TD 77* 7* O 1 " J

rseudoleperditta ocnneider, 

1956 (Ostracoda, Crustacea),

an Early Mississippian Genus 

From Southwestern Nevada

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-C
Pseudokperditia Schneider, 

1956 (Ostracoda, Crustacea), 

an Early Mississippian Genus 

From Southwestern Nevada

By I. G. SOHN

CONTRIBUTIONS TO PALEONTOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-C

Redefinition of the genus, 

based on Pseudoleperditia poolei n. sp., 

the youngest described representative of 

the Paleozoic Eeyrichicopina

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 30 cents (paper cover)
CONTENTS

Abstract-- _ ________

Introduction _______

Register of localities. 

Age of the species_ 

Silicification_ _____

Page

Cl

1

1

1

2

Dimorphism _________________

Systematic descriptions.- _______

Suborder ?Beyrichicopina__.

Genus Pseudoleperditia.

References cited-_____________

Page 

02 

3 

3 

3 

5

ILLUSTRATIONS

[Plate follows references]

PLATE 1. Pseudoleperditia poolei.

FIGURE 1. Index map of southern Nevada, showing the collecting localities-__. 

2. Length-height plot of right and left valves of Pseudoleperditia poolei.

Page

C2

5

CONTRIBUTIONS TO PALEONTOLOGY

PSEUDOLEPERDITIA SCHNEIDER, 1956 (OSTRACODA, CRUSTACEA), AN EARLY 

MISSISSIPPIAN GENUS FROM SOUTHWESTERN NEVADA

By I. G. SOHN

ABSTRACT

Pseudoleperditia Schneider, 1956, described from the Tournaisian of Russia, is redefined. Silicified specimens from the Narrow 

Canyon and lower Mercury Limestones in southwestern Nevada, 

representing growth stages and adults of P. poolei n. sp., demonstrate that the genus is dimorphic and asymmetrical with regard to the anterior spines. This genus is the first known Early 

Mississippian representative of the Beyrichicopina, which formerly was restricted to rocks of early Paleozoic age.

INTRODUCTION

The presence of a new species of the Early Mississippian (Tournaisian) genus Pseudoleperditia Schneider, 

1956, in southwestern Nevada, as silicified specimens in 

the Narrow Canyon Limestone and the Mercury Limestone, is significant for the following reasons: It aids 

in the age determination of the North American rocks, 

and, because of its abundance and mode of preservation, 

the new species clarifies the identity of the previously 

monotypic genus, which is the end member of a Paleozoic 

group of dimorphic genera in the Beyrichicopina.

I am grateful to the following U.S. Geological Survey 

colleagues: F. G. Poole and Mackenzie Gordon, Jr., for 

taking me to the outcrops in Nye and Clark Counties, 

Nev., in October 1966, where all but one of the collections were made. In 1965, these men collected the sample 

of Narrow Canyon Limestone (USGS colln. 22446) 

that demonstrated the presence of silicified ostracodes in 

the unit. Jean M. Berdan aided materially by discussions and critical review of the paper. The photographs 

are by Robert H. McKinney, and the plate was composed by Elinor Stromberg.

REGISTER OF LOCALITIES

USGS loc. 

No.

Field 

No.

22446-PC 65G26

Description of locality, stratigrapJiic position, 

collector, and date

North slope of Timpi Canyon at lat 

36°38'06" N.; long 115°57'14" W., 

Mercury 7%-minute quadrangle, Nye 

County, Nev. (fig. 1, loc. 3). Lowest 

limestone bed of Narrow Canyon 

Limestone exposed above fault, 70 to 

75 feet below the top of the formation. 

Collected by Mackenzie Gordon, Jr., 

and F. G. Poole, Sept. 17 and 18, 

1965.

USGS loc. 

No.

Field 

No.

12866-PC 10/30/2

12867-PC 10/30/3

12872-PC 10/30/7

Description of locality, stratigrapJiic position, 

collector, and date

West Sandy Wash, Spotted Eange, 

Mercury 7>{-minute quadrangle, Nye 

County, Nev. (fig. 1, loc. 2). Knotty, 

argillaceous limestone 6 to 7 feet thick, 

85 feet below the top of the Narrow 

Canyon Limestone. Collected by Mackenzie Gordon, Jr., F. G. Poole, and 

I. G. Sohn, Oct. 30, 1966.

West Sandy Wash, Spotted Range, 

Mercury 7^-minute quadrangle, Nye 

County, Nev. (fig. 1, loc. 2). Limestone 6 inches thick, 15 feet above 

USGS locality 12866-PC, or 70 

feet below the top of the Narrow 

Canyon Limestone. Collected by 

Mackenzie Gordon, Jr., F. G. Poole, 

and I. G. Sohn, Oct. 30, 1966.

West Sandy Wash, Spotted Fange, 

Mercury 7K-minute quadrangle, Nye 

County, Nev. (fig. 1, loc. 2). Limestone, 5-foot bed near top of Narrow 

Canyon Limestone. Collected by 

Mackenzie Gordon, Jr., F. G. Poole, 

and I. G. Sohn, Oct. 30, 1966.

West Sandy Wash, Spotted Fange, 

Mercury 7K-minutes quadrangle, Nye 

County, Nev. (fig. 1, loc. 2). Mercury 

Limestone, approximately 21 feet 

above the base. Collected by Mackenzie Gordon, Jr., F. G. Foote, and 

I. G. Sohn, Oct. 30, 1966.

Narrow Canyon Wash, approrimate 

lat 36°42'10" N.; long 115°53'27" W., 

Mercury 1}{ -minute quadrangle, 

Clark County, Nev. (fig. 1, loc. 1). 

Type locality of the Narrow Canyon 

Limestone, 4-foot limestone bed, 152 

feet above the base of the foriration. 

Collected by Mackenzie Gordon, Jr., 

F. G. Poole, and I. G. Sohn, O^t. 31, 

1966.

AGE OF THE SPECIES

The Narrow Canyon Limestone was originally described as u Upper Devonian and Lower Mississippian" 

(Johnson and Hibbard, 1957, p. 356). At the type-locality (fig. 1, loc. 1), the formation is 175 feet thick and 

consists of dark-gray silty limestone that weathers into

Cl

12875-PC 10/30/12

12879-PC 10/31/5
C2 CONTRIBUTIONS TO PALEONTOLOGY

thin buff-colored plates which form talus slopes. No 

fossils were recorded in the original description of the 

formation; later, however, Poole, Houser, and Orkild 

(1961, p. D108) recorded the linguloid brachiopod 

Barroisetta and dictyospongid fragments and spicules. 

More recently, Poole and others (1967, p. 885) considered the Narrow Canyon Limestone to be Early Mississippian (Kinderhookian) because of the presence of 

the conodont Siphonodetta sp. The Mercury Limestone 

overlies the Narrow Canyon Limestone with a gradational contact. Johnson and Hibbard (1957, p. 356) described this unit as cherty crinoidal limestone that forms 

resistant ledges and is dark gray, buff weathering, and 

poorly bedded. The Mercury Limestone is incomplete 

at the type-locality where 115 feet is exposed below a 

fault. The megafossils were reported to be- similar to 

those of the Tin Mountain Limestone nearby in the 

Funeral Mountains, Calif, (fig. 1, loc. 4).

S MINERAL

- V ^

\ 

)\

' \

 /ESMERALDA N * E

^

\

\!

EXPLANATION \ oBeatty

\ 2

1 Narrow Canyon N 3

2 West Sandy Wash 4»\ 

\ 

3 Timpi Canyon v

4 Funeral Mountains

0

1

5n 100 MILES 

1 1

1

' "~~~i

i i

ri

LINCOLN

1 

1 !

jU CLARK

* ° Indian "M I 

. Springs Lnke j< 1 Meadjl 1

4 Vegas ~^^r\/L

i NSM

FIGUEE 1. Index map of southern Nevada, showing the 

collecting localities.

Both units contain abundant poorly silicified ostracodes that are similar on the generic level; they have 

some species in common, including the new species. 

Based on the classification in Moore (1961), a preliminary list of ostracodes for those units contains representatives of the following families: Aechminellidae, 

Kirkbyellidae, Hollinidae, Kirkbyiclae, Amphissitidae, 

Beyrichiopsidae, Paraparchitidae, Bairdiidae, Berounellidae, and Quasillitidae. Additional genera, some of 

which are new, are not yet classified on the family level. 

The genera are similar to an undescribed silicified assemblage from the Tin Mountain Limestone of California, considered by Poole and others (1967, p. 885) 

as equivalent in age to the Narrow Canyon Limestone. 

These genera resemble also the ostracodes described

from the Banff Formation, Alberta, Canada, of early 

Osagean and Kinderhookian age (Green, 1963). The 

Tin Mountain Limestone and Banff Formation, however, do not contain Pseudoleperditm Schneider, 1956. 

This genus was described from the Tournaisian of Eussia. The new species described in this paper is Early 

Mississippian (Kinderhookian).

SILICIFICATION

The term "silicification," as applied to fossil shells 

obtained by dissolving limestone with dilute, acid, does 

not necessarily imply that the entire shell was replaced 

by silica. If silica or some other acid-insoluMe mineral 

replaces the outermost and innermost layers of the shell 

on the molecular level, the shell body between these 

replaced layers may become protected frcm further 

replacement and also may be protected from solution 

by acid. Thus, a perfect replica of a fossil that may 

consist mostly of acid-soluble minerals may be recovered when the matrix is dissolved. In other shells, impurities may retard their rate of solution by acid in 

relation to that of the limestone matrix, and fossils may 

therefore be recovered. The danger of dealing with 

silicified fossils, particularly microfossils, is that differential replacement or solution may create artifacts 

which have no morphologic meaning. The best example 

of artifacts is the formation of beekite (Wickes, 1910).

The silicified ostracodes in the Narrow Canyon and 

Mercury Limestones were preserved mostly because of 

replacement by silica of the outer surface of the shells 

and only rarely also of the interior surface (pi. 1, figs. 

22, 27, 33, 35). The replacement was confirmed by treating a specimen with hydrofluoric acid (Sohn, 1956) ; 

the acid completely dissolved the specimen in 24 hours. 

Had the fossil contained calcium carbonate, it would 

have been converted to fluoride. The new species, 

Pseudoleperditia poolei, has hollow spine? near the 

cardinal angles. These spines may have been hollow in 

the living animal, or the hollow may be an r.rtif act due 

to incomplete replacement by silica.

DIMORPHISM

Jaanusson and Martinsson (1956, p. 402) introduced 

the terms "heteromorph" and "tecnomorph" to describe 

fossil ostracodes because sex determination based on 

soft parts and appendages is not feasible. Heteromorphs are those individuals that have dimorphic 

structures, which may be interpreted to indicate females ; tecnomorphs are adult and preadult individuals 

that do not have the dimorphic structures and may 

represent either the adult males or immature females. 

Jaanusson (1957, p. 190,197) distinguished three major 

groups of dimorphic Palaeocopida: (1) beyrichiid
PSEUDOLEPERDITIA, EARLY MISSISSIPPIAN GENUS, SOUiTHWESTERN NEVADA C3

type characterized by a distinct swelling of the anteroveiitral or ventral part of the carapace in heteromorphs, (2) kloedenellid type characterized by a 

greater width in the posterior part of the heteromorphs, 

and (3) velar or histial type characterized by certain 

adventral ornamental extensions of the valves of 

heteromorphs. A more recent discussion of dimorphism 

in ostracodes is in Becker (1968a, b). The new species described in this paper has the beyrichiid type of 

dimorphism.

Beyrichiid dimorphism was hitherto unknown in 

ostracodes younger than the Devonian and was a convenient criterion for dividing ostracodes of early Paleozoic age from younger forms. The discovery of 

ostracodes that have beyrichiid dimorphism in Lower 

Mississippian rocks serves as a warning against the 

uncritical use of beyrichiid dimorphism as an indication of stratigraphic age.

SYSTEMATIC DESCRIPTIONS

Suborder ?BEYRICHICOPINA Scott, 1961

Superfamily Uncertain

Family Uncertain

Pseudoleperditia was questionably assigned to the 

Primitiidae Ulrich and Bassler, 1923, by Schneider 

(1956, p. 87) when she originally described the genus. 

Later, Zanina, Neckaja, and Polenova (1960, p. 304) 

tentatively referred this genus to the subfamily Euprimitiinae Hessland, 1949, in the Primitiidae. By 

working from the literature, I (Sohn, 1961, p. Q184) 

questionably referred this genus to the Geisinidae Sohn, 

1961. The discovery of silicified specimens of Pseudoleperditia in collections from the Narrow Canyon and 

lower Mercury Limestones (Lower Mississippian) of 

Nevada clarified many of the characters of this genus, 

including its suprageneric affinities. The type of dimorphism and the large size, 1 mm (millimeter) to more 

than 2.5 mm in greatest length, exclude this genus from 

the Geisinidae.

My colleague, Jean M. Berdan, correctly pointed out 

to me the familial affinities of Pseudoleperditia and the 

Early Devonian genus Myomphalus Swartz and Whitmore, 1956. According to her, these and several additional early Paleozoic genera may belong to an as yet 

imdescribed family.

Genus PSEUDOLEPERDITIA Schneider, 1956 

Pseudoleperditia Schneider, 1956, VSEGEI Materialy, p. 87.

Type-species (original designations) P. tuberculifera Schneider, 1956 (p. 87, pi. 22, figs, la, b). Tournaisian, northeastern Eussian Platform.

Diagnosis. Large, straightbacked, essentially unisulcate, dimorphic ostracodes that have a subdued preadductorial lobe in front of the sulcus; large single spines 

at or near the dorsoanterior and dorsoposterior angles 

of the right valve, and only one spine near the dorsoposterior angle of the left valve. Crumina does not inflate; rounded, fairly obscure velar bend. Tongue and 

groove hinge, left valve overlaps slightly on free margins, fits into groove along hinge margin. A narrow 

calcified inner lamella along free margins of both v?lves. 

An adductor-muscle scar that is drop shaped and consists of multiple flecks is at the base of the sulcus.

Description. The following is a translation of the 

original diagnosis and discussion (Schneider, 1956, 

p. 87):

Large sized shell, up to 1.50 mm long and 1.00 mm high; subrectangular form, almost equivalved, relatively convex. Anterior 

and posterior ends widely rounded, forming with the straight 

dorsal margin almost right angles. Ventral margin convex, 

transition to end margins arc-like. Convexity of valves eoually 

developed in middle part, less convex on terminal ends. In the 

mid-dorsal part or in the center of both valves there is developed 

a rounded relatively large node, behind which there is a shallow 

transverse sulcus of loop-like shape. The surface is smooth or 

sometimes pitted. The anterior and posterior dorsal angles have 

clearly visible single spines, occasionally absent on one of the 

angles.

Distinguishing features of the genus. The genus Pseudoleperditia is characterized by distinct systematic features which 

differentiate it from the other known Paleozoic genera. It ir most 

similar to Leperditia in the following features: straight dorsal 

margin, presence of anterior and posterior dorsal angles, smooth 

or finely punctuate surface. It differs in the presence of a distinct transverse median sulcus, in front of which there is developed a large rounded node, and the presence of anterior and 

posterior dorsal spines.

Discussion. Schneider (1956) stated that the typespecies was based on "well preserved carapaces and 

single valves." Because the largest specimen of the typespecies is less than 2 mm in greatest length, and the 

dimorphism observed in the new species is in specimens 

2 mm long or larger, that feature may not have been 

noted by Schneider. In more than 50 silicified specimens 

of the new species from five collections, I saw no indication of an anterior dorsal spine on any of the 23 left 

valves or the left valves of the four carapaces. This observation, plus the fact that Schneider's illustration of 

a carapace in dorsal view (1956, pi. 22, fig. Ib) charly 

indicates that there is no dorsoanterior spine on the 

left valve of the type-species, are evidence that the 

genus is asymmetrical with regard to dorsoanterior 

spines. Whether reversal of overlap and hingement 

occurs in this genus remains to be seen. The preserce of 

a structure tentatively interpreted as a rudimentary 

inner lamella (pi. 1, figs. 19, 27, 33, 35) may be significant and is the reason for the uncertain suprageneric 

classification.
C4 CONTRIBUTIONS TO PALEONTOLOGY

Blumenstengel (1968, p. 194) illustrated, but did not 

identify, a silicified right valve from the Upper Devonian of Thuringia that probably belongs to 

Pseudoleperditia.

This genus was misinterpreted when it was questionably referred to the Geisinidae (Sohn, 1961, p. Q184).

Strati.graphic range. Upper Devonian (?), Lower 

Mississippian (Tournaisian).

Ecology. Marine.

Pseudoleperditia Foolei Sohn, n. sp. 

Plate 1, figures 1-35

Name. In honor of F. G. Poole, U.S. Geological 

Survey, with whom the collections that contain this 

species were made.

Holotype. USNM 163510.

Paratypes. USNM 163511-163537.

Material. More than 50 carapaces, valves, and fragments representing various stages of growth, from five 

collections in three localities.

Type-locality. Type-locality of the Narrow Canyon 

Limestone, in Narrow Canyon Wash, approximate lat 

36°42'10" N.; long 115°53'27" W., Clark County, Nev.

Type-level. Limestone, 4 feet thick, 152 feet above 

the base of the Narrow Canyon Limestone (USGS loc. 

12879-PC).

Diagnosis. Differs from P. tiiberculifera Schneider, 

1956, in that the subcentral node and sulcus do not extend below the midheight of the valve. Another difference from P. tiiberculifera is that the dorsoanterior 

spine of the right valve is so close to the corner in lateral 

outline that the anterior margin in most specimens appears to continue in an unbroken line with the front end 

of the spine.

Description. The anterior spine on the right valve 

extends dorsally above the hinge line and trends more 

toward the top than toward the side; the distance between the dorsoanterior corner and the spine is less 

than the diameter of the base of the spine. The posterior 

spines are symmetrically placed near the dorsoposterior 

corner of each valve; they are equidistant from the dorsal and posterior margins by approximately the width of 

the base of the spine. These posterior spines trend laterally ; they have a slight upward curve so that the ends of 

the spines are above the hinge margins. On a few specimens, the posterior spine curves slightly backward so 

that it covers the posterior cardinal angle, and on at 

least one valve the spine bends slightly forward so 

that the posterior cardinal angle is exposed in lateral 

view. The direction in which these spines point varies 

with individuals.

Specimens 2 mm or larger in greatest length have 

beyrichiid dimorphism; the heteromorph has a broad

Fig. No. (pi. 1) or USNM No.

l._ ._. -..... __.- . f>

3...- ...... .......................

4....................................

5 ......... ....... . ...............

6.-...--...-.-..--.----...-.-..-.

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

163532A. . ... ......................

9......................................

10 _ ... .

11... ...... ...... ....... .. 

12-14..... ....... ...... .............

163532B. ...... .......... .......... ...... ....

15, 16. ...................... ............

17-19 (holotype). _ ... . .- .

20-22 ... .... ...... ... 

23, 24. - .- ...

163533...--.......--..--....-----....--...

25..... .................................

26 --. .-.---.--.. ------------

27,28 . 

29-31. ............ ...... . .

Maximum 

length 

(parallel to 

dorsal 

margin)

O en

60

.75

90

94

1.07

.... 1.12

.... 1.44

1.47

1.46

1.73

1 74

1.78

..-- 1.83

2.13

2.27

--.- 2.06

2.07

2 22

2.10

2.30

2.52

Maximum 

height 

(normal to 

dorsal 

margin)

0.32

.37

.45

.56

.60

.68

.76

.92

.95

1.05

1.11

1.09

1.08

1.17

1.38

1.43

1.28

1.23

1.39

1.33

1.45

1.65

anteroventral swelling that is not present in smaller 

specimens and adult tecnomorphs. The ventral surface 

of the crumina is smooth.

Measurements (in mm] of paratypes, unless stated 

otherwise. 

Disc-u-ssio-n. In addition to the illustrated specimens,

1 measured six right valves and 12 left valves. Figure

2 shows the size distribution of the measured specimens; 

the range in greatest length is from 0.50 mm to 2.52 mm, 

and fragments indicate that even larger individuals 

may have existed. Growth stages cannot be discerned 

on this diagram. The specimens illustrated on plate 1 as 

figures 32-35 were not measured because they are broken 

valves.

Although some of the adhering silica grains and 

smaller ostracodes were removed with a fine needle, several specimens were broken in the process; consequently, 

adhering matter was not removed from all the illustrated 

specimens (pi. 1, figs. 1, 3, 10, 14, 15, 22, 28). Silicification of parts of the inner shell layers is illustrated on 

plate 1, figures 22, 27, 33, 35. The adductor muscle scar 

that is drop shaped and consists of multiple flecks is 

shown on plate 1, figures 11,18,24, 26 and 32.

Blumenstengel (1968, p. 194, fig. 2) illustrated an 

imdescribed Late Devonian assemblage of silicified 

ositracodes from a borehole, "Bohrung Mandelholz 

18/65," in Thuringia, Germany. The third specimen 

from the top near the right margin of the figure appears 

to be the right valve of a Pseudoleperditia on which the 

dorsoposterior spine was broken. If my identification 

of the photograph is correct, the Late Devonian specimen differs from P. tiiberculifera Schneic1 er and P. 

poolei n. sp. in lateral outline and in that its dorsoposterior spine is a greater distance in front of tlie posterior 

cardinal angle than are those of the two known species.
PSEUDOLEPERDITIA, EARLY MISSISSIPPIAN GENUS, SOUTHWESTERN NEVADA C5

1.7 

1.6 

1.5 

1.4 

1.3 

1.2

v> i i cc 1.1

LJ 

LU

| 1.0 

i 0.9

EXPLANATION

 

Right valve

x

Left valve

 

Holotype

X

X 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6

LENGTH (MILLIMETERS) 

FIUTJEE 2. Length-height plot of right and left valves of Pseudoleperditia poolei n. sp.

Based on the Thuringian specimen, the stratigraphic 

range of the genus is given as Upper Devonian (?) to 

Lower Mississippian.

Distribution. Rare in Narrow Canyon Limestone 

(USGS colln. 12866, 12867, and 12872); common in 

Narrow Canyon Limestone (USGS colln. 22446 and 

12879) and in lower Mercury Limestone (USGS colln. 

12875).

REFERENCES CITED

Becker, Gerbard, I968a, Geschlechtsdimorpkismus bei Ostracoden I: Natur u. Mus., v. 98, no. 2, p. 47-57, 6 text figs. 

 1968b, Geschlechtsdiniorphismus bei Ostracoden II:

Natur u. Mus., v. 98, no. 3, p. 119-132, 11 text figs. 

Blumenstengel, Horst, 1968, Die oberdevonischen Ostracoden

Thiiringens und ihre Beziehungen zu gleichaltrigen Ostracodenfaunen anderer Gebiete: Deutsche Gesell. geol. Wiss.

Ber., Reihe A, Geologie u. Palaontologie,, v. 13, no 2 p

191-198, 3 figs. 

Green, Robert, 1963, Lower Mississippian ostracodes from the

Banff Formation, Alberta: Research Council Alberta Bull

11, 237 p., 17 pis. 

Jaanusson, V<aldar, 1957, Middle Ordovician ostracodes of central

and southern Sweden: Uppsala Univ. Geol. Inst. Bull., v.

37, p. 173-422,15 pis.

Jaanusson, Valdar, and Martinsson, Anders, 1956, Two hoJlinid 

ostracodes from the Silurian Mulde Marl of Gotland: Uppsala Univ. Geol. Inst. Bull., v. 36, p. 401-410, 1 pi.

Johnson, M. S., and Hifobard, D. E., 1957, Geology of the Atomic 

Energy Commission Nevada Proving Grounds Area, Nevada : 

U.S. Geol. Survey Bull. 1021-K, p. 333-384, pis. 32, 33.

Moore, R. C., ed., 1961, Treatise on invertebrate paleontology 

Part Q, Arthropoda 3, Crustacea, Ostracoda: New York 

and Lawrence, Kans., Geol. Soc. America and Univ. Kansas 

Press, 442 p., 334 figs.

Poole, F. G., Baars, D. L., Drewes, Harald, Hayes, P. T., 

Ketner, K. B., McKee, E. D., Teichert, Curt, and Williams, 

J. S., 1967, Devonian of the Southwestern United States, 

in Volume 1 of Oswald, D. H., ed., International symposium 

on the Devonian System, Calgary, Alberta, Sept. 1967: Calgary, Alberta Soc. Petroleum Geologists, p. 879-912.

Poole, F. G., Houser, F. N., and Orkild, P. P., 1961, Eleana Formation of Nevada Test Site and vicinity, Nye County, 

Nevada: U.S. Geol. Survey Prof. Paper 424-D, p. D104- 

Dlll.

Schneider, G. F., 1956, Gen. Pseudoleperditia Schneider, gen. 

nov., in Kiparisova, L. D., Markovskii, B. P., and Radczenko, G. P., eds., Materialy po paleontologii; rovye 

semeistva i rody: Vses. Nauchno-Issled. Geol. Inst. 

(VSEGEI), Materialy, new ser., no. 12, Paleontolo-riya. 

p. 87, pi. 22.
C6 CONTRIBUTIONS TO PALEONTOLOGY

Sohn, I. G., 1956, The transformation of opaque calcium carbonate to translucent calcium fluoride in fossil Ostracoda: 

Jour. Paleontology, v. 30, no. 1, p. 113-114, pi. 25.

 1961, Family Geisinidae Sohn, n. fam., in Moore, R. C., 

ed., Treatise on invertebrate paleontology Part Q, Arthropoda 3, Crustacea, Ositracoda : New York and Lawrence, 

Kans., Geol. Soc. America and Univ. Kansas Press, p. 

Q182-Q184.

Swartz, F, M., and Whitmore, F. C., Jr., 1956, Ostracoda of the 

Silurian Decker and Manlius limestones in New Jersey

and eastern New York: Jour. Paleontology, v. 30, p. 1029- 

1091, pis. 103-110.

Wickes, W. H., 1910, Beekite: Bristol Naturalists ?oc. Proc., ser. 

4, v. 2, pt. 3, p. 11-21.

Zanina, I. E., Neckaja, A. I., and Polenova, E. N., 1960, Superfamily Beyrichiacea, in Tchernyslieva, N. E, ed., Osnovy 

paleontologii; Spravochnik dlya paleontologov i geologov 

SSSR [v. 8], Chlenistonogie, trilobitoobraznye i rakoobraznye [Arthropoda, Trilobitomorpha, and Crustacea] ; Moscow, Gosudar. Nauch.-Tekh. Izd. Lit. Geol. i Okhrane Nedr. 

515 p., 18 pis.
PLATE 1
PLATE 1

[Magnification approximately X 15]

FIGURES 1-35. Pseudoleperditia poolei Sohn, n. sp.

1. Lateral view of right valve, youngest growth stage available. From Narrow Canyon Limestone (fig. 1, loc. 2), 

USGS collection 12866; paratype, USNM 163511.

2. Lateral view of right valve, slightly larger growth stage. From lower Mercury Limestone (fig. 1, loc. 2), 

USGS collection 12875; paratype, USNM 163512.

3. Lateral view of right valve, slightly larger growth stage. From Narrow Canyon Limestone (fig. 1, loc. 3), 

USGS collection 22446; paratype, USNM 163513.

4. Lateral view of right valve, slightly larger growth stage. From lower Mercury Limestone (fig. 1, loc. 2), 

USGS collection 12875; paratype, USNM 163514.

5. Lateral view of right valve, possibly the same growth stage as fig. 4 above. From Narrow Canyon Limestone 

(fig. 1, loc. 2), USGS collection 12866; paratype, USNM 163515.

6. Lateral view of broken right valve, possibly the same growth stage as fig. 5 above. From Narrow Canyon 

Limestone (fig. 1, loc. 2), USGS collection 12867; paratype, USNM 163516.

7. 8. Dorsal and lateral views of right valve, slightly larger growth stage. From Narrow Canyon Limestone (fig. 

1, loc. 3), USGS collection 22446; paratype, USNM 163517.

9. Lateral right view of crushed carapace, slightly larger growth stage. From Narrow Canyon Limestone (fig. 

1, loc. 1), USGS collection 12879; paratype, USNM 163518.

10. Lateral view of broken right valve, possibly same growth stage as fig. 9 above. From Narrow Canyon 

Limestone (fig. 1, loc. 1), USGS collection 12879; paratype, USNM 163519.

11. Lateral view of right valve, slightly larger growth stage. Note adductor muscle-scar pattern that is drop

shaped and consists of multiple flecks. From Narrow Canyon Limestone (fig. 1, loc. 1), USGS collection

12879; paratype, USNM 163520. 

12-14. Right, left, and posterior views of carapace, same growth stage as above. The surface, including the

area of the posterior spines, is covered with adhering silica. From Narrow Canyon Limestone (fig. 1, loc. 1),

USGS collection 12879; paratype, USNM 163521. 

15, 16. Dorsal and lateral views of left valve. The lighter object below the posterior spine is an adhering silica

grain. From lower Mercury Limestone (fig. 1, loc. 2), USGS collection 12875; paratype, USNM 163522. 

17-19. Ventral, outside, and inside views of left valve of heteromorph. From Narrow Canyon Limestone (fig. 1,

loc. 1), USGS collection 12879; holotype, USNM 163510. 

20-22. Lateral, ventral, and inside views of right valve of tecnomorph. Note hinge and adductor muscle scar.

From Narrow Canyon Limestone (fig. 1, loc. 1), USGS collection 12879; paratype, USNM 163523. 

23, 24. Inside and outside views of right valve; posterior spine broken. From Narrow Canyon Limestone (fig. 1,

loc. 3), USGS collection 22446; paratype, USNM 163524.

25. Lateral view of left valve. From lower Mercury Limestone (fig. 1, loc. 2), USGS collection 12£75; paratype, 

USNM 163525.

26. Lateral view of right valve. Note adductor muscle scar. From Narrow Canyon Limestone (fig. 1, loc. 1), 

USGS collection 12879; paratype, USNM 163526.

27. 28. Inside and outside views of left valve of heteromorph. From Narrow Canyon Limestone (fig. 1, loc. 1),

USGS collection 12879; paratype, USNM 163527. 

29-31. Lateral, ventral, and dorsal views of right valve of heteromorph. From Narrow Canyon Limestone (fig. 1,

loc. 1); USGS collection 12879, paratype, USNM 163528. 

32, 33. Outside and inside views of a fragment of a very large left valve. Note that anterior is missing. From

Narrow Canyon Limestone (fig. 1, loc. 1); USGS collection 12879, paratype, USNM 163529.

34. Lateral view of broken right valve of heteromorph. From Narrow Canyon Limestone (fig. 1, loc. 1); USGS 

collection 12879, paratype, USNM 163530.

35. Inside view of broken right valve of heteromorph. From Narrow Canyon Limestone (fig. 1, loc. 1); USGS 

collection 12879, paratype, USNM 163531.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 643-C PLATE 1

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PSEUDOLEPERDITIA POOLEI