Midde Trias sic Molluscan Fossils

of iostratigraphic Significance

from the Humboldt Range,

Northwestern Nevada
Middle Triassic Molluscan Fossils 

of Biostratigraphic Significance 

from the Humboldt Range, 

Northwestern Nevada

By N. J. SILBERLING and K. M. NICHOLS

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207

Taxonomic and super positional documentation 

of an unusually complete faunal succession

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1982
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Silberling, Norman John, 1928-

Middle Triassic molluscan fossils of biostratigraphic significance from the Humboldt Range, northwestern Nevada.

(Geological Survey Professional Paper 1207)

Bibliography: p. 71

Supt. of Docs. No.: I 19.16: 1207

1. Mollusks, Fossil. 2. Paleontology Triassic 3. Geology, Stratigraphic Triassic. 4. Geology Nevada Humboldt Range.

I. Nichols, Kathryn Marion, 1946- joint author. II. Title. III. Series: United States. Geological Survey. Professional Paper 1207.

QE801.S64 564 80-607925

For sale by the Distribution Branch, U.S. Geological Survey 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Abstract ----------------------------------------

Introduction ------------------------------------

History -------------------------------------

Description of study and acknowledgments 

Stratigraphic occurrence and composition of faunas 

General statement ---------------------------

Lower Anisian ------------------------------

Middle Anisian -----------------------------

Upper Anisian ------------------------------

Lower Ladinian -----------------------------

Upper Ladinian -----------------------------

Age and correlation ------------------------------

Paleontology ----------------------------

Procedures and conventions ----------

Systematic descriptions --------------

Class Cephalopoda --------------

Subclass Ammonoidea -------

Genus Sageceras --------

Genus Koipatoceras -----

Genus Alanites ----------

Genus Ismidites ---------

Genus Amphipopanoceras 

Genus Humboldtites -----

Genus Paracrochordiceras 

Genus Cuccoceras -------

Genus Nicomedites ------

Genus Hollandites -------

Genus Anagymnotoceras - 

Genus Gymnotoceras ----

Genus Parafrechites -----

Genus Frechites ---------

Genus Paraceratites -----

Genus Eutomoceras -----

Genus Nevadites --------

Genus Hungarites -------

Genus Tropigymnites ----

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Paleontology Continued

Systematic descriptions Continued 

Class Cephalapoda Continued

Subclass Ammonoidea Continued 

Genus Japonites --------------

Genus Gymnites --------------

Genus Epigymnites ------------

Genus Sturia -----------------

Genus Discoptychites ----------

Genus Isculites ----------------

Genus Czekanowskites ---------

Genus Pseudodanubites --------

Genus Unionvillites ------------

Genus Lenotropites ------------

Genus Intorrdtes --------------

Genus Longobardites ----------

Genus Metadinarites ----------

Genus Aplococeras ------------

Genus Tropigastrites ----------

Genus Tozerites ---------------

Genus Thanamites ------------

Genus Proarcestes -------------

Genus Protrachyceras ----------

Genus Sirenites ---------------

Genus Ussurites ---------------

Genus Monophyllites ----------

Subclass Nautiloidea --------------

Genus Aulametacoceras --------

Genus Germanonautilus -------

Genus Grypoceras -------------

Genus Paranautilus -----------

Genus Michelinoceras ---------

Subclass Coleoidea ----------------

Genus Atractites --------------

Class Bivalvia ------------------------

Genus Pteria----------------------

Genus Daonella -------------------

References cited -------------------------------

Index ----------------------------------------

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ILLUSTRATIONS

[Plates 1-3 in pocket, 4-38 follow "Index"]

PLATE 1. Geologic map of part of the Humboldt Range, Nev., showing collecting-sites A, B, and C.

2. Locality map of collecting-site A on the south side of Fossil Hill, Humboldt Range, showing fossil localities.

3. Locality map of collecting-site C on the south spur of Saurian Hill, Humboldt Range, showing fossil localities.

4. Sageceras, Koipatoceras, and Acrochordiceras.

5. Acrochordiceras and Sageceras.

6. Hollandites, ^Anagymnotoceras, Nicomedites, Thanamites?, Amphipopanoceras, and Unionvillites.

7. Gymnotoceras.

8. Gymnotoceras.

9. Gymnotoceras and Frechites.

10. Frechites.

11. Frechites and Parafrechites.

m
IV CONTENTS

12. Parafrechites.

13. Parafrechites.

14. Frechites.

15. Frechites and Paraceratites.

16. Paraceratites.

17. Paraceratites.

18. Eutomoceras.

19. Eutomoceras, Pseudodanubites, and Czekanowskites.

20. Cuccoceras, Hungarites, and Intornites.

21. Intornites, Longobarbites, Metadinarites, and Aplococeras.

22. 'Aplococeras and Nevadites.

23. Nevadites.

24. Nevadites and Protrachyceras.

25. Protrachyceras and Sirenites.

26. Tropigymnites and Tropigastrites.

27. Tozerites and Proarcestes.

28. Proarcestes, Humboldtites, Isculites, Ismidites, and Alanites.

29. Paracrochordiceras, Isculites, Lenotropites, and Alanites.

30. Isculites, Gymnites, and Sturia.

31. Gymnites, Aulametacocerasf and Epigymnites.

32. Monophyllites, Ussurites, Germanonautilus, Paranautilus, and Grypoceras.

33. Michelinoceras? and Airaciites.

34. Atractites.

35. Daonella.

36. Daonella.

37. Daonella.

38. Daonella and Pteriaf

Page

FIGURE 1. Index map showing the Humboldt Range ----------------------------------------------------------------------- 2

2. Photograph showing view south across South American Canyon towards Fossil Hill -------------------------------- 2

3. Photograph showing view northwest towards collecting-site A on the south side of Fossil Hill ----------------------- 6

4. Photograph showing view southeast across collecting-site C on the south spur of Saurian Hill ----------------------- 6

5. Correlation chart showing the stage and substage assignments of Middle Triassic biostratigraphic units-------------- 12

6. Frequency distributions of morphologically different variants within single species of ammonites -------------------- 14

7-18. Drawings of suture lines of:

7. Koipatoceras discoideus ------------------------------------------------------------------------------ 18

8. Alanites mulleri -------------------------------------------------------------------------------------- 19

9. Alanites obesus -------------------------------------------------------------------------------------- 20

10. Ismidites aff. /. marmarensis -------------------------------------------------------------------------- 20

11. Amphipopanoceras cf. A. selwyni ---------------------------------------------------------------------- 21

12. Humboldtites septentrionalis -------------------------------------------------------------------------- 21

13. Acrochordiceras hyatti -------------------------------------------------------------------------------- 23

14. Acrochordiceras cf. A. carolinae ----------------------------------------------------------------------- 23

15. Cuccoceras bonaevistae ------------------------------------------------------------------------------- 24

16. Nicomedites sp. -------------------------------------------------------------------------------------- 24

17. Hollandses aff. #. uoiiz ------------------------------------------------------------------------------ 25

18. Frechites johnstoni ----------------------------------------------------------------------------------- 31

19. Scatter diagram comparing width between ventral spines to whorl height in population samples of Nevadites ------- 37

20-23. Drawings of suture lines of:

20. Gymnites tregorum ----------------------------------------------------------------------------------- 40

21. Gymnites perplanus ---------------------------------------------------------------------------------- 40

22. Gymnites cf. G. humboldti --------------------------------------------------------------------------- 40

23. Discoptychites sp.------------------------------------------------------------------------------------ 42

24. Diagrammatic cross section of Discoptychites sp.--------------------------------------------------------------- 42

25-26. Drawings of suture lines of:

25. Isculites meeki --------------------------------------------------------------------------------------- 43

26. Isculites tozeri --------------------------------------------------------------------------------------- 43

27. Scatter diagram comparing Isculites tozeri with /. meeki -------------------------------------------------------- 44

28-43. Drawings of suture lines of:

28. Pseudodanubites halli -------------------------------------------------------------------------------- 45

29. Unionvillites asseretoi -------------------------------------------------------------------------------- 46

30. Lenotropites caurus ---------------------------------------------------------------------------------- 46

31. Intornites mctaggarti --------------------------------------------------------------------------------- 48

32. Intornites nevadanus --------------------------------------------------------------------------------- 49

33. Longobardites parvus --------------------------------------------------------------------------------- 50
CONTENTS

Page

34. Longobardites zsigmondyi----------------------------------------------------------------------------- 51

35. tMetadinarites desertorus ----------------------------------------------------------------------------- 52

36. Aplococeras smithi ----------------------------------------------------------------------------------- 53

37. Aplococeras vogdesi ---------------------------------------------------------------------------------- 53

38. Aplococeras paruus ----------------------------------------------------------------------------------- 53

39. Tropigastrites louderbacki ---------------------------------------------------------------------------- 54

40. Tozerites gemmellaroi -------------------------------------------------------------------------------- 55

41. Tozerites humboldtensis ------------------------------------------------------------------------------ 56

42. Proarcestes cf. P. balfouri ----------------------------------------------------------------------------- 57

43. Proarcestes gabbi ------------------------------------------------------------------------------------ 57

44. Scatter diagram comparing shell width to diameter for Proarcestes gabbi ----------------------------------------- 58

45-47. Drawings of suture lines of:

45. Sirenites homfrayi ----------------------------------------------------------------------------------- 59

46. Ussurites cf. U. arthaberi ----------------------------------------------------------------------------- 60

47. Monophyllites cf. M. agenor -------------------------------------------------------------------------- 61

48. Siphuncular structure of Atractites ---------------------------------------------------------------------------- 65

49. Diagrammatic sketch of the right valve of a Daonella ----------------------------------------------------------- 67

TABLES

TABLE 1. Stratigraphic distribution of upper Anisian ammonoids, coleoids, and Daonellas at Fossil Hill and vicinity - - - - 8

2. Correlation of upper Anisian and lower Ladinian localities at collecting-sites A, B, and C in the vicinity of Fossil

Hill and Saurian Hill ------------------------------------------------------------------------------- 10

3. Triassic fossil localities in the Humboldt Range and vicinity ------------------------------------------------- 15

4. Morphologic comparison of longobarditinids from Nevada --------------------------------------------------- 47

MIDDLE TRIASSIC MOLLUSCAN FOSSILS OF BIOSTRATIGRAPHIC 

SIGNIFICANCE FROM THE HUMBOLDT RANGE, 

NORTHWESTERN NEVADA

By N. J. SILBERLING and K. M. MCHOLS

ABSTRACT

Cephalopods and bivalves of the genus Daonella occur at certain 

levels throughout the Middle Triassic section in the Humboldt Range, 

northwestern Nevada. These fossiliferous strata are assigned to the 

Fossil Hill Member and upper member of the Prida Formation, which 

here forms the oldest part of the Star Peak Group. The distribution and 

abundance of fossils within the section is uneven, partly because of 

original depositional patterns within the dominantly calcareous succession and partly because of diagenetic secondary dolomitization and 

hydrothermal metamorphism in parts of the range.

Lower and middle Anisian fossil localities are restricted to the 

northern part of the range and are scattered, so that only three 

demonstrably distinct stratigraphic levels are represented. 

Cephalopods from these localities are characteristic of the Caurus Zone 

and typify the lower and upper parts of the Hyatti Zone, a new zonal 

unit whose faunas have affinity with those from the older parts of the 

Varium Zone in Canada.

The upper Anisian and lowermost Ladinian, as exposed in the 

vicinity of Fossil Hill in the southern part of the range, are extremely 

fossiliferous. Cephalopod and Daonella shells form a major component 

of many of the limestone interbeds in the calcareous fine-grained 

clastic section here. Stratigraphically controlled bedrock collections 

representing at least 20 successive levels have been made from the Fossil Hill area, which is the type locality for the Rotelliformis, Meeki, and 

Occidentalis Zones of the upper Anisian and the Subasperum Zone of 

the lower Ladinian. Above the Subasperum Zone fossils are again 

scarce; upper Ladinian faunas representing the Daonella lommeli beds 

occur at only a few places in the upper member of the Prida Formation.

Although unevenly fossiliferous, the succession of Middle Triassic 

cephalopod and Daonella faunas in the Humboldt Range is one of the 

most complete of any known in the world. Newly collected faunas from 

this succession provide the basis for revising the classic monograph on 

Middle Triassic marine invertebrates of North America published in 

1914 by J. P. Smith and based largely on Stratigraphically uncontrolled 

collections from the Humboldt Range. Taxonomic treatment of these 

collections, old and new, from the Humboldt Range provides the 

documentation necessary to establish this Middle Triassic succession 

as a biostratigraphic standard of reference.

Of the 68 species of ammonites described or discussed, 4 are from the 

lower Anisian, 20 from the middle Anisian, 39 from the upper Anisian, 

4 from the lower Ladinian, and 1 from the upper Ladinian. A few additional ammonite species from other localities in Nevada are also 

treated in order to clarify their morphologic characteristics and 

stratigraphic occurrence. Other elements in the Middle Triassic molluscan faunas of the Humboldt Range comprise five species of 

nautiloids and three of coleoids from the middle and upper Anisian 

parts of the section. Eight more or less Stratigraphically restricted 

species of Daonella occur in the upper Anisian and Ladinian.

INTRODUCTION

HISTORY

The Humboldt Range in northwestern Nevada (fig. 1) 

has become a classic locality for Middle Triassic paleontology, partly because fossils of this age are locally abundant and partly because the area was favored by early 

collectors. By good fortune the most richly fossiliferous 

Middle Triassic beds in the northern part of the range 

are closely associated with silver deposits that in 1860 

caused one of the many flurries of mining excitement in 

western Nevada after the discovery of the Comstock 

Lode. Fossils found in the Humboldt Range by mining 

men near the boom towns of Unionville and Star City (of 

which little remains in Star Creek canyon) were acquired 

by the Geological Survey of California and described by 

W. M. Gabb in 1864. They were thus among the first 

marine invertebrates from the New World to be 

described from rocks of recognized Triassic age.

Additional collections of Middle Triassic fossils from 

the Humboldt Range were made during the years 

1867-69 by members of Clarence King's U.S. Geological 

Exploration of the Fortieth Parallel. These were 

described by Meek (1887) in collaboration with Alpheus 

Hyatt who subsequently visited and collected from the 

Humboldt Range in 1888 in company with I. C. Russell.

Middle Triassic Cephalopods from the Humboldt 

Range were included in an intended comprehensive 

study of the marine invertebrate faunas of the North 

American Triassic by Hyatt of Harvard University and 

James Perrin Smith of Stanford University. This study 

was brought to a preliminary conclusion by Smith after 

Hyatt's death and was published under the title of 

"Triassic cephalopod genera of America" by Hyatt and 

Smith in 1905. As part of this study, Smith first visited 

the Humboldt Range in 1902 and 1903, and he credited 

L. F. Dunn of Winnemucca, Nev., for directing him to 

the extremely rich Middle Triassic locality in the 

southwestern part of the range that came to be known as
MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

118°15' 118°

HUMBOLDT 

RANGE NORTHERN 

\ xEAST RANGE 

V,x* SOUTHERN 

I TOBIN RANGE 

* * FAVRET

^CANYON, 

; * AUGUSTA 

NEW PASS MOUNTAINS 

RANGE

Coyote and ~ 

John Brown 

Canyons 

Big Canyon

_ Vista 

O Unionville Creek and 

= Congress 

c Canyons

FIGURE 1. Index map showing the location of Fossil Hill and other 

pertinent place names within the Humboldt Range, Nev.

"Fossil Hill" (Merriam, 1908, pi. 1, fig. 1; Smith, 1914) 

(fig. 2). Collections from the Humboldt Range were 

basis for the monographic treatment of the "Middle 

Triassic marine invertebrate fauna of North America" 

published by Smith in 1914. In this publication 128 

species of marine invertebrates, including 110 species of 

ammonites, are described or listed from Fossil Hill 

alone.

Shortly after Smith drew attention to the richly fossiliferous Middle Triassic localities in the Humboldt 

Range, large collections were made from Fossil Hill by 

Percy Train, a professional collector. Although, according to his associates, Smith was quite dismayed at 

this commercial enterprise, Train was responsible for obtaining much of the Humboldt Range material studied 

by L. F. Spath (1934; 1951) at the British Museum of 

National History as well as the collections from the 

Humboldt Range to be found at many other institutions 

around the world.

FIGURE 2. View south across South American Canyon, Humboldt 

Range, towards Fossil Hill (left foreground). Saurian Hill is in right 

background.

While extensive collections of Middle Triassic fossils 

were being made from the Humboldt Range, study of the 

geologic and stratigraphic setting of this fauna was 

generally neglected. Until the studies were made by 

Cameron (1939) in the northern part of the Humboldt 

Range and by Ferguson, Muller, and Roberts (1951) in 

the East Range, the next range east of the Humboldt 

Range, knowledge of the Triassic section in this part of 

Nevada advanced little beyond the original survey made 

by the geologists of the Fortieth Parallel expedition 

(King, 1878). As the richly fossiliferous Middle Triassic 

beds in the Humboldt Range are rarely more than a few 

tens of meters thick at any one place, and as they are 

part of a Triassic section obviously more than a thousand meters thick, it is not surprising that the early collectors, including Smith, tended to regard all of the fossils from these beds throughout the range as part of a 

single fauna, and little or no effort was made to segregate 

collections made from different stratigraphic levels.

Most of the Middle Triassic fossils described by Smith 

(1914) from the Humboldt Range were regarded by him 

as representative of the "Daonella dubia zone." He was 

aware of some difference in age among the faunas of this 

zone as shown by statements such as "the upper Anisic 

stage is certainly represented . . ., and the higher beds of 

the Daonella dubia shaly limestone may represent the 

lower Ladinic" (Smith, 1914, p. 7). But the faunal associations listed by Smith commonly include species 

now known to be restricted to the middle Anisian or even 

in the lower Ladinian. Thus the nature of the faunal succession was largely obscured, which is unfortunate 

because the paleontologic significance of the Middle 

Triassic of the Humboldt Range lies not only in its 

highly fossiliferous nature but in the unusually complete 

stratigraphic sequence of its different faunas.

The succession of Anisian and lower Ladinian ammonite faunas in the Humboldt Range is, in fact, one of 

the most complete of any known in the world, and it
STRATIGRAPHIC OCCURRENCE AND COMPOSITION OF FAUNAS

provides an important biostratigraphic standard of 

reference for rocks of this age. Moreover, the almost continuously fossiliferous upper Anisian beds afford a 

unique opportunity for detailed study of the changes in 

ammonite populations through time and give considerable insight into the evolution and taxonomy of 

these fossils.

DESCRIPTION OF STUDY AND 

ACKNOWLEDGMENTS

The present study was commenced by Silberling in 

1956 and carried out at various times during the late 

1950's and early 1960's as part of a more general geologic 

investigation of the Humboldt Range during which the 

entire range was mapped in some detail by R. E. Wallace, E. B. Tatlock, and N. J. Silberling (Wallace, 

Tatlock, Silberling, and Irwin, 1969; Wallace, Silberling, 

Irwin, and Tatlock, 1969; Silberling and Wallace, 1967). 

The location and geologic setting of paleontologically 

significant outcrops has thus been fairly well established, but the potential of the area for further 

paleontologic studies is by no means exhausted. 

Although about two man-months of pick-and-shovel 

work were devoted to obtaining bedrock collections from 

the upper Anisian in the vicinity of Fossil Hill in the 

southern part of the range, still larger stratigraphically 

controlled population samples of some taxa would be 

desirable and would be essential for meaningful 

statistical study. In the northern part of the range the 

faunal record of the Middle Triassic is obscured by poor 

fossil preservation, and discovery of even a single 

favorably fossiliferous block could add importantly to 

the known fauna.

During the course of this study much useful information and material on the Middle Triassic paleontology 

and stratigraphy of Canada, and on the Triassic in 

general, were received from E. T. Tozer and the late F. 

H. McLearn of the Geological Survey of Canada. Tozer 

visited various Triassic exposures in Nevada, including 

those in the Humboldt Range, in 1964 and has provided 

encouragement and criticism during the following years.

By the mid-1960's Silberling had organized much of 

the Middle Triassic material from the Humboldt Range, 

prepared synonymies of Smith's numerous species, and 

written some taxonomic description. Nichols completed 

the study in 1976 while a National Research Council 

post-doctoral fellow at the U.S. Geological Survey.

Bernhard Kummel of Harvard University aided the 

present study by providing helpful discussion at various 

times and by lending the Middle Triassic types from the 

Whitney collection at the Museum of Comparative 

Zoology. After a search for Gabb's missing 1864 types at 

Harvard proved fruitless, some of them were discovered

at the Academy of Natural Science of Philadelphia by 

Ellen J. Moore during a visit by her to that institution. 

To Horace G. Richards of the Philadelphia academy we 

are indebted for providing access to these collections and 

lending those of Gabb's types that were recovered.

Most of the photographic illustrations were prepared 

by Kenji Sakamoto of the U.S. Geological Survey.

STRATIGRAPHIC OCCURRENCE AND 

COMPOSITION OF FAUNAS

GENERAL STATEMENT

Cephalopods of early Anisian, middle Anisian, late 

Anisian, early Ladinian, and late Ladinian age are 

represented in the Middle Triassic of the Humboldt 

Range, and bivalves of the genus Daonella are locally 

abundant in rocks of late Anisian and Ladinian age. 

However, the stratigraphic occurrence of these fossils is 

quite uneven. Parts of the section are much more fossiliferous than others, and only some of the Middle 

Triassic faunas are found in sequence in any one part of 

the range.

The fossiliferous Middle Triassic rocks belong to the 

Prida Formation, the lowest of the formations that 

locally constitute the Star Peak Group (Nichols and 

Silberling, 1977). The description of these strata in the 

Humboldt Range and interpretation of their paleogeographic relationships by Silberling and Wallace (1969) 

was emended and amplified by Nichols and Silberling 

(1977) and needs only to be summarized here. 1 Three 

members of the Prida Formation are recognized: a lower 

member that includes a basal conglomerate or sandstone 

overlain by a variety of impure calcareous and dolomitic 

rocks; a middle member, the Fossil Hill Member, which 

is dark-gray, commonly fossiliferous, lenticular 

limestone interbedded with calcareous mudstone, siltstone, and shale; and an upper member of evenly parted, 

dark-gray or black, laminated, cherty limestone. Within 

the 5-km (kilometer) length of the Humboldt Range the 

relative thickness of these three members, and the total 

thickness of the Prida Formation, undergo pronounced 

changes owing partly to local relative uplift and erosion 

during early Anisian time and partly to a southward 

facies transition of the basinal carbonate rocks of the 

Prida with carbonate platform rocks of the largely correlative Augusta Mountain Formation. In total thickness 

the Prida Formation ranges from as little as 

60 m (meters) at its southernmost exposures in the range 

to more than 600 m in the northern part of the range.

Where the Prida was continuously deposited in the

'The stratigraphic nomenclature used for the Star Peak Group by Nichols and Silberling 

(1977) has been adopted by the Geologic Names Committee for use by the U.S. Geological 

Survey.
MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

northern part of the range, the lower member is as much 

as 140 m thick and includes in its middle part a unit of 

carbonate rocks that locally is 60 m thick. At least two 

completely distinct ammonite faunas of Spathian (late 

Early Triassic) age occur at different stratigraphic levels 

in this carbonate unit. The higher of these faunas, which 

is characteristic of the Neopopanoceras haugi Zone, has 

sometimes been regarded as the basal zone of the Middle 

Triassic but is correlated by Silberling and Tozer (1968) 

with the uppermost Lower Triassic Keyserlingites subrobustus Zone of Canada and Siberia. A description of 

this fauna is therefore not included here.

The Fossil Hill Member also attains its greatest 

thickness of approximately 120 m in the northern part of 

the Humboldt Range. Here it includes beds older than 

those at the base of the member farther south and contains ammonite faunas of early, middle, and late Anisian 

age. Farther south in the range, south of Buena Vista 

Creek canyon and Unionville, the Fossil Hill Member is 

less than 60 m thick and contains faunas of late Anisian 

age only. The type section of the member is on the south 

side of Fossil Hill within collecting-site A (pi. 1). Here 

the member is about 60 m thick, but closely spaced 

minor faults prohibit measurement of its thickness along 

any single line of section. It rests with sharp contact on 

quartz-silty, finely crystalline, sugary dolomite at the 

top of the lower member, and it grades upward through 

3-6 m of section into the upper member of the Prida Formation. At site A the stratigraphically lowest molluscan 

fossils occur about 30 m above the base of the Fossil Hill 

Member. However, where intra-Prida Formation erosion 

was greatest in the central part of the range, as in the 

vicinity of the Arizona Mine about two kilometers 

southwest of Unionville, these same upper Anisian 

faunas occur within about 10 m of the base of the 

member.

Throughout the Humboldt Range the transitional Fossil Hill Member-upper member contact roughly coincides with the Anisian-Ladinian Stage boundary. In its 

southernmost exposures in the range the upper member 

is only about 30 m thick and is of earliest Ladinian age. 

Farther north in the range it thickens to more than 600 m 

at the expense of overlying rock units of the Star Peak 

Group, and in its upper part it locally contains faunas of 

both late Ladinian (latest Middle Triassic) and probable 

early Karnian (earliest Late Triassic) age. Although the 

Panther Canyon Member of the Augusta Mountain Formation, the Congress Canyon Formation and some of the 

Smelser Pass Member of the Augusta Mountain Formation, in the southern part of the range are lateral facies 

equivalent to the upper member of the Prida Formation 

in the northern part of the range (Nichols and Silberling, 

1977), and hence are of Middle Triassic age, no identifiable ammonites or halobiid pelecypods have been 

found in these platform carbonate rocks.

All of the Middle Triassic fossils described herein from 

the Humboldt Range are thus from the Fossil Hill 

Member and the upper member of the Prida Formation. 

The successive biostratigraphic units in these rocks and 

their age assignments, modified from the classification 

of the North American marine Triassic by Tozer (1967), 

Silberling and Tozer (1968), and Tozer (1974) are: 

Daonella lommeli beds ---------------late Ladinian

Protrachyceras subasperum Zone - - - -early Ladinian

Frechites occidentalis Zone ------------ late Anisian

Parafrechites meeki Zone ------------- late Anisian

Gymnotoceras rotelliformis Zone ------- late Anisian

Acrochordiceras hyatti Zone -------- middle Anisian

Lenotropites caurus Zone ------------early Anisian

Following the convention used by most Mesozoic ammonite biostratigraphers, the names of ammonite zones, 

such as those listed above under the full name of their 

nominal index species, are generally referred to 

henceforth in this paper only by the trivial name of their 

index species. For example, where the context is clear, 

the name Lenotropites caurus Zone is shortened to 

Caurus Zone.

Some of these biostratigraphic units are much better 

developed than others, and only the three upper Anisian 

zones and the lowermost Ladinian zone, as developed at 

localities near Fossil Hill in the southern part of the 

range, are stratigraphically contiguous. The others are 

separated by unfossiliferous beds, leaving room in the 

section for a number of additional biostratigraphic units 

of comparable scope. For example, the Balatonites 

shoshonensis Zone, which occurs in the Favret Formation at localities farther east in northwestern Nevada, is 

not represented in the Humboldt Range. However, in the 

southern Tobin Range, about 50 km east of Fossil Hill, it 

has been found stratigraphically bracketed between the 

Hyatti and Rotelliformis Zones (Burke, 1973, p. 52) as 

anticipated by Silberling and Tozer (1968).

LOWER ANISIAN

In the Humboldt Range the oldest age-diagnostic 

Middle Triassic ammonites are indicative of the Caurus 

Zone, which has its typical development in northeastern 

British Columbia (Tozer, 1967; Silberling and Tozer, 

1968). Listed in the order of decreasing abundance, these 

ammonites in the Humboldt Range are:

Gymnites tregorum n. sp.

Isculites meeki (Hyatt and Smith)

Lenotropites caurus (McLearn)

Paracrochordiceras aff. P. americanum McLearn 

This fauna is restricted to about a meter of beds that 

crop out at U.S. Geological Survey Mesozoic localities 

M2358, M2367, and M2828 along strike between Star 

Creek canyon and Bloody Canyon (fig. 1) where the Fossil Hill Member of the Prida Formation attains its
STRATIGRAPHIC OCCURRENCE AND COMPOSITION OF FAUNAS

greatest thickness in the Humboldt Range. The part of 

the Fossil Hill Member beneath these fossiliferous beds 

varies from about 30-45 m thick. Ammonites identified 

as Eophyllites sp. and brachiopods assigned to 

"Spirigem" cf. "S" stoliczkai Bittner occur near its 

base, but the few other ammonites found in this basal 

part of the member are not well enough preserved to be 

identified. Above the fossiliferous beds of the Caurus 

Zone, no fossils have been found in the 30-40 m of section up to the stratigraphically lowest occurrences of 

Hyatti Zone fossils.

MIDDLE ANISIAN

The name Acrochordiceras hyatti Zone is introduced 

here for the strata in Nevada referred to by Tozer (1974) 

as the "A. hyatti beds." These strata were originally assigned by Silberling and Tozer (1968; Silberling and 

Wallace, 1969) to the Varium Zone whose typical occurrence is in northeastern British Columbia. Subsequently, this zone in Canada was recognized as including 

correlatives in Nevada of both what is now termed the 

Hyatti Zone and the succeeding Shoshonensis Zone. In 

the Humboldt Range both the Hyatti Zone and the older 

Caurus Zone are represented only north of Buena Vista 

canyon. Farther south in the range, marine strata corresponding in age to these zones are absent.

A complete list of the cephalopods identified from the 

Hyatti Zone in the Humboldt Range includes:

Koipatoceras discoideus n. sp.

Alanites mulleri n. sp.

A. obesus n. sp.

Ismidites aff. /. marmarensis Arthaber

Amphipopanoceras cf. A. selwyni (McLearn)

Acrochordiceras hyatti Meek

Cuccoceras bonaevistae (Hyatt and Smith)

Nicomedites sp.

Hollandses voiti (Oppel)

lAnagymnotoceras moderatum (McLearn)

Japonites cf. J. sugriva Diener

Gymnites perplanus (Meek)

Isculites tozeri n. sp.

Czekanowskites hayesi (McLearn)

Pseudodanubites halli (Mojsisovics)

Unionvillites hadleyi (Smith)

U. asseretoi n. sp.

Intornites mctaggarti (McLearn)

/. cf. /. nevadanus (Hyatt and Smith)

Ussurites cf. U. arthaberi (Welter)

Aulametacoceras? humboldtensis n. sp.

Grypoceras whitneyi (Gabb)

In addition, orthoconic nautiloids are common. Among 

the ammonites only Alanites mulleri and the species of 

Acrochordiceras, Cuccoceras, Gymnites, Isculites, and

Intornites are fairly well represented in the available collections. Some of the other species listed are represented 

by only a single specimen. The only other shelly fossils 

found in the Hyatti Zone are two kinds of bivalves: 

"Sphaera" whitneyi Gabb and a Posidorao-like form 

having coarsely rugate ornamentation.

Although the Hyatti Zone is the most fossiliferous part 

of the Triassic section in the northern part of the range, 

preservation of fossils is generally poor because of incipient metamorphism. At most places identifiable 

cephalopods were collected as float or else they could be 

obtained from only a single bed within the zone, which 

has a total thickness of at least 45 m.

The typical expression of the Hyatti Zone is 

designated here as the section that includes USGS 

Mesozoic localities M2829 and M2830 (Silberling and 

Wallace, 1967; 1969, pi. 1) in the Fossil Hill Member of 

the Prida Formation on the east slope of Star Peak. 

Locality M2830 is about 60 m above the base of the Fossil Hill Member and about 30 m higher in the section 

than USGS Mesozoic locality M2828, which contains 

ammonites of the Caurus Zone. Compared with other 

more or less correlative localities in the lower part of the 

Hyatti Zone, locality M2830 is represented by only a few 

ammonites, including Alanites cf. A. mulleri, Acrochordiceras hyatti, Cuccoceras bonaevistae, and Intornites 

mctaggarti. The last two species listed are especially 

characteristic of the lower part of the Hyatti Zone. 

Locality M2829 is approximately 40 m higher in the section and has yielded the following ammonites:

Alanites cf. A. obesus n. sp.

Acrochordiceras hyatti Meek

Gymnites cf. G. perplanus (Meek)

Pseudodanubites halli (Mojsisovics)

Unionvillites hadleyi (Smith)

U. asseretoi n. sp.

Intornites cf. /. nevadanus (Hyatt and Smith) 

Of these, the last three listed are characteristic of the upper part of the Hyatti Zone. In the northern Humboldt 

Range, where the Hyatti Zone occurs, the next higher 

molluscan faunas are at least 45 km stratigraphically 

above the Hyatti Zone within the Fossil Hill Member 

and are poorly represented. If any ammonites are found 

at all here, they are poorly preserved and generally represent the Frechites nevadanus beds of the upper Anisian 

Meeki Zone.

UPPER ANISIAN

Upper Anisian cephalopod and halobiid bivalve 

faunas are well represented in the southern part of the 

Humboldt Range, where they are the oldest Middle 

Triassic larger invertebrate faunas found. Unlike the 

scattered occurrences of Anisian molluscan fossils
MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

farther north in the Humboldt Range, at favorable 

localities, such as those in the vicinity of Fossil Hill and 

Saurian Hill (pi. 1 and fig. 2), large upper Anisian collections can be obtained from bedrock at fairly closely 

spaced stratigraphic intervals.

Large collections, mostly obtained from stratigraphically mixed, weathered surface debris, were made by J. 

P. Smith from Fossil Hill and vicinity in the early 1900's 

and formed the basis for his monograph (Smith, 1914) on 

Middle Triassic faunas. Using stratigraphically controlled bedrock collections from the same area, Silberling (1962) published a preliminary taxonomic revision 

of the many species of ammonoids described by Smith 

from the upper Anisian and a tabular summary of their 

stratigraphic distribution. With only minor further taxonomic revision, this succession formed the basis for the 

definition of the Rotelliformis, Meeki, and Occidentalis 

Zones by Silberling and Tozer (1968), who regarded 

these zones as a complete representation of the upper 

Anisian in North America.

In the vicinity of Fossil and Saurian Hills, cephalopod 

and Daonella shells, more or less broken but readily 

identifiable, are important constituents of lenticular, 

thin to medium-thick, micritic limestone beds within 

the Fossil Hill Member of the Prida Formation. These 

limestone beds are irregularly interstratified with 

calcareous siltstone, mudstone, and shale and generally 

occur at 1-2 m intervals. Upper Anisian collections have 

been obtained from at least 20 different stratigraphic 

levels within a total thickness of about 25-30 m of strata. 

To achieve this density of stratigraphically successive 

samples, a total of 55 bedrock collections were made 

within collecting-sites A, B, and C, the locations of 

which are shown on plate 1.

Because the fossiliferous limestone beds are laterally 

discontinuous, collecting from single measured sections, 

as at site B, proved unrewarding. At sites A and C (figs. 3 

and 4) collections were randomly made across and along 

strike wherever fossiliferous bedrock could be found at or 

near the surface of the gullied, thinly soil-covered hillsides. Stratigraphic relations between collections at each 

site were determined, insofar as possible, by laterally 

trenching certain beds from which vertical stratigraphic 

measurements could be made. Plates 2 and 3 are 

detailed plane-table maps of these sites.

Stratigraphic superposition at these sites can only be 

directly observed for several collections at a time, owing 

to lateral lithologic variation and, at site A, small-scale 

normal faulting. Thus the overall stratigraphic distribution must be obtained by correlating and combining the 

superpositional data that can be observed within about a 

dozen different groups of bedrock collections. Some additional stratigraphically restricted collections were 

made from isolated bedrock exposures and from single

loose weathered blocks. To correlate these various collections, the faunal sequence observed within the upper 

Anisian has been used as a local standard (Silberling, 

1962). Twelve successive informal biostratigraphic units, 

termed "beds," are recognized on the basis of one or 

more index species of ammonites. The grouping of these 

informally named beds within the upper Anisian zones is 

shown on table 1. For all of the collections made near 

Fossil and Saurian Hills, the superpositional relationships, correlations, and assignments to the biostratigraphic units are given in table 2.

The stratigraphic distribution of the upper Anisian 

species of ammonites, coleoids, and Daonella 

represented in stratigraphically controlled collections 

from the Fossil Hill and Saurian Hill area is plotted on 

table 1. Because successive population samples of some

FIGURE 3. View northwest towards collecting-site A on the south side 

of Fossil Hill, Humboldt Range (pi. 1). Fossil localities at this site 

are on the gullied slope in the center of the view.

FIGURE 4. View southeast across collecting-site C on the south spur of 

Saurian Hill, Humboldt Range (pi. 1). The cluster of trees in the 

center of the view is within site C.
STRATIGRAPHIC OCCURRENCE AND COMPOSITION OF FAUNAS

genera tend to show progressive changes in morphology, 

in some cases suggesting transitions between arbitrarily 

defined species, the stratigraphic ranges are plotted in 

the same manner used by Silberling (1962, table 1). To 

accommodate gradation between species, where such 

might exist, "the stratigraphic range of those populations in which the majority of specimens fall within the 

arbitrarily defined morphologic limits of one species is 

indicated by a row of X's. This range is then extended by 

plus signs to show the occurrence of specimens that 

typologically would belong to the same species, but are 

end-member variants of populations that as a whole 

have the morphology of a different species of the same 

genus." The rationale for this procedure is discussed 

further in Silberling (1962, p. 158-159).

Although it can be described as progressive through 

time, morphologic change, or the replacement of one 

species by another in successive stratigraphic levels, 

within several of the better represented families of upper 

Anisian ammonites from the vicinity of Fossil Hill cannot be demonstrated to be gradual, as pointed out by 

Silberling and Nichols (1980). This limitation applies 

even though population samples were obtained from 

stratigraphic levels as closely spaced as the occurrence 

and preservation of the ammonites in the section would 

permit. Thus the data on table 1 permissibly fit the 

evolutionary pattern termed "punctuated equilibrium" 

by Eldredge and Gould (1972) and do not necessarily 

demonstrate "phyletic gradualism."

The 37 species of upper Anisian ammonites listed in 

table 1 represent a considerable taxonomic revision of 

the many species described from the Fossil Hill area by 

Smith (1914). Of the 110 species of ammonites described 

or listed by Smith from this locality, 14 either are known 

to be other than late Anisian in age or are based on apparently pathologic specimens, as explained by Silberling (1962, p. 157-158). Of the remainder, only 5 of the 

species reported by Smith are not represented in the collections on which the present study is based. These are:

Gymnites calli Smith, 1914

Ptychites evansi Smith, 1914 [probably best regarded as a nomen dubium]

Trachyceras (Anolcites) barberi Smith, 1914

Ceratites weaveri Smith, 1914 [holotype from New 

Pass Range, Nev.]

Ceratites (Paraceratites) gabbi (Meek) of Smith 

[= Eudiscoceras gabbi Meek, 1877; holotype from 

Cottonwood Canyon, Humboldt Range]

Although not found by us in the Humboldt Range, the 

morphologically distinctive Eudiscoceras gabbi was collected by the late S. W. Muller in the southern Tobin 

Range (at Stanford University loc. 2766) in association 

with ammonites of the upper Rotelliformis Zone or lower 

Meeki Zone.

Only two or three* kinds of ammonoids different from 

those described by Smith were collected during the present investigation from the upper Anisian of the Humboldt Range. These additional occurrences, which are 

not listed on table 1, include:

Sturia cf. S. sansovinii Mojsisovics, 1882 [a float 

specimen from the Frechites nevadanus beds of 

the Meeki Zone or stratigraphically higher] 

Ptychitest sp. indet. [an immature specimen from

the Parafrechites meeki beds] 

Discoptychites sp. [a single fragmentary specimen 

from the Paraceratites clarkei beds of the Rotelliformis Zone. Possibly the same as "Ptychites" 

evansi Smith]

In addition to the biostratigraphically useful ammonoids, coleoids, and Daonellas listed on table 1 and 

discussed above, four different nautiloids, Michelinoceras? cf. M.? campanile (Mojsisovics), Germanonautikis furlongi Smith, Grypoceras whitneyi (Gabb), and 

Paranautilus smithi Kummel, and the bivalve Pteria 

obesus (Gabb) are described herein as part of the upper 

Anisian fauna of the Humboldt Range.

Considering the very large amount probably at least 

several tons of paleontological material collected from 

the Fossil Hill area, the approximately 40 species of ammonites accounted for above most likely represent the 

total number of taxa of late Anisian age present at this 

locality. This figure, of course, is dependent on the scope 

of intraspecific variation accepted by us. Of this total of 

40 species, as shown on table 1, the Rotelliformis, Meeki, 

and Occidentals Zones have yielded, respectively, a 

total of 16, 15, and 14 species of ammonites, and each 

zone is characterized by about 10 uniquely occurring 

species or species having uniquely overlapping ranges. 

Some species of coleoids and Daonellas are also 

restricted in their stratigraphic ranges within the upper 

Anisian. The greatest diversity of ammonites collected 

from a single limestone layer is 9 species from USGS 

locality M144, which is representative of the Nevadites 

humboldtensis beds of the Occidentals Zone. The 

average diversity of ammonite species for the 12 

biostratigraphic subdivisions or "beds" of the upper Anisian zones is 6.8.

LOWER LADINIAN

The Anisian-Ladinian Stage boundary, as recognized 

herein, roughly coincides with the lithologic transition 

from the Fossil Hill Member upward into the upper 

member of the Prida Formation. Compared with the 

Fossil Hill, which consists of calcareous siltstone, mudstone, and shale with lenticular fossiliferous limestone 

interbeds, the upper member of the Prida is lithlogically 

more uniform. It consists mostly of laminated, regularly 

parted, cherty micritic limestone in which the small
TABLE 1. Stratigraphic distribution of upper Anisian ammonoids, coleoids, and Daonellas at Fossil Hill and vicinity, Humboldt Range

[Rows of crosses denote stratigraphic ranges of populations in which the majority of specimens fall within the arbitrary morphologic limits of nominal species. Extension of these ranges by plus signs shows the 

typologically would belong to the same species, but are end-member variants of populations that as a whole have the morphology of a different species of the same genus. Queries mark the stratigraphic level of 

w?

Q .S

W -S

s s ?

 3 s

B CO

2 '.a

a J3 

c -M

I 

Frechites occidentalis 

Zone

Parafrechites meeki 

Zone

Gymnotoceras rotelliformis 

Zone

Nevadites gabbi beds

Nevadites furlongi beds

Nevadites humboldtensis beds

Nevadites hyatti beds

Parafrechites dunni beds

Parafrechites meeki beds

Frechites nevadanus beds

Gymnotoceras blakei beds

Paraceratites cricki beds

Paraceratites vogdesi beds

Paraceratites clarkei beds

Paraceratites burckhardti beds

c- x + a x x

8 B + 

a x + 

a + x 

c- X X + B 

jxj XX

8 a x + 

B a a + 

^4 b6 X 

X ' X ^ 

1 81+ i | " 

888 + B 

S x alb XXX X 

i^ X X X 

jj x + x g 

X !K! X X

XXX + X X

xx+H x R 

xx a 

X H

a+x ^d + B 

s^ _1_ W ?N PS 

R + R x

x x + x a 

x x + x 8 

X X + X X

xx a ^

XX X X

a a a x XX X X 

XX X

H H

a a x
STRATIGRAPHIC OCCURRENCE AND COMPOSITION OF FAUNA

O 

O

1

 g

mqnp -(j

BUBJ^) mossnow -(j -jo '(j

osisfoj^ o^oSuoja '(j -p -(j

(aipauae) tjnjs -(j -p -(j

Jiuig mioauawo t^jauoo(j

avoiiNoaisod 

vaodAoaiad

(Jjaaj^) stsuaponau -y

Hjiuig snpyos -y

Jtuis sn]n)O(iBp sawaouiy

y 'ds sayijaouiy

avcaaiHinaxoHdix 

vacaoaioo

) aojpuoxajo sa}]

'Q -p saimwtQ 

aVOLLINJVAO

5(8aj\[ iqqoS 'J 

(\addQ) unojjoq -j -p saisaauveuj

avaixsaoHv

sjsuatpjoqwmf -j;

pus

avaiLisnaxoHd

siqjouojd -j; -jo isaii

avdlLINOdVf

xxxx

xxxx

xxxx

xxxx

XXX

gabbibeds

Nevadites

XXXX

xxxx

xxxx

xxxx

xxxx

01

Nevadites

i

xxxx

XX

xxxx

X

XXX

xxxx

X

XXX

00

£ff\

humboldtensii

Nevadites

i

xxxx

xxxx

xxxx

XXX

xxxx

xxxx

hyatti beds

Nevadites

.05 "3

1

'o »

o a 0 0

05 N

 "i3 s

cu

^

i

X

xxxxxxxxxx

xxxxxx

XX

6

xxxxxxxx

beds dunni tes

J

i i

xxxxxxx

6

xxxxxxx

beds meeki ts

1

X

X

XX

XXX

XXX

+

m

levadanus bedi

Frechites r

'-S

s05 

 ^ *

"C ^

o N

.^

BQ

^

xxxxxxx

X

XX

X

xxxxxxx

+ +

xxxxxxx

'S

-22

05

Bcu

Gymnotoc

XXXX

X

xxxx

beds cricki tes

Paracerati

xxxxxx

xxxxxx

xxxx

to

^ 

ID

1

05

.8

Paracerati

xxxxx

xxxxx

00

'tes clarkei bed

Paracerati

XXX

XXX

00

<D

'tes burckhardt

Paracerati

.05

5

1-~

cu

8 OB

CO g

3 o

ft, N

o

g

s
10 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

TABLE 2. Correlation of upper Anisian and lower Ladinian bedrock and single float-block localities at collecting-sites A, B, and

C in the vicinity of Fossil Hill and Saurian Hill, Humboldt Range

[ Within each vertical column of numbers, superposition of localities has been objectively determined, and stratigraphic distances in meters between localities are given where known. Vertical

scale is not proportional to true stratigraphic thicknesses. Localities are described in table 3]

Zone

S

1 o.

_g

p

CB

"3

"6

T3

O

'3

S

.a

if

1

Zona.subd.vis.n

Nevadites gabbi beds

Nevadites fwlongi beds

Nevadites humboldtensis beds

Nevadites hyatti beds

Parafrechites dunni beds

Parafrechites meeki beds

Frechites neuadanus beds

Gymnotoceros blakei beds

Paraceratites cricki beds

Paraceratites vogdesi beds

Paraceratites clarkei beds

Paracerantes burckhardti beds

Site A

M962A

M962

M9681

M136

[

1.5tm 

M136-5ft(1.5m)

2.l'm

Mt36-7ft(2.1m)

M140

M138

M137

M147

M961

M963 M142

M141

M146

T

4.0m

I M145

1

4.0m

J M144

T

1.8m

M144-6ft(1.8m)

6.4m

1 M960

1.2m

M143

I

4.0m

M»64

7.3m

!

M139

M966

M967

2.7m

M967-9ft(2.7m)

4.5m

M967-15ft(4.5m) 

0.6m

i 

M965+3ft (0.9m)

T

0.9m

M965

SiteB

M167

5.5m

ivil66

'

6.0m

M165 M163

1.2 m

M162

M164

SiteC

M626

M615

M605+10ft(3.0m)

3.0 m

, M605

M624

14m

1

i 

M620

M

2.

-j

^

1.

. M

616

r

I m

611

3m

609

M628

M6

|

27

3.0m

, Mf 23

M612

1.8m

Me 10

M625

T

2.1m

M621

1

3.7m

M618

t

4.3m

1

M617

1

4.3m

I

M608

M622

t

5.2m

M619

1 5.8 m

1

M614

2.4m

M607+2 ft (0.6 m)

0.6m

M§07

M613

1

4.6m

Ivf606

'Collected as float and placed in sequence by fai

amount of quartz silt is evenly distributed as scattered 

grains or concentrated in laminae. Subordinate interstratified thick-bedded units of course-grained 

bioclastic limestone and carbonate slide breccias are the 

only other primary rock types in the member and are 

most important in the higher parts of the section 

(Silberling and Wallace, 1969). Locally, as in the vicinity 

of Fossil Hill, much of the upper member is secondarily 

dolomitized where it stratigraphic ally underlies the 

primary dolomite forming the Panther Canyon Member 

of the Augusta Mountain Formation (Nichols and 

Silberling, 1977). Deposition of the distinctive basinal 

limestone of the upper member was interpreted by 

Nichols and Silberling (1977) to have been relatively 

rapid and to reflect the development of a carbonate platform farther east in north-central Nevada.

Along with the lithologic change from the Fossil Hill 

Member to the upper member of the Prida Formation, 

the cephalopods and Daonella shells that are so abundant in the Fossil Hill become scarce and then all but 

disappear. Only in the lowermost 10 m or so of the upper 

member are fossils locally well represented, and these 

beds that are directly above the Occidental Zone in the

vicinity of Fossil Hill constitute the type Subasperum 

Zone of Silberling and Tozer (1968). Impressions of 

Daonella rieberi are locally abundant in the Subasperum 

Zone, but cephalopods are scarce. Stratigraphically 

restricted population samples that would permit taxonomic revision and partial synonymy of the primitive 

species of Protrachyceras described from these rocks in 

the Humboldt Range could not be obtained.

The species that occur together in collections made by 

us from the Subasperum Zone are:

Protrachyceras subasperum (Meek) [along with the 

possibly synonymous species P. americanum 

(Mojsisovics) and P. lahontanum Smith] 

Frechites johnstoni n. sp. 

Epigymnites alexandrae (Smith) 

Daonella rieberi n. sp.

Protrachyceras meeki occurs low in the upper Prida 

and therefore may also represent the Subasperum Zone.

UPPER LADINIAN

Above the Subasperum Zone the upper member of the 

Prida Formation is mostly unfossiliferous. Identifiable 

fossils, found at only a few places, usually consist of a
AGE AND CORRELATION 11

single species of Daonella similar to or identical with the 

characteristic Alpine upper Ladinian species D. lommeli 

(Wissman).

The most diverse upper Ladinian fauna was collected 

in float from the upper member in the upper part of 

Congress Canyon, where the specimens of Daonella cf. 

D. lommeli described herein were found associated with 

Protrachyceras?, Proarcestes, and Hungarites. Of these 

ammonites, only the specimen of the Hungarites is 

described in order to document the occurrence of this 

genus in North America. It has also been reported from 

rocks of about the same age in the New Pass Range, Nev. 

(Silberling and Tozer, 1968, p. 36). From the same 

general locality in Congress Canyon, collections made 

previously by F. N. Johnston include, in addition to 

Daonella cf. D. lommeli, the ammonites Meginoceras cf. 

M. meginae McLearn, Protrachyceras cf. P. sikanianum 

McLearn, and Thanamites schoolerensis (McLearn), 

which are indicative of the Meginae Zone.

Another upper Ladinian species of Daonella, D. n. sp. 

ex aff. D. indica Bittner, is described from Fisher Canyon in the southern part of the Humboldt Range where it 

is associated with probable specimens of D. lommeli.

AGE AND CORRELATION

Figure 5 shows the stage and substage assignments 

adopted herein for the Middle Triassic biostratigraphic 

units recognized in Nevada and the correlation of these 

biostratigraphic units with those recognized in Canada. 

The application of stage and substage terms to the 

faunal succession in North America follows the classification proposed by Tozer (1967) and Silberling and 

Tozer (1968). During the early 1960's, when the North 

American classification was being formulated, little 

modern data were at hand to indicate how the classical 

Alpine stages and their subdivisions should be applied; 

the faunal succession in North America was known in 

much more detail than that in Alpine Europe where the 

stage names were originally defined.

In recent years a rekindling of interest in Triassic 

biostratigraphy of the Alpine-Mediterranean region has 

greatly improved knowledge of the classical Middle 

Triassic sections. Some of the more important studies 

are: the age of the Avisianus Zone in the Italian Alps 

(Assereto, 1969), the identity of the Binodosus Zone in 

the northern and southern Alps (Assereto, 1971), the 

Anisian biostratigraphy of the island of Chios and 

nearby northwestern Turkey (Assereto, 1972, 1974), the 

Hallstatt facies of Middle Triassic in Greece (Krystyn 

and Mariolakos, 1975), conodont biostratigraphy 

(Kozur, 1974, 1975), the unique ammonite and Daonella 

succession of the Grenzbitumenzone of southern 

Switzerland in a series of papers by Rieber (culminating

in Rieber, 1973), and the type section of the Anisian in 

Upper Austria (Summesberger and Wagner, 1972). As a 

consequence of these and other studies, the faunal succession of the Alpine-Mediterranean Anisian is especially well established, as shown by the representative 

columns included in figure 5. For the most part, agreement exists in the correlation of ammonite faunas 

between North America and Alpine Europe. The placement of the Anisian-Ladinian Stage boundary and the 

choice of substage units, however, is unsettled, and 

typological arguments can be made for several different 

points of view. Presumably convention will ultimately 

rule among the various usages that now exist.

To reiterate the argument given by Silberling and 

Tozer (1968, p. 12), the Anisian-Ladinian boundary in 

Nevada is placed below the first occurrence of primitive 

Protrachyceras that are characterized by having a discrete ventral furrow and ceratitic saddles. These fossils 

are known from the southern Alps low in the Buchenstein beds, the lithologic unit associated with the first use 

of the stage-name Ladinian by Bittner (1892). However, 

at a time when the youngest faunas of the Anisian were 

generally regarded as those of the Trinodosus Zone, the 

Avisianus Zone in the southern Alps was long regarded 

as Ladinian in age and mistakenly placed in the zonal 

succession above the position of the earliest species of 

Protrachyceras such as P. reitzi. Consequently, even 

after correction of its superpositional relationships (Assereto, 1969), an argument can still be marshalled for 

retaining the Avisianus Zone in the Ladinian, as advocated by Kozur (1974, 1975).

PALEONTOLOGY 

PROCEDURES AND CONVENTIONS

Many of the following descriptions involve species or 

genera that were previously described from the Humboldt Range by Smith (1914). For these, complete 

descriptions are provided here only when the concept of 

Smith's taxa has been considerably altered. Thus the 

present report is intended to be used in conjunction with 

the original monograph by Smith.

In addition to primary types, Smith commonly illustrated several or more examples of the species he 

recognized. Stratigraphically controlled population samples indicate that some of the paratypes or plesiotypes 

figured by Smith were misidentified. Each specimen 

figured by Smith must therefore be cited individually in 

the synonymies. This citation is done by linking together 

different figure numbers referring to the same specimen 

by a hyphen and separating the figure numbers of different specimens, where they are written in a series, by a 

comma.

Suture lines for which the illustrations by Smith
12 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

NORTH AMERICA

Stages and substages 

( Silberling and Tozer, 1968)

LADINIAN

ANISIAN

upper

lower

upper

middle

lower

Biostratigraphic units

Humboldt Range, Nev. 

(this paper)

Daonella lommeli beds

Subasperum Zone

Occidentalis Zone

Meeki Zone

Rotelliformis Zone

upper

lower

Caurus Zone

Tobin Range, Nev. 

(Burke, 1973, p. 52)

Rotelliformis Zone

Shoshonensis Zone

Hyatti Zone 

(upper part)

Northeastern British Columbia 

(Tozer, 1974)

Sutherland! Zone

Maclearni Zone

Meginae Zone

Poseidon Zone

Subasperum Zone

Chischa Zone

Deleeni Zone

Varium Zone

upper

middle

lower

Caurus Zone

ALPINE EUROPE

European Tethys 

( Kozur, 1974, 1975 )

Zone

Archeleus

Curionii

Reitzi

Avisianus

Trinodosus

Balatonicus

Ismidicus

Osmani

Anodosum

Substage

Longobard

Fassan

Illyr

Pelsen

Bithynian

Aegean

Stage

z 

5 

<

w 

<

FIGURES (above and facing page). Correlation chart showing the stage and substage assignments of Middle Triassic biostratigraphic 

units in the Humboldt Range and elsewhere in North America compared with biostratigraphic successions, stages, and substages recognized in Alpine Europe. Dashed lines indicate approximate boundaries.

(1914) are adequate are not illustrated again in the present report.

The terminology used herein for sutural elements of 

ammonites is purely descriptive and is based on the position of different elements on the mature phragmocone; it 

does not necessarily derive from the ontogenetic development of the elements. The abbreviations Si, S2, and S3 

refer to the first, second, and third principal saddles 

beginning with the most ventral one. LI, L2, and L3 refer 

to the principal lobes in the same fashion. Minor sutural 

elements located dorsally of the principal elements are 

termed auxiliary elements. The ventral lobe is abbreviated VL, and the external saddle, which divides the 

ventral lobe in some ammonites, is abbreviated ES.

Reference marks on all of the ammonite suture-line

drawings are those conventionally used: the arrow points 

in the orad direction and marks the midline of the 

venter; straight lines mark the umbilical shoulder, 

ventro-lateral shoulder, or both; and an arcuate line 

marks the umbilical seam where it can be located.

Ratios used to express the proportions of coiled 

cephalopod shells are: greatest width to diameter (W/D), 

width of umbilicus to diameter (U/D), and greatest 

width to maximum height (W/H). In reference to the 

proportions of a single specimen, all of the measurements that enter into these ratios are taken in the same 

plane that includes the axis of coiling.

Repositories of figured specimens are abbreviated as 

follows:
PALEONTOLOGY PROCEDURES AND CONVENTION 13

ALPINE EUROPE

Kokaeli Peninsula, 

Turkey and Chios 

(Assereto, 1972, 1974)

Biostratkjraphic unit

Flexoptychites beds

Paraceratites beds

Balatonites beds

Ismidicus Zone

Osmani Zone

ParacrochordicerasJaponites beds

Substage

Illyr

Pelson

Bithynian

Aegean

1

3

Stage

<

Greece 

(Krystyn and 

Mariolakos, 1975)

Biostratigraphic 

unit

Protracyceratids with 

ceratitic 

sutures

Reitzi Zone

Avisianus Zone

Substage

Longobard

Fassan

Illyr

Pelson

Bithynian

Stage

z 

5 

_i

CO

z

G renzbitu menzone, 

Switzerland 

(Rieber, 1973)

Fauna

"Protracyceras "

Stoppaniceras 

Daonella elongata 

Ticinites 

Parakellnerites

Zone

Curionii Zone

Reitzi Zone

Polymorphus Zone

Substage

Fassan

Illyr

Stage

z 

5 

_i

co

<

USNM National Museum of Natural History,

Washington, D.C. 

ANSP Academy of Natural Sciences of

Philadelphia 

MCZ Museum of Comparative Zoology, Harvard

University

Data on the occurrence of each of the species collected 

during the present investigation include the number of 

specimens obtained from each locality. For example, the 

entry reading "USGS Mesozoic localities M1181 (25+) 

and M2829 (4)" means that 4 recognizable specimens of 

the species were collected from locality M2829, and 25 

identifiable specimens, plus additional immature or 

broken specimens, were obtained from locality M1181.

The greatest amount of synonymizing of Smith's 

species involves those from the upper Anisian of the Fossil Hill area where population samples illustrating the 

range in intraspecific morphologic variation have been

obtained from stratigraphically controlled bedrock collections. Actual or potential intergrading variants that 

occur together at the same stratigraphic level are 

regarded here as belonging to the same species. Where 

stratigraphically successive population samples show a 

progressive shift in morphology, the cutoff between contiguous species is essentially arbitrary. The population 

sample from any particular level is assigned to that 

species whose arbitrarily defined morphologic scope includes the mean morphologic variants of the sample 

(Silberling, 1962, p. 158).

For some of the better represented single-bed population samples, a roughly normal frequency distribution of 

morphologic variants can be demonstrated simply by 

sorting out all of the specimens in the sample into 

morphotypes that range spectrally from one extreme to 

the other with respect to one or more characters. Figure 6 

illustrates two examples of this kind of distribution. For 

most species, however, the number of representatives
MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

B C D E F 

MORPHOTYPES

C D E F 

MORPHOTYPES

G H

FIGURE 6. Frequency distributions of morphologically 

different variants within single species of ammonites from 

USGS locality M136. A, 99 specimens of Gymnotoceras 

rotelliformis divided among morphotypes A-G that range 

progressively from most compressed, delicately ornamented 

variants (morphotype A) to most robust, coarsely ornamented variants (morphotype G). B, 47 specimens of 

Paraceratites vogdesi divided among the same kind of 

morphotypes lettered A-I.

from one stratigraphic level is inadequate to demonstrate complete intergradation, and a normal distribution of morphologic variations and a reasonable range in 

variation within species must be assumed.

Regrouping of the narrowly defined species described 

by Smith (1914) on the basis of stratigraphic ally controlled bedrock samples from the same general locality 

involves little guesswork. Problems arise where the 

morphology of previously named species, typologically 

defined from other parts of the world, is represented 

within the range of morphologic variation of single 

population-based species. In these cases, the older 

typological names are ignored on the basis that they 

represent populations of unknown morphologic range. 

They are names for concepts that are intrinsically different from the species recognized here. This problem is 

discussed further in the description of Paraceratites

vogdesi, which as revised almost certainly includes 

variants having the morphology of specimens that typify 

species named in the last century from the Alpine Triassic.

All of the U.S. Geological Survey fossil-locality 

numbers to which reference is made in this report are 

described in table 3. The prefix "M" in these numbers 

denotes that they are recorded in fossil-locality registers 

maintained at the Menlo Park, Calif., laboratory of the 

U.S. Geological Survey. Numbers less than Ml,000 are 

recorded in an all-purpose register; those greater than 

Ml,000 are recorded in Mesozoic megafossil registers 

and these localities are properly referred to as "USGS 

Mesozoic localities."

SYSTEMATIC DESCRIPTIONS

Class CEPHALOPODA 

Subclass AMMONOIDEA

Order CERATTTTDA

Superfamily HEDENSTROEMIACEAE (Waagen)

Family SAOECERATIDAE Hyatt, 1900

Genus SAGECERAS Mojsisovics, 1873

Sageceras gabbi Mojsisovics, nomen dubium

Plate 4, figures 1, 2

Ceratites haidingeri (Hauer) [in part]. Gabb, 1864, p. 22, pi. 5, figs. 8, 

10 [not pi. 4, fig. 9 = Longobardites sp.].

Sageceras gabbi Mojsisovics, 1873, p. 71 [new name for Ceratites 

haidingeri (Hauer) of Gabb, 1864, pi. 5, figs. 8, 10] Hyatt and 

Smith, 1905, p. 97, pi. 25, figs. 1-3 [= copy of Gabb, 1864]. Smith, 

1914, p. 49, pi. 6, figs. 1-3 [ = copy of Gabb, 1864].

The specimen illustrated (ANSP 30783) is thought to 

be the original of Gabb's (1864) figures 8 and 10 on his 

plate 5. In addition to Gabb's label, a note reading "this 

may be the type figured on pi. 5, f. 10 & 8" was found associated with this specimen in the collections of the 

Academy of Natural Sciences of Philadelphia. The note 

is unsigned but is like others that were written by 

Alpheus Hyatt and accompany Gabb's Triassic fossils at 

the Philadelphia Academy. The specimen, a complete 

phragmocone showing the final septum and beginning of 

the body chamber, is sheared parallel to the plane of 

symmetry, partly crushed, and badly eroded; it lacks the 

orad part of the venter, but the estimated maximum 

diameter of the phragmocone was about 110 mm or 

roughly the size indicated by Gabb for his figure 10. On 

Gabb's label the locality is given simply as "Humboldt, 

Nev." which agrees with the locality given by him (1864, 

p. 23) in his description of Goniatites haidingeri. Like 

other fossils described by Gabb from the Humboldt 

Range, this specimen is probably from the Middle Triassic in the vicinity of Buena Vista or Star Canyons. This 

specimen is specifically unrecognizable owing to its poor 

preservation.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 15

TABLE 3. Triassic fossil localities in the Humboldt Range and vicinity, north-central Nevada

[Unless otherwise noted, all localities are in the Fossil Hill Member of the Prida Formation, and collections were made by N. J. Silberling, 1956-65]

USGS locality Field locality Description and collector(s)

M136-M146 - - - 57-66-1 through 11 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Stratigraphically controlled 

bedrock collections from collecting-site A (pi. 1) on south side of Fossil Hill between South 

American and Troy Canyons. Approximately 2,000 feet (600 m) NWfrom SE corner of sec. 19, 

T. 28 N., R. 35 E. Localities plotted on plate 2. Rotelliformis, Meeki, and Occidentalis Zones.

M147 --------- 57-66-12 Same locality as M136-M146 except from upper member of Prida Formation and Subasperum

Zone.

M162 --------- 57-51-B102 Union Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from

collecting-site B (pi. 1) on west side of low hill capping first small spur south of Fossil Hill 

between South American and Troy Canyons. Approximately 1,200 ft (370 m) N. 80° W. from 

SE corner of sec. 19, T. 28 N., R. 35 E., 102 ft (31 m) Stratigraphically above base of Fossil Hill 

Member of Prida Formation. Section complicated by faulting. Rotelliformis Zone.

M163 --------- 57-51-B108 through B110 Same as M162 except 108-110 ft (33-33.5 m) above base of section. Rotelliformis Zone.

M164 --------- 57-51-F130 Same as M162 except collected from a single float block at least 130 ft (40 m) above base of section. Rotelliformis Zone.

M165 --------- 57-51-B143 Same as M162 except 143 ft (43.5 m) above base of section. Rotelliformis Zone.

M166 --------- 57-51-B163 Same as M162 except 163 ft (50 m) above base of section. Meeki Zone.

M167 --------- 57-51-B180 through B182 Same as M162 except 180 ft (55 m) above base of section. Meeki Zone.

M533 --------- 58-3 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from

north wall of Big Canyon, 11,500 ft (350 m) N. 25° W. from BM 4964. Center of W1/2NW1/4 sec. 

14, T. 30 N., R. 34 E. Locality plotted on Wallace and others (1969). Hyatti Zone.

M605-M626 - - - 58-30-1 through 21 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Stratigraphically controlled

bedrock collections from collecting-site C (pi. 1) west side of south spur of Saurian Hill, north 

side of Troy Canyon. Approximately 4,500 ft±200 ft (1220±60m) S. 50-55° W. from SE corner 

of sec. 19, T. 28 N., R. 35 E. Localities plotted on pi. 3. Rotelliformis, Meeki, and Occidentalis 

Zones.

M627-M628 - - - 58-30-22, -23 Same as M605-M626 except from upper member of Prida Formation. Subasperum Zone.

M635--------- None Gilbert Creek SW Quadrangle, Augusta Mountains, Lander County, Nev. Wildhorse

quicksilver district. Float collections 3,000 ft (915 m) NW of Wildhorse Mine on north side of 

Wildhorse Mine road and then north along strike about 1,000 ft (300 m). Shoshonensis Zone.

M636 --------- None Cain Mountain Quadrangle, Augusta Mountains, Pershing County, Nev. Float collections

from high on north wall of Favret Canyon just below Tertiary volcanic rocks and about 2 mi 

(miles) (3.2 km) from mouth of canyon. NEV4 sec. 12, T. 25 N., R. 39 E. Fossil Hill Member of 

Favret Formation. Upper Anisian beds.

M905 --------- 59-W-815 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection 0.75 mi

(1.2 km) south of Indian Creek in gulch bottom, 600 ft (185 m) SE of center sec. 24, T. 29 N., R. 

34 E. Upper member of Prida Formation. Subasperum Zone. Collected by R. E. Wallace and 

D. B. Tatlock, 1959.

M907 --------- 58-7 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from

drainage bed of northwest tributary to Congress Canyon. Approximately 700 ft (210 m) due 

west of center sec. 16, T. 30 N., R. 34 E., and along strike at elevation 7,000 ft (2140 m). Upper 

member of Prida Formation. Locality plotted on Wallace and others (1969). Daonella lommeli 

beds.

M908 --------- 59-3 Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from

divide between heads of Peru and Jackson Canyons. Approximately 10,200 ft (3100 m) N. 71° 

E. from VABM 8882 in center of S ¥2 sec. 34, T. 30 N., R. 34 E. Upper member of Prida Formation. Locality plotted on Wallace and others (1969). Subasperum Zone.
16 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

TABLE 3. Triassic fossil localities in the Humboldt Range and vicinity, north-central Nevada Continued

USGS locality Field locality Description and collector(s)

M909

M911

M957

M958 ------

M959 ------

M960-M967

M968 

M969

M970

Ml 124 

M1180

M1181 

M1182

Ml 183 

Ml 184 

Ml 185

M2358

M2359

59-7

56-35

60-1

60-1+3 ft 

60-1+12 ft 

57-66-13 through 20

57-66 

None

None

58-2 

58-8

57-71 

61-21A

61-21B

61-21C 

57-5

64S-411

64S-412

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

Jackson Canyon, along road to Wheeler and Cottonwood Mines, approximately 400 ft (125 m) 

north of Wheeler Mine. South center sec. 34, T. 30 N., R. 34 E. Locality plotted on Wallace and 

others (1969). Occidentalis Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

north wall of American Canyon. Approximately 11,350ft (3450m) N. 13° W. from Saurian Hill 

(elevation-point 5852). Locality plotted on Wallace and others (1969). Subasperum Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from west 

side of south spur of Saurian Hill. Immediately north of collecting-site C (pi. 3). Meeki Zone.

Same as M957 except 3 ft (0.9 m) stratigraphically higher. 

Same as M957 except 12 ft (3.7 m) stratigraphically higher.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Stratigraphically controlled 

bedrock collections from collecting-site A (pi. 1) on south side of Fossil Hill between South 

American and Troy Canyons. Approximately 2,000 ft (600 m) NW from SE corner sec. 19, T. 28 

N., R. 35 E. Localities plotted on pi. 2. Rotelliformis, Meeki, and Occidentalis Zones.

Same locality as M960-M967 except single float-block collection. Meeki Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from north 

side of Congress Canyon, approximately 30 ft (9 m) above canyon bottom and 70 ft (22 m) 

above base of Fossil Hill Member of Prida Formation. NWViSE 1/* sec. 16, T. 30 N., R. 34 E. 

Locality plotted on Wallace and others (1969). Hyatti Zone.

Float collection from same locality as M969 except approximately 140 ft (43 m) above base of 

Fossil Hill Member of Prida Formation. Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from divide 

between Big and Coyote Canyons. SE Vi SE V4 N W V4 sec. 14, T. 30 N., R. 34 E. Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

crest of divide between Congress and Big Canyons. Center N 1/2SW 1/4 sec. 15, T. 30N., R. 34E. 

Locality plotted on Wallace and others (1969). Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

north side of John Brown Canyon. NWViSEViSEVi sec. 16, T. 30 N., R. 34 E. Locality plotted 

on Wallace and others (1969). Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Single float-block collection 

from crest of divide between main forks of Congress Canyon. South-central WV^SEViSWVi 

sec. 16, T. 30 N., R. 34 E. Hyatti Zone.

Same locality as M1182. Single float-block collection. Hyatti Zone. 

Same locality as M1182. Single float-block collection. Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from 

Congress Canyon. Center SEV4 sec. 16, T. 30 N., R. 34 E. Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from crest of 

intermediate spur between Star and Bloody Canyons, near range front. Approximately 150 ft 

(45 m) stratigraphically above base of Fossil Hill Member of Prida Formation. Center E Vz 

NWV4 sec. 26, T. 31 N., R. 34 E., 11,900 ft (3,620 m) N. 70.5° E. from VABM 9834 (Star Peak). 

Locality plotted on Silberling and Wallace (1967). Caurus Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Single float-block collection from 

crest of intermediate spur between Star and Bloody Canyons. Center WV^EV^NWVi sec. 26, T. 

31 N., R. 34 E., at approximately 11,750 ft (3,580 m) N. 70° E. from VABM 9834 (Star Peak) 

and 95 ft (29 m) above M2358. Hyatti Zone.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 17

TABLE 3. Triassic fossil localities in the Humboldt Range and vicinity, north-central Nevada Continued

USGS locality Field locality Description and collector(s)

M2362

M2367

M2369

M2819

M2821

M2826

M2828

M2829

M2830

M2836

M3093

M3094

M3095

M5481

64S-422

64S-434

64S-436

65S-412

65S-423

65S-461

65S-463

65S-464

65S-465

65S-484

58-30A

57-32

56-90X

None

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from crest of 

divide north of Coyote Canyon near range front. SE 1/4NE 1/4NW 1/4 sec. 2, T. 30 N., R. 34 E. 

Caurus Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collect/on from crest of 

divide south of Star Canyon. Same as bed M2358 except approximately 1,000 ft (300 m) farther 

north along strike. Caurus Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from crest of 

divide south to Star Canyon. Approximately 130-135 ft (39.5-41 m) stratigraphically above 

M2367. NWV4 sec. 26, T. 31 N., R. 34 E. Locality plotted on Silberling and Wallace (1967). 

Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from Star Canyon, approximately 0.4 mi (0.65 km) south of Sheba Mine. Center WV4SEV4SWV4 sec. 22, T. 

31 N., R. 34, E. Locality plotted on Silberling and Wallace (1967). Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from crest of 

spur north of Star Canyon, 245 ft (75 m) above base of Fossil Hill Member of Prida Formation. 

Center of south boundary of sec. 14, T. 31 N., R. 34 E. Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from crest of 

spur on south side of divide between Coyote and Bloody Canyons. Center S ¥2SEViSEVi sec. 

34, T. 31 N. R. 34 E. Locality plotted on Silberling and Wallace (1967). Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from Bloody 

Canyon approximately 0.25 mi (0.4 km) west of Bloody Canyon Mine and 100 ft (30 m) above 

base of Fossil Hill Member of Prida Formation. Center NVfeSEViNEVi sec. 34, T. 31N., R. 34 

E. Caurus Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Float collection from crest of 

divide between Coyote and Bloody Canyons approximately 0.3 mi (0.5 km) SW of Bloody Canyon Mine. Center NV&NEy4SEV4, sec. 34, T. 31 N., R. 34 E. Hyatti Zone.

Imlay Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from crest of 

divide between Coyote and Bloody Canyons approximately 0.3 mi (0.5 km) SW of Bloody Canyon Mine. NE 1/4NE 1/4SE 1/4, sec. 34, T. 31 N., R. 34 E. Locality plotted on Silberling and Wallace (1967). Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

crest of spur SE of John Brown Canyon approximately 0.5 mi (0.8 km) south of its mouth. 

SW 1/4SW1/4NE 1/4SW1/4 sec. 11, T. 30 N., R. 34 E. Locality plotted on Wallace and others 

(1969). Hyatti Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Float block from near M627 

on west side of ridge south of peak of Saurian Hill. Upper member of Prida Formation. 

Subasperum Zone.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection approximately 0.5 mi (0.8 km) east of Fossil Hill. Center EVaSE 1^ sec. 19, T. 28 N., R. 35 E. Upper 

member of Prida Formation. Locality plotted on Wallace and others (1969). Subasperum 

Zone.

Buffalo Mountain Quadrangle, Humboldt Range, Pershing County, Nev. Float from uppermost part of upper member of Prida Formation from south wall of Fisher Canyon approximately 80 ft (24 m) stratigraphically below base of Augusta Mountain Formation. 1,000 ft (300 

m) south of NE corner sec. 12, T. 27 N., R. 34 E.

Unionville Quadrangle, Humboldt Range, Pershing County, Nev. Bedrock collection from 

"1,000 ft [300 m] west of Arizona Mine, Unionville district." Upper member of Prida Formation. Subasperum Zone. Collected by F. N. Johnson, 1932.
18 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Sageceras waiter! Mojsisovics

Plate 5, figures 10-12

Sageceras walteri Mojsisovics, 1882, p. 187, pi. 53, figs. 9a-9c 

[holotype], lla-llb?, 12a-12b?, 13? Spath, 1934, p. 56, 58-59.

Sageceras gabbi Mojsisovics. Hyatt and Smith, 1905, pi. 74, figs. 8-9; 

pi. 75, figs. 14-15. Smith, 1914, pi. 11, figs. 8-9; pi. 12, figs. 14-15; 

pi. 21, figs. 18-20. Silberling, 1962, p. 156.

This species occurs sporadically through most or all of 

the upper Anisian in the vicinity of Fossil Hill. The 

stratigraphically lowest specimen collected from bedrock 

is from the Paraceratites vogdesi beds of the Itotelliformis Zone, and the highest specimen was found as 

float derived from the Occidentalis Zone or higher.

The better preserved specimens from the upper Anisian of Fossil Hill described and illustrated as S. gabbi 

Mojsisovics by Hyatt and Smith (1905) and Smith 

(1914) are from the same general locality and perhaps 

from the same part of the stratigraphic section as the 

specimens on which Gabb based the concept that 

Mojsisovics named S. gabbi. S. gabbi is suppressed here 

as a nomen dubium and the specimens of Sageceras from 

the Middle Triassic of the Humboldt Range are assigned 

to the Alpine Middle Triassic species S. walteri 

Mojsisovics. Some Nevada specimens were assigned to 

S. walteri by Spath (1934, p. 56, 59) despite the priority 

of the name S. gabbi.

The separation of Middle Triassic forms assigned here 

to S. walteri from the typically Upper Triassic S. 

haidingerii (Hauer, 1847) is a further problem. As 

pointed out by Spath (1934, p. 58-60), the latter species 

seems to be distinguished by a wider umbilicus with an 

abrupt umbilical rim bordered by a spiral depression, 

but these differences have not been positively 

demonstrated.

Figured specimen. Plesiotype, USNM 248641.

Occurrence. USGS localities M965 (1), Paraceratites 

burckhardti beds; M139 (1), Paraceratites clarkei beds; 

M607 (3), Paraceratites cricki beds, Rotelliformis Zone; 

M963 (1), Parafrechites meeki beds; M618 (1) Parafrechites dunni beds, Meeki Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

Superfamily DINARITACEAE (Mojsisovics, 1882)

Family DINARITIDAE

Subfamily DINARITINAE

Genus KOIPATOCERAS, n. gen.

Type species. Koipatoceras discoideus n. sp. 

Definition. Typically small shells; evolute, compressed discoidal in shape with narrow, sharply truncate

venter. Smooth or with traces of falcoid ribbing on flanks 

and at ventral-lateral shoulder. Suture subammonitic; 

VL shallow, LI pronounced; only two lateral lobes.

Discussion. Though only three specimens from the 

Hyatti Zone serve as the basis for this new genus and 

species, they embody a unique combination of shell 

characters that sets them apart from any other known 

Middle Triassic ammonites. The discoidal shape, truncate venter, and simple suture pattern of Koipatoceras 

suggests relationship with the Spathian genus Stacheites 

Kittl, which is included in the subfamily Dinaritinae by 

Tozer (1971). As compared with the type species of 

Stacheites from Yugoslavia and with Stacheites from the 

Prohungarites and Subcolumbites beds of Nevada, 

Koipatoceras, as presently known, is more evolute, more 

ornate, and has a more coarsely subdivided suture.

The name of this new genus is derived from 

"Koipato," a transliteration of the Piute Indian name for 

the Humboldt Range (King, 1878, p. 269).

Koipatoceras discoideus n. sp. 

Plate 4, figures 3-10; text-figure 7

The general characters of this species are those that 

define the genus. Only three specimens were collected, 

probably all from the same bed, but these illustrate different stages of variation in strength of ornamentation, 

which is inversely proportional to the whorl compression. 

The holotype, the largest of the specimens and having a 

greatest diameter of 24 mm, is the most compressed 

(W/D about 0.20) and is ornamented only by weak radial 

folds on the flanks. Its truncate venter is slightly concave 

between sharp, ridgelike ventral-lateral margins. On the 

two paratypes, ribbing is marked by sinuous swellings or 

bullae on the lower flank and by serrations of the ventral 

lateral shoulder, which have the form of alternating clavi 

on the more coarsely ornamented of the two.

A

FIGURE 7. Suture line (X 5) of Koipatoceras discoideus n. sp. 

Holotype, USNM 248631.

The abbreviated external suture line of this species, 

which has only two lateral lobes and saddles, may be a 

consequence of the evolute coiling (U/D of holotype 0.31) 

and whorl height, which is relatively low considering the 

compressed shape of the shell. Both lateral saddles are
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 19

weakly crenulate with a few pronounced crenulations on 

the ventrad side of SI; the lobes are coarsely digitate, 

and the depth of LI is about twice that of L2. The broad, 

shallow ventral lobe is only about one-fourth the depth 

of LI and is divided into two points by a low ventral 

saddle.

Figured specimens. Holotype, USNM 248631; 

paratypes, USNM 248629 and 248630.

Occurrence. USGS Mesozoic localities M1180 (1) 

and M1184 (2); Hyatti Zone on ridge between Congress 

and Big Canyons, Humboldt Range, Nev.

Subfamily KHVALYNITINAE Shevyrev, 1968

Genus ALANITE8 Shevyrev, 1968

Alanites mulleri n. sp.

Plate 29, figures 31-35; text-figure 8

Dagnoceratid, n. gen., n. sp. A. Silberling and Wallace, 1969, p. 17, 

table 1.

Description. Compressed (W/D 0.30-0.35 at D > 15 

mm); moderately involute (U/D 0.16-0.18). Maximum 

size exceeding 70 mm.

Flanks flattened; parallel on inner whorls; convergent 

ventrally from abrupt, narrowly rounded umbilical 

shoulders on outer whorls. Umbilical margin slightly 

flaring on body chamber. Venter broadly rounded, 

delimited from flanks by narrowly rounded ventrolateral shoulders. Width of venter about 0.15 of shell 

diameter. Umbilical wall roughly perpendicular to 

flanks.

Ornamentation varies from falcoid growth striae of irregular strength to blunt, foldlike falcoid ribs that are 

most prominent on lower flanks. Closely spaced (about 

3/mm) fine strigae on outer shell surface of mature shell.

Suture as for the genus; details of secondary subdivision variable; SI and S2 of about equal size, asymmetrically triangular in gross shape on inner whorls, 

becoming rounded and elongate (about twice as long as 

wide) on outer whorls (fig. 8).

Discussion. The holotype, having a maximum 

preserved diameter of about 70 mm, is the largest 

specimen and is septate to an estimated diameter of 

about 40 mm.

This species differs from A. obesus primarily in its 

much less robust whorl proportions. From the same loose 

block from which the type specimens of this species were 

collected, one small specimen having the same external 

form and ornamentation has a much more advanced 

suture as illustrated in figure 8D and in this way resembles typical Ismidites rather than Alanites. Alanites

mulleri is named in honor of the late Prof. Siemon W. 

Muller of Stanford University.

Figured specimens. Holotype, USNM 248903; 

paratypes, USNM 248901 and 248902.

Occurrence. USGS localities M533 (3?), M969 (1); 

Mesozoic localities M1181 (1?), M2359 (50+; mostly 

small specimens), M2830 (1?), Hyatti Zone, northeastern part of Humboldt Range, Nev.

D

FIGURE 8. Sutures lines (X 3) ofAlanites mulleri n. sp. A, paratype, 

USNM 248902. B, paratype, USNM 248901. C, holotype, USNM 

248903, dotted where inferred. D, paratype, USNM 248963, 

specimen not figured.

Alanites obesus n. sp.

Plate 28, figures 21-25; text-figure 9

Description. Thick discoidal (W/D 0.5-0.6); 

moderately evolute (U/D about 0.2). Maximum size exceeding 100 mm.

Inner whorls subquadrate; outer whorls compressed 

subtrapezoidal. Flanks flattened, becoming concave 

near raised, narrowly rounded umbilical margin. Umbilical wall approximately perpendicular to adjacent 

part of flank. Venter broadly rounded, about equal in
20 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

width to whorl height on inner whorls, becoming 

relatively narrow (about 0.5 of whorl height at a 

diameter of 100 mm) with increasing shell size. Ventrolateral shoulders on inner whorls abrupt, with low, 

rounded carina; on outer whorls narrowly rounded.

Weak foldlike ribs, swollen on lower flanks and at 

ventro-lateral shoulders at diameters of 25-30 mm on 

holotype. Traces of strigation impressed on internal 

mold.

Suture as for the genus; at a height of 10 mm on the 

holotype SI and S2 bluntly rounded in general shape; 

subammonitic with relatively large-scale subdivisions on 

the ventral side of SI.

Discussion. The above description is based on only 

two specimens, both internal molds, whose maximum 

diameters are about 30 and 100 mm. Though similar in 

most respects to A. mulleri, the much broader whorls of 

these specimens justify establishing a separate species 

for them. The larger specimen is septate to an estimated 

diameter of about 50 mm; its suture (not illustrated) 

could be only partly exposed, but, in agreement with 

that of the smaller holotype, the width of its lanceolate 

lateral lobe is about 0.4 of the whorl height.

Another specimen, 22 mm in diameter, from USGS 

Mesozoic locality M2829 in the upper part of the Hyatti 

Zone near Bloody Canyon (Silberling and Wallace, 1969) 

may belong to this species with which it agrees closely in 

shape and proportions but from which it differs in having 

much stronger ornamentation consisting of regular 

falcoid ribs that are swollen on the lower flanks and 

enlarged into blunt tubercles on the ventro-lateral 

shoulders.

Figured specimens. Holotype, USNM 248885; 

paratype, USNM 248886.

Occurrence. USGS locality M533 (2); USGS 

Mesozoic locality M2829 (1); Hyatti Zone, Humboldt 

Range, Nev.

FIGURE 9. Suture line (X 3) of Alanites obesus n. sp. Holotype, 

USNM 248885.

Genus ISMIDITES Arthaber, 1915 

Ismidites aff. I. marmarensis Arthaber

Plate 28, figures 19-20; text-figure 10 

aff. Ismidites marmarensis Arthaber, 1915, p. 185, pi. 15, figs. lOa-c.

The whorl shape and suture of a somewhat eroded 

specimen having a maximum preserved diameter of 49 

mm, from the upper part of the Hyatti Zone at USGS 

locality M970 is more likely that of Ismidites marmarensis as described and illustrated by Arthaber than 

that of the apparently closely related new species of 

Alanites described here. Like I. marmarensis, the 

rounded venter of this specimen grades evenly into the 

flanks without abrupt change in curvature, and its umbilicus, which is sharply set off from the flanks, is 

relatively narrow (U/D 0.12). Its suture (fig. 10), though 

similar to that of A. mulleri, differs in having the tip of 

its first lateral saddle drawn out into an elongated projection which is one-half or less the width of the second 

saddle. Perhaps owing to the eroded nature of the shell, 

the peculiar proportions of its first lateral saddles are 

not, however, as extreme as those typical of /. marmarensis.

Figured specimen. Plesiotype, USNM 248884.

Occurrence. USGS locality M970 (1), upper Hyatti 

Zone, northwestern part of the Humboldt Range, Nev.

FIGURE 10. Suture line (X 3) of Ismidites aff. /. marmarensis 

Arthaber. Plesiotype, USNM 248884.

Superfamily MEGAPHYLLITACEAE (Mojsisovics, 1896)

Family PARAPOPANOCERATIDAE Tozer, 1971

Genus AMPHIPOPANOCERAS Voinova, 1947

Amphipopanoceras selwyni (McLearn)

Parapopanoceras selwyni McLearn, 1948, p. 1, pi. 9, figs. 7-9. 

Parapopanoceras testa McLearn. McLearn, 1969, p. 46, pi. 9, figs. 

1, 2 (only).

Amphipopanoceras cf. A. selwyni (McLearn)

Plate 6, figures 15, 16; text-figure 11

Only one specimen of a parapopanoceratid has been 

discovered in the Middle Triassic of the Humboldt 

Range. The recognition of the species A. selwyni, the 

species to which this specimen is compared, and its inclusion in the genus Amphipopanoceras follows E. T. 

Tozer (written commun. 1974).

Figured specimen. Plesiotype, USNM 248648.

Occurrence. USGS Mesozoic locality M2829 (1); up-
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 21

FIGURE 11. Suture line (X 4) of Amphipopanoceras cf. A. selwyni 

(McLearn). Plesiotype, USNM 248648.

per part of Hyatti Zone on the divide between Coyote 

and Bloody Canyons, Humboldt Range, Nev.

Family MEGAPHYLLITIDAE Mojsisovics, 1896 

Genus HUMBOLDTITES, n. gen.

Type species. Megaphyllites septentrionalis Smith, 

1914.

Diagnosis. Involute; inner whorls robust, subquadrate in outline; outer whorls thick discoidal with 

flattened parallel flanks and arched venter. Inner whorls 

smooth except for delicate radial striae; outer whorl ornamented by radial constrictions and ridges of uneven 

spacing and strength. Suture ammonitic with six or more 

lateral lobes forming a slightly retracted series; saddles 

progressively decrease in height inwards; principal saddles elongate, tend to be constricted at their bases, 

crenulate or digitate throughout with no second and 

third order subdivisions.

Discussion. The single species for which this genus is 

established was originally included in Megaphyllites, 

but, as noted by Spath (1951, p. 139), it differs from 

typical members of that genus in having a more ammonitic suture with crenulate rather than monophylletic 

terminations of the saddles. The suture of Hum boldtites 

also differs from that of the other genera included in the 

Megaphyllitacea like Parapopanoceras and Neopopanoceras, which are characterized by simple phylloid saddles. Nevertheless, in the general shape of its saddles 

and pattern of its suture, Humboldtites is more like the 

megaphyllitids than any of the arcestacids, and it is 

therefore included in the Megaphyllitidae.

Humboldtites septentrionalis (Smith) 

Plate 28, figures 3-9; text-figure 12

Megaphyllites septentrionalis Smith, 1914, p. 42, pi. 21, figs. 4-5

[holotype], 6, 7-9, 10-12. 

"Megaphyllites" septentrionalis Smith. Silberling, 1962, p. 157.

To the general generic diagnosis several morphologic 

details can be added for this species, which was found 

only in the Nevadites beds.

The whorls of some of the robust (W/D 0.55-0.65) 

young shells having diameters less than 15 mm increase 

regularly in size whereas others have approximately 

three contractions and bulbous expansions of the shell

during each volution. All gradations in the intensity of 

this irregular growth seem to exist. Larger shells more 

than 25 mm in diameter have a more strongly arched 

venter in comparison with the subquadrate inner whorls 

and are more compressed (W/D about 0.45). The largest 

specimen collected has part of the body chamber and is 

36 mm in diameter. On the venter of this specimen near 

the broken orad end of its final whorl there is irregular 

closely spaced strigation in addition to the radial ornament, which is slightly convex on the flanks and most 

pronounced on the venter.

Figured specimens. Plesiotypes, USNM 248879 to 

248881.

Occurrence USGS localities M144 (1), M620 (3), 

and M962 (9), lower part of Occidentalis Zone, vicinity 

of Fossil Hill, Humboldt Range, Nev.

FIGURE 12. Suture lines of Humboldtites septentrionalis (Smith). A, 

plesiotype (X 4), USNM 248880. B, plesiotype (X 6.6), USNM 

248881.

Superfamily CERATITACEAE (Mojsisovics, 1879)

Family ACROCHORDICERATIDAE Arthaber, 1911

Genus PARACROCHORDICERAS Spath, 1934

Paracrochordiceras americanun McLearn

Plate 29, figures 1-9

Acrochordiceras (Paracrochordiceras) americanum McLearn, 1946b, p. 

3, pi. 5, fig. 1. McLearn, 1969, p. 12, pi. 1, figs. 1-3.

Figured specimens. Plesiotypes, USNM 248887 to 

248890.

Occurrence. USGS Mesozoic localities M2358 (9), 

M2362 (1?), M2367 (3), M2828 (1?); Caurus Zone 

between Coyote and Star Canyons, Humboldt Range, 

Nev.

Acrochordiceras hyatti Meek, 1877

Plate 4, figures 11-28; 

Plate 5, figures 1-7; text-figure 13

Acrochordiceras hyatti Meek [in part], 1877, p. 124, pi. 11, fig. 5a 

[herein selected as lectotype] [not fig. 5]. Hyatt and Smith, 1905,
22 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

p. 178 [not pi. 23, figs. 8-11]. Smith, 1914, p. 39, pi. 15, fig. 5a [not

pi. 4, figs. 8-11, pi. 15, fig. 5]. 

Haydenites hatschekii Diener, Smith, 1914, p. 114, pi. 33, figs. 1-3. [?]

Haydenites hatschekii Diener, 1907, p. 72, pi. 6, figs, la-lb. 

[not] Acrochordiceras hyatti Meek. Spath, 1934, p. 394, text-figure

137a-c. 

[not] Acrochordiceras sp. aff. A. hyatti Meek. Tozer, 1972, p. 32, pi. 10,

figs. 11-13.

Description. Thick discoidal; inner whorls 

moderately evolute (U/D 0.30-0.40), outer whorls more 

involute (U/D about 0.25). Whorl shape and proportions 

widely variable, changing with increasing shell 

diameter. Cross section of inner whorls circular, at larger 

diameters ranging from compressed to depressed with 

gently to sharply rounded ventral and umbilical 

shoulders. Final whorl subquadrate with flattened, 

nearly parallel flanks and broadly rounded venter. Maximum diameter exceeding 150 mm.

Ornamentation modified with growth, varying in 

strength and ontogenetic development. On inner whorls 

ribs regularly spaced, nearly straight on flanks, swing 

slightly forward and pass over venter with or without interruption. Ribbing on phragmocone generally passes 

through distinct ontogenetic stages: first, ribs decrease 

in strength on venter, tend to alternate in position across 

venter, and may even crisscross on venter; next, ribbing 

becomes strong on venter passing straight across; finally, 

ribs fade on venter and again tend to alternate on either 

side. Duration and shell diameter of each ontogenetic 

stage widely variable.

On body chamber lateral ribs terminate in slightly 

projected ventral-lateral swellings proportional in size to 

strength of early ornamentation. Widely spaced tubercles or bullae develop at small diameter at or just below 

midline of flank, form point of origin for two or three 

ribs, and are separated by two to five intercalated ribs 

depending on strength of ribbing. Persistence of tubercles with growth widely variable: tubercles on some 

variants weakly developed and absent at shell diameters 

exceeding 20 mm; on more coarsely ornamented variants 

lateral tubercles may persist to beginning of body 

chamber at large diameter. Strength and persistence of 

tubercles proportional to persistence of rounded shape of 

inner whorls with increasing shell diameter.

Suture ceratitic, nearly subammonitic; principal elements elongate. SI and S2 of equal height with clubshaped rounded crests but with weak crenulations extending high on sides. LI coarsely digitate. VL about 

two-thirds depth of LI; prongs on either side of ES subdivided. One auxiliary saddle external to umbilical 

shoulder.

Discussion. The two syntypes of Acrochordiceras 

hyatti illustrated by Meek (1877, pi. 11, figs. 5 and 5a) 

differ from one another, and specimens of these two 

kinds do not occur in the same populations in Nevada.

The morphologic characters of the syntype illustrated by 

Meek's figure 5 are known only in specimens from the 

Hyatti Zone, whereas those of the other syntype, Meek's 

figure 5, distinguish the kind of Acrochordiceras found 

in the Shoshonensis Zone near the base of the Fossil Hill 

Member of the Favret Formation several tens of 

kilometers southeast and east of the Humboldt Range in 

the New Pass Range, Augusta Mountains, and southern 

Tobin Range (Nichols and Silberling, 1977).

Population samples of Acrochordiceras from each of 

these two zones show a wide range of variation, but little, 

if any, morphologic overlap exists between them. In 

comparison with those from the Shoshonensis Zone, 

those from the Hyatti Zone include specimens having 

more loosely coiled whorls, which tend to be rounded in 

cross section rather than thickest near the umbilicus, 

tubercles that are located laterally or well up on the 

lower flank rather than near the umbilical shoulder, and 

a less subdivided suture pattern. Meek's original 

description of A. hyatti clearly refers to the kind of 

Acrochordiceras that occurs in the Hyatti Zone, as he 

describes the lateral tubercles as being "near or within 

the middle of each side" and attributes the umbilical 

position of the tubercles on the specimen illustrated by 

his figure 5 as probably being due to distortion (Meek, 

1877, p. 124). Consequently, the syntype (Meek, 1877, 

pi. 11, fig. 5a) most closely agreeing with Meek's 

characterization of the species is selected here as the lectotype of A. hyatti, and this specific name is applied to 

the specimens described here from the Hyatti Zone of 

the Humboldt Range.

Because of the wide morphologic variation shown by 

population samples of Acrochordiceras from the 

Shoshonensis Zone, the other syntype of A. hyatti 

(Meek, 1877, pi. 11, fig. 5) can be compared with several 

previously described European species.

Acrochordiceras damesi Noetling (1880) is the oldest 

name for specimens having this kind of ornamentation 

and whorl shape, but as originally drawn, the suture of 

this species differs from that of other Acrochordiceras in 

having a broad, shallow, first lateral lobe and slender 

saddles whose sides converge toward their crests (Diener, 

1907, p. 100). Though these differences may simply be 

due to a faulty restoration, until more information is 

available, the specimens from the Shoshonensis Zone in 

Nevada are provisionally referred to A. carolinae 

Mojsisovics, 1882, the next most prior name. A partial 

list of possibly synonymous names, judging from the 

wide variation shown by Acrochordiceras cf. A. carolinae 

from Nevada, would include Acrochordiceras fischeri 

Mojsisovics, A. haueri Arthaber, A. pustericum 

Mojsisovics, and A. undatum Arthaber.

The syntype of A. hyatti (Meek, 1877, pi. 11, fig. 5), 

here assigned to A. cf. A. carolinae, is illustrated by 

figures 8 and 9, on plate 5. The suture of A. cf. A.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 23

carolinae, text-figure 14, is subammonitic with incipient 

crenulation of the crests of the principal saddles and 

some second-order subdivision of the first lateral lobe.

The specimen from the Whitney Collection in the 

Museum of Comparative Zoology, Harvard University, 

on which Hyatt and Smith (1905), Smith (1914), and 

Spath (1934) based their concept of A. hyatti is of the 

kind assigned here to A. cf. A. carolinae. The locality of 

this and some other specimens from the Whitney Collection is given as "the Shoshone Mountains, Nevada," 

which may refer to the New Pass Range as suggested by 

Smith (1914, p. 239) L

The only locality given by Meek (1887, p. 126) for A. 

hyatti is "New Pass, Desatoya Mountains [New Pass 

Range], Nevada." In the New Pass Range, specimens 

like Meek's syntype that is assigned here to A. cf. A. 

carolinae occur, along with an abundance of other ammonites characteristic of the Shoshonensis Zone, in float 

collections made near the base of the fossiliferous Middle 

Triassic section. However, ammonites like those from 

the upper part of the Hyatti Zone in the Humboldt 

Range are also represented in some collections, and thus 

the lectotype of A. hyatti, which is like specimens 

elsewhere restricted to the Hyatti Zone, could have been 

obtained from this level in the New Pass Range, 

although the stratigraphic relations are unclear. As the 

40th Parallel exploration (King, 1878) collections 

studied by Meek include specimens from both the New 

Pass and Humboldt Ranges, it is also possible that 

Meek's locality is in error and that the lectotype of A. 

hyatti was actually collected in the Humboldt Range.

The character of the body chamber of Acrochordiceras 

was evidently unknown at the time that Diener (1907) 

established the genus Haydenites. The large specimen illustrated by Diener as the type species, H. hatschekii, 

appears to be nothing more than a fully developed 

Acrochordiceras showing the peculiar modification of the 

body chamber. Haydenites hatschekii, as originally 

described from the Middle Triassic of India, generally 

agrees with Acrochoridiceras hyatti in ornamentation, 

suture, whorl shape, and modification of the shell with 

growth, and the two species are at least congeneric. The 

lectotype of A. hyatti is nearly identical with the corresponding part of the larger of the two specimens from 

the Humboldt Range figured by Smith (1914, pi. 33, figs. 

1-2) as Haydenites hatschekii.

Two other species of Acrochordiceras, A. foltsense and 

A. alternans, were described by Smith (1914, p. 38-39) 

from the Humboldt Range. The former species is based 

on a single specimen from the Upper Anisian at Fossil 

Hill and may be a pathologic Gymnotoceras as suggested 

by Spath (1934, p. 393). Acrochordiceras alternans, on 

the other hand, appears to be an Acrochordiceras and 

resembles A. hyatti in having a growth stage marked by 

weakening and alternation of the ribs on the venter.

However, the two specimens assigned to A. alternans by 

Smith are more involute than any of the Acrochordiceras 

from the Hyatti Zone, and they might represent a 

stratigraphically distinct population, possibly transitional between A. hyatti and A. cf. A. carolinae.

Figured specimens. Lectotype, USNM 12514 

(originally figured by Meek, 1877, pi. 11, fig. 5a); 

plesiotypes, USNM 248632 to 248640.

Occurrence. USGS localities M533 (20+), M970 (3); 

USGS Mesozoic localities M1124 (2), M1180 (12+), 

M1181 (5), M1184 (3), M2819 (10), and M2829 (12+); 

Hyatti Zone between Buena Vista and Star Canyons on 

east side of Humboldt Range, Nev.

B

FIGURE 13. Suture lines (X 2) of Acrochordiceras hyatti Meek. A, 

plesiotype, USNM 248983, specimen not figured. B, plesiotype, 

USNM 248638.

FIGURE 14. Suture line (X 2) of Acrochordiceras cf. A. carolinae 

Mojsisovics. Plesiotype, USNM 248984.

Family BALATONITIDAE Spath, 1951

Oenus CUCCOCERAS Diener, 1905 

Cuccoceras bonaevistae (Hyatt and Smith)

Plate 20, figures 1-12; text-figure 15

Dinarites bonae-vistae Hyatt and Smith, 1905, p. 162, pi. 60, figs. 1-4

[holotype], 6-7. 

Cuccoceras bonae-vistae (Hyatt and Smith). Smith, 1914, p. 71, pi. 10,

figs. 1-4, 6-7.

This species is well represented in the Hyatti Zone of 

the Humboldt Range. Allowing for some variation in the 

strength and density of the ribbing and in the spacing of 

the periodic constrictions, the inner whorls are adequately characterized in Hyatt and Smith's original
24 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

description. Attention is drawn, however, to the peculiar 

modification of the ornamentation on the outer whorl.

As the shell increases in diameter beyond about 25 

mm, the ribs bordering the apicad side of each constriction become enlarged and develop a slight forwarddirected bend at or above the midflank. With further increase in shell size, generally at diameters exceeding 40 

mm, tubercles develop at the point of bending and 

ultimately extend forward across the constriction, joining with the next orad rib. Thus, on the body chamber of 

the adult shell, the ribs bordering the pronounced constrictions pass more or less straight across the venter and 

then coalesce in tubercles, which interrupt the constrictions on the upper flank. On the flanks below the tubercles the constrictions are less conspicuous and continue 

to the umbilical margin following a prosiradiate course. 

Accompanying this change in ornament, the whorls 

become thicker and the venter more broadly rounded.

Figured specimens. Holotype, USNM 74383 

(originally figured by Hyatt and Smith, 1905, pi. 60, figs. 

1-4); plesiotypes, USNM 248786 to 248789.

Occurrence. USGS localities M533 (25+), M969 (4); 

USGS Mesozoic localities M1124 (10+), M1181 (5), 

M1182 (3), M1184 (2), M2359 (50+), M2821 (5), M2829 

(2), M2830 (5), and M2836 (5); Hyatti Zone, 

northeastern Humboldt Range, Nev.

FIGURE 15. Suture line (X 3) of Cuccoceras bonaevistae (Hyatt and 

Smith). Plesiotype, USNM 248786.

Family CERATITIDAE Mojsisovics, 1879

Subfamily BEYRICHITINAE (Spath, 1934)

Genus NICOMEDITES Toula, 1896

Nicomedites sp.

Plate 6, figures 9-11; text-figure 16

One specimen of a beyrichitid, whose distinction lies 

in its rather featureless character, was collected from the 

Hyatti Zone. The incomplete shell has a maximum 

diameter of 36 mm, is involute (U/D about 0.14) and 

compressed discoidal (W/D about 0.35) in shape, and 

has flattened flanks that converge to an evenly rounded, 

blunt venter. Only weak falcoid folds are visible on the 

flanks of the otherwise smooth shell. The suture is 

ceratitic, nearly subammonitic, with incipient crenulations high on the sides of the somewhat asymmetric saddles and with coarsely digitate lobes.

The suture line of this specimen is generally like that

of Hollandites aff. H. voiti collected from approximately 

the same stratigraphic level, but its tight coiling and 

weak ornamentation differ from those characteristic of 

Hollandites. Beyrichites has been applied in a broad 

sense to various similar unspecialized beyrichitids but it 

typically has a subtrigonal whorl cross section with a 

narrowly arched venter and has a rather advanced suture 

line. Of the recognized genera of beyrichitids, 

Nicomedites seems most applicable to involute shells 

that have an unmodified whorl shape and a relatively 

simple suture pattern like that of the present specimen.

Figured specimen. USNM 248646.

Occurrence. USGS locality M533 (1); Hyatti Zone, 

between Big and Coyote Canyons, Humboldt Range, 

Nev.

FIGURE 16. Suture line (X 3) of Nicomedites sp. Figured specimen, 

USNM 248646.

Genus HOLLANDITES Diener, 1905 

Hollandites voiti (Oppel)

Ammonites voiti Oppel, 1863, p. 276, pi. 77, fig. 1.

Ceratites voiti (Oppel). Diener, 1895, p. 8, pi. 2, figs, la-lb, 2a-2b

[holotype]. 

Ceratites (Hollandites) voiti (Oppel). Diener, 1907, p. 60, pi. 7, figs.

3a-3b, 4.

Hollandites aff. H. voiti (Oppel) 

Plate 6, figures 1-6; text-figure 17

Hollandites sp. Silberling and Wallace, 1969, p. 17, table 1.

Hollandites is represented from the Hyatti Zone by 

about 20 specimens, most of which are immature. The 

ontogenetic variation and ontogenetic development is 

not adequately shown by these specimens; though they 

differ in some details of their suture and ornamentation 

from previously described species of Hollandites, they 

are generally similar to the type species, H. voiti (Oppel).

The largest unbroken specimen (pi. 6, figs. 3-5), having a greatest diameter of 71 mm, shows the compressed 

discoidal shape (W/D about 0.25), excentrumbilicate 

(U/D of outer whorl 0.31) high whorls, and smooth, 

rounded venter characteristic of Hollandites. About onehalf of the outer whorl of this specimen represents the 

body chamber. The ceratitic suture, with slender,
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 25

somewhat asymmetric saddles, agrees in plan and degree 

of complexity with that of Hollandites. The broad, deep 

first lateral lobe is much larger than the second lateral 

lobe, the second lateral saddle is slightly higher than the 

first lateral saddle, and of the three auxiliary saddles 

only the outermost is prominent.

Inner whorls, like the specimen illustrated by figures 1 

and 2 on plate 6, are ornamented by regular, nontubercular, somewhat sigmoidal ribs that arise at the umbilical shoulder or by intercalation, cross the flanks with 

uniform strength, and then fade where they are projected 

strongly forward on the ventral-lateral shoulder. Some 

more strongly ornamented small specimens develop 

weak umbilical bullae on the primary ribs.

With increasing shell size, the ribbing is reduced to 

slightly convex folds, which are restricted to the middle 

part of the flanks and fade ventrally by branching into 

striae that swing sharply forward onto the venter. This 

style of ornamentation differs somewhat from that of 

typical Indian representatives of Hollandites whose ribs 

on the outer whorls tend to develop umbilical or lateral 

tubercles and to extend to the ventral-lateral shoulders 

where they are commonly emphasized as projected swellings. However, the large whorl fragment illustrated by 

figure 6 on plate 6 has coarse simple ribs that are most 

pronounced near the middle of the flank and at the 

ventral-lateral shoulder. The ribbing of this fragment, 

from the same block of matrix as the other two 

specimens of Hollandites illustrated on plate 6, is like 

that characteristic of the final whorl of typical Hollandites.

The specimens from the upper Anisian of the Humboldt Range assigned by Smith (1914) to Hollandites, 

i.e., those he included in "Ceratites (Hollandites)" 

montis-bovis and "C. (H)" organi Smith, possess the 

subammonitic suture, whorl shape, ornamentation, and 

keeled venter of younger genera of beyrichitids and are 

regarded here as variants of Parafrechites meeki, 

revised, and Frechites occidentalis, revised.

Figured specimens. Plesiotypes USNM 248642 to 

248644.

Occurrence. USGS localities M969 (5), M533 (6+); 

USGS Mesozoic localities Ml 180 (5), M1181 (2), and 

M2836 (1); Hyatti Zone, vicinity of Congress Canyon, 

Humboldt Range, Nev.

FIGURE 17. Suture line (X 3) of Hollandites aff. H. voiti (Oppel). 

Plesiotype, USNM 248643.

Genus ANAGYMNOTOCERAS McLearn 

?Anagymnotoceras moderatum (McLearn)

Plate 6, figures 7-8

Gymnotoceras moderatum McLeam, 1948, p. 3, pi. 10, fig. 10. 

Anagymnotoceras moderatum (McLearn). McLearn, 1966, pi. 1, fig. 8. 

Anagymnatoceras aff. A. moderatum (McLearn). Silberling and Wallace, 1969, table 1, p. 17.

Figured specimen. Plesiotype USNM 248645. 

Occurrence. USGS Mesozoic locality M2822 (2); 

Hyatti Zone, northern Humboldt Range, Nev.

Genus GYMNOTOCERAS Hyatt, 1877

Gymnotoceras Hyatt in Meek, 1877, p. 110 [type species Ammonites 

blakei Gabb, 1864, by original designation].

Revised description. Discoidal, compressed; 

moderately involute. Cross-sectional shape of 

phragmacone whorls subtrigonal with acutely rounded 

periphery. On body chamber periphery becomes broadly 

rounded to subtabulate near the aperture.

Ribbing nearly absent to strong, decreasing in 

strength on outer whorl. Ribs falcoid or projected, may 

branch or intercalate on lower flanks or have weak 

lateral bullae and faint marginal swellings. Bluntly 

rounded keel on strongly ornamented inner whorls.

Suture typically subammonitic with rounded 

crenulate saddles. First lateral lobe broad, deeper than 

ventral lobe, roughly twice as deep as second lateral 

lobe. Ventral lobe divided by low, generally triangular, 

ventral saddle. First lateral saddle broader and as high 

as or higher than second lateral saddle. One or two auxiliary saddles external to umbilical shoulder.

Discussion. Ammonites of the genera Gymnotoceras, 

Parafrechites, and Frechites are among the best 

represented in collections from the Fossil Hill area. 

Stratigraphically controlled samples totalling nearly 

2,000 specimens were collected either from bedrock or 

from single loose weathered blocks and represent different levels throughout the upper Anisian.

Only two intergrading Stratigraphically restricted 

species of Gymnotoceras occur in the Fossil Hill area as 

the scope of Gymnotoceras is herein changed from 

former usage by Silberling (1962), Silberling and Tozer 

(1968), and Silberling and Wallace (1969). Allowing for a 

certain amount of variation in ornamentation, whorl 

shape, and degree of compression, Gymnotoceras is distinguished from other ceratitacids by its narrowly 

rounded phragmocone periphery. The generic names 

Philippites and Beyrichites have also been applied to 

ammonites from Fossil Hill here included in Gymnotoceras, but for the typical examples of neither of
26 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

these genera, which might be junior synonyms of Gymnotoceras, is the shape and ornament of the inner whorls 

sufficiently well known.

Gymnotoceras rotelliformis Meek

Plate 7, figures 1-27; plate 8, figures 1-5

Gymnotoceras rotelliforme Meek, 1877, p. Ill, pi. 10, figs. 9-9a. 

Beyrichitesrotelliformis (Meek). Hyatt and Smith, 1905, p. 155, pi. 23,

figs. 1-2, 3-5, 6-7a; pi. 58, figs. 1-4?, 5-6, 7-9?, 10-12?, 13-15?.

Smith, 1914, p. 118, pi. 4, figs. 1-2, 3-5, 6-7a; pi. 8, figs. 1-4?, 5-6,

7-9?, 10-12?, 13-15?; pi. 14, figs. 9-9a; pi. 31, figs. 1-2?, 3-4, 5-6?;

pi. 91, figs. 1-2, 3-4?, 5-7, 8?, 9-10?. Spath, 1934, p. 422. 

Ceratites (Philippites) argentarius Smith, 1914, p. 107, pi. 63, figs. 1-3

[holotype], 4-6, 7-8, 9-11, 12-14?. 

Beyrichites tenuis Smith, 1914, p. 119, pi. 32, figs 1-2 [holotype], 3-4,

5-6?; pi. 89, figs. 15-17, 18-20. 

Philippites? argentarius Smith. Spath, 1934, p. 419. 

Gymnotoceras argentarius (Smith). Silberling, 1962, p. 156. 

[not] Beyrichites rotelliformis (Meek). Smith, 1904, p. 379, pi. 43, figs.

13-14; pi. 45, fig. 5 [= Gymnotoceras blakei (Gabb), revised].

Revised description. Discoidal, compressed (immature W/D 0.30-0.40, mature 0.30-0.50); moderately 

involute (immature U/D 0.15-0.30, mature 0.12-0.25). 

Transition from immature to mature morphology at 

diameter 30-40 mm; maximum diameter exceeding 85 

mm. Venter acutely rounded, without ventral shoulders, on phragmocone, becoming broadly rounded with 

growth in some forms.

Ribbing on immature shell widely variable in strength 

from weak to strong, fading with growth. Ribs falcoid, 

commonly branching from swollen primary ribs on lower 

flanks and weakening on upper flanks; ventral tips of 

ribs slightly enlarged. No tubercles on ribs. Blunt 

ventral keel distinct only on more strongly ornamented 

immature shells; fades with growth.

Suture simple, subammonitic with four rounded finely 

crenulate external saddles decreasing progressively in 

height inwards.

Discussion. This species, as revised, shows a wide 

range of morphologic variation and complete intergradation with Gymnotoceras blakei, which characterizes the 

beds immediately overlying those with G. rotelliformis. 

Immature specimens of both G. rotelliformis and G. 

blakei are distinctive in having high whorls whose flanks 

taper to a narrowly rounded acute venter, but G. rotelliformis lacks the regular falcoid ribs which cross the 

flanks with uniform strength in G. blakei. In some 

variants of G. rotelliformis the outer whorl thickens 

rapidly and the acute venter of the inner whorls becomes 

bluntly rounded.

The average morphology of G. rotelliformis, as revised, 

is closest to that of specimens included in G. argentarius 

by Smith (1914) but with less inflated whorls. Meek's 

type specimen of G. rotelliformis agrees with weakly ornamented variants of populations that include forms

with the average morphology, but its ornament approaches that of G. blakei in which it was included by 

Silberling (1962, p. 156).

Figured specimens. Holotype, USNM 12526, 

originally figured by Meek, 1877, pi. 10, figs. 9-9a; 

plesiotypes, USNM 248654 to 248665.

Occurrence. Paraceratites burckhardti, P. clarkei, 

and P. uogdesi beds, grading into Gymnotoceras blakei 

in the Paraceratites cricki and Gymnotoceras blakei 

beds. USGS localities M136 (100+), M136 -5 ft (1.5 m) 

(12), M139 (22), M163 (14), M164 (30+), M165 (20), 

M605 (38), M606 (14), M607 (3), M608 -8 ft (2.5 m) (6), 

M965 (100+), M965 +3 ft (0.9 m) (18), M966 (40), M967 

(3), and M967 -9 ft (2.7 m) (7); Rotelliformis Zone, 

vicinity of Fossil Hill, Humboldt Range, Nev.

Gymnotoceras blakei (Oabb)

Plate 8, figures 6-19; plate 9, figures 1-18

Ammonites blakei Gabb, 1864, p. 24, pi. 4, figs. 14-15.

Ceratites (Gymnotoceras) blakei (Gabb) [in part]. Hyatt and Smith, 

1905, p. 173, pi. 22, figs. 10-11, 12-14?, 15-17?, 18-20?, 21-23? 

[not figs. 1-3, 4-5, 7-9 = Parafrechites meeki (Mojsisovics), 

revised]. Smith, 1914, p. 109, pi. 3, figs. 10-11, 12-14?, 15-17?, 

18-20?, 21-23?, pi. 16, figs. 8-10, 17-19; pi. 66, figs. 1-2, 3-4?, 

5-6?, 7-8? [not pi. 14, fig. lOb; pi. 65, figs. 14-16? = Parafrechites 

meeki (Mojsisovics), revised].

Beyrichites falciformis Smith, 1914, p. 116, pi. 91, figs. 11-13 

[holotype]; pi. 92, figs. 1-2, 3-5, 6-8. Spath, 1934, p. 423.

Gymnotoceras blakei (Gabb). Spath, 1934, p. 427, text-figure 145? 

Silberling, 1962, p. 156.

[not] Gymnotoceras blakei (Gabb). Meek, 1877, p. 113, pi. 10, figs. 

10-10a, lOb [=Parafrechites meeki (Mojsisovics), revised], pi. 11, 

figs. 6-6a [=Frechites neuadanus (Mojsisovics), revised]. Spath, 

1934, p. 427, text-figure 145? [ = ?'Parafrechites meeki (Mojsisovics), revised]. Kummel m Arkell and others, 1957, fig. 182, 

no. la-lc? [=?P. meeki (Mojsisovics), revised].

[not]Ceratites (Gymnotoceras) blakei (Gabb). Smith, 1904, p. 386, pi. 

43, figs. 9-10; pi. 44, figs. 2, 3 [=Parafrechites meeki 

(Mojsisovics), revised].

Revised description. Discoidal, compressed (immature W/D about 0.32-0.40, mature about 0.30); involute (immature U/D 0.15-0.25, mature about 0.15). 

Transition from immature to mature morphology at 

diameter 30-40 mm; maximum diameter more than 80 

mm. Venter of immature shell acute, narrowly rounded, 

without ventral shoulders; with maturity venter 

becomes bluntly rounded, but whorls remain narrow. 

Closely spaced falcoid dichotomous nontubercular ribs 

extend with uniform strength from umbilicus to venter 

on immature whorls. With growth, ribs fade beginning 

on lower flanks, leaving faint projected swellings on 

outer flanks of mature shell. Blunt ventral keel on ribbed 

immature whorls; fades with growth. External suture 

simple, subammonitic with rounded crenulate first and 

second lateral saddles and two auxiliary saddles.

Discussion. The average morphology of Gym-
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 27

notoceras blakei differs from that of G. rotelliformis, 

which occurs stratigraphically lower, in having regular 

falcoid ribbing and narrower whorls, but the two species 

intergrade, and transitional populations include individuals with the average morphology of both. At the 

upper limit of its stratigraphic range, G. blakei coexists 

without morphologic intergradation with Frechites 

nevadanus. Parafrechites meeki, which ranges from the 

Frechites nevadanus beds upwards, differs from G. 

blakei mainly in having relatively low whorls with a 

broadly rounded or subtabulate venter.

Of seven numbered specimens (ANSP 1227-1233) at 

the Academy of Natural Sciences of Philadelphia 

labeled as the type lot of Ammonites blakei Gabb, the 

lectotype (ANSP 1227) selected here, though secondarily 

deformed, is the only one that resembles Gabb's original 

illustration (1864, pi. 4, figs. 14-15) in the degree of compression and shape of the whorls. Accompanying this 

specimen is a note reading "this is obviously same 

species as Gabb's type of Blakei, pi. 4, f. 14, and may be 

the type, A.H." This note was evidently written by 

Alpheus Hyatt who based the genus Gymnotoceras on 

this species. Among the other specimens in the type lot 

that were not illustrated by Gabb, ANSP 1228 belongs to 

Frechites nevadanus, ANSP 1229 agrees with either 

Parafrechites dunni or P. meeki, and ANSP 1230 to 1233 

belong to P. meeki. The lectotype has thicker whorls and 

is less regularly ribbed than average specimens in populations of G. blakei, as revised; it is in closest agreement with forms found in the lower part of the G. blakei 

beds.

The large specimen figured as Ceratites (Gymnotoceras) blakei by Smith (1914, pi. 65, figs. 14-16) and 

refigured by Spath (1934, p. 428, text-fig. 145) and by 

Kummel (in Arkell and others, 1957, fig. 182, la-lc) is 

more robust than any specimens found in the G, blakei 

beds. This specimen is too large to positively identify but 

probably should be assigned to Parafrechites meeki 

(Silberling, 1962, p. 156).

Figured specimens. Lectotype, ANSP 1227 

(probably the specimen on which Gabb's figures, 1864, 

pi. 4, figs. 14-15, were based); plesiotypes, USNM 

248666 to 248678.

Occurrence Gymnotoceras blakei beds, stratigraphically above the occurrence of G. rotelliformis and 

below that of Parafrechites meeki. USGS localities M137 

(24), M141 (19), M142 (23), M607 +2 ft (0.6 m) (16), 

M608 (32), M609 (7), M610 (7), M611 (40), M613 (13), 

and M964 (35); Rotelliformis Zone, vicinity of Fossil 

Hill, Humboldt Range, Nev.

Genus PARAFRECHITES n. gen.

Type species. Parafrechites meeki (Mojsisovics).

Definition. Thickly discoidal to moderately compressed, moderately involute. Venter broadly and evenly 

rounded or with subtle ventral shoulders. Bluntly 

rounded keel on inner whorls. Mature venter smooth.

Strong, regular falcoid ribbing on inner whorls fading 

adorally. Ribs rarely have weak umbilical bullae or faint 

ventro-lateral swellings.

Suture simple, subammonitic with rounded crenulate 

first and second lateral saddles; LI relatively prominent, 

as many as two auxiliary saddles external to the umbilical seam.

Discussion. A new generic name for these relatively 

nondescript beyrichitids is desirable so that the other 

upper Anisian genera Gymnotoceras and Frechites can 

be recognized as morphologically distinctive entities. 

Parafrechites is easily distinguished from Gymnotoceras 

by its broadly rounded venter and from Frechites by the 

absence of tubercles and distinct ventral-lateral 

shoulders.

Parafrechites meeki (Mojsisovics)

Plate 11, figures 7-23; plate 12, figures 1-29; plate 13, figures 1-5

Gymnotoceras blakei (Gabb), Meek, 1877, p. 113, pi. 10, figs. 10-10b. 

Ceratites meeki Mojsisovics, 1888, p. 168 [new name for Gymnotoceras

blakei (Gabb) of Meek, 1877, pi. 10, figs. 10-10b]. 

Ceratites (Gymnotoceras) blakei (Gabb). Smith, 1904, p. 386, pi. 43,

figs. 9-10; pi. 44, figs. 2, 3. Hyatt and Smith, 1905, p. 173, pi. 22,

figs. 1-3, 4-5, 7-9. Smith, 1914, p. 109, pi. 14, fig. lOb; pi. 65, figs.

14-16? 

Ceratites (Gymnotoceras) meeki Mojsisovics. Smith, 1914, p. Ill, pi.

14, figs. 10-10a; pi. 69, figs. 1-2, 3-4, 5-6, 7-9,10-13,14-16,17-19. 

Ceratites tenuispiralis Smith, 1914, pi. 46, figs. 17-19 [holotype],

20-22, 23?, 24-25?. 

Ceratites washbwnei Smith, 1914, p. 103, pi. 92, figs. 9-11 [holotype],

12-14, 15-17. 

Ceratites (Hollandses) montis-bovis Smith, 1914, p. 105, pi. 58, figs.

1-4 [holotype], 5-7, 8-11, 12-14, 15-16?, 17-20?. 

Ceratites (Hollandses) organi Smith [in part], 1914, p. 105, pi. 55, figs.

1-2, 3-4?, 5-7, 8-10 [not pi. 54, figs. 1-9; ?pl. 55, figs. 11-30 =

Frechites occidentalis (Smith), revised]. 

Ceratites (Gymnotoceras) beckeri Smith, 1914, p. 109, pi. 3, figs. 4-5,

7-9; pi. 66, figs. 10-13 [holotype], 14-15, 16-19, 20-22, 23, 24-26,

27-29?. 

Ceratites (Gymnotoceras) russelli Smith, 1914, p. Ill, pi. 3, figs. 1-3

[holotype], 6; pi. 67, figs. 1-3, 4-7, 8-9, 10-12, 13-15. 

Ceratites (Gymnotoceras) wemplei Smith, 1914, p. 113, pi. 68, figs. 1-3

[holotype], 4-6, 7-9. 

Gymnotoceras meeki (Mojsisovics). Spath, 1934, p. 430. Silberling,

1962, p. 156.

Frechites tenuispiralis (Smith). Spath, 1934, p. 453. 

Gymnotoceras russelli Smith. Spath, 1934, p. 429. 

Gymnotoceras wemplei Smith. Spath, 1934, p. 431. 

Gymnotoceras washburnei (Smith) [in part]. Silberling, 1962, p. 156.

Revised description. Thick discoidal (immature 

W/D 0.40-0.45, mature 0.35-0.40, W/D of bullate 

variants in lower part of stratigraphic range may exceed 

0.5); moderately involute (immature and mature U/D 

0.20-0.30). Transition to mature morphology not
28 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

marked; loss of ornament begins at diameter 40-50 mm. 

Maximum diameter exceeds 80 mm. Venter broadly 

rounded to subtabulate at all growth stages.

Ribbing strong and regular, projected or slightly 

falcoid across flanks. Primary ribs enlarged or slightly 

bullate on lower flanks below bifurcation point on more 

coarsely ribbed variants. Ventral tips of ribs slightly 

enlarged on forms tending to develop ventral-lateral 

shoulders. Strong umbilical bullae and distinct projected ventral-lateral tubercles only on some variants in 

lower part of stratigraphic range. Blunt ventral keel persistent to diameters exceeding 40 mm.

Suture simple, subammonitic with rounded crenulate 

first and second lateral saddles and usually only one discrete auxiliary saddle external to the umbilical shoulder.

Discussion. Parafrechites meeki, as revised, is distinguished by its broadly rounded or subtabular venter, 

by the strong, regular ribbing, by the generally poor 

development of tubercles or bullae on the ribs, and by 

the persistence of the immature ornamentation to 

relatively large shell diameters.

The principal variations in populations from the middle part of the P. meeki beds are in the density of the ribbing and the degree of angularity at the ventral-lateral 

shoulders. The average morphology of these populations 

is close to that of forms included by Smith in "Ceratites 

(Gymnotoceras) russelli." Although Smith (1914, p. 110- 

112) contended that intergradation did not occur among 

the various species he included in "Gymnotoceras" 

Spath (1934, p. 428-429) pointed out the close alliance of 

"G." meeki, "G." russelli, "G." beckeri, and "G. blakei" 

(of Smith) and the existence of many "passage forms" 

between them among the stratigraphically random collections from Fossil Hill at the British Museum. 

Intergradation is well shown in the population samples 

on which the present revision is based.

Populations from the lower part of the Parafrechites 

meeki beds show a greater amount of variation and range 

in morphology from relatively robust end members with 

umbilical bullae and coarse ribs terminating in ventrallateral swellings or tubercles to regularly ribbed, nontuberculate, compressed, high-whorled end members. 

The lectotype (Meek, 1877, pi. 10, figs. 10-10a) of P. 

meeki, selected here, is in closest agreement with forms 

from the lower part of the stratigraphic range of P. 

meeki, as revised.

The holotype of Ceratites (Hollandites) montis-bouis, 

included in Gymnotoceras by Spath (1934, p. 427) and in 

P. meeki here, is more involute and more delicately 

ribbed than the characteristic form of P. meeki as 

revised, and may be transitional to P. dunni, which 

characterizes the beds stratigraphically above those with 

P. meeki. However, a morphologic intergradation

between P. meeki and P. dunni is not demonstrated by 

the available stratigraphically controlled collections, 

perhaps because the number of specimens represented is 

too small.

Figured specimens. Lectotype, USNM 12512 

(originally figured by Meek, 1877, pi. 10, figs. 10-10a); 

plesiotypes, USNM 74301 (holotype of Gymnotoceras 

russelli Smith, 1914, pi. 3, figs. 1-3), USNM 74391 

(holotype of G. beckeri Smith, 1914, pi. 66, figs. 10-13), 

and USNM 248694 to 248710.

Occurrence. Parafrechites meeki beds; stratigraphically above Frechites neuadanus beds and ranging 

stratigraphically upwards into the P. dunni beds. USGS 

localities M138 (9), M140 (60+), M143 (21), M612 (17); 

M616 (9), M617 (15), M958 (100+), M960 (150+), and 

M963 (60+); Meeki Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Parafrechites dunni (Smith)

Plate 13, figures 6-30

Beyrichites dunni Smith, 1914, p. 116, pi. 32, figs. 7-8 [holotype], 9-10,

11-12?. Spath, 1934, p. 423. 

Beyrichites osmonti Smith, 1914, p. 117, pi. 31, figs. 7-8 [holotype],

9-10, 11-12, 13-14?; pi. 89, fig. 14?. 

Gymnotoceras dunni (Smith). Silberling, 1962, p. 166. 

[?] Ceratites williamsi Smith, 1914, p. 82, pi. 47, figs. 11-14 [holotype],

15-16, 17-18?. 

[?] Ceratites (Philippites) ransomei Smith, 1914, p. 108, pi. 99, figs.

1-3 [holotype], 4.

Revised description. Discoidal, moderately compressed (W/D 0.33-0.40); involute (U/D 0.15-0.20). 

Whorl shape and proportions constant with growth. 

Maximum diameter more than 65 mm. Venter broadly 

rounded, grading imperceptibly into flanks or delimited 

by poorly developed ventral-lateral shoulders.

Ornamentation generally restricted to inner whorls 

and variable in strength, nearly absent on some forms 

and commonly lost at shell diameters of more than 30 

mm. Ribbing, when developed on immature shell, dense 

and regular; ribs projected or slightly falcoid, branching 

on lower flanks. Weak umbilical bullae and ventral swellings on ribs only on inner whorls of coarsely ornamented 

variants. Outer whorls smooth except for falcoid growth 

lines projected across venter. Blunt ventral keel 

developed in proportion to strength of ribbing, usually 

weakly developed for at least part of one volution even on 

smoothest variants.

Suture subammonitic with rounded, weakly crenulated first and second lateral saddles and two auxiliary 

saddles external to the umbilical seam.

Discussion. This species is distinguished by a poor 

development or early loss of ornamentation and by its 

thick discoidal whorls having a broad, rounded, or
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 29

slightly tabular venter. Some specimens, like those included by Smith in "Beyrichites" osmonti, are nearly 

devoid of ornamentation, and for this reason they were 

assigned to Beyrichites by Smith who derived this genus 

directly from Gymnotoceras by a progressive loss of 

sculpture. These smooth forms are included here in 

Parafrechites because they are like end-member variants 

of population in which more average forms possess the 

characteristic ribbing and ventral keel of Parafrechites 

on their inner whorls. Most of the species of beyrichitids 

from Fossil Hill tend to become less ornamented with 

growth and show some individual variation in the 

strength of sculpture. Consequently, specific assignment 

of an isolated specimen may be difficult; for example, 

the paratype of "Beyrichites" osmonti Smith (1914, pi. 

89, fig. 14) might belong to the present species, as 

revised, or be a smooth and perhaps premature variant 

of Gymnotoceras rotelliformis, revised.

Some large, strongly sculptured specimens with the 

characteristic ornament and whorl shape of P. meeki occur with populations of P. dunni in collections from a 

single bed. Forms transitional between the two species 

appear to be lacking in these collections, perhaps 

because of the relatively small size of these samples.

The lithologic character of the beds characterized by 

P. dunni differs from that of the beds stratigraphically 

above and below in being more sandy and pervasively 

stained with ferric oxides. Matrix material like that of 

the P. dunni beds can be recognized on one of the 

paratypes of "Beyrichites" osmonti Smith (1914, pi. 31, 

figs. 9-10), on a paratype of "B." dunni Smith (1914, pi. 

32, figs. 9-10), and possibly on the holotype of "B." 

dunni. The holotype of "Ceratites" williamsi Smith, 

questionably included in Parafrechites dunni, as revised, 

bears a shell fragment probably referable to Daonella 

dubia, a species occurring stratigraphically above the P. 

dunni beds; "C." williamsi may be a smooth variant 

closely related to forms like "C." rotuloides Smith as 

suggested by Smith (1914, p. 83), and hence it might 

belong with the group of Smith's species included here in 

Frechites occidentalis.

The suture line of "Ceratites (Philippites) " ransomei 

as illustrated by Smith (1914, pi. 99, fig. 4) is oversimplified; the saddles on the suture of this specimen are 

slightly crenulate rather than being smoothly rounded.

Figured specimens. Plesiotypes, USNM 248712 to 

248721.

Occurrence. Restricted to the Parafrechites dunni 

beds, stratigraphically above the P. meeki beds and 

below the Frechites occidentalis beds. USGS localities 

M167 (20+), M618 (24), M619 (40+), M959 (20+), and 

M968 (60+); Meeki Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Genus FRECHITES Smith, 1932

Frechites Smith [type species Ceratites humboldtensis Hyatt and 

Smith, 1905, by original designation].

Revised description. Thickly discoidal to moderately 

compressed; moderately involute. Whorl section on inner whorls has broadly rounded venter, changing on 

outer phragmacone and body chamber to subtrapezoidal 

with flattened venter and distinct rounded ventrallateral shoulders. Venter on inner whorls has bluntly 

rounded keel, on outer whorls is smooth. Falcoid simple, 

branching or intercalating ribs having ventral swellings 

or distinct blunt tubercles at ventral-lateral shoulders 

and on some having bullae or spines on lower flanks. 

Suture subammonitic, LI relatively prominent; one or 

two auxilliary saddles beyond S2.

Frechites nevadanus (Mojsisovics)

Plate 9, figures 19-25; plate 10, figures 1-24; 

plate 11, figures 1-6

Gymnotoceras blakei (Gabb). Meek, 1877, pi. 11, figs. 6-6a.

Ceratites nevadanus Mojsisovics, 1888, p. 168 [new name for Gymnotoceras blakei (Gabb) of Meek, 1877, pi. 11, figs. 6-6a]. Smith 

[in part], 1914, p. 101, pi. 15, figs. 6-6a, pi. 64, figs. 1-2?, 8-9? 

[not? figs. 3-7, 10-12, 13-14 = ?Frechites occidentalis (Smith), 

revised], pi. 65, figs. 1-4?, 5-7?, 8-9?, 10-11?, 12-13?.

Ceratites humboldtensis Hyatt and Smith, 1905, p. 170, pi. 57, figs. 1-3 

[lectotype selected by Spath (1934, p. 447)], 4-5, 6-7, 8-11, 

12-13?, 14-16?, 17-18?, 19-21?, 22-23?. Smith, 1914, pi. 7, figs. 

1-3, 4-5, 6-7, 8-11,12-13?, 14-16?, 17-18?, 19-21?, 22-23?; pi. 61, 

figs. 1-3, 4-5, 6-7, 8-12, 13-15. Arthaber, 1915, p. 120, text-fig. 

7e-7f.

Ceratites cornutus Smith, 1914, p. 98, pi. 62, figs. 1-4 [holotype], 5-7, 

8-9, 10-12, 13-15, 16-17?.

Ceratites emmonsi Smith [in part], 1914, p. 98, pi. 60, figs. 13-15 

[holotype], 19-21; [not figs. 16-18 = Frechites occidentalis 

(Smith), revised].

Ceratites spirdfer Smith [in part], 1914, p. 103, pi. 59, figs. 1-3 

[holotype], 9-10 [not figs. 4-7 = Paraceratites cricki Smith, 

revised]; pi. 60, figs. 1-3, 4-6, 7-9?, 10-12.

Ceratites (Gymnotoceras) hersheyi Smith, 1914, p. 110, pi. 93, figs. 1-3 

[holotype], 4-6?, 7-8?, 9-10?, 11-12?, 13-14?.

Frechites humboldtensis (Hyatt and Smith). Smith, 1932, p. 32. 

Spath, 1934, p. 447.

Frechites cornutus (Smith). Spath, 1934, p. 449.

Frechites emmonsi (Smith). Spath, 1934, p. 449.

Frechites spinifer (Smith). Spath, 1934, p. 448.

Gymnotoceras (Frechites) nevadanus (Mojsisovics). Silberling, 1962, 

p. 156.

[not] Frechites nevadanus (Mojsisovics). Spath, 1934, p. 450 

[=Frechites occidentalis (Smith), revised].

Revised description. Thick discoidal (immature 

W/D about 0.40, mature 0.45-0.60); moderately involute 

(U/D about 0.25). Transition from immature to mature 

sculpture beginning at diameter of 25-35 mm; maximum 

diameter more than 85 mm. Immature whorl cross section subquadrate with venter broadly arched; mature
30 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

cross section trapezoidal owing to pronounced tubercles 

on lower flanks and broad flattened venter.

Ribs on immature shell coarse and regular, running 

from umbilical shoulders onto venter and branching on 

lower flanks. Transition to mature ornamentation by 

enlargement of ribs into tubercles at ventral-lateral 

shoulders and then by development on lower flanks of 

coarse umbilical tubercles from which two or three ribs 

diverge. Decrease in strength of ribs on outer whorl accompanied by elongation of ventral-lateral tubercles into 

low clavi. Umbilical tubercles on mature shell spinose, 

rising from broad swellings, or elongated radially with 

their tips sometimes curved adapically. Blunt ventral 

keel conspicuous on immature whorls, gradually 

diminishing in strength. Broad venter of mature shell 

smooth, gently arched, flat, or even slightly biconcave 

bordered by rows of ventral-lateral tubercles or clavi.

Suture subammonitic with crenulate saddles. First 

lateral saddle and lobe prominent; one or two discrete 

auxiliary saddles beyond second lateral saddle.

Discussion. Young stages of F. nevadanus are indistinguishable from those of Parafrechites meeki, but 

mature shells of the latter species, even from possibly 

transitional populations in the lower part of its 

stratigraphic range, failed to develop the broad flattened 

venter and pronounced umbilical tubercles of the former 

species.

Robust tubercular variants of F. occidentalis closely 

resemble the mature form of the present species. They 

differ from F. nevadanus by the early loss or poor 

development of the ventral keel, the higher and more 

rectangular cross section of their early whorls, the more 

bullate character of the umbilical tubercles on the 

mature shell, and the shape of their ventral-lateral 

tubercles, which are more in the form of projected swellings than discrete tubercles or clavi.

On Meek's holotype of F. nevadanus the part of the 

shell bearing the ventral keel is not well preserved, but 

the presence of a keel is strongly suggested. The nature 

of the tubercles and venter also indicate that this name 

is properly applied to the present group. From his study 

of stratigraphically random specimens, Smith had no 

way of knowing that populations like those included here 

in F. nevadanus do not include forms like the robust 

tuberculate variants of F. occidentalis, and several of the 

specimens figured by him as belonging to the former 

species evidently belong to the latter. This incorrect assignment, in addition to an erroneous conception of 

Meek's type specimen, led Smith (1914, p. 101) and 

Spath (1934, p. 450) to characterize F. nevadanus as differing from the other species of Smith's "group of 

'Ceratites' humboldtensis" (= Frechites) by lacking a 

ventral keel.

Figured specimens. Holotype, USNM 12512

(originally figured by Meek, 1877, pi. 11, figs. 6-6a); 

plesiotypes, USNM 248679 to 248693.

Occurrence. Restricted to Frechites nevadanus beds, 

stratigraphically above Gymnotoceras blakei beds and 

below Parafrechites meeki beds. USGS localities M142 

(4), M166 (100+), M614 (120+), M615 (35+), andM957 

(35+); Meeki Zone, vicinity of Fossil Hill, Humboldt 

Range, Nev.

Frechites occidentalis (Smith)

Plate 13, figures 31-34; plate 14, figures 1-33

Ceratites occidentalis Smith, 1914, p. 84, pi. 44, figs. 21-23 [holotype],

24-25, 26-28; pi. 45, figs. 1-2, 3-4, 5-7?, 8-9?, 10-11?, 12-13?. 

Ceratites applanatus Smith, 1914, p. 80, pi. 53, figs. 9-11 [holotype],

12-14?. 

Ceratites rotuloides Smith, 1914, p. 80, pi. 47, figs. 1-3 [holotype], 4-5,

6-7, 8-10?. 

Ceratites altilis Smith, 1914, p. 83, pi. 45, figs. 14-16, 17-18, 19-20,

21-22?; pi. 67, figs. 19-21 [holotype].

Ceratites gilberti Smith, 1914, p. 84, pi. 98, figs. 1-3 [holotype]. 

Ceratites karpinskyi Smith, 1914, p. 100, pi. 44, figs. 4-6 [holotype],

7-8, 9-10, 11-12?, 13-15?, 16-18?, 19-20?. 

Ceratites nevadanus (Mojsisovics) [in part]. Smith, 1914, pi. 64, figs.

3-7, 10-12, 13-14. Spath, 1934, p. 450. 

Ceratites pilatus Smith, 1914, p. 102, pi. 46, figs. 1-4, 5-6, 7-8, 9-10,

11-12?, 13-14?, 15-16?; pi. 89, figs. 10-13 [holotype]. 

Ceratites (Hollandses) organi Smith, 1914, p. 105, pi. 54, figs. 1-4

[holotype], 5-6, 7-9; pi. 55, figs. 11-12?, 13-15?, 16-18?, 19-20?,

21-23?, 24-26?, 27-30?.

Frechites occidentalis (Smith). Spath, 1934, p. 452. 

Frechites rotuloides (Smith). Spath, 1934, p. 454. 

Frechites altilis (Smith). Spath, 1934, p. 453. 

Frechites karpinskyi (Smith). Spath, 1934, p. 451. 

Frechites pilatus (Smith). Spath, 1934, p. 451. 

Gymnotoceras occidentalis (Smith). Silberling, 1962, p. 156. 

Gymnotoceras washburnei (Smith) [in part]. Silberling, 1962, p. 156. 

[?]Ceratites (Philippites) lawsoni Smith, 1914, p. 108, pi. 56, figs. 1-5

[holotype], 6-8, 9-11, 12-13; pi. 57, figs. 1-3, 4-6, 7-9?, 10-13?,

14-17?. 

[?]Ceratites (Gymnotoceras) spurri Smith, 1914, p. 112, pi. 67, figs.

16-18 [holotype].

Revised description. Discoidal, moderately compressed (W/D 0.33-0.40, W/D of bullate variants may exceed 0.45); moderately involute (immature U/D 

0.25-0.32, mature 0.18-0.30, mainly 0.20-0.25). Loss of 

ventral keel and development of distinct ventral-lateral 

shoulders usually occurs at diameters less than 25 mm; 

ornamentation fades on outer whorl. Maximum 

diameter about 80 mm; some fully mature shells may 

not exceed 60 mm diameter. Venter subtabulate, 

broadly arched between rounded, but distinct, ventrallateral shoulders, which are commonly emphasized by 

tubercles at ventral ends of ribs.

Ribbing coarse but widely variable in strength. 

Primary ribs give rise to two or three branches on lower 

flanks. On some robust variants primary ribs bullate or 

represented by large umbilical tubercles below bifurcation point. Other forms coarsely ribbed without um-
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 31

bilical tubercles or bullae; some variants nearly smooth 

with faint wide ribs. Ventral ends of ribs enlarged into 

projected swellings or tubercles at ventral-lateral 

shoulders. Blunt ventral keel only on inner whorls.

Suture simple, subammonitic with rounded crenulate 

first and second lateral saddles and one or two auxiliary 

saddles external to the umbilical shoulder.

Larger stratigraphically controlled collections might 

demonstrate that populations in the lower part of the 

stratigraphic range of F. occidentalis bear a stronger 

resemblance to Parafrechites meeki, a possible ancestor, 

than do those that occur higher. These possibly transitional populations were grouped into a distinct species, 

"Gymnotoceras" washburnei, by Silberling (1962, p. 

156), but their range of morphologic variation is here 

regarded as too similar to that of Frechites occidentalis 

for specific separation. The various "species" described 

by Smith that were included in "G." washburnei 

(Smith) by Silberling are therefore included in either 

Parafrechites meeki or Frechites occidentalis, as revised.

"Ceratites (Philippites)" lawsoni Smith was referred 

to Frechites by Spath (1934, p. 418-419) and is 

provisionally included here in F. occidentalis, although 

no specimens with the exaggerated curved bullae of 

Smith's holotype are present in the stratigraphically 

controlled collections. Some coarsely ribbed variants of 

Parafrechites dunni, as revised here, resemble the 

paratypes of "C. (P.)" lawsoni Smith and suggest a possible transition from P. dunni to F. occidentalis.

The inclusion of "Ceratites" altilis Smith and "C. 

(Holhndites)" organi Smith in F. occidentalis is substantiated by shell fragments of Daonella dubia and D. 

moussoni adhering to the holotypes of these species. 

These bivalves are indicative of the Occidentalis Zone.

Figured specimens. Plesiotypes, USNM 248722 to 

248739.

Occurrence. From the Parafrechites dunni beds 

stratigraphically upwards into the Nevadites gabbi beds. 

USGS localities M144-6 ft (1.8 m) (10), M144 (6+), 

M145 (50+), M622 (7), M623 (10), M624 (35+), M625 

(24+), M626 (50+), M961 (11), M962 (10), and M962A 

(6). Upper part of Meeki Zone and Occidentalis Zone, 

vicinity of Fossil Hill, Humboldt Range, Nev.

Frechites johnstoni n. sp. 

Plate 15, figures 1-5; text-figure 18

Gymnotoceras n. sp. Silberling, 1962, p. 158.

Description. Discoidal, compressed (W/D about 

0.33) shell becoming increasingly involute as size increases (U/D immature 0.20-0.24, mature 0.15). Flanks 

flattened, converging to narrow, broadly arched venter. 

Ventral-lateral shoulders distinct. Ribs falcoid, simple 

or bifurcating, densely and regularly spaced (about 40

per volution on outer flank), persistent to relatively large 

shell diameter (more than 60 mm) but fading on orad 

part of body chamber. Bullae and tubercles lacking, but 

ventral tips of ribs enlarged, tending to increase angulation of ventral-lateral shoulders. Blunt low ventral keel 

on inner whorls fades with increasing shell size, not discernible beyond diameters of about 30 mm.

Suture simple, subammonitic; LI relatively prominent; two auxiliary saddles and lobes.

Discussion. This new species of beyrichitid is placed 

in Frechites because of its subtabulate venter, and it differs from other species of this genus in having higher, 

more compressed whorls and in lacking tuberculation.

This species is named in honor of Francis Newlands 

Johnston, who, in addition to his important study of Upper Triassic ammonites from the New Pass Range, Nev., 

also collected Triassic ammonites from the Humboldt 

Range, including the type lot of this species.

Figured specimens. Holotype, USNM 248740; 

paratype, USNM 248741.

Occurrence Subasperum Zone. USGS locality M627 

(2) and USGS Mesozoic locality M3093 (1), vicinity of 

Fossil Hill; USGS locality M905 (1) associated with 

Protrachyeras cf. P. americanum (Mojsisovics) between 

Cottonwood Canyon and Fitting; and USGS Mesozoic 

locality M5481 (4), the type lot from a single limestone 

block associated with Protrachyceras cf. P. subasperum 

(Meek), Arizona Mine area near Unionville, Humboldt 

Range. Nev.

FIGURE 18. Suture line (X 4) of Frechites johnstoni n. sp. Holotype, 

USNM 248740.

Subfamily PARACERATITINAE Silberling, 1962

Genus PARAGERATITES Hyatt, 1900

Paraceratites burckhardti Smith

Plate 15, figures 6-18

Ceratites (Paraceratites) burckhardti Smith, 1914, p. 90, pi. 52, figs. 

19-21 [holotype].

Revised description. Discoidal, compressed (W/D 

mainly about 0.30 measured between lateral nodes, maximum W/D of robust variants including nodes more than 

0.45); moderately involute (U/D 0.20-0.25). Maximum 

diameter exceeding 100 mm. Flanks broadly rounded,
32 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

subparallel; ventral-lateral shoulders marked by tubercles but not sharply rounded. Venter high and narrow, 

extending well above ventral-lateral tubercles as a blunt 

keel that persists to shell diameters of more than 70 mm.

Ribs on inner whorls at diameters less than 30 mm 

regular, projected or slightly falcoid, branching from 

umbilical swellings and terminating in projected ventral 

swellings. With increasing shell growth ribs bifurcate at 

lateral tubercles developed below midline of flanks on 

most primary ribs. On outer whorls ribs become weak 

and irregular, whereas lateral tubercles, numbering 

about 10 per whorl, develop into pronounced widely 

spaced nodes at or below midline of flank. Ventrallateral tubercles persist as projected swellings corresponding to ventral tips of ribs, outnumber lateral 

nodes 3:1 to 3.5:1, become weak coalescing clavae on outermost whorl.

Suture ceratitic. SI and S2 high and entire; only one 

discrete auxiliary saddle. L2 and divided VL about equal 

in depth and two-thirds that of LI. Lobes coarsely 

digitate.

Discussion. This species occurs in the stratigraphically lowest collections obtained from the vicinity 

of Fossil Hill. The pronounced development of widely 

spaced lateral nodes and the high, bluntly carinate 

venter, extending well above the ventral-lateral tubercles, distinguish P. burckhardti from the stratigraphically succeeding species P. clarkei and P. uogdesi, 

as revised. By these same characters P. burckhardti 

closely resembles P. cricki, the stratigraphically highest 

species of Paraceratites in the Rotelliformis Zone. 

Though their stratigraphic ranges are not contiguous 

and those of other species intervene, P. burckhardti and 

P. cricki are readily separated only by the lower proportion (2:1) of ventral-lateral to lateral tubercles and the 

more regular ribbing of the latter.

Some compressed variants of P. burckhardti, especially from USGS locality M164, which may be the 

stratigraphically lowest ammonite collection from the 

Rotelliformis Zone, have poorly defined ventral-lateral 

shoulders and lateral tubercles that arise low on the 

flanks from umbilical bullae.

Figured specimens. Plesiotypes, USNM 248742 to 

248747.

Occurrence. Paraceratites burckhardti beds, stratigraphically below the occurrence of P. clarkei. USGS 

localities M164 (6) and M965 (40+); Rotelliformis Zone, 

vicinity of Fossil Hill, Humboldt Range, Nev.

Paraceratites clarkei Smith 

Plate 16, figures 1-12

Ceratites (Paraceratites) clarkei Smith, 1914, p. 91, pi. 40, figs. 15-17 

[holotype], 18-20, 21-23; pi. 52, figs. 1-3, 4-6, 7-8, 9-11.

Ceratites (Paraceratites) newberryi Smith [in part], 1914, p. 92, pi. 40,

figs. 6-8, 9-11 [not figs. 1-3, 4-5, 13-14?= Paraceratites vogdesi

(Smith), revised]. 

Ceratites (Paraceratites) trinodosus Mojsisovics [inpart]. Smith, 1914,

p. 92, pi. 39, fig. 6; pi. 52, figs. 15-18 [not pi. 39, figs. 1-2, 3-5,

7-8?, 9-10, 11-13?, 14-16?, 17-19?; pi. 52, figs. 12-14 =

Paraceratites vogdesi (Smith), revised]. 

Ceratites beecheri Smith [in part], 1914, p. 94, pi. 43, figs. 18-20 [not

figs. 15-17, 21-22, 23-24?, 25-26? = Nevadites humboldtensis

Smith, revised]. 

Nevadites fontainei Smith [in part], 1914, p. 122, pi. 41, figs 16-17,

18-19, 20-22; pi. 51, figs 5-9 [ not pi. 41, figs. 23?, 24-25?, 26-27?;

pi. 51, figs. 1-4 = Nevadites humboldtensis Smith, revised]. 

Paraceratites clarkei Smith. Spath, 1934, p. 445. Silberling, 1962, p.

156 [in part]. 

[t]Ceratites rectangularis Smith, 1914, p. 85, pi. 41, figs. 14-15

[holotype]. 

[t]Ceratites (Paraceratites) wardi Smith, 1914, p. 94, pi. 53, figs. 4-6

[holotype], 7-8.

Revised description. Compressed discoidal to thick 

discoidal (W/D 0.30-0.50); width of umbilicus proportional to whorl thickness (U/D 0.25-0.35). Maximum 

diameter exceeding 70 mm. Ventral-lateral shoulders 

abrupt, emphasized by tubercles; venter broadly 

rounded with low, blunt ventral keel of variable strength 

on inner whorls. Cross section of whorls subrectangular.

Ribbing and tuberculation variable in strength 

proportional to whorl thickness. On inner whorls of compressed forms, ribs delicate and falcoid, originate singly 

or in pairs from indistinct umbilical tubercles, terminate 

at sharp ventral-lateral tubercles elongated parallel to 

projected ventral tips of ribs; lateral tubercles developed 

last, spaced irregularly on consecutive or alternate ribs 

below midline of flanks. On more robust shells coarse 

primary ribs join umbilical with lateral tubercles on 

lower flanks. Most primary ribs bifurcate at lateral 

tubercles, some rejoin at ventral-lateral tubercles; ratio 

of ventral-lateral to lateral tubercles less than 2:1. On 

outer whorls ribbing becomes weak and irregular, lateral 

and ventral-lateral tubercles dominate ornamentation. 

Strength of ventral-lateral tubercles equals or exceeds 

that of lateral tubercles.

Suture ceratitic, like that of P. burckhardti.

Discussion. This species occupies a stratigraphic 

position intermediate between that of P. burckhardti 

and P. uogdesi and in some respects combines the 

morphologic characters of these species, although complete intergradation with them is not exhibited. The 

position of the lateral tubercles low on the flanks is like 

that of P. burckhardti, whereas the comparable or 

greater strength of the ventral-lateral compared with the 

lateral tubercles and the wide, broadly rounded venter 

are in agreement with P. vogdesi. The young stages of 

compressed strongly keeled variants of P. clarkei are indistinguishable from specimens of P. burckhardti of 

comparable size and proportions on which the lateral 

tubercles are not yet fully developed.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 33

Paraceratites clarkei was recognized as a distinct 

species by Silberling (1962, p. 156), but due to insufficient stratigraphic control its occurrence was misplaced between that of P. vogdesi and of P. cricki. 

Though few in number, subsequent stratigraphically 

controlled collections amply verify the correct 

stratigraphic position of P. clarkei.

Figured specimens. Plesiotypes, USNM 248748 to 

248753.

Occurrence Paraceratites clarkei beds, stratigraphically between the occurrence of P. burckhardti and P. 

vogdesi. USGS localities M136 -7 ft (2.1 m) (1), M606 

-8 ft (2.5 m) (4), M966 (30+), and M967 -15 ft (4.5 m) 

(2); Rotelliformis Zone, vicinity of Fossil Hill, Humboldt 

Range, Nev.

Paraceratites vogdesi (Smith) 

Plate 16, figures 13-28; plate 17, figures 1-5

Ceratites vogdesi Smith, 1904, p. 384, pi. 43, figs. 7 [holotype], 8; pi.

44, fig. 1 [holotype]. 

Ceratites (Paraceratites) vogdesi Smith. Smith, 1914, p. 89, pi. 35, figs.

4-6 [holotype], 7-9?. 

Ceratites (Paraceratites) newberryi Smith [in part], 1914, p. 92, pi. 40,

figs. 1-3 [holotype], 4-5, 13-14? [not figs. 6-8, 9-11 =

Paraceratites clarkei Smith, revised]. 

Ceratites (Paraceratites) trinodosus Mojsisovics [in part]. Smith, 1914,

p. 92, pi. 39, figs. 1-2, 3-5, 7-8?, 9-10, 11-13?, 14-16?, 17-19?; pi.

52, figs. 12-14 [not pi. 39, fig. 6, pi. 52, figs. 15-18 = Paraceratites

clarkei Smith, revised].

Ceratites fissicostatus Hauer. Smith, 1914, p. 96, pi. 53, figs. 1-3. 

Ceratites haguei Smith, 1914, p. 97, pi. 42, figs. 1-2 [holotype], 3-5; pi.

43, figs. l-2a, 3-5?, 6-7?, 8-10?. 

Paraceratites vogdesi (Smith). Spath, 1934, p. 444. Silberling, 1962, p.

156 [in part]. 

[?] Ceratites kingi Smith, 1914, p. 85, pi. 41, figs. l-3a [holotype], 4,

5-6, 7-8?, 9?, 10-11?, 12-13?. 

[?] Ceratites (Paraceratites) trojanus Smith, 1914, p. 88, pi. 36, figs.

1-3 [holotype], 4-5; pi. 37, figs. 1-3, 4-5. 

[?] Ceratites crassicomu Smith, 1914, p. 95, pi. 43, figs. 11-12

[holotype], 13-14?.

[?] Ceratites ecarinatus Hauer. Smith, 1914, p. 96, pi. 44, figs. 1-3. 

[?] Paraceratites trojanus Smith. Spath, 1934, p. 443.

Revised description. Discoidal, moderately compressed (W/D 0.30-0.35 between lateral tubercles or 

spines); width of umbilicus widely variable proportional 

to whorl width and strength of ornamentation (U/D 

0.22-0.32). Maximum diameter exceeding 95 mm. 

Ventral-lateral shoulders abrupt, emphasized by tubercles; venter broadly rounded with indistinct low keel on 

inner whorls. Whorl cross section subrectangular in compressed, weakly ornamented forms, hexagonal in robust 

forms with coarse lateral spines.

Ribbing and tuberculation widely variable in strength 

proportional to width of whorls and umbilicus. On inner 

whorls ribs weakly falcoid, branch from umbilical 

shoulder or at midflank, terminate in projected tubercles. Lateral tubercles above midline of flanks, first appear at about 25-mm diameter on average forms, at less 

than 20 mm on coarsely ornamented robust variants, 

may be absent on extremely compressed variants. On 

average outer whorls, lateral tubercles develop into 

forward-curving hornlike spines whose length amounts 

to half the maximum whorl width. Umbilical tubercles 

develop parallel with lateral tubercles on more coarsely 

ornamented variants, fade on outer whorl. Ventrallateral tubercles develop into pronounced clavi on outer 

whorl, alternate in position on either side of low, broadly 

rounded venter, extend above height of midline of 

venter. On outer whorl ribbing weak and irregular, ornamentation dominated by lateral spines and ventrallateral clavi.

Suture ceratitic, like that of P. burckhardti with high 

entire principal saddles, deep LI, coarsely digitate lobes, 

and only one auxiliary saddle.

Discussion. Paraceratites vogdesi shows perhaps the 

greatest range in morphologic variation of any ammonite 

species in the Fossil Hill fauna. Nevertheless, it is 

readily separated from the stratigraphically subjacent 

and also variable P. clarkei by the position of the lateral 

tubercles or spines which are above the midline of the 

flanks in the former and on the lower flanks of the latter. 

The broad, low venter of P. vogdesi and the relative 

prominence of the ventral-lateral clavi compared with 

the lateral spines distinguish this species from P. cricki 

and P. burckhardti which occur respectively higher and 

lower in the section.

Paraceratites clarkei was erroneously considered 

morphologically and stratigraphically transitional from 

P. vogdesi to P. cricki by Silberling (1962, p. 156). 

Further collecting proved this interpretation incorrect, 

and no clearly transitional forms were found between the 

stratigraphic occurrence of these two species. Possible 

intergradation between P. vogdesi and P. cricki might be 

represented by the specimens described by Smith as 

Ceratites (Paraceratites) trojanus and questionably included here in the revised P. vogdesi. The lateral spines 

of these forms are borne high on the flanks as in P. 

vogdesi but, like those of P. cricki, are much more 

pronounced than the weak ventral- lateral tubercles.

As pointed out by Spath (1934, p. 436), the specimens 

from fossil Hill assigned by Smith to Paraceratites 

trinodosus Mojsisovics, which are included here partly in 

P. vogdesi and partly in P. clarkei, developed coarser 

sculpture than the Alpine types of this species. 

Nevertheless, among the wide range of morphologic 

variants assigned here to P. clarkei, individuals closely 

similar to the types of P. trinodosus are expectable, and 

among the variants of P. vogdesi some specimens are 

very close to the typical specimens of the Alpine species 

Ceratites fissicostatus Hauer and C. ecarinatus Hauer. 

Despite their priority, application of any of these Alpine
34 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

specific names to the species of Paraceratites recognized 

herein from Nevada seems unwise because the 

morphologic range of the populations represented by 

these European names is unknown, and on a population 

basis the European species may differ considerably. 

These European specific names represent a different 

kind of concept than the specific entities recognized here 

and the two are not strictly comparable. Until the European and Nevadan species can be compared on a population basis it seems preferable for the purpose of taxonomy to regard Smith's usage of these European names 

as misidentifications.

Figured specimens. Plesiotypes, USNM 248754 to 

248763.

Occurrence. Paraceratites uogdesi beds, stratigraphically between the occurrence of P. clarkei and P. 

cricki. USGS localities M136 (50+), M136 -5 ft (1.5 m) 

(4), M163 (9), M165 (8), M605 (20+), M606 (24), and 

M967 -9 ft (2.7 m) (3); Rotelliformis zone, vicinity of 

Fossil Hill, Humboldt Range, Nev.

Paraceratites cricki Smith 

Plate 17, figures 6-20

Ceratites (Paraceratites) cricki Smith, 1914, p. 87, pi. 37, figs. 6-9

[holotype], 10-11, 12-13; pi 38, figs. 1-2, 3-4, 5-6, 7-8, 9-10?,

11-12?; pi. 47, figs. 19-21, 22-24?. 

Ceratites (Paraceratites) taurus Smith, 1914, p. 88, pi. 35, figs. 1-2

[holotype], 3. 

Paraceratites cricki Smith. Spath, 1934, p. 443. Silberling, 1962, p. 156

[in part].

Revised description. Inner whorls discoidal, compressed (W/D 0.25-0.30); outer whorl more robust (W/D 

between lateral nodes of outer whorl 0.30-0.42). 

Moderately involute (U/D 0.20-0.25), outer whorl 

somewhat more evolute (U/D of robust outer whorls as 

much as 0.30). Maximum diameter exceeds 90 mm; 

compressed forms attain larger diameter than robust 

variants. Ventral-lateral shoulders abrupt, emphasized 

by tubercles on inner whorls. Venter widely variable in 

width proportional to thickness of whorls, raised into 

blunt keel extending well above ventral-lateral tubercles, bluntly fastigate on robust outer whorls.

Ribbing on inner whorls strong and regular. Primary 

ribs branch on lower flank; ribs terminate in projected 

ventral-lateral swellings or tubercles. At about 20-mm 

diameter lateral tubercles develop at bifurcation point of 

primary ribs; weak nonpersistent umbilical tubercles 

may also develop. With increasing shell growth lateral 

tubercles increase rapidly in strength. On outer whorl 8 

to 10 pronounced spinose lateral nodes dominate ornamentation. Ventral-lateral tubercles spaced in regular 

2:1 ratio to lateral nodes or tubercles, with increasing 

shell diameter become clavate and finally coalesce into 

ventral-lateral ridge on orad part of outer whorl.

Suture ceratitic; LI wide, twice depth of L2 and 

divided VL; upper half of SI and S2 entire; only one discrete auxiliary saddle.

Discussion. This is the stratigraphically highest 

species of Paraceratites occurring at Fossil Hill. Its high, 

keeled or fastigate venter and pronounced lateral nodes 

are in strong contrast with the morphology of P. vogdesi 

and P. clarkei, the species occurring successively lower 

in the section. It is therefore surprising that P. cricki 

closely resembles P. burckhardti, the stratigraphically 

lowest paraceratite whose occurrence is separated from 

that of P. cricki by about 6 m of section. The shape of the 

venter and development of tuberculation is the same in 

both species; the principal distinctions between them 

are the more abrupt and angular ventral-lateral 

shoulders of P. cricki and the ratio of ventral-lateral to 

lateral tubercles, which is regularly 2:1 in P. cricki but 

3:1 or more in P. burckhardti. Unfortunately, the 

available stratigraphically controlled collections are insufficient to show whether P. cricki is j homeomorph of 

P. burckhardti derived through transitions with the 

stratigraphically intervening P. clarkei and P. vogdesi, 

or whether it represents a morphologic stock that suddenly reappears in the section, presumably by migration 

from some other area.

The holotype of P. cricki is from the New Pass Range, 

about 100 km southeast of the Humboldt Range, where it 

has been collected subsequently from beds now assigned 

to the Favret Formation. Specimens from the Favret 

Formation in the Augusta Mountains, about 55 km eastsoutheast of Fossil Hill, were found in association with 

Gymnotoceras blakei and Tropigymnites sp. and are 

thus from a stratigraphic level comparable to that at 

which P. cricki occurs at Fossil Hill.

Figured specimens. Plesiotypes, USNM 248764 to 

248770 from the vicinity of Fossil Hill in the Humboldt 

Range.

Occurrence. Paraceratites cricki beds, above the occurrence of P. vogdesi, and with populations transitional 

between Gymnotoceras rotelliformis and G. blakei. 

USGS localities M605 +10 ft (3 m) (1), M607 (40+), and 

M967 (10+); Rotelliformis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

Genus EUTOMOCERAS Hyatt, 1877 

Eutomoceras cf. E. lahontanum Smith

Plate 18, figure 1

cf. Eutomoceras lahontanum Smith, 1914, p. 63, pi. 28, figs. 8-11 

[holotype].

This species was placed in synonomy with 

Eutomoceras dalli Smith in the preliminary summary of 

the Fossil Hill fauna by Silberling (1962, p. 156). It is 

provisionally regarded here as a distinct species because 

its peculiar morphology is not duplicated in the
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 35

available but admittedly small samples of E. dalli, and a 

single specimen that may agree with Smith's holotype of 

E. lahontanum was collected about a meter stratigraphically below the occurrence of E. dalli. This 

specimen, illustrated here, is mainly part of an outer 

whorl on which the ornamentation is reduced, but strong 

bullae, like those of E. lahontanum, can be seen on the 

umbilical part of the penultimate whorl. Also, the width 

of the venter is proportional to that of E. lahontanum 

and greater than that of E. dalli.

Eutomoceras lahontanum may be a connecting link 

between Paraceratites cricki and Eutomoceras dalli; the 

single specimen assigned to E. lahontanum is from a 

stratigraphic position intermediate between those of 

these two species. On E. lahontanum the strong umbilical bullae and distinct ventral-lateral shoulders, 

which on the holotype are ornamented by widely spaced 

paired tubercles, suggest affinity to Paraceratites cricki. 

But the discrete high keel, the origin of the bullae at the 

umbilical shoulder, and the bifurcating falcoid ribs of E. 

lahontanum are more in agreement with Eutomoceras.

Figured specimen. Plesiotype, USNM 248771.

Occurrence. USGS locality M610 (1), lower part of 

Gymnotoceras blakei beds, Rotelliformis Zone, vicinity 

of Fossil Hill, Humboldt Range, Nev.

Eutomoceras dalli Smith 

Plate 18, figures 2-7

Eutomoceras (Halilucites) dalli Smith, 1914, p. 65, pi. 29, figs. 1-4

[holotype], 5, 6-8, 9-10?. 

Hungarites fittingensis Smith [in part], 1914, p. 58, pi. 90, figs. 5-7

[holotype] [not? pi. 29, figs. 12-14 = ^Eutomoceras dunni Smith] 

Eutomoceras dalli Smith [in part]. Silberling, 1962, p. 156. 

[not] Hungarites aff. H. fittingensis Smith. Kiparisova, 1961, p.

164-165, pi. 32, figs. 3a-3c.

Eutomoceras dalli is the stratigraphically lowest of an 

evidently intergraditional succession of species that includes E. dalli, E. dunni, and E. laubei. Compared with 

younger species of this series, E. dalli has a wider umbilicus (U/D about 0.25), thicker whorls, a wider venter, 

and coarser ribbing that commonly branches from 

enlarged primary ribs on the lower flanks. The development of irregularly spaced papillae on the ribs, a feature 

characteristic of Eutomoceras, is widely variable among 

individuals of a single population. Papillation is 

generally absent at shell diameters of less than 30 mm; 

on the outer whorl the strong ornamentation is reduced 

to discontinuous smooth weak ribs.

As suggested by Spath (1951, p. 11), the holotype of 

"Hungarites" fittingensis Smith is a fragment of the 

outer whorl of a Eutomoceras; the remainder of this 

specimen is restored with plaster. Traces of coarse papillae are visible on the apicad part of this fragment, and its 

whorl shape and proportions are like those of E. dalli.

Smith's paratype of "Hungarites" fittingensis, also part 

of an outer whorl, is more like E. dunni in shape.

The assignment by Smith of E. dalli to Halilucites, 

which he treated as a subgenus of Eutomoceras, seems 

incorrect in view of the nonpapillate ribbing of the 

typical European representatives of Halilucites. Spath 

(1951, p. 11) was probably correct that Eutomoceras and 

Halilucites are distinct, perhaps geographically isolated, 

derivatives from Paraceratites.

Figured specimens. Plesiotypes, USNM 248772 to 

248775.

Occurrence. USGS localities M137 (4), M141 (4), 

M611 (11), M613 (7), and M964 (1); Gymnotoceras 

blakei beds, Rotelliformis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

Eutomoceras dunni Smith

Plate 18, figures 8-15

Eutomoceras dunni Smith, 1904, p. 381, pi. 43, fig. 11 [holotype]; pi.

44, fig. 4 [holotype]. Smith, 1914, p. 62, pi. 27, figs. 14-16, 17,

18-19, 20-21, 22-23?, 24-25?. Silberling, 1962, p. 156. 

Eutomoceras breweri Smith, 1914, p. 61, pi. 28, figs. 1-4 [holotype], 5,

6-7a. 

. Eutomoceras laubei Meek [in part]. Smith, 1914, p. 63, pi. 26, figs. 7-8,

9, [not E. laubei on pis. 10, 24, 27, and 90 = Eutomoceras laubei

Meek]. 

[?] Hungarites fittingensis Smith, 1914 [in part], p. 58, pi. 29, figs.

12-14 [not pi. 90, figs. 5-7 = Eutomoceras dalli Smith].

Eutomoceras dunni is intermediate between E. dalli 

and E. laubei in the width of its umbilicus (U/D about 

0.20), its whorl thickness, and the strength of its ribbing 

and papillation. As with E. dalli, the development of 

papillation varies among individuals and with the stage 

of growth. Hence, the separation by Smith of E. breweri 

Smith from E. dunni, from which it differs only in the 

weaker development of papillae on the ribs, is impractical.

Figured specimens. Plesiotypes, USNM 248776 to 

248779.

Occurrence. Frechites nevadanus beds at USGS 

localities M137+4 ft (1.2 m) (2), M142 (6), and M614 

(4); Parafrechites meeki beds at USGS localities M166 

(3), M612 (1), M616 (2), M958 (3), and M960 (1); Meeki 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Eutomoceras laubei Meek 

Plate 19, figures 1-6

Eutomoceras laubei Meek, 1877, p. 126, pi. 10, figs. 8-8a [holotype]. 

Hyatt and Smith, 1905, p. 131, pi. 60, figs. 7-10, 11. Smith, 1914, 

[in part], p. 63, pi. 10, figs. 7-10,11; pi. 14, figs. 8-8a; pi. 27, figs. 

1-2, 3-4, 5-7?, 8-10?, 11-13?; pi. 90, figs. 1-4 [not pi. 26, figs. 7-8, 

9 = Eutomoceras dunni Smith]. Silberling, 1962, p. 156.

Among the known species of Eutomoceras, E. laubei is 

the stratigraphically highest. Although the available
36 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

samples are relatively small, complete morphologic transition evidently exists between this species and E. dunni, 

which is characteristic of the beds immediately underlying those with E. laubei.

Compared with E. dunni, E. laubei is more finely 

sculptured, lacks enlarged primary ribs on the lower 

flanks, is more involute (U/D about 0.10 to 0.15), and has 

thinner whorls whose flanks converge towards a narrow 

venter.

Following Spath's suggestion, two of the specimens included by Smith (1914) in E. laubei are transferred here 

to E. dunni, with which their relatively evolute coiling is 

in better agreement.

In stating that E. laubei was first discovered by 

geologists of the 40th Parallel Survey in the New Pass 

Range in association with "Acrochordiceras hyatti," 

Smith (1914, p. 64) introduced an unwarranted stratigraphic assumption. In the original description of these 

two species, Meek (1877, p. 128) did indicate that the 

"locality and position" of E. laubei is the same as that of 

"Acrochordiceras hyatti" but for the latter his entry (p. 

126) is simply: "New Pass, Desatoya Mountains [New 

Pass Range], Nevada; Trias." TheTriassic section of the 

New Pass Range, about 100 km southeast of the Humboldt Range, includes ammonite-bearing beds of both 

the Hyatti and Meeki Zones, and there is therefore no 

reason to believe that Eutomoceras laubei, which is 

restricted to the upper part of the Meeki Zone in the 

Humboldt Range, occurs in the Hyatti Zone of the New 

Pass Range.

Figured specimens. Holotype, USNM 12528 

(originally figured by Meek, 1877, pi. 10, figs. 8-8a), 

plesiotypes, USNM 248780 and 248781.

Occurrence. Parafrechites dunni beds, Meeki Zone, 

at USGS localities M618 (7), M619 (6), M959 (1+), and 

M968 (4); lower Occidentalis Zone at USGS localities 

M144 (1), M144 -6 ft (1.8 m) (4), M620 (2), and M962 

(10+); vicinity of Fossil Hill, Humboldt Range, Nev.

Genus NEVADITES Smith

Nevadites Smith, 1914, p. 121 [type species N. merriami Smith, 1914, 

a subjective synonym of Nevadites hyatti (Smith, 1904), by 

original designation].

Stratigraphically restricted collections of Nevadites 

show a wide range in morphologic variation. Because of 

the relatively large size and ornate character of these 

ammonites, bedrock collections sufficiently large and 

well preserved to completely demonstrate a normal frequency distribution and complete morphologic intergradation of variants could not be obtained. 

Nevertheless, the mutual occurrence in a single bed of 

morphologically distinct but closely related forms 

evidences their specific identity.

All of the ammonites referred by Smith (1914) to 

Anolcites are regarded here as belonging to Nevadites, 

thereby enlarging the original concept of the genus. Even 

in the Stratigraphically highest species, however, in 

which the two rows of ventral spines are closest together, 

no trace of a ventral furrow, the distinguishing feature of 

Protrachyceras, is present. Otherwise, the youngest 

Nevadites, as revised here, are in all respects similar to 

Protrachyceras and are logical direct ancestors of this 

and all other clydonitacids.

Nevadites hyatti (Smith) 

Plate 22, figures 24-29; plate 23, figures 1-7

Trachyceras (Anolcites) hyatti Smith, 1904, p. 389, pi. 43, fig. 12

[holotype]; pi. 45, figs. 1 [holotype], 2. 

Nevadites hyatti (Smith). Smith, 1914, p. 124, pi. 77, figs. 1-3, 4-5,

6-8, 9-11?, 12-13?. Silberling, 1962, p. 157. 

Nevadites merriami Smith, 1914, p. 125, pi. 75, figs. 1-3 [holotype],

4-6, 7-8, 9-11,12-14; pi. 76, figs. 1-2?, 3-6?, 7-10?, 11-13?, 14-16.

Inner whorls at diameters of about 20 mm have regular 

ribbing with umbilical and ventral tubercles and a subrectangular cross section with the width nearly equal to 

the height. With increasing shell diameter the whorl outline becomes hexagonal as lateral spines develop and 

become increasingly pronounced slightly above the 

midline of the flanks. Accompanying increase in relative 

size of the lateral and ventral tubercles, the ribs become 

increasingly coarse, irregular, and interrupted. On large 

shells the whorl width measured at the interspaces is 

about the same as or a little greater than the height; the 

maximum width measured to the tips of the lateral 

spines may be as much as twice the corresponding whorl 

height.

Except for weak extensions of the ribs, the venter is 

smooth and flattened at all growth stages. The ratio of 

ventral width between the tips of the ventral spines to 

the whorl height averages about 0.60 for small shells and 

about 0.70 for the largest specimens; the range in this 

ratio for outer whorls is 0.55-0.75.

Populations of Nevadites hyatti, as revised, in comparison with the Stratigraphically higher populations of 

N. humboldtensis, as revised, include specimens that on 

the average have thicker whorls, broader venters, fewer 

but stronger ribs, and more pronounced tuberculation. 

These distinctions are apparent only in comparing populations from different stratigraphic levels; the 

morphologic variation of the two species overlaps and 

complete transition between them could take place 

within Stratigraphically intermediate samples.

The basis for separating the six species that Smith assigned to Nevadites into these two morphologically more 

encompassing species is illustrated by the scatter 

diagram (fig. 19) on which the width of the venter
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 37

measured between the tips of the ventral spines is plotted against the corresponding whorl height for two sets of 

specimens, one set representing a stratigraphic level 

2-2.5 m higher than the other. A similar diagram, in 

which the scattering of points representing specimens 

from different levels would fall into two distinct but 

overlapping areas, could be obtained by plotting whorl 

width against whorl height. Figure 19 shows that Smith's 

"species" conform to one or the other cluster of points 

that are regarded here as characterizing the revised 

species N. hyatti and N. humboldtensis^^ ______ 

Younger species referred here to Nevadites, but 

originally included by Smith (1914) in A no kites, differ

co cc

LU

CO 

LU

0. 

CO

18

16

. 14

cc

Z 12

LU

CO

Eb 10

LU 8 

00

"XX

10 14 18 22 26 30 

WHORL HEIGHT BETWEEN TUBERCLES, IN MILLIMETERS

FIGURE 19. Scatter diagram comparing the width across the venter 

between the tips of the ventral spines to the corresponding whorl 

height measured between the tubercles for specimens in population 

samples of Nevadites from different stratigraphic levels. Dots are 

specimens of N. hyatti, revised, from USGS localities M144 6 ft 

and M962; crosses are specimens of N. humboldtensis, revised, 

from the stratigraphically higher USGS localities M144 and 

M962A. For comparison, the trend of width between the ventral 

spines with increasing whorl height is plotted as a dashed line for 

each holotype of five of the so-called "species" of Nevadites 

recognized by Smith (1914). Comparable lines for the specimens assigned to N. whitneyi (Gabb) by Smith (1914) would be close to 

those representing the type specimens of Smith's "species" here included in N. humboldtensis.

from both N. hyatti and N. humboldtensis in having four 

or more rows of tubercles in addition to being generally 

more discoidal and involute and in having a narrower 

venter between the rows of ventral spines.

Figured specimens. Holotype, USNM 74268 

(originally illustrated by Smith, 1904, pi. 43, fig. 12 and 

pi. 45, fig. 1), plesiotypes, USNM 248827 to 248831.

Occurrence. USGS localities M144 -6 ft (1.8 m) 

(11), M621 (11), and M962 (21); lower part of Nevadites 

beds, Occidentalis Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Nevadites humboldtensis Smith 

Plate 23, figures 8-19; plate 24, figures 1-4

Nevadites humboldtensis Smith, 1914, p. 123, pi. 78, figs. 1-3 

[holotype]; pi. 79, figs. 1-3, 4-6, 7-8, 9-10. Silberling, 1962, p. 157.

Nevadites fontainei Smith [in part], 1914, p. 122, pi. 41, figs. 23?, 

24-25?, 26-27?; pi. 51, figs. 1-4 [holotype]. [Not pi. 41, figs. 16-17, 

18-19, 20-22, pi. 51, figs 5-9 = Paraceratites clarkei Smith, 

revised].

Nevadites sinclairi Smith, 1914, p. 126, pi. 81, figs. 17-19 [holotype]; 

pi. 82, figs. 1-3.

Nevadites whitneyi (Gabb) [in part]. Smith, 1914, p. 126, pi. 80, figs. 

1-3, 4-5, 6-8; pi. 81, figs. 1-3, 4-5, 6-7, 8-9, 10-13, 14-16? [not? 

pi. 48, figs. 4-5 copied from Gabb (1864), genus and species unrecognizable].

Ceratites beecheri Smith [in part], 1914, p. 94, pi. 43, figs. 15-17 

[holotype], 21-22, 23-24?, 25-26? [not figs 18-20 = Paraceratites 

clarkei].

[?] Trachyceras (Anolcites) gracile Smith, 1914, p. 132, pi. 82, figs. 4-5 

[holotype], 6-7?, 8-9?.

The morphologic variation within populations included in Nevadites humboldtensis overlaps that of N. 

hyatti, but as a whole specimens of the former have narrower whorls (W/H about 0.90 measured at the interspaces), denser and more regular ribbing, and relatively 

weaker tuberculation than those of the latter.

Lateral tubercles appear early in the ontogeny of N. 

humboldtensis and are commonly well developed at 

diameters less than 15 mm. On the outer whorls the 

lateral tubercles of densely ribbed, relatively highwhorled variants are relatively small and are located just 

below the midflanks, whereas on coarsely ornamented 

variants they are on the upper flanks.

As with N. hyatti, the venter of N. humboldtensis is 

smooth and flattened at all growth stages; a low keel like 

those on the Paraceratites described by Smith as 

paratypes of N. fontainei is never present. The ratio of 

ventral width between the tips of the ventral spines to 

whorl height averages about 0.50 for whorls of more than 

15 mm in height; the extremes for outer whorls range 

from 0.40 to 0.63 and thus overlap the range of ratios for 

N. hyatti (fig. 19).

Ornamentation of the holotype of N. humboldtensis is 

coarser than that of average specimens in populations included under this name and is more like that of N.
38 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

hyatti. However, none of the populations to which the 

latter name is applied include specimens with such a 

narrow ventral width or with whorls as high in proportion to their width.

One of the two specimens of Ceratites whitneyi Gabb 

originally illustrated by Gabb (1864) was selected as the 

type of "Trachyceras" americanum by Mojsisovics 

(1886, p. 149), leaving the specimen portrayed by Gabb's 

plate 4, figures 11 and lla as the implicit type of C. 

whitneyi. This specimen, for which no locality is given in 

the original description, was considered a Nevadites by 

Smith, and if this were so, N. whitneyi (Gabb) would be 

the prior name for the specimens included here in N. 

humboldtensis. Part of the type lot of Ceratites 

whitneyi, including three small unfigured specimens 

(ANSP 1222-1224) of Nevadites and the holotype 

of "Trachyceras" americanum Mojsisovics (ANSP 

1220-1221, different numbers for two parts of the same 

specimen), were located at the Academy of Natural 

Sciences of Philadelphia with Gabb's original label. The 

specimen corresponding to Gabb's figures 11 and lla on 

plate 4 could not be found, and a note written by 

Alpheus Hyatt and found with the type lot indicates that 

this specimen has been missing since before 1900. The 

small, numbered specimens of Nevadites in the type lot 

were contained in a pillbox from a drug store in Palo 

Alto, Calif., suggesting that J. P. Smith of Stanford 

University may have borrowed this collection at some 

time during his study of the Middle Triassic fauna and 

perhaps based his concept of C. whitneyi upon them. 

Because the figured type is missing and Gabb's illustrations of it (pi. 4, figs. 11, lla) are unrecognizable, C. 

whitneyi is considered here a nomen dubium. The distance between the ventral spines shown on Gabb's 

diagrammatic whorl outline (fig. lla) is considerably 

less than that of Nevadites humboldtensis, and the 

specimen portrayed might be a younger Nevadites or 

even a Protrachyceras, assuming that it came from the 

Middle Triassic of the Humboldt Range.

Figured specimens. Plesiotypes, USNM 248832 to 

248839.

Occurrence. USGS localities M144 (25+), M620 

(18+), M622 (15+), M961 (25+), and M962A (20+); 

Nevadites humboldtensis beds, Occidentalis Zone, 

vicinity of Fossil Hill, Humboldt Range, Nev.

Nevadites furlongi (Smith)

Plate 24, figures 5-7

Trachyceras (Anolcites) furlongi Smith, 1914, p. 130, pi. 83, figs. 1-4 

[holotype], 5-7; pi. 84, figs. 1-2, 3-5, 6-8, 9-11?, 12-13?.

[?] Trachyceras (Anolcites) meeki Mojsisovics [in part], Smith, 1904, 

pi. 45, fig. 3.

Compared with Nevadites gabbi, which occurs 5 to 10 

ft higher in the section, N. furlongi has more robust

whorls, a wider umbilicus, coarser ribs, and stronger 

tubercles. From older species of the genus, N. furlongi 

differs in having besides the umbilical and ventral rows 

of tubercles both a ventral-lateral and a lateral row of 

tubercles. The ribs bifurcate at the lateral row, which 

migrates to the upper flank and becomes exaggerated in 

size on the outer whorl.

Figured specimens. Plesiotypes, USNM 248840 and 

248841.

Occurrence USGS localities M145 (3), M623 (8), 

and M625 (3); Nevadites furlongi beds, Occidentalis 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Nevadites gabbi (Smith) 

Plate 24, figures 8-11

Trachyceras (Anolcites) gabbi Smith, 1914, p. 132, pi. 9, figs. 3-6, 7-9?,

10-12?, 13-15?, 16-17?; pi. 11, figs. 4-5, 6-7?; pi. 85, figs. 11-12

[holotype]; pi. 86, figs. 1-3, 4-6, 7-9?, 10-11?. 

Trachyceras (Anolcites) meeki Mojsisovics. Hyatt and Smith, 1905 [in

part], pi. 59, figs. 3-6, 7-9?, 10-12?, 13-15?, 16-17?; pi. 74, figs.

4-5, 6-7?. 

[l]Trachyceras (Anolcites) meeki Mojsisovics. Smith, 1904 [in part],

pi. 45, fig. 4.

Nevadites from the stratigraphically highest of the 

beds characterized by this genus agree with Smith's concept of "Anolcites" gabbi but are difficult to compare 

with the poorly preserved type specimens of this species.

Compared with N. furlongi, the whorls of AT. gabbi are 

higher and narrower, and the ribbing and tuberculation 

are more delicate. The inner whorls have four rows of 

tubercles as with N. furlongi, but with growth two additional lateral rows commonly developed. In his original 

description, Smith mentioned only four rows, and his 

statement (Smith, 1914, p. 131) that the spines of 

"Anolcites"gabbi are more numerous than those of "A." 

furlongi may be in reference to the number of spines per 

spiral rather than the number of rows of spirals. 

Nevertheless, some specimens with the delicate ornamentation of N. gabbi develop as many as six rows. 

Unfortunately, the number of spine spirals on the 

holotype is indefinite owing to its poor preservation.

Figured specimens. Plesiotypes, USNM 248842 and 

248843.

Occurrence. USGS localities M146 (6), M624 (8), 

and 7M626 (1); Nevadites gabbi beds, Occidentalis 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Family HUNOARITIDAE Waagen, 1895

Genus HUNOARITES Mojsisovics, 1879

Hungarites sp.

Plate 20, figures 13-14

A single poorly preserved specimen of this genus was 

collected from the upper member of the Prida Formation 

at Congress Canyon, associated wiihDaonella lommeli,
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 39

Proarcestes, and shell fragments of Protrachyceras? of 

late Ladinian age. Though not adequate for specific assignment, the specimen is illustrated here as the only 

true Hungarites yet found in the Middle Triassic of the 

Humboldt Range.

The suture could not be exposed, but the nearly 

smooth flanks, proportions of the fastigate venter, and 

degree of involution closely resemble those of the septate 

inner whorls of Hungarites pradoi illustrated by 

Mojsisovics (1882, pi. 32, figs. 7, 8) from the Ladinian of 

Spain and of the specimen assigned to the same species 

by Diener (1908, p. 18, pi. 4, fig. 11) from the Ladinian 

Daonella shales of Spiti.

Figured specimen. Plesiotype, USNM 248790.

Occurrence. USGS locality M907; upper part of the 

upper member of the Prida Formation, Congress Canyon, Humboldt Range, Nev.

Superfamily PINACOCERATACEAE (Mojsisovics, 1879)

Family JAPONITIDAE Tozer, 1971

Genus TROPIGYMNITES Spath, 1951

Tropigymnites planorbis (Hauer)

Sibyllites planorbis Hauer, 1896, p. 271, pi. 12, figs. 1-8. 

Tropigymnites planorbis (Hauer). Spath, 1951, p. 102.

Tropigymnites? cf. T. Planorbis (Hauer)

Plate 26, figures 1-4

Gymnites (Anagymnites) acutus Hauer. Smith, 1914, p. 54, pi. 97, figs.

13-14. 

Tropigymnites planorbis (Hauer). Silberling, 1962, p. 157.

Following the suggestion by Spath (1951, p. 100), 

specimens like that assigned to the gymnitid species 

Anagymnites acutus (Hauer) by Smith (1914) are 

questionably placed in the genus Tropigymnites. Unfortunately, the suture could not be exposed on any of the 

specimens from the Humboldt Range. Because the whorl 

shape and shell proportions of Tropigymnites and 

Anagymnites are similar, Smith's generic assignment remains a possibility. Assignment of the present species to 

Tropigymnites is favored because it occurs stratigraphically below any of the species of Tropigastrites, 

and it may therefore be the earliest representative of the 

succession of celtitid species, each of which characterizes 

a different level of the upper Anisian. Moreover, externally similar specimens found in the Paraceratites cricki 

beds of the Favret Formation in the Augusta Mountains 

have a simple suture pattern like that of Tropigymnites 

with three subammonitic saddles. These specimens from 

Augusta Mountain, which occupy a stratigraphic position intermediate between that of the present species 

and that of Tropigastrites gemmellaroi, differ from the 

present species only in having a narrower umbilicus and 

higher whorls.

At comparable shell diameters the specimens 

provisionally assigned here to Tropigymnites planorbis 

have somewhat higher and more compressed whorls than 

the typical specimens from the Dinaric Alps as illustrated by Hauer (1896).

Figured specimens. Plesiotypes USNM 248844 and 

248845.

Occurrence. USGS localities M136 (4) and M605 (1), 

Paraceratites vogdesi beds, Rotelliformis Zone, vicinity 

of Fossil Hill, Humboldt Range, Nev.

Genus JAPONITES Mojsisovics, 1893 

Japonltes cf. J. sugriva Diener

cf. Japonites sugriva Diener, 1895, p. 32, pi. 7, figs, la-lc.

A single specimen collected in the Humboldt Range by 

I. C. Russell and Alpheus Hyatt in 1888 is the only 

known representative of Japonites found thus far in 

North America.

The maximum preserved diameter of about 135 mm of 

this specimen approximately corresponds to the end of 

its phragmocone. Its evolute coiling, robust subtrigonal 

whorl shape, and ornamentation of radial umbilical folds 

are comparable to those of Japonites sugriva Diener. The 

suture could not be prepared in detail, but its general 

plan is like that characteristic of Japonites, having three 

prominent lateral saddles followed by a series of low auxiliary elements that are directed radially and do not form 

a retracted suspensive lobe like that distinctive of Gymnites.

Russell and Hyatt's locality description reads simply 

"Star Peak Triassic Unionville, Nevada," which might 

suggest that the specimen came from the Hyatti Zone, 

the most fossiliferous part of the section in the immediate vicinity of Unionville. This source is confirmed 

by a small ammonite embedded in the matrix that fills 

the small part of the body chamber preserved on the 

specimen. This small ammonite is like those from USGS 

Mesozoic locality M2829, and elsewhere in the Humboldt Range, that may be finely ornamented variants of 

Unionvillites hadleyi Smith and that have been found 

only in the upper part of the Hyatti Zone.

Family GYMNITITIDAE (Waagen, 1895)

Genus GYMNITES Mojsisovics, 1882

Gymnites tregorum n. sp.

Plate 31, figures 6-12, text-figure 20 

Leiophyllites! sp. A. Silberling and Wallace, 1969, p. 17, table 1.

Description. Discoidal, compressed (W/D 0.20-0.25); 

evolute (U/D 0.35-0.40). Flanks flattened and venter 

evenly rounded. Umbilical wall low and steep.

Shell surface smooth except for weak, irregular, 

slightly falcoid radial folds that cross the venter.
40 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Suture ammonitic. On one poorly preserved specimen 

three principal elements are recognized. First saddle is 

coarsely crenulate.

Discussion. Compared with the specimens assigned 

here to Gymnites perplanus from the Hyatti Zone in the 

Humboldt Range, G. tregorum has lower whorls, 

stronger surficial ornamentation, and a less subdivided 

SI. G. tregorum also does not attain the large size of G. 

perplanus.

This species is named in honor of Mr. and Mrs. R. H. 

Trego of Unionville, Nev.

Figured specimens. Holotype USNM 248915; paratypes USNM 248914, 248916, and 248917.

Occurrence. USGS Mesozoic localities M2358 (30+) 

and M2367 (14+); Caurus Zone, northern Humboldt 

Range, Nev.

FIGURE 20. Suture line (X 4) of Gymnites tregorum n. sp. Paratype, 

USNM 248917.

Gymnites perplanus (Meek) 

Plate 30, figures 11-16; text-figure 21

Arcestes? perplanus Meek, 1877, p. 120, pi. 11, figs. 7-7a. 

Gymnites perplanus (Meek). Smith, 1914, p. 54, pi. 15, figs. 7-7a.

This species is characteristic of the Hyatti Zone in the 

northern part of the Humboldt Range. The original two 

specimens on which the species is based were collected 

by the 40th Parallel Survey in the vicinity of Buena 

Vista Creek canyon where this zone is the most fossiliferous part of the section. Smith (1914, p. 54) 

recorded Gymnites perplanus from the upper Anisian at 

Fossil Hill in the southern part of the Humboldt Range, 

but this occurrence is not documented.

The suture of G. perplanus, illustrated here for the 

first time, is like that characteristic of the genus and has 

two complexly subdivided principal lobes and a 

retracted suspensive lobe that is subdivided into auxiliary elements. As in other species of the genus, LI is 

much larger than L2, and S2 is somewhat larger than SI. 

The suture of G. perplanus, as observed in several 

specimens, differs from that of species occurring at 

higher levels in the Anisian of the Humboldt Range 

chiefly in the number of auxiliary elements on the 

suspensive lobe. External of the umbilical seam are only 

three individualized, trifid auxiliary lobes, whereas 

younger species that are no more involute than G.

perplanus are characterized by five or more such lobes. A 

relatively small number of discrete auxiliary elements 

may also be characteristic of other species like G. 

sankara Diener from India and G. uolzi Welter from 

Timor that are from deposits of probable mid-Anisian 

age and hence of about the same age as G. perplanus.

Figured specimens. Holotype, USNM 12531 

(originally figured by Meek, 1877, pi. 11, figs. 7-7a); 

plesiotypes, USNM 248908 and 248909.

Occurrence. USGS localities M533 (8), M970 (1); 

USGS Mesozoic localities M1180 (2), M1181 (3), M1184 

(2), M2826 (1), and M2829 (5); Hyatti Zone in northern 

part of the Humboldt Range, Nev.

FIGURE 21. Suture line (X 1.75) of Gymnites perplanus (Meek). 

Plesiotype, USNM 248909.

Gymnites cf. O. humboldti Mojsisovics

Plate 31, figure 1; text-figure 22

cf. Gymnites humboldti Mojsisovics, 1882, p. 235, pi. 55, figs. 1-3. 

Gymnites cf. G. incultus (Beyrich, 1867). Silberling, 1962, p. 158.

A single phragmocone of a relatively involute (U/D 

0.28), compressed Gymnites having a maximum 

preserved diameter of about 100 mm was collected in 

place from the Gymnotoceras blakei beds of the Rotelliformis Zone in the vicinity of Fossil Hill. Except for 

conspicuous falcoid growth striae of irregular strength, 

the shell is smooth and lacks the spiral row of tubercles 

characteristic of Epigymnites alexandrae Smith, which 

occurs stratigraphically higher. The suspensive lobe of 

the suture (fig. 22) is subdivided by six or possibly seven 

discrete auxiliary lobes, which is twice the number found 

in G. perplanus (Meek) from the Hyatti Zone. The 

suture pattern, lack of ornamentation, and degree of inFIGURE 22. Suture line (X 1.75) of Gymnites cf. G. humboldti 

Mojsisovics. Plesiotype, USNM 248911. Some fine detail lost in 

preparation.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 41

volution of this specimen are comparable to those of G. 

humboldti Mojsisovics, which was originally described 

from the upper Anisian of the Hallstatt Limestone in 

Austria.

Figured specimen. Plesiotype, USNM 248911.

Occurrence. USGS locality M609, Gymnotoceras 

blakei beds, Rotelliformis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

Gymnites? call! Smith 

Gymnites calli Smith, 1914, p. 53, pi. 26, figs. 1-la.

The only known specimen of this species is the 

holotype that was collected near Fossil Hill in the 

southern part of the Humboldt Range. The shell is considerably less evolute (U/D about 0.14) than other 

species of Gymnites from the Humboldt Range and is 

perhaps too tightly coiled for inclusion in this genus as 

presently delimited (Arkell and others, 1957, p. L184). 

The suture pattern, however, is that typical of Gymnites.

Although no additional specimens were found during 

the present study, shell fragments of Nevadites and 

Daonella dubia in the matrix of the type specimen indicate that it was derived from the upper part of the Occidentalis Zone.

Genus EPIGYMNITES Diener, 1916 

Epigymnites alexandrae (Smith)

Plate 31, figure 13

Gymnites alexandrae Smith, 1914, p. 52, pi. 23, fig. 1; pi. 24, figs. 1-2, 

3?, 4-4a?, 5-6?, 7-9?, %-12?; pi. 25, fig. 1?. Silberling, 1962, p. 

156.

Several incomplete specimens from different localities 

in the vicinity of Fossil Hill are ornamented by a single 

spiral row of tubercles on the middle of the flank and 

otherwise agree in whorl shape and suture pattern with 

this species. The stratigraphically lowest of these 

specimens is from the Parafrechites dunni beds at the 

top of the Meeki Zone and the highest is from the 

Subasperum Zone. Epigymnites alexandrae thus ranges 

through the upper part of the upper Anisian and at least 

the lower part of the lower Ladinian.

An imprint of Daonella cf. D. moussoni on the type 

specimen of G. alexandrae (Smith, 1914, pi. 23, fig. 1) indicates that it was derived from the upper part of the Occidentalis Zone. The ratio U/D for this specimen is 0.365. 

The "cotype" (Smith, 1914, pi. 25, fig. 1; Stanford 

University type colln. no. 5429) is appreciably more involute (U/D 0.305) and generally resembles G. ecki 

Mojsisovics, which was originally described from the 

calcare di Clapsavon of northeastern Italy and is supposedly of late Ladinian age.

Figured specimen. Plesiotype, USNM 248918.

Occurrence. USGS localities M619 (1), Parafrechites 

dunni beds, upper part of Meeki Zone; M624 (2) and 

M625 (1), upper part of Occidentalis Zone; one float 

specimen from the Occidentalis Zone of collecting-site 

C; USGS Mesozoic locality M 3094 (1), Subasperum 

Zone; vicinity of Fossil Hill, Humboldt Range, Nev.

Family STURIIDAE (Kiparisova, 1958) 

Genus STURIA Mojsisovics, 1882 

Sturia cf. S. japonica Diener, 1915

Plate 30, figures 17-18 

cf. Sturia japonica Diener, 1915b, p. 18, pi. 6, figs. 1-2.

Part of a large septate whorl of Sturia, having a maximum whorl height of about 150 mm, was found in the 

Fossil Hill area as float derived from the Meeki Zone or 

stratigraphically higher. The suture of this specimen 

cannot be traced in detail, but it is illustrated 

photographically to show its general pattern and the 

degree of complexity of its subdivision.

According to Kiparisova (1961, p. 180), Sturia 

japonica differs from the type species, S. sansovinii 

(Mojsisovics), mainly in having the spiral furrows on the 

umbilical part of the flanks more widely spaced, but the 

validity of this specific distinction has perhaps not been 

adequately tested as implied by Onuki and Ban do (1959, 

p. 101) who placed the two species in synonymy.

Figured specimen. USNM 248910.

Occurrence. Float at USGS locality M614, Meeki 

Zone (?), vicinity of Fossil Hill, Humboldt Range, Nev.

Genus DISCOPTYCHITES Diener, 1916 

Discoptychites sp.

Text-figures 23 and 24

^.Discoptychites evansi (Smith). Silberling, 1962, p. 157. 

[?] Ptychites evansi Smith, 1914, p. 47, pi. 21, figs. 3-3a.

A septate fragment of the ventral part of a large ammonite having the compressed, subtrigonal whorl shape 

and suture pattern of Discoptychites was collected in 

place from the Paraceratites clarkei beds of the Rotelliformis Zone at Fossil Hill. This fragment could belong 

to the same species as the specimen named Ptychites 

evansi by Smith (1914) though this specific name should 

probably be regarded as a nomen dubium. Smith's 

specimen lacks outer whorls comparable in size to the 

present specimen, but its whorl shape is similar, and 

fragments of Daonella americana in its matrix indicate 

that it came from either the Rotelliformis or Meeki 

Zones.

Other than the Sturia previously described, the only 

other ptychitid found thus far in the Humboldt Range is
42 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

an indeterminate immature specimen of Ptychitest from 

the Meeki Zone at USGS Mesozoic locality M960.

Figured specimen. USNM 248985.

Occurrence. USGS locality M139, Paraceratites 

clarkei beds, Rotelliformis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

FIGURE 23. Suture line (X 1.5) of Discoptychites sp. Figured 

specimen, USNM 248985.

TIP OF FIRST 

LATERAL SADDLE

FIGURE 24. Diagrammatic cross section (natural size) of the outer 

part of an incomplete whorl of Discoptychites sp.; dotted where inferred. Figured specimen, USNM 248985.

Family ISCULITIDAE Spath, 1951 

Genus ISCULITES Mojsisovics, 1886

Isculites Mojsisovics, 1886, p. 154 [type species/, hauerinus (Stolicska)

by monotypy]. 

Smithoceras Diener, 1907, p. 97 [type species S. drummondi Diener by

monotypy]. 

Spitisculites Diener, 1916, p. 101 [type species Isculites hauerinus

(Stolicska) by original designation]. 

Alloptychites Spath, 1951, p. 151 [type species Ptychites meeki Hyatt

and Smith by original designation].

Isculites meeki (Hyatt and Smith) 

Plate 28, figures 10-18; plate 29, figures 10-13; text-figure 25

Ptychites meeki Hyatt and Smith, 1905, p. 87, pi. 25, figs. 6-8 

[holotype], 8-10, 11-12. Smith, 1914, p. 47, pi. 6, figs. 6-8, 8-10, 

11-12.

Alloptychites meeki (Hyatt and Smith). Spath, 1951, p. 151.

Isculites meeki (Hyatt and Smith). Silberling and Wallace, 1969, table 

1, p. 17.

Revised description. Inner whorls moderately involute and subglobose with evenly rounded venter and 

flanks; at diameters of 20-30 mm W/D = 0.50-0.75 and 

mean U/D = 0.22 for nine specimens; umbilical shoulder 

narrowly rounded, umbilical wall steep, nearly perpendicular. Outer whorls slightly uncoiled and more compressed, generally with flattened, subparallel flanks; at 

diameters > 40 mm W/D is mostly 0.40-0.50 and mean 

U/D = 0.254 for 13 specimens; umbilical wall shallower 

and more sloping as a function of egression. Maximum 

diameter exceeds 75 mm, but specimens having 

diameter > 50 mm uncommon.

Surface smooth except for growth striae of irregular 

strength. One or more constrictions and flares near aperture.

Suture only known from holotype; weakly subammonitic; SI, S2, and S3 of equal height, SI and S2 

broadly rounded in shape; LI and L2 of equal depth and 

width, equal to VL in depth.

Discussion. The type lot of this species is from the 

Whitney collection in the Museum of Comparative 

Zoology, Harvard University, and was originally collected at Star Creek canyon in the Humboldt Range. 

Hyatt and Smith (1905, p. 87; Smith, 1914, p. 47), for 

reasons not stated, gave the stratigraphic horizon as 

lower Ladinian, but during the present study /. meeki 

has only been found in the lower Anisian Caurus Zone in 

the vicinity of Star Creek canyon.

None of the many specimens from the two localities 

from which the present collections were made show the 

details of the suture, but its general plan and the proportions of its major elements are like that of the suture on 

the holotype.

Compared with other species of the genus, when fully 

grown /. meeki is more compressed and its venter remains broadly rounded rather than becoming more narrowly arched as in /. hauerinus. Although the shell 

proportions and rate of maturity are evidently widely 

variable, egression of the outer whorls is definitely 

shown. The relative increase in the size of the umbilicus 

with growth as indicated by the means of the U/D ratios 

for shells smaller in diameter than 30 mm and those 

larger than 40 mm is significant at a probability level of 

0.01.

Figured specimens. Holotype, MCZ 3998 (originally 

figured by Hyatt and Smith, 1905, p. 25, figs. 6-8);
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 43

paratype, MCZ 3900 (originally figured by Hyatt and 

Smith, 1905, pi. 25, figs. 9-10); plesiotypes, USNM 

248882 and 248883; USNM 248891 and 248892.

Occurrence. USGS Mesozoic localities M2358 (75+) 

and M2367 (35+), Caurus Zone between Bloody Canyon 

and Star Creek canyon, Humboldt Range, Nev.

FIGURE 25. Suture line (X 3) oflsculites meeki (Hyatt and Smith). 

Holotype, MCZ 3998.

Isculites tozeri n. sp. 

Plate 30, figures 1-10; text-figure 26

/. n. sp. ex aff. /. drummondi (Diener). Silberling and Tozer, 1968, p.

38. 

Isculites n. sp. Silberling and Wallace, 1969, table 1, p. 17.

Description. Inner whorls moderately involute and 

globose; at diameters of 15-25 mm W/D = 0.65-1.00 and 

the mean U/D = 0.18 for seven specimens; umbilical 

shoulder narrowly rounded, umbilical wall steeply sloping or perpendicular. Outer whorls more compressed 

(W/D = 0.50-0.90 at D > 35 mm) with marked egression 

of umbilical margin (mean U/D = 0.23 for 19 specimens 

of D > 35 mm). Body chamber modified to arched or 

bluntly subtrigonal cross-sectional shape, reverting to 

parabolic cross section at apertural margin. Diameter of 

complete shells mostly 40-50 mm; estimated diameter of 

largest available specimen 50-55 mm.

Surface smooth except for nearly straight growth 

striae of irregular strength. Projected constriction and 

flare just apicad of aperture.

Suture known only from one specimen; subammonitic; SI, S2, and S3 broadly rounded in shape and of 

about equal height and proportions.

Discussion. This species is characteristic of the 

Hyatti Zone, and compared with Isculites meeki from 

the stratigraphically lower Caurus Zone, it has on the 

average a more robust shell. On a scatter diagram (fig. 

27) comparing width and diameter of specimens of 

Isculites tozeri from USGS locality M533 and USGS 

Mesozoic locality M2359 and of /. meeki from localities 

M2358 and M2367 the shell proportions of the two 

species plot in two generally distinct but overlapping 

fields. Both samples of /. meeki plotted on figure 27 show 

about the same variation in shell proportions, as might 

be expected because they were collected only about 0.5 

km apart probably from within the same few meters of 

section. The two plotted samples of /. tozeri, however, 

are from localities several kilometers apart and may 

represent different levels within the Hyatti Zone. They

differ in their average proportions at diameters greater 

than 35 mm, the sample from locality M533 retaining a 

more globose shape of the body chamber. Although W/D 

ratios of the larger specimens of /. tozeri from locality 

M2358 overlap with those of /. meeki, shells of the two 

species are still readily distinguished by their different 

whorl shape, /. meeki having flattened, subparallel 

flanks and /. tozeri having a parabolic or subtrigonal outline widest at the umbilical shoulder.

The only suture line that could be prepared from the 

present samples of /. tozeri is more ammonitically 

crenulated than that of the holotype of /. meeki, but the 

general applicability of this distinction is uncertain.

Of the Indian species herein regarded as belonging to 

Isculites, Smithoceras drummondi Diener (1907, p. 98, 

pi. 12, figs. 3a-3c) is like /. tozeri in its shell proportions, 

shape, and suture line, but the illustrated specimen of 

this species is still septate at a diameter greater than 60 

mm, and it is thus much larger than any of the 

specimens of /. tozeri from Nevada. As S. drummondi is 

known from only two specimens, further comparison 

with /. tozeri is not possible.

Isculites tozeri is named for E. T. Tozer of the 

Geological Survey of Canada.

Figured specimens. Holotype, USNM 248905; 

paratypes, USNM 248904, 248906, and 248907.

Occurrence. USGS locality M533 (40+) and USGS 

Mesozoic locality M2359 (50+), Hyatti Zone, northern 

part of Humboldt Range, Nev. Also represented from the 

Hyatti Zone of the Humboldt Range at USGS Mesozoic 

localities M1181 (2), Ml 182 (2), 7M1183 (5+), 7M2819 

(3), M2821 (6), and 7M2829 (1).

FIGURE 26. Suture line (X 3) of Isculites tozeri n. sp. Holotype, 

USNM 248905.

Superfamily DANUBITACEAE (Spath, 1951)

Family DANUBITIDAE

Genus CZEKANOWSKITES Diener, 1915

Czekanowskites hayesi (McLearn)

Plate 19, figures 16-19

"Ceratites" hayesi McLearn, 1946a, sheet 2, pi. 1, fig. 2. 

Czekanowskites hayesi (McLearn). McLearn, 1969, p. 43-44, pi. 1, figs. 

4-8.

The specimen illustrated is one of the only two found 

of this species and was collected from the Hyatti Zone of 

the Humboldt Range. The suture cannot be observed, 

but externally these specimens are nearly identical with
44 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

EXPLANATION 

Isculites meek/

Type lot 

A Loc. M2367 

O Loc. M2358 

Isculites tozeri 

X Loc. M533 

+ Loc. M2359

20 25 30 

WIDTH, IN MILLIMETERS

FIGURE 27. Scatter diagram comparing width and diameter of 

specimens of Isculites tozeri n. sp. from USGS locality M533 and 

USGS Mesozoic locality M2359 with Isculites meeki (Hyatt and 

Smith) from USGS Mesozoic localities M2358 and M23679 Solid 

lines enclose all points for /. meeki; dashed lines all points for /. 

tozeri.

the holotype of Czekanowskites hayesi , a cast of which 

was provided us through the courtesy of the late F. H. 

McLearn along with casts of several variants.

Figured specimen. Plesiotype, USNM 248785.

Occurrence. USGS locality M970 (1) and USGS 

Mesozoic locality M2359 (1), upper Hyatti Zone, Humboldt Range, Nev.

Genus PSEUDODANUBITES Hyatt, 1900 

Pseudodanubites halli (Mojsisovics)

Plate 19, figures 7-15; text-figure 28

Clydonites laevidorsatus (Hauer). Meek, 1877, p. 109, pi. 10, figs. 7

[herein selected as lectotype of Danubites halli Mojsisovics], 7a. 

Danubites halli Mojsisovics, 1896, p. 696 [new name for "Clydonites

laevidorsatus (Hauer)" of Meek, 1877]. 

Tropigastrites halli (Mojsisovics) [in part]. Smith, 1914, pi. 14, figs. 7,

7a [not figs, of "T. halli" on pis. 6, 12,18, and 88 = Tropigastrites

gemmellaroi Arthaber]. 

Pseudodanubites? halli (Mojsisovics). Silberling and Wallace, 1969,

table 1, p. 17.

[not] Celtites halli Mojsisovics. Hyatt and Smith, 1905, p. 125, pi. 25, 

figs. 4-4a, 5, 5a-5b; pi. 75, figs. 1-la, 2-3, 4-5 [= ? Tropigastrites 

gemmellaroi Arthaber].

This specific name was applied by Hyatt and Smith 

(1905) and Smith (1914) to specimens of Tropigastrites 

from the Rotelliformis Zone, but specimens like those 

figured by Meek and for which Mojsisovics proposed the 

name Danubites halli differ from Tropigastrites in whorl 

shape and ornamentation and occur in the Hyatti Zone.

The serpenticone inner whorls of Pseudodanubites 

halli are roughly quadrate in cross section with gently 

rounded umbilical and ventral-lateral shoulders and a 

broadly arched venter. The flanks are ornamented by 

blunt straight ribs and the venter is smooth. A gradual 

change in the shape of the outer whorls is produced by 

further arching of the venter into a bluntly fastigate 

shape. Although the periphery becomes narrowly 

rounded, it is not sharp as in Tropigastrites. Accompanying this change in whorl shape, the ribs first tend to 

become bulbous and enlarged at the ventral-lateral 

shoulder and then on the outer whorl project forward 

onto the venter. The correspondence of ribs on either 

side of the outer whorl is irregular; where they coincide 

in position, they pass over the narrowly rounded ventral 

margin only slightly diminished in strength.

Some variation in whorl compression and strength of 

ribbing occurs among individuals from the same bed. 

Compressed variants tend to have less bulbous ribs, 

which extend onto the venter at a smaller diameter, as 

on the specimen illustrated by figures 7-9, plate 19. This 

particular specimen may be from a somewhat higher 

level than others in the Hyatti Zone but is generally the 

same as some variants found in association with 

specimens like the lectotype.

The suture is simple in plan with three broad, subammonitically crenulate external saddles of about equal 

height. LI is about twice the depth of L2 and slightly 

deeper than VL which is divided by an elongate 

triangular ES.

This species differs from typical Danubites in the 

modified fastigate shape and ornamentation of its outer 

whorl, the absence of any kind of a ventral keel, and its 

subammonitic suture with relatively low and broad saddles. It is assigned to Pseudodanubites, although its 

typical species, P. dritarashtra (Diener, 1895), differs 

from the present species in two important respects: the 

suture, though described as being more advanced than 

that of Danubites, is still ceratitic, and the venter bears 

a "thread-like keel" (Diener, 1895, p. 30). Otherwise, P. 

dritarashtra as described by Diener is in close agreement 

with P. halli in whorl shape and ornamentation.

The relationship of P. halli to some species of 

Tropigastrites that have similar ornament and equally 

evolute coiling, is evidently close. Although the ribs of
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 45

Tropigastrites are restricted to the lower flanks and the 

venter has a sharp fastigate margin, the suture is 

generally the same in plan and degree of complexity. 

Thus P. halli is in some respects intermediate between 

Pseudodanubites and Tropigastrites. This poses a 

problem in familial assignment because these genera are 

currently placed (Tozer, 1971) in different superfamilies: 

respectively the Danubitacea and Nathorstitacea.

Figured specimens. Lectotype, USNM 12522 

(originally figured by Meek, 1877, pi. 10, fig. 7); 

plesiotypes, USNM 248782 to 248784.

Occurrence. USGS Mesozoic localities M1124 (1), 

M1180 (7), M1181 (2), M1184 (1), and M1185 (1), and 

M2829 (10+), Humboldt Range, Nev.

vJA/

FIGURE 28. Suture lines (X 4) of Pseudodanubites halli (Mojsisovics), 

dashed where approximate. A, plesiotype, USNM 248986, specimen 

not figured. B, plesiotype, USNM 248784, suture line reversed.

Genus UNIONVILLITES n. gen.

Type species. Unionvillites hadleyi (Smith).

Definition. Discoidal, strongly evolute; typically 

with low subquadrate to broadly arched whorls. Welldeveloped rounded ventral keel. Regularly spaced, 

typically tuberculate, projected radial ribs. Suture incompletely known but simple and short, having subammonitic saddles, LI much deeper than L2 or VL.

Discussion. Specimens of specie^ included in this 

genus are neither well represented nor completely known 

morphologically. Nevertheless, among mid-Anisian ammonites they embody a unique combination of 

characters quite unlike that of any previously described 

genus. Because they are easily recognized and serve as 

markers for the upper part of the Hyatti Zone, introducing a new genus for them, even though incompletely 

characterized, is useful. No other middle Anisian ammonites, except the inner whorls of longobarditinids, 

possess tuberculate ribbing and a strong persistent 

ventral keel. The outer margin of Balatonites, in which 

Unionvillites hadleyi was originally placed, is quite different in having ventral spines on ribs that cross the 

venter rather than being ventrally carinate.

Unionvillites hadleyi (Smith)

Plate 6, figures 17-23

Balatonites hadleyi Smith, 1914, p. 119, pi. 90, figs. 8-10.

The following description is based largely on Smith's 

holotype plus a few other well-preserved specimens from 

the Tobin Range and Augusta Mountains.

The shell is thickly discoidal (W/D about 0.40 at D less 

than 30 mm), but widely umbilicate (U/D 0.50-0.55). In 

addition to the well-developed, persistent ventral keel, 

ornamentation consists of regularly but widely spaced 

projected primary ribs, each of which bears a bullate 

spine on the flanks and then projects sharply forward, 

fading toward the keel. On the venter between each 

primary rib, an additional rib is inserted and the projection of both primary and secondary ribs tends to serrate 

the keel. The holotype has 16 primary ribs per volution. 

The suture, as partly seen on a specimen from the 

Augusta Mountains, is simple in form, having three 

principal lateral elements and apparently slightly 

crenulate subammonitic saddles. It is mainly distinguished by having VL much shallower than LI.

Figured specimens. Holotype, USNM 74432; 

paratypes, USNM 248649 and 248650.

Occurrence. USGS Mesozoic localities M1181 (1), 

M2829 (1), upper Hyatti Zone, northern Humboldt 

Range, Nev. Better represented in the upper Hyatti 

Zone at the southern tip of the Tobin Range and in the 

Augusta Mountains several tens of kilometers east and 

southeast of the Humboldt Range.

Unionvillites asseretoi n. sp. 

Plate 6, figures 24-28; text-figure 29

Description. Evolute and compressed, at diameter of 

30 mm, W/D = 0.32 and U/D = 0.50. Low subquadrate 

whorls with well-developed, persistent ventral keel. Umbilical wall gently sloping, umbilical shoulder absent.

Ornamentation consists of regularly spaced projected 

ribs with strong ventral swellings. The holotype has 37 

ribs per volution. Suture known only from one specimen; 

subammonitic, three principal elements; VL much shallower than LI. This species is named in honor of the late 

Riccardo Assereto.

Discussion. This species is characteristic of the 

Hyatti Zone, and compared with Unionvillites hadleyi 

from the same stratigraphic level, it has a more discoidal 

shell, more ribs per volution and lacks bullate spines. 

The suture of Unionvillites asseretoi is about the same as 

Unionvillites hadleyi.

Figured specimens. Holotype, USNM 248653; 

paratypes, USNM 248651 and 248652.
46 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Occurrence. USGS Mesozoic locality M2829 (6), upper Hyatti Zone, northern Humboldt Range, Nev.

FIGURE 29. Suture line (X 4) of Unionvillites asseretoi n. sp. 

Paratype, USNM 248652.

Family LONGOBARDITIDAE (Spath, 1951)

Subfamily GROENLANDITINAE Asserto, 1966

Genus LENOTROPITES Popov, 1961

Lenotropites caurus (McLearn)

Plate 29, figures 14-30; text-figure 30

"Hungarites" caurus McLearn, 1948, p. 1, pi. 11, figs. 1, 2. 

Lenotropites caurus (McLearn). Tozer, 1967, p. 69, 71, pi. 7, figs, la, b.

Figured specimens. Plesiotypes, USNM 248893 to 

248900.

Occurrence. USGS Mesozoic localities M2358 (8), 

M2367 (4), M2828 (8+), M2362 (20+); Caurus Zone, 

northern Humboldt Range, Nev.

FIGURE 30. Suture line (X 3) of Lenotropites caurus (McLearn), 

dashed where approximate. Plesiotype, USNM 248896.

Subfamily LONGOBARDITINAE

The species of Longobardites recognized from the 

Humboldt Range are, in stratigraphically ascending 

order: Intornites mctaggarti (McLearn) from the lower 

part of the Hyatti Zone; Longobardites parvus (Smith) 

from the Rotelliformis and Meeki Zones; and L. cf. L. 

zsigmondyi (Bbckh) from the Occidentalis Zone. A 

fourth species, /. nevadanus Hyatt and Smith, which is 

typical of the Shoshonensis Zone in other parts of 

northwestern Nevada, may also occur in the Humboldt 

Range in the upper part of the Hyatti Zone. Intornites 

nevadanus thus occurs in Nevada at a level intermediate 

between that of/, mctaggarti and that of L. parvus and 

is described here on the basis of specimens from the 

Shoshonensis Zone of the New Pass Range in order to 

clarity the correct usage of this name.

Mature shells of all four species of longobarditinids 

from Nevada are smooth, compressed, acutely terminated oxycones and have the same distinctive 

pseudoadventitious suture pattern in which the height of 

S2 exceeds that of SI and the depth of L2 exceeds that of 

LI. The term "pseudoadventitious" was introduced by 

McLearn (1951) because these unusual proportions of 

the principal suture elements result from differential 

development during ontogeny from a normal pattern of 

saddles and lobes that progressively decrease in size dorsally, and this pattern is not a true adventitious arrangement in which the ventral elements are developed by 

subdivision of VL.

Compared with the outer whorls of Intornites mctaggarti and /. nevadanus, those of L. parvus and L. cf. L. 

zsigmondyi have a different configuration of the growth 

lines and are on the average more compressed. The inner 

whorls, however, provide the principal means of 

separating the different species and determining their 

generic assignment. Intornites mctaggarti, the oldest 

species recognized in Nevada, has robust, evolute, 

keeled, ornate inner whorls that pass by gradual transition into the involute, compressed oxyconic mature 

whorls. The distinctive shape and ornament of the inner 

whorls may persist to diameters exceeding 25 mm, and 

the pseudoadventitious suture characteristic of the outer 

whorls is not developed until the whorls are more than 15 

mm high. Successively younger species have young 

stages less divergent from the mature morphology and 

develop the mature oxyconic shape and pseudoadventitious suture line at progressively smaller shell 

diameters. The inner whorls of L. cf. L. zsigmondyi, the 

youngest species, have essentially the same shape as the 

outer whorls at diameters of less than 10 mm. Although 

the morphology of the inner whorls and rate at which 

they mature is widely variable among individuals from 

the same stratigraphic level, little overlap exists between 

the combined characters of different species.

The distinguishing features of the different species are 

given on table 4.

The morphologic differences between successive 

species of longobarditinids in Nevada suggests a 

biogenetic pattern whereby recapitulation of an evolute, 

thick-whorled, costate, carinate, ceratitically septate 

ancestor recedes farther and farther back into the ontogeny of successive species until it is no longer 

recognizable in the youngest of the species. Such an 

evolutionary relationship appears to exist between Intornites mctaggarti and /. nevadanus, which in Nevada 

may be connected by stratigraphically intermediate, 

morphologically transitional populations, and also 

between L. parvus and L. cf. L. zsigmondyi. The 

phyletic relationship between /. nevadanus and L. 

parvus is obscure, but even so, the implication is strong
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 47

 

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that progressive development of the oxyconic shape and 

distinctive suture pattern of Longobardites from a nonoxyconic ceratitic ancestor may have taken place during 

one or more relatively brief parts of Anisian time.

Genus INTORNITES Assereto, 1966 

Intornites mctaggarti (McLearn)

Plate 20, figures 15-35; text-figure 31

Longobardites mctaggarti McLearn, 1946a, p. 2, pi. 2, fig. 5. 

Longobardites larvalis McLearn, 1948, p. 20, pi. 9, figs. 3-4; Silberling

and Tozer, 1968, p. 38. 

Longobardites cf. L. larvalis McLearn. Silberling and Wallace, 1969,

table 1, p. 17. 

Intornites mctaggarti (McLearn). Tozer, 1971, p. 1017.

Description. Mature shell oxyconic, compressed 

(W/D about 0.25); venter narrowly tapered, acutely terminated; umbilicus nearly closed. Diameter of 

phragmocone exceeds 60 mm. Surface smooth except for 

growth lines that describe pronounced convex curve on 

lower flank, recurve about two-thirds of distance across 

flank, and form a smaller convex curve on outer flank.

Inner whorls at diameters less than 10 mm evolute, 

round or depressed oval in cross section, ornamented by 

distinct rounded ventral keel and short, coarse, concave 

radial ribs on lateral margins. Indistinct furrows border 

keel and strigae cross ribs on more depressed, coarsely 

ornamented variants. Whorl shape, strength of ornament, and rate of maturing of inner whorls widely 

variable; at diameter of 15 mm whorl proportions (W/H) 

varies from 0.7 to 1.5, width of umbilicus (U/D) varies 

from 0.15 to 0.40, mostly exceeds 0.25.

Transition to oxyconic mature morphology gradual, 

from 10 to 30 mm. During transition lower flanks ornamented by irregular ribs that commonly bear bullae at 

position corresponding to original lateral ribs of earlier 

whorls.

Suture ceratitic; principal lobes coarsely crenulate; 

principal saddles high and narrow; ES about two-thirds 

height of Si. Sutures closely spaced with sides of successive saddles touching or nearly so. At diameters less than 

15 mm proportions of principal elements normal: in 

height SI equal or greater than S2, S2>S3; in depth 

L1>L2, L2»L3. Two or three auxiliary saddles follow 

S3 whose apex is inside midline of flank. Pseudoadventitious pattern develops by transitions at diameters more 

than 15 mm. On outer phragmocone height and breadth 

of SKS2, S2 = S3; depth and breadth of LKL2, 

L2«L3. Three or four auxiliary saddles follow S3 

whose apex is approximately at midline of flank.

Figured specimens. Plesiotypes, USNM 248791 to 

248799.

Occurrence USGS localities M533 (40+), M969 

(3?); USGS Mesozoic localities M1124 (11), 7M1182 (7), 

7M1184 (1), 7M1185 (2), M2830 (20+), and M2836 (5); 

lower part of Hyatti Zone, Humboldt Range, Nev.

B

FIGURE 31. Suture lines (X 3) of Intornites mctaggarti (McLearn). A, 

plesiotype, USNM 248792. B, plesiotype, USNM 248987, specimen 

not figured.

Intornites nevadanus (Hyatt and Smith) 

Plate 21, figures 1-18; text-figure 32

Longobardites nevadanus Hyatt and Smith [in part], 1905, p. 132, pi. 

25, figs. 13-16 [holotype], 17-18 [not pis. 58 and 75 = L. parvus 

(Smith) and (or) L. cf. L. zsigmondyi (Bockh)]. Smith, 1914, p. 

50, pi. 6, figs. 13-16, 17-18 [not pis. 8, 12, and 30 = L. parvus 

(Smith) and (or) L. cf. L. zsigmondyi (Bockh)]. McLearn, 1951, p. 

13. Silberling and Wallace, 1969, table 1, p. 17.

Longobardites canadensis McLearn, 1946a, p. 1, pi. 3, figs. 1 

[holotype], 5-6. McLearn, 1948, pi. 3, figs. 1, 5-6; pi. 10, fig. 3.

Longobardites intornatus McLearn, 1946, p. 1, pi. 1, fig. 1.

Longobarditoides nevadanus (Hyatt and Smith). Shevyrev, 1961, p. 

74.

[?] Longobardites cf. nevadanus Hyatt and Smith. Frebold, 1930, p. 

302, pi. 1, figs. 11-12.

Longobardites (Intornatus) nevadanus Hyatt and Smith [in part]. Assereto, 1966, p. 963, pi. 69, figs. 5, 7; pi. 70, figs. 1, 3, 4, 6.

Description. Mature shell like that of /. intornatus, 

compressed oxyconic, with narrow, acutely terminated 

venter, closed umbilicus, and asymmetrically biconvex 

growth striae. Maximum diameter of phragmacone exceeds 100 mm.

Inner whorls at diameters of 10 to 15 mm discoidal, 

compressed (W/H mostly 0.4-0.5); flanks broadly 

rounded, narrowly to bluntly convergent; umbilicus narrow but open (U/D 0.05-0.15); discrete rounded keel on 

venter of more robust variants. Flanks smooth or ornamented with regular falcoid ribs that fade on upper 

flank; ribs bullate on lower flanks of more thickly 

whorled evolute variants.

Smooth, tightly involute oxyconic mature morphology attained by gradual transition at diameters between 

15 and 30 mm.

Mature suture with characteristic pseudoadventitious 

longobarditinid pattern and proportions, five to seven 

auxiliary saddles (including S3). Pseudoadventitious 

pattern (L2>L1 in depth and breadth) not developed 

below whorl heights less than 15 mm; generally S2>S1 

by whorl height of 10 mm.

Discussion. The range in variation among young 

stages of. Intornites nevadanus may overlap that of/, mctaggarti, but at a given diameter the inner whorls of /.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 49

B

FIGURE 32. Suture lines (X 5) of Intomites nevadanus (Hyatt and 

Smith). A, plesiotype, USNM 248803. B, plesiotype, USNM 

248988, specimen not figured. C, holotype, MCZ 3902. D, 

plesiotype, USNM 248803.

nevadanus are on the average much more compressed 

and involute. From those of Longobardites parvus they 

differ in having regular ribbing and in most cases a discrete ventral keel.

Growth striae on smooth mature whorls of /. 

nevadanus are unevenly biconvex in contrast with those 

of L. parvus, which describe a single asymmetric convex 

curve. In fact, among longobarditinids from Nevada the 

nature of the growth striae serves to distinguish all 

mature shells of Intornites from those of the 

stratigraphically higher genus Longobardites. This is not 

a generic distinction generally, however, because the lectotype selected by Assereto (1966) for the type species of 

Longobardites, L. breguzzanus Mojsisovics, has 

biconvex growth striae in addition to other Intomiteslike characteristics such as distinct ventral shoulders 

and a sutural development essentially like that of /. 

nevadanus. In all respects it is closest to nonkeeled, 

relatively smooth variants of /. nevadanus, so that the 

only generally applicable distinction between Longobardites, as typified by its type-species lectotype, and Intornites is the absence of a distinct ventral keel on the inner 

whorls of the former, and this derives from the nature of 

a type specimen rather than a population sample. Thus, 

in view of the real differences between the various middle and upper Anisian species of longobarditinids, their 

separation into genera is unfortunately artificial.

Confusion regarding the characteristics of /. 

nevadanus has resulted from the original description by

Hyatt and Smith (1905), which was based partly on the 

small, poorly preserved type specimens, presumably all 

from the Shoshonensis Zone of the New Pass Range, 

about 100 km southeast of the Humboldt Range, and 

partly on younger specimens from the upper Anisian at 

Fossil Hill. The greatest diameter of the holotype is 20 

mm and that of the paratype figured by Hyatt and 

Smith is 10 mm. Both are somewhat eroded internal 

molds on which a ventral keel, if present, is obscure and 

the surface sculpture not preserved. Although they correspond with relatively compressed, involute, smooth 

variants among the inner whorls of populations included 

here in /. nevadanus, by themselves they are not adequate to separate /. nevadanus from other younger 

species of longobarditinids. Fortunately, one previously 

unfigured paratype (MCZ 3903a) shows the keeled 

venter and biconvex growth striae of the inner whorl that 

distinguishes populations from the Shoshonensis Zone 

from those that occur in higher zones of the Nevada Middle Triassic. The population sample upon which the present description is based is from the type locality of the 

Shoshonensis Zone (at USGS locality M635) in the 

Wildhorse mining district in the low hills north of the 

New Pass Range, whereas the type specimens were 

probably collected farther south in the New Pass Range. 

Equivalence of the stratigraphic level represented by 

this population sample with that represented by the type 

lot is evidenced by a shell fragment on one of the unfigured paratypes (MCZ 3903b) of a distinctive 

pelecypod referred to Enteropleura cf. E. bittneri Kittl, 

which is characteristic of the Shoshonensis Zone in the 

Wildhorse district and elsewhere.

Several collections from relatively high in the Hyatti 

Zone of the Humboldt Range include immature 

specimens of Intomites whose shell proportions and 

strength of ornamentation are intermediate between 

those of the average young stages of/, mctaggarti and /. 

nevadanus. These may be compared with I. intornatus, 

which characterizes the middle part of the Varium Zone 

in Canada (Tozer, 1971, p. 1017).

Figured specimens. Holotype, MCZ 3902 (originally 

figured by Hyatt and Smith, 1905, pi. 25, figs. 13-16); 

paratypes, MCZ 3904 (originally figured by Hyatt and 

Smith, 1905, pi. 25, figs. 17-18), and MCZ 3903a 

(previously unfigured); plesiotypes, USNM 248800 to 

248804.

Occurrence. USGS locality M635 (60+); Shoshonensis Zone in the lower part of the Fossil Hill 

Member of the Favret Formation, Wildhorse mining district, hills north of New Pass Range, Nev. Localities 

from which /. nevadanus is questionably represented 

relatively high in the Hyatti Zone in the northern Humboldt Range are USGS Mesozoic localities M1181 (25+) 

and M2829 (4).
50 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Genus LONGOBARDITES Mojsisovics, 1882 

Longobardites parvus (Smith)

Plate 21, figures 19-25; text-figure 33

Longobardites nevadanus Hyatt and Smith, 1905, p. 132, pis. 58 and 75

[in part]. Smith, 1914, p. 50, pis. 8, 12, and 30 [in part]. 

Dalmatites parvus Smith, 1914, p. 60, pi. 30, figs. 1-2 [holotype], 3-4,

5-7, 8-9?, 10-12?. 

Dalmatites minutus Smith, 1914, p. 59, pi. 29, figs. 15-16 [holotype],

17-19, 20-21. [not "Neodalmatites minutus (Smith)" of Popov,

1961, p. 64].

Neodalmatites parvus (Smith). Spath, 1951, p. 24. 

Longobardites hyatti Shevyrev, 1961, p. 74 [holotype = L. nevadanus

Hyatt and Smith, 1905, pi. 58, fig. 16 (and 17-18)]. 

Longobardites parvus (Smith). Silberling, 1962, p. 157.

Description. Mature shell compressed (W/D about 

0.20), oxyconic; flanks broadly convex, converge to narrow, acutely terminated venter; umbilicus closed. Maximum diameter exceeds 60 mm. Surface smooth except 

for asymmetric convex growth striae, the most orad 

point of which is above midline of flank.

Inner whorls at diameters of 10 to 15 mm involute 

(U/D less than 0.10) with acute, unkeeled, bluntly 

tapered venter; strength of ornamentation proportional 

to variable whorl thickness (W/H 0.4-0.7). Ornamentation varies from convex striae on compressed variants to 

widely spaced radial folds and depressions on lower flank 

of robust variants. Immature ornament, even on most 

coarsely sculptured variants, not persistent beyond 

diameter of 25 mm.

Mature suture with characterisitc pseudoadventitious 

Longobardites pattern (SKS2, LKL2) and proportions; six or more auxiliary saddles (including S3) at 

whorl height of 20 mm. Lobes weakly digitate in comparison with those of /. nevadanus; sides of saddles 

smooth. S2 may exceed height of Si at whorl height less 

than 10 mm, but L2 does not exceed Ll in depth at whorl 

height of less than 12 mm.

Discussion. Stratigraphically controlled population 

samples show that small ornamented specimens like 

those named Dalmatites parvus and D. minutus by 

Smith, and for which the genus Neodalmatites was established by Spath, are gradational into less robust, 

smooth shells like some of those misidentified as 

Longobardites nevadanus by Hyatt and Smith and by 

Smith. And further, they show that small shells like 

Smith's "Dalmatites" are the inner whorls of smooth oxycones having the distinctive pseudoadventitious suture 

pattern of Longobardites. Smith (1914, p. 59) described 

"Dalmatites" minutus as a dwarf form ornamented at 

maturity with coarse radial folds, but the holotype, 

which has a greater diameter of 20.5 mm and is the 

largest specimen illustrated by Smith, is entirely septate. Also, contrary to Smith's statement that 

"Dalmatites" parvus lacks the characteristic "adventitious lobes" of Longobardites, at a whorl height of

B

FIGURE 33. Suture lines (X 3) of Longobardites parvus (Smith). A, 

plesiotype, USNM 248807, suture line reversed. B, plesiotype, 

USNM 248989, specimen not figured. C, plesiotype, USNM 248990, 

specimen not figured, suture line reversed.

about 15 mm on the holotype L2 is deeper than Ll, and 

the suture therefore is pseudoadventitious.

Inner whorls of Longobardites parvus differ from those 

of /. nevadanus in never possessing a discrete ventral 

keel or regular falcoid ribbing, and the outer whorls differ in having convex rather than biconvex growth striae. 

From Longobardites cf. L. zsigmondyi, which occurs 

Stratigraphically higher in the Humboldt Range, L. 

parvus is distinguished mainly by its more robust and 

less oxyconic inner whorls.

The single fragmentary specimen from northeastern 

Siberia assigned to Neodalmatites minutus (Smith) by 

Popov (1961, p. 64) is said to have a distinct ventral keel, 

a feature not found in the typical specimens of this 

species, which herein is placed in synonomy with 

Longobardites parvus (Smith). Other Siberian species 

assigned to "Neodalmatites,"like "N."kharaulakhensis 

Popov (1961, p. 64) and "N." grumulus (Kiparisova) 

(Vozin and Tikhomirova, 1964, p. 75) are also keeled 

forms and differ still further from typical Neodalmatites 

in having three to five fewer auxiliary elements in their 

suture lines at equivalent shell diameters. The generic 

assignment of these Siberian species is thus regarded as 

incorrect. Unfortunately, Popov (1961) has established 

both a "Neodalmatites Zone" in Siberia and a "Subfamily Neodalmatitinae" based on this misconception of 

the genus Neodalmatites, which is no more than a synonym of Longobardites (Tozer 1971, p. 1017).

Specimens from Fossil Hill like those assigned here to 

L. parvus, and in particular like that illustrated by 

Hyatt and Smith (1905, pi. 58, figs. 16-18) as an example 

of L. nevadanus, were provided with the name L. hyatti 

by Shevyrev (1961, p. 74) because he regarded their 

suture pattern as being adventitious, unlike some other 

specimens of L. nevadanus described by Hyatt and 

Smith. These others, like the type specimens of the 

species, which are too small to have the pseudoadventitious suture pattern developed on them, were regarded 

by Shevyrev as having a normal suture pattern and were
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 51

therefore assigned to his new genus Longobarditoides. 

Proper understanding of the ontogenetic development 

and stratigraphic position of the species to which these 

Nevada specimens belong obviates the need for the 

specific name Longobardites hyatti, but, as suggested by 

Assereto (1966, p. 960), the generic name Longobarditoides might be usefully applied to shells having a 

tendency toward a distinctly tricarinate whorl shape.

Figured specimens. Plesiotypes, USNM 248805 to 

248808.

Occurrence. USGS localities M139 (1), Paraceratites 

clarkei beds, Rotelliformis Zone; M607 (7), Paraceratites 

cricki beds, Rotelliformis Zone; M137 (2), M141 (9), 

M607 +2 ft (0.6 m) (3), M608 (1), M611 (12), M613 (1), 

and M964 (7), Gymnotoceras blakei beds, Rotelliformis 

Zone; M142 (3), Parafrechites neuadanus beds, Meeki 

Zone; MHO (10+), M143 (8), and M960 (15+), 

Parafrechites meeki beds, Meeki Zone; 7M619 (1), 

Parafrechites dunni beds, Meeki Zone, vicinity of Fossil 

Hill, Humboldt Range, Nev.

Longobardites zsigmondyi (Bockh)

Ammonites (Sageceras) zsigmondyi Bockh, 1874, p. 177, pi. 4, fig. 14. 

Longobardites zsigmondyi (Bockh). Mojsisovics, 1882, p. 185, pi. 52, 

figs. 4a-4c.

Longobardites cf. L. zsigmondyi (Bockh)

Plate 21, figures 26-28; text-figure 34

Longobardites nevadanus Hyatt and Smith, 1905, p. 132, pis. 58 and 75 

[in part]. Smith, 1914, p. 50, pis. 8, 12, and 30 [in part].

Longobardites n. sp.? cf. "Longobardites indet. ex aff. L. zsigmondyi" 

of Mojsisovics. Silberling, 1962, p. 157.

Description. Oxyconic compressed (W/D about 0.20) 

at shell diameters exceeding 10 mm; umbilicus closed; 

venter acute, narrowly tapered, on outer whorl may 

become slightly fastigate with faint ventral-lateral 

edges. Maximum observed diameter of complete shell 40 

mm, of phragmocone 20 mm. Surface smooth except for 

convex growth striae.

Venter becomes acute at diameters of 4 mm or less; innermost whorls may have faint umbilical ornamentation 

like that of Longobardites parvus.

Suture with pseudoadventitious Longobardites pattern (SKS2, LKL2) and proportions at whorl heights 

exceeding 10 mm; six or more auxiliary saddles 

(including S3) at whorl-height 15 mm. Lobes weakly 

digitate, sides of saddles smooth.

Discussion. Of the two species of Longobardites 

described from Nevada, L. cf. L. zsigmondyi achieved 

the mature form and suture pattern of Longobardites at 

a smaller size. This apparent accelerated development 

and the smaller diameter of the full-grown shell are the 

only essential differences between L. cf. L. zsigmondyi 

and L. parvus. The rate of maturity with respect to shell

B

v

FIGURE 34. Suture lines (X 5) of Longobardites zsigmondyi (Bockh), 

all reversed. A, B, and C, all of plesiotype, USNM 248809, at different whorl heights.

diameter of the present species, which is nearly 

restricted to the lower part of the Occidentalis Zone, 

may be transitional with the somewhat slower rate 

characteristic of L. parvus, which occurs stratigraphically lower. Gradation, if it exists, between the 

two species is obscured by the scarcity of Longobardites 

in the higher parts of the Meeki Zone.

Three small specimens of Longobardites from separate 

localities in the upper part of the Occidentalis Zone of 

the Fossil Hill area, above the occurrence of L. cf. L. 

zsigmondyi, have relatively robust, bluntly terminated 

whorls, weak ribs on the lower flanks, and discrete 

ventral keels. On the larger two of these specimens the 

suture is pseudoadventitious (LKL2) at a whorl height 

of 10 mm. These may represent another distinct species, 

morphologically reminiscent of /. nevadanus but 

suturally as advanced as L. cf. L. zsigmondyi.

According to Mojsisovics, Longobardites zsigmondyi 

(Bockh) typically occurs in the Protrachyceras reitzi 

zone of the southern Alps and differs from L. breguzzanus, a possible senior synonym of I nevadanus, in having more auxiliary lobes and in being more compressed 

with a narrower aperture. Unfortunately, Bockh's only 

specimen is an internal mold that does not show the configuration of the growth lines. However, convex growth 

lines, like those of the present specimens from Nevada, 

are present on the specimen from the Protrachyceras 

archelaus zone illustrated by Mojsisovics (1882, pi. 52, 

figs. 3a-3b) as "Longobardites cf. zsigmondyi."

Figured specimens. Plesiotypes, USNM 248809 and 

248810.

Occurrence. 7USGS locality M968 (5), Parafrechites 

dunni beds, upper Meeki Zone; USGS localities M144 

(5), M144 -6.5 ft (2.0 m) (4), M620 (5), M621 (4), M622 

(11), M961 (15+), M962 (20+), M962A (7), 7M623 (1), 

lower part of Occidentalis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.
52 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Family APLOCOCERATIDAE Spath, 1951

Genus METADINARITES Spath, 1951

Metadinarites desertorus (Smith)

Dinarites desertorum Smith, 1914, p. 60, pi. 89, figs. 3-4 [holotype],

5-7; pi. 98, figs. 13-14, 15-16, 17-18. 

Metadinarites desertorus (Smith). Spath, 1951, p. 37. 

[l]Dinarites?pygmaeus Smith, 1914, p. 70, pi. 89, figs. 8-9 [holotype].

?Metadinarites desertorus (Smith) 

Plate 21, figures 29-30; text-figure 35

IMetadinarites desertorum (Smith). Silberling, 1962, p. 157.

None of the present specimens from stratigraphically 

controlled collections is identical with the types of M. 

desertorus (Smith). Nevertheless, two small ammonites 

from the Paraceratites cricki beds, Rotelliformis Zone, 

are questionably assigned to M. desertorus and may be 

transitional between this species and species of 

Aplococeras that occur stratigraphically higher.

The whorl shape and proportions of the two specimens 

under consideration here are like that of Aplococeras 

smithi from the overlying Gymnotoceras blakei beds. 

The configuration of the growth striae on their flanks, 

however, is less sinuous and more nearly rectiradiate 

compared with the strongly convex and rursiradiate 

striae characteristic of Aplococeras. The suture pattern 

shown by one of the specimens also differs from that of 

Aplococeras in having a slightly crenulate LI about 

equal in depth to VL.

Compared with the holotype of M. desertorus, neither 

of the present specimens is as strongly ornamented, but 

the specimen illustrated does have a few rectiradiate ribs 

parallel to the growth striae on the lower flanks. The 

suture agrees in plan with that of M. desertorus, but the 

lobes are less subdivided and the auxiliary series less distinct, differences that might be attributed to the whorl 

height represented by Smith's (1914, pi. 89, fig. 7) 

figured suture being nearly twice that represented by the 

suture illustrated here. The regular increase in whorl 

thickness with growth shown by the present specimens is 

an obvious difference from the typical examples of M. 

desertorus whose robust inner whorls thicken only 

gradually, producing an extremely shallow umbilicus.

Taken as a whole, the shell proportions, ornament, 

and suture of the present specimens are intermediate 

between Metadinarites and Aplococeras, which suggests 

that forms with the typical morphology of Metadinarites 

desertorus may occur stratigraphically lower in the 

Rotelliformis Zone.

Figured specimen. Plesiotype, USNM 248811.

Occurrence. USGS locality M967 (2); Paraceratites 

cricki beds, Rotelliformis Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

J

FIGURE 35. Suture line (X 8) of IMetadinarites desertorus (Smith). 

Plesiotype, USNM 248811.

Genus APLOCOCERAS Hyatt, 1900 

Aplococeras smithi n. sp.

Plate 21, figures 31-37; text-figure 36 

Pseudaplococeras nudus (Smith). Silberling, 1962, p. 157.

Description. Discoidal, compressed (W/D 0.25-0.30); 

evolute (U/D 0.40-0.45). Maximum diameter more than 

35 mm, probably not much exceeding 40 mm. Whorls 

thickly ovate in cross section, becoming more compressed with growth.

Ornamentation restricted to transverse striae, which 

are bundled together forming numerous closely spaced 

riblets on lower flanks. Course of striae strongly convex, 

curving back on lower flanks, rectiradiate on upper 

flank, and forming shallow sinus on venter.

Suture goniatitic to subceratitic. In some specimens 

LI and even L2 slightly crenulate. Depth of LI twice that 

of VL, nearly three times that of L2. Only one auxiliary 

saddle external to umbilical seam.

Discussion. The name Pseudaplococeras nudus 

(Smith) was incorrectly applied to this species by 

Silberling (1962, p. 157). The holotype of Lecanites 

nudus Smith has compressed whorls with nearly parallel 

flanks and weak umbilical bullae; it is in better 

morphologic agreement with weakly ornamented 

variants in populations of A. uogdesi (Hyatt and Smith). 

The paratype (designated the "cotype" by Smith, 1914, 

pi. 98) of Lecanites nudus is too featureless for positive 

identification; its suture as illustrated by Smith lacks 

the deep LI characteristic of Aplococeras and in plan is 

more like that of Metadinarites. Because neither L. 

nudus nor the other specific names proposed by Smith 

are suitable for the present species, a new name, A. 

smithi, is established here.

Some variants of A. vogdesi, particularly those in the 

lower part of its stratigraphic range, have thickly ovate 

whorls like those of A. smithi but differ in having bullae 

or well-defined ribs on the lower flanks. Other variants of 

A. uogdesi in the upper part of its stratigraphic range 

lack ribs or bullae but can be distinguished from A. 

smithi by their more compressed whorls and flattened 

flanks.

A. smithi is named in honor of James Perrin Smith.

Figured specimens. Holotype, USNM 248812; paratypes, USNM 248813 to 248815.

Occurrence. USGS localities M607 +2 ft (0.6m) (1), 

M608 (5), and M613 (1), Gymnotoceras blakei beds,
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 53

FIGURE 36. Suture line (X 7) of Aplococeras smithi n. sp. Holotype, 

USNM 248812.

Rotelliformis Zone; M142 (1), M612 (1), and M614 (1) 

Frechites nevadanus beds; Meeki Zone, vicinity of Fossil 

Hill, Humboldt Range, Nev.

Aplococeras vogdesi (Hyatt and Smith)

Plate 22, figures 1-17; text-figure 37

Lecanites vogdesi Hyatt and Smith, 1905, p. 139, pi. 60, figs. 12-15 

[holotype], 16-17, 18-19?, 20-22?; pi. 75, figs. 10, 11-13?. Smith, 

1914, p. 67, pi. 10, figs. 12-15, 16-17, 18-19?, 20-22?; pi. 12, figs. 

10, 11-13?; pi. 30, figs. 17,18-19, 20, 21-22, 23-24, 28?; pi. 88, figs. 

24-25.

Pseudaplococeras vogdesi (Hyatt and Smith). Spath, 1951, p. 37. 

SUberling, 1962, p. 157.

Lecanites crassus Smith, 1914, p. 66, pi. 89, figs. 1-2 [holotype].

Lecanites nudus Smith, 1914, p. 66, pi. 98, figs. 8-9 [holotype], 10-12?.

This species is quite variable in ornamentation and 

whorl shape. Populations in the lower part of its 

stratigraphic range tend to have more robust whorls and 

ornamentation dominated by approximated convex umbilical ribs in comparison with stratigraphically higher 

populations in which the whorls are commonly narrower 

and more flat sided and in which the ornamentation consists mainly of irregular umbilical bullae of variable 

strength. Recognition of more than one species, however, 

seems impractical because of the wide morphologic 

overlap between populations from different stratigraphic 

levels.

The average morphology of A. vogdesi differs from 

that of A. smithi in the more pronounced umbilical ribs 

or bullae of the former. Weakly ornamented variants of 

A. vogdesi resemble A. smithi more closely but are 

generally more compressed with flattened flanks. Such 

variants occur in the stratigraphically highest populations of A. vogdesi and may be forerunners of A. parvus 

from which they differ in having thicker and more involute whorls.

The identity of the genus Pseudaplococeras proposed 

by Spath (1951, p. 37) for Lecanites vogdesi of Hyatt and 

Smith (1905) with the Alpine genus Aplococeras was 

pointed out by Asseretto (1969) who considers the 

species A. vogdesi, as redefined herein, as a synonym of, 

and the same age as, A. avisianus, the holotype of 

Aplococeras.

Figured specimens. Holotype, USNM 74385 

(originally figured by Hyatt and Smith, 1905, pi. 60, figs. 

12-15), plesiotypes, USNM 248816 to 248823.

B

FIGURE 37. Suture lines (X 7) of Aplococeras vogdesi (Hyatt and 

Smith), reversed. A, plesiotype, USNM 248820. B, plesiotype, 

USNM 248821.

Occurrence USGS localities M140 (5), M143 (1), 

M958 (16), and M960 (45), Parafrechites meeki beds; 

M167 (3), M618 (2), M619 (12), M959 (9), and M968 

(20+), Parafrechites dunni beds; Meeki Zone, vicinity of 

Fossil Hill, Humboldt Range, Nev.

Aplococeras parvus (Smith)

Plate 22, figures 18-23; text-figure 38

Lecanites parvus Smith, 1914, p. 66, pi. 30, figs. 25-26 [holotype], 27?;

pi. 88, figs. 26-28. 

Pseudaplococeras parvus (Smith). Silberling, 1962, p. 157.

Representatives of this species form a well-defined entity that is morphologically distinct and stratigraphically separated from A. vogdesi. The whorls are smooth 

except for growth striae, and they are thinner (W/D 

about 0.20) and more loosely coiled (U/D 0.45-0.55) than 

those of A. vogdesi. No specimens transitional between 

the two species were found, and yet these species are 

clearly congeneric; both have a goniatitic suture with LI 

exaggerated in size and convex rectiradiate growth 

striae.

The cross section of the whorls was described by Smith 

(1914) as "miter-shaped," i.e., arched with convex sides 

and an acute venter. This whorl shape characterizes only 

the outermost volution; the venter of the inner whorls is 

broadly rounded, grading imperceptibly into subparallel 

flattened flanks.

Figured specimens. Plesiotypes, USNM 248824 to 

248826.

FIGURE 38. Suture line (X 7) of Aplococeras parvus (Smith). 

Plesiotype, USNM 248826.
54 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Occurrence. USGS localities M144 minus 6 ft (1.8 

m) (6), M144 (1), M620 (1), M622 (1), M623 (6), M961 

(10), M962 (12), and M962A (2), Nevadites beds, Occidentalis Zone, vicinity of Fossil Hill, Humboldt Range,

Nev.

Superfamily NATHORSTITACEAE (Spath, 1951)

?Family PROTEUSITIDAE Spath, 1951

Genus TROPIG AS TRITE S Smith, 1914

Tropigastrites lahontanus Smith

Plate 26, figures 5-17

Tropigastrites lahontanus Smith, 1914, p. 28, pi. 19, figs. 14-15a 

[holotype] [not figs. 16-17, 18-19a, 20-21a?, 24-26? = Tozerites 

gemmellaroi (Arthaber)]. Silberling, 1962, p. 157.

Tropigastrites halli (Mojsisovics) [in part]. Smith, 1914, p. 27, pi. 18, 

figs. 11-12, 13-14a?; pi. 88, figs. 14-15? [not specimens on pis. 6, 

12, and 88 included in Tozerites gemmellaroi (Arthaber); not pi. 

14, figs. 7, 7a = Pseudodanubites? halli (Mojsisovics)].

Tropigastrites rothpletzi Smith, 1914, p. 31, pi. 19, figs. 1-3 [holotype], 

4-5, 6-7, 8-9?, 10-11?, 12-13a?, 22-23?; pi. 86, figs. 24-26.

Tropigastrites neumayri (Mojsisovics) [in part]. Smith, 1914, p. 29, pi. 

18, figs. 15-16a, 17-17a, 18-19?, 20-21a?, 22-23?.

[?] Gymnites (Anagymnites) rosenbergi Smith, 1914, p. 55, pi. 26, figs. 

2-3a [holotype], 4-5?, 6?.

The discrimination of species in the genus Tropigastrites and the choice of specific names among the 

partly synonomous names proposed by Smith (1914) is 

not entirely satisfactory. Populations of Tropigastrites 

are evidently quite variable, but the range of variation 

can seldom be demonstrated in a single collection owing 

to the scarcity of specimens. Further, isolated, strati - 

graphically random specimens, like those described by 

Smith, may agree with variants of more than one of the 

species based on the collective characters of specimens 

from different collections representing restricted parts of 

the section.

Tropigastrites lahontanus includes discoidal, compressed (W/D 0.23-0.30, mostly about 0.26), evolute 

(U/D about 0.5, not less than 0.45) shells with thick 

whorls, the outer two or three of which are arch shaped in 

cross section with a broadly fastigate venter. The largest 

specimens are about 60 mm in diameter. Prosiradiate ornamentation varies in strength from striae to regularly 

spaced umbilical ribs or bullae. The suture is ceratitic to 

subammonitic with SI completely crenulate in some 

specimens; LI is about equal to or greater in depth than 

VL.

Tropigastrites lahontanus probably grades into T. 

louderbacki, which is the next higher species in the section and from which it is distinguished mainly by having 

thinner and more closely coiled whorls.

Figured specimens. USNM 248846 to 248851, 

248983.

Occurrence. USGS localities M137 (1), M141 (1), 

M607 +2 ft (0.6 m) (4), M608 (5), M609 (6), M611 (1), 

M964 (1); Gymnotoceras blakei beds, Rotelliformis 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Tropigastrites louderbacki (Hyatt and Smith) 

Plate 26, figures 18-36; text-figure 39

Sibyllites louderbacki Hyatt and Smith, 1905, p. 58, pi. 74, figs. 10-12

[holotype]. 

Tropigastrites louderbacki (Hyatt and Smith). Smith, 1914, p. 29, pi.

11, figs. 10-12; pi. 18, figs. 3-6, 9-10a?; pi. 88, figs. 4-5, 6-9,

10-13?. Silberling, 1962, p. 157. 

Tropigastrites powelli Smith, 1914, p. 31, pi. 18, figs. 1-2, 7-8a; pi. 97,

figs. 1-4 [holotype], 5-6, 7-8?, 9-10, 11-12. 

Tropigastrites trojanus Smith, 1914, p. 32, pi. 17, figs. 1-4 [holotype], 5

and 10?, 6-9, 11-13, 14, 15-19, 20-22?, 23?, 24-27?, 28-30?.

Silberling, 1962, p. 157.

Japonites louderbacki (Hyatt and Smith). Diener 1915a, p. 158. 

[?] Tropigastrites obliterans Smith, 1914, p. 30, pi. 87, figs. 27-29

[holotype], 30-32.

This species, which is fairly common in the Frechites 

nevadanus beds, is characterized by thick fastigate 

whorls whose width may be half again as much as their 

height. The shell is thus thicker (W/D 0.35-0.50, mostly 

about 0.40) than in T. lahontanus and is also on the 

average more involute (U/D 0.40-0.50, mostly about 

0.45). Eccentric and more open coiling accompanied by 

an increase in the relative height of the final whorl 

begins at shell diameters ranging from 20 to 40 mm; 

much of the morphologic variation within a single population can be attributed to some specimens having 

matured at smaller diameters than others. Ornamentation consists of prosiradiate umbilical ribs or bullae that 

fade on the final eccentrumbilicate whorl.

The simple subammonitic suture line as illustrated by 

Smith (1914) for some of the specimens included in this 

revised species is correct. SI is prominent with the 

crenulation on its flanks decreasing in strength towards 

its summit. The broad VL, which is divided by a prominent ES, is about equal in depth to LI.

The holotype of T. trojanus Smith, the type species of 

Tropigastrites by original designation (Smith, 1914, p. 

25), clearly falls within the scope of this expanded 

species for which T. louderbacki is the prior name. 

However, some specimens assigned by Smith (1914) to 

T. trojanus, like that illustrated by his plate 17, figures 5 

and 10, reproduced in Arkell and others (1957, fig. 202, 

5a), differ in having narrower and more loosely coiled 

whorls and may be transitional to T. lahontanus, as 

revised.

Figured specimens. Holotype, USNM 74400 

(originally figured by Hyatt and Smith, 1905, pi. 74, figs. 

10-12); plesiotypes, USNM 248852 to 248859.

J

FIGURE 39. Suture line (X 5) of Tropigastrites louderbacki (Hyatt 

and Smith). Plesiotype, USNM 248852.
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 55

Occurrence. USGS localities M137 +4 ft (1.2 m) (1), 

M142 (3), M166 (22), M612 (1), M614 (25+), M615 (2), 

and M957 (7); Frechites nevadanus beds, Meeki Zone, 

vicinity of Fossil Hill, Humboldt Range, Nev.

Genus TOZERITES, n. gen.

Type species. Tozerites humboldtensis (Smith).

Definition. Discoidal, compressed, evolute shells 

having broadly rounded to weakly fastigate outer 

margin. Ornamented by projected bullate umbilical ribs 

fading on outer whorl. Suture ceratitic; VL markedly 

deeper than LI that is weakly serrate; L2 weakly differentiated.

Discussion. This genus evidently evolved from 

Tropigastrites from which it differs primarily in the 

proportions and simplicity of its suture. The 

stratigraphically higher species also differ from 

Tropigastrites in their nonfastigate whorl shape and 

more projected ribbing. Tozerites gemmellaroi is transitional in these characters. The Alpine specimens 

named Celtites neumayri by Mojsisovics (1893, p. 348, 

pi. 200, figs. 5a-5b, 6) outwardly resemble members of 

this genus. Smith (1914) applied this specific name to 

specimens from Nevada, which he placed in Tropigastrites, but the suture pattern of Mojsisovics' specimens is unknown. Spath (1951, p. 99) mentioned a large 

specimen from Bosnia, identified as "Tropigastrites 

neumayri, var. crassiplicata (Mojsisovics)," as having 

VL about twice as deep as LI, which suggests its inclusion in Tozerites.

This genus is named in honor of E. T. Tozer.

Tozerites gemmellaroi (Arthaber)

Plate 27, figures 1-13; text-figure 40

Celtites halli (Mojsisovics). Hyatt and Smith, 1905, p. 125, pi. 25, figs.

4-4a [herein selected as lectotype of Celtites gemmellaroi

Arthaber], 5? [specimen missing], 5a-5b?; pi. 75, figs. 1-la?,

2-3?, 4-5?. 

Celtites gemmellaroi Arthaber, 1911, p. 266 [new name for "Celtites

halli H. & Sm."] 

Tropigastrites halli (Mojsisovics) [in part]. Smith, 1914, p. 27, pi. 6,

figs. 4-4a, 5?, 5a-5b?; pi. 12, figs. 1-la?, 2-3?, 4-5?; pi. 88, figs.

16-18, 19-20, 21-23 [not specimens on pis. 18 and 88 included in

Tropigastrites lahontanus Smith; not pi. 14, figs. 7, 7a,=

Pseudodanubites? halli (Mojsisovics)]. 

Tropigastrites lahontanus Smith, 1914, p. 28, pi. 19, figs. 16-17,

18-19a, 20-21a?, 24-26?.

Tropigastrites rothpletzi Smith. Silberling, 1962, p. 157. 

Tropigastrites neumayri (Mojsisovics) [in part]. Smith, 1914, p. 26, pi.

88, figs. 1-3.

This species, occurring in the Parafrechites meeki and 

P. dunni beds of the Meeki Zone, is the stratigraphically 

lowest species of Tozerites and is in some respects transitional with Tropigastrites, which ranges up into the 

lowest beds of the Meeki Zone. Sutures of specimens 

from the P. dunni beds have the unusually deep VL 

characteristic of Tozerites, but sutures cannot be seen on

outwardly similar specimens from the P. meeki beds, 

and their generic assignment is thus uncertain; in whorl 

shape and ornamentation they are similar to 

Tropigastrites lahontanus.

Specimens positively assigned to T. gemmellaroi are 

compressed (W/D 0.20-0.30) and evolute (U/D 

0.50-0.60). The largest of these specimens barely exceeds 

30 mm in diameter and shows a loss of ornament suggesting maturity. The whorl shape is broadly rounded in 

the juvenile shell, but the shape of the outer whorl is 

proportionally narrower and fastigate on most 

specimens. About 19-20 projected bullate ribs of fairly 

even spacing and strength characterize inner whorls but 

fade on outer whorls.

The stratigraphically higher Tozerites humboldtensis 

and T. polygyratus lack fastigate whorls at any growth 

stage and have umbilical ribs that are much more 

strongly projected.

The lectotype of T. gemmellaroi was described and illustrated by Hyatt and Smith (1905) and was misidentified by them as belonging to Danubites halli 

Mojsisovics, for which they used the new combination 

Celtites halli (Mojsisovics). Because this combination 

was a secondary homonym of the Permian species 

Celtites (Paraceltites) halli Gemmellaro, 1887, Arthaber 

(1911) proposed Celtites gemmellaroi as a replacement 

for "Celtites Halli H. & Sm." Although Arthaber was 

probably unaware that the specimens included by Hyatt 

and Smith in Celtites halli (Mojsisovics) were misidentified, his name, Celtites gemmellaroi, is nonetheless the 

first and only available name for ammonites of this kind.

Figured specimens. Lectotype, USNM 74305 

(originally figured by Hyatt and Smith, 1905, pi. 25, figs. 

4-4a); plesiotypes, USNM 248860 to 248864.

Occurrence. Questionably represented from USGS 

localities MHO (1), M143 (3), M167 (1), M958 (6), and 

M963 (4), Parafrechites meeki beds; positively identified 

from M618 (6), M619 (9), M959 (6+), and M968 (7), 

Parafrechites dunni beds; Meeki Zone, vicinity of Fossil 

Hill, Humboldt Range, Nev.

I N-' 

B

FIGURE 40. Suture lines of Tozerites gemmellaroi (Arthaber). A, 

plesiotype, USNM 248864 (X 8). B, lectotype, USNM 74305 (X 5), 

dashed where approximate.
56 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Tozerites humboldtensis (Smith) 

Plate 27, figures 14-23; text-figure 41

Columbites humboldtensis Smith, 1914, p. 36, pi. 20, figs. 26-28 

[holotype]; pi. 87, figs. 1-3, 4-5, 6-9, 10-11, 12-14?.

Columbitesplicatulus Smith, 1914, p. 37, pi. 20, figs. 15-16 [holotype], 

17-18, 19-22, 23?, 24-25?; pi. 87, figs. 15-16, 17-18, 19-23.

Celtites? humboldtensis (Smith). Silberling, 1962, p. 157.

This species is in some respects transitional between 

Tozerites gemmellaroi and T. polygyratus. Though it is 

stratigraphically intermediate between these two 

species, morphologic intergradation with them has not 

been observed.

The proportions of the evolute (U/D 0.45-0.55), thickwhorled (W/D 0.30-0.35) shell are like those of the inner 

whorls of Tozerites gemmellaroi, from which T. humboldtensis differs in lacking a fastigate final whorl, in 

having a more subquadrate whorl shape with better 

defined flanks, and in having the strongly prosiradiate 

umbilical ribs and bullae irregularly spaced and of uneven strength. The whorl shape and prosiradiate ribbing 

in turn resemble that of T. polygyratus, from which T. 

humboldtensis differs in having more tightly coiled and 

thicker whorls and irregular spacing and strength of the 

ribs.

"Columbites"plicatulus was described by Smith as a 

separate species with more robust whorls and coarser 

sculpture than "C. "humboldtensis. Complete gradation 

between these two forms is suggested by specimens from 

a single bed; consequently the name T. humboldtensis 

(Smith) is revised to include both forms named by 

Smith.

Figured specimens. Plesiotypes, USNM 248865 to 

248869.

Occurrence. USGS localities M144 (6), M144 minus 

6 ft (1.8 m) (1), M620 (4), M621 (1), and 962 (4); 

Nevadites hyatti and N. humboldtensis beds; (Decidentalis Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

FIGURE 41. Suture line (X 5) of Tozerites humboldtensis (Smith). 

Plesiotype, USNM 248991, specimen not figured.

Tozerites polygyratus (Smith) 

Plate 27, figures 24-29

Celtites polygyratus Smith, 1914, p. 35, pi. 20, figs. 1-2 [holotype], 3, 4,

5-6?, 7-8a?.

Celtites gabbi Smith. Silberling, 1962, p. 157. 

[?] Celtites gabbi Smith, 1914, p. 34, pi. 20, figs. 9-10 [designated here

as lectotype], 11-12, 13-14?.

This species is distinguished by its compressed (W/D

0.25-0.30), extremely evolute (U/D 0.55-0.60) shell and 

its subquadrate whorl shape. The venter is broadly 

rounded and grades into flattened, subparallel flanks, 

which on the inner whorls are ornamented by regularly 

spaced strongly prosiradiate ribs.

Unfortunately, the suture is unknown except for the 

goniatitic pattern drawn by Smith (1914, pi. 20, fig. 8a) 

from a specimen presumably of this species only several 

millimeters in diameter.

Specific separation of "Celtites gabbi" Smith from 

typical Tozerites polygyratus, from which it differs in 

having higher, narrower whorls and more delicate ribbing, seems impractical, though intergradation of the 

two forms at the same stratigraphic level cannot be 

demonstrated by the present collections. "Celtites gabbi" was proposed by Smith as a new name for 

"Goniatites laevidorsatus (Hauer)" of Gabb (1864) [not 

"Clydonites laevidorsatus (Hauer)" of Meek (1877) = 

Danubites halli Mojsisovics, 1896], but it is unclear 

whether Smith intended Gabb's specimen or one of his 

own to serve as holotype. Seven specimens representing 

Pseudodanubitest,Aplococeras, Tropigastrites, and possibly Tozerites, were found in the collections of the 

Academy of Natural Sciences of Philadelphia (lot ANSP 

30782) associated with Gabb's original label, but none of 

these agrees closely with Gabb's figure of "Goniatites 

laevidorsatus" Although "C. gabbi" is considered a 

probable synonym of Tozerites polygyratus, to avoid 

possible confusion the largest of the specimens figured 

by Smith (1914, pi. 20, figs. 9-10) is selected here as lectotype of Celtites gabbi Smith.

Figured specimens. Plesiotypes, USNM 248870 to 

248872.

Occurrence USGS localities M622 (10+), M624 (3), 

M626 (1), and M962A (1), upper part of Nevadites beds; 

Occidentalis Zone, vicinity of Fossil Hill, Humboldt 

Range, Nev.

Family THANAMITIDAE Tozer, 1971

Genus THANAMITES Diener, 1908

Thanamites? contractus (Smith)

Plate 6, figures 12-14

Nannites contractus Smith, 1914, p. 45, pi. 21, figs. 13-15 [holotype],

16-17a. 

Nannites? contractus Smith. Silberling, 1962, p. 157.

A single small specimen from the Nevadites beds 

agrees closely in whorl shape, development, and size 

with this species. The shell of this specimen is globose 

and moderately involute to a diameter of 7 or 8 mm, 

after which the coiling becomes eccentric and the whorl 

shape narrow and subtrigonal. This modification appears to be that of the final whorl, though the greatest 

diameter is only 12 mm. The suture illustrated by Smith 

(1914, pi. 21, fig. 17a) from a minute specimen assigned
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 57

to this species is goniatitic and normal, VL having a 

depth equal to that of LI. As such it is like that of 

Thanamites from the Ladinian of British Columbia (E. 

T. Tozer, written commun., 1974). The specimens from 

Nevada also resemble this genus in general form and excent rumbilic ate coiling, and hence they are questionably 

assigned to Thanamites rather than retained in the 

typically Karnian genus Nannites.

Figured specimen. Plesiotype, USNM 248647.

Occurrence. USGS locality M144 (1), Nevadites 

humboldtensis beds, Occidentalis Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Superfamily ARCESTACEAE (Mojsisovics, 1875)

Family ARCESTTDAE

Genus PROARCESTES Mojsisovics, 1893

Proarcestes balfouri (Oppel)

Ammonites balfouri Oppel, 1863, p. 285, pi. 80, fig. 5.

Proarcestes balfouri (Oppel). Diener, 1895, p. 83, pi. 27, figs. 6, 7a-7c.

Proarcestes cf. P. balfouri (Oppel)

Plate 27, figures 30-35; text-figure 42

Arcestes (Proarcestes) hartzelli Smith, 1914, p. 43, pi. 93, figs. 17-18

[holotype]. 

Arcestes (Proarcestes) quadrilabiatus Hauer. Smith, 1914, p. 44, pi. 93,

figs. 15-16. 

Arcestes (Proarcestes) cf. A. (P.) bramantei Mojsisovics. Silberling,

1962, p. 157.

Proarcestes from the Rotelliformis Zone and the lower 

part of the Meeki Zone are readily distinguished from 

those occurring higher in the Meeki Zone and in the Occidentalis Zone by their more globose shell and semicircular ventral outline. Assignment of these specimens to a 

distinct species is thus justified, but the choice of a 

specific name is complicated by the profusion of 

available names, many of which are very narrow in concept. The whorl shape, shell proportions, and suture line 

of the present specimens are closely similar to those of 

Arcestes (Proarcestes) balfouri (Oppel) from the 

Himalayan Middle Triassic as well as to those of several 

subsequently described species of about the same age 

such as A. (P.) bramantei Mojsisovics. The validity of 

these various species, which are distinguished by minor 

differences such as slight variations in shell proportions 

or in the number and configuration of constrictions, cannot be evaluated on the basis of their published descriptions. Moreover, the available material from the Humboldt Range, including the specimens described by 

Smith, is inadequate for detailed comparison. Consequently, the arcestids from the lower part of the upper 

Anisian are tentatively assigned to P. balfouri, which 

was the first to be named among several closely related 

and probably partly synonymous species.

Compared with P. gabbi, which occurs stratigraphiFIGURE 42. Suture line (X 2) of Proarcestes cf. P. balfouri (Oppel), 

reversed. Plesiotype, USNM 248992, specimen not figured.

cally higher, P. cf. P. balfouri has a wider shell (W/D 

0.80-1.0) and a semicircular rather than parabolic 

ventral outline. The suture line of both species is similar. 

ES is elongate, more than half the height of SI, and has 

parallel subdivided flanks; SI is asymmetric owing to a 

pronounced first-order subdivision on its ventral side.

Figured specimens. Plesiotypes, USNM 248873 and 

248874.

Occurrence. USGS locality M965 (4), Paraceratites 

burckhardti beds; M967 (1), Paraceratites cricki beds; 

M137 (4), M608 (10), and M609 (1), Gymnotoceras 

blakei beds; Rotelliformis Zone; M612 (1) and M615 (2), 

Parafrechites neuadanus beds; M960 (1?), Parafrechites 

meeki beds; M167 (2?), Parafrechites dunni beds; Meeki 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Proarcestes gabbi (Meek)

Plate 27, figures 36-45; 

Plate 28, figures 1-2; text-figure 43

Arcestes gabbi Meek, 1877, p. 121, pi. 10, figs. 6-6a [holotype], 6b. 

Arcestes ausseanus Hauer. Gabb, 1864, p. 25, pi. 3, figs. 16-17. 

Arcestes (Proarcestes) gabbi Meek. Smith, 1914, p. 43, pi. 14, figs.

6-6a, 6b; pi. 21, figs. 1-2; pi. 48, figs. 1-3; pi. 93, figs. 19-19a, 20.

Silberling, 1962, p. 157.

This species is characteristic of the Occidentalis Zone. 

Compared with Proarcestes cf. P. balfouri from lower in 

the section, it has a relatively compressed shell (W/D 

0.70-0.85 at about 20 mm in diameter, 0.55-0.75 at 

larger diameters) and a parabolic rather than semicircular ventral outline. The maximum size exceeds 75 mm 

in diameter.

B

FIGURE 43. Suture lines (X 2) of Proarcestes gabbi (Meek). A, 

plesiotype, USNM 248878. B, plesiotype, USNM 248877.
58 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

The range in shell proportions within a single population is illustrated by figure 44. Unfortunately, the collections of P. cf. P. balfouri are insufficient for graphical 

treatment, but several specimens from different 

localities in the Gymnotoceras blakei beds are plotted for 

comparison.

Proarcestes gabbi may be synonymous with P. extralabiatus Mojsisovics from the Alpine Middle Triassic, 

but the two species are not comparable without knowing 

the morphologic limits of populations including typical 

specimens of P. extralabiatus Mojsisovics.

Figured specimens. Holotype, USNM 12523 

(originally illustrated by Meek, 1877, pi. 10, figs. 6-6a); 

plesiotypes, USNM 248875 to 248878.

Occurrence. USGS locality M968, Gymnotoceras 

dunni beds, Meeki Zone; M144 -6 ft (1.8 m) (6), M144 

(6), M620 (1), M961 (1), M962 (100+), MUG (15+), 

M623 (12+), and M624 (2), Occidentalis Zone. 7USGS 

locality M627 (1), lowermost Subasperum Zone. Vicinity 

of Fossil Hill, Humboldt Range, Nev.

Genus PROTRAGHYGERAS Mojsisovics, 1893

Several species of Protrachyceras have been described 

from the Subasperum Zone immediately overlying the 

Occidentalis Zone in the Humboldt Range. The boundary between these two zones is more or less coincident 

with the gradational contact between the impure 

calcareous rocks of the Fossil Hill Member of the Prida 

Formation, which locally are highly fossiliferous, and the 

dark, laminated limestone and dolomite of the upper 

member of the Prida Formation in which fossils are 

generally scarce. Consequently, collections from the 

Subasperum Zone are meager, and stratigraphically successive population samples that would demonstrate the 

taxonomic and stratigraphic relations of the previously 

described species of Protrachyceras are not available.

The few isolated specimens of this genus collected during the present study indicate that the type specimens of 

the following species were derived from the lowermost 

part of the Subasperum Zone within ten meters or so 

stratigraphically above the occurrence of Nevadites:

Protrachyceras subasperum (Meek, 1877) [= Trachyceras judicaricum 

var. subasperum Meek, 1877, pi. 11, figs. 2-2b] P. meeki (Mojsisovics, 1882, p. 108 [= "Trachyceras judicaricum Mojsisovics" 

of Meek, 1877, pi. 11, figs. 1-la].

P. americanum (Mojsisovics, 1886, p. 149) [= Ceratites whitneyi 

Gabb, 1864, pi. 4, figs. 12-12a].

P. lahontanum Smith, 1914.

P. dunni Smith, 1914.

The type specimens of the first three species listed are 

reillustrated here by figures 12-16, plate 24 and figures 

1-5, plate 25. Protrachyceras springeri, described from 

an unknown locality and stratigraphic position in the 

northern Humboldt Range by Smith (1914, p. 136), differs from the species listed above in having a more discrete, narrow ventral furrow and is more like specimens 

collected at a considerably higher stratigraphic level in

60

50

40

30

20

XX 

X

XX j

X X 

X X 

XX

XX

10

*xxx

Xt

X

XXX 

-x x L_

20 30 

WIDTH, IN MILLIMETERS

40

FIGURE 44. Scatter diagram of shell width plotted against 

corresponding diameter for 37 specimens of Proarcestes gabbi from 

USGS locality M962 in the Nevadites hyatti beds (crosses). 

Equivalent points (dots) for several specimens of P. cf. P. balfouri 

from different localities in the Gymnotoceras blakei beds are plotted for comparison.

the Prida Formation. Ammonites homfrayi Gabb, assigned to Protrachyceras and provisionally listed as being represented in the Fossil Hill fauna by Smith (1914, 

p. 11) is a Sirenites of probable Late Triassic age.

Protrachyceras subasperum, P. americanum, and P. 

lahontanum form a closely related group characterized 

by a relatively broad and indistinct ventral furrow and a 

similar pattern of tuberculation. Persistent umbilical, 

ventral-lateral, and ventral spiral rows of tubercles are 

common to all three species; two additional rows of 

spines, an upper lateral and a lower lateral row making a 

total of five rows, may have completed the basic pattern 

on the inner whorls. With growth the lateral spines 

became obsolescent or one lateral row became obsolete 

while the other became emphasized as widely spaced 

tubercles of exaggerated size. This kind of ontogenetic 

development, which results in mature whorls like those 

of the type specimens of these three species, is shown by 

small collections associated with Daonella rieberi and 

Frechites johnstoni. Small mutually occurring 

specimens in such collections show a fairly wide range in 

morphology, as might be expected, and range from 

relatively compressed, involute, finely sculptured individuals to those with more robust, evolute, and
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 59

coarsely sculptured whorls. These variations that can be 

demonstrated among small individuals suggest that 

some of the obvious differences in shell proportions and 

ornamentation among large shells, like the type 

specimens, may be due to variation in ontogenetic 

development within a single species.

The holotype of P. meeki represents another closely 

related form with a similarly developed ventral furrow 

but with duplication of the lateral rows of spines, 

producing a total of seven rows in which the spines are of 

more or less equal strength. This pattern may persist to 

large shell diameters as shown by the plesiotype figured 

by Hyatt and Smith (1905, pi. 59, figs. 1-2) on which two 

of the lateral spine rows first commence to become 

enlarged at the expense of the other two at a shell 

diameter of about 80 mm.

Contrary to Smith's (1914, p. 134) description, P. 

dunni differs from the other species of Protrachyceras 

considered here in lacking a distinct ventral furrow. The 

ventral spines alternate across the midline of the venter 

and are connected in crisscross fashion by continuations 

of the ribs. It should be noted that the holotype and only 

described specimen of this species is partly pathologic; a 

healed injury of some kind has displaced the venter to 

one side and altered the spacing of the lateral tubercles 

for about one-fifth of the outer whorl. Assuming that this 

abnormality is not related to its more general 

morphologic distinctions, the simple tuberculation and 

poorly developed ventral furrow suggest that this species 

is transitional between Nevadites and Protrachyceras. 

Possibly conspecific with P. dunni are the holotype of 

Nevadites barberi, which has more regular and stronger 

tuberculation than N. gabbi and a venter like that of P. 

dunni, and one of the specimens originally illustrated by 

Hyatt and Smith (1905, pi. 74, figs. 1-3) as Trachyceras 

(Anolcites) meeki.

Superfamily CLYDONITACEAE (Mojsisovics, 1879)

Family ARPADITIDAE Hyatt, 1900 

Subfamily SIRENITINAE, Tozer, 1971 

Genus SIRENITES Mojsisovics, 1893

Sirenites homfrayi (Oabb) 

Plate 25, figures 6-7; text-figure 45

Ammonites homfrayi Gabb, 1864, p. 26, pi. 4, figs. 18-19. 

Trachyceras (Protrachyceras) homfrayi (Gabb). Smith, 1914, p. 134,

pi. 16, figs. 11-13. 

Trachyceras (Paratrachyceras) homfrayi (Gabb). Kutassy, 1933, p.

682.

This species, which is not part of the Middle Triassic 

fauna of the Humboldt Range, is redescribed here to prevent further confusion concerning its identity and age.

Description of holotype. Partly crushed, completely 

septate internal mold. Discoidal, compressed, and 

moderately involute in shape. Maximum measureable 

diameter about 47 mm, corresponding maximum width 

about 13 mm, width of umbilicus 8.5 mm.

FIGURE 45. Suture line (X 3) of Sirenites homfrayi (Gabb). Holotype, 

ANSP 30793.

Ornamented by closely spaced falcoid ribs bearing 

small spines in spiral rows of varying strength. Ribs 

originate at umbilical shoulder or by intercalation on 

lower flanks. Number of spiral spine rows obscure, at 

least eight including umbilical and ventral-lateral rows. 

Ribs split at ventral-lateral tubercles, project strongly 

forward to ridges bordering ventral furrow, and form 

closely spaced elongate ventral tubercles slanting 

forward and towards the ventral midline, giving the 

ventral ridges a ropelike appearance. Ventral furrow narrow and distinct.

Suture ammonitic. SI and S2 narrow with converging 

sides, deeply scalloped. LI with incipient secondary subdivision, much larger than L2. One discrete auxiliary 

saddle at umbilical shoulder.

Discussion. Confusion concerning generic assignment and age of this species has resulted from the inadequacies of Gabb's original description and illustrations. 

According to Gabb (1864, p. 26-27), Ammonites 

homfrayi was collected with "Ammonites" billingsianus 

Gabb at an unspecified locality in the East Range, the 

next range east of the Humboldt Range. Under the 

impression that the latter species was a Monophyllites 

like that found in the upper Anisian at Fossil Hill, Smith 

(1914) assigned "A." homfrayi to Protrachyceras, though 

he stated that no specimens from his "Daonella dubia 

zone" could positively be identified with it and that it 

may have come from higher in the Middle Triassic than 

the beds equivalent to the Ceratites trinodosus zone.

Kutassy (1933, p. 682) placed "A." homfrayi in 

Paratrachyceras and regarded it as Anisian in age. This 

generic assignment was also adopted by Spath (1951, p. 

42-43), who regarded the age of the species as Ladinian.

Evidently none of these authors had an opportunity to 

examine the type specimen, which was located by us in 

the reference collections of the Academy of Natural 

Sciences of Philadelphia, and they were misled by 

Gabb's original drawing, which fails to show the splitting 

of the ribs at the ventral-lateral shoulder and the consequent doubling of the number of tubercles on the ridges 

bordering the ventral furrow. These features, in addition 

to the suture line, clearly place "A." homfrayi in the 

genus Sirenites. It is similar to the species in the group of 

S. senticosus described by Mojsisovics (1893, p. 727-740) 

from the lower Karnian of the Alps, and thus it was
60 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

probably collected from the Smelser Pass Member of the 

Augusta Mountain Formation, which is largely Karnian 

in age (Nichols and Silberling, 1977).

Figured specimen. Holotype, ANSP 30793 (originally illustrated by Gabb, 1864, pi. 4, figs. 18-19).

Order PHYLLOCERATIDA

Superfamily PHYLLOCERATACEAE (Zittel, 1884)

Family USSURITIDAE Hyatt, 1900

Genus USSURITES Hyatt, 1900

Ussurites cf. U. arthaberi (Welter)

Plate 32, figures 3-4; text-figure 46

Ammonites billingsianus Gabb. Gabb, 1870, p. 8, pi. 5, fig. 3.

Monophyllites billingsianus (Gabb). Hyatt and Smith, 1905, p. 94, pi. 

24, figs. 3-4. Smith, 1914, p. 48, pi. 5, figs. 3-4 [not pi. 22 = 

Monophyllites cf. M. sphaerophyllus (Hauer); not pi. 48, figs. 8-9 

= Monophyllites cf. M. agenor (Munster)].

cf. Monophyllites arthaberi Welter, 1915, p. 115, pi. 89, figs, la-lc.

cf. Ussurites arthaberi (Welter). Spath, 1934, p. 301.

Ussurites billingsianus (Gabb). Spath, 1934, p. 286, fig. lOOi.

The only phylloceratacids found in the Middle Triassic of the Humboldt Range during the present study were 

a few specimens from the Hyatti Zone that are comparable to Ussurites arthaberi Welter.

As noted by Spath (1934, p. 299), the specimen from 

the Whitney Collection (Museum of Comparative 

Zoology, Harvard University) illustrated as "Monophyllites billingsianus" by Hyatt and Smith (1905, pi. 24, 

figs. 3-4), and reillustrated by Smith (1914, pi. 5, figs. 

3-4), is a Ussurites. It agrees with those illustrated here 

as Ussurites cf. U. arthaberi in having only three distinct 

saddles on its external suture and in lacking subdivision 

on the ventral side of the second saddle. The locality of 

this specimen is given only as "Middle Triassic, East 

Range, Humboldt Mountains, Nevada."

The specimen described by Gabb (1870, pi. 5, fig. 3) as 

"Ammonites billingsianus," subsequent to his (Gabb,

B

\

FIGURE 46. Suture lines (X 2) of Ussurites cf. U. arthaberi (Welter). 

A, plesiotype, USNM 248919. B, plesiotype, USNM 248993, 

specimen not figured.

1864) original description of this species, is also a Ussurites like U. arthaberi. No locality was given for this 

specimen by Gabb who erroneously regarded its suture 

as that characteristic of his species "Ammonites" billingsianus.

Figured specimen. Plesiotype, USNM 248919.

Occurrence. USGS locality M533 (1); USGS 

Mesozoic localities M1181 (1) and M1185 (1); float from 

Hyatti Zone in northern part of the Humboldt Range, 

Nev.

Genus MONOPHYLLITES Mojsisovics, 1879 

Monophyllites cf. M. sphaerophyllus (Hauer)

cf. Ammonites sphaerophyllus Hauer, 1850, p. 113, pi. 18, figs.

1la-lid, 

cf. Monophyllites sphaerophyllus (Hauer). Mojsisovics, 1882, p. 206,

pi. 79, figs. 1-2, 3. 

Monophyllites billingsianus (Gabb). Smith, 1914, p. 48, pi. 22, figs.

1-2?, 3-4a, 5? [not pi. 5, figs. 3-4 = Ussurites cf. U. arthaberi

(Welter); not pi. 48, figs 8-9 = Monophyllites cf. M. agenor

(Munster) ].

Three specimens from the fossiliferous upper Anisian 

or lowermost Ladinian beds at Fossil Hill are illustrated 

by Smith (1914) as "Monophyllites billingsianus." Shell 

fragments of Daonella in the matrix of the specimen illustrated by figures 3-4a on Smith's plate 22 confirm 

this stratigraphic assignment. As pointed out by Spath 

(1934, p. 300), the suture of this specimen has the 

slightly more complex subdivision of the second saddle 

that distinguishes Monophyllites from Ussurites, and it 

is comparable to the suture of Monophyllites 

sphaerophyllus (Hauer).

Spath noted that according to Smith's locality data 

Monophyllites and Ussurites evidently occur together in 

Nevada, but this is not necessarily so: the Monophyllites 

from Fossil Hill illustrated by Smith are younger than 

the Ussurites illustrated here from the northern part of 

the Humboldt Range, and the localities and 

stratigraphic positions of the Ussurites illustrated by 

Gabb (1870), Hyatt and Smith (1905), and Smith (1914) 

are unknown.

Monophyllites cf. M. agenor (Munster) 

Plate 32, figures 1-2; text-figure 47

cf. Ammonites (Ceratites) agenor Munster, 1834, p. 15, pi. 2, fig. 9.

Ammonites billingsianus Gabb, 1864, p. 26, pi. 5, figs. 20-20a.

cf. Monophyllites agenor (Munster). Mojsisovics, 1882, p. 205, pi. 78, 

figs. 6, 7, 8-9.

cf. Mojsvarites agenor (Munster). Mojsisovics, 1902, p. 316.

Monophyllites billingsianus (Gabb). Smith, 1914, p. 48, pi. 48, figs. 8-9 

[not pi. 22 = Monophyllites cf. M. sphaerophyllus (Hauer); not 

pi. 5, figs. 3-4 = Ussurites cf. U. arthaberi (Welter)].

A specimen recently located by us in the collections of 

the Academy of Natural Sciences of Philadelphia is
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 61

B

FIGURE 47. Suture lines (natural size) of Monophyllites cf. M. agenor 

(Miinster). A, holotype, ANSP 30794, at whorl height of 20.5 mm. 

B, ventral saddle of same specimen at whorl height of 33 mm.

believed to be the holotype of Ammonites billingsianus 

Gabb. Although it bore no identifying marks or labels 

when found in the ANSP collections, it agrees closely 

with Gabb's original description and generalized illustration. A note, apparently written by Alpheus Hyatt, 

accompanied the specimen and reads: "This is undoubtedly Amm. Billingsianus Gabb and I think it is the 

type A.H."

Although Ammonites billingsianus has previously 

been regarded as both an Anisian Monophyllites or Ussurites, probably because of the simple suture of a 

specimen erroneously illustrated by Gabb (1870) under 

this specific name, the holotype is a Monophyllites comparable to M. agenor (Miinster). According to Gabb 

(1864, p. 27), Ammonites billingsianus was found in the 

East Range of Nevada along with Ammonites homfrayi 

Gabb, which is shown here to be a Sirenites of early Karnian age. As Monophyllites agenor is characteristic of 

the Alpine early Karnian (Mojsisovics, 1882, p. 206, 

209), the ages of Ammonites billingsianus Gabb 

[= Monophyllites cf. M. agenor (Miinster)] and Ammonites [= Sirenites] homfrayi Gabb, based on the 

proper identification of their holotypes, are thus in 

agreement. Neither of these species is a component of 

the Middle Triassic fauna of the Humboldt Range.

Description of holotype. Completely septate; somewhat sheared along plane of symmetry. Maximum 

preserved diameter about 90 mm; corresponding maximum width about 34 mm and width of umbilicus about 

30 mm. Whorls slightly more compressed than shown in 

Gabb's cross section (Gabb, 1864, pi. 5, fig. 20a); W/H 

about 0.76.

Surface of outer shell, as preserved in patches, nearly 

smooth, lacking regular transverse striation.

Suture line monophyllic with incipient diphyllic subdivision of all three lateral saddles, like that typical of 

Monophyllites.

Fragments of trachyceratid ammonites included in 

matrix.

Figured specimen. Holotype, ANSP 30794 

(originally illustrated by Gabb, 1864, pi. 5, figs. 20-20a).

Subclass NAUTILOIDEA

Order NAUTILIDA

Family TAINOCERATIDAE Hyatt, 1883

?Genus AULAMETACOCERAS Miller and Unklesbay, 1948

Aulametacoceras? humboldtensis n. sp.

Plate 31, figures 2-5.

Description. Whorls depressed, subtrapezoidal (e.g., 

holotype having W/H = 1.85) to subquadrate (e.g., 

paratype having W/H = 1.5). On paratype U/D of internal mold is 0.27. Paratype, of which orad half of outer 

whorl is body chamber, is largest available specimen and 

has maximum preserved diameter about 50 mm.

Venter biconvex with median sulcus; ventrolateral 

shoulders angular; flanks broadly convex to flat; umbilical shoulders broadly rounded on internal mold, narrowly rounded on outer shell; umbilical walls steep.

Three longitudinal ridges on venter on either side of 

ventral sulcus; ridges evenly spaced between ventrolateral shoulder and edge of sulcus; interspaces broader 

than ridges. Width across sulcus between the ridges 

bordering it about one-fourth width of venter. 

Ventrolateral shoulder marked by row of tubercles, density of which estimated as 25-30 per volution. 

Ventrolateral tubercles project onto outer flanks as low, 

slightly rursiradiate folds that fade on flanks; flanks 

otherwise unornamented. Umbilical shoulder apparently 

not ornamented.

Suture as for family; siphuncle unknown.

Discussion. Kummel (1953, p. 27) characterized 

Aulametacoceras as having "the general physiognomy of 

Metacoceras but with longitudinal ribs on the venter," 

and following Miller and Unklesbay (1942, p. 726) he included in it besides the Permian type species, A. mckeei 

Miller and Unklesbay, the Karnian species Nautilus rectangularis Hauer. Like N. rectangularis, the new species 

Aulametacoceras? humboldtensis differs from typical 

Aulametacoceras in having a more subquadrate whorl 

shape, in having a median sulcus more or less differentiated from the rest of the venter, and in lacking tuberculation of the umbilical margin. From Nautilus rectangularis, Aulametacoceras? humboldtensis differs 

mainly in its more involute proportions and broader, 

more rapidly expanding whorls. Hence these two Triassic species resemble each other much more than they do
62 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

the type species of Aulametacoceras, and they might 

justifiably be placed in a distinct genus except that ornate tainoceratids are presently too poorly represented 

to allow grouping of the few described species into 

phylogenetically meaningful genera.

The Lower or Middle Triassic specimen from the 

Primoyre Region of the U.S.S.R. described by 

Kiparisova (1961, p. 16, pi. 1, figs. 4a-4c) as a new 

species and subgenus of Pleuroceras, i.e., P. (Ussurinautilus) amurensis, is similar to A.? humboldtensis 

in the configuration and ornamentation of its venter, but 

it is said to have lateral ribs and longitudinal ridges.

Figured specimens. Holotype, USNM 248912; 

paratype, USNM 248913.

Occurrence. USGS locality M533 [1 (paratype)]; 

USGS Mesozoic localities M2369 (1), and M2359 [2 

(including holotype)]; Hyatti Zone in northern part of 

Humboldt Range, Nev.

Genus GERM ANON AUTILUS Mojsisovics, 1902

Germanonautilus furlongi Smith

Plate 32, figures 5-6

Germanonautilus furlongi Smith, 1914, p. 142, pi. 95, figs. 1-2. Kummel, 1953, p. 29, pi. 3, figs. 12-13, text-fig. 12.

Two large specimens of this species, each of which is 

about the same size as Smith's holotype or Kummel's 

plesiotype, were collected as float from the upper Anisian beds at collecting-site C near Fossil Hill. One 

specimen was associated in the same block with a 

specimen of Parafrechites meeki, and the matrix of the 

other agrees lithologically with the rock type unique to 

the Parafrechites dunni beds; hence both specimens 

were probably derived from the Meeki Zone.

On one of these specimens, a phragmocone having a 

maximum preserved diameter of about 95 mm, the outer 

shell is remarkably well preserved and shows the finer 

details of ornamentation. The growth striae are 

markedly biconvex on the flanks and strongly rursiradiate near the umbilical margin. On the venter they 

describe a deep hyponomic sinus. The abrupt umbilical 

shoulder is ridgelike, and, as shown on the holotype, is 

bordered by shallow furrows on the adjacent part of the 

umbilical wall and lower flank. The ventrolateral 

shoulder, which on the internal mold is broadly rounded, 

has on the outer shell two angulations, each of which is 

expressed as a faint longitudinal ridge. On the ventral 

surface are several more faint longitudinal ridges. The 

surface of an intermediate shell layer on the venter bears 

Runzelschichten ornamentation in addition to fine lirae 

that form a reticulate pattern with the impressions of the 

growth striae.

The small bodychamber segment illustrated by figures 

5-6 on plate 32 was also collected as float from 

collecting-site C and was probably derived from the

Parafrechites dunni beds of the Meeki Zone. Umbilical 

and ventrolateral ridges on this specimen correspond to 

those on the larger specimen described above, but are 

more strongly expressed, the ventrolateral ridges being 

visible on the internal mold. On the outer shell, which is 

preserved in small patches, bundling of the growth striae 

where they pass over these ridges produces a faint 

irregular tuberculation suggestive of that of 

Mojsuaroceras.

Figured specimen. Plesiotype, USNM 248920.

Occurrence. Float at USGS locality M608, Meeki 

Zone, Fossil Hill, Humboldt Range, Nev.

Family GRYPOCERATIDAE Hyatt in Zittel, 1900

Genus GRYPOCERA8 Hyatt, 1883

Grypoceras whitneyi (Gabb)

Plate 32, figures 9-11

Nautilus whitneyi Gabb, 1864, p. 19, pi. 3, figs. 2-3. 

Grypoceras whitneyi (Gabb). Smith, 1914, p. 141, pi. 16, figs. 2-3; pi. 

99, figs. 5-7. Kummel, 1953, p. 53, pi. 5, fig. 1; pi. 6, figs. 1-4.

Grypoceras, apparently conspecific with G. whitneyi 

(Gabb), were found during the present study in the 

Hyatti Zone of the middle Anisian and the Rotelliformis 

and Meeki Zones of the upper Anisian. Gabb's type 

specimen from the "Buena Vista district" could be from 

any of these zones, as fossiliferous beds of both middle 

and late Anisian age occur in the general vicinity of 

Unionville, i.e., the Buena Vista mining district. Smith's 

plesiotype from the Wheeler mine area south of Unionville is probably from the upper Anisian.

Smith's and Kummel's descriptions, based on Smith's 

plesiotype, adequately describe the holotype, which was 

recently located in the collections of the Academy of 

Natural Sciences of Philadelphia.

Figured specimen. Holotype, ANSP 30792 (originally illustrated by Gabb, 1864, pi. 3, figs. 2-3).

Occurrence. USGS locality M533 (10+); USGS 

Mesozoic locality M1181 (1), Hyatti Zone, northern part 

of the Humboldt Range; USGS localities M965 (1), 

Rotelliformis Zone, M142 (1) and one float specimen 

from the Parafrechites dunni beds, Meeki Zone, vicinity 

of Fossil Hill, Humboldt Range, Nev.

Family LIROCERATIDAE Miller and Youngquist, 1949

Genus PARANAUTILUS Mojsisovics, 1902

Paranautilus smith! Kummel

Plate 32, figures 7-8

Paranautilus multicameratus (Gabb). Smith, 1914, p. 143, pi. 95, figs.

3-4 [not pi. 16, figs. 4-5 = P. multicameratus (Gabb)]. 

Paranautilus smithi Kummel, 1953, p. 71, pi. 4, figs. 11-12; pi. 8, figs.

12-13, text-fig. 36.

Kummel (1953) justifiably established this species for 

the specimen previously described by Smith (1914) as
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 63

Paranautilus multicameratus (Gabb) because Smith's 

specimen differs from Gabb's figure of "Nautilus" multicameratus (Gabb, 1864, pi. 3, figs. 4-5) in lacking a 

ventral median depression at a comparable diameter 

and in lacking the lirate ornament said by Gabb (1864, 

p. 20) to be present on his specimen.

A badly crushed Paranautilus (ANSP 30790), consisting largely of phragmocone, was recently found in the 

collections of the Academy of Natural Sciences of 

Philadelphia associated with a note that was evidently 

written by Alpheus Hyatt and reads "It is possible that a 

part of this [specimen] may have been used for Gabb's 

[figures of "Nautilus" multicameratus]" A label also 

found with the specimen gives the locality as "Dun Glen, 

Nev.," which corresponds with the type locality of "N." 

multicameratus. However, this specimen is about 110 

mm in diameter and is thus much larger than the 

holotype of "N." multicameratus should be, according to 

Gabb's figures. Moreover, it lacks the depressed venter 

and other distinguishing features shown by Gabb's 

figures. It is thus evidently not the holotype of "N." multicameratus, which species is probably best regarded as 

a nomen dubium.

The large specimen of Paranautilus smithi, illustrated 

by figures 7-8, plate 32, was collected in place from the 

lower part of the Occidentalis Zone near Fossil Hill. It is 

septate to a diameter of about 150 mm; the maximum 

preserved diameter is about 160 mm, beyond which part 

of the body chamber is preserved for another quarter 

whorl. This specimen adds to the knowledge of P. smithi 

by showing the transition in whorl shape from the inner 

whorls, which have broadly rounded flanks and venter, 

to the mature body chamber, which is more nearly 

trapezoidal, having nearly flat convergent flanks and a 

flat venter.

Figured specimen. Plesiotype, USNM 248921.

Occurrence. USGS localities M143 (1), M612 (1), 

and M963 (1), Meeki Zone, vicinity of Fossil Hill; M620 

(2), M961 (1), and M965 (1), Occidentalis Zone, vicinity 

of Fossil Hill, Humboldt Range, Nev.

Order ORTHOCERIDA

Family ORTHOGERATIDAE M'Coy, 1844

?Genus MICHELINOCERAS Foerste, 1932

Michelinoceras? cf. M.? campanile (Mojsisovics)

Plate 33, figures 1-2

cf. Orthoceras campanile Mojsisovics, 1882, p. 291, pi. 113, figs. 1, 

2a-2b, 3, 4a-4b, lla-llb.

Orthoconic nautiloids occur in all of the Anisian zones 

in the Humboldt Range wherever cephalopod faunas are 

well developed. Longitudinal thin sections of two 

specimens from the Meeki Zone in the Fossil Hill area 

are illustrated to show the simple internal structure of

these shells. The siphuncle is central and cylindrical, 

contracting only slightly at the septal necks, which are 

orthochoanitic, or nearly so. Neither siphuncular nor 

cameral deposits are present.

Following Sweet (in Teichert and others, 1964) these 

orthocones are tentatively included in Michelinoceras, 

although the typical members of this genus are of early 

Paleozoic age and possess cameral deposits. Kiparisova 

(1961), among others, has described similar Triassic 

orthocones under the generic name Trematoceras 

Eichwald, but the type species of this genus, T. elegans 

(Minister), is characterized by a unique arrangement of 

episeptal and mural deposits in the chambers.

Figured specimens. Plesiotypes, USNM 248922 and 

248923.

Occurrence. USGS localities M139 (1), M608 (15+), 

M611 (1), Rotelliformis Zone; M142 (6+), M618 (1), 

M619 (3), M958 (1), Meeki Zone; M144 (3), M144 minus 

6 ft (1.8 m) (1), M620 (1), M622 (7+) M961 (2) and M962 

(1), Occidentalis Zone, vicinity of Fossil Hill, Humboldt 

Range, Nev.

Subclass COLEOIDEA

Order AULACOCERIDA

Family XIPHOTEUTHIDIDAE Naef, 1922

Genus ATRACTITES Giimbel, 1861

Smooth aulacocerid coleoids referred to Atractites are 

fairly common in the upper Anisian of the Humboldt 

Range as well as that at other localities in northwestern 

Nevada. All of the specimens collected near Fossil Hill 

are broken segments, mostly of rostra. Several specimens 

were also collected from the lower and middle Anisian 

Caurus and Hyatti Zones of the Humboldt Range, but 

for some reason all of these are pieces of phragmocones 

rather than of the more durable rostra.

Allowing for some variation, rostra from different 

stratigraphic levels within the upper Anisian have distinctive shapes, and some can be identified with the 

species recognized on the basis of rostra by Smith (1914). 

Phragmocones associated with these rostra, however, are 

externally alike regardless of stratigraphic position, and 

the recognition by Smith of "Atractites bockhi (Stiirzenbaum)," a species originally based on part of a 

phragmocone, is meaningless.

Recognition of species among the Atractites guards 

described here is somewhat tenuous owing to their 

fragmentary nature and the apparent morphologic variation among specimens from the same stratigraphic level. 

Nonetheless, three generalized but morphologically distinct and stratigraphically restricted groups are 

recognized and treated as separate .species. The material 

at hand suggests that greater taxonomic refinement 

might be possible if collections were more complete and 

that species of Atractites, based on the shape of guards,
64 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

may be as narrowly limited in stratigraphic ranges as the 

species of ammonites with which they occur.

The few relatively well-preserved Atractites phragmocones from the upper Anisian of Nevada confirm 

some of the morphologic characters that Jeletzky (1966) 

has found to be characteristic of the Order Aulacoceri da. 

Two specimens, one (pi. 33, figs. 3-4) from the Rotelliformis Zone near Fossil Hill in the Humboldt Range 

and the other (pi. 34, figs. 1-3) from the Meeki Zone of 

the Favret Formation in the Augusta Mountains, show 

the configuration of the conothecal striae. Both of these 

specimens are incomplete phragmocones, but in all 

probability they correspond with the associated rostra, 

which are like those described herein. On the flanks of 

these phragmocones the conothecal striae are inclined 

orally towards the dorsum, forming an angle of about 60° 

with the axis of the shell; on the dorsum, they describe a 

broad, orally convex curve, and on the venter an orally 

concave curve. Hence, in agreement with Jeletzky's 

observations, they lack a discrete dorsal proostracum, 

and they have no ventral proostracum.

Thin sections of the specimen mentioned above from 

the Favret Formation, Atractites sp. C, and of another 

specimen from the same locality, Atractites sp. B, show 

the structure of the siphuncle and septal necks in some 

detail, although not completely. They can be interpreted 

to have the same structure as that described by Jeletzky 

(1966, p. 20-22) for aulacocerids in general, but not that 

illustrated by his text-figure 3, which is incorrectly 

drafted (J. A. Jeletsky, written commun., 1969). The 

larger of these specimens, Atractites sp. C, consists of 

eight camera of the phragmocone expanding in dorsalventral diameter from 17 to 24.5 mm. In thin section the 

septa are seen to be mostly broken away except along the 

ventral side in the vicinity of the siphuncle. Though 

evidently composed originally of faintly lamellar 

calcareous material, the septa are preserved as filmy inclusions in the mosaic of calcite crystals that fill the 

camera and replace the shell material. In vertical section 

(fig. 48; pi. 33, fig. 7) each septum is strongly curved 

forward as it approaches the dorsal side of the septal 

foramen and is joined on its ventral side with a necklike 

structure of similar composition. The internal lamination of the septum does not appear to bend back in 

retrochoanitic fashion so as to be continuous with that of 

this necklike structure, and hence the true septal necks 

are best described as achoanitic or slightly prochoanitic. 

The necklike structure is evidently a modified connecting ring that is distinctly two layered and whose 

outer surface is attached to the apicad side of the 

prochoanitic septal neck. This necklike part of the connecting ring follows the curvature of the septum in a 

dorsad-apicad direction for a short distance and then 

projects apically, forming a funnellike siphuncle wall.

The thickness and composition of each funnel is like that 

of the septa for about one-third camera apicad of its septum of origin, after which it thins and becomes dark in 

color, as if it was partly composed of organic matter, and 

its two-layered construction becomes indistinct. In the 

smaller sectioned specimen (pi. 33, fig. 6), which is the 

alveolar part of a phragmocone, each funnellike connecting ring of the siphuncle wall extends a little over 

IVz camera apicad from its septum of origin and invaginates within the funnel produced by the preceding 

septum. The siphuncle wall in this specimen thus consists of two funnellike invaginated connecting rings in 

the orad part of each chamber and one connecting ring in 

the apicad part. The apicad extent of each runnel in the 

larger specimen described above is obscured by discoloration within the siphuncle but seems to be similar, 

at least the orad part of the siphuncle wall between successive chambers being formed by two invaginated connecting rings.

Atractites sp. A.

Plate 33, figures 3-4

Figured specimen. USNM 248924. 

Occurrence. USGS locality M136, Rotelliformis 

Zone, vicinity of Fossil Hill, Humboldt Range, Nev.

Atractites sp. B. 

Plate 33, figure 6

Figured specimen. USNM 248926. 

Occurrence. USGS locality M636, upper Anisian, 

Favret Canyon, Augusta Mountains, Nev.

Atractites sp. G. 

Plate 33, figure 7; plate 34, figures 1-3; text-figure 48

Figured specimen USNM 248927. 

Occurrence. USGS locality M636c, Meeki Zone, 

Favret Canyon, Augusta Mountains, Nev.

Atractites clavatulus Smith 

Plate 33, figure 5; plate 34, figures 6-11

Atractites clavatulus Smith, 1914, p. 139, pi. 96, figs. 11-12 [holotype], 

13, 14.

The stratigraphically lowest well-represented belemnite guards from the Fossil Hill area are from the Gymnotoceras blakei beds of the Rotelliformis Zone and are 

comparable with the specimens described by Smith as 

Atractites clavatulus. They are distinguished by their 

clavate shape, thickly ovate or elliptical cross section, 

and the deep apicad penetration of the alveolus into the 

bulbous part. The amount of constriction that produces 

the clavate shape varies among individual specimens, 

and the constriction of the horizontal diameter is com-
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 65

FIGURE 48. Siphuncular structure (X 25) of Atractites sp. C (USNM 

248927) from the upper Anisian of the Favret Formation, Augusta 

Mountains, Nev. Diagrammatic interpretation of dorso-ventral median section illustrated by plate 33, figure 7. Orad direction upward; ventral side to left. Si, interior of siphuncle; Si, septum; CRli 

and CRlo, inner and outer layers of connecting ring originating at 

SI; CR2, undifferentiated layers of connecting ring originating at 

next orad septum. Ventral wall of siphuncle is not preserved, and 

details in the vicinity of septal foramina and apicad termination of 

CR2 are not clearly shown on the specimen.

monly greater in relation to the amount of constriction of 

the dorso-ventral diameter. Apicad of the inflated part, 

the guard is drawn out into a gradually tapering, much 

compressed apex of unknown length.

A fragment (USNM 248929; pi. 34, figs. 4-5) of a much 

inflated clavate guard from the Paraceratites cricki 

beds, just below the occurrence of A. clavatulus, has a 

nearly circular cross section, and only the apicad tip of 

the alveolus is represented at the orad end of the inflated 

part of the guard. The alveolus thus seems to have been 

situated farther orad in the guard than it is in A. 

clavatulus, and this specimen may represent Atractites 

elegans Smith (1914, pi. 96, fig. 10).

Figured specimens. Plesiotypes, USNM 248925, 

248930, and 248931.

Occurrence USGS locality M608 (16), Gymnotoceras blakei beds, Rotelliformis Zone, vicinity of 

Fossil Hill, Humboldt Range, Nev.

Atractites solidus Smith 

Plate 34, figures 12-25

Atractites solidus Smith, 1914, p. 140, pi. 96, figs. 1-2 [holotype], 3-4, 

5.

This species was found only in the Frechites 

nevadanus beds of the Meeki Zone. The alveolar part of 

the guard is robust with its width and height approximately equal. In contrast to the broadly rounded dorsal 

side and flanks, the ventral side is flattened and bears a 

longitudinal median depression or groove of varying 

strength. Viewed laterally, the dorsal margin is nearly 

straight, whereas the ventral margin tends to be broadly 

bowed in a bellowlike curve. The guard is only slightly 

constricted towards its orad end, lateral constriction being more pronounced than dorso-ventral constriction. 

Apicad of the alveolus the sides taper more rapidly than 

the dorsum or venter, producing a long, laterally compressed apex, the tip of which is not preserved on any of 

the available specimens.

The specimen illustrated by Smith (1914, pi. 96, figs. 

8-9) as "Atractites nevadensis (Meek)" may belong to A. 

solidus but is larger and more generalized in shape.

Figured specimens. Plesiotypes, USNM 248932 to 

248936.

Occurrence. USGS localities M142 (3), M166 (1), 

M612 (1), and M614 (3); Frechites nevadanus beds, 

Meeki Zone, vicinity of Fossil Hill, Humboldt Range, 

Nev.

Atractites nevadensis (Meek) 

Plate 34, figures 26-33

Belemnites nevadensis Meek, 1877, p. 138, pi. 12, figs. 7-7b [holotype]. 

Atractites burckhardti Smith, 1914, p. 139, pi. 96, figs. 6-7 [holotype]. 

[not] Atractites nevadensis (Meek). Smith, 1914, p. 139, pi. 96, figs. 

8-9.

Meek's typical specimen of this species borders on being specifically unidentifiable, and yet it shows a high 

degree of lateral compression of the guard at a relatively 

large diameter, which is the characteristic feature of the 

specimens grouped under this name. This is also the 

diagnostic feature attributed to Atractites burckhardti 

by Smith. In the alveolar region the lateral diameter of 

the guard amounts to 0.60 to 0.75 of the dorso-ventral 

diameter and the cross section is either elliptical or ovate 

with the dorsal side more broadly rounded than the 

ventral. The apex of the guard is even more compressed 

than the orad part and seems to vary in length, some 

specimens being more bluntly terminated than others. 

None of the specimens are more than faintly constricted 

towards the orad end of the guard.

Specimens answering this general description 

characterize both the Parafrechites meeki and the 

stratigraphically higher Nevadites beds, but more adequate material might demonstrate the presence of more 

than one species in this part of the section. One
66 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

specimen from the Nevadites beds (pi. 34, figs. 31-33) is 

unique in having a pair of pronounced dor sal-lateral 

grooves that elevate the dorsal margin into a ridge, 

diverge apically in dorsal view, and in lateral view seem 

to outline the position of the alveolus within the guard. 

The ventral margin of this part of the guard is narrowly 

rounded so that the cross-sectional outline approaches 

that of the ace of spades. This specimen somewhat 

resembles the guard of the Upper Triassic genus Calliconites Gemmellaro which, however, bears ventrallateral as well as dorsal-lateral grooves.

Figured specimens. Plesiotypes, USNM 248937 to 

248939.

Occurrence. USGS localities M140 (1), M143 (2), 

M616 (1), M958 (1), and M963 (1), Parafrechites meeki 

beds, Meeki Zone; M144 (3), M621 (2), and M962 (1), 

Occidentalis Zone, vicinity of Fossil Hill, Humboldt 

Range, Nev.

Class BIVALVIA

Order PTERIOIDA

Family PTERIIDAE Gray, 1847

Genus PTERIA Scopoli, 1777

[?] Rhynchopterus Gabb, 1864, p. 31 [type species Rhynchopterus 

obesus Gabb, by monotypy].

The name Rhynchopterus Gabb is a junior homonym 

of Rhynchopterus Shrank, 1798, originally used in combination with the trivial name of a weevil. According to 

Charles W. O'Brien, Department of Entomology, 

University of California, Berkeley (written commun., 

1962), Shrank's name may have resulted from a lapsus 

calami wherein another name used by Shrank, 

Rhychophorus, was intended. Nevertheless, Rhynchopterus Shrank is still an available name, and Rhynchopterus Gabb should be suppressed. Rather than erect a 

new generic name for Rhynchopterus Gabb, which is still 

imperfectly known, Gabb's genus is regarded as a 

probable synonym of Pteria, sensu lato.

Pteria? obesus (Gabb)

Plate 38, figures 8-9

Rhynchopterus obesus Gabb, 1864, p. 32, pi. 5, figs. 30a-30b. Smith, 

1914, p. 145, pi. 16, figures 16-17. Newell in Cox and others, 1969, 

p. N305, fig. C39, 3.

Besides the ubiquitous shells and fragments of 

Daonella, specimens of this relatively inflated, smooth 

pteriid(?) are the only other common noncephalopod 

molluscan shells found in the upper Anisian at Fossil 

Hill. Seventy-five specimens are represented among the 

stratigraphically controlled bedrock collections and are 

evenly distributed throughout the section from the 

Paraceratites vogdesi beds of the Rotelliformis Zone to

the Nevadites furlongi beds of the Occidentalis Zone. 

Among these specimens left valves outnumber right 

valves 2:1.

Little can be added to the published description of this 

species other than that the right valves are approximately mirror images of the left, except for being less inflated. The hinge structure could not be prepared on any 

of the available specimens.

The specimen illustrated was found along with others 

of Gabb's types at the Academy of Natural Sciences of 

Philadelphia and is thought to be the holotype, although 

as with Gabb's other specimens, there was no mark or 

label associated with the specimen to indicate this. The 

slab bearing this specimen contains Nevadites furlongi 

and Daonella dubia and is thus from the Occidentalis 

Zone. This and other specimens from the upper part of 

the upper Anisian on the average tend to be more 

elongate than those from low in the substage, but 

otherwise they are generally the same.

Figured specimen. Holotype?, ANSP 30791.

Family POSIDONIIDAE Frech, 1909 

Genus DAONELLA Mojsisovics, 1874

Daonellas are an important component of the upper 

Anisian and Ladinian faunas of the Humboldt Range. 

They are abundant enough so that fragments of their 

shells make up an appreciable part of some limestone 

beds, and distinct species from different levels in the section commonly can be distinguished by obvious 

morphologic features. Nevertheless, characterization of 

species among these shells, and for that matter among 

Halobias and Daonellas in general, is less than satisfactory, for despite their local abundance, relatively complete large-size specimens, adequately showing the 

morphology, are difficult to obtain.

Some of the more abundant upper Anisian Daonellas 

from the Humboldt Range can be assigned to Daonella 

americanum and D. dubia, species originally described 

from the Humboldt Range. Other kinds generally resemble forms described from the Alps and yet differ in 

details that might prove to be taxonomically significant 

if better material were available for study. These 

specimens are compared with Alpine species such as D. 

sturi, D. moussoni, and D. elongata, each of which was 

the earliest of its kind to be described. As used herein 

these names represent groups of potentially or actually 

more narrowly defined and more stratigraphically 

restricted specific entities, which can be recognized in 

exceptional geologic situations such as that described by 

Rieber (1968, 1969). In favorable situations, as Rieber 

has demonstrated, detailed evolutionary trends among 

Daonellas can be established, and the recognition of 

numerous narrowly defined specific entities is justified. 

More commonly, however, ideal material is lacking, and
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 67

more generalized, broader species concepts, such as 

those adopted herein, are appropriate. Even so, such 

species are still biostratigraphically useful and have 

resolving power for stratigraphic subdivision at about 

the level of one ammonite zone.

In order to characterize the differences in shell shape 

among different kinds of Daonellas, the conventions 

used here for measuring the size, shape, and ribbing of 

these shells are illustrated on figure 49.

k-AD >

H

FIGURE 49. Diagrammatic sketch of the right valve of a Daonella 

showing the conventions used in measuring and describing these 

shells. L, length; H, height; AD, anterior-dorsal length; AV, 

anterior-ventral length. Also shown is the position of the centrally 

located 90° of arc within which the number of ribs or radial furrows 

are counted.

Daonella americana Smith

Plate 35, figures 1-7

Daonella americana Smith, 1914, p. 143, pi. 49, figs. 4-5 [holotype], 6, 

7?, 8?, 9?. Silberling, 1962, table 1, p. 157 [in part].

Description. Shell elongate (H/L about 0.50); 

obliquely subtrigonal (AV/L about 0.69). Ribbing 

produced by generally weak radial striae arranged randomly by relative strength except on central part of shell 

where coarsest striae tend to be widely and evenly 

spaced, imparting to the ribbing a distinctly grouped or 

regularly subdivided character. About 8-10 coarse striae 

per 90° of arc in central field of ribbing; generally several 

(rarely as many as 10) weaker striae per coarse striation.

Figured specimens. Plesiotypes, USNM 248940 to 

248946.

Occurrence USGS localities M965, M136 minus 7 ft 

(2.1 m), M139, M162, M966, M136, M163, M606, M967 

minus 9 ft (2.7 m), M607, M967, and M964, Rotelliformis Zone; USGS locality M612, Frechites 

neuadanus beds, lowermost Meeki Zone; vicinity of Fossil Hill, Humboldt Range, Nev.

Daonella cf. D. sturi (Benecke)

Plate 35, figures 8-12

cf. Halobia sturi Benecke, 1868, p. 55, pi. 4, figs. 9a-9b, 10, 11. 

cf. Daonella sturi (Benecke). Mojsisovics, 1874, p. 17, pi. 2, figs. 7-8. 

Daonella americana Smith [in part]. Silberling, 1962, table 1, p. 157.

The shells compared with this Alpine species differ 

from Daonella americana in being more elongate (H/L 

about 0.40) and correspondingly more oblique (AV/L 

about 0.74). More importantly, the nature of the ribbing 

differs in that the ribs are not grouped according to 

strength. Instead, striae or interspaces of varying 

strength tend to separate each rib or pair of ribs, and the 

width of the most pronounced interspaces rivals that of 

the rounded, flat-topped, undivided ribs between them. 

Characteristically, several or more successive ribs among 

those in the central part of the shell are of about the 

same strength and spacing. Within a 90° arc in the 

central part of the rib field, the ribs vary in strength by a 

factor of several times, but they generally total 15-20 in 

number.

At Fossil Hill the stratigraphic range of Daonella cf. D. 

sturi overlaps that of D. americana, but on any one bedding surface shells of only one species or the other occur.

Figured specimens. Plesiotypes, USNM 248947 to 

248951.

Occurrence. USGS localities M607+2.0 ft (0.6 m), 

M608, M609, and M613, Gymnotoceras blakei beds, uppermost Rotelliformis Zone; M142, Frechites neuadanus 

beds, lowermost Meeki Zone, vicinity of Fossil Hill, 

Humboldt Range, Nev.

Daonella cf. D. elongata Mojsisovics 

Plate 36, figures 1-5

cf. Daonella elongata Mojsisovics, 1874, p. 13, pi. 2, fig. 9. 

Daonella cf. D. elongata Mojsisovics. Silberling, 1962, p. 157.

Daonellas having a bizarre, extremely elongate (H/L 

0.20-0.30), oblique shape, fine, fairly regular ribs, and 

anteriorly pronounced commarginal folds resemble 

members of the Alpine species group of Daonella 

elongata and are the first record of such forms from outside of the Alps. Among the narrowly defined specific entities placed in an evolutionary series within this species 

group by Rieber (1968), the Nevada specimens most 

closely resemble "Daonella vaceki Kittl," as characterized by Rieber.

Figured specimens. Plesiotypes, USNM 248952 to 

248956.

Occurrence. USGS locality M968, float block 

derived from the Parafrechites dunni beds, upper part of 

Meeki Zone, vicinity of Fossil Hill, Humboldt Range, 

Nev.
68 MOLLUSCAN FOSSILS, HUMBOLDT RANGE, NEVADA

Daonella cf. D. moussoni (Merian)

Plate 36, figures 6-9; plate 37, figures 1-3

cf. Posidonomya moussoni Merian in Escher v. d. Linth, 1853, p. 93, pi.

5, figs. 46, 47, 48. 

cf. Daonella moussoni (Merian). Mojsisovics, 1874, p. 9, pi. 3, figs. 18,

19. 

Daonella. moussoni (Merian). Smith, 1914, p. 144, pi. 50, figs. 4, 5-6, 7,

8, 9?, 10-11. 

Daonella cf. D. moussoni (Merian). Silberling, 1962, p. 157.

Like the Alpine forms with which they are compared, 

these shells are relatively high (H/L 0.75-0.80) and erect 

(AV/L 0.50-0.55) and have densely spaced ribs (about 

two or three per millimeter) that are fairly equal in 

strength, generally not varying in width by more than 

two times. Commarginal folds are pronounced on the 

umbonal part of the shell. Most of the more or less complete specimens are small, less than 20 mm in length, 

and the largest specimen (pi. 36, fig. 8) apparently did 

not exceed 60 mm in length.

Similar shells in the southern Alps that were first assigned to Daonella moussoni have been named D. 

pseudomoussoni and D. luganensis by Rieber (1969) and 

apparently characterize about the same part of the upper Anisian as do the specimens from Nevada.

Figured specimens. Plesiotypes, USNM 248957 to 

948960.

Occurrence. 7USGS localities M140, M143, and 

M959, middle and upper Meeki Zone; USGS localities 

M145, M146, 7M620, M621, M622, M623, M624, M625, 

M626, M909, M961, M962, and M962a, throughout Occidentalis Zone, vicinity of Fossil Hill and the Arizona 

mine area south of Buena Vista Canyon, Humboldt 

Range, Nev.

Daonella dubia (Oabb)

Plate 36, figures 10-15

Halobia? dubia Gabb, 1864, p. 30, pi. 5, figs. 28a-28b [lectotype

selected by Silberling, 1962, p. 153, footnote 2], [not fig. 28]. 

Daonella dubia (Gabb). Mojsisovics, 1874, p. 22. Smith, 1904, p. 405,

pi. 44, fig. 5. Smith, 1914, p. 143, pi. 14, fig. 5; pi. 44, figs. 10, 11?;

pi. 50, figs. 1, 2?, 3?. Silberling, 1962, p. 157. 

Daonella lindstroemi Mojsisovics. Smith, 1914, p. 144, pi. 49, figs. 1-3. 

[?] Halobia (Daonella) lommeli Wissman. Meek, 1877, p. 100, pi. 10,

fig. 5.

Description. Relatively large (L exceeding 100 mm), 

elongate (L about twice H), obliquely subtrigonal (AV/L 

0.70-0.80) shells having distinctly grouped or bundled 

ribs. In central part of shell pronounced radial grooves, 

wider than they are deep and irregularly spaced at about 

10-12 per 90° of arc, define first-order ribs. These are 

further subdivided by second-order striae into flattopped secondary ribs whose surfaces bear several more 

fine radial striae. Commarginal growth striae or folds 

generally obscure.

Discussion. Compared with the stratigraphically 

lower Daonella americana, which of the species in 

Nevada most closely resembles D. dubia, the principal 

radial grooves that produce the ribbing are much 

stronger on D. dubia by a factor of two or three times, 

and the ribs are not so regularly bundled or grouped into 

two generally distinct size classes. Daonella fascicostata, 

described by Rieber (1969, p. 671, pi. 4, figs. 1-2, 4-6, 

and 8) from the southern Alps, is very similar and 

perhaps conspecific with D. dubia, the differences cited 

by Rieber between these species being largely attributable to the inadequacies of the figures of D. dubia 

published by Smith (1914).

Figured specimens. Lectotype, ANSP 20785; 

plesiotypes, USNM 248961 to 248965.

Occurrence. 7USGS localities M144, M620, and 

M621, lower part of Occidentalis Zone; USGS localities 

M145, M623, M624, M625, and M626, upper part of Occidentalis Zone, vicinity of Fossil Hill, Humboldt Range, 

Nev.

Daonella rieberi n. sp. 

Plate 37, figures 4-9; plate 38, figures 1-2

Daonella aff. D. taramellii Silberling and Wallace, 1969, p. 20.

Description. Moderately elongate (H/L 0.60-0.65), 

obliquely ovate (AV/L 0.60-0.70) shells having beak well 

forward on dorsal margin (AD/L 0.35-0.50). Numerous 

(35-40 per 90° of arc in midshell) flat-topped ribs as 

much as about 1 mm in width and generally do not vary 

in width by more than two or three times. Interrib striae 

much narrower than average width of ribs and of uniform strength. Commarginal folds generally prominent, 

especially near umbo.

Discussion. From the stratigraphically lower shells 

assigned here to Daonella cf. D. moussoni, D. rieberi differs in its more oblique and ovate shape and its broader 

ribs. Among Alpine forms D. rieberi resembles the 

roughly correlative species D. taramellii Mojsisovics except for being more ovate and elongate.

This species is named for Hans Rieber whose studies of 

the Grenzbitumenzone in the southern Alps have added 

importantly to knowledge of Anisian Daonellas.

Figured specimens. Holotype, USNM 248969. 

Paratypes, USNM 248970 to 248975.

Occurrence USGS localities M147 (the type locality 

of D. rieberi where it is associated in bedrock collection 

with Protrachyceras cf. P. americanum Mojsisovics) and 

M628, vicinity of Fossil Hill; USGS Mesozoic locality 

M3094, associated in float collection with Protrachyceras cf. P. meeki, vicinity of Fossil Hill; USGS locality 

M911, American Canyon about 2.5 km north-north west 

of Fossil Hill; USGS locality M908, Arizona mine area
PALEONTOLOGY SYSTEMATIC DESCRIPTIONS 69

south of Buena Vista Creek canyon. All from 

Subasperum Zone, Humboldt Range, Nev.

Daonella n. sp. ex aff. D. indica Bittner 

Plate 38, figures 3-4

aff. Daonella indica Bittner, 1899, p. 39, pi. 7, figs. 4,5, 6, 7, 8,9,10,11.

Two slabs of buff calcareous siltstone from beds of 

probable late Ladinian age about 160 m above the base 

of the upper member of the Prida Formation in the 

southern part of the Humboldt Range contain fairly 

large (L at least 100 mm) Daonellas that embody a 

unique set of characters. They are neither well enough 

represented nor well enough tied into the stratigraphic 

section to warrant naming them and are designated here 

simply as having affinity with Daonella indica, an upper 

Ladinian Himalayan species.

Like D. indica these shells have a high (H/L about 

0.80), roughly equilateral and circular outline and 

numerous (about 30 per 90° of arc in midshell) flattopped primary ribs that are similar to one another in 

width. However, in contrast with D. indica in which a 

secondary radial groove tends to divide each primary rib 

into two parts, the flat surfaces of the primary ribs on the 

Nevada specimens bear several very fine radial striae.

On one of the two illustrated slabs (pi. 38, fig. 4) a 

negative Daonella impression having the ribbing pattern 

of D. lommelli confirms the upper Ladinian stratigraphic assignment of this collection based on its stratigraphic level.

Figured specimens. Plesiotypes, USNM 248978 and 

248979.

Occurrence. USGS Mesozoic locality M3095, south 

wall of Fisher Canyon, southern Humboldt Range, Nev.

Daonella cf. D. lommeli (Wissmann)

Plate 38, figures 5-7

cf. Halobia lommeli Wissmann, in Wissmann and Munster, 1841, p.

22, pi. 16, fig. 11. 

cf. Daonella lommeli (Wissmann). Mojsisovics, 1874, p. 19, pi. 2, figs.

12, 13.

Daonellas having the distinctive appearance of the 

Alpine upper Ladinian species Daonella lommeli occur 

in the Humboldt Range in several places well above the 

base of the upper member of the Prida Formation 

(Silberling and Wallace, 1969, p. 20). Like the typical 

Alpine examples, they show the distinctly bundled pattern of ribbing produced by radial furrows of several different orders of strength tending to subdivide the shell 

surface into regularly dichotomous ribs. They also show 

the characteristic tendency for the ribs to be broadly 

curved, convex in the anterior direction.

Figured specimens. Plesiotypes, USNM 248980 to 

248982.

Occurrence. USGS locality M970, Congress Canyon, 

northern Humboldt Range, Nev.

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Ablagerungen von Spiti und Gnari-Khorsum in Tibet: Palaontologische Mittheilungen Museum bayerischen Staates, v. 4, p.

267-304, pis. 75-88.

Popov, Yu. N., 1961, Triassic ammonoids of the northeastern zone of 

the U.S.S.R.: U.S.S.R. Scientific Research Institute on the 

Geology of Arctic Regions, Transactions, v. 79, p. 1-215. [in Russian] .

Rieber, Hans, 1968, Die Artengruppe der Daonella elongata Mojs. aus 

der Grenzbitumenzone der mittleren Trias des Monte San Giorgio 

(Kt. Tessen, Schweiz): Palaontologische Zeitschrift, v. 42, no. 1/2, 

p. 33-61, pis. 2-3.

 1969, Daonellan aus der Grenzbitumenzone der mittleren Trias 

des Monte San Giorgio (Kt. Tessin, Schweiz): Eclogae Geologicae 

Helvetiae, v. 62, no. 2, p. 657-683, pis. 1-4.

 1973, Cephalopoden aus der Grenzbitumenzone (Mittlere Trias) 

des Monte San Giorgio (KantonTessin, Schweiz): Schweizerische 

Palaontologische Abhandlungen, v. 93, p. 1-96, pis. 1-17.

Shevyrev, A. A., 1961, Ontogenetic development of some Anisian

ceratites of the Caucasus [trans. from Russian]: Paleontologischeskiy Zhurnal, no. 4, p. 71-85. 

Silberling, N. J., 1962, Stratigraphic distribution of Middle Triassic

ammonites at Fossil Hill, Humboldt Range, Nevada: Journal of

Paleontology, v. 36, no. 1, p. 153-160. 

Silberling, N. J., and Nichols, K. M., 1980, Phylogenetic patterns

among Middle Triassic ammonites: Revista Italiana di Paleontologia e Stratigrafia, v. 85, p. 737-740. 

Silberling, N. J., and Tozer, E. T., 1968, Biostratigraphic classification

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America Special Paper 110, 63 p.

Silberling, N. J., and Wallace, R. E., 1967, Geology of the Imlay 

quadrangle, Pershing County, Nevada: U.S. Geological Survey 

Geologic Quadrangle Map GQ-666, scale 1:62,500.

 1969, Stratigraphy of the Star Peak Group (Triassic) and overlying Lower Mesozoic rocks, Humboldt Range, Nevada: U.S. 

Geological Survey Professional Paper 592, 50 p.

Smith, J. P., 1904, The comparative stratigraphy of the marine Trias of 

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 1914, The Middle Triassic invertebrate faunas of North 

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pis.

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INDEX

[Italic page numbers indicate major references]

Acrochordiceras altemans ................................... 23

carolinae ............................................ 22; pi. 5

..................................................... 22

..................................................... 22

foltsense ...................................................... 23

haueri ......................................................... 22

hyatti .................................. 5, 21, 36; pis. 4, 5

zone ........................................................ 4

pustericum .................................................. 22

undatum ..................................................... 22

(Paracrochordiceras) americanum .................. 21

sp. ................................................................ 5

Acrochordiceratidae ............................................ 21

acutus, Anagymnites .......................................... 39

Gymnites (Anagymnites) .............................. 39

agenor, Ammonites (Ceratites) ............................ 60

Mojsvarites .................................................. 60

Monaphyllites .................................... 60; pi. 32

Atomies mulleri .................................. 5, 19; pi. 29

obesus ........................................... 5, 19; pi. 28

alexandrae, Epigymnites .............. 10, 40, 41; pi. 31

Gymnites ..................................................... 41

Alloptychites meeki ............................................ 42

sp. .............................................................. 42

Alps ................................................................. 11

altemans, Acrochordiceras .................................. 23

altilis, Ceratites ................................................. 30

Frechites ..................................................... 30

American Canyon .......................................... 16, 68

americana, Daonella ............... 41, 66, 67, 68; pi. 35

americanum, Acrochordiceras (Paracroehordiceras) . 21

Paracrochordiceras ......................... 4, 21; pi. 29

PrQtrachyceras ............................ 10, 31, 58, 68

Trachyceras ................................................. 38

Ammowites balfouri ........................................... 57

billingsianus ........................................... 59, 60

fctofcei .................................................... 25, 26

homfrayi .......................................... 58, 59, 61

spkaerophyllus ............................................. 60

wi<i ............................................................ 24

(Ceratites) agenor ........................................ 60

(Sageceras) zsigmondyi ................................. 51

Amphipopanoceras selwyni .................... 5, 20; pi. 6

amurensis, Pleuroceras (Ussurinautilus) .............. 62

Anagymnites acutus ........................................... 39

sp. .............................................................. 39

nnites) acutus, Gymnites ......................... 39

rosenbergi, Gymnites .................................... 54

nnotoceras moderatum ................. 5, 25; pi. 6

Anolcites fitrlongi .............................................. 38

Sra66i .......................................................... 38

sp. .............................................................. 36

(Anolcites) barberi, Trachyceras ............................ 7

furlongi, Trachyceras ................................... 38

Trachyceras ................................................. 38

gracile.Trachyceras ....................................... 37

%ofti, Trachyceras ...................................... 36

raeefci, Trachyceras ................................. 38, 59

Aptococeras avisianus ........................................ 53

pawts .......................................... 8, 53; pi. 22

smitfei ..................................... 8, 52, 53; pi. 21

vogdesi .................................... 8, 52, 53; pi. 22

sp. ......................................................... 52, 56

Aplococeratidae .............................................. 8, 52

applanatus, Ceratites ......................................... 30

Arcestes ausseanus ............................................ 57

gabbi ........................................................... 57

perplanus .................................................... 40

(Proarcestes) balfouri ................................... 57

bramantei .............................................. 57

gabbi .................................................... 57

hartzelli ................................................ 57

quadrilabiatus ........................................ 57

Arcestidae ..................................................... 9, 57

argentarius, Ceratites (Philippites) ...................... 26

Gymnotoceras .............................................. 26

Philippites ................................................... 26

Arizona Mine ................................................ 17, 68

Arpaditidae ........................................................ 59

arthaberi, Monophyllites ..................................... 60

Ussurites ....................................... 5, 60; pi. 32

asseretoi, Unionvillites .......................... 5, 45; pi. 6

Atractites bo'ckhi ................................................ 63

burckhardti .................................................. 65

clavatulus .............................. 9, 64; pis. 33, 34

elegans .............................................. 65; pi. 34

nevadensis ..................................... 9, 65; p. 34

solidus .......................................... 9, 65; pi. 34

sp. .............................................................. 63

sp. A............................................ 9, 64; pi. 33

sp. B ................................................ 64; pi. 33

sp. C ......................................... 64; pis. 33, 34

Augusta Mountain Formation ........... 3, 4, 10, 17, 60

Augusta Mountains . 15, 22, 34, 39, 45, 64; pis. 33, 34 

Aulametacoceras humboldtensis ............. 5, 61; pi. 31

mckeei ........................................................ 61

sp. .............................................................. 61

ausseanus, Arcestes ........................................... 57

Austria ............................................................. 11

avisianus, Aplococeras ....................................... 53

B

Ralatonites shoshonensis Zone .............................. 4

Balatonitidae ...................................................... 2$

balfouri, Ammonites .......................................... 57

Arcestes (Proarcestes) ................................... 57

Proarcestes ........................................ 57; pi. 27

barberi, Nevadites .............................................. 59

Trachyceras (Anolcites) .................................. 7

beckeri, Ceratites (Gymnotoceras) ........................ 27

Gymnotoceras .............................................. 28

beecheri, Ceratites ......................................... 32, 37

Relemnites nevadensis ........................................ 65

Beyrichites dunni ............................................... 28

falciformis ................................................... 26

osmonti ....................................................... 28

rotelliformis ................................................. 26

tenuis ......................................................... 26

sp. ................................................... 24, 25, 29

Beyrichitidae ........................................................ 8

Beyrichitinae ...................................................... 24

Big Canyon ............................................ 15, 19, 24

billingsianus, Ammonites .............................. 59, 60

Monophyllites .............................................. 60

Ussurites ..................................................... 60

bittneri, Enteropleura ......................................... 49

blakei, Ammonites ........................................ 25, 26

Ceratites (Gymnotoceras) ......................... 26, 27

Gymnotoceras ............. 8, 10, 26, 27, 28, 29, 34,

35, 40, 51, 52, 54, 57, 58, 64, 67; pi. 8

Bloody Canyon ............................. 4, 16, 20, 21, 43

bockhi, Atractites .............................................. &

bonaevistae, Cuccoceras ........................ 5, 23; pi. 20

bonae-vistae, Dinarites ....................................... 23

bramantei, Arcestes (Proarcestes) ........................ 57

breguzzanus, Longobardites ............................ 49, 51

breweri, Eutomoceras ......................................... 35

British Columbia .................................................. 4

Buchenstein beds ............................................... 11

Buena Vista Canyon ............... 4, 14, 23, 40, 68, 69;

pis. 7, 20, 30, 32 

burckhardti, Atractites ........................................ 65

Ceratites (Paraceratites) ............................... 31

Paraceratites ............................... 8, 10, 18, 26,

37,32,33, 34, 57; pi. 15

calli, Gymnites .............................................. 7, 41

Calliconites sp. .................................................. 66

campanile, Michelinoceras .................... 7, 63; pi. 33

Orthoceras ................................................... 63

Canada ......................................................... 4, 11

canadensis, Longobardites ................................... 48

carolinae, Acrochordiceras .................................. 22

caurus, Hungarites ............................................ 46

Lenotropites ....................................... 46; pi. 29

Celtites gabbi..................................................... 56

gemmellaroi................................................. 55

halli ...................................................... 44, 55

neumayri .................................................... 55

polygyratus ................................................. 56

(Paraceltites) halli ....................................... 55

Ceratites altilis .................................................. 30

applanatus .................................................. 30

freecfceri .................................................. 32, 37

comutus ...................................................... 29

crassicomu .................................................. 33

ecarinatus ................................................... 33

emmonsi ..................................................... 29

fissicostatus ................................................. 33

.................................................... 30

.................................................... 33

gren .................................................... 14

hayesi ......................................................... 43

humboldtensis .............................................. 29

karpinskyi ................................................... 30

fcin^t ........................................................... 33

meeki .......................................................... 27

nevadanus .............................................. 29, 30

occidentalis .................................................. 30

pilatus ........................................................ 30

rectangularis ............................................... 32

rotuloides ............................................... 29, 30

spinifer ....................................................... 29

tenuispiralis ................................................ 27

trinodosus ................................................... 59

vogdesi ........................................................ 33

witi............................................................ 24

ivashburnei .................................................. 27

weaveri ......................................................... 7

whitneyi ................................................. 38, 58

mlliamsi ..................................................... 28

(Gymnotoceras) beckeri ....................... 27; pi. 13

fctakei .............................................. 26, 27

hersheyi ................................................ 29

meeki .................................................... 27

73
74 INDEX

Page 

Ceratites Continued

(Gymnotoceras) beckeri Continued

russelli ....................................... 27; pi. 12

spurri ................................................... 30

wemplei ................................................ 27

(Hollandites) montis-bovis ........................ 25, 27

organi ........................................ 25, 27, 30

voiti ...................................................... 24

(Paraceratites) burckhardti ........................... 31

clarkei .................................................. 32

cricfei .................................................... 34

jrabfet ...................................................... 7

newberryi ......................................... 32, 33

taurus ................................................... 34

trinodosus ........................................ 32, 33

trojanus ................................................ 33

vogdesi .................................................. 33

wardi .................................................... 32

(Philippites) argentarius ............................... 26

lawsoni ................................................. 30

nawsorwei ............................................... 28

(Ceratites) agenor, Ammonites ............................ 60

Ceratitidae .................................................... 8, 24

clarkei, Ceratites (Paraceratites) ......................... 32

Paraceratites ........................... 7, 8, 10, 18, 26,

52, 33, 34, 37, 41; pi. 16 

clavatulus, Atractites ............................... 64; pi. 33

Clydonites laevidorsatus ................................ 44, 56

Columbites humboldtensis ................................... 56

plicatulus .................................................... 56

Comstock Lode .................................................... 1

Congress Canyon ................... 11, 15, 19, 25, 38, 69

Congress Canyon Formation ................................. 4

contractus, Nannites .......................................... 56

Thanamites ........................................ 56; pi. 6

cornutus, Ceratites ............................................. 29

Frechites ..................................................... 29

Cottonwood Canyon................. pis. 9, 12, 24, 25, 28

Cottonwood Mine ............................................... 16

Coyote Canyon ....................................... 16, 21, 24

crassicornu, Ceratites ......................................... 33

crassiplacata, Tropigastrites neumayri ................. 55

crassus, Lecanites .............................................. 53

crickl, Ceratites (Paraceratites) ........................... 34

Paraceratites ......................... 8, 10, 18, 26, 29,

32, Sit, 35, 39, 52, 57, 65; pi. 17 

Cuccoceras bonaevistae ......................... 5, 23; pi. 20

sp. ................................................................ 5

Czekanowskites hayesi .......................... 5, 43; pi. 19

D

Dagnoceratid ...................................................... 19

dalli, Eutomoceras ............................. 34, 35; pi. 18

(Halilucites) .......................................... 35

Dalmatites minutus ........................................... 50

parvus ........................................................ 50

damesi, Acrochordiceras ..................................... 22

Danubites halli ....................................... 44, 55, 56

Danubitidae ....................................................... 43

Daonella americana ................................. 9, 41, 66,

67, 68; pi. 35 

dubia .......................... 2, 9, 29, 31, 41, 59, 66,

68; pi. 36 

zone ........................................................ 2

elongata .................................. 9, 66, 67; pi. 36

fascicostata .................................................. 68

indica ......................................... 11, 69; pi. 38

lindstroemi .................................................. 68

lommeli ...................... 4, 11, 15, 38, 69; pi. 38

luganensis ................................................... 68

moussoni ............................... 9, 31, 41, 66, fiS;

pis. 36, 37 

pseudomoussoni ........................................... 68

rieberi ................................... 10, 58, 68; pi. 37

sturi ....................................... 9, 66, 67; pi. 35

laramellii .................................................... 68

vaceki ......................................................... 67

sp...................................................... 3, 11, ee

(Daonella) lommeli, Halobia .............................. 68

Page

desertorum, Dinarites ......................................... 52

Metadinarites ..................................... 52; pi. 21

Dinarites bonae-vistae ........................................ 23

desertoraw .................................................. 52

pygmaeus .................................................... 52

Dinaritidae ........................................................ 18

Dinaritinae ........................................................ 18

discoideus, Koipatoceras ........................ 5, iS; pi. 4

Discoptychites evansi .......................................... 41

sp. .......................................................... 7, 4J

dritarasktra, Pseudodanubites ............................. 44

drummondi, Isculites ......................................... 43

Smithoceras ............................................ 42, 43

dwbia, Daonella ..................... 2, 29, 31, 41, 59, 66,

68; pi. 36 

Halobia ....................................................... 68

dunni, Beyrichites .............................................. 28

Protrachyceras ............................................. 58

Bwtomoceras ...................................... 55; pi. 18

Gymnotoceras .............................................. 28

Parafrechites ......................... 8, 10, 18, 27, 2S,

31, 36, 41, 51, 53, 55, 57, 63, 67; pi. 13

E

ecarinatus, Ceratites .......................................... 33

ecki, Gymnites ................................................... 41

elegans, Atractites .............................................. 65

Trematoceras ............................................... 63

elongata, Daonella ............................. 66, 67; pi. 36

emmonsi, Ceratites ............................................ 29

Frechites ..................................................... 29

Enteropleura bittneri .......................................... 49

Eophyllites sp. .................................................... 5

Epigymnites alexandrae ........................... 9, 10, 40,

4.2; pi. 31 

Eudiscoceras gabbi ............................................... 7

Eutomoceras breweri .......................................... 35

daHi ....................................... 8, 34, 55; pi. 18

dunni ........................................... 8, 55; pi. 18

lahontanum ................................... 8, 54; pi. 18

laubei ........................................... 8, 55; pi. 19

(Halilucites) dalli ........................................ 35

evansi, Discoptychites ......................................... 41

Ptychites ................................................. 7, 41

extralabiatus, Proarcestes ................................... 58

falciformis, Beyrichites ....................................... 26

fascicostata, Daonella ......................................... 68

Favret Canyon ........................... 15, 64; pis. 33, 34

Favret Formation ................... 4, 22, 34, 39, 49, 64

fischeri, Acrochordiceras ..................................... 22

Fisher Canyon ........................................ 11, 17, 69

fissicostatus, Ceratites ........................................ 33

fittingensis, Hungarites ...................................... 35

fontainei, Nevadites ...................................... 32, 37

foltsense, Acrochordiceras ................................... 23

Fossil Hill Member, Favret Formation . 3, 7, 15, 22, 49 

Frechites altilis ................................................. 30

cornutus ...................................................... 29

emmonsi ..................................................... 29

humboldtensis .............................................. 29

johnstoni ............................... 10, 31, 58; pi. 15

karpinskyi ................................................... 30

nevadanus .......................... 5, 7, 8, 10, 26, 29,

35, 54, 65, 67; pis. 9, 10, 11 

occidentalis ............................ 8, 25, 27, 29, 30;

pis. 13, 14 

zone .................................................... 4, 8

pilatus ........................................................ 30

rotuloides .................................................... 30

spinifer ....................................................... 29

tenuispiralis ................................................ 27

sp. ................................................... 25, 27, 29

(Frechites) nevadanus, Gymnotoceras .................. 29

furlongi, Anolcites ............................................. 38

Germanonautilus ............................ 7, ft2; pi. 32

Page

Furlongi-Contimied

Nevadites .......................... 8, 10, 38, 66; pi 24

Trachyceras (Anolcites) ................................ 38

G

aabbi, Anolcites ................................................. 38

Arcestes ...................................................... 57

Arcestes (Proarcestes) ................................... 57

CeMifes ....................................................... 56

Ceratites (Paraceratites) ................................. 7

Eudiscoceras .................................................. 7

Nevadites .................................... 8, 10, 31, 5S,

59; pi. 24 

Proarcestes ........................................ 57; pi. 27

Sageceras ...................................... 14, 18; pi. 4

Trachyceras (Anolcites) ................................ 38

gemmellaroi, Celtites .......................................... 55

Tozerites ..................................... 54, 55; pi. 27

Tropigastrites .......................................... 39, 44

Germanonautilus furlongi .............................. 7, S2;

pi. 32 

Gilbert Creek Quadrangle ................................... 15

ailberti, Ceratites ............................................... 30

Goniatites haidingeri .......................................... 14

laevidorsatus ............................................... 56

oracile, Trachyceras (Anolcites) .......................... 37

Greece .............................................................. 11

{Jrenzbitumenzone ............................................... 11

Groenlanditinae .................................................. 46

orumulus, Neodalmatites .................................... 50

Grypoceras whitneyi .................................. 5, 7, 62;

pi. 32 

Grypoceratidae ................................................... 62

Gymnites alexandrae .......................................... 41

caih' ........................................................ 7, 4i

ecfei ............................................................ 41

humboldti ...................................... 9, 40; pi. 31

incultus ...................................................... 40

perplanus ...................................... 5, 40; pi. 30

sankara ...................................................... 40

tregorum ....................................... 4, 59; pi. 31

volzi ........................................................... 40

(Anagymnites) acutus .................................. 39

rosenbergi .............................................. 54

sp. .......................................................... 5, 41

Gymnitidae .................................................... 9, 39

Gymnotoceras argentarius ................................... 26

beckeri ........................................................ 28

blakei ............................. 8, 10, 2fi, 27, 28, 29,

34, 35, 40, 51, 52, 54, 57, 58, 64, 67; pis. 8, 9 

dunni ......................................................... 28

meeki..................................................... 27, 28

moderatum .................................................. 25

occidentalis .................................................. 30

rotelliformis ................................. 8, 14, 26, 29,

34; pi. 7 

zone .................................................... 4, 8

russelli .................................................. 27, 28

uxishburnei ............................................. 27, 30

wemplei ...................................................... 27

(Frechites) nevadanus .................................. 29

sp. ............................................. 25, 27, 29, 31

(Gymnotoceras) beckeri, Ceratites ........................ 27

blakei, Ceratites ...................................... 26, 27

hersheyi, Ceratites ....................................... 29

meeki, Ceratites ........................................... 27

russelli, Ceratites ......................................... 27

spurri, Ceratites .......................................... 30

wemplei, Ceratites ........................................ 27

H

hadleyi, UnionvilUtes .................................... 5, 39,

45; pi. 6 

haguei, Ceratites ................................................ 33

haidingeri, Ceratites ........................................... 14

Goniatites .................................................... 14

haidingerii, Sageceras ......................................... 18

Halilucites sp. ................................................... 35

(Halilucites) dalli, Eutomoceras .......................... 35

halli, Celtites ^.^..^.....^............................... 44, 55

(Paraceltites) ......................................... 55
INDEX 75

halli Continued

Danubites ......................................... 44, 55, 56

Pseudodanubites ................................. 5, 44, 54,

55; pi. 19 

Tropigastrites .................................... 44, 54, 55

Hallstatt Facies, Greece ..................................... 11

Halobia dubia ................................................... 68

sturi ........................................................... 67

(Daonella) lommeli ...................................... 68

hartzelli, Arcestes (Proarcestes) ........................... 57

hatschekii, Haydenites ........................................ 22

haueri, Acrochordiceras ...................................... 22

hauerinus, Isculites ............................................ 42

Haydenites hatschekii ......................................... 22

hayesi, Ceratites ................................................ 43

Czekanowskites, ........................................ 5, 43

hersheyi, Ceratites (Gymnotoceras) ...................... 29

History ............................................................... 1

Hollandites voiti ................................... 5, 24; pi. 6

sp. .............................................................. 24

(Hollandites) montis-bovis, Ceratites ............... 25, 27

organi, Ceratites ............................... 25, 27, 30

voiti, Ceratites ............................................. 24

homfrayi, Ammonites .............................. 58, 59, 61

Sirenites ............................................ 59; pi. 25

Trachyceras (Paratrachyceras) ...................... 59

humboldtemis, Aulametacoceras ..................... 5, 6.Z;

pi. 31 

Ceratites ..................................................... 29

Columbites .................................................. 56

Frechites ..................................................... 29

Nevadites .......................... 7, 8, 10, 37, 56, 57;

pi. 23 

Tozerites ..................................... 55, 56; pi. 27

humboldti, Gymnites ................................ 40; pi. 31

Humboldtites septentrionalis .......................... 9, 21;

pi. 28 

Hungarites caurus ............................................. 46

fittingensis .................................................. 35

pradoi ......................................................... 39

sp. .............................................. 11, 3#; pi. 20

Hungaritidae ...................................................... 38

hyatti, Acrochordiceras ............................. 5, 21, 36;

pis. 4, 5 

Longobardites .............................................. 50

Nevadites .......................... 8, 10, 36, 56; pi. 22

Trachyceras (Anoleites) ................................ 36

I

Imlay Quadrangle ............................................... 16

iticultus, Gymnites ............................................. 40

Indian Creek ..................................................... 15

indica^Daonella ................................. 11, 69; pi. 38

intornatus, Intornites ......................................... 49

Longobardites .............................................. 48

(Intornatus) nevadanus, Longobardites ................ 48

Intornites intornatus .......................................... 49

mctaggarti ............................. 5, 46, 47, 48, 49;

pi. 20 

nevadanus ............................. 5, 46, 47, 4#, 49,

50, 51; pi. 21 

sp. .......................................................... 5, 49

Isculites drummondi .......................................... 43

hauerinus .................................................... 42

meeki ..................................... 4, 42; pis. 28, 29

tozeri ............................................ 5, 43; pi. 30

sp. .......................................................... 5, Jt"2

Isculitidae .......................................................... £2

Ismidites rnarmarensis .................................. 5, £0;

pi. 28 

sp. .............................................................. 19

Italy ................................................................. 41

Jackson Canyon ................................................. 15

japonica, Sturia ....................................... 41; pi. 30

Japonites louderbacki ......................................... 54

sugriva ................................................... 5, 39

Page 

Japonitidae .................................................... 9, 39

John Brown Canyon ........................................... 16

johnstoni, Frechites ................................ 10, 31, 58;

pi. 15 

judicaricum, Trachyceras .................................... 58

subasperum, Trachyceras .............................. 58

K

karpinskyi, Ceratites .......................................... 30

Frechites ..................................................... 30

Keyserlingites subrobustus zone ............................. 4

kharaulakhensis, Neodalmatites ........................... 50

Khvalynitinae ..................................................... 19

kingi, Ceratites .................................................. 33

Koipatoceras discoideus ................................. 5, .ZS;

pi. 4

laevidorsatus, Clydonites ............................... 44, 56

Goniatites .................................................... 56

lahontanum, Eutomoceras ........................ 34; pi. 18

Protrachyceras ........................................ 10, 58

lahontanus, Tropigastrites ............................. 54, 55;

pj.26 

larvalis, Longobardites ....................................... 48

laubei, Eutomoceras ................................. 35; pi. 19

lawsoni, Ceratites (Philippites) ........................... 30

Lecanites crassus ............................................... 53

nwdits .................................................... 52, 53

parvus ........................................................ 53

vogdesi ........................................................ 53

T*eiophyllites sp. ................................................ 39

T-enotropites caurus .................................. 46; pi. 29

zone ........................................................ 4

lindstroemi, Daonella ......................................... 68

Liroceratidae ..................................................... 62

lommeli, Daonella ....................... 4, 11, 15, 38, 69;

pi. 38 

Halobia (Daonella) ...................................... 68

Longobardites breguzzanus ............................. 49, 51

canadensis ................................................... 48

fcyotti .......................................................... 50

intornatus ................................................... 48

larvalis ....................................................... 48

mctaggarti ................................................... 48

nevadanus ........................................ 48, 50, 51

parwts ............................ 8, 46, 47, 48, 49, 50,

51; pi. 21 

zsigmondyi ............................ 8, 46, 47, 48, 50,

51; pi 21 

(Intornatus) nevadanus ................................ 48

sp. ............................................. 14, 46, 49, 51

Longobarditidae ............................................. 8, 46

Longobarditinae ................................................. 46

louderbacki, Japonites ........................................ 54

Sibyllites ..................................................... 54

Tropigastrites ..................................... 54; pi. 26

luganensis, Daonella .......................................... 68

M

marmarensis, Ismidites ........................ 5, 20; pi. 28

mckeei, Aulametacoceras .................................... 61

mctaggarti, Intornites ......................... 5, 46, 47, 48,

49; pi. 20 

Longobardites .............................................. 48

meeki, Alloptychites ........................................... 42

Cerates ..................................................... 27

(Gymnotoceras) ...................................... 27

Gymnotoceras ......................................... 27, 28

Isculites ........................................ 4, 42; pi. 28

Parafrechites ............... 7, 8, 10, 18, 25, 26, 27,

29, 31, 35, 51, 55, 57, 63, 65; pi. 11 

Protrachyceras .................................. 10, 58, 68

Ptychites ..................................................... 42

Trachyceras (Anoleites) ........................... 38, 59

Megaphyllites, septentrionalis .............................. 21

Megaphyllitidae .............................................. 9, 21

Page

meginae, Meginoceras ......................................... 11

Meginoceras meginae .......................................... 11

merriami, Nevadites ........................................... 36

Metaeoceras sp. ................................................. 61

Metadinarites desertorus ....................... 8, 52; pi. 21

sp. .............................................................. 52

Michelinoceras campanile ..................... 7, 63; pi. 33

sp. .............................................................. 63

minutus, Dalmatites .......................................... 50

Neodalmatites .............................................. 50

moderatum, Anagymnotoceras ................ 5, 25; pi. 6

Gymnotoceras .............................................. 25

Mojsvarites agenor ............................................. 60

Mojsvaroceras sp. .............................................. 62

Monophyllites agenor ............................... 60; pi. 32

arthaberi ..................................................... 60

billingsianus ................................................ 60

sphaerophyllus ............................................. 60

sp. .............................................................. 59

montis-bovis, Ceratites (Hollandites) ............... 25, 27

moussoni, Daonella ................. 31, 41, 66, 6S; pi. 36

Posidonomya ............................................... 68

mulleri Alanites .................................. 5, 19; pi. 29

multicameratus, Nautilus ................................... 63

Paranautilus ............................................... 62

N

Nannites contractus ........................................... 56

sp. .............................................................. 57

Nautilus multicameratus .................................... 63

rectangularis ............................................... 61

whitneyi ...................................................... 62

Neodalmatites grumulus ..................................... 50

kharaulakhensis ........................................... 50

minutus ...................................................... 50

parvus ........................................................ 50

sp. .............................................................. 50

Neodalmatitinae ................................................. 50

Neopopanoceras haugi zone .................................. 4

sp. .............................................................. 21

neumayri, Celtites ............................................. 55

Tropigastrites .......................................... 54, 55

crassiplacata, Tropigastrites .......................... 55

Nevadites barberi ............................................... 59

fontainei ................................................ 32, 37

furlongi ............................. 8, 10, 3S, 66; pi. 24

ffafeM .......................... 8, 10, 31, 3#, 59; pi. 24

humboldtensis .................... 7, 8, 10, 37, 56, 57;

pis. 23, 24 

hyatti ......................... 8, 10, 36, 56; pis. 22, 23

merriami ..................................................... 36

sinclairi ...................................................... 37

whitneyi ...................................................... 37

sp. ........................................ 21, 36, 54, 58, 65

nevadanus, Ceratites ..................................... 29, 30

Frechites ............................ 5, 7, 8, 10, 26, 29,

35, 54, 65, 67; pi. 9 

Gymnotoceras (Frechites) .............................. 29

Intornites .................................... 5, 46, 47, 48,

49, 50, 51; pi. 21 

Longobardites ................................... 48, 50, 51

(Intornatus) ........................................... 48

Parafrechites .......................................... 51, 57

nevadensis, Atractites ............................... 65; pi. 34

Belemnites ................................................... 65

New Pass Range . 11, 22, 23, 36, 46, 49; pis. 4, 5, 19 

newberryi, Ceratites (Paraceratites) ................ 32, 33

Nicomedites sp. .................................... 5, 24; pi. 6

nudus, Lecanites ........................................... 52, 53

Pseudoplococeras .......................................... 52

0

obesus, Alanites ................................... 5, 19; pi. 28

Pteria ........................................... 7, 66; pi. 38

Rhynchopterus ............................................. 66

obliterans, Tropigastrites .................................... 54

occidentalis, Ceratites ......................................... 30

Frechites .......................... 25, 27, 29, 30; pi. 13

Gymnotoceras .............................................. 30
76 INDEX

Page 

orgcmi, Ceratites (Holkmdites) ................. 25, 27, 30

Orthoceras campanile ......................................... 63

Orthoceratidae ................................................... 63

osmonti, Beyrichites ........................................... 28

P,Q

Panther Canyon Member,

Augusta Mountain Formation ................ 4, 10

(Pamceltites) halli, Celtites ................................ 55

Paraceratites burckhardti .................... 8, 10, 18, 26,

31, 32, 33, 34, 57; pi. 15 

clarkei .............................. 7, 8, 10, 18, 26, 32,

33, 34, 37, 41; pi. 16 

cricfcj ......................... 8, 10, 18, 26, 29, 32, 34,

35, 39, 52, 57, 65; pi. 17 

trinodosus ................................................... 33

trojanus ...................................................... 33

vogdesi ....................... 8, 10, 14, 15, 18, 26, 32,

33, 34, 66; pis. 16, 17 

sp. ......................................................... 34, 37

(Paraceratites) burckhardti, Ceratites ................... 31

clarkei, Ceratites ......................................... 32

cricki, Ceratites ........................................... 34

gabbi, Ceratites .............................................. 7

newberryi, Ceratites ................................ 32, 33

taurus, Ceratites .......................................... 34

trinodosus, Ceratites ............................... 32, 33

trojanus, Ceratites ....................................... 33

vogdesi, Ceratites ......................................... 33

wardi, Ceratites ........................................... 32

Paraceratitinae ................................................... 31

Paracrochordiceras americanum ..................... 4, 21;

pi. 29

(Paracrochordiceras) americanum, Acrochordiceras . 21 

Parafrechites dunni ...................... 8, 10, 18, 27, 28,

31, 36, 41, 51, 53, 55, 57, 63, 67; pi. 13 

meeki ..................... 7, 8, 10, 18, 25, 26, 27, 29,

31, 35, 51, 55, 57, 63, 65; pis. 11, 12, 13 

zone .................................................... 4, 8

nevadanus .............................................. 51, 57

sp. ................................................... 25, 27, 29

Paranautilus, multicamemtus ............................. 62

smithi ........................................... 7, 62; pi. 32

Parapopanoceras selwyni .................................... 20

testa ........................................................... 20

sp. .............................................................. 21

Parapopanoceratidae ........................................... 20

Paratrachyceras sp. ........................................... 59

(Paratrachyceras) homfrayi, Trachyceras ............. 59

parvus, Aplococeras ................................. 53; pi. 22

Dalmatites ................................................... 50

Lecanites ..................................................... 53

Longobardites ............................ 46, 47, 48, 49,

50, 51; pi. 21 

Neodalmatites .............................................. 50

Pseudaplococeras .......................................... 53

perplanus, Arcestes ............................................ 40

Gymnites ....................................... 5, 40; pi. 30

Peru Canyon ..................................................... 15

Philippites argentarius ....................................... 26

sp. .............................................................. 25

(Philippites) argentarius, Ceratites ...................... 26

lawsoni, Ceratites ........................................ 30

ransomei, Ceratites ...................................... 28

pilatus, Ceratites ............................................... 30

Frechites ..................................................... 30

planorbis, Sibyllites ........................................... 39

Tropigymnites .................................... 39; pi. 26

Pleuroceras (Ussurinautilus) amurensis ............... 62

plicatulus, Columbites ........................................ 56

polygyratus, Celtites ........................................... 56

Tozerites ..................................... 55, 56; pi. 27

Posidonia sp. ...................................................... 5

Posidoniidae ................................................... 9, 66

Posidonomya moussoni ...................................... 68

pawelli, Tropigastrites ........................................ 54

pradoi, Hungarites ............................................. 39

Page

Proarcestes balfouri ............................. 9, 57; pi. 27

extralabiatus ................................................ 58

gabbi ..................................... 9, 57; pis. 27, 28

sp. ......................................................... 11, 39

(Proarcestes) balfouri, Arcestes ........................... 57

bramantei, Arcestes ...................................... 57

gabbi, Arcestes ............................................ 57

hartzelli, Arcestes ........................................ 57

quadrilabiatus, Arcestes ................................ 57

Prohungarites sp. .............................................. 18

Proteusitidae .................................................. 9, 54

Protrachyceras americanum ..... 10, 31, 58, 68; pi. 25

archelaus zone ............................................. 51

dunni ................................... .. 58

lahontanum ............................................ 10, 58

meeki .................................... 10, 58, 68; pi. 24

reitzi ...................................................... 11, 51

sikanianum ................................................. H

springeri . . ....................................... 58

subasperum ........................... 10, 31, 58; pi. 24

zone ........................................................ 4

sp. .................................. 10, 11, 36, 39, 58, 59

Pseudaplococeras vogdesi .......................... 53; pi. 22

Pseudodanubites dritarashtra .............................. 44

halli ................................. 5, 44, 54, 55; pi. 19

sp. ......................................................... 44, 56

pseudomoussoni, Daonella ..........................

Pseudaplococeras nudus ..................................... 52

parvus 53

sp.

Pteria obesus ............................ -. . 1, S6; pi.

sp. 66

Pteriidae .......................................-- 66

Ptychites evansi ............................................. 7, 41

meeki ........................................... 42

sp. ...............................-........- - . 7

pustericum, Acrochordiceras ................................ 22

pygmaeus, Dinarites .......................................... 52

Q

quadrilabiatus, Arcestes (Proarcestes) .................. 57

R 

ransomei, Ceratites (Philippites) ......................... 28

rectangularis, Ceratites ...................................... 32

Nautilus ............................. - 61

reitzi, Protrachyceras .................................... H, 51

Khynchopterus obesus ....,................... . 66

sp. .............................................................. 66

rieberi, Daonella .................................... 10, 58, 68;

pi. 37 

rosenbergi, Gymnites (Anagymnites) .................... 54

rotelliformis, Beyrichites ....................... .- 26

Gymnotoceras ............................. 14, 26, 29, 34;

pi. 7 

rothpletzi, Tropigastrites ................................ 54, 55

rotuloides, Ceratites .............................. 29, 30

Frechites ............................. . 30

russelli, Ceratites (Gymnotoceras) ....................... 27

Gymnotoceras .......................... . . 27, 28

S

Sageceras gabbi ................................... 14, 18; pi. 4

haidingerii................................................... 18

wafteri ........................................... 8, 1#; pi. 5

(Sageceras) zsigmondyi, Ammonites .................... 51

Sagerceratidae ............................................... 8, 14

sankara, Gymnites ............................................. 40

sansovinii, Sturia .......................................... 7, 41

schoolerensis, Thanamites ................................... 11

selwyni, Amphipopanoceras ........................... 5, 20;

pi. 6 

Parapopanoceras .......................................... 20

septentrionalis, Humboldtites .............................. 21;

pi. 28 

Megaphyllites ............................................... 21

Page 

Sheba Mine ....................................................... 17

Siberia ................................................................ 4

Sibyllites louderbacki ......................................... 54

planorbis ..................................................... 39

sikanianum, Protrachyceras ................................ 11

Silver deposits ..................................................... 1

sinclairi, Nevadites ............................................ 37

Sirenites homfrayi ................................... 59; pi. 25

senticosus .................................................... 59

sp. ......................................................... 58, 59

Sirenitinae ......................................................... 59

Smelser Pass Member,

Augusta Mountain Formation ................ 4, 60

smithi, Aplococeras ............................ 52, 53; pi. 21

Paranautilus ................................. 7, 62; pi. 32

Smithoceras drummondi ................................ 42, 43

sp. .............................................................. 42

solidus, Atractites .................................... 65; pi. 34

South American Canyon ................................. 2, 15

Sphaera whitneyi ................................................. 5

spinifer, Ceratites .............................................. 29

Frechites ..................................................... 29

Spirigera stoliczaki .............................................. 5

Spitisculites sp. ................................................. 42

sphaerophyllus, Ammonites ................................. 60

Monophyllites .............................................. 60

springeri, Protrachyceras .................................... 58

spurri, Ceratites (Gymnotoceras) ......................... 30

Stacheites sp. .................................................... 18

Star Canyon ....... 1, 4, 14, 16, 23, 42; pis. 9, 28, 36

Star City ............................................................ 1

Star Peak ........................................... 3, 4, 16, 39

stoliczaki, Spirigera ............................................. 5

stun, Daonella .................................. 66, 67; pi. 35

Halobia ....................................................... 67

Sturia japonica ........................................ 41; pi. 30

sansovinii ................................................ 7, 41

Sturiidae ........................................................... 4!

sugriva, Japonites .......................................... 5, 39

subasperum, Protrachyceras ..................... 10, 31, 58

Trachyceras judicaricum ............................... 58

Subcolumbites sp. .............................................. 18

Summary ............................................................. 1

Switzerland ........................................................ 11

Tainoceratidae .................................................... 61

taramellii, Daonella ........................................... 68

taurus, Ceratites (Paraceratites) .......................... 34

tenuis, Beyrichites ............................................. 26

tenuispiralis, Ceratites ....................................... 27

Frechites ..................................................... 27

testa, Parapopanoceras ....................................... 20

Thanamites contractus ........................... 9, 56; pi. 6

schoolerensis ................................................ 11

sp. .............................................................. 56

Thanamitidae ................................................. 9, 57

Tobin Range ....................................... 4, 7, 22, 45

tozeri, Isculites .................................... 5, 43; pi. 30

Tozerites gemmellaroi ............................... 9, 54, 55;

pi. 27

humboldtensis .......................... 9, 55, 56; pi. 27

polygyratus ............................. 9, 55, 56; pi. 27

sp. .............................................................. 54

Trachyceras americanum .................................... 38

judicaricum ................................................. 58

subasperum ........................................... 58

(Anolcites) barberi ......................................... 7

furlongi ................................................. 38

gracile .................................................. 37

ffa&b? .................................................... 38

fa/atti .................................................... 36

meefci............................................... 38, 59

(Paratrachyceras) homfrayi ........................... 59

tregorum, Gymnites ............................. 4, 39; pi. 31

Trematoceras elegans ......................................... 63

sp. .............................................................. 63
INDEX 77

Page

trinodosus, Ceratites .......................................... 59

(Paraeeratites) .................................. 32, 33

Paracemtites ............................................... 33

trojanus, Ceratites (Paraeeratites) ....................... 33

Paraeeratites ............................................... 33

Tropigastris ................................................. 54

Tropigastrites gemmellaroi ............................. 39, 44

halli ................................................ 44, 54, 55

lakontanus .............................. 9, 54, 55; pi. 26

louderbacki .................................... 9, 54; pi. 26

newmayri ............................................... 54, 55

crassiplicata .......................................... 55

obliterans .................................................... 54

powelli ........................................................ 54

rothpletzi ................................................ 54, 55

trojanus ._................................................... 54

sp. ........................................ 39, 44, 54, 55, 56

Tropigymnites planarbis ....................... 9, 39; pi. 26

sp. ......................................................... 34, 39

Troy Canyon ..................................................... 15

Turkey .............................................................. 11

U

undatum, Acrochordiceras .................................. 22

Page

Unionville ...................................... 1, 39; pis. 6, 20

Unionvillites asseretoi ........................... 5, 45; pi. 6

kadleyi ..................................... 5, 39, 45; pi. 6

sp. .............................................................. 45

Ussurites arthaberi .............................. 5, 60; pi. 32

billingsianus ................................................ 60

sp. .............................................................. 60

Ussuritidae ........................................................ 60

(Ussurinautilus) amurensis, Pleuroceras .............. 62

vaceki, Daonella ................................................ 67

vogdesi, Aplococeras ........................... 52, 53; pi. 22

Ceratites ..................................................... 33

(Paraeeratites) ....................................... 33

Lecanites ..................................................... 53

Paraeeratites .............. S, 10, 14, 15, 18, 26, 32,

33, 34, 66; pi. 16 

Pseudaplococeras ................................ 53; pi. 22

voiti, Ammonites ............................................... 24

Ceratites ..................................................... 24

(Hollandites) ......................................... 24

Hollandites ..................................... 5, £4; pi. 6

i>o/zi, Gymnites ................................................. 40

W

ivalteri, Sageceras ..................................... 18; pi. 5

wardi, Ceratites (Paraeeratites) ........................... 32

washburnei, Ceratites ......................................... 27

Gymnotoceras ......................................... 27, 30

wemplei, Ceratites (Gymnotoceras) ...................... 27

Gymnotoceras .............................................. 27

Wheeler Mine .................................................... 16

whitneyi, Ceratites ........................................ 38, 58

Grypoceras ............................... 5, 7, 62; pi. 32

Nevadites .................................................... 37

Sphaera ........................................................ 5

Wildhorse mining district .................................... 49

wilHamsi, Ceratites ............................................ 28

X, Y, Z

Xiphoteuthididae ............................................ 9, 63

zsigmondyi, Ammonites (Sageceras) .................... 51

Longobardites ....................... 46, 47, 48, 50, 51;

pi. 21

PLATES 4-38

[Contact photographs of the plates in this report are available, at cost, from U.S. Geological Survey Library, Federal Center,

Denver, Colorado 80225]
PLATE 4

[All figures natural size unless otherwise indicated]

FIGURES 1-2. Sageceras gabbi Mojsisovics (p. 14). Lectotype, ANSP 30783, Humboldt Range, Nev.; stratigraphic occurrence

unknown. 

3-10. Koipatoceras discoideus n. sp. (p. 18). Hyatti Zone.

3-4. Paratype, USNM 248629, USGS Mesozoic loc. M1184, X 2. 

5-6. Paratype, USNM 248630, USGS Mesozoic loc. M1184.

7. Same as figure 6, X 2.

8-10. Holotype, USNM 248631, USGS Mesozoic loc. M1180. 

11-28. Acrochordiceras hyatti Meek (p. 21). Hyatti Zone, unless otherwise indicated. 

11-13. Plesiotype, USNM 248632, USGS loc. M533. 

14-16. Plesiotype, USNM 248633, USGS loc. M533. 

17-19. Plesiotype, USNM 248634, USGS loc. M533. 

20-21. Plesiotype, USNM 248635, USGS Mesozoic loc. M1180. 

22-23. Plesiotype, USNM 248636, USGS Mesozoic loc. Ml 184. 

24-26. Plesiotype, USNM 248637, USGS Mesozoic loc. M2821. 

27-28. Lectotype, USNM 12514, probably from New Pass Range, Nev.; stratigraphic occurrence unknown.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 4

SAGECERAS, KOIPATOCERAS, AND ACROCHORDICERAS
PLATE 5

[All figures natural size unless otherwise indicated]

FIGURES 1-7. Acrochordiceras hyatti Meek (p. 21). Plesiotypes, Hyatti Zone. 

1-3. USNM 248638, USGS loc. M533. 

4-5. USNM 248639, USGS loc. M970, X V2 . 

6-7. USNM 248640, USGS Mesozoic loc. M1180. 

8-9. Acrochordiceras cf. A. carolinae Mojsisovics (p. 23).

Plesiotype, USNM 12514, New Pass Range, Nev.; stratigraphic occurrence unknown. 

10-12. Sageceras walteri Mojsisovics (p. 18). Rotelliformis Zone. 

10-11. Plesiotype, USNM 248641, USGS loc. M139. 

12. Same as figure 11, showing suture, X 2.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 5

9 I IU 11

ACROCHORDICERAS AND SAGECERAS

12
PLATE 6

[All figures natural size unless otherwise indicated]

FIGURES 1-6. Hollandites voiti (Oppel) (p. 24). Plesiotypes, USGS loc. M969, Hyatti Zone. 

1-2. USNM 248642. 

3-5. USNM 248643. 

6. USNM 248644. 

7-8. ?Anagymnotoceras moderatum (McLearn) (p. 25). Plesiotype, USNM 248645, USGS Mesozoic loc. M2822,

Hyatti Zone. 

9-11. Nicomedites sp. (p. 24).

USNM 248646, USGS loc. M533, Hyatti Zone.

12-14. Thanamites? contractus (Smith) (p. 56). Plesiotype, USNM 248647, USGS loc. M144, Occidentalis Zone, X 2. 

15-16. Amphipopanoceras cf. A. sehoyni (McLearn) (p. 20). Plesiotype, USNM 248648, USGS Mesozoic loc. M2829,

Hyatti Zone. 

17-23. Unionvillites hadleyi (Smith) (p. 45). Hyatti Zone.

17-18. Plesiotype, USNM 248649, USGS Mesozoic loc. M2829. Specimen is partly a plaster cast from an external mold.

19-20. Plesiotype, USNM 248650, USGS Mesozoic loc. M1181. 

21-23. Holotype, USNM 74432, from near Unionville, Humboldt Range, Nev. 

24-28. Unionvillites asseretoi n. sp. (p. 45). USGS Mesozoic loc. M2829, Hyatti Zone. 

24-25. Paratype, USNM 248651. 

26. Paratype, USNM 248652. 

27-28. Holotype, USNM 248653.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 6

28

HOLLANDITES, ?ANAGYMNOTOCERAS, NICOMEDITES, THANAMITES?, 

AMPHIPOPANOCERAS AND UNIONVILLITES
PLATE 7

[All figures natural size]

FIGURES 1-27. Gymnotoceras rotelliformis Meek (p. 26), Rotelliformis Zone.

1-3. Holotype, USNM 12516, "Buena Vista Canyon, Humboldt Range, Nevada" (Meek, 1877).

4-5. Plesiotype, USNM 248654, USGS loc. M136.

6-8. Plesiotype, USNM 248655, USGS loc. M136. 

9-10. Plesiotype, USNM 248656, USGS loc. M136. 

11-12. Plesiotype, USNM 248657, USGS loc. M136. 

13-14. Plesiotype, USNM 248658, USGS loc. M136. 

15-16. Plesiotype, USNM 248659, USGS loc. M136. 

17-19. Plesiotype, USNM 248660, USGS loc. M136. 

20-21. Plesiotype, USNM 248661, USGS loc. M136. 

22-24. Plesiotype, USNM 248662, USGS loc. M136. 

25-27. Plesiotype, USNM 248663, USGS loc. M136.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 7

23 27

GYMNOTOCERAS
PLATE 8

[All figures natural size]

FIGURES 1-5. Gymnotoceras rotettiformis Meek (p. 26). Plesiotypes, USGS loc. M165, Rotelliformis Zone. 

1-2. USNM 248664. 

3-5. USNM 248665.

6-19. Gymnotoceras blakei (Gabb) (p. 26). Plesiotypes, Rotelliformis Zone.

6-8. USNM 248666, USGS loc. M141.

9-10. USNM 248667, USGS loc. M141.

11-12. USNM 248668, USGS loc. M611

13-14. USNM 248669, USGS loc. M611.

15-17. USNM 248670, USGS loc. M611.

18-19. USNM 248671, USGS loc. M611.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE

GYMNOTOCERAS
PLATE 9

[All figures natural size]

FIGURES 1-18. Gymnotoceras blakei (Gabb) (p. 26). Rotelliformis Zone.

1-3. Holotype, ANSP 1227, near Star Canyon, Humboldt Range, Nev.

4-5. Plesiotype, USNM 248672, USGS loc. M964.

6-7. Plesiotype, USNM 248673, USGS loc. M964.

8-9. Plesiotype, USNM 248674, USGS loc. M964. 

10-12. Plesiotype, USNM 248675, USGS loc. M964. 

13-14. Plesiotype, USNM 248676, USGS loc. M608. 

15-16. Plesiotype, USNM 248677, USGS loc. M608. 

17-18. Plesiotype, USNM 248678, USGS loc. M608. 

19-25. Frechites nevadanus (Mojsisovics) (p. 29). Meeki Zone.

19-20. Holotype, USNM 12512, Cottonwood Canyon, Humboldt Range, Nev. 

21-23. Plesiotype, USNM 248679, USGS loc. M615. 

24-25. Plesiotype, USNM 248680, USGS loc. M615.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 9

22 ' 23

GYMNOTOCERAS AND FRECHITES
PLATE 10

[All figures natural size]

FIGURES 1-24. Frechites nevadanus (Mojsisovics) (p. 29). Plesiotypes, USGS loc. M166, Meeki Zone.

1-3. USNM 248681.

4-5. USNM 248682.

6-7. USNM 248683.

8-9. USNM 248684. 

10-12. USNM 248685. 

13-15. USNM 248686. 

16-18. USNM 248687. 

19-20. USNM 248688. 

21-22. USNM 248689. 

23-24. USNM 248690.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 10

23 

FRECHITES
PLATE 11

[All figures natural size]

FIGURES 1-6. Frechites nevadanus (Mojsisovics) (p. 29). Plesiotypes, USGS loc. M164, Meeki Zone.

I-2. USNM 248691. 

3-4. USNM 248692. 

5-6. USNM 248693. 

7-23. Parafrechites meeki (Mojsisovics) (p. 27). Plesiotypes, Meeki Zone.

7-8. USNM 248694, USGS loc. M958. 

9-10. USNM 248695, USGS loc. M958.

II-12. USNM 248696, USGS loc. M143. 

13-15. USNM 248697, USGS loc. M143. 

16-17. USNM 248698, USGS loc. M143. 

18-20. USNM 248699, USGS loc. M143. 

21-23. USNM 248700, USGS loc. M143.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 1207 PLATE 11

19 20 

FRECHITES AND PARAFRECHITES

23
PLATE 12

[All figures natural size]

FIGURES 1-29. Parafrechites meeki (Mojsisovics) (p. 27). Meeki Zone.

1-2. Holotype, USNM 12512, Cottonwood Canyon, Humboldt Range, Nev.

3-5. Plesiotype, USNM 74301, Fossil Hill, Humboldt Range, Nev. [originally illustrated by Smith,

1914, as the holotype of "Ceratites (Gymnotoceras) russelli Smith"]. 

6-7. Plesiotype, USNM 248701, USGS loc. M140. 

8-10. Plesiotype, USNM 248702, USGS loc. M140. 

11-13. Plesiotype, USNM 248703, USGS loc. M140. 

14-16. Plesiotype, USNM 248704, USGS loc. M140. 

17-18. Plesiotype, USNM 248705, USGS loc. M140. 

19-20. Plesiotype, USNM 248706, USGS loc. M140. 

21-22. Plesiotype, USNM 248707, USGS loc. MHO. 

23-24. Plesiotype, USNM 248708, USGS loc. M140. 

25-27. Plesiotype, USNM 248709, USGS loc. M960. 

28-29. Plesiotype, USNM 248710, USGS loc. M960.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 12

__ __ 1_______ _____ ^^ 2 _____

PARAFRECHITES
PLATE 13

[All figures natural size]

FIGURES 1-5. Parafrechites meeki (Mojsisovics) (p. 27). Plesiotypes, Meeki Zone.

1-3. USNM 74391, Fossil Hill, Humboldt Range, Nev. [illustrated by Smith, 1914, as the holotype of

"Ceratites (Gymnotoceras) beckeri Smith"]. 

4-5. USNM 248711, USGS loc. M618.

6-30. Parafrechites durtni (Smith) (p. 28). Plesiotypes, Meeki Zone. 

6-8. USNM 248712, USGS loc. M618. 

9-11. USNM 248713, USGS loc. M618. 

12-13. USNM 248714, USGS loc. M618. 

14-15. USNM 248715, USGS loc. M618. 

16-18. USNM 248716, USGS loc. M968. 

19-21. USNM 248717, USGS loc. M968. 

22-23. USNM 248718, USGS loc. M968. 

24-26. USNM 248719, USGS loc. M968. 

27-28. USNM 248720, USGS loc. M968. 

29-30. USNM 248721, USGS loc. M619.

31-34. Frechites occidentalis (Smith) (p. 30). Plesiotypes, USGS loc. M144 minus 6.0 ft. (1.8 m), Occidentalis Zone. 

31-32. USNM 248722. 

33-34. USNM 248723.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 13

i '^^f^- it

34

PARAFRECHITES AND FRECHITES
PLATE 14

[All figures natural size]

FIGURES 1-33. Frechites occidentalis (Smith) (p. 30). Plesiotypes, Occidentalis Zone.

1-2. USNM 248724, USGS loc. M962.

3-4. USNM 248725, USGS loc. M962.

5-6. USNM 248726, USGS loc. M962.

7-8. USNM 248727, USGS loc. M962. 

9-10. USNM 248728, USGS loc. M145. 

11-12. USNM 248729, USGS loc. M145. 

13-14. USNM 248730, USGS loc. M145. 

15-16. USNM 248731, USGS loc. M145. 

17-18. USNM 248732, USGS loc. M145. 

19-20. USNM 248733, USGS loc. M145. 

21-22. USNM 248734, USGS loc. M145. 

23-25. USNM 248735, USGS loc. M145. 

26-27. USNM 248736, USGS loc. M145. 

28-29. USNM 248737, USGS loc. M624. 

30-31. USNM 248738, USGS loc. M624. 

32-33. USNM 248739, USGS loc. M624.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 14

25

FRECHITES

27
PLATE 15

[All figures natural size]

FIGURES 1-5. Frechitesjohnstoni n. sp. (p. 31). USGS Mesozoic loc. M5481, Subasperum Zone.

1-2. Holotype, USNM 248740.

3-5. Paratype, USNM 248741. 

6-18. Paraceratites burckhardti Smith (p. 31). Plesiotypes, USGS loc. M965, Rotelliformis Zone.

6-7. USNM 248742.

8-9. USNM 248743. 

10-11. USNM 248744. 

12-13. USNM 248745. 

14-15. USNM 248746. 

16-18. USNM 248747.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 15

18

FRECHITES AND PARACERATITES
PLATE 16

[All figures natural size]

FIGURES 1-12. Paraceratites clarkei Smith (p. 32). Plesiotypes, Rotelliformis Zone.

1-2. USNM 248748, USGS loc. M608 minus 8 ft (2.5 m).

3-4. USNM 248749, USGS loc. M136 minus 7 ft (2.1 m).

5-6. USNM 248750, USGS loc. M966.

7-8. USNM 248751, USGS loc. M966.

9-10. USNM 248752, USGS loc. M966.

11-12. USNM 248753, USGS loc. M966.

13-28. Paraceratites vogdesi (Smith) (p. 33). Plesiotypes, USGS loc. M136, Rotelliformis Zone. 

13-14. USNM 248754. 

15-16. USNM 248755. 

17-18. USNM 248756. 

19-20. USNM 748757. 

21-22. USNM 248758. 

23-24. USNM 248759. 

25-26. USNM 248760. 

27-28. USNM 248761.
PROFESSIONAL PAPER 1207 PLATE 16

28

PARACERATITES
PLATE 17

[All figures natural size]

FIGURES 1-5. Paraceratites uogdesi (Smith) (p. 33). Plesiotypes, USGS loc. M136, Rotelliformis Zone.

1-3. USNM 248762.

4-5. USNM 248763. 

6-20. Paraceratites cricki Smith (p. 34). Plesiotypes, Rotelliformis Zone.

6-7. USNM 248764, USGS loc. M607.

8-9. USNM 248765, USGS loc. M607. 

10-11. USNM 248766, USGS loc. M607. 

12-13. USNM 248767, USGS loc. M607. 

14-15. USNM 248768, USGS loc. M607. 

16-18. USNM 248769, USGS loc. M607. 

19-20. USNM 248770, USGS loc. M605 plus 10 ft (3.0 m).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 17

20

PARACERATITES
PLATE 18

[All figures natural size]

FIGURE 1. Eutomoceras cf. E. lahontanum Smith (p. 34). Plesiotype, USNM 248771, USGS loc. M610, Rotelliformis Zone. 

2-7. Eutomoceras dalli Smith (p. 35). Plesiotypes, USGS loc. M611, Rotelliformis Zone.

2. USNM 248772.

3. USNM 248773. 

4-5. USNM 248774. 

6-7. USNM 248775. 

8-15. Eutomoceras dunni Smith (p. 35). Plesiotypes, Meeki Zone.

8-9. USNM 248776, USGS loc. M142. 

10-11. USNM 248777, USGS loc. M142. 

12-13. USNM 248778, USGS loc. M137 plus 4 ft (1.2 m). 

14-15. USNM 248779, USGS loc. M137 plus 4 ft (1.2 m).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 18

\____ ____

EUTOMOCERAS
PLATE 19

[All figures natural size]

FIGURES 1-6. EutomoceraslaubeiMeeli(p. 35).

1-2. Holotype, USNM 12528, New Pass Range, Nev. 

3-4. Plesiotype, USNM 248780, USGS loc. M962, Occidentalis Zone. 

5-6. Plesiotype, USNM 248781, USGS loc. M618, Meeki Zone. 

7-15. Pesudodanubites halli (Mojsisovics) (p. 44). Plesiotypes, Hyatti Zone.

7-9. USNM 248782, USGS loc. M970. 

10-11. USNM 248783, USGS Mesozoic loc. M1181. 

12-13. USNM 248784, USGS Mesozoic loc. M1181. 

14-15. USNM 12522, Congress Canyon, Humboldt Range, Nev. 

16-19. Czekanowskites hayesi (McLearn) (p. 43). Plesiotype, USNM 248785, USGS loc. M970, Hyatti Zone.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 19

EUTOMOCERAS, PSEUDODANUBITES, AND CZEKANOWSKITES
PLATE 20

[All figures natural size unless otherwise indicated]

FIGURES 1-12. Cuccoceras bonaevistae (Hyatt and Smith) (p. 23). Hyatti Zone.

1-3. Holotype, USNM 74383, Unionville, Buena Vista Canyon, Humboldt Range, Nev.

4-5. Plesiotype, USNM 248786, USGS loc. M533.

6-8. Plesiotype, USNM 248787, USGS loc. M533.

9-10. Plesiotype, USNM 248788, USGS loc. M533.

11-12. Plesiotype, USNM 248789, USGS loc. M533.

13-14. Hungarites sp. (p. 38). Plesiotype USNM 248790, USGS loc. M907, upper Ladinian. 

15-35. Intornites mctaggarti (McLearn) (p. 48). Plesiotypes, USGS loc. M533, Hyatti Zone.

15. USNM 248791. 

16-17. USNM 248792. 

18-19. USNM 248793. 

20-21. USNM 248794. 

22-23. USNM 248795. 

24. USNM 248796. 

25-26. Same as figure 24, X 2. 

27-28. USNM 248797, X 2.

29. Same as figure 28.

30. USNM 248798. 

31-32. Same as figure 30, X 2.

33. USNM 248799. 

34-35. Same as figure 33, X 2.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 20

CUCCOCERAS, HUNGARITES, AND INTORNITES
PLATE 21

[All figures natural size unless otherwise indicated]

FIGURES 1-18. Intorrdtes nevadanus (Hyattand Smith) (p. 48). Shoshonensis Zone. 

1-2. Paratype, MCZ 3903a, New Pass Range, Nev., X 2. 

3-4. Paratype, MCZ 3904, New Pass Range, Nev., X 2. 

5-6. Holotype, MCZ 3902, New Pass Range, Nev., X 2. 

7-8. Plesiotype, USNM 248800, USGS loc. M635. 

9-11. Plesiotype, USNM 248801, USGS loc. M635, X 2. 

12-14. Plesiotype, USNM 248802, USGS loc. M635. 

15-16. Plesiotype, USNM 248803, USGS loc. M635. 

17-18. Plesiotype, USNM 248804, USGS loc. M635.

19-25. Longobardites parvus (Smith) (p. 50). Plesiotypes, Rotelliformis Zone. 

19-20. USNM 248805, USGS loc. M611, X 2. 

21-22. USNM 248806, USGS loc. M611. 

23-24. USNM 248807, USGS loc. M611, X 2.

25. USNM 248808, USGS loc. M964.

26-28. Longobardites zsigmondyi (Bockh) (p. 51). Plesiotypes, Occidentalis Zone. 

26-27. USNM 248809, USGS loc. M961, X 2.

28. USNM 248810, USGS loc. M962.

29-30. Metadinarites desertorus (Smith) (p. 52). Plesiotype, USNM 248811, USGS loc. M967, Rotelliformis Zone. 

31-37. Aplococeras smithi, n. sp. (p. 52).

31-32. Holotype, USNM 248812, USGS loc. M608, Rotelliformis Zone. 

33-34. Paratype, USNM 248813, USGS loc. M608, Rotelliformis Zone. 

35-36. Paratype, USNM 248814, USGS loc. M613, Rotelliformis Zone. 

37. Paratype, USNM 248815, USGS loc. M142, Meeki Zone.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 1207 PLATE 21

37

INTORNITES, LONGOBARDITES, METADINARITES, AND APLOCOCERAS
PLATE 22

[All figures natural size]

FIGURES 1-17. Aplococeras vogdesi (Hyatti and Smith) (p. 53). Meeki Zone.

1-2. Holotype, USNM 74385, Fossil Hill, Humboldt Range, Nev.

3-4. Plesiotype, USNM 248816, USGS loc. M960.

5-6. Plesiotype, USNM 248817, USGS loc. M960.

7-8. Plesiotype, USNM 248818, USGS loc. M960.

9. Plesiotype, USNM 248819, USGS loc. M619.

10-11. Plesiotype, USNM 248820, USGS loc. M619.

12-13. Plesiotype, USNM 248821, USGS loc. M619.

14-15. Plesiotype, USNM 248822, USGS loc. M968.

16-17. Plesiotype, USNM 248823, USGS loc. M968.

18-23. Aplococeras paruus (Smith) (p. 53). Plesiotypes, Occidentalis Zone. 

18-19. USNM 248824, USGS loc. M144 minus 6.0 ft (1.8 m). 

20-21. USNM 248825, USGS loc. M623. 

22-23. USNM 248826, USGS loc. M962A.

24-29. Nevadites hyatti (Smith) (p. 36). Plesiotypes, USGS loc. M144 minus 6.0 ft (1.8 m). 

24-25. USNM 248827. 

26-27. USNM 248828. 

28-29. USNM 248829.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 22

J___________.2__J

APLOCOCERAS AND NEVADITES
PLATE 23

[All figures natural size]

FIGURES 1-7. Nevadites hyatti (Smith) (p. 36). Occidentalis Zone.

1-3. Holotype, USNM 74268, Fossil Hill, Humboldt Range, Nev.

4-5. Plesiotype, USNM 248830, USGS loc. M144 minus 6.0 ft (1.8 m).

6-7. Plesiotype, USNM 248831, USGS loc. M144 minus 6.0 ft (1.8 m). 

8-19. Nevadites humboldtensis Smith (p. 37). Plesiotypes, USGS loc. M144, Occidentalis Zone.

8-9. USNM 248832. 

10-11. USNM 248833. 

12-13. USNM 248834. 

14-15. USNM 248835. 

16-17. USNM 248836. 

18-19. USNM 248837.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 23

\ 

\ 

\

\ W*

\ i^ »*£ 4

x <i ') '*/

19

18

NEVADITES
PLATE 24

[All figures natural size]

FIGURES 1-4. Nevadites humboldtensis Smith (p. 37). Plesiotypes, USGS loc. M144, Occidentalis Zone. 

1-2. USNM 248838. 

3-4. USNM 248839. 

5-7. Nevadites furlongi (Smith) (p. 38). Plesiotypes, USGS loc. M145, Occidentalis Zone.

5. USNM 248840. 

6-7. USNM 248841.

8-11. Nevadites gabbi (Smith) (p. 38). Plesiotypes, USGS loc. M146, Occidentalis Zone. 

8-10. USNM 248842. 

11. USNM 248843. 

12-13. Protrachyceras subasperum (Meek) (p. 58). Holotype, USNM 20223, Cottonwood Canyon, Humboldt Range,

Nev.

14-16. Protrachyceras meeki (Mojsisovics) (p. 58). Holotype, USNM 12529, Cottonwood Canyon, Humboldt Range, 

Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 24

12 16

NEVADITES AND PROTRACHYCERAS
PLATE 25

[All figures natural size]

FIGURES 1-5. Protrachyceras americanum (Mojsisovics) (p. 58).

1-3. Holotype, ANSP 1221, locality unknown but probably Humboldt Range, Nev. 

4-5. Plesiotype figured by Meek, 1877, USNM 12527, Cottonwood Canyon, Humboldt Range, Nev. 

6-7. Sirenites homfrayi (Gabb) (p. 59). Holotype, ANSP 30793, East Range, Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 25

PROTRACHYCERAS AND SIRENITES
PLATE 26

[All figures natural size]

FIGURES 1-4. Tropigymnites? cf. T. planorbis (Hauer) (p. 39). Plesiotypes, Rotelliformis Zone.

1-2. USNM 248844, USGS loc. M605.

3-4. USNM 248845, USGS loc. M136.

5-17. Tropigastrites lahontanus Smith (p. 54). Plesiotypes, Rotelliformis Zone. 

5. USNM 248846, USGS loc. M609.

6-7. USNM 248983, USGS loc. M609.

8-9. USNM 248847, USGS loc. M141. 

10-11. USNM 248848, USGS loc. M608. 

12-13. USNM 248849, USGS loc. M608. 

14-15. USNM 248850, USGS loc. M964. 

16-17. USNM 248851, USGS loc. M611.

18-36. Tropigastrites louderbacki (Hyatt and Smith) (p. 54). Meeki Zone. 

18-19. Plesiotype, USNM 248852, USGS loc. M142.

20-21. Holotype, USNM 74400, vicinity of Fossil Hill, Humboldt Range, Nev. 

22-23. Plesiotype, USNM 248853, USGS loc. M166. 

24-25. Plesiotype, USNM 248854, USGS loc. M166. 

26-28. Plesiotype, USNM 248855, USGS loc. M166. 

29-30. Plesiotype, USNM 248856, USGS loc. M166. 

31-32. Plesiotype, USNM 248857, USGS loc. M166. 

33-34. Plesiotype, USNM 248858, USGS loc. M166. 

35-36. Plesiotype, USNM 248859, USGS loc. M166.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 26

36

TROPIGYMNITES? AND TROPIGASTRITES
PLATE 27

[All figures natural size]

FIGURES 1-13. Tozeritesgemmellaroi (Arthaber) (p. 55). Meeki Zone.

1-2. Lectotype, USNM 74305, vicinity of Fossil Hill, Humboldt Range, Nev. 

3-4. Plesiotype, USNM 248860, USGS loc. M968. 

5-7. Plesiotype, USNM 248861, USGS loc. M968. 

8-9. Plesiotype, USNM 248862, USGS loc. M619.

10-11. Plesiotype, USNM 248863, USGS loc. M618.

12-13. Plesiotype, USNM 248864, USGS loc. M619. 

14-23. Tozerites humboldtensis (Smith) (p. 56). Plesiotypes, Occidentalis Zone.

14-15. USNM 248865, USGS loc. M144.

16-17. USNM 248866, USGS loc. M962.

18-19. USNM 248867, USGS loc. M962.

20-21. USNM 248868, USGS loc. M144.

22-23. USNM 248869, USGS loc. M144. 

24-29. Tozerites polygyratus Smith (p. 56). Plesiotypes, Occidentalis Zone.

24-25. USNM 248870, USGS loc. M624.

26-27. USNM 248871, USGS loc. M622.

28-29. USNM 248872, USGS loc. M622. 

30-35. Proarcestes cf. P. balfouri (Oppel) (p. 57). Plesiotypes, Rotelliformis Zone.

30-32. USNM 248873, USGS loc. M609.

33-35. USNM 248874, USGS loc. M137. 

36-45. Proarcestes gabbi Meek (p. 57). Plesiotypes, Occidentalis Zone.

36-38. USNM 248875, USGS loc. M962.

39-41. USNM 248876, USGS loc. M962.

42-43. USNM 248877, USGS loc. M620.

44-45. USNM 248878, USGS loc. M144.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 27

44 45

TOZERITES AND PROARCESTES
PLATE 28

[All figures natural size]

FIGURES 1-2. Proarcestesgabbi (Meek) (p. 57). Holotype, USNM 12523, near Cottonwood Canyon, Humboldt Range, Nev. 

3-9. Humboldtites septentrionalis (Smith) (p. 21). Plesiotypes. Occidentalis Zone. 

3-5. USNM 248879, USGS loc. M962. 

6-7. USNM 248880, USGS loc. M245. 

8-9. USNM 248881, USGS loc. M620 

10-18. Isculites meeki (Hyatt and Smith) (p. 42).

10-11. Holotype, MCZ 3998, Star Canyon, Humboldt Range, Nev. 

12-13. Paratype, MCZ 3900, Star Canyon, Humboldt Range, Nev. 

14-16. Plesiotype, USNM 248882, USGS Mesozoic loc. M2358, Caurus Zone. 

17-18. Plesiotype, USNM 248883, USGS Mesozoic loc. M2358, Caurus Zone.

19-20. Ismidites aff. /. marmarensis Arthaber (p. 20). Plesiotype, USNM 248884, USGS loc. M970, Hyatti Zone. 

21-25. Alanites obesus n. sp., (p. 19). USGS loc. M533, Hyatti Zone. 

21-22. Holotype, USNM 248885. 

23-25. Paratype, USNM 248886.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 28

23 X^" ^^ '"^^^ 25 

PROARCESTES, HUMBOLDTITES, ISCULITES, ISMIDITES, AND ALANITES
PLATE 29

[All figures natural size]

FIGURES 1-9. Pamcrochordiceras americanum McLearn (p. 21). Plesiotypes, USGS Mesozoic loc. M2358, Caurus Zone. 

1-2. USNM 248887. 

3-5. USNM 248888. 

6-7. USNM 248889. 

8-9. USNM 248890.

10-13. Isculites meeki (Hyatt and Smith) (p. 42). Plesiotypes, USGS Mesozoic loc. M2358, Caurus Zone. 

10-11. USNM 248891. 

12-13. USNM 248892.

14-30. Lenotropites caurus (McLearn) (p. 46). Plesiotypes, USGS Mesozoic loc. M2358, Caurus Zone. 

14-15. USNM 248893. 

16-17. USNM 248894. 

18-19. USNM 248895. 

20-21. USNM 248896. 

22-23. USNM 248897. 

24-25. USNM 248898. 

26-27. USNM 248899. 

28-30. USNM 248900. 

31-35. Alanites mulleri n. sp., (p. 19). USGS Mesozoic loc. M2359, Hyatti Zone.

31. Paratype, USNM 248901. 

32-33. Paratype, USNM 248902. 

34-35. Holotype, USNM 248903.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 29

31 35

PARACROCHORDICERAS, ISCULITES, LENOTROPITES, AND ALANITES
PLATE 30

[All figures natural size unless otherwise indicated]

FIGURES 1-10. Isculites tozeri n. sp. (p. 43). USGS loc. M533, Hyatti Zone.

1-2. Paratype, USNM 248904.

3-4. Holotype, USNM 248905.

5-7. Paratype, USNM 248906.

8-10. Paratype, USNM 248907.

11-16. Gymnites perplanus (Meek) (p. 40).

11-12. Holotype, USNM 12531, Buena Vista Canyon, Humboldt Range, Nev. 

13-14. Plesiotype, USNM 248908, USGS loc. M533, Hyatti Zone. 

15-16. Plesiotype, USNM 248909, USGS loc. M533, Hyatti Zone. 

17-18. Sturia cf. S. japonica Diener (p. 41). USGS loc. M614, float from Meeki Zone or higher.

17. Suture of specimen illustrated by figure 18 (USNM 248910).

18. Plesiotype, USNM 248910, X Vz.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 30

ISCULITES, GYMNITES AND STURIA
PLATE 31

[All figures natural size]

FIGURE 1. Gymnites cf G. humboldti Mojsisovics (p. 40). Plesiotype, USNM 248911, USGS loc. M609, Rotelliformis Zone. 

2-5. Aulametacoceras? humboldtensis n. sp. (p. 61). Hyatti Zone.

2-3. Holotype, USNM 248912, USGS Mesozoic loc. M2359. 

4-5. Paratype, USNM 248913, USGS loc. M533.

6-12. Gymnites tregorum n. sp. (p. 39). USGS Mesozoic loc. M2358, Caurus Zone. 

6-7. Paratype, USNM 248914. 

8-9. Holotype, USNM 248915. 

10-11. Paratype, USNM 248916. 

12. Paratype, USNM 248917. 

13. Epigymnites alexandrae (Smith) (p. 41). Plesiotype, USNM 248918, USGS loc. M619, Meeki Zone.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 31

10

'^,y-^ 13

11 12

GYMNITES, AULAMETACOCERAS?, GYMNITES AND EPIGYMNITES
PLATE 32

[All figures natural size unless otherwise indicated]

FIGURES 1-2. Monophyllites cf. M. agenor (Miinster) (p. 60). Holotype, ANSP 30794, East Range, Nev.

3-4. Ussurites cf. U. arthaberi (Welter) (p. 60). Plesiotype, USNM 248919, USGS Mesozoic loc. M1185, Hyatti Zone. 

5-6. Germanonautilus furlongi Smith (p. 62). Plesiotype, USNM 248920, USGS loc. M608 (float), probably from

Meeki Zone.

7-8. Paranautilus smithi Kummel (p. 62). Plesiotype, USNM 248921, USGS loc. M620, Occidentalis Zone, X Vz. 

9-11. Grypoceras whitneyi (Gabb) (p. 62). Holotype, ANSP 30792, vicinity of Buena Vista Canyon, Humboldt Range, 

Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 32

MONOPHYLLITES, USSURITES, GERM ANON AUTILUS, PARANAUTILUS, AND GRYPOCERAS
PLATE 33

FIGURES 1-2. Michelinoceras? cf.M.? campanile (Mojsisovics) (p. 63). Plesiotypes, Meeki Zone.

1. Longitudinal cross section, USNM 248922, USGS loc. M142, X 5.

2. Longitudinal cross section, USNM 248923, USGS loc. M619, X 5.

3-4. Atractites sp. A (p. 64). Dorsal and lateral views, USNM 248924, USGS loc. M136, Rotelliformis Zone, natural 

size.

5. Atractites clavatulus Smith (p. 64). Plesiotype, dorso-ventral median section showing tip of alveolus and 

protoconch within the guard, USNM 248925, USGS loc. M608, Rotelliformis Zone, X 11.5.

6. Atractites sp. B (p. 64). Dorso-ventral median section showing siphuncle; orad direction upward, camera and 

septa to left, ventral shell wall to right. USNM 248926, USGS loc. M636, (Favret Canyon, Augusta Mountains, Nev.), upper Anisian, X 11.5.

7. Atractites sp. C (p. 64). Dorso-ventral median section showing septal neck, connecting rings, and siphuncle (on 

left side); orad direction upward; see text-figure 48 for interpretation. Plate 34, figures 1-3 show specimen 

before thin sectioning. USNM 248927, USGS loc. M636c (Favret Canyon, Augusta Mountains, Nev.), Meeki 

Zone, X 23.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 33

/

,-i 6 7

MICHELINOCERAS? AND ATRACTITES
PLATE 34

[All figures natural size; all lateral views oriented so that dorsal side is nearest dorsal view (if any) and ventral side is nearest ventral view (if any)].

FIGURES 1-3. Atrocities sp. C (p. 64). Dorsal, lateral, and ventral views, USNM 248927, specimen before it was destroyed

for thin section (pi. 33, fig. 7), USGS loc. 636c (Favret Canyon, Augusta Mountains, Nev.), Meeki Zone.

4-5. ?Atractites elegans Smith (p. 64). Lateral and dorsal views, plesiotype, USNM 248929, USGS loc. M967, Rotelliformis Zone.

6-11. Atractites clavatulus Smith (p. 64). Plesiotypes, USGS loc. M608, Rotelliformis Zone. 

6-8. Dorsal, lateral, and ventral views, USNM 248930. 

9-11. Ventral, lateral, and dorsal views, USNM 248931. 

12-25. Atractites solidus Smith (p. 65). Plesiotypes, Meeki Zone.

12-14. Dorsal, lateral, and ventral views, USNM 248932, USGS loc. M614. 

15-17. Ventral, lateral, and dorsal views, USNM 248933, USGS loc. M142. 

18-20. Dorsal, lateral, and ventral views, USNM 248934, USGS loc. M142. 

21-23. Ventral, lateral, and dorsal views, USNM 248935, USGS loc. M614. 

24-25. Ventral and lateral views, USNM 248936, USGS loc. M166. 

26-33. Atractites nevadensis (Meek) (p. 65). Plesiotypes.

26-27. Lateral and dorsal views, USNM 248937, USGS loc. M621, Occidentalis Zone. 

28-30. Ventral, lateral, and dorsal views, USNM 248938, USGS loc. M963, Meeki Zone. 

31-33. Ventral, lateral, and dorsal views, USNM 248939, USGS loc. M144, Occidentalis Zone.
GEOLOGICAL SURVEY

PROFESSIONAL PAPER 1207 PLATE 34

24 25 28 29 

ATRACTITES
PLATE 35

[All figures natural size]

FIGURES 1-7. Daonella americana Smith (p. 67). Plesiotypes, Rotelliformis Zone.

1. USNM 248940, USGS loc. M964.

2. USNM 248941, USGS loc. M162.

3. USNM 248942, USGS loc. M162.

4. USNM 248943, USGS loc. M163.

5. USNM 248944, USGS loc. M163.

6. USNM 248945, USGS loc. M163.

7. USNM 248946, USGS loc. M965. 

8-12. Daonella cf. D. sturi (Benecke) (p. 67). Plesiotypes.

8. USNM 248947, USGS loc. M607 plus 2.0 ft (0.6 m), Rotelliformis Zone.

9. USNM 248948, USGS loc. M607 plus 2.0 ft (0.6 m), Rotelliformis Zone.

10. USNM 248949, USGS loc. M608, Rotelliformis Zone.

11. Latex impression, USNM 248950, USGS loc. M142, Meeki Zone.

12. USNM 248951, USGS loc. M609, Rotelliformis Zone.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 35
PLATE 36

[All figures natural size]

FIGURES 1-5. Daonella cf. D. elongate Mojsisovics (p. 67). Plesiotypes, USGS loc. M968, Meeki Zone.

1. USNM 248952.

2. USNM 248953.

3. USNM 248954.

4. USNM 248955.

5. USNM 248956. 

6-9. Daonella cf. D. moussoni (Merian) (p. 68). Plesiotype, Occidentalis Zone.

6. USNM 248957, USGS loc. M962.

7. USNM 248958, USGS loc. M623.

8. USNM 248959, USGS loc. M145.

9. USNM 248960, USGS loc. M145. 

10-15. Daonella dubia (Gabb) (p. 68).

10. Lectotype, ANSP 20785, Star Canyon, Humboldt Range, Nev.

11. Plesiotype, USNM 248961, USGS loc. M623, Occidentalis Zone.

12. Plesiotype, USNM 248962, USGS loc. M145, Occidentalis Zone.

13. Plesiotype, USNM 248962, USGS loc. M145, Occidentalis Zone. Same slab as figure 12.

14. Plesiotype, USNM 248964, USGS loc. M145, Occidentalis Zone.

15. Plesiotype, USNM 248965, USGS loc. M145, Occidentalis Zone.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 36

DAONELLA
PLATE 37

[All figures natural size]

FIGURES 1-3. Daonella cf. D. moussoni (Merian), (p. 68). Plesiotypes, Occidentalis Zone.

1. USNM 248966, USGS loc. M909.

2. USNM 248967, USGS loc. M146.

3. Latex impression, USNM 248968, USGS loc. M623. 

4-9. Daonella rieberi n. sp. (p. 68). Subasperum Zone.

4. Latex impression of holotype, USNM 248969, USGS loc. M147. 

4a. Latex impressions of paratypes, USNM 248970, USGS loc. M147.

5. Latex impression of paratype, USNM 248971, USGS Mesozoic loc. M3094.

6. Latex impression of paratype, USNM 248972, USGS loc. M908.

7. Paratype, USNM 248973, USGS loc. M911.

8. Latex impression of paratype, USNM 248974, USGS loc. M911.

9. Latex impression of paratype, USNM 248975, USGS loc. M911.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 37
PLATE 38

[All figures natural size]

FIGURES 1-2. Daonellarieberi n. sp. (p. 68). Paratypes, USGS loc. M908, Subasperum Zone.

1. Latex impression, USNM 248976.

2. Latex impression, USNM 248977. 

3-4. Daonella n. sp. ex aff. D. indica Bittner (p. 69). Plesiotypes, USGS Mesozoic loc. M3095, upper Ladinian.

3. USNM 248978.

4. USNM 248979. 

5-7. Daonella cf. D. lommeli (Wissman) (p. 69). Plesiotypes, USGS loc. M907, upper Ladinian.

5. USNM 248980.

6. USNM 248981.

7. USNM 248982.

8-9. Pteria? obesus (Gabb) (p. 66). Holotype?, ANSP 30791, original locality description vague but probably from 

Humboldt Range, Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1207 PLATE 38

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U.S. GOVERNMENT PRINTING OFFICE: 676-041/15 1983