Contributions to 

Paleontology, 1970

GEOLOGICAL SURVEY PROFESSIONAL PAPER 683

This volume was published 

as separate chapters A-E
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS G. B. MORTON, Secretary

GEOLOGICAL SURVEY 

W. A. Radlinski, Acting Director
CONTENTS

[Letters designate the separately published chapters]

(A) Late Miocene nonmarine diatoms from the Kilgore area, Cherry County, Nebraska, by George W. Andrews.

(B) The Early Cambrian fossil Salterella conulata Clark in eastern North America, by Ellis L. Yochelson.

(C) Foraminifera from the Bahama Bank west of Andros Island, by Ruth Todd and Doris Low.

(D) Climatic implications of a late Pleistocene obstracode assemblage from southeastern Virginia, by Page C. Valentine.

(E) Early Miocene nonmarine diatoms from the Pine Ridge area, Sioux County, Nebraska, by George W. Andrews.

U. S. GOVERNMENT PRINTING OFFICE : 1971 O - 428-195

Late Miocene 

Nonmarine Diatoms 

From the Kilgore Area, 

Cherry County, 

Nebraska

By GEORGE W. ANDREWS

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 683-A

A description of a late Miocene nonmarine 

diatom assemblage from the Great Plains 

region and its stratigraphic and 

paleoecologic significance

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1970
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

Library of Congress catalog-card No. 70-607395

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

Washington, D.C. 20402 - Price 50 cents (paper cover)
CONTENTS

Page

Abstract __ _____ Al

Introduction 1

General features __________ . 1

Acknowledgments _____-__ . 1

Kilgore diatomite deposit __ . 1

Location ________________________ __ . 1

Stratigraphic section __________ __ . 2

Valentine Formation __________ _________ . 3

General features _____________________. 3

Page

Valentine Formation Continued

Vertebrate paleontology _____ ____________ A5

Paleobotany __ ____ _ _ __ . 5

Diatom assemblage _______

General features ___________

Stratigraphic significance _.

Paleoecologic interpretation

Systematic descriptions _____.

_____________ _____. 5

	5 

____________. 5

_____________. 7

_____________________ 8

Selected references _____________________. 21

Index ________________________________. 23

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Melosira, Tetracyclus, Fragilaria, Synedra, Eunotia, and Achnanthes.

2. Stauroneis, Anomoeoneis, Neidium, and Navicula.

3. Pinnularia, Cymbella, Gomphonema, and Nitzschia.

FIGURE 1. Index map showing the Kilgore area, Nebraska __ __-__ 

2. Map showing the Kilgore fossil-diatom locality, Cherry County, Nebr __

3. Photographs showing lithologic units at the Kilgore fossil-plant locality

Page

A2

3

4

TABLE

TABLE 1. Relative abundance of diatoms from six collections in the Kilgore diatomaceous deposits

Page

A6

in

CONTRIBUTIONS TO PALEONTOLOGY

LATE MIOCENE NONMARINE DIATOMS FROM THE 

KILGORE AREA, CHERRY COUNTY, NEBRASKA

By GEORGE W. ANDREWS

ABSTRACT

The Valentine Formation of A. L. Lugn, which is of late 

Miocene and early Pliocene age, contains diatomaceous and 

plant-bearing sediments at a locality on the north bluff of 

the Niobrara River, about 10 miles south of Kilgore, Cherry 

County, Nebr. The fossil flora has been studied by H. D. 

MacGinitie, who concluded that the deposit is of late Miocene age. Correlative strata near Valentine, Nebr., several 

miles east of this locality, are reported to contain a vertebrate fauna of late Miocene age.

The Kilgore diatom assemblage consists of 45 taxa of 

nonmarine diatoms. Of these, four species are herein recorded as new, one species has been previously reported 

from the middle Pliocene of France, and the remaining 40 

taxa are identified as still living in modern nonmarine environments. The diatom assemblage suggests deposition in a 

relatively shallow, small lake. The waters of this lake were 

probably hard, and perhaps at times somewhat alkaline or 

saline. It is difficult to separate the influences of ecology and 

geologic age on the composition of the diatom assemblage, 

but this problem should be resolved as other Tertiary assemblages are studied. The five presumably extinct species may 

prove to be useful for stratigraphic correlation when their 

geologic ranges are better known. The composition of the 

assemblage, the relative number of taxa, and the absence of 

several widespread modern genera and species of nonmarine 

diatoms should be of value in identifying other late Miocene 

assemblages and in distinguishing them from assemblages 

of different age.

INTRODUCTION 

GENERAL FEATURES

The Kilgore diatomaceous beds crop out among 

the small and discontinuous exposures of the Valentine Formation of Lugn (1938) found along the 

highly dissected north bluff of the Niobrara River 

in Cherry County, Nebr. Diatomite and diatomaceous 

shale containing a well-preserved fossil flora are exposed at a site about 10 miles south of the village of 

Kilgore. The plant remains were described and 

dated as late Miocene by MacGinitie (1962). The

diatomaceous deposit has also been correlated with a 

late Miocene vertebrate fauna from Valentine, Nebr.

The Kilgore deposit contains the first Tertiary nonmarine diatom assemblage from the Great Plains 

area of North America to be systematically studied. 

The preservation of the diatom assemblage is good. 

The age of the deposit is confirmed by two independent lines of evidence. The Kilgore diatom assemblage 

occurs in a deposit of known and stratigraphically 

significant age close to the Miocene-Pliocene boundary. This provides a valuable reference marker for 

understanding and determining the stratigraphic 

ranges of the Tertiary nonmarine diatoms.

This occurrence of diatomite was called to the 

attention of the writer by a sample submitted by Dr. 

Morton Green of the Museum of Geology, the South 

Dakota School of Mines and Technology, Rapid City, 

in 1962. The fossil-plant locality was examined in 

1965 and samples were taken for diatom study. An 

unsuccessful search for additional diatomiferous 

sediments was made in the vicinity of Valentine, 

Nebr., in 1966.

ACKNOWLEDGMENTS

The helpfulness of Morton Green in transmitting 

a sample of the Kilgore diatomite is gratefully 

acknowledged. The owners of the Drinkwalter Ranch 

kindly permitted access to their property so that the 

outcrops could be studied. Thanks are expressed to 

Kenneth E. Lohman, Division of Paleobotany, The 

Smithsonian Institution, and to Sergius H. Mamay, 

U.S. Geological Survey, for their critical review of 

the manuscript.

KILGORE DIATOMITE DEPOSIT 

LOCATION

Diatomaceous sediments of Lugn's Valentine ForAl
A2 CONTRIBUTIONS TO PALEONTOLOGY

mation crop out on the north valley wall of the Niobrara River, approximately 10 miles south of the village of Kilgore, Cherry County, Nebr. The location 

of the Kilgore area in north-central Nebraska is 

shown in figure 1. The sample of diatomite submitted 

by Morton Green was described as coming from the

p______ _102^ Valentine, 100°

"I j£>gor<£ ~P^T " " 

.Crawford^^T "-*KjigOr> ^'

^l diatom

50 100 MILES

FIGURE 1. Kilgore area, Nebraska.

SW14NW14 sec. 33, T. 33 N., R. 31 W. The samples 

of diatomaceous sediments collected by the writer 

came from the fossil-plant locality, described by MacGinitie (1962), in the W^NE^i sec. 34, T. 33 N., R. 

31 W. (fig. 2).

The Kilgore diatomite locality is readily accessible 

from a road skirting the base of the north bluff 

along the Niobrara River. The fossil-plant-bearing 

bed at the base of the diatomaceous section occurs at 

approximately the 2,700-foot contour level (fig. 2) 

and about 85 feet above the average water level of 

the Niobrara River (MacGinitie, 1962, p. 69-70). 

The outcrops exposed in 1965 were by no means as 

extensive as suggested by MacGinitie's map (1962, 

p. 70). The hard siliceous plant-bearing shale containing fossil plants crop out discontinuously in the 

area, but the soft overlying diatomaceous sediments 

are seen only in new excavations. Considerable sand 

slumped from overlying deposits covers the diatomaceous section in many areas and prevents the lateral 

tracing of beds for any distance.

STRATIGRAPHIC SECTION

The geology and stratigraphic section of the Kilgore fossil-plant locality have been accurately described by MacGinitie (1962, p. 72-76), and the following discussion is modified from his work. The 

diatomaceous section is underlain by about 75 feet of 

fine calcareous sands of the Valentine Formation, 

which lie disconformably on siltstones of Hemingfordian age equivalent to the Rosebud Formation of 

South Dakota and the Marsland Formation of western Nebraska according to Webb (1969, p. 7). The 

section is overlain by an unknown thickness of fine 

sands and sandstones of the Valentine Formation. 

The diatomaceous interval is considered to be in the 

lower part of the Valentine Formation as more of 

the Valentine is above the interval than below it. It 

consists of 8 or 9 feet of shaly sediments containing 

some diatomaceous layers.

The following beds can be identified at the Kilgore 

locality:

Thickness 

Ft in

7. Tan silty diatomite (fig. 34). USGS diatom 

locality 5837, sample from 2 to 5 in. above 

base of unit _______ 1 0

6. Massive sandy silt ___ _ 2 6

5. Soft buff diatomaceous shale with carbonaceous 

specks (fig. SB). USGS diatom locality 5836, 

sample from about 15 in. above base of unit __ 2 7

4. Hard greenish-gray finely laminated siliceous

shale with hackly fracture _.______ 0 4

3. Soft white very fissile diatomite with carbonaceous matter (fig. 3C). USGS diatom locality 

5835; sample from 5 to 6 in. above base of 

unit. USGS diatom locality 5834, sample from 

2 to 3 in. above base of unit __ __ 1 0

2. Soft brown fissile diatomaceous organic matter 

immediately overlying the plant-bearing shale 

(fig. 3C). USGS diatom locality 5833; sample 

from first inch above the plant-bearing shale 0 2

1. Hard gray finely laminated siliceous calcareous 

shale with platy fracture (fig. 3C, D). This 

is the main fossil leaf bed of the Kilgore 

locality, and plant remains are abundant and 

well preserved. USGS diatom locality 5832; 

sample from upper 2 in. of unit ________ 0 6

The sample taken from unit 1, the plant-bearing 

shale (USGS diatom locality 5832) did not contain 

diatoms. The overlying organic matter of unit 2 

(USGS diatom locality 5833) was relatively poor in 

diatoms. It is thought that both of these units were 

originally highly diatomaceous, but that the diatoms 

were leached from them by percolating alkaline 

waters. Perhaps some of the diatom silica was 

leached from the highly organic unit 2 and redeposited in the underlying plant-bearing shale. This 

would account for the partial silicification of the 

plant-bearing bed and the remarkable preservation 

of the Kilgore flora. Units 4 and 6 were not thought 

suitable for diatom preservation, and were not studied.

The outcrop that furnished the sample submitted 

by Morton Green was not located because of the 

limited time available for fieldwork. The sample
101°00' 

42°50'

MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA

100°55'

A3

42°45'

Base from U.S. Geological Survey 

1:62,500 Kilgore, 1950

1MILE

FIGURE Z. Kilgore fossil-diatom locality, Cherry County, Nebr.

(USGS diatom locality 5419) consists of a soft white 

fissile diatomite with fish scales and poorly preserved 

leaf fragments. MacGinitie (1962, p. 76) states that 

the plant-bearing shales merge into pure diatomite 

about a mile to the west, that is, in the direction of 

locality 5419. He also indicates that these sediments 

are restricted in lateral distribution by stating (p.

76), "The lake sediments are exposed in the Niobrara River bluffs for a distance of about 1% miles, 

and they end abruptly both at the east and west 

boundary."

VALENTINE FORMATION 

GENERAL FEATURES

The Kilgore diatomite deposit occurs in the Valen-
A4 CONTRIBUTIONS TO PALEONTOLOGY

FIGURE 3. Kilgore fossil-plant locality. A, Tan silty diatomite of unit 7, uppermost diatomaceous layer. B, Soft buff diatomaceous shale of unit 5. C, Units 1-3. D, Slabby, siliceous shale of unit 1 containing the Kilgore fossil flora.

tine Formation, which is the lowermost unit of the 

Ogallala Group as redefined by Lugn (1939, p. 1258- 

1264) from the original Ogallala Formation of Darton (1898). The Ogallala Group of Lugn (1938) 

contains the following subdivisions (in ascending 

order) : Valentine Formation, Ash Hollow Formation, Sidney Gravel, and Kimball Formation. The 

Valentine Formation was originally defined as the 

"Valentine beds" by Barbour and Cook (1917, p. 

173) and was redefined as a formation in the Ogallala Group by Lugn (1938). The lower boundary of 

the Valentine Formation was tenuously suggested by
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A5

Lugn as the base of the Pliocene, but he recognized 

the necessity of further fossil data before a positive 

age determination could be made.

VERTEBRATE PALEONTOLOGY

The Kilgore fossil-plant and diatom locality occurs 

about 75 feet above the base of the Valentine Formation. The nearest vertebrate remains at approximately the same stratigraphic level in the lower part 

of the Valentine Formation occur near Valentine, 

Nebr., about 22 miles east of the Kilgore locality. 

This fauna has been designated the Niobrara River 

fauna by Stirton and McGrew (1935, p. 129), who 

state as follows: "Although we have called the Niobrara River fauna an Upper Miocene fauna, it is 

practically transitional between the Upper Miocene 

and the Lower Pliocene, but nearer to the Miocene 

than the Pliocene." The Niobrara River fauna of 

Stirton and McGrew (1935) is distinctly older than 

the Valentine fauna of these authors and others, and 

the Valentine fauna occurs in the Ash Hollow Formation. This confusion between the Valentine fauna, 

a fossil zone, and the Valentine Formation, a rock 

unit, has been ably discussed by Johnson (1936), 

Lugn (1939), and MacGinitie (1962). The Niobrara 

River local fauna has been designated as Barstovian, 

and the lower part of the Valentine Formation is 

shown as late Miocene age by Wood and others 

(1941).

The correlation of the Kilgore diatomite assemblage with the Niobrara River fauna of Stirton and 

McGrew (1935) on the basis that they both occur 

about 75 feet above the base of the Valentine Formation is not without peril. Moreover, the diatomite 

deposit is of relatively small extent and cannot be 

traced laterally for more than 2 miles. There is no 

lithologic equivalent to the diatomite at Valentine, 

for the vertebrate fossils occur in sandy sediments 

which are not likely to contain diatoms. On the other 

hand, both the Kilgore deposit and Niobrara River 

fauna at Valentine occur in approximately the same 

relative stratigraphic position, in the lower beds of 

the Valentine Formation. Although it is impossible 

to assure an exact correlation, the probability of 

their near age equivalence is strong. The Kilgore 

diatomite deposit is, therefore, probably very late 

Miocene in age on the basis of vertebrate paleontological evidence.

PALEOBOTANY

The fossil plants of the Kilgore locality have been 

ably described by MacGinitie (1962), who discussed

the ecologic and climatic aspects of the flora. He has 

also examined thoroughly the relationships of the Kilgore flora to possible correlative floras, but he recognizes the difficulties imposed by the great distances 

from Kilgore to other well-known fossil-plant localities. However, on the basis of the flora alone, he concludes that the Kilgore flora is more modern than 

the Mascall flora of Oregon described by Chaney 

and Axelrod (1959) but not as advanced as the 

Weiser flora of Idaho described by Dorf (1936). The 

Mascall flora is considered to be Barstovian (late 

Miocene) in age. The Weiser flora, partly on stratigraphic and vertebrate fossil evidence, is considered 

to be earliest Pliocene in age. MacGinitie (1962, p. 

105) concludes that the most probable age of the 

Kilgore flora is late Miocene or Barstovian. Taking 

into consideration that it appears to be younger than 

the Mascall flora, it may be considered to be latest 

Miocene on the basis of the floral evidence.

DIATOM ASSEMBLAGE 

GENERAL FEATURES

The samples were prepared for diatom study following standard laboratory procedures. All the 

samples were noncalcareous, and they disintegrated 

readily in distilled water. Organic matter was removed chemically, and coarse particles were eliminated by decantation of the diatoms and other suspended sediment. The cleaned samples were mounted 

as strewn slides in kollolith, a synthetic resin with 

approximately the same refractive index as Canada 

balsam. Specimens were located by systematic traversing with a mechanical stage, and their locations 

were recorded as coordinates of the mechanical stage. 

The relative abundance of each diatom taxon in the 

six studied assemblages is shown in table 1. USGS 

diatom localities 5833-5837 represent collections 

from different stratigraphic levels at the Kilgore 

fossil-plant locality of MacGinitie (1962), and the 

exact position of these collections is given in the discussion of the stratigraphic section. USGS locality 

5419 is a collection made about a mile west of MacGinitie's fossil-plant locality.

STRATIGRAPHIC SIGNIFICANCE

This report represents the first stratigraphic 

study of a Tertiary nonmarine diatom assemblage 

from the Great Plains region of North America. 

Although fossil marine diatoms have been extensively studied in many parts of the world, little has 

been published on fossil nonmarine diatom assem-
A6 CONTRIBUTIONS TO PALEONTOLOGY

TABLE 1. Relative abundance of diatoms from six collections 

in the Kilgore diatomaceous deposits

[A, abundant; C, common; F, frequent; R, rare]

USGS diatom locality

Melosira granulata (Ehrenberg) Ralfs _ 

var. ang^lstissima Miiller ___________

italica (Ehrenberg) Kutzing _______

distans (Ehrenberg) Kutzing _______

Tetracyclus lacustris Ralfs - 

pagesi Heribaud __________________

tripartitus Brun and Heribaud _____

rupestris (A. Braun) Grunow ______

cruciformis Andrews, n. sp. - -

Fragilaria brevistriata Grunow ________

gigantea Lauby _____-____________

Synedra rumpens Kutzing . 

ulna (Nitzsch) Ehrenberg _________

Eunotia parallela Ehrenberg _______ 

pectinalis var. minor (Kutzing) 

Rabenhorst .___________________

Achnanthes hungarica (Grunow) 

Grunow ____________________

Stauroneis phoenicenteron (Nitzsch)

Ehrenberg _________________.

anceps Ehrenberg ___________

smithii Grunow ___________-

lauenburgiana Hustedt _____________

Anomoeoneis sphaerophora

(Ehrenberg) Pfitzer _________.

Neidium iridis var. ampliata

(Ehrenberg) Cleve -_________________

Navicula amphibola Cleve ______________

niobrara Andrews, n. sp ____________

actinota Andrews, n. sp __________

cuspidata (Kutzing) Kutzing _______

bacillum Ehrenberg _________________

radiosa Kutzing ____________________

graciloides A. Mayer __________

anglica var. subsalsa (Grunow) Cleve 

elginensis (Gregory) Ralfs ____ 

elginensis var. rostrata (A. Mayer) 

Patrick .______________________

Pinnularia subcapitata var. paucistriata 

(Grunow) Cleve ______________________

brevicostata Cleve ___________. 

clevei Patrick _______________________

torta (Mann) Patrick _ _________

viridis (Nitzsch) Ehrenberg _______

Cymbella naviculiformis Auerswald ____

ehrenbergii Kutzing ________________

cistula (Hemprich) Grunow ____ 

var. maculata (Kutzing) Van Heurck 

tumida (Brebisson) Van Heurck ___

Gomphonema affine var. insignis

(Gregory) Andrews, n. comb _________

Hantzschia elongata (Hantzsch) 

Grunow ______________-_____.

Nitzschia calva Andrews, n. sp .._________

O3 CO M1 W CD ti-H CO CO CO CO CO

 * CO 00 00 00 00 1/5 in in in 10 in

C C A A __ __

C C A A __ __

A __ C C A A

C R - R - __

R R R F __ __

F __ R R R __

R __ __ R __ __

R R __ R __ __

- __ __ __ F __

A R __ R A __

F __ R R __ __

__ __ __ R __ __

F __ F F __ R

F __ R R __ __

F __ __ R R __ 

__ __ __ R __ __

__ __ F _. __

R __

F R

R __

F __ F 

F __ __

F __ R

R I ~

- R

F R R

F __ __

R C R

- C C

__ R __

__ R R

- R R

R __ __

R __ __

R C~ R~

- R __

R __ __

R " R

F __ __

F __ __

C _. R

A R R

C __ F

R __ __

__ R -

F

R __ F

R __ __

F A C

F F __

__ __ F

C F F F C F

_- __ __ __ F __

- ._ __ __ R __

blages. The late Eocene nonmarine diatoms of the 

Beaver Divide area of Wyoming have been reported 

upon by Lohman and Andrews (1968). This assemblage, however, is considerably older than the late 

Miocene deposit studied here, and it has a distinctly 

different composition. A late Pleistocene diatom assemblage from Wisconsin was studied by Andrews 

(1966) and proved to be mainly modern in aspect. 

The Kilgore assemblage falls between these extremes

in time, and it seems to show some intermediate 

aspects.

Lauby (1910) published a report on Tertiary nonmarine diatoms from several localities in the Massif 

Central of France. On the basis of his studies, he 

extended the stratigraphic ranges of many modern 

taxa of nonmarine diatoms back to the Miocene and 

Oligocene Epochs. A critical examination of Lauby's 

work shows that most of his "Oligocene" nonmarine 

diatoms came from the Aquitanian Stage, which is 

lower Miocene in modern terminology. Aside from 

this change in stratigraphic nomenclature, many of 

Lauby's claims on stratigraphic ranges of diatom 

taxa seem extravagant in comparison to the known 

ranges in North America. Although it appears that 

Lauby was a competent diatomist, he correlated the 

volcanic rocks and lake sediments of the Massif 

Central primarily on the basis of fossil plants. A 

critical reevaluation of these paleobotanical correlations should be made before any of Lauby's diatom 

ranges can be accepted.

The Kilgore diatom assemblage consists of 45 species and varieties of nonmarine diatoms. Of these, 

four species (Tetracyclus cruciformis, Navicula niobrara, Navicula actinota, and Nitzschia calva) are 

new, and one species, Fragilaria gigantea, has been 

found in beds of possible middle Pliocene age in 

France. A form similar to Tetracyclus cruciformis 

has been reported from Miocene deposits in the 

U.S.S.R. The remaining 40 taxa are still living in 

modern nonmarine environments.

The absence of many modern genera and species 

from the Kilgore diatom assemblage may be of as 

much significance as the composition of the assemblage. It is difficult to ascertain, on the basis of only 

one studied assemblage, whether some forms had not 

yet evolved or whether they are missing only because 

of ecological factors. When the Kilgore assemblage is 

contrasted with modern assemblages, there are obvious differences that should be pointed out. The significance of these differences must be considered at 

present as tentative and subject to modification when 

other Tertiary fossil diatom assemblages are investigated.

The genera Cyclotella and Stephanodiscus, centric 

diatoms common in modern assemblages, are both 

absent from the Kilgore assemblage. Of the subfamily 

Tabellarioideae, the genera Tabellaria, Diatoma, and 

Meridian, all common in modern assemblages, are 

absent, although the subfamily is represented by 

Tetracyclus. The Eunotiaceae are represented only 

by two relatively simple species of Eunotia. Cocco-
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A7

neis is missing from the assemblage, and Achnanthes 

is rarq. The naviculoid genera, Mastogloia, Colonels, 

and Diploneis are missing although the family is 

well reipresented. Even the genus Navicula, however, 

does not show the rich variety common in modern 

assemblages. Amphora has not been recorded 

although its near relative Cymbella occurs with notable abundance though without much variety. Gomphonema is represented by only one taxon, and that 

is highly variable in composition. There is nothing 

to suggest the wide variation shown by modern 

Gomphonemas as, G. affine var. insignis is a rather 

generalized, possibly primitive, form. Perhaps of 

most significance is the total lack of the Epithemiaceae Denticula, Epithemia, and Rhopalodia. These 

genera are common and widespread in modern assemblages, and their lack in the Kilgore assemblage 

is of importance. The Surirellaceae have not been 

noted in the Kilgore assemblage, but they are less 

often abundant in modern assemblages.

The Kilgore assemblage has 45 species and varieties which are included in 15 genera. A late Pleistocene assemblage of virtually modern aspect described 

by Andrews (1966) contains 73 species and varieties 

included in 23 genera. In contrast, the late Eocene 

diatom assemblage from the Beaver Divide locality 

of Lohman and Andrews (1968) has only 34 species 

and varieties included in nine genera. The Kilgore 

assemblage is intermediate both in age and in number of taxa with respect to these described assemblages. Perhaps this suggests a trend toward increasing complexity in progressively younger nonmarine 

assemblages.

The Kilgore diatom assemblage is significant in 

that it contains five extinct species. The total number of forms represented in the assemblage is also 

significant. A substantial number of the modern 

genera are present, but this Miocene assemblage 

does not have the richness of variation found in 

most Pleistocene and modern assemblages. The 

absence of certain genera and species in the Kilgore 

deposit may be the result of ecology, but the lack 

of whole families and subfamilies can hardly be 

explained on this basis alone. The modern ecology of 

those forms still living suggests that these missing 

categories could have lived in the Kilgore environment had they been in existence at that time. The 

changes in nonmarine diatom assemblages from the 

late Miocene to the present are perhaps more the 

result of the development of new species than of the 

extinction of old species.

PALEOECOLOGIC INTERPRETATION

The modern ecology of the 40 long-ranging taxa in 

the Kilgore diatom assemblage furnishes clues about 

the paleoecology of the deposit. The relative abundance of planktonic forms indicates deposition in 

standing water, probably in a shallow lake. The 

abundance and variety of benthonic diatoms confirm 

deposition in a comparatively shallow lacustrine environment with relatively clear water. MacGinitie 

(1962, p. 76) states that the lake sediments are 

exposed for a distance of about 1% miles, which 

gives an order of geographic magnitude for the lake. 

The lake probably filled slowly with sediments as 

long as it existed and provided an increasingly shallow environment with time. The total thickness of 

the diatomaceous and intercalated sediments at the 

fossil-plant locality is about 8 feet, and the initial 

depth of water was probably not much greater.

Many of the taxa in the Kilgore assemblage are 

common and widespread in modern temperate freshwater environments and thus do not indicate specific 

information about the depositional temperature and 

salinity. Four of the taxa show an affinity for cool or 

cold water. It is probably of greater significance that 

six taxa are tolerant of moderate alkalinity, whereas 

nine taxa are said to tolerate some salinity or water 

of high mineral content. In contrast only three taxa 

are known to prefer waters of low mineral content, 

and only one favors an acid environment. This indicates that the climate was temperate to cool and 

that the water had a fairly high mineral content and 

perhaps was a bit saline. The lack of carbonate in 

the rocks may indicate either that concentrations 

were never great enough for carbonate deposition or 

that the beds were subsequently leached of carbonates. Certainly some postdepositional leaching has 

taken place at the fossil-plant locality. The plantbearing bed itself is a hard siliceous shale, and the 

immediately overlying sediment is relatively impoverished in diatoms. Some diatom silica was leached 

to silicify the fossil-plant bed, but the process was 

only partial. The siliceous shale of unit 4 is also 

probably the result of postdepositional leaching and 

redeposition of silica.

The different beds in the stratigraphic section at 

the fossil-plant locality (USGS diatom localities 

5833-37) show some differences in diatom assemblages which may have significance. Localities 5833- 

35 show great similarity as indeed they should, for 

they come from adjacent beds. These beds are dominated by species of the pelagic genus Melosira. 

Localities 5836 and 5837 seem to show similarities
A8 CONTRIBUTIONS TO PALEONTOLOGY

even though they come from beds separated by a 

nondiatomaceous sandy silt bed. These assemblages 

are characterized by a lack of Melosira granulata 

and an increased abundance of Melosira italica and 

Cymbella cistula. The overall assemblages of these 

younger beds are suggestive of somewhat shallower 

water than the assemblages from localities 5833-35. 

A possible correlation of the assemblage from USGS 

diatom locality 5419 with that from the fossil-plant 

locality (about a mile distant) merits consideration. 

In general the isolated locality seems to show greater 

affinity to the lower assemblages (localities 5833-35) 

than to the upper assemblages (localities 5836 and 

5837). The rather rich assemblage of locality 5419 

seems to be closest to that of locality 5835 at the 

fossil-plant site, though the evidence is not conclusive enough to make a positive correlation.

In summary, the Kilgore diatom assemblage was 

deposited in a shallow lake with dimensions not 

greater than 1 or 2 miles. The climate was temperate 

or cool temperate, and rainfall was sufficient to maintain the lake. The waters of the lake were hard and 

perhaps slightly alkaline and saline, especially during 

dry seasons. The lake grew progressively shallower 

because of filling with sediments. It eventually disappeared, and the deposits were buried by sandy 

sediments typical of the Valentine Formation.

SYSTEMATIC DESCRIPTIONS

The classification in this report is that used by 

Lohman and Andrews (1968) and is based on a proposed classification by K. E. Lohman (unpub. data). 

It follows Moore (1954) to the rank of class and is 

modified from previous classifications proposed by 

Schutt (1896), Karsten (1928), and Hendey (1937). 

The treatment of nomenclature at the generic, specific, and varietal level has been conservative, and the 

standard nomenclature has been preserved except in 

instances of obvious error. This does not imply a 

wholehearted endorsement of previous taxonomic 

work, but merely an attempt to avoid further confusion. New taxa have been described as species, as 

it is felt that the creation of new infraspecific taxa 

among the diatoms should be discouraged except 

under most unusual circumstances. An illustration of 

the absurdity of some varietal names derived from 

modern diatom assemblages may be in order here. 

This late Miocene assemblage contains a form identified as Gom,phonema affine var. insignis, a taxon 

described as a variety from living diatom assemblages. Although the type G. affine may have existed 

somewhere in late Miocene time, it need not have.

Hence we have a Miocene variety of a species for 

which no Miocene type existed. Such absurd situations are avoided by the use of a strictly binomial 

system of nomenclature.

The descriptions herein recorded are for the specimens observed in the Kilgore deposit and do not 

necessarily reflect the total variation of each taxon. 

Except for the new species, they are brief and cover 

only salient features. For more complete descriptions 

the general works cited in the synonymies should be 

consulted. In the synonymies the first citation is that 

of the original author of the taxon; second, references to the genus and species as accepted in this 

paper are given in chronologic order; third, synonyms and misidentifications are given in chronologic 

order. The most common errors, those of incorrect 

attributions of authorship, have been placed in the 

third category. References that have not been examined by the writer are marked by an asterisk. The 

brief comments on the ecology of modern diatom 

taxa are adapted from Patrick and Reimer (1966), 

Hustedt (1927-30, 1931-59, 1961-66), and Hustedt 

(1930). The known geologic ranges of the species 

and varieties are based on the results of this study, 

and some will undoubtedly be extended when older 

diatom assemblages are investigated.

Kingdom PROTISTA Haeckel, 1866

Subkingdom PROTOCTISTA Hogg, 1860

Division CHRYSOPHTYA Pascher, 1914

Class DIATOMOPHYCEAE Rabenhorst, 1864

Order CENTRALES Schutt, 1896

Suborder DISC INEAE Kiitzing, 1844

Family COSCINODISCACEAE Kiitzing, 1844

Subfamily MELOSIROIDEAE Kiitzingr, 1844

Genus MELOSIRA Agardh, 1824

Melosira granulata (Ehrenbergr) Ralfs

Plate 1, figures 1, 2

Gallionella granulata Ehrenberg, 1843, Kgl. preuss. Akad.

Wiss. Berlin, Phys. Abh., 1841, p. 415. 

Melosira granulata (Ehrenberg) Ralfs, in Pritchard, 1861,

History of Infusoria, p. 820. 

Hustedt, 1927, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, pt. 1, p. 248-252, fig. 104. 

Orthosira punctata W. Smith, 1856, Synopsis of the British

Diatomaceae, v. 2, p. 62, pi. 53, fig. 339. 

Meloseira granulata (Ehrenberg) Ralfs. Boyer, 1927, Acad.

Nat. Sci. Philadelphia Proc., v. 78, supp., p. 30.

Description. Valves cylindrical, bound in chains 

of frustules; diameter about 15^, length of valve 

about 9/A-15/A, with valve orientation in a strewn 

mount more commonly the girdle view; puncta 

coarse, arranged in longitudinal rows, about 11 rows 

in IO/A; puncta about eight to 10 in 10^; valve ends 

denticulate.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A9

Remarks. This species is common in USGS diatom localities 5419 and 5833, and it is abundant in 

localities 5834 and 5835.

Living representatives of this plantonic species 

are common in eutrophic lakes, ponds, and streams 

and often occur in great abundance.

Known geologic range. Late Miocene to present.

Melosira granulata var. angustissima Miiller

Plate 1, figure 3

Melosira granulata var. angustissima Muller, 1899, Hedwigia,

v. 38, p. 315, pi. 12, fig. 28.

Hustedt, 1927, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, pt. 1, p. 250-251, fig. 104d.

Description. Valve cylindrical, similar to the 

type, except that the length :width ratio is much 

greater; diameter commonly 4^-5^, length often 

greater than 20/x.

Remarks. The variety occurs in the same relative 

abundance as the type, common in localities 5419 

and 5833, and is abundant in localities 5834 and 

5835.

The modern ecology of the variety is similar to 

that of the type.

Known geologic range. Late Miocene to present.

Melosira italica (Ehrenberg) Kiitzing

Plate 1, figure 4

Gaillonella italica Ehrenberg, 1836, Kgl. preuss. Akad. Wiss.

Berlin, Ber., 1836, p. 53. 

Melosira italica (Ehrenberg) Kiitzing, 1844, Die kieselschaligen Bacillarien oder Ditaomeen, p. 55, pi. 2, fig. 6. 

Hustedt, 1927, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, pt. 1, p. 257-262, fig. 109. 

Lohman and Andrews, 1968, U.S. Geol. Survey Prof.

Paper 593-E, p. E12, pi. 1, fig. 6. 

Gallionella crenulata Ehrenberg, 1843, Kgl. preuss. Akad.

Wiss. Berlin, Phys. Abh., 1841, p. 376, pi. 2, fig. I, 41;

pi. 3, fig. I, 28; pi. 4, fig. I, 31. 

Melosira crenulata (Ehrenberg) Kiitzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 55, pi. 2, fig. 8. 

Meloseira crenulata (Ehrenberg) Kiitzing. Boyer, 1927, Acad.

Nat. Sci. Philadelphia Proc., v. 78, supp., p. 29.

Description. Valves cylindrical, bound in chains 

of frustules, often but not always greater in height 

than in diameter; margin denticulate; mantle finely 

punctate, about 14 in lO/x, arranged in longitudinal 

or slightly spiral rows, about 16 in lO/x. Diameter 

about lO/x-20/x, height about lO/x-20/x; length:width 

ratio widely variable, but most specimens are seen 

in girdle view.

Remarks. The rows of puncta on the Kilgore 

specimens tend to be more longitudinal and less spiral

than in some modern forms. Along with M. italica 

there occurs a very thin walled finely punctate variety, usually seen as a single valve or attached pair in 

girdle view. These thin-walled valves are nearly 

always slightly crushed on the open ends, and this 

gives the appearance of a slightly flattened truncated 

conical valve. This apparent change from a cylindrical to a truncated conical outline appears to be a 

mechanical deformation and without significance in 

differentiating the thin-walled form from M. italica.

The species is common in USGS diatom localities 

5834 and 5835 and abundant in localities 5419, 5836, 

and 5837.

M. italica is a cosmopolitan species and lives today 

in temperate fresh-water environments throughout 

the world as a pelagic form in lakes and as a littoral 

form in smaller bodies of water.

Known geologic range. Late Eocene to present.

Melosira distans (Ehrenberg) Kiitzing

Plate 1, figure 5

Gaillonella distans Ehrenberg, 1836, Kgl. preuss. Akad. Wiss. 

Berlin, Ber., 1836, p. 83-84.

Melosira distans (Ehrenberg) Kiitzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 54, pi. 2, fig. 12.

Hustedt, 1927, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, pt. 1, p. 262-266, fig. 110-111.

Meloseira distans (Ehrenberg) Kiitzing. Boyer, 1927, Acad. 

Nat. Sci. Philadelphia Proc., v. 78, supp., p. 30.

Description. Valve of relatively low height compared to diameter, recognized only in valve view in 

strewn mounts of the Kilgore deposit; ends of valve 

convex, punctate, with no discernable lineation or 

orderly arrangement of the coarse puncta. Diameter, 

about ISfji.

Remarks. This species is common in USGS diatom locality 5419 and rare in localities 5833 and 

5835.

Living representatives of the species are littoral 

forms and show a preference for cool fresh-water 

environments.

Known geologic range. Late Miocene to present.

Order PENNALES Schiitt, 1896

Suborder ARAPHIDINEAE Karsten, 1928

Family FRAGILARIACEAE Kiitzing, 1844

Subfamily TABELLARIOIDEAE, Kiitzing, 1844

Genus TETRACYCLUS Ralfs, 1843

Tetracyclus lacustris Ralfs

Plate 1, figures 6, 7

Tetracyclus lacustris Ralfs, 1843, Annals and Mag. Nat. History, v. 12, p. 105, pi. 2, fig. 2.

Hustedt, 1931, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, pt. 2, p. 12-15, fig. 545a-d.
A10 CONTRIBUTIONS TO PALEONTOLOGY

Description. Valve elongate with a moderate 

transverse swelling at center; apices rounded and 

on some specimens subcuneate; pseudoraphe very 

narrow but distinct; costae three to four in ID/*, some 

specimens incomplete; striae very fine. Length, 20^- 

34^; width, about IS/*.

Remarks. T. lacustris has frequently been confused with T. pagesi, and the two species have often 

been placed together as a single variable species. 

Although doubtful specimens may occur, in most 

instances the two species can be readily distinguished. Patrick and Reimer (1966, p. 102, pi. 1, fig. 

9) unfortunately describe as T. lacustris a species 

that seems much closer to T. pagesi, and their illustration is that of a rather extreme form of T. pagesi.

This species occurs frequently in USGS diatom 

locality 5835; it is rare in localities 5419, 5833, and 

5834.

Living representatives of the species prefer cool 

standing waters.

Known geologic range. Late Miocene to present. 

Tetracyclus pagesi Heribaud 

Plate 1, figures 8, 9

Tetracyclus pagesi Heribaud, 1902, Les diatomees fossiles

d'Auvergne, p. 17, pi. 8, fig. 10. 

Tetracyclus lacustris var. capitata Hustedt, in Schmidt, 1911,

Atlas der Diatomaceenkunde, pi. 269, fig. 6. 

Hustedt, 1931, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 14, fig. 545e.

Description. Valve elongate with highly variable 

degree of transverse swelling at the center; apices 

rounded and on some specimens slightly subcuneate; 

ends always distinctly capitate or subcapitate; pseudoraphe very narrow but distinct; costae three to 

four in 10^, prominent; striae very fine. Length, 

33^-43^; width, about 15^-18^.

Remarks. T. pagesi is distinguished from T. 

lacustris by its generally larger size and its distinctive capitate or subcapitate ends. Some specimens 

show a much more greatly expanded central swelling 

than T. lacustris, but this characteristic is not consistent enough to be in itself definitive. Some specimens of T. pagesi may appear similar to T. lacustris, 

but the shape of the ends, if not the central swelling, 

is sufficient to distinguish the two species.

The species occurs frequently in USGS diatom 

locality 5419, and is rare in localities 5834-36.

Living representatives of the species are apparently similar in ecology to T. lacustris.

Known geologic range. Late Miocene to present,

described by Heribaud from the upper Pliocene of 

France.

Tetracyclus tripartitus Brun and Heribaud

Plate 1, figures 10, 11

Tetracyclus tripartitus Brun and Heribaud, in Heribaud,

1893, Les diatomees d'Auvergne, p. 223, pi. 6, fig. 5. 

Tetracyclus tripartitus var. gracilis Peragallo and Heribaud

in Heribaud, 1902, Les diatomees d'Auvergne, p. 39,

pi. 8, fig. 11. 

Tetracyclus lacustris var. elongata Hustedt in Schmidt, 1911,

Atlas der Diatomaceenkunde, pi. 269, figs. 7, 8. 

Hustedt, 1931, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 14, fig. 545h.

Description. Valve elongate, faintly to distinctly 

triundulate, with central swelling slightly exceeding 

the terminal swellings in width; apices rounded and 

on some specimens subcuneate; pseudoraphe very 

narrow but distinct; costse three to four in 10^, prominent ; striae very fine. Length, 55^-64^ ; width, about

Remarks. Although the internal structure of this 

species is similar to T. lacustris and T. pagesi, its 

relatively great size, distinctly triundulate lateral 

margins, and high length :width ratio are diagnostic 

of the species. Peragallo and Heribaud (in Heribaud, 

1902) distinguished a variety gracilis based on 

weakly triundulate specimens. There seems to be complete inter gradation, however, between the type and 

the variety, and the distinction appears to be artificial.

Tetracyclus tripartitus is rare in USGS diatom 

localities 5419 and 5835.

The modern ecology is similar to that of T. 

lacustris.

Known geologic range. Late Miocene to present, 

described by Heribaud (1902) from the upper Pliocene of France.

Tetracyclus rupestris (A. Braun) Granow

Plate 1, figures 12, 13

Gomphogramma rupestre A. Braun, in Eabenhorst, 1853, Die 

Siisswasser-Diatomaceen (Bacillarien) fur Freunde der 

Mikroscopie, p. 33, pi. 9.*

Tetracyclus rupestris (A. Braun) Grunow, in Van Heurck, 

1881, Synopsis des diatomees de Belgique, pi. 52, 

figs. 13, 14.

Hustedt, 1931, Die Kieselalgen Deutschlands, Osterreichs, 

und der Schweiz, pt. 2, p. 15-16, fig. 547.

Description. Valve elliptical, small, with broadly 

rounded apices; pseudoraphe definite but very narrow ; costae four to five in 10^, some rudimentary and 

not reaching the center ; striae very fine. Length, 13^- 

20^; width, 9^-11^.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA All

Remarks. This species may be a small relatively 

unornamented form of T. lacustris. It does not have 

the characteristic shape of T. lacustris, however, and 

seems to conform to the description of T. rupestris. 

It is smaller than T. ellipticus.

This species is rare in USGS diatom localities 

5419, 5833, and 5835.

Living representatives of the species are reported 

from very shallow water and moist surface environments.

Known geologic range. Late Miocene to present.

Tetracyclus cruciformis Andrews, n. sp.

Plate 1, figures 14-17

Diagnosis. Valve cruciform, with four extensions 

or arms of nearly equal length set at right angles. 

Pseudoraphe narrow, in part indistinct, extending to 

the ends of some of the four arms of the valve, but 

indistinct in other arms. Segments of the pseudoraphe 

from the arms join together in an irregular manner 

in the central area. Costae, two to four in 10/u., irregularly spaced, normal or diagonal to the sides of 

the arms, terminating or looping irregularly in the 

central area. Striae 17-27 in 10/u., finely punctate, 

oriented generally parallel to the costae and hence 

somewhat irregularly distributed in the central area. 

Length and width equal and indistinguishable from 

each other in the structure of the valve, ranging from 

41/A to 45/u, in the specimens examined.

Holotype. USGS diatom catalog 3626-4 (pi. 1, 

fig. 14), length and width, 45/u..

Paratypes. USGS diatom catalog 3626-41 (pi. 1, 

fig. 15), length and width, 43/u.. USGS diatom catalog 

3626-20 (pi. 1, fig. 16), length and width, 39^. USGS 

diatom catalog 3626-31, (pi. 1, fig. 17), length and 

width, 4V All from USGS diatom locality 5836.

Remarks. This species of Tetracyclus is highly 

distinctive in that it involves the modification of a 

form closely related to T. lacustris into a species with 

four arms, each usually showing a pseudoraphe. This 

involves a basic change in structure from the normally pennate species of the genus Tetracyclus to a 

pseudocentric form. Because of the obvious affinities 

for T. lacustris, however, there seems to be no justification for creating a new genus to accommodate this 

form, but it can be recognized as a distinctive species 

of Tetracyclus. This species should be an excellent 

marker fossil if it proves to be of widespread distribution.

A similar or perhaps identical species has been reported from the Miocene of the Lake Baikal region 

of the U.S.S.R. by Cheremisinova (1968). Although 

she has named and figured her species as Tetracyclus

fioriformis sp. nov., no formal diagnosis or description has been made as far as the writer is aware. This 

name, unless validly published with a description or 

diagnosis, has no standing under the present rules of 

nomenclature.

Occurs frequently in USGS diatom locality 5836, 

also reported from the Miocene of the U.S.S.R.

Known geologic range. Late Miocene.

Subfamily FRAGILARIOIDEAE Kiitzing, 1844 

Genus FRAGILARIA Lyngbye, 1819

Fragilaria brevistriata Grunow

Plate 1, figures 18, 19

Fragilaria brevistriata Grunow, in Van Heurck, 1885, Synopsis des diatomees de Belgique, p. 157.

Hustedt, 1931, Die Kieselalgen Deutschlands, Osterreichs, 

und der Schweiz, pt. 2, p. 168-170, fig. 676a-e.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 128-129, pi. 4, fig. 14.

Description. Valve linear-lanceolate with subrostrate apices; striae about 16 in 10/u., short, marginal 

to a central hyaline area. Length as much as 48/x; 

width about 6/u..

Remarks. This species is more often seen in 

girdle view as chains of f rustules than in valve view. 

Specimens from Kilgore have striae of moderate 

length, and they more closely resemble the species as 

illustrated by Patrick and Reimer (1966) than as 

illustrated by Hustedt (1931). The hyaline central 

area suggests that the Kilgore forms are closer to 

the modern F. brevistriata than to F. virescens.

The species is abundant in USGS diatom localities 

5419 and 5836; it is rare in localities 5833 and 5835.

Living representatives of the species are tolerant 

of a wide range of fresh-water environments.

Known geologic range. Late Miocene to present.

Fragilaria gigantea Lauby

Plate 1, figures 20, 21

Fragilaria gigantea Lauby, 1910, France Service Carte Geol. 

Bull. 125, v. 20, p. 214, pi. 9, fig. 17.

Description. Valve large, robust, elongate with 

rounded subcapitate apices; margins nearly straight, 

but with a slight tendency to be triundulate in some 

specimens; pseudoraphe very faint to nonexistent; 

transverse striae about 11 in 10/u., parallel, coarse, 

strongly beaded, on some specimens continuous across 

the center of valve where the pseudoraphe should be 

located, and on some slightly separated by the 

pseudoraphe or discontinuous on opposite sides of a 

tenuous pseudoraphe; length, 60/u.-100/u,; width, 9//,-
A12 CONTRIBUTIONS TO PALEONTOLOGY

Remarks. This species in the Kilgore deposit 

appears to be identical with Lauby's species from the 

Massif Central in France. The only difference, probably not significant, is that the Kilgore specimens 

have about 11 striae in lOju,, whereas Lauby indicated 

that his specimens had 15 striae in lOju. F. gigantea is 

a distinctive species, generally larger and more robust 

than most Fragilarias, but showing only vestiges of 

a pseudoraphe. It should be an excellent marker 

fossil.

Lauby (1910, p. 125, 331) reported this species 

from one locality, the Route du Mont-Dore a Besse 

in the Department of Puy-de-D6me, France. Although he indicates that the deposit is Plaisancian 

(early Pliocene) in age, this stage is now considered 

to be of middle Pliocene age (Wood and others, 

1941). F. gigantea occurs frequently in USGS diatom 

locality 5419, rare in localities 5834 and 5835.

Known geologic range. late Miocene to middle 

Pliocene.

Genus SYNEDRA Ehrenberg, 1830 

Synedra rumpens Kiitzing

Plate 1, figure 22

Synedra rumpens Kiitzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 69, pi. 16, fig. 6.

Hustedt, 1932, Die Kieselalgen Deutschlands, Osterreichs, 

und der Schweiz, pt. 2, p. 207-208, fig. 697.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 143, pi. 5, fig. 19.

Description. Valve linear, tapering to small subcapitate apices; pseudoraphe narrow; central area 

extends to lateral margins and is longer than it is 

wide; valve margins show a suggestion of swelling 

along central area; striae about 13 in lOju. Length 

about 35ju; width about 4p.

Remarks. The species is rare in USGS diatom 

locality 5835.

Living representatives of the species are widely 

distributed in standing or slow-flowing fresh waters.

Known geologic range. Late Miocene to present.

Synedra ulna (Nitzsch) Ehrenberg

Plate 1, figure 23

Bacillaria ulna Nitzsch, 1817, Naturf. Gesell. Halle, Neue 

Schr. v. 3, no. 1, p. 99-104, pi. 5.

Synedra ulna (Nitzsch) Ehrenberg, 1836, Kgl. preuss. Akad.

Wiss. Berlin, Ber. 1836, p. 53. 

Hustedt, 1932, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 195-201, fig. 691A, a-c. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 148-149, pi. 7, figs. 1, 2.

Description. Valve linear, very gradually tapering to small subrostrate apices; pseudoraphe very 

narrow; hyaline central area formed by lack of marginal striae; striae about 10 in ID/*, parallel. Length 

as much as 216ju,; width about 4ju.

Remarks. This species is frequent as fragments 

in USGS diatom localities 5419, 5834, and 5835, and 

it is rare in locality 5837.

Living representatives of the species are common 

and widely distributed in fresh-water environments.

Known geologic range. Late Miocene to present.

Suborder BAPHIDIOIDINAE Karsten, 1928

Family EUNOTIACEAE Kiitzing, 1844

Genus EUNOTIA Ehrenberg, 1837

Eunotia parallela Ehrenberg

Plate 1, figure 24

Eunotia parallela Ehrenberg, 1843, Kgl. preuss. Akad. Wiss.

Berlin, Phys. Abh., 1841, p. 414. 

Hustedt, 1932, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 302, fig. 768. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 193, pi. 10, fig. 12.

Description. Valve with parallel dorsal and ventral margins; slightly concave ventral margin and 

slightly convex dorsal margin, flexed a little in opposite direction near the rounded apices; striae about 

12 in lOju,, somewhat irregular in spacing, parallel. 

Length, 45ju-87ju,; width, about 6ju-l(V.

Remarks. The species is frequent in USGS diatom 

locality 5419 and rare in localities 5834 and 5835.

Living representatives of the species are more common in cool or cold fresh waters.

Known geologic range. Late Miocene to present.

Eunotia pectinalis var. minor (Kiitzing) Babenhorst

Plate 1, figure 25

Himatidium minus Kiitzing, 1844, Die kieselschaligan Bacillarien oder Diatomeen, p. 39, pi. 16, fig. 10. 

Eunotia pectinalis var. minor (Kiitzing) Rabenhorst, 1864.

Flora Europaea Algarum, sect. 1, p. 74. 

Hustedt, 1932, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 298, fig. 763d-f. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 207, pi. 12, figs. 12, 13.

Description. Ventral margin slightly concave, 

dorsal margin somewhat more convex; dorsal margin 

somewhat pinched in, which narrows the valve near 

the rounded apices; striae about 14 in 10/i, parallel, 

irregularly spaced. Length, 24^-38^; width, about 7j*.

Remarks. The species occurs frequently in USGS 

diatom locality 5419 and is rare in localities 5835 and 

5836.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A13

Living representatives of the species occur in acid 

to circumneutral water, but it will tolerate some calcium carbonate.

Known geologic range. Late Miocene to present.

Suborder MONOBAPHIDINEAE Karsten, 1928

Family ACHNANTHACEAE Kiitzing, 1844

Subfamily ACHNANTHOIDEAE Schtitt, 1896

Genus ACHNANTHES Bory, 1822

Achnanthes hungarica (Grunow) Grunow

Plate 1, figures 26, 27

Achnanthidium hungaricum Grunow, 1863, Kaiserl.-kgl. zool.- 

bot. Gesell. Wien Verb., v. 13, p. 146, pi. 4, fig. 8a-c.

Achnanthes hungarica (Grunow) Grunow, in Cleve and

Grunow, 1880, Kgl. svenska vetensk. akad. Handl., v.

17, no. 2, p. 20. 

Hustedt, 1933, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 383-384, fig. 829. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 259, pi. 16, figs. 27, 28.

Description. Valves elliptical with subcuneate 

apices; raphe valve with narrow linear axial area 

widening abruptly at the central area to form a 

hyaline stauros extending to the margins of the 

valve; raphe fine, terminating in rather prominent 

central pores and distal ends flexed in opposite directions near the apices of the valve; striae faint, slightly 

radiate. Pseudoraphe valve with narrow pseudoraphe, 

only slightly expanded at central area; striae slightly 

radiate, somewhat more pronounced than on raphe 

valve; strise about 18 in 10/x on both valves. Length, 

about 20/x; width, about 8/t.

Remarks. The species as observed in the Kilgore 

deposit is somewhat more elliptical than specimens 

figured by Patrick and Reimer (1966) and more 

closely resembles the figures of Hustedt (1933).

Achnanthes hungarica is rare in USGS diatom 

locality 5835.

Living representatives of the species are rare and 

occur in fresh, alkaline, or slightly saline lakes or 

ponds.

Known geologic range. Late Miocene to present.

Suborder BIBAPHIDINEAE Karsten, 1928

Family NAVICULACEAE Kutzing, 1844 

Subfamily NAVICULOIDEAE Kiitzing, 1844

Genus STAURONEIS Ehrenberg, 1843

Stauroneis phoenicenteron (Nitzsch) Ehrenberg

Plate 2, figure 1

Bacillaria phoenicenteron Nitzsch, 1817, Naturf. Gesell. Halle, 

Neue Schr. v. 3, no. 1, p. 92-97, pi. 4, figs. 12, 14.

Stauroneis phoenicenteron (Nitzsch) Ehrenberg, 1843, Kgl. 

preuss. Akad. Wiss. Berlin, Phys. Abh., 1841, p. 387, 

pi. 2, fig. V; pi. 3, fig. I, 17.

Hustedt, 1959, Die Kieselalgen Deutschlands, Osterreichs, 

und der Schweiz, pt. 2, p. 766-770, fig. 1118a.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 359, pi. 29, figs. 1, 2.

Description. Valve lanceolate with rounded somewhat protracted apices; striae 14-16 in 10/x, radiate, 

sharply punctate; puncta irregularly placed on the 

strise, which terminate with a somewhat ragged margin along the axial area; stauros slightly expanding 

because of the radiating striae. Length, 75/^-117/x; 

width, 17ju-22/x.

Remarks. The Kilgore specimens are distinctly 

convex on the lateral margins, and resemble S. 

phoenicenteron f. gracilis as figured by Patrick and 

Reimer (1966, pi. 29, figs. 3, 4). However, the 

coarser striation of the Kilgore forms place them 

within the limits of S. phoenicenteron. The only 

criterion for the differentiation of f. gracilis from the 

type seems to be arbitrary, with specimens having 

more than 17 striae in 1(V being referred to f. gracilis.

Occurs frequently in USGS diatom localities 5419 

and 5835.

Living representatives of this species have a broad 

pH tolerance and are common and widespread in 

many fresh-water environments.

Known geologic range. Late Miocene to present.

Stauroneis anceps Ehrenberg

Plate 2, figure 2

Stauroneis anceps Ehrenberg, 1843, Kgl. preuss. Akad. Wiss.

Berlin, Phys. Abh., 1841, p. 422, pi. 2, fig. I, 18. 

Hustedt, 1959, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 771-775, fig. la. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 361, pi. 30, fig. 1.

Description. Valve elliptical-lanceolate with protracted subrostrate apices. Axial area narrow, linear, 

widening in the central area to the margins as a 

parallel-sided stauros. Striae slightly radiate, about 

22 in 1(V, finely but distinctly punctate. Length, 38/x42ju,; width, about 9/x.

Remarks. This species shows an obvious relationship to S. phoenicenteron, but it is generally smaller 

and more finely striated.

The species occurs frequently in USGS diatom 

locality 5419.

Living representatives of the species are widespread in fresh-water environments and tolerant of 

a considerable range in pH.

Known geologic range. Late Miocene to present.

Stauroneis smithii Grunow

Plate 2, figure 3

Stauroneis smithii Grunow, 1860, Kaiserl.-kgl. zool.-bot. 

Gesell. Wien Verh., v. 10, p. 564-565, pi. 4, fig. 16.
A14 CONTRIBUTIONS TO PALEONTOLOGY

Hustedt.. 1059, Die Kieselalgen Deutschlands, ftsterreichs, 

und dor Sc-hweiz, pt. 2, p. 810-813, fig. 1157a-c.

Patrick and Keimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 365, pi. 30, fig. 12.

Description. Valve markedly triundulate, terminating in small rostrate-apiculate ends; central undulation wider than terminal undulations; prominent 

pseudoseptum. Axial area linear, widening centrally 

into a parallel-sided stauros; striae very fine, punctate. Length, about 26//,; width about 7//,.

Remarks. Rare in USGS diatom locality 5836.

Living representatives of this species show a 

preference for alkaline waters.

Known geologic range. Late Miocene to present.

Stauroneis lauenburgiana Hustedt

Plate 2, figures 4-6

Stauroneis lauenburgiana Hustedt, 1950, Archiv fiir Hydrobiologie, v. 6, p. 405, pi. 37, fig. 15.

Hustedt, 1959, Die Kieselalgen Deutschlands, Osterreichs, 

und der Schweiz, pt. 2, p. 808-809, fig. 1155a, b.

Description. Valve lanceolate to elongate with 

produced rostrate to subrostrate apices; short pseudoseptum ; axial area varies in width because of irregular length of the striae; central area widened into a 

stauros with nearly parallel sides; striae about 19 in 

10/x, very slightly radiate, formed by irregularly 

spaced puncta; punctation anomoeonoid with puncta 

showing a disorderly longitudinal alinement. Length, 

40/A-48//,; width, about 9//,-10//,.

Remarks. This species occurs frequently in USGS 

diatom locality 5836 and is rare in locality 5837.

Living representatives of the species have been 

reported from both standing and flowing fresh water.

Known geologic range. Late Miocene to present.

Genus ANOMOEONEIS Pfitzer, 1871 

Anomoeoneis sphaerophora (Ehrenberg) Pfitzer

Plate 2, figure 7

Navicula sphaerophora, Ehrenberg, 1843, Kgl. preuss. Akad.

Wiss. Berlin, Phys. Abh., 1841, p. 419, pi. 3, fig. IV, 3. 

Anomoeoneis sphaerophora (Ehrenberg) Pfitzer. Patrick and

Reimer, 1966, Acad. Nat. Sci. Philadelphia Mon. 13,

p. 374-375, pi. 32, fig. 1. 

Anomoeoneis sphaerophora (Kiitzing) Pfitzer, 1871, Untersuchungen uber Bau und Entwicklung der Bacillariaceen (Diatomaceen), p. 77-78, pi. 3, fig. 10. 

Hustedt, 1959, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 2, p. 740-744, fig. 1108a.

Description. Valve elliptical-lanceolate with extended rostrate apices; axial area narrow, linear,

broadening into a transversely elliptical, asymmetric 

central area; striae about 18 in 10/*, slightly radiate; 

composed of irregularly spaced puncta, partly oriented in irregular longitudinal rows. Length about 

42/x; width about 14//,.

Remarks. This species, as it occurs in the Kilgore 

deposit, has some features differing from living 

forms. Although the central area tends to be asymmetrical, the areas between the raphe and the lateral 

margins tend to be filled with normal puncta and not 

hyaline as in modern specimens. These hyaline areas 

in modern specimens often show vestiges of puncta 

that no longer exist in those areas. The Kilgore forms, 

therefore, may be more primitive forms of A. sphaerophora in which the lateral puncta are fully developed.

This species is rare in USGS diatom locality 5836.

Modern representatives of this fresh-water species 

show some preference for alkaline water and are 

tolerant of some salt concentration.

Known geologic range. Late Miocene to present.

Genus NEIDIUM Pfitzer, 1871 

Neidium iridis var. ampliata (Ehrenberg) Cleve

Plate 2, figure 8

Navicula ampliata Ehrenberg, 1854, Mikrogeologie, pi. 15A, 

figs. 32, 35?

Neidium iridis var. ampliata (Ehrenberg) Cleve, 1894, Kgl.

svenska vetensk. akad. Handl., v. 26, no. 2, p. 69. 

Hustedt in Pascher, 1930, Die SUsswasser-flora Mitteleuropas, no. 10, p. 245, fig. 381.

Neidium iridis var. ampliatum (Ehrenberg) Cleve. Patrick 

and Reimer, 1966, Acad. Nat. Sci. Philadelphia Mon. 

13, p. 388, pi. 34, fig. 5.

Description. Valve linear-elliptical with broad 

subrostrate apices; axial area narrow, widening 

abruptly to form a small rounded central area; striae 

about 17 in 10//,, slightly oblique, sharply punctate. 

Length, about 79//,-86//,; width, about 22/*.

Remarks. This species occurs frequently in USGS 

diatom locality 5836.

Living representatives of this species are more common in standing than in flowing water, and they are 

tolerant of a wide range in pH.

Known geologic range. Late Miocene to present.

Genus NAVICULA Bory, 1822 

Navicula amphibola Cleve

Plate 2, figure 9

Navicula amphibola Cleve, 1891, Soc. pro Fauna et Flora 

Fennica, Acta, v. 8, no. 2, p. 33.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A15

Cleve, 1895, Kgl. svenska vetensk. akad. Handl., v. 27,

no. 3, p. 45. 

Hustedt, 1966, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 3, p. 792-795, fig. 1767. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 445, pi. 39, figs. 7, 8.

Description. Valve elliptical-lanceolate with 

sharply rostrate, rounded apices; axial area narrow, 

widening abruptly to form a transverse central area 

by the irregular shortening of the adjacent striae; 

striae about seven to eight in 10/x, radiate, slightly 

irregular, widely spaced, and ornamented with distinct puncta. Length, 33/X-62/X ; width, about 15/x-20/x.

Remarks. This species is common in USGS diatom locality 5836, frequent in localities 5419 and 

5834, and rare in localities 5835 and 5837.

Living representatives of the species are common 

in circumneutral waters.

Known geologic range. Late Miocene to present.

Navicula niobrara Andrews, n. sp.

Plate 2, figures 10, 11

Diagnosis. Valve lanceolate with subrostrate 

rounded apices; axial area about 1/5-1/6 the width 

of the valve, tapering toward the apices, but nearly 

constant in width approaching the central area, 

which is distinctly rounded ; diameter about one-third 

the width of the valve ; margins of the axial and central areas slightly ragged because of the uneven 

length of adjacent striae; raphe straight, inclined to 

the plane of the valves, terminating in pores slightly 

deflected toward one side of the central area; striae 

six to nine in 10/x, irregular in length and spacing, 

distinctly separated, divergent; puncta fine but distinct, about 15-16 in 10/x. Length, 102^-120/x; width,

Holotype. USGS diatom catalog 3626-29 (pi. 2, 

fig. 10) ; length, 104/.; width, 39/x.

Paratype. USGS diatom catalog 3626-33 (pi. 2, 

fig. 11) ; length, IHV; width, 37/x. Both from USGS 

diatom locality 5836.

Remarks. This species is similar in size and general outline to N. maculata ( J. W. Bailey) Cleve, but 

differs considerably in ornamentation. These differences from N. maculata include: a wider axial area 

and rounder central area, much finer punctation and 

consequent wider spacing of the striae, lateral deflection of the central pores. N. niobrara may be included 

in the subgeneric group termed Naviculae punctatae

by Cleve (1895, p. 37). The species has a large but 

thin valve, and it is more commonly found in the Kilgore deposit as fragments than as whole specimens. 

Because of its large size and distinctive punctation, 

N. niobrara should be an excellent marker fossil.

Occurs frequently in USGS diatom locality 5419 

and is common in localities 5836 and 5837.

Known geologic range. uate Miocene.

Navicula actinota Andrews, n. sp

Plate 2, figures 12, 13

Diagnosis. Valve elliptical-lanceolate with rostrate to subapiculate apices; axial area about onesixth or one-seventh the width of the valve, narrowing toward the apices and widening to a transversely 

elliptical central area. Raphe filamentous, terminating in prominent pores at the central area; striae 

eight to nine in 10/*, distinctly separated, divergent 

throughout the length of the valve; puncta eight to 

12 in 10/t, dotlike near the axial area, but elongating 

to become rodlike or raylike parallel to the striae 

nearer the margins of the valve; raylike puncta appear to have sharp, rectangular corners. Length, 

Sl/t-57/i; width, 22/,-24/x.

Holotype. USGS diatom catalog 3626-11 (pi. 2, 

fig. 12); length, 51/tj width, 22/t.

Paratype. USGS diatom catalog 3626-34 (pi. 2, 

fig. 13) ; length, 57,.; width, 2V

Remarks. N. actinota falls within Cleve's subgeneric group Naviculae punctatae, and it is generally 

similar in external shape to several species within 

that group. The most distinctive characteristic of this 

species is the peculiar shape of the rectangular raylike puncta. These puncta are elongated in the direction of the striae, and their sharply angular corners 

are striking. Because of its highly distinctive punctation, N. actinota should be a useful marker fossil.

Rare in USGS diatom locality 5836.

Known geologic range. Late Miocene.

Navicula cuspidata (Kiitzing) Kiitzing

Frustulia cuspidata Kiitzing, 1833, Linnaea, v. 8, p. 549, pi. 

14, fig. 26.

Navicula cuspidata (Kiitzing) Kiitzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 94, pi. 3, figs. 24, 37. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 464, pi. 43, figs. 9, 10.

Navicula cuspidata forma genuina Hustedt, 1961, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, 

pt. 3, p. 59-64, fig. 1206a.

Description. Valve lanceolate with small attenu-
A16 CONTRIBUTIONS TO PALEONTOLOGY

ated rounded apices; axial area narrow, expanding 

only slightly at central area; striae fine, 13 or more 

in 10/x, parallel; longitudinal rows of puncta can be 

seen only at high magnification.

Remarks. The valves of this species are very thin 

and fragile and only broken specimens were observed. 

The differences between N. cuspidata and N. halophila as described in the literature are not striking, 

and the Kilgore specimens could possibly be assigned 

to N. halophila. The coarseness of the striae has, however, suggested that they be placed in N. cuspidata.

This species is rare in USGS diatom localities 5836 

and 5837.

Living representatives of the species are widespread in many fresh-water environments.

Known geologic range. Late Miocene to present.

Navicula bacillum Ehrenberg

Plate 2, figure 14

Navicula bacillum Ehrenberg, 1843, Kgl. preuss. Akad. Wiss.

Berlin, Phys. Abh., 1841, p. 418, pi. 4, fig. V, 8. 

Hustedt, 1961, Die Kieselalgen Deutschlands, Osterreichs,

und der Schweiz, pt. 3, p. 113-115, fig. 1248a-d. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 494-495, pi. 47, figs. 4, 5.

Description. Valve linear, with rounded apices; 

axial area narrow, widening into a longitudinally 

elliptical central area; striae about 18 in 10/x at the 

center, finer near the apices; striae radiate and 

curved, convex toward the apices. Length, 28/i-47/u,; 

width, about 7/x-10/x.

Remarks. The species occurs frequently in USGS 

diatom locality 5419 and is rare in localities 5834, 

5836, and 5837.

Living representatives of the species are found in 

fresh to slightly saline waters and are tolerant of 

alkalinity.

Known geologic range. Late Miocene to present.

Navicula radiosa Kiitzing

Plate 2, figure 15

Navicula radiosa Kiitzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 91, pi. 4, fig. 23.

Hustedt, in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 299, fig. 513.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 509, pi. 48, fig. 15.

Description. Valve lanceolate with sharply 

rounded apices; axial area narrow, widening slightly 

to form a rather ill-defined central area; striae about 

13 in 10/x, intensely radiate at the center, but becoming slightly convergent near the apices; center striae

shortened to accommodate the great divergence of the 

striae near the center of the valve. Length about 38/A; 

width about 8/x.

Remarks. This species is rare in USGS diatom 

locality 5835.

Living representatives of the species are common 

in circumneutral fresh water and are tolerant of some 

salinity.

Known geologic range. Late Miocene to present.

Navicula graciloides A. Mayer

Plate 2, figure 16

Navicula graciloides A. Mayer, 1919, Kryptogamische Forschungen, Bayerische botanische Gesellschaft, Miinchen, v. 1, no. 4, p. 203, 212, pi. 7, fig. 60* 

Hustedt in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 299, fig. 515.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 516, pi. 49, figs. 9, 10.

Description. Valve linear to lanceolate with 

rounded slightly subrostrate apices; axial area narrow, expanding to a transversely oval central area by 

shortening of the marginal striae; striae about nine 

to 10 in 10/x, strongly radiate, curved. Length about 

41/x-43/x; width, about 10/x-ll/x.

Remarks. This species is rare in USGS diatom 

localities 5419 and 5835.

Living representatives of the species occur in fresh 

to slightly saline circumneutral waters.

Known geologic range. Late Miocene to present.

Navicula anglica var. subsalsa (Grunow) Cleve

Plate 2, figure 17

Navicula tumida var. subsalsa Grunow, 1860, Kaiserl.-kgl. 

zool.-bot. Gesell, Wien Verh., v. 10, p. 537, pi. 2, fig. 

43b, c. 

Navicula anglica var. subsalsa (Grunow) Cleve, 1895, Kgl.

svenska vetensk. akad. Handl., v. 27, no. 3, p. 22. 

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 303.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 520-521, pi. 49, fig. 20.

Description. Valve lanceolate with subrostrate, 

broadly rounded apices. Axial area very narrow, 

widening abruptly to a transversely elliptical central 

area. Striae about 11 in 10/A, radiate, curved convexly 

toward the apices. Length, about 25/x; width, about 

9/x.

Remarks. This species is rare in USGS diatom 

locality 5834.

Living representatives of this species prefer hard 

or slightly saline, circumneutral waters.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A17

Known geologic range. Late Miocene to present.

Navicula elginensis (Gregory) Ralfs

Plate 2, figure 18

Pinnularia elginensis Gregory, 1856, Quart. Jour. Micr. Sci.,

v. 4, p. 9, pi. 1, fig. 33*. 

Navicula elginensis (Gregory) Ralfs, in Pritchard, 1861,

History of Infusoria, p. 902. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 524-525, pi. 5, fig. 3. 

Navicula dicephala (Ehrenberg) W. Smith. Hustedt, in

Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no.

10, p. 302-303, fig. 526.

Description. Valve linear to lanceolate with rostrate to subcapitate apices; axial area narrow, widening at the center to form a rounded central area; 

striae about 11 in 10/x, radiate, slightly curved and 

convex toward the apices. Length, 29/*-30//,; width, 

about 9/t-lO//,.

Remarks. This species occurs in all of the samples 

studied from Kilgore. It is common in USGS diatom 

locality 5836, frequent in locality 5419, and rare in 

localities 5833-5835 and 5837.

Living representatives of the species are widespread in slightly saline and in fresh-water environments.

Known geologic range. Late Miocene to present.

Navicula elginensis var. rostrata (A. Mayer) Patrick

Plate 2, figure 19

Navicula dicephala var. rostrata A. Mayer, 1917, Kgl. Bayern 

botanischen Gesellschaft Denkschriften, v. 13 (N.F. 7), 

p. 114, pi. 1, fig. 42a, b.*

Navicula elginensis var. rostrata (A. Mayer) Patrick, in 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon 13, p. 526, pi. 50, fig. 6.

Remarks. This variety is distinguished from the 

type on the basis of its subrostrate to rostrate apices. 

Other characteristics and modern ecology are similar 

to those of the type.

The variety occurs frequently in USGS diatom 

locality 5419.

Known geologic range. Late Miocene to present.

Genus PINNULARIA Ehrenberg, 1840 

Pinnularia subcapitata var. paucistriata (Grunow) Cleve

Plate 3, figure 1

Navicula subcapitata var. paucistriata Grunow, in Van 

Heurck, 1880, Synopsis des diatomees de Belgique, 

pi. 6, fig. 23.

Pinnularia subcapitata var. paucistriata (Grunow) Cleve, 

1895, Kgl. svenska vetensk. akad. Handl., v. 27, no. 3, 

p. 75.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 597, pi. 55, fig. 11.

Pinnularia subcapitata var. paucistriata Grunow. Hustedt, 

in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, 

no. 10, p. 317.

Description. Valve linear with rounded apices; 

axial area narrow near apices, widening uniformly to 

central area, which is a transverse fascia because of 

lack of striae along the lateral margins; striae about 

11 in 10/x, slightly radiate near the center, slightly 

convergent near the apices. Length, about 27/t; width 

about Sfi.

Remarks. This variety is similar to modern 

forms, but the apices do not appear to be at all 

rostrate.

Rare in USGS diatom locality 5833. 

Modern representatives of this variety prefer fresh 

water of low mineral content.

Known geologic range. Late Miocene to present.

Pinnularia brevicostata Cleve

Plate 3, figure 2

Pinnularia brevicostata Cleve, 1891, Soc. pro Fauna et Flora 

Fennica, Acta, v. 8, no. 2, p. 25, pi. 1, fig. 5.

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 329-330, fig. 609.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 623, pi. 60, fig. 1.

Description. Valve linear with a slight expansion 

at the center; rounded apices; axial area about half 

the width of the valve; striae short, 12 in 10/*, slightly 

radiate, very slightly shortened at the central area. 

Length about 53/x; width about 11/x.

Remarks. This species is rare in USGS diatom 

locality 5419.

Living representatives of the species prefer cool 

waters of low mineral content. 

Known geologic range. Late Miocene to present.

Pinnularia clevei Patrick

Plate 3, figure 3

Pinnularia clevei Patrick, 1945, Farlowia, v. 2, no. 2, p. 193, 

pi. 3, figs. 9, 10.

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia 

Mon. 13, p. 628-629, pi. 61, fig. 3.

Description. Valve elongate but slightly expanded
A18 CONTRIBUTIONS TO PALEONTOLOGY

near the center; axial area about a third the width 

of the valve; costae, seven in ID/*, slightly radiate in 

the center but convergent near the apices; costae 

crossed by a longitudinal band; central area slightly 

asymmetrical but only vaguely differentiated from 

the axial area. Length about 113^; width about 21/*.

Remarks. This species is rare in USGS diatom 

locality 5835.

Living representatives of the species have widespread distribution in freshwater environments.

Known geologic range. Late Miocene to present.

Pinnularia torta (Mann) Patrick 

Plate 3, figures 4, 5

Navicula torta Mann, 1924, Washington Acad. Sci. Jour., v.

14, p. 31, pi. 4, fig. 6. 

Pinnularia torta (Mann) Patrick, in Patrick and Reimer,

1966, Acad. Nat. Sci. Philadelphia Mon. 13, p. 634,

pi. 63, fig. 3. 

Pinnularia major var. asymmetrica Cleve, 1895, Kgl. svenska

vetensk. akad. Handl., v. 27, no. 3, p. 89, pi. 1, fig. 22.

Description. Valve linear with rounded ends, on 

some specimens slightly swollen in the center; axial 

area about V^rV^ the width of the valve, noticeably 

asymmetrical to the center line; raphe about centrally 

located in the axial area, filamentous, oblique to the 

plane of the valves; central area rounded, slightly 

expanded in direction of the deflection of the central 

pores of the raphe; costae about eight in 1(V, moderately radiate at the center and convergent at the 

ends, some specimens flexed to an attenuated S-shape, 

crossed by a broad longitudinal band. Length, 112^- 

196^; width, 20^-28^.

Remarks. The specimens of P. torta observed in 

the Kilgore deposit appear to be somewhat less asymmetrical with regard to raphe and axial area than 

that figured by Patrick and Reimer (1966, pi. 63, 

fig. 3).

The species is rare in USGS diatom localities 5419, 

5834, and 5836.

Living representatives of the species prefer standing acid waters of low mineral content. 

Known geologic range. Late Miocene to present.

Pinnularia viridis (Nitzsch) Ehrenberg

Plate 3, figure 6

Bacillaria viridis Nitzsch, 1817, Naturf. Gesell. Halle, Neue 

Schr. v. 3, no. 1, p. 97-98, pi. 6, figs. 1-3.

Pinnularia viridis (Nitzsch) Ehrenberg, 1843, Kgl. preuss. 

Akad. Wiss. Berlin, Phys. Abh., 1841, p. 305, 385, 

pi. 1, fig. I, 7, fig. Ill, 3; fig. IV, 3; pi. 2, fig. I, 22, 

fig. Ill, 1, fig. V, 2, fig. VI, 21; pi. 3, fig. I, 1, 2.

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 334-335, fig. 617a. 

Patrick and Reimer, 1966, Acad. Nat. Sci. Philadelphia

Mon. 13, p. 639, pi. 64, fig. 5.

Description. Valve linear, tapering toward 

rounded apices; axial area narrow, widening slightly 

to form a small rounded, asymmetrical central area; 

raphe complexly twisted; costae six to eight in 10/*, 

slightly radiate at center and becoming slightly 

divergent near the apices and crossed by a welldefined longitudinal band. Length, 86^-121^; width, 

17/*-20/*.

Remarks. The species occurs frequently in USGS 

diatom localities 5419 and 5835.

Living representatives of this species prefer circumneutral water but are tolerant of waters with a 

high mineral content.

Known geologic range. Late Miocene to present.

Family CYMBELLACEAE Agardh, 1830 

Genus CYMBELLA Agardh, 1830

Cymbella naviculiformis Auerswald

Plate 3, figure 7

Cymbella naviculiformis Auerswald, in Rabenhorst, 1861, Die

Algen Europa's, no. 1065.* 

Cleve, 1894, Kgl. svenska vetensk. akad. Handl., v. 26,

no. 2, p. 166. 

Boyer, 1927, Acad. Nat. Sci. Philadelphia Proc., v. 79,

supp., p. 281. 

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 356-357, fig. 653.

Description. Valve elliptical-lanceolate, slightly 

asymmetrical, with protracted rostrate apices; axial 

area narrow, widening into a rounded central area; 

raphe off center, slightly convex toward the dorsal 

side; striae, about 12 in ID/*, radiate, finely punctate. 

Length, 34^-43^; width, about 12^.

Remarks. This species occurs frequently in USGS 

diatom localities 5419 and 5837, and it is rare in 

locality 5835.

C. naviculiformis is a common and widespread 

fresh-water diatom species.

Known geologic range. Late Miocene to present.

Cymbella ehrenbergii Kiitzing

Plate 3, figure 8

Cymbella ehrenbergii Kutzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 79, pi. 6, fig. 11. 

Cleve, 1894, Kgl. svenska vetensk. akad. Handl., v. 26, 

no. 2, p. 165.

Boyer, 1927, Acad. Nat. Sci. Philadelphia Proc., v. 79, 

supp., p. 275.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA A19

Hustedt, in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 356, fig. 656.

Description. Valve lanceolate, slightly asymmetric with slightly protracted subrostrate apices; raphe 

slightly off center but nearly straight; axial area narrow, widening into a rounded asymmetric central 

area; striae nine to 11 in 10/u,, irregularly spaced and 

formed of distinct closely spaced puncta. Length, 

48ju,-58ju,; width, about 17^.

Remarks. The species is common in USGS diatom locality 5419 and rare in localities 5834 and 5835.

Modern representatives of this species are common 

and widespread in many fresh-water environments.

Known geologic range. Late Miocene to present.

Cymbella cistula (Hemprich) Grunow

Plate 3, figure 9

Bacillaria cistula Hemprich, in Ehrenberg, 1828, Symbolae

physicae (Phytozoa), pi. 2, fig. IV, 10.* 

Cymbella cistula (Hemprich) Grunow, in Van Heurck, 1880,

Synopsis des diatomees de Belgique, p. 64, pi. 2, fig. 12. 

Boyer, 1927, Acad. Nat. Sci. Philadelphia Proc., v. 79,

supp., p. 280. 

Hustedt, in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 363, fig. 676a. 

Cymbella cistula Hemprich. Cleve, 1894, Kgl. svenska vetensk.

akad. Handl., v. 26, no. 2, p. 173.

Description. Valve markedly asymmetric, with a 

convex dorsal side and a concave ventral side that 

often shows a slight swelling in center; apices 

rounded; raphe off center; axial area narrow, expanding to a rounded central area on some specimens; striae about eight in 1(V, coarsely punctate, 

radial; striae on the ventral side terminate in a row 

of very coarse isolated puncta along the margin of 

the central area. Length, 92^-150^; width, about 25/u,.

Remarks. This species occurs in all samples studied for this report. It is abundant in USGS diatom 

localities 5419 and 5836, common in locality 5837, 

frequent in locality 5835, and rare in localities 5833 

and 5834.

Modern representatives of the species are widespread and common in fresh-water environments.

Known geologic range. Late Miocene to present.

Cymbella cistula var. maculata (Kiitzing) Van Heurck

Plate 3, figure 10

Frustulia maculata Kiitzing, 1834, Algarum aquae dulcis 

Germinacarum, Dec. no. 85.*

Cymbella cistula var. maculata (Kiitzing) Van Heurck, 1880,

Synopsis des diatomees de Belgique, p. 64, pi. 2, figs.

16, 17. 

Cleve, 1894, Kgl. svenska vetensk. akad. Handl., v. 26,

no. 2, p. 173. 

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 363, fig. 676b. 

Cymbella cistula maculata (Kiitzing) A. Schmidt. Boyer,

1927, Acad. Nat. Sci. Philadelphia Proc., v. 79, supp.,

p. 280.

Remarks. C. cistula var. maculata is similar to 

the type variety, except that the axial area does not 

expand to form a distinct central area and the row 

of conspicuous heavy puncta on the ventral side of the 

central area is lacking.

This variety is common in USGS diatom locality 

5419 and frequent in localities 5834-5836.

Living representatives of the variety are frequently 

found in association with the type and are common 

and widespread in fresh-water environments.

Known geologic range. Late Miocene to present.

Cymbella tumida (Brebisson) Van Heurck

Plate 3, figure 11

Cocconema tumidum Brebisson, in Kiitzing, 1849, Species

Algarum, p. 60.* 

Cymbella tumida (Brebisson) Van Heurck, 1880, Synopsis

des diatomees de Belgique, p. 64, pi. 2, fig. 10. 

Cleve, 1894, Kgl. svenska vetensk. akad. Handl., v. 26,

no. 2, p. 176. 

Boyer, 1927, Acad. Nat. Sci. Philadelphia Proc., v. 79,

supp., p. 280. 

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 366, fig. 677.

Description. Valve cymbiform, with convex dorsal side and nearly straight ventral side marked by a 

broad but slight central swelling; apices small, 

rounded, subrostrate; raphe central, but markedly 

curved; axial area narrow near the apices, tapering 

wider toward the center, and expanded to form a 

small central area; striae eight to 10 in 10/u,, ornamented with heavy puncta; striae mostly normal to 

the raphe but slightly radial near the apices. A distinctive feature is the presence of a single coarse 

punctum on the ventral side of the central area. 

Length about 34^; width about 14^.

Remarks. The species occurs frequently in USGS 

diatom locality 5837.

Living representatives of the species are widespread in fresh-water environments, but they are seldom found in abundance.

Known geologic range. Late Miocene to present.
A20 CONTRIBUTIONS TO PALEONTOLOGY

Family GOMPHONEMACEAE Kutzing, 1844 

Genus GOMPHONEMA Agardh, 1824

Gomphonema affine Kutzing

Gomphonema affine Kutzing, 1844, Die kieselschaligen Bacillarien oder Diatomeen, p. 86, pi. 30, fig. 54. 

Grunow, in Van Heurck, 1880, Synopsis des diatomees

de Belgique, pi. 24, figs. 8, 9. 

Gomphonema lanceolatum Cleve, 1894 [non Ehrenberg, 1843],

Kgl. svenska vetensk. akad. Handl., v. 26, no. 2, p. 183. 

Hustedt, in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 376, fig. 700. 

Gomphonema lanceolatum Cleve, 1894 [non Kutzing, 1844].

Boyer, 1927, Acad. Nat. Sci. Philadelphia Proc., v. 79,

supp., p. 295.

Remarks. It is evident from the examination of 

the pertinent literature that Cleve (1894, p. 183) 

based both his G. lanceolatum and his G. gracile var. 

lanceolata on G. lanceolatum Ehrenberg. As was 

pointed out by Andrews (1966, p. A19), only G. gracile var. lanceolata of Cleve and others conforms to 

Ehrenberg's original description of G. lanceolatum. 

Therefore, the G. lanceolatum of Cleve (1894), Boyer 

(1927), Hustedt (1930), and others, is an invalid 

name, and it should be replaced. It is here proposed 

that the name Gomphonema affine Kutzing, 1844, replace the name Gomphonema lanceolatum Cleve, 1894 

[non Ehrenberg, 1843].

The type of Gomphonema affine does not occur in 

the Kilgore deposit, but this nomenclatural problem 

must be resolved before discussing a variety of the 

species.

Gomphonema affine var. insignis (Gregory) Andrews, n. comb.

Plate 3, figures 12-16

Gomphonema insigne Gregory, 1856, Micros. Soc. Quart.

Jour., v. 4, p. 12, pi. 1, fig. 39. 

Grunow, in Van Heurck, 1880, Synopsis des diatomees

de Belgique, pi. 24, figs. 39-41. 

Gomphonema lanceolatum var. insignis (Gregory) Cleve,

1894, Kgl. svenska vetensk. akad. Handl., v. 26, no. 2,

p. 183. 

Hustedt, in Pascher, 1930, Die Susswasser-flora Mitteleuropas, no. 10, p. 376, fig. 701. 

Gomphonema lanceolatum insigne (Gregory) Cleve. Boyer,

1927, Acad. Nat. Sci. Philadelphia Proc., v. 79, supp.,

p. 295.

Description. Valve lanceolate-clavate to nearly 

lanceolate, rounded on the upper end but somewhat 

more acutely pointed on the lower end; axial area 

about one-fourth the width of the valve; central area 

asymmetrical, formed by shortening of a single stria

on one side of the valve; a single stigma on opposite 

side of valve from the shortened central stria; raphe 

filamentous, with small terminal pores deflected 

toward the stigma; striae six to nine in 10^, fine, 

sharply punctate. Length, 29^-84jn; width, 9^-12^.

Remarks. The most distinctive characteristic of 

G. affine var. insignis in the Kilgore deposit is its 

high degree of variability both in external shape and 

internal ornamentation. The great variation in length 

together with nearly constant width causes considerable variation in external form. Some of the longer 

specimens resemble G. intricatum or even G. intricatum var. vibrio in external outline. In addition 

there is considerable variation in the fineness of the 

striae, whereas the spacing of the striae remains 

relatively constant. These factors seem, however, to 

indicate only a high degree of variation within a 

single taxon. Because of the intergradation between 

individuals in the population, any attempt at differentiating the taxon into several species or varieties 

seems to be both arbitrary and useless.

Common in USGS diatom localities 5419 and 5836; 

occurs frequently in localities 5833-5835 and 5837.

Living representatives of this variety are common 

in a wide range of fresh-water environments.

Known geologic range. Late Miocene to present.

Family NITZSCHIACEAE Grunow, 1860

Subfamily NITZSC HIOIDEAE Grunow, 1860

Genus HANTZSCHIA Grunow, 1880

Hantzschia elongata (Hantzsch) Grunow

Nitzschia vivax var. elongata Hantzsch, 1860, Hedwigia, v. 2, 

no. 6, p. 35-36, pi. 6, fig. 5.

Hantzschia elongata (Hantzsch) Grunow, in Cleve and Grunow, 1880, Kgl. svenska vetensk. akad. Handl., v. 17, 

no. 2, p. 104.

Hustedt, in Pascher, 1930, Die Siisswasser-flora Mitteleuropas, no. 10, p. 395, fig. 751.

Hantzschia elongata Grunow. Boyer, 1927, Acad. Nat. Sci. 

Philadelphia Proc., v. 79, supp., p. 528.

Description. Valve linear, elongate, tapering 

somewhat abruptly to capitate apices; keel puncta 

about five in 10^; transverse striae about 12 in 1(V, 

distinct and finely punctate. Length, more than 14(V; 

width about 12^-13p.

Remarks. This very long, slender species is found 

only as fragments in the Kilgore deposit. This fragmentation, together with a rather strong twisting of 

the keel near the apices, causes great difficulty in the 

preparation of a photomicrograph of the species at 

high magnification.
MIOCENE NONMARINE DIATOMS FROM KILGORE AREA, CHERRY COUNTY, NEBRASKA 21

Hantzschia elongata occurs frequently in USGS 

diatom locality 5836.

Living representatives of the species are widespread in fresh-water environments.

Known geologic range. Late Miocene to present.

Genus NITZSCHIA Hassall, 1845 

Nitzshia calva Andrews, n. sp.

Plate 3, figures 17-20

Diagnosis. Valve linear-lanceolate with slight 

central constriction and tapering to narrowly rounded 

or slightly rostrate apices; keel puncta variable, 

averaging about eight to nine in 10/x; transverse 

striae fine, punctate, about 22 in 10/x; transverse 

striae fringe the margins of the valve only and end 

irregularly as scattered puncta around a hyaline area 

at the center of the valve; rare puncta are scattered 

in central hyaline area; fringing striae are longer on 

the keel side of the valve. Length, about 70/x-80/x; 

width, about 12/x, slightly less at center.

Remarks. N. calva shows obvious affinities for 

the group Tryblionellae (Grunow, in Cleve and Grunow, 1880, p. 67), but it is much more finely striated 

than most modern species of this group. The species 

most closely resembles N. plana W. Smith, as figured 

by Hendey (1964, pi. 39, fig. 7), a brackish-water 

species from the coastal waters of Great Britain. N. 

calva, however, as it occurs in the Kilgore deposit, is 

smaller, more finely striated, and has finer keel 

puncta than N. plana. The apices of N. calva are also 

somewhat more attenuated. N. calva shows similarities to N. fremontensis Lohman and Andrews (1968) 

from the upper Eocene of Wyoming. It differs from 

the latter species, however, in the slightly greater 

biconstriction of the valves and in the central hyaline 

area. N. fremontensis does show some central break 

down of the transverse striae into individual puncta, 

but it shows nothing suggesting the central hyaline 

area which is a distinctive feature of N. calva.

Holotype. VSGS diatom catalog 3626-43 (pi. 3, 

figs. 17, 18), length, 76/x; width, 12/x.

Paratype. USGS diatom catalog 3626-37 (pi. 3, 

figs. 19, 20) length, 70/x; width, 12/x. Both from USGS 

diatom locality 5836.

This species is rare in USGS diatom locality 5836.

Known geologic range. Late Miocene.

SELECTED REFERENCES

Andrews, G. W., 1966, Late Pleistocene diatoms from the 

Trempealeau Valley, Wisconsin: U.S. Geol. Survey Prof. 

Paper 523-A, 27 p., 3 pis.

Barbour, E. H., and Cook, H. J., 1917, Skull of Aelurodon

platyrhinus sp. nov.: Nebraska Geol. Survey, v. 7, p.

173-180. 

Boyer, C. S., 1927, Synopsis of North American Diatomaceae: Acad. Nat. Sci. Philadelphia Proc., v. 78, supp.,

p. 1-228; v. 79, supp., p. 229-583. 

Chaney, R. W., and Axelrod, D. I., 1959, Miocene floras of

the Columbia Plateau: Carnegie Inst. Washington Pub.

617, 237 p. 

Cheremisinova, Ye. A., 1968, Novye dannye o diatomeyakh

Neogenovykh Otlozheniy PribaykaPya, in Iskopayemye

Diatomovye Vodorosli SSSR; Moscow, Akad. Nauk

SSSR, p. 71-74, pis. 3-6. 

Cleve, P. T., 1894 1895, Synopsis of the naviculoid diatoms:

Kgl. svenska vetensk. akad. Handl., v. 26, no. 2, 194 p.?

5 pis., 1894; v. 27, no. 3, 219 p., 4 pis., 1895. 

Cleve, P. T. and Grunow, Albert, 1880, BeitrSge zur Kenntniss

der arctischen Diatomeen: Kgl. svenska vetensk. akad.

Handl., v. 17, no. 2, p. 1-121, pis. 1-7.

Darton, N. H., 1898, Geology and water resources of Nebraska west of the one hundred and third meridian: U.S.

Geol. Survey 19th Ann. Rept. pt. 4, p. 719-785. 

Dorf, Erling, 1936, A late Tertiary flora from southwestern

Idaho: Carnegie Inst. Washington Pub. 476, p. 73-124,

3 pis.

Ehrenberg, C. G., 1843, Verbreitung und Einfluss des mikroskopischen Lebens in Slid- und Nord-Amerika: Kgl. 

preuss. Akad. Wiss. Berlin, Phys. Abh., 1841, p. 291-445,

4 pis.

Hendey, N. I., 1937, The plankton diatoms of the southern 

seas: Discovery Repts., v. 16, p. 151-364, pis. 6-13.

____ 1964, An introductory account of the smaller algae of 

British coastal waters, Part V, Bacillariophycese (Diatoms) : London, Ministry of Agriculture, Fisheries, and 

Food, 317 p., 45 pis.

Heribaud, Joseph, 1902, Les diatomees d'Auvergne: ClermontFerrand, France, 166 p., 4 pis.

Hustedt, Friedrich, 1927-30, 1931-59, 1961-66, Die Kieselalgen Deutschlands, Osterreichs, und der Schweiz, Band 7 

of Rabenhorst, G. L., Kryptogamenflora***: Leipzig, 

Akademische Verlagsgesellschaft, pt. 1, 920 p., 542 figs., 

1927-30; pt. 2, 845 p., 637 figs., 1931-1959; pt. 3, lieferungen 1-4, p. 1-816, figs. 1180-1788, 1962-66.

____ 1930, Bacillariophyta (Diatomese), Heft 10 of Pascher, 

Adolf, ed., Die Susswasser-flora Mitteleuropas: Jena, 

Gustav Fischer, 466 p., 875 figs.

Johnson, F. W., 1936, The status of the name "Valentine" in 

Tertiary geology and paleontology: Am. Jour. Sci., 5th 

ser., v. 31, p. 467-475.

Karsten, George, 1928, Bacillariophyta (Diatomese), in Engler, Adolf, Die naturlichen Pflanzenfamilien; Band 2, 

Peridineae (Dinoflagellatae), Diatomese (Bacillariophtya); 

Myxomycetes: Leipzig, Wilhelm Englemann, p. 105-303, 

329 figs.

Kutzing, F. T., 1844, Die kieselschaligen Bacillarien oder 

Diatomeen: Nordhausen, W. Kohne, 152 p., 30 pis.

Lauby, Antoine, 1910, Recherches paleophytologiques dans le 

Massif Central: France Service Carte Geol. Bull. 125, 

v. 20, 398 p., 14 pis.

Lohman, K. E., and Andrews, G. W., 1968, Late Eocene nonmarine diatoms, Beaver Divide areas, Fremont County, 

Wyoming: U.S. Geol. Survey Prof. Paper 593-E, 26 p., 

2 pis.
A22 CONTRIBUTIONS TO PALEONTOLOGY

Lugn, A. L., 1938, The Nebraska State Geological Survey and 

the "Valentine problem:" Am. Jour. Sci., 5th ser., v. 36, 

no. 213, p. 220-227.

____ 1939, Classification of the Tertiary System in Nebraska: Geol. Soc. America Bull., v. 50, no. 8, p. 1245- 

1275, 1 pi.

MacGinitie, H. D., 1962, The Kilgore flora: California Univ. 

Pubs. Geol. Sci., v. 35, no. 2, p. 67-158, 16 pis.

Moore, R. C., 1954, Kingdom of organisms named Protista: 

Jour. Paleontology, v. 28, p. 588-598.

Patrick, Ruth, and Reimer, C. W., 1966, The diatoms of the 

United States, v. 1: Acad. Nat. Sci. Philadelphia Mon. 

13, 688 p., 64 pis.

Schtitt, Franz, 1896, Bacillariales (Diatomeae), in Engler, 

Adolf, and Prantl, K. A. E., Die natiirlichen Pflanzenfamilien: Leipzig, pt. 1, Abt. Ib, p. 31-153, 282 figs.

Stirton, R. A., and McGrew, P. 0., 1935, A preliminary notice 

on the Miocene and Pliocene mammalian faunas near 

Valentine, Nebraska: Am. Jour. Sci., 5th ser., v. 29, no. 

170, p. 125-132.

Webb, S. D., 1969, The Burge and Minnechaduza Clarendonian mammalian faunas of north-central Nebraska: California Univ. Pubs. Geol. Sci., v. 78, 191 p.

Wood, H. E. 2d, and others, 1941, Nomenclature and correlation of the North American continental Tertiary: Geol. 

Soc. America Bull., v. 52, p. 1-48, 1 pi.
INDEX

[Italic page numbers indicate major references and descriptions]

D

Achnanthaceae .................

Achnanthes ....................

hungarica .................

Achnanthidium hungaricum ........ .13

Achnanthoideae ...................

actinota, Navicula ............. .6, 15

affine, Gomphonema ...............

insignis, Gomphonema ..... 6, 7, 20;

amphibola, Navicula ............ 6,14;

Amphora ........................

ampliata, Navicula ................

Neidium iridis ............ .6,14;

ampliatum, Neidium iridis ...........

anceps, Stauroneis ............. .6,13;

anglica subsalsa, Navicula ....... .6,16;

angustissima, Melosira ..............

Melosira granulata ............ 6, 9; Anomoeoneis ......................

sphaerophora ............. .6, 14;

Araphidineae .....................

asymmetrica, Pinnularia major .......

B

Page 

A13

7, 13

6

, Pi. 1

13

;pl. 2

8,20 

pi. 3 

pi. 2

7

14

pi. 2

14

pi. 2

 pi. 2

9

: Pi- 1 

11

pi. 2 

9 

18

Bacillaria cistula .................. 19

phoenicenteron ................ 13

ulna ........................ 12

viridis ....................... 18

bacillum, Navicula .............. 6,16; pi. 2

Biraphidineae ..................... 13

brevicostata, Pinnularia .......... 6,1 7; pi. 3

brevistriata, Fragilaria .......... .6,11; pi. I

Caloneis ......................... 7

calva, Nitzschia ................ 6, 21; pi. 3

capitata, Tetracyclus lacustris ........ 10

Centrales ........................ 8

Chrysophyta ...................... 8

cistula, Bacillaria .................. 19

Cymbella ............... 6, 8,19; pi. 3

maculata, Cymbella ......... 6, 19; pi. 3

clevei, Pinnularia ............... 6,17; pi. 3

Cocconeis ........................ 7

tumidum ..................... 19

Coscinodiscaceae .................. 8

crenulata, Gallionella ............... 9

Meloseira .................... 9

Melosira ..................... 9

cruciformis, Tetracyclus ......... .6, 11; pi. 1

cuspidata, Frustulia ................ 15

Navicula ..................... 6, 15

cuspidata genuina, Navicula .......... 15

Cyclotella ........................ 6

Cymbella ........................ 7, 18

cistula .................. 6, 8,19; pi. 3

maculata ................ 19; pi. 3

ehrenbergii ................ 6, 18; pi. 3

maculata .................... 6

naviculiformis .............. 6,18; pi. 3

tumida ................. 6, 19; pi. 3

Cymbellaceae ..................... 18

Denticula ..........

Diatom assemblage . . 

Diatoma ...........

Diatomophyceae . . . . .

dicephala, Navicula . .

rostrata, Navicula

Diploneis ..........

Discineae ..........

distans, Gaillonella . . .

Page 

.......... A7

.......... 5

.......... 6

.......... 8

.......... 17

.......... 17

.......... 7

.......... 8

.......... 9

Melosira .................. .6, 9; pi. 1

E

ehrenbergii, Cymcella ........... .6,18; pi. 3

elginensis, Navicula ............. 6, 17; pi. 2

rostrata, Navicula ........... 6,17; pi. 2

Pinnularia .................... 17

ellipticus, Tetracyclus .............. 11

elongata, Hantzschia ............... 6,20

Nitzschia vivax ................ 20

Tetracyclus lacustris ........... 10

Epithemia ........................ 7

Eunotia ......................... 6, 12

parallela .................. 6, 12; pi. 1

pectinalis minor ........... .6, 12; pi. 1

Eunotiaceae ...................... 12

floriformis, Tetracyclus 

Fragilaria ..........

brevistriata .....

gigantea .......

virescens .......

Fragilariaceae ......

Fragilarioideae ......

fremontensis, Nitzschia 

Frustulia cuspidata . .

maculata ......

11 

11

.6,11; pi. 1

.6,11; pi. 1

11

9

11

21

15

19

Gaillonella distans .................

italica .......................

Gallionella crenulata ...............

granulata ....................

genuina, Navicula cuspidata .........

gigantea, Fragilaria ............. 6, 11;

Gomphonema .....................

affine .......................

insignis ............. 6, 7, 20

gracile lanceolata ..............

insigne ......................

intricatum ...................

vibrio ...................

lanceolatum ..................

insigne ..................

insignis ..................

Gomphogramma rupestre ............

Gomphonemaceae .................

gracile lanceolata, Gomphonema ......

gracilis, Stauroneis phoenicenteron ....

Tetracyclus tripartitus ..........

15 

pi. 1 

7,20 

8,20

; pi. 3

20

20

20

20

20

20

20

10

20

20

13

10

Page 

graciloides, Navicula ........... A6,16; pi. 2

granulata, Gallionella .............. 8

Melosira ................... 6, 8; pi. 1

angustissima, Melosira .......... 9; pi. 1

H

halophila, Navicula ................ 16

Hantzschia ....................... 20

elongata ...................... 6, 20

Himatidium minus ................. 12

hungarica, Achnanthes .......... .6,13; pi. 1

hungaricum, Achnanthidium ......... 13

insigne, Gomphonema .............. 20

Gomphonema lanceolatum ....... 20

insignis, Gomphonema lanceolatum .... 20

intricate ~n, Gomphonema ........... 20

vibrio, Gomphonema ........... 20

iridis ampliata, Neidium ........ .6,14; pi. 2

iridis ampliatum, Neidium ........... 14

italica, Gaillonella ................. 9

Melosira ................. .6, 8, 9; pi. 1

Kilgore diatomite deposit ............ 1

L

lacustris, Tetracyclus ....... .6, 9, 10, 11; pi. 1

capitata, Tetracyclus .....

elongata, Tetracyclus ..... 

lanceolata, Gomphonema gracile 

lanceolatum, Gomphonema ....

insigne, Gomphonema ....

insignis, Gomphonema

10

10

20

20

20

20

lauenburgiana, Stauroneis ......... 6, 14; pi. 2

M

maculata, Cymbella ................ 6

Cymbella cistula ............ 6, 19; pi. 3

Frustulia ..................... 19

Navicula ..................... 15

major asymmetrica, Pinnularia ....... 18

Mascall flora of Oregon ............. 5

Mastogloia ....................... 7

Meloseira crenulata ................ 9

Melosira ......................... 7,8

Melosira angustissima .............. 6

crenulata .................... 9

distans ..................... 6, 9; pi. 1

granulata .................. 6, 8; pi. 1

angustissima ............ 6, 9; pi. 1

italica .................... 6, 8,9; pi. 1

Melosiroideae ..................... 8

Meridian ........................ 6

minor, Eunotia pectinalis ....... .6,12; pi. 1

minus, Himatidium ................ 12

Monoraphidineae .................. 13

N

Navicula ......................... 14

actinota .................... 6,15; pi. 2

A23
A24

ontinued 

amphibola ............... .A6, 14;

qmpliata .....................

flftgZica subsalsa ............. 6, 16;

bacttlum .................. 6, 16;

cuspid at a .,,......,,,..........

genuina ..................

(licephala ....................

rostrate ..................

eJgtnensis ...,.,,,......... 6, 17;

rostrata ............... 6, 1 7;

graciloides ................ 6, 1 6;

halophiln .....,,,,....,,.....

................. .6, 15;

radt«s« ................... 6, 16;

subcapitata

Navicylaceae

naviculiformis,

Navjculoideae

. 6, 18;

iridis amplittftt ,....,,,,,.... 6, 14;

niobrara, Navicul® .............. 6, 15;

Nitzschia ....,,.,,,..,..,.,......

caZwa ....,,,,..,.,.,,..... 6, 21;

fremontensis ,,.,.,,,..........

plana ..,,,,,,,,,.,...........

Nitzschiaceae 

Nitzschioideae

Ogallala Formation of Lugn 

Orthosira punctata .......

Page 

 pi. 2

14 

pi. 2 

pi. 2 

6,15

15

17

17

pi. 2

pi. 2

pi. 2

16

15

pi. 2

pi. 2

14

17

18 

16 

15 

13 

pi. 3

13

14

pi 2

14

pi. 2 

21 

pi. 3 

21 

21 

20 

20 

20

pagesi, Tetracyclus ........... .. 6, 10; pi. 1

Paleobotany ...................... 5

Paleoecologic interpretation .......... 7

parallela, Eunotia .............. 6, 12; pi. 1

paucistriata, Navicula subcapitata .... 17

Pinnularia subcapitata ....... 6,17; pi. 3

pectinalis minor, Eunotia ....... .6,12; pi. 1

INDEX

Page 

Pennales .......................... A9

phoenicenteron, Bacillaria ........... 13

Stauroneis ................. 6, 13; pi. 2

gracilis, Stauroneis ............ 13

Pinnularia ........................ 17

brevicostata ................ 6,1 7; pi. 3

clevei ................... .6, 17; pi. 3

elginensis .................... 17

major asymmetrica ............ 18

subcapitata paucistriata ..... .6, 17; pi. 3

torta .................... .6, IS; pi. 3

wmdis .................... 6, IS; pi. 3

plana, Nitzschia ....

Protista ...........

Protoctista ........

punctata, Orthosira . 

punctatae, Naviculae

21

8

8

8

15

R

radiosa, Navicula .............. .6,16; pi. 2

Raphidioidineae ................... 12

Rhopalodia ....................... 7

rostrata, Navicula dicephala ......... 17

Navicula elginensis ......... 6, 17; pi. 2

rumpens, Synedra .............. 6, 12; pi. 1

rupestre, Gomphogramma ........... 10

rupestris, Tetracyclus ........... .6, 10; pi. 1

smithii, Stauroneis ............. .6, 13;

sphaerophora, Anomoeoneis . .... .6, 14;

Navicula .....................

anceps .................... 6, 13;

lauenburgiana .............. 6, 14;

phoenicenteron ............. 6, 13;

gracilis ..................

xmithii .................... 6, 13;

Stephanodiscus ....................

Stratigraphic section of the Kilgore 

fossil-plant locality ...............

Stratigraphic significance of diatom 

assemblage .....................

subcapitata paucistriata, Navicula ....

paucistriata, Pinnularia ...... 6, 1 7;

subsala, Navicula anglica ......... 6, 16;

pi. 2

pi. 2

14

13

pi. 2

pi. 2

pi. 2

13

pi. 1

6

5

17

pi. 3

pi. 2

subsala Continued Page 

Navicula tumida ............... A16

St/nedra ......... ................ 12

rumpens .................. 6,12; pi. 1

ufria ..................... .6, 12; pi. 1

Systematic descriptions ............. 8

Tabellaria ........................ 6

Tabellarioideae ................... 9

Tetracyclus ......................... 6, 11

cruciformis ................. 6, II; pi. 1

ellipticus ..................... 11

floriformis .................... 11

lacustris ............ .6, 9, 10, 11; pi. 1

lacustris capitata .............. 10

lacustris elongata .............. 10

pagesi ..................... 6,10; pi. 1

rupestris ................... 6, 10; pi. 1

tripartitus ................. 6, 10; pi. 1

gracilis .................. 10

torta, Navicula .................... 18

Pinnularia .................6, IS; pi. 3

tr:partitus, Tetracyclus ........... 6, 10; pi. 1

gracilis, Tetracyclus ............ 10

tumida, Cymbella .............. 6,19; pi. 3

subsalsa, Navicula ............. 16

tumidum, Cocconema .............. 19

, Bacillaria .................... 12

Synedra ................... 6,12; pi. 1

V

Valentine Formation of Lugn .......... 1, 3

Vertebrate paleontology ............. 5

vibrio, Gomphonema intricatum ...... 20

oirescens, Fragilaria ................ 11

viridis, Bacillaria .................. 18

Pinnularia ................. 6, 18; pi. 3

wtwax elongata, Nitzschia ............ 20

W

Weiser flora of Idaho

U.S. GOVERNMENT PRINTING OFFICE : 1970 O 382-018
PLATES 1-3
PLATE 1

[All figures X 960 except fig. 25 which is X 1,230]

FIGURE 1, 2. Melosira granulata (Ehrenberg) Ralfs (p. A8).

1. USGS diatom catalog 3405-81. Diameter, 15/i.

2. USGS diatom catalog 3624-15. Diameter, 15/t.

3. Melosira granulata var. angustissima Miiller (p. A9). 

USGS diatom catalog 3624-4. Diameter 5fi.

4. Melosira italica (Ehrenberg) Kiitzing (p. A9). 

USGS diatom catalog 3627-4. Diameter, IS/j..

5. Melosira distans (Ehrenberg) Kiitzing (p. A9). 

USGS diatom catalog 3405-30. Diameter, 18/*. 

6, 7. Tetracyclus locustris Ralfs (p. A9).

6. USGS diatom catalog 3405-13. Length, 26/*.

7. USGS diatom catalog 3625-16. Length, 29/*. 

8, 9. Tetracyclus pagesi Heribaud (p. A10).

8. USGS diatom catalog 3625-29. Length, 36/*.

9. USGS diatom catalog 3626-19. Length, 35/*. 

10, 11. Tetracyclus tripartitus Brun and Heribaud (p. A10).

10. USGS diatom catalog 3405-67. Length, 640.

11. USGS diatom catalog 3625-40. Length 55/*. 

12, 13. Tetracyclus rupestris (A. Braun) Grunow (p. A10).

12. USGS diatom catalog 3405-36. Length, 20/*.

13. USGS diatom catalog 3625-28. Length, 13/*. 

14-17. Tetracyclus cruciformis Andrews, n. sp. (p. All).

14. Holotype, USGS diatom catalog 3626-4. Length and width, 45/i.

15. Paratype, USGS diatom catalog 3626-41. Length and width, 43/t.

16. Paratype, USGS diatom catalog 3626-20. Length and width, 39,u.

17. Paratype, USGS diatom catalog 3626-31. Length and width, 41/i. 

18, 19. Fragilaria brevistriata Grunow (p. All).

18. USGS diatom catalog 3627-5. Length, 35/i.

19. USGS diatom catalog 3405-12. Length, 48/*. 

20, 21. Fragilaria gigantea Lauby (p. All).

20. USGS diatom catalog 3405-31. Length, 100/i.

21. USGS diatom catalog 3405-71. Length, 89/*.

22. Synedra rumpens Kiitzing (p. A12).

USGS diatom catalog 3625-4. Length, 35/*.

23. Synedra ulna (Nitzsch) Ehrenberg (p. A12). 

USGS diatom catalog 3624-27. 

Estimated complete length, about 216/*.

24. Eunotia parallela Ehrenberg (p. A12).

USGS diatom catalog 3405-86. Length, 83/*.

25. Eunotia pectinalis var. minor (Kiitzing) Rabenhorst (p. A12).

USGS diatom catalog 3405-37. Length, 38/i. 

26, 27. Achnanthes hungarica (Grunow) Grunow (p. A13). 

USGS diatom catalog 3625-20. Length, 20/*.

26. Raphe valve.

27. Pseudoraphe valve.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 683-A PLATE 1

19 20 24 

MELOSIRA, TETRACYCLUS, FRAGILARIA, SYNEDRA, EUNOTIA, AND ACHNANTHES
PLATE 2

[All figures X 960]

FIGURE 1. Stauroneis phoenicenteron (Nitzsch) Ehrenberg (p. A13). 

USGS diatom catalog 3405-90. Length, lllfi.

2. Stauroneis anceps Ehrenberg (p. A13).

USGS diatom catalog 3405-24. Length, 38/i.

3. Stauroneis smithii Grunow (p. A13).

USGS diatom catalog 3626-36. Length, 26/i. 

4-6. Stauroneis lauenburgiana Hustedt (p. A14).

4. USGS diatom catalog 3626-1. Length, 40/i.

5. USGS diatom catalog 3626-25. Length, 48/i.

6. USGS diatom catalog 3626-38. Length, 48/i.

7. Anomoeoneis sphaerophora (Ehrenberg) Pfitzer (p. A14). 

USGS diatom catalog 3626-32. Length, 42/i.

8. Neidium iridis var. ampliata (Ehrenberg) Cleve (p. A14) 

USGS diatom catalog 3626-39. Length, 82/i.

9. Navicula amphibola Cleve (p. A14).

USGS diatom catalog 3405-68. Length, 53/i. 

10, 11. Navicula niobrara Andrews, n. sp. (p. A15).

10. Holotype, USGS diatom catalog 3626-29. Length, 104^.

11. Paratype, USGS diatom catalog 3626-33. Length, 110/i. 

12, 13. Navicula actinota Andrews, n. sp. (p. A15).

12. Holotype, USGS diatom catalog 3626-11. Length, 51/i.

13. Paratype, USGS diatom catalog 3626-34. Length, 57/i.

14. Navicula bacillum Ehrenberg (p. A16).

USGS diatom catalog 3405-93. Length, 45]u.

15. Navicula radiosa Kiitzing (p. A16).

USGS diatom catalog 3625-15. Length, 38/i.

16. Navicula graciloides A. Mayer (p. A16).

USGS diatom catalog 3405-94. Length, 41/i.

17. Navicula anglica var. subsalsa (Grunow) Cleve (p. A16). 

USGS diatom catalog 3624-23. Length, 25/i.

18. Navicula elginensis (Gregory) Ralfs (p. A17). 

USGS diatom catalog 3623-4. Length, 29/i.

19. Navicula elginensis var. rostrata (A. Mayer) Patrick (p. A17) 

USGS diatom catalog 3405-60. Length, 34/i.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 683-A PLATE 2

STAURONEIS, ANOMOEONEIS, NEIDIUM, AND NAVICULA
PLATE 3

[All figures X 960 except figs. 4, 5, 9, 10 which are X 475]

FIGURE 1. Pinnularia subcapitata var. paucistriata (Grunow) Cleve (p. A17). 

USGS diatom catalog 3623-11. Length, 27/z.

2. Pinnularia brevicostata Cleve (p. A17).

USGS diatom catalog 3405-91. Length, 53/z.

3. Pinnularia clevei Patrick (p. A17).

USGS diatom catalog 3625-39. Length, 113/z. 

4, 5. Pinnularia torta (Mann) Patrick (p. A18).

4. USGS diatom catalog 3405-8. Length, 196/z.

5. USGS diatom catalog 3626-13. Length, 184/z.

6. Pinnularia viridis (Nitzsch) Ehrenberg (p. A18). 

USGS diatom catalog 3405-54. Length, 106/z.

7. Cymbella naviculiformis Auerswald (p. A18). 

USGS diatom catalog 3405-25. Length, 35/z.

8. Cymbella ehrenbergii Kutzing (p. A18).

USGS diatom catalog 3405-66. Length, 54/x.

9. Cymbella cistula (Hemprich) Grunow, (p. A19). 

USGS diatom catalog 3405-95. Length, 131/x.

10. Cymbella cistula var. maculata (Kutzing) Van Heurck (p. A19). 

USGS diatom catalog 3405-96. Length, 101/x.

11. Cymbella tumida (Brebisson) Van Heurck (p. A19).

USGS diatom catalog 3627-11. Length, 34/z. 

12-16. Gomphonema affine var. insignis (Gregory) Andrews, n. comb. (p. A20).

12. USGS diatom catalog 3625-37. Length, 29/z.

13. USGS diatom catalog 3405-65. Length, 43/x.

14. USGS diatom catalog 3625-21. Length, 44/x.

15. USGS diatom catalog 3405-80. Length, 52/z.

16. USGS diatom catalog 3405-15. Length, 66/z. 

17-20. Nitzschia calva Andrews, n. sp., X 960 (p. A21).

17. Holotype, first valve, USGS diatom catalog 3626-43. Length, 76/z.

18. Holotype, second valve, USGS diatom catalog 3626-43. Length, 76/z.

19. Paratype, one valve, USGS diatom catalog 3626-37. Length, 70<u.

20. Paratype, whole frustule, USGS diatom catalog 3626-37. Length, 70/z.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 683-A PLATE 3

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PINNULARIA, CYMBELLA, GOMPHONEMA, AND NITZSCHIA