number of 

species

17

5

24 

16

35

17

38

4.c

20

54

Percent 

restricted

0

0 

0

0

0

0

0

0

Percent 

first 

appearance

60

71 

6

23

18

34

13

0

Percent 

last 

appearance

0

0 

0

6

12

0

7

10

Occurrence

Total species for all faunas _

Saw Rock Canyon, Rexroad, and

Sand Draw and Dixon

Saw Rock Canyon, Red Corral,

Sand Draw, Dixon, Sanders, and

Number of 

species

56

68

37

52

54

40

57

Percent 

restricted

5

0

2

10

4

Percent 

first 

appearance

70

37

35

73

3Q

Percent 

last 

appearance

4

q

10

12

TABLE 4. Faunal similarities

100C [Calculated from data of table 2 by , where C=number of species common to two faunas and Ni=number of species in smaller fauna]

Local faunas

Buis Ranch (N = 5) _ - __ ._ _____ ________ _ _

Saw Rock Canyon (N = 24)___________ _ __________

Red Corral (N = 16)________.___-_._______________

Rexroad (N = 36) _ .___--____-__--_________-_____

Bender (N = 17)___.__ _ _ ____. _ __.__ __

Sand Draw (N = 38)-_-_-_-_-__,.______-_ _ _______

Dixon (N = 45)- ----------_-----_-__-----__-__-

Sanders (N = 20) _________________________________

Buis 

Ranch

40

60

80

20

100

100

40

Saw Hock 

Canyon

40

81

92

71

58

67

70

Red Corral

60

81

100

50

fiQ

69

56

Rexroad

80

92

100

83

49

60

80

Bender

20

71

50

83

65

71

77

Sand Draw

100

58

69

49

65

82

85

Dixon

100

67

69

60

71

82

85

Sanders

40

70

56

80

77

85

85

TABLE 5. Distribution of thermally significant species in late Pliocene and early Pleistocene faunas of the High Plains

Climate

Mesothermal: 

Winters relatively mild and 

short.

Summers mild__

Summers warm but not hot 

and dry.

Species

Gastrocopta cristata (Pilsbry and 

Vanatta) .

Stagnicola bulimoides techella (Haldeman) .

Vallonia pulchella (Miiller) _

Promenctus umbilicatellus (Cockerell) _

Local fauna

Buis 

Ranch

X

Saw 

Rock 

Canyon

X 

X

X

X

Red 

Corral

X

X

X

Rexroad

X

X 

X

X

X 

X 

X

Bender

X

X 

X

X 

X

Sand 

Draw

X

X

X 

X 

X 

X 

X 

X 

X

Dixon

X

X 

X 

X

X 

X

X

X 

X

Sanders

X

X 

X

X 

X

X 

X 

X
14 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Nineteen species are first known in the earliest 

Pleistocene. Perhaps all of these were living to the 

north during the late Pliocene.

Temperature differences and similarities are shown 

by table 5. The Saw Eock Canyon, Eexroad, Bender, 

and Sanders local faunas are believed to have lived in 

a climate with summers warm but not hot and dry; the 

Sand Draw and Dixon local faunas in one of mild 

summers. These climatic shifts probably represent continent-wide changes, for southwestern Kansas is well 

beyond the limits of glaciation. These changes are tentatively correlated with the glacial-interglacial sequence in the Mississippi Valley.

SUMMARY OF FAUNAL SEQUENCE

Figure 1 summarizes the sequence of some Pliocene 

and Pleistocene faunas in the Great Plains and their 

stratigraphic position and age. In addition to the 

middle Pliocene to early Pleistocene assemblages 

described in detail elsewhere in this report, middle 

and late Pleistocene faunas of southwestern Kansas 

and northwestern Oklahoma, and other faunas mentioned in the text are included. The following notes 

present supplementary information, including references to pertinent literature. Numbers correspond to 

those in figure 1.

The North American ages Hemphillian, Blancan, 

Irvingtonian, and Rancholabrean (Wood and others, 

1941; Savage, 1951) have not been adopted for official 

usage by the U.S. Geological Survey.

1. Buis Ranch local fauna (Herrington and Taylor, 

1958; Hibbard, 1954; Oelrich, 1957; Tihen, 1955). In 

the upper part of the Ogallala formation, in Beaver 

County, Okla. Mammals, reptiles, amphibians, and 

mollusks. Several of the mammals show close relations with others in the Saw Rock Canyon local fauna, 

in the lower part of the Rexroad formation. Occurrence in the fauna of a rhinoceros (unknown elsewhere 

in North America from assemblages as young as 

Blancan), and the stratigraphic position of the fossils 

in the Ogallala formation, are the suggestive but 

somewhat arbitrary reasons for assigning this fauna 

to the late Hemphillian rather than early Blancan. 

The few mollusks slightly differentiate the assemblage 

from the Saw Rock Canyon and Rexroad local faunas, 

but how significantly is uncertain. Climate with summers less hot and dry than those of the area today. 

Significant members: Pliogeomys, Perognathus cf. P. 

mclaugJilini Hibbard, rhinoceros, Stagnicola caperata 

(Say), Vertigo ovata Say.

2. Saw Rock Canyon local fauna (Herrington and 

Taylor, 1958; Hibbard, 1953, 1954, 1957; Taylor, this 

paper; Tihen, 1955). In the XI member (of Hibbard,

1949) of the lower part of the Rexroad formation, 

Seward County, Kans. Fishes, amphibians, reptiles, 

birds, mammals, and mollusks. The mammals indicate 

an earliest Blancan (early late Pliocene) age. The 

mollusks do not differentiate this fauna from the 

Rexroad local fauna. Climate subhumid and mesothermal, with less extreme summer hot spells and 

slightly greater and more effective annual precipitation. Significant members: Dipoides wilsoni Hibbard, 

Ogmodontomys sawrockensis Hibbard, Baiomys sawrockensis Hibbard, Osteoborus progressus Hibbard, 

Vertigo hibbardi Baker, /Stagnicola bulimoides techella 

Haldemaii, Promenetus wnbilicatellus (Cockerell).

3. Rexroad local fauna (Herrington and Taylor, 

1958; Hibbard, 1950; 1954b; 1956, p. 185; Oelrich, 

1957; Taylor, this paper; Tihen, 1955). In the upper 

part of the Rexroad formation, below the massive 

caliche, Meade and Seward counties, Kansas. Amphibians, reptiles, birds, mammals and mollusks. The 

mammals indicate a considerably younger age than 

that of the Saw Rock Canyon local fauna, though still 

Pliocene. Climate subhumid and mesothermal, with 

markedly milder winters than those today, summers 

lacking the present hot spells, and a somewhat greater 

annual rainfall. There is no evidence of a stratigraphic break or of a climatic change between the 

horizons of the Saw Rock Canyon and Rexroad local 

faunas. Significant members: Dipoides rexroadensis 

Hibbard and Riggs, Ogmodontomys poaphagus Hibbard, Bensonomys eliasi (Hibbard), Procastoroides 

lanei (Hibbard), Plesippus simplicidens (Cope), Nannippus phlegon (Hay), primitive Stegomastodon, Testudo rexroadensis Oelrich, T. turgida Cope, Stagnicola 

bulimoides techella (Haldeman), $. exilis (Lea), Promenetus umbilicatellus (Cockerell), Gastrocopta franzenae Taylor, G. pellucida hordeacella (Pilsbry), G. 

rexroadensis Franzen and Leonard.

4. Bender local fauna (Taylor, this paper). In 

the upper part of the Rexroad formation above the 

massive caliche, in Meade and Seward Counties, Kans. 

Mollusks only. The fauna is a little more like the 

Rexroad local fauna than the Sanders local fauna 

or other Pleistocene interglacial assemblages, and tends 

to favor a Pliocene age. Climate subhumid and mesothermal. Significant members: Stagnicola bulimoides 

techella (Haldeman), S. caperata (Say), Promenetus 

umbilicatellus (Cockerell), Gastrocopta franzenae 

Taylor, G. cf. G. cristata (Pilsbry and Vanatta), G. 

scaevoscala Taylor.

5. Unnamed assemblage (Hibbard, 1949, p. 67; 

1956; Savage, 1955). A few large vertebrates have 

been collected from the Angell member of the Ballard 

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16 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

sip pus simpUcidens (Cope), Equus (Asinusl) sp., 

Nannippus plilegon (Hay), Stegomastodon mirificus 

(Leidy), and camel.

6. Deer Park local fauna (Hibbard, 1956). In the 

lower part of the Missler member of the Ballard formation, in Meade County, Kans. The mammals indicate Blaiican age, narrowed to Aftoniaii by indications 

of mild climate and by their stratigraphic position. 

From the Angell member of the Ballard formation, 

below the Missler member, Hibbard (1944) reported 

glacially striated pebbles. Significant members: Pliolemmus antiquux Hibbard, Pliopotamys meadensis 

Hibbard, Procastoroides sweeti Barbour and Schultz, 

Nannippus plilegon (Hay), Plesippus simpUcidens 

(Cope), and large species of Testudo.

7. Sanders local fauna (Hibbard, 1956; Taylor, 

this paper; Tihen, 1955). In the upper part of the 

Missler member of the Ballard formation, above the 

massive caliche, in Meade County, Kans. Mollusks, 

amphibians, birds, and mammals. Stratigraphic position, ecologic interpretations, and faunal evidence indicate late Aftonian age. The fauna is distinct from 

other Blaiican assemblages in its composition as well 

as climatic implications. Climate subhumid and mesothermal, with more effective precipitation and sharply 

reduced summer temperatures. Significant members: 

Sigmodon, Zapus, Plesippus simpUcidens (Cope), 

Nannippus phlegon (Hay), Gastrocopta chauliodonta 

Taylor, G. paracristata Franzen and Leonard, Physa 

skinneri Taylor, Stagnicola l>ulimoides techella (Haldeman).

8. Seger local fauna (Hibbard, 1951, 1953; Savage, 

1955). In the Stump Arroyo member of the Crooked 

Creek formation, in Meade and Clark Counties, Kans. 

Large mammals only. The few species known do not 

differentiate this fauna from earlier ones, but are distinct from those of later assemblages. They have 110 

special climatic implications. Significant members: 

Plesippus. sp. cf. P. simplicidens (Cope), Nannippus 

phlegon (Hay), Stegomastodon mirificus (Leidy).

9. Cudahy fauna (Frye and Leonard, 1952, p. 158- 

159; Herrington and Taylor, 1958; Hibbard, 1944, 

1949b; Johnston and Savage, 1955; Leonard, 1950; Tihen, 1955). Includes the Tobin and Wilson Valley 

faunules (Frye, Leonard, and Hibbard, 1943), the 

"Yarmouthian molluscan fauna" (Leonard, 1950), and 

the "Kaiisan molluscan fauna" (Frye and Leonard, 

1952) in part. The Arkalon local fauna (Hibbard, 

1953a) is tentatively included. Associated with the 

Pearlette ash bed (usually immediately below the ash) 

over a wide area from Iowa to Texas. In southwestern 

Kansas it is in the At water member of the Crooked 

Creek formation. Frye, Swineford, and Leonard

(1948) recognized the petrographic distinctness of 

the Pearlette ash bed and listed the mollusks associated 

with it. This volcanic ash demonstrates the essential 

contemporaneity of the associated fossils. The name 

Cudahy fauna is used in the broad sense for the entire 

assemblage, for there seems no reason to use more 

than one name. Fishes, amphibians, reptiles, birds, 

mammals, and mollusks are known. Hibbard (1949b) 

considered the Cudahy a glacial fauna of Kansan 

age, pointing out the boreal relations of the vertebrates. The snails Pupilla muscorum^ P. blandi, Vertigo gouldi, V. modesta, and others occur in the Great 

Plains today only far to the north. Their presence 

in the Cudahy fauna as far south as Texas indicates 

radically cooler and moister summers and presumably 

wetter, but not necessarily colder, winters. Significant 

members: Equus sp., Sorex, Neosorex lacustris Hibbard, Microsorex pratensis Hibbard, Synaptomys 

(Mictomys] horeaUs (Kichardson), Microtus paroperarius Hibbard, Pedomys llanensis (Hibbard), Pitymys meadensis Hibbard, Pupilla muscorum (Linnaeus), Vertigo modesta (Say), Valvata tricarinata 

(Say).

10. Borchers local fauna (Hibbard, 1941b, 1949b; 

Tihen, 1955). In the Atwater member of the Crooked 

Creek formation, above the Pearlette ash bed, in Meade 

County, Kans. Amphibians, reptiles, birds, and mammals. The small mammals indicate a climate as warm 

or warmer than that of present day southwestern 

Kansas, and hence an interglacial age. Significant 

members: Testudo, large species, Onychomys fossilis 

Hibbard, Sigmodon hilli Hibbard, Synaptomys landesi Hibbard.

11. Butler Spring local fauna (Herrington and 

Taylor, 1958; Hibbard and Taylor, 1960; Smith, C. 

L., 1958; Tihen, 1955). In the lower part of a section 

included in the undifferentiated Sanborn group, in 

Meade County, Kans. Fishes, amphibians, reptiles, 

mammals, and mollusks. Stratigraphic position and 

ecological interpretations indicate a late Illinoiaii age. 

Climate subhumid, differing from that of Meade 

County today in being markedly cooler, the difference 

mostly in the summers. Significant members: Ictalurus cf. /. punctatus (Rafinesque), Perca flavescens 

(Mitchill), Valvata tricarinata (Say), Probythinella 

lacustris (Baker), Lymnaea. stagnalis jugularis Say, 

Pliysa skinneri Taylor, Pupilla muscorum (Linnaeus), 

Vallonia cyclophorella Sterki.

12. Jinglebob local fauna (Herrington and Taylor, 

1958; Hibbard, 1952, 1955, 1956a; Hibbard and Taylor, 1960; Oelrich, 1953; Rinker, 1949; Taylor and 

Hibbard, 1955; Tihen, 1954, 1955; van der Schalie, 

1953). In the Kingsdown silt, Meade County, Kans.
SUMMARY OF FAUNAL SEQUENCE 17

Fishes, amphibians, reptiles, mammals, and mollusks. 

Stratigraphic position and ecologic inferences suggest 

a late Sangamon age. Climate humid and mesothermal; summers were cooler and winters warmer than 

those of the area today. Significant members: Terrapene llanensis Oelrich, Arctodus simus (Cope), Oryzomys, Bison latifrons (Harlan), Promenetus exacuous (Say), Valvata tricarinata (Say), Laevapex kirkla,ndi (Walker), /Strobilops la~byrinthica (Say).

13. Cragin Quarry local fauna (Etheridge, 1958; 

Hibbard, 1949b; Hibbard and Taylor, 1960). In the 

Kingsdown silt, Meade County, Kans. Fishes, amphibians, reptiles, mammals, and mollusks. Stratigraphic 

position and ecologic inferences suggest an early Sangamon age. Climate semiarid and mesothermal; summers were slightly less hot, winters much warmer 

than those of today. Significant members: Terrapene 

llanensis Oelrich, Testudo, medium sized, Phrynosoma 

cornutum (Harlan), P. modestum Girard, Notiosorex 

crawfordi (Coues), Peromyscus progressus Hibbard, 

Promenetus kansasensis (Baker).

14. Jones Sink (lower level) (Goodrich, 1940; Herringtoii and Taylor, 1958). In the Vanhem formation, 

Meade County, Kans. Only mollusks have been recovered so far. Their Stratigraphic position close 

below the Jones local fauna and climatic inferences 

suggest a Wisconsin age. Climate microthermal, subhumid. Significant members: Pisidium obtusale 

Pfeiffer, P. lilljeborgi Clessin, P. subtruncatum Malm.

15. Jones local fauna (Downs, 1954; Herrington 

and Taylor, 1958; Hibbard, 1940, 1949; Hibbarcl and 

Taylor, 1960; Taylor and Hibbard, 1955; Tihen, 1942, 

1955). In the Vanhem formation, Meade County, 

Kans. Fishes, amphibians, birds, mammals, and mollusks. Stratigraphic position and climatic inferences 

suggest a Wisconsin age. No assignment to a particular subage is yet possible. Climate subhumid, 

microthermal; summer temperatures were much lower 

than those of southwestern Kansas today. Significant 

members: Camelops, Platygonus, Microtus pennsylvanicus (Ord), Pisidium walkeri Sterki, P. tilljeborgi 

Clessin, P. ferrugineum Prime, Valvata tricarinata, 

(Say), Lymnaea stagnalis jugularis Say, Pupil!a 

l)landi Morse.

16. Red Corral local fauna (Herrington and Taylor, 1958; Taylor, this paper). In an unnamed formation, in Oldham County, Tex. Mammals (principally 

all unpublished) and mollusks. The horse Plesippus 

indicates Blancan age, narrowed to late Pliocene by 

the mollusks. The fauna is equivalent, to or slightly 

older than the Rexroad, perhaps as old as the Saw 

Rock Canyon local fauna. Climate subhumid and 

mesothermal. Summers were cooler and moister than

those of the area today, winters not much if any cooler. 

Significant members: Plesippus, Nannippus, Gastrocopta paracristata Franzen and Leonard, G. rexroadensis Franzen and Leonard, G. peUucida hordeacella 

(Pilsbry), Ferrissia rivularis (Say), Promenetus um- 

~bi!ica tellus ( Cockerell).

17. Sand Draw local fauna (Herrington and Taylor, 1958; Hibbard, 1956, 1957; McGrew, 1944; Savage, 1955; Taylor, 1954, this paper). In an unnamed 

formation, in Brown County, Nebr. Fishes, reptiles, 

mammals, and mollusks. Faunal correlation and climatic inferences indicate a late Nebraskan age. Climate 

subhumid to humid and microthermal; summers were 

cooler and moister than those of the area today, but 

winters were no more severe. Significant members: 

Geomys quinni McGrew, Pliopotamys meadensis Hibbard, Gastrocopta chauliodonta Taylor, G. cristata 

(Pilsbry and Vanatta), Helicodiscus singleyanus 

(Pilsbry), Physa skinneri Taylor.

18. Dixon local fauna (Herrington and Taylor, 

1958; Hibbard, 1956, 1958a; Tihen, 1955). In an equivalent of or in the Missler member of the Ballard formation, in Kingman County, Kans. Amphibians, birds, 

mammals, and mollusks. Faunal correlation and climatic inferences indicate a latest Nebraskan or earliest 

Aftonian age. Climate mesothermal and subhumid. 

Significant members: Sorex. PUophenacomys meadensis Hibbard, Pliopotamys meadensis Hibbard, Pliolemmus antiquus Hibbard, Gastrocopta cliauliodonta Taylor, G. pellucida hordeacella (Pilsbry), Vallonia perspectiva Sterki, Valvata tricarinata (Say), Physa 

skinneri Taylor.

19. Berends local fauna (Herrington and Taylor, 

1958; Hibbard and Taylor, 1960; Mengel, 1952; Smith, 

1954, 1958; Starrett, 1956; Taylor and Hibbard, 1955). 

In a basin deposit, included in the undifferentiated 

Sanborn group, in Beaver County, Okla. Faunal evidence and climatic interpretations indicate an Illinoian age. Climate subhumid or humid, and 

microthermal. Significant members: Castoroides, 

Paradipoides stovalli Rinker and Hibbard, Perca flavescens (Mitchill), Esox masquinongy Mitchill, Physa 

skinneri Taylor, Valvata tricarinata (Say).

20. Bar M local fauna (Herrington and Taylor, 

1958; Hibbard and Taylor, 1960; Taylor and Hibbard, 

1955). The fauna is from two sinkhole fillings in 

Harper County, Okla. Mammals and mollusks. Stratigraphic position and climatic inferences indicate an 

Illiiioiaii or Wisconsin age. Climate subhumid or 

humid, and microthermal. Significant members: Dasypus belJus (Simpsoii), Microtus pennsylvanicus 

(Ord), Lymnaea stagnalis jugularis Say, Physa skin-
18 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

neri Taylor, Pupilla muscorum (Linnaeus), Discus 

cronkhitei ( Newcomb).

21. Slaton local fauna (Herrington and Taylor, 

1958; Meade, 1942, 1952). Lubbock County, Tex. 

Mammals, reptiles, and mollusks. Faunal correlation 

and ecologic interpretation suggest a Sangamon age. 

Climate mesothermal and subliumid or humid. Significant members: Neofiber leonardi Hibbard, Terrapene 

Uanensis Oelrich, Stagnicola caperata (Say), Promenetus kansasensis (Baker), Pupoides hordaceu-s 

(Gabb), Pupilla blandi Morse, Gastrocopta pellucida 

fiordeacella (Pilsbry).

22. Rezabek local fauna (Franzen and Leonard, 

1947; Frye, Leonard, and Hibbard, 1943; Herrington 

and Taylor, 1958; Hibbard, 1943). Lincoln County, 

Kans. Fishes, amphibians, reptiles, birds, mammals, 

and mollusks. Stratigraphic position and ecologic 

inferences indicate Sangamon age. Abundance of 

broken and badly worn shells suggests some may have 

been reworked. Significant members: Rorex cinereus 

Kerr, Microtus cf. M. pennsylvanicus (Ord), Neofiber 

leonardi (Hibbard).

CORRELATION OF NORTH AMERICAN AGES WITH 

LYELLIAN EPOCHS

For relating the Blancan, Irvingtonian, and Rancholabrean ages to the Lyellian epochs Pliocene and 

Pleistocene, southwestern Kansas and western Oklahoma is the most significant area in North America. 

This importance is due to a combination of several 

unusual factors, principally conditions of deposition 

peculiar to this area. Oversimplifying the picture, 

one may state that from the late Pliocene through the 

present continued solution at depth of Permian salt 

and gypsum beds has caused development of many 

sinkholes and large basins. The exceptionally thick 

deposits "trapped" in these depressions contain the 

most complete sequence of late Pliocene and Pleistocene continental faunas yet recorded. This chapter 

is intended to emphasize only the sequence of faunas 

and to show their broader implications. The foregoing summary of the f aunal sequence contains a more 

detailed treatment, listed by individual faunas.

In the western Oklahoma and southwestern Kansas 

area, the unusually detailed sequence is confined to the 

late Pliocene and Pleistocene. Clarendonian and Hemphillian faunas not of unusual significance are mentioned below only to indicate their presence in the 

area. Following a summary of the depositional and 

biological sequence is a correlation of this sequence 

with the Pliocene-Pleistocene boundary and the Blarican, Irvingtonian, and Rancholabrean ages.

SUMMARY OF DEPOSITIONAL AND BIOLOGICAL 

SEQUENCE

Hemphillian age. All Hemphillian fossils from the 

southwestern Kansas area come from the Ogallala 

formation. The grass seed Biorbia fossilia occurs in 

the upper part of the formation (Elias, 1942, p. 144; 

Hibbard, 1941b, p. 199). Three local faunas are 

known: Buis Ranch, Optima, and Swayze Quarry. 

The Buis Ranch local fauna (late Hemphillian) is 

closely related to the Saw Rock Canyon local fauna 

(earliest Blancan) in the basal part of the Rexroad 

formation. Deposition of the Ogallala formation was 

apparently followed by a period of major erosion but 

short duration, for the Rexroad formation (Blancan) 

is nowhere found overlying the Ogallala. Probably 

the Ogallala occurred as upland remnants when the 

Rexroad was being laid down at lower elevations.

Blancan age. Six superposed local faunas from 

three formations are assigned to the Blancan. In order 

of decreasing age and successive superposition these 

are as follows: Saw Rock Canyon, Rexroad, Bender 

(in the Rexroad formation), Deer Park, Sanders 

(Ballard formation), and Seger (Crooked Creek formation).

The relatively fine-grained Rexroad formation is 

known to represent a large time range by the differences between mammals of the Saw Rock Canyon and 

Rexroad local faunas. The Saw Rock Canyon local 

fauna might almost as well be termed Hemphillian as 

Blancan; the Rexroad local fauna is more characteristically Blancan, containing Ple.sippus and Nannippus. Both mammals and mollusks indicate that the 

climates in which these two faunas lived were mesothermal and subhumid or humid, lacking extremely 

cold winters and hot summers, and with more and 

better distributed rainfall than southwest Kansas 

receives now. Furthermore, the deposits and faunas 

overlying the Rexroad formation show 4 cycles of 

erosion and deposition of coarse materials in a cool 

climate separated by 3 intervals of mild climate with 

deposition of fine-grained sediments. The most reasonable interpretation of this sequence tentatively 

correlates the 4 cool-climate cycles with the 4 major 

continental glaciations, and regards the Rexroad formation as preglacial (here, equivalent to pre-Pleistocene). The upper part of the Rexroad formation, 

above the level of the Rexroad local fauna, contains 

a massive buried caliche zone indicative of a change 

to semiarid climate. Above the caliche, silt containing 

the Bender local fauna grades into sandy silts. This 

succession indicates a change from semiarid to moister 

climate.
CORRELATION OF NORTH AMERICAN AGES WITH LYELLIAN EPOCHS 19

The Ballard formation unconformably overlies the 

Rexroad formation. Its lower sand and gravel member has yielded glacially striated pebbles (Hibbard, 

1944), and scattered vertebrates. The higher silt member contains at its base the mild-climate Deer Park 

local fauna, a higher presumably interglacial buried 

caliche zone, and the still higher Sanders local fauna 

indicative of a subhumid mesothermal climate. As 

part of the first of four cool-climate erosional and 

depositional cycles, the lower part of the Ballard 

formation is considered probably Nebraskan, and the 

upper part probably Aftonian.

The Crooked Creek formation is a unit similar in 

lithologic succession to the unconformably underlying 

Ballard formation, but distinct from that formation 

in lithologic type. As part of the second of four coolclimate cycles of erosion and deposition, the lower part 

of the Crooked Creek formation is considered probably 

Kansan. The basal gravel of this unit contains the 

Seger local fauna, with such characteristically Blancan 

forms as Plesippus and Nannippus. For this reason 

the Blancan age includes the early part of the Kansan 

age.

Irvingtonian age. Three faunas, all from the upper 

part of the Crooked Creek formation, are referred to 

the Irvingtonian age. These are the Cudahy fauna, 

associated with the Pearlette ash bed; the Arkalon 

local fauna, equivalent to or very slightly later than 

the Cudahy; and the Borchers local fauna, stratigraphically the highest of these three faunas. From 

its position in the sequence the Crooked Creek formation is believed to be probably Kansan and Yarmouth 

in age. The Arkalon and Cudahy (implying microthermal climates) are termed Kansan; but the later 

Borchers local fauna indicates a warm, semiarid climate of probable Yarmouth age.

Rancholabrean age. Mammals from the younger 

deposits in the southwestern Kansas area are inadequate to place precisely the Irvingtonian-Rancholabrean boundary in terms of glacial ages. The late 

Kansan Arkalon local fauna is Irvingtonian, and the 

Sangamon Jinglebob local fauna is Rancholabrean. 

By analogy with the Blancan-Irvingtonian boundary, 

the middle Illinoian age may include the end of the 

Irvingtonian.

Later Pleistocene stratigraphy in the Meade County, 

Kans. area is more complex than that of the earlier 

Pleistocene, because of a change in type of deposition 

which occurred in about earliest Illinoian time. The 

lower Pleistocene Ballard and Crooked Creek formations are widespread sheet deposits; the fossils of these

two units can be related stratigraphically to one another with relative ease. Upper Pleistocene deposits, 

however, are of two chief types: fillings of valleys 

cut into the earlier formations, and isolated sinkhole 

deposits. After deposition of the Crooked Creek 

formation (that is, in post-Yarmouth time) two intervals of valley cutting and filling took place. Deposits 

of the first interval are included in the Kingsdown 

silt, those of the second are termed the Vanhem formation. The two units are correlated tentatively with the 

Illinoian-Sangamon and Wisconsin ages, respectively. 

The isolated sinkhole deposits, regardless of age, are 

included in the undifferentiated Sanborn group. These 

later Pleistocene deposits usually lack the massive 

buried caliche of earlier units, and may lack a basal 

gravel. This more complicated upper Pleistocene stratigraphy results in less stratigraphic control for these 

faunas. Warm-climate faunas are called Sangamon, 

and cool-climate faunas are referred to the Illinoian or 

Wisconsin, depending upon which unit they come 

from.

Two Illinoian faunas are from the undifferentiated 

Sanborn group: the Berends and Butler Spring local 

faunas. Both Sangamon assemblages, the Cragin 

quarry and Jinglebob local faunas, are from the Kingsdown silt. The Jinglebob local fauna is of interest in 

containing Bison latifrons, marking the late Sangamon 

first appearance of Bison in the Meade County area.

The Vanhem formation has yielded the youngest 

assemblage of fossils in the southwest Kansas area, the 

Jones local fauna.

CORRELATION

Previous discussions of the Pliocene-Pleistocene 

boundary and of the North American ages such as 

Hemphillian and Blancan have been handicapped by 

confusion of two essentially different categories. The 

North American ages are successive broad phases in 

the development of the North American mammalian 

fauna. The type section of the Pliocene-Pleistocene 

boundary in central Italy is based upon changes in 

marine invertebrate faunas; the Astian-Calabrian 

boundary is the one evidently considered definitive by 

the International Geological Commission. Italian 

mammalian assemblages no less than those from the 

United States are dated relative to the Pliocene-Pleistocene boundary by indirect correlation, not definition. Chapters in the history of land mammals of 

North America do not necessarily correspond to those 

of Europe, and neither of these necessarily corresponds 

to chapters in the history of marine invertebrates in 

the Mediterranean.

Pliocene-Pleistocene boundary. The 18th International Geological Congress recommended that the Plio-
20 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

cene-Pleistocene boundary have a type area in Italy, 

and that the marine Calabrian stage and its continental equivalent, the Villafranchian, be considered 

earliest Pleistocene (American Commission on Stratigraphic Nomenclature, 1949). The Pliocene-Pleistocene boundary in other parts of the world should be 

established with reference to this Italian type, but 

application of this principle is beset with difficulties 

of correlation as well as ambiguities in interpretation 

of the Congress' decision.

The most recent and most careful study of the Pliocene and Pleistocene stratigraphy of central Italy 

(Liittig, 1958) has shown the need for revision of previous ideas about the Villafranchian stage. The concept of this stage has been more broadly inclusive and 

poorly defined than realized, and includes more than 

simply the continental equivalents of the marine Calabrian stage. Llittig's conclusions are so significent 

in considering the Pliocene-Pleistocene boundary that 

it is desirable to quote some of his statements at 

length. After discussion of the classifications of Pliocene and Pleistocene sediments in northwestern Europe 

and in the Alps, Liittig (1958, p. 655-656) stated 

(translation) :

Both of the classifications cited above show that there is 

a series of readily recognizable stratigraphic entities older 

than the Mindel glacial interval, or the part of the Quaternary 

in northwestern Europe which corresponds to it, which are included in the "Villafraiichiano" of central Italy (under the 

assumption that they can be differentiated also in central 

Italy). From the results of Quaternary geology in central and 

northwestern Europe, the concept of the Villafraiichiano 

would then be put in a new light, if the observations made 

in Italy had not already led to the demand that, the "Villafranchiano" concept be applied no longer in central Italy 

or at least no longer in the previous way. At the type locality, 

in the rest of northern Italy and in France, observations are 

accumulating which favor the view of Lona (1950), Venzo 

(1056), and Movius (1949) that the Villafraiichiano in the 

strict sense is to be placed in the first warm interval of the 

Pleistocene, that is in the ?Tegelen interstadial or the 

Donau/Giinz interstadial. The continental Villafraiichiano 

is in striking correlation with the marine Calabriano. The 

differentiation of a warm from a cold Villafraiichiano must be 

discarded, for that which has been called "warm Villafraiichiano" is definitely to be placed in the Pliocene, according 

to Movius' useful summary and my own field work. The 

faunas and floras of the "cold Villafraiichiano" document the 

selection of species caused by the first significant invasion of 

cold of the Pleistocene, in which the warmth-loving "Tertiary 

elements" were partly decimated. The faunas and floras of 

the Valdarno superiore, which have been called quite inadmissibly typical of the "Villafranchiano," range from the 

(middle) Pliocene to (at least) the Tegelen interstadial. The 

Villafraiichiano in the strict sense is only a fraction of this, 

and it is not permissible to use this concept any longer for 

deposits which may have an age from middle Pliocene to 

Mindel.

If one considers this critical view correct, the result is that 

none of the stratigraphic concepts previously applied in the 

nonmarine Quaternary (and Pliocene) of central Italy satisfy 

the demands which are put on stratigraphy. We may derive 

from this the demand, that a new stratigraphy of the central 

Italian Quaternary must be provided, and this must naturally 

happen from the clarification of the local relationships themselves, lienee from some kind of local classification.

The descriptions of the stratigraphy in various local 

areas of central Italy given by Liittig (1958) are 

necessary for understanding the regional relationships 

of the Calabrian and Villafranchian sediments, but 

need not be repeated here. Liittig's discussion of the 

sequence in the upper Arno Valley, however, is so 

important as a basis for correlation with the series of 

faunas from the Great Plains described in this paper 

that, part of it (Liittig, 1958, p. 659-660) is quoted 

here (translation) :

The Yaldarno superiore: The classic locality of Plio-Pleistoceue faunas and floras, which have been erroneously called the 

typical fossil associations of the Villafranchiano, includes 

thick lacustrine clay and silt, which are truncated above by 

sands and fluviatile gravels. Within the lacustrine clay lies 

the boundary between Pliocene and Pleistocene. Consideration 

of the fossils shows that they can be divided into two types: 

Type a: fossils of a warm to subtropical character, Type b: 

fossils of temperate climate, which therefore show that a 

cold-invasion took place during or before their dispersal. The 

first "glacial interval" of the Pleistocene corresponds to this 

cold-invasion. The fossils of type a occur in the lower clays 

of the Valdarno (Stellicone series); in these clays occvirs 

the greater part of the lignite, in particular the deposits of 

Santa Barbara, Gaville, Tegolaia, Monastero and San Donato 

in Avane. The fossils of type b are restricted to the higher 

parts of the lake beds (Ville beds). Both sedimentary complexes are separated by an "unconformity" according to observations by Sestini (1936). The reasoning for this unconformity of Sestini, which Movius (1940) also put to use, I 

cannot follow, but in effect come to the same conclusion. At 

Ricasoli may be seen fluviatile gravels at an horizon which 

corresponds to Sestini's unconformity, and which as the 

Ricasoli beds represent the first cold time of the Pleistocene. 

A division of the lake beds cannot be doubted. The hypothesis 

of a lower warm and an upper cold "Villafranchiano" is superfluous ; the "warm Villafranchiano" is middle to upper Pliocene, the "cold Villafranchiano" corresponds to the first warm 

interval of the Pleistocene, the Ville series, and the decimation 

of the fauna and flora of a warm interval which is shown in 

fossil-type b, occurred during deposition of the Ricasoli series. 

The overlying gravels of the so-called Sansino series are to 

be placed in the second cold interval of the Pleistocene.

If one wishes, the Ville series can be equated to the Villafraiichiano in the strict sense. Since, however, this concept 

has been used in this area in a wider sense instead, a new 

usage in another sense would bring more confusion than order.

Although some confusion in the concept of the Villafranchian fauna may have been due to inadequate 

locality information, part may also have been due to 

facies changes. According to Liittig's descriptions,
CORRELATION OF NORTH AMERICAN AGES WITH LYELLIAN EPOCHS 21

the Astian (late Pliocene) deposits of central Italy 

are marine almost everywhere except in the upper 

Valdarno, where all of the Piacenzian and Astian 

equivalents are continental.

Correlation between the High Plains and central 

Italy on the basis of fossil mammals has been attempted, but is unreliable. The number of mammals 

known from late Pliocene deposits in the area selected 

by the International Geological Congress as the standard of reference for the Pliocene-Pleistocene boundary 

is very small indeed, and most of the mammals which 

have been considered as the typical Villafranchian 

fauna from this area are not of earliest Pleistocene 

age (Liittig, 1958; Thenius, 1959). Furthermore, the 

latest Pliocene-earliest Pleistocene time interval involved is relatively short, and it seems that dispersal 

lag might affect mammalian correlations significantly 

even though it is unimportant in earlier parts of the 

Tertiary.

The most practicable, and perhaps also the most 

precise correlation of the Pliocene-Pleistocene boundary between the Great Plains and the type area in 

central Italy is adoption of the earliest horizon with 

evidence of marked climatic cooling in temperate latitudes as representing the earliest Pleistocene. In 

southwestern Kansas and northwestern Oklahoma, 

where the geologic record of late Pliocene and Pleistocene times is more nearly complete than elsewhere 

in the Great Plains, the Pliocene-Pleistocene boundary 

is on this criterion between the Rexroad and Ballard 

formations. These two units are separated by an 

erosional unconformity which represents an hiatus 

of uncertain extent.

Blancan age. The term Blancan was proposed 

(Wood and others, 1941) for a group of mammalian 

assemblages considered roughly contemporaneous and 

characterized by the association of (among others) 

Plesippus, Nannip'pus, and Borophagus. The name, 

but not the entire basis for the term, was taken from 

the Blanco local fauna of Texas. The time characterized by this composite faimal concept was called 

the Blancan Provincial Age, and was thought to be 

late Pliocene.

Since establishment of this term, evidence has accumulated that many Blancan faunas lived during the 

early Pleistocene (Nebraskaii to early Kansaii). Other 

studies, principally by C. W. Hibbard and others in 

southwestern Kansas, have shown that Blancan assemblages lived both before and after the beginning of 

continental glaciation. Much of the confusion about 

the age of the Blancan interval comes from the tacit 

oversimplification by many paleontologists that all 

Blancan faunas lived during a relatively short inter508945 O 60___3

val, and that the faunas must be either Pliocene or 

Pleistocene.

Another reason for which the Blancan age has been 

correlated with the early Pleistocene is the belief that 

the marked faunal break between the Kimball and 

Broadwater formations of the Nebraska Geological 

Survey does not imply a considerable time interval. 

(See Schultz and Stout, 1948). The Kimball has been 

regarded as late Pliocene, the Broadwater as early 

Pleistocene. According to the interpretations and correlations accepted here, however, the Kimball is middle 

Pliocene, the Broadwater is Pleistocene, and the late 

Pliocene is unrepresented in the Great Plains north 

of southwestern Kansas.

Schultz and Stout (1948, p. 556) summarized the 

significant differences between the fossil mammals 

from the Kimball and Broadwater formations. The 

rhinoceroses, longirostrine mastodonts, and transitional PUohippus-Plesippus from the Kimball suggest 

a late Hemphillian assemblage. If the Broadwater 

formation is Pleistocene, then the earlier Blancan 

interval represented by the Rexroad formation in 

Kansas does not have an equivalent unit in western 

Nebraska. The correlation of the middle Pliocene to 

early Pleistocene deposits of southwestern Kansas and 

western Nebraska with those of central Italy (as classified by Liittig, 1958) is shown in table 6.

TABLE 6. Correlation of middle Pliocene to lower Pleistocene 

deposits in Italy and the High Plains

North American ages

Hemphillian

Southwestern 

Kansas

Stump Arroyo 

member of 

Crooked Creek 

formation

Ballard 

formation

Rexroad 

formation

Ogallala 

formation

Western Nebraska

Broadwater ' 

formation

(erosion)

Ogallala * 

group

Central Italy stages

Arno Stage 

(Pleistocene)

(Pliocene) 

Astian Stage

Piacenzian 

Stage 

?

i Terminology of Nebraska Geological Survey.

Irvingtonian and Rancholabrean ages. -Correlation 

of the upper limit of the Blancan, and of the limits 

of the Irvingtonian and Rancholabrean ages with the 

glacial and interglacial stages of the midcontinent 

region is now possible only in southwestern Kansas. 

It is hardly definite, however, for the glacial and 

interglacial intervals recognized in southwestern Kansas are correlated in turn with the Mississippi Valley 

area. Accepting these correlations, however, the Blan-
22 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

can-Irvingtonian boundary falls within the Kansan 

age, and the Irvingtonian-Rancholabrean boundary 

falls within the Illinoian age.

DESCRIPTION OF LOCAL FAUNAS 

BUIS RANCH LOCAL FAUNA

Previous work. The Buis Eanch fossil locality was 

discovered in 1951 by a University of Michigan field 

party under the supervision of C. W. Hibbard. Subsequent collecting by Hibbard and other Michigan 

groups has yielded a small fauna, especially interesting because it shows relationships to both Hemphillian and Blancan assemblages. Previous references 

to the mollusks are by Herrington and Taylor (1958) 

and Hibbard (1954).

Fauna. Following is a list of the Buis Ranch local 

fauna:

Class Pelecypoda

Order Teleodesmacea

Pisidium casertanum (Poll) 

Class Gastropoda

Order Basommatophora

Stagnicola caperata (Say)

Ferrissia rivularis? (Say) 

Order Stylommatophora

Strobilops sparsicostata Baker

Vertigo ovata Say 

Class Amphibia 

Order Caudata

Ambystomatidae, indet. 

Order Salientia

Frogs or toads, or both 

Class Reptilia

Order Chelonia

Testudo twffida Cope 

Order Squamata

Snake and lizard bones 

Class Mammalia

Order Insectivora

Hesperoscalops sp. 

Order Carnivora

Buisnictis schoffl Hibbard 

Order Rodentia

Citellus dotti Hibbard

Perognattiiis cf. P. mclaugMini Hibbard

Prodipodomys sp.

Pliogeomys buisi Hibbard

Cricetidae, indet. 

Order Lagomorpha

Leporidae, indet. 

Order Artiodactyla

Giant camel 

Order Perissodactyla

Nannippus sp.

Rhinoceros, indet.

Occurrence. The Buis Ranch local fauna is known 

only from Beaver County, Okla.

Stratigraphy. Hibbard (1954) reported the faumi 

to occur in the lower part of the Rexroad formation. 

Later fieldwork, however, has shown that it occurs in 

the Ogallala formation of that area (Tihen, 1955, p. 

238). Apparently both Permian rocks and Ogallala 

formation sagged, perhaps because of ground water 

solution of salt and gypsum at depth. The Ogallala 

was thus kept largely below the water table, so that 

weathering could not form the mortar beds so characteristic of the formation in northwestern Oklahoma 

and southwestern Kansas.

Localities. Only one locality is known, on the west 

side of Buckshot Arroyo, Buis Ranch, NEV4SWV4 

sec. 5, T. 5 N., R. 26 E., Beaver County, Okla.

Age. Perognathus cf. P. mclaughlini, and Pliogeomys suggest that the Buis Ranch local fauna is 

of approximately the same age as the Saw Rock 

Canyon local fauna (earliest Blancan). The presence 

of a rhinoceros tends to indicate a Hemphillian, rather 

than Blancan, age. A latest Hemphillian age thus 

seems reasonable.

Mollusks are so rare that they cannot give an accurate picture of the fauna which lived in the area. The 

occurrence of Vertigo ovata, unknown from the thoroughly collected Saw Rock Canyon fauna, suggests 

a greater age for the Buis Ranch local fauna, however, 

for the mutually exclusive occurrence of Vertigo Jiibbardi and V. ovata suggests ecologic replacement. V. 

ovata is known from the Clarendonian Laverne local 

fauna and from Pleistocene faunas, but is absent from 

the Saw Rock Canyon and Rexroad local faunas. V. 

hibbardi is known only from these last two faunas.

Paleoecology. Climate: Stagnicola caperata occurs 

in the High Plains as far South as Nebraska. It suggests cooler summers at the time the Buis Ranch fauna 

lived. Ferrissia requires permanent water, and implies 

greater rainfall than northwest Oklahoma receives 

today. Habitat: The few species and their rarity 

suggest the possibility that the mollusks may not have 

lived where their shells were found. Ferrissia rivularis is a stream snail, Stagnicola caperata a temporary 

pond species.

SAW BOCK CANYON LOCAL FAUNA

Previous work. The Saw Rock Canyon local fauna 

was discovered in 1943 by Thad G. McLaughlin and 

Claude W. Hibbard. Subsequent fieldwork has been 

by Hibbard and parties from the Universities of Kansas (1944) and Michigan (since 1950). Hibbard 

(1944a, b) named the fauna and described vertebrates 

from the deposit. Later stratigraphic studies and 

more vertebrate material (principal reference Hibbard,
DESCRIPTION OF LOCAL FAUNAS 23

1953) have emphasized the transitional HemphillanBlancan aspect of the fauna. Previous references to 

the mollusks are by Franzen and Leonard (1947), 

Frye and Leonard (1952, p. 151, Seward County 

locality), Herrington and Taylor (1958), and Leonard 

(1952a). Mollusks collected by University of Michigan parties form the chief basis for the present report. 

Fauna. Following is a list of the Saw Rock Canyon 

local fauna:

Class Pelecypoda

Order Teleodesmacea

Sphaerium striatimtm (Lamarck)

sp.

Pisidium casertanum (Poll) 

Class Gastropoda

Order Mesogastropoda

Marstonia decepta (Baker)

crybetes (Leonard) 

Order Basommatophora

Stagnicola bulimoides techclla (Haldeman)

sp.

Fossaria dalli (Baker) 

Gyraulus parvus (Say) 

Helisoma anceps (Menke) 

Promenetus Jcansasensis (Baker)

unibilicatellus (Cockerell) 

Ferrissia rivularis (Say) 

Physa anatina Lea 

Order Stylommatophora

StroMlops laltyrinthica, (Say) 

Gastrocopta holsingeri (Sterki) 

fransenae Taylor

paracristata Franzen and Leonard 

rexroadensis Franzen and Leonard 

tappaniana (Adams) 

Pupoides alMlabris (Adams) 

Vertigo MJ)~ba,rdi Baker

milium (Gould) 

Vallonia perspectiva Sterki 

cf. Succinea

Deroceras aenigma, Leonard 

Helicodiscus singleyanus (Pilsbry) 

Nesovitreaf sp. 

Hawaiia minuscula (Binney) 

Class Osteichthyes

Small catfish 

Class Amphibia 

Order Caudata

Ambystomatidae, indet. 

Order Salientia

Frog and toad bones 

Class Reptilia

Order Chelonia

Turtle, indet. 

Order Squamata

Eumeces striatiilatus Taylor 

Snake, indet. 

Class Aves

Unstudied bird remains

Class Mammalia

Order Insectivora

Soricidae, indet. 

Order Rodentia

Marmota? sp.

Pliogeomys sp.

Perognathus mclaughlini Hibbard

Prodipodomys sp.

Dipoides ivilsoni Hibbard

Onychomys larralteei Hibbard

Baiomys sawrockensis Hibbard

Cimarronomys stirtoni Hibbard

Ogmodontomys sawrockensis Hibbard 

Order Carnivora

Osteoborus progressus Hibbard

Buisnictis cf. B. schoffi Hibbard 

Order Artiodactyla

Gigantocamelus cf. G. spatulus (Cope)

Occurrence. The Saw Rock Canyon local fauna is 

known only from Seward County, southwest Kansas.

Stratigraphy. See Hibbard, 1949a, p. 92-97. The 

fauna occurs near the base of the Rexroad formation 

in the XI member.

Localities. Only one locality is known, near the 

center of the west line of sec. 36, T. 34 S., R. 31 W., 

Seward County, Kans.

Age. Essentially all mollusks of the Saw Rock 

Canyon local fauna occur also in the Rexroad local 

fauna, but considerable age difference between the two 

is indicated by the associated mammals. Hibbard 

(1949a) considered the Saw Rock Canyon local fauna 

as either late middle Pliocene or early late Pliocene, 

and later (Hibbard, 1953) as early late Pliocene. The 

Rexroad local fauna (which see) is of later late Pliocene age.

Leonard (quoted by R. C. Moore, in McLaughlin, 

1946, p. 33) stated that "fossil mollusk assemblages 

associated with the Saw Rock Canyon vertebrates are 

clearly differentiated from those of the type Rexroad." 

This distinction was maintained by Leonard (1948). 

Frye and Leonard (1952) indicated that all Saw Rock 

Canyon mollusks occurred in the Rexroad local fauna 

also, but did not discuss the previously held difference. 

They further believed the faunas to be of the same age, 

but did not consider the conflicting vertebrate evidence.

Paleoecology. Climate: Promenetus umbilicatellus 

has a northern distribution in the High Plains, ranging ~ as far south as Nebraska. It indicates summers

without the present extremes of heat. Stagnicola 

bulimoides techella is found in the High Plains only 

as far north as Kansas. It shows that winters were 

very slightly, if at all, cooler than now, and may even 

have been milder.
24 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Table 7 compares the Blancan and Recent molluscan 

faunas of southwestern Kansas. There are two probably significant differences between the Recent and 

Saw Rock Canyon faunas: The fossil fauna has four 

snails requiring permanent water, the Recent none. 

There are two fossil forms needing humus in wooded 

spots, but the better known Recent fauna has but one 

rare species of such a habitat. In comparing the two 

faunas it should be noted that the Recent list is 

slightly increased by permanent water species found 

only in cool artesian springs, and not characteristic of 

the area as a whole.

TABLE 7. Comparison of Blancan and Recent molluscan faunas 

of southwestern Kansas, by habitats

[Recent list based on Lee (1951), Leonard (1943), Miles (1958), and personal collections 

in Meade County]

Habitat

Permanent water: 

Stream. _____ .

Pond or stream _ __

Pond..-. ___________

Permanent to temporary: 

Permanent or subpermanent.

Permanent or temporary.

Temporary water: 

Temporary pond or

marginal pool.

Temporary pond or 

stream.

Marginal pools and 

wet mud.

Semiaquatic, riparian

habitat. 

Moister humus. _____

Damp humus or grass

Damp humus o

wooded area.

Species

Anodonta grandis Say..--.

Helisoma anceps (Menke).

Marstonia crybetes (Leonard). 

decepta (Baker) __ __

Sphaerium striatinum (Lamarck). 

transversum (Say). ....

^Ligumiasubrostrata (Say) .

man). 

Helisoma trivolvis (Say) 

Physa anatina Lea. .. _

Promenetus exacuous (Say)_

kansasensis (Baker) -..-_ 

Uniomerus tetralasmus-

(Say). 

Gyraulus parvus (Say). _ _ 

Stagnicola exilis (Lea) . _ . . -

sp. ______________________

Aplexa hypnorum (Linnaeus) . 

Phidium casertanum (Poll).

Promenetus umbilicatellus 

(Cockerell).

bulimoides techetta (Haldeman).

Ferriss) . 

Fossaria dalli (Baker)...-

Gastrocopta tappaniana 

(Adams). 

Vertigo milmm (Gould). _.

(Sterki).

bardt.

(Say).

(Gould).

(Say).

7onitoides arboreus (Say).

3aw 

,ock Canyon 

ocal 

auna

v

X

X

X

X

X

X

X

X

X

X

X

X 

X

X

?

v

]

.exoad 

ocal 

auna

v

X

X

X

v

X

X

X 

X

X

X

X

X

X

X 

X

X

X

X

X

X

v

?

Fauna

Bender 

ocal 

'auna

v

- 

v

X 

X

X

X

X 

X

V

anlers 

ocal 

auna

X

X

X

v

X

X

X

X 

X

Reent

v

v

X

X

X

v

V

X 

X

v

V

v

TABLE 7. Comparison of Blancan and Recent molluscan faunas 

of southwestern Kansas, by habitats Continued

[Recent list based on Lee (1951), Leonard (1943), Miles (1958), and personal collections 

in Meade County]

Habitat

4

Species

Vanatta).

(Pilsbry).

Hawaiia minuscula (Binney). 

Helicodiscus singleyanus 

(Pilsbry). 

Pupoides albilabris 

(Adams) .

Gould.

Deroceras aenigma Leonard.

lor. 

paracristata Franzenand 

Leonard.

Leonard.

Taylor.

atta.

Vattonia perspectiva Sterki.

SawRock Canyon 

local 

fauna

X 

X 

X

X

X

v

v

X 

X

Rexroad 

local 

fauna

X

X 

X 

X

X

X

X 

X

v

v

X

X

X 

X

Fauna

Bender 

local 

fauna

X

X 

X 

X

X

v

X

v

v

Sanders 

local 

fauna

v

X 

X 

X

X

X

X

X

X

X

X

Recent

v

X

X

X 

X 

X 

X

 

A former climate explaining all these data would 

differ from that of the present by less extreme summer 

hot spells and rainfall not necessarily much greater but 

more effective, probably within the 20-30 inches per 

year range. The minimum changes one needs to postulate to explain the former molluscan fauna are summer 

rains occurring more often and more gently, rather 

than as occasional intense thundershowers; summer hot 

spells less extreme; and annual precipitation perhaps 

increased to 25 inches per year.

Habitat: Table 8 summarizes the habitat indications 

of the mollusks of the Saw Rock Canyon local fauna. 

The site of deposition apparently was close to three 

sorts of aquatic habitats: a permanent, slow moving 

stream, shallower water near shore, with dense vegetation, and fluctuating lagoons and backwaters with 

shallow, muddy borders.

Two terrestrial habitats may be distinguished also, 

moist to quite damp humus associated with dead wood 

and decaying leaves, the floor of a wooded area, and a 

slightly dryer but still protected habitat, perhaps more 

open grassy areas. Deroceras and cf. Succinea may 

have been associated in a transitional, nearly semiaquatic situation, but their habitat preferences are unknown for sure.
DESCRIPTION OF LOCAL FAUNAS 25

TABLE 8. Habitat indications of mollusks of Saw Rock Canyon 

local fauna

[A, abundant (>1,000); C, common (101-1,000); S, scarce (21-100); R, rare (1-20)]

Habitat

Permanent water: 

Pond or stream.

Stream_____________ 

Permanent to temporary water: 

Permanent or subpermanent 

Permanent or temporary______

Temporary pond or marginal pool.

Temporary pond or stream..______

Marginal pools or wet mud. 

Moister humus_______ 

Damp humus or grass...___

Damp humus of wooded areaDamp to dry ground_____.

UncertainSpecies

Helisoma anceps (Menke)..____-. 

Marstonia crybetes (Leonard)__ . 

decepta (Baker)_________. 

Sphaerium striatinum (Lamarck).... 

Ferrissia rivularis (Say)_______.

Physa anatina Lea_____..._. 

Promenetus kansasensis (Baker)._- 

Gyraulus parvus (Say)_____ - 

Stagnicola sp.. __________ - 

Pisidium casertanum (Poli)..___- 

Promenetus umHlicatellus (Cockerell). 

Stagnicola bulimoides techella (Haldeman).

Fossaria dalli (Baker)...____ . 

Vertigo mttium (Gould)._.___...__ . 

Oastrocopta holzingeri (Sterki).....

tappaniana (Adams)._.____. 

Nesovitreaf sp_.___________. 

Strobilops labyrinthica (Say)....__. 

Hawaiia minuscula (Binney)__ . 

Helicodiscvs singleyanus (Pilsbry)... 

Pupoides albilabris (Adams).___. 

Oeroceras aenigma Leonard ____.. 

Oastrocopta framenae Taylor.... .

paracristata Franzen and Leonard.

rexroadensis Franzen and Leonard.

Sphaerium sp_.._________ . 

cf. Succinea... _____.__..___---. 

Vallonia perspectiva Sterki_____. 

Vertigo hibbardi Baker.____ .

Abundance

Before combining these data to reconstruct the area, 

we may note that the sediments containing the fauna 

are all fine grained fine sand, silt, and clay. There 

are no coarse elastics above the rubble incorporated in 

the base of the Rexroad formation.

These data suggest that the Saw Rock Canyon local 

fauna lived in and close to a perennial, slow-moving 

stream, such as a large creek or river. There were 

wooded areas along the stream, and perhaps also 

patches of open grassland. The timbered area was 

strictly riparian, not covering the uplands.

BED CORRAL LOCAL FAUNA

Previous work. In the summer of 1954 D. E. Savage 

and a University of California Museum of Paleontology field party visited a group of Frick Laboratory 

vertebrate quarries southwest of Channing, Tex. In 

its brief visit the party observed mollusks and collected 

scraps of mammalian fossils. Later in the same year 

C. W. Hibbard went to the site to collect the mollusks. 

The name Red Corral local fauna is applied to the 

mammals and mollusks known from the quarries 10 

miles southwest of Channing, on the west side of the 

valley of Rita Blanca Creek. The only fossils previously described from the assemblage are the sphaeriid 

clams (Herrington and Taylor, 1958).

Fauna. Following is a list of the Red Corral fauna:

Class Pelecypoda

Order Teleodesmacea

Pisidium casertanum (Poli) 

Class Gastropoda

Order Basommatophora

Stagnicola, bulimoides tecJiella (Haldeman) 

Gyraulus parvus (Say) 

Promenetus kansasensis (Baker)

umbilicatellus (Cockerell) 

Ferrissia rivularis (Say) 

Physa anatina Lea 

Order Stylommatophora

Strobilops sparsicostata Baker 

Gastrocopta franzenae Taylor 

pellucida hordeacella (Pilsbry) 

paracristata Franzen and Leonard 

rexroadensis Franzen and Leonard 

Pupoides inornatus Vanatta 

Vertigo milium (Gould) 

Pupillidae?, indet. 

cf. Succinea

Deroceras aenigma Leonard 

Hawaiia minuscula (Binney) 

Class Mammalia

Order Perissodactyla 

Plesippiis sp. 

Nannippus sp.

Occurrence. The Red Corral local fauna is known 

only from northern Oldham County, Tex.

Stratigraphy. Essentially no data are available. 

The fossiliferous unit in the immediate vicinity of the 

fossil locality is a west-dipping series of sand and clay.

Localities. (USGS Cenozoic loc. 21040). Only one 

mollusk locality is known, included in aerial photograph DAY 10M 63. A west-dipping unit of sand 

and clay is exposed in the upper part of draws running 

into the west side of Rita Blanca Creek. In the basin 

of a north-northeast-trending draw about half a mile 

south of the county line and about three-quarters of a 

mile north of a red corral are several Frick Laboratory 

vertebrate quarries. All or most of these quarries are 

about 20 feet stratigraphically below 2- to 3-foot-thick 

bed of massive caliche. Shells were collected from a 

fine to very fine compact sand immediately below a 2- 

f oot bed of carbonaceous papery clay shale with abundant crushed shells at the north end of one of the quarries. This quarry is on the east side of the main draw, 

just south of a minor tributary gully.

Age. Among the vertebrate material in University of California collections from a Frick Laboratory 

quarry close to and at the same stratigraphic horizon 

as the mollusk locality are Plesippus and Nannippus, 

indicative of Blancan age.

The mollusks suggest correlation of the Red Corral 

and Rexroad local faunas. Virtually all species of
26 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

the Red Corral local fauna occur also in the Rexroad 

local fauna. (See tables 2 and 4.)

Paleoecology. Climate: Two species (Gastrocopta 

pellucida hordeacella and Stagnicola bulimoides techella) have southern distributions in the United 

States. In the High Plains they range as far north as 

Kansas. These two suggest that winters were not 

much if at all more severe than those of the Texas Panhandle today. Promenetus umbilicatellus, of northern 

distribution, occurs in the High Plains as far south as 

Nebraska. It suggests that the Red Corral fauna lived 

in a climate with summers lacking the present extremes 

of heat and temperature.

Recent mollusks of the Texas Panhandle are practically unknown. Several local lists have been published, 

but nearly all are drift collections which may be contaminated by Pleistocene shells. The list given by 

Clarke (1938) is based partially on drift also, but at 

least there are no obvious anomalies of distribution. 

Palo Duro Creek (spelled Paladora by Clarke) has 

cut deeply into the eastern edge of the Llano Estacado. 

Permanent water and the protected situation in a 

deep canyon probably give an assemblage unusually 

varied for the Texas Panhandle. Clarke did not record 

the exact site of his collection, but distance and direction 

given ("* * * Paladora Creek which lies 4 miles east 

and 3 miles north of Canyon, Tex.") indicate Palo 

Duro Creek near 6-mile crossing, 10 miles upstream 

from Palo Duro State Park, Randall County, Tex. The 

locality is about 40 miles southeast of the Red Corral 

site.

TABLE 9. Habitat indications of mollusks of Red Corral local fauna 

[A, abundant (>100); C, common (21-100); S, scarce (6-20); R, rare (1-5)]

Habitat

Permanent stream_________________

Permanent to temporary water: 

Permanent or subpermanent..-

Permanent or temporary._... 

Temporary water:

Temporary pond or marginal 

pool.

Temporary pond or stream_.,.

Moister humus _.____--__-..

Damp humus of wooded areaDamp to dry ground..........

Uncertain.....................

Species

Ferrissia rivularis (Say).

Physa anatina Lea____--_________.

Promenetus kansasensis (Baker),.... 

Gyraulus parvus (Say).__.____.......

Pisidium casertanum (Poll)... ______

Promenetus umbilicateUus (Cockerell). 

Stagnicola bulimoides techella (Haldeman).

Vertigo milium (Gould)___._.___._.. 

Strobilops sparsicostata Baker..-___. 

Hawaiia minuscula (Binney). ______

Deroceras aenigma Leonard ________

Gastrocopta paracristata Pranzen and 

Leonard.

pellucida hordeacella (Pilsbry)_._ 

rexroadensis Pranzen and Leonard. 

franzenae Taylor__--__-------__

Pupoides inornatus Vanatta.-_.___. 

cf Succinea..........................

PupUlidl. .___._____-_____-.-____-__

Abundance

Table 10 compares the mollusks of the Red Corra] 

local fauna with the Recent collection from Palo Duro 

Canyon. This list is modified from Clarke (1938) a:

TABLE 10. Comparison of mollusks of Red Corral local fauna 

with Recent mollusks from Palo Duro Canyon, Texas, by habitats

[Recent list from Clarke (1938), modified as explained in text]

Habitat

Permanent water:

Permanent to temporary 

water: 

Permanent or subpermanent.

Permanent or temporary...

Temporary water: 

Temporary pond or marginal pool.

Temporary pond or stream. 

Marginal pools and wet mud.

Damp humus of wooded area.

Species

Promenetus kansasensis (Baker) ...

Promenetus umbilicatellus (Cockerell). 

Stagnicola bulimoides techella 

(Haldeman) .

Hawaiia minuscula (Binney) ------

Gastrocopta paracristata Franzen 

and Leonard. 

pellucida hordeacella (Pilsbry). _. 

rexroadensis Franzen and Leonard.

Red 

Corral

X

X 

X 

X

X 

X

X

X

X

X

X 

X

X 

X

X 

X 

X

Recent

X 

X 

X 

X

X

X 

X

X 

X 

X

X 

X

X 

X 

X 

X 

X

X

X

follows: Vallonia costata and V. perspectives, are considered V. parvula following Pilsbry (1948, p. 1028). 

Succinea avara is changed to cf. /Succinea. Other 

changes are nomenclatural.

Two differences appear significant at first: The Red 

Corral local fauna has one permanent stream snail, the 

Recent assemblage none. The Red Corral fauna includes several temporary water species, the Recent assemblage none. In comparing these two faunas it must 

be remembered that the Recent collection is from a 

deep canyon with a permanent stream supplied by 

springs and seepage, but that the Red Corral local 

fauna lived in a shallow, exposed valley.

Habitat indications of the Red Corral local fauna 

(see table 9) suggest the presence of some woodland 

and moist humus, as well as seasonal ponds and a permanent stream. The occurrence of /Strobilops, not now 

found in the Great Plains except in woodland at the 

eastern edges, is especially significant.

These data and inferences suggest that the Red 

Corral local fauna lived in a climate with winters not 

much if at all more severe than those of the area today, 

summers lacking present extremes of heat and drought, 

and a greater rainfall of about 30 inches per year.

Habitat: Table 9 summarizes the habitat indications
DESCRIPTION OF LOCAL FAUNAS 27

of the mollusks of the Ked Corral local fauna. The 

four species classed as abundant suggest a shallow pond 

fluctuating annually, with thick, submerged vegetation. 

The other aquatic species fit such a picture, except for 

Ferrissia rivularis, which requires permanent water. 

Probably the pond was a lagoon or oxbow lake near a 

permanent stream. The occurrence of Strobilops indicates the presence of woodland and moist humus, but 

there are so few land snails, and most of these are so 

scarce, that this habitat was probably not close to the 

site of deposition.

BEXROAD LOCAL FAUNA

Previous work. Hibbard (1938) named the Rexroad local fauna and described vertebrates from it. 

Subsequent field work has been by Hibbard and parties 

from the University of Kansas (1936-46) and University of Michigan (1947 to date). The rich vertebrate 

fauna has been described in numerous papers summarized by Hibbard (1950, 1954a). Later contributions are by Hibbard (1956, p. 185), Oelrich (1957), 

Savage (1955, p. 67-68), and Tihen (1955). The mollusks of the Rexroad local fauna have been studied 

primarily by Baker, Franzen, and Leonard (Baker, 

1938; Franzen and Leonard, 1947; Frye and Hibbard, 

1941, p. 408; Frye and Leonard, 1952, p. 151, Meade 

County localities; Herrington and Taylor, 1958; Hibbard, 1941, p. 95; 1941a, p. 265; Leonard, 1950, p. 38; 

1952a; 1957; Smith, 1940, p. 98). The most nearly 

complete lists are those of Baker (in Hibbard, 1941, 

p. 95) and Leonard (Frye and Leonard, 1952, p. 151).

According to Hibbard (written communication, 

November 29, 1954) most of the University of Kansas 

material reported from the SW*4 sec. 22, T. 33 S., R. 

29 W., Meade County, Kans. (collected by Hibbard 

and Leonard), is from localities la, Ib, and Ic of the 

Bender local fauna; some is from Rexroad locality 3. 

Several species reported from University of Kansas 

collections were not found by University of Michigan 

parties, and hence their stratigraphic horizon is in 

doubt. Sphaerium sp., Marstonia crybetes (Leonard), 

and Helisoma anceps (Menke) have habitat requirements which suggest they came from Rexroad locality 

3. Gastrocopta rexroadensis Franzen and Leonard and 

CioneUa lubrica, (Muller) have been found at other 

Rexroad localities, but not in the Bender local fauna, 

and so probably came from Rexroad locality 3. Zonitoides arboreus (Say) is listed with a query under both 

faunas.

Fauna. Following is a list of the Rexroad local 

fauna:

Class Pelecypoda

Order Prionodesmacea

fLigumia subrostrata (Say) 

Order Teleodesmacea 

SpJiaerium sp.

Pisidium casertanum (Poll) 

Class Gastropoda

Order Mesogastropoda

Marstonia crybetes (Leonard) 

Order Basommatophora

Carychtum exiguum (Say) 

Stagnicola bulimoides techella, (Haldeman) 

caperata (Say) 

exilis ( Lea) 

Fossaria dalli (Baker) 

Gyraitlus parvus (Say) 

Helisoma anceps (Menke) 

Promenetus kansasensis (Baker)

umbilicatellHS (Cockerell) 

Ferrissia parallela (Haldeman)

rivularis (Say) 

Physa anatina Lea 

Order Stylommatophora

Strobilops sparsieostata Baker 

Gastrocopta franzenae Taylor 

holzingeri (Sterki) 

paracristata Franzen and Leonard 

pellucida hordeacella (Pilsbry) 

rexroadensis Franzen and Leonard 

tappaniana (Adams) 

Pupoides albilabris (Adams)

inornatus Vanatta 

Vertigo hibbardi Baker

milium (Gould) 

Vallonia gracilicosta Reinhardt

perspectiva Sterki 

Cion-ella lubrica (Muller) 

cf. Succinea

Helieodiscus singleyanus (Pilsbry) 

Deroceras aenigma Leonard 

RetineHa rhoadsi (Pilsbry)

ivheatleyi (Bland) 

Nesovitrea electrina (Gould) 

Hawaiia minuscula (Binney) 

?Zonitoides arboreus (Say) 

Polygyra rexroadensis Taylor 

Class Amphibia 

Order Caudata

Ambystoma hibbardi Tihen 

Order Salientia

Scaphiopus diversus Taylor 

Nepscaphiopus noblei Taylor 

Bufo sp.

Anchylorana moorei Taylor 

dubita Taylor 

robustocondyla Taylor 

Rana fayeae Taylor 

meadensis Taylor 

ephippium Taylor 

rexroadensis Taylor 

ralida Taylor 

parvissima Taylor
28 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Class Reptilia

Order Chelonia

Testudo rexroadensis Oelrich

lurgida Cope 

Order Squamata

Phrynosoma cornutitm Harlan

Sceloporus robust us Twente

Cnemidophorus bilobatus Taylor

Eumeces striatulatus Taylor

Eumecoides hibbardi Taylor 

mylocoelus Taylor

Heterodon plionasicus Peters 

Class Aves

Order Podicipediformes

Podiceps sp. 

Order Ciconiiformes

Threskiornithidae, indet. 

Order Anseriforrnes

Anas bunkeri (Wetmore)

Bucephala albeola (Linnaeus) 

Order Falconiformes

Buteo sp. 

Order Galliformes

Colinus hibbardi Wetmore

Meleagris gallopavo Linnaeus

Meleagrididae, indet. 

Order Gruiformes

Rallits prenticei Wetmore

Fulica americana Gmelin 

Order Charadriiformes

Scolopacidae, indet.

Sterna sp. 

Order Cohimbiformes

Zenaidiira macroura (Linnaeus) 

Order Psittaciformes

Psittacidae, indet. 

Order Passeriformes

Indeterminate remains 

Class Mammalia

Order Insectivora

Sorex rexroadensis Hibbard 

taylori Hibbard

Par aery ptotis rex Hibbard

Cryptotisf meadensis Hibbard

Blarina adainsi Hibbard

Notiosorex jacksoni Hibbard

Hesperoscalops rexroadi Hibbard 

Order Chiroptera

Lasiurus fossilis Hibbard 

Order Edentata

MegaJonyx cf. M. leptostomits Cope 

Order Rodentia

Paenemarmota barbouri Hibbard and Schultz

Citcllus howelli Hibbard 

rexroadensis Hibbard

Nerterogeomys minor (Gidley)

Geomys qulnni McGrew

PerognatJnts rexroadensis Hibbard 

gidleyi Hibbard 

pearlpftenxis Hibbard

Prodipodomys rexroadensis Hibbard

Liomys centraUs Hibbard

Dipoides rexroadensis Hibbard and Riggs

Class Mammalia Continued 

Order Rodentia Continued

Procastoroides lanei (Hibbard)

Sigmodon intermedius Hibbard

Reithrodontomys rexroadensis Hibbard 

wetmorei Hibbard

Peromyscus baumgartneri Hibbard 

Ttansasensis Hibbard

Parahodomys quadriplicattis Hibbard

Bensonomys eliasi (Hibbard)

Baiomys Jcolbi Hibbard 

rexroadi Hibbard

Onycliomys gidleyi Hibbard

Symmetrodontomys simplicidens Hibbard

Ogmodontomys poaphagus Hibbard

PliopJienacomys primaevus Hibbard

Zapus rinkeri Hibbard 

Order Carnivora

Canis lepopliagus Johnston 

sp. (large)

Borophagus diversidens Cope

Bassarisciis casei Hibbard 

rexroadensis Hibbard

Procyon rexroadensis Hibbard

Buisnictis breviramus (Hibbard)

Trigondctis kansasensl<s Hibbard

Mustela rexroadensis Hibbard 

sp.

Maries foxi Hibbard and Riggs

Taxidea taxus (Schreber)

Spilogalc rexroadi Hibbard

Mephitis? rexroadensis Hibbard

Brachyopsigale dubius Hibbard

Lutra cf. L. piscinaria Leidy

Felts lacustris Gazin 

sp. (large)

Machairodus? sp. 

Order Proboscidea

Stegomastodon, sp.

Mammut adamsi (Hibbard) 

Order Lagomorpha

Pratilepus kansasensis Hibbard

Notolagus lepusculiis (Hibbard)

Hypolagus regalis Hibbard

Nekrolagtis progressus (Hibbard) 

Order Artiodactyla

Platygonus bicalcaratus Cope

Pliaitchenia cochrani Hibbard and Riggs

Gigantocamelus spatulus (Cope)

Tanupolama blancoensis Meade

Odocoileus brachyodontus Oelrich

Antilocapridae, indet. 

Order Perissodactyla

Nannippus phi ego n (Hay)

Plesippus simplicidens (Cope)

Occurrence. Vertebrates of the Rexroad local fauna 

are known from both Meade and Seward Counties, 

Kans., but all mollusks come from Meade County. In 

this area alluvial deposition had been going on continuously since the early late Pliocene. The stream 

shifted back and forth across its flood plain, laying
DESCRIPTION OF LOCAL FAUNAS 29

down sands and fine gravels (derived from the Rocky 

Mountains), sandy silt, and clay (Hibbard, 1950, p. 

119).

Stratigraphy. See Hibbard 1949a, 1950, and McLaughlin, 1946. The Rexroad local fauna occurs in 

the upper part of the Rexroad formation below the 

massive caliche.

Localities. All the following localities are in Meade 

County, Kans.:

Locality 1. (Big Springs Ranch; University of Kansas Meade 

County loc. 25). Center of south edge NW^NE1^ sec. 18, 

T. 32 S., R. 28 W. Exposure in the south bank of a tributary of Spring Creek, where the Rexroad formation is unconformably overlain by the Meade formation. Sanders 

local fauna locality 1 is in this exposure also. This locality 

was listed by Hibbard (1950, p. 174) as near the center of 

the line between sees. 17 and 18, T. 32 S., R. 28 W.

Locality 2. (Big Springs Ranch). Center of NE^NW^ sec. 

24, T. 32 S., R. 29 W. Exposure on the south side of the 

main branch of Spring Creek. Nearly a mile up the Sand 

Draw are Sanders local fauna localities 2 and 3 in the 

overlying Meade formation. This locality is given as the 

NW^NWi/i sec. 19, T. 32 S., R. 28 W. by Franzen and 

Leonard (1947) and by Hibbard (1950, p. 174) ; and as the 

NW% sec. 19, T. 32 S., R. 28 W. by Frye and Leonard 

(1952, p. 151).

Locality 3. (Rexroad Ranch; University of Kansas Meade 

County loc. 3, USGS Cenozoic loc. 21171). W^SW1^ sec. 

22, T. 33 S., R. 29 W. Mollusks come from a pond or bog 

deposit now covered by the sandy bed of a tributary of 

Stump Arroyo. This zone is downstream around the bend 

from the chief vertebrate locality, figured by Hibbard (1950, 

pi. 3). The mollusks occur stratigraphically at or slightly 

above the upper limit of vertebrate occurrence at this locality. Mollusks were reported by Baker (1938), Hibbard 

(1941, p. 95), Franzen and Leonard (1947), Leonard (1950, 

p. 38; 1952a), and Frye and Leonard (1952, p. 151).

Locality 4. (Fox Canyon; University of Michigan loc. UMKl-47). Sec. 35, T. 34 S., R. 30 W. Exposures along Fox 

Canyon (Hibbard, 1950, pi. 5, fig. 1). Locality 4a is a 

pocket of fluviatile sandy silts, 17 feet below the massive 

caliche, from which the vertebrates and a few mollusks were 

collected. Locality 4b is a lenticular bed of blue-gray clay, 

10 feet below the caliche, from which most of the mollusks 

were collected. Franzen and Leonard (1947), Leonard 

(1952a) and Frye and Leonard (1952, p. 151) reported 

mollusks from this locality.

Age. Mammalian evidence for the late Pliocene age 

of the Rexroad local fauna has been summarized by 

Hibbard (1950). Additional evidence for this age is 

as follows.

The Rexroad local fauna indicates a climate more 

humid than the present and lacking such hot summers. 

This fauna occurs below 4 formations representing 4 

cycles of erosion and deposition. These cycles are 

represented also by four cool-climate faunas separated 

by three warmer-climate faunas. A correlation of 

these faunas with the standard glacial-interglacial

TABLE 11. Locality occurrence of mollusks of Rexroad local fauna

[Unverified records from following sources: (1) Hibbard, 1941 (2) Franzen and 

Leonard, 1947 (3) Leonard, 1952a (4) Frye and Leonard, 1952. X, verified occurrence]

Species

Pisidium casertanum (Poli) --......

Fossaria dalli (Baker) _____ __ __

paracristata Franzen and Leonard. ..

Localities

1

X

X 

X 

X

X 

X 

X

X

X 

X

X

X

X

X

2

4 

X

4

X 

X 

4

X

X 

X 

X

2 

X 

X 

X 

X 

X

X 

4 

X 

X 

X

X

X

3

X 

4 

X 

4 

X 

X

X

4 

X

X 

1 

X 

X 

X 

X 

X 

X 

2 

X 

X 

X 

X 

X 

X 

X 

4 

X 

X 

X 

X

1 

1 

X 

?4 

X

4a

X

X

4b

X 

4 

X 

4 

X

4

3 

X 

4 

4 

X 

X

X

2 

X 

X

4 

X

X 

X 

X 

4

X

X

sequence in the Mississippi Valley indicates a preglacial (Pliocene) age for the Rexroad local fauna.

The Saw Rock Canyon local fauna, in the lower part 

of the Rexroad formation, might be assigned to the 

middle Pliocene almost as well as to the upper Pliocene. 

The Rexroad local fauna, in the upper part of the 

Rexroad formation, is of late Pliocene age. A large 

time gap between these two faunas is thus indicated. 

Both faunas indicate a similar temperate climate, lacking present hot, dry summers. There is no evidence of 

climatic change between these two faunas. This period 

of probably uniform climate endured longer than the 

glacial-interglacial ages, as indicated by mammalian 

evolution. Such an interval of mild climate is more 

reasonably Pliocene than Pleistocene.

Paleoecology. Climate: Stagnicola caperata, Promenetus umbilicatellus, and Vattonia, gracilicosta occur 

in the High Plains as far south as Nebraska. They indicate that the Rexroad local fauna lived in a climate 

lacking the hot summers of southwestern Kansas today. 

Gastrocopta pettucida hordeacella and Stagnicola 

bulimoides techella have southern distributions in the 

United States, and range north in the High Plains into 

Kansas. They suggest the Rexroad local fauna lived in 

a climate with winters slightly if at all colder than 

those of the region now.
30 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Table 7 compares the Blancan and Recent molluscan 

faunas of southwestern Kansas. There are two probably significant differences between the Recent and 

Rexroad local faunas: The fossil assemblage has 

several snails requiring permanent water, the Recent 

none. The Recent fauna has only one rare species 

characteristic of damp humus in wooded areas, whereas 

there are several common species of such requirements 

in the Rexroad local fauna. The contrast between the 

two assemblages is further shown by the much greater 

number of species in the Rexroad local fauna. In 

comparing the two assemblages it should be noted that 

the Recent list is slightly increased by permanent water 

species found only in cool artesian springs, and not 

characteristic of the area as a whole.

The association of Cionella lubrica and Gastrocopta 

pellucida hordeacella in the Rexroad local fauna is 

especially significant, for the only known joint occurrence of these two today is in southern New Jersey. 

Presumably here the ocean reduces seasonal extremes 

of temperature, permitting usually remote species to 

live in the same locality.

Hibbard (1950, p. 175-177) summarized the ecological evidence of various groups represented in the 

Rexroad local fauna. He concluded (p. 177) : "There 

is evidence that the climate in the Upper Pliocene was 

more equable than at present, without extremely cold 

winters or severely hot summers, and that there was a 

greater degree of humidity in the region than there is 

now.''

Habitat interpretations (see below) of the Rexroad 

local fauna suggest the presence of timbered areas and 

of grassland. Such vegetation implies greater rainfall 

than southwestern Kansas receives now.

The former climate suggested by all these lines of 

evidence differed from that of the present in having 

summers with less extreme hot spells, and a greater 

annual rainfall of about 30-35 inches. If precipitation 

distribution were better, and gentle rains rather than 

thundershowers were more frequent, one can guess that 

perhaps rainfall was only about 30 inches per year. 

Winters were markedly milder than at present.

Habitat: Table 12 summarizes habitat indications of 

the Rexroad local fauna. Only material represented 

in University of Michigan collections is considered.

Locality 1 was apparently a temporary pond habitat. 

Rarely occurring species characteristic of permanent 

water indicate it was perhaps a small oxbow pond 

close to a permanent stream. The scarcity and small 

variety of land snails suggest that riparian vegetation 

nearby was scanty. Possibly the pond was located on a 

floodplain without nearby woodland, and on which 

only cf. Succinea thrived.

TABLE 12. Habitat indications of mollusks of Rexroad local fauna

[A, abundant (>225); C, common (41-225); S, scarce (8-40); R, rare (1-7). Based 

on material examined only]

Habitat

Permanent water:

Permanent to temporary 

water: 

Permanent or subpermanent.

Permanent or temporaryTemporary water: 

Temporary pond or 

marginal pool.

Temporary pond or 

stream. 

Marginal pools and wet 

mud.

Damp humus of wooded 

area.

Species

Promenetus kansasensis (Baker).

Promenetus umbilicatettus 

(Cockerell). 

Stagnicola bulimoides techella 

Haldeman.

Gastrocopta holzingeri (Sterki)..

Vallonia gracilicosta Reinhardt.

Strobilops sparsicostata Baker. . 

Hawaiia minuscula (Binney) .. 

Helicodiscus singleyanus (Pilsbry). 

Pupoides albilabris (Adams) . . - 

Deroceras aenigma Leonard - .

paracristata Pranzen and 

Leonard. 

pellucida hordeacella (Pilsbry).

1

R

S 

R

r

A 

A 

R

R

R

S

S

s

R

C

Locality

2

R

R

R 

R

S 

S 

S

"c"

c

c

R 

A

S

s 

s 

s 

s

R

3

R

R

C

R

R

R

R

C 

C

S 

A

r

A 

A 

A

C 

A

A

S

R

C 

C 

A 

C

S

4a

 -

S 

A

....

....

4b

R

A

A

A

R

R

R

A

S

C 

R

A 

C

R

R

Locality 2 apparently had only rare surface water. 

Scarcity of temporary-pond species shows that probably habitats were unsuitable for most aquatic snails. 

Significantly greater abundance of dry-tolerant snails 

further suggests little ground moisture and perhaps no 

vegetation but grass. The site of deposition may have 

been the bare floor of a small intermittent stream valley 

bordered by small shrubs and grass, but no trees.

Locality 3 is the richest and shows the greatest 

ecologic diversity of all Rexroad localitites. Aquatic 

species are few in number, and only Physa anatina is 

common. There is a rich land-snail fauna, however, 

which suggests a wooded area providing damp humus 

and dead wood as favorable habitats for many species. 

This somewhat peculiar situation a rich land assemblage but poor freshwater fauna suggests that deposition may have been on land. The local area could 

well have been a well-wooded flood plain, with only 

minor amounts of open water. These could have been 

provided by small, shaded pools, seepages, or beaver 

canals (Hibbard, 1941, p. 97). Probably the Physa 

lived near the area of deposition, but other freshwater 

shells were brought in by the stream when it over-
DESCRIPTION OF LOCAL FAUNAS 31

flowed its banks. Absence of larger land snails such as 

Triodopsis or Mesodon probably indicates that woodland was not widespread, but restricted largely to the 

stream valleys.

Locality 4a has yielded abundant small vertebrates 

but only two species of mollusks. From a study of the 

sediments and contained bones Hibbard (1950, p. 167- 

168) concluded:

The deposit from which the fossils were taken in Fox 

Canyon was laid down by a stream that was carrying fine 

sediments which consisted chiefly of silts and fine sands. The 

remains of fishes in the deposit indicate that the stream was 

probably permanent. The size of the fossils recovered shows 

the effect of stream sorting. The material does not show 

signs of abrasion and appears to have been transported but a 

short distance, either from slope wash along the valley or 

carried by a short tributary that headed in the upland area. 

Because of the dominance of rodents, the concentration of 

small vertebrates is best accounted for as an accumulation of 

remains from the pellets or castings of owls or hawks that 

nested nearby.

The mollusks from locality 4a agree well with this 

picture. The only two species found, Pupoides albilabris and Deroceras aenigma, are both of medium size 

and have shells of relatively high density and strength, 

compared to other mollusks in the Rexroad local fauna. 

Probably other shells were broken and carried away, 

while those of only two species were concentrated at 

the edge of the stream.

Locality 4b represents a slough or stagnant oxbow 

lake. The land snails suggest some vegetation, such 

as shrubs and grass, but again no extensive forest. The 

Physa and Stagnicola indicate a semipermanent aquatic habitat with probably abundant vegetation. The 

rare Marstonia was perhaps washed in from a nearby 

stream during high water.

BENDER LOCAL FAUNA

Previous work. Mollusks from above the massive 

caliche in the type section of the Rexroad formation 

have previously been considered part of the Rexroad 

local fauna. They are segregated here as the Bender 

local fauna (new name). The fauna is named after 

Mr. H. C. Bender, Plains, Kans., who now owns the 

Rexroad ranch, on which the type locality is located. 

Only mollusks are known in the fauna.

Some species not in University of Michigan collections, but reported in University of Kansas material 

from SW*4 sec. 22, T. 33 S., R. 29 W., Meade County, 

may be from either Rexroad locality 3 or from Bender 

localities la, Ib, or Ic. See under Rexroad local fauna 

for discussion.

Fauna. Following is a list of the Bender local 

fauna:

Class Gastropoda

Order Basommatophora

Stagnicola 'bulimoides techella (Haldeman)

caperata (Say)

sp.

Fossaria dalli (Baker) 

Promenetus umMlicatellus (Cockerell) 

Physa anatina Lea 

Order Stylommatophora

Gastrocopta cf. G. cristata (Pilsbry and Vanatta)

 franzenae Taylor

paracristata Franzen and Leonard

scaevoscala Taylor

tappaniana (Adams) 

Pupoides albilabris (Adams) 

Vertigo milium (Gould) 

Vallonia parvnla Sterki 

cf. Succinea

Hclicodiscus singleyanus (Pilsbry) 

Deroceras aenigma Leonard 

Hawaiia minuscula (Binney) 

fZonitoides arboreus (Say) 

Polygyra rexroadensis Taylor

Occurrence. The Bender local fauna is known only 

from Meade and Seward Counties, southwestern 

Kansas.

/Stratigraphy. This assemblage occurs in the uppermost Rexroad formation above the massive caliche. 

Locality 2 is at the same stratigraphic position as the 

mollusks recorded by Hibbard (1949a, p. 94) in a section measured close by that locality.

Localities. Following are from the Bender local 

fauna:

Locality 1. Three sites at the same stratigraphic level, in exposures within about an eighth of a mile along the banks 

of a tributary of Stump Arroyo, SE^SW1^ and SW^SE1^ 

sec. 22, T. 33 S., R. 29 W., Meade County, Kans. Uppermost part of the Rexroad formation, above massive caliche 

bed. About 300 yards downstream from Rexroad locality 3. 

Locality la. NE^SE^SW1^ sec. 22. Dark bed (soil?). 

South side of stream, upstream from locality Ib. Locality 

Ib. NWHSW^SE^i sec. 22. East side of stream, about 

halfway between localities la and Ic. Just below Meade 

gravels. Locality Ic. SW^SW^SE1^ sec. 22. Southwest 

side of stream, downstream from locality Ib; near section 

road along south side of section 22.

Locality 2. Seward County, Kans. Wolf Canyon, in approximately the center of W% sec. 12, T. 35 S., R. 31 W. Uppermost part of the Rexroad formation, above massive caliche 

bed.

Age. Since associated vertebrates are lacking, age 

assignments must be based on the molluscan fauna and 

on climatic inferences from the sediments and fauna. 

The molluscan fauna has similarities to both the 

Rexroad and Sanders local faunas, but is slightly closer 

to the Rexroad. In addition, G. cf. cristata is intermediate between the Rexroad Gr. franzenae and the 

Sanders, Dixon, and Sand Draw Gr. cristata. Negative 

evidence, interesting but of slight or no significance, is
32 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

the absence in the Bender local fauna of Vertigo hibbardi of the Rexroad local fauna, and the absence of 

Vertigo ovata, Gastrocopta chauliodonta, Physa skinnerij and Aplexa hypnorum of the Sanders local fauna. 

Comparison of the Bender local fauna with early Pleistocene faunas besides the Sanders would be of little 

value. The Sanders and Bender local faunas probably 

lived under similar conditions, while the Sand Draw 

and Dixon mollusks suggest markedly different climates.

Hibbard (1954a, p. 235-236) discussed the significance of the massive caliche bed in the uppermost part 

of the Rexroad formation. In summary, it may be 

stated that the caliche suggests a semiarid climate, 

whereas the faunas above and below indicate moister 

climates. There is no evidence that the Bender local 

fauna lived in a climate cooler than that of the Rexroad local fauna. The uppermost part of the Rexroad 

formation, above the massive caliche and including 

the Bender local fauna, might be considered Pleistocene if the climatic change from semiarid to moister 

were considered contemporaneous with the beginning 

of continental glaciation, and if the Pleistocene epoch 

were defined as beginning with the first activity of 

major continental glaciers (see Frye and Leonard, 

1953).

The differences between the Bender and first Pleistocene faunas (Sand Draw, Dixon) are much greater 

than those between the Rexroad and Bender, however. 

The weight of evidence favors a Pliocene age for the 

Bender local fauna.

Paleoecology. Climate: Stagnicola caperata and 

Promenetus umbilicatellus occur in the High Plains as 

far south as Nebraska. They indicate that the Bender 

local fauna lived in a climate lacking the present summer extremes of heat. Stagnicola bulimoides techetta 

has a southern distribution, and ranges north in the 

High Plains only as far as Kansas. Its occurrence suggests winters only slightly if at all colder than those of 

southwestern Kansas today.

Table 7 compares the Blancan and Recent molluscan 

faunas of southwestern Kansas. Only 9 of the 19 species of the Bender local fauna still live in the area. 

Vertigo milium lives not too far to the east however, 

and several extinct species have ecological equivalents 

in southwestern Kansas.

The few aquatic species suggest only subpermanent 

to temporary bodies of water. Several of the land 

snails can withstand dry upland conditions in the High 

Plains today (Gastrocopta cristata, Pupoides albilabris, Hawaiia minuscufa), and none of the others requires much shelter or permanent moisture. There is 

no indication of vegetation heavier than grass and a 

little scrub, or (in conjunction with summers slightly 

cooler than present) of rainfall greater than about 20 

inches per year.

Habitat: Table 13 summarizes the habitat indications 

of the Bender local fauna. Locality 1 probably represents deposition on land, for terrestrial species are 

abundant and aquatic forms rare. The land snails are 

all species which do not require woodland, though the 

Polygyra may have inhabited patches of scrub. The 

few fresh water species are all able to endure drying of 

their water body. The general environment suggested 

is a slow-moving temporary stream with bordering 

vegetation of grass and clumps of bushes or scattered 

trees.

Locality 2 suggests similar conditions, except that 

conditions were more favorable for freshwater snails 

and less favorable for land snails.

TABLE 13. Habitat indications of Bender local fauna 

[A, abundant (>250); C, common (41-250); S, scarce (8-40); R, rare (1-7)1

Habitat

Permanent to subpermanent water. 

Permanent or temporary 

water. 

Temporary pond or 

marginal pool.

Temporary pond or 

stream. 

Marginal pools and wet 

mud.

Damp humus or grass- __ 

Damp to dry ground, ...

Species

Stagnicola, sp... ........ . _ .

Promenetus umbilicatellus 

(Cockerell). 

Stagnicola bulimoides techeJla 

(Haldeman) .

Vertigo milium (Gould) ...

Gastrocopta tappaniana 

(Adams) .

Gastrocopta cristata (Pilsbry 

and Vanatta). 

Hawaiia minuscula (Binney)__ 

Helicodiscus singleyanus (Pilsbry). 

Pupoides albilabris ( Adams) ___ 

Deroceras aenigma Leonard ___

paracristata Franzen and 

Leonard.

Locality

la

R

R

S

S 

S

0 

R

S

A

A

S

0 

0

A

S

S

Ib

R

S

R

S

C 

A

C

'"s"

A

S

1C

R

S 

S 

R 

C

R

A

A 

C

C 

C

C

S

S

2

C 

S 

C 

C 

C 

R

C 

R

S

-.-...

C

C

SAND DRAW LOCAL FAUNA

Previous work. Fossils representing the Sand Draw 

local fauna were first collected by M. F. Skinner for 

the Frick Laboratories in 1934. From these and later 

collections by Skinner only two species have been published (Frick, 1937, p. 529; Osborn, 1936, p. 726). 

Later collections by Bryan Patterson and J. H. Quinn 

of the Chicago Natural History Museum yielded many 

additional vertebrates and mollusks (Baker, 1938; McGrew, 1944). In 1950 C. W. Hibbard and a party from
DESCRIPTION OF LOCAL FAUNAS 33

the University of Michigan Museum of Paleontology 

visited the area and collected at other localities not 

sampled by Patterson and Quinn. Additional species 

found include mollusks (Taylor, 1954a) and a few 

mammals (Hibbard, 1956, 1957). Taylor visited the 

region in 1953, studied the stratigraphy of the localities 

where mollusks had been found, and collected more 

material. This stratigraphic study and an examination 

of the shells collected by these persons form the basis 

of the present discussion.

Fauna. Following is a list of the Sand Draw local 

fauna:

Class Pelecypoda

Order Prionodesmacea

fAnodonta grandis Say 

Order Teleodesmacea

Sphaerittm partiimeiutn (Say)

striatinum (Lamarck)

sulcatum (Lamarck)

transversum (Say) 

Pisidium casertanum (Poll)

compress utn Prime

nitidum Jenyns 

Class Gastropoda

Order Mesogastropoda

Valvata lew is i Currier

tricarinata (Say) 

Order Basornmatophora 

Carychium sp. 

Stagnicola cf. 8. reflexa (Say)

caperata (Say) 

Fossaria dalli (Baker)

ofirussa (Say) 

Bitlimnea megasoma (Say) 

Anisus pattersoni (Baker) 

G-yraulus parvus (Say) 

Helisoma anceps (Menke) 

Planorbula armigera (Say) 

Promenetus kansasensis (Baker)

utn'biUcatel'lus (Cockerell) 

Acrolojeus coloradensis (Henderson) 

Ferrissia meekiana (Stimpson)

rivularis (Say) 

Physa anatina Lea

gyrina Say

skinner i Taylor 

Aplexa Jtypnorum (Linnaeus) 

Order Stylommatophora

Strobilops sparsicostata Baker 

Gastrocopta chauliodonta Taylor

cristata (Pilsbry and Vanatta)

tappaniana (Adams) 

Vertigo milium (Gould)

ovata Say 

Pupoides aJbilabris (Adams)

i no mat us Vanatta 

Va-llonia pulchella (Mttller) 

cf. Succinea

Class Gastropoda Continued

Order Stylommatophora Continued 

Helicodiscus singleyanus (Pilsbry) 

Deroceras aenigma Leonard 

Hawaiia minuscula (Binney) 

Class Osteichthyes

let alums sp. 

Class Reptilia

Order Chelonia 

Pseudemys sp. 

Testudo, 2 species 

Class Mammalia 

Order Rodentia

Geomys quinni McGrew

Procastoroides siceeti Barbour and Schultz 

Nebraskomys mcgrewi Hibbard 

Pliopotamys meadensis Hibbard 

Order Carnivora

Canis cf. C. latrans Say 

Trigonictis kansasensis Hibbard 

Taxidea cf. T. taoeus (Schreber) 

Stnilodon sp. 

Order Proboscidea

Stegotnastodon primitivus Osborn 

Order Artiodactyla 

Platygomts sp. 

Gigantocamelus sp. 

Camelops sp. 

Capromeryoe sp. 

Order Perissodactyla

Plesippus simpUcidens (Cope)

Occurrence. All known outcrops of the beds containing the Sand Draw local fauna are in northern 

Brown County, Nebr., within a northwest trending 

area about 10 by 4 miles. It appears that the beds are 

the fill in a late Pliocene valley, possibly related to an 

ancestor of the Elkhorn River.

Stratigraphy. The deposits yielding the Sand Draw 

local fauna are unnamed. They rest unconformably, 

upon the underlying Pliocene rocks, and are overlain 

unconformably by a widespread sand and gravel sheet 

which forms much of the High Plains surface in the 

area. The approximate maximum thickness of the 

beds is 125 feet.

Lithology varies from fine-bedded alternating black 

clays and buff sands to crossbedded coarse sand and 

gravel. The fine-bedded sediments are extensively exposed along Deep Creek, and probably represent quietwater deposition. The top of a thick sand and gravel 

unit is indicated at the base of the section on page 34. 

Crossbeddiiig and lenticular clay and gravel beds represent fluviatile deposition.

There are three principal mollusk-bearing horizons: 

A, 75 feet below the unconformity (loc. 1); B, 35 feet40 feet (loc. 2-3); and C, 15-22 (loc. 4-7). The 

following section contains only the highest horizon.

508945 O 60-
34 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Section at center north side SW}i sec. 25, T. 81 N., R. %2 W., 

Brown County, Nebr. Section and photograph by McGrew (1944,

p. 84-85) are from this same exposure.

Feet

9. TopsoU.____---____-___.------------------------ 4.0

8. Fine sand and gravel, dark tan____________________ 1. 75

7. Sand, medium-grained, crossbedded, light rust-colored 

with many thin manganese-stained layers, occasional 

fine silt lenses,_________________________________ 5. 25

6. Coarse sand and fine gravel, dark rust color. ________ 2. 0

5. Sand, fine white, with coarse rusty layer 1-4 inches

thick at base______^_________________________ 6. 25

Erosional unconformity

Formation containing Sand Draw local fauna

4. Sand, fine, light tan, grading upward into silt-__-_-__ 7. 5 

3. Silt, tan (weathering light gray) with rodent burrows

filled by sand from unit 4; some shells (loc. 6) _____ 2. 0 

2. Sand, fine, slightly marly, gray-buff with abundant

shells (loc. 6) _________________________________ 9. 0

1. Channel sands, fine, gray-tan, with lenses of clay and

gravel ______________________________________ 9. 0

Bed of wash (base of formation not exposed)

Localities. All the following localities are in Brown 

County, Nebr.:

Locality 1. Center west side SE^SWVi sec. 24, T. 31 N., R. 

22 W; exposure on north side of Sand Draw at mouth of 

second wash downstream from bridge on former State Highway 7; locally reddish marly spot, 75 feet below unconformity.

Locality 2. NW& sec. 14, T. 31 N., R. 23 W. (USGS Cenozoic 

loc. 19090), exposures at head of West Fork of Deep Creek; 

sandy layer in thin-bedded sand and clay layers about 38 

feet below unconformity.

Locality 3. NE^SWii sec. 12, T. 31 N., R. 23 W; exposure on 

east side of Middle Fork of Deep Creek; thin-bedded sand 

and dark-gray clay, 35 feet-40 feet below unconformity.

Locality 4. NW& sec. 33, T. 31 N.. R. 22 W; exposure on north 

side of Sand Draw; marly silt, 21-22 feet below unconformity.

Locality 5. Center of north side sec. 34 and southeast corner 

SW% sec. 27, T. 31 N., R. 22 W; exposures on small draw 

near earth dam; marly silt, 18-20 feet below unconformity; 

mollusks from this locality were listed by McGrew (1944, p. 

36) as "from an exposure 2 miles west of Sand Draw." 

Baker (1938, p. 130) reported the snails by error as from 

the exposure on Sand Draw. (See below.)

Locality 6. North side of SW& and south side of NWVi, sec. 

25, T. 31 N., R. 22 W. (USGS Cenozoic loc. 19091). Exposures along first wash south of Sand Draw on former 

State Highway 7. Marly sand and tan silt (units 2 and 3 

of section), 8-15 feet below unconformity. This wash is 

not the Sand Draw proper, as considered by McGrew (1944, 

p. 35, explanation of figure), but a small tributary to it. 

The photograph and section given by McGrew (1944, p. 

34-35) were taken in the center of the north side of the 

SW& of sec. 25. Mollusks from this locality were listed by 

McGrew (1944, p. 36) as from the "Sand Draw exposure," 

and by Baker (1938, p. 131) by error (see below) as from 

2 miles west of the Sand Draw exposure.

Locality 7. Near center of SW%SE% sec. 4, T. 30 N., R. 21 

W. Exposure on Bone Creek near Stegomastodon quarry. 

Baker (1938, p. 130-131) listed mollusks from two localities, 

one "6 miles north of Ainsworth" and the other "about 2 

miles west" of the former. Bryan Patterson, who collected 

the material, in a letter (dated December 22, 1949) to C. 

W. Hibbard, stated that Baker transposed the two localities. 

A letter from Baker to Patterson clearly shows that this 

transposition took place. McGrew (1944, p. 36) corrected 

the error, but without so indicating.

Age. Faunal correlation and climatic inferences indicate the Sand Draw local fauna is of Nebraskan or 

Aftonian age. Pliopotamys meadensis is otherwise 

known only from the late Nebraskan or early Aftonian 

Dixon local fauna and the Aftonian Deer Park local 

fauna. This rodent is especially significant for correlation of the Sand Draw local fauna. The snail 

GastroGopta chauliodonta is known only from the Sand 

Draw, Dixon, and Sanders local faunas and thus tends 

to support the mammalian evidence.

Although the mollusks of the Dixon, Sanders, and 

Sand Draw local faunas are generally similar (table 

4), the Dixon and Sand Draw local faunas are related 

by sharing Bulimnea megasoma and Acroloxus coloradensis. These two species are rare or unknown in other 

Pleistocene assemblages, and suggest a similar environment for both faunas.

Climatic interpretation of the fauna is somewhat 

restricted because land snails are relatively underrepresented, and because the known vertebrates are mostly 

large mammals of little ecologic value. The large 

turtle Testudo indicates much warmer winters than 

those of north-central Nebraska today, with minimum 

temperatures rarely if ever at freezing. With the limited stratigraphic and paleontologic evidence available 

no precise climatic or age interpretations are possible. 

The mollusks alone, but especially the large Testudo, 

indicate that the assemblage did not live during a time 

of major glacial advance. It is not a late glacial age 

assemblage if the contrast with the late Kansan 

Cudahy fauna and the late Illinoian Butler Spring and 

Berends local faunas is reliable. The Sand Draw local 

fauna may be a transitional Nebraskan and Aftonian 

assemblage, as the Dixon local fauna is thought to be, 

or it may date from an interstadial in the Nebraskan 

age analogous to the Donau/Giiiiz interstadial of the 

Alps.

Paleoecology. Climate: Comparison of the mollusks 

of the Sand Draw local fauna with those living today 

in north-central Nebraska (table 15) shows 2 main 

contrasts which are most simply explained in 2 different ways. Valvata lewisi, V. tricarinata, Physa 

skinneri, and Vattonia pulchella have a generally
DESCRIPTION OF LOCAL FAUNAS 35

TABLE 14. Habitat indications of mollusks of Sand Draw 

local fauna

[A, abundant (>200); C, common (41-200); S, scarce (16-40); R, rare (1-15)]

Habitat

Permanent water: 

Pond.____ _ ._ ...

Permanent to temporary water: 

Permanent or subpermanent.

Permanent or temporary.

Temporary pond or 

marginal pool.

Marginal pools and 

wet mud.

Damp humus or grass .

Species

A croloxus coloradensis 

(Henderson) . 

Bulimnea megasoma

(Say).

Helisoma anceps 

(Menke). 

Pisidium compressum 

Prime.

Sphaerium partumeium 

(Say). 

striatinum (Lamarck) .

Valvata tricarinata (Say)

Ferrissia rivularis (Say)._

Planorbula armigera 

(Say).

Promenetus kansasensis 

(Baker). 

Gyraulus parvus (Say) ...

Stagnicola cf. S. reflexa 

(Say). 

Aplexa hypnorum (Linnaeus) . 

Pisidium casertanum 

(Poll). 

Promenetus umbilicatellus (Cockerell).

Vertigo milium (GouldK

Gaftrocopta tappaniana 

(Adams) . 

Vallonia pulchella 

(Miiller). 

Gastrocopta cristata 

(Pilsbry and Vanatta). 

Hawaiia minuscula 

(Binney). 

Helicodiscus smgleyanus 

(Pilsbry). 

Pupoides albilabris 

(Adams) . 

Anisus pattersoni 

(Baker). 

Deroceras a enigma 

Leonard. 

Ferrissia meekiana 

(Stimpson) . Gastrocopta chauliodonta 

Taylor.

Pupoides inornatus Vanatta. 

Strobilops sparsicostata 

Baker.

Locality and abundance

Level 

A

1

S

C 

A

C

R 

R

C 

C

C

A 

R 

C

R

R

R 

R

R

Le\el 

B

2

R

R

S

C 

R

R

R 

C

C 

R

S

S

s

R

R 

R

R 

R

R

R

S

R 

R

R 

R

3

S

C

A 

A

O

R

A

A

C 

A

A

A 

R 

R 

A

S

O

R

R

S 

R

R

R

C 

R 

R

R 

C

R

S

Level 

C

4

R

R

R 

C

A

C

R 

S 

C 

R

R

S

R 

C

R

R

5

C

S 

A

A

A 

A 

S 

A 

A

S 

C 

R

R

R

C

C

6

R

A 

R

R

R 

A

A

A 

R 

R 

A

A 

R

S 

S 

S

R

R 

R

S

A 

R

R 

C

S

7

R

C 

C

C

R 

A

S

R

R

C 

R

R

S

S

northern distribution in North America. Physa skinneri does not range south in the Great Plains as far as 

the United States; the others are found a little farther 

south, but are ordinarily found only north of the Sand 

Draw fossil localities. These species suggest that the 

fauna lived under cooler summer conditions than those 

of northern Nebraska today.

The other contrast between the fossil and Eecent 

faunas is in the habitats represented. Table 15 showTs

that there are 13 species which live in perennial water 

bodies in the Sand Draw local fauna, but only 3 in the 

local living fauna. This is considered a real and 

significant difference. The three Recent species in this 

habitat type are all known from a single locality where 

a group of springs forms a summer-cool, permanent 

pond. North-central Nebraska now is probably considerably drier and warmer in the summers than formerly. A number of land snails, particularly those of 

damp humus and sheltered habitats, are present in the 

Recent fauna but not in the Sand Draw local fauna. 

This may be explained by sampling error.

Only two mollusks (Gastrocopta cristata, Helicodiscus singleyanus] in the fossil assemblage have a relatively southern distribution in North America. The 

former reaches its northern known limit of range in 

northern Nebraska; the latter, in South Dakota. They 

suggest that winters were formerly no colder than those 

of the area today. The most significant temperature 

indicator in the fauna is the large land turtle, Testudo. 

The occurrence of this species in northern Nebraska indicates that winters were formerly much milder than 

now, with the lowest temperatures rarely if ever at 

freezing.

The mild winter climate inferred from the Sand 

Draw local fauna contrasts with the climates inferred 

from other late glacial faunas from the High Plains, 

such as the Cudahy fauna and the Berends, Butler 

Spring, and Jones local faunas. The occurrence of 

several markedly northern species suggests a climate 

more likely to be glacial than interglacial, but several 

land snails usually found in glacial faunas, such as 

Pupilla muscorum (Linnaeus), P. blandi Morse, Vertigo modesta Say, and V. gouldi (Binney), are absent. 

Until pollen analyses or better samples of the terrestrial fauna are available, the former climate and 

precise age of the Sand Draw local fauna will remain 

uncertain.

Habitat: Table 14 shows the habitat indications of 

the Sand Draw mollusks. Distribution and relative 

abundance of the species suggest that horizon C represents deposition in shallower water with a smaller 

variety of aquatic habitats than the other levels. Such 

an interpretation is supported by the fine-grained noncrossbedded sediments, and by the presence of rodent 

burrows at locality 6 (see section). Presence of Ferrissia rivularis, Valvata tricarinata, and Helisoma anceps at horizons A and B suggests a nearby stream. 

The fine-bedded, alternating black carbonaceous clays 

and light-colored sands along Deep Creek in which 

these species occur probably indicate lacustrine deposition, however.
36 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

TABLE 15. Comparison of Sand Draw local fauna and Recent 

mollusks from northern Nebraska

Habitat

Permanent water:

Pond _ __________________

Permanent to temporary 

water: 

Permanent or subpermanent.

Permanent or temporary- _

Temporary pond or marginal pool.

Marginal pools and wet 

mud. 

Moister humus _ _ __

Semiaquatie, riparian habitat.

Damp humus or grass.

Damp humus of wooded 

area.

Species

Acroloxus coloradensis (Henderson).

Promenetus umbilicatellus (Coekerell).

cristata (Pilsbry and Vanatta). 

Haicaiia minuscula (Binney) ______ 

Helicodiscus singleyanus (Pilsbry).

Occurrence

Sand Draw 

horizon

A

X 

X

X 

X

X 

X

X

X

X

X

X

X

X

X 

X

X

B

xxxx

X

X

X

X

X

X

X

X

X 

X

X 

X

X 

X 

X

X

X 

X

X

X

xxxxxxxxx

X

X

c

X 

X 

X

X

v

X 

X

X

X

X 

X

X 

X

X 

X

X 

X

X

X

X 

X

"x"

X 

X

X 

X

X

Recent

X

X

X

xxx ixxxxx

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

Horizon A contains a relatively low proportion of 

land species and a high proportion of aquatic species, 

especially those characteristic of permanent water. 

The local habitat may have been a permanent pond 

fed by or draining into a stream. Rarity of temporary pond and land snails may indicate that the locality is well out from the former shore.

Horizon B is the richest of the three. The sediments 

and mollusks of varied habitats suggest a large, quiet 

lake bordered by shallow marginal pools with grass 

and bushes along the shore. Absence of genera such as 

Discus, Retinella. and Zonitoides may indicate there 

were no woods along the shore. Shells from the shore 

and shallow^ water were apparently washed out to the 

deeper areas of the lake. A connecting river probably 

contributed some shells, especially Ferrissia.

Horizon C species indicate some permanent water, 

but apparently many shallow temporary pools were 

present. The increased percentage of temporary water 

and land species suggests a series of small pools and 

shoreline lagoons around a basin which did not dry 

up, but in which water level fell annually. Grass and 

a few trees and bushes lined the shore, but as in 

horizon B. evidence of extensive woodlands is absent.

DIXON LOCAL FAUNA

Previous work, Frye and Leonard (1952, p. 151, 

Kingman County locality) reported mollusks from 

what is here called Dixon locality 1. Acting on thendiscovery, C. W. Hibbard and University of Michigan 

field parties have made additional large collections 

which yielded amphibians, birds, and mammals, besides many more mollusks (Herrington and Taylor, 

1958; Hibbard, 1956; Taylor, this paper; Tihen, 1955). 

Mollusks and a few vertebrates (Hibbard, 1958a) from 

a second locality in Kingman County are included in 

the Dixon local fauna in this paper. University of 

Michigan collections are the basis of the present study.

Fauna. Following is a list of the Dixon fauna:

Class Pelecypoda

Order Teleodesmacea

Sphaerium laoustre (Miiller) 

partumelum (Say) 

transversum (Say) 

Pisidium casertanum (Poll) 

compression Prime 

nitidum Jenyns 

Class Gastropoda

Order Mesogastropoda

Valvata tricarinata (Say) 

Viviparidae, indet. 

Marstonia crybetes (Leonard) 

Hydrobiidae, indet. 

Order Basommatophora

Carychium exiguum (Say) 

Stagnicola caperata (Say)

reflexa (Say) 

Fassaria dalli (Baker) 

Biilimnea tnegasoma (Say) 

Anisus pattersoni (Baker) 

Gyro-u-lus parvus (Say) 

Helisoma anceps (Menke) 

trivolvis (Say)
DESCRIPTION OF LOCAL FAUNAS 37

Class Gastropoda Continued

Order Basommatophora Continued 

Planorbula armigera (Say) 

Promenetus kansasensis (Baker)

nmMlicatellus (Cockerell) 

Acroloxus coloradensis (Henderson) 

Ferrissia meekiana (Stimpson)

rivularis (Say) 

Physa anatina Lea

gyrina Say

skinner I Taylor 

Order Stylommatophora

Strobilops sparsicostata Baker 

Gastrocopta armifera (Say)

chauliodonta Taylor

cristata (Pilsbry and Vanatta)

pellucida hordeacella (Pilsbry)

procera (Gould)

scaevoscala Taylor

tappaniana ( Adams) 

Pupoides albilabris (Adams) 

Vertigo milium (Gould)

ovata Say

Vallonia perspectiva Sterki 

Oxyloma retusa (Lea) 

cf. Sitccinea 

Helicodiscus parallelus (Say)

singleyanus (Pilsbry) 

Deroceras aenigma Leonard 

Nesovitrea electrina (Gould) 

Hawalia minuscula (Binney) 

Zonitoides arboreus (Say) 

Class Amphibia 

Order Caudata

Ambystoma tigrinum (Green) 

Class Aves

Undescribed bird remains 

Class Mammalia

Order Insectivora

Sorex dixonensis Hibbard

leahyi Hibbard

sp.

Blarina sp.

Cryptotis kansasensis Hibbard 

Order Rodentia 

Citellus sp. 

Geomys sp. 

Castoridae, indet. 

Sigmodon sp. 

Peromyscus sp.

Pliophenacomys meadensis Hibbard 

Pliopotamys meadensis Hibbard 

Pliolemmus antiquus Hibbard 

Synaptomys r Inker i Hibbard 

Order Carnivora

Mustelidae, indet.

Occurrence. The Dixon local fauna is known only 

from Kingman County, south-central Kansas.

Stratigraphy. Neither the top nor the base of the 

fine silt unit containing the Dixon local fauna is exposed at the localities examined. On the basis of the 

age indicated by the fauna, the deposit is equivalent to

or may be part of the Missler member of the Ballard 

formation.

Localities. Both in Kingman County, Kans.: 

Locality 1: Sl/2 sec. 12, T. 29 S., K. 8 W. Most of the 

material collected by Hibbard and party came from the 

southeast corner of the SW^ (see Frye and Leonard, 

1952, p. 62, pi. 3, fig. B). The exposure continues into 

the southwest corner of the SEV4- Additional material 

was collected from the center of the SW^4, on a slope 

above the northeast side of Red Creek. Locality 2: 

SEV4NE14 sec. 23, T. 30 S., R. 5 W.

These two localities are believed to represent one 

fauna on the basis of the mollusks alone. All other 

faunas known from more than one locality which are 

reported in this paper are defined by independent stratigraphic or mammalian evidence.

Table 17 shows the close similarity of the molluscan 

assemblages from localities 1 and 2. Species considered 

especially significant are Acroloxus coloradensis, Bulimnea megasoma, and the viviparid. In the Pleistocene 

of the Great Plains the first two are known only from 

the Sand Draw and Dixon local faunas, the last from 

the Dixon local fauna only. It should be emphasized 

that the collection from each locality gives independently a similar and unusual ecological picture. Barring extinct species, the fossil land snail fauna is closely 

similar to that living in southern Kansas; the fossil 

and Recent freshwater assemblages are markedly distinct, however.

Mammals from locality 2 are few in number. If this 

locality is correlative with locality 1, as the mollusks 

suggest strongly, then the association of Sigmodon 

with so many shrews is remarkable. Furthermore, the 

occurrence of another species of shrew at locality 2, in 

addition to the four known from locality 1, suggests 

peculiarities of sampling error or only an approximate 

correlation between the two localities.

Age. Faunal correlation and ecologic inferences indicate a latest Nebraskan or earliest Aftonian age 

(Hibbard, 1956). Pliophenacomys meadensis Hibbard, 

Pliopotamys meadensis Hibbard, Pliolemmus antiquus 

Hibbard, and Gastrocopta chauliodonta Taylor are all 

species known only from the Deer Park, Dixon, Sand 

Draw, and Sanders local faunas, of Nebraskan and 

Aftonian age. Ecologic interpretation of the mollusks 

and mammals tends to favor a late Nebraskan age, but 

the salamanders suggest Aftonian age. The fauna is 

therefore considered latest Nebraskan or earliest 

Aftonian.

Paleoecological indications (see below) are that the 

fauna lived in a climate with summers similar to or 

slightly cooler than those of today, and with runoff 

considerably greater from winter precipitation. The
38 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

climate was not as markedly glacial as that of the 

Cudahy, Berends, and Bar M local faunas, nor as mild 

as that of the Sanders or Jinglebob local faunas. Summers were probably not quite so cool as those under 

which the Sand Draw local fauna lived, but this difference can be explained by latitude. The Dixon local 

fauna seems to represent the latest Nebraskan glacial 

age, when the climate had already begun to aproach 

that of today.

Frye and Leonard (1952, p. 148-151) distinguished 

the Dixon local fauna from the Kansan Cudahy fauna. 

They confused the late Pliocene Saw Rock Canyon and 

Rexroad local faunas with it, however, and gave all 

three a Nebraskan age. This procedure was based upon 

12 supposed index fossils, 5 of which were found associated with Nebraskan till. Occurrence of these 

species is shown in Table 16.

TABLE 16. Occurrence of supposed Nebraskan index fossils 

[After Frye and Leonard, 1952, p. 151]

Species

11. Vertigo hibbardi- .....................

Fauna and locality

Saw K ock 

Canyon 

local 

fauna

X 

X 

X 

X 

X

X 

X 

X 

X 

X

Rexroad 

local 

fauna

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X

Dixon 

local 

fauna

X 

X 

X 

X 

X 

X

X

X 

X

Nebraskan till 

and 

David 

City 

gravel

X

X

X

X

X

Numbers 1-6 are considered synonyms of living 

species. Number 7 is believed to be not the living Polygyra mooreana but an extinct species known only from 

the Rexroad and Bender local faunas. Numbers 8 and

9 range from the late Pliocene Saw Rock Canyon local 

fauna to the Aftonian Sanders local fauna. Numbers

10 and 11 are believed restricted to the upper Pliocene; 

the record of 11 in the Dixon local fauna is considered 

erroneous. Number 12 occurs in the upper Pliocene 

and Nebraskan. The extensions in range of these 

species are due to two chief reasons: difference in taxonomic evaluation (whether the fossils are different 

from other species or not), and use of vertebrate fossils 

for age determination.

Paleoecology. Climate: Mollusks of the Dixon local 

fauna are compared with those living in Kingman 

County today in table 18. The most significant and 

obvious difference is the much greater number of freshwater species, especially those requiring permanent

water, in the Dixon local fauna. The terrestrial components of the two assemblages, however, are not 

significantly different. In this case sampling error is 

probably not important, for the Dixon local fauna is 

known from two fairly well sampled localities representing several habitats. The absence of such characteristically northern land snails as Pupilla, Vallonia 

gracilicosta, Discus, and some species of Vertigo is 

probably real.

The occurrence in the Dixon local fauna of some 

freshwater snails of generally northern distribution in 

North America may be explained by their habitat in 

summer-cool, perennial water bodies. Other freshwater species which do not range as far west as Kingman County also indicate a greater variety of aquatic 

habitats in the early Pleistocene. The evidence of the 

land snails suggests that the markedly northern snails 

Valvata tricarinata and Physa skinneri indicate the 

persistence of cool water habitats during the summer, 

rather than markedly cooler summer climate. The 

close similarity of the land snails to those living locally 

tends to suggest a climate not unlike that of Kingman 

County today.

The sources of water for the perennial streams which 

contained the relatively diverse fresh-water molluscan 

assemblage of the Dixon local fauna are speculative. 

Presumably the mean annual precipitation did not 

differ greatly in amount from that today, for then a 

larger, more diverse land snail fauna would be expected. Perhaps greater annual snowfall in the 

Rocky Mountains or the melting of glaciers were contributing factors.

The Dixon local fauna evidently represents a later 

stage of deglaciatioii than do the Cudahy, Berends, 

Butler Spring, or Bar M local faunas, for these assemblages suggest much cooler, moister summers. It is 

most similar to the Sand Draw local fauna, and differences between the two can be explained by latitude 

and sampling error.

Habitat: Table 17 summarizes the habitat indications 

of the mollusks of the Dixon local fauna. At locality 

1 the area of deposition was probably close to two 

freshwater habitats: a permanent slow-moving stream 

or slack-water stretch, probably of at least moderate 

size, and shallower, quiet water near shore, with dense 

vegetation. The more abundant land snails taken as a 

group suggest a streamside situation of damp grass and 

humus with some dead wood, but no wooded area. The 

species characteristic of woodland are so much rarer 

that this habitat was either not important at the time, 

or else some distance upstream. This inference is erroneous to an uncertain degree, however, because of 

the larger size of the species in question, whose shells
DESCRIPTION OF LOCAL FAUNAS 39

TABLE 17. Habitat indications of mollusks of Dixon local fauna 

[A, abundant (>250); C, common (41-250); S, scarce (8-40); R, rare (1-7)]

Habitat

Permanent water:

Permanent to temporary 

water: 

Permanent or subpermanent.

Permanent or temporaryTemporary pond or marginal 

pool.

Marginal pools and wet mud. 

Semiaquatic, riparian habitatDamp humus of wooded area. 

Damp to dry ground- ____--__

Species

Acroloxus coloradensis (Henderson).

Pisidium compressum Prime.--...

Promenetus kansasensis (Baker) . . .

Promenetus umbilicatellus (Cockerell).

Oastrocopta tappaniana (Adams) -.

cristata (Pilsbry and Vanatta) .

Hawaiia minuscula (Binney) ._. _ 

Helicodiscus singleyanus (Pilsbry) . 

Pupoides albilabris (Adams). _ _.

Ferrissia meekiana CStimpsoii) ....

pellucida hordeacella (Pilsbry) .

Abundance

Loc. 1

R

C

S 

C 

R 

C 

R

R

R 

R 

C

R

C

R 

A 

A 

C 

R 

S

S 

A 

S 

S 

R 

C 

C 

C

R 

R 

R

S 

S 

R 

C

R

S 

S

c

R

S

s

R 

R

Loc. 2

R

S

R

C

S 

R

C

C 

C 

A 

C

R

C

A 

R

S

R

S 

S 

S

R

S

c

A

S

R 

C

R 

R

S 

S

would not be transported as readily as those of smaller 

forms.

The mammals from Dixon local fauna locality 1 were 

studied by Hibbard (1956, p. 18). He stated "The 3 

species of Sorex, Blarina, and the 4 species of microtines indicate a marshy habitat along the water edge, 

and Blarina indicates the presence of trees and shrubs."

Thus the local habitat at locality 1 may have been as 

follows: A small to medium-sized river meandered 

slowly across the plain, depositing fine sand and silt. 

The quiet but more open water 2-4 feet deep had a 

molluscan assemblage dominated by BuJimnea megasoma and Helisoma anceps. Driftwood, reeds, and 

mussel shells in slow to moderate current furnished a 

suitable habitat, for Ferrissia. The dense growth of 

vegetation such as Potamogeton and MyriophyUum in 

thick patches here and there supported abundant 

Physa, Promenetus, Gyrcuulm, and Stagnicola refiexa. 

Shallow embayments and marginal pools near shore

had Physa, Fossaria, Gyraulus, Promenetus unbilicatellus, and Pisidium casertanum. On shore was some 

woodland, and damp grassy areas with dead wood and 

leaf mold supporting many small land snails.

Locality 2 was generally similar to locality 1, except 

that the fresh water and land faunas were not quite 

so diversified. The more common fresh water snails 

are those which live in subpermanent or temporary 

water bodies. The land snail assemblage at locality 2 

is like that of locality 1 in composition and in relative 

abundance of species, but suggests a little more grass 

and less woodland.

The local habitat was probably a side-channel, backwater, or oxbow pond which dried up partly in the 

summer. The reeds and submerged vegetation supported many Gyraulus, Helisoma, Planorbula, Promenetus, Stagnicola, Physa, and Ferrissia. In the

TABLE 18. Comparison of mollusks of Dixon local fauna with 

those living in Kingman County, Kans., by habitats

[Recent list based on Franzen and Leonard (1942) and personal collections]

Habitat

Permanent water:

Permanent to temporary 

water: 

Permanent or subpermanent.

Permanent or temporary. -

Temporary pond or marginal 

pool.

Temporary pond or stream. .. 

Marginal pools and wet mud.

Semiaquatic, riparian habitat.

Damp humus of wooded areaSpecies

Acroloxus coloradensis (Henderson) .

Promenetus kansisensis (Baker) ...

Promenetus umbilicatellus (Cockerell).

Stagnicola bulimoides techella 

(Haldeman)

cristata (Pilsbry and Vanatta).

Hawaiia minuscula (Binney) ------ 

Helicodiscus singleyanus (Pilsbry) --

Gastrocopta chauliodonta Taylor .... 

pellucida hordeacella (Pilsbry)-.

Ferrissia meekiana (Stimpson)...-- 

Phvsa skinneri Tavlor. . . ---------

Dixon

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X

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40 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

deeper parts of this quiet water, and especially toward 

the nearby stream, lived Bulimnea megasoma, Helisoma 

anceps, and Valvata. Soft mud furnished a suitable 

habitat for the common /Sphaerium partmneium. The 

vegetation on shore was grass and shrubs with some 

trees, among which many small land snails lived.

SANDERS LOCAL FAUNA

Previous work. This fauna was discovered in 1953 

by C. W. Hibbard and a University of Michigan field 

party. Collecting in 1953 and 1954 yielded mollusks, 

amphibians, birds, and mammals (Hibbard, 1956; 

Tihen,1955).

Fauna. Following is a list of the Sanders local 

fauna:

Class Gastropoda

Order Basommatophora

Stagnicola bulimoides tecliella (Haldeman) 

caperata (Say) 

sp.

Fossaria dalli (Baker) 

Gyraulus parvus (Say) 

Promenetus kansasensis (Baker)

umMlicatellns (Cockerell) 

PJiysa anatina Lea

skinner i Taylor 

Aplexa Jiypnorum (Linnaeus) 

Order Stylommatophora

Ga,strocopta chauliodonta Taylor 

crlstata (Pilsbry and Vanatta) 

paracristata Franzen and Leonard 

tappaniana (Adams) 

Vertigo milium (Gould)

ovata Say

Pupoides albilabris (Adams) 

Pupillidae, new genus and species? 

Vallonia perspectiva Sterki 

cf. Succinea

Helicodiscus singleyanus (Pilsbry) 

Deroceras aenigma Leonard 

Haicaiia minuscuJa (Binney) 

Class Amphibia 

Order Caudata

Ambystoma tigrinum (Green)? 

Class Aves

Undescribed bird remains 

Class Mammalia

Order Insectivora

Sorex sandersi Hibbard 

Order Rodentia

G-eomys tobiitemiis Hibbard 

Perognathuft cf. P. pcarlettensis Hibbard 

Prodipodomys sp.

tiigmodon cf. #. intermedium Hibbard 

Bensonomys meadentsis Hibbard 

Plioplienacomys meadensis Hibbard 

Pliolemmus antiques Hibbard 

Zapus sandersi Hibbard

Class Mammalia Continued 

Order Carnivora

Mustela sp. 

Order Proboscidea

Mastodont, indet. 

Order Artiodactyla

Camelidae, indet. 

Order Perissodactyla

Nannippus phlegon (Hay)

Plesippits simplicidens (Cope)

Occurrence. The Sanders local fauna is known only 

from Meade County, southwest Kansas.

Stratigraphy. The fauna occurs in the Missler 

member of the Ballard formation, above the caliche. 

Hibbard (1956, p. 150-151; 1958, p. 56) has published 

measured sections including localities of the Sanders 

local fauna.

Localities. All the following localities are in Meade 

County, Kans.

Locality 1 (University of Michigan UM-K1-53) : Center of 

south edge NW%NE& sec. 18, T. 32 S., R. 28 W. Exposure 

on tributary of Spring Creek, where Ballard formation unconformably overlies Rexroad formation. Rexroad local 

fauna locality 1 (Kansas University locality 25) is in this 

exposure also.

Localities 2 and 3 (University of Michigan UM-K2-53) : 

Near center of sec. 23. T. 32 S., R. 29 W. Exposures of gray 

silt above a tributary of Spring Creek. The two fossiliferous 

localities are only a few tens of feet apart and at the same 

stratigraphic horizon. All the vertebrates have been grouped 

as coming from one locality. The more numerous shells 

were kept separate to determine the extent of local environmental differences evidently minor. (See table 19.)

Age. The Sanders local fauna is believed to be of 

late Aftonian age from faimal evidence, ecologic inferences, and stratigraphic position. The faunal evidence from the restricted ranges of extinct groups 

comes primarily from the mammals. They indicate 

a Nebraskan or Aftonian age. Gastrocopta chauliodonta* otherwise known only from the Sand Draw and 

Dixon local faunas, also suggests an earliest Pleisticene 

age.

Ecologic inferences from the fauna suggest a mesothermal, subhumid climate with seasonal extremes 

much less marked than those of today. The fauna as 

a whole contrasts with the glacial assemblages which 

have a marked element of northern species. The inferred climate is intermediate between that of the 

glacial intervals and the warm-temperate, semi arid 

climate suggested by the caliche horizon. For these 

reasons the Sanders local fauna is called Aftonian.

The stratigraphic position of the fauna in the upper 

part of the Ballard formation, above a buried, massive 

caliche layer, is interpreted to indicate an age less than 

that of some part of the Aftonian. The caliche is be-
DESCRIPTION OF LOCAL FAUNAS 41

lieved to be Aftonian, but what part of this interval it 

represents is uncertain.

Paleoecology. Climate: Both characteristically 

northern and characteristically southern faunal elements occur in the Sanders local fauna. The most extreme contrast in distributions is between those of 

Physa sMnneri and Stagnicola bulimoides techella. 

These species now live hundreds of miles apart, but 

were associated in southwestern Kansas. The joint occurrence of these and other species is taken to indicate 

a former reduction of climatic extremes.

The southern element among the mollusks is composed of species which in the Great Plains are restricted to or characteristic of the southern part. These 

are Stagnicola l>ulimoides techella, (raxtrocopta crisfata, Vallonia perspective!, and Helicodiscus singleyanus. A moderately northern element is composed of 

Stagnicola caperata, Promenetus umbilicatellus, and 

Aplexa, hypnorum, which range south in the Great 

Plains as far as Nebraska. The most striking element 

is Physa sMnneri, which is widespread in the plains of 

southern Canada but unknown in the United States.

This association of species is different from that 

known in any other Blancan fauna. Southern and 

mid-northern species are known in the late Pliocene 

faunas, but with no markedly northern forms. Glacial 

faunas have a much reduced southern element, or none 

at all, and many northern species. Such a peculiar 

combination of elements is shown also by the mammals 

of the Sanders local fauna. Hibbard (1956, p. 156) 

noted that there are some southern types of mammals: 

the cotton rat (Sigmodon}, Bensonomys, and a kangaroo rat (Prodipodomys}. These, and the relative 

scarcity of shrews, suggest a wrarm, interglacial climate, 

but the cricetine rodents would then be expected to be 

common. "The paucity of cricetine rodents may be due 

in part to the habitat, but it is in contrast to their 

abundance in the warm-temperate Rexroad fauna" 

(Hibbard, 1956, p. 156).

The local lenses of grayish organic muds in which 

the Sanders local fauna occurs suggest small, shallow 

ponds or a slow-moving, unentreiiched stream. The 

aquatic snails and land snails of moist habitats indicate 

permanent moisture and subpermaneiit standing water. 

Hence, the Sanders local fauna probably lived in and 

near shallow annual ponds or else a small, slow-moving 

stream of local origin. The absence of genera usually 

associated with bushes or trees bordering such a habitat 

further suggests seasonal grassland ponds or streams. 

Neither of these situations necessarily implies greater 

rainfall than that of southwestern Kansas at the present time, but only greater effectiveness of precipitation. 

Milder summers might well account for this. Occurrence of the jumping mouse, Zapus, and the abundance 

of microtine rodents also indicates a moister climate 

(Hibbard, 1956, p. 156).

The former climate in which the Sanders local fauna 

lived thus differed from the present by more effective 

rainfall, and summers with much less intense hot 

spells. Neither distribution nor amount of annual 

rainfall was necessarily different.

An earlier interpretation of the fauna, based on my 

misidentification of /Stagnicola bulimoides techella, 

suggested that winters were considerably warmer than 

now (Hibbard, 1956, p. 156). The winters may indeed 

have been warmer than now, but the mollusks give no 

evidence for this.

Habitat. Table 19 summarizes habitat indications of 

the mollusks of the Sanders local fauna. All three localities seem to represent the same situation: shallow 

sub-permanent ponds or stream backwaters with surrounding grassy areas. Discus, Euconulus, Helicodiscus parallelus, Retinella, Zonitoides, and other 

forms usually associated with damp humus around 

dead wood are absent. This fact suggests that woodland, if present, was not all well developed, and recalls 

the hay meadow regions of north-central Nebraska. 

Here large areas of grassland have streams and ponds 

each spring, and trees are infrequent.

TABLE 19. Habitat indications of mollusks of Sanders local fauna 

[A, abundant (>250); C, common (41-250); S, scarce (8-40); R, rare (1-7)]

Habitat

Permanent to temporary 

water:

manent.

Temporary water: 

Temporary pond or marTemporary pond or 

stream.

Species

Promenetus kansasensis (Baker) .

Aplexa hypnorum (Linnaeus) _

Promenetus umbilicatellus (Cockerell). 

Stagnicola bulimoides techella 

(Haldeman) .

Vanatta) . 

Hawaiia minuscula (Binney)___- 

Helicodiscus singleyanus (Pilsbry). 

Pupoides albilabris (Adams). _- -_

paracristata Franzen and 

Leonard.

Vallonia perspectiva (Sterki)

I 

1

S

"R"

R

s 

c

A

S

A

R

C

A

A

A 

C

S

S 

R

C

C

jocalit 

2

R

R

R

S

R 

R

R

R

C

S 

S

s

R

R

S

R

Y 

3

R

R 

R

R

C

S 

C 

R

A

S

A

A 

R

S 

S

R

R

C

R

DEER PARK LOCAL FAUNA

Previous work. Collections at the Deer Park locality have been made by C. W. Hibbard and parties 

from the University of Kansas (1936, 1944) and Uni-
42 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

versity of Michigan (1954). The mammals now included in the Deer Park local fauna were originally 

referred to the Rexroad local fauna (Hibbard, 1938, 

1941a), but later recognized as coining from a higher 

stratigraphic horizon (Hibbard, 1949). A number of 

vertebrates but only one mollusk have been discovered 

(Hibbard, 1956).

Fauna. Following is a list of the Deer Park local 

fauna:

Class Gastropoda

Order Stylommatophora

Deroceras aenigma Leonard 

Class Reptilia

Order Chelonia

Testudo, large species 

Order Squamata

Snake, indeterminate 

Class Aves

Birds, indet. 

Class Mammalia 

Order Rodentia

Cynomys meadensis Hibbard

Citellus sp.

Geomys quitnri McGrew

Procastoroldes sweeti Barbour and Schultz

Ogmodontomys sp. or Mimomys (Cosomys) sp.

Pliopotamys meadensis Hibbard

Pliolemmus antiquus Hibbard 

Order Carnivora

Canis sp.

Mustelidae, indet.

Taxidea cf. T. taxus (Schreber) 

Order Proboscidea

Stegomastodon sp.

Rhynclwtherium sp. 

Order Lagomorpha

Hypolagus sp. 

Order Artiodactyla

Platygonus sp.

Camelidae, 2 indeterminate species 

Order Perissodactyla

Nannippus phlegon (Hay)

Plesippus simplicidens Cope

Occurrence. The Deer Park local fauna is known 

only from Meade County, southwest Kansas.

Stratigraphy. The fauna occurs in the Missler 

member of the Ballard formation (Hibbard, 1949, 

1956).

Localities. Only one locality is known, in Meade 

County State Park, near the west edge SE*4 sec. 15, 

T. 33 S., R. 29 W., Meade County, Kans. (University 

of Kansas Meade County loc. 1).

Age. Ecologic interpretation and the stratigraphic 

position of the Deer Park local fauna indicate an 

Aftonian age.

Paleoecology. The occurrence of pockets and tubes 

of flour sand within the surrounding unconsolidated 

silt and silty clay of the Missler member, badly worn

and polished bone fragments, the greater abundance 

of harder enamel teeth than bones, occurrence of the 

relatively strong slug shells and no other mollusk remains, and the similarity of the deposit to the numerous artesian springs of Meade County today all indicate that the Deer Park quarry is in deposits of a 

former artesian spring system. "The habitat in the 

neighborhood of these springs can be considered to 

have been similar to that characteristic of the same 

springs in Meade County today. The area of discharge is a death trap of boiling quick-sand, and the 

entire basin is a bog, in places choked with water 

cress and other aquatic plants that cover outlets of 

a part of the earlier dendritic pattern. The basin 

grades into a marsh that supports sedges and associated vegetation. Around the edges of the marsh 

and along the banks of the outlet area are trees, shrubs, 

and grapevines. This habitat furnishes not only a 

home for rodents and shrews but also a watering and 

feeding place for the larger grazers and browsers and 

for some carnivores. The remains consist chiefly of 

those of horses, mastodons, camels, and peccaries. The 

large grazers and browsers had probably ventured out 

too far from the edge of the basin while feeding" 

(Hibbard, 1956, p. 155-156). The slug Deroceras 

aenigma probably lived among the semiaquatic vegetation around the spring, along with many other snails 

whose shells have not been preserved.

"The climate at the time this fauna lived is regarded 

as interglacial because of the presence in it of the large 

land turtle Testudo, which could have inhabited the 

region only during a mild-temperate time" (Hibbard, 

1956, p. 156).

RECENT MOLLUSKS FROM NORTHERN NEBRASKA

In the summer of 1953 R. D. Mitchell, A. L. Lamb, 

and D. W. Taylor collected Recent mollusks at localities in north-central Nebraska while working on the 

Sand Draw local fauna. They are of interest in comparison with the Sand Draw local fauna, and also 

because mollusks from the area have not been reported 

before.

LOCALITIES

Cherry County. Nebr.:

1. Fort Niobrara National Widlife Refuge, 5 miles east 

of Valentine. Pond and seepage area at old fort 

reservoir.

2. North side Niobrara River flood plain % miles west 

of U. S. Highway 20. Nearly filled old oxbow lake 

with seepage and slight current.

3. Sand hills pond on west side U. S. Highway 83, 7.4 

miles south of junction with U. S. Highway 20. 

Temporary.

4. Small creek and tributary drainage ditches 4 miles 

northeast of Simeon. Subpermanent water.
RECENT MOLLUSKS FROM NORTHERN NEBRASKA 43

Cherry County, Nebr. Continued

5. Creek at junction of dirt road and paved road to 

Alkali Lake, 4.4 miles west of junction with U. S. 

Highway 83.

6. South side Red Deer Lake. Permanent water.

7. Lake on west side U. S. Highway 83, 20 miles north

of Thedford. Probably temporary. 

Brown County, Nebr.:

8. Wooded draw on south bluffs Niobrara River, on 

State Highway 7, 0.4 mile south of bridge across 

river.

9. Drainage ditches in northwest corner sec. 34, T. 30 

N., R. 22 W. Temporary water.

10. Drainage ditch at northwest corner sec. 10, T. 29 N., 

R. 22 W. Water probably permanent, but ditch dug 

recently.

11. Seepages along stream in wooded draw 50 yards south 

of Long Pine Creek at bridge 2% miles south of 

Long Pine.

12. Calamus River .5 mile west of State Highway 7.

Seepages along south bank. 

Rock County, Nebr.:

13. Drainage ditches along U. S. Highway 20, 2.8 miles 

west of Bassett.

14. Pond on north side U. S. Highway 20, 2.3 miles east

of Bassett. 

Hooker County, Nebr.:

15. Middle Loup River 5 miles east of Mullen. 

Thomas County, Nebr.:

16. Stock tank beside State Highway 2, 1 mile west of 

Seneca.

17. Middle Loup River at south side Thedford.

18. Middle Loup River, 1 mile east of Seneca.

HABITATS

The area studied lies on the northeast side of the 

Sand Hills region of western Nebraska, and thus 

includes two physiographic types, the Sand Hills and 

the High Plains proper. Each of these is discussed 

below.

High Plains. The part of the region collected in 

is typical: flat land sloping gently toward the Missouri River. Grassland is broken rarely by an occasional cottonwood tree. This flat surface is largely 

a plain of alluviation, probably completed sometime 

in the middle Pleistocene. The Mobrara River is 

incised well into this mantle, and its tributaries are 

cutting rapidly headward into the poorly consolidated 

sediments. The widespread sands and gravels form 

ideal aquifers; streamside patches of springs and 

seepage areas are abundant. Well-developed deciduous woodland occurs in these valleys wherever adequate water is available; pine stands cover the drier 

slopes. Drainage and irrigation ditches on the undissected upland dry up toward the end of summer. They 

often connect with ponds, also temporary. In this 

region land snails are largely restricted to stream valleys where cover and moisture are available. Freshwater mollusks are removed from the large streams 

by flooding, but are abundant in small spring-fed 

creeks, seepages, and upland ponds and ditches with 

no flood scour.

Sand Hills. The Sand Hills region is a huge area 

of western Nebraska covered by shifting sand loosely 

held by dune grass. The hills so formed vary in shape 

and size, but are similar in having only sparse grass 

growing on them. A large proportion of the hollows 

in this area contain shallow ponds, many large enough 

to be called lakes. Permanence is proportional to 

size; in the worst drouth years all but the largest 

lakes dry up. This large area is almost devoid of 

land snails, and the freshwater fauna is drastically 

reduced by the temporary nature of the water bodies. 

Stagnicola caperata, S. palustris, and Physa gyrina 

occur in nearly every pond; rich localities have 7 or 

8 species.

Most of the Sand Hills area is undrained, but some 

medium-sized streams flow from the area. The small 

creeks are but little more permanent than the ponds, 

but the rivers are perennial. The streams draining 

this region cannot flood, for rain sinks into the sand 

as soon as it falls. There are thus no accumulations 

of flood debris along the banks. There is essentially 

no mud or gravel anywhere, for the area is all sand. 

The only mud seen was in seepage areas along the 

rivers, where watercress and other semiaquatic plants 

have produced organic debris. As in the High Plains 

proper, deciduous woodland grows in the river valleys. 

Almost all of the few land snails occur in this habitat.

The habits are tabulated below, and the mollusks 

occurring in them listed in the following section.

I. Aquatic habitats.

A. Permanent water bodies.

1. Marginal stations. At the edge of ponds, snails 

occur in a semiaquatic position, frequently as 

much out of water as in it.

2. Quiet water.

a. Lake. Red Deer Lake (loc. 6) was the only 

one of this type sampled. The fauna does 

not differentiate it from, the temporary ponds.

b. Backwaters or sheltered spots along rivers. 

This habitat is peculiar to the Sand Hills 

for elsewhere each flood scours the banks.

c. Oxbow lake. The only such station visited 

(loc. 2) has a permanent water supply from 

seepage through the valley fill, but is not 

cooled by it.

d. Spring-fed pond. At locality 1 spring waters 

of 15 °C. were ponded. The summer-cool 

water is believed responsible for presence of 

some species in the area.

3. Flowing water. At numerous places along streams 

cut into the High Plains surface small springs 

and seepages occur. The mollusks are usually 

among the mud and water cress.
44 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

B. Subpermanent water bodies.

1. Ponds. These dry up only in drier years.

2. Sand Hills creeks. Quiet spots along such streams 

are more nearly permanent than most Sand 

Hills ponds, which they drain. 

C. Temporary water bodies.

1. Ponds. This category includes the temporary 

Sand Hills ponds as well as small ponds along 

ditches outside the Sand Hills. Locality 16 is 

a metal stock tank.

2. Ditches (irrigation and drainage). These fill up 

after heavy rains but because of their low 

gradient flow only slowly and do not flush out 

the snails.

II. Terrestrial habitats. 

A. Marginal stations.

1. Moist leaves around seepages.

2. Riparian station. Oxyloma was almost always 

within a few inches of permanent water, crawling about on water cress or logs.

3. Lake shore. At locality 7 SSuccinea was found 

on the wet shore several feet from the water's 

edge among sparse tall grass.

B. Damp ground. Among slightly damp leaves or on soil 

under timber or rocks.

SPECIES FOUND AT THE NOBTHERN NEBRASKA 

LOCALITIES

The first symbol of letters and numbers indicates 

the habitat type, the following numbers in parentheses 

the localities from pages 42-43.

SpJiacrium lacustre (Miiller) form ryckholti (Normand) IA3

(11), IC1 (3)

securis Prime, IBK14)

Pisidhtm casertanum (Poll), IA2c(2), IA3(11, 18) 

VaJvata tricarinata (Say), IA2d(l) 

Carychium exiguum (Say). IIAl(ll) 

Stagnicola palustris (Muller), IA2a(6), IB2(4), IC1(3, 7),

IC2(13)

caperata Say, IB2(4), IC1(3, 7), IC2(9, 13) 

Fossaria obrussa (Say), IA1U, 15, 17), IA3(11, 12)

daUi (Baker), IA2c(2), IA3U1) 

Armiger crista (Linnaeus). IB2(5) 

Gyraulus circumstrtatus (Tryon). IA3(11, 12), IB2(4),

parrits (Say), IA2a(6). IA2d(l), IB1(14), IB2(5), IC1(3),

IC2(13)

deflect us (Say), IA2d(l) 

Hclisoma anccpa (Menke), IA2d(l)

trivolris (Say), IA2a(6), IA2d(l), IB1(14), IC2(13) 

Planorbula armigera (Say). IA2c(2) 

Promenetus exacuous (Say). IBK14), IB2(5)

umbilieatPllus (Cockerell), IC1(3, 7), IC2(9) 

Physa anatina Lea, IA2d(l), IA3(1, 11, 12, 18)

gyrhta Say, IA2a(6). !A2b(17), IB1(14). IB2(4, 5), IC1 (3.

7, 16), IC2(10, 13)

Aplexa Inipnornm (Linnaeus), IC2(9, 13) 

Gastrocopta armifera (Say), IIB(l)

crlstata (Pilsbry and Vanatta), IIB(8)

holsinfferi (Sterki), IIB(l)

tappaniana (Adams), IIAl(ll), IIB(l)

Vertigo ovata (Say), IIAl(ll)

Vallonia gracilicosta Reinhardt, IIB(1, 8)

parvula Sterki, IIB(1, 8) 

Cionella lubrica (Muller), IIB(8) 

cf. Succinea, IIA3(7) 

Succinea ovalis Say, I1B(8)

Oxyloma retusa (Lea), IIAl(ll), IIA2(1, 2, 15, 18) 

Discus cronMiitei (Newcomb), IIB(2,11, 15) 

Punctum minutissimwn. (Lea), IIAl(ll) 

Deroceras laeve (Muller), IIAl(ll), IIB(1, 2, 15) 

Euconulus fulvus (Muller), IIB(2, 8, 11) 

Nesovitrea electrina (Gould), IIB(2,11, 15) 

Hawaiia minuscula (Binney), IIB(1, 15) 

Zonitoides arboreus (Say), IIB(1, 2, 8, 11, 15) 

Stenotrema leal (Binney), IIB(2)

SYSTEMATIC DESCRIPTIONS

Dates of genera and species given in the center 

headings have not been personally verified except in 

the case of extinct species. Sources are Pilsbry (1940, 

1946, 1948) for the land snails and Baker (1911, 1928, 

1928a) for the fresh-water mollusks.

References are intended to include all records of 

mollusks from the faunas considered, as well as the 

minimum number of general references, which were 

selected to indicate current taxonomic treatment and 

summaries of other references and of distribution.

Diagnoses (and usually descriptions) are given for 

all the extinct species restricted to the Blancan age, 

and for most of the other extinct species as well.

Distribution is based on the most reliable source 

known. The planorbid distributions without source 

indication are based upon my own examination of 

specimens, chiefly those in the University of Michigan 

Museum of Zoology.

Ecology is largely from published data. Personal 

observations made in northern Nebraska are added for 

comparison and supplement.

Occurrences cited are restricted to the faunas considered here. Numerous late Pleistocene records, for 

example, are not included.

Also under "Occurrences" are the abbreviation of 

the name of the institution, catalog number, and number of specimens represented. This last number is not 

the number of fragments examined, but the minimum 

number of shells required to furnish the fragments. 

Abbreviations are as follows: ANSP, Academy of 

Natural Sciences of Philadelphia; CNHM, Chicago 

Natural History Museum; UTMNH, University of 

Illinois Museum of Natural History; UKMNH, University of Kansas Museum of Natural History; 

UMMZ, University of Michigan Museum of Zoology; 

USGS, United States Geological Survey; USNM, 

United States National Museum.

H. B. Herrington identified the Sphaeriidae and 

contributed notes on the specimens. The data in this
SYSTEMATIC DESCRIPTIONS 45

paper are based on his notes and Herrington and 

Taylor (1958).

Taxonomic changes: summarized below are the new 

taxa proposed, and the disposition of species synonymized or relegated to different genera.

New:

Phreatomenetus n. subgen.; type Promenetus umMlicatellus (Cockerel!) 

Gastrocopta (s. s.) fransenae Taylor, n. sp.

(s. s.) scaevoscala Taylor, n. sp. 

Polygyra rexroadensis Taylor, n. sp. 

Changed in status:

Amnicola walkeri Pilsbry = A. lustrica Say 

CarycJiium perexiguum Baker = C. exiguum (Say) 

Lymnaea macella Leonard = Stagnicola exilis (Lea) 

parexilis Leonard = Stagnicola exilis (Lea) 

diminuta Leonard = Stagnicola bulimoides techella

(Haldeman)

turritella Leonard = Fossaria dalli (Baker) 

Gyraulus enaulus Leonard = G. parvus (Say) 

Menetus kansasensis Baker transferred to Promenetus 

Promenetus blancoensis Leonard = P. umbilicatellus

(CockereU)

Planorl>is circumlineatus Shuttleworth assigned to Promenetus

santacrusensis (Germain) assigned to Promenetus 

aemginosus Morelet assigned to Promenetus 

Vertigo (Angustula) Mbbardi Baker transferred to

Vertigo s. s.

Angustula Sterki, subgenus considered of minor rank and 

synonymized with Vertigo s. s.

Class PELECYPODA 

Order PRIONODESMACEA

Family TTNIONIDAE

Subfamily ANODONTINAE

Genus ANODONTA Lamarck, 1799

Subgenus PYGANODON" Crosse and Fischer, 1894

?Anodonta (Pyganodon) grandis Say, 1829

Anodonta grandis Say. Frierson, 1927, Check list of North

American naiades, p. 14. 

Baker, 1928, Wisconsin Geol. Nat. History Survey Bull. 70,

pt. 2. p. 152, pi. 62, fig. 5. 

Anodonta gigantea Lea. Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 2, p. 161, pi. 62, fig. 4; pi.

65, fig. 3.

Remarks. Fragments referred to this species were 

found as float in the West Fork of Deep Creek, sees. 

11 and 14, T. 31 N., R. 23 W., Brown County, Nebr. 

They are probably from the same stratigraphic position as the other material collected on Deep Creek, 

but a more precise locality cannot be given. One fragment shows enough of the adductor and retractor 

muscle scars to indicate it probably represents Ano508945 O 60 5

donta. Thickness of shell and geographic location 

make A. grandis the most reasonable specific allocation.

Material from Sand Draw locality 2 is indeterminate, and only presumptively referred to the same 

species.

Occurrence and material: Sand Draw local fauna. West 

Fork of Deep Creek, UMMZ 184321 (1) ; loc. 2, UMMZ 184167

(1).

Family ftUADRULIDAE

Subfamily LAMPSILINAE 

Genus LIGTTMIA Swainson, 1840 

?Ligumia subrostrata (Say), 1831

Lampsilis subrostrata (Say). Isely, 1925, Oklahoma Acad.

Sci. Proc., v. 4, p. 108. 

Lampsilis subrostrata Say. Frierson, 1927, Check list of North

American naiades, p. 77.

Remarks. Dr. Henry van der Schalie identified a 

fragmentary valve showing beak sculpture and worn 

pseudocardinal teeth as probably either Ligumia subrostrata (Say) or Uniomerus tetralasmus (Say), of 

which the former seems more likely.

Occurrence and material: Rexroad local fauna. Rexroad 

loc. 3, UMMZ 183025 (1/2).

Order TELEODESMACEA

Family SPHAERIIDAE

Genus SPHAERITTM Scopoli, 1777

Sphaerium partumeium (Say), 1822

Musculium partumeium (Say). Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 354, pi. 99, fig.

24-26. 

Sphaerium partumeium (Say). Herrington and Taylor, 1958,

Michigan Univ. Mus. Zool. Occ. Papers 596, p. 7. 

Musculium truncatum (Linsley). Baker, 1928, Wisconsin

Geol. Nat. History Survey Bull. 70, pt. 2, p. 356, pi. 99,

fig. 21-23.

Distribution. "Most of the United States; less common in mountainous areas. Southern Canada from 

Saskatchewan to Quebec" (Herrington and Taylor, 

1958, p. 8).

Ecology. "Ponds and eddies in rivers where there 

is considerable vegetation and a soft bottom" (Herrington and Taylor, 1958, p. 8).

Remarks. None of the shells from the Sand Draw 

local fauna is complete, but several are nearly so. They 

compare well in every feature with a series (Herrington collection S-658) of S. partumeium from Baton 

Rouge, La., except that the Baton Rouge specimens 

are somewhat larger but they are also larger than 

the usual northern specimens. The shells from the
46 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Dixon local fauna are identified certainly, even though 

most are only fragments.

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 1, UMMZ 186369 (77/2). Dixon loc. 

2, UMMZ 191501 (114/2), 191502 (17/2).

Sphaerium lacustre (Miiller), 1774 

form ryckholti (Normand), 1844

Musculium ryckholti (Normand). Baker, 1928, Wisconsin

Geol. Nat. History Survey Bull. 70, pt. 2, p. 359, pi. 99,

fig. 6-9. 

Musculium jayense (Prime). Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 353, pi. 99, fig.

27, 28. 

Musculium rosaceum (Prime). Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 359, pi. 99, fig.

19, 20. 

Sphaerium lacustre (Miiller) form ryckholti (Normand).

Herrington and Taylor, 1958, Michigan Univ. Mus. Zool.

Occ. Papers 596, p. 8. 

Sphaerium sp. Frye and Leonard, 1952, Kansas Geol. Survey

Bull. 99, p. 151 (Kingman County loc.).

Distribution. Holarctic. In North America from 

the Southern United States to the Northwest Territories. This form of lacustre is also found in Europe 

and Brazil.

Ecology. "It seems to have a preference for ponds 

where there is considerable vegetation and even bog 

ponds that have a bottom of muck, rotting wood, 

grasses, and the like" (Herrington and Taylor, 1958, 

p. 9).

Remarks. Shells from the Dixon local fauna are 

near the form ryckholti in shape. They are a little 

heavier than usual but not more so than some Recent 

specimens. None are whole, but a number of fragments are large and a few nearly whole. In beaks 

and outline these seem to be lacustre.

The reference by Frye and Leonard is attributed to 

this species because 8. lacustre is the commonest 

Sphaerium in the Dixon local fauna.

Occurrence and material: Dixon local fauna; Recent in 

northern Nebraska. Dixon loc. 1, UMMZ 186386 (31/2).

Sphaerium securis (Prime), 1851

Musculium securis (Prime). Baker, 1928, Wisconsin Geol. 

Nat. History Survey Bull. 70, pt. 2, p. 360, pi. 99, fig. 

10-13.

Distribution. "East of the Rocky Mountains, but 

apparently rare in the South and wanting in the Gulf 

States; common in the Northeast; South Carolina"" 

(Baker, 1928a, p. 361).

Ecology. In northern Nebraska it was found in a 

small permanent or nearly permanent pond in sandy 

bottom among dense vegetation in shallow water.

Occurrence: Recent in northern Nebraska.

Sphaerium .striatinum (Lamarck), 1818

Sphaerium striatinum (Lamarck). Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 2, p. 334, pi. 

98, fig. 1-5.

Herrington and Taylor, 1958, Michigan Univ. Mus. Zool. 

Occ. Papers 596, p. 9.

Distribution. Almost all of North America, from 

Great Slave Lake, Northwest Territories, to Panama.

Ecology. Perennial water bodies with some current 

action are suitable habitats. It lives in large lakes or 

small ones, in rivers or small streams, in a bottom of 

gravel, sand, or mud. Ponds, lagoons, and swamps are 

not favorable places, probably because there is insufficient current to oxygenate the water well.

Occurence and material: Saw Rock Canyon and Sand Draw 

local faunas. Saw Rock Canyon, UMMZ 186408 (1/2), an 

infant right valve. The shell is the size of an infant recently 

expelled from the parent. Sand Draw loc. 1, UMMZ 186368 

(5/2). The only complete valve from this locality has a reversed hinge all the hinge characters are those of the right 

valve, but at opposite ends. This valve perfectly matches some 

Recent ones of the heavy form in the Herrington collection in 

shape of shell, striae, and shape of hinge characters, but the 

cardinal is slightly more central. Sand Draw loc. 3, UMMZ 

181125 (3/2). A fragment of the anterior end of a right 

valve has striae which seem too coarse for S. sulcatum. Fragments of two more valves are referred doubtfully to S. 

striatinum.

Sphaerium sulcatum (Lamarck), 1818

Sphaerium sulcatum (Lamarck). Herrington and Taylor,

1958, Michigan Univ. Mus. Zool. Occ. Papers 596, p. 9. 

Sphaerium simile (Say). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 2, p. 313, pi. 96, fig. 4-7. 

Sphaerium simile planatum Sterki. Baker, 1928, Wisconsin

Geol. Nat. Hist. Survey Bull. 70, pt. 2, p. 317, pi. 96,

fig. 8-10; pi. 98, fig. 29-33. 

Sphaerium crassum Sterki. Baker, 1928, Wisconsin Geol. Nat.

Hist. Survey Bull. 70, pt. 2, p. 318, pi. 96, fig. 11-13. 

Sphaerium lineatum Sterki. Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 321, pi. 96, fig.

18-21.

Distribution. "Northeastern North America from 

Quebec to Virginia, west to Iowa, Montana, and Alberta" (Herrington and Taylor, 1958, p. 10).

Ecology. S. sulcatum has a preference for a soft 

bottom in fairly still waters, in eddies of a creek or 

river, along shore in lakes, and even in lakes filling 

up with marl. Herrington has found it associated 

with Pisidium compressum in all these habitats.

Occurrence and material: Sand Draw local fauna. Sand 

Draw loc. 1, UMMZ 186370 (3/2). All are good-sized adults, 

but somewhat broken. The striae are normal. One left valve 

has both ends complete but the cardinal area is broken out.
SYSTEMATIC DESCRIPTIONS 47

Sphaerium transversum (Say), 1829

Musculium transversum (Say). Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 351, pi. 98, fig.

22-25 [not 22-28]. 

Sptiaerium transversum (Say). Herrington and Taylor, 1958,

Michigan Univ. Mus. Zool Occ. Papers 596, p. 8.

Distribution. "North America east of the Rocky 

Mountains from Mexico to the Northwest Territories1 ' 

(Herrington and Taylor, 1958, p. 8).

Ecology. "In rivers, ponds and lakes, usually in 

soft mud, on the surface or buried at different depths" 

(Baker, 1928a, p. 352).

Remarks. A large specimen from the Dixon local 

fauna seems to be transversum. A dwarf form of this 

species which occurs in the Sand Draw local fauna 

resembles certain living individuals that appear in 

unfavorable habitats.

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 3, UMMZ 186378 (43/2). Dixon 

loc. 1, UMMZ 186385 (10/2).

Sphaerium species

Sphaerium sp. Frye and Leonard, 1952, Kansas Geol. Survey

Bull. 99, p. 151 (Meade County localities). 

Sphaerium indet. Herrington and Taylor, 1958, Michigan

Univ. Mus. Zool. Occ. Papers 596, p. 13. 

Remarks. Some specimens from several localities 

are unidentifiable specifically, because they are immature or too fragmentary. They may well represent 

the thinner-shelled species, partumeium, lacustre, and 

transversum.

University of Michigan collections contain no 

tSphaerium from the Rexroad or Bender local faunas. 

The material reported by Frye and Leonard from the 

SWVi sec. 22, T. 33 S., R. 29 W., Meade County, Kans. 

probably came from Rexroad locality 3, for Bender 

locality 1 has yielded few aquatic forms.

Occiirence and material: Saw Rock Canyon and Sand Draw 

local faunas; Rexroad local fauna (Frye and Leonard). Saw 

Rock Canyon, TTMMZ 177514 (1), 177553 (6/2). Sand Draw 

loc. 2, UMMZ 184168 (1/2); loc. 3, UMMZ 181124 (2/2), 

186379 (31/2) ; loc. 4, UMMZ 186373 (8/2) ; loc. 5, UMMZ 

186374 (18/2), 186366 (263/2); loc. 7, UMMZ 186381 (1/2), 

177225 (5/2).

Genus PISIDITTM Pfeiffer, 1821 

Pisidium casertanum (Poll), 1791

Pisidium. casertanum (Poli). Woodward, 1913, Catalogue of 

British species of Pisidium, p. 31, pi. 1, fig. 3-6; pi. 3, 

fig. 3; pi. 13-18.

Herrington, 1954, Nautilus, v. 67, p. 131.

Hibbard, 1954, Michigan Acad. Sci. Papers, v. 39, p. 342.

Herrington and Taylor. 1958, Michigan Univ. Mus. Zool. 

Occ. Papers 596, p. 14.

Pisidium sp. Baker, 1938, Nautilus, v. 51, p. 131.

Hibbard, 1941, Kansas Univ. Sci. Bull., v. 27, p. 95.

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

p. 408.

McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser., v. 9, p. 36. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151 (Meade County localities).

Psidium sp. Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p, 

265.

Distribution.. "Almost cosmopolitan: Eurasia, New 

Zealand, and Australia; in the Western Hemisphere 

from Patagonia to Alaska" (Herrington and Taylor, 

1958, p. 14).

Ecology. The wide distribution of Pisidium casertanum reflects a corresponding adaptability, greater 

than any other American sphaeriid. It lives where any 

other species of Pisidium can live, except for deep 

water. The typical form of the species, with relatively 

heavy shells, lives in rivers or fairly large creeks. 

Thinner shells with smoother outline are found in 

ponds, swamps, lagoons, bog ponds, and similar quiet 

water bodies. P. casertanum is one of the few species 

of Pisidium which can tolerate seasonal desiccation, 

and sometimes it may be the only aquatic mollusk in a 

small, temporary stream or seepage.

Remarks. Previous records of Pisidium sp. from 

the Rexroad local fauna are probably based on P. 

casertanum, for this is the only one in University of 

Michigan collections. The original specimens reported 

by Baker and McGrew from the Sand Draw local 

fauna have been verified as P. casertanum.

Occurence and, material: Buis Ranch, Saw Rock Canyon, Red 

Corral. Rexroad, Sand Draw, and Dixon local faunas; Recent in northern Nebraska. Buis Ranch, UMMZ 181119 (1/2). 

Saw Rock Canyon, UMMZ 173587 (51/2), 195838 (1 + 

1398/2). This series shows much variation in shape, just as 

one finds in Recent shells. Some of the shells are pitted, 

evidently by solution. Many are in fragments, but this seems 

to be the result of removal from the matrix. The specimens 

show no signs of being rolled, for the laterals and cardinals 

are unbroken. Red Corral, UMMZ 182992 (58/2). These 

shells suggest still water. They are like those found in small, 

slow-moving creeks that go dry for part of the year, or in 

lakes filling up with marl. Rexroad loc. 2, UMMZ 186388 

(3/2) ; loc. 3, UMMZ 186387 (11/2). Sand Draw loc. 3, 

UMMZ 186377 (8/2). Mostly form roperi. Loc. 4, UMMZ 

177311 (58/2). Form roperi Sterki. Much broken. Some 

have "rest periods," like capped beaks at more than one place. 

Loc. 5, UMMZ 186367 (32/2), 181134 (11/2). Mostly form 

roperi Sterki; the others are close. Most have strong "rest 

periods" or capped beaks. Loc. 6, CNHM PE3439 (2/2). Loc. 

7, TTMMZ 177226 (25/2). Mostly form roperi Sterki. Dixon 

loc. 1, UMMZ 186383 (H/2).

Pisidium compressum Prime, 1851

Pisidium compressum Prime. Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 2, p. 370, pi. 100, fig. 9-13. 

Herrington, 1954, Nautilus, v. 67, p. 135. 

Herrington and Taylor, 1958, Michigan Univ. Mus. Zool.

Occ. Papers 596, p. 15.
48 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Pisidium sp. Frye and Leonard, 1952, Kansas Geol. Survey 

Bull. 99, p. 151 (Kingman County loc.).

Distribution. "North America, from Mexico to 

Great Slave Lake, Northwest Territories" (Herrington 

andTaylor, 1958, p. 16).

Ecology. This species inhabits only perennial water 

bodies with some current action, such as lakes, rivers 

and creeks; it is never found in ponds, swamps, lagoons, or bogs.

Remarks. The reference by Frye and Leonard is 

attributed to this species because P. compression is 

the most abundant Pisidium in the Dixon local fauna.

Occurrence and, material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 1, UMMZ 186371 (579/2). These 

clearly have the hinge charcters of compressum. The beaks 

are moderately narrow. A few give hints of ridges. The 

striation varies considerably, but suggests compressum. The 

shells are rather light in heft and, on the whole, give the 

impression of rather still water, not where there is swift 

running water with a sandy gravel or where there is heavy 

wave action. Loc. 3, UMMZ 177328 (1172/2). Mostly thin, 

many fractured, perhaps in recovering. All have narrow 

beaks but only the slightest number show even a hint of a 

ridge. These show considerable variation in outline. Loc. 6, 

UMMZ 186372 (1/2), 177422 (3/2). Dixon loc. 1, UMMZ 

186382 (240/2). Good specimens. Striae as coarse as usual; 

beaks narrow, some with faint hints of ridges. A little longer 

than the usual form found in creeks; could have come from 

a creek or small lake.

Pisidium nitidum Jenyns, 1832

Pisidium nitidum Jenyns. Woodward, 1913, Catalogue of 

British species of Pisidium, p. 44, pi. 1, fig. 9; pi. 3, fig. 

6; pi. 19.

Herrington, 1954, Nautilus, v. 67, p. 132.

Herrington and Taylor, 1958, Michigan Univ. Mus. Zool. 

Occ. Papers 596, p. 15.

Distribution. Holarctic. Eurasia and North Africa; 

in North America from Hudson Bay to Mexico, except 

for the southeastern United States.

Ecology. Found only in perennial water bodies, 

such as lakes, ponds, rivers, and large creeks.

Remarks. The fossil specimens are of the form 

commonly found in lakes that are drying up or have 

dried up.

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 3, UMMZ 186375 (347/2), 186376 

(7/2). The hinge of these varies from moderately heavy to 

light. Seven valves (UMMZ 186376) are of the form paupcrclum Sterki. One of these latter has a steep posterior slope 

like a pauperculum approaching the form contortum. Loc. 

7, UMMZ 186380 (1/2). Fragmentary. Dixon loc. 1, UMMZ 

186384 (8/2).

Class GASTROPODA

Subclass PROSOBRANCHIA

Order MESOGASTROPODA

Family VALVATIDAE 

Genus VALVATA Miiller, 1774 

Valvata tricarinata (Say), 1817

Valvata tricarinata (Say). Baker, 1928, Wisconsin Geol Nat.

History Survey Bull. 70, pt. 1, p. 11, pi. 1, fig. 1-3. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 12. 

La Rocque, 1956, Nautilus, v. 70, p. 13.

Valvata tricarinata perconfusa Walker. Baker, 1928, Wisconsin Geol. Nat. History Survey Bull. 70, pt. 1, p. 16, pi. 

1, fig. 4.

Valvata tricarinata unicarinata DeKay. Baker, 1928, Wisconsin Geol. Nat. History Survey Bull. 70, pt. 1, p. 16, pi. 1, 

fig. 5.

Valvata tricarinata mediocarinata Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 1, p. 17, pi. 1, 

fig. 7.

Valvata tricarinata basalis Vanatta. Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 1, p. 17, pi. 1, 

fig. 8, 9.

Valvata tricarinata infracarinata Vanatta. Baker, 1928, Wisconsin Geol. Nat. History Survey Bull. 70, pt. 1, p. 18.

Valvata tricarinata simplex Gould. Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 1, p. 18, pi. 1, 

fig. 10, 14.

Distribution. "Eastern United States west to Iowa; 

Great Slave Lake south to Virginia and the Ohio 

River" (Baker, 1928, p. 14) ; an isolated spring occurrence in Cherry County, Nebr.

Ecology. A species found only in permanent lakes 

and rivers. In northern Nebraska this species was 

found in a spring-fed pond of temperature 15 °C. The 

snails were crawling on aquatic plants, largely Ceratophyllum^ Elodea, and algae, near the edge of the pond.

Remarks. Valvata tricarinata was found considerably south of its previously known range in a springfed pond at the old fort reservoir in the Fort Niobrara 

National Wildlife Eefuge, 5 miles east of Valentine, 

Cherry County, Nebr. Its existence at this locality 

is considered possible because of the insulating effect 

of the cool spring water. This northern species is 

probably able to live here because the pond is warmed 

little if at all during the summer hot spells. Other 

permanent ponds in Cherry County, apparently similar except that they lack spring sources, were examined 

without finding this species.

Occurrence and material: Sand Draw and Dixon local 

faunas; Recent in northern Nebraska. Sand Draw loc. 2, 

UMMZ 184170 (65). Carinae 101, 64 specimens; carinae 

001, 1 specimen. Loc. 3, UMMZ 177329 (2500). Carinae 101, 

about 2500 specimens; carinae 100, 12 specimens; carinae 001, 

20 specimens; carinae 000, 16 specimens. Dixon loc. 2, UMMZ
SYSTEMATIC DESCRIPTIONS 49

191503 (33). Carinae 111. The 17 Recent specimens are tricarinate, 111.

Valvata lewisi Currier, 1868

Valvata lewisi Currier. Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 26, pi. 1, fig. 28-30. 

Valvata leivisi Jielicoidea Dall. Baker, 1938, Nautilus, v. 51,

p. 130. 

McGrew, 1944, Field Nat. Mus. Hist. Geol. Ser., v. 9, p. 36.

Distribution. "Northern part of the United States 

from the Atlantic to the Pacific oceans, northward, in 

British America, to the upper Mackenzie River. Its 

southward range is not fully known" (Baker, 1928, 

p28).

Ecology. "* * * a lake species largely" (Baker, 

1928, p. 28).

Remarks. A higher spire in the former is the 

principal distinction between V. lewisi and V. lewisi 

helicoidea. Variation of this character in the lots 

examined is such that separation of the two forms 

does not appear practicable in this case.

Occurrence and material: Sand Draw local fauna. Sand 

Draw loc. 5, CNHM PE3428 (125), UIMNH P6781 (26) ; loc. 

6, UMMZ 177423 (400), 181208 (150).

Family VIVIPARIDAE 

Genus and species uncertain

Remarks. Two small individuals represent this 

family, but are inadequate for closer identification.

Occurrence and material: Dixon local fauna. Dixon loc. 1, 

UMMZ 182193 (1) ; loc. 2, UMMZ 191504 (1).

Family HYDROBIIDAE

Classification of this family is still in a primitive 

state, and nomenclature is in flux. Shells of this 

group provide less information than in perhaps any 

other family of freshwater snails. Snails with markedly different opercula, radulae, and reproductive 

apparatus may have similar shells; rather different 

shells may contain animals of similar anatomy. Fossil 

shells of the Hydrobiidae are thus often very difficult 

to classify with any conviction of certainty.

For many years two family names have been used: 

Europeans have called the group Hydrobiidae, while 

Americans have preferred the term Amnicolidae. "Hydrobiae" Troschel, 1857 (1856-1893, v. 1, p. 106), has 

priority over Amnicolidae Tryoii (1862, p. 452), and 

hence the name Hydrobiidae is preferable.

The subfamily divisions listed below are slightly 

modified from Morrison (1949) :

Hydrobiinae: verge with one functional duct (vas 

deferens).

Amnicolinae: verge with two functional ducts (vas 

deferens, and accessory duct of secondary lobe) ; operculum corneous, paucispiral.

Buliminae: verge as in Amnicolinae; operculum calcareous, concentric with subspiral nucleus.

Emmericiinae: verge with three functional ducts 

(vas deferens, and an accessory duct in each of two 

secondary lobes).

The second subfamily was called Bythinellinae by 

Morrison (1949), but is here changed to Amnicolinae. 

The term Amnicolidae is the second oldest group name 

within the Hydrobiidae, and deserves retention in some 

form. Its application, however, involves the complicated question of identification of the genotype of 

Amnicola (Morrison 1947, H. B. Baker 1947), Paludina lustrica Say, 1821.

The original description is as follows (Say, 1821, p. 

175):

P. *lustrica. Shell conic, whirls slightly wrinkled, convex; 

suture profoundly indented; aperture oval nearly orbicular; 

labrum with the superior edge not appressed to the preceding 

whirl, but simply touching it; umbilicus rather large, rounded. 

Length less than %o of an inch. Cabinet of the Academy. 

The smallest species I have seen. The aperture somewhat resembles that of a Valvata, to which genus it may probably be 

referrible. Mr. Jessup obtained two specimens, on the shore 

of Cayuga Lake.

Distinctive features mentioned in this description 

are conical shape, very deep suture, a nearly circular 

aperture which simply touches the preceding whorl 

and is not modified in outline by it, very small size. 

Only two species of the general region (cf. Letson 

1905) approach this character combination: Amnicola 

loalkeri Pilsbry, 1898, and Lyogyrus granum (Say), 

1822. But Say contrasted L. granwn with Paludina, 

lustrica in his description of the former, indicating 

that he thought of the two as distinct.

Berry (1943, p. 26) described the shell of Amnicola 

walkeri thus:

About 2.5 mm high, 2.2 mm wide, thin, broadly conic in outline. Four whorls increasing regularly in size. Apex obtuse, 

elevated, whorls shouldered, convex; sutures very deep. 

Aperture almost circular (1.04 mm wide; 1.04 mm high). 

Peristome continuous, adnate to the preceding whorl for only 

a short distance. Umbilicus rather wide, deep. Periostracum 

light tan, lines of growth crowded but distinct, often concealed with a deposit from its environment.

The descriptions by Say and Berry are so strikingly 

similar that it seems highly probable that they refer 

to the same species.

Accepting Paludina lustrica Say as being the species 

generally known heretofore as Amnicola walkeri, we 

find that fortunately there are no major changes in 

the group concept. Berry (1943) showed the close
50 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

relationship between A. walkeri. now A. lustrica 

(Say), and A. limosa (Say), usually but erroneously 

considered the type species.

The classification and generic synonymy of groups 

treated by Morrison (1947) implied by synonymization of Amnicola walkeri with Paludina lustrica and 

by acceptance of Morrison's (1949) outline of the 

Hydrobiidae is as follows:

Family Hydrobiidae

Subfamily Hydrobiinae

Genus Marstonia F. C. Baker, 1926. Type (by original 

designation) : Amnicola lustrica Pilsbry, 1890 [not 

of Say, 1821] = Amnicola lacustris Morrison, 1947. 

Subfamily Amnicolinae

Genus Amnicola Haldeman, 1840. Type (by original 

designation) : Paludina lustrica Say, 1821, Amnicola walkeri Pilsbry, 1890.

Subjective synonyms: Euamnicola Crosse and 

Fischer, 1891.

Type: Paludina lustrica Say; the statement "(ou 

Anmicola sensu stricto)" fixed the type as that 

of Amnicola, no matter whether or not Crosse and 

Fischer correctly listed the type of Amnicola.

Marstoniopsis Altena, 1936. Type (by original 

designation) : Hydro'bia steinii v. Martens, 1858.

Subfamily HYDROBIINAE

Genus MARSTONIA Baker, 1926

Marstonia crybetes (Leonard), 1952

Plate 2, figures 1-3, 7, 8

Amnicola crybetes Leonard, 1952. Nautilus, v. 66, p. 38, pi. 5,

fig. A. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151, pi. 14, fig. h. 

Types. Holotype UKMNH 3805, Saw Rock Canyon local

fauna. Paratypes UKMNH 3806.

Diagnosis. A Marstonia shorter and wider than 

other species of the genus, with ovate-pyriform aperture and moderately impressed suture.

Description. Shell small, ovate, conoidal, with 

acute spire and apex. Whorls 4 to 41/2, convex, gently 

shouldered and slightly flattened peripherally, expanding fairly rapidly; body whorl about three-fourths 

of total shell length. Embryonic shell of about one 

whorl, not depressed to the level of the postembryonic 

whorls. Suture strongly impressed, slightly below 

periphery of whorls. Aperture simple, entire, ovatepyriform; peristome appressed to preceding whorl or 

simply adnate, broadly rounded below, narrowly 

rounded to obtusely angular at junction of outer and 

parietal lips. Umbilicus small but distinct, about oneninth of shell diameter. Sculpture consists only of 

very fine growth lines on the postembryonic shell.

Number of specimens., ,

Length: 

Mean.. ___________ _ _

Standard deviation

Width: 

Mean. _______ __

Standard deviation, _ _ _ 

Length aperture:

Standard deviation. 

Width aperture:

Standard deviation. 

Width to length ratio:

Standard deviation. 

Length aperture to length 

ratio:

Standard deviation.

Number of whorls

3%

25

2. 35 ±. 026 

. 13 ±. 018

1. 80 ±. 020 

. 10 ±. 014

1.20 ±.018 

. 09 ±. 013

. 95 ±. 012 

. 06 ±. 008

.76 ±.0058 

. 029±. 0041

.52 ±.0054 

. 027±. 0038

4

44

2. 63 ±. 033 

.22 ±.023

1.96 ±.027 

. 18 ±. 019

1.33 ±.018 

. 12 ±. 013

1. 08 ±. 017 

. 11 ±. 012

. 74 ±. 0039 

. 026±. 0028

.51 ±.0041 

. 027±. 0029

4H

36

2.95 ±.027 

. 16 ±. 019

2. 16 ±. 027 

. 16 ±. 019

1. 44 ±. 017 

. 10 ±. 012

1. 15 ±. 013 

.08 ±.0094

. 73 ±. 0037 

. 022±. 0026

. 49 ±. 0032 

. 019±. 0022

4}£

25

3. 23 ±. 028 

. 14 ±. 020

2. 30 ±. 024 

.12 ±.017

1.51 ±.014 

. 07 ±. 010

1. 24 ±. 018 

.09 ±.013

.71 ±.0042 

. 021 ±. 0030

.47 ±.0028 

. 014±. 0020

Measurements. A large series of specimens (UMMZ 

177554) from the Saw Rock Canyon site was sampled 

to study variation in several size groups selected on 

number of whorls. Measurements are in millimeters.

Variation. The size range of adults is uncertain 

because adult shells cannot be distinguished surely 

from juveniles on any character other than size. Some 

variation is, however, evident from the fact that shells 

of 4% whorls are rare, and those of 4^2 and 41/4 

whorls progressively more common. Variation in 

shape, the most conspicuous variant, is shown under 

Measurements. The last part of the body wrhorl varies 

in degree of appression, so that the peristome may be 

appressed or adnate; rarely the last part of the body 

whorl is disjunct.

Remarks. Amnicola crybetes Leonard is referred to 

the genus Marstonia because of its similarity to M. 

decepta (Baker), the genotype. With the latter species 

it shares an acute spire, undepressed nuclear whorl, 

narrow umbilicus, and ovate-pyriform aperture. Cincinnatia [as exemplified by C. Integra (Say) and C. 

peracuta (Pilsbry and Walker)] has a shell of similar 

shape but larger, with a larger nuclear whorl. Amnicola lustrica (Say), to which Leonard compared M. 

crybetes in describing the latter, has a slightly smaller 

shell with more deeply incised sutures, a nearly round 

aperture, and more conspicuous umbilicus.

Marstonia decepta differs from M. crybetes by its 

larger size and proportionately narrower shape; otherwise shells of the two are similar.

The material recorded by Frye and Leonard (1952, 

p. 151) from the SWl/4 sec. 22, T. 33 S., R, 29 W., 

Meade County, almost certainly came from Rexroad 

locality 3 rather than Bender locality 1. Habitat inferences from Bender locality 1 species suggest only
SYSTEMATIC DESCRIPTIONS 51

temporary bodies of water. Rexroad locality 3 had the 

permanent water which Marstonia crybetes required.

Occurrence and material: Saw Rock Canyon and Rexroad 

local faunas; Dixon local fauna (Frye and Leonard). Saw 

Rock Canyon, UMMZ 173593 (33), 177554 (500), USGS 

19089-11 (100) ; Rexroad loc. 1, UMMZ 183051 (1) ; loc. 4b, 

UMMZ 177597 (2), 181046 (2).

Marstonia decepta (Baker), 1928

Plate 2, figure 9

Amnicola lustrica decepta Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 108, text fig. 45. 

Amnicola lustrica Pilsbry. Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70. pt. 1, p. 104, pi. 6, fig. 16, 17,

26, 27; text fig. 45. 

Amnicola (Marstonia) lustrica Pilsbry. Berry, 1943, Michigan

Univ. Mus. Zool. Misc. Publ. 57, p. 29, pi. 1, fig. 4-6; pi.

3, fig. 3; pi. 5, fig. 6; pi. 7, fig. 4. 

Amnicola lacustris Morrison, 1947, Nautilus, v. 60, p. 86.

Distribution. New York west to Minnesota and 

Iowa; north-south range uncertain (F. C. Baker, 1928, 

p. 106-107; USNM colln.).

Remarks. Two specimens associated with abundant 

M. crybetes differ from that species by their narrower 

form and smaller aperture. Their measurements in 

mm: length 2.8, 2.7; width 1.8, 1.7; length aperture 

1.1, 1.1; width aperture 1.0, 0.9; width/length ratio 

0.66, 0.64; length aperture to length ratio 0.41, 0.42; 

both have 4^ whorls. Comparison of these measurements with those given under M. crybetes shows that 

the two narrow specimens fall more than three standard deviations from the mean of the characters width, 

length of aperture, and the length of aperture to 

length ratio, and close to this distance for other characters. It is therefore most unlikely that these two 

shells are only extreme variants of Marstonia crybetes. 

They agree well with U. S. National Museum material 

of M. decepta, except for being slightly smaller, and 

are referred to that species.

The species nomenclature is involved. Morrison 

(1947) proposed Amnicola lacustris as a new name for 

the preoccupied A. lustrica Pilsbry, [not Say]. In 

1928, however, F. C. Baker had added two varietal 

names to the species: A. lustrica decepta and A. lustrica. perlustrica. Both of these have priority over A. 

lacustris Morrison, and bar that name from use for 

the species as a whole (cf. Bull. Zool. Nomenclature, 

v. 4, p. 240, concl. 2, 1950). The name decepta is here 

applied to the species known as A. lustrica Pilsbry; 

lacustris Morrison and perlustrica Baker are available 

for the ecological variants distinguished by Baker.

Occurrence and material: Saw Rock Canyon local fauna, 

UMMZ 186155 (2).

Genus and species uncertain

Remarks. Two fragmentary specimens represent 

an amnicolid with a high, narrow spire, distinct from 

Marstonia crybetes. It may be Pyrgophorus or Fontigens.

Occurrence and material: Dixon local fauna. Dixon loc. 1, 

UMMZ 182194 (2).

Subclass PULMONATA 

Order BASOMMATOPHORA

Family CARYCHIIDAE 

Genus CARYCHITTM Miiller, 1774 

Carychium exiguum (Say), 1822

Carychium exiguum (Say). Pilsbry, 1948, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 2, p. 1052, fig. 561a, b, 562. 

Harry, 1952, Nautilus, v. 66, p. 5.

Carychium perexigutim Baker, 1938, Nautilus, v. 51, p. 128. 

Smith, 1940, Kansas Geol. Survey Bull. 34, p. 98. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

151, pi. 14, fig. j.

Leonard, 1957, Illinois Geol. Survey Report of Investigations 201, p. 10, pi. 1, fig. 1. 

Carychium perexlguum F. C. Baker. Hibbard, 1941, Kansas

Univ. Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, 

p. 408.

Distribution. "Newfoundland to Colorado, south to 

Mobile Bay, Alabama, and near Deming, southwestern 

New Mexico" (Pilsbry, 1948, p. 1052.)

Ecology. In northern Nebraska this species was 

found among wet leaves in seepage areas and beside 

a spring-fed brook.

Remarks. Examination of the type series (U1MNH 

P6776, P6777) and of a series of topotypes (UMMZ 

183026) shows that C. perexiguum is a synonym of 

C. exiguum. Baker thought it distinguished by "the 

shorter shell, heavier lip, and the upward bending 

columellar lamella." The series of topotypes, as well 

as the original measurements, shows a size range 

within that given by Pilsbry (1948, p. 1054) for 

C. exiguum. The thickening of the lip in the topotype series appears no different from that in C. exiguum. Only two of the types were dissected by Baker, 

and only one of these shows the principal columellar 

lamella adequately. The upward bend of this lamella 

referred to in the original description is a minor flare 

on the ventral side of the lamella within the body 

whorl. This feature is certainly well within the range
52 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

of variation of C. exiguum as figured by Pilsbry 

(1948).

Occurrence and material: Rexroad local fauna; Dixon local 

fauna (Frye and Leonard) ; Recent in northern Nebraska. 

Rexroad loc. 8, UMMZ 183026 (63), UIMNH P6776 (4), 

P6777 (3).

Carychium sp.

Carychitim perexiguum F. C. Baker. Taylor, 1954, Michigan 

Univ. Mus. Zool. Occ. Papers 557, p. 14 [not of Baker].

Remarks. The single Sand Draw specimen is surely 

not C. perexiguum (=(7. exiguum), and may be new. 

It is distinguished by the upper columellar fold, which 

is bent 90° toward the outer lip, ascends the parietal 

lip, and is strongly thickened. The fold thus appears 

as a large, transverse lamella protruding conspicuously 

into the aperture. Additional material is needed to 

determine the significance of this specimen.

Occurrence and material: Sand Draw local fauna. Sand 

Draw loc. 3, UMMZ 181126 (1).

Family LYMNAEIDAE 

Genus STAGNICOLA Jeffreys, 1830

Subgenus STAGNICOLA s. s. 

Stagnicola (s. s.) exilis (Lea), 1837

Galba exilis (Lea). Baker, 1911, Chicago Acad. Sci. Spec.

Pub. 3, p. 343, pi. 35, fig. 4; pi. 36, fig. 21-22; pi. 37,

fig. 1-11. 

Stagnicola exilis (Lea). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 226, pi. 14, fig. 7-11;

pi. 17, fig. 16. 

Stagnicola reflexa (Say). Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 95 [not of Say]. 

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265

[not of Say]. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408 [not of Say]. 

Lymnaea macella Leonard, 1952, Nautilus, v. 66, p. 40, pi. 5,

fig. J. 

Lymnaea macella Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Meade County

localities], pi. 14, fig. q. 

Lymnaea parexilis Leonard, 1952, Nautilus, v. 66, p. 41, pi. 5,

fig. K. 

Lymnaea parexilis Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Meade County

localities], pi. 14, fig. x. 

Lymnaea palustris (Miiller). Taylor, 1954, Michigan Univ.

Mus. Zool. Occ. Papers 557, p. 3 [in part: Rexroad local

fauna. Not of Miiller].

Distribution. "Ohio to Kansas, northward to northern Minnesota and northern Michigan1 ' (Baker, 1928, 

p. 227).

Ecology. "Exilis is an inhabitant of sloughs, ponds, 

and streams which dry up more or less during a portion of the year" (Baker, 1928, p. 227).

Remarks. Lymnaea macella Leonard and L. parexilis Leonard are obviously young and adult of the 

same species. This is readily demonstrable by breaking the larger L. parexilis into a smaller shell, which 

is then L. macella. The differentiae given for L. macella were the smaller size, heavier varix, and larger 

nuclear whorl. All are invalid. Varix and nuclear 

whorl are not different in the specimens examined 

personally; if it was meant that they are relatively 

different, the characters are a function of size. Large 

series from the Rexroad local fauna clearly show the 

intergradation of the two forms. Leonard may have 

reached a similar conclusion, unless a mislabelled illustration gives an erroneous implication. Plate 6, figure 

f (Frye, Leonard, and Swineford, 1956) is captioned 

Lymnaea macella Leonard; but this photograph is 

evidently the same illustration as those published by 

Leonard (1952a) and Frye and Leonard (1952) as 

Lymnaea parexilis.

The Pliocene populations from the Rexroad formation, distinguished by Leonard as distinct species, are 

referred to Stagnicola exilis on the basis of large University of Michigan series and of published information. The few specimens from Rexroad locality 3, 

the type locality of Lymnaea macella and L. parexilis, 

are inadequate to show the range of variation. Series 

from Rexroad locality 4c, from which Frye and Leonard (1952) recorded L. parexilis, agree well with 

Stagnicola exilis as described and figured by Baker 

(1911, 1928).

According to Leonard (1952, p. 42) "The shell of 

Lymnaea parexilis is similar in general form to that 

of L. exilis, but is much smaller with a relatively more 

elongate aperture, and more intricate sculpture." The 

only significant feature of these three is the relatively 

longer aperture. Recent Stagnicola exilis, and the 

University of Michigan fossil series examined, have 

a slightly smaller aperture than Lymnaea parexilis as 

figured and described by Leonard (1952a). This character is probably not of specific value; at any rate at 

least some occurrences of L. parexilis represent Stagnicola exilis.

Occurrence and material: Rexroad local fauna. Rexroad 

loc. 1, UMMZ 183053 (100) ; loc. 3, UMMZ 183027 (3) ; loc. 

4b, UMMZ 177599 (150), 181048 (125).

Stagnicola (s. s.) palustris (Miiller), 1774

Galba palustris (Miiller). Baker, 1911, Chicago Acad. Sci. 

Spec. Pub. 3, p. 298, pi. 26, fig. 17-37, pi. 33, fig. 1-25; 

pi. 34, fig. 20.

Distribution. "Circumboreal. Northern Asia and 

Europe. North America from the Atlantic to the
SYSTEMATIC DESCRIPTIONS 53

Pacific Ocean, and from Alaska south to New Mexico" 

(Baker, 1911, p. 307).

Ecology. In northern Nebraska it was found abundant in drainage ditches and ponds, temporary and 

perennial water bodies.

Occurrence: Recent in northern Nebraska.

Stagnicola (s. s.) reflexa (Say), 1821

Galba reflexa (Say). Baker, 1911, Chicago Acad. Sci. Spec.

Pub. 3, p. 332, pi. 30, fig. 30, 31; pi. 35, fig. 3, 5-22, pi.

36, fig. 1-11; pi. 18, fig. 10. 

Stagnicola reflexa (Say). Baker, 1928, Wisconsin Geol. Nat.

Hist. Survey Bull. 70, pt. 1, p. 221, pi. 14, fig. 1-6; pi.

17, fig. 15. 

Lymnaea macella Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151, in part [Kingman County

locality. Not of Leonard]. 

Lymnaea parexilis Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151, in part [Kingman County

locality. Not of Leonard].

Distribution. "Eastern Quebec west to Nebraska, 

Manitoba south to southern Illinois and southern Kansas" (Baker, 1928, p. 224).

Ecology. "The typical habitat of reflexa in northern Illinois and Wisconsin is in small pools or ponds 

which may become more or less dry in summer. All 

of the Wisconsin habitats have been in swales in 

woods or fields, none have been found in large streams 

or lakes" (Baker, 1928, p. 224).

Remarks. Large series from the Dixon local fauna 

show that the Stagnicola has the more convex whorls 

and impressed sutures of S. reflexa, rather than 8. 

exilis which was reported by Frye and Leonard.

Occurrence and material: Dixon local fauna. Dixon loc. 1, 

UMMZ 182197 (1500) ; loc. 2, UMMZ 191505 (250).

Stagnicola (s. s.) cf. S. reflexa (Say), 1821

Stagnioola cf. reflexa (Say). Baker, 1938, Nautilus, v. 51, p.

130.

Stagnioola, sp. Baker, 1938, Nautilus, v. 51, p. 131. 

Fossaria dalli grandis F. C. Baker. Baker, 1938, Nautilus, v.

51, p. 131 [in part. Not of Baker]. 

Stagnicola cf. reflexa. McGrew, 1944, Field Mus. Nat. Hist.

Geol. Ser. v. 9, p. 36. 

Stagnicola sp. McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser.,

v. 9, p. 36. 

Fossaria dalli grandis. McGrew, 1944, Field Mus. Nat. Hist.

Geol. Ser., v. 9, p. 36 [in part].

Remarks. Although Stagnicola is abundant in 

Sand Draw local fauna collections, almost all shells 

are immature or fragmentary. A few halfgrown 

shells from various localities suggest S. reflexa, but 

the identification is uncertain and there may even 

be more than one species represented.

Baker (1938) identified five juvenile specimens from 

the Sand Draw local fauna as Fossaria dalli grandis. 

Four (UIMNH P6T96, CNHM PE3442) are''Stagnicola cf. S. reflexa, the other (CNHM PE3443) Fossaria dalli.

Occurrence and material: Sand Draw local fauna. Sand 

Draw loc. 1, UMMZ 181238 (150) ; loc. 2, UMMZ 184172 (28) ; 

loc. 3, UMMZ 177330 (700) ; loc. 4, UMMZ 177313 (80) ; loc. 

5, CNHM PE3429 (18), PE3430 (19), UIMNH P6783 (1), 

P6784 (3), P6782 (14), UMMZ 181136 (2000), 181227 (6500); 

loc. 6, CNHM PE3441 (6), PE3442 (1), UIMNH P6795 (4), 

P6796 (3), UMMZ 177426 (150), 181210 (1000) ; loc. 7, UMMZ 

177227 (175).

Stagnicola (s. s.) sp.

Remarks. Immature and fragmentary shells from 

several localities represent a species of the Stagnicola 

palustris group, such as S. exilis or S. reflexa, but are 

inadequate for precise identification.

Occurence and material: Saw Rock Canyon, Bender, and 

Sanders local faunas. Saw Rock Canyon, UMMZ 183655 (3) ; 

Bender loc. la, UMMZ 184119 (1) ; loc. 2, UMMZ 184149 (14) ; 

Sanders loc. 1, UMMZ 182146 (5) ; loc. 2, UMMZ 184161 (2) ; 

loc. 3, UMMZ 182176 (4).

Subgenus HINKLEYIA Baker, 1928 

Stagnicola (Hinkleyia) caperata (Say), 1829

Stagnicola caperata (Say). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 260, pi. 18, fig. 43-47. 

Baker, 1938, Nautilus, v. 51, p. 130. 

Stagnicola caperata. McGrew, 1944, Field Mus. Nat. Hist.

Geol. Ser., v. 9, p. 36. 

Lymnaea caperata Say. Hibbard, 1954, Michigan Acad. Sci.

Papers, v. 39, p. 342. 

fLymnaea diminuta Leonard. Frye and Leonard, 1952,

Kansas Geol. Survey Bull. 99, p. 151 [in part: Kingman

County locality].

Distribution. "From Quebec and Massachusetts 

west to California; Yukon Territory and James Bay 

south to Maryland, Indiana, Colorado and California" 

(Baker, 1928, p. 263).

Ecology. "In the Mississippi Valley this species 

seems to almost invariably occupy intermittent streams 

or small pools, ponds and ditches which dry up in 

the summer. In Illinois it is usually found in association with Aplexa hypnorum and Sphaeriwn occidentale, either in small streams, pools or sloughs, or in 

spring pools in the woods which become completely 

dry in late spring and summer *** In these dry ponds 

living specimens may frequently be found by digging 

into the mud, leaves and other debris. In Wisconsin, 

caperata has been found almost invariably in small 

woodland pools which become dry in summer and 

fall, or in small streams which become wholly or 

partially dry" (Baker, 1928, p. 263). In northern 

Nebraska, S. caperata was found in similar, temporary
54 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

bodies of water, such as irrigation ditches, and also 

in the more perennial ponds of the Sand Hills. It was 

commonly associated with Stagnicola palustris, Promenetus umbilicatellus, and Aplexa hypnorum.

Remarks. The habitat of this species is one apparently available quite widely in the southern Plains 

region. It has never been recorded alive as far south 

as Kansas, however, and its usual common occurrence 

elsewhere and distinctive shape argue that its absence 

is reliable. The most reasonable explanation for the 

northern restriction of this species is that the hot summers to the south bar its southward dispersal.

Frye and Leonard (1952) reported Lymnaea diminuta (=8tagnicola bulimoides techella), but not 8. 

capera.ta, from the Dixon local fauna. Because the 

two species are somewhat similar, and because University of Michigan collections contain many 8. caperata 

but no 8. bulimoides techella, their reference may well 

be based on 8. caperata.

Hibbard's (1954) report of this species in the Rexroad local fauna is based upon the Bender local fauna 

specimens. None of the Rexroad local fauna localities 

studied carefully have yielded 8. caperata, but the 

species occurs at at least one other site represented in 

University of Michigan collections.

Occurrence and material: Buis Ranch, Bender, Sand Draw, 

Dixon, and Sanders local faunas; Recent in northern Nebraska. 

Buis Ranch, UMMZ 181113 (1) ; Bender loc. 1, UMMZ 177504 

(4) ; loc. la, UMMZ 184146 (17) ; loc. Ic, UMMZ 183011 (1) ; 

loc. 2, UMMZ 184148 (100) ; Sand Draw loc. 2, UMMZ 184171 

(37) ; loc. 3, UMMZ 181127 (30) ; loc. 4, UMMZ 177312 (12) ; 

loc. 5, CNHM PB3431 (50), UIMNH P6785 (18), UMMZ 

181135 (75), 181226 (150) : loc. 6, UMMZ 177424 (150), 181209 

(250) ; loc. 7, UMMZ 177228 (100) ; Dixon loc. 1, UMMZ 182- 

195 (24) ; loc. 2, UMMZ 191506 (41) ; Sanders loc. 1, UMMZ 

182226 (150) ; loc. 2, UMMZ 184159 (10) ; loc. 3, UMMZ 182174 

(43).

Submenus NASONIA Baker, 1928

Stagnicola (Nasonia) bulimoides techella (Haldeman), 1867

Galba bulimoides tecJiella (Haldeman). Baker, 1911, Chicago

Acad. Sci. Spec. Pub. 3, p. 214, pi. 27, fig. 30-35; pi. 28,

fig. 1-3, 8. 

Lymnaea diminuta Leonard, 1952, Nautilus, v. 66, p. 39, pi. 5,

fig. B. 

Lymnaea diminuta Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Meade County

localities], pi. 14, fig. s.

Distribution. Southwestern and south-central 

United States to central Mexico; from southern California through Utah, Colorado, southernmost Nebraska and Kansas to Missouri and Alabama; south 

to San Luis Potosi and Oaxaca.

Ecology. In northeastern Kansas "Lymnaea bulimoides techella is locally abundant in roadside ditches 

* * * throughout the broad terraces of the lower

Wakarusa valley. It may be found in ephemeral pools 

where it appears in large numbers for a few weeks 

in the early spring. Many of the adults die after 

the egg laying period and few adults are seen through 

the hot summer months; immature individuals presumably remain alive, buried in the mud" (Franzen 

and Leonard, 1943, p. 405).

Remarks. Lymnaea diminuta Leonard is a synonym of Stagnicola l)ulim,oides techella. It was compared by Leonard to F. humilis and others of the 

genus Fossaria, but its larger nuclear whorl, simple 

columella, and wide inner lip indicate that it belongs 

to the subgenus Nasonia. L. diminuta agrees with 8. 

bulimoides techella in having the significant characters 

of an acutely conic spire, obese body whorl, and 

broadly reflected inner lip (see Baker, 1911, p. 216).

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, and Sanders local faunas. Saw Rock 

Canyon, UMMZ 183656 (14) ; Red Corral, UMMZ 182993 

(175) ; Rexroad loc. 1, UMMZ 183052 (600) ; loc. 2, UMMZ 

183065 (2) ; Bender loc. la, UMMZ 184118 (32) ; loc. Ic, 

UMMZ 183012 (33) ; loc. 2, UMMZ 184147 (200) ; Sanders loc. 

1, UMMZ 182145 (75) ; loc. 2, UMMZ 182164 (1), 184160 (17) ; 

loc. 3, UMMZ 182175 (50).

Genus FOSSARIA Westerlund, 1885 

Fossaria obrussa (Say), 1825

Galbra obrussa (Say). Baker, 1911, Chicago Acad. Sci. Spec.

Pub. 3, p. 270, pi. 26, fig. 8-13, pi. 31, fig. 20-37. 

Fossaria obrussa (Say). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 293, pi. 16, fig. 14; pi.

18. fig. 14-24.

Distribution. "From the Atlantic to the Pacific 

oceans, and from Mackenzie Territory, Canada south 

to Arizona and northern Mexico" (Baker, 1928, p. 

296).

Ecology. "The normal habitat of this species is 

in small bodies of water, as creeks, ponds, sloughs, 

bays, and marshy spots along river banks. It is at 

home on sticks, stones, and any other debris that may 

be in the water or along its edge" (Baker, 1928, p. 

296). In northern Nebraska it was found on mud 

and logs just above water level, or in the mud of 

seepages by streams.

Occurrence and material: Sand Draw local fauna; Recent in 

northern Nebraska. Sand Draw loc. 3, UMMZ 181128 (54).

Fossaria dalli (Baker), 1906 

Plate 2, figures 6, 10-27

Galba dalli (Baker). Baker, 1911, Chicago Acad. Sci. Spec.

Pub. 3. p. 251, pi. 30, fig. 13-18. 

Fossaria dalli (F. C. Baker). Baker, 1928, Wisconsin Geol.

Nat. Hist. Survey Bull. 70, pt. 1, p. 288, pi. 16, fig. 11.
SYSTEMATIC DESCRIPTIONS 55

Fossaria dalli grandis F. C. Baker. Baker, 1938, Nautilus,

v. 51, p. 131 [in part]. 

Fossaria dalli grandis. McGrew, 1944, Field Mus. Nat. History

Geol. Ser., v. 9, p. 36. 

Lymnaea turritella Leonard, 1952, Nautilus, v. 66, p. 39, pi.

5, fig. 0. 

Lymnaea turritella Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151, pi. 14, fig. r. 

fLymnaea humilis modicella (Say). Frye and Leonard, 1952,

Kansas Geol. Survey Bull. 99, p. 151.

Distribution. "Ohio to Northern Michigan and 

Montana, south to Kansas and Arizona" (Baker, 1928, 

p. 288).

Ecology. "* * * inhabits wet, marshy places, generally out of the water, on sticks, stones, or muddy 

flats" (Baker, 1928, p. 289, 287). In northern Nebraska it was found in seepage areas, in the water 

or in wet leaves and debris at the water's edge.

Size-shape variation in Lymnaea turritella topotypes is as follows:

Number of whorls

3%

Number of specimens.

Length:

Mean________ ____________

Standard deviation, _ _

Width:

Mean.___________________

Standard deviation.- ______

Length aperture:

Mean.____ _______________

Standard deviation.. _

Width aperture:

Mean. ___________________

Standard deviation.- ______

Width to length ratio:

Mean__ __________________

Standard deviation._______

Length aperture to length ratio: 

Mean.. __________________

Standard deviation,. ______

3. 44 ± 0.

.28 ± .

1. 94 

.12

1. 60

. 14

± 

±

± 

±

.99 ±

. 087 ±

. 566 ± 

. 014 ±

. 465 ± 

. 0081 ±

066

047

028

020

033

023

021

015

0033

0023

0019

0014

3. 79 ± 0.

.27 ± .

2. 09 ± . 

. 16 ± .

1. 73 ± . 

. 13 ± .

1. 03 ± . 

.081 ± .

. 550 ± . 

. 013 ± .

. 457 ± . 

. 0072± .

059

042

035

025

028

020

018

013

0028

002

0016

0011

4.27 

.31

2. 27 

.16

1. 89 

. 14

±0.

± .

± 

±

± 

±

1. 12 ±

. 078 ±

. 532 ± 

. 0093 ±

. 443 ± 

. 012 ±

078

055

040

028

035

025

019

014

0023

0016

003

0021

4. 60 

. 70

2. 31

. 28

1. 92 

. 30

1. 14 

. 17

. 504

. 022

. 416

. 015

±0. 25 

± . 018

± . 100 

± . 070

± . 11 

± . 075

± . 060 

± . 043

± . 0078 

± . 0055

± . 0053 

± . 0038

Series from the Saw Rock Canyon, Bender, Sand 

Draw, Berends, and Jinglebob local faunas are all 

closely similar in having sculpture of coarse, irregular 

growth lines and small apertures. A large series from 

Rexroad locality 4b differs somewhat in having a 

greater range of variation. Many shells matching 

those from the other faunas may be found, but many 

others cannot be so matched. These latter specimens 

are slightly smoother, with longer apertures; some 

attain both greater size and a larger number of whorls 

than occur in other samples. Such large specimens 

may be referable to Fossaria parva (Lea) (Baker, 

1911, p. 243) or to F. parva sterkii (Baker) (Baker, 

1911, p. 248). The Rexroad locality 4b sample provides no evidence that more than one population is 

represented, however. This sample may be F. parva, 

rather than F. dalli as here considered, or F. dalli may 

be a synonym of F. parva. These questions involve 

revision of a number of Recent species, a study outside the scope of this report. The Rexroad locality 

4b material is referred to F. dalli because what is 

probably a single population contains numerous individuals morphologically indistinguishable from other 

samples referable to F. dalli.

Small series from the Dixon and Sanders local faunas, and other Rexroad local fauna localities, are 

inadequate to show similarities closer either to the 

Rexroad 4b sample or to other samples.

Other late Pleistocene material surely representing 

what is called here Fossaria dalli, and which agrees 

closely with the Saw Rock Canyon, Sand Draw, Berends, and Jinglebob material is in the U. S. National 

Museum, as follows: 570570, marl, Castalia, Erie 

County, Ohio; identified by F. C. Baker as Fossaria 

dalli grandis. 570542, loess, Fulton County, 111., identified by F. C. Baker as Fossaria parva tazewelliana. 

570573, bed of drained pond, 2 miles southeast of 

Northport, Wash.; identified by F. C. Baker as Fossaria perplexa. F. C. Baker (1938) identified five 

juvenile specimens as Fossaria dalli grandis. One 

(CNHM PE 3443) is F. dalli, the others (CNHM PE 

3442, UIMNH P6796) /Stagnicola palustris.

Frye and Leonard (1952) reported Lymnaea hwnili* 

modicella from some localities represented by University of Michigan collections. The form has not been 

recognized in this material. The reference may be 

based upon short-spired specimens of F. dalli, however.
56 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Remarks. \Lymnaea turritella Leonard was originally distinguished from F. dalli by its somewhat 

larger size and slenderer form. Comparison of a 

large series of topotoypes with other large series of 

fossils, and with Recent material in the U. S. National 

Museum identified by F. C. Baker, shows that these 

differences are not constant. The description and 

previous illustrations of L. turritella are based on 

extremely long, narrow specimens. The accompanying table, as well as the illustrations, shows variation 

in shape in the Saw Rock Canyon fauna sample. 

Comparison of these measurements with those given 

by Baker reveals further that there is no significant 

difference in size.

Occurrence and material: Saw Rock Canyon, Rexroad, Bender, Sand Draw, Dixon, and Sanders local faunas; Recent in 

northern Nebraska. Saw Rock Canyon, UMMZ 173595 (12), 

177555 (250) ; Rexroad loc. 1, UMMZ 183054 (1) ; loc. 2, 

UMMZ 183066 (4) ; loc. 3, UMMZ 183028 (4) ; loc. 4b, UMMZ 

177598 (200), 181047 (125); Bender loc. Ib, UMMZ 184134 

(9) ; loc. Ic, UMMZ 183013 (1) ; loc. 2, UMMZ 184150 (3) ; 

Sand Draw loc. 2, UMMZ 184187 (6) ; loc. 6, CNHM PE3443 

(1), UMMZ 177425 (7); Dixon loc. 1, UMMZ 182198 (34); 

loc. 2, UMMZ 191507 (2) ; Sanders loc. 3, UMMZ 182177 (4).

Genus BULIMNEA Haldeman, 1841 

Bulimnea megasoma (Say), 1824

Bulinmea megasoma (Say). Baker, 1911, Chicago Acad. Sci.

Spec. Pub. 3, p. 184, pi. 25, fig. 1-6. 

Baker, 1928, Wisconsin Geol. Nat. Hist. Survey Bull. 70,

pt. 1, p. 277, pi. 8, fig. 19-23; pi. 17, fig. 31, 35. 

Lymnaea cf. stagnalis jugularis Say. Baker, 1938, Nautilus,

v. 51, p. 131.

Stagnicola sp. Baker, 1988, Nautilus, v. 51, p. 131. 

Lymnaea cf. stagnalis jugularis. McGrew, 1944, Field Mus.

Nat. History Geol. Ser., v. 9, p. 36. 

Stagnicola sp. McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser.,

v. 9, p. 36 [in part]. 

Lymnaea megasoma Say. Taylor, 1954, Michigan Univ. Mus.

Zool. Occ. Papers 557, p. 14.

Distribution. "Northern New England (Vermont) 

west to Minnesota, Iowa, and Manitoba; northern 

Ohio (latitude 41°) northward to about latitude 57° 

in British America" (Baker, 1928, p. 282).

Ecology. "Megasotna is usually an inhabitant of 

small, quiet bodies of water or swamps" (Baker, 1928, 

p. 281).

Remarks. The material which Baker (1938) reported from the Sand Draw local fauna is fragmentary, but of the species known from this fauna can 

be only B. megasoma.

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 1, UMMZ 181237 (21) ; loc. 2, UMMZ 

184186 (1) ; loc. 3, UMMZ 177331 (100) ; loc. 4, UMMZ 177314

(4); loc. 6, CNHM PE3440 (1), UIMNH P6794 (2), P6798 

(fragments) ; Dixon loc. 1, UMMZ 182196 (60) ; loc. 2, UMMZ 

191508 (15).

Family PLANORBIDAE

Subfamily PLANORBINAE 

Genus ANISTTS Studer, 1820

Submenus ANISUS s. s. 

Anisus (s. s.) pattersoni (Baker), 1938

Gyraulus pattersoni Baker, 1938, Nautilus, v. 51, p. 129.

Gyraulus pattersoni. McGrew, 1944, Field Mus. Nat. History 

Geol. Ser., v. 9, p. 36.

Gyraulus pattersoni Baker. Leonard, 1950, Kansas Univ.

Paleont. Contr. 8, p. 20, pi. 3, fig. I. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

158, pi. 15, fig. g.

Leonard, 1957, Illinois Geol. Survey Report of Investigations 201, p. 12, pi. 2, fig. 4-6.

Anisus pattersoni (Baker). Taylor, 1958, Jour. Paleont., v. 

32, p. 1149.

Types. Holotype CNHM, Sand Draw loc. 5. Paratypes CNHM (2), UIMNH P7455 (4), ANSP 169948

(2).

Diagnosis. An Anisus of small size (less than 5 

mm diameter), with 5-6 whorls, nearly plane on 

both sides, subangular at junction of left side and 

periphery of whorls.

Description. Shell small, discoidal, presumably 

ultradextral, nearly plane on both sides; whorls 5-6, 

flattened on the left side, subangulate at junction of 

left side with periphery, rounded on periphery and 

right side, very slowly and regularly increasing; 

suture well impressed; aperture subquadrate, left side 

flattened to arcuate, periphery gently rounded, right 

side strongly rounded; lip sometimes thickened 

within; sculpture of numerous fine, irregular growth 

lines and weak spiral striation; embryonic shell of 

about one-half whorl, spirally striate only.

Measurements. See table of comparative measurements below.

Distribution. Pliocene in southwestern Idaho, 

northern Utah, western Wyoming; early Pleistocene 

in southwestern Idaho, Nebraska, and Kansas; middle 

Pleistocene in the central Great Plains; late Pleistocene, Ohio.

Ecology. Known only from inference, since the 

species is extinct. Its association with fossils which 

represent living species suggests it lived in shallow, 

quiet waters, in the backwaters along streams or in 

semipermanent ponds and sloughs.

Remarks. Anisus pattersoni (F. C. Baker) seems 

most nearly related to A. rotundatus (Poiret); but 

insufficient data for adequate comparison are available
SYSTEMATIC DESCRIPTIONS 57

on A. perezi (Dupuy), to which it may be closer. A. 

pattersoni is smaller than A. rotundatus (see measurements), with fewer whorls than either A. rotundatus 

or A. perezi. No specimens of A. pattersoni with over 

51/2 whorls have been seen, whereas Germain (1931, 

p. 530-531) ascribes six or seven to the European 

species. The left side of the whorls of A. pattersoni 

is more flattened than the right side, so that there is 

an obtuse angle of the aperture above, but only a 

curve below. In most specimens examined, the left 

side is broader than the right. The largest specimens, 

however, lose the subangulation on the last whorl, 

and thus approach A. rotundatus. Like A. rotundatus

and A. perezi, A. pattersoni possesses an internal 

thickening of the lip. Formation of this callus is not 

restricted to mature individuals; most specimens show 

several such calluses, the number depending on the 

individual's age.

Differences in size between the two species are shown 

by the following measurements (in millimeters). Catalogue numbers are those of the University of Michigan 

Museum of Zoology, as follows: 177231, Sand Draw 

local fauna, locality 7, Brown County, Nebr., 177290, 

probably Cudahy local fauna, W1/^ sec. 35, T. 33 S., 

E. 32 W., Seward County, Kans.; 90458, Eecent, 

Menonville, France.

Differences in the two species are as follows:

Anisus rotundatus (Poiret)

Number of 

whorls

5

4!4

4%

5Y2

5l/4

4^ 

5y2

5y2

5

4K

4/2

Diameter

3. 7

3. 1 

2. 9 

4. 6 

4. 2 

3. 2 

6. 3

6. 3 

4. 9 

3. 9 

4. 2

Height

0 8

7 

7 

1 2 

8 

7 

1 3

1 3 

9 

9 

1 1

Diameter of 

aperture

0 6

6 

5 

8 

8 

6 

1 0

1 2 

9

7 

9

Height of 

aperture

0 8

7 

7 

9 

8 

7 

1 3

1 3 

9 

9 

1 1

Catalog

No.

177231

177290 

90458

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 2, USGS 19090-1 (6) ; loc. 3, UMMZ 

177332 (150) ; loc. 4, UMMZ 177316 (6) ; loc. 5, CNHM (3), 

UIMNH P7455 (4), ANSP 169948 (2); loc. 6, UMMZ 177427 

(48), 181211 (500) ; loc. 7, UMMZ 177231 (75) ; Dixon loc. 1, 

UMMZ 182199 (26).

Genus GYRAULUS Charpentier, 1837 

Gyraulus circumstriatus (Tryon), 1866

Gyraulus circumstariatus (Tryon). Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 1, p. 378, text fig. 

162.

Distribution. Gyraulus circumstriatus is found in 

a broad belt across central North America, in southern Canada and the northern United States between 

the Atlantic and Pacific oceans, southward in the 

Rocky Mountains to northern Arizona.

Ecology. Gyraulus circumstriatus is characteristic 

of small, seasonal water bodies, such as woods pools, 

marshes, ponds on flood plains or prairie ponds. In 

northern Nebraska it was found in seepages beside 

streams, and in temporary Sand Hills ponds.

Occurrence. Recent in northern Nebraska.

508945 O 60 6

Gyraulus deflectus (Say), 1824

Gyraulus deflectus (Say). Baker, 1928, Wisconsin Geol. Nat. 

Hist. Survey Bull. 70, pt. 1, p. 370, pi. 23, fig. 15-21.

Distribution. British Columbia to Nova Scotia and 

Mackenzie District; south in the Eocky Mountains to 

Montana and Idaho; eastern South Dakota and Iowa 

to the Atlantic Ocean; south in the Atantic Coastal 

Plain to the Potomac Eiver, Virginia.

Ecology. "A species of quiet bodies of water" (F. 

C. Baker, 1928, p. 370). In northern Nebraska this 

species was found in a spring-fed pond with a temperature of 15 °C. The snails were crawling on aquatic 

plants, largely Ceratophyllum, Elodea, and algae, near 

the edge of the pond.

Remarks. In north-central Nebraska this species is 

about 200 miles south of its previously recorded range. 

Its existence in the area is considered possible because 

of the insulating effect of the cool spring water. 

Essentially a northern species, it is probably able to 

live here because the pond is warmed little if at all 

during the summer hot spells. Other permanent ponds, 

apparently similar except that they lack spring 

sources, were examined without finding this species.

Occurrence: Recent in northern Nebraska.
58 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Gyraulus parvus (Say), 1817 

Plate 4, figs. 1-13, 17, 18

Gyraulus parvus (Say). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 374, pi. 23, fig. 27-31,

39, text fig. 162. 

Gyraulus altissimus (F. C. Baker). Baker, 1938, Nautilus,

v. 51, p. 130-131 [not of Baker]. 

Gyraulus altissimus. McGrew, 1944, Field Mus. Nat. History

Geol. Ser., v. 9, p. 36. 

Gyraulus cnaulus Leonard, 1952, Nautilus, v. 66, p. 43, pi. 5,

fig. G. H, I. 

Gyraulus enaiilus Leonard. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151, pi. 14, fig. u.

Distribution. North America, from Alaska and 

northern Canada to Cuba and from the Atlantic to 

the Pacific coast. Perhaps also in northern Eurasia.

Ecology. "Usually in quiet bodies of water, often 

of small size. * * * parvus is partial to a habitat 

which has rather thick vegetation. This species is 

more often found in vegetation than in any other 

situation" (Baker, 1928, p. 376-377). In northern 

Nebraska it was found in. permanent and temporary 

quiet water bodies: in permanent and temporary 

ponds, in temporary water in ditches, and in quiet 

spots at the edge of a stream.

Remarks. Gyraulus altissimus Baker (1919), described from upper Pleistocene deposits in Illinois, 

was reported from the Sand Draw local fauna. The 

material is G. parvus rather than G. altissimus. The 

shells from the Sand Draw local fauna are characterized by a lateral flattening of the whorls, relatively 

close coiling, and no deflection of the body whorl. G. 

altissimus also has closely coiled whorls, but the body 

whorl is deflected and the flattening is at an angle of 

about 45 degrees to the axis of the coil.

Gyraulus enaulus Leonard was not compared to G. 

parvus in the original description, but is referable to 

that species as represented in University of Michigan 

Museum of Zoology and U. S. National Museum collections.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Sand Draw, Dixon, and Sanders local faunas; Recent in 

northern Nebraska; Rexroad local fauna (Frye and Leonard). 

Saw Rock Canyon, UMMZ 173591 (125), 177556 (1200), uncat., 

USGS 19089-1 (200) ; Red Corral, UMMZ 182994 (200) ; Sand 

Draw loc. 1, UMMZ 181239 (250) ; loc. 2, USGS 19090-2 (100) ; 

loc. 3, UMMZ 177333 (2250) ; loc. 4, UMMZ 177317 (300) ; loc. 

5, UMMZ 181228 (125), 177219 (24), CNHM PE3436 (175), 

UIMNH P6790 (41) ; loc. 6, UMMZ 177428 (200), 181212 (75), 

CNHM PE3444 (46), UIMNH P6797 (15) ; loc. 7, UMMZ 177- 

232 (150) ; Dixon loc. 1, UMMZ 182200 (6500), uncat.; loc. 2, 

UMMZ 191509 (300) ; Sanders loc. 1, UMMZ 182147 (5) ; loc. 

3, UMMZ 182178 (1).

Genus ARMIGER Hartmann, 1840 

Armiger crista (Linnaeus), 1758

Gyraulus crista (Linn.). Baker, 1928, Wisconsin Geol. Nat. 

History Survey Bull. 70, pt. 1, p. 385, text fig. 164.

Distribution. Holarctic; in North America, 

north of about 41°, but south of this latitude on the 

Pacific Coast to San Mateo County, Calif., and southward in central Utah.

Ecology. Kenk (1949, p. 53) found A. crista was 

common in a temporary pond in southern Michigan. 

"Armiger crista (Linnaeus) was taken in Pond 1 from 

March to June. Numerous individuals appeared also 

in the culture of a soil sample from the bottom of the 

pond, prepared in October. No specimens were collected from December to February. The animals 

obviously estivated buried in the dry mud and, after 

the pond had filled, remained inactive in the soil until 

the latter part of the winter." In northern Nebraska 

a single specimen was found, under culvert fill stones 

at the edge of a stream. Ecologic information on this 

species in America is scanty.

Occurrence: Recent in northern Nebraska.

Subfamily HELISOMATINAE 

Genus HELISOMA Swainson, 1840

Submenus HELISOMA s. s. 

Helisoma (s. s.) anceps (Menke), 1830

Helisoma antrosa (Conrad). Baker, 1928, Wisconsin Geol. 

Nat. History Survey Bull. 70, pt. 1, p. 317, pi. 19, fig. 

8-15. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151. 

Helisoma anceps (Menke). Pilsbry, 1934, Acad. Nat. Sci.

Philadelphia Proc., v. 86, p. 45.

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557, 

p. 14.

Distribution. Oregon to Maine, southward to western Mexico and Alabama.

Ecology. "* * * primarily a river and creek species, 

not living in the large lakes" (Baker, 1928, p. 319). 

In northern Nebraska it was found in a spring-fed 

pond with a temperature of 15 °C.

Remarks. Pilsbry (1934) considered the name antrosa as a junior synonym of anceps. The name anceps 

has been used by subsequent writers except Leonard 

(1950, p. 16, and later papers). Pilsbry (1950, p. 68) 

discussed the reasons for acceptance of anceps.

The single Recent occurrence in a summer-cool pond 

together with Valvata and Gyraulus deflectus might 

be interpreted to mean that its existence in the area
SYSTEMATIC DESCRIPTIONS 59

is dependent upon a temperature factor. Considering 

its wide distribution and the number of High Plains 

localities given by Walker (1909), I think the controlling factor is permanent water.

The material reported by Frye and Leonard (1952, 

p. 151) from the SW^4 sec. 22, T. 33 S., R. 29 W., 

Meade County, almost certainly came from Rexroad 

locality 3 rather than Bender locality 1. Habitat 

inferences from Bender locality 1 species suggest only 

temporary bodies of water. Rexroad locality 3 had 

the permanent water which Helisoma anceps requires.

Occurrence and material: Sand Draw and Dixon local 

faunas; Saw Rock Canyon and Rexroad local faunas (Frye 

and Leonard) ; Recent in northern Nebraska. Sand Draw loc. 

1, UMMZ 181240 (65) ; loc. 2, UMMZ 184173 (5) ; loc. 3, UMMZ 

177334 (250) ; loc. 6, UMMZ 177429 (1) ; Dixon loc. 1, UMMZ 

182201 (100) ; loc. 2, UMMZ 191510 (1).

Subgenus PIEROSOMA Ball, 1905 

Helisoma (Pierosoma) trivolvis (Say), 1817

Helisoma trivolvis (Say). Baker, 1928, Wisconsin Geol. Nat. 

History Survey Bull. 70, pt. 1, p. 330, pi. 20, fig. 1-13, 

22, 23.

Distribution. "Atlantic Coast and Mississippi 

River drainages, northward to Arctic British America and Alaska and southward to Tennessee and Missouri. The southern distribution is not clear owing 

to mixing with related species" (Baker, 1928, p. 332).

Ecology. "Typical trivolvis is always an inhabitant 

of quiet, more or less stagnant water" (Baker, 1928, p. 

332). In northern Nebraska it was found in permanent ponds almost exclusively. The exception was a 

single specimen found in a drainage ditch where it 

might have come from a permanent pond.

Occurrence and material: Dixon local fauna; Recent in 

northern Nebraska. Dixon loc. 1, UMMZ 182202 (2, + fragments) ; loc. 2, UMMZ 191511 (72).

Subfamily PLANORBTILINAE

Genus PLANORBULA Haldeman, 1842

Planorbula armigera (Say), 1818

Planorbula armigera (Say). Baker, 1928, Wisconsin Geol.

Nat. Hist. Survey Bull. 70, pt. 1, p. 355, pi. 8, fig. 27-30. 

Planorbnla sp. Taylor, 1954, Michigan Univ. Mus. Zool. Occ.

Papers 557, p. 15.

Distribution. "New England west to Nebraska, 

south to Georgia and Louisiana, north to Great Slave 

Lake." (F. C. Baker, 1928, p. 359.)

Ecology. "* * * largely a species of swales or of 

small and stagnant bodies of water." (F. C. Baker, 

1928,. p. 358). In northern Nebraska it was found 

in a small oxbow lake in the Niobrara River valley.

Remarks. Sand Draw local fauna material consists

chiefly of fragments and young specimens. None 

shows the apertural dentition, but all agree well in 

size and shape with P. armigera.

The series from Dixon locality 2 agrees well in size, 

shape, and lamellae with Recent specimens of P. armigera. The three immature specimens from Dixon 

locality 1 are referred to the same species, since they 

show no differences from the locality 2 series.

The single Recent Nebraska specimen differs from 

P. armigera as figured and described by Baker (1928) 

in having a lesser axial height, five whorls, and a more 

open spire-pit. It differs from P. christyi (Dall) as 

figured by Baker (1945, pi. 119, figs. 13-15) in having 

fewer whorls. The specimen probably represents normal variation within P. armigera.

Occurrence and material: Sand Draw and Dixon local 

faunas; Recent in northern Nebraska. Sand Draw loc. 1, 

UMMZ 181241 (44) ; loc. 4, UMMZ 177318 (14) ; Dixon loc. 1, 

UMMZ 182203 (3) ; loc. 2, UMMZ 191512 (200).

Genus PROMENETUS Baker, 1935

Subgenus PROMENETTIS s. s. 

Promenetus (s. s.) exacuous (Say), 1821

Menetus exacuous (Say). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 361, pi. 23, fig. 1-5. 

Promenetus exactions exacuous (Say). Baker, 1945, Molluscan

family Planorbidae, p. 182.

Distribution. North America north of about 39°; 

south in the Colorado Plateau and Rocky Mountains 

to New Mexico; south along the Atlantic Coastal Plain 

to North Carolina; an isolated occurrence in cool 

springs, Meade County, Kans.

Ecology. Promenetus exacuous is found in shallow, 

perennial or subpernianent, quiet water bodies, such as 

ponds, ox-bow lakes, marshes, and sloughs or backwaters along streams. It is usually on the submerged 

vegetation in such habitats. The isolated occurrence in 

Meade County, Kans., can be explained by the summercool habitat furnished by artesian water in which this 

snail lives. In northern Nebraska it was found in 

permanent or nearly permanent quiet water.

Occurrence: Recent in northern Nebraska.

Promenetus (s. s.) kansasensis (Baker), 1938 

Plate 3, figures 7, 8, 12-30

Menetus kansasensis Baker, 1938, Nautilus, v. 51, p. 129. 

Menetus kansasensis F. C. Baker. Baker, 1938, Nautilus, v.

51, p. 130-131.

Hibbard, 1941, Kansas Univ. Sci. Bull., v. 27, p. 95. 

Hibbard. 1941. Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408.

Baker, 1945, Molluscan family Planorbidae, p. 516, pi. 140, 

fig. 26-29.
60 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Menetus kansasensis Baker. Smith, 1940, Kansas Geol. Survey Bull. 34, p. 408. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99. p.

151, pi. 14, fig. t.

Leonard, 1957, Illinois Geol. Survey Report of Investigations 201, p. 13, pi. 2, fig. 1-3.

Menetus kansasensis. McGrew, 1944, Field Mus. Nat. History 

Geol. Ser., v. 9, p. 36.

Types. Holotype TJIMNH P6778, Kexroad loc. 3. 

Paratypes UIMNH P6778 (3), uncataloged (20), 

ANSP 169884 (not found).

Diagnosis. Similar in shape and size to Promenetus 

exacuous, but with sculpture of numerous irregularly 

spaced riblets.

Distribution. Late Pliocene to late Pleistocene 

(Sangamon) in the Great Plains.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Sand Draw, Dixon, and Sanders local faunas. Saw 

Rock Canyon, UMMZ 173588 (75), 177557 (2500), uncat., USGS 

19089-2 (75) ; Red Corral, UMMZ 182995 (8) ; Rexroad loc. 

1, UMMZ 183055 (1) ; loc. 3, UIMNH P6778 (4), uncat. (20), 

UMMZ 183029 (12) ; Sand Draw loc. 1, UMMZ 181242 (100) ; 

loc. 2, USGS 19090-3 (48) ; loc. 3, UMMZ 177335 (1500) ; loc. 

4, UMMZ 177319 (54) : loc. 5, CNHM PE 3434 (30), UIMNH

P6788 (17), UMMZ 177217 (3000), 181229 (3500); loc. 6, 

UIMNH P6798 (6), UMMZ 177430 (100), 181213 (600); loc. 

7, UMMZ 177229 (125) ; Dixon loc. 1, UMMZ 182204 (1000) ; 

loc. 2, UMMZ 191513 (150) ; Sanders loc. 2, UMMZ 182165

(2) ; loc. 3, UMMZ 182179 (1).

Subgenus PHREATOMENETTTS 8 Taylor, n. subg.

Type. Promenetus umbilicatellus (Cockerell). 

Diagnosis. Snails fitting the definition of Promenetus (see Baker, 1945, p. 178-182), but distinguished 

conchologically as follows: shell broadly rounded 

peripherally; sides of whorls convex to slightly flattened; left side strongly convex or subangular at edge 

of spire-pit; right side sometimes strongly convex or 

subangular near the suture.

Referred species. None of the species besides the 

type is known anatomically; others listed below are assigned on shell characters. 

Promenetus umUlicatellus (Cockerell), 1887. Type.

Northern North America. 

earns (Pilsbry and Ferriss), 1906.

Southwestern Texas. 

circumlineatus (Shuttleworth), 1854. 

Central America to the Lesser Antilles. 

(Including Planorbis santacruzensis Germain, 

1923; may be a synonym of Plcm,orbis aeruginosus 

Morelet, 1851).

* Gr. phrear, -atos, n., well or reservoir; in reference to the steepsided, well-nke spire-pit of the species referred to the group.

Promenetus (Phreatomenetus) umbilicatellus (Cockerell), 1887

Gyraulus umbilicatellus (Cockerell). Baker, 1928, Wisconsin 

Geol. Nat. History Surrey Bull. 70, pt. 1, p. 383, pi. 22, 

fig. 18-21.

Menetus unibilicatettus (Cockerell). Baker, 1938, Nautilus, v. 

51, p. 130.

Gyraulus unibllicatellus. McGrew, 1944, Field Mus. Nat. History Geol. Ser., v. 9, p. 36.

Promenetus timUlicatellus (Cockerell). Baker, 1945, Molluscan family Planorbidae, p. 182, pi. 123, fig. 34-36.

Promenetus Wancoensis Leonard, 1952, Nautilus, v. 66, p. 42,

pi. 5, fig. D-F.

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, 

p. 151, pi. 14, fig. o.

Distribution. North America north of about lat. 

41° from Nevada and Alaska east and southeast to 

western New York; south in the Rocky Mountains to 

southern Colorado; an isolated occurrence in the Ozark 

Mountains, northeastern Oklahoma.

Ecology. "All specimens in Wisconsin have been 

found in swales11 (Baker, 1928, p. 384). In northern 

Nebraska it was found common in drainage ditches 

and temporary ponds.

Remarks. Promenetus blancoensis appears to be a 

synonym of P. umbilicatellus, easily falling within the 

range of variation of the latter. The differentiae given 

were the smaller size, lesser number of whorls (always 

less than 4), nonstriate nucleus, absence of spiral 

sculpture, and depressed spire. The great majority of 

Recent specimens examined have less than 4 whorls 

and have a diameter of approximately 4 millimeters, 

thus agreeing with the measurements of P. l)lancoensis. 

To the "nonstriate nucleus 1 ' not much significance 

should be atached. All other characters are in agreement with those of P. umbilicatellus, and the nuclear 

striation might easily be lost through wear. The apparent absence of spiral sculpture does not differentiate 

the form from P. umbilicatellus, for this character is 

often very difficult to observe in unworn Recent specimens, and in fossils faint spiral sculpture might have 

been lost or easily overlooked. The depressed spire is 

also a character which may be found in Recent specimens, although it is not common. Material from the 

Saw Rock Canyon local fauna, and from Rexroad local 

fauna localities 1 and 3 confirms the synonymization. 

The specimens agree well in size and form with P. umbilicatellux, and less worn individuals show the spiral 

striation and nuclear sculpture typical of that species.

The material reported by Frye and Leonard (1952, 

p. 151) from SW4 sec, 22, T. 33 S., R. 29 W., Meade 

County, is probably from Bender locality 1 rather than 

Rexroad locality 3. University of Michigan collections
SYSTEMATIC DESCRIPTIONS 61

contain numerous specimens from the Bender locality, 

but none from the Rexroad locality.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, Sand Draw, Dixon, and Sanders local 

faunas; Recent in northern Nebraska. Saw Rock Canyon, 

UMMZ 177515 (50), 177558 (600), USGS 19089-3 (75); Red 

Corral, UMMZ 182996 (150) ; Rexroad loc. 1, UMMZ 183056 

(1500) ; Bender loc. 1, UMMZ 177505 (1) ; loc. la, UMMZ 

184120 (30) ; loc. Ic, UMMZ 183014 (11) ; loc. 2, UMMZ 184151 

(47) ; Sand Draw loc. 1, UMMZ 181243 (6) ; loc. 2, UMMZ 

184174 (40) ; loc. 3, UMMZ 177336 (225) ; loc. 4, UMMZ 177320 

(150); loc. 5, CNHM PE3435 (75), UIMNH P6789 (36), 

UMMZ 177218 (125), 181230 (800) ; loc. 6 UMMZ 177431 (300), 

181214 (6000) ; loc. 7, UMMZ 177230 (250) ; Dixon loc. 1, 

UMMZ 182205 (9) ; loc. 2, UMMZ 191514 (6) ; Sanders loc. 

1, UMMZ 182148 (300); loc. 2, UMMZ 182166 (2), 184162 

(31) ; loc. 3, UMMZ 182180 (20).

Family AWCYLIDAE

Subfamily ACROLOXINAE

Genus ACROLOXTTS Beck, 1837

Acroloxus coloradensis (Henderson), 1930

Plate 1, figures 1-4

Ancyltis hendersoni Walker, 1925, Michigan Univ. Mus. Zool

Occ. Papers 165, p. 1. 

Mozley, 1926, Nautilus, v. 40, p. 56.

Ancylus coloradensis Henderson, 1930, Nautilus, v. 44, p. 31. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557, 

p. 15.

Distribution. Known from only two areas in the 

Rocky Mountains in Colorado and Alberta.

Ecology. In high mountain lakes. "* * * only 

clinging to stones, etc., in very tiny inlets from the 

lake, where they were well protected from the waves, 

but in clear lake water, not in swampy ground" 

(Walker, 1925, p. 3).

Remarks. The discovery of this rare and littleknown species in the Pleistocene of the Great Plains is 

remarkable. The specimens are closely similar to a 

series of paratypes, however, and also to specimens 

collected in Alberta by Mozley.

International Commission on Zoological Nomenclature Opinion 363 (1955) fixes the type oiAncylus as 

A. fluviatilis Miiller, 1774, and of Acroloxus as Patella 

lacustris Linnaeus, 1758, as interpreted by Miiller, 1774. 

Ancylus coloradensis Henderson is accordingly to be 

called Acroloxus coloradensis (Henderson).

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 3, UMMZ 181129 (28) ; Dixon loc. 1, 

UMMZ 182209 (1) ; loc. 2, UMMZ 191515 (1).

Subfamily FERRISSIINAE

Genus FERRISSIA Walker, 1903

Ferrissia rivularis (Say), 1819

Ferrissia rivularis (Say). Baker, 1928, Wisconsin Geol. Nat. 

History Survey Bull. 70, pt. 1, p. 398, pi. 24, fig. 16-18.

Hibbard, 1941, Kansas Univ. Sci. Bull., v. 27, p. 95. 

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408.

Frye and Leonard, 1952, p. 151. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 15. 

Ferrissia rivularis"? (Say). Hibbard, 1954, Michigan Acad.

Sci. Papers, v. 39, p. 343.

Distribution. "Massachusetts west to Nebraska, 

Ohio nortlrward to Wisconsin and Michigan" (F. C. 

Baker, 1928, p. 399).

Ecology. "Found on stones in streams" (Robertson 

and Blakeslee, 1948, p. 72).

Occurrence and material: Saw Rock Canyon, Rexroad, Sand 

Draw, and Dixon local faunas; Buis Ranch local fauna? 

Buis Ranch, UMMZ 181114 (1, fragmentary) ; Saw Rock 

Canyon, UMMZ 173594 (24), 177559 (350), USGS 19089-9 

(100) ; Red Corral, UMMZ 182997 (5) ; Rexroad loc. 3, UMMZ 

183031 (8) ; Sand Draw loc. 1, UMMZ 181245 (57) ; loc. 2, 

UMMZ 184175 (1) ; loc. 3, UMMZ 181111 (250) ; Dixon loc. 1, 

UMMZ 182210 (56).

Ferrissia parallela (Haldeman), 1841

Ferrissia parallela (Haldeman). Baker, 1928, Wisconsin Geol.

Nat. History Survey Bull. 70, pt. 1, p. 395, pi. 24, fig.

1-5.

Hibbard, 1941, Kansas Univ. Sci. Bull., v. 27, p. 95. 

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. n.

Distribution. Nova Scotia and New England west 

to Manitoba and northeastern Illinois (F. C. Baker, 

1928, p. 397).

Ecology. "Femssia parallela is usually found in 

quiet water, on plants, the water in such places ranging 

from .3-2 meters in depth. The animal is usually 

found near the surface but may occur on the lower part 

of such plants as Scirpus, near the bottom. Parallela 

appears to be a pond or lake species, at least in Wisconsin" (F. C. Baker, 1928).

Occurrence: Rexroad local fauna (Hibbard).

Ferrissia meekiana (Stimpson), 1863

Gundlachia meekiana Stimpson, 1863, Boston Soc. Nat. History

Proc., v. 9, p. 250.

Binney, 1865, Smithsonian Misc. Coll. 143, p. 150. 

Pilsbry, in Heclley and Pilsbry, 1895, Nautilus, v. 9, p. 63. 

Ancylus pumilus Sterki. Walker, 1904, Nautilus, v. 18, p. 82,

pi. 6. fig. 20-22. 

Walker, 1914, Nautilus, v. 27, p. 129.
62 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Ferrissia cf. pumila (Sterki). Taylor, 1954, Michigan Univ. 

Mus. Zool. Occ. Papers 557, p. 15.

Distribution. Probably the species ranges over most 

of the eastern United States. It is known from scattered localities in Alabama, Missouri, Virginia, the 

District of Columbia, and from Iowa eastward to New 

York.

Ecology. Uncertain. It has been found in temporary pools, ponds, and sloughs, but may occur in other 

habitats as well.

Remarks. The kinds of shells called Ferrissia meekiana in this paper have been found at several localities in Pleistocene deposits of the Great Plains. Frequently the very small, septate, immature shells are asassociated with larger, non-septate shells similar to F. 

pumila. Only one sample large enough to show the 

range of variation adequately has been collected; it is 

from Dixon locality 2 (UMMZ 191516). On the basis 

of the range of variation in this fossil sample, the range 

of variation in Recent material in the University of 

Michigan Museum of Zoology, and the similarity of 

the fossils to specimens identified by Walker as Grundlachia meekiana it appears that the small, septate shells 

and larger nonseptate specimens represent one species, 

and that Ancylus pumilus Sterki represents the nonseptate form of "Grundlachia" meekiana. Walker 

(1914, p. 129) reached similar conclusions from study 

of Recent shells.

Watson (in Connolly, 1938, p. 525-526) presented 

evidence to indicate that reference of all septum-forming Ancylidae to Gundlachia is unjustified. He restricted Gundlachia to tropical American and West 

Indian species with a smooth apex and an asymmetrical 

central tooth, and placed apically striate septum-forming species (Kincaidilla} in Ferrissia. In accordance 

with this classification Gundlachia meekiana (including Ancylus pumilus} is referred to Ferrissia.

Occurrence and material: Sand Draw and Dixon local 

faunas. Sand Draw loc. 1. UMMZ 181244 (7), 181246 (2) ; 

loc. 3, UMMZ 177338 (13) ; Dixon loc. 1, UMMZ 182211 (5) ; 

loc. 2, UMMZ 191516 (44).

Sand Draw loc. 1: Only one of the nine specimens is 

septate. Loc. 3: all 13 lack septa. Dixon loc. 1: Of the 5 

specimens 3 are septate. Loc. 2: 7 of the 44 are septate. 

The series from Dixon loc. 2 is the only one large enough to 

give a reasonably adequate idea of variation within the 

population. It may be divided into five groups, as follows:

(a) Five small specimens, 1.7-2.3 mm long, with the 

septum covering about three-quarters of the aperture. These 

are similar to the two small, septate specimens from Dixon 

loc. 1. Three are striate anteriorly.

(b) Four small specimens, 2.3-2.5 mm long, nonseptate. 

These are similar in shape to those of group (a), and to one 

specimen from Sand Draw loc. 3. All four are smooth.

(c) Two immature specimens, 2.5 and 3.3 mm long. Both 

apparently formed a septum over about one-fifth of the aperture before continuing growth. The larger is striate anteriorly.

(d) Four mature specimens, 3.0-3.2 mm long, nonseptate, 

with nearly straight sides roughly parallel or slightly divergent anteriorly. Three are anteriorly striate.

(e) Twenty-nine specimens, immature and mature, reaching a size of 3.3 X 1.9 mm. The lateral outline of the shell 

varies from only slightly to moderately curved. One only is 

anteriorly striate. The apex is about one-fourth of the shell 

length from the posterior end and somewhat to the right of 

the median line. The right slope is straight or gently concave ; the left slope straight or gently convex. The height of 

the shell varies from less to more elevated than F. pumila as 

figured by Walker (1904, pi. 6, fig. 20). Most shells are more 

depressed, however, with a slightly more concave posterior 

slope. The anterior end of the shell is symmetrical in outline, the posterior end usually so. The slight flattening of 

the dextroposterior margin is not as marked as in the specimens from Sand Draw loc. (UMMZ 181244). This group 

agrees well with a series (UMMZ 67269) from Clear Lake, 

La Porte, La Porte County, Ind., identified as Gundlachia 

meekiana by Bryant Walker.

Family PHYSIDAE 

Genus FHYSA Draparnaud, 1801 

Fhysa anatina Lea, 1864

Physella anatina Lea. Baker, 1928, Wisconsin Geol. Nat. 

History Survey Bull. 70, pt. 1, p. 470, pi. 19, fig. 5 

[not 7]. 

Physa species, young and fragments. Baker, 1938, Nautilus,

v. 61, p. 130. 

Physa anatina Lea. Hibbard, 1941, Kansas Univ. Sci. Bull.,

v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

p. 408. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151, pi. 14, fig. z.

Physa sp. McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser., v. 

9, p. 36 [in part].

Distribution. Very poorly known, on account of the 

lack of study of the genus. Probably it will be found 

in most of the central and southern Great Plains. 

Crandall (1901, p. 57) states, "It is plentiful around 

Wichita, Kansas, and has been reported from Missouri, 

Kansas, Nebraska, and Michigan. It probably inhabits 

all the intervening territory."

Ecology. This species is found in almost any sort of 

perennial, shallow water body, in either flowing or 

standing water. In Meade County, southwestern Kansas, it can be found in small streams, in the spring-fed 

ponds in the State Park, or in stock tanks. In northern 

Nebraska it was not found in still water, but only in 

seepages or spring-fed streams.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, Sand Draw, Dixon, and Sanders local 

faunas; Recent in northern Nebraska. Saw Rock Canyon, 

UMMZ 172364 (31), 177560 (2500), USGS 19089^ (800);
SYSTEMATIC DESCRIPTIONS 63

Red Corral, UMMZ 182998 (150) ; Rexroad loc. 1, UMMZ 

183057 (35) ; loc. 2, UMMZ 183067 (1) ; loc. 3, UMMZ 183030 

(60); loc. 4b, UMMZ 177600 (3000), 181049 (1500); Bender 

loc. la, UMMZ 184121 (3) ; loc. Ib, UMMZ 184135 (1) ; loc. 

2, UMMZ 184152 (50) ; Sand Draw loc. 2, UMMZ 184176 (1) ; 

loc. 3, UMMZ 177340 (55) ; loc. 4, UMMZ 177321 (8) ; loc. 5, 

CNHM PB3432 (4), UIMNH P6786 (3), UMMZ 181231 (25); 

loc. 6, UMMZ 177432 (1), 181215 (1); Dixon loc. 1, UMMZ 

182206 (150) ; Sanders loc. 1, UMMZ 182149 (13) ; loc. 2, 

UMMZ 184163 (2) ; loc. 3, UMMZ 182181 (3 + fragments).

Physa gyrina Say, 1821, form hildrethiana Lea, 1841

PJiysella gyrina hildrethiana (Lea). Baker, 1928, Wisconsin 

Geol. Nat. History Survey Bull. 70, pt. 1, p. 453, pi. 27, 

fig. 36; pi. 28, fig. 2-4, 7-14.

Physa elliptica Lea. Taylor, 1954, Michigan Univ. Mus. Zool. 

Occ. Papers 557, p. 15.

Distribution. Probably found in most of North 

America north of Mexico. According to Baker (1928), 

P. gyrina is found "from the Arctic regions south to 

Alabama and Texas;" the form hildrethiana, " * * * 

is common east of the Mississippi River from western 

New York and Pennsylvania to Illinois and south to 

Alabama. Occurs also in Iowa and possibly in other 

states west of the Mississippi River/'

Ecology. "Hildrethiana is characteristic of swales 

and summer-dry ponds, where it is deprived of moisture 

for a large part of the year. The variety in such 

localities rarely reaches maturity, the usual form being 

a small, short, shell with dome-shaped spire, greatly 

resembling oleacea and elliptica. These small forms 

usually show no rest marks, living only as long as the 

water remains in the pool. Mature shells may often 

be found by digging in the mud or in cracks in the 

bottom of the pool where the mollusk has descended 

for moisture" (Baker, 1928, p. 454). In northern 

Nebraska this snail was common at many places, in 

temporary ponds and drainage ditches, permanent 

ponds and a stock tank. P. gyrina, and P. anatina were 

never found together. P. anatina occured only in seepages and streams.

Occurrence and material: Sand Draw and Dixon local 

faunas: Recent in northern Nebraska. Sand Draw loc. 1, 

UMMZ 181247 (13) ; loc. 2, UMMZ 184177 (3) ; Dixon loc. 1, 

UMMZ 182207 (60) ; loc. 2, UMMZ 191517 (65).

Physa skinneri Taylor, 1954 

Plate 3, figures 5, 6, 9-11

Physa species, young of small, narrow species. Baker, 1938,

Nautilus, v. 51, p. 130. 

Physa sp. McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser., v.

9, p. 36 [in part]. 

Physa skinneri Taylor, 1954, Michigan Univ. Mus. Zool. Occ.

Papers 557, p. 9, 15.

Types. Holotype UMMZ 181292, Berends local fauna. Paratypes UMMZ 177533 (31), MCZ 198177 (68), USNM 562010 

(12).

Diagnosis. A species distinguished by its small size 

(less than 7.5 mm), narrow ovoid form, and obtusely 

rounded apex. It is most similar to P. fontinalis 

(Linne) and P. hordacea Lea.

Description of types. Shell small, narrowly ovoid, 

polished; apex obtusely rounded. Whorls about three, 

gently and regularly convex, slowly enlarging, at first 

overlapping; body whorl over three-fourths of total 

shell length. Suture weakly impressed, slightly 

descending at first but later more strongly; above periphery of first whorl, at periphery of later whorls. 

Aperture narrowly elongate; outer lip slightly convex, 

more strongly so toward base; base strongly rounded; 

inner lip nearly straight or with a pronouced angle at 

junction of columella and parietal lip; peristome usually heavily callused in larger specimens, in which case 

the suture descends slightly at the callus; parietal wall 

covered by a thin callus. Nucleus smooth; later sculpture of A^ery fine, indistinct growth lines occasionally 

cut by very faint, short segments of spiral striae between which growth lines may be locally more prominent.

Measurements. The mean of 21 adult paratypes of 

3 whorls is folloAved by the range in parentheses. These 

are judged to be adult because they usually have a 

heavy peristome callus and because specimens with 

more whorls are rare. Measurements are given in millimeters. Length, 3.7 (3.0-4.3); width, 2.0 (1.7-2.5); 

length of aperture, 2.2 (1.7-2.6) ; width of aperture, 

1.1 (0.8-1.3).

The measurements in millimeters of 10 Recent specimens from Utah (USNM 533484) are as follows:

Length

6. 4

6. 7

7. 3

6. 9

7. 1

6. 6

6. 7

6. 6

7. 1

6. 9

Width

3. 4

3.7

4. 0

3.7

3. 9

3. 6

3. 7

3. 6

3. 9

3. 7

Length of 

aperture

4. 0

4. 4

4. 6

4. 1

4. 3

3. 9

4. 1

3. 9

4. 1

4.0

Width of 

aperture

1. 8

2. 1

2. 1

2. 0

2. 1

1. 9

2.0

1. 9

1. 8

2. 0

Number of 

whorls

3%

4

4

4

4

4

4

4

4H

4H

These are the largest specimens seen, in both size and 

number of whorls.

Variation. The proportions vary slightly, as indicated by the measurements, but the obtuse apex is 

constant. In the shorter shells the shallow suture gives 

an almost unbroken curve from apex to base. Sometimes an earlier peristomal callus is visible through 

the shell. The callus is accompanied by the usual brief
64 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

descent of the suture, which thereafter ascends and resumes the former angle of descent.

Distribution. Alaska southward to northern Utah; 

eastward across southern Canada to western Ontario 

and northern Minnesota.

Ecology. The scanty information from the Recent 

occurrences suggests this species lives in shallow bodies 

of water, either perennial or seasonal, such as temporary ponds, sloughs, and backwaters along streams.

Remarks. A number of Recent series of P. skinneri 

are now known which demonstrate that the species is 

not extinct, as was first thought, and that it has a wide 

distribution in North America. This living material 

also helps to establish the range of variation in P. 

skinneri.

Two of the larger series of adults from the Uinta 

Mountains, Wyoming and Utah, differ from the type 

series in being slightly larger, thinner shelled and with 

weak or absent peristomal calluses. The larger series 

(USNM uncat., 72 specimens) is from the Heward 

ranch, Uinta County, Wyo., from a slough by the Bear 

River 1 mile above the Utah border. Numerous adult 

shells agree well in proportions with the type series. 

They attain 31/2-4 whorls, and reach a length of 6 mm. 

There are no peristomal calluses. Sculpture consists 

of weak growth lines, and many spiral series of very 

short, axial, impressed lines.

Another lot (USNM 533484, 10 specimens) is from 

Lost Creek, Summit County, Utah, T. 1 S., R 5 E., 

6,000 feet elevation. All ten shells are adult, and 

larger than those of the type series or those from Uinta 

County (see measurements). They are also proportionally higher spired, but not more so than the extreme 

observed in fossil material. Sculpture is as in the 

Uinta County material. Several individuals have a 

thin callus around the peristome and another one about 

%-l whorl earlier. The suture descends slightly to 

the earlier callus, as it does in the type series.

In the Pleistocene of the Great Plains, Physa skinneri is commonly associated with P. anatina Lea and P. 

gyrina Say. It differs from these two species in its 

smaller size, narrower form, obtuse and rounded apex, 

regularly convex whorls, and proportionally smaller 

aperture. It apparently has no close relatives living in 

the Great Plains.

Physa jennessi Ball (1919, p. 20A) differs from P. 

skinneri by being nearly twice as long, with l-l^ 

more whorls, a deeper suture, and a proportionally 

longer spire and shorter aperture. The columella may 

be markedly gyrate, a feature not seen in P. skinneri; 

no trace of peristomal callus is visible. The only localities known surely are Bernard Harbor, Northwest Territories (type locality), White Horse, Yukon Territory (USNM 251936), and a pond at lat. 69° 40' N., 

long., 141° W., on the coast of Yukon Territory 

(USNM 251938).

Physa hordacea Lea (1864, p. 116; 1866, p. 176; 1867, 

p. 132; this paper, pi. 3, figs. 1-4) is similar to P. skinneri in size, sculpture and general shape, but has an 

acute apex instead of a blunt, rounded one. The only 

known material with precise locality data is the type 

lot from Columbia River, Vancouver Island, at Vancouver, Clark County, Wash. (USNM 170764, holotype 

and 111 paratypes).

The European Physa fontinalis (Linne) is perhaps 

the species most closely related to P. skinneri. It 

shares the blunt, rounded apex of the latter, but has 

usually another whorl and is half again as long. It is 

proportionally wider, globose rather than narrowly 

ovoid as is P. skinneri, and thus has a wider aperture 

with the inner lip markedly angular at the junction 

of columellar and parietal portions.

The grouping of Physa species is very diffcult, because the limits of variation of the species are poorly 

understood, and biological information is not available for more than a very few species, however they are 

delimited. The relations of P. skinneri, as inferred 

from a single shell character, may be viewed in two 

ways: The blunt, rounded apex of P. skinneri and P. 

fontinalis indicates their close relation. P. hordacea is 

similar only by convergence, for its acute apex indicates a quite different ancestry. P. hordacea and P. 

skinneri are so similar that they must be closely related 

no matter what apical differences there may be. P. 

fontinalis is similar only in the not-too-significant feature of a rounded apex.

When anatomical data are available on the American 

species, it wrill be possible to evaluate these shell characters, and perhaps even to recognize subgenera of 

Physa.

Types. Holotype FMMZ 181292, Berends local fauna. 

Paratypes UMMZ 177533 (31), MCZ 198177 (68), USNM 

562010 (12).

Occurrence: Sand Draw, Dixon, and Sanders local faunas. 

Sand Draw loc. 2, USGS 19090-4 (9) ; loc. 3, UMMZ 177339 

(100) ; loc. 4, UMMZ 177322 (3) ; loc. 5, CNHM PE3433 (3), 

UIMNH P6787 (3), UMMZ 181137 (25), 181232 (100); loc. 

6, UMMZ 177433 (4), 181216 (100); loc. 7, UMMZ 177233 

(20) ; Dixon loc. 1, UMMZ 182208 (36) ; loc. 2, UMMZ 191518 

(22) ; Sanders loc. 1, UMMZ 182150 (1) ; loc. 3, UMMZ 182- 

182 (4).

Genus APLEXA Fleming, 1820

Aplexa hypnorum (Linnaeus), 1758

Aplexa hypnorum (Linne). Baker, 1928, Wisconsin Geol. Nat.

History Survey Bull. 70, pt. 1, p. 473, pi. 19, fig. 1-4. 

Taylor. 1954, Michigan Univ. Mus. Zool. Occ. Papers 557, 

p. 15.
SYSTEMATIC DESCRIPTIONS 65

Distribution. Holarctic. In North America "* * * 

from east of the Cascade Mountains to the Atlantic and 

from Alaska and Hudson Bay south to the vicinity of 

the Ohio River' 1 (Baker, 1928, p. 474).

Ecology. ^ A pi. eve a hypnorum is a species of swales 

and intermittent streams or stagnant pools in Wisconsin, as far as present data goes. It is especially 

abundant in woodland pools which become dry in 

summer * * *" (Baker, 1928, p. 474). In northern 

Nebraska it was locally abundant in roadside drainage 

ditches with temporary water.

Occurrence and material: Sand Draw and Sanders local 

faunas; Recent in northern Nebraska. Sand Draw loc. 3, 

UMMZ 181202 (1) ; loc. -i, UMMZ 177323 (2) ; loc. 5, UMMZ 

181138 (100). 181233 (300) ; loc. 6. UMMZ 181217 (1) ; Sanders 

loc. 1, UMMZ 182151 (16).

Order STYLOMMATOPHORA

Family STROBI10PSIDAE

Genus STROBI10PS Pilsbry, 1893

Submenus STROBILOPS s. s.

Strobilops (s. s.) labyrinthica (Say), 1817

Plate 1, figures 5, 6

Strobilops labyrinthica (Say). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 2, p. 854, fig. 463. 

Strobilops cf. labyrinthica. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Seward County

loc.]. 

Strobilops sparsicosta Baker. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Seward County

loc.].

Distribution. "Maine and Quebec west to Manitoba, 

Minnesota, Kansas and Arkansas, south to Georgia 

and Alabama" (Pilsbry, 1948, p. 854).

Ecology. "Its usual stations are 'under loose bark 

of logs, in half-decayed wood, among dead leaves and 

in sod at bases of trees' v (Pilsbry, 1948, p. 854).

Remarks. Specimens from the Saw Rock Canyon 

local fauna differ from S. texasiana and $. sparsicostata, and agree with S. labyrinthica. in that the axial 

riblets are small, not widely spaced, and usually cover 

about half the base, and also that the parietal lamellae 

enter only one-half whorl. They are also smaller 

(diameter 2.5 mm.) than /S. sparsicostata topotypes 

or referred specimens. These specimens are thus considered referable to S. labyrinthica.

Sculpture on the base is variable. The riblets may 

pass over the periphery to cover the whole base, or 

only about a quarter of a whorl behind the aperture. 

Ten specimens were dissected for examination of the 

basopalatal folds. These folds are as usual for the

S. labyrinthica-texasiana group; they differ from those 

observed in /S. sparsicostata topotypes in that the first 

and second basals are not so large, the third through 

fifth basopalatals are stronger, and the sixth basopalatal is sometimes absent. Six specimens examined have 

parietal lamellae entering half a whorl.

Frye and Leonard (1952) reported S. cf. labyrinthica in association with S. sparsicostata from the Saw 

Rock Canyon local fauna. University of Michigan 

material from the same locality justifies recognition 

of only one species, 8. labyrinthica (Say).

For discussion of the differences between #. labyrinthica and S. sparsicostata, see under the latter 

species.

Occurrence and material: Saw Rock Canyon local fauna. 

UMMZ 177561 (35).

Strobilops (s. s.) sparsicostata Baker, 1938 

Plate 1, figures 7-10

Strobilops sparsicostata Baker, 1938, Nautilus, v. 51, p. 127. 

Smith, 1940, Kansas Geol. Survey Bull. 34, p. 98. 

Leonard. 1957, Illinois Geol. Survey Report of Investigations 201. p. 18, pi. 1, fig. 4-6. 

Strobilops sparsicostata F. C. Baker. Hibbard, 1941, Kansas

Univ. Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

p. 408.

Strobilops sparsicosta Baker. Frye and Leonard, 1952, Kansas 

Geol. Survey Bull. 99. p. 151 [in part: Meade County 

loc.].

Strobilops densecostata F. C. Baker. Pilsbry, 1948, Acad. Nat. 

Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 851 [lapsus for 

sparsicostata].

Strobilops cf. labyrinthica. Frye and Leonard, 1952, Kansas 

Geol. Survey Bull. 99, p. 151 [in part: Meade County 

loc.].

Types. Holotype UIMNH P6774, Rexroad loc. 3. Paratypes 

UIMNH P6774 (51), P6775 (4), ANSP 169886 (not found).

Diagnosis. A Strobilops (s.s.) characterized by 5- 

6 strongly unequal basopalatal folds, the sixth (when 

present) above the periphery, and by axial sculpture 

of strong, widely spaced riblets not extending onto 

the base of the shell.

Description. Shell broadly conic, subangular at periphery. Whorls about 5l/2> embryonic l 1/^ weakly 

and finely granular with faint axial striation; later 

whorls with axial riblets, small and closely but irregularly spaced from 11^-3 whorls, becoming stronger 

and wider spaced thereafter; last 2 whorls with strong, 

irregularly and widely spaced riblets, occasionally 

with 1 or 2 weak riblets between. Base smooth, or with 

a few weakening riblets extending over the periphery 

on the last quarter whorl; umbilicus contained 7 times 

in shell diameter. Aperture roughly semicircular, with
66 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

a prominent, massive, parietal lamella extending forward to fuse with a thick parietal callus; a low, inconspicuous, infraparietal lamella almost reaching the 

parietal callus, visible externally; lip reflected, thickened. Parietal and infraparietal lamellae entering 

three-fourths of a whorl; a weak interparietal lamella 

about a quarter whorl long nearly reaching the inner 

ends of the other parietal lamellae; interparietal and 

inner halves of parietal and infraparietal lamellae 

with prickly nodes at intervals of about 11/2 times 

their length; columellar lamella low, about half a 

whorl long, beginning at about a quarter whorl within 

aperture, increasing and decreasing in size gradually; 

basopalatal folds parallel, arranged in an arc from 

about two-thirds of a whorl within aperture nearest 

the columella to one-third of a whorl within at the 

periphery, 5-6 in number, the sixth above the periphery if present; first 2 basal folds much larger than 

others, the first nearly horizontal, roughly triangular 

or tongue shaped, the second longer, erect, lamellar; 

other folds short and low, the sixth basopalatal weak 

or absent.

Measurements. Five randomly chosen topotypes 

measure as follows, the mean being followed by the 

range in parentheses. Measurements are in millimeters. Length, 2.26 (2.1-2.5) ; width, 2.70 (2.6-2.8) ; 

number of whorls, 5.5 (514-5%).

Variation. The chief observed variables are axial 

ribbing and basopalatal folds. Most of the major 

series of riblets extend from suture to periphery, at 

least. Some are shorter, however, and reach only 

halfway to the periphery from suture, or vice versa. 

The minor series is variably developed, from none to 

two small riblets being present between the larger 

ones. The columellar lamella varies in length and 

size. Both first and second basal folds vary greatly 

in size and shape. The first is usually subhorizontal, 

but sometimes nearly erect; almost always shorter 

than the second basal fold, never longer; and triangular to linguiform. The second basal fold varies 

chiefly in slope of its ends; these may slope equally, 

or either one may be steeper. The upper side of the 

fold may be parallel to the base for much of its length, 

or it may slope toward the ends from a subcentral 

point. The sixth basopalatal fold may be present or 

absent. Two specimens have supernumerary basopalatal folds between the first and second (recognized 

by their characteristic shape and position) of a more 

usual series. One specimen has a small, tubercular fold 

approximate to the second basal and fused to the 

peripheral end of the first basal fold. Other basopalatal folds in this specimen are typical. The other 

specimen has 4 supernumerary basopalatal folds, 3 between the first and second of the usual series, 1 between 

the second and third. The most axiad supernumerary 

fold is fused to the first basal fold, but the next two 

are distinct. The fourth supernumerary fold is fused 

to the second basal fold. The third basal is present 

and typical, but the fourth through sixth are absent. 

(The description and the above discussion of variation 

are based on about 250 topotypes, UMMZ 183032; 15 

specimens were dissected to observe the basopalatal 

folds, 10 for the parietal lamellae.)

Distribution. Middle Pliocene to lower Pleistocene 

(perhaps middle Pleistocene also) of the High Plains.

Remarks. /Strobilops sparsicostata is closely related 

to both 8. labyrinthica (Say) and 8. texasiana Pilsbry 

and Ferriss. It differs from 8. labyrinthica by the 

slightly larger size, deeper penetration of the parietal 

lamellae, coarser and more widely spaced axial riblets, 

and sometimes smoother base. It differs from 8. texasiana in the slightly larger size and smooth base.

Frye and Leonard (1952) reported S. cf. labyrinthica 

in association with S. sparsicostata from Rexroad 

localities 2 and 3. University of Michigan material 

from locality 3 justifies recognition of only 8. sparsicostata, and for this reason both references to 8. cf. 

labyrinthica are assigned to 8. sparsicostata.

Leonard (1950, 1952) has reported 8. sparsicostata 

from middle Pleistocene deposits, but I have not 

examined material from these higher levels.

Occurrence: Buis Ranch, Red Corral, Rexroad, Sand Draw 

and Dixon local faunas.

Discussion of material: Rexroad loc. 1, UMMZ 183058 (1). 

The single, juvenile (3% whorls) specimen shows coarse 

ribbing, and may be referred to S. sparsicostata.

Rexroad loc. 4b, UMMZ 181056 (1). The single specimen 

(adult) was not dissected, but is similar to S. sparsicostata 

topotypes in external features.

Buis Ranch, UMMZ 181116 (3). The material consists of 

3 adult body whorls only, 2 slightly broken. The axial riblets 

are as strong as those in S. sparsicostata topotypes, and 

stronger than those of 8. labyrinthica. They are spaced more 

widely than those of $. labyrinthica and more closely than 

those of ASf. sparsicostata topotypes. The one specimen on 

which the adult diameter can be measured is 2.7 mm in diameter, larger than $. labyrinthica but within the size range 

of S. sparsicostata topotypes. Only one specimen retains the 

parietal lamella; it enters three-fourths of a whorl, as in 

 S. sparsicostata. This material is referred to $. sparsicostata.

Red Corral, UMMZ 182999 (1). The single specimen (adult) 

was not dissected, but is similar to 8. sparsicostata topotypes 

in external features.

Sand Draw loc. 2, UMMZ 184178 (11). A series of specimens has ribs weaker than in S. sparsicostata topotypes but 

stronger than those of 8. labyrinthica. These specimens 

agree with 8. sparsicostata and differ further from $. labyrinthica in size (diameter 2.7-2.8 mm) penetration of the parietal 

lamellae for a distance of three-fourths whorl, and smoothness of base. They are therefore referred to S. sparsicostata 

for the present.
SYSTEMATIC DESCRIPTIONS 67

Sand Draw loc. 3, UMMZ 181203 (2). Two specimens (one 

adult, one subadult) agree in external features with those 

from Sand Draw loc. 2. The inner ends of the parietal 

lamellae of the adult are broken away.

Dixon loc. 1, UMMZ 182213 (3). The single adult specimen 

was not dissected. It agrees with 8. sparsicostata topotypes 

and differs from 8. labyrinthica in the following respects: 

large size (diameter 2.9 mm), smooth base, and widely spaced 

riblets. The strength of the riblets is, however, intermediate 

between that of &. sparsicostata and 8. labyrinthica. Specimens from the Dixon local fauna are referred to 8. sparsicostata for the present.

Family PUPILLIDAE

Subfamily GASTROCOPTINAE

Genus GASTROCOPTA Wollaston, 1878

Subgenus GASTROCOPTA s. s.

Gastrocopta (s. s.) procera (Gould), 1840

Plate 1, figure 27

Gastrooopta procera, (Gould). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 2, p. 907, fig. 492:1-5. 

Gastrocopta procera (Gould). Franzen and Leonard, 1947,

Kans. Univ. Sci. Bull., v. 31, p. 341 [in part], pi. 18,

fig. 3 [not fig. 6].

Distribution. Maryland to South Carolina and 

Alabama; west to South Dakota and Arizona (Pilsbry, 

1948, p. 907, 910).

Ecology. "This pupillid lives on timbered slopes 

of streams. Its general distribution in Kansas indicates an ability to withstand periods of summer 

drought" (Franzen and Leonard, 1947, p. 342).

Remarks. For discussion of the species and of this 

material see under G. fransenae.

Occurrence and material: Dixon local fauna. Dixon loc. 1, 

UMMZ 182217 (1) ; loc. 2, UMMZ 191520 (11).

Gastrocopta (s. s.) franzenae 4 Taylor, n. ,sp. 

Plate 1, figure 29

Gastrocopta cristata Pilsbry and Vanatta. Hibbard, 1941,

Kansas Univ. Sci. Bull., v. 27, p. 95 [not of Pilsbry and

Vanatta]. 

Hibbard, 1941, Kansas Acad. Sci. Trans. v. 44, p. 265

[not of Pilsbry and Vanatta]. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408 [not of Pilsbry and Vanatta]. 

Gastrocopta cristata (Pilsbry and Vanatta). Franzen and

Leonard, 1947, Kansas Univ. Sci. Bull., v. 31, p. 344

[in part: Rexroad fauna material. Not of Pilsbry and

Vanatta]. 

Gastrocopta procera (Gould). Franzen and Leonard, 1947,

Kansas Univ. Sci. Bull., v. 31, p. 341 [in part: Saw

Rock Canyon fauna material], pi. 18, fig. 6 [not of

Gould].

* Named for Dr. Dorothea S. Franzen.

Types. Holotype: UMMZ 183033a, Rexroad loc. 3. Hypodigm: Material from Saw Rock Canyon, Red Corral, and Rexroad local faunas and from Bender local fauna localities lb 

and 2 in University of Michigan collections.

Diagnosis. A Gastrocopta of the G. cristata group 

with a strong labial callus, an anguloparietal lamella 

either bifid or simple; some individuals with a tubercle 

on the outer lip.

Distribution. Upper Pliocene of the southern High 

Plains.

Remarks. Late Pliocene samples of the Gastrocopta cristata group are unusual in that several populations include the diagnostic characters of distinct, 

Kecent species, as well as characters not found in 

these living species. For reasons set forth below, the 

late Pliocene populations are considered representative 

of an extinct, probably ancestral species.

Gastrocopta cristata and G. procera are two wideranging Eastern North American land snails of similar habitat. Each occurs separately in much of its 

range, but the 2 are also found together in a large 

area (see under the 2 species for details of distribution). They are now distinct species, although closely 

related; and their association in the Nebraskan age 

Dixon local fauna indicates their separate status 

throughout nearly the entire Pleistocene epoch.

Distinction of these two species is based chiefly on 

the anguloparietal lamella (straight or slightly sinuous 

in G. cristata, bifid in G. procera) and on the labial 

callus (weak or absent in G. cristata, strong in G. 

procera). Other, less diagnostic features are the 

stronger, more proximal crest and greater diameter 

of G. cristata shells. Late Pliocene samples, however 

(especially those from the Kexroad local fauna), are 

markedly more variable than Kecent series. The Pliocene samples include shells like those of G. cristata 

and G. procera, specimens intermediate in the degree 

of fusion of the anguloparietal lamella (not seen in 

Recent or Pleistocene material), shells like G. cristata 

but with a strong labial callus as in G. procera, and 

shells like G. procera but with a strong tubercle on 

the outer lip next to the sinulus. The frequency distributions of these character combinations suggest 

that only one population is represented in the Kexroad local fauna and at Bender local fauna localities 

lb and 2. The sample from Saw Kock Canyon is inadequate for analysis.

In figure 2, Pliocene specimens of the Gastrocopta 

cristata group are distributed according to arbitrarily 

selected segments of the range of variation of two 

characters: development of the labial tubercle (absent, 

weak, or strong), and degree of fusion of the anguloparietal lamella (straight or slightly sinuous, strongly
68 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

= 12 N = 22 = 396

25 

(3)

8 

(1)

67 

(8)

Saw Rock Canyon 

N = 484

Bender Ib

Absent

Weak

Strong

Bender 2

Labial

Tubercle

Anguloparietal

FIGURE 2. Frequency distribution of Pliocene Gastrocopta cristata

group.

sinuous, or bifid). The groups with straight and 

bifid anguloparietal lamella were established to correspond with the range of variation in Recent G, 

cristata and G. procera, respectively.

The Rexroad local fauna has yielded ample series 

from three localities. Each series is considered representative of but one population. The slight bimodality 

in the locality 4b sample is ascribed to error and (or) 

intraspecific variation. The general similarity between the three populations is such that reference to 

one species is justified. Contemporaneity of these 

three is established to the degree of refinement possible 

by mammalian and stratigraphic correlation; but 

within such limits there is surely enough time that 

minor genetic changes may account for some or all 

of the observed differences.

The holotype of G. franzenae is selected from the 

specimens intermediate in development of labial callus 

and in degree of fusion of the anguloparietal lamella.

The Saw Rock Canyon sample, although inadequate, 

is of interest because two-thirds of the specimens have

a bifid anguloparietal lamella and a strong labial 

tubercle. This combination of characters is markedly 

infrequent in other samples. In this connection it 

should be noted that apparently all specimens from 

this locality available to Franzen and Leonard (1947, 

p. 341) are of this extreme type.

The Red Corral sample is also inadequate. All 

shells are similar to G. cristata, except that some 

have a strong labial callus. The material is believed 

representative of a population similar to those of the 

Rexroad local fauna, however; observed differences 

may be accounted for by geographic separation of 

the sample sites, possible temporal difference between 

the samples, small size of the Red Corral sample, and 

large percentage of similar shells in the Rexroad 

locality 4b sample.

Bender local fauna samples are considered significantly different among themselves. Localities la, Ib, 

and Ic are about one-eighth of a mile apart and at the 

same stratigraphic horizon. There is presumably some 

difference in mean age of the three samples, but it is 

considered inadequate to account for the striking differences observed. Material from localities la and Ic 

is referred to one population (G. cf. cristata}, similar 

to G. cristata but with frequent development of a 

strong labial callus. This strong callus occurs in a 

smaller percentae of specimens than it does in the 

Rexroad local fauna. Locality Ib material is believed 

to represent another population, referred to G. franzenae. Bender locality 2 material is referred to G. 

franzenae also.

Early Pleistocene samples (Sand Draw, Dixon, Sanders local faunas) of the G. cristata group are all 

typical of the Recent G. cristata and G. procera. Large 

series of G. cristata from the Sanders local fauna 

have a straight or slightly sinuous anguloparietal 

lamella and no strong labial callus; the same is true 

of a small series from Dixon and two specimens from 

Sand Draw. One specimen of G. procera from Dixon 

has a bifid anguloparietal lamella, thick labial callus, 

and no labial tubercle.

Gastrocopta franzenae is a satisfactory structural 

ancestor for both G. cristata and G. procera, for its 

range of variation includes specimens similar to both 

of these Recent species. Further support for a 

franzenae-cristata and procera lineage is the presence 

at Bender localities la and Ic of a population intermediate between G. franzenae and G. cristata, but apparently distinct from associated G. franzenae. Specimens from Bender localities la, Ib, and Ic may therefore have lived shortly after the derivation of G. cristata from G. franzenae.
SYSTEMATIC DESCRIPTIONS 69

The evidence is inconclusive, but does suggest that 

G. franzenae gave rise to both G. procera and G. cristata during the late Pliocene, that it became extinct 

shortly thereafter (perhaps with the climatic changes 

associated with the onset of continental glaciation), 

and that the two descendants have lived to the present 

day. The time, place, and method of origin of the 

two younger species are uncertain. The Bender sample suggests that G. franzenae had already given rise 

to a species with which it did not interbreed, and 

which has subsequently changed into G. cristata. G. 

procera, if already distinct, is not known from this 

interval.

One possible method of origin of the two descendants is by selection of their particular gene combinations from the G. franzenae "pool". There seems no 

need to postulate mutation, although this may have 

occurred. Assuming that the labial tubercle is genetically produced, its genes were left behind in selecting 

out G. cristata and G. procera. The evolution of the 

two species may possibly have been caused by climatic 

changes which "filtered" them out of G. franzenae.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, and Bender local faunas. Saw Rock Canyon, UMMZ 

177516 (1), 177563 (9), 183654 (2); Red Corral, UMMZ 183- 

001 (24) ; Rexroad loc. 2, UMMZ 183068 (575) ; loc. 3, UMMZ 

183033 (825); loc. 4b, UMMZ 177601 (371), 181052 (509); 

Bender loc. Ib, UMMZ 184136 (31) ; loc. 2, UMMZ 184153 

(175).

Gastrocopta (s. s.) cristata (Pilsbry and Vanatta), 1900 

Plate 1, figures 24-26

Gastrocopta cristata Pilsbry and Vanatta. Baker, 1938,

Nautilus v. 51, p. 130. 

Gastrocopta, cristata. McGrew, 1944, Field Mus. Nat. Hist.

Geol. Ser., v. 9, p. 36. 

Gastrocopta cristata (Pilsbry and Vanatta). Franzen and

Leonard, 1947, Kansas Univ. Sci. Bull., v. 31, p. 344,

pi. 19, fig. 1; pi. 20, fig. 1. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 911, fig. 493 :6, 8-12.

Distribution. Northern Nebraska to southern 

Texas, west to Arizona.

Ecology. "Gastrocopta cristata has, in Kansas, 

usually been found associated with G. procera (Gould) 

on timbered slopes near streams" (Franzen and Leonard, 1947, p. 345). In northern Brown County, Nebr., 

it was found in a wooded ravine, among damp leaves 

and dead wood.

Remarks. The Recent specimens from Nebraska 

differ from other material examined in being paler 

and in lacking a subcolimiellar tubercle. These differences probably represent normal variation, rather than 

specific characters.

The record by Taylor (1954a, p. 12) of this species 

in the Clarendonian Laverne local fauna is considered 

erroneous. The single specimen (UMMZ 181273) 

shows no trace of coloring on the peristome, as do all 

the other fossil Gastrocopta from the same locality. 

It is almost surely a Recent specimen. The only species 

of Gastrocopta (s. s.) known in the Laverne local 

fauna are G. riograndensis (Pilsbry and Vanatta) 

(Franzen and Leonard, 1947, p. 349, and University 

of Michigan collections) and G. lavernensis Taylor 

(1954a, p. 11).

For discussion of fossil material see under G. franzenae.

Occurrence and material: Bender, Sand Draw, Sanders, and 

Dixon local faunas; Recent in northern Nebraska. Sand 

Draw loc. 5, CNHM PE3437 (1) ; loc. 6, UMMZ 177435 (1) ; 

Dixon loc. 1, UMMZ 182216 (36) ; loc. 2, UMMZ 191519 (2) ; 

Sanders loc. 1, UMMZ 182153 (400) ; loc. 2, UMMZ 182167 

(125) ; loc. 3, UMMZ 182183 (600). G. cf. cristata: Bender 

loc. 1, UMMZ 177506 (111) ; loc. la, UMMZ 184122 (1750) ; 

loc. lc. UMMZ 183015 (2000).

Gastrocopta (s. s.) paracristata Franzen and Leonard, 1947, 

emend.

Plate 1, figures 31, 32

Gastrocopta paracristata Franzen and Leonard, 1947, Kansas 

Univ. Sci. Bull., v. 31, p. 346, pi. 19, fig. 2, 3 [in part: 

dextral shells only]. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151.

Types. Holotype UKMNH 3929, Rexroad loc. 4b. Paratypes 

UKMNH.

Diagnosis. A Gastrocopta of the G. cristata group 

with massive folds and lamellae, three equally immersed platal folds adjacent to the palatal callus, 

and no subcolumellar lamella.

Description of holotype. "Shell elongate-oval, summit obtuse; rimate, minutely perforate; suture sharply 

and deeply incised; whorls 5%; convex, regularly and 

slowly increasing in size; the l 1/^ nuclear whorls finely 

granular; remaining whorls finely and irregularly 

striate; height of body whorl less than one-half of the 

total height of the shell, constricted at the base and 

expanding rapidly toward the aperture; prominent, 

rounded crest paralleling the peristome from which 

it is somewhat removed; aperture rounded, slightly 

oblique, expanding toward the peristome; denticles 5: 

a fused, sinuous, anguloparietal, the angular portion 

continuous with a parietal callus and outer lip; 3 

equally entering palatal folds, connected anteriorly 

by a low callus, a tubercular upper palatal, a higher, 

elongate lower palatal, its highest point about midway 

of its length, and a low, tubercular basal fold; the 

columella lamella high, elongate, entering horizontally

508945 O 6
70 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

and ascending the spire at its extreme innermost portion; peristome reflected, thickened along its inner 

border, margin sharp" (Franzeii and Leonard, 1947, 

p. 346).

Measurements. Franzen and Leonard gave dimensions of five specimens from the type series. The 

mean of these (in millimeters) is followed by the 

range in parentheses. Length, 3.0 (2.7-3.4) ; width, 

1.4 (1.3-1.5) ; length of aperture, 1.1 (0) ; width of 

aperture, 1.0 (0.9-1.1) ; number of whorls, 5.9 (5V4~

_

Variation. "The range in height of the shells of 

Gastrocopta paracristata is from 2.7 mm to 3.4 mm. 

The width varies independently of the height, therefore, shells vary in shape from elongate-ovate to 

elongate-conic. The basal fold, usually prominent, is 

sometimes very low and occasionally wanting. The 

callus of the peristome varies in prominence. A prominent, rounded crest on the ultimate whorl, paralleling 

the peristome is usually present, rarely wanting, sometimes low and sharp. The distance between the peristome and the center of the crest varies from 0.5 to 

0.25 mm/ 1 (Franzen and Leonard, 1947, p. 347).

Distribution. Upper Pliocene and lower Pleistocene 

of the High Plains.

Remarks. Sinistral specimens from the SWl/4 sec. 

22, T. 33 S.; K. 29 W., Meade County, Kans., were 

included in G. paracristata by Franzen and Leonard 

in their original description of the species. These 

sinistral specimens are described as G. scaevoscala 

Taylor, n. sp., in this report.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, and Sanders local faunas. Saw Rock 

Canyon, UMMZ 173590 (1), 177562 (35), USGS 19089-5 (1); 

Red Corral, UMMZ 183003 (1) ; Rexroad loc. 1, UMMZ 183060 

(1) ; loc. 2, UMMZ 183071 (8) ; loc. 3, UMMZ 183036 (10) ; 

loc. 4b, UMMZ 177602 (35), 181051 (50) ; Bender loc. 1, UMMZ 

177507 (11-4) loc. la, UMMZ 18-412-4 (600): loc. Ib. UMMZ

184138 (300)

18-4154 (200)

loc. le. UMMZ 18-41-45 (150) ; loc. 2, UMMZ 

Sanders loc. 1, UMMZ 182154 (27) ; loc. 2,

UMMZ 182168 (1).

Gastrocopta (s. s.) scaevoscala Taylor, n. sp.B 

Plate 1, figures 33, 34

Gastrocopta paracristata Franzen and Leonard, 1947, Kansas 

Univ. Sci. Bull., y. 31, p. 346-347 [in part: sinistral 

specimens].

Types. Holotype UMMZ 1S4320, Bender loc. 1. Paratypes 

UMMZ 184125 (9), 183017 (13).

Diagnosis. A sinistral Gastrocopta of the G. 

cristata group with massive folds and lamellae, three 

equally immersed palatal folds adjacent to the palatal 

callus, no subcolumellar lamella, slightly ascending

5 L. scaei'tis, on or toward the left, scala^ flight of stairs.

columellar lamella, and relatively steeply inclined suture.

Description. The shell is so similar to G. paracristata that it can be described best by comparison. 

It differs from G. paracristata by its sinistral coiling, 

more steeply inclined suture, and gradually ascending 

columellar lamella.

Measurements. The mean of the 11 whole specimens in the type series is followed by the range in 

parentheses. Measurements are in millimeters. 

Length, 2.82 (2.6-2.9) ; length of aperture, 0.97 (0.9- 

1.0); width, 1.28 (1.2-1.3); width of aperture, 0.88 

(0.8-0.9); number of whorls, 5.7 (51/4-6).

Variation. G. scaevoscala seems relatively invariable, but this may be an artifact of small sample size. 

Observed variation is like that in G. paracristata: in 

size (see measurements), prominence of basal fold 

and crest, and in degree of fusion of the anguloparietal 

lamella.

Distribution. Latest Pliocene and early Pleistocene 

of southern Kansas.

Remarks. The record of sinistral Gastrocopta paracristata in the Kexroad local fauna (Franzen and 

Leonard, 1947, p. 347) is almost certainly based on 

G. scaevoscala from the Bender local fauna. University of Michigan collections from both assemblages 

contain the sinistral G. scaevoscala from the Bender 

local fauna only. University of Kansas material 

reported from the SWl/4 sec. 22, T. 33 S., K. 29 W., 

Rexroad Ranch, Meade County, is largely from 

Bender localities la, Ib, and le, according to C. W. 

Hibbard (written communication Nov. 29, 1954), 

who helped collect the fossils.

G. scaevoscala is apparently the only sinistral species 

of Gastrocopta (s. s.), although the subgenera Immersidens and Sinalbinula have such forms. The similarity to G. paracristata suggests it is a species derived 

through mutation in direction of coil, and so reproductively isolated. The differences indicated in the 

description are minor, but constant, so that it is difficult to regard the specimens from the Bender local 

fauna simply as sinistral individuals of G. paracristata. Furthermore, G. scaevoscala occurs in the 

Dixon local fauna unaccompanied by G. paracristata.

Occurrence and material: Bender and Dixon local faunas. 

Bender loc. 1, UMMZ 184320 (1) ; loc. la, UMMZ 184125 (9, 

only 4 whole) ; loc. le, UMMZ 183017 (13, only 7 whole) ; 

Dixon loc. 2, UMMZ 191522 (6).

Gastrocopta (s. s.) chauliodonta Taylor, 1954

Plate 1, figures 11-16

(rastroeopta ehauliodonta Taylor, 1954, Michigan Univ. Mus.

Zool. Occ. Papers 557, p. 12, 15.

Types. Holotype LTMMZ 181120, Sand Draw loc. 6. Paratypes UMMZ 181121 (11).
SYSTEMATIC DESCRIPTIONS 71

Diagnosis. A species most closely related to the 

lower Pliocene Gastrocopta lavernensis Taylor and to 

the Recent G. curacoana Pilsbry. It is characterized by 

the massive anguloparietal lamella which almost hides 

the deeply immersed palatal folds, the descending columellar lamella, the absence of a subcolumellar lamella, and the relatively broad, cylindrical form.

Description of types. Shell small, cylindric, rimate; 

apex obtuse. About 5^ whorls, convex, slowly and 

regularly enlarging; sutures strongly impressed; body 

whorl less than half of total shell length, about onehalf whorl behind aperture becoming flattened and 

then slightly concave in the middle of the outer 

side, convex again at a prominent, rounded crest just 

behind the reflected peristome. Sculpture of nuclear 

whorl minutely granular; postnuclear sculpture of 

fine, irregular, oblique growth lines. Aperture 

slightly oblique, rounded, with dentition of five folds 

and lamellae, as follows: a prominent, massive, sinuous anguloparietal lamella, gradually increasing in 

height and terminating abruptly, the angular part 

continuous with the parietal lip; a deeply immersed, 

small, lamelliform upper palatal fold of about equal 

length and height; a still more deeply immersed 

(dorsal in position) long, angulate, deeply entering, 

lower palatal fold, of about the same height as the 

upper palatal fold, increasing in height abruptly and 

decreasing gradually, the outer third ascending 

slightly, the inner two-thirds approximately parallel 

to the base and roof of the body whorl; a tubercular 

basal fold immersed equally with, or slightly more 

than, the lower palatal fold; all palatal folds situated 

well behind the palatal callus; columellar lamella 

heavy, elongate, descending the columella to its base. 

Inner and outer lips heavily callused except in the 

conspicuous sinulus.

Measurements. The mean of the 11 whole specimens in the type series is followed by the range in 

parentheses. Measurements are given in millimeters. 

Height, 2.51 (2.2-2.7) ; width, 1.22 (1.1-1.3) ; height 

of aperture, 0,86 (0.7-0.9) ; width of aperture, 0.87 

(0.8-0.9); number of whorls, 51/2 (5-6).

Variation. The anguloparietal lamella varies in 

shape considerably. Usually the angular part is represented by a slightly prominent ridge which gives 

the lamella a sinuous appearance; sometimes this ridge 

is curved toward the outer lip and the lamella is 

bifid, the sinulus almost completely enclosed; occasionally the whole lamella is nearly straight. The 

anguloparietal varies in width also, from about onefourth to one-sixth of the internal width of the aperture. The columellar lamella may enter horizontally,

in which case the inner half turns downward abruptly, 

or it may descend gradually.

Distribution: Lower Pleistocene of the High Plains.

Remarks. Gastrocopta chauUodonta appears most 

nearly related to G. lavernensis Taylor, 1954, from the 

Pliocene of Oklahoma, and G. curacoana Pilsbry, 1924, 

living in the Dutch West Indies. It differs from the 

former by its more massive lamellae and peristome 

callus, simpler anguloparietal lamella, more deeply 

immersed basal fold, and lamelliform upper palatal 

fold. It differs from G. curacoana (see Pilsbry, 1922- 

26, p. 202-204) by its less tapering shape and more 

conspicuous anguloparietal lamella.

The long, deeply immersed low^er palatal fold and 

the descending columellar lamella of Gastrocopta 

chauUodonta, G. lavernensis, and G. curacoana might 

be considered evidence indicating close relationship 

with Immersidens, which sometimes has these characters. These species agree with Gastrocopta s. s. in 

the differentiating characters of apertural callus and 

simpler anguloparietal lamellae, however. G. octonaria Pilsbry (1922-26, p. 204-205) is transitional 

from this species group to others of Gastrocopta s. s. 

by having a subcolumellar lamella partially united 

with the columellar. This fact, and the greater development of the columellar lamella in Immersidens, suggests that the descending columellar lamella of the 

G. curacoana group may represent a fusion of columellar and subcolumellar lamellae, whereas in Immersidens the descending columellar lamella originated as 

a unit.

Occurrence and material: Sand Draw, Dixon. and Sanders 

local faunas. Sand Draw loc. 2, USGS 19090-5 (23) ; loc. 3, 

UMMZ 181204 (1): loc. 6, UMMZ 181120 (1), 181121 (11), 

181218 (1) ; loc. 7, UMMZ 177236 (2%) ; Dixon loc. 1, UMMZ 

182215 (13): Sanders loc.'1, UMMZ 182152 (30).

Gastrocopta (s. s.) pellucida hordeacella (Pilsbry), 1890 

Plate 1, figure 28

Gastrocopta pellucida liordeacella (Pilsbry)- Franzen and

Leonard, 1947, Kansas Univ. Sci. Bull., v. 31, p. 349,

pi. 19, fig. 8. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 913, fig. 494 :a-d, 495. 

Pilsbry, 1953, Acad. Nat. Sci. Philadelphia Proc., v. 105,

p. 162.

Distribution. Southern and Baja California (locally) through southeast Colorado and Kansas to 

Florida; south to Sinaloa and Tainpico, Mexico; north 

on the Atlantic Coastal Plain to southern New Jersey 

(Franzen and Leonard, 1947; Pilsbry, 1948, 1953). 

"The northward extension along the Atlantic Coast 

is very narrow, discontinuous so far as known, and
72 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

perhaps mainly confined to the coastal islands" (Pilsbry, 1948, p. 914).

Ecology. Uncertain. From the geographic distribution, frequent occurrence in stream drift in the 

southern Great Plains, and occasional occurrence in 

samples of fossils washed from bulk collections of 

matrix it appears this species may live among the 

grass roots, occasionally even on exposed slopes. So 

far as known, the snail has not been collected alive in 

the Plains.

Occurrence and material: Red Corral, Rexroad, and Dixon 

local faunas. Red Corral, UMMZ 183002 (4) ; Rexroad loc. 

3, UMMZ 183037 (3) ; Dixon loc. 2, UMMZ 191521 (3).

Submenus ALBINULA Sterki, 1892 

Gastrocopta (Albinula) armifera (Say), 1821

Gastrocopta armifera (Say). Franzen and Leonard, 1947,

Kansas Univ. Sci. Bull., v. 31. p. 328, pi. 17, fig. 3-5. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2, 

pt. 2, p. 874, fig. 472 :l-4.

Distribution. Quebec to northern Florida, west to 

the Eocky Mountains (Pilsbry, 1948, p. 875).

Ecology. "Gastrocopta armifera is a gregarious 

species occurring commonly on wooded slopes, near or 

removed from a stream. It is to be found under dead 

wood, limestone rocks, or light cover of leaf mold or 

other debris. O. armifera frequently occurs under 

boards or rocks in gardens" (Franzen and Leonard, 

1947, p. 329). In northern Nebraska it was found 

under logs, barks, and stones in moist grass around 

seepages.

Occurrence and material: Dixon local fauna; Recent in 

northern Nebraska. Dixon loc. 1, UMMZ 182214 (10).

Gastrocopta (Albinula) holzingeri (Sterki), 1889

Gastrocopta liolzingeri (Sterki). Hibbard, 1941, Kansas Univ.

Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 883, fig. 474:4-6, 475. 

Frye and Leonard, 1952. Kansas Geol. Survey Bull. 99,

p. 151. 

Gastrocopta holsinoeri Sterki. Franzen and Leonard, 1947,

Kansas Univ. Sci. Bull., v. 31, p. 333, pi. 18, fig. 2.

Distribution. "Ontario and western New York to 

Helena, Montana, south to Illinois, Kansas, and Albuquerque and Mesilla, New Mexico" (Pilsbry, 1948, 

p. 883).

Ecology. ^Gastrocopta liolzingeri is found on timbered slopes under leaf mold. Although it may occur

in large numbers, it is probably overlooked because of 

its small size * * * In order to remain established 

in northwestern Kansas, as it is doing to some extent, 

it must be tolerant of the hot, dry climatic conditions 

which obtain in the summertime. G. holzingeri is 

not one of the predominating species of the fauna of 

Kansas. According to its general distribution in 

North America, it prefers decidedly cooler climates" 

(Franzen and Leonard, 1947, p. 334-335). In northern 

Nebraska it was found under logs, bark, and stones 

in a moist tall-grass area around seepages.

Occurrence and material: Rexroad local fauna; Saw Rock 

Canyon local fauna (Franzen and Leonard) ; Recent in northern Nebraska. Rexroad loc. 1, UMMZ 183059 (1) ; loc. 2, 

UMMZ 183070 (16); loc. 3, UMMZ 183035 (150).

Subgenus VERTIGOPSIS Sterki, 1893 

Gastrocopta (Vertigopsis) tappaniana (Adams), 1842

Gastrocopta tappaniana (C. B. Adams). Baker, 1938, Nautilus, v. 51, p. 131. 

Franzen and Leonard, 1947, Kansas Univ. Sci. Bull., v.

31, p. 336, pi. 18, fig. 8. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 889, fig. 477 :9. 

Frye and Leonard. 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. k. 

Gastrocopta tappaniana C. B. Adams. Hibbard, 1941, Kansas

Univ. Sci. Bull., v. 27, p. 95.

Hibbard. 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard. 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Gastrocopta tappaniana. McGrew, 1944, Field Mus. Nat. Hist.

Geol. Ser., v. 9, p. 36.

Distribution. "Ontario and Maine to Virginia and 

Alabama, west to South Dakota and Kansas, southwest to Arizona, but not known from the southeastern 

Atlantic states, Virginia to Florida" (Pilsbry, 1948, 

p. 889).

Ecology. "Its most frequent habitat is on shaded 

slopes near streams. However, it has been taken 

from among the grass roots on an unshaded slope near 

a pasture pond" (Franzen and Leonard, 1947, p. 337). 

In northern Nebraska it was found among moist leaves 

or under logs in moist grass near seepages.

Occurrence and material: Saw Rock Canyon, Rexroad, Bender, Sand Draw. Dixon, and Sanders local faunas; Recent in 

northern Nebraska. Saw Rock Canyon, UMMZ 177517 (1), 

177564 (23); Rexroad loc. 2, UMMZ 183072 (20); loc. 3, 

UMMZ 183038 (27) ; loc. 4b, UMMZ 177604 (3), 181053 (1) ; 

Bender loc. 1, UMMZ 177508 (1) ; loc. la, UMMZ 184126 (1) ; 

loc. Ib, UMMZ 184139 (39) ; Sand Draw loc. 3, UMMZ 181205 

(2); loc. 5, UMMZ 181251 (1); loc. 6, CNHM PE3445 (1), 

UMMZ 177436 (15), 181219 (9) ; Dixon loc. 1, UMMZ 182218 

(75) ; loc 2, UMMZ 191523 (32) : Sanders loc. 1, UMMZ 182155 

(150) ; loc. 2, UMMZ 184164 (5) ; loc. 3, 182184 (17).
SYSTEMATIC DESCRIPTIONS 73

Subgenus IMMERSIDENS Pilsbry and Vanatta, 1900

Gastrocopta (Immersidens) rexroadensis Franzen and Leonard,

1947

Plate 1, figure 30

Gastrocopta rexroadensis Franzen and Leonard, 1947, Kansas

Univ. Sci. Bull., v. 31, p. 338, pi. 18, fig. 4, 5. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. e.

Types. Holotype UKMNH 3781, Rexroad loc. 3. Paratypes 

UKMNH.

Diagnosis. An Immersidens with a short, straight, 

oblique parietal lamella placed behind a much smaller 

angular lamella not fused to it, an oblique, descending 

columellar lamella, no basal fold, and a deeply immersed lower palatal fold.

Description of holotype. "Shell small, elongateconic; summit obtuse; rimate; suture sharply incised; 

4% whorls; apical whorls strongly convex, lower 

whorls slightly convex; whorls slowly and regularly 

increasing in size; the l 1/^-nuclear whorls finely 

granular; remaining whorls irregularly and finely 

striate; height of body whorl exceeding one-half of the 

total height, contracted basally and expanding rapidly 

toward the aperture; a prominent, rounded crest 

paralleling the peristome from which it is separated by 

a deep, wide groove; aperture triangularly rounded, 

scarcely oblique, widely expanding; denticles 5; a 

prominent, oblique, arched, deeply immersed parietal 

lamella extending toward the periphery below the 

angular lamella; an elongate, prominent angular 

lamella arising from the peristome, approximate to but 

not fused posteriorly with the parietal lamella; the upper palatal fold immersed, fused with a triangular 

callus on the outer border of the peristome; a prominent, shortly elongate, deeply immersed, oblique lower 

palatal fold; a prominent columellar lamella, entering 

horizontally with the posterior half turned downward; 

margin of peristome very narrowly reflected; ends of 

peristome approaching, connected by a thin callus 

upon the parietal wall" (Franzen and Leonard, 1947, 

p. 338).

Measurements. Franzen and Leonard gave dimensions of five specimens. The mean of these (in millimeters) is followed by the range in parentheses. 

Length, 2.35 (2.25-2.4) ; width, 1.29 (1.25-1.35) ; length 

of aperture, 0.88 (0.8-0.9) ; width of aperture, 0.80 

(0.7-0.9) ; number of whorls, 5.0 (4%-5V4).

Distribution. Late Pliocene of the southern High 

Plains.

Remarks. G. rexroadensis appears most closely related to G-. cochisensis (Pilsbry and Ferriss), G. oligobasodon (Pilsbry and Ferriss), and G. prototypus 

( Pilsbry). It differs from G. cochisensis by the separation of the angular and parietal lamellae, the shorter 

and straight parietal lamella, absence of a basal fold, 

and the fusion of the upper palatal fold with the palatal callus. It differs from G. oligobasodon by the 

separation of the angular and parietal lamellae, obliqueness of the parietal lamella, larger columellar 

lamella, absence of a basal fold, and the fusion of the 

upper palatal fold with the palatal callus. It differs 

from G. prototypus by the separation of the angular 

and parietal lamellae, straight and oblique parietal 

lamella, larger and descending columellar lamella with 

no callus above, more deeply immersed, larger, and 

oblique lower palatal fold, and larger upper palatal 

fold fused with the palatal callus.

Franzen and Leonard (1947, p. 339) considered this 

species closely related to G. bilamellata (Sterki and 

Clapp). It differs from the latter in being shorter and 

relatively broader in shell form; by the shorter and 

simpler angular and parietal lamellae, separate and 

straight, the parietal oblique; the absence of a 

basal fold; the oblique lower palatal; and the less 

deeply immersed upper palatal, fused to the palatal 

callus. The differences between G. rexroadensis and G. 

bilamellata seem greater than those between G. rexroadensis and G. cochisensis, G. oligobasodon, and G. 

prototypus.

Occurrence and material: Saw Rock Canyon local fauna 

(Frye and Leonard) ; Red Corral local fauna; Rexroad local 

fauna (Franzen and Leonard). Red Corral, UMMZ 183004 

(2).

New genus and species?

Description. Shell conical, perforate, apex obtuse. 

Whorls five, convex, separated by well impressed 

suture. Aperture subtrigonal, basally regularly 

rounded, inconspicuously dentate. Folds and lamellae 

five, weak: anguloparietal low, elongate, sinuous; 

columellar elongate-tubercular, entering horizontally; 

basal and lower palatal both low, tubercular, and immersed equally with the columellar; upper palatal 

tubercular, slightly elongate parallel to suture, very 

deeply immersed, dorsal in position; peristome reflected, not thickened; a weak palatal callus 

behind the reflection but in front of the folds. 

Umbilicus small, about one-seventh of the diameter, 

perforate to the apex, slightly covered by body whorl. 

First whorl minutely punctate; later whorls with many 

nearly regular, low, rounded, but relatively coarse 

raised lines between which lie weak growth lines. 

Length, 2.5 mm; width, 1.4; length aperture, 0.8; width 

aperture, 0.7; whorls 5.
74 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Remarks. Only one specimen of this unusual pupillid was found. The weak teeth and palatal callus 

and unthickeiied peristome suggest that it may be not 

quite mature or else that it may be like Gastrocopta 

(Privatula] or Microstele in having reduced dentition. 

Of associated forms Gastroropta tappaniana is closest 

in having a conical shape, but dentition, umbilicus, and 

sculpture are so different that it seems unlikely that, 

the specimen is simply a monstrosity of G. tappaniana. 

Perhaps this individual represents an extinct derivative 

of Gastrocopta (Vertigopsis) with an enlarged umbilicus, paralleling Chae nay-is in that respect. More material is needed for a decision.

Occurrence and material: Sanders local fauna, loc. 3, UMMZ

182187 (1).

Subfamily PUPILLINAE 

Genus PUPOIDES Pfeiffer, 1854

Submenus PTTPOIDES s. s.

Pupoides (s. s.) albilabris (Adams), 1841

Plate 1, figures 36. 37

Pupoides maryinatiis (Say). Hibbard, 1941, Kansas Univ.

Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

p. 408. 

Franzen and Leonard, 1947, Kansas Univ. Sci. Bull., v.

31, p. 370, pi. 21, fig. 3-4. 

Pupoides albilabris (C. B. Adams). Pilsbry, 1948, Acad. Nat.

Sci. Philadelphia Mou. 3. v. 2, pt. 2, p. 921, fig. 499:1-7. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. b. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 15.

Distribution. Maine to the West Indies, west to 

North Dakota, Arizona, and northern Mexico (Pilsbry, 

1948, p. 923).

Ecology. "It lives under stones or at the roots of 

grass, in well-drained but often sunny places; following rains it is sometimes found on trees a few feet 

from the ground" (Pilsbry, 1948).

Occurrence and material: Saw Rock Canyon. Rexroad, Bender, Sand Draw. Dixou. and Sanders local faunas. Saw Rock 

Canyon, UMMZ 177565 (4) ; Rexroad loc. 1, UMMZ 183061 

(14) ; loc. 2, UMMZ 183073 (75) ; loc. 3, UMMZ 183039 (100) ; 

loc. 4a, UMMZ 177571 (22) ; loc. 4b, UMMZ 177605 (80), 181- 

054 (12) ; Bender loc. 1, UMMZ 177509 (23) ; loc. la, UMMZ 

184127 (350) : loc. Ib, UMMZ 184140 (75) ; loc. Ic, UMMZ 

183018 (200) ; loc. 2, UMMZ 184155 (11) : Sand Draw loc. 2, 

UMMZ 184179 (2); loc. 6, UMMZ 177437 (15), 181220 (1); 

Dixon loc. 1. UMMZ 182221 (21) ; loc. 2, UMMZ 191524 (16) ; 

Sanders loc. 1, UMMZ 182158 (500) ; loc. 2. UMMZ 182170 

(53) ; loc. 3, UMMZ 182186 (150).

Submenus ISCHNOPUPOIDES Pilsbry, 1926

Pupoides (Isehnopupoides) inornatus Vanatta, 1915

Plate 1, figure 35

Pupoides inornatus Vanatta. Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Franzen and Leonard, 1947, Kansas Univ. Sci. Bull., v. 31,

p. 374. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mou. 3, v. 2,

pt. 2, p. 926, fig. 499 :10.

Distribution. Only two definitely Recent occurrences are known: Pikes Peak, El Paso County, Colo. 

(Pilsbry, 1948, p. 926); Sidney, Cheyenne County, 

Nebr. (USNM 424028, 363054).

Ecology. Uncertain.

Occurrence and material: Red Corral, Rexroad, and Sand 

Draw local faunas. Red Corral, UMMZ 183005 (1) ; Rexroad 

loc. 2, UMMZ 183074 (16) ; loc. 3, UMMZ 183040 (41) ; Sand 

Draw loc. 2, UMMZ 184180 (2).

Subfamily VERTIGININAE

Genus VERTIGO Miiller, 1774

Vertigo ovata Say, 1822

Vertigo ovata Say. Baker, 1938, Nautilus, v. 51, p. 130.

Franzen and Leonard, 1947, Kansas Univ. Sci. Bull., v.

31, p. 354, pi. 19, fig. 6. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 952, fig. 513 :l-3, 4, 7. 

Vertiao ovata. McGrew, 1944, Field Mus. Nat. Hist. Geol. Ser.,

v. 9, p. 36. 

Vertigo orata (Say). Hibbard, 1954, Michigan Acad. Sci.

Papers, v. 39, p. 343. 

Vertigo hibbardi Baker. Frye and Leonard, 1952, Kansas

Geol. Survey Bull. 99, p. 151 [in part: Kingman County

loc. Not of Baker].

Distribution. Laborador to the West Indies, west to 

Arizona, Utah, Oregon, and Alaska (Pilsbry, 1948, p. 

953).

Ecology. u ***on]y in moist environs afforded by 

shaded slopes near streams and shores of ponds11 

(Franzen and Leonard, 1947, p. 355). In northern Nebraska it was found on sticks and in wet leaves in 

seepages and immediately adjacent to a stream, associated with Carychiiim, Fossa ria, and Pisidium.

Remarks. Frye and Leonard reported V. hibbardi, 

but not V. ova fa. from the Dixon local fauna. University of Michigan collections, however, contain about 

200 specimens of V. ovata, but no V. hibbardi. Furthermore, V. ovata and V. hibbardi have never been 

found together, a fact which suggests ecologic replacement since their geologic ranges overlap. In addition
SYSTEMATIC DESCRIPTIONS 75

the two species are superficially similar, and careful 

examination of the apertural lamellae is necessary for 

their discrimination. The Dixon local fauna reference to V. hibbardi, therefore, is probably based on 

V. ovata. (Compare Frye and others, 1943, p. 42, with 

Franzen and Leonard, 1947, p. 354).

Occurrence and material: Buis Ranch, Sand Draw, Dixon, 

and Sanders local faunas; Recent in northern Nebraska. 

Buis Ranch, UMMZ 181115 (1); Sand Draw loc. 2, UMMZ 

184181 (4) ; loc. 3, UMMZ 181131 (29) ; loc. 4, UMMZ 177326 

(30); loc. 5, CNHM PE3438 (2), UIMNH P6791 (1), UMMZ 

181140 (31), 181235 (100); loc. 6, UMMZ 177438 (8), 181222 

(12) ; loc. 7, UMMZ 177235 (3) ; Dixon loc. 1, UMMZ 182219 

(200) ; loc. 2, UMMZ 191526 (4) ; Sanders loc. 1, UMMZ 182- 

157 (1).

Vertigo hibbardi Baker, 1938 

Plate 1, figures 18-22

Vertigo hibbardi Baker, 1938, Nautilus, v. 51, p. 126. 

Smith, 1940, Kansas Geol. Survey Bull. 34, p. 98. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151 [in part: Meade County loc.].

Leonard, 1957, Illinois Geol. Survey Report of Investigations 201, p. 21, pi. 1, fig. 3. 

Vertigo hibbardi F. C. Baker. Hibbard, 1941, Kansas Univ.

Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Franzen and Leonard, 1947, Kansas Univ. Sci. Bull., v.

31, p. 367, pi. 20, fig. 9, 10.

Types. Holotype UIMNH P6773, Rexroad loc. 3. Paratypes UIMNH P6773 (5), ANSP 169883 (not found).

Diagnosis. A moderately large, ovate Vertigo with 

seven folds and lamellae, the palatals deeply entering, 

the columellar descending and spoon shaped; the body 

whorl flattened laterally and flaring in basal view.

Rexroad loc. 3_____

(3 specimens)_

Saw Rock Canyon.

(7 specimens) _

Variation. The shape of the shell varies from 

ovate to conical, as shown by the measurements. The 

folds and lamellae are relatively stable for pupillids. 

The infrapalatal fold is rarely absent. The inner 

end of the parietal lamella may be bent towards 

either lip, or not at all. Shells from the Saw Rock 

Canyon local fauna are larger than topotypes (see 

measurements), and their apertures are not so nearly 

closed by the dentition. Some topotypes have the 

base trumpetlike when viewed from below, as Baker 

noted, but others are less extreme. The Saw Rock 

Canyon specimens do not have this pronounced constriction in the body whorl.

Description. "Shell moderate in size for the genus; 

ovately conic; rimate; whorls typically 5, convex; 

suture sharply incised; nuclear whorl finely granulose; 

remaining whorls glossy, and finely striate in wellpreserved shells, regularly and rapidly increasing in 

size; body whorl as much as three-fifths of total 

height; aperture biarcuate. expanding toward the peristome; peristome narrowly reflected, margins sharp, 

terminations approaching and connected across parietal wall by a thin callus; denticles 7: 2 elongate lamellae on parietal wall, the parietal lamella the more 

deeply immersed, the innermost third deflected at a 

right angle toward the outer lip; the angular about 

one-third as long as the parietal, less deeply immersed; 

suprapalatal fold, when present, tubercular; upper 

palatal fold lamelliform, high, long and sinuous; 

lower palatal fold lamelliform, more deeply immersed 

than the upper palatal, increasing in height up to 

its midpoint and then declining, partially forked anteriorly ; infrapalatal low, elongate, as deeply immersed, 

and about half as long as the lower palatal; basal 

lamelliform, elongate, increasing in height inwardly 

and terminating rather abruptly; the folds connected 

by a low callus; columellar lamella large, heavy, 

crescentic, ascending slightly toward the columella, 

then turning downward and recurving slightly forward at the base; crest behind the peristome prominent, rounded, separated from the peristome by a 

groove; body whorl indented at level of the upper 

and lower palatals resulting in the contraction of 

the body whorls at its base" (Franzen and Leonard, 

1947, p. 367-368).

Measurements. The mean of the series measured is 

followed by the range in parentheses. Measurements 

are in millimeters.

Length Length aperture Width

2. 00 0. 8 1. 3

(1.9-2.0) (.8) (1.3)

2. 19 . 84 1. 41

(2.0-2.3) (. 7-. 9) (1.3-1.5)

Number of 

Width aperture whorls

0. 77 V/i

(. 7-. 8) (^A)

. 84 4^

(. 8-. 9) (4^-5)

Distribution: Late Pliocene of southwestern Kansas.

Remarks. For discussion of the reported occurrence of V. hibbardi in the Dixon local fauna see 

under V. ovata.

F. C. Baker and subsequent writers who have dealt 

with V. hibbardi have considered it as one of the 

subgeiius Angustula Sterki, 1888. The species has 

most of the characters in the subgeneric definition 

given by Pilsbry (1948, p. 944), but other features 

seem to show that this resemblance is only convergent. 

Furthermore, V. milium (type of Angustula} appears 

to have close relationships with other species which 

are not recognized by present taxonomy.
76 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Vertigo hibbardi agrees with the diagnosis of Angustula (based on apertural dentition) in all respects 

save one: the inner end of the lower palatal fold does 

not curve downward. It differs radically from the 

other species heretofore placed in Angustula by its 

larger size, conical or ovate-conic shape, and laterally 

flattened body whorl. The difference in shape, not 

necessarily significant in all gastropod genera, is 

important because the other species-groups in Vertigo 

have unity in external form, the species differing primarily in lamellar characters. V. hibbardi is probably most closely related to the V. ovata, group, although not nearly. It is similar in shape to species of 

this group, differing slightly by the laterally compressed body whorl. The strongly developed folds 

and lamellae are similar to those of V. ovata diaboli 

Pilsbry (Pilsbry, 1948, p. 953), from which it differs 

in the absence of an infraparietal lamella and in the 

spoonshaped, descending columellar lamella.

The criteria previously used for definition of Angustula therefore seem artificial, because they associate 

otherwise dissimilar and apparently unrelated species. 

But it appears that these characters have also excluded a related species from the V. miliuin group: 

V. numellata. Pilsbry (1918-20, p. 149-150) compared 

V. bermudensis of the V. milium group with V. numellata (then placed in its own species group) as follows: 

"The much larger V. numellata has a similar crest, 

the lower palatal fold is long, also, and the angular 

and parietal lamellae similar in position; yet it has not 

the peculiarly shaped columellar lamella of Angustula" By the same token as used with V. hibbardi. 

it seems that the strictly lamellar characters have resulted in an unnatural grouping of species. From the 

similarities of both dentition and external form, the 

V. milium group includes V. numellata and V. bermudensis, but not V. hibbardi. It appears that a descending columellar lamella has developed more than once 

in Vertigo, Whether Angustula merits subgeneric 

rank seems questionable, if its unique character of a 

descending columellar lamella is no longer unique. It 

seems best to synonymize it with Vertigo s. s., and to 

consider V. milium and its relatives coordinate with 

other species groups, such as those of V. ovata, and 

V. modesta.

Occurrence and material: Saw Rock Canyon and Rexroad 

local faunas. Saw Rock Canyon, UMMZ 173589 (10), 177566 

(400), USGS 39089-6 (125), Rexroad loc. 2, UMMZ 183075 

(3) ; loc. 3, UMMZ 183041 (11), UIMNH P6773 (6).

Vertigo milium (Gould.), 1840

Vertigo milium Gould. Hibbard, 1941, Kansas Univ. Sci. Bull.,

v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Leonard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151. 

Vertigo milium (Gould). Franzen and Leonard, 1947, Kansas

Univ. Sci. Bull., v. 31, p. 365, pi. 20, fig. 8. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 944, fig. 509. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 15.

Distribution. Maine to South Dakota, south to Arizona, Mexico, and the West Indies (Pilsbry, 1948, p. 

945).

Ecology. "Moist situations afforded by timbered 

stream banks, or marshes. It is not found in areas of 

low relative humidity or low annual precipitation and 

high summer tempertures * * *" (Franzen and Leonard, 1947, p. 367).

Occurrence and material: Red Corral, Rexroad, Bender, Sand 

Draw, Dixon, and Sanders local faunas; Saw Rock Canyon 

local fauna (Franzen and Leonard). Red Corral, UMMZ 

183006 (27) ; Rexroad loc. 2, UMMZ 183076 (15) ; loc. 3, 

UMMZ 183042 (57) ; loc. 4b, UMMZ 177606 (1), 181055 (2) ; 

Bender loc. 1, UMMZ 177510 (15) ; loc. la, UMMZ 184128 

(75) ; loc. Ib, UMMZ 184141 f3) ; loc. Ic, UMMZ 183019 (75) ; 

Sand Draw loc. 2, UMMZ 184182 (2) ; loc. 3, UMMZ 181132 

(7); loc. 4, UMMZ 177325 (2); loc. 5, UMMZ 181141 (4), 

181234 (18) ; loc. 6, UMMZ 177439 (1), 181221 (20) ; Dixon loc. 

1, UMMZ 182220 (100) ; loc. 2, UMMZ 191525 (25) ; Sanders 

loc. 1, UMMZ 182156 (500) ; loc. 2, UMMZ 182169 (5) ; loc. 

3, UMMZ 182185 (500).

Family PUPILLIDAE?

Remarks. A fragmentary specimen consisting of the 

apical whorls only may represent a pupillid. It is 

distinct from the other species listed from the local 

fauna.

Occurrence: Red Corral local fauna. UMMZ 183000 (1).

Family VALLONIIDAE

Genus VALLONIA Risso, 1826

Vallonia pulchella (Miiller), 1774

Valloma pulohella (Miiller). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 2, p. 1023, fig. 545a. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557, 

p. 15.

Distribution. Holarctic. In North America east of 

the Rocky Mountains from Nova Scotia and Manitoba 

south to Missouri and Kentucky (Pilsbry, 1948, p. 

1024).
SYSTEMATIC DESCRIPTIONS 77

Ecology. "Found plentifully under wood, leaves, 

stones, old logs, in moss and on the banks of streams" 

(Baker, 1902, p. 251).

Occurrence and material: Sand Draw local fauna. Sand 

Draw loc. 3, UMMZ 181133 (6) ; loc. 6, UMMZ 181223 (1).

Vallonia gracilicosta Reinhardt, 1883

Vallonia gracilicosta Reinhardt. Hibbard. 1941, Kansas Univ.

Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 2, p. 1028, fig. 549. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. f.

Distribution. Minnesota to Montana, south and 

southwest to Nebraska, New Mexico, Arizona, and 

California (Pilsbry, 1948, p. 1029-1030).

Ecology. In northern Nebraska this species occurs 

under logs, bark, and stones on slightly moist leaf 

mold in wooded areas.

Occurrence and material: Rexroad local fauna; Recent in 

northern Nebraska. Rexroad loc. 3, UMMZ 183043 (1800).

Vallonia parvula Sterki, 1893

Vallonia parvula Sterki. Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 1027, fig. 547.

Distribution. Great Plains from South Dakota to 

north-central Oklahoma; eastward to northern Missouri, northern Ohio, southern Ontario, and western 

New York.

Ecology. In northern Nebraska V. parvula occurs 

under logs, bark, and stones on slightly moist leaf 

mold in wooded areas.

Occurrence and material: Bender local fauna; Recent in 

northern Nebraska. Bender loc. la, UMMZ 184129 (31) ; loc. 

Ic, UMMZ 183020 (1).

Vallonia perspectiva Sterki, 1893

Vallonia perspectiva Sterki. Pilsbry, 1948, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 2, p. 1033, fig. 553.

Distribution. Sparsely recorded from New Jersey 

and Alabama to the Rocky Mountains. More abundant in Arizona and New Mexico; Chihuahua (Pilsbry, 1948, p. 1034).

Ecology. Uncertain.

Occurrence and material: Saw Rock Canyon, Rexroad, 

Dixon, and Sanders local faunas. Saw Rock Canyon, UMMZ 

177567 (2) ; Rexroad loc. 2, UMMZ 183077 (29) ; loc. 3, UMMZ 

183044 (150) ; Dixon loc. 1, UMMZ 182222 (1) ; Sanders loc. 

1, UMMZ 182159 (150); loc. 2, UMMZ 184165 (1); loc. 3, 

UMMZ 182188 (1).

Family CIONELLIDAE 

Genus CIONELLA Jeffreys, 1829 

Cionella lubrica (Miiller), 1774

Cionella lubrica (Miiller). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 2, p. 1047. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, 

p. 151.

Distribution. Holarctic. "Point Barrow, Alaska, 

and Queen Charlotte Islands to Labrador and Newfoundland, south in the East to Washington, D.C., and 

southern Missouri; in all the Western and Mountain 

States except California; to the Mexican boundary 

in Arizona; in the Sierra Madre of western Chihuahua." (Pilsbry, 1948, p. 1048; see also Pilsbry, 1953, 

p. 165).

Ecology. "(7. lubrica lives among the damp underleaves in densely shaded places; under wood, such as 

old board sidewalks; in chinks of stone walls and 

under stones" (Pilsbry, 1948, p. 1049). In northern 

Nebraska it was found among damp leaves and small 

logs in a wooded ravine.

Occurrence: Rexroad or Bender local fauna (Frye and 

Leonard) ; Recent in northern Nebraska.

Family STTCCINEIDAE

Land snails of the family Succineidae are common 

and often conspicuous members of the Recent molluscan fauna of the central Great Plains. Their 

shells are likewise common as fossils in both Pliocene 

and Pleistocene deposits of this region. Even the 

best preserved fossils may be unidentifiable, however, 

because the shells alone are often not specifically 

diagnostic. After studying the Succineidae of Kansas, 

Miles (1958) found that most species can not be identified by shell characters, and that two of the three 

genera are indistinguishable from their shells. Oxyloma, with the one species Oxyloma retusa in Kansas, 

may be distinguished from Succinea and Quickella; 

Succinea ovalis and adult specimens of Succinea concordialis can be identified by shell features; but the 

other species of Succinea and Quickella must be determined by anatomical criteria.

The fossil succineid shells considered in this paper 

include only one of the specifically identifiable types: 

Oxyloma retusa. At least for the present, all others 

are lumped as "cf. Succinea" Perhaps future detailed 

study of the shells of dissected Recent snails will 

enable more of the fossils to be identified specifically.
78 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Genus SUCCINEA Draparnaud, 1801 

Succinea ovalis Say, 1817

Sttccinea ovalis Say. Pilsbry, 1948, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 801, fig. 430-433.

Distribution. "Newfoundland and James Bay to 

North Dakota and Nebraska, south to Alabama" 

(Pilsbry, 1948, p. 803).

Ecology. "S. ovalis is usually found on low ground 

near streams, in summer often upon the weedy herbage 

of such places, a foot or two from the ground" (Pilsbry, 1948, p. 804). In northern Nebraska it was 

found under logs among damp leaves, in a wooded 

ravine well above the flood-plain of the Niobrara 

River.

Remarks. The locality in northern Brown County, 

Nebraska, recorded in this paper is farther southwest 

than previously known occurrences.

Occurrence: Recent in northern Nebraska.

cf. Succinea

Succinea grosvenori Lea. Hibbard, 1941, Kansas Univ. Sei.

Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151. 

Succinea grosvenori gelidu F. C. Baker. Hibbard, 1941,

Kansas Univ. Sci. Bull., v. 27, p. 95. 

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38,

p. 408. 

Succinea sp. Taylor, 1954, Michigan Univ. Mus. Zool. Occ.

Papers 557, p. 15.

Occurrence: Saw Rock Canyon, Red Corral, Rexroad, Bender, Sand Draw, Dixon, and Sanders local faunas: Recent in 

northern Nebraska.

Discussion of materials. Saw Rock Canyon, IJMMZ 

172363 (12), 1T7568 (200), ITSGS 19089-7 (17). Three 

fairly large specimens have short spires, elongate apertures, and slightly impressed sutures. These shells 

agree well with Succinea concordialis Gould (Pilsbry, 

1948, p. 833).

Red Corral, UMMZ 183007 (1). The single juvenile 

specimen is indeterminate.

Rexroad loc. 1, UMMZ 183062 (54) ; loc. 2, UMMZ 

183078 (10) ; loc. 3, UMMZ 183045 (300) ; loc. 4b, 

UMMZ 177607 (6), 181057 (1). About a dozen specimens from locality 3 may be only half grown. They 

differ from the Saw Rock Canyon material in having 

a narrow shell, relatively large pointed spire with 

moderate suture, and smaller, ovate aperture. These 

specimens resemble S. grosvenori gelida and 8. avara 

in having a relatively prominent spire and small aperture, but differ by their narrower spire and shallower 

suture. They are closest to 8. luteola Gould (Pilsbry, 

1948, p. 830). One other specimen from locality 4b 

is of similar form, but the remaining Rexroad material is indeterminate.

Bender loc. 1, UMMZ 177511 (5) ; loc. la, UMMZ 

184130 (32) ; loc. Ic, UMMZ 183021 (9); loc. 2, UMMZ 

184156 (75). Seven adult specimens from locality 2 

show considerable variation in proportions, but share 

a high, narrow spire, moderately deep suture, and 

fairly smooth shell surface. They are higher spired 

and narrower than the Saw Rock Canyon specimens, 

similar to the Rexroad locality 3 material, and may 

represent Succinea luteola Gould also. Bender locality 1 material is not diagnostic.

Sand Draw loc. 1, UMMZ 181248 (7) ; loc. 2, UMMZ 

184183 (13); loc, 3, UMMZ 181130 (34); loc. 4, 

UMMZ 177324 (10); loc. 5, UMMZ 181139 (45), 

181236 (150) ; loc. 6, UMMZ 177434 (11), 181224 (7) ; 

loc, 7, UMMZ 177234 (21). Almost all the material 

is indeterminate. One specimen from locality 1 and 

two from locality 6 (UMMZ 177434) are similar to 

the Rexroad material.

Dixon loc, 1, UMMZ 182223 (7); loc. 2, UMMZ 

191527 (12). The few immature specimens collected 

are closer to the Rexroad than to the Saw Rock 

Canyon material.

Sanders loc. 1, UMMZ 182160 (500); loc. 2, UMMZ 

184166 (10); loc, 3, UMMZ 182189 (44). About a 

dozen adult specimens, and others nearly adult, show 

considerable variation in spire and aperture proportions. They overlap the Rexroad locality 3 material, 

but are mostly slightly lower spired. These also are 

like S. luteola Gould. Sanders locality 3 specimens 

are not determinable, but seem conspecific,

Genus OXYLOMA Westerlund, 1885 

Oxyloma retusa (Lea), 1834

Oxyloma retusa (Lea). Pilsbry, 1948, Acad Nat. Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 785, fig. 421, 422c. 

Miles, 1958, Kansas Univ. Sci. Bull., v. 38, p. 1521, pi. 1, 

fig. G, H: fig. 6, 7.

Oxyloma haydeni (W. G. Binney). Pilsbry, 1948, Acad. Nat. 

Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 797, fig. 427e.

Distribution. Ohio west to Montana, south to Kansas. If Oxyloma siHimani is a synonym, as suggested 

by Pilsbry (1948, p. 796), the range may include 

parts of Nevada and Washington.

Ecology. In northern Nebraska this species was 

always found within about 6 inches of permanent 

water, crawling about on dead wood or among riparian vegetation and debris. Although not strictly 

aquatic, its habitat overlaps that of the semiaquatic
79

Fossaria dalli. In Meade County State Park, Kansas, 

"this snail thrives on the moist marshes and borders 

of the pools in the artesian basin, where it is frequently 

found on watercress' 1 (Leonard, A. E., 1943, p. 240). 

Remarks. Miles (1958) has demonstrated the great 

variation in shell form of Oxyloma retusa, even within 

single populations. The original illustrations of Oxyloma haydeni (Pilsbry, 1948, p. 796, fig. 427e) show 

striking resemblance to those of established 0. retusa 

(Miles, 1958, p. 1537, pi. 1, fig. H). 0. haydeni was 

originally distinguished by shell features which are 

evidently invalid.

Occurrence and material: Dixon local fauna; Recent in 

northern Nebraska. Dixon loc. 1, UMMZ 182212 (37) ; loc. 2, 

UMMZ 191528 (27).

Family ENDODONTIDAE

Subfamily ENDODONTINAE

Genus DISCUS Fitzinger, 1833

Subgenus DISCUS s. s. 

Discus (s. s.) cronkhitei (Newcomb), 1865

Discus cronkJtitei (Newcomb). Pilsbry, 1948, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 2, p. 601, fig. 328a-d.

Distribution. Alaska to the mountains of southern 

California; Rocky Mountains south into Arizona and 

New Mexico; Colorado and northern Canada east to 

northern Illinois, Maryland, Newfoundland, and 

Labrador; also Missouri (Pilsbry, 1948, p. 602-603).

Ecology. "In the east it lives in humid forest, 

under dead wood, and among rotting leaves or grass 

in rather wet situations1 ' (Pilsbry, 1948, p. 604). In 

northern Nebraska it occurred under sticks and logs 

on moist leaf mold, always close to running water.

Remarks. The localities in northern Nebraska reported in this paper are the most southern known 

Recent occurrences of this species in the High Plains.

Occurrence: Recent in northern Nebraska.

Subfamily HELICODISCINAE 

Genus HELICODISCUS Morse, 1864

Subgenus HELICODISCUS s. s. 

Helicodiscus (s. s.) parallelus (Say), 1821

Helicodiscus parallel us (Say). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3. v. 2, pt. 2, p. 625, fig. 338c, 339. 

Leonard and Goble. 1952, Kansas Univ. Sci. Bull., v. 34, 

p. 1039. pi. 101, fig. 24, 25.

Distribution. Eastern North America, from Newfoundland south to Georgia and Alabama; westward 

to South Dakota and Oklahoma (Pilsbry, 1948, p. 

626).

Ecology. "It lives on decaying wood in shady or 

humid places, also on damp leaves" (Pilsbry, 1948, 

p. 627). "In eastern Kansas the species may occur 

in grassy fields, on sparsely timbered slopes, and on 

rocky ledges as well as in more moist places. In the 

more arid parts of the state, however, H. parallelus 

is limited to woodland cover, and usually occurs 

around decaying timber1 ' (Leonard and Goble, 1952, 

p. 1039).

Occurrence and material: Dixon local fauna. Dixon loc. 2, 

UMMZ 191529 (18).

Subgenus HEBETODISCUS Baker, 1929 

Helicodiscus (Hebetodiscus) singleyanus (Pilsbry), 1890

Helicodiscus singleyanus Pilsbry. Hibbard, 1941, Kansas Univ.

Sci. Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Helicodiscus sinyleyanus (Pilsbry). Pilsbry, 1948, Acad. Nat.

Sci. Philadelphia Mon. 3, v. 2, pt. 2, p. 636, fig. 346. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, 

p. 151.

Distribution. NewT Jersey to Florida, west to South 

Dakota, Colorado, and Arizona (Pilsbry, 1948, p. 

636).

Ecology. This species has apparently never been 

collected alive in the High Plains. In southwestern 

Kansas fresh shells have been found frequently by 

University of Michigan field parties in the course 

of collecting fossils by washing bulk matrix through 

screens. In this process any Eecent shells which may 

be present are recovered along with the fossils. From 

the localities so represented, it appears probable that 

Helicodiscus singleyanus lives among grass roots, even 

on exposed slopes that become hot and dry during 

the summer.

Occurrence and material: Saw Rock Canyon, Rexroad. Bender, Sand Draw, Dixon, and Sanders local faunas. Saw Rock 

Canyon, UMMZ 181289 (2) ; Rexroad loc. 2, UMMZ 183079 

(7) : loc. 3, UMMZ 183046 (500) ; loc. 4b, UMMZ 181287 (20) ; 

Bender loc. 1, UMMZ 181288 (24) ; loc. la, UMMZ 184131 

(38) ; loc. Ib, UMMZ 184142 (300) ; loc. Ic, UMMZ 183022 

(100) ; loc. 2, UMMZ 184157 (5) ; Sand Draw loc. 2, UMMZ 

184184 (4) ; Dixon loc. 2. UMMZ 191530 (400) ; Sanders loc. 

2. UMMZ 182171 (100) ; loc. 3, UMMZ 182190 (3).

Subfamily PUNCTINAE

Genus PUNCTUM Morse, 1864

Punctum minutissimum (Lea), 1841

Punctum minutissimum (Lea). Pilsbry, 1948, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 2, p. 644, fig. 350.

Distribution. Newfoundland to Florida, w^est to 

Oregon, Colorado, New Mexico, and Puebla, Mexico 

(Pilsbry, 1948, p. 644-645).
80 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Ecology. "This dwarf among pygmies lives on 

damp leaves, around decaying logs, and is chiefly 

to be obtained by sifting leaves, according to my experience. Morse states that [in Maine] 'dense, hardwood growths appear to be their favorite position. 

They prefer the rotten bark of beech trees, and frequently are found in the large forms of fungi, such 

as Polyporus and Boletus.'" (Pilsbry, 1948, p. 645). 

In northern Nebraska it was taken among moist leaves 

beside a spring-fed brook.

Occurrence: Recent in northern Nebraska.

Family LIMACIDAE 

Genus DEROCERAS Rafinesque, 1820

Subgenus uncertain

Deroceras aenigma Leonard, 1950

Plate 4, figures 14-16, 19-26

Deroceras aenigma Leonard, 1950, Kansas Univ. Paleont.

Contr. 8, p. 38, pi. 5, fig. E. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151, pi. 14, fig. e. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 6, 15. 

Hibbard, 1956, Michigan Acad. Sci. Papers, v. 41, p. 171.

Distribution. Upper Pliocene to upper Pleistocene 

in the High Plains (Taylor, 1954a).

Ecology. Like living species of Deroceras, D. aenigma probably favored damp riparian habitats.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, Sand Draw, Dixon, Deer Park, and Sanders 

local faunas. Saw Rock Canyon, UMMZ 172365 (1), 177569 

(125, 2 sinistral), USGS 19089-10 (17); Red Corral, UMMZ 

183008 (50) : Rexroad loc. 1, UMMZ 183063 (40) ; loc. 2, 

UMMZ 183080 (5) ; loc. 3, UMMZ 183047 (400) ; loc. 4a, 

UMMZ 177442 (500), 177572 (500); loc. 4b, UMMZ 177608 

(2) ; Bender loc. 1, UMMZ 177513 (5) ; loc. la. UMMZ 184132 

(100) ; loc. Ic, UMMZ 183023 (100) ; Sand Draw loc. 1, UMMZ 

181249 (6) : loc. 3, UMMZ 181206 (2) ; loc. 4, UMMZ 177327 

(100) ; loc. 6, UMMZ 177440 (10) ; loc. 7, UMMZ 177238 (3) ; 

Dixon loc. 1, UMMZ 182224 (75) ; loc. 2, UMMZ 191531 (6) ; 

Deer Park, UMMZ 185798 (65) ; Sanders loc. 1, UMMZ 182161 

(57) ; loc. 2, UMMZ 182172 (3) ; loc. 3, UMMZ 182191 (24).

Family ZONITIDAE

Subfamily EUCONULINAE

Genus EUCONULUS Reinhardt, 1883

Euconulus fulvus (Miiller), 1774

Euconulus fuJwis (Miiller). Pilsbry, 1946, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 1, p. 235, fig. 116, 117.

Distribution. "Almost throughout the Holarctic 

realm, but wanting in the Gulf and South Atlantic

States from Texas to North Carolina" (Pilsbry, 1946, 

p. 236).

Ecology. UE. fulvus lives among damp leaves in 

well-shaded places, and may usually be obtained by 

leaf sifting where its presence wT ould otherwise be 

unsuspected" (Pilsbry, 1946, p. 236). In northern 

Nebraska it was found in damp leaves or under logs 

and bark on moist ground.

Occurrence: Recent in northern Nebraska.

Subfamily ZONITINAE

Genus NESOVITREA Cooke, 1921

Subgenus PERPOLITA Baker, 1928

Nesovitrea (Perpolita) electrina (Gould), 1841

Retinella electrina (Gould). Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408. 

Pilsbry, 1946, Acad. Nat. Sci. Philadelphia Mon. 3, v. 2,

pt. 1, p. 256, fig. 126. 

Leonard, 1950, Kansas Univ. Paleont. Contr. 8, p. 36, pi.

5, fig. H. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, p.

151, pi. 14, fig. 1. 

Nesovitrea (Perpolita) electrina (Gould). Forcart, 1957,

Archiv fur Molluskenkunde, v. 86, p. 110.

Distribution. North America north of about lat 

38° N., southward in the Rocky Mountains to Arizona 

and New Mexico.

Ecology. "Retinella electrina, is an inhabitant of 

woodlands where it lives in decaying leaves, beneath 

loosened bark on dead trees and under sticks and fallen 

logs. It is frequently associated with another woodland snail (Zonitoides arboreus) of similar size and 

superficial appearance. R. electrina, is common in the 

woodlands of eastern Kansas, where the annual rainfall is generally more than 35 inches but it declines 

in frequency of occurrence toward the more arid 

Plains Border province, and is unknown in the Plains 

province, even where timber is locally available" 

(Leonard, 1950, p. 37). In northern Nebraska it was 

found only under dead wood or among leaves on damp 

ground close to running w^ater.

Occurrence and material: Rexroad local fauna; Dixon local 

fauna (Frye and Leonard) ; Recent in northern Nebraska. 

Rexroad loc. 3, UMMZ 183049 (75).

Nesovitrea? sp.

Remarks. A single juvenile shell is indeterminate. 

It may represent one of the species of Retinella in the
SYSTEMATIC DESCRIPTIONS 81

Rexroad local fauna, but perhaps more likely Nesovitrea electrina.

Occurrence and material: Saw Rock Canyon local fauna, 

UMMZ 183010 (1).

Genus RETINELLA Fischer, 1877

Subgenus GLYPHYALUS Baker, 1928

Retinella (Glyphyalus) wheatleyi (Bland), 1883

Retinella wheatleyi Bland. Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408.

Retinella wheatleyi (Bland). Pilsbry, 1946, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 1, p. 272, fig. 134, 141:1-3.

Distribution. Sporadically from Rhode Island and 

North Carolina west to Michigan, Missouri, and northern Alabama (Pilsbry, 1946, p. 272-273).

Ecology. In Knox County, Tenn., "Even in the 

spring, it was rare except in a shallow valley on the 

west-facing (more humid) slope of the ridge, where 

one or two individuals per square meter were obtained 

under the decaying leaves in the oak-chestnut woods" 

(Baker, quoted in Pilsbry, 1946, p. 273).

Occurrence: Rexroad local fauna (Hibbard).

Submenus GLYPHYALOPS Baker, 1928 

Retinella (Glyphyalops) rhoadsi (Pilsbry), 1899

Retinella rhoadsi Pilsbry. Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 9o.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408.

Retinella rhoadsi (Pilsbry). Pilsbry, 1946, Acad. Nat. Sci. 

Philadelphia Mon. 3, v. 2, pt. 1, p. 286, fig. 145.

Distribution. Maine to North Carolina, west to 

Michigan (Pilsbry, 1946, p. 286) ; Jackson County, 

111. (Baker, 1939, p. 70).

Ecology. Uncertain; presumably similar to that 

of R. wheatleyi.

Occurrence: Rexroad local fauna (Hibbard).

Genus HAWAIIA Gude, 1911 

Hawaiia minuscula (Binney), 1840

Hawaii miniscula Binney. Hibbard, 1941, Kansas Univ. Sci.

Bull., v. 27, p. 95.

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408.

Hawaiia minuscula (Binney). Pilsbry, 1946, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 1, p. 420, fig. 228a, b,

229:l-3. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99,

p. 151, pi. 14, fig. m. 

Taylor, 1954, Michigan Univ. Mus. Zool. Occ. Papers 557,

p. 15.

Distribution. North America from Alaska and 

Maine to Costa Rica. "It is generally spread over 

every eastern and midwestern state, and in Florida as 

far south as Miami and Cape Sable, though not seen 

from the keys. It becomes rather local in the Rocky 

Mountain States, and has not been seen from Washington, Oregon, Idaho, Nevada and Utah, and only 

towards the south in California, where some of the 

records are probably owing to importation with 

plants" (Pilsbry, 1946, p. 421-423).

Ecology. The wide geographic range of this common snail is correlated with adaptability to various 

habitats. In northeastern Kansas, Franzen and Leonard (1943) found that it "* * * is a common snail in 

the Wakarusa valley, where it lives in rocky ledges 

or among dead leaves and under fallen logs. It 

thrives in piles of moist drift where it has been cast 

by flood waters." In Meade and Clark counties, Kansas, "This species is widely distributed over the area, 

being nowhere numerous. It withstands arid conditions successfully but is most numerous in wooded 

places where moisture conditions are better than on 

the treeless prairies" (Leonard, A. E., 1943, p. 238). 

In northern Nebraska it was found under logs and 

bark on damp ground near running water.

Occurrence and material: Saw Rock Canyon, Red Corral, 

Rexroad, Bender, Sand Draw, Dixon, and Sanders local 

faunas; Recent in northern Nebraska. Saw Rock Canyon, 

UMMZ 173592 (1); 177570 (34); Red Corral, UMMZ 183009 

(4) ; Rexroad loc. 1, UMMZ 183064 (11) ; loc. 2, UMMZ 183- 

081 (200) ; loc. 3, UMMZ 183048 (1000) ; loc. 4b, UMMZ 177609 

(200), 181058 (125) ; Bender loc. 1, UMMZ 177512 (285) ; loc. 

la, UMMZ 184133 (3200) ; loc. Ib, UMMZ 184143 (150) ; loc. 

Ic, UMMZ 183024 (1600); loc. 2, UMMZ 184158 (60); Sand 

Draw loc. 1, UMMZ 181250 (2) ; loc. 2, UMMZ 184185 (6) ; 

loc. 3, UMMZ 181207 (2) ; loc. 6, UMMZ 177441 (8) ; 181225 

(1) ; loc. 7. UMMZ 177237 (12) ; Dixon loc. 1, UMMZ 182225 

(49) ; loc. 2, UMMZ 191532 (150) ; Sanders loc. 1, UMMZ 182- 

163 (600) ; loc. 2, UMMZ 182173 (26) ; loc. 3, UMMZ 182192 

(300).

Subfamily GASTRODONTINAE

Genus ZONITOIDES Lehmann, 1862 

Zonitoides (s. s.) arboreus (Say), 1816

Zonitoides arltoreiix (Say). Pilsbry, 1946, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 1, p. 480, fig. 261, 262. 

Frye and Leonard, 1952, Kansas Geol. Survey Bull. 99, 

p. 151, pi. 14, fig. p.

Distribution. North America from northern Canada to Costa Rica (Pilsbry, 1946, p. 481).

50894S O 6C
82 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

Ecology. "* * * occurs in woodlands, living under 

loosened bark, leaves, and stones, and other cover 

affording protection from the sun, and providing at 

least moderate moisture" (Leonard, 1950, p. 37). In 

northern Nebraska it was found under logs and bark 

and among leaves on damp ground, usually in wooded 

areas.

Occurrence: Rexroad or Bender and Dixon local faunas 

(Frye and Leonard) ; Recent in northern Nebraska.

Family POLYGYBIDAE

Subfamily POLYGYBINAE

Genus POLYGYRA Say, 1818

Subgenus ERYMODON Pilsbry, 1956

Polygyra (Erymodon) rexroadensis 6 Taylor, n. sp.

Plate 1, figures 17, 23; Plate 2, figures 4, 5

Polygyra mooreana tholus (Binney). Hibbard, 1941, Kansas

Univ. Sci. Bull., v. 27, p. 95 [not of Binney]. 

Hibbard, 1941, Kansas Acad. Sci. Trans., v. 44, p. 265

[not of Binney]. 

Frye and Hibbard, 1941, Kansas Geol. Survey Bull. 38, p.

408 [not of Binney].

Polygyra mooreana (Binney). Frye and Leonard, 1952, 

Kansas Geol. Survey Bull. 99, p. 151, pi. 14, fig. v [not 

of Binney].

Types. Holotype UMMZ lTT610a, Kexroad loc. 4b. 

Paratypes: UMMZ 177610 (1) ; 183050 (4), loc. 3; 

183082 (2), loc. 2.

Diagnosis. A Polygyra of the P. texasiana group 

characterized by its weak axial sculpture, spiral striae, 

high and asymmetrical parietal tooth, and absence of 

columellar tubercle.

Description of types. Shell depressed, plane or with 

low spire above; periphery rounded; whorls 5, 

strongly descending to aperture; umbilicus at first 

steep sided, perforate to apex, expanding in last whorl 

to about one-third of shell diameter, with a shallow 

groove parallel to suture for last half whorl; aperture 

semicircular except for dental barrier; outer lip thickened, reflected following marked constriction of body 

whorl, bearing 2 laterally compressed teeth of equal 

size separated by deep sinus; from each tooth a broad, 

thick, ridge extends toward lip insertions; parietal 

callus bearing a large, asymmetrical biramose tooth 

opposite palatal teeth; branch toward columella about 

4 times as long as that toward the upper lip insertion, 

straight, high and even for nearly two-thirds its 

length, descending sharply toward columella; no columellar tubercle; first (embryonic) whorl with fine 

growth lines, becoming coarse and irregular on later

6 Named for its occurrence in the Rexroad local fauna.

whorls, slightly coarsening behind lip; umbilical side 

of whorls with numerous, raised, dotlike papillae; last 

whorl with fine, close, irregular, wavy, impressed, 

spiral striae. Measurements in millimeters: paratype 

(UMMZ 183050) diameter 9.5, height 4.5, whorls 5; 

holotype diameter 7.8, height 4.0, whorls 5.

Variation. The spire height varies slightly, but 

not as much as the measurements might indicate. The 

holotype has a relatively high body whorl and a low 

spire, rather than a much higher spire than the 

measured paratype. Umbilical width varies from a 

little more than one-third shell diameter (paratype) 

to one-fourth (holotype). The inner, permeable portion of the umbilicus varies correspondingly in width. 

Spiral striation on the slightly worn paratype is 

visible on only the last one-third whorl, but on the 

holotype it is visible on all the base exposed (slightly 

over one whorl). On this paratype this sculpture extends over the whorl, but on the holotype it is restricted below the periphery. The other unworn paratype shows the spiral sculpture but it is imperfect and 

the whorls cannot be counted.

Distribution. Late Pliocene of southwestern Kansas.

Remarks. P. rexroadensis is most similar to P. 

texasiana texasensis and P. chisosensis. It differs from 

the former by the weaker axial sculpture, the spiral 

striae on the last whorl, the umbilical papillae, and 

the shape of the parietal tooth. In P. t. texasensis 

this tooth is roughly v-shaped, and both branches 

descend gradually toward their distal ends. In P. 

rexroadensis this tooth is asymmetrical, wT ith a long, 

high, columellar branch which descends sharply at 

its distal end. P. chisosensis has minutely granular 

sculpture and a columellar tubercle; both of these 

characters are absent in P. rexroadensis. P. chisosensis also lacks the umbilical papillation and spiral 

striation of P. rexroadensis. P. mooreana and P. tholus have stronger sculpture, a columellar tubercle, a 

V-shaped parietal tooth, and lack the spiral striae and 

umbilical papillae.

Material from the Bender local fauna consists only 

of small fragments. These show the spiral striae and 

umbilical papillae of P. rexroadensis^ but suggest palatal teeth of subequal size. This difference may be 

a character of immaturity, however, and the specimens 

are considered referable to the Rexroad species.

Occurrence and material: Rexroad and Bender local faunas. 

Rexroad loc. 2, UMMZ 1S3082 (8. including 2 fragmentary subadult paratypes) ; loc. 3, LT MMZ 183050 (67, including 1 adult 

paratype (measured) and 3 subadult paratypes) ; loc. 4b, 

UMMZ 177610 (6, including holotype and 1 fragmentary subadult paratype), 181059 (3); Bender loc. Ib, UMMZ 184144 

(10).
LITERATURE CITED 83

Genus STENOTREMA Rafinesque, 1819 

Stenotrema leal leai (Binney), 1840

Stenotrema monodon (Rackett). Pilsbry, 1940, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 1, pt. 2, p. 676, fig. 421a, b. 

Leonard, 1950, Kansas Univ. Paleont. Contr. 8, p. 36. 

Stenotrema leai (Binney). Pilsbry, 1948, Acad. Nat. Sci.

Philadelphia Mon. 3, v. 2, pt. 2, p. 1099.

Distribution. New York to Maryland, west to 

South Dakota and Nebraska.

Ecology. "$. monodon is a snail of damp places 

near the water" (Pilsbry, 1940, p. 678). "Stenotrema 

monodon thrives in rather humid forests, and may be 

found on low terraces and flood plains of streams, 

under leaves, logs, and stones" (Leonard, 1950, p. 36). 

In northern Nebraska it was found under boards on 

damp ground, on the floodplain of the Niobrara River.

Remarks. The Nebraska specimens have the open 

umbilicus and broader aperture of Stenotrema, leai 

leai, rather than S. leai aliciae. The occurrence in 

northern Cherry County, Nebr., reported in this paper 

is farther west than previously known localities.

Pilsbry (1940, p. 678) listed two Kansas records 

for this form, but Leonard (1950, p. 36) referred all 

Kansas material to 8. leai aliciae.

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 1919, Description of a new species and variety of 

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 1928, The fresh water Mollusca of Wisconsin, part I, 

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 1928a, The fresh water Mollusca of Wisconsin, part II, 

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 1937, Pleistocene land and fresh-water Mollusca as indicators of time and ecological conditions, in G. G. MacCurdy fed.]. Early Man: Philadelphia, J. B. Lippincott, 

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 1938, New land and freshwater Mollusca from the upper 

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Berry, E. G., 1943, The Amnicolidae of Michigan: distribution, 

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Connolly, M., 1939, A monographic survey of South African 

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Crandall, A. O., 1901, The American Physae: Nautilus, v. 15, 

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Franzen, D. S., and A. B. Leonard, 1942, A preliminary survey of the Mollusca of Kingman County, Kansas: Kansas 

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 1943, The Mollusca of the Wakarusa River valley: 

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 1947, Fossil and living Pupillidae (Gastropoda =

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Frick, Childs, 1937, Horned ruminants of North America: 

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Frierson, L. S., 1927, A classified and annotated check list of 

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Frye, J. C., 1942, Geology and ground-water resources of Meade 

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Frye, J. C., A. B. Leonard, and C. W. Hibbard, 1943, Westward extension of the Kansas "Eqiius beds": Jour. Geology, v. 51, p. 33-47.

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84 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

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 1939, Notes on some mammals from the Pleistocene of 

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 1944, Stratigraphy and vertebrate paleontology of 

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 1948, Late Cenozoic climatic conditions in the High 

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 1954, A new Pliocene vertebrate fauna from Oklahoma: 

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 1955, The Jinglebob interglacial (Sangamon?) fauna 

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 1956, Vertebrate fossils from the Meade formation of 

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 1957, Two new Cenozoic microtine rodents: Jour. 

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 1958, New stratigraphic names for early Pleistocene 

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LITERATURE CITED 85

La Rocque, Aurele, 1956, Variation of carinae in Valvata

tricar India: Nautilus, v. 70, p. 13-14. 

Lea, Isaac, 1864, Descriptions of twenty-four new species of

Pliysa of the United States and Canada: Acad. Nat. Sci.

Philadelphia Proc., 1864, p. 114-116.

 1866, New Unionidae, Melanidae, etc., chiefly of the 

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 1867, Observations on the genus Un-io * * *, v. 11, 146

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 1948a, Five new Yarmouthian planorbid snails: Nautilus, v. 62, p. 41-47, pi. 2.

 1950, A Yarmouthian molluscan fauna in the midcontinent region of the United States: Kansas Univ. Paleont. 

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 1952, Illinoian and Wisconsinan molluscan faunas in 

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 1952a, New gastropods from the Blanco formation 

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 1953, Molluscan faunules in Wisconsinan loess at 

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 1957, Types of late Cenozoic gastropods in the Frank

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Leonard, A. B., 1943, The Mollusca of Meade and Clark

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Leopold, L. B., 1951b, Pleistocene climate in New Mexico: Am.

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Leopold, L. B., and J. P. Miller, 1954, A postglacial chronology

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McGrew, P. O., 1944, An early Pleistocene (Blancan) fauna

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 1948, [Discussion of Sand Draw fauna], In Colbert, E.

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McLaughlin, T. G., 1946, Geology and ground-water resources

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 1952, The water rat in the Pleistocene of Texas: Jour.

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Mengel, R. M., 1952, White Pelican from the Pleistocene of

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Miles, C. D., 1958, The family Succineidae (Gastropoda:

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Morrison, J. P. E., 1947, One hundred six years of Amnicola:

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 1949. The cave snails of eastern North America: Amer.

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Mozley, A., 1926, Preliminary list of the Mollusca of Jasper

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Oelrich, T. M., 1953, A new Boxturtle from the Pleistocene of

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 1957, The status of the upper Pliocene turtle, Testudo 

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 1922-26, Pupillidae (Orculinae, Pagodulinae, Acanthinulinae) : Manual of Conchol., ser. 2, v. 27, p. 1-369, pi. 

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 1934, Review of the Planorbidae of Florida, with notes 

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 1940, Land Mollusca of North America (north of 

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 1946, Land Mollusca of North America (north of 

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 1948, Land Mollusca of North America (north of 

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 1950, Hellsoma anceps (Menke), 1830: Nautilus, v. 64, 

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 1953, Inland Mollusca of northern Mexico. II. Urocoptidae, Pupillidae, Strobilopsidae, Valloniidae and Cionellidae: Acad. Nat. Sci. Philadelphia Proc., v. 105, p. 133-167,

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Savage, D. E., 1951, Late Cenozoic vertebrates of the San

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 1955, A survey of various late Cenozoic vertebrate

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86 LATE CENOZOIC MOLLUSCAN FAUNAS FROM HIGH PLAINS

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and terraces in the Great Plains: Geol. Soc. America

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Smith, C. L., 1954, Pleistocene fishes of the Berends fauna of

Beaver County, Oklahoma: Copeia, 1954, p. 282-289.

 1958, Additional Pleistocene fishes from Kansas and 

Oklahoma: Copeia, 1958, p. 176-180.

Smith, H. T. U., 1940, Geological studies in southwestern 

Kansas: Kansas Geol. Survey Bull. 34, 212 p., 34 pi.

Starrett, Andrew, 1956, Pleistocene mammals of the Berends 

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Stokes, W. L., 1955, Another look at the Ice Age: Science, v. 

122, p. 815-821.

Taylor, D. W., 1954, Nonmarine mollusks from the upper 

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 1954a, A new Pleistocene fauna and new species of fossil snails from the High Plains: Michigan Univ. Mus. 

Zool. Occ. Paper 557, 16 p.

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fauna from Harper County, Oklahoma: Oklahoma Geol. 

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 1956, Pliocene mollusks from Jackson Hole, Grand Valley, and Star Valley, Wyoming and Idaho: Wyoming 

Geol. Assoc. Guidebook 11, p. 123-125.

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 1954, A Kansas Pleistocene herpetofauna: Copeia, 1954, 

p. 217-221.

 1955, A new Pliocene species of Ambystoma,, with remarks on other fossil ambystomids: Michigan Univ. Mus. 

Paleout. Contr., v. 12, p. 229-244, 1 pi.

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2 v.

Tryon, G. W., 1862, Notes on American fresh water shells, 

with descriptions of two new species: Acad. Nat. Sci. 

Philadelphia Proc., 1862, p. 451-452.

Van der Schalie, H., 1953, Mollusks from an interglacial deposit (Sangamon? age) in Meade County, Kansas: Nautilus, v. 66, p. 80-90.

Van Houten, F. B., 1944, Stratigraphy of the Willwood and 

Tatman formations in northwestern Wyoming: Geol. Soc. 

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 1909, Notes on Planorbis, II; P. Mcarinatus: Nautilus, 

v. 23, p. 1-10, 21-32, pi. 1-3.

 1914, Notes on the Ancylidae of North Africa: Nautilus, 

v. 27, p. 113-117, 124-131.

 1925, New species of North American Ancylidae and

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Wood, H. E., 2d, and others, 1941, Nomenclature and correlation of the North American continental Tertiary: Geol. 

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 1951, Fossil fresh-water mollusks and ecological interpretations: Geol. Soc. America Bull., v. 62, p. 1375-1380.
INDEX

[Italic numbers Indicate descriptions]

Acknowledgments. 

Acroloxinae........

Acroloxus..........

._. -_ - . ............... 61

............................................................ 61

coloradensis..............................----- 6, 7,12,33,34,35,36,37,39, 61, pi. 1

adamsi, Blarina. -- 28 

Mammut.............---------------------------------------------------. 28

aenigma, Deroceras 3, 12,23,24,25,26, 27,29,30,31,32,33, 35, 36,37,39, 40,41,42, 80, pl.4 

aeruginosus, Planorbis............. 60

Promenetus-............................................................... 45

Age determination 9 

albeola, Bucephala............................................................ 28

albilabris, Pupoides. ... 3,6,12,23,24, 26, 27, 29,30,31,32,33,35,36,37,39,40,41, 74, pi. 1

Albinula...................................................................... 72

(Albinula) armifera, Gastrocopta.......................... _ .. __ 7#

holzingeri, Gastrocopta.......................................... ___ 72

altissimus, Gyraulus.....................................................___ 58

Ambystoma hibbardi,~-......... .....___ 27

tigrinum.................................................................. 37,40

Ambystomatidae _. 22,23 

americana, Fulica............... __ 28

Amnicola..................................................................... 50

crybetes...................................................... __.. 38,50

lacustris.... .................. __ 50,51

limosa........................................................... ___ 50

lustrica................................................................ 45,50,51

decepta................ ... 51

perlustrica. __ 51 

walkeri............ ............ -. ... ___-______._ 45,49.50

(Marstonia) lustrica .................................................... 51

Amnicolinae____ - _ ______ 49,50 

Amphibia...____.__....... . .... __...._.__.__ 22,23,27,37,40

Anasbunkeri....... _____ 28

anatina, Physa-.... 3,6,12,23,24,25, 26,27,29,30,31,32,33,35,36,37, 39,40, 41,44, 68, 64

Physella... ............................-.........................._.. 62

anceps, Helisoma ........................ 3,6,12,23,24,27,29,33,35,36,39, 44,58, 59

Anchylorana dubita. _____ 27 

moorei .. 27 

robustocondyla..-.-----------------------------------------------...___ 27

Ancylidae_.... . __ 61

Ancylus fluviatilis. ..................... ...___ 61

hendersoni.. .................................................._____ 61

pumilus-....-................................................._____ 61,62

Angell member of the Ballard formation.._.__________________ 3,15 

Angustula.................................................................... 45,76

(Angustula) hibbardi, Vertigo...............__ ....______________ 45

Anisus...__ ... . ...___ 56 

pattersoni. .............................. . .. 7,12,33,35, 36,39, 58, 57

perezi______ -.-.__._______ 57 

rotundatus- _--- _.. -.--.-.--.-.-..-..-..--.-...-......-..... 56,57

Anodonta.----- _ __ ......._... 45

gigantea_---- ----------------- --._-.__........ 45

ffraniiw--------------------------------------------------------- 24,33,35,36,45

(Pyganodon) grandis...-- ... ... .....______________ 46

Anodontinae. ___.------------------ --------------_ 45

Anseriformes -----------------------------------___.__-.___-,---_-.. 28

Antilocapridae__- __ __ --_ _ ___- -_ __.......... 28

antiquus, Pliolemmus.-.. .... -...... .-...-....__..._______ 17,37,40,42

antrosa, Helisoma..---------------------------------...--------_--.....-.... 58

Aplexa-------------------------- --__.----_--__--_-_----_--.-._--.___.. 64

hypnorum- ...... .................. 6,12,13,24,32,33,35,36,40,41,44,53,54,64

arboreus, Zonitoides ------------------------ 6,12,24,27,29,31,36,37,39, 44, 80, 81

Arctodus simus-....................................._...................... 17

armifera, Gastrocopta.................... ._...._____- 6,12,24,26,36,37,39,44,72

Gastrocopta (Albinula)....----_-------._---_.___.-__-----------_ 72

Page 

Armiger.--.-... _-.._.-._-------_-------------- ..._........____ 58

crista.-- --------------------------------------------------- 6,36,44,58

armigera, Planorbula ----------------------------------- 6,12,33,35,36,37,39,44,59

Artiodactyla.... . . ... 22,23,28,33,40,42

(Asinus) sp., Equus-.-.--------------------------_------------- ....__ 16

Astian (late Pliocene) deposits.-.. .__ ....__ .....__.....___. 21

Atlantic Coastal Plain_---------------- --------- ------- -----_- 7

Atwater member. -_ -- -- _- - - - - 15

avara, Sucdnea.-----------------... .. --------- -_._ .._- 26,78

Aves. .__ - - - - 23,28,37,40,42

B 

Baiomys kolbi.------.... ................ _.....................___.

rexroadi ------------------... . ....__..___--------___.....

sawrockensis.----... _._--._.............._..__...._...._......

Ballard formation.----------__.....________________......

barbouri, Paenemarmota..------...- . --------____--._...__......

Bar M local fauna._ ......__ _ . .._.__.............

basalts, Valvata tricarinata---------.....--.--.-.......-..-,-.......-..........

Basommatophora.... - .. - ... 22,23,25,27,31,33,36,

Bassariscus casei... - _- _ - _- _-_- - __......

rexroadensis .- ------------ -------------- ----------_.

baumgartneri, Peromyscus--.------------- ___... . . ....

bettus, Dasypus- --------- .._........ ....

Bender local fauna____ .___ __.___. __.________ __ 11, 

Bensonomys eliasi ...... _.__....._----------___.. ......

meadensis-.--.----...........................----------------... ...._..-

Berends local fauna._. . _--,---._-------____--._____...

bermudensis, Vertigo-.................--------------------- ...

bicalcaratus, Playgonus. ---------------... ..-_-_...__------------_..

bilamellata, Gastrocopta-.--.---.... _-------------_-------___........

bilobatus, Cnemidophorus ---------------....-_........... ------ .._.

Biorbia fossilia.... ..-._---------------_--------_____ --------------

Bir ds.--------- .-. .-.-.-.-. . ......- . -.-..-...- .-.-- . _

Bison latifrons-------------------------------------...----- - .......

Blancan age- _----------__-...-.-.-- -----------...

blancoensis, Promenetus ------------...-...--.-.-.-...__-___....___ 38,

Tanupolama------...........^..............___---.-.-.---.-..._-.....

blandi, Pupilla ......-_________-_____...__.__ .... 16,17,

Blarina...------------- ------------------_..---_.----.---_-.-..........

adamsi ----- ....... ----------- ---------- ............

sj?........................................................................

Borchers local fauna.. ..-.-.-...-.-.-.......___...................._.

borealis, Synaptomys (Mictomys).....___-------_-_-------_......_.

Borophagus.-------------------- _--------------------------- _- 

diversidens------ .... . __.__._-___-_-_ ... . ... ...

brachyodontus, Odocoileus.----------...----------_ __.........._...

Brachyopsigale dubius.----------------...-.-.-.-...-.-.-...-.-.---.-.....-....

breviramus, Buisnictis....-------_- .__-.-.-.-..__.-.._------...

Bucephala albeola----------------------- ......................................

Buckshot Arroyo..--------_-.-..-.---.------_--_-------------------_-----

Bufosp ,-------......................................... ---..............

Buis Ranch local fauna - , 1,

buisi, Pliogeomys_.---.-.-.-.-...-.-.-.-.-.-.-.-.-.-.....-.---.-.-...-.-.-..

Buisnictis breviramus------------....- ------.--.-.-.-.----.--- --------

Buliminae-------_.._---------_--------__...._.___.__.........

Bulimnea...-------------------- --------- .................. -..._.._

megasoma...... ..-____....__-----------_----- 6,7,12,33,34,35,36,39,

bulimoides techella, Galba.------------------------------...-----.----.-----.--.

techella, Stagnicola-...... 3,6,12,13,16,23,24,24,25,26,27,29,30,31,32,40,41.

Stagnicola (Nasonia)--------------------------------...---------------

bunkeri, Anas.... __ - _- . - _..-.-.._---------

Buteo sp- _-.. _ __._ -_ ._ _-

Butler Spring local fauna.__ . - .-_-_ _.___.......__-.........

87

28

28

23

15

28

17

48

40,51

28

28

28

17

14,31

28

40

17

76

28

73

28

18

42

17,19

18,21

45,60

28

18,35

39

28

37

16

16

21

28

28

28

28

28

22

27

14,22

22

28

22,23

49

56

40,56

54

45,54

54

28

28

16
88 INDEX

Page

Caliche, origin of-.. --- - - - _- 3 

Camel, giant------- - ------- ------- . _ __ 22

Camelidae___________.---_- .-._____ 40,42 

Cametops----------------------------------------------------------------- 17,33

sp. 33

Canis latrans-.--........ _-_ --- ---- - ---- - 

lepophagus.... .................- - 

 33

 28

sp_ 28,42

caperata, Stagnicola-..... 6,12,13,18,22,24,27,29,31,32,33,35,36,39,40,41,43,44, 53, 54

Stagnicola (Hinkleyia)-........ - . _ ....__ 53

Capromeryx sp__-___-_---- --- - - _--- - . .... 33

Carnivore.. - - 22,23,28,33,37,40,42

carus, Promenetus---------------------- --------- _ - __ _._. 60

Carychiidae-.--__ .... ..._ 51

Carychium... __-__-__-_-_- ------ .. .... 51,74

exiguum-............ ... ...... 2,6,12,24,26,27,29,30,36,39,44,45,51,52

perexiguum--------- ...--------- .. ...... 45,51,52

sp- .. . 33,35,36,52

casei, Bassariscus.--.------.----------.--------.---.--.-.---------.......---.- 28

casertanum, Pisidium... 6,12,22,23,24,25,26,27,29,30,33,35,36,39,44,47 

Castoridae____ __------_ ...--..-.-.-_____........____ 37

Castoroides -. - .. .. __.___________ 17

Caudata...- ...... 22,23,27,37,40

centralis, Liomys.............................._.__-....__________... 28

Ceratophyttum.................................. 48,57

Chaenaxis.......--------- -------- -... ........_________.. 74

Charadriiformes _____________________.__________ 28

chauliodonta, Gastrocopta-......... 11,12,16,17,24,32,33,34,35,36,37,39,40,41, 70, pi. 1

Chelonla...... 22,23,28,33,42

Chiroptera..-------........-....---------------______-___...__. 28

chisosensis, Polygyra.........................-____.._________ 82

Ciconiiformes_________.-._______-___________.__ 28

Cimarron River.--.______________________________.___ 3 

Cimarronomys stirtoni .........................__________.._._... 23

Cincinnatia integra...................-...-..__._________.__......_ 50

peracuta..... ..... . .. ..........__________...... 50

cinereus, Sorex...................._____._______________,_ 18

Cionella......... .......... . ... ...........____________ 77

lubrica................ ........ ...... 6,7,12,24,27,36,44,77

Cionellidae.______________________.____________ 77 

circumlineatus, Planorbis ...... ______________..___________ 45

Promenetus............--_.___________..._____________ 60

circumsfriatus, Gyraulus......................__._____._______ 6,36,44,57

Citellus dotti.. ... .. ....... ....................... 22

howelli. - - - - -- ----._-- . 28

reiroadensis..........................._____...______ *

sp. . . . .......................... 37,42

Cnemidophorus bilobatm.........____________________________ 28

cochisensis, Gastrocopta_....____..__________________ 73

cochrani, Pliauchenia........____________....____._______ 28

cockerelli, Stagnicola.........._...._.____....__.____....... 24

Colinus hibbardi_____________________________. ______ 28 

Collecting methods_____._______________ ________ ___ 2 

coloradensis, Acroloxus... __ ______...._______ 6, 7,12,33,34,35,36,37,39, 61, pi. 1

Cclimbiformes------_---..-...._-_____________......... 28

Comparison of faunas__...__.-._____... _ ___....._........ 11

compressum, Pisidium.-............ ________.__ 6,12,26,33,35,36,39,46,47

concordialis, Succinea........ ______........____..._......___....... 24,39,77

contracta, Gastrocopta-...................... ____....____________ 39

cornutum, Phrynosoma....... ________________._..._____. ______ 17,28

Correlation of North American ages with Lyellian epochs_____ _ _____ 18 

costata, VaZ.oiM'a._________-___-_-___.___------_-_-_--_-_----.-______________ 26 29

Cragin Quarry local fauna____________________________________ 17

crassum, Sphaerium.-............................. _____.._-______________ 46

crawfordi, Notiosorex......... _____________.________________ 17

Cricetldaeindet._____________________________________ 22

crista, Armiger............... .. .-.. -..---______________ 6,36,44,58

Gyraulus................................................................. 58

cristate, Gastrocopta----. 2, 6,12,13,17,24,26,31,32,33,35,36,37,39, 40,41,44,67, 69, pi. 1

cronkhitei, Discus-.-.................................................. 6,18,36, 44, 79

Crooked Creek formation.....____________________________ 15; 19

crybetes, Amnicola.............................__________________ 38,50

Marstonia................................ 3,12,23, 24, 27, 29,30,36,39, 50, 51, pi. 2

Cryptotis kansasensis..............................................._...____.__ 37

meadensis......................................................._.__.__... 28

Cudahy fauna__________________________________ llt 15

curacoana, Gastrocopta..............................______.................... 71

Cyclic climatic changes_______._____________________.__ 10

Page 

cyclophorella, Vallonia....................................... .............. 16

Cynomys meadensis. ... 42

D

dalli, Fossaria 3, 6,12,23,24,27,29,30,31,32,33,35,36,39,40,41,44,45,54,56,79, pi. 2 

Galba ............................ ... ...... ... 54

», Fossaria......................................................... 53,55

 _...__-__ _ 17

decepta, Amnicola lustrka 51

Matt-onto-.. ---- -------------------------------- 3,6,12,23,24,50, 61, pi.2

Deer Park local fauna... 16,4/ 

deflectus, Gyraulus. .. .. ..... 6,7,36,44,57

densecostata, Strobilops.... .... ...... ... .... 65

Depositional and biological sequence, summary of. 18 

Deroceras. .. ... ... ... 25,80

aenigma. .. 3,12,23,24,25,26,27,29,30,31,32,33,35,36,37,39,40,41,42,80, pi. 4 

laeve ... 24,36,44

diaboli, Vertigo ovata..... .. ....... 76

diminuta, Lymnaea............................. ... .... ....... 38,45,53,54

Dipoides wilsoni.......... .... . ....... 23

Discus-. . - 79

cronkhitei.... . 6,18,36,44,79

macclintocki........ ....... ....... .... .............. .. .-. 8

diversidens, Borophagus.. 28

diversus, Scaphiopus............ .... ......... ... ...... 27

Dixon local fauna... . . . 1,11,17, S6 

dixonensis, Sorex.... .. ... ...... ... . . 37

dotti, Ctiettus . ........ . ... 22

dubita, Anchylorana................ ............. . ...... ............. 27

dubius, Brachyopsigale. . . . . ........................................ 28

E 

Edentata ..._____ 28

elecfrina, Nesovttrea ...... .................... 6,12,24,27,29,30,36,37,39,80

Ntsovitrea (Perpolita).. .. .. ................. SO

eliasi, Bensonomys.... 28

elliptica, Physa.... ......... 63

Elodea _________ ______ ____ ~_____ 48,57

Emmericiinae ___.. 49 

enaulus, Gyraulus ........ ..... ..... ....-. . ....... 38,45,58

Endodontinae.. 79 

ephippium, Rana............. . .................. ........ ......... 27

Equus (Asinus) sp 19 

so.. _________-__--____---______--____-- 16

Erymodon.-------.

Esox masguinongy. 

Euamnicola........

Euconulinae_

Euconulus -. ---

.... . -. - 82

........ .....-. ... .. -- - 17

...... .. . .. . 50

... .. 80

. ___ _ _ _ ___ ______ _____ _ __ ____ ____ . ___ 80

fultms...... 6,36,44,80

Eumeces striatulafus---- _ _ . - -------- __ 23,28

Eumecoides hibbardi. ---------------- _____-__-----__-------_._--------- _. 28

mylocoelus- ---------------------- ... -----. ----- ------------------- 28

exacuous, Menetus- ----------------- .... .. _--------_----------------_------ 59

exccuous, Promenetus--- .... - -. -----_-- -.- .--------- 59

Promenetut - - -- -- --- --- 6,7,17,24,36,44,59 

exiguum, Carychium. .... . ........ 2, 6, 12, 24, 26, 27, 29, 30, 36, 39, 44, 45, 61, 52

exilis, Galba.. -.. .-..... ....... ....... ....... ^ . 52

Stagnicola. ........ ........ ... ....... ...... 6,12,24,27,29,30,45.5^

-... _ _ - --- 28

_ ... ... -------- 9

____---__._----_ ----------------- 8

---- -- - - -------------- - ----- 14

________ _.______.__._.-___ 11

fayeae, Rana------------ ... -------- .....~. .------- -------------------- 27

------------------------------------- 28

Falconiformes------ - __ _

Faunal dating.. .... .. _

Faunal interpretation, methods of. 

Faunal sequence, summary of.-..- 

Faunas, comparison of.

sp.---------------------------------------------------------------------- 28

Ferrissia.-------------- ...---------------- __.. . ------- --------- 61

meekiana. -...-.................--..........-----...-. 6,12,33,35,36,37,39, 61, 62

parallela.. 6,12, 24,27,29, 61

pvmila...-.---------.---------- .- .----.---------------------------- 62

rivularis-------------------- 3,6,12,17, 22, 23, 24, 25,26, 27, 29,30,33,35, 36,37,39, 61

Ferrissiinae-.----------------------------------------------------------------- 61

ferrugineum, Pisidium---.-------- ... -- - --- -- --------- 17

flavescens, Perca.------------------ ... - - - - - 16,17

fluviatilts, Ancylus.-----------... - __ - - - - -- 61

Fontigens...-........--.-...-..........--..-.........-- -------------------- 51

fontinalis, Physa.---------------- . . ------ _... ..-- 64
INDEX 89

Page 

Fossaria.... ----.. ..----------------------------------.-..-. 8,39,54,74

dalli-......... 3,6,12, 23, 24, 27,29,30,31,32,33,35,36,39, 40, 41, 44, 45, 64, 56,79, pi. 2

grandis------------- ------------,------ --.-.--------. -------- 53,55

obnssa.---.-... ---.------------.-------.---- 6,12,24,26,33,35,36,44,54

parva. _________________________ 55

................... ... .. 55

... _ ., ___ __ ______ 55

... ... __________________ 55

. ___ . __ _.-___.___-_ 3

......................... 18

....... .... ...... ... ..... 28

_-_-____--_-_---_-_--.__. 16

... ... _-.--_--_--_-_ _ -- 28

franzenae, Gastrocopta.. .................. 3, 12, 23, 24, 25, 26, 27, 29, 30, 31, 32, 45, 67, pi. 1

fraternum, Stenotrema .... ......... _ _ _ ____________ _ ...... ... ... _.._. _ .. 39

Fulica amencana _____ _.._.._.__ _ _.__._._.._______... _ _____ _ _________ _ . 28

fulvus, Eueonulus ____ .__ _____ _ ____ _____ _ _ ____ . ____ ._ 6, 36, 44. SO

sterkii ..... ... .-. ..-.......-....... .

tazeweltiana .... ... . _____ ... ___

perplexa..... -------------------- .... ..... .

Fossil mollusks, environmental interpretations. 

fossilia, Biorbia. ...............................

fossilis, Lasmrus ....... ...... .. ... ..... ..... . ..

Onychomys. ------------ ... -___ _ ...- _ --

foxi, Martes. -----.-----------.--------.-..-...-

Galba bulimoides techella. 

dalli-. .-. 

exilis................

obrussa.- 

palustrisreflexa. _ _

-------- -----.---------- -.--- 54

-______-_-__-______-____-____-__-_.___-_________ 54

_-____- ___.______-____-_______-_____-___-___ 52

______________________________________________ 5.

-____-_____-_-_____________-__-__-___-___-_..-__ 52

_________________________________________________________________ 53

Galliformes________________________________.__________. 28

gallopavo, Meleagris... ________________________________..____ 28

Gastrocopta.--------- ------------ _-____-._______._____________________ 67

armijera.-- --- --- --- ------- 6,12,24,26,36,37,39,44,7.?

bilamellata _______________.._____________________. 73

chauliodonta. __________________ 11,12,16,17,24,32, 33,34,35,36,37,39,40,41, 70, pi. 1

cochisensis-... _________________.__-_________--_-____-----_-----_____ 73

(Albinula) armifera. __________________________________________________ 7%

holzingeri----.----. --- _---_-__-___--___--_-__-_.___.__----__---_ 73

contracta............................. _._________________ 39

cristata.... -- 2, 6,12,13,17, 24, 26,31,32,33,35,36,37,39,40, 41,44, 67, 69, pi. 1

curacoana... ___________________________________________________ 71

Jranzenae..- --- __________ 3,12, 23, 24, 25, 26, 27,29,30,31,32,45, 67, pi. ]

holzingeri------------------------- --------- 2,3,6,12,23,24,27,29,30,36,44,73

(Immersidens) rexroadensis-.-- __________________________________ 73, pi. 1

lavernensis --------------- ___._-___--__-_-_____________________ 71

oligobasodon..-------------------- _._--_-______-.__.-__--.___._____ 73

paracristata- _____________ 3,12,16,17, 23, 24, 25, 26,27, 29,30,31,32,38, 40, 41, 9, pi. 1

pellucida hordeacella... .. 6, 7,12,13,17,18, 24, 25, 26, 27,29,30,37.39, 71, pi. 1 

procera. _____________________________________________ 2, 6,13, 24, 26,37,39, 67, pi. 1

prototypus-.-- _____________________._____________ 73

rexroadensis-----------------------. 3,11,12,17, 23, 24, 25, 26, 27, 29, 38,73,pi. 1

scaevoscala..- -- ------- .-. _____________ 12, 24,31,32,37,39,45, 70, pi. 1

tappaniana. __________ 3,6,12, 23, 24, 27, 29,30,31,32,33,35, 36,37,39,40, 41,44, 7S, 74

Gastrocoptinae.---._-_--_-____-_____.-_-____.___--__.____________________ 67

Gastrodontinae__________________________._-__.______ 81

Gastropoda.......____________________________________ 22,23,25,27,31,33,36,40,42,48

gelida, Succinea grosvenori-------- ---__---________---__.--_____--___________-__ 78

Geomysguinni______________________________________ 17,28,33,42

tobinensis. ______________________.----_____________________________ 40

sp. ___________________________________________ 37

Geyer, quoted_____-____--__.__________________.._________ 5

gidleyi, Onychomys.--- ____._________________...____________ 28

gigantea, Anodonta.. ______________________________________________________ 45

Gigantocamelusspatulus--.- _______._____________________ 23.28

sp_ _________________________________________________________________ 33

Glyphyalops-------------.... _____________________________________________ 81

OJyphyalus.-.-.--.....--... .-...-- .--.-------..-.-..... __________________ 81

(Glyphyalvs) wheatleyi, Betjnella....-.... ........... .................... 81

gouldi, Vertigo....... ______________________________.____________ 16.35

gracilicosta, Vallonia. ________________________________.__6,12,13, 24,27, 29, 30,36,44, 77

grandis, Anodonta... _________________________________________________ 24.33,35,36,45

Anodonta (Pyganodon)-...-__-_____-______----___.--__--______-_____-_____ 45

Fossaria dalli----.--.---_. ____________________________________ 53,55

granum, Lyogyrus.--- .____-____---____-_--____-__._________________________ 49

grosvenori, Succinea........................................................... 78

gelida, Succinea. __________________________________________________________ 78

Gruiformes_-_-___________________________________________________________ 28

Gundlachia meekiana._____________ _________________ __ __ 61, 62

Gyraulus...... __________________________________________________________ 57

altissimus... ________________________________________________________ 58

circumstriatus-- ____________________________________ 6,36,44,57

crista- ________________________________________________________________ 58

deflectus. __________________________________________________________ 6,7,36,44,57

parvus.... ______________ 3, 6,12, 23, 24, 25, 26, 27, 29,33,35,36,39,40,41,44,45, 68, pi. 4

Page

Qyraulus C ontinued

pattersoni... _____________________________________...________________ 56

vmMlicatellus.... __..__-_______._-_-__.___.-.___________________ 60

gyrina, Physa. ___________________________________ 6,12,26,33,35,36,37,39,43,44,63,64

hildrethiana, Physella.--------------- ________-.-________________________ 63

H

Habitat and distributional data, inadequacy of..-----_-__________________ 7

Hawaiia -____._.__________._____________________________ 81

minuscula- ______ _ 3, 6,12, 23, 24, 25, 26,27, 29,30,31,32,33,35,36,37,39,40,41,44, 81

haydeni, Oxyloma... ___________________________________________ 78,79

Hebetodiscus.......... ____________________________________________________ 79

Helicodiscinae___ _____-____ _-__-_-_____________________________ 79

Hehcodiscus---------------------------- ____________________________________ 79

(Hebetodiscus) singleyanvs............ ____________________________ 79

parallelus--------------------------..--. ...-------- 6,12,24,26,37,39,41,79

singleyanus. __________ 3, 6,12,13,17, 23,24, 27, 29,30,31,32,33,35,36,37,39,40,41, 79

helicoidea, Valvata lewisi--.... ___________________ _______ 49

Helisoma.------------- ______________________-._______________ 68

o.wx'pn ------------------------ 3,6,12,23,24,27,29,33,35,36,39,44,55,59

antrosa______________________________________________________________ 58

(Pierosoma) Mvolvis.... ___________________________________________ 59

trtoolois.-- - - .. ..- . 6,12,24,26,36,39,44,59

Helisomatinae____________________________________________________---.____ 58

Hemp hillian age.______________________________________________________ 18

hendersoni, Ancylus,... ______-_--__-__-_____________---____.-_____--________ 61

Hendersonia occulta..... __________-_--__-_____--_-_--_--__________-____-____ 8

Hesperoscalops rexroadi..--------- _-_--__________-__---.._________-_--__-___ 28

sp__------______--______-_-______-__________--_____-.____________-________ 22

Heterodon plionasicus..... --_-__-_____-__________-_____-____-__--____-_______ 28

hibbardi, Ambystoma. _________________________________________________________ 27

Colinus---..--........-------- - .-. __________________________ 28

Eumecoides______-----_____-__-___---__,-______________--_______. 28

Vertigo...... . . 3,11,12,22,23,24, 27,29,30,32,38,45, 74,75, 76, pi. 1

hildrethiana, Physella gyrina... ______________________..._______._ 63

hilli, Sigmodon ________________________________________________________ 16

Hinkleyia... _________________________________________________ 53

(Hinkleyia) caperata, Stagnicola___.--_.__._-_-_____.--__-____----___ 53

holzingeri, Gastrocopta _________________________ _ 2,3,6,12,23,24,27,29,30,36,44,7.?

Gastrocopta (Albinula)-- __________________________________.-.- 72

hordacea, Physa................ ___________________________--.- 64,pi.3

hordaceus, Pupoides ________-_____-_-______._-_-_._________--._ 18

hordeacella, Gastrocopta pellucida.... 6,7,12,13,17,18,24,25,26,27,29,30,37,39, 71, pi. 1

howelli, Citellus--------------.------ ----.------------------------- 28

hvmilis modicella, Lymnaea....-- _---_-_--_____-_-_-_-__----.____----_---- 55

Hydrobia steinii... _______________________._-_-_.____________-_--.--- 50

Hydrobiidae..--.____________________________________________________ 5,36,39,49,50

Hydrobiinae....______________________________________________________________ 49,50

hypnorum, Aplexa. ________________________ 6,12,13,24,32,33,35,36,40,41,44,53,54,64

Hypolagus regalis---------------------- _____________.___._--- 28

Hypolagus sp____.___---_____-----_---_-_.___-_-________________ 42

Ictalurus punctatus.

sp.

._ .- ______ _ _- __.____._-__________. ______ 16

.____ _ _- _-_-______,_ _-__-_ -_._ 33

Immersidens........-__________--.-.______________________._ 70,73

(Immersidens) rexroadensis, Gastrocopta..................._._-_____.__ 73,pi. 1

indentata, Petinetta... _______.--._______________._-_____.-._.. 39

infracarinata, Valvata _ncara?a.a_______________________..__..___ 48

inornatus, Pupoides... ______________________ 6,12, 24,25,26,27,29,30,33,35,36,74, pi. 1

Pupoides (Ischnopupoides).. __._.___________________________ 74,pi. 1

Inseetivora._________________________________________________________ 22,23,28,37,40

Integra, Cindnnatia.. __________________________________________ 50

intermedius, Sigmodon----------- ___________________...___________ 28, 40

International Geological Congress__-_--_-_-_-.-_____________________.__ 19

Irvingtonian age________.____.___________________..__._. 19,21

Ischnopupoides____-----____________________________------__.__ 74

(Ischnopupoides) inornatus, Pupoides___________________________ 74, pi. 1

J 

jacksoni, Notiosorex. --__-_-_----_.____________________-_-----_-._-__ 28

jayense, Musculium______________________________________.______ 46

jennessi, Physa............ ._.___________________._._-_.________ 64

Jinglebob local fauna.___________________________________________ 16

Jones local fauna.--___-____________________________________---. 17

Jones Sink________________________________.-._____._. 17

jugularis, Lymnaea stagnalis___________________________________ 16,17, 56
90 INDEX

Page

K

kansasensis, Cryptotis- . _---....___---------__________________________ 37

Menetus...... ...____.---._______________________ 38,45,59

Peromyscus... ___.--.___--__-_---_--.__......._.__._.__...... 28

Pratilepus..... .._____.______._---_.___.___......_.... 28

Promenetus . 3,12,17,18, 23, 24,25,26,27,29,30,33,35,36,37,39,40,41, 59, pi. 3

Trigonictis______...__...___._________.________ 28,33

Kincaidilla.-.... - -. -------- ....-......--.-.--.-----_..-.. 62

Kinfsdown silt.-_.--.-._.______..__--..._._-.__.__...___.... 15

kirldandi, Laevapex.--------------------------...___._._....._........ 17

kolbi, Baiomys.------ _-------------_-___---_______.......___.... 28

labyrinthica, Strobilops- . 3, 6, 12, 17, 23, 24, 65, pi. 1

lacustre, Sphaerium ________ .... ____ _ ______ ... __ 6,12,36,39,44,46

lacustris, Amnicola ... ....... ... .... _ ._. _ __ - ____ . __ ... __ .. _ . _ 50, 51

Felis .... ...... ...........--- . ____________ _ ___ __ _______ ..

Neosorex ..... . __ .__-_. ___ - ______ . ______ . _________

Patella . ____ . _______________ . ___________ _____ 

Probythinella ...... __ ... _ ....... ___ ..... _ _ ____ ___ . _ _ ._.

Laevapex kirklandi. ........ ... ------------- ...... __ __ . ___ .. _ .....

laeve, Deroceras ...... ... ...- _ ... _ .... _ ...... _ ...... _ ... __ .___.. 24,

Lagomorpha ___ - _______ - _______ ___. __ ... ___________ 22,

Lampsilinae _ ... _ _ ---------- _ ........ __ --.--...- ___ .. _ _ .....

Lampsilis subrostrata ...... .-----.-.-... _ _ .......... _ _ _ _ __ -.---....

landesi, Synaptomys __ ... _ ....... ._ __ ... _ .......... _ ... _ _ -------

lanei, Procastoroides ... ----------------- __ ......... __ ..... __ _. __ .._____

larrabeei, Onychomys ... ------------ ___ _ _ ... __ ._._. __ _ . _ .._____

Lasiurus fossilis .... ._.. __ . _ _. __ ......... _ ..... _ . _ ____ _ .....

latifrons, Pison ...-. . ..--.------....... _ _ .......... _ ... _ _ _

latrans, Canis ... . __ ..----.--.-.-......... _ .... _ .... _ _ .---..-.-...._.

lavernensis, Oastiocopta ....... __ _ ...... _ ... _ ....... _ .. __ _ ___

leahyi, Sorex ------ -__------.---.____._ _ .--.---.-............. _ ______

leal, Stenotrema ..... -. _ __.--___ _ _ ._ __ _________ _ ____...___. __ 6,36,

leai, Stenotrema.-.. ... ._ __ _ ....... __ . _ ______ _ ...... _ __ .....

leonardi, Neofiber..... .... --.-. ........ _ --.-......... _ ._ _ .........

lepophagus, Canis ...... -_-.. _ ... _ ._.. ___ __ _____ __ ..... ___ ... _

Leporldae indet...... _ _ _ ___ ..... _ ... _ ... _____ .__ ____ ....

leptostomus, Megalonyx... .... . ___ .... _ __ _ . _ ___ _ __ _ __ _

lepmculus, Notolagus. ...... ______ . ______ _ _____ _________

lewisi, ralvata.. ............................................. 6, 12, 13, 33, 34, 35,

helicoidea, Valvata _____ ... _ ...._._ _ _ ..._._ __ .. ____ ___ .......

Ligumia....-- ..... .................................... _ _ _ _ .. __ . _ ...

subrostrata- ....... . .... __ . ____ _ _______ .. __ 24,27,29,

lilljeborgi, Pisidium.... ......... ....... __ ......._. _ .... ___ _ _ ......

Limacidae _____ _ _ ___ __ ..... _ __ ._._ _ . __ _____ _ __ _ ......

Limiting factors, recognition of...._ __ _ _.._._... __ .. _ . _ ............

limosa, Amnicola----.-.. _____ _ _.___-_ _ . _ ......... ___ .__ ___ ... __

lineatum, Sphaerium ... .... ___ _ __ ___ _ ______ __ _ ... _ _ _ ... _ _. _ _

Liomys centralis .... ..._. ....______ ___ __ _.... _ . ___ _ _ _ .........

Literature cited __ ._--_-___-___-_____ __ . __ ._. _ _ _ _ ... _ __________

llanensis, Pedomys.---.--.- ... _ ------- _ _ _ _. __ __ _ ....... __ _..______

Llano Estacado.. ______________ _ _________ _.. _____ _ __

caliche _ -.__--_-_-_-_-___ _ _ _ _ _._-__-_-_________ ___ . __ .......

Local faunas ___ ____ _ ______ ___ ____________ _ _ ....... ___ .. _ ...

description of. ....... __ _--______----______________..- _ __ ________ _

lubrica, Cionetta.... ............ ___ ____ _ __ _ ____ ____ 6,7, 12, 24,27,36,

lustrica, Amnicola _____ __ _ __ ______.._..._____ _ ___ _ __________________ 45,

decepta, Amnicola .-. __ __._____. _ ___-__--_.____._. _ _ ... _ ____ _

Paludina... .... _ --._.____-___ _ .... _ _ __________ _ . ___ ._.__-___

perlustrica, Amnicola.. .__...._.__.-_._____ _ _________ _ _.__..-.__--____

luteola, Siiccinea. ---------------_-___-____._____________.____.________________

Lutra piscinaria __________ _ ________________ _ ____ _ _

Liittig quoted..... __ _ ______ __ _______ ___ _____ . _ _ _

Lyell, quoted.. ____________________________________ _

Lyellian epochs, correlation of North American ages with ___________ .

Lymnaea diminuta _______________ . _________________ 38, 45,

humilis modicella .... _ _____ _ _____ ________ ___ ___ __ _ _.

macella. ... ............................................ ... .......... 38,45,

palustris ------ ... ......... . ...... ....... . ............ . ........ .... ... _ _.

parezilis. ........................................................... 38,45,

stagnalis jugularis ...... .. __ ___ ____ _ _____ __ ____ _ ._ __ . 16,

turritella.. .......................................................... 38, 45,

Lymnaeidae ______ _ __ _ ___________ _ _______ _ _ _

Lyogyrus granum..... ....... .... ... ....... .......... ... ..... ...... .. .... ___._

M 

macclintocki, Discus ..... __ _ __ ___ _ ____ ___ ___ __ ____ _ _ _.__.._. 8

macella, Lymnaea .......... ....... ............. .. ... _ _ _ ____ __ . 38,45,52, 53

28

16

61

16

17

36,44

28,42

45

45

16

28

23

28

17, 19

33

71

37

44,83

83

18

28

22

28

28

36, 48

49

45

30,45

17

80

5

50

45

28

83

16

17,18

26

3

10

22

,44,77

,50, 51

51

49, 50

51

73

28

20

9

18

, 53, 54

55

,52,53

52

52,53

17, 56

55, 56

52

49

Page 

mcgrewi, Nebraskomys......................................................... 33

Machairodus sp 28 

mclaughlini, Perognathus...................................................... 22,23

Mammalia... . 22,23,25,28,33,37,40,42

Mammut adamsi...................................... .................... 28

marginatus, Pupoides......................................................... 74

Marmota sp.... 23

Marstonia................... ------------------ 50

crybetes.......... ................. - 3,12,23,24,27,29,30,36,39,50,51, pi. 2

decepla................................................. 3, 6,12,23, 24, 50, 51, pi. 2

Marstoniopsis........ ............................ 50

Martesfoxi .. -...................-. ...................... 28

masquinongy, Esox............................................................ 17

Mastodont.-... 40 

meadensis, Bensonomys....................................................... 40

Cryptotis............... ...... . 28

Cynomys....................... .. .. .. . -- 42

Pitymys.......... ..................................... 16

Pliophenacomys-...................................................... 17.37,40

Pliopotamys..............-................................... 16,17,33,34,37,42

Rana......................... ... ...... ... ... -......................... 27

mediocarinata, Valvata tricarinata.......... 48

meekiana, Ferrissia........................................ 6,12.33,35,36,37, 39, 61, 62

Oundlachia............................................................... 61,62

Megalonyx, leptostomus....................................................... 28

megasoma, Bulimnea.---.................................. 6, 7,12,33,34,35,36, 39, 56

Meleagrididae indet-- _. 28 

Meleagris gallo,pavo...................-- ---. ---.-...........---........... 28

Menetus exacuous........ 59

kansasensis...- .............. 38,45, 59

umbilicatellus---- 60

Mephitis rexroadensis-........................................................ 28

Mesodon..........-------------------......................................... 31

Mesogastropoda.. -. 23,27,33,

Methods.--._ _ - __--__ . ______

Microsorex pratensis....-------------------------------- ... ..____________---_--

Microstele............- -- . ----------------------------------------------

Microtines_____----_-_-___-_- __.____________-__--_______-_-_--- -_._.

Microt us paroperarius...---------------------------------------- ---------

pennsylvanicus.... ____________.-_-_---_----------_ ------ _ --

(Mictomys) borealis, Synaptomys..---- ... _.__--_______ ________________ ..

milium, Vertigo. ______,. 2,3,6,12,23, 24, 25, 26, 27, 29, 30,31,32,33,35,36,37,39,40,

minor, Nerterogeomys.--------------------------------------------------------

minuscula, Hawaiia.... 3, 6,12, 23, 24, 25, 26, 27,29,30, 31,32,33, 35,36,37,39, 40,41,

minutissimum, Punrtum... _________--_------________--_----_ _.-___.-__- 36,

mirificus, Stegomastodon....... ...---------------------------------------------

Missler member.____--_-__ __________________-__-__-_____---_-----------_ 

modesta, Vertigo....-----------------------------------------------------------

modestum, Phrynosoma. ______....--------------------------------------------

modicella, Lymnaea humilis------------------------- __-____------- --_----

monodon, Stenotrema...----------------------------------------- ... ...--

mooreana, Polygyra.. _________________ ________________ .... .. 

tholus, Polygyra, ____ -------------------------------- ____._-____-_----

moorei, Anchylorana,---------------------------------------------------------

muscorum, PupUla... _._ -------------------- ... --______ ..... 7,16,

Musculiumjayense......... ______.... --. .. -_________---_ ___

partumeium---------- ...._-_.-- ---------------------------------------

rosaceum..... ______ ___-_------ _---------- _-___--- -_-- 

ryckholti.-----------------------------------------------------------------

securis--------------------------------------------------------------------

transversum....-----------------------------------------------------------

truncatum.---------------------------------------------------------------

Mustela rexroadensis------- ________-_-------- - _ -----------

sp.

Mustelidae _--___ ------ 

myJocoelus, Eumecoides.-.... 

Myriophyllum...............

Nannippus. -------------------------------------------------------------- 17,

phlfgon -. 16,28,

SD

Nasonia. -.- .... --_____-___.__- _

(Nasonia) bulimoides techella, Stagnicola. 

Nebraskomys mcgrewi-------------- --..

Nekrolagusprogressus.----- ----- ----

Neofiber leonardi------------------------

Neoscaphiopus noblei ... _._--------____ ._

Neosorex lacustris--------------- --------

36,48

2

16

74

39

16

17,18

16

41,76

28

44,81

44, 79

16

15

16,35

17

55

83

38,82

82

27

18,35

46

45

46

46

46

47

45

28

28,40

37,42

28

39

18, 21

40,42

*** *"

54 

54 

33 

2S 

18 

27
INDEX 91

Nerterogeomys minor.---...--,...-............................... .......

Nesotiitrea_____...____._.___...____...___________

electrina........................................ 6,12,24,27,29,30,36,37,39,

sp.

Page

28 

80

, 44, 80 

23,80 

,^5 

27 

17 

28 

28 

76

nitidum, Pisidium._............................................ 6,12,33,35,36,

noblei, Neoscaphiopus,__.. ,________________________________

Notiosorex crawfordi...............................................____________

jacksoni__...._...___......................................................

Notolagus lepusculus................................................._____

numellata, Vertigo....................................................

O 

obrussa, Fossaria-........................................ 6,12,24,26,33,35,36,44,54

obtusale, Pisidium............................................................. 17

occidentale, Sphaerium..........................................___...__ 53

occulta, Hendersonia.___..................... .__________________ 8

Odocoileus brachyodontus...-................................................_. 28

Ogallala formation_____...................................................... 3,15,22

Ogmodontomys poaphagus..................................................._. 28

sawrockensis............._____..._________________ 23

sp.. .............. . .___- __ _ ____ _ 42

oligobasodon, Qastrocopta. 

Onychomys fossilis.......

............................................... 73

 - .--________._______________ 16

..____________,______________________ 28

larrabeei _.._._......................................__..........._______.. 23

Oryzomys___..__.............................................................. 17

Osteiehthyes.. _________________ -_____. __ _____ ____ 23,33 

Osteoborus progressus.______................................................... 23

ovalis, Succinea_........................................__.__.____._____ 36,44,77,75

ovata diaboli, Vertigo.......................................................... 76

Vertigo.......................... 6,11,12,22.24,26,32,33,35,36,37,40,41,44,74,76

Oiyloma._..__................................................................ 78

haydeni................................................................... 78,79

retusa.............................................. 6,12,24,36,37,39,44,77, 78, 79

siUimani.................................................................. 78

Paenemarmota barbouri.........................................___ __.___. 28

Paladora Creek_________....__________.________ 26

Paleoeeologie interpretation, principles of.___...__.________, 4 

Palo Duro Creek. __ ___ ____________._______________ 26 

Paludina lustrica............................._______. _________. 49, 50

palustris, Oalba............................................................._. 52

Stagnicola.___............................................... 6,36,39,43,44,52,54

paracristata, Oastrocopta___... 3,12,16,17,23,24,25,26,27,29,30,31,32,38,40,41, 69, pi. 1 

Paracryptotis rex._............................................._.________ 28

Paradipoides stovatti..........................................._............. _. 17

Parahodomys guadriplicatus........................................_........_. 28

parallela, Ferrissia................... ..._______________ 6,12,24,27,29,61

parallelus, Helicodiscus....................................... 6,12,24,26,37,39,41,79

parexilis, Lymnaea_______________________________ 38,45,52,53 

paroperarius, Microtus---...............................................______ 16

partumeium, Musculium____.................................................. 45

Sphaerium. .-. -- .- - . __.-____._____ 6,12,33,35,36,39,45

parva, Fossaria..................................................____.__._____. 55

sterkii, Fossaria........................................................._. 55

tazewettiana, Fossaria...................................................._ 55

parvissima, Rana........................................................._.__ 27

parvula, Vattonia......................................_. 6,12,24,26,31,32,36,44,77

parvus, Gyraulus........... 3,6,12,23,24,25, 26, 27, 29,33,35,36,39,40,41,44, 45, 68, pi. 4

Passerifonres_--_---------____....____...____.-.._____ 28

Patella lacustris.__________........................... __.__.___....___ 61

pattersoni,Anisus _........................................ 7,12,33,35,36,39,56,57

Oyraulus..........................................._________..___________ 56

Pearlette ash bed_____....______________.____________ 11,15

pearlettensis, Perognathus..................................................... 40

Pedomysttanensis .......................................................... 16

Pelecypoda.... - . - - _ _.__ _ _____________ 22,23,25,27,33,36,45

pellucida hordeacetta, Gastrocopta.,.. 6,7,12,13,17,18,24,25,26,27,29, 30,37,39, 71. pi. 1 

pennsylvanicus, Microtus..........................__._______________.__...____ 17,18

peracuta, Cincinnatia.............................._______________...__.______ 50

Perca flavescens..................................__..____________._... ...___ 16,17

perconfusa, ValvataMcarinata____......_....._______..___________.______ _... 48

pereiiguum, Carychium..............._.................................... 45,51,52

perezi, Anisus.................._._______________________________..... ______ 57

Perissodaetyla.__________.________,________ 22,25,28,33,40.42

perlustrica, Amicola lustrica................................................... 51

Perognathus gidleyi......................................................_..... 28

mclaughlini___....................................._.__..._________...._ 22,23

pearlettensis-........................._____________.__________.____....... 28,40

rexroadensis__.....................______________.____________ ...__..._ 28

Peromyscus baumgartneri. 

kansasensis...........

progressus-.-.-.......

Page

28

28

17

37

55

41,77

40,42

45,60

60

17,28

17

anatina. ____..._ 3,6,12,23,24,25, 26, 27,29,30,31,32,33,35,36,37,39,40,41,44, 62, 64

ettiptica................................................................... 63

fontinalis................................................................. 64

gyrina..............................-... - 6,12,26,33,35,36,37,39,43,44,63,64

hordacea................................................................. 64,pl.3

_ __ - - - 64

SP---.- .... - - . - -- . - ................. .......

perplexa, Fossaria__............-..............................................

Perpolita......_____..........................................................

(Perpolita) electrina, Nesovitrea................................................

perspectiva, Vallonia.................... 3,12,13,17,23, 24,26,27,29,30,37,39,40,

phlegon, Nanmppus.................................................... 16,28: Phreatomenetus...........--------- - ....

(Phreatomenetus) umbilicatellus, Promenetus..--...._.........................

Phrynosoma cornutum........................................................

modestum ....--..-..-----..-----..----.--..----..--.-----.---.-..-.....

skinneri.................. 6,8,12,13.16,17,24,32,33,34,35,36,37,39, 40,41, 63, pi. 3

SP__ -------._-- - -__-_ -_._.__- .--.. 62

Physella anatina..__.._____.__.

gyrina hildrethiana.........

Physidae.____...._....

Piaeenzian deposits____ . 

Pierosoma.....................

(Pierosoma) trivolvis, Helisoma. 

piscinaria, Lutra.______........

Pisidium......................

......................................... 62

.. .. -_ . - . 63

................... ...................... 62

.-_ . _ . 21

..... _ _ .. .. 59

- .. .. ........... ........... 59

......................................... 28

.____ __ _. 47

casertanum.. .................... 6, 12, 22, 23, 24, 25, 26, 27, 29,30,33,35, 36, 39, 44, 47

compressum..... ...................................... 6,12,26,33,35,36,39,46.4?

ferrugineum .... .. ... ... -... ............. ... ---------- .... ................. 17

Wljeborgi-... . - - --- .-- -. 17

nttidum....------.--... .................................... 6,12,33,35,36,39,48

------------------------------------------ 17

-- - ------ -------------- 17

...........--... ....... ...... ... .... 17

.... ........ ...... . ... ..... 47.48

svbtruncatum. 

walkeri. ......

sp__ 

Pity my s meadensis-.-----.- .... __-_ -------------- _ -___- _--- . 16

planatum, Sphaerium simile_.. ----- 46

Planorbidae------_ ___ _.--- -------_ _- - -------------- 8,56

Planorbinae.--___ ._ - - 56 

Planorbis aeruginosus........ --------------------------- ..-. ------- - 60

circumlineatvs.... - --------- . .. 45

santacruzensis............... ___.__ _------_------ -- -_ _-- 45,60

Planorbula................... ............. - 59

..____ .__ __ - .- - 6,12,33,35,36,37,39,44,59

sp- ____ _ - - 59

Planorbulinae.. - - 

tygonus........

bicalcaratus....

sp.-- - 33,42

Plesippus.....................................-. - . 17,18,21

simplicidens .- - ---- - - -- --- 16,28,33,40,42

sp. ------------------------ ______-_- .-____-_ _-_____---____- 25

Pleuroeeridae_____.-- ........... ----------------- .... ----_-..... 8

Pliaucheniacochrani.----------------------------...-------------------------- 28

Pliocene-Pleistocene boundary.... _--... .......- 19

Pliogeomys buisi...........--------------------- ... -- - - -------- 22

sp....... -......... . 23

Pliohippvs-Plesippus............---......------------------ . _------ 21

Pliolemmus antiquus.-.........................- ...- ....... 17,37,40,42

plionasicus, Heterodon............... ... .....----....-----.....-.-.-....... 28

Pliophenacomys meadensis. ----------------------------- ---.---- - - 17,37,40

primaecus.. 28 

Pliopotamys meadensis....................------------------------ 16,17,33,34,37,42

poaphagus, Ogmodontomys..---------..---.----------------------------------- 28

Podicepssp................ - ------- - 28

Podieipediformes----------------------------------- ------ -------------- 28

Polygyra...- - - - - --- -- 82

82

38,82 

tholus...------ -------------------- -.----_-_____-_------------------ 82

rexroadensis-.............. .. - 11,12, 24, 27, 29,30,31,32,45, 82, pis. 1, 2

texasiana......................-......----...-.^.--.------.--.------------- 82

terasmsz'S----------------------------------------------- ----------- 82

Polygyridae.- - - - ----- 82

Polygyrinae.------- - -. _--______-_ . - 82

39
92 INDEX

pratensis, Microsorex ... ___-_ 

Pratilepus kansasensis. ----

prenticei, Rallus. .... -------

Previous work _._ __ --___ 

primaevus, Pliophenacomys. 

primitwus, Stegomastodon ...

Page

-- --------- __--. --._______ 16

------------ ----- -__-_-----_----__--.-_. __ 28

---- ____- - _ __- ___ __-_---_-_--__-__.____ 28

-_-_-. _ _-. ----.__ __ _ --_-__-___-___ 4 

__-_---__-____-_---- -____ ___________ 28

--...- _ _-._ __ ----..__ _ ________________ 33

Prionodesmacea__-___ _ __ ____________ __ ... ___ __ __ __.. 27,33,45

Privatula- ------ ... __-___-__._-----_-__---_-_-____-_----. _ .................. 74

Proboscidea. -------------------.-----------------_---_---_---_-------__ 28,33,40,42

Probythinella lacustris ... _____--_---_________-___----.____________________-..___ 16

Procastoroideslanei.. .-- . - ------------- --.. ... ..... _ _ _ .......... 28

sweeti.. ... .....-.----.-. . __ ....... __ _._._._________. _ ____ . 16,33,42

procera, Gastrocopta- _____________________________________ 2, 6, 13, 24, 26, 37, 39, 67, pi. 1

Procyon rexroadensis .._ __________________ ---------- ___________________________ 28

Prodipodomys rexroadensis .... __________________ _ __________________________ 28

sp... . 22,23,40

progressus, Nekrolagus--..-.-------------------------------- . .--- ---. 28

Osteoborvs.- .. __ -.--._-. __ ____ __ ........... _ _____..__ 23

Peromyscus- .._ ______ _ __---.--.___._______-_--__... __ ___ _ ___. _ ..__ 17

Promenetus--- __________ __ _...._____ __ _ __ . __ . _____ ______ _ 45,59,60

aeruginosus-- ----------- .__---.____--__ _ __-_-----__--_________-___ _ ... 45

blancoensis -------- __ . _ . _ .-_________._.. __ ...__________. _ 38,45,60

carus- ..------.-.. _ ___-_-_--_-_--._-_-_-____-_-______---.-.-____-_..____ 60

circumlineatus. ------------------------------------ ___ __._... _ _ _._.-__ 60

exacuous- .... - - _.. _ __ _.. _ . 6,7,17,24,36,44,59

exacuot/s--- -----------.--.-,--------.- ... _----__------_- _ ----------- 59

kansasensis- ....... 3, 12, 17, 18, 23, 24, 25, 26, 27, 29, 30, 33, 35, 36, 37, 39, 40, 41, 59, pi. 3

umbilicatellus-- __ _ ___ . ____ ._. _______ _ ___ -... ____ .... 3,6,

12, 13, 17, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 35, 36, 37, 39, 40, 41 , 44, 45, 54, 60 

(Phreatomenetus) umbilicatellus- .---.-.--.--.--... _ .. _ .___._._____ 60

Prosobranchia_---__ _. ___ ___ __ _______ _ _.______. ___ _________________ 48

prototypus, Gastrocopta. _ --- -.. ___ _ ..____ _ _________ _ ...___ 73

Pseudemys sp_ ..-_-__.__----__-.-...______________________ _ _______..._____.. 33

Psittacidae, indet __ -----_-__--_--____-__._-___-________________-___...__.._ 28

Psittaciformes. _------__- ___--__-______________.______ _ ________..._____.. 28

pulchella, Vallonia.. _.._____._..__ __ __ ___ . _ _ ___ _._ 6,12,13,33,34,35,36,76

Pulmonata.._ _--_-___-___-________-.__________.___.____._____ _ __...__.______ 51

pumila, Ferrissia ..... ___.--_______--___.______-_-__.._____.........._________. 62

pumilus, Ancylus . ... ------.-.--......... _ __________________________________ 61,62

punctatus, Ictalurus _ . _- --.._ ._._._ --.____. __ ____ 16

Punctinae._ __ ... __ ............ __ . __ ____ __ _.________.. ___ _ __ 79

Punctum.- _--_-_-__-__.__-__.----______________________ _ ___________________ 79

simum, ____________________________________________________ 36,44, 79

Pupilla blandi... ....____._________.__.........__._.______ 16,17,18,35

muscorum.-- _______________________________._.._____________ 7,16,18,35

Pupillid.._._-_. - - _ 26,41

PupiUidae..-------.-.---------_---.-.-----.--.--............._... 5,24,25,40,67,76

Pupillinae__---- __________________________________________________________ 74

Pupoides. _.__.-----_-_-_.________________________________________________._ 74

albilabris . ........ 3, 6,12, 23, 24, 26,27,29, 30, 31,32, 33,35, 36, 37, 39, 40,41, 74, pi. 1

hordaceus-..................._______..______.__________ 18

inornatus-- .......................... 6,12, 24, 25, 26,27, 29,30,33,35,36, 74, pi. 1

marginatus-.--..........................................._________ 74

(Ischnopupoides) inornatus_________________________ 74, pi. 1 

Pyganodon.................................................................... 45

(Pyganodon) grandis, Anodonta....-..................______________ 45

Pyrgophorus-- __________________________________ 51

guadriplicatus, Parahodomys. 

Quadrulidae..________. 

Quicketta----................

Q

.__________________________ 28 

... ................................ 45

.... . . ..-.......................... 77

vagans--. ...._______________..___________________ 24 

guinni, Oeomys......................._________________ 17,28,33,42

Rallus prenticei..

Rana ephippiumfayeae ..... 

meadensis..._ 

parvissima.-- 

rexroadensis 

valida.... __

__________._________________________ 27

____________________________.______ 27

 ______ 27

 _ __ _____ 27

_______________________________ 27

...._____________________________ 27

Rancholabrean age...________________...___.___...____. 19,21 

Recent mollusks from northern Nebraska____________....._____ 42

Red Corral local fauna________._____.___________ 11,17,05

reflexa, Galba-..-. _______....___.._____________________ 53

Stagnicola.. _.._...._..______ ... 6,12, 33, 35, 36, 39, 52, 53

regalis, Hypolagus__________..________.________________ 28

Reithrodontomys rexroadensis-- ..._______________...______-__ 28

wetmorei_____________________________________ 28

Page 

Reptilla...... 22,23,28,33,42

Petinella........................................ .... . . . .. 81

indentata .............. 39

rhoadsi. .. ... ... ... 6,12, 24,27,29, &

vheatleyL. --_______ 6,12,24,27,29, &

(Glyphyalops) rhoadsi.-- 81

(Glyphyalus) wheatleyi.................................................... 8/

retusa, Oxyloma. ........................ _ 6,12,24,36,37,39,44,77,78,79

rex, Paracryptotis........................... . ..... . .. . ....... 28

Rexroad formation 3,9,15 

Rexroad local fauna..__ 7,11,14,07 

rexroadensis, Bassariscus...................................................... 28

Gastrocopta............................. 3,11,12,17,23,24,25,26,27,29,38,73,pi. 1

(Immersidens) -............... ...............-..- ---........... 73, pi. 1

Mephitis............................. 28

Mu^ela..................... 28

Perognathus...................................... ....-. . ........... 28

Polygyra. ............................ 11,12,24,27,29,30,31,32,45,80, pi. 1, pi. 2

(Erymodon)- .....- . - - 82, pi. 1

Procyon.-................................. ........ -. .. 28

Prodipodomys. .............. ... . . 28

Pana............................. ..... -..... .... .. .. 27

Peithrodontomys.---...................................................... 28

Sorex............... 28

Testudo.. 28

rexroadi, Baiomys....................................... .. . . 28

Hesperoscalops..... 28

Spilogale....... .. 28

Rhinoceros indet_ 22 

rhoadsi, Petimlla.............................. - 6,12,24,27,29, 81

Phynchotherium sp_. 42

rinkeri, Synaptomys 37

Zapus.......... 28

Rita Blanca Creek.. 25

rivulans, Ferrissia-._____._ 3,6,12,17,22, 23,24,25, 26,27,29,30,33,35,36,37,39, 61 

robustocondyla, Anchylorana 27 

robustus, Sceloporus- 28 

Rodentia. .... . 22,23,28,33,37,40,42

rosaceum, Musculium 46 

rotundatm, Anisus........................... .. .. - - - - 56,57

ryckholti, Musculium 46

Salientia 22,23,27

Sand Draw local fauna....--. . 1,11,17,30

Sanders local fauna..__.. H, 16, Ifi 

sandersi, Sorex_____ . 40 

santacruzensis, Planorbis 45,60

Saw Rock Canyon local fauna..... ... ................. 3,9,11,14,00,25

sawrockensis, Baiomys 23

Ogmodontomys...__.- 23 

scaevoscala, Gastrocopta...-... ... .. . - 12,24,31,32,37,39,45, 70 

Scaphiopus diversus. __... .. - 27 

Sceloporus robustus - . 28 

., Buisnictis............................. ... . .... ..... 22,23

Scirpus. ... ... 61

Scolopacidae indet__ . 28

securis, Musculium.............. 46

Sphaerium ............................................................ 6,36,44, 46

Sediments, environmental interpretations.... 3

Seger local fauna____. .. 16

Shells, specific identification of..____ . 5

Sigmodon__.._ 16

hilli............. .............- .- . . 16

Mermedius. ________________ __ 28,40 

sp_ 37

sillimani, Oxyloma.-.. .. . 78 

simile planatum, Sphaerium .. ... 46 

simplex, Valvata tricarinata______ 48 

simplicidens,PlesippuS--.--. .- ........ .........- . 16,28,33,40,42

Symmetrodontomys_________ .. 28 

simus, Arctodus---. .. 17 

Sinalbinula. _______._. _ - 70 

singleyanus, Helicodiscus.. 3, 6,12,13,17, 23,24,27, 29,30, 31, 32,33, 35, 36,37, 39, 40, 41, 79 

Helicodiscus (Hebetodiscus)__._____ __ . 79 

skinneri, Physa............. 6, 8,12,13,16,17,24, 32, 33,34,35,36, 37, 39, 40,41,63, 64, pi. 3

Slaton local fauna______ __ ... 1 

Smilodon sp...___._.. .. 33 

Snake..- . 23,42
INDEX 93

Page 

Sorex.. ...... . ...... .......... .... ...................... .... ........ ... .... 16,17,39

cinereus ... .... .. ... .. ..... _. .. ___ _ . _ _ _____ __ . 18

dixonensis.----. ....... ...... .. ........ .................... _____ . __ . 37

leahyi .......

rexroadensis . 

sandersi ..... 

taylori... ...

...... __________________________ 37

._ . ........ -.. ........... 28

 .- .. . _.__ 40

 . _ __ 28

sp...... ..... .... -_.. . . 37

Soricidae ________ . _____________________ 23 

sparsicostata,Strobilops.- -......... 12, 22, 24, 25, 26, 27,29,30,33,35,36,37, 39, 65, pi. 1

spatulus, Gigantocamelus...................................................... 23,28

Sphaeriidae................ ___________________ 45

Sphaerium.................................................................... 45

crassum................................................................... 46

lacustre........................... .. ... . ..... 6,12, 36, 39, 44, 46

lineatum.. .................___________.___________._ 46

occidental..-............... . _______...._______... 53

partumeium..................... ........................ 6,12,33,35,36,39,45

securis --- -- ---- - . .......... 6,36,44,46

simile. .............................._____-_____________ 46

planatum _----.-----.................................__........_.. 46

striatinum............................................... 6,12,23,24,33,35,36,46

sulcatum..... .......... ............................. 6,12,26, 33, 35,36, 46

transversum.-.......... ......... .__________ 6,12,24,26,33,35,36,39,47

sp.... ..............- .. . .. 23,24,27,29,46,47

Spilogale rexroadi............................................................. 28

Squamata__________.__________________________ 22,23,28,42 

stagnalis jugularis, Lymnaea............................................._. 16,17,56

Stagnicola ._____________________ 39,52

bulimoides techella........... 3,6,12,13,16,23,24,25, 26, 27, 29, 30, 31, 32, 40,41,45, 54

caperata............. 6,12,13,18, 22, 24, 27, 29, 31, 32,33,35, 36,39, 40, 41,43, 44, 53, 54

cockerelli................................... .......__..____.__ 24

exilis.................. 6,12, 24,27, 29, 30,45, 51.

palustris ............ -- ................. 6,36,39,43,44,52,54

reftexa............. ............................. 6,12,33.35,36,39,52,53

sp... ..... 3,23,24,31,32,40,41,53,56

(Hinkleyia) caperata... __________...______...__.__.... 53

(Nasonia) bulimoides techella......................................__...__. 54

Stegomastodon mirificus....................................................... 16

primitivus_____.______..._______________.____ 33 

sp........ . . . ............ 28,42

steinii, Hydrobia... __________________________________ 50 

Stenotrema.... _______________ _____________________________ r _________________ 83

fraternum.._------.----- .---- ---............. .............__.__. 39

feat.. - - - _ _. _ __._ __ _ 6,36,44,83

leai__________________________________ _____________________ ......- 83

monodon...---_-__-_-__--___-_---_-____ ___________________.._._________ 83

sterkii, Fossaria parva_____._________________________________ .........._._...._ 55

Sterna'. sp_ 28

stirtoni, Cimarronomys- - -----------------_--_--___-__-_ __________._.__-___ 23

stovalli, Paradipoides-------...--.--.................._......_......._.... ..... 17

striatinum, Sphaerium--- __. .. -_ 6,12,23,24,33,35,36, 46

striatulatus, Eumeces..._ - .-- ___ _ __. ____ _ 23, 28

Strobilops.- , -- . _________ 65

densecostata_._.__________ ______________________________________________ eg

Zafcyrmttjco............................................. 3,6,12,17,23,24,65, pi. 1

sparsif-ostata ................. 12, 22, 24, 25, 26,27, 29,30,33,35,36,37,39, 65, pi. 1

texasiana. __- - - -- -- .____ __._ 65

Strobilopsidae_--_-_ _________________________ ....----..............__._..._. 65

Stylommatophora. ___________________________________ 22,23,25,27,31,33,37,40,42,65

Stump Arroyo member of Crooked Creek formation... ___ 3,15

subrostrata, Lampsilis... _____ _.__ ___ _.-_............_.. 45

Ligumia. ______________________________________________ 24,27,29,30,45

subtruncatum, Pisidium_______ ___ _ ______________ 17

Succinea... .............. 3, 23, 24, 25, 26, 27, 29,30,31", 32,33, 35, 36,37,39,40, 41,44, 77, 78

avara...........

concordialis _

grosvenori. _.

gelida_ _ _

luteola.-..__

------- 26,78

-.. 24,39,77

------- 78

------ 78

----- - 78

ovalis- -.---...--....-..---..-_........... -.....-........_..... g6, 44, 77, 78

vagtnacontorta_ - -----_---. - ............ .-........._________._ 24

sp-.._- .-- ..-......_..._ .......-.-......._......_...._... 78

Succineidae_ ---..--... - ._....._-... ___ _ _________ _ 5,8,77

sulcatum, SpAaeriMm..._________________________ _____________ 6,12,26,33,35,36,46

sweeti, Procastoroides. ..._.-------.---- -__ --_........ .....__...... 16,33,42

Symmetrodontomyssimplicidens. ______________________________________________ 28

Synaptomys landesi. 

rinkeri.-----....

(Mictornys) borealis.. 

Systematic descriptions.

Page

16

37

16

44

T 

Tanupolama blancoensis...--------------------------------------------------- 28

tappaniana, Gastrocopta.. 3,6,12, 23, 24, 27, 29,30, 31,32,33,35,36,37,39,40,41,44,72, 74 

Gastrocopta (Vertigopsis)................. . . -................___.. 72

Taxideataxus.....-.... ._.--.--..---.------.----------------- -.. - 28,33,42

Taxonomy, unsatisfactory. ........-..._..-._..............-.--..-----........ 8

taxus, randea- --------------------- . ... ....-------. .. 28,33,42

taylori, Sorex... 28

tazewelliana, Fossaria parva..____.________. _-. ._. . .__ 55

techella, Oalba bulimoides ___________ ________________________ ................ 54

Stagnicola bulimoides..____._ 3, 6,12,13,16, 23, 24, 25, 26,27,29,30,31,32, 40, 41, 45, 64

(Nasonia) bulimoides....___-.- --------_---------- __ __-_ 54

Teleodesmacea..--..........-... ...... . 22,23,25,27,33,36,45

Terrapene llanensis.-----------............................................... 17,18

Testudo - - -- - - -- ---------------------- 16,17,33,34,42

rexroadensis---.................._................-...._.-------------..... 28

turgida..-................................................................. 22,28

tetralasmus, Uniomerus---.---..-.----------.---------.-------------------- 24, 26, 45

texasensis, Polygyra texasiana----.............................................. 82

texasiana, Polygyra--..____......----- ------- . ----- .. ... 82

Strobilops-... ..__.__.__-_......._-__.......____-------- 65

texasensis, Polygyra...___-._... ------------------------------------------- 82

tholus, Polygyra mooreana..------- --___ _---------------- ----------- 82

Threskiornithidae, indet -_... .- - ---------------------- - . 28

tigrinum, Ambyttoma.................... .....................-..----. . 37, 40

tobinensis, Oeomys........................................... ...-_ _-_ _ 40

transversum, Musculium...................................................... 47

Sphaerium _______.................................. 6,12,24,26,33,35,36,39,47

tricarinata, Valvata. ......................... 6,7,12,13,16,17,33,34,35,36,39,44,48

basalis, VoJvata.-........--....-------..--................................ 48

infracarinata, Valvata.--------------- _-___________--_--__--__--_------- 48

mediocarinata, Valvata-.......................__________________..___..... 48

perconfusa, Vateata.................................. .......... ..... 48

simplex, Valvata...--------------------________-_._..--_--------------_- 48

unicarinata, Valvata- -__ -_ . _ ____-_-_- -__ 48

Trigonictis kansasensis..----.---------___ -------------------------------- __ 28,33

Triodopsis----------- __-------_---._-_-_-___________.................... 31

truncatum, Musculium...--___.......... _ . ----- -.---_----- ..__ .. 45

turgida, Testudo ............................................................ 22,28

turritella, Lymnaea....................--------- ...... _ .__. 38,45, 55,56

Turtle .- ... - - . -- - -- 23

U 

umbilicatellus, Gyraulus---.-------.----------------------------------------- 60

Menetus_-.._ __--.-------..-----.--..-...---------.-.-.--.-------.---- 60

Promentus-__....__________________......_ . ....... 3,

6,12,13,17, 23, 24, 25, 26,-27, 29, 30, 31,32,33, 35,36,37,39,40, 41,44,45, 54, 60 

(Phreatomenetus)..................................................... 60

unicarinata, Valvata tricarinata----. ._____- _____ _-__ _-- __-_ - .... 48

Uniomerus tetralasmus.- __---------- _- --___-_- ---_- _-__ -_ 24, 26, 45

Unionidae________________--____-__-__---_---_.__--..-__----_--_._--_--- 8,45

trivolvis, Helisoma . -- - .......... 6,12,24,26,36,39,44,59

Helisoma (Pierosoma)___ _._..------_--__----._____------_- _--_-__--__ 59

V 

vagans, Ouickella.-............................................................ 24

vaginacontorta, Succinea....___... -_ __ _ ____ __ -_ __ ........... 24

valida, Rana.-.......------...-.-.......--..--.-.-.-.-.-... .----.- ------- 27

Vallonia ----------------------- - -------------------- - ------- - ------ 76

costata. ........- -.--. -.--- --.-- -.--- 26,29

cyclophorella-------------------------------------------------------------- 16

gracilicosta......................................... 6,12,13,24,27,29,30,36,44,77

parvula------------------------------------------- 6,12,24,26,31,32,36,44,77

perspective -- - .- 3,12,13,17,23,24,26,27,29,30,37,39,40,41,77 

pidcheUa . 6,12,13,33, 34, 35, 36, 76

Valloniidae 76

Valvata. .- - -.-. -- . .. 48

lewiii . 6,12,13,33,34,35,36,45

helicoidea................-.-_----..---------------------.---.-.--.--.. 49

tricarinata-.. .. 6,7,12,13,16,17,33,34,35,36,39,44,48

basalis..-------------------------------------------------------------- 48

infracarinata.--.-.........---.-----.------.------------.------....--.- 48

mediocarinata.-------------------------------------------------------- 48

perconfusa.. ____... ___ ....__...-....- 48

simplex.--.- _____...._-...__--------_--.--- . 48

unicarinata.-- __.____..-------.--.-_--.__- . . 48

508945 O 60-
94 INDEX

Page 

Valvatidae.---------- --------_------.----....._...._..._.......... 48

Vanhem formation-..------.-.---__-.-.......__._____............ 3,15

Vertigininae_.___----------__--.------._---.------------....___. 74

Vertigo.-- _...._..._..._-...__.--_-----.-__--.__......_..__. 74

bermudensis______--------_...-_------____--_---....__.. 76

gouldi --- - ---------. - . . .......................... 16,35

hibbardi- . ............... 3,11,12, 22,23,24,27, 29, 30, 32, 38, 45, 74, 76, 76, pi. 1

milium. ..--..-....- 2,3,6,12, 23,24,25, 26,27, 29, 30, 31, 32,33, 35,36, 37, 39, 40,41, 76

modesta..................... ____..____.________._______ 16,35

numellata... .._._..._..._._--.-._..__.....____..___. 76

ovata .......................... 6,11,12, 22, 24, 26, 32, 33, 35, 36, 37, 40, 41, 44, 74, 76

diaboll................................................................ 76

(Angustula) hibbardi................................_.-------............ 45

Vertigopsis_..._._---._.........._..__-------_-__-._..__-..... 72

Villafranchian fauna._..__-.--------------.----_....-------.-.----............ 21

Viviparidae ........................................................... 8,36,39,49

W 

walkeri, Amnicola--.-------.-----------.----------.------------------------- 45, 49, 50

Pisidium--.---...... ..-__--. ___-_-. ---..-_ ------- --------- 17

Washing technique...---_--_._-. .____. --------_.-.--._-.----- 1,2

wetmorei, Ffeithrodontomys..... ___-____.-__.-.-.-.--__..... . 28

wheatleyi, ffettraeHa. . 6,12,24,27,29,81

Petinella (Glyphyalus)---.....................................-__- - 81

wilsoni, Dipoides... _.-.-_----_.-_-_ __._-. -------- 23

Zapusrinkeri-

.-.............. ........ . 16

- - - - 28

Zenaidura macroura__---------.--------_--_--------------------_----------- 28

Zomtidae-------------------------------------------------------------- 5,80

Zonitinae..__-__---..-____._.. .___---.._. _.-.-- 80

Zonitoides-................................................................. 81

arboreus.-- .....-- 6,12, 24,27, 29, 31,36, 37, 39,44,80,8/

Zygospores of Chara...----_- _--.-__..._----------- ------ -.. 2

o
PLATES 1-4
PLATE 1

FIGFRES 1-4. Acroloxus color ad ensis Henderson, X 1% (p. 61). 

Sand Draw local fauna.

1, 2. UMMZ 181129a. 

3, 4. UMMZ 181129b.

5, 6. Strobilops labyrinthica (Say), X 7^ (p. 65). 

Saw Rock Canyon local fauna.

5. UMMZ 177561b.

6. UMMZ 177561a. 

7-10. Strobilops sparsicostata Baker, X 1% (p. 65).

7. Sand Draw local fauna. UMMZ 184178a.

8. Topotype. Rexroad local fauna. UMMZ 183032a.

9. Topotype. Rexroad local fauna. UMMZ 183032c.

10. Topotype. Rexroad local fauna. UMMZ 183032b. 

11-16. Gastrocopta chauliodonta Taylor (p. 70).

11. Sanders local fauna. Basal view, X 22^, of dissected specimen showing columellar and anguloparietal 

lamellae. UMMZ 182152e.

12. Paratype. Sand Draw local fauna. X 15. UMMZ 181121a.

13. Sanders local fauna. Basal view, X 22^, of dissected specimen showing columellar and anguloparietal 

lamellae. UMMZ 182152e.

14. Sanders local fauna. Spiral view, X 15, of body whorl of dissected specimen showing the very deeply immersed lower palatal fold. UMMZ 182152a.

15. Sanders local fauna. Lateral view, X 22^, of dissected specimen showing columellar lamella. The basal 

part is incompletely joined to the rest of the lamella, and gives the appearance of a subcolumellar lamella. 

UMMZ 182152c.

16. Sanders local fauna. Basolateral view, X 22^, of dissected specimen showing anguloparietal and columellar lamellae. UMMZ 182152b. 

17, 23. Polygyra rexroadensis Taylor, n. sp. (p. 82).

Holotype, X 1%. Two views of aperture. UMMZ 177610a. 

18-22. Vertigo hibbardi Baker, X 15 (p. 75).

18. Topotype. Rexroad local fauna. UMMZ 183041a.

19. Saw Rock Canyon local fauna. UMMZ 177566b.

20. Saw Rock Canyon local fauna. Basolateral view of dissected specimen, showing angular, parietal, and 

columellar lamellae. UMMZ 177566c.

21. Saw Rock Canyon local fauna. UMMZ 177566a.

22. Topotype. Rexroad local fauna. UMMZ 183041a. 

24-26. Gastrocopta cristata (Pilsbry and Vanatta), X 15 (p. 69).

24. Sanders local fauna. UMMZ 182183b.

25. Sanders local fauna. UMMZ 182183c.

26. Sanders local fauna. UMMZ 182183a.

27. Gastrocopta procera (Gould), X 15 (p. 67).

Figured specimen. Dixon local fauna. UMMZ 182217.

28. Gastrocopta pellucida hordeacella (Pilsbry), X 15 (p. 71).

Figured specimen. Rexroad local fauna. UMMZ 183037a.

29. Gastrocopta franzenae Taylor, n. sp., X 15 (p. 67).

Figured specimen. Saw Rock Canyon local fauna. Specimen with bifid anguloparietal lamella and strong 

labial tubercle. UMMZ 177563a.

30. Gastrocopta rexroadensis Franzen and Leonard, X 15 (p. 73).

Red Corral local fauna. UMMZ 183004a. 

31, 32. Gastrocopta paracn'stata Franzen and Leonard, X 15 (p. 69).

31. Figured specimen. Bender local fauna. UMMZ 177507b.

32. Figured specimen. Bender local fauna. Basal fold absent. UMMZ 177507a. 

33, 34. Gastrocopta scaevoscala Taylor, n. sp., X 15 (p. 70).

33. Holotype. UMMZ 184320.

34. Paratype. Bender local fauna. Lateral view of dissected specimen showing ascending columellar lamella.

Dotted line marks shell axis. UMMZ 183017a. 

35. Pupoides inornatus Vanatta, X 7/£ (p. 74).

Rexroad local fauna. UMMZ 183074a. 

36. 37. Pupoides aUiilabris (Adams), X 7H (p. 74).

36. Sanders local fauna. UMMZ 182158b.

37. Sanders local fauna. UMMZ 182158a.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 337 PLATE 1

37

LATE PLIOCENE AND PLEISTOCENE MOLLUSKS FROM THE HIGH PLAINS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 337 PLATE 2

"ll

A

17

12 13

.I**-

- »* .

f

23 24

V 20

A

10

t

15

A

tW

21

11

16

25
PLATE 2

FIGURES 1-3, 7, 8. Marstonia crybetes (Leonard), X 10 (p. 50).

Topotypes, Saw Rock Canyon local fauna.

1. UMMZ 177554e. "

2. UMMZ 177554b.

3. UMMZ 177554a.

7. UMMZ 177554c.

8. UMMZ 177554d.

4, 5. Polygyra rexroadensis Taylor, X 3 (p. 82). 

Holotype, Rexroad local fauna.

4. Apical view.

5. Basal view. 

6, 12-14, 17, 18. Fossaria dalli (Baker), X 10 (p. 54).

Topotypes of Lymnaea turritella Leonard, Saw Rock Canyon local fauna.

6. UMMZ 177555a.

12. UMMZ 177555b.

13. UMMZ 177555f.

14. UMMZ 177555d.

17. UMMZ 17755oe.

18. UMMZ 177555c. 

9. Marstonia derepta (Baker), X 10 (p. 51).

Figured specimen, Saw Rock Canyon local fauna, UMMZ 186155a. 

10, 11, 15, 16. Fossaria dalli Baker, X 10 (p. 54).

Figured specimens, Jinglebob local fauna.

10. UMMZ 181151a.

11. UMMZ 181151d.

15. UMMZ 18ll51b.

16. UMMZ 181151c. 

19-27. Fossaria dalli Baker, X 10 (p. 54).

Figured specimens, Rexroad local fauna. Population showing wide range of variation and approaching 

F. parva.

19. UMMZ 177598d.

20. UMMZ 177598b.

21. UMMZ 177598a.

22. UMMZ 177598c.

23. UMMZ 177598i.

24. UMMZ 177598h.

25. UMMZ 177598g.

26. UMMZ 177598f.

27. UMMZ 177598e.
PLATE 3

FIGUKES 1-4. Physa hordacea Lea, X 5 (p. 64).

Paratypes, Recent, Vancouver, Washington. USNM 170764. 

5, 6. Physa skinneri Taylor, X 5 (p. 63).

Recent, Uinta Mountains, Utah. USNM 533484. 

9-11. Physa skinneri Taylor, X 5 (p. 63). 

Paratypes, Berends local fauna.

9. UMMZ 177533c.

10. UMMZ 177533a.

11. UMMZ 177533b. 

7, 8, 12-20, 23, 24, 27, 28. Promenetus kansasensis (Baker), X 20 (p. 59).

Sand. Draw local fauna loc. 6. Specimens from an unusually variable population showing variation 

in sculpture and shape.

7,12,16. UMMZ 177430a.

8,13,17. UMMZ 177430b.

14, 15, 18. UMMZ 177430d.

19. 23, 27. UMMZ 177430e.

20. 24, 28. UMMZ 177430c. 

21, 22, 25, 26, 29, 30. Promenetus kansasensis (Baker), X 20 (p. 59).

Sand. Draw local fauna loc. 2. Unusually large specimens with expanded body whorl, analogous 

to P. exacuous (Say) form megas (Dall).

21. 25, 29. USNM uncat.

22. 26, 30. USNM uncat.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 337 PLATE 3

27 28 29 " '30 

LATE PLIOCENE AND PLEISTOCENE MOLLUSKS FROM THE HIGH PLAINS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 337 PLATE 4

LATE PLIOCENE AND PLEISTOCENE MOLLUSKS FROM THE HIGH PLAINS
PLATE 4

FIGURES 1-3, 5-7, 10-12. Gyraulus parvus (Say), X 20 (p. 58).

Dixon local fauna loc. 1.

1. 5, 10. UMMZ 182200b.

2. 6, 11. UMMZ 182200a.

3. 7, 12. UMMZ 182200c. 

4, 8, 9, 13, 17, 18 Gyraulus parvus (Say), X 5 (p. 58)

Topotypes of G. enaulus Leonard, Saw Rock Canyon local fauna. 

4,8,9. UMMZ 177556a.

13. 17, 18. UMMZ 177556b.

14-16, 19-26. Deroceras aenigma Leonard, X 10 (p. 80). 

Topotypes, Rexroad local fauna loc. 3.

14. UMMZ 183047d Ventral view.

15. UMMZ 183047k

16. UMMZ 183047h

19. UMMZ 183047J

20. UMMZ 183047e

21. UMMZ 1830471

22. UMMZ 183047b

23. UMMZ 183047c

24. UMMZ 183047f

25. UMMZ 183047g

26. UMMZ 183047a

Dorsal view.

Dorsal view, sinistral specimen.

Ventral view.

Dorsal view.

Dorsal view.

Dorsal view.

Dorsal view.

Dorsal view.

Dorsal view.

Dorsal view.

U.S. GOVERNMENT PRINTING OFFICE: 1960 O -508945