American Triassic 

Coiled Nautiloids

GEOLOGICAL SURVEY PROFESSIONAL PAPER 250
1
American Triassic 

Coiled Nautiloids

By BERNHARD KUMMEL

GEOLOGICAL SURVEY PROFESSIONAL PAPER 250

A study of the classification and evolution of late 

Paleozoic and early Mesozoic cephalopods, 

and description of new species

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1953,
UNITED STATES DEPARTMENT OF THE INTERIOR

Douglas McKay, Secretary

GEOLOGICAL SURVEY

W. E. Wrather, Director

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

Washington 25, D. C. - Price $1.25 (paper cover)
CONTENTS

Abstract_ _ _______________________________________

Introduction and acknowledgments___-_---_-_-_-_____

Occurrence.-.._____________________________________

Middle Rocky Mountains region________________

Nevada__ ___________________________________

California. _____________________________________

Canada______________________________________

Alaska ________________________________________

Mexico ________________________________________

South America.________________________________

Classification of late Paleozoic and Triassic nautaloids___ 

Geologic history.___________________________________

Evolution__ _ _____________________________________

Systematic paleontology.____________________________

Family Tainoceratidae Hyatt, 1883_______________

Phylogeny____ — _______ —— _______________

Genus Temnocheilus M'Coy, 1844_____________

Genus Foordiceras Hyatt, 1893_______________

Genus Metacoceras Hyatt, 1883.._____________

Subgenus Mojsvaroceras Hyatt, 1883______

M. (Mojsvaroceras) turneri Hyatt and 

Smith. _ _____________________

M. (Mojsvaroceras) frenchi, n. sp_ _ _ _ _

Genus Parametacoceras Miller and Owen, 1934_ 

Genus Tainoceras Hyatt, 1883______________

Genus Cooperoceras Miller, 1945. _____________

Genus Tainionautilus Mojsisovies, 1902______

Genus Tirolonautilus Mojsisovics, 1902________

Genus Aulametacoceras Miller and Unklesbay, 

1942. ____________________________________

Genus Germanonautilus Mojsisovics, 1902______

Germanonautilus brooksi Smith__________

Germanonautilus furlongi Smith-__________

Germanonautilus johnstoni, n. sp__________

Germanonautilus montpelierensis, n. sp___._ 

Germanonautilus spp. (of Nevada)________

Germanonaulilus spp. (of Alaska)_________

Genus Thuringionautilus Mojsisovics, 1902_____

Genus Pleuronautilus Mojsisovics, 1882________

Subgenus Pleuronautilus ss_______________

P. (Pleuronautilus} alaskensis, n. sp___ 

P. (Pleuronautilus) idahoensis, n. sp___ 

P. (Pleuronautilus) sp. (of Idaho)_____

P. (Pleuronautilus) sp. (of Montana) __ 

Subgenus Enoploceras Hyatt, 1900._______

P. (Enoploceras) newelli, n. sp ________

Subgenus Holconautilus Mojsisovics, 1902__ 

Subgenus Encoiloceras Hyatt, 1900______

Subgenus Anoploceras Hyatt, 1900_.______

Subgenus Trachynautilus Mojsisovics, 1902_ 

Genus Phloioceras Hyatt, 1883_--_______.____

Phloioceras sp__________________________

Family Grypoceratidae Hyatt, 1900_____________

Phylogeny_ ________________________________

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Systematic paleontology—Continued

Family Grypoceratidae Hyatt—Continued F'&e

Genus Grypoceras Hyatt, 1883— _____________ 48

Subgenus Grypoceras..-....--.- — ______ 53

G. (Grypoceras) milleri, n. sp _________ 53

G. (Grypoceras) whitneyi (Gabb)______ 53

Subgenus Domatoceras Hyatt, 1891____ _ _ _ _ 54

Subgenus Plummeroceras, n. subgen.______ 54

G. (Plummeroceras) plummeri, n. sp___ 54

Genus Gryponautilus Mojsisovics, 1902________ 55

Gryponautilus cooperi Smith._____________ 56

Genus Menuthionautilus Collignon, 1933-__-___ 57

Genus Stenopoceras Hyatt, 1893______________ 57

Genus Stearoceras Hyatt, 1893________________ 58

Genus Pselioceras Hyatt, 1883____-_______-___ 58

Genus Titanoceras Hyatt, 1884_______________ 59

Family Syringonautilidae Mojsisovics, 1902________ 59

Phylogeny__ _____-___-_______----_-_--_-_-_ 59

Genus Syringonautilus Mojsisovics, 1902_______ 60

Genus Syringoceras Hyatt, 1894______________ 60

Syringoceras spurri Smith._______________ 63

Genus Juvavionautilus Mojsisovics, 1902_______ 63

Genus Oxynautilus Mojsisovics, 1902__________ 63

Genus Clymenonautilus Hyatt, 1900___________ 65

Family Paranautilidae Kummel, 1950_____________ 65

Phylogeny-___._____________--_--_-_____--_ 66

Genus Paranautilus Mojsisovics, 1902_________ 67

Paranautilus multicameratus (Gabb)______ 71

Paranautilus smithi, n. sp_ ___----_-__---_ 71

Paranautilus sp_ — ______________________ 72

Genus Indonautilus Mojsisovics, 1902.____ 72

Genus Sibyllonautilus Diener, 1915._______ 73

Sibyllonautilus fergusoni, n. sp________ 74

Sibyllonautilis liardensis (Whiteaves) _ _ 75

Family Clydonautilidae Hyatt, l900__--___--_--_- 75

Phylogeny _________ —— __-________-_-__-___ 77

Genus Styrionautilus Mojsisevics, 1902._______ 80

Styrionautilus sp_----__-_______—______ 80

Genus Proclydonautilus. _____________________ 80

Proclydonautilis triadicus Mojsisovics______ 81

Proclydonautilus spirolobus (Dittmar)____ 82

Proclydonautilus stantoni Smith.__________ 82

Proclydonautilus ursensis Smith.__________ 83

Proclydonautilus hessi (Smith)______._^___ 83

Proclydonautilus squawensis, n. sp_________ 83

Proclydonautilus natosini McLearn_ _______ 84

Genus Cosmonautilus Hyatt and Smith, 1905___ 84

Co&monautilus dilleri Hyatt and Smith-___ 85

Cosmonautilus pacificus Smith.___________ 85

Cosmonautilus shastensis Smith.__________ 86

Cosmonautilus hersheyi Smith___________ 87

Genus Callaionautilus Kieslinger, 1924_______ 87

Genus Clydonautilus Mojsisovics, 1882__"_____ 88

Family Gonionautilidae Kummel, 1950____________ 89

Genus Gonionautihis Mojsisovics, 1902________ 89

Bibliography. ______________________________________ 89

Index.____________________________________________ 95

m
IV CONTENTS

ILLUSTRATIONS

[Plates 1-19 follow index]

PLATE 1. Temnocheilus and Metacoceras.

2. Metacoceras (Mojsvaroceras).

3. Germanonautilus.

4. Pleuronautilus, P. (Enoploceras), Phloioceras, M. 

(Mojsvaroceras), Paranautilus.

5. Grypoceras (Grypoceras) and G. (Plummeroceras).

6. Grypoceras (Grypoceras).

7. Gryponautilus, Syringoceras, Clymenonautilus, and 

Proclydonautilus.

8. Proclydonautilus, Paranautilus, and Sibyllonautilus.

9. Proclydonautilus. 

10. Proclydonautilus and Cosmonautilus.

PLATE 11. Proclydonautilus.

12. Cosmonautilus.

13. Cosmonautilus.

14. Cosmonautilus, Paranautilus, and Sibyllonautilus.

15. Cosmonautilus, Proclydonautilus, and Styrionautilus.

16. Cosmonautilus.

17. Pleuronautilus (Anoploceras), P. (Holconautilus), 

Phloioceras, P. (Trachynautilus), P. (Enioiloceras) .

18. Juvavionautilus, Syringonautilus, Syringoceras, Styrionautilus, Indonautilus.

19. Oxynautilus, Tainionautilus, Gonionautiluz, Callaionautilus.

FIGURE 1. Bar chart of number of nautiloid genera per 

period_ _ _____________________________

2. Bar chart of number of species of Triassic 

nautiloids per epoch___-_-_-_-______..____

3. Bar chart of number of genera of Triassic 

nautiloids per epoch-__________________

4. Phylogeny of late Paleozoic and Triassic coiled 

nautiloids- _____________________________

5. Phylogeny of the Tainoceratidae____ _______

6. Range chart of the Tainoceratidae._________

7. Tainionautilus, Foordiceras, Aulametacoceras, 

Tainoceras, Cooperoceras, Tirol'onautilus, 

Metacoceras, and Temnocheilus_________.„

8. Temnocheilus latus (Meek and Worthen) __ _ _ _

9. Germanonautilus and Metacoceras (Mojsvaroceras) _-_______-__---________-__-______

10. Metacoceras (Mojsvaroceras) turneri Hyatt and 

Smith——— — ———— — — —— — — — ———

11. Metacoceras (Mojsvaroceras) frenchi n. sp_____

12. Germanonautilus furlongi Smith___________

13. Germanonautilus johnstonin. sp_____________

14. Germanonautilus montpelierensis n. sp_______

15. Thuringionautilus jugatonodosus (Zimmermann) _________________________________

16. Pleuronautilus, P. (Encoiloceras), P. (Trachynautilus) , and Phloioceras, _______________

17. Pleuronautilus idahoensis n. sp___________

18. P. (Holconautilus) and P. (Enoploceras).---,

19. P. (Enoploceras) newelli n. sp_______________

20. Phloioceras sp----------------------------

21. Phylogeny of the Grypoceratidae and Syringonautilidae_ ______------_-__-______-_____

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Range chart of the Grypoceratidae________ 47

Pselioceras, Stenopoceras, Menuthionautilus,

and G. (Domatoceras) __________________ 49

Grypoceras (Grypoceras) __________________ 50

Gryponautilus, Titanoceras, and Stearocerds _ _ 52 

Grypoceras (Grypoceras) milleri n. sp_______ 53

Grypoceras (Plummeroceras) plummeri n. sn__ 56 

Menuthionautilus kieslingeri Collignon_ ______ 57

Range chart of the Syringonautilidae._______ 59

Syringoceras and Syringonautilus- ___________ 62

Syringoceras spurri Smith_________________ 63

Oxynautilus, Juvavionautilus, Syringonautilus,

and Clymenonautilus- _______-______--_-- 64

Phylogeny of Paranautilidae, Clydonautilidae,

and Gonionautilidae_____-__________-__- 67

Range chart of the Paranautilidae, Clydonautilidae, and Gonionautilidae______________ 68

Liroceras, Paranautilus, Sibyllonautilus, and

Indonautilus _________-_________-__----- 70

Paranautilus smithi n. sp__________________ 72

Sibyllonautilus fergusoni n. sp______________ 75

Clydonautilus, Gonionautilus, and Sty^ionautilus- ____________-___-_-_______-_-- 76

Styrionautilus sp_-_-__-_-___-_-_---_-_--_- 77 

Proclydonautilus- _________-___-_______-_-- 78

Paranautilus, Styrionautilus, Proclydonautilus, 

Callaionautilus, Cosmonautilus, and Clydonautilus- ------------------------------ 79

Proclydonautilus squawensis n. sp_______-___ 84

Callaionautilus turgidus Kieslinger__________ 88
AMERICAN TRIASSIC COILED NAUTILOIDS

By BEKNHARD KUMMEL

ABSTRACT

The relationships of late Paleozoic and Triassic nautiloids are 

studied. Of the nine families of late Paleozoic nautiloids three 

are directly involved in the ancestry of Triassic nautiloids. Two 

of these "Paleozoic" families include Triassic genera. Only 

three families of nautiloids are confined to the Triassic. Pennsylvanian, Permian, and Triassic nautiloids are very closely related 

and show no big breaks in their history. There is a large -change 

in the evolutionary pattern of nautiloids between the Triassic and 

the Jurassic but only a very minor one at the Permian-Triassic 

boundary. Evolution of the nautiloids in the Triassic is mostly 

one of culminating patterns and modes started in the late 

Paleozoic.

The late Paleozoic and Triassic nautiloid families discussed are: 

(1) the Tainoceratidae, which includes Temnocheilus, Foordiceras, 

Metacoceras, M. (Mojsvaroceras), Parametacoceras, Tainoceras, 

Aulametacoceras, Cooperoceras, Tirolonautilus, Tainionautilus, 

Germanonautilus, Pleuronautilus, PI. (Encoiloceras), PL (Enoploceras), PI. (Anoploceras), PI. (Trachynautilus), PL (Holconautilus), Phloioceras; (2) the Grypoceratidae, which includes 

Grypoceras, G. (Domatoceras), G. (Plummeroceras), n. subgen., 

Stearoceras, Titanoceras, Stenopoceras, Pselioceras, Menuthionautilus, Gryponautilus; (3) the Syringonautilidae, which includes 

Syringonautilus, Syringoceras, Juvavionautilus, Oa,ynautilus, Clymenonautilus; (4) the Liroceratidae, which includes Liroceras, 

Condraoceras, Acanthonautilus, Coelogasteroceras, and Peripetoceras; (5) the Paranautilidae, which includes Paranautilus, 

Sybillonoutilus, and Indonautilus; (6) the Clydonautilidae, which 

includes Styrionautilus, Proclydonautilus, Clydonautilus, Cosmonautilus, and Callaionautilus; (7) the Gorionautilidae, which 

includes Gonionautiliis.

Triassic nautiloids are not nearly as common in North America 

as they are in the region of the Tethyian geosyncline. About 30 

species are known from North America, including 12 new ones.

INTRODUCTION AND ACKNOWLEDGMENTS

Studies in American Triassic paleontology have been 

almost completely neglected since the days of Alpheus 

Hyatt and J. P. Smith. The several large monographs 

by these pioneers were mainly on the ammonitic 

cephalopods. The nautiloids were only briefly treated. 

There is not a single American publication devoted 

solely to Triassic nautiloids. The writer has for the 

past ten years been studying the stratigraphy and 

paleontology of the Triassic formations in the Middle 

Rockies. Some of the rarest fossils in these Triassic 

formations are the nautiloid cephalopods. Interest hi 

this particular group of invertebrates was greatly stimulated by Dr. A. K. Miller of the University of Iowa. 

Identification of the few dozen specimens collected from

the Thaynes formation in southeastern Idaho was a 

relatively easy task. However, study of the great 

monographs by Triassic scholars such as Mojsisovics, 

Hauer, Hyatt, Arthaber, Diener, Kieslinger, etc., revealed a surprising lack of discussion or speculation as to 

the relationships of Triassic genera with the late Paleozoic forms. The same observation holds true for published monographs on late Paleozoic nautiloids by 

Miller, Kruglov, Hyatt, and others.

The present study is an attempt to review the 

status and phylogenetic relationships of late Paleozoic 

and Triassic nautiloids. The orthoceraconic nautiloids 

are not included in this report; only the coiled forms 

are discussed. Of the late Paleozoic families only 

those which were involved directly or indirectly in the 

ancestry of Triassic nautiloids are discussed. The 

ranges and geographic distribution of species in ep.ch 

genus are listed at the end of each generic discussion. 

The relationships of the genera have been established 

from all their characters. The value of certain morphological features in classification differs in the various 

phyletic units. One feature found to be of significance 

was the shape of the conch in cross section. Cross 

sections of many species are figured to show thenrelationships, and degrees of variability within genera. 

Most of the cross section drawings were obtained from 

the literature and reproduced at one size to facilitate 

comparison.

The taxonomic part of the text includes a discuss; on 

and description of all North American species of 

Triassic nautiloids. The collections available were 

those of the U. S. Geological Survey and the author's 

collections from southeastern Idaho. Late Paleozoic 

nautiloids are treated only as to families and genera, 

with the exception of one new subgenus and species. 

The original descriptions of most genera are included 

because many are to be found only in rare publications. 

It is hoped that this study, which systematically treats 

an invertebrate group on both sides of the PaleozcicMesozoic boundary, will be of value to those interested 

in the biological significance of the great systematic 

boundaries.

The author is greatly indebted to Dr. J. B. Rees; de 

Jr., who kindly arranged the loan of the specimens and 

devoted much time to the tedious task of checking speci-
AMERICAN TEIASSIC COILED NAUTILOIDS

men data. Many stimulating discussions on nautiloid 

taxonomy and evolution were held with N. D. Newell, 

A. K. Miller, R. H. Flower, and H. B. Stenzel, and 

analysis of the evolution of late Paleozoic and Triassic 

nautiloids was greatly facilitated by the splendid 

monographs on late Paleozoic nautiloids by A. K. 

Miller. Finally, the author is grateful to the Graduate 

School of the University of Illinois, which furnished 

the working facilities, equipment, and all the funds for 

preparation of the plates and figures.

OCCURRENCE

Triassic nautiloids are very rare in North America. 

Only 28 species distributed in 17 genera have been 

recorded in contrast to myriads of ammonites in many 

zones in the Triassic of western North America. 

About two tons of material collected in southeastern 

Idaho from the Lower Triassic ammonite-rich limestone 

containing Meekoceras yielded only one fragmentary 

specimen of an orthoceraconic nautiloid. In contrast 

to this scarcity of nautiloids, however, the Hosselkus 

limestone of Late Triassic age of California seems to contain abundant nautiloid remains. It has long been recognized that the nautiloids, after their almost explosive 

introduction in the Ordovician, declined steadily to the 

present. Nautiloid shells are not generally common 

throughout the late Paleozoic and Triassic. Part of 

this seeming scarcity is due to lack of interest in this 

group and lack of thorough collecting. Most of the 

collections available were made by field parties whose 

main objectives were not stratigraphic or paleontologic. 

The quality of some recent collections, especially those 

from Mexico, Nevada, and Alaska indicates that future 

collecting should be very profitable in these areas.

The occurrence of Triassic nautiloids is discussed 

below by regions. The distribution outside North 

America is not listed here but the geographic and 

geologic range of all species are listed in the discussion 

of each genus, in the systematic part of this paper.

MIDDLE ROCKY MOUNTAINS REGION

No nautiloids have been described from the Lower 

Triassic formations of the Middle Rocky Mountains region. The Dinwoody formation in Slight Canyon, west 

of Bear Lake, southeastern Idaho has yielded one specimen, Grypoceras (Grypoceras} mttleri, n. sp., and a very 

large fragment of the living chamber of a nautiloid that 

must have measured at least a foot in diameter came 

from pre-Meekoceras beds (Dinwoody formation) in 

Montpelier Canyon, southeastern Idaho.

The limestone with Meekoceras, of the Thaynes formation, which contains myriads of ammonites throughout 

southeastern Idaho is practically barren of nautiloids. 

Only one fragmentary "Orthoceras" has been found in

this very fossiliferous bed. The black shale w: th black 

limestone concretions about 500 ft above the F.mestone 

with Meekoceras, and referred to as the Columbites shale 

by Kummel (1943) has yielded a small but well-preserved nautiloid fauna. In four field seasons the 

author visited several outcrops in southeastern Idaho, 

and was able to collect about 40 specimens. The 

Columbites shale contains the following species:

Metacoceras (Mojsvaroceras) frenchi, n. sp. 

Germanonautilus montpelierensis, n. sp. 

Pleuronautilus (Enoploceras) newelli, n. sp. 

Pleuronautilus (Pleuronautilus) idahoensis, n. sp.

The Tirolites zone, which lies between the Meekoceras 

and Columbites beds of the Thaynes formation, in Paris 

Canyon, southeastern Idaho has yielded one specimen, 

described here as Pleuronautilus sp.

The Lower Triassic rocks of Montana are not as fossiliferous as those in southeastern Idaho. Only one 

specimen, described here as Pleuronautilus sp., from the 

Thaynes formation, is available for study.

No nautiloids have been reported from tbo Lower 

Triassic of Utah.

NEVADA

Few nautiloid specimens are available from Triassic 

formations of the Hawthorne and Tonopah Quadrangles, 

Nevada. From the Luning formation Germanonautilus 

sp. and Paranautilus sp. are recognized. TI Q. Gabbs 

formation has yielded Sibyllonautilus fargusoni, n. sp. 

Muller and Ferguson (1939) list Grypocercs cf. G. 

brahmanicum (Griesbach) from the Candelaria formation, Cosmonautilus cf. C. pacijicus Smith from the 

Luning formation, and from the Gabbs formation, 

Proclydonautilus spirolobus and Gonionautilus securis.

The Middle Triassic series of the Humboldt Range 

has yielded a fan* number of nautiloids, including:

Orthoceras campanile Mojsisovics 

Orthoceras blakei Gabb 

Paranautilus smithi n. sp. 

Paranautilus multicameratus (Gabb) 

Germanonautilus furlongi Smith 

Grypoceras (Grypoceras) whitneyi (Gabb)

At New Pass, Desatoya Mountains the Daonella zone 

has yielded the following species:

Germanonautilus johnstoni, n. sp. 

Germanonautilus furlongi Smith 

Grypoceras (Grypoceras) whitneyi (Gabb) 

Orthoceras blakei Gabb 

Paranautilus sp. 

Styrionautilus sp.

From the upper part of the Star Peak formation, West 

Humboldt Range, in shales carrying Pseudomonotis subcircularis, Smith (1927) has described Syringoceras 

spurri Smith.
CLASSIFICATION OF LATE PALEOZOIC AND TRIASSIC NAUTILOIDS

CALIFOBNIA

The largest and most varied Triassic nautiloid fauna 

of North America occurs in the Upper Triassic series of 

California. The Tropites subbullatus zone of the Hosselkus limestone, Brock Mountain, Shasta County, 

California, has yielded the following fauna:

Orthoceras shastense Hyatt and Smith

Prodydonautilus hessi (Smith)

Proclydonautilus squawensis n. sp.

Prodydonautilus spirolobus (Dittmar)

Prodydonautilus stantoni Smith

Prodydonautilus triadicus Mojsisovics

Prodydonautilus ursensis Smith

Oxynautilus acutus (Hauer)

Gryponautilus cooperi Smith

Metacoceras (Mojsvaroceras) turneri Hyatt and Smith

Cosmonautilus dilleri Hyatt and Smith

Cosmonautilus hersheyi Smith

Cosmonautilus pacificus Smith

Cosmonautilus shastensis Smith

The zone of Parapopanoceras (Anisian), Inyo County, 

California, has yielded Orthoceras sp. indet. (Smith 1914, 

p. 6).

CANADA

Only two species of Triassic nautiloids have been 

described from the extensive Triassic sequence of 

Western Canada: SibyUonautilus liardensis (Whiteaves) 

from the Liard formation, Liard Eiver, northeastern 

British Columbia (see McLearn 1947, p. 10) and 

Proclydonautilus natosini McLearn and Proclydonautilus 

sp. from Norian beds, Sikanni Chief Eiver Basin, 

British Columbia (McLearn 1946, pp. 2, 3). Proclydonautilus natosini also occurs in the Pardonet beds, 

Pardonet Hills, Peace Eiver foothills, British Columbia. 

From beds containing the Nathorstites fauna McLearn 

(1947) reports "Nautilus" sp. at Hage Creek, Sikanni 

Chief Valley and from outcrops a little west of mile post 

386 on the Alaskan Highway. The Toad formation has 

only yielded "Nautilus" sp. and Orthoceras sp. (McLearn 

1946, 1948). No nautiloids are known from the Lower 

Triassic formations of British Columbia (McLearn 

1945).

ALASKA

The extensive Upper Triassic formations of Alaska 

have yielded relatively few nautiloids. The best summary of the known Triassic invertebrates in Alaska is 

by Martin (1916, 1926). The Chitistone limestone of 

the Chitina Valley contains Orthoceras cf. 0. shastense 

Hyatt and Smith, Orthoceras sp. (Martin, 1926, p. 15) 

and Pleuronautilus alaskensis, n. sp. The Upper 

Triassic rocks on Gravina Island contain Cosmonautilus? 

(Martin 1926, p. 71). Mojsvarocerasf has been reported 

from Upper Triassic limestones 7 miles southeast of 

Kake, on Kupreanof Island. The Upper Triassic limestone near Nation Eiver, Yukon Valley contains Germanonautilus brooksi Smith, Germanonautilus sp. and 

Orthoceras sp. The collections under study contair a 

specimen of Germanonautilus sp. from Cape Kekurnoi, 

between Gold and Alinchak Bays, Alaska Peninsula. 

The Upper Triassic rocks exposed at Herring Bay, 

Admiralty Island, Alaska have yielded a fragmentary 

but very well preserved specimen of Phloioceras sp.

MEXICO

The Upper Triassic Barranca formation of Sono^a, 

Mexico, has yielded a few nautiloids (see Keller, 1928, 

and King, 1939). At the Mina el Antimonio, in beds 

containing a rich Karnian fauna, the following species 

have been recognized:

Proclydonautilus triadicus (Mojsisovics)

Cosmonautilus pacificus Smith

Orthoceratoids

The collections of the U. S. Geological Survey include 

three specimens, and a plaster cast of a specimen in the 

Institute Geologico de Mexico, that are referable to 

Cosmonautilus dHleri Hyatt and Smith. These specimens also came from the locality of Mina el Antimonio.

SOUTH AMERICA

Triassic cephalopods are indeed rare in South America. 

The only Triassic nautiloid known to the author 

is one he collected in the upper Triassic Utcubamba 

formation in Suta Valley, a tributary of the Utcubamba 

River, northern Peru (Kummel, 1950). The specimen 

is immature and silicified. It consists of only one-third 

volution with a rounded whorl section and a subcentral 

siphuncle. The specimen can be identified only as 

Syringonautilusl'.

CLASSIFICATION OP LATE PALEOZOIC AND 

TRIASSIC NAUTILOIDS

During the past three decades active interest in 

nautiloid cephalopods has been revived by Flower, 

Foerste, Miller, Kieslinger, Rruglov, Schindewclf, 

Spath, Stenzel, Strand, Teichert, Troedsson, and others. 

Only Kieslinger concerned himself with Triassic nr.utiloids, the others concentrating on Palezoic and po^tTriassic nautiloids. Fine monographs on late Paleozoic nautiloids of North America have been published 

in the last two decades by Miller and various coworkers. 

As pointed out by Miller and Youngquist (1949, p. 15)

* * * the classification of the nautiloid cephalopods is not 

in as satisfactory condition as is that of the ammonoids and mist 

other major groups of fossil invertebrates, and the best existing 

systematic arrangement seems to be that which Hyatt publisl ">d 

in 1900 in the Zittel-Eastman Text-book of paleontology.

These authors further emphasize the tentative nature 

of this system and are cognizant of its many weaknesses. Flower and Kummel (1950) proposed a com-
AMERICAN TRIASSIC COILED NAUTILOIDS

pletely revised classification of the Nautiloidea placing 

the 75 families of nautiloids into 14 orders.

Hyatt (1900) placed the Triassic nautiloid genera 

known at that time in four families, the Grypoceratidae, 

Clydonautilidae, Rhineceratidae, and Pleuronautilidae. 

Moj sisovics two years later published the first comprehensive taxonomic treatment of Triassic nautiloids and accepted only one of Hyatt's families. He (Moj sisovics) also 

classified the twenty genera of Triassic nautiloids known 

at that time into four families, the Clydonautilidae, 

Syringonautilidae, Gryponautilidae, and the Temnocheilidae, using the presence or absence of an annular 

lobe as a primary character in his classification. Temnocheilidae (Moj sisovics) is synonymous with Tainoceratidae of Hyatt. They include essentially the same 

Paleozoic genera, but Moj sisovics included several 

Triassic genera. Diener (1919) took exception to 

Moj sisovics' classification because he had overemphasized the importance of the annular lobe. Diener 

combined the genera that Moj sisovics had included in 

the Clydonautilidae and Gryponautilidae into one 

family, the Grypoceratidae. Diener retained the 

Temnocheilidae and Syringonautilidae as proposed by 

Mojsisovics. This taxonomic scheme was also followed 

by Kieslinger (1924). Since Kieslinger's publication 

there has been no publication devoted solely to Triassic 

nautiloids, although nautiloids have been included in 

numerous general faunal studies.

A marked handicap in most taxonomic studies of 

Triassic nautiloids has been an insufficient understanding of late Paleozoic nautiloids and their relationships with the Triassic forms. Fortunately, owing to 

the work of Miller and others our knowledge of Pennsylvanian and Permian nautiloids has increased greatly 

in the past twenty years. In preparation of this report, 

data on the geologic and geographic distribution of 

most late Paleozoic nautiloids have been assembled. 

The writer was impressed by the general lack of statements as to the evolutionary status of the various 

taxonomic groups, but in the early papers such speculation was impossible or unwise owing to incomplete 

knowledge. Restudy of all late Paleozoic genera with 

the aim of presenting a reasonable phylogeny in accordance with our present state of knowledge was undertaken 

to determine the probable phylogenetic lines from which 

the Triassic nautiloids developed.

The most significant fact brought out in this study 

is the close genetic relationship of many Triassic and 

late Paleozoic genera. Several well-known Triassic 

genera are considered as direct evolutionary descendants that replaced the Paleozoic genera. In this 

report the Triassic nautiloids are placed in the Tainoceratidae Hyatt (Temnocheilidae Mojsisovics), Syringonautilidae Mojsisovics, Grypoceratidae Hyatt, Paranautilidae Kummel, Clydonautilidae Hyatt, and Gonionautilidae Kummel. The Tainoceratidae, Grypoceratidae, and Paranautilidae include both late Paleozoic and Triassic genera.

The interpretation of phylogenetic relationships 

presented here is not radically different from the 

conclusions of earlier workers; however, there are 

significant differences. All genera of families involved 

in the evolution of late Paleozoic-Triassic nautiloids, 

and their inferred position in nautiloid evolution are 

discussed in the taxonomic part of this report.

The system presented here can be only tentative. 

Frequently the data available are so meager that one 

can only make the most logical proposal possible and 

wait for additional information. A study like this is 

always open to criticism from many sides. However, 

to those who feel our knowledge has as yet not attained 

a sufficient level the only answer possible is that we 

probably never will know all the answers within the 

limits of paleontological research. It is felt that if 

such studies stimulate action as well as reaction they 

have been at least partly successful.

The classification used in this report is as follows:

Family Tainoceratidae Hyatt, 1883 

Genus Temnocheilus M'Coy, 1844

Genotype: Nautilus (Temnocheilus) coronatus

M'Coy 

Genus Foordiceras Hyatt, 1893

Genotype: Nautilus goliathus Waagen 

Genus Metacoceras Hyatt, 1883

Genotype: Nautilus (Discus) sangamoninsis Meek

and Worthen 

Subgenus Mojsvaroceras Hyatt, 1883

Subgenotype: Temnocheilus neumayri Mojsisovics 

Genus Parametacoceras Miller and Owen, 19^4

Genotype: Parametacoceras bellatulum Miller and

Owen 

Genus Tainoceras Hyatt, 1883

Genotype: Nautilus quadrangulus McC'iesney 

Genus Cooperoceras Miller, 1945

Genotype: Cooperoceras texanum Miller 

Genus Tainionautilus Mojsisovics, 1902

Genotype: Nautilus transitorius Waagen 

Genus Tirolonautilus Mojsisovics, 1902

Lectotype: Nautilus crux Stache 

Genus Aulametacoceras Miller and Unklesbay, 1942 

Genotype: Aulametacoceras mckeei 3filler and

Unklesbay 

Genus Germanonautilus Mojsisovics, 1902

Genotype: Nautilus bidorsatus Schlotheim 

Genus Thuringionautilus Mojsisovics, 1902

Genotype: Trematodiscus jugatonodosus Zimmermann 

Genus Pleuronautilus Mojsisovics, 1882

Genotype: Pleuronautilus trinodosus Mojsisovics 

Subgenus Enoploceras Hyatt, 1900

Subgenotype: Nautilus wulfeni Mojsisovics 

Subgenus Holconautilus Mojsisovics, 1902 

Subgenotype: Nautilus semicostatus Beyrich
GEOLOGIC HISTORY

Family Tainoceratidae, Hyatt, 1883—Continued

Genus Pleuronautilus Mojsosovics, 1882—Continued 

Subgenus Anoploceras Hyatt, 1900

Subgenotype: Nautilus ampezzanus Loretz 

Subgenus Encoiloceras Hyatt, 1900

Subgenotype: Nautilus superbus Mojsisovics 

Subgenus Trachynautilus Mojsisovics, 1902

Subgenotype: Pleuronautilus subgemmatus Mojsisovics 

Genus Phloioceras Hyatt, 1883

Genotype: Nautilus gemmatus Mojsisovics 

Family Grypoceratidae Hyatt, 1900 

Genus Grypoceras Hyatt, 1883

Genotype: Nautilus mesodiscus Hauer 

Subgenus Domatoceras Hyatt, 1891

Subgenotype: Domatoceras umbilicatum Hyatt 

Subgenus Plummeroceras n. subgen.

Subgenotype: Plummeroceras plummeri, n. sp. 

Genus Gryponautilus Mojsisovics, 1902

Genotype: Nautilus galeatus Mojsisovics 

Genus Menuthionautilus Collignon, 1933

Genotype: Nautilus (Menuthionautilus) kieslingeri

Collignon 

Genus Sienopoceras Hyatt, 1893

Genotype: Phacoceras dumblei Hyatt 

Genus Stearoceras Hyatt, 1893

Genotype: Endolobus gibbosus Hyatt 

Genus Pselioceras Hyatt, 1883

Genotype: Nautilus ophioneus Waagen 

Genus Titanoceras Hyatt, 1884

Genotype: Nautilus ponderosus White 

Family Syringonautilidae Mojsisovics, 1902 

Genus Syringonautilus Mojsisovics, 1902

Genotype: Nautilus lilianus Mojsisovics, 1882 

Genus Syringoceras Hyatt, 1894

Genotype: Nautilus granulosostriatus Klipstein 

Genus Juvavionautilus Mojsisovics, 1902

Genotype: Nautilus heterophyllus Hauer 

Genus Oxynautilus Mojsisovics, 1902

Genotype: Nautilus acutus Hauer 

Genus Clymenonautilus Hyatt, 1900

Genotype: Nautilus ehrlichi Mojsisovics 

Family Paranautilidae Kummel, 1950

Genus Paranautilus Mojsisovics, 1902

Genotype: Nautilus simonyi Hauer 

Genus Indonautilus Mojsisovics, 1902

Genotype: Nautilus kraffti Mojsisovics 

Genus Sibyllonautilus Diener, 1915

Genotype: Nautilus sibyllae Mojsisovics 

Family Clydonautilidae Hyatt, 1900

Genus Styrionautilus Mojsisovics, 1902

Genotype: Nautilus styriacus Mojsisovics 

Genus Proclydonautilus Mojsisovics, 1902

Genotype: Nautilus griesbachi Mojsisovics 

Genus Cosmonautilus Hyatt and Smith, 1905

Genotype: Cosmonautilus dilleri Hyatt and Smith 

Genus Callaionautilus Kieslinger, 1924

Genotype: Callaionautilus turgidus Kieslinger 

Genus Clydonautilus Mojsisovics, 1882

Genotype: Nautilus noricus Mojsisovics 

Family Gonionautilidae Kummel, 1950

Genus Gonionautilus Mojsisovics, 1902

Genotype: Nautilus securis Dittmar 

232820—53———2

GEOLOGIC HISTORY

The nautiloids with their long geologic history make 

au excellent group for evolutionary studies. T/e 

approximately 630 genera of nautiloids represent a 

complex evolution extending from the Late Cambrian 

to the Recent epoch. From the Pliocene to the 

Recent epoch only one genus, Nautilus, is left of what 

was once an important and abundant invertebrate 

group. The nautiloids illustrate a peculiar evolutionary pattern in that they attain a peak of diversity soon 

after their introduction into the fossil record. Figure 1 

is a bar chart of the number of genera per period. Tre 

data upon which this chart was made were kindly 

furnished by Dr. Curt Teichert. The earliest nautiloids, 

those of the Ordovician, are represented by far the me *t 

genera; in fact, there are more than twice as many 

nautiloid genera in the Ordovician as in the Silurian. 

This great discrepancy would, of course, be decreased 

if the graph were plotted in terms of the number of 

genera per million years. Miller (1949, p. 231) suggests the Silurian as the "heyday of the nautiloids, 

insofar as both numbers and kinds are concerned." 

The number of Ordovician and Silurian species of 

nautiloids is not known, but the number of genera is 

much larger for the Ordovician.

By the end of the Ordovician most of the major 

stocks of nautiloids were well established. One stock, 

the "Orthochoanites," was destined to give rise to the 

modern Nautilus. Most of the other stocks were short 

lived. The holochoanitids and mixochoanitids died 

out in the Silurian, the cyrtochoanitids lived through 

the Paleozoic era.

It has been known generally that there was a steady 

and progressive decline in the nautiloids from the 

Ordovician onward. This fact is well illustrated in 

figure 1. The large breaks in the distribution cor^e 

between the Ordovician and the Silurian, between the 

Devonian and the Carboniferous and to a lesser degree 

between the Triassic and Jurassic periods. Although 

the number of genera of post-Devonian nautiloids was 

never great for any one period, there were times of gre.^-t 

expansion in numbers of individuals and species. 

Miller (1949) has shown that early Cenozoic nautiloids 

were very abundant in many widely scattered places 

in the world. Kieslinger (1925) has noted a secondary 

peak of development during the Late Triassic. Tlis 

aspect of nautiloid history will be the concern of tl is 

paper.

There are about 250 established species of TriasHc 

nautiloids placed in 30 genera (no species identified as 

cf. or aff. with recognized species are included in this 

number). The distribution of species per epoch is 

illustrated in figure 2. Early Triassic (Scythian)
6 AMERICAN TRIASSIC COILED NAUTILOIDS

250 —

200 —

150 —

100 —

50

40

30

20

10

0

lol

.

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FIOUEE 1.—Bar chart showing number of genera of nautUoid cephalopods present in each period. (Data from C. Teichert, personal communication.)

nautiloids are relatively rare as to numbers of species 

and inclividuals. By the Anisian the nautiloids became very widespread and most of the important genera 

had become established. The decline in numbers of 

species in the Ladinian is difficult to explain. How 

much of this decline is only apparent, and due to lack 

of a paleontological record is not known. The evolution 

of the genera and families shows no significant break in 

the Ladinian. About 90 species occur in the Karnian, 

and less than half that number (about 35) in the Norian. 

The distribution of the genera of Triassic nautiloids 

is illustrated in figure 3. In the Scythian the nautiloids 

are represented by members of 2 late Paleozoic families: 

Grypoceras and MenuthionautUus (Grypoceratidae), 

and Pleuronautilus, Enoploceras, Tainionautilus, Mojsvaroceras, and GermanonautUus (Tainoceratidae). Grypoceras and Mojsvaroceras are considered direct evolutionary offshoots of the basic evolving stock of their 

respective families. Tainwnautttus and MenuthionautUus are not present in younger Triassic ro°-ks. In 

the Anisian, 8 new genera are introduced and tl °> actual 

evolutionary radiation of Triassic nautiloids begins. 

The oldest species of the Syrmgonautilidae and Clydonautilidae are found in the Anisian. The genera having their first Triassic species in the Anisian are Paranautilus, SibyllonautUus, StyrionautUus, Syringoceras, 

SyringonautUus, TrachynautUus, Anoploceras, r,nd Holconautttus. ParanautUus is believed to include 2 possible Permian species; however, no Scythian species are 

known. The radiation of the pleuronautilidf is well 

established during the Anisian. There may b?, justification in placing all these forms in the family Pleuro-
EVOLUTION

JOG'-

90—

60 —

50 —

40-

30 —

20 —

10

0 —

Scythian Anisian Ladinian Karnian Norian

FIGUEE 2.—Bar chart showing total number of species of Triassic nautiloids in each

epoch.

nautilidae as proposed by Hyatt (1900), however, 

tentatively the author is following Mojsisovics and 

retaining them in the Tainoceratidae.

During the Ladinian only 3 genera, Phloioceras, 

Thuringwnautilus, and Clydonautilus got their start; of 

these only Clydonautilus turned out to be a virile stock. 

There are 16 genera represented in the Ladinian. The 

acme was attained in the Karnian epoch with 20 genera 

and approximately 90 species of nautiloids. Only 4 

genera (Proclydonautttus, Cosmonautttus, Gryponautilus, 

Encoiloceras) made their debut in the Karnian, whereas 

many of the well-established genera (including Trachynautilus, Encoiloceras, Anoploceras, Holconautilus, Pleuronautilus, Mojsvaroceras, and Germanonautilus) make 

their last appearance. Only 2 Karnian species, Tainoceras klipsteini and Aulametacoceras rectangularis, are 

placed in Permian genera. Tainoceras is a common 

Pennsylvanian and Permian nautiloid genus, and the 

Karnian species is assigned to it mainly on similarities 

of ornamentation. Aulametacoceras was originally described from beds of Leonard age in Arizona, and has 

only one Permian species. Whether placing Karnian 

species in Permian genera (in the absence of any intervening forms) is correct only time will tell.

There is only a slight decrease in total number of 

genera in the Norian (from 20 to 18). This is due

mainly to the introduction of 6 new genera — Juvamona^itilus, OxynautUus, Clymenonautttus, Indonautilus, Gonionautttus, and Callaionautilus. Only Juvavwnautilus, 

has more than one species or an extensive geograplic 

distribution. Menutfiionautilus in the Scythian, Thuringionautilus in the German Keuper, and Encoilocer^ 

in the Karnian, are also monotypic genera. In the 18 

genera represented in the Norian, about 80 percent of 

the species are in 5 genera — ParanautUus, Clydonautilus, 

Proclydonautttus, Enoploceras, and Juvavionautilus. 

Most of the remaining genera are represented by only

one species each.

EVOLUTION

The whole evolutionary complex of late Paleozoic and 

Triassic nautiloids more or less follows a generalization 

concluded by Kieslinger (1925, p. 107) from his study 

of the Late Triassic nautiloids of Timor that the 

degree of involution and ornamentation are inverseJy 

proportional. There are eight families of late Paleozoic 

nautiloids (see Miller and Youngquist, 1949, p. v) but 

only the Grypoceratidae, Tainoceratidae, and Liroceratidae are thought to be involved in the direct ancestry 

of Triassic nautiloids and are discussed in this report. 

The Liroceratidae does not include Triassic genera. 

The families Paranautilidae, Ciydonaituiidae, Gonio20 —

is —

10 —

o —

Scythian Anisian Ladinian Karnian Norian

FIGUEE 3.—Bar chart showing number of genera of nautiloid cephalopods present in 

each epoch (light stippling) and number of new genera appearing for the first true 

in each epoch of the Triassic period (dense stippling).
8 AMERICAN TRIASSIC COILED NAUTILOIDS

.—Diagram showing inferred phytogeny and geologic distribution of late Paleozoic and Triassie coiled nautiloids.
EVOLUTION 9

nautilidae, and Syringonautilidae are confined to the 

Triassic (text fig. 4).

These seven families can be grouped into two phyletic 

lines that show a great deal of convergence throughout 

their history. The first group (the Tainoceratidae) 

includes most of the ornamented, generally evolute, 

nautiloids that have subquadratic whorl sections and 

very simplified sutures. The second, more complex, 

phyletic group includes forms that are smooth, generally involute, and tend towards modification and complication of the suture pattern. Three subdivisions of 

this group can be recognized. The first subgroup includes forms that have a smooth, involute conch and 

highly modified sutures (Clydonautilidae and Gonionautilidae). The second subgroup comprising the Paranautilidae and Liroceratidae, have a smooth, involute conch 

but very simple, practically straight, sutures. The third 

sub-group (Grypoceratidae and Syringonautilidae) is less 

homogeneous, and includes smooth, evolute to involute 

conchs, generally with flattened venters. The sutures 

include a broad lateral lobe with some modifications 

of the suture on the venter.

Although the grouping of late Paleozoic and Triassic 

families reveals the general evolutionary picture there 

are numerous anomalies. The acquisition of ornamentation occurred repeatedly in all or some species of 

genera Clydonautilidae and Grypoceratidae and in a 

sense shows a convergence towards some forms of the 

Tainoceratidae. Cosmonautilus, for example, has developed nodes on the ventral shoulders in some stages of its 

growth. Hyatt and Smith (1905, p. 207) used this as 

evidence of an ancestry in the genus Metacoceras, but 

the present author does not believe that this derivation 

is correct. In all other characters and especially its 

suture Cosmonautilus agrees with representatives of the 

Clydonautilidae. Callaionautilus is another ornamented genus of Clydonautilidae. Clydonautilus cicatricosus shows characters transitional to Cosmonautilus 

and the Tainoceratidae in having nodose ornamentation 

with a typical clydonautilid suture. A few other 

species of Clydonautilus show low folds on the flanks. 

Domatoceras, Gryponautilus, and Plummeroceras of the 

Grypoceratidae have nodes developed on either or both 

the ventral and umbilical shoulders in some or all of 

their species. However, the basic pattern of the conch 

and suture, are typical of the Grypoceratidae. The 

nodes and other ornamentation, especially developed 

on essentially smooth stocks are probably effects of late 

mutations superimposed on established conch patterns 

probably have no phyletic significance but merely 

represent local adaptations. However, the nature of 

adaptive advantage that ornamentated forms have 

over non-ornamented forms is not known for these 

invertebrates.

The conch pattern of each phyletic line retain, 

within broad limits, a certain homogeneity, but each 

shows some radiation that converges towards radiations 

of other groups. If each basic conch pattern reflects 

an adaptation to a certain environmental niche or 

way of life it appears that each phyletic line was well 

diversified and contributed toward the various environmental types.

Certain basic conch patterns were acquired independently by genera in one or more families during the 

late Paleozoic and Triassic. Highly compressed involute conchs in the late Paleozoic are confined to the 

genus Stenopocems. Somewhat similar conch patterns, 

but of a more truly oxycone type, are seen in Gryponautilus and Oxynautilus of the Late Triassic. Proclydonautilus ermollii and StyrionautUus discoidalis of 

the family Clydonautilidae also have highly compressed involute conchs very similar to that of Stenopoceras. Domatoceras and Plummeroceras have compressed, evolute conchs with flattened venters. Some 

species of Domatoceras show transition to Stenopoceras. 

In the Triassic Juvamonautilus has a somewhat similar 

conch pattern. Menuthionautilus appears to combine 

features of domatoceratid and stenopoceratid con",h 

patterns. Sibyllonautilus with its depressed but rapicUy 

expanding conch is very reminiscent of Acanthonautilus 

of the late Paleozoic.

The greatest diversity in conch pattern intragenericaJly 

is found in the Clydonautilidae, the family which a] so 

has the most highly modified sutures. The Taiuoceratidae, which include most of the ornamented late 

Paleozoic and Triassic nautiloids, maintain a remarkal^y 

uniform conch pattern, with only minor diversity. 

Some species in this family, especially in Mojsvarocerv-s 

and Germanonautilus, evolved toward loss of ornamentation, but did not greatly increase their involution.

Much of the similarity of the conch patterns of the 

genera and species of two families can be explained by 

convergence and adaptations to similar environments 

or modes of life. The repetition of similar conch 

patterns within a phyletic line may be partly explained 

on the same basis. Domatoceras and Juvamonautilus 

are very similar in conch patterns and each is thought 

to have given rise to highly compressed, involute 

genera, Stenopoceras and Oxynautilus. JuvamonautHus 

belongs in the family Syringonautilidae, which apper.rs 

to have its origin in the Grypoceratidae. Gryponautilus, 

also of the Grypoceratidae, has a conch pattern reminiscent of a slightly inflated Stenopoceras and is somewb at 

similar to Oxynautilus. Acanthonautilus of the Liroceratidae has a counterpart in Sibyllonautilus of the 

Paranautilidae, the latter family being derived from 

the former.

In the example of the Grypoceratidae and Syringo-
10 AMERICAN TRIASSIC COILED NAUTILOIDS

nautilidae the compressed, involute radiation comes 

near the beginning and near the end of the history of 

these families. This does not appear to be the case in 

the other example involving the Liroceratidae and 

Paranautilidae. The amount and kind of modifications 

that can be made on any one nautiloid conch pattern 

is limited. Stenopoceras, Gryponautilus, and Oxynautilus 

or Domatoceras and Juvavionautilus are similar in their 

basic conch pattern but differ in other features. The 

highly compressed involute shell was acquired by 

several distinct branches of the ammonoids throughout 

much of their history, and is also seen in the Cretaceous 

nautiloid HeminautUus. This form of the shell must 

have had some adaptive value and, when the genetic 

potential of the parent and the environment were in accord, it was possible to develop new stocks with this 

conch pattern completely independent of any previous 

or future radiation in this direction.

Most late Paleozoic and Triassic nautiloids have very 

simple suture patterns. Within the Tainoceratidae, 

sutures with shallow ventral and lateral lobes are the 

rule. The only exception is HolconautUus, which has a 

ventral saddle—a type of modification of the suture 

expressed in other completely independent lines. The 

Grypoceratidae, which have higher whorls than the 

Tainoceratidae generally, have a broad lateral lobe, but 

also show some modification on the ventral lobe. 

Plummeroceras has a very deep ventral lobe, almost 

equal to the width of the flattened venter. However, 

some species of Domatoceras are transitional to Plummeroceras in this character. Grypoceras mesodiscus of 

the Triassic has a deep ventral lobe similar to that 

of Plummeroceras. Most of the Syringonautilidae have 

highly simplified sutures. Juvavionautilus has a ventral 

saddle flanked by broad lateral lobes. Clymenonautilus 

has a conch pattern placing it in the Syringonautilidae, 

but shows strong convergence to the Clydonautilidae in 

the deep and peculiar lateral lobe of its suture. The 

Paranautilidae have simple, almost straight, sutures.

The only family that shows definite evolutionary 

changes in the suture is the Clydonautilidae, which also 

attained the highest diversity and modifications of the 

septa of any late Paleozoic and Triassic nautiloids. 

They are rivaled in complexity only by the early 

Cenozoic genera Aturia, Aturoidea, and Hercoglossa. 

The various genera of this family are largely defined on 

modifications of the suture on the venter, except for 

Cosmonautilus and CallaionautUus. For each genus 

there is a surprising uniformity in overall plan of the 

suture. The conch pattern, however, varies greatly.

Among late Paleozoic nautiloids the annular lobe 

has been found only in some species of Stearoceras. The 

annular lobe is characteristic of many Triassic genera; 

it is absent in the Clydonautilidae, and in all Paranautilidae except Sibyttonautttus. Welter (1914, p. 213) 

describes and illustrates a specimen of ProclydcnautUus 

gasteroptychus timorensis that possesses an annular 

lobe. Mojsisovics used the annular lobe as a primary 

criterion in his taxonomic scheme for Triassic nautiloids. 

Most later authors do not consider this feature diagnostic by itself. In several post-Triassic nautiloid 

genera the annular lobe disappears early in the ontogeny 

(Spath, 1927b). The writer believes that the annular 

lobe generally cannot be used by itself to distinguish 

groups of taxonomic rank higher than subge.ius and 

genus.

The siphuncle in most late Paleozoic and Triassic 

nautiloids remains nearly central. In the late Paleozoic only Solenochilus has its siphuncle in a marginal 

position. Menuthionautilus of the Scythian of Madagascar and Pakistan also has its siphuncle in a marginal 

position. Syringoceras has its siphuncle in a near 

marginal position, and on this criterion alone is separated from Syringonautilus. Data on the position of 

the siphuncle of m6st species are unpublished.

Most families of late Paleozoic and Triassic nr.utiloids 

follow a similar mode or pattern in their evolution: a 

central virile stock that slowly evolved from the 

Pennsylvanian through the Triassic, and periodically 

produced nearly equal virile stocks and isolated aberrant 

groups. The modifications of the aberrant groups 

are merely added to or superimposed on the conch 

pattern of the central stock. The Permian-Triassic 

boundary is not a very significant one in terms of 

nautiloid evolution. The two families, namely 

Tainoceratidae and Grypoceratidae, which be^t illustrate the above observations show only minor changes 

at the Permian-Triassic boundary.

In the Tainoceratidae, the main evolving stock is 

that of Metacoceras. This genus has a subquadrate 

cross section of the whorl, is somewhat evolute, and 

bears nodes on the shoulders. It is a very prolific 

stock in both numbers of species and individuals, and 

has a world-wide distribution in the Pennsylvanian 

and Permian. The late Paleozoic evolution of this 

group shows no definite trends; Permian and Pennsylvanian species are quite similar. Met^-coceras 

evolved directly into or is replaced by Mojsw-roceras 

in the Triassic. Mojsvaroceras has the same general 

pattern of the conch as Metacoceras, and differs only 

in tighter coiling and the acquisition of an annular lobe. 

All of the remaining genera of the Tainoceratidae are 

either direct or indirect offshoots of the MetacocerasMojsvaroceras line. Each of these offshoots is 

characterized by a characteristic pattern of ornamentation, or modification of the conch shape, but at the 

same time shows clear affinities to Metacoceras. Many 

of these descendant forms have very narrow geographic
EVOLUTION 11

distributions and stratigraphic ranges. It is very 

likely that they are the result of adaptations to changes 

in environmental conditions.

The most virile offshoot from Metacoceras is the complex of genera and subgenera evolving around Pleuronautilus. This group includes most of the ribbed, subquadratic late Paleozoic and Triassic nautiloids. 

PleuronautUus seems to have arisen in early Permian 

time, and to have remained a rather singular and undiversified stock throughout the Permian. However, 

in the Triassic, and especially during the Anisian, the 

group began to radiate in many directions, and produced a complex association of highly ornamented 

nautiloids. Each subgroup of the pleuronautilid complex is characterized by a generally distinctive pattern 

of ornamentation or modification of the conch shape. 

Perhaps Hyatt (1900) was justified in placing this group 

in a separate family.

The Grypoceratidae have an evolutionary pattern 

very similar to that of the Tainoceratidae. Domatoceras and Grypoceras have the same relationships as 

Metacoceras and Mojsvaroceras. Domatoceras has an 

evolute compressed conch with a tabulate venter and 

is replaced in the Triassic by Grypoceras which is more 

involute, the venter more rounded, and the suture 

somewhat modified. The end members of this evolutionary line are quite different but there are numerous 

transitional forms. The offshoots of the DomatocerasGrypoceras line are characterized by the extreme development of usually one of three main morphological 

changes that express the evolution in the parent stock. 

The trend towards involution is seen in Stenopoceras, 

MenuthionautUus, and Gryponautilus. . Hounding of the 

ventral region of the conch is well developed in Grypoceras, but also expressed in Pselioceras, MenuthionautUus, and even in some Stenopoceras. Modification 

of the suture in the parent stock is mainly in development of a deeper ventral lobe adjoined by a large, 

broad, lateral lobe. In the parent stock this transition 

appears to be gradual. The subgenus Plummeroceras 

developed an extremely deep ventral lobe on a typical 

domatoceratid conch; the suture actually resembles that 

of some Late Triassic grypoceratids.

Stearoceras and Titanoceras of the Grypoceratidae 

are not fully understood but appear to be independent 

lines not involved in the Domatoceras-Grypoceras trend.

The Syringonautilidae are confined to the Triassic. 

They may have been derived from Stearoceras-Domatoceras transition complex in the Grypoceratidae. 

Syringonautilus and Syringoceras are very similar except for the position of the -siphuncle. The writer 

considers them to be independent and parallel lines 

developing from the Grypoceratidae. Syringonautilus

appears to have given rise to three aberrant offshoots 

in the Norian. These are Juvavionautilus, Oxynaut''lus, 

and Clymenonautilus. Juvavionautilus has a ccnch 

pattern very similar to that of Domatoceras except for 

a more rounded venter. Oxynautilus has a very compressed, involute conch similar to that of Stenopoceras. 

Clymenonautilus has a conch pattern like that of some 

grypoceratids but its suture develops a peculiar deep 

lateral lobe. Each of these Late Triassic offshoots of 

Syringonautilus takes on conch patterns resembling 

those seen in the Grypoceratidae, the ancestral group 

of the Syringonautilidae.

The evolutionary patterns in the Tainoceratidae 

Grypoceratidae, and Syringonautilidae are expressed 

primarily in the shape of the conch, degree of involution, and types of ornamentation, and only to a minor 

degree on modifications of the suture. The Liroceratidae, Paranautilidae, Clyclonautilidae, and Goniorautilidae are characterized by involute conchs, generally 

devoid of ornamentation, and by a tendency towards 

extreme modification of the suture in the Clydorautilidae and Gonionautilidae. In all of these families 

there is a constancy in the suture pattern for any 

particular generic assemblage but at the same time 

the conch pattern may vary tremendously.

The Liroceratidae are a closely related group of 

several independent lines of Pennsylvanian and Permian 

nautiloids. The Paranautilidae are thought to be 

derived from Liroceras in the Permian. This family has 

a very simple, globular, smooth conch with an almost 

straight suture. Paranautilus is the main stock that 

gave rise to two aberrant developments and most 

important, it was ancestral to the Clydonautilidae. 

The Clydonautilidae show extreme modification of the 

suture. The complexity of the suture in such gerera 

as Proclydonautilus, Clydonautilus, and Cosmonautilus 

is rivaled only by early Cenozoic forms like Hercoglo*sa, 

Aturoidea, and Aturia. The suture on the ventral 

region displays the most modification and is a feature of 

prime importance in distinguishing the various genera. 

The Gonionautilidae are represented by only one species, 

distinguished by its suture. This monotypic form 

represents the acme in sutural development of Triable 

nautiloids.

One aberrant Permian form from Timor, "Aganides" 

bitauniensis Haniel (1915), has the conch form of an 

involute domatoceratid, but its suture (with its deep 

bluntly pointed ventral lobe and a very deep as^nnmetrical and pointed lateral lobe) resembles those of 

the Late Triassic Clydonautilidae. "Aganides" litauniensis most surely belongs in a new genus, but the 

writer refrains from proposing one without actual 

specimens to study.
12 AMERICAN TRIASSIC COILED NAUTILOIDS

SYSTEMATIC PALEONTOLOGY 

Family TAINO CERATIDAE Hyatt, 1883

Some of the most characteristic nautiloids in the late 

Paleozoic and Triassic sedimentary rocks are the 

ornamented forms bearing ribs, nodes, and spines. 

Most of these ornamented forms are placed in the 

family Tainoceratidae. When Hyatt first established 

this family he included in it a wide variety of forms. 

These are Trocholites Conrad and Hall, Plectoceras 

Hyatt, Litoceras Hyatt, Diadiploceras Hyatt, Metacoceras Hyatt, Tainoceras Hyatt, Mojsvaroceras Hyatt, 

Grypoceras Hyatt, Clydonautilus Mojsisovics, Enclimatoceras Hyatt, Hercoglossa Conrad, and Aturia Bronn. 

In his final work on the classification of the nautiloids, 

Hyatt (1900, p. 524) placed in this family Tainoceras, 

Temnocheilus, Foordiceras, Metacoceras, Coelogasteroceras, and Diadiploceras; and he listed Endolobus Meek 

and Cryptoceras d'Orb. as synonyms of Temnocheilus 

M'Coy.

Mojsisovics (1902, p. 204) placed the following genera 

in his family Temnocheilidae: Temnocheilus, Metacoceras, 

Tainoceras, Foordiceras, Tainionautilus, Tirolonautilus, 

Mojsvaroceras,Qermanonautilus, Thuringionautilus, Pleuronautilus, P. (Holconautilus), P. (Trachynautilus), and 

Phloioceras. The two families Temnocheilidae Mojsisovics and Tainoceratidae Hyatt are almost identical in 

their scope and there are several genera that have been 

included in both families. As Temoncheilidae is synonomous with Tainoceratidae and the latter family has 

priority, Mojsisovics' family is suppressed as a synonym 

of Tainoceratidae. In this report the following genera 

and subgenera are included in this family: Temnocheilus, 

Tainoceras, Parametacoceras, Foordiceras. Metacoceras, 

Tainionautilus, Coopefoceras, Tirolonautilus, Qermanonautilus, Thuringionautilus, Mojsvaroceras, Aulametacoceras, Pleuronautilus, Enoploceras, Anoploceras, Encoiloceras, Holconautilus, Trachynautilus, and Phloioceras.

As here defined this family includes nautiloids with 

thick subquadrate conchs in which the volutions are 

somewhat broader than high, slightly to moderately 

involute, umbilici usually wide and open, sutures sinuous, siphuncles subceiitral and orthochoanitic. The 

family includes the typically "ornamented" nautiloids 

of the late Paleozoic and Triassic.

PHYLOGENY

Study of this evolutionary unit has led to several 

interesting observations. The genera included in this 

family comprise for the most part the "ornamented" 

nautiloids of the late Paleozoic and Triassic. Although 

19 generic names used to differentiate the various phyletic elements there is a surprising uniformity among all 

of them. More important is the strong similarity and 

relationships between the Paleozoic and Triassic forms.

Four and possibly 5 of the genera seem to range across 

this important boundary.

The ancestral form appears to be Temnocheilus, which 

ranges from the lower part of the Carboniferous into 

the Permian. Temnocheilus is characterized ly a subtrigonal cross section of the conch with a row of nodes 

on the ventrolateral shoulders. In the Morrov (lowest 

Pennsylvanian) two members of this family, Temnocheilus and Metacoceras, lived side by side. Metacoceras 

appears to be a direct descendant of Temnocheilus. 

Metacoceras has a subquadrate conch with *\ row of 

nodes on the ventrolateral shoulders and perheDs a row 

of nodes on the umbilical shoulder. This genus is abundant throughout the Pennsylvanian and Permian. It 

has more species than any other genus of the Tainoceratidae and shows almost an infinite amount of variation. It is difficult to evaluate the validity of many of 

the species of this genus because no extensive studies 

have been made of any population—and the potential 

range of variation is not known, partly because of insufficient material. The shape of the conch anc1 type of 

ornamentation of Metacoceras seem to have been the 

fundamental pattern upon which modifications were 

developed that form the basis for distinguishing many 

of the other genera of the Tainoceratidae. Metacoceras 

was a virile prolific stock of nautiloids that experienced 

no great evolutionary changes. The degree of variation seems to be just as large in the lower part of the 

Pennsylvanian as in the Permian. However, this basic 

stock periodically gave off mutants some of which had 

but a small stratigraphic and geographic extent, and 

others became the ancestors of independent phyletic 

lines.

Thus, in the early Pennsylvanian two basic phyletic 

lines were well defined, one of Temnocheilus and the 

other evolving from Metacoceras. Temnocheilus appears to belong to a comparatively sterile line with 

little variation and few species. Temnocheilus is 

thought to have given rise to only one genus, Foordiceras. This genus retained very closely the sub trigonal 

outline of the conch of Temnocheilus, but developed 

lateral ribs on the flanks. The broad definiticn of this 

genus by Miller and Youngquist (1949) is not held by 

the present writer, who believes that the earlier interpretation by Hyatt, Mojsisovics, and others f,re more 

nearly correct. Nautilus goliathus Waagen, the genotype of Foordiceras, has a subtrigonal outline and 

appears to show quite clearly affinities with Temnocheilus. Miller and Youngquist broadened the definition 

of this genus to include numerous forms with subquadratic cross sections.

Metacoceras is thought to be the ancestral stock from 

which the remaining genera of nautiloids of tie Tainoceratidae were derived. Parametacoceras, Des Moines
TAINOCERATIDAE 13

to Virgil in age, is one of the first groups to split off 

from Metacoceras. Parametacoceras has the subrectangular conch but with short transverse ribs on 

the mature portion of the conch. The complex of 

genera evolving from Pleuronautilus includes the 

prominently ribbed members of the Tainoceratidae. 

It is possible that Parametacoceras represents the 

ancestral elements of Pleuronautilus etc. However, 

the writer believes that altogether the evidence indicates descent from Metacoceras. Miller and Youngquist (1949, p. 96) recommended suppressing Parametacoceras, considering it a synonym of Foordiceras. The 

present author disagrees, and presents his views in his 

discussion of these genera (pp. 33-34).

One of the most unusual nautiloid genera of the 

family Tainoceratidae is Tainoceras which is characterized by a double row of nodes on the venter. There 

is one row of nodes on the ventral shoulder and perhaps 

another on the umbilical shoulder. Tainoceras ranges 

from the Des Moines to the Ochoan and it is suggested 

that a Triassic Karnian species should be included in 

this genus. The derivation of Tainoceras from Metacoceras has been generally agreed upon for many years. 

From the middle and late Permian several aberrant 

types of ornamented nautiloids that have narrow 

stratigraphic and geographic ranges, Cooperoceras, 

Tainionautilus, Tirolonautilus, and Aulametacoceras, 

are regarded as direct descendants of Metacoceras. 

Cooperoceras which ranges through the Leonard and 

Guadalupe, is characterized by the presence on the 

ventral shoulder of long, slender hollow paired spines 

that project ventrolaterally.

Tainionautilus includes nautiloids which on the 

mature portion of the conch have lateral ribs on the 

flanks that extend onto the venter and terminate at a 

ventral furrow. Recently Miller and Youngquist 

(1949, p. 96) proposed suppressing this genus as a 

synonym of Foordiceras. The view is not held tenable 

and a detailed discussion of this problem is given in 

the taxonomic treatment of these two genera (pp. 17,26). 

The exact affinities of Tainionautilus are not well 

established. The older views (Mojsisovics 1902, p. 

232) held Tainionautilus to be an aberrant development out of Tainoceras, with T. tuberculatum Trautschold a transitional form. Reed (1944, p. 356) considered Tainionautilus to be a subgenus of Metacoceras 

with M. sulciferum Miller and Thomas as a transitional 

form. The writer's interpretation somewhat resembles 

that of Reed.

Tirolonautilus also is derived directly from Metacoceras (Mojsisovics, 1902, p. 233) differing mainly in its 

slightly more involute outline and possession of a ventral furrow. Tirolonautilus has been reported only 

from the Bellerophon Limestone of the Alps. Aulametacoceras is another unique form; it has longitudiral 

ribs on the venter; the genotype A. mckeei is from beds 

of Leonard age in Arizona. The only other species 

placed in this genus is A. rectangularis (Hauer) from the 

Alpine Karnian. Tainionautilus, Tirolonautilus, Aufametacoceras, Cooperoceras retain the general shape of 

the conch and degree of involution of Metacoceras. 

The evolution and modifications which set the 4 genera 

apart from Metacoceras are changes that are confined 

mostly to the ventral regions of the conch. In Cooperoceras it is the development of spines, in Tainionautilus 

and Tirolonautilus the ventral furrow is distinctive and 

in the former genus there are also present lateral ribs 

which extend on to the venter. In Aulametacoceras 

the longitudinal ribs on the venter are the distinctive 

feature. These 4 genera have a total of only 11 species.

Metacoceras is thought to evolve directly into Mojsvaroceras at the end of the Permian and beginning of the 

Triassic. The two genera differ only in that the 

younger form is slightly more involute and has an annular lobe. The presence or absence of an annular lol % 

however, is not known for most species of Metacoceras. 

On the phylogenetic diagram (text fig. 5), Mojsvaroceras 

is .placed in a line directly continuous with that of Me4fi,- 

coceras. Mojsisovics (1902, p. 233) believed that the 

evolutionary trend within Mojsvaroceras was toward? a 

loss of ornamentation; but the present writer does cot 

agree. This genus ranges from the Scythian to the 

Karnian, with its acme in the Anisian. In the Ir.te 

Scythian a tribe of nautiloids, Germanonautilus, which 

tended towards greater involution and a loss of ornamentation, stemmed from Mojsvaroceras or possibly 

directly from Metacoceras. Germanonautilus ranges 

from the Scythian to the Karnian. Of the Triassic 

members of the Tainoceratidae Mojsvaroceras, Thuringionautilus, and Germanonautilus appear to be directly 

or indirectly derived from Metacoceras. Aulametacoceras 

and Tainoceras, both late Paleozoic genera, may ea<\h 

include one Triassic species.

The above discussion has attempted to summarize 

the lines of development stemming from theMetacocerasMojsvaroceras relationship. Another important phyletic 

line that also seems to have its ancestry in Metacoceras 

involves mostly Triassic nautiloids. This includes the 

genus Pleuronautilus and six closely related genera and 

subgenera. The writer believes that most of the ribbed 

nautiloids with subquadrate conchs of the late Paleozoic 

should be placed in the genus Pleuronautilus. These 

Paleozoic ribbed nautiloids developed out of Metacoceras 

in late Pennsylvanian or early Permian time. This 

branch remained fairly simple in its development in the 

Permian, but began a trend towards extreme modification and diversity in the early Triassic. There was 

actually a great expansion of this genetic line hi to
14 AMERICAN TRIASSIC COILED NAUTILOIDS

FIGURE 5.—Diagram showing inferred phylogeny and geologic distribution of the Tainoceratidae,
TAINOCERATIDAE 15

Scythian Anistan Ladinian Karnian Norian Rhoetian

FIGURE 6.—Range chart showing known stratigraphic occurrence of the Tainoceratidae. The width of the line is proportional to the number of species.
16

n

FIGURE 7.—Cross sections of the conch of A, Tainionautilus transitorius (Waagen) 1879, pi. 6, fig. 4, height 38 mm, B, Foordiceras goliathum (Waagen) 1879, pi. 4, diameter 169 mm, the genotype of Foordiceras: C, Aulametacoceras mckeei Miller and Unklesbay 1942, fig. 1A, diameter about 

185 mm, the genotype of Aulametacoceras; D, Tainoceras wyomingense Miller and Thomas 1936, fig. 3A, height 34 mm; E, Cooperoceras texanum 

Miller 1945, fig. IB, height 10 mm, the genotype of Cooperoceras; F, Tirolonautilus crux (Stache) 1877, pi. 6, fig. Ic, height 26 mm; G, Metacoceras cavatiformis Hyatt 1891, fig. 33, diameter 66 mm: H, Metacoceras cornutum Girty 1915, pi. 29, fig. 5b, height 24 mm; I, Metacoceras 

cannatum Girty 1915, pi. 30, fig. 3b, height 9 mm; J, Metacoceras dubium Hyatt 1891 fig. 35, height 43 mm; K, Tainoceras cavatum Hyatt 1891, 

fig. 42, diameter 106 mm; L, Metacoceras nodosum Miller, Dunbar and Condra 1933, pi. 15, fig. 7, height 20 mm; M. Temnocheilus sp. Miller 

and Owen 1934, fig. 2B, height 24 mm; N, Metacoceras sinuosum Girty 1915, pi. 30, fig. Ib, height 15 mm.
TAINOCERATIDAE 17

several more specialized lines. The most elaborate and 

complexly ornamented Triassic nautiloids belong in 

this phyletic line.

The directions of specialization in Pleuronautilus 

were twofold; the first towards changes in suture and 

the second towards changes in shape and ornamentation 

of the conch. Only one subgenus, Holconautilus, 

changed its suture pattern in developing a ventral 

saddle. The remaining subgenera are defined on 

changes in the form of the conch and patterns of ornamentation. Enoploceras has a quadratic conch with 

flattened venter, flanks, and umbilical walls. The 

ornamentation is not very unlike that of Pleuronautilus. 

Anoploceras has a depressed subquaclratic conch with 

a broadly arched, smooth venter and steep umbilical 

walls. The flanks have sinuous ribs. In Trachynautilus the conch is characterized by longitudinal ribs 

and its small size. The last group, Encoiloceras, has a 

very evolute conch with strong fold-like ribs and 

modifications of the aperture. Enoploceras is the most 

heterogeneous, with 18 species. Anoploceras has only 2 

species, Trachynautilus has 7, Encoiloceras has 1, and 

Holconautilus has 10.

Phloioceras developed longitudinal ridges on the 

flanks and venter. It is an independent development 

out of Pleuronautilus, but closely allied to Trachynautilus.

Genus TEMNOCHEILUS M'Coy, 1844

Genotype: Nautilus (Temnocheilus) coronatus M'Coy

This genus ranges from the early part of the Carboniferous to the middle part of the Permian period 

and is thought to be the ancestral form of the Tainoceratidae. Mojsisovics, Hyatt, Miller, and others have 

repeatedly pointed out its ancestral position in the 

phylogenetic history of this family. ' Miller, Dunbar, 

and Condra (1933) did much to clarify the complex 

taxonomic problems surrounding this genus, and gave 

the following clear, concise diagnosis of the genus:

Conch nautiliconic, the whorls being greatly depressed, 

strongly flattened ventrally and laterally, narrowly rounded 

ventrolaterally and more broadly so dorsoventrally, and slightly 

impressed dorsally; lateral sides typically not parallel but converging toward the dorsum, the whorls therefore being subtrapezoidal in cross section. Umbilicus very broad, deep, and 

perforate. Prominent growth lines indicate the presence of a 

deep tongue-shaped hyponomic sinus. Ventrolateral shoulders 

of the conch marked by a single row of large, prominent nodes 

which are more or less confluent and are elongated in a direction 

parallel to the axis of the conch; these peculiar nodes are one of 

the most distinctive characters of the genus. Sutures simple 

and approximately transverse to long axis of the conch but 

slightly sinuous; they form broad, shallow, broadly rounded 

lobes as they cross the flattened lateral and ventral sides of the 

conch, rounded saddles as they cross the ventrolateral and dorsolateral zones, and deep, bluntly rounded lobes as they cross the 

dorsum. Septa likewise approximately transverse to long axis

of conch and moderately convex apicad. Siphuncle small, 

subcentral in position, and orthochoanitic in structure; septal 

necks short but straight; connecting rings not expanded within 

camerae.

(See text fig. 8 and PI. 1, figs. 1, 2.)

In this paper only two genera are considered direct 

descendants of Temnocheilus: Foordiceras and Metacoceras. The latter genus ranges through the Pennsylvanian and Permian, and is extremely varied and 

abundant. Metacoceras is thought to be the direct 

ancestor of several Paleozoic and Triassic general. 

This is the virile branch of the family tree; it is also 

the branch which maintains a more or less subqur.drangular cross section of the conch. The various 

descendants are differentiated mostly on the basis of 

differences in ornamentation.

FIGUEE 8.—Diagrammatic cross section of the holotype of Temnocheilus lotus (Meek 

and Worthen) (Univ. Illinois X-438-A) from the Pennsylvanian, Carbon Cliffs, 

Kock Island County, Illinois, X 1.

Foordiceras is confined to the Permian. It has few 

species and appears to have a restricted geograpHc 

range (depending on the interpretation of the gemr). 

Foordiceras maintains a sub trigonal type of conch 

which is similar to that of the ancestral Temnocheilus.

Temnocheilus ranges throughout the Pennsylvanian 

and Permian, and has been recorded from the United 

States and Eurasia. The species listed on page 18 have 

been assigned to it.

Genus FOORDICERAS Hyatt, 1893 

Genotype: Nautilus goliathus Waagen

The genus Foordiceras has been generally neglected 

by American authors since Hyatt's time; however, 

Miller and Youngquist (1949) discussed the genus at 

length and included in it many species that had previously been assigned to Metacoceras, Parametacoceras, 

Shansinautilus, and Tainionautilus. They also suggested suppressing completely • Shansinautilus Yabe 

and Mabuti, Parametacoceras Miller and Owen, and 

Tainionautilus Mojsisovics in favor of Foordiceras 

Hyatt. Much of their interpretation of this genus is
18 AMERICAN TRIASSIC COILED NAUTILOIDS 

Distribution of species of the genus Temnocheilus

Species Stratigraphic distribution Geographic distribution

Temnocheilus ? acanthicus Tzwetaev 1888_____

T. asiaticus Grabau 1924__________________

T. atuberculatus Tzwetaev 1888______________

T. gemmellaroi Canavari 1935_ ______________

T. grewingki Tschernyschew 1899____________

T. harneri Miller and Owen 1934___________

T. inaequilateralis Miller and Youngquist 1949. 

T. johnsoni Miller, D unbar, and Condra 1933- 

T. latus (Meek and Worthen) 1870__ _ ___. 

T. medioventralis Sturgeon 1946______________

T. multituberculatus (Waagen) 1879._________

T. multituberculatus simensis Kruglov 1928-___ 

T. multituberculatus tastubensis Kruglov 1928__ 

T. nikitini Loweneck 1932__________________

T. ornatissimus Tzwetaev 1888______________

T. posttuberculatus (Karpinsky) 1874.________

T. posttuberculatus kosswae Kruglov 1928__ __ 

T. posttuberculatus waschkuricus Kruglov 1928.

Upper Carboniferous_____________

Permian (Taiyuan series)_________

Upper Carboniferous_____________

Permian (Sosio beds)______________

Permian (Bakhmout dolomite) ______

Pennsylvanian (Cherokee formation). 

Permian (Leonard formation) _______

Pennsylvanian. ___________________

.do.

Pennsylvanian (Allegheny formation) _ 

Permian (Upper Productus limestone). 

Permian (Ashian) __________________

Permian (Schwagerina princeps beds). 

Upper Carboniferous_____________

Permian (Artinskian)______________

T. quinqueliratus Sturgeon 1946_________________

T. subrectangularis Miller, Dunbar, and Condra 1933. 

T. tuberculatus Sowerby 1821____________________.

T. waageni Loczy 1898__________________________

T. winslowi (Meek and Worthen) 1870.___________

Pennsylvanian (Allegheny formation) 

Pennsylvanian (Upper part of Pottsville). 

Carboniferous.________________________

Permo-Carbonif erous __________________

Pennsylvanian. _______________________

Central Russia.

Shansi, China.

Central Russia.

Sicily.

Kulogory, RussH.

Missouri.

Brewster County, Tex.

Colorado.

Illinois.

Ohio.

Salt Range, PaHstan.

Sims River, Russia.

Tastuba, Russia.

Tianschen, China.

Central Russia.

Koswa River, F'lssia.

Do.

Tchussovaya River, Russia. 

Ohio.

Floyd County, Ky. 

Great Britain. 

Yunnan, China. 

Illinois.

believed by the writer to be untenable. Nautilus 

goliathus Waagen of the Upper Productus limestone of 

the Salt Range, India, is the genotype of Foordiceras 

by original designation. Because it is pertinent to the 

analysis of ribbed nautiloids in the late Paleozoic and 

to the proper phylogenetic placement of Foordiceras, 

Waagen's discription of the genotype of Foordiceras 

is included here.

The general form of the shell is that of a very thick disk. The 

umbilicus is very deep, but not very wide; the whorls are very 

thick and inflated with an extremely broad flattened external 

part. The transverse section of the whorl is broad trapezoidal, 

the broadest diameter being near the outer edge of the whorl. 

The lateral parts of the whorls unite with the external part in a 

rounded edge, which is ornamented with a row of thick elongated 

rib-like tubercles extending halfway down the height of the 

whorl. There are about fifteen of these tubercles on the specimen 

of a diameter of 168 mm. The lateral parts of the whorls slope 

down from the external edge regularly to the umbilical suture, 

only showing a slight curve, without forming any umbilical edge 

or a distinct umbilical wall.

The septa of this species are slightly curved like those of the 

preceding one (Nautilus fiemingianus de Koninck) but they are 

much less numerous. Besides this there is no relation between 

the air chambers and the tubercles, as in the case in Nautilus 

flemingianus. The specimen I have got for description is not 

sufficiently well preserved to count the number of septa on each 

whorl, but there may have been about thirty-two on the last 

circuit.

The position of the siphon could not be ascertained.

From this description and examination of the figure 

of the holotype (Waagen 1879, PI. 4; which Foord 1891, 

p. 156, states is "highly restored") it should be emphasized that the conch is trapezoidal in shape and that the 

flanks 

slope down from the external edge regularly to the umbilical

suture, only showing a slight curve, without forming a ny umbilical edge or distinct umbilical wall (see fig. 7B).

The trapezoidal conch is very reminiscent of that seen 

only in typical representatives of Temnocheilus. The 

latter genus is also characterized by having ventrolateral nodes. Short ribs are common in several early 

Permian species of Temnocheilus described by Kruglov 

(1928) from Russia and Yin (1933) from China. 

Temnocheilus and Foordiceras are the only late Paleozoic 

or Triassic nautiloids with a similar trapezoidal'conch. 

Mojsisovics (1902, p. 232) first observed that Foordiceras 

had a Temnocheilan cross section and he considered 

Foordiceras as a "directly descendant type from 

Temnocheilus in ,a somewhat more advanced evolutionary stage" [free translation]. In this interpretation 

the writer concurs. Many of the forms recently assigned 

to Foordiceras by Miller and Youngquist (1949) have a 

subquadratic to compressed conch and should be placed 

in the phyletic lines of Metacoceras and Pleur<mautUus. 

The ornamentation is considered to be of secondary 

importance in this case and the shape of the conch a 

nore vital basis of differentiation and ind; °.ator of 

genetic relationship. As demonstrated ir several 

places in this study, the evolutionary history of Pennsylvanian, Permian, and Triassic nautiloids has several 

examples of convergent evolution and homeomorphic 

tendencies. The convergence may be in shape of the 

conch, in the ornamentation, or both. Thus it appears 

to be more correct to place Foordiceras as a direct 

derivative of Temnocheilus and confined to t^e Paleozoic, giving rise to no Triassic forms. Those nautiloids 

with more or less quadratic to compressed conchs 

should be kept in a completely different phyletic line.
TAESTOCERATIDAE 

Distribution of species of the genus Foordiceras

19

Species

Foordiceras dyadicum ( Haniel) 1915__--_-________-

F. flemingianum (deKoninck) 1863- _______________

F. goliathum (Waagen) 1879__ _ _ _____________ _

F. grypoceroide Reed 1931--- ------ ________ __-_

F. loczyi (Fliegel) 1901. _ _ __. _ ._. __ .___

F. nodosocostatum (Gemmellaro) 1888__ __________

F. pleuronautiloide (Gemmellaro) 1888___--_- ._-__

F. sumatrense (Fliegel) 1901- ______________ _ ___

F.? ufimskensis Kruglov 1928 _ _ ___ _ _ ______ _

F. wynnei (Waagen) 1879_--__-___-___- _____ _ _

Stratigraphic distribution

Permian (Middle Productus limestone). -------

Permian (Upper Productus limestone) ___---__-

Permian (Productus limestone)— _ _ _________

Permian (middle) _ ____ ________ ___________

Permian (Sosio beds) _ _ ________________ __

- _ do

Permian (middle) _ __ _ -____-____ _ ____ _

Geographic distribution

Timor.

Salt Range, Pakistan.

Do.

Do.

Do.

Russia.

Salt Range, Pakistan.

The writer believes that none of the species referred 

to Foordiceras by Miller and Youngquist (1949) 

belong to that genus and are more properly placed in 

Metacoceras and Pleuronautilus. The following species 

are thought to belong in the genus Foordiceras.

Genus METACOCERAS Hyatt, 1883 

Genotype: Nautilus (Discus) sangamonensis Meek and Worthen

The most prolific Late Paleozoic nautiloid genus is 

Metacoceras, with about 50 species. The original 

generic designation by Hyatt (1883, p. 268) is as 

follows,

Metacoceras includes Silurian and Carboniferous species with 

broad, ventral, lateral, and dorsal lobes but no annular lobes. 

Siphon near the ventrum or central. Whorls quadrate, sides 

with one row of nodes along the external border, umbilical 

shoulders smooth but gibbous, the type has this part of the 

whorls elevated into a ridge. The forms are evidently transitional from the genus Plectoceras to Mojsvaroceras.

A more recent and amended diagnosis of the genus is 

given by Miller, Dunbar and Condra (1933, p. 168- 

169). The many studies of the genus since Hyatt's 

original designation have tended to broaden the concept 

of it. Miller (1945) placed in this genus several ribbed 

forms from the middle Permian of West Texas that he 

later placed in Foordiceras (Miller and Youngquist, 

1949). Girty (1915, p. 239-249) attempted to group 

the species of Metacoceras into four subdivisions. 

Fortunately, however, Girty applied no formal names 

to his groups (Miller, Dunbar, and Condra, 1933, 

p. 166) Study of the Literature, and a large collection 

of forms from the Late Paleozoic of Texas, show that 

the various "types" of ornamentation are gradational 

and that no practical or consistent subdivisions can be 

set up on this basis at the present time.

The basic pattern of ornamentation of Metacoceras is 

that of ventrolateral and umbilical nodes. The species 

can be separated into two groups, the first including 

those that have only ventrolateral nodes, and the 

second those that have both ventrolateral and umbilical 

nodes. Within these two groups there are countless 

variations and gradations. In the first group, there 

are species with weakly developed nodes (such as M.

sublaeve and M. inconspicuum), and also species with 

strongly developed ventrolateral nodes (such as M. 

sangamonense, M. mammiferum, and M. coloradoense). 

Intermediate in development of the ventrolateral nodes 

are such species as M. mutabile and M. cornutum. 

Other species evolved elongated types of ventrolateral 

nodes such as are found in M. hayi, M. walcotti, and 

M. cavatiformis. Species of Metacoceras with both 

ventrolateral and umbilical nodes do not seem to be 

quite as common as those with only ventrolateral nodes. 

The binodal ornamentation is illustrated in such species 

as M. angulatum, M. nodosum, M. biseriatum, M. 

medlicottianum etc. The genotype of Metacoceras, 

M. sangamonense (Meek and Worthen) is characterised 

by large blunt, rounded ventrolateral nodes, with no 

nodes on the umbilical shoulder but with an acutely 

rounded umbilical shoulder (pi. 1).

Within recent years there has been a tendency to 

include in the genus Metacoceras Pennsylvanian and 

Permian nautiloids with the approximate gross form of 

the genotype, but with variously modified lateral ribs. 

The development of lateral ribs, which in some fonts 

culminate in a ventro-lateral node and/or an umbilical 

node, appears to be a separate phyletic development 

that gave rise to the great complex of genera, subgene^a, 

and species evolving around the genus Pleuronautilus. 

The evolutionary trend deriving Mojsvaroceras directly 

from Metacoceras does not appear to involve the development of primary ribs; however, some species of Mojsvaroceras do show connecting "pilae" or ribs between 

ventrolateral and umbilical nodes. Twenty-four specks 

of Permian nautiloids, many previously referred to 

Metacoceras, are retained or placed in the genus Pleu^onautUus and seem to represent the primitive early forms 

of Pleuronautilus, most of them showing marked 

affinities with Metacoceras. (See discussion of Pleuronautilus on pp. 33, 34.)

The genus Metacoceras ranges from the earliest Pernsylvanian to the latest Permian and is thought to be 

replaced in the Triassic by the subgenus Mojsvaroceras. 

Metacoceras shows two maxima in number of species, 

one in Des Moines-Missouri time and the other in 

Wolfcamp-Leonard time. The high degree of variation
20 AMERICAN TRIASSIC COILED NAUTILOIDS 

Distribution of species of the subgenus Metacoceras (Metacoceras)

Stratigraphic distribution Geographic distribution

Metacoceras (Metacoceras) angulatum Say re 1930___. 

M. (M.) armatum (Sowerby) 1840_______________

M. (M.) baylorense Miller and Youngquist 1949____.

M. (M.) biseriatum Miller and Owen 1934____---__.

M. (M.) bituberculatum Miller and Youngquist 1949- 

M. (M.) carinatum Girty 1911__________________

M. (M.) cavatiforme Hyatt 1891__________________

M. (M.) cheneyi Miller and Youngquist 1947__--__. 

M. (M.} chittidilense Reed 1944___________________

M. (M.) coloradoense Miller, Dunbar, and Condra

1933. 

M. (M.) cornutum Girty 1911--------------------

M. (M.) costatum (Hind) 19U_---__.________.

M. (M.) diecoideiim Merla 1934_________________

M. (M.) dubium Hyatt 1891_-_---_-.---_____._.

M. (M.) falcatum (Sowerby) 1840___-_-___________

M. (M.) hayi Hyatt 1891__--.-----_-----_-----__.

M. (M.) aff. M. hayi (Fliegel) 190l____________.

M. (M.) inaequiseptatum Merla 1934_______________

M. (M.) inconspicum Hyatt 1891-____-_-___-____.

M. (M.) jacksonense Miller, Lane, and Unklesbay

1947. 

M. (M.) knighti Miller and Thomas 1936___._____.

M. (M.) Iambi Sturgeon 1946__-_______-_-_-____

M. (M.) mammiferum Miller 1945_______--________

M. (M.) medlicottianum (Waagen) 1879__________

M. (M.) multituberculatum Girty 1911 _____________

M. (M.) mutabile Miller and Owen 1934_____-____-

M. (M.) nodosum Miller, Dunbar, and Condra 1933. 

M. (M.) ornatissimum (Miller and Youngquist)

1941. 

M. (M.) perelegans Girty 1911__________________

M. (M.) pernodosum (Tschernyschew) 1899_ _______

M. (M.) "pitzovi Kruglov 1926.__-__________--___.

M. (M.) pissovi artiense Kruglov 1928-------------

M. (M.) postcostatum Bisat 1930-_________________

M. (M.) pottsvillense Morningstar 1922____________

M. (M.) reedianum Merla 1934___________________

M. (M.) sangamonense (Meek and Worthen) 1860__. 

M. (M.) sinuosum Girty 1911 _.__-________-_____.

M. (M.) subglabrum Kruglov 1928__ ______________

M. (M.) subquadranffiilaris (Whitfield) 1882-_______

M. (M.) tricarinatum Sturgeon 1946___----___--__-

M. (M.) tricarinatum parvinodosum Sturgeon 1946__- 

M. (M.) trigonotuberculatum Jakolew 1899_____ _-.__.

M. (M.) tschernyschewi (Tzswetaev) 1888____---___.

M. (M.) tuberosum (McCoy) 1853________________

M. (M.) unklesbayi Miller and Youngquist 1949_ _ _. 

M. (M.) vagans Miller and Owen 1937____________

M. (M.) walcotti Hyatt 1891_-__-__-----_---__.

Pennsylvanian (Westerville limestone) _ 

Carboniferous_ _ ____________________

Permian (Leuders formation)_________

Pennsylvanian (Cherokee formation) __. 

Permian (Leonard formation) _________

Pennsylvanian (Wewoka formation) _ _ _ 

Permian (Fort Riley? limestone) ______

Permian (Admiral formation)_____-_-_

Permian (Middle Productus limestone). 

Pennsylvanian- ___________-___----_-

Pennsylvanian (Wewoka formation) _ 

Carboniferous. _ ___________________

Permian (Bellerophon limestone) 

Permian (Fort Riley? limestone) 

Carboniferous.-- _ _________________

Permian (Fort Riley? limestone) 

Permian (lower)___________________

Permian (Bellerophon limestone) 

Permian (Fort Riley? limestone) 

Pennsylvanian ^Winterset limestone).

Pennsylvanian (Casper formation)__-_- 

Pennsylvanian (Allegheny formation) _ _ 

Permian (Bone Spring limestone)_____ - 

Permian (Middle Productus limestone). 

Pennsylvanian (Wewoka formation) 

Pennsylvanian (Cherokee formation)__. 

Pennsylvanian (Kansas City group) 

Permian (Admiral formation) _________

Pennsylvanian (Wewoka formation) 

Permian (middle)___________--___---__.

Permian_ _ __________________________

Permian (Artinskian)_..____-__-_-_-__.

Carboniferous.. _ ______________________

Pennsylvanian (Pottsville formation) 

Permian (upper)____-_-_____-__-----_.

Pennsylvanian (McLeansboro formation). 

Pennsylvanian (Wewoka formation) 

Permian (Ashian)_____________________

Pennsylvanian ________________________

Pennsylvanian (Allegheny formation) ___. 

.doPermian (Bakhmout dolomite and Bellerophon

limestone). 

Carboniferous (upper)___„_____________-___.

Carboniferous__ _____________________________

Permian (Kaibab formation)________________

Pennsylvanian (Coffeyville formation)_________

Pennsylvanian _____---____----________-.--_--

Missouri.

Great Britain.

Baylor County, Tex.

Henry County, Mo.

Brewster County, Tex.

Oklahoma.

Geary County, Kans.

Coleman County, Tex.

Salt Range, Pakistan.

Colorado.

Oklahoma.

Great Britain.

Italy.

Geary County, Kans.

Great Britain.

Geary County, Kans.

Sumatra.

Italy.

Geary County, Kans.

Jackson County, Mo.

Wyoming.

Ohio.

Hudspeth County, Tex.

Salt Range, Pakistan.

Oklahoma.

Henry County, Mo.

Missouri.

Coleman County, Tex.

Oklahoma.

Russia.

Ufa Plateau, Russia.

Asha River, Rursia.

Great Britain.

Ohio.

India.

Illinois.

Oklahoma.

Asha River, Russia.

Ohio.

Do.

Do. 

Donetz Basin, Russia;

Alps, Italy. 

Central Russia. 

Great Britain. 

Arizsona. 

Oklahoma. 

Texas.

and few or poorly preserved specimens prevent a thorough understanding of most of the species. There are 

more than twice as many species of Metacoceras (50) 

as of any other Pennsylvanian and Permian nautiloid. 

The closest rival in numbers of species is Domatoceras 

with 22 species. Metacoceras and Mojsvaroceras are 

very similar in their gross form and show similar degrees 

of variation. Mojsvaroceras is slightly more involute 

and has an annular lobe. Hyatt (1883, p. 268) in his 

original designation of the genus Metacoceras states that 

no annular lobe is present. The number of species in 

which the dorsal suture pattern is known, however, is 

so few that the status of this feature in Pennsylvanian 

and Permian species of Metacoceras is not known. Recent studies on nautiloids (Diener, 1919, Kieslinger,

1924, and numerous publications by Miller) have cast 

grave doubt on the taxonomic significance of the annular 

lobe. Because the two genera are so closely related, 

differing mainly in the degree of involution and the 

presence or absence of an annular lobe, it is expedient 

to make Mojsvaroceras a subgenus of Metacoceras. This 

classification will also emphasize the close phyletic 

relationship between the two groups, that Mojevaroceras 

appears to have been evolved directly from and to have 

replaced Metacoceras.

Miller, Dunbar, and Condra (1933, p. 167-168) 

assigned 33 species to the genus Metacoceras. Since 

then, taxonomic changes have raised to perhaps 50 the 

number of species the writer considers valid members of 

the genus.
TAINOCERATEDAE 21

Subgenus MOJSVAROCERAS Hyatt, 1883 

Subgenotype: Temnocheilus neumayri Mojsisovics

According to Hyatt's original description (1883, p. 

269) the genus

Mojsvaroceras, nobis, of the Dyas and Trias includes the species 

described by Mojsisovics in the Mediterr. Trias Prov. as Temnocheili. These have two rows of lateral tubercles, the form 

quadrate and very stout, the siphons below the centre, and 

sutures with ventral lobes, but also according to Mojsisovics 

with minute annular lobes.

"Temnocheili" of Mojsisovics include T. neumayri, 

T. augusti, T. morloti, T. cassianus, and. T. schloenbachi. 

The last three species are forms very different from the 

genotype and have subsequently been referred to 

other genera.

Mojsisovics (1902, p. 233) greatly amplified Hyatt's 

description of Mojsvaroceras. He characterized the 

genus as having straight ribs, by which it was differentiated from Pleuronautilus, and included Pennsylvanian 

and Permian species (Nautilus nikitini Tzwetaev (1888) 

and Nautilus verae Arthaber, and with question "Temnocheilus" crassus Hyatt). Mojsisovics visualized the 

ornamentation of Mojsvaroceras as consisting of either 

ventrolateral and umbilical nodes which may or may 

not be connected by lateral ribs, or lateral ribs only, or 

ventrolateral nodes only. He suggests an evolutionary 

trend towards a decrease in ornamentation. Mojsvaroceras perarmatum Mojsisovics of the Karnian with 

ventrolateral and umbilical nodes was considered a 

possible offshoot from the main evolutionary line.

There are 18 species of the subgenus Mojsvaroceras: 

2 in the Scythian, 12 of Anisian age, 1 of Ladinian age, 

and 3 of Karnian age. This distribution appears to 

indicate an expansion in the Anisian and great reduction

in the number of species in the Ladinian and Karnir.n. 

The two Scythian species are typical binodal forms 

showing strong affinities with Metacoceras. TTie 

Anisian species show a great amount of variation in 

the form of the conch and in ornamentation. One of the 

most striking characteristics of the Anisian species is 

the disappearance of the ornamentation leaving a 

smooth conch after the first or second whorl. This is 

. well illustrated in M. aureculatum (Hauer), M. ventricosum (Hauer), and M. kellneri (Hauer). The Karnian 

species, namely M. pironai (Tommasi), and M. perarmatum Mojsisovics are all typical binodal forms; M. 

turneri Hyatt and Smith has only a row of elongated 

nodes along the midline of the flanks. The fact that 

the latest species of Mojsvaroceras, those of Karnian 

age, are typical binodal, quadrate forms appears to 

indicate that this ornamentational type is the main 

evolutionary pattern of this group. The principal 

modifications in these late species over the earlier 

species are the greater development of the ventral lobe, 

the presence of an annular lobe, and a slightly more 

involute conch. The Anisian species that led Mosisovics to believe in an evolutionary trend towards a 

decrease in ornamentation in Mojsvaroceras appear to 

be local aberrant forms that in effect show a great 

acceleration in their ontogenies and converger<?e 

towards Germanonautilus.

Only two species of Mojsvaroceras are known from 

the Triassic of North America, M. turneri Hyatt and 

Smith from the Hosselkus limestone, Shasta County, 

California and M. frenchi Kummel n. sp. from the 

Thaynes formation, southeastern Idaho. Most of the 

remaining species of Mojsvaroceras are known from the 

Alpine region of Europe, a few from Triassic rocks of the 

Himalayas, and one species from northern Siberia.

Distribution of species of the subgenus Metacoceras (Mojsvaroceras)

Species Stratigraphie distribution Geographic distribution

Metacoceras (Mojsvaroceras) augusti (Mojsisovics)

1882.

M. (M.) auriculatum (Hauer) 1892—__-_--_--___-. 

M. (M.) binodosum (Hauer) 1887---------------.

M. (M.) bulogense (Hauer) 1887-----------------.

M. (M.) frenchi Kummel n. sp____---__________.

M. (M.) kagae Diener 1907_______-___-------_-.

M. (M.) kellneri (Hauer) 1887— ------------------

M. (M.) morloti (Mojsisovics) 1882_-__----_ ___-__.

M. (M.) neumayri (Mojsisovics) 1882-___-__---___. 

M. (M.) nivicola Diener 1907___-_-_---_-_- _______

M. (M.) patens (Hauer) 1896_ — — __-_--_._.-__. 

M. (M.) perarmatum (Mojsisovics) 1873__----___..

M. (M.) pironai (Tommasi) 1890- ___-j____ _______

M. (M.) polygonium (Hauer) 1892----------------

M. (M.) subaratum (Keyserling) I860.------------

M. (M.) turneri Hyatt and Smith 1905- _____.___..

M. (M.} ventricosum (Hauer) 1896-_______________

Triassic (Anisian)

Triassic (Anisian, Ladinian) 

Triassic (Anisian)_____----

.____do—— —— — ---

Triassic (Scythian)____-_-_ 

Triassic (Anisian)_____-__-

.____do—— —— .

.____do—— — — .

._—do— ——— — 

.____do_.------

Triassic (Karnian).

Triassic (Anisian) _. 

Triassic (Scythian) 

Triassic (Karnian). 

Triassic (Anisian) _.

Alps.

Alps, Yugoslavia.

Do.

Yugoslavia. 

Idaho.

Himalayas, India. 

Yugoslavia. 

Alps, Yugoslavia. 

Alps.

Himalayas, India. 

Yugoslavia. 

Alps.

Do.

Yugoslavia. 

Siberia. 

California. 

Yugoslavia.
22 AMERICAN TRIASSIC COILED NAUTILOIDS

FIQUEE 9.—Cross sections of the conch of A, Oermanonautilus salinarius Mojsisovics 1882, pi. 91, flg. 3b, diameter 86 mm; B, O. tintoretti Mojsisopfc* 

1882, pi. 91, flg. 2b, diameter 76 mm; C, O. breuneri (Hauer), after Mojsisovics 1902, pi. 9, fig. 2b, diameter 118 mm; D, Metacoceras (Mojsaaroceras) polygonium Hauer 1892, pi. 1, flg. 4b, diameter 94 mm; E, M. (M.) kettneri Hauer 1887, pi. 2, flg. 2b, diameter 88 mm; F, M. (M.) aurUculatus Hauer 1892, pi. 2, fig. Ib, diameter 69 mm; G, M. (M.) patens Hauer 1896, pi. 3, flg. 2, diameter 92 mm; H, M. (M.) bmodosum Hauer 

1896, pi. 1, flg. 4, diameter 78 mm; /, M. (M.) neumayri (Mojsisovics) 1882, pi. 88, flg. 2b, diameter 75 mm, the subgenotype of M. (M.); J, 

M. (M.) subaratus (Keyserling), after Mojsisovics 1886, pi. 16, flg. Ib, diameter 56 mm.
TAINOOERATIDAE 23

Metacoceras (Mojsvaroceras) turner! Hyatt and Smith 

Plate 2, figures 11-14; text figure 10

1905. Mojsvaroceras turneri Hyatt and Smith, U. S. Geol. Survey, 

Prof. Paper 40, p. 209, pi. 48, figs. 6-11.

1927. Mojsvaroceras turneri Hyatt and Smith, U. S. Geol. Survey, 

Prof. Paper 141, p. 106, pi. 48, figs. 6-11.

The holotype is a fragmentary specimen consisting of 

four camerae and about 65 mm of the living chamber. 

The whorls are subquadratic in cross section (text fig. 

10). At the most adoral part of the conch the whorl 

is 60 mm wide and 40 mm high. The venter is broadly 

arched grading to distinct ventral shoulders. The flanks 

converge ventral and are only slightly arched. The umbilical shoulders are sharply rounded and the umbilical 

wall convex and steep. The impressed zone is moderately deep. The adoral part of the living chamber 

expands very rapidly.

FIGURE 10.—Diagrammatic cross section of the holotype of Metacoceras (Mojsvaroceras) turneri Hyatt and Smith (U.S.N.M. 74026) from Hosselkus limestone, 

Shasta County, California, X 1.

Along the mid line of the flanks are large elongated low 

nodes spaced about 17 mm apart. There are no nodes 

on the ventral or umbilical shoulders. The sutures form 

shallow ventral and lateral lobes and have an annular 

lobe. A small paratype 30 mm hi diameter has a 

flattened venter with well rounded ventral and umbilical 

shoulders. The flanks are also flattened. The nodose 

pattern of ornamentation is not present on this immature specimen.

Occurrence: Upper Triassic Hosselkus limestone, 3 

miles east of Madison ranch, between Squaw Creek and 

Pit River, Shasta County, California.

Types: Holotype, U.S.N.M. 74026; paratype, 

U.S.N.M. 74026a.

Metacoceras (Mojsvaroceras) frenchi n. sp. 

Plate 2, figures 1-10; plate 4, figures 8, 9, 10; text figure 11

This species is the most abundant form hi the Lower 

Triassic nautiloid fauna from Idaho. Ten fairly complete specimens are available for study.

The conch is evolute, impressed zone being small. 

Cross-section of the adoral whorl is subquadratic in outline (text fig. 11) being broader than high. The venter is

broad, flattened, and has a shallow depressed zone along 

the center in the maturer portions of the conch. The 

ventral shoulder is broadly rounded and the flanks flair 

distinctly outward. The umbilical shoulder is sharply 

rounded and passes on to a broadly arcuate umbilical 

wall which turns inward at the seam. The adapertiral 

whorls are more rounded but still broader than high. 

The first one-half volution has no apparent umbilical 

shoulder, the flanks grade more or less gradually or to 

the dorsal area. The length of the living chamber is 

unknown. The umbilicus is broad, deep, and perforate. 

The umbilical perforation is 4 to 7 mm across in the 

specimens studied.

FIGURE 11.—Diagrammatic cross section of the holotype of Metacoceras (Afoj^aroceras) frenchi, n.sp. (U.S.N.M. 107069) from the Cdumbites beds, Thaynes 

formation, Montpelier Canyon, Idaho, X 1.

The test has strong prominent growth lines that pr <*s 

aborally over the umbilical wall, curve adorally over 

the flanks and on the ventral shoulder the growth lires 

turn aborally to form a broad, deep ventral sinus. 

Delicate lirae oriented transverse to the growth lires 

have a wavy appearance. The lirae extend only 

between growth lines, but are more or less continuous. 

The most distinctive feature of the test is the presence 

of two sets of nodes, one set of nodes on the ventral 

shoulder or adjacent to it, and the other set of nodes on 

the umbilical shoulder. The nodes are high, slender and 

very distinct; there are no ribs or raised areas connecting 

tHe nodes. The nodes are also present on the interral 

mold but somewhat subdued. There is a slight variation in the prominence of the nodes on the interaal 

mold. There is also some degree of variation in the 

nodes on the ad apical half of the first volution. On tl is 

part of the conch there is essentially only one node, and 

it has the appearance of a short rib in some specimen. 

In other specimens there is a distinct node on the
24 AMERICAN TRIASSIC COILED NAUTILOIDS

umbilical shoulder that slopes gradually towards the 

venter but there is no node on the ventral shoulder. 

One such specimen (pi. 4, figs. 8, 9, 10) shows strong 

similarities to Parametacoceras of the Pennsylvanian and 

Permian. The test of the adapertural first one-half 

volution is composed of delicate transverse and longitudinal ridges that give this portion of the conch a 

granular appearance. On one of the paratypes (pi. 2, 

fig. 8) there are, at a diameter of 15 mm, two depressed 

areas on the margins of the venter. These depressed 

areas are L-shaped and approximately 5 mm long. 

The borders of these depressed areas slope gradually 

on to the surface of the conch, producing no ridge or 

markings at the contact. The significance of these two 

symmetrical depressions is unknown.

The sutural elements are simple, consisting of a broad 

shallow ventral lobe, an adjacent shallow lateral lobe on 

the flanks, a short shallow lateral saddle on the umbilical 

shoulder following to the umbilical seam over the umbilical wall in almost a straight line. A short but 

distinct annular lobe is present. At a diameter of 15 

mm the suture is essentially straight.

The siphuncle is subcentral and very small. In the 

immature part of the conch the siphuncle is central.

Dimensions (in millimeters} of holotype (U.S.N.M. 107069)

Diameter of conch__________________________________ 69. 5

Height of last whorL____________________________ ____ 30. 0

Width of last whorl___________-_---_-_------________ 44. 8

Height of umbilical shoulder on the most adapical whorl. _ 13. 5

Diameter of umbilicus______________________________ 24. 5

Depth of umbilicus.________________________________ 15. 0

Impressed zone______________---__--_--__-____-_____ 3. 0

Remarks.—The type of Mojsvaroceras as picked by 

Hyatt and illustrated and described by Mojsisovics 

(1882, p. 267, pi. 88, figs. 1, 2) has a smooth conch for 

the first \Yz volutions; thereafter marginal nodes are 

developed on the ventral and umbilical shoulders. 

Metacoceras (Mojsvaroceras) jrenchi has lateral nodes 

developed after the K volution and thus differs in this 

respect from the genotype. A study of other species 

included in this genus by Mojsisovics shows that he 

included forms that developed ornamentation at an 

early stage. Metacoceras (Mojsvaroceras} jrenchi is a 

very distinctive form characterized by its rapidly expanding conch, the nodes on the ventral and umbilical 

shoulders, and the shape of its whorl section.

Mojsvaroceras has been recorded from the Alpine, the 

Himalayan, the northern Siberian, and the California 

Triassic regions. It ranges from the Scythian to the 

Karnian. The only other Scythian species of this 

subgenus known is Metacoceras (Mojsvaroceras) subaratum from the Olenek region of northern Siberia. 

Mojsvaroceras is very abundant in the Anisian in the 

Alpine and Himalayan regions. Smith (1927, p. 105)

states that there are some forms in the middle Triassic 

of North America that may belong to this genus. One 

Ladinian species is known from the Alpine Triassic. 

In the Karnian only a few species are known from the 

Alpine region, one from the Himalayas and one from 

the Hosselkus limestone of California.

Occurrence.—Upper shale member (Columbites zone), 

Thaynes formation, Montpelier Canyon, Idaho, sec. 31, 

T. 12 S., R. 45 E. and Hot Springs, Idaho, sec. 18, T. 

15 S., R. 45 E.

Types.—Holotype, U.S.N.M. 107069; paratypes 

107070-107078.

Genus PARAMETACOCERAS Miller and Owen, 1934

Genotype: Parametacoceras bellatulum Miller and Owen

In their discussion of the genus Foordiceras, Miller 

and Youngquist (1949, p. 96) recommended suppressing 

Parametacoceras as a synonym of Foordiceras. This 

interpretation is held to be untenable for mary of the 

reasons mentioned in the discussion of Tainionautilus 

and Foordiceras (pp. 17, 26). The subquadrstic cross 

section of the whorl and the ornamentation show a 

close affinity to Metacoceras as originally pointed out 

by Miller and Owen (1934, p. 232-233); their original 

description is as follows:

Conch tarphyceraconic and typically slightly evolute. Whorls 

subquadrate in cross section. Umbilicus large and perforate. 

Aperture marked ventrally by a broad deep rounded 1 yponomic 

sinus. On mature portion of the conch lateral sides of whorls 

bear short transverse ribs. Each suture forms very shallow 

broadly rounded ventral, lateral, and dorsal lobes and these 

are separated by similar but more narrowly rounded ventrolateral and dorso-lateral saddles. Siphuncle small, subcentral 

or subventral in position, and orthochoanitic in structure.

Possibly Parametacoceras is actually the ancestral 

group of Pleuronautilus. It is only superficially similar 

to Foordiceras as defined by Miller and Youngquist 

(1949). As interpreted here, Parametacoceras includes 

only P. bellatulum Miller and Owen, the genotype, 

P. schucherti Miller, P. crassus (Hyatt), and possibly 

P. nikitini (Tzwetaev), all from the Pennsylvanian. 

"Parametacoceras" praecursor (Girty) from the Leonard 

formation of West Texas and "Parametacoceras" 

venustum Reed from the Upper Productus limestone of 

the Salt Range, India, the writer assigns to the genus 

Pleuronautilus.

Genus TAINOCERAS Hyatt, 1883 

Genotype: Nautilus quadrangulus McChesney

The genus Tainoceras is well represented in rocks of 

middle Pennsylvanian to late Permian age throughout 

the world. It is here proposed to include a Triassic 

species. The best and most recent description of the
TAINOCERATIDAE

genus is that by Miller and Youngquist (1949), quoted 

in part as follows:

Conch nautiliconic but not deeply involute, and typically 

whorls are subrectangular in cross section as they are depressed 

dorsoventrally, flattened laterally and ventrally, and only 

slightly impressed dorsally [see text fig. 71]. The volutions are 

few in number. The umbilicus is large and open, the umbilical 

shoulders are abrupt, and the umbilical walls are steep. On 

each of the ventrolateral zones of the conch there is a single row 

of nodes that border a median sulcus or flattened zone. Growth 

lines indicate that the aperture bears a broad shallow lobe on 

the ventral, lateral, and dorsal sides of the conch—these are 

separated by very narrowly rounded or subangular saddles that 

center on the ventrolateral zones of the conch and the umbilical 

seams. As a result of the ventral nodes, the sutures are sinuous 

and commonly asymmetrical as they cross the ventral zone. 

At the umbilical shoulders which in some cases are nodose there 

is a marked change in the adoral curvature of the sutures. The 

siphuncle is orthochoanitic in structure and is more or less subcentral in position but typically located much closer to the 

venter than the dorsum. The septal necks are short but straight, 

the connecting rings are not expanded appreciably within the 

camerae, and the segments of the siphuncle are therefore essentially cylindrical in shape.

" Trematodiscus" klipsteini Mojsisovics from the 

Alpine Karnian resembles typical Paleozoic representatives of Tainoceras very closely. It bears prominent 

nodes on each ventrolateral shoulder and a double 

row of nodes on the venter. This species is more 

involute than any Paleozoic species of Tainocreas, the 

outer whorls inclosing more than half of the inner 

whorl. However, in all other morphologic features 

this Triassic form shows closer relationships to Tainoceras than to any other genus. Mojsisovics (1902, p. 

236-237) placed this species in his new genus Thuringionautilus and noted its similarity to typical Tainoceras. 

He considered it to be nearer Germanonautilus because 

in the ontogeny the ventrolateral nodes appeared before 

the nodes on the venter. This is precisely what is 

found in at least some of the Paleozoic Tainoceras.

It is always difficult to ascertain the affinities of 

stratigraphically widely separated species. Pennsylvanian and Permian species are numerous and widespread ; the only Triassic species even closely related is 

Tainoceras klipsteini whose morphological similarity is 

great. The same problem exists with bringing together 

in one genus Aulametacoceras mckeei and Nautilus 

rectangularis from the Alpine Karnian. One can easily 

ask, "Where are the intervening forms?" It is of 

course feasible to consider T. klipsteini as an aberrant 

development of Germanonautilus or keep it in the genus 

Thuringionautilus as suggested by Mojsisovics. However, it does not even reasonably resemble the genotype 

of Thuringionautilus, T. jugatonodosus. The writer 

believes that so striking a feature of ornamentation as 

the double row of ventral nodes, which is developed in 

only one stock of late Paleozoic nautiloids, is a monophyletic development and that provisionally it is be?t 

to place the Triassic species in this genus. It is well 

to note that no monographic works on Alpine Triassic 

nautiloids have appeared since those by Mojsisovics 

(1873-1902) and Diener (1919).

Distribution of species of the genus Tainoceras

Species Stratigraphic distribution Geographic distribution

Tainoceras cavatum Hyatt 1891 ___________ __

T. clydense Miller and Kemp 1947_ __________

T. comptum Reed 1944_________________ _

T. debile Reed 1944___.____________________

T. duttoni Hyatt 1893______________________

T. klipsteini ( Mojsisovies) 1882______________

T. mingshanense (Kayser) 1883 _ _____________

T. monolifer Miller, Dunbar, and Condra 1933.

Permian (Leuders? formation)_________

Permian (Clyde formation)____________

Permian (Upper? Productus limestone).

T. murrayi Miller and Unklesbay 1942.________

T. nebrascense Miller, Dunbar, and Condra 1933-

T. nodocarinatum (McChesney) 1859_ __________

T. noetlingi subglobosum Reed 1931___-__-_-___- 

T. occidental (Swallow) 1858__--_____---_____-

T. orientate (Kayser) 1883___________________

T. quadrangulum (McChesney) 1859____________

T. rotundatum Miller, Dunbar, and Condra 1933. 

T. schellbachi Miller and Unklesbay 1942________

T. toulai (Gemmellaro) 1888_ _____'_____________

T. trautscholdi (Waagen) 1879_________________

T. trimuense Reed 1944_______________________

T. unklesbayi Miller and Youngquist 1949_______

T. wyomingense Miller and Thomas 1936________

T. zmajevacense Simic 1933____________________

Permian (middle) _ 

Triassic (Karnian). 

Permian (middle) _. 

Pennsylvanian

Pennsylvanian (Lecompton limestone)_________

Pennsylvanian-Permian (Wabaunsee group to

lower Permian). 

Pennsylvanian _____________----___-_------_-

Permian (Productus limestone)________________

Permian (lower)______________--__-___----_--

Permian (middle)____________________________

Pennsylvanian- _____________________________

Pennsylvanian (Oread limestone)______________

Permian (Kaibab formation)__________________

Permian (Sosio beds)_______-__-_____---_----

Upper Carboniferous----_____________________

Permian (Lower Productus limestone)____-__-__

Permian (Toroweap formation)________________

Pennsylvanian (Casper formation)_____________

Permian (upper)__________---_____-___-----_

Ballinger, Tex. 

Baylor County, Tex. 

Salt Range, Pakistan.

Do.

New Mexico, Ariz. 

Alps. * 

Kiangsi, China. 

Mid-Continent region,

U. S. A. 

Oklahoma. 

Nebraska.

Illinois.

Salt Range, Pakistan.

Kansas.

Kiangsi, China.

Illinois.

Nebraska.

Arizona.

Sicily.

Russia.

Salt Range, Pakistan.

Arizona.

Wyoming.

Yugoslavia.
26 AMERICAN TRIASSIC COILED NAUTILOIDS

Genus COOPEROCERAS Miller, 1945 

Genotype: Cooperoceras texanum Miller

This genus is another aberrant development out of 

Metacoceras that is present in the Permian. Cooperoceras is characterized by the presence of "long slender 

hollow paired ventrolateral spines that project ventrolaterally and are distinctly recurved" (see text fig. 7E). 

Only the genotype species is assigned with certainty to 

this genus. "Metacoceras" spinosus Kruglov of the 

Middle Permian Artinskian beds of Russia may belong 

to this genus. The genus as far as is known is confined 

to the Permian, and there are no Triassic nautiloids 

similar to it. A full discussion of the genus can be 

found in Miller (1945) and Miller and Youngquist 

(1949).

During the middle and late Permian there was extensive diversification of the Tainoceratidae. Four 

genera of nautiloids (Tainionautilus, Tirolonautilus, 

Aulametacoceras, and Cooperoceras) became established. 

Each of these genera has a restricted stratigraphic and 

geographic range. All these forms have a ventral 

furrow or furrows that is a new morphological feature 

not acquired previously by any stock of Pennsylvanian 

or Permian nautiloids except Metacoceras sulciferum. 

Aulametacoceras is represented in the Karnian by, 

possibly one species, and Tainionautilus in the Scythian 

by one species.

Genus TAINIONAUTILUS Mojsisovics, 1902

Genotype: Nautilus transitorius Waagen

When Mojsisovics first established this genus (1902, 

p. 232), he placed it in the family Temnocheilidae. He 

considered it to be transitional with the genus Tainoceras 

through Nautilus trautscholdi Waagen. Waagen (1879, 

pp. 54, 55) first pointed out the relationship between 

his species, Nautilus transitorius and Nautilus trautscholdi (=Nautilus tuberculatus Trautschold, non 

Sowerby). For the purpose of this study it probably 

would not have been necessary to make extensive comments on this genus except that recently Miller and 

Youngquist (1949) have discussed it and they recommended suppressing the genus and placing its forms in 

Foordiceras. The writer differs with this interpretation. 

For the sake of completeness it should be mentioned 

that Foord (1891, p. 136) included the group of Nautilus 

trautscholdi (Tainionautilus) inthegexmsPleuronautilus.

The shape of the conch and ornamentation differ 

considerably from either of the above genera. Part of 

Waagen's description of N. transitorius, the genotype, 

is as follows:

The general form of this species is very different according to 

the age of the shell.

The whole shell appears thick disciform, with wide and rather 

shallow umbilicus. The transverse section of the whorls is

somewhat squarish, the outer or ventral part of the shell being 

flat with a shallow depression in the middle. The lateral parts 

of the whorls are perpendicular, and form a distinct rngle with 

the external part. The umbilicus is surrounded by a distinct 

umbilical wall, which forms a more or less distinct edg^ where it, 

unites with the lateral parts of the whorls.

In the young shell the first circuit has a diameter of about 

17 mm, being pierced in the middle by a central aperture of about 

5 or 6 mm in diameter. The commencement of the shell is quite 

smooth (the entire form of the "calotte" not being oHervable) 

and very depressed, the transverse section about twice as broad 

as high; but already towards the end of the first circuit the ornamentation of the shell begins to appear. This consists cf a prominent crest along the umbilical edge and of low folds on the 

outer margin of the whorl, where the lateral and external parts 

of the shell unite. As the shell grows larger these folds increase 

considerably in height, and extend more and more towards the 

crest which surrounds the umbilicus. There may 1 ave been 

about fifteen of these folds on the third volution, tow many 

there may have been on the second is not observable. On all 

these inner whorls the external part of the shell seeirs to have 

been entirely smooth, without marked depression on tl ? middle.

On the last whorl the sculpture changes considerably. Already 

towards the end of the third volution the crest on the umbilical 

margin thickens at certain intervals, and generally on? of these 

nodular thickenings corresponds to two of those folds on the 

lateral parts of the whorl. On the last whorl now this crest is 

entirely resolved into single high knobs along the umbi''cal edge, 

and no proper crest remains. These knobs unite with alternate 

high thick ribs, which come from the external margin of the 

whorl, and are highest on that margin. Between tl ose there 

are other ribs equally high on the outer margin of the whorl, 

but which disappear gradually towards the umbilical edge. The 

whole system of sculpture becomes less prominent towards the 

the mouth of the shell.

The strong ribs which cover the lateral part of the last whorl 

extend on this whorl in a somewhat retrograde direction to the 

external or ventral part of the shell, up to near the middle of it, 

and terminate there as two very low longitudinal ridges which 

border a tolerable broad medial depression on both sidis.

It is very difficult to observe what form the sutures of the 

septa may have possessed, as the whole specimen is covered with 

its shell, but it seems that there were sinuosities both on the 

sides and on the external part of the whorl.

I am not able to indicate anything as to the numbe" of septa 

in one whorl, but the siphon is clearly observable on one of the 

septa. It is very narrow, and in its position nearer th<> internal 

than the external side of the whorl.

From the description and illustration of the genotype 

species by Waagen, it is readily seen that tl a. shape 

of the whorl section is approximately square with 

abrupt imbilical walls (see text fig. 7 A). The genotype 

of Foordiceras, F. goliathus (Waagen) has no umbilical 

edge, or a distinct umbilical wall. The ornamentation 

of the two forms is different. In Tainionautilus the lateral folds or ribs extend onto the venter and terminate 

at the ventral furrow. The venter of at least the genotype of Foordiceras is smooth throughout growth. Also, 

Foordiceras shows no development of a crest ard nodes 

on the umbilical shoulder such as are developed in 

T. transitorius. The trapezoidal conch of Foordiceras
TAINOCEEATIDAE 27

and differences in ornamentation appear to make it 

improbable that these two genera are related.

Only five species have been referred to this genus, 

T. fugax Mojsisovics, from the Bellerophon Limestone, 

the genotype T. transitorius (Waagen), T. wynnei 

(Waagen), T. multicostatus (Reed), and T. sp. Reed 

from the Productus Limestone of the Salt Range, Pakistan. T. trachyceras Frech from the Skythian beds of the 

Salt Range has also been placed in this genus (pi. 19, 

fig. 3). Thus the known range of the genus is upper 

Permian to Lower Triassic.

Reed (1944, p. 356) considered TainionautUus to be 

a subgenus of Metacoceras and stated

the nearest allied species to M. wynnei (Waagen) seems to be 

M. sulciferum Miller and Thomas (1936, p. 729, pi. 97, figs. 4-5) 

from the Casper formation of Wyoming, for they both possess 

the characteristic median groove on the venter.

Several species of Metacoceras show a binodal type of 

ornamentation in which the nodes are elongated onto 

the flanks and which have steep umbilical shoulders. 

To my knowledge, M. sulciferum is the only species of 

that genus possessing a median furrow. With only 

five isolated species of TainionautUus so far recorded 

and none of these at the disposal of the writer, it is 

difficult to ascertain the affinities of this genus. The 

writer tentatively accepts Reed's (1944) interpretation 

as probably most correct (that TainionautUus is an 

aberrant development derived from Metacoceras) but it 

it is here given generic rank. No North American 

species are referred to this genus.

Genus TIROIONAUTIIUS Mojsisovics, 1902 

Genotype: Nautilus crux Stache

Miller and Youngquist (1949, p. 80) questioned the 

validity of this genus and stated " * * * it seems 

rather doubtful if they [species of TirolonautUus] differ 

sufficiently from typical Tainoceras, Foordiceras, and 

Metacoceras to be regarded as generically distinct." 

The four species assigned to this genus all come from 

the Bellerophon Kalk of the Alps. Neither the present 

author nor Miller and Youngquist have had an opportunity to study any specimens of these species, but it 

appears that the ornamentation is distinctive enough to 

distinguish this group from Metacoceras and Tainoceras. 

Middle and late Permian time was a period of great 

experimentation and diversification in the Tainoceratidae. This experimentation is well illustrated by such 

genera as Cooperoceras, TainionautUus, and Aulametacoceras. Rather than place TirolonautUus in synonymy 

of other genera, this genus is considered to be just 

another aberrant evolutionary development with a 

narrow stratigraphic and geographic range.

Mojsisovics (1902, p. 233) diagnosed the genus as 

follows:

Die aus Metacoceras hervorgegangenen Formen, welche l'» 

jetzt bios aus dem permischen Bellerophonkalk Stidtirols bekamt 

sind, unterscheiden sich von Metacoceras, mit welcher Gattung 

sie sonst gut ubereinstimmen, hauptsachlich durch die furchenformige Langseinsenkung in der Mitte des Externtheiles. E'e 

Involution ist nach den Abbildungen Stache's etwas starker Ms 

wie bei dem geologisch alteren Metacoceras und nahert sich d^n 

Einrollungsverhaltnissen von Mojsvaroceras. Die kraftig er*.- 

wickelten Marginalknoten sind schrage gestreckt und setz^n 

sich bei TirolonautUus crux Stache von diesen schrage gestellton 

Randknoten rippenartige Verlangerungen auf den Externth^il 

fort, in dessen vertiefter Mittellinie sie von beiden Seiten unter 

einem spitzigen Winkel zusammenstossen. Eine Form, Tirolonautilus Sebedinus Stache besitzt auf der Mitte der Flank^n 

schwielige, rippenartige Auftreibungen. Die dritte, in diese 

Gattung gehorige Art, welche den typischen Formen von Metacoceras am ahnlichsten sieht, ist TirolonautUus Hoernesi Stacl e. 

Aber auch bei diesser Art sind wegen der starkeren Einrollung 

die Marginalknoten des vorletzten Umganges im Nabelraume 

nicht mehr sichtbar.

Mojsisovics' description can be summarized as 

follows:

This genus, derived from Metacoceras, is known only from the 

Bellerophon Kalk of the Alps. It differs from Metacoceras 

namely in the presence of a median furrow. Its involution is 

intermediate between that of Metacoceras and Mojsvaroceran. 

The strong nodes on the ventral shoulders of TirolonautUus crux 

are elongated and oblique. They form a conspicuous angul^ 

ventral shoulder and there are ribs that project adapically from 

these marginal nodes, over the venter towards the deep median 

furrow. TirolonautUus sebedinus Stache has radial fold-like 

ribs on the flanks. TirolonautUus hoernesi Stache, which is 

most similar to Metacoceras is more involute and the ventrolateral nodes of the earlier whorls are not visible in the umbilicus.

Mojsisovics did not designate a type for his genu-*; 

TirolonautUus crux (Stache) (text fig. QF) is hereby 

selected as the type for this genus.

TirolonautUus hoernesi is very similar to Metacoceras 

sulciferum Miller and Thomas of the Stenopoceras bed"\ 

Casper formation, Wyoming; both of these species have 

a characteristic median furrow. No other species of 

Metacoceras has a median furrow like M. sulciferum. 

The remaining two species of TirolonautUus because of 

their distinctive ornamentation are not directly conparable to any other known Permian nautiloid.

Genus AUIAMETACOCERAS Miller and Unklesbay, 1942 

Genotype: Aulametacoceras mckeei Miller and Unklesbay

This genus is characterized by a conch with tl ^ 

general physiognomy of Metacoceras but with longitudinal ribs on the venter (see text fig. 7(7). Tl <v 

genotype is from the Kaibab limestone, Arizona. Only 

one other species, NautUus rectangularis Hauer from the 

Alpine Karnian, has been placed in this genus by its 

authors. This genus is well described by Miller ar'i
28 AMERICAN TRIASSIC COILED NAUTILOIDS

Unklesbay (1942, p. 726) and by Miller and Youngquist 

(1949, p. 93), and need not be repeated here.

The Triassic species, A. rectangulare, has a similar 

development of ribs on the venter as in A. mckeei but 

has a subquadratic conch in contrast to a subhexagonal 

conch. The Triassic species also has no nodes on the 

umbilical shoulders. A. rectangulare has previously 

been placed in Trematodiscus, Coelonautilus, and 

Thuringionautilus but is not similar to any of these 

genera. Even though only two stratigraphically and 

geographically widely separated species of this genus 

are known, the writer believes that a tentative plan of 

following the procedure of Miller and Youngquist is the 

best one. With our present knowledge of PermianTriassic nautiloids it is difficult to separate the two 

species on a logical basis except that of time and until 

more material is available it seems best to bring these 

closely similar species together into one genus.

Genus GERMANONAUTILUS Mojsisovics, 1902

Genotype: Nautilus bidorsatus Schlotheim

The original diagnosis of this genus by Mojsisovics 

(1902, p. 235) is quoted here in part:

Als Typus dieser Gattung betrachte ich Germanonautilus 

bidorsatus. Die aus der Zone des Ceratites trinodosus von mir 

beschriebenen Formen Nautilus privatus, N. Tintoretti, N. 

salinarius, and N. ind. aff. salinario, welche in allem wesentlichen 

Merkmalen mit den glattschaligen Abanderungen des germanischen Bidorsatus-Typus ubereinstimmen und offenbar derselben 

Gattung wie dieser zuerechnet werden ratissen, unterscheiden 

sich von den in der gleichen Lagerstatte auftretenden Arten von 

Mojsvaroceras lediglich durch das vollstandige Pehlen von Pilae 

und Knoten, und erscheint es zweckmassig, diesem glatten, 

offenbar aus Mojsvaroceras hervorgegangenen Typus unter 

einem selbstandigen Gattungsnamen zusammenzufassen. Die 

rasch in die Hohe und Breite wachsenden Gehause besitzen in 

der Regel einen mehr winiger rechteckigen Querschnitt (text 

fig. 9). Dir Umgange umfassen einander ziemlich stark, ohne 

aber den tiefen Nabel zu verschliessen. Die Breite der Umgange 

uberwiegt in der Regel bedeutend die Hohe. Der Externtheil 

ist breit, abgeflacht, manchmal auch leicht concav eingebogen.

Der Nabelrand, in dessen nachster Nahe die grosste Breite der 

Umgange erreicht wird, ist deutlich markirt, abgesturxpft oder 

kantig. Die Schale ist in der Regel glatt, aber von kraftigen 

zuwachsstreifen bedeckt, welche auf den Planken vom Nabelrande weg, schrage gegen riickwarts gewendet, dem kantigen 

Marginalrande zustreben und auf dem Externtheile einen starken, 

riickwarts gewendeten Sinus beschreiben (G. Breunneri, G. 

Cassianus, G. Schloenbachi). Bei einigen Pormen treten Marginalknoten auf, was im Hinblick auf die genetischen Relationen 

als eine atavistische, an Mojsvaroceras oder Temnocheilus erinnernde Erscheinung aufgefasst werden Kanri. Da diese Arten 

in alien tibrigen Merkmalen vollstandig mit den glattschaligen 

Reprasentanten ubereinstimmen, erscheint es wohl iib^r fliissig, 

sie unter einer besonderen generischen Bezeichnung abzutrennen.

Die Loben von Germanonautilus schliessen sich den Loben mit 

steiler Nabelwand versehenen Arten. von Mojsvaroceras an. 

Die Kammerwande stehen sehr gedrangt, bilden auf der Externseite einen seichten, flachen Lobus oder tibersetzen den Externtheil geradlinig; auf den Flanken ist ein gleichfalls ziemlicb 

weiter, etwas tieferer Lobus vorhanden, Kleine, abgerundete 

Sattel stehen auf dem Aussen- und dem Nabelrande.

Ein Internlobus (Annularlobus) ist vorhanden * * * Der 

dicke Sipho steht, ahnlich wie bei Mojsvaroceras, in oder unter 

der halben Miindungshohe.

Mojsisovics' diagnosis can be summarized as follows:

The type of this genus is Germanonautilus bidorsatus. Germanonautilus is undoubtedly derived from Mojsvaroceras and 

differs from that genus in the complete lack of ribs or nodes 

The whorl section is subquadrate, generally wider tl ",n high. 

The venter is broad, flattened, and often slightly concave. 

The umbilical shoulder is sharply rounded. The shell is smooth 

except for growth lines which trend adapically over the whorl 

sides and form a sinus on the venter. The suture forms a shallow 

ventral and a broad, deeper lateral lobe. An annular lobe is 

present. The siphuncle is approximately central in position as 

in Mojsvaroceras.

Mojsisovics included in this genus two species (G. 

cassia.nus and G. schloenbachi), which have distinct 

nodes on the ventral shoulders, but he exprersed the 

possibility that these two species did not belong to 

Germanonautilus and should perhaps be placed in a 

new genus. The shape of the conch agrees quite closely 

with that of the genotype of Germanonautilus. However, without having seen specimens of these species

Distribution of species of the genus Germanonautilus

Species

Germanonautilius advena (Fritsch) 1902 __

G. bidorsatus (Schlotheim) 1832 . _

G. breunneri (Hauer) 1847 _____

G. brooksi Smith 1927- _ ___ ___ ____ _________

G. cassianus (Mojsisovics) 1882_ ___

G. furlongi Smith 1914 __ _ _-___-____ __________

G. johnstoni Kummel n. sp__

G. montpelierensis Kummel n. sp _ __ .

G. nodosus (Minister) 1831.- __ __

G. salinarius (Mojsisovics) 1882 _____

G. schloenbachi (Mojsisovics) 1873 _

G. spurnosus (Fritsch) 1902_ _ _ ___

G. siievicus (Philippi) 1898 ___.._ _

Stratigraphic distribution

-___do____ ___--_---

__-_do--_- ----- -__ __ -___-_

__-- _do_-_---_- __________________ _ _ — ____. _

_____do_----___ -----------------------------

-___do---_-_- -----------------------------

Geographic distrit ntion

Germany.

Do.

Do.

Do.
TAESTOCEKATIDAE

the writer refrains from changing the taxonomic status 

of these forms. Germanonautilus appears to be a 

derivative of Mojsvaroceras or Metacoceras sensu stricto 

differing mainly in the greater involution and general 

loss of ornamentation.

Germanonautilus brooksi Smith 

Plate 3, figures 1-10.

1927. Germanonautilus brooksi Smith, U. S. Geol. Survey Prof. 

Paper 141, p. 105, pi. 52, figs. 7-10.

Smith's description of this species is as follows:

Shell moderately evolute, with open umbilicus, whorls broader 

than high, deeply embracing. Cross section low, crescentic, 

with broadly arched venter, more sharply curving flanks, and 

steep umbilical walls. There is only a faint suggestion of the 

ventral shoulders usually characteristic of the group and no 

remnant of the nodes. Surface shows fine striae of growth and 

spiral lines. The striae of growth bend backward on the venter, 

forming a deep broad sinus. The septa show a broad, shallow 

ventral lobe, and a short funnel shaped ventral [dorsal] or annular 

lobe. Siphuncle central.

The specimens figured and described by Smith came 

from U.S.G.S. locality 9384, south bank of Yukon 

River opposite mouth of Nation River, Alaska. In 

addition to this holotype and paratype there are available one specimen from the same locality which can 

thus be considered a topotype, U.S.N.M. 107087, and 

a specimen from U.S.G.S. locality 9385, Yukon River 

Ys mile northeast of the mouth of Nation River, Alaska. 

Both the holotype and topotype seem to be immature 

specimens, thus accounting for the broadly rounded 

ventro-lateral and umbilical shoulders. The fourth 

specimen, U.S.N.M. 107086, and the paratype are 

presumably late adolescent or early mature individuals. 

The ventral and umbilical shoulders are distinct, the 

flanks converge towards the venter, and the venter is 

broadly rounded. The umbilical walls are gently 

rounded but steep and the umbilicus is deep. The 

sutures have a very shallow ventral lobe and a broad 

shallow lateral lobe with a slight saddle on the umbilical 

shoulder. The first one-half volution of specimen 

U.S.N.M. 107086 has delicate reticulate ornamentation. 

The siphuncle is central and large, measuring 3 mm in 

diameter.

Occurrence.—Holotype, paratype, and topotype from 

U.S.G.S. locality 9384, south bank of Yukon River 

opposite mouth of Nations River, Alaska, in Upper 

Triassic beds of Karnic age. Plesiotype U.S.N.M. 

107086 from U.S.G.S. locality 9385, Nation River, 

hillside % mile northeast of mouth of Yukon Valley, 

Alaska.

Types.—Holotype, U.S.N.M. 74206; paratype, U.S. 

N.M. 74206a; topotype, U.S.N.M. 107087; plesiotype, 

U.S.N.M. 107086.

232820—53———3

Germanonautilus furlongi Smith 

Plate 3, figures 12, 13; text figure 12

1914. Germanonautilus furlongi Smith, U. S. Geol. Survey Prof. 

Paper 83, p. 142, pi. 95, figs. 1, 2.

Smith's description of this species is as follows:

Form robust, whorls low, broad and trapezoidal in cross section, little embracing, and little indented by the inner whor?s. 

Sides converging toward venter. Umbilicus about one-fourth 

of the diameter of the shell. Umbilical shoulders subangular, 

inner walls very steep. Ventral shoulders rounded, venter 

broad and flat, without concavity. Siphuncle a little below tl 3 

middle of the chamber.

Septa close together, with gentle backward curve or the lobe en 

the flanks. Surface smooth, outer shell unknown.

Dimensions of the type specimen of Germaaonautilus furlongi

(mm) 

Diameter __________________________________________ P7

Height of last whorl_______-_________________________ 43

Width of last whorl-_______.___________.__-__ CO

Width of umbilieus--____-_-_---_____-_____--__---___ ?3

Involution.________________________________________ 8

Germanonautilus furlongi is very closely related to G. salinarivfi 

Mojsisovics of the same horizon in the Alpine province but hp,s 

the sides of the whorl somewhat more convergent and the uirbilicus narrower. It is still closer to Germanonautilus sp. ind. 

Mojsisovics and may be identical with that unnamed species.

Two fragmentary specimens are referred with quertion to this species. One is from the same locality as 

the holotype. This specimen, U.S.N.M. 32631, has 

only part of the phragmocone and living chamber c* 

only one side of the conch preserved. It is 118 mm in

FIQTJEE 12.—Diagrammatic cross section of the holotype of Germanonautilus furlmyi 

Smith (U.S.N.M. 74444) from Daonella dubia zone of Star Peak formation, Foss'l 

Hill, West Humboldt Range, Nevada, X 1.
30 AMERICAN TRIASSIC COILED NAUTILOIDS

diameter, but does not have the subangular umbilical 

shoulders of the holotype. This, however, may be an 

ontogenetic feature as the holotype is much smaller 

than this specimen. The other fragmentary specimen, 

consists of only two camerae plus a small part of the 

living chamber. The specimen is more quadratic in 

outline of the conch than the hojotype but appears to 

belong to this species.

Occurrence.—The holotype U.S.N.M. 74444 and 

specimen U.S.N.M. 32631 came from the Daonella dubia 

zone, Ceratites trinodosus subzone of the Star Peak 

formation, South Fork of American Canyon, Fossil 

Hill, West Humboldt Range, Nevada. Another specimen came from the same formation and horizon, on the 

north side of South Canyon, New Pass Range, Nevada.

Types.—Holotype U.S.N.M. 74444; specimen 

U.S.N.M. 32631.

Germanonautilus Johnstoni n. sp. 

Plate 3, figures 14, 15; text figure 13

One small specimen of 1% volutions, 42 mm across, 

is available. The specimen is especially noteworthy 

because it represents a nodose form of Germanonautilus 

related to G. cassianus and G. schloenbachi. The conch 

is rapidly expanding and at its maximum diameter the 

whorl has a subquadratic cross-section about 20 mm in 

height and 27 mm in width; the flanks converge toward 

the venter. The venter is essentially flat and the ventral shoulders well rounded. The flanks are convex and 

the umbilical shoulders subangular (text fig. 13). 

The umbilical wall is only slightly convex and practically vertical. The umbilicus is deep and measures 

11 mm at the maximum diameter of the conch. Up to 

the end of the first volution the flanks and both shoulders are more rounded.

On the ventral shoulders are low distinct ribs that 

curve adapically parallel to the trend of the growth 

lines, which form a deep hyponomic sinus. The ribs 

are discernable only over the rounded ventral shoulder 

and do not extend far on the venter or the flanks. The 

most adoral rib visible is 10 mm in length.

The suture forms a distinct lobe on the venl er and a 

broad concave lateral lobe. The siphuncle was not 

observed.

Remarks.—Only three species of Germanonautilus 

with ribs or elongated nodes on the ventral shoulders 

have been described. These are ff. cassianus, G. 

schloenbachi, and G. johnstoni. The first two species 

from the Alpine Karnian have very rapidly erpanding 

conchs with angular to subangular ventral shoulders. 

In G. cassianus the nodes are elongated parallel to the 

angular ventral shoulder. In G. schloenbachi the nodes 

are not parallel but elongated at a small angle from the 

subangular ventral shoulder. In neither species do the 

elongated nodes parallel the growth lines as in 6\ 

johnstoni.

Occurrence.—Star Peak formation, South Canyon, 

New Pass, Desatoya Range Nevada. Collected by 

F. N. Johnston.

Holotype.—U.S.N.M. 107088.

Germanonautilus montpelierensis n. sp. 

Plate 3, figure 11; text figure 14

A rather poorly preserved phragmocone from the 

Columbites zone at Hot Springs, Idaho is referred to 

Germanonautilus. The right side of the specimen and 

most of the venter has been crushed. The conch is 

evolute, rapidly expanded orad, and has a ralher deep 

perforate umbilicus. The phragmocone is the only 

portion of the conch preserved and consists of about 

\% volutions. The outline of the adoral camera is 

quadrate, measuring 42.6 mm wide and 33 mm high 

(text fig. 14). The venter is broadly arched and the 

ventral shoulders are obliquely rounded. The flanks 

are flattened and slope obliquely outward passing on 

to a strongly rounded umbilical shoulder. The^umFIQUEB 13.—Diagrammatic cross section of the holotype of Qermanonautilus Johns 

toni, n. sp. (U.S.N.M. 107088) from the Star Peak formation, South Canyon, New 

Pass. Desatoya Range, Nov., X 1.

FIGURE 14.—Diagrammatic cross section of the holotype of OermanorawtUus montpelierensis, n. sp. (U.S.N.M. 107089) from the Columbites beds, Thayres formation, 

Hot Springs, Idaho, X 1.
TAINOCEKATIDAE 31

bilical wall is oblique and arched; the extreme lower 

edge of the umbilical wall is turned in sharply into the 

umbilical seam. The inner whorls are much more 

rounded in cross section but still broader than high and 

the umbilical wall is more nearly vertical. The first 

adapertural one-half volution is ovoid in cross section 

and has no apparent umbilical shoulder. The umbilicus 

is rather narrow, deep, and perforate. It measures 25 

mm in width and is 15 mm deep. The umbilical perforation is 6 mm in diameter.

Only a few isolated parts of the conch have the test 

preserved. The growth lines are very delicate, closely 

spaced, and slightly sinuous on the flanks. The test is 

distinctive, however, in having delicate transverse 

striations or ridges. This feature is best observed on 

the umbilical wall, where slightly weather portions of 

the test emphasize the lines. The test also has delicate 

undulating longitudinal lines. This feature is not very 

conspicuous however, as the test is not well preserved. 

There is a small node on the flanks of the adapical half 

of the adapertural first one-half volution. As there are 

no other nodes on this specimen, probably because it 

is poorly preserved, the significance of this node is 

not known. The suture is preserved only on the 

flanks where it forms a broad concave lateral lobe. 

The siphuncle is central in position and is about 3 mm 

in diameter.

Remarks.—Oermanonautilus montpelierensis does not 

seem to be closely similar to any other species of the 

genus. It is more evolute than most species of Oermanonautilus. This species shows some affinities in 

form of its conch to species of SyringonautUus. G. 

montpelierensis is the first record of a Scythian representative of this genus; all the other species occur in 

Ansian and Karnian formations.

Occurrence.—Upper shale member, Columbites zone, 

Thaynes formation, Hot Springs, Idaho, sec. 18, T. 

15 S., R. 45 E. Collected by the author.

Holotype.—U.S.N.M. 107089

Germanonautilus spp. (of Nevada)

Two incomplete specimens from the Upper Triassic 

of Nevada can be assigned to Oermanonautilus but are 

not well enough preserved to identify specifically. The 

first specimen U.S.N.M. 107090 (U.S.G.S. loc. 11782) 

has only 2 cm of living chamber and 5 cm of phragmocone (measured along the venter) preserved. The 

venter is broadly rounded, flanks slightly convex and 

sloping sharply ventrad. Sutures are practically 

straight with only a slight ventral and lateral lobe. 

The growth lines are very coarse and show a broad 

rather deep sinus on the venter. The label accompanying this specimen reads as follows:

Upper Triassic, massive limestone Shoshone Range; by 

roadside % mile south of spring in mouth of Union Canyon, T^est 

front of Shoshone Range, Tonopah Quadrangle, Nevada.

This is presumably from the Lulling formation (see 

Muller and Ferguson, 1939).

The second specimen U.S.N.M. 107091 (U.S.G.S. loc. 

14344) consists of one half whorl with only one side 

and part of the venter preserved. No septa are visible, 

most of the specimen probably represents living 

chamber. The venter is broadly arched, grading to a 

sharp, subangular ventral shoulder. The flanks are 

convex and the umbilical shoulders are well rounded. 

This specimen came from the Cedar Range, 3% miles 

south of Bench Mark 6679, Tonopah Quadrangle, 

Nevada, in the Luning formation.

Germanonautilus spp. (of Alaska)

Two specimens are available for study from Alaska 

that clearly belong in Oermanonautilus but are too incomplete to warrant specific assignment. The first, 

U.S.N.M. 107092 (U.S.G.S. loc. 12393), is from the 

Gold Bay District, Alaska Peninsula, Alaska and ^as 

collected by W. R. Smith in 1924. The specimen is an 

essentially complete living chamber with part of the 

crushed phragmocone. The conch is very robust, 

measuring 57 mm in width and 54 mm in. height on the 

most adoral part of the living chamber. The verter 

is broadly rounded, flanks slightly convex grading on 

to a rounded and sloping umbilical wall. There r a 

broad shallow constriction on the flanks and verter 

about 2 cm back of the most adoral part of the specimen. The phragmocone is badly crushed but appears 

to be very much smaller in its general dimensions tl <vn 

the living chamber, indicating a rapidly expanding 

conch. Only part of a broad lateral lobe of the suture 

is visible. Position of the siphuncle is not known.

The second Alaskan specimen, U.S.N.M. 107093 

U.S.G.S. loc. 8895), is also the living chamber of a 

very robust individual. The specimen is 42 mm high 

and 58 mm wide, measuring the conch along the midpoint of the specimen and 110 mm in length along the 

venter. The venter and flanks are only broadly arcted, 

ventral and umbilical shoulders well defined rud 

rounded. The umbilical wall is con vex and steep. Tils 

specimen is from a 10-ft bed of dark noncrystalline 

limestone that is separated from Carboniferous limestones by a 50-ft covered interval along the south bank 

of the Yukon River about 1 mile above the Nation 

River, Alaska (see Martin, 1926, p. 96). Stanton 

(in Martin, 1926) has identified the following genera 

from this limestone bed: Rhynchonella, Terebrafrda, 

Spiriferina, Halobia, Aviculopecten, Natica,' and Nautilus. Thirty feet above this limestone bed characteristic Upper Triassic fossils were obtained. Stanton's
32 AMERICAN TRIASSIC COILED NAUTILOIDS

conclusions that the lower limestone (U.S.G.S. loc. 

8895) was probably Triassic is correct. However, the 

nautiloid described here does not aid in a more specific 

age determination.

Genus THURINGIONAUTILUS Mojsisovics, 1902 

Genotype: Trematodiscus jugatonodosus Zimmermann

Mojsisovics' original description is quoted here in 

full (1902, p. 236-237):

Von Germanonautilus sich abzweigende Gattung, welche sich 

durch die Erwerbung einer Externseulptur von Germanonautilus 

unterscheidet. Als Typus ist der durch eine auffallend lange 

Wohnkammer Umgang bemerkenswerte Thuringionautilus jugatonodosus Zimmermann anzusehen.

Diese Art, welehe aus dem Grenzdolomit des thuringisehen 

Keupers stammt, erwirbt auf dem letzten Umgange eine an den 

permischen Tainionautilus erinnernde Externseulptur. Die 

Mitte des Externtheiles ist ausgehohlt und wird beiderseits 

durch Langsleisten begrenzt, welche durch sehrage gegen vorne 

laufende Querjoche mit den auf der Marginalkante stehenden, 

in der Riehtung der Spirale verlangerten Marginalknoten verbunden sind. Auf dem vorletzten Umgange fehlen die Querjoehe 

sowie die Randknoten und sind nach Zimmermann's Beschreibung bios die Langsleisten vorhanden. Es geht hieraus klar 

hevor, dass ein directer genetiseher Zusammenhang mit Tainionautilus nicht besteht. Da in dem sonstigen Verhalten die 

grosste Uebereinstimmung mit Germanonautilus besteht, so ist 

es evident, dass Thuringionautilus bios als ein von Germanonautilus derivirfer, selbstandiger Typus zu betrachten ist.

Die zweite, in diese Gattung einzubeziehende Art ist der von 

mir friiher zu Trematodiscus gestellte Thuringionautilus rectangularis (Hau.), welcher ebenso wie Th. jugatonodosus sehr 

evolut ist und bei ganz iibereinstimmendem Entwicklungsgange 

sich durch eine grossere Anzahl von Externrippen unterscheidet.

Eine etwas weitergehende Verschiedenheit zeigt die dritte 

bekannte Art, Thuringionautilus Klipsteini Mojs., welche sich 

durch starkere Involution auszeichnet und durch die Sculptur 

ihrer Externseite mehr an Tainoceras erinnerb. Die Abstammung von Germanonautilus ist aber auch bei dieser Art leicht 

aus der ontogenetischen Entwieklung nachzuweisen. Es erscheinen namlich auf dem ersten Umgang die Marginalknoten 

friiher als die durch riiekwarts gewendete Querjoche mit diesen 

verbundenen Externknoten und sieht in diesem Stadium das 

Gehause vollkommen dem Germanonautilus Cassianus ahnlich.

Thuringionautilus besitzt wie Germanonautilus gedrangt 

stehende Kammerwande mit breiten Extern-und Laterallobus. 

Umbilicalsattel und Internlobus vorhanden. Sipho subcentral.

Mojsisovics' description can be summarized as 

follows:

The type of this genus is Thuringionautilus jugatonodosus 

(Zimmermann). Thuringionautilus is derived from Germanonautilus and differs from that genus in the presence of sculpture 

on the ventral region. The modifications on the venter are 

reminiscent of that found in the Permian Tainionautilus. The 

venter has a conspicuous ventral furrow with sharp borders. 

The sharply rounded ventral shoulder has oblique, elongated 

nodes that project adapically over the venter toward the border 

of the ventral furrow. The ventral nodes disappear adorally. 

A direct relationship with Tainionautilus is not indicated but 

rather a close relationship to Germanonautilus. A second species, 

T. rectangularis (Hauer), was previously placed in Trematodiscus.

It is evolute like T. jugatonodosus and is distinguished by its 

numerous ventral ribs. T. klipsteini Mojsisqvics is more involute and similar in its ornamentation to Tainoceras. Its 

derivation from Germanonautilus is evident from its ontogenetic 

development. The ventrolateral nodes appear earlie^ on the 

first volution than the ventral nodes and in this stage the conch 

is similar to Germanonautilus cassianus. Thuringionautilus, as 

Germanonautilus, has a depressed whorl section. The suture 

has a wide ventral and lateral lobe. An umbilical saddle and a 

dorsal lobe are present. The siphuncle is subcentral.

Of the three species assigned to this genus by Mojsisovics T. rectangularis, has subsequently beer placed 

in Aulametacoceras (Miller and Unklesbay 1942, p. 726). 

The similarity between the genotype species, A. mckeei, 

from beds of Leonard age, Arizona to the Karnian 

A. rectangulare is remarkable. "Thuringionautilus" 

klipsteini is tentatively placed in Tainoceras and is discussed under that genus. The existence of longitudinal 

ribs on the ventral reigon is found in four genera of 

the Tainoceratidae, namely Phloioceras, Trachyrautilus,

FIGURE 15.—Diagrammatic cross section of the holotype of Thuringionautilus juga. 

tonodosus (Zimmermann) from the Keuper of Germany, X 1. After Zi-namermann.

Thuringionautilus, and Aulametacoceras. The first two 

genera are clearly related to Pleuronautilus and need 

no further mention here. The last two belong to the 

Metacoceras-Mojsvacoceras evolutionary complex. In 

Thuringionautilus the presence of a deep ventral furrow 

offers additional problems. There are only two species 

of Aulametacoceras and one of Thuringionautilus so far 

reported. The only species of Thuringionautilus comes 

from the Keuper of Germany. The writer tentatively 

accepts the present taxonomic status of thes^ forms. 

The derivation of Thuringionautilus from Germanonautilus, as proposed by Mojsisovics is also believed to be 

correct. Possibly this genus descended directly from 

Mojsvaroceras. The similarity of Thuringionautilus 

jugatonodosus to the Permian Tainionautilus is thought 

to be superficial. With so few specimens and species 

of this genus it appears unwise to speculate too widely 

as to its affinities. This genus has not been reported 

from any North American strata of Triassic age.
TAINOCEKATIDAE 33

Genus PLEURONAUTILUS Mojsisovics, 1882 

Genotype: Pleuronautilus trinodosus Mojsisovics

This genus, with its 5 subgenera and approximately 

95 species, includes most of the highly ornamented 

Triassic nautiloids. The group includes Permian and 

Triassic nautiloids which have ribs with or without 

associated nodes. Mojsisovics' original description is 

given here (1882, p. 273):

Der Externtheil der rechteckigen, einander nur sehr wenig 

umhiillenden, weitnabeligen Formen ist, wie bei Temnocheilus, 

glatt, sculpturfrei, die Seiten sind dagegen in der Regel mit 

kraftigen, geraden oder leicht geschwungenen Rippen bedeckt, 

welche bei den meisten Formen mit einer oder mehreren Knotenspiralen versehen sind. Die init bios einer, marginal stehenden 

Knotenreihe ausgestatteten Formen erinnern an Temnocheilus, 

von welchem sie jedoch liecht durch die kraftigen Rippen 

unterscheiden werden konnen.

Die erste Halfte der ersten Windung ist bei einer Anzahl von 

Formen bios mit einfachen Querstreifen versehen, bei anderen 

(Pleuronautilus marmolatae, Pleuronautilus subgemmatus) kommen auf den Seitentheilen gekornte Langsrippen vor, wie bei 

Trematodiscus. Die Perforation des Nabels erreicht bei manchen 

Formen, wie bei Pleuronautilus superbus, einen sehr bedeutenden 

Umfang.

Kammerwande bei einigen alteren Formen, wie Pleuronautilus 

semicostattis und Pleuronautilus distinctus, gerade iiber den Externtheil verlaufend und seitlich einen flachen, breiten Laterallobus bildend, oder aber, wie bei der Mehrzahl der triadischen 

Formen, auch auf dem Externtheil zu einem flachen Externlobus 

eigebogen. Bei allem, in dieser Beziehung naher untersuchten 

Formen konnte ein kleiner Internlobus constatirt werden. (Text 

fig. 16.)

Mojsisovics' description can be summarized as follows:

Conch evolute, widely umbilicate, venter smooth, whorl sides with 

strong, straight or slightly sinuous ribs which in most forms have 

one or more spiral row of nodes. The first half volution in many 

species has merely simple cross striae, but other species have 

nodose strigations as in Trematodiscus. The umbilical perforation in several species, such as Pleuronautilus superbus, is very 

large. The suture is straight over the venter or with a shallow 

ventral lobe; the lateral lobe is broad and shallow. A small 

annular lobe is present.

Mojsisovics continued his description of Pleuronautilus, explaining his reasons for establishing the genus, 

and its probable affinities. This part is pertinent to 

the following discussion and will be quoted here in full 

(translation from Foord p. 135-136, 1891).

I was at first disposed to make Pleuronautilus a distinct division of Temnocheilus; but the near relationship between Pleuronautilus and Trematodiscus on the one hand, and the distinctness 

of these two genera from the coexisting Teinnocheilus-stock on 

the other hand, determined me to introduce Pleuronautilus as a 

distinct genus.

The near relationship between Trematodiscus and Pleuronautilus can easily be made out. First, the variation in certain 

species of Carboniferous Tremaiodiscus must be pointed out; this 

consists in the development in advanced age of a full, rounded 

shell, free from sculpture. The union of the typical Trematodiscus sculpture with the lateral ribs of Pleuronautilus is observable in Gyroceras tessellatum, de Koninck, G. binodosum, Sfjndberger, G. coslatum, Goldfuss, Cyrtoceras rugosum, Fleming, as 

well as in Nautilus nodoso-carinatus, F. Roemer, of the Coal Measures. Secondly, the characters presented by Pleuronautilus 

marmolatae (in which the Trematodiscus sculpture passes directly 

into the Pleuronautilus sculpture), added to the appearance in 

other Pleuronautili of several nodose-ridged species (Pleuronautilus trinodosus, P. Mosis, P. Cornaliae, P. Fischeri etc.) 

which are apparently equivalent to the nodose-keeled species of 

Treamtodiscus, speak in such a convincing manner in favour of 

the genetic connection between the two genera that we do not 

hesitate to place forms with smooth surface and creiiulated 

ridges, such as P. (Phloioceras) gemmatus, in the genus Pleuronautilus.

As is indicated in Gyroceras aigoceras, de Koninck (which 

possesses the sculpture of Pleuronautilus), it seems quite possible that some Pleuronautili have been developed from fcrms 

with open whorls without passing through a Trematodiscus 

stage * * *

The oldest Pleuronautili known to me are found in the Productus Limestone of the Salt Range, and in the Permian-Kalkstein 

of the Araxes Pass in Armenia.

Foord (1891, p. 134-138) emended this genus to 

include a variety of Late Paleozoic forms. However, 

species referred by Foord to Pleuronautilus have since 

been placed in at least six other genera. Foord's broad 

interpretation of the genus is untenable and cannot be 

followed.

Arthaber (1896) slightly emended the description of 

Pleuronautilus by Mojsisovics and established tbree 

form groups into which he placed all the species of 

Pleuronautilus known at that time. Arthaber's gronps 

are those of Pleuronautilus ampezzanus, Pleuronautilus 

mosis, and Pleuronautilus subgemmatus.

Hyatt (1900, p. 525) proposed the family Pleuronautilidae, and included in it Pselioceras Hyatt, Pleuronautilus Mojsisovics, Enoploceras Hyatt, EncoUoceras 

Hyatt, and Anoploceras Hyatt. The last three ger^ra 

were newly described by Hyatt in the 1900 edition 

of the Zittel-Eastman Textbook of Paleontology. The 

genotype of Enoploceras is Nautilus wulfeni Mojsisovics, 

that of EncoUoceras is Pleuronautilus superbus Mojsisovics, and that of Anoploceras is Pleuronautilus ampezzanus (Loretz). Since Hyatt's publication these tl ree 

genera have generally been considered subgenera of 

Pleuronautilus by most authors and this procedure is 

followed here. Mojsisovics (1902, p. 237-239) established two more subgenera of Pleuronautilus; P. 

(Holconautilus) for the forms with ventral saddles and 

P. (Trachynautilus) for the group of Pleuronautilus 

subgemmatus.

Ribbing as a dominant ornamentational type is 

present in relatively few Paleozoic Tainoceratic'ae: 

Foordiceras, Tainionautilus, Tirolonautilus and Pleuronautilus. Foordiceras, which has a Temnoche;lan
34 AMERICAN TRIASSIC COILED NAUTILOIDS

outline, has lateral ribs that extend half way up the 

flank from the venter as seen in the genotype Nautilus 

goliathus Waagen.

TainionautUus was established by Mojsisovic in 1902, 

type Nautilus transitorius Waagen 1879, to include 

nautiloids with quadratic whorl sections and sinuous 

lateral ribs that extend up the venter to a ventral 

furrow. Mojsisovics considered the genus an offshoot 

of the genus Tainoceras. The writer considers TainionautUus a specialized offshoot of Metacoceras with a 

limited geologic and geographic range. This genus 

was suppressed by Miller and Youngquist (1949) as a 

synonym of Foordiceras, but this view cannot be held. 

The quadratic conch, the type of ornamentation, and 

the ventral furrow are quite distinct from the genotype 

of Foordiceras, so much so that direct comparison is 

difficult.

The genus Huanghoceras was established by Yin 

(1933, p. 19) for ribbed nautiloids with whorl section 

more trapezoidal than that of PleuronautUus. Yin's 

descriptions and illustrations are inadequate, and it is 

difficult to evaluate the true character of his genus. 

The species he assigned to his new genus are so closely 

allied to PleuronautUus that Huanghoceras is here 

placed in synonymy of PleuronautUus. Possibly the 

species of Huanghoceras more properly belong in 

Foordiceras. The species assigned to Huanghoceras by 

Young (1942, p. 123) are so poorly preserved and his 

descriptions so brief that the correct affinities of these 

forms remain in doubt.

The other ribbed representatives of the Paleozoic 

Tainoceratidae have been shifted from one genus to 

another by nearly every paleontologist working with 

these forms. One can almost make the generalization 

that specialists on Paleozoic nautiloids have tended to 

put these forms in Metacoceras or Foordiceras and 

specialists on Triassic nautiloids have tended to place 

them in PleuronautUus. Within the Tainoceratidae, 

the development and elaboration of ribbing as the 

basic ornamentational pattern is most fully attained in 

one generic group, that evolving around PleuronautUus. 

There are about 24 Permian species and 34 Triassic 

species of PleuronautUus, 4 in the Scythian, 20 in the 

Anisian, 6 in the Ladinian, and 4 in the Karnian. The 

widest range in form and in ornamentational variation 

is attained in the Anisian where the most species have 

so far been recognized. Many of the Triassic species 

have simple straight ribs. Similar forms with more or 

less quadratic whorl sections and straight ribs are 

recognized in Permian rocks throughout the world. 

Many of these species appear to be transitional between 

Metacoceras and the Triassic PleuronautUus and should 

be placed in the latter genus. It is interesting to note 

how the generic assignments of many of these species by

various authors vacillates between the above two 

genera. The phylogenetic study 01 the Tainoceratidae 

as an entity seems to support placing the ribbed Permian species in PleuronautUus and deriving that genus 

directly out of Metacoceras. Schmidt (1929, p. 60) 

considered Metacoceras as a subgenus of PleuronautUus. 

The Permian species placed in PleuronautUus have 

a world wide distribution. Only two Triassic sp ^cies of 

PleuronautUus from North America are known, these 

are P. idahoensis Kummel, n. sp. from Scythian rocks of 

southeast Idaho and P. alaskensis Kummel, n. sp. from 

Karnian beds in Alaska. Most of the other Triassic 

species of PleuronautUus are found in the region of the 

Tethyian geosyncline.

PleuronautUus (p.) alaskensis n. sp. 

Plate 4, figures 5, 6

This species is based on a single well-preserved internal mold of an immature individual. The specimen, 

comprising one and one half whorls, is septate throughout and no portion of the living chamber is preserved. 

It measures 51 mm in diameter. The most adoral 

camera is subquadratic, and is 24 mm wide and 19 mm 

high. The umbilical and ventral shoulders are sharply 

rounded, the flanks flattened, and the nearly fat umbilical wall slopes at a high angle to the umbilical seam. 

The impressed zone is about 1 mm deep. At the end 

of the first one-half volution the conch height and width 

are about equal, with a distinctly arched venter. 

The umbilicus measures 20 mm across and is also 

perforate.

The lateral flanks are ornamented with two rows of 

nodes. On the ventral shoulders is a row of small 

rounded nodes spaced approximately 5 mm apart, 

measured from crest to crest. Adapically th^ nodes 

are closer together and appear to form a distinct 

continuous ridge. Along the midline of the flank 

is another set of nodes similar to those on the ventral 

shoulders. A low distinct ridge connects the t^o rows 

of nodes. On the first one-half volution these nodes 

coalesce and form a ridge following the midline of the 

flanks. There may have been a row of nodes along 

the umbilical shoulder, but this is difficult to determine 

from the internal mold. No part of the shell is preser ved, 

but the appearance of the two sets of nodes suggests 

they probably were joined to form a nodose rib.

The suture forms a shallow ventral lobe and a broadly 

rounded lateral lobe. There is a rounded saddle on 

the ventral shoulder, with the apex ventral to the 

nodes on the ventral shoulders. Over the umbilical 

wall the suture slopes adorally in a straight line. 

There is a well-defined angular dorsal lobe witt a small 

annular lobe.

The siphuncle is 3 mm in diameter in the mort adoral
35

m

FIGURE 16.—Cross sections of the conch of A, PleuronautUus (EncoUoceras) superbus Mojsisovics 1873, pi. 4, flg. Ib, diameter 98 mm, the subgenotype of Encoiloceras; B, Phloioceras gemmatum, Mojsisovics 1873, pi. 3, flg. Ib, diameter 140 mm, the genotype of Phloioceras, C, PleuronautUuis 

(Trachynautilus) subgemmatum Mojsisovics 1882, pi. 85, flg. 22, diameter 24 mm, the subgenotype of TrachynautUus: D, PleuronautUus esinensis 

Mojsisovics 1882, pi. 86, flg. 5b, diameter 60 mm; E, P. mom Mojsisovics 1882, pi. 85, flg. 3b, diameter 95 mm; F, P, crassescens Arthaber 

1896, pi. 3, flg. Ib, diameter 34 mm; Q, P. strangulatus (Hauer) 1892, pi. 2, flg. 4b, diameter 45 mm; H. P. cornaliae (Stoppani), after Mojsisovics 1882, pi. 84, flg. 2b, diameter 68 mm; /, P. triserialis (Hauer) 1896, pi. 5, flg. 4, diameter 61 mm; J, P.furcatm Arthaber 1896, pi. 2, flg. 

3b, diameter 75 mm; K, P. verae Arthaber 1898, pi. 13, flg. 4b, diameter 51 mm; L, P. ambigus Arthaber 1896, pi. 3, flg. 3b, diameter 39 mm; 

M, P. trinodosus Mojsisovics 1882, pi. 85, flg. Ib, diameter 90 mm, the genotype of Pleuronautttus.
36 AMERICAN TRIASSIC COILED NAUTILOIDS

Distribution of species of the subgenus Pleuronautilus (Pleuronautilus)

Species Stratigraphic distribution Geographic distribution

Pleuronautilus (Pleuronautilus) ambiguus Arthaber

1896. 

P. (P.) ambiquus var. spirata Reis 1905-__________

P. (P.) alaskensis Kummel n. sp__________________

P. (P.) carbonarius Kruglov 1928_________________

P. (P.) cooperi (Miller) 1945._______________.

P. (P.) cornaliae (Stoppani) 1859_________________

P. (P.) crassescens Arthaber 1896________________

P. (P.) crassescens var. jugulata Arthaber 1896_____-

P. (P.) crassescens var. semijugulata Alma 1926____.

P. (P.) dieneri Krafft and Diener 1909__________

P. (P.) dolomiticus Koken 1913_________________

P. (P.) dorini Caneva 1906_.___________________

P. (P.) dorso-armatus (Abich) 1878________________

P. (P.) esinensis Mojsisovics 1882________________

P. (P.) externelobatus Gemmellaro 1904____________

P. (P.) furcatus Arthaber 1896_____-_-_________.

P. (P.) gregarium (MiJler) 1945___________________

P. (P.) idahoensis Kummel n. sp_________________

P. (P.) incertus (Abich) 1878_____--______.____.

P. ? (P.) kasarmenskensis Kruglov 1928— __________

P. (P.) kokeni Frech 1905____.____________.

P. ? (P.) latissimus (Waagen) 1879______________

P. (P.) linchengense (Yin) 1933-------_-_--_-_-__.

P. (P.) longinodosus Turina 1912________________

P. (P.) magnicostatum (Miller) 1945_______________

P. (P.) mariani Airaghi 1902_____________________

P. (P.) marmolatae Mojsisovics 1882______________

P. (P.) megaporum (Miller) 1945_____"_'_________.

P. (P.) mosis Mojsisovics 1882_____-__-____-____.

P. (P.) mutatum (Miller) 1945_____-_.___________.

P. (P.) narcissae Toula 1896________________.

P. (P.) nodosostriatus Yin 1933___________________

P. (P.) oenanus Mojsisovics 1882_ ________________

P. (P.) ornatissimus Yin 1933____________________

P. (P.) ornatus (Hauer) 1887______________.

P. (P.) paronai Airaghi 1902__-___-__________-__.

P. (P.) pernodosus Yin 1933.___________________

P. (P.) praecursor (Girty) 1908-_._--__._________.

P. (P.) ptychoides Arthaber 1896_.__-____________.

P. (P.) quadrangulus (Hauer) 1892_______________.

P. (P.) schafhautli Reis 1900______________.

P. (P.) seminodosus Arthaber 1896_______________.

P. (P.) shumardianum (Girty) 1908---___________.

P. (P.) simplicostatum (Yin) 1933_________________

P. (P.) strangulatus (Hauer) 1892________________.

P. (P.) subquadrangulus Tien 1933________________

P. (P.) taramelli Tommasi 1894_________________

P. (P.) tommasi (Parona) 1889___________________

P. (P.) trinodosus Mojsisovics 1882-_-____________.

P. (P.) iriserialis (Hauer) 1896___________________

P. (P.) tschihatscheffi Toula 1896___.____________

P. (P.) tubercularis (Abich) 1878___ __..__ _______ _

P. (P.) venustum (Reed) 1944_______________.

P. (P) verae (Abich) 1878_._____________________

P. (P.) wangi (Yin) 1933__ _.__-._____._„____

Triassic (Anisian),

Triassic (Karnian)_____-________---_-

Permian (Ashian and Krasnoufimskian) 

Permian (Leonard series)_____________

Triassic (Ladinian)__________________

Triassic (Anisian)___________________

_do_

Triassic (Scythian)_____-____--_--__

Triassic (Karnian)____________ ______

Permian (Bellerophon limestone) _____

Permian (Djulfa beds)______________

Triassic (Ladinian)_________________

Triassic (upper)____________________

Triassic (Anisian)__________________

Permian (Leonard series)____________

Triassic (Scythian)_________________

Permian (Djulfa beds)______________

Permian (Ashian)_____--_______--__

Triassic (Scythian)_________________

Permian (Upper Productus limestone). 

Permian (Taiyuan series)____________

Triassic (Anisian)____-_-___-__---__

Permian (Leonard series)____________

Triassic (Ladinian)_________________

Permian 

Triassic 

Permian 

Triassic 

Triassic 

Triassic 

Permian 

Triassic 

Triassic 

Permian 

Permian 

Triassic

(Leonard series) 

(Anisian, Ladinian). 

(Leonard series)___ 

(Anisian) _________

(Taiyuan series) _ _ _

(Taiyuan series) 

(Anisian) _______

(Ladinian) _____

(Taiyuan series) 

(Leonard series) _ 

(Anisian)___ _ ____

.do. 

.do.

Permian (Capitan limestone). 

Permian (Taiyuan series) 

Triassic (Anisian)__________

Triassic (Scythian)_________

Triassic (Anisian)__________

Triassic (Karnian)__________

Triassic (Anisian)__________

.do.

Permian (Djuifa beds)______________

Permian (Upper Productus limestone). 

Permian (Djulfa beds)-_________--__

Permian (Taiyuan series)____________

Alps.

Do.

Alaska.

Sterlitamak, Russia. 

Texas. 

Alps.

Do.

Do.

Do.

Himalayas, India. 

Alps. 

Italy. 

Armenia. 

Alps. 

Sicily. 

Alps. 

Texas. 

Idaho. 

Armenia.

Sims River, Russia. 

Salt Range, Pakistan.

Do. 

China. 

Yugoslavia. 

Texas. 

Alps.

Do. 

Texas.

Alps, Yugoslavia. 

Texas. 

Turkey. 

China. 

Alps. 

China. 

Yugoslavia. 

Alps. 

China. 

Texas. 

Alps.

Yugoslavia. 

Alps.

Do. 

Texas. 

China. 

Yugoslavia. 

China. 

Alps.

Do.

Do.

Yugoslavia. 

Turkey. 

Armenia.

Salt Range, Pakistan. 

Armenia. 

China.

part of the phragmocone and is dorsal of the center of 

the whorl.

Remarks.—There is no previous record of Pleuronautilus from the Upper Triassic of North America. 

This present species is from the Chitistone limestone of 

Alaska. From the whole Karnian there are only four 

species of nautiloids previously assigned to Pleuronautilus.

Pleuronautilus alaskensis is similar in ornamentation 

to the genotype species, P. trinodosus Mojsisovics. 

In the latter species three rows of nodes are on the

flanks, and the whorl section of the conch is higher than 

wide. Comparisons with any other species of Pleuronautilus are futile because our specimen lacks the shell 

material, which would show the ornamentation more 

clearly. Nevertheless, it appears that our species is a 

valid member of the gen as, and it is important because 

it represents the first representative of the genus recorded from the Upper Triassic of North Arierica.

Occurrence.—U.S.G.S. loc. 13749, Chitistone limestone (Upper Triassic, Karnian) from the flats at the 

base of cliff along edge of Kennicott glade11*, 5 miles
TAINOCEBATIDAE

north of Kennicott, Chitna Valley, Copper River 

Region, Alaska. 

Holotype.—U.S.N.M. 107082.

Pleuronautilus idahoensis n. sp. 

Plate 4, figures 2, 3, 4; text figure 17

The holotype of this species is a well-preserved 

internal mold 105 mm in diameter. The first 1% 

volutions have the shell preserved. The conch is 

involute, consists of 2}£ whorls, and is a mature specimen. The living chamber is 105 mm in length measured on the venter, and expands rapidly orad. The 

living chamber is apparently incomplete, as there are 

no indications of an apertural margin. The crosssection of the living chamber (text figure 17) is subquadrate with a flattened venter, a well-rounded 

ventral shoulder, weakly concave flanks, and steeply 

rounded umbilical shoulders. The living chamber is 

10.6 percent wider than high, measuring 57 mm in 

width and 51 mm in height. The impressed zone is 

5 mm deep, being 9.83 percent of the height of the 

living chamber. The phragmocone is 79 mm in diameter and has 15 camerae in the last one-half volution. 

The last camera of the phragmocone (the adoral one) 

is 37 mm high and 39 mm wide. At an estimated 

diameter of 58 mm the height is 26 mm and the width

FIGURE 17.—Diagrammatic cross section of the holotype of Pleuronautilus idahoensis, 

n. sp. (U. S. N. M. 107079) from the Columbites beds, Thaynes formation. Hot 

I Springs, Idaho, X 1.

232820—53———4

31 mm. At an estimated diameter of 44 mm the 

height is 21 mm and the width 25 mm.

The adapertural three-quarters volution of the 

phragmocone is smooth and consists of numerous 

relatively thin subquadrate camerae. The venter of 

the phragmocone at its most adoral portion is broadly 

rounded, almost flattened, and the flanks are smooth 

and nearly flat. The ventral shoulder and the umbilical shoulder are will rounded and the umbilical wall is 

broadly rounded and vertical. Adapically the whcrl 

section of the phragmocone becomes more roundel. 

The venter becomes broadly curved, the flanks are 

only slightly curved and the ventral shoulder is obtuseT y 

rounded, the umbilical shoulder being more broadly 

rounded. The second volution has a broadly curved 

flank with a well-rounded and deep umbilical shoulder. 

The first one-half volution is apparently ovoid in sbapi; 

the flanks of this portion of the conch are broadly 

curved, and no distinct umbilical shoulder is presort.

The umbilicus is fairly narrow and deep, measuring 

30 mm in width, which is 28.5 percent of the height of 

the conch; the depth of the umbilicus measures 20 mm. 

The height of the umbilical shoulder is 14 mm at the 

adoral portion of the living chamber, 11 mm at the 

most adapertural portion of the phragmocone, 7 mm at 

the end of the second volution and 4 mm at the end of 

the first volution. A small umbilical perforation is 

present and measures 4 mm in diameter (estimated). 

The perforation could not be completely excavated and 

the extreme adapicai end of the conch is not present, 

but the above measurement is undoubtedly fairfy 

accurate.

The surface of the test is for the most part smooth. 

The second volution, which has the shell preserved, h?,s 

narrow well-defined ribs that extend from the umbilical 

shoulder to the ventral shoulder. The ribs are radial 

and straight and about 4 mm apart, measured from 

crest to crest. Adaperturally the phragmocone is 

smooth, with no indications of ribs or nodes. Tie 

adapicai part of the living chamber has four slight 

nodes oil the ventral shoulder. These nodes, though 

not conspicuous on an internal mold, must have been 

rather high on the shell. A small area of the shell is 

preserved on the living chamber. It is 1.75 mm thick 

and has distinct growth lines. The extreme adapicai 

part of the phragmocone, consisting of the first % 

volution, has conspicuous transverse lirae. The lirr<3 

can be studied only on the flanks of the whorls. This 

feature is similar to that described by Miller (1936, 

p. 96, fig. 10) for an immature specimen of Metacoceras 

sp.

The sutural elements are relatively simple. Tie 

suture at 75 mm consists of a broad shallow ventral 

lobe, an acutely rounded saddle whose apex is on tl e
38 AMERICAN TRIASSIC COILED NAUTILOIDS

ventral shoulder, and a broad concave lateral lobe 

occuping the entire flank. It passes over the umbilical 

shoulder to the umbilical seam forming a short simple 

lateral saddle. At 59 mm the suture has a more primitive aspect. The ventral lobe is smaller and is flanked 

by two broadly rounded ventral saddles whose apices 

are on the venter and not on the ventral shoulder as 

they are adaperturally. The lateral lobe is distinctly 

concave and the deepest part of the lobe is in the dorsal 

half of the flank. The lateral saddle curves up over the 

umbilical shoulder.

The siphuncle is subcentral in position, being 20 mm 

from the venter and 12 mm up from the dor sum, and it 

is 3 mm in diameter.

Remarks.—The rapidly expanding conch, shape of the 

whorl section, and the ornamentation distinguish this 

unique form. It superficially resembles several Hallstatt forms described by Mojsisovics but since the 

test for the most part is lacking and only one mature 

specimen is available, relationships are difficult to point 

out and are inadvisable. Smith (1932) referred a 

specimen to Nautilus (Pleuronautilus) sp. from the 

Columbites zone of the Thaynes formation, Idaho. He 

did not describe or illustrate the specimen, however.

Only one mature specimen of this species is available 

for study; however, two smaller immature specimens in 

the collection are assigned to this species. The first 

(U.S.G.S. loc. 7588) is from the same locality and 

probably the same horizon as the holotype. The 

specimen was collected by T. W. Stanton in 1910 from a 

"dark shaly limestone 300 or 400 ft. above the basal 

limestone of the Thaynes formation on the west slope 

of the second ridge east of Hot Springs, Idaho." The 

adoral part of the specimen is broken however, enough 

of the features are preserved to indicate clearly its 

affinities with the holotype.

The second immature specimen (pi. 4, figs. 3, 4) from 

the Columbites zone, Montpelier Canyon, is 33 mm in 

diameter and also doubtfully referred to this species. 

The specimen has straight lateral ribs and the outline 

of the adoral camera is subquadratic, measuring 24.5 

mm wide and 15 mm high;, the venter is slightly arched. 

It has a well-defined ventral lobe that passes over the 

umbilical wall in a straight line.

Diener recorded Pleuronautilus dieneri from the 

Hedenstroemia beds, southeast of Muth, Spiti in the 

Himalayas, and Frech referred a doubtful specimen to 

this genus, Pleuronautilus^. kokeni, from the Scythian 

of the Salt Range. During the Triassic period Pleuronautilus was present in the Germanic, Alpine Mediterranean, the Himalayan regions, Timor, Alaska, and 

Idaho. In the Anisian, Pleuronautilus became very 

abundant and diversified and developed highly ornate 

conchs. The largest number of species and of specimens known was in the Alpine Triassic. The Germanic 

province has yielded only one species. The eastern 

regions of the Tetheys have yielded a few specie1* in the 

Himalayas and in Timor. Pleuronautilus has not been 

recorded from the Middle Triassic of North America. 

In the Ladinian and Karnian stages Pleuronautilus declined in number of species considerably, foreshs dowing 

the great decline of the nautiloids which took place at 

the end of the Triassic period.

Occurrence—Upper shale member, (Columbites zone) 

Thaynes formation, Hot Springs, Idaho, sec. If, T. 15 

S., R. 45 E.

Types.—Holotype, U.S.N.M. 107079; psratype, 

107080, unfigured plesiotype, U.S.N.M. 107081.

Pleuronautilus sp. (of Idaho)

The only representative of this species is a poorly 

preserved internal mold from the Tirolites limestone 

Thaynes formation, Paris Canyon, Idaho. Tin conch 

is 101 mm in diameter and consists of about 2 volutions, 

1% volution being phragmocone and % volution living 

chamber. The incomplete living chamber is 120 mm 

long, as measured on the venter, expands rapidly orad, 

and shows no indications of an apertural margin. The 

outline of the living chamber is subquadratic, having a 

flattened venter with a median furrow, rounded ventral 

shoulders, broadly convex flanks and a steep wellrounded umbilical shoulder. The cross section of the 

living chamber measures 46.5 mm high and 54 mm 

wide, the ratio of height to width is 14.8 percent. The 

impressed zone is 5 mm deep.

The phragmocone is 77 mm in diameter and consists 

of numerous thin subspherical to subquadrate c^merae. 

The most adapertural camera is 33 mm high and 40 

mm wide, height-width ratio is 17.5 percent At a 

diameter of 40 mm (estimated) the height and width 

are 21 mm and 28 mm respectively, the ratio is 25 

percent. The cross section of the phragmocone at a 

diameter of 40 mm is subspherical, the venter is broadly 

arched, the flanks weakly convex and the umbilical 

shoulder is well rounded and steep. Adorrlly the 

venter of the phragmocone is badly weathered and the 

true shape of the venter is not preserved.

The umbilicus is narrow and deep, measuring 

30 mm in width and 23 mm in depth. The width of the 

umbilicus is 29.7 percent the diameter of the conch. 

The umbilical shoulder measures 16 mm at the adoral 

end of the living chamber and 14 mm at the adoral end 

of the phragmocone. Presumably, an umbilical perforation is present. It could not be completely excavated, however, but from the nature of tH inner 

volutions a measurement of 9.5 mm for the vddth of 

the umbilical perforation is thought to be fairly accurate.
TAINOCERATIDAE 39

The surface of the test is, for the most part, weathered 

and not much detail is present. There are, however, 

strong radial ribs on the first one and % volutions which 

are confined to the flanks of the conch. These ribs 

are broad and high, and are about 12 mm apart, 

measured from crest to crest.

The suture is not preserved on the venter but forms 

a broad shallow lobe on the flanks and a straight course 

on the umbilical wall.

The siphuncle is not preserved.

Remarks.—This specimen may be conspecific with 

Pleuronautilus idahoensis; although there are significant 

differences. Pleuronautilus sp. has fewer whorls, a more 

rapidly expanding conch, and the ribs are of a very 

different nature.

Occurrence.—Middle limestone member of Thaynes 

formation, Paris Canyon, Idaho. (Kummel, 1950). 

Collected by the author.

Specimen.—V.S.NM. 107083.

Pleuronautilus sp. (of Montana)

One complete but weathered specimen from the 

Thaynes formation in Little Water Canyon, southwestern Montana is available for study. The specimen 

measures 127 mm in diameter. The most adoral part 

of the living chamber is 45 mm high and 40 mm wide. 

The cross section of the whorl is subquadratio with well 

defined ventrolateral and umbilical shoudders. The 

venter has a median furrow. The umbilicus measures 

40 mm in diameter.

The most adoral part of the living chamber appears 

to flare outward and is not in contact with the preceding 

whorl dorsally. The specimen cannot be identified 

specifically but can definitely be assigned to the genus 

Pleuronautilus. The specimen is of special interest as 

the first Triassic nautiloid reported from Montana. It 

is not unlike the few other pleuronautilids from southeastern Idaho.

Occurrence.—From beds above the Meekoceras zone, 

Thaynes formation, Little Water Canyon, 6 miles west 

of Dell, southwestern Montana. Collected by the 

the author.

Specimen.—U.S.N.M. 107084

Subgenus ENOPIOCERAS Hyatt, 1900 

Subgenotype: Nautilus wulfeni Mojsisovics

Of the five subgenera of Pleuronautilus, the subgenus 

Enoplffceras is the most adundant and widespread form. 

It is characterized by a whorl section that at maturity 

is subquadratic with flattened venter, flanks, and 

umbilical walls (text fig. 18). The ventral and umbilical 

shoulders are generally sharply rounded. No other

group of pleuronautilids is so striking in form of conch. 

Hyatt did not describe the genus, bat the description of 

the subgenotype by Mojsisovics (1873, p. 10) is given 

here in part:

Die ziemlich rasch anwachsenden Windungen dieser mit 

Nautilus perarmatus, Nautilus .planilateratus und Nautilus 

Fischeri eine Formenreihe bildenden Art sind viel breiter als 

hoch und wahrend d,es ersten halben Umganges gerundet, spaterhin aber platten sich die Seiten stark ab, der Convextheil erscheint 

massig gewolbt und zur Naht senkt sich eine hohe Nabelwand 

von einer scharfen Nabelkante sehrage herab. Zwischen Seiten 

und Convextheil befindet sich eine stumpfe Seitenkante. Die 

Involution erstreckt sich nur auf den Convextheil des vorherocehenden Umganges. Der tiefe Nabel ist in der Mitte von eirem 

kleinen Loche durchbrochen. Mit Beginn der zweiten Hal'te, 

des ersten Umganges stellen sich auf den Seiten Radialfalten ein, 

welche an der Nabelkante mit einem Knoten ansetzen und an der 

Seitenkante mit einem solchem abschliessen. An einem Exemplare bemerkt man ausserdem, aber nur vom Beginn der zweiten 

Halfte des ersten Umganges bis zum Beginn des zweiten Viertels 

des zweiten Umganges ganz feine, auf der Mitte der Radialfalten 

stehende Knotchen; die andern Exemplare zeigen sie nicht. Die 

Radialfalten, welche bei manchen Stiicken schon auf den inne~en 

Umgangen sehr schwach sind und deren man auf eimen ganzen 

Umgange nicht mehr als 14-15 zahlt, verflachen sich auf den 

aiisseren Windungen, insbesondere auf der Wohnkammer fast bis 

zur Unkenntlichkeit; dagegen bleiben die Knoten auf dem Nal •?!- 

und Seitenrand constant und nehmen immerfort an Starke zu.

Die schalenoberflache iiberziehen zahlreiche gedrangte, feine 

Querstreifen, iiber welche sehr schone undulirte Langsstrei^en 

hinwegziehen. Auf der Mitte des Convextheiles bleibt ein 

ziemlich breiter Streifen frei von den Langsstreifen.—Sobald die 

Sehalenoberflaehe durch Verwitterung etwas gelitten hat, tre4,en 

nur mehr die Querstreifen seharf hervor.

Auf der Wohnkammer plattet sich der Convextheil starker ab 

und es bildet sich in der Mitte desselben eine flache Rinne.

Die Kammerseheidewande zeiehnen sich dureh besond^re 

Starke der in mehrfachen Lagen sieh abblatternden Perlmuttersubstanz aus. Auf dem Convextheile befindet sieh ein flacher 

Lobus, dem ein tieferer Laterallobus folgt. Auf dem Concavetheile steht ein kleiner Spindellobus.

Der grosse Sipho steht im ersten Drittel der KammerwandhShe, 

nahe iiber dem Spindellobus. Normallinie auf der Perlmutterschicht deutlich, auf dem Steinkern nur schwach sichbar.

Mojsisovics' description of Nautilus wulfeni can be 

summarized as follows:

The whorls are wider than high and in the first half volution 

are rounded. The whorls then become flattened on the sides 

and the venter moderately arched. The ventral shoulders are 

blunt. The involution is such that only the venter of the preceding whorls are covered. The umbilicus is deep and with a 

small perforation. Radial ribs with nodes on the umbilical 

shoulder commence at the end of the first half volution. Th^re 

are 14 to 15 radial ribs per volution and they diminish in pro-rainence adorally. On the living chamber they are almost unrecognizable; the nodes, however, remain. The shell has delicr-te, 

crowded cross striae with undulating longitudinal lines. The 

longitudinal lines are not present on the central part of the 

venter. On the living chamber the venter is flattened rod 

slightly concave. The suture has a shallow ventral and lateral 

lobe. An annular lobe is present. The siphunele is subcentral 

in position.
FIGURE 18.—Cross sections of the conch ofA,Pleuronautilus (HolconaiitUus) intermedius (Hauer) 1896, pi. 5, flg. 9, diameter 50 mm; B, P. (Holconautilus) distinctus (Mojsisovics) 1882, pi. 85, flg. 4b, diameter 65mm; C, P. (Holconautilus) semicostaius (Beyrich),thesubgenotypeof Holconautilus, after Mojsisovics 1882, pi. 86, flg. Ib, diameter 92 mm; D, P. (H.) ramsaueri (Hauer), after Mojsisovics 1902, pi. 5, flg. 4b, diameter 75 mm; 

E, P. (Enoploceras) ausseanus Diener 1919, flg. 4, diameter 93 mm; F, P. (E.) wulfeni Mojsisovics, 1902, pi. 10, flg. Ib, diameter 127 mm, the 

subgenotype of Enoploceras; G, P. (E.) molengraaffi Kieslinger 1924, pi. 7, flg. 4b, diameter 88 mm; H, P. (E.) lepsiusi Mojsisovics 1902, pi. 10, 

flg. 2b, diameter 44 mm; 1, P. (E.) wulfeniformis Kieslinger 1924, flg. 28, diameter 82 mm; J, P. (E.) gaudryi Mojsisovics 1902, pi. 9, flg. 5b, 

diameter 109 mm; K, P. (E.) pseudowulfeni Kieslinger 1924, flg. 29c, diameter 122 mm; L, P. (E.) n. sp. ex. afl. ivulfeni Kieslinger 1924, flg. 30, 

diameter 112 mm.
TAESTOCERATIDAE 41

Sixteen species of Enoploceras have been described 

to date. There are also numerous specimens that have 

been described as being related to or similar to previously designated species. Most of the species of 

Enoploceras occur in rocks of Karnian age, only three 

are known from the Norian. The only North American

species is Pleuronautilus (Enoploceras) newelli n. sp., 

from the Thaynes formation (Scythian) of southeastern 

Idaho. With the exception of the single North American species all the species of Enoploceras occur in localities within the Tethyian geosyncline, namely the AHine 

region, the Himalayas, and the Island of Timor.

Distribution of species of the subgenus Pleuronautilus (Enoploceras)

Species Stratigraphic distribution Geographic distribution

Pleuronautilus (Enoploceras) ausseeanus Diener 1919- 

P. (E.) fischeri (Mojsisovics) 1873_______________

P. (E.) gaudryi Mojsisovics 1902____-_------------

P. (E.) kossmati Diener 1901__-_---------_-------

P. (E.) lepsiusi Mojsisovics 1902__________________

P. (E.) lepsiusiformis Diener 1919_______________

P. (E.) malayicus Welter 1914___------_--________

P. (E.) molengraaffi Kieslinger 1924_______________

P. (E.) newelli Kummel n. sp__-------_----_------

P. (E.) planilateratus (Hauer) 1860______________

P. (E.) pseudoplanilateratus Kieslinger 1924________

P. (E.) pseudowulfeni Kieslinger 1924____________

P. (E.) semseyi Frech 1903--------------__-----

P. (E.) tibeticus Mojsisovics 1896.________________

P. (E.) wulfeni (Mojsisovics) 1873________________

P. (E.) wulfeniformis Kieslinger 1924___----_-_-__-

Triassic (Karnian, Norian). 

Triassic (Karnian)______

.____do_-----------------

Triassic (Norian) _________

Triassic (Karnian, Norian). 

Triassic (upper)__--______

Triassic (Scythian). 

Triassic (Karnian)-

Triassic (upper)--. 

Triassic (Karnian).

Alps.

Do.

Do.

Do.

Alps, Timor. 

Alps. 

Timor.

Do. 

Idaho. 

Alps. 

Timor.

Do. 

Alps.

India, Timor. 

Alps. 

Timor.

Pleuronautilus (Enoploceras) newelli n. sp. 

Plate 4, figure 1; text figure 19

Only one specimen, well-preserved and fairly complete, is available for study. About a third of the conch 

is missing and the test is not present over the venter. 

The conch is evolute, robust, has a deep perforate 

umbilicus, and is rapidly expanded orad; it measures 

84 mm in diameter. The cross section of the living 

chamber is quadratic, is much broader than high, and 

measures 61 mm wide and 40 mm high (text fig. 19). 

The venter is flattened and contains a shallow central 

furrow. The ventral shoulder is abruptly rounded and 

has large prominent nodes. The flanks are very gently 

arched, converge slightly ventrally, and have an acutely 

rounded umbilical shoulder. The umbilical wall is 

vertical and sinuous. The umbilicus is very deep and 

the umbilical perforation is about 8 mm in diameter. 

The incomplete living chamber measures 55 mm along 

the venter. The phragmocone is much more rounded 

in cross section and is also much broader than high. 

The cross section of the phragmocone at a diameter of 

about 55 mm measures 46 mm wide and 27 mm high. 

The venter is distinctly arched passing on to the flattened flanks at a definite line of contact. The umbilical 

shoulder is sharply rounded and the umbilical wall is 

steep but slightly oblique. The extreme lower portion 

of the umbilical shoulder curves inward toward the 

seam. The depth of the impressed zone at this diameter of the conch is about 10 mm.

The surface of the test is well preserved and ornate. 

There are two sets of nodes present, one on the umbilical

shoulder and one on the ventral shoulder. Insofar as 

can be determined from the specimen the nodes begin 

near the adoral end of the first volution. The nodes 

here are rather slender, high, and very distinct. The 

umbilical wall of the next whorl extends down to the 

ventrolateral set of nodes. There are no ridges or ribs 

connecting the nodes. On the ventral shoulder of the 

living chamber the nodes are much larger, blunter, and

FIGURE 19.—Diagrammatic cross section of the holotype of P. (Enoploceras) newett 

n. sp. (U. S. N. M. 107085), from the Cclumbttes beds, Thaynes formation, Montpelier Canyon, Idaho X 1.
42 AMERICAN TRIASSIC COILED NAUTILOIDS

essentially more subdued than they are on the phragmocone. On the umbilical shoulder of the living chamber 

the nodes are large, narrow, and very much subdued. 

The nodes are also very conspicuous on the internal 

mold. The test on the adapetural first two-thirds 

volution consists of delicate transverse and longitudinal 

striae, or ridges, which give the conch at this place a 

granular appearance.

The growth lines on the phragmocone are moderately 

distinct. They curve adapically over the umbilical 

wall, straighten out over the flanks and form a deep 

broad sinus on the venter. On the living chamber the 

growth lines are much more distinct. Over the umbilical wall they are arcuate in shape, being concave 

orally. On the flanks the growth lines form a broad 

orally concave arc, the curvature of the arc decreasing 

towards the venter; at a distance of 30 to 40 mm from 

the aperture this arc, formed by the growth lines, is 

about 8 mm deep, adjacent to the aperture the arc is 

very shallow. As the test is not preserved on the 

venter, the shape of the growth lines there is unknown. 

The test has numerous delicate undulating longitudinal ridges or striations. This type of shell ornamentation gives the test a more or less corrugated 

appearance and is characteristic of many representatives of this group of nautiloids. The aperture is 

preserved in only a small area around the umbilical 

shoulder. The apertural margins are short and abruptly curved, folding slightly under the margins of 

the conch. The thickness of the test varies considerably at different portions of the conch. Adjacent 

to the umbilical shoulder on the living chamber the

test is 0.8 mm thick, adjacent to the ventral si oulder 

2 mm thick, and on the venter of the phragraocone 

less than 1 mm thick.

The septa and the siphuncle are not preserved.

Remarks.—Pleuronautilus (Enoploceras) wulfeni is 

the only Scythian representative of this submenus; 

all other species of P. (Enoploceras) are confined to 

the Karnian and the Norian. The Idaho species is 

much more depressed than P. (E.} wulfeni and has no 

radial folds that connect the nodes.

Occurence.—The only known representative of this 

species came from the upper shale member, Columbites 

zone, Thaynes formation, Montpelier Canyon, Idaho, 

sec. 31, T. 12 S., R. 45 E. Collected by the author.

Holotype.—U.S.N.M. 107085

Subgenus HOLCONAUTILUS Mojsisovics, 1902 

Subgenotype: Nautilus semicostatus Beyrich

This subgenus was proposed by Mojsisovics (1902, 

p. 238) to include those pleuronautilids which have a 

ventral saddle instead of the more typical ventral lobe. 

In practically every other respect the forms included 

in Holconautilus are similar to Pleuronautilus (eee text 

figs. 16, 18, pi. 17, figs. 3, 4).

Only nine species of this subgenus have been described, six are from the Anisian, one from the La dinian, 

and two from the Karnian. Many described specimens have been placed in this subgenus with cf. or off. 

to one of described species. All of the species of 

Holconautilus come from the Germanic region, the 

Mediterranean region, or from the Island of Timor.

Distribution of species of the subgenus Pleuronautilus (Holconautilus)

Species

Pleuronautilus (Holconautilus) distinctus (Mojsisovics) 1882. 

P. (H.) intermedius (Hauer) 1896 _____________ _ _

P. (H.) pichleri (Hauer) 1865— ------------------

P. (H.) ramsaueri (Hauer) 1855-- _ _- - ___

P. (H.) scabiosus (Arthaber) 1896_ ___________ ___

P. (H.) semicostatus (Beyrich) 1865____ __ _--_____

P. (H.) singularis (Welter) 1914_.__-__- __________

P. (H.) stautei (Fritsch) 1902___-___ ____ _____ _

P. (H.) striatus (Hauer) 1892._ ... __ __ _ _ _ _

Stratlgraphic distribution

Triassic (Anisian)

do

do - -

do

Triassic (upper)

Triassic (Muschelkalk)____ _________ __ ___

Geographic distribution

Alps.

Alps, Yugoslvaia.

Alps.

Do.

Do.

Do.

Timor.

Germany.

Alps.

Subgenus ENCOILOCERAS Hyatt, 1900 

Subgenotype: Encoiloceras superbus Mojsisovics

Hyatt (1900, p. 525) originally proposed Encoiloceras 

as a distinct genus in his family Pleuronautilidae. However, most subsequent authors have treated Encoiloceras 

as a subgenus of Pleuronautilus. It is a monotypic 

genus and since Hyatt did not give any diagnosis of 

his new genus the description of the holotype by

Mojsisovics (1873, p. 18) is quoted here in part (see 

pi. 17, figs. 9, 10):

Diese schone Art aus der Verwandtschaft des Nautilus Ramsaueri Hauer zeichnet sich vor alien mir bekannten Nautilen 

durch die Grosse des von der inneren Windung oflfen Gelassenen 

Kaumes aus, welche nicht weniger als 25-26 mm in Dunhmesser 

misst.

Der Anfang der ersten Windung ist vollig frei, bald a her wird 

dieselbe vom nachstfolgenden. Umgange beriihrt und kurz 

darauf stellt sich das normale Involutionsverhaltniss her, indem
TAINOCE.RATIDAE 43

% der vorhergehenden Windung vom folgenden Umgange bedeckt 

wird.

Wahrend des ersten Umganges wachsen die Windungen 

langsam an und sind breiter als hoch. Der Uebergang der 

Seiten zur Nabelwand und zum. Convextheil ist gerundet, ohne 

irgend welche Andeutung einer Kantenbildung. Auf der Mitte 

des Concavtheiles ist die Schale seicht rinnenforming vertieft. 

Die Schalenoberflaehe ist niit feinen Querstreifen bedeckt, 

ahnlich wie bie Nautilus brevis und Nautilus evolutus. Kreuzende 

Langsstreifen wurden nur auf dem Concavtheil, hier aber in 

ausgezeichneter Scharfe bemerkt.

Auch auf dem zweiten Umgange sind die Windungen breiter 

als hoch; die Form des Querschnittes und die Sculptur andern 

sich aber ausserordentlich. Es bildet sich am Anfange des 

zweiten Umganges, zugleich mit dem Erscheinen radialer Falten 

auf den Seiten, eine stumpfe Nabelkante, welche spaterhin, wo 

aus den Falten formliche Rippen werden, weniger markirt 

hervortritt. Der Convextheil bleibt noch geraume Zeit schon 

gewolbt; auf der Wohnkammer jedoch plattet er sich bedeutend 

ab und der Querschnitt erscheint in Folge dessen eher viereckig 

als gerundet.

Die Zahl der Falten betragt 27. Dieselben sind leicht geschwungen mit nach aussen gekehrter Concavitat. Gegen den 

Rand zum Convextheil verdicken sie sich allmalig und enden 

mit undeutlichen Knoten.

Gegen die Mundung der beilaufig J4 Umgang einnehmenden 

Wohnkammer zu stellt sich auf der Mitte des Convextheiles 

eine leichte, ziemlich breite rinnenartige Vertiefung ein und am 

Rande des Convextheiles gegen die Seiten erfolgt eine Contraction der Windung, gegen die Naht zu hingegen eine Erweiterung 

derselben, indem die letzten Rippen geradezu das verkehrte 

Verhaltniss gegen alle vorhergehenden zeigen, namlich innerhalb 

des Seitenrandes erst ansetzen, gegen den Nabel zu sich allmalig 

verbreitern und auf der Nabelwand mit einer knotenformigen 

Verdickung endigen.

Die dicht auf einander folgenden Kammerwande beschreiben 

auf dem ersten Umgang auf dem Convextheil einen flach gewolbten Sattel, auf dem zweiten Umgang dagegen einen flachgewolbten Lobus; auf den Seiten folgt ein weiterer Laterallobus; 

auf dem Concavtheile schliessen zwei flache Sattel einen namentlich auf der ersten Windung verhaltnissmassig grossen 

Spindellobus ein.

Der Sipho steht tief, ganz nahe uber dem Spindellobus.

Ueber die Mitte des Convextheiles verlauft eine auf uber die 

ganze Wohnkammer sich erstreckende Normallinie.

Mojsisovics' description can be summarized as 

follows:

This beautiful species, related to Nautilus ramsaueri has the 

largest umbilical performation of any Triassic nautiloid known 

to me. The initial part of the first volution is completely free 

but soon becomes partially inclosed by the succeeding whorls. 

The normal involution is about one-third the whorl height. In 

the first volution the whorls are wider than high and the whorl 

sides rounded. The dorsal area has longitudinal striae. The 

shell surface bears fine cross striae. The whorls on the second 

volution are also wider than high and radial folds begin to 

develop. The whorl shape on the living chamber is subquadratic. There are about 27 slightly sinuous ribs per volution that 

thicken towards the ventral shoulder where they form a slight 

node. On the last third volution prior to the aperture the 

venter has a median furrow. The whorl sides are more convergent and the ribs thicken towards the umbilical shoulder. 

The suture has a shallow ventral, lateral, and dorsal lobe with

an annuler lobe. On the first volution there is a ventral saddle 

instead of a ventral lobe. The siphuncle is close to the dorsnm.

The holotype is from the Karnian of the Alps (pi. 17, 

figs. 9, 10). Kutassy (1928) records P. (Encoiloceras) 

sp. ex. aff. superbus from Karnian rocks of Hungary.

Subgenus ANOPLOCEKAS Hyatt, 1900 

Subgenotype: Anoploceras ampezzanus (Loretz)

This is another of the new genera placed in his family 

Pleuronautilidae by Hyatt in the 1900 edition of the 

Ziteel-Eastrnan Textbook of Paleontology. The two 

species that have been placed in Anoploceras are very 

closely related to Pleuronautilus and it seems best to 

treat this group as a subgenus. Anoploceras is characterized by an evolute conch with a subquadratic and 

depressed whorl section. The flanks have thick, foldlike, slightly sinuous ribs and the venter is smooth 

pi. 17, figs. 62.

Hyatt did not describe his new genus so the description of the subgenotype by Loretz (1875, p. 809) 

is quoted here in part:

Die Seitenflache der Windung verlaugt flach und ist mit d'".ht 

aufeinander folgenden gleichbreiten Furchen und Ripnen 

versehen, deren auf die halbe Windung je circa 18 bis 19 kommen; sie reichen von der Nabekante bis an den Beginn der 

Wolburg, welche die Seitenflache mit der Aussenflache verbnHet. 

Die Rippen sind in ihrer grossten Lange radial gerichtet, in 

der Nahe der Nabelkante jedoch sind sie etwas abgelenkt und 

nehmen eine Richtung vorwarts an.

Mit der Naht ist die Seitenflache durch eine ziemlich steil 

abfallende, anscheinend glatte Nahtflache verbunden; zwischen 

beiden Flachen ist eine markirte Nabelkante. Die Aus^enflache der Windung ist sehr breit, gegen die mitte zu nur sehr 

liecht eingesenkt, ohne Rippen und Furchen, und mit den 

Seitenflachen, zu denen sie rechtwinklig steht, durch eine 

continuirliche Wolbung verbunden, so dass sich keine Aus^enkante bildet.—Die Schale ist in der Mitte der Aussenflache der 

Windung nur dunn, wird nach den Seitenflachen zu starker und 

ist auf letzteren von betrachtlicher Dicke.

Die Lobenlinie bildet auf der Mitte der Seitenflache, sowie auf 

der Mitte der Aussenflache eine sanft nach rtickwarts ge^ohwungene Bucht. Etwa die Halfte des vorliegenden Sttnkes 

ist Wohnkammer; nur die beiden letzten Lobenlinien konnten 

beobachtet werden, sie stehen auf der Mitte der Aussenflache 

circa 11 mm. von einander ab.—Der Sipho liegt der cones ven 

Seite der Windungsrohre nahe.

This description is summarized as follows:

The whorl sides are flattened and have thick radial ribs and 

furrows; there are approximately 18 to 19 ribs on a half volution. 

In the region of the umbilical shoulder the ribs project adorMly. 

The unbilical shoulder is sharply rounded and the umbi"'cal 

wall steep and smooth. The venter is very broad and slightly 

concave. The ventral shoulders are rounded. The suture 

forms a shallow ventral and lateral lobe. The siphuncl? is 

below the center of the whorl.

The type species comes from Karnian rocks of the 

Alpine region. The only other species assigned to this
44 AMERICAN TRIASSIC COILED NAUTILOIDS

subgenus, P. (A.} rollieri (Arthaber) 1896, is from 

Anisian rocks of the Alps.

Subgenus TRACHYNAUTILUS Mojsisovies, 1902 

Subgenotype: Pleuronautilus subgemmatus Mojsisovics

When Mojsisovics (1902, p. 239) proposed his subgenus Trachynautilus he made the following comments:

Als eine weitere Untergattung von Pleuronautilus mochte ich 

Trachynautilus oder die Gruppe des Pleuronautilus subgemmatus 

auffassen, welche den Uebergang zur Gattung Phloioceras vermittelt. Die Abstammung dieser durch laterale Langsrippen 

ausgezeichneten kleinen Gruppe von Pleuronautilus lehrt 

deutlich der von G. v. Arthaber aus dem Reiflinger Kalke 

beschriebene Pleuronautilus scabiosus und insbesondere der von v. 

Arthaber als Varietat dieser Art bezeichnete PL jugulatus, 

welcher in den mittleren Lebensstadien deutlich die Verbindung 

der .typischen Pleuronautilus-Sculptur mit der Trachynautilus—

Sculptur zeigt, auf der Wohnkammer aber ausschlierslich die 

longitudinale Trachynautilus-Sculpbur besitzt. Bei dem julischen Trachynautilus Telleri ist das Uebergreifen der lateralen 

Langsrippen auf die Externseite zu beobachten, wodurch sich 

die allmahliche Annaherung an den Typus von Phloioceras 

deutlich zu erkennen gibt.

The type specimen is refigured on plate 17. 

Mojsisovics' comments can be summarized as follows:

As another subgenus of Pleuronautilus I propose Trachynautilus 

for the group of Pleuronautilus subgemmatus, which is trr.nsitional 

to Phloioceras. The derivation of this group with longitudinal 

ribs on the flanks from Pleuronautilus is especially demonstrated 

in Pleuronautilus scabiosus and P. jugulatus described by Arthaber 

from the Reiflinger Kalk which in there ontogeny show the 

combination of Pleuronautilus and Trachynautilus ornamentation. Trachynautilus telleri has the longitudinal ribs spreading 

onto the venter and in this respect is transitional to Phloioceras.

Distribution of species of the subgenus Pleuronautilus (Trachynautilus)

Species

Pleuronautilus (Trachynautilus) clathratus Hauer

1896. 

P. (T.) Jam's Schnetzer 1934--- __ _______________

P. (T.) mimiens Kittl 1908 _ ____ _ ___ __ ____

P. (T.) nodulosus Arthaber 1896_-_- _ ___ __ ____

P. (T.) subgemmatus Mojsiovics 1882.. _ _ ____

P. (T.) telleri Mojsisovics 1902 __ _______ ______

P. (T.) trilineatus Frech 1903_ _ _____ _-.___.___

Stratigraphic distribution

do. ______

Triassic (Ladinian) _____________ _ __ _____

Geographic distribution

Yugoslavia.

Roumania.

Alps.

Do.

Do.

Do.

Genus PHLOIOCERAS Hyatt, 1883 

Genotype: Nautilus gemmatus Mojsisovics

When Hyatt (1883, p. 286) first established this

genus he diagnosed it as follows:

The shells are ridged longitudinally, and the ridges in the type 

roughened by transverse striae. Mojsisovics considers them as 

allies of Nautilus cariniferus, and he may be right, but we have 

placed them in this series on account of the resemblance of [N.] 

gemmatus to Kophinoceras. The sutures have simple, lateral, 

ventral and dorsal lobes, with small annular lobes. Siphon is 

central or below the centre.

(see pi. 17, figs. 5, 6).

In the very next generic description of that paper, 

Hyatt discussed the genus Pleuronautilus and remarked

The young of one species, Pleuronautilus (now Trachynautilus} 

subgemmatum, as figured by Mojsisovics (1883, p. 85) is similar 

to the adult Phloioceras gemmatum, and appears to settle the 

question of affinity.

At this time he included both of these genera in his 

family Rutoceratidae. However, in the 1900 edition 

of the Zittel-Eastman Text-book of Paleontology he 

placed Phloioceras in the family Rhineceratidae. 

Mojsisovics (1902, p. 239) expressed the opinion that 

Phloioceras is somewhat similar to Trachynatilus and 

is actually an offshoot of Pleuronautilus and thus belongs in the family Temnocheilidae (Tainoceratidae of 

the present paper). Mojsisovics also pointed out that

as yet no intermediate forms are known tl <vt link 

Phloioceras and Trachynautilus. The latter genus has 

the peculiar longitudinal ridges confined to the flanks 

and do not occupy the venter, and also all the species of 

Trachynautilus are rather small. Phloioceras has the 

longitudinal ridges developed both on the flanks and the 

venter, and the robust shell attains a much larger size 

than in any known representative of Trachynautilus. 

The writer is inclined to agree with Mojsisovics and in 

depicting the phylogenetic development of the Tainoceratidae Phloioceras is placed close to Trachynautilus 

but regarded as having been derived directly from 

Pleuronautilus.

Phloioceras sp.

Plate 4, figure 7; text figure 20

Only one fragmentary specimen in the present collection can be assigned to the genus Phloioceras. The 

writer refrains from naming the form because tl °- specimen is not sufficiently complete. The specimen consists 

of about 25 mm of the living chamber with the shell preserved and the ventral region of an inner whorl. The 

preserved part of the living chamber measures 22 mm in 

height and 33 mm in width. The venter is broadly 

arched, the flanks slightly divergent, and the umbilical 

shoulder is subangular (see text fig. 20). The umbilical 

wall slopes at an angle of approximately 35 degrees.
GRYPOCERATIDAE

Distribution of species of the genus Phloioceras

45

Species

Phloioceras deliciomm Diener 1908- -_-_ __ _ __

P. gemmatum (Mojsisovics) 1882___ _ _ __ ___

P. welteri Kieslinger 1924. __ _ _ _______

P. BP—— — — — — — — —— __-_ — __________________

Stratigraphic distribution Geographic distribution

Timor.

FIGURE 20.—Diagrammatic cross section of Phloioceras sp. (U. S. N. M. 107094) 

from the Upper Triassic on Admiralty Islands.. Alaska, X 1.

The surface of the conch is highly ornamented. Along 

the venter are four longitudinal and parallel rows of low 

elongate nodes. The nodes along the median portion of 

the venter are spaced slightly farther apart than those of 

the adjacent row of nodes on either side. There is a row 

of rather high rounded nodes on the ventral shoulder 

and one on the umbilical shoulder. Along the middle of 

the flank between the shoulders is another row of nodes, 

which are likewise large and rounded. There are thus 

ten distinct longitudinal rows of nodes on the flanks and 

venter. The ventral region of an inner whorl shows four 

distinct longitudinal ridges. The ridges are in pairs on 

each side of the venter, and the space between the two 

central ridges is nearly twice that between the outer two 

ridges. This is very similar to the type of ornamentation seen in Trachynautilus.

Remarks.—Phloioceras sp. of Alaska is very similar to 

Phloioceras welteri Kieslinger from the Norian of Timor. 

P. welteri has six rows of nodes on the ventral region, a 

row of nodes on the ventral and umbilical shoulders, but 

no median row of nodes on the flanks as seen in P. sp. 

Both species differ from the genotype, which has a much 

more highly developed ornamentation, with longitudinal ridges that seem to be formed by the coalescing of 

elongated nodes, and much more numerous rows of 

nodes. The basic form of the conch, however, is similar 

in all three forms.

Occurrence.—Point at north entrance to Herring Bay, 

Admiralty Islands, Alaska. Bed 9 in section (Martin 

1926, p. 90) from a "fossiliferous limestone."

Type—U.S.N.M. 107094.

Family GRYPOCERATIDAE Hyatt, 1900

The genera now included in Grypoceratidae are 

Grypoceras, Gryponautilus, Domatoceras, Stenopoceras, 

Menuthionautilus, Plummeroceras, Stearoceras, Titanoceras, and Pselioceras. Mojsisovics (1902) established 

the family Gryponautilidae for Grypoceras and Gryponautilus. He separated these genera from the Clydonautilidae mainly on the presence of an annular lob<\ 

Diener (1919) objected to the taxonomic scheme of 

Mojsisovics (1902), especially to the importance that 

Mojsisovics attached to the annular lobe. Diener (1919) 

combined the Gryponautilidae and Clydonautilidae of 

Mojsisovics (1902) into the family Grypoceratidae 

Hyatt (1900). In this latter family Hyatt (1900) originally had only included Grypoceras and Syringoceras.

It now seems quite clear that the relationship of Grypoceras to Domatoceras links that genus closely to its 

Paleozoic ancestors and that they should be included hi 

the same family. As will be discussed below Domatoceras Hyatt 1891, is placed as a subgenus of Grypoceras 

Hyatt 1883, which has priority. Miller and Your'?- 

quist (1949, p. 41) erected the family Domatoceratidae 

for five very similar late Paleozoic nautiloid genera tl at 

probably directly or indirectly evolved from Koninckioceras "or some very similar form." These genera f,re 

Domatoceras, Stearoceras, Stenopoceras, Titanoceras, and 

Pselioceras. These genera are now all included in the 

Grypoceratidae. A new subgenus, Plummeroceras, is 

proposed for late Paleozoic grypoceratids with de°/p 

ventral lobes. Menuthionautilus is a monotypic development known only in the Scythian beds of Madagascar and Pakistan. In its ontogeny and morphological features it appears to be an aberrant offshoot of 

Domatoceras.

As an evolutionary unit this family appears to be 

closely integrated. The extensive variations experimented with in this family keep an over-all unity in 

both the shape of the conch and sutural development. 

The Paleozoic genera are mostly widely umbilicr.te 

forms except for Stenopoceras and those species of 

Domatoceras transitional to Stenopoceras. The pr^icipal Triassic representative, Grypoceras, is slightly 

more involute than Domatoceras but Menuthionautilus 

and Gryponautilus are highly involute forms similar to 

Stenopoceras. The group as a whole has compressed 

conchs that tend to be flattened laterally and may or 

may not be flattened ventrally. The sutures form 

ventral, lateral, and dorsal lobes. An annular lobe is 

present in Stearoceras, Grypoceras, and Gryponautilus 

but not present or not recognized as yet in the remaining genera. Nodes on the ventral shoulders are developed at full maturity in some of the Paleozoic rep^e-
PENNSYLVANIAN

PERMIAN

PERMIAN TRIAS

Morrow Atoka Das Moines Missouri Virgil Wolfcomp Leonard Guadalupe Ochoa Scythian Anisian Ladinian 
GRYPOCERATIDAE 47

sentatives of this group. Similar types of nodes are 

found in youthful Gryponautilus but they are not considered to indicate any affinity with the Tainoceratidae. 

The sum total of all the characteristics of these forms 

refutes any genetic relationship to that family. The 

siphuncle is orthochoanitic in structure and is extremely variable in position; it ranges from subcentral 

in most genera to an extreme ventral position in 

Menuthionautilus.

Geographically this family is very wide spread. The 

Paleozoic forms are rather wide-spread in North 

America, Europe, Asia, and Australasia. The Triassic 

forms have a closely limited distribution in North 

America but are quite common in the region of the 

Triassic Tethyian geosyncline.

PHYIOGENY

The evolution of the Gypoceratidae is similar to 

that of the Tainoceratidae in the existance of a dominant, slowly evolving stock from which several varied 

forms developed (text figs. 21,22). Domatoceras is a very 

abundant nautiloid in late Paleozoic rocks and practically world wide in distribution. It does show a 

great range of variation in the Pennsylvanian and 

Permian, but these variations appear to be random 

and of no stratigraphic significance. Grypoceras is 

considered to be a direct offshoot of Domatoceras and 

replaces it in the Triassic. The main changes are

toward a rounding of the venter, and greater involution. Scythian species of Grypoceras, as G. brahmanicum, G. hexagonalis, and G. milleri n. sp. (p. 53) have 

rectangular whorl sections with rounded ventral and 

umbilical shoulders and somewhat flattened flanks. 

These species are actually difficult to distinguish from 

several species of Pennsylvanian and Permian Domatoceras. Middle and Late Triassic species of Grypoceras 

show more rounding of the venter and greater 

involution.

The suture in Domatoceras has in general rather 

moderate ventral and lateral lobes, those in Grypoceras 

are somewhat deeper and there is an annular lob 3. 

This relationship is very similar to that between 

Metacoceras and Mojsvaroceras. Plummeroceras (p. 54) 

is an aberrant offshoot of Domatoceras that maintained 

a typical evolute domatoceratid conch but acquired 

a very deep ventral lobe similar to that of some Triassic 

species of Grypoceras.

Both Domatoceras and Grypoceras gave rise to more 

specialized offshoots that have more limited geolog; °< 

and geographic distributions. A trend towards greater 

involution is found in Stenopoceras, Pennsylvanian to 

Permian in age; Menuthionautilus, Scythian in age; acd 

in Gryponautilus, Late Triassic in age. Stenopoceras has 

a highly involute and compressed conch. The venter 

is generally narrow and may be rounded, subacute, or 

even concave. Stenopoceras is connected with DomaSteoroceros

Gryponautilus

Grypoceras

Domotoceras

Plummeroceras

Menuthianautllus

Stenopoceras

Titanoceras

Pselioceras

PENNSYLVANIAN '

Morrow Atoka

——— ^

Des Moines

••

Missouri

mm*

Virgil

mm*m

3ERMIAr 

1— (?)

Wolfcomp

————— •

HMMM

^ PERMIAN

Leonard

«»

«•

•••••

Guadalupe

———

Ochoa

•••••

TRIASSIC

Scythian

mmm

Anisian

«

Ladinian

i

•••

Karnian

1MB

Morion

•mi 

mimm

Rhaetion

FIOUBE 22.—Range chart showing known stratigraphic occurrence of the Grypoceratidae. The width of the line is proportional to the number of species in each epo-;h.
48 AMERICAN TRIASSIC COILED NAUTILOIDS

toceras through such involute species as D. kleihegei and 

D. moorei. Stenopoceras did not give rise to any other 

groups of nautiloids and represents merely an involute 

offshoot of the more slowly evolving domatoceratid 

stock.

Menuthionautilus is another involute offshoot of 

Domatoceras. It has a rapidly expanding, smooth, and 

involute conch. On the early whorls the venter is flattened and becomes broadly convex on the mature portion of the conch. The conch form, suture, and 

ontogeny appear to indicate a close relationship with a 

domatoceratid ancestry. Along with the greater involution of the conch there was a shifting of the siphuncle to an extreme ventral position. The parent 

stock, Domatoceras, shows a great deal of variation in 

the position of the siphuncle. Some of the more involute species, as D. kleihegei, have the siphuncle only 

12.5 percent of the whorl height from the venter. 

Shifting of the siphuncle to an extreme ventral position 

is a relatively rare ocurrence in late Paleozoic and 

Triassic nautiloids. This phenomenon is present only in 

SolenochUus of the late Paleozoic and in Menuthionautilus of the Early Triassic.

Gryponautilus is incompletely known. The genotype, 

Q. galeatus, has an inflated involute conch with a very 

narrow keel-like venter. The inner whorls have a 

broad flatly convex venter, and there are nodes along 

the ventral shoulders. The suture and general form and 

ontogenetic development of the conch clearly point to 

its ancestry in Grypoceras in the Late Triassic. Ornamentation is not characteristic in the Grypoceratidae— 

most species have smooth conchs. There are some 

species of Domatoceras, as D. williamsi, that have nodes 

on the ventral shoulder. The presence of nod es in members of the Grypoceratidae do not appear to have any 

phylogenetic significance—they merely show some convergence towards the Tainoceratidae.

The relationships of Pselioceras, Stearoceras, and 

Titanoceras are uncertain. Pselioceras is a widely umbilicate form known only from the Salt Range of 

Pakistan. Titanoceras occurs in the Pennsylvanian but 

not in the Permian. It gave rise to no other genera, 

and its ancestry and relationships with other genera of 

the Grypoceratidae are not well understood. Stearoceras appears to be an independent development out of 

Koninckioceras paralleling Domatoceras (Miller and 

Youngquist, 1949, p. 42). According to the broad interpretation of this genus as proposed by Miller and 

Youngquist Stearoceras now includes a wide assortment 

of forms. There are forms intermediate between 

Stearoceras and Domatoceras. The Syringonautilidae 

are thought to arise from these.

Genus GRYPOCERAS Hyatt, 1883 

Genotype: Nautilus mesodicum Hauer

Hyatt first diagnosed this genus as follows:

Grypoceras, nobis, includes species of the Trias which are described by Mojsisovics, "Das Gebirge um Hallst.," with compressed and more involute whorls than the above (Moj^varoceras), 

abdomen, however, truncated at some stage of growth, though 

acute in some species in the later adolescent and adult stages. 

Siphon below the centre, sutures like the above (Moj«varoceras), 

but with deeper lateral lobes and narrow V»-shaped ventral lobes. 

The forms have annular lobes according to Mojsisovics.

The forms with acute venters included by Hyatt in 

this genus were later placed by Mojsisovics in a subgenus, Gryponautilus, which is raised to full generic rank 

in the present report.

Mojsisovics (1902, p. 228), in discussing this genus 

made several pertinent comments as to its probable 

affinities, pointing out the close relationship of Grypoceras with Domatoceras. As his comments are important 

and generally inaccessible they are quoted in part here 

(free translation)

The closest similarity is with Domatoceras Hyatt, a characteristic nautiloid of the Pennsylvanian and Permian that Hyatt 

had placed in the family Koninckioceratidae. This conclusion 

does not rest solely on the suture but also in the form o* the conch 

in the older species of Grypoceras, from which they diPer in being 

less involute and lacking an annular lobe. Prof. Diener showed 

me a specimen of Domatoceras hunicum from the Perriian limestone of Chitichun, Himalayas, India in which one would have 

doubt as to whether both these species should not b^ placed in 

the same genus

Most compressed Triassic nautiloids with flattened 

ventral and lateral areas have been placed in the genus 

Grypoceras. This Triassic genus shows remarkable similarity with typical representatives of Domatoceras (text 

figs. 23, 24). Grypoceras, however, is generally more involute than Domatoceras and has an annular lobe. 

These differences are precisely the same as those between Metacoceras and Mojsvaroceras.

The degree of involution of the conch in species of 

Domatoceras is varied. Calculation taken from the 

literature on 12 species show the diameter of the umFIGURE 23.—Cross sections of the conch of A, Pselioceras ophioneus (Waagen) 1879, pi. 5, flg. 2b, Height 48 mm; B, Stenopoceras cooperi Miller and Unklesbay 1942, flg. IE, 

Height 56 mm; C, Menuthionautilus kieslingeri Collignon 1933, flg. 4, Height 54 mm; the genotype of Menuthionautilus; D, 8. smithi Miller and Unklesbiy 1947, flg. 1, 

Height 52 mm; E, P. convolutum (Waagen) 1879, pi. 6, flg. 2b, Height 31 mm; F, S. whitei Miller and Youngquist 1949, flg. 22A, Height 37 mm; G, 8. abundum Miller 

and Thomas 1936, pi. 99, flg. 1, Diameter 120 mm; H, 8. abundum Miller and Thomas, 1949, flg. 21A, Diameter 61 mm; /, S. dumblei (Hyatt) 1891, flg. 50, Diameter 138 

mm; the genotype of S.; J, S. sp. Miller 1945, flg. 2B, Height 51 mm;.K", Grypoceras (Domatoceras) umbittcatum Hyatt 1891, flg.47, Height 73 mm; L, O. (D.) wittiamsi Miller 

and Owen 1934, pi. 17, flg. 4, Height 27 mm; M, G. (D.) conoergens (Abich), after Arthaber 1900, pi. 18, flg. 2b, Height 30 mm; N, G. (D.) bradyi Miller and Unklesbay 1942, 

flg. 1H, Height 55 mm; O, G. (D.) walteri Miller and Unklesbay 1942, flg. IP, Height 55 mm: P, G. (D.)sculptile (Qirty) 1915, pi. 31, fig. 2a, Diameter 73 nrm: Q, G. (D.) 

umbilimtum Hyatt, 1891, flg. 46, D. 100 mm±; the genotype of G. (D.); R, G. (D.) moorei Miller, Dunbar, and Condra 1933, pi. 21. flg. 2, Diameter 106 mm-|-; S, G. 

(D.) mosquensis Tzwetaev 1888, pi. 6, flg. 37, Diameter 110 mm: T, G. (D.) hunicus Diener 1903, pi. 1, flg. Ib, Diameter 74 mm.
GRYPOCERATIDAE 49

FIGURE 23
50 AMERICAN TRIASSIC COILED NAUTILOIDS

FlGTJKE 24.
GRYPOCERATIDAE 51

bilicus to range from 16 to 50 percent the diameter of 

the conch.

Range of diameter of umbilicus in 12 species of Domatoceras, expressed as percent of diameter of the conch

Species 

D. unlUamsi— ------------ _______ _

D. bradyi. _________ ___ ___

D. northropi.- _________ ____ ______

D. walteri- ______ __________________

D. obsoletum. __ ___ ____ __ _____

D. umbilicatum- __ ____________ ____

D. shepherdi _ _____________________

D. sculptile _ ______ ________ _

D. hunicum---- _ _________ _______

D. arthaberi- ____________ ____ ___

D. kleighegei- _____________________

D. moorei..- ________ ___ __ ______

Percent 

of diameter of 

conch

-_--____ 50

-_..__-_ 50

________ 50

________ 50

-_--__._ 43

________ 35

-__.____ 35

-_-,-___ 30

________ 30

________ 30

________ 17

________ 16

The last two species are generally thought to be transitional forms to Stenopoceras, which is a highly involute 

and compressed offshoot of Domatoceras.

Within the genus Grypoceras the percentage of the 

diameter of the umbilicus to diameter of the conch 

ranges from 8.5 to 30.

Range of diameter of umbilicus in 9 species of Grypoceras, expressed 

as percent of diameter of the conch

Species 

G. obtusum- -, _ _

G. laubei, ___ _ _ __

G. gumbeli-. __ __

G. whitneyi _ _ _ _

G. privatum- _

G. palladi. __ ______ __ _

G. haloricum-- __ _____ _____

G. mesodicum-.-,---._ _ _ __

Percent 

of diameter of 

conch

..__.-___ 30

.._...__. 27

_-_ — _.__ 24

_-_-_____ 24

_________ 22

_________ 18

.-_-.____ 17

,-_-_.___ 14

G. involutum- ----_-___..___________________ 8. 5

Whereas the range in width of the umbilicus to the 

diameter of the conch hi Grypoceras is 8.5 to 30 percent, 

that of Domatoceras, if one leaves out of consideration 

the two species which are transitional to Stenopoceras, 

is from 30 to 50 percent. In neither genus is there any 

obvious correlation between the percentage and geologic 

age, perhaps because available data are insufficient.

The position of the siphuncle in Domatoceras is generally subcentral, but varies in the different species. 

Unfortunately, for many species data on the siphuncle 

are unavailable. Measurements and descriptive data 

on the position of the siphuncle for 10 species were 

analyzed.

Variation in position of the siphuncle in 7 species of 

Domatoceras, expressed as percent of the distance from 

the venter to the siphuncle, to the height of the whorl

Percent

of whorl

Species . height

D. Tdeighegei--------------.----------------- 12. 5

D. walteri--------.---- _ _________---_-__-- 14. 2

D. toddanum.. ______________________________ 20

D. northropi__---------_---_---_. ----------- 24. 5

D. moorei- _________________________________ 25

D. williamsi-.-------------- ________________ 38. 5

D. sculptile--------.----, ------------------- 50

Domatoceras umbilicatum, D. parallelus, and D. mosquensis have the siphuncle "above the center of the 

whorl." The same measurements for Grypoceras range 

from 30 to 50 percent.

Quantitative or diagrammatic data on the sutrre 

pattern are rather meager. In general, Grypoceras t as 

deeper lobes than are found hi Domatoceras, and it also 

has an annular lobe which is unknown as yet in 

Domatoceras.

Many species of Grypoceras lose the angularity of the 

ventral shoulders. It is significant that Mojsisov'cs 

(1902), in describing Grypoceras, pointed out that on 

comparing Domatoceras hunicum with G. brahmanid.'>m 

the marked similarity made him wonder if the specks 

should not be placed hi the same genus. The writer 

believes that the presence or absence of an annular lobe 

is not of great taxonomic importance. The difference 

between Grypoceras and Domatoceras being mainly degree of involution and the presence or absence of an 

annular lobe, the Triassic genus is considered to have 

descended directly from Domatoceras and the latter 

genus is retained as a subgenus of Grypoceras which has 

priority. This is in accord with the treatment given 

Metacoceras and Mojsvaroceras where a rather similar 

relationship exists.

Grypoceras (Plummeroceras) plummeri Kummel, n. 

subgen., n. sp., from the Permian of Texas, is very 

similar to the type species of Grypoceras. It has an 

unusually large ventral lobe, similar to that of G. (G.) 

mesodicum (see pi. 5, figs. 2, 3, 4; text fig. 27). Tv e 

lateral lobe of this specimen is not so concave as 

Mojsisovics' specimen and also the Texas form is more 

evolute.

Grypoceras is widely distributed geographically, and 

is fairly common hi the Alpine and Himalayan TriasHc 

regions. It is also reported in Triassic rocks from 

North America, the Ussuri region, Timor, and Now 

Zealand.

FIGURE 24.—Cross sections of the conch of A, G. mesodicum (Hauer), after Mojsisovics 1873, pi. 8, fig. Ib, Diameter 150 mm; B, G. haloricum (Mojsisovies) 1873, pi. 7, fig. 

4b, Diameter 112 mm; C, G. obtusum (Mojsisovics) 1873, pi. 7, fig. Ib, Diameter 90 mm: D, 0. involutum Kieslinger 1924, pi. 1, fig. 7b, Diameter 82 mm: E, G. gum^eH 

(Mojsisovics) 1873, pi. 7 fig. 2b, Diameter 39 mm: F, G. whitneyi (Gabb) 1863, pi. 3, fig. 3, Diameter 60 mm; G, G. cancettatum Hauer 1896, pi. 5, fig. 6, Diameter 54 irm; 

H, G. quadrangulum (Beyrich) after Mojsisovics 1882, pi. 83, fl?. 3b, Diameter 54 mm; /, G. brahmanicum (Griesbach) after Diener 1897, pi. 1, fig. Ib, Diameter 63 mm: J, 

G. hexagonalis Diener 1897, pi. 1, flg. 2, Diameter 39 mm; K, G. privatum (Mojsisovics) 1882, pi. 40, fig. 3b, Diameter 80 mm; L, G. laubei (Mojsisovics) 1873, pi. 6, fig. 

lOa, Diameter 30 mm.
52

FIGURE 25.—Cross sections of the conch of ^4, Qryponautilus suessi Mojsisovics 1873, pi. 13, flg. 2b, Diameter 70 mm; B, O. galeatus Mojsisovics 1873, pi. 12, flg. 1, Diameter 

390 mm; the genotype of Qryponautilus; C, O. cooperi Smith, based on the holotype at a diameter of about 67 mm; D, Titanoceras ponderosum (Meek), the genotype of 

Titanoceras, after Miller and Unklesbay 1942, flg. U, Height 61 mm; E, Stearoceras sublaeve (Miller, Dunbar, and Condra), after Miller and Youngquist 1949, flg. 19, 

Height 20 mm: F, S. phosphoriense (Branson), after Miller and Youngquist 1949, fig. 11, Height 33 mm; G, S. militarium (Hyatt), after Miller and Youngquist 1949, flg. 

10A, Diameter 49 mm: H, Stearoceras conchiferous (Hyatt) 1891, flg. 24, Height 11 mm: I, S. rotundatum (Miller and Unklesbay), 1942, flg. IB, Height 40 mn: J, S. after - 

rans (Miller and Unklesbay) 1942, flg. 1C, Height 49 mm: K, 8. gibbosus (Hyatt) 1891, flg. 56, Height 82 mm the genotype of -S. L. S. sanandresense (Miller, Dunbar, and 

Condra), after Miller and Unklesbay 1942, flg. ID, Height 34 mm; M, S. simplex (Hyatt,) after Miller and Youngquist 1949, flg. 18, Height 68 mm.
GRYPOCERATIDAE

Distribution of species of the subgenus Grypoceras (Grypoceras)

Species

Grypoceras (Grypoceras) brahmanicum (Griesbach)

1880. 

G. (G.) cancellatum (Hauer) 1896

G. (G.) griesbachi (Diener) 1895-- _____

G. (G.) guembeli (Mojsisovics) 1873__ _

G. (G.) haloricum (Mojsisovics) 1873

G. (G.) hexagonalis (Diener) 1897

G. (G.) involutum Kieslinger 1924__

G. (G.) laubei (Mojsisovics) 1873 ________

G. (G.) lilangense Krafft and Diener 1909

G. (G.) mesodicum (Hauer) 1846. _

G. (G.) milleri Kummel n. sp

G. (G.} obtusum (Mojsisovics) 1873. -

G. (G.} palladi (Mojsisovics( 1869. __

G. (G.) privatum (Mojsisovics) 1883- _

(?. (G.} quadrangulum (Bevrich) 1866

G. (G.) vihianum Diener 1913 _ _ _

G. (G.) lohitneyi (Gabb) 1864___ _____

Stratigraphic distribution

Triassic (Scythian) _ _

do

Triassic (Norian).

do_ ___ _ _

Triassic (Norian). _

Triassic (Scythian) _ _

_____do_________ __________ ______-__--__----_

_____do________________-_ . ____-------------_

_____do.____ ________________ ._____-____---__

_____do__ ___________________________________

Geographic distribution

Himalayas, India.

Yugoslavia.

Himalayas, India.

Alps.

Do.

Himalayas, India.

Timor.

Alps.

Himalayas, India.

Alps.

Idaho.

Alps.

Alps, Yugoslavia.

Alps.

Do.

Himalayas, India.

California, Nevada.

Grypoceras (Grypoceras) milleri n. sp. 

Plate 6, figures 5, 6; text figure 26

One poorly preserved specimen from the Lower Triassic 

Dinwoody formation of southeastern Idaho is available 

for study. The specimen includes only the living 

chamber and part of the crushed and recrystallized 

phragmocone. The living chamber measures 100 mm 

along the venter. The whorl section is subrectangular, 

with a broad slightly convex venter; the flanks are 

flattened and converge gradually towards the venter 

(text fig. 26). The ventral shoulders are abruptly 

rounded. The umbilical shoulders are not well preserved but seem to be well rounded and steep. The 

living chamber expands rapidly, the most adapical part 

measuring 31 mm and 21 mm in height and witdh and 

the most adapertural part 48 mm and 27 mm respectively.

The suture can be made out in a general way on the 

most adapical part of the living chamber. There is a 

deep ventral lobe and a broad lateral lobe. The siphuncle is subventral in position, lying only 5 mm from 

the venter. No surface markings of any kind are 

preserved.

Remarks.—The most interesting and distinctive feaPIGUEE 26.—Diagrammatic cross section of holotype of Grypoceras milleri, n. sp. 

(U.S.N.M. 107095) from the Dinwoody formation, Slight Canyon, southeastern 

Idaho.

ture of this species is the shape of the whorl section. 

In this feature it is very similar to such species of 

Grypoceras (Domatoceras) as G. (D.) hunicum, G. (D.) 

parallelum, and G. (D.) williamsi. With the exception 

of a doubtful species of Grypoceras recorded from tl x 9- 

Ussuri region of eastern Siberia (Diener, 1895) all the 

previously recorded Scythian species are from the 

Himalayan region. All three of the Himalyayp,n 

species (G. (G.) brahmanicum, G. (G.) hexagonalis, and 

G. (G.} lilangense) have compressed subrectangular 

whorl sections with distinct ventral and umbilical 

shoulders. Grypoceras (G.} lilangense also shows p,n 

extraordinary expansion of the living chamber. Grypoceras (G.} milleri is more similar to these Scythian 

species than to any other species of Grypoceras. Muller 

and Ferguson (1939, p. 1584) report G. (G.} cf. G. (<7.) 

brahmanicum from the Candelaria formation of Nevada. 

The geologically younger species of Grypoceras generally 

show more highly arched venters and less distinct 

ventral shoulders. Grypoceras (G.) milleri can be considered a transitional form between (G.} (Domatoceras) 

and G. (Grypoceras).

Occurrence.—Slight Canyon, Paris-Bloomington region, southeastern Idaho; from limestone near middle 

of Dinwoody formation, along road, 600 ft from 

abandoned mine shaft. Collected by the author.

Holotype.—U.S.N.M. 107095.

Grypoceras (Grypoceras) whitneyi (Gabb) 

Plate 5, figure 1; plate 6, figures 1-4

1863. Nautilus whitneyi Gabb, Geol. Surv Calif. Paleontology

vol. 1, p. 19, pi. 3, figs. 5-7. 

1914. Grypoceras whitneyi (Gabb.) Smith, U. S. Geol. Survey

Prof. Paper 83, p. 141, pi. 16, fig. 2, 3, pi. 99, figs. 5-7.

Gabb described this species as follows:

Shell moderate in size; last volution expanding somewhat 

rapidly towards the aperture, enveloping about two-thirds of 

the preceding whorl. Sides flat, converging towards the dorsum,
54 AMERICAN TRIASSIC COILED NAUTILOIDS

and gradually rounding into it. Dorsum slightly arched. 

Umbilicus large, being nearly one-third the diameter of the whole 

disk; the umbilical margin slopes outwards and unites the surface 

of the shell by a rounded angle. Septa deeply arched on the 

sides; separated from each other by about one-third the width of 

the volution. Surface marked by fine lines, which arise in the 

umbilicus; curve slightly backwards and then forwards on the 

side, and, as they pass over the angle between the side and back, 

again curve backwards, making a deep sinus on the dorsum.

The holotype was not available for study. A pleisotype (pi. 6, figs. 1—4) was assigned to this species by 

Smith (1914, p. 141). This specimen measures 88 mm 

in diameter, 46 mm for width of the last whorl, 45 mm 

for height of last whorl and it has an umbilicus 21 mm 

in diameter. The conch is smooth, compressed, and 

evolute. The venter is well rounded, grading onto the 

flanks with no distinct ventral shoulders. The flanks 

are flattened grading onto sharply rounded umbilical 

shoulders and steep umbilical walls. The surface of the 

conch is smooth except for fine growth lines that form 

a rounded sinus on the venter. The siphuncle is 

centrally located. The sutures form rounded ventral 

and lateral lobes.

Smith (1914, p. 141) correctly noted that this species 

is very similar to Grypoceras palladi Moj^isovics 

"differing only in the shallower lateral lobe of the septa."

Occurrence—Holotype from the Buena Vista District, Humboldt Mining region. Plesiotype from Middle Triassic, zone of Ceratites trinodosus, Wheeler mine, 

Buena Vista Canyon, near Unionville, West Humbolt 

Range, Nevada.

Types—Plesiotype, U.S.N.M. 74459.

Subgenus DOMATOCERAS Hyatt, 1891 

Subgenotype: Domatoceras umbilicatum Hyatt

Hyatt (1900, p. 523, 525) placed Domatoceras in the 

family Koninckioceratidae. Miller and Yongquist 

(1949) followed Hyatt in the derivation of Domatoceras 

from Koninckioceras but felt these forms were far 

enough removed to be established in a distinct family. 

It has already been pointed out in the discussion of 

Grypoceras that Grypoceras and Domatoceras are ultimately related and that Domatoceras is placed as a 

subgenus of Grypoceras which has priority. For this 

reason also the family Domatoceratidae Miller and 

Youngquist cannot be used and it falls in the synonomy 

of Grypoceratidae. The morphological characters of 

the subgenus Domatoceras were discussed in the chapter 

on Grypoceras.

The subgenus Domatoceras occupies a position in the 

family Grypoceratidae similar to that of Metacoceras 

in the Tainoceratidae. It seems to be the persistent 

evolving stock from which forms like Stenopoceras, 

Grypoceras, and Menuthionautilus are thought to have 

been derived. Miller and Youngquist consider Stearoceras to be an independent development out cf Koninckioceras paralleling Domatoceras and that S^aroceras 

and Domatoceras are more or less gradational and connected by intermediate forms.

Subgenus PLUMMEROCERAS Kummel, n. subgenus

Subgenotype: Grypoceras (Plummeroceras) plummeri Kummel, 

n. sp.

The single specimen upon which this new subgenus 

is based is a compressed evolute conch with a flattened 

venter. The conch agrees in essentially al] features 

with representatives of G. (Domatoceras), such as 

G. (D.) williamsi Miller and Owen except in having a 

very deep ventral lobe. The species that have been 

assigned to G. (Domatoceras) have very shallow ventral 

lobes or sutures which pass straight over the venter. 

The remaining Paleozoic genera of the Grypc ceratidae 

likewise have very shallow ventral lobes. Ifenuthionautilus is an involute compressed nautiloid with a deep 

ventral lobe, but not nearly so well developed as in 

G. (Plummeroceras). Within the subgenus G. (Grypoceras} well-developed ventral lobes are present. The 

genotype G. (G.) mesodicum has a ventral lobe very similar to that in G. (Plummeroceras), but again it does 

not appear to be so deep.

G. (Grypoceras) is belived to be a direct evolutionary 

development out of G. (Domatoceras), actually replacing 

the latter subgenus in the Triassic. The Paleozoic 

species of G. (Domatoceras) do not show much evolution 

in any particular direction or feature. However, in 

G. (Grypoceras) there are definite trends towards a 

more involute conch, rounding of the ventral shoulders 

and the venter, and increased differentiation of the 

suture. Early Triassic species of G. (Grypoceras) 

seem more similar to Permian species of G. (Domatoceras) than to late Triassic species of G. (Grtpoceras). 

G. (Plummeroceras) has an advanced and specialized 

type of suture developed on a conch that is fairly 

primitive for this evolutionary line and is interpreted 

as a specialized development of the subgenus G. (Domatoceras) not belonging in the group that eventually 

produced the forms included in G. (Grypoceras).

The only specimen of this subgenus available is from 

the Belle Plains formation (Leonard), Callahan County, 

Texas.

Grypoceras (Plummeroceras) plummeri, n. sp. 

Plate 5, figure 4; text figure 27

The conch is compressed and evolute, with flattened 

venter, angular ventral shoulders. The flanks of the 

phragmocone are flattened to slightly arched, becoming 

more arched on the living chamber. The umbilical 

shoulders are sharply rounded and the umbil^al walls 

steep. The greatest diameter of the cone1! is 168
GRYPOCE RATID AE 55

Distribution of species of the subgenus Grypoceras (Domatoceras)

Stratigraphic distribution Geographic distribution

Grypoceras (Domatoceras) arthaberi (Haniel) 1915__ 

G. (D.) bradyi (Miller and Unklesbay) 1942.____. 

G. (D.) complanatum (Sowerby) 1821______________

G. (D.) fredericksi (Kruglov) 1928_______________

G. (D.) hunicum (Diener) 1903

G. (D.) inostranzewi (Tzwetaev) 1888 

G. (Z>.) kleihegei (Miller, Lane, and Unklesbay) 1947-

G. (D.) krotoyi (Kruglov) 1928

G. (D.) minimum (Kruglov) 1928-________________

G, (D.) moorei (Miller, Dunbar, and Condra) 1933__ 

G. (D.) mosquensis (Tzwetaev) 1888_______________

G.t (D.) nikitowkensis (Jakowlew) 1899

G. (D.) northropi (Miller and Unklesbay) 1942. 

G. (D.) obsoletum (Strugeon) 1946___________

G. (D.) parallelus (Abich) 1900.

(?. (D.) planovolve (Shumard) 1858_________

G. (D.) sculptile (Girty) 1911__________

G. (D.) shepherdi (Sturgeon) 1946._______

G. (D.) subquadrangulare (Grabau) 1924____

G. (D.) umbilicatum (Hyatt) 1891________

G. (D.) walteri (Miller and Unklesbay) 1942. 

G. (D.) williamsi (Miller and Owen) 1934___

Permian (Bitauni and Amarrassi beds). 

Permian (Kaibab limestone)__________

Carboniferous_ ____________________

Permian (Artinskian and Kungurian) _. 

Permian (Chitichum formation) _______

Upper Carboniferous_______________

Pennsylvanian (Winterset limestone).. 

Permian (Artinskian and Kungurian) _. 

Upper Carboniferous (Uralian)_______.

Pennsylvanian (Kansas City group) _ _. 

Upper Carboniferous_______________

Permian (middle)__________________

Permian (Chupadero formation) _ 

Pennsylvanian (Allegheny formation) _ 

Permian (Djulfa beds)________--_-__.

Pennsylvanian. _____________________

Pennsylvanian (Wewoka formation) _ _. 

Pennsylvanian (Allegheny formation) _. 

Permian (Paotechow limestone) _______

Pennsylvanian (lower)_______________

Permian (San Andres limestone)_______

Pennsylvanian (Cherokee formation) __.

Timor.

Arizona.

Isle of Man.

Ural Mountains, Russia.

Himalayas, India.

Central Russia.

Jackson County, Mo.

Ural Mountains, Russia.

Do.

Kansas. 

Central Russia. 

Donetz Basin, Russia. 

New Mexico. 

Ohio. 

Armenia. 

Nebraska. 

Oklahoma. 

Ohio.

Shansi, China. 

Kansas. 

New Mexico. 

Missouri.

mm, width and height of the most adoral part of the 

living chamber are 47 mm and 59 mm respectively. 

The living chamber measures 160 mm along the venter. 

At the junction of the living chamber and the phragmocone the venter is 25 mm wide.

The umbilicus is broad, measuring 67 mm, and the 

umbilical perforation is 6 mm. in diameter. The 

whorls are very little embracing. The specimen is an 

internal mold with a perfectly smooth surface. There 

appear to be, however, low, small, and indistinct elongated nodes on the ventral shoulders of the most adoral 

half volution of the phragmocone. There are also two 

low, large, blunt nodes on the umbilical shoulders of 

the living chamber.

The suture is the most distinctive feature of this 

species (text fig. 27). The ventral lobe is deep and 

acutely rounded. The most adoral suture has a ventral 

lobe 23 mm wide and 23 mm deep. In the more 

adapical sutures the depth of the ventral lobe is always 

slightly less than the width of the lobe. There is an 

acute saddle on the ventral shoulder which passes to a 

broad deep lateral lobe spanning the whole flank. On 

the umbilical wall, the suture trends slightly adorally 

and is faintly concave. The septa are closely spaced, 

with 27 camerae in the last volution. The siphuncle 

was not observed.

Remarks.—This species is very similar to such 

species of G. (Domatoceras} as G. (D.} williamsi Miller 

and Owen and G. (D.) umbilicatum Hyatt. The only 

essential difference is in the deep ventral lobe. In 

this it is similar to G. (Grypoceras) mesodicum (Hauer) 

of the Upper Triassic, although it differs in being 

more evolute and compressed. G. (D.} williamsi is of 

special interest because it has nodes developed on portions of the ventral and umbilical shoulders very similar 

to that seen in (6?.) (Plummeroceras) plummeri.

Occurrence. Belle Plains formation, 2K miles west 

of Baird, Callahan County, Texas; Bureau of Economic 

Geology loc. 30-T-9; the type specimen was collected 

by F. B. Plummer, for whom it is named.

Holotype.—Bureau of Economic Geology, University 

of Texas, no. 7173.

Genus GRYPONAUTILUS Mojsisovics, 1902 

Genotype: Nautilus galeatus Mojsisovics

Mojsisovics (1902, p. 229) erected this group as a 

subgenus of Grypoceras and most authors have accepted this arrangement. The writer believes that 

this group of nautiloids should be given full generic 

rank. Gryponautilus has been recorded from only th^ 

Karnian and Norian and seems to be a specialized offshoot of Grypoceras; four species, and four specimens 

referred with question or with affinities to one of thQ, 

four species, have so far been recorded. Of these eight 

forms one occurs in the Norian, and seven in th^ 

Karnian.

Gryponautilus is a highly involute nautiloid with a 

very narrow venter on the mature portions of tfo 

conch. The inner whorls have broad concave to convex 

truncated venters and inflated flanks (text fig. 25). 

According to Mojsisovics, in the genotype specie? 

the venter becomes very narrow and almost forms a 

sharp keel at a whorl height of 130-150 mm. In such 

species as G. suessi and G. cooperi, both much smaller 

than G. galeatus and not having the acute ventered 

last whorl, there is a row of nodes along the sharp 

ventrolateral margins. Likewise G. suessi and G. 

cooperi have very simple sutures with very shallov
56 AMERICAN TRIASSIC COILED NAUTILOIDS

ventral and lateral lobes. In G. galeatus there is a 

shallow ventral lobe, a deep lateral lobe, anc1 a lateral 

saddle that separates the lateral lobe from the umbilical 

lobe (Mojsisovics 1902, p. 229). Gryponai'iilus also 

has an annular lobe.

None of the species assigned to Gryponautilus have 

the highly contracted venter in the adoral whorls of 

the genotype. They all, however, have hirer whorls 

that closely resemble those of G. galeatum and are 

probably correctly assigned to this genus. Mojsisovics 

believed Gryponautilus to be an aberrant involute 

offshoot of Grypoceras, and the present vriter has 

found no evidence to the contrary.

Gryponautilus cooperi (Smith) 

Plate 7, figures 1-5

1927. Grypoceras (Gryponautilus) cooperi Smith, U. S. Geol. 

Survey, Prof. Paper 141, p. 107, pi. 88, figs. 1-5.

The holotype and one paratype are ava.ilable for 

study. The conch is involute, robust, and has a slightly 

arched truncated venter. The living chamber of the 

holotype is 75 mm long and of the paratype 48 mm. 

The greatest width of the conch is just ventral to the 

umbilical shoulder and the broadly rounded f anks converge strongly towards the venter. The ventral 

shoulders are acute and have conspicuous elongated 

nodes that coalesce to form an almost continuous carinate ridge along the shoulder. The nodes on the 

ventral shoulder are nearly paired on the phrr,gmocone, 

but on the living chamber they are alternate in position.

The suture has a very shallow ventral and lateral 

lobe. The siphuncle was not observed. No part of the 

shell is preserved on either available specimen.

Diameter. __________-_---_-___-_____

Height of last whorL- _ _____---_-_____

Width of venter.

Dimensions (n millimeters)

Holotype

67 

38 

41

8 

18

Paratype

25. 5 

15. 

22. 5 

5. 

10.

FIGURE 27.—Diagrammatic cross section and representation of suture of the holotype 

of Grypoceras (Plummeroceras) plummeri n. sp. (Bureau of Economic Geology 

Coll., 7173) from the Belle Plains formation, Callahan County, Texas, X0.8.

Gryponautilus cooperi appears to be closely related to 

G. suessi Mojsisovics and G. suessiforme Diener, but is 

sufficiently different to be easily distinguished. These 

three forms differ from the genotype, Gryponautilus 

galeatus Mojsisovics, in lacking the nearly acute venter 

in the mature^ portion of the conch.

Occurrence.—From the Upper Triassic limestone, 

upper or Juvavites subzone of the zone of Tropites 

subbullatus, Bear Cove, north end and east side of
GRYPOCERATIDAE 57

Brock Mountain, between Squaw Creek and Pit River,

Shasta County, California.

Types.—Holotype, U.S.N.M. 74127; paratype 74127a

Genus MENUTHIONAUTILUS Collignon, 1933 

Genotype. Nautilus (MenuthionautUus) kieslingeri Collignon

Unique among Triassic nautiloids is this monotypic 

genus from Scythian rocks in northern Madagascar. 

Few late Paleozoic or Triassic nautiloid genera have the 

siphuncle in an extremely ventral position. Solenochilus is the only late Paleozoic form with the siphuncle 

in this position. MenuthionautUus is the only Triassic 

genus with the siphuncle against the venter. Syringoceras has a siphuncle that is somewhat ventrally placed 

but it is not in so extreme a position as in Solenochilus 

or MenuthionautUus.

The conch is involute, rapidly expanding, and smooth. 

Whorls are compressed with a broadly convex venter 

on the mature portion of the conch. The inner whorls, 

according to Collignon's cross section (text fig. 28 of 

present report) have a flattened venter. The flanks are 

broadly convex. The umbilicus measures approximately 12 percent of the diameter of the conch. The 

umbilical shoulders are sharply rounded, unbilical walls 

steep. The suture forms a ventral lobe and a broad 

lateral lobe that occupies nearly the whole flank. The 

siphuncle is in an extreme ventral position and about 

1 mm in diameter.

The shape of the conch and the suture clearly place 

this form in the Grypoceratidae. It shows closest

FIGURE 28.—Diagrammatic cross section of the holotype of Menuthionautilus_ kieslingeri Collignon from the Lower Triassic of Madagascar, X 1. After Collignon 

1933, fig. 4.

affinities with the subgenus Grypoceras (Domatoceras} . 

The compressed involute conch with a flattened convex 

venter on the inner whorls and a more broadly convex 

venter on the mature portion of the conch also seem tc 

indicate affinities with Q. (Domatoceras}. The suture? 

are similar, both forms having rounded ventral and 

lateral lobes. Such involute species of G. (Domatoceras} as Q. (D.} kleihegei and Q. (D.} moorei are very 

similar in their main features to MenuthionautUus 

kieslingeri. Likewise in both of these species the siphuncle lies in.a somewhat ventral position, G. (D.) 

kleihegei having its siphuncle only 12.5 percent of the 

height of the whorl from the venter. G. (Domatoceras} 

was also the ancestral form of Stenopoceras, a highly 

compressed genus with a very narrow venter. MenuthionautUus shows some affinities to Grypoceras, also 

considered a derivative of G. (Domatoceras}. However, Grypoceras appears to be a more advanced form 

and differs in the proportions of its sutural element? 

and in general form of the conch. It seems best tc 

consider MenuthionautUus an aberrant offshoot of G. 

(Domatoceras}.

Genus STENOPOCERAS Hyatt, 1893 

Genotype: Phacoceras dumblei Hyatt

Late Paleozoic nautiloids with strongly compressed 

and involute smooth conchs are generally placed in the 

genus Stenopoceras. The suture forms a deep ventral 

saddle, a broad rounded lateral lobe, a smaller rounded 

dorsolateral saddle in the region of the umbilical 

shoulder, a similar lobe that centers on or near the 

umbilical seam, and a similar internal lateral saddle 

which extends to a moderately deeply depressed Vshaped truncated dorsal lobe. The siphuncle is small 

and lies ventral of the center of the conch.

Stenopoceras is clearly related to G. (Domatoceras} 

(Miller and Youngquist, 1949, p. 70). It is connected 

with the latter genus through such species as G. (D.} kleihegei and G. (D.} moorei. Hyatt (1891, p. 349) made 

the following comments in his discussion of the genotype 

species of Stenopoceras, Phacoceras dumblei: The aspect 

of the adults and the sutures in this genus are like 

Triassic species such as Grypoceras (Nautilus} galeatus, 

Mojsisovics, [now Gryponautilus] and at first they 

appear to have occurred before their proper geologic 

period. When, however, their young are studied, it is 

plain that their shells at early stages have the ordinary 

characteristics of normal members of the Carboniferous 

faunas, and that the peculiarities of later stages were 

evolved from purely Carboniferous forms. There 

mimicry of Triassic shells in later stages must therefore 

be regarded simply as good examples of parallel progressive complications arising independently in different 

genetic series during different periods of time.
58 AMERICAN TRIASSIC COILED NAUTILOIDS 

Distribution of species of the genus Stenopoceras

Stratigraphic distribution Geographic distribution

Stenopoceras abundans Miller and Thomas 1936. 

S. cooperi Miller and Unklesbay 1942________

S. dumblei (Hyatt) 1891_______________

S. inexpectans Miller 1945____-__--____.___.^_

S. rouillieri (deKoninck) 1878.-____-____--___

S. smithi Miller and Unklesbay 1947_________

S. tularosense Miller 1932.___________________

S. whitei Miller and Youngquist 1949________

Pennsylvanian (Casper formation). 

Pennsylvanian (Neva limestone) _ _ 

Permian (Fort Riley? limestone) _ _ 

Permian (Leonard formation) _____

Upper Carboniferous___________

Pennsylvanian (Conemaugh series). 

Pennsylvanian (Abo? sandstone) _ _ 

Permian (Clyde formation) _______

Wyoming.

Kansas.

Geary County, Kans.

Brewster County, Tex.

Central Russia,

Pennsylvania.

New Mexico.

Baylor County, Tex.

This genus represents a specialized compressed offshoot of 6. (Domatoceras) and does not seem to have 

given rise to any other forms. Stenopoceras ranges 

from the lower part of the Upper Carboniferous up into 

the middle part of the Permian in North America and 

central European Russia.

Genus STEAROCERAS Hyatt, 1893 

Genotype: Endolobus gibbosus Hyatt

Miller and Youngquist (1949) in their monograph on 

American Permian Nautiloids discussed this genus 

extensively. They recognized that a wide assortment 

of both quadratic and compressed forms had been included in Domatoceras. Very little attention has been 

given the genus Stearoceras since Hyatt described it. 

As now defined by Miller and Youngquist it includes 

forms with subtrapezoidal conchs that are depressed 

dorsoventrally, and flattened laterally and ventrally 

(text fig. 25). The umbilicus is moderate in size, deep 

and probably perforate. The umbilical shoulders are 

fairly distinct, and the umbilical walls are steep. The 

sutures form slight ventral^ lateral, and dorsal lobes and 

there is a small annular lobe.

The above authors broadened the interpretation of 

this genus by including several species with a wide umbilicus and rather abrupt umbilical shoulders. Their 

conclusions on this genus are tentatively followed by 

the present writer. Actually, Stearoceras, includes many

nautiloids with subtrapezoidal conchs that were once 

included in Domatoceras. Several species previously 

placed in Titanoceras and Metacoceras were also placed 

in Stearoceras by Miller and Youngquist. T>eir interpretation is very different from earlier authors and it is 

not considered at all certain that all the species now 

referred to this genus are properly placed.

Stearoceras seems to be an independent development 

out of Koninckioceras paralleling O. (Domatoceras}. As 

pointed out by Miller and Youngquist (1949, p. 42) 

there are intermediate forms between Stearoceras and 

O. (Domatoceras). It is known to range from the lower 

part of the Pennsylvanian to the middle Penrian.

Genus F8ELIOCERA8 Hyatt, 1883 

Genotype: Nautilus ophioneus Waagen

Of the nine genera included in the Grypoceratidae 

Pselicoceras is the most widely umbilicate form. Hyatt 

erected this genus for the "Ophionei" of Waagen (1879, 

p. 58) designating Nautilus ophioneus Waagen as the 

genotype. The group includes compressed nautiloids 

with whorls little embracing and having an umbilical 

perforation. The conch is smooth, ventral and lateral 

areas are slightly convex, and umbilical shoulders 

broadly rounded (text fig. 23). The suture is straight 

over the venter and forms a shallow lateral lobe. The 

siphuncle is about central. Only the thr^e species 

described by Waagen from the Productus limestone of

Distribution of species of the genus Stearoceras

Species Stratigraphic distribution Geographic distribution

Stearoceras aberrans (Miller and Unklesbay) 1942___ 

S. conchiferum (Hyatt) 1891____________________

S. gibbosus (Hyatt) 1893_____________________

S. hesperium Miller and Youngquist 1949._________

S. highlandensis (Meek and Worthen) 1873__--____-

S. ingens (Miller, Dunbar, and Condra) 1933_--__-_ 

S. lasallensis (Meek and Worthen) 1873____-_ ____-.

S. militarium (Hyatt) 1893________-___-___-__--

<S.? permianum (Swallow) 1858___________________

S. phosphoriense (Branson) 1930_________-__-__--_

S. rotundatum (Miller and Unklesbay) 1942________

S. sanandreasense (Miller, Dunbar, and Condra)

1933. 

S. simplex (Hyatt) 1893______________-_______-__

S. sublaeve (Miller, Dunbar, and Condra) 1933___ _ 

S. toddanum (Gurley) 1883__---_-_---_------_-__-

Permian (Chupadera formation)_____________

Late Paleozoic._____________________________

Pennsylvanian (lower)_____________ _-L ________

Permian (Leonard formation)___________1____.

Pennsyl vanian (M cLeansboro formation) _______

Pennsylvanian (middle)______________________

Pennsylvanian (McLeansboro formation)_______

Permian (Clyde formation)___________________

Permian__ ________________________________

Permian (Phosphoria formation)______________

Permian (San Andres limestone)_____________

Permian (San Andres limestone and Kaibab

formation). 

Permian (Clyde formation)___________________

Pennsylvanian (Neva limestone)_____________

Pennsylvanian ______________________________

New Mexico. 

Texas.

Do.

Do.

Illinois. 

Nebraska. 

Illinois.

Baylor County, Tex. 

Kansas. 

Wyoming. 

New Mexico. 

New Mexico, Ariz.

Baylor Count"1", Tex.

Texas.

Missouri.
SYRINGONAUTILIDAE

the Salt Range have been assigned to this genus: P. 

ophioneus from the lowest part of the Middle Productus 

limestone, P. connectens from the upper part of the 

Middle Productus limestone, and P. convolutus from 

the Upper Productus limestone.

Miller and Youngquist (1949, p. 41) placed Pselioceras 

in the Domatoceratidae, and they also pointed out the 

general similarity of that genus with Domatoceras but 

suggested that it may have had a different ancestry. 

Miller and Unklesbay (1942, p. 721-722) had placed 

these three species in the genus Domatoceras. Waagen 

(1879, p. 63) pointed out the similarity of P. convolutus 

with Nautilus spitiensis Stoliczka. Waagen recognized 

an evolutionary trend in his "Ophionei" toward greater 

involution and believed that Nautilus spitiensis now 

Syringonautilus was merely a continuation of this 

developmental series.

Genus TITANOCERAS Hyatt, 1884 

Genotype: Nautilus ponderosus White

Miller and Youngquist (1949, p. 69-70) characterized 

this genus as follows:

The whorls are subquadratic in cross section, being distinctly 

wider than high, slightly impressed dorsally, rounded dorsolaterally, flattened but nevertheless convex laterally, subangular 

ventrolaterally, and concave ventrally. The umbilicus is large, 

open, and perforate. At full maturity each of the ventrolateral 

shoulders of the conch bears a row of relatively small elongate 

nodes. The mature sutures form broad rounded ventral, lateral 

and almost certainly dorsal lobes. No information is available 

in regard to the siphuncle.

These authors placed no late Paleozoic nautiloids in 

this genus in their monograph on Permian Nautiloids. 

It is not clear how many Carboniferous species should 

be placed here in addition to the genotype. Titanoceras is possibly an offshoot of G, (Domatoceras) and 

does not seem to have been a direct ancestor of any 

Triassic species.

Family SYRINGONAUTILIDAE Mojsisovics, 1902

The interpretation of this family followed here is very 

similar to that of Mojsisovics when he first established 

it. Only five genera, more or less closely related, are 

included: Syringonautilus, Syringoceras, Juvavionautilus, Oxynautttus and Clymenonautilus. Syringonautilus and Syringoceras, which differ only in the position 

of the siphuncle, are the dominant forms Distinguishing the two genera on that basis alone is open to 

question. Study of large collections of both genera 

would probably decide the validity of the distinction, 

but such collections were not available. For the 

present, Syringoceras and Syringonautilus are considered independent offshoots from the complex between 

G. (Domatoceras) and Stearoceras of the Grypoceratidae.

Juvavionautilus, Oxynautttus, and Clymenonautilv* 

are aberrant developments of the Late Triassic. TH 

last two genera are monotypic and the first has only 

six species. Juvavionautilus has a conch pattern similar 

to some late Paleozoic domatoceratids, and Oxynautttv* 

has a highly involute compressed conch similar to that 

found in Stenopoceras. Clymenonautilus has a conch 

pattern like that of Syringonautilus but a suture 

that passes straight over the venter and forms a narrow, 

deep lateral lobe. In this last feature it shows convergence to the Clydonautilidae. Cross sections of tH 

conch of species of each of these genera are illustrated 

in text figure 32.

Syringoceras and Syringonautilus range from tH 

Anisian to the Norian (text fig. 29). Only one species

Scythian Anisian Ladinian Karnian Norian Rhaetian

FIGUBE 29.—Range chart showing known stratigraphic occurrence of the Syringonautilidae. The width of the line is proportional to the number of species.

of Syringoceras is known from North America. TH 

two genera are confined mainly to Triassic areas within 

the Tethyian geosyncline. Juvavionautilus is Norian 

in age and found in the Alpine and Timor Triass; o 

areas. Clymenonautilus is found only in the Norian of 

the Alps. OxynautUus is found in the Norian of tH 

Alps and of California (Smith, 1927).

PHYLOGENY

The origin of the Syringonautilidae is much lens 

obvious than the other families of Triassic nautiloids 

(text fig. 21). Their origin in the Grypoceratidae is 

based on the similarity of the basic conch patterns 

found in some groups of these two families. The mopt 

important evolutionary lines in Pennsylvanian and 

Permian Grypoceratidae are Stearoceras and G. (Domatoceras), which show a wide divergence in conch form 

and have transitional forms between them. It is in 

these transitional forms that one can find nautiloids 

with the essential morphological features from which 

it was possible to derive two independent lines, that r,
60 AMERICAN TRIASSIC COILED NAUTILOIDS

one leading to Syringonautilus and the other to Syringoceras. It is difficult to imagine any other late Paleozoic 

ancestors for these two Triassic genera.

The evolution of Syringonautilus and that of Syringoceras have interesting and contrasting patterns. 

Syringonautilus has the largest number of species at 

the beginning of its recorded history and declines 

rapidly in numbers of species. Syringoceras begins 

slowly and reaches its acme in numbers of species late 

in its history. The reason for such a pattern is not 

known.

In the Late Triassic three aberrant forms developed 

out of Syringonautilus: Juvavionautilus, Oxynautilus, 

and Clymenonautilus. Juvavionautilus and Oxynautilus 

have conch patterns similar to those found in the 

Paleozoic ancestral family Grypoceratidae. Clymenonautilus is convergent with the Clydonautilidae in its 

suture but retains the conch pattern of typical Syringonautilus. All three Late Triassic genera are unsuccessful experiments coming near the end of the family 

history.

Genus SYRINGONAUTILUS Mojsisovics, 1902

Genotype: Nautilus lilianus Mojsisovics

Syringonautilus is distinguished from Syringoceras by 

the subcentral position of its siphuncle (pi. 18, figs. 3, 

4). Syringoceras has a nearly marginal siphuncle, but 

the literature reveals neither the amount of variation 

in position of the siphuncle within either genus, nor 

whether there is gradation between the two genera.

A diagram showing the number of species p^r epoch 

(text fig. 29) reveals an interesting distribution that may 

or may not be significant. Of Syringonautilus there are 

no species in the Scythian, 9 in the Anisian, 5 in the 

Ladinian, 3 in the Karnian, and 1 indeterminate species 

in the Norian. For Syringoceras there are no Scythian 

species, 2 in the Anisian, 2 in the Ladinian, 13 in the 

Karnian, and 1 species in the Norian. The pattern of 

diversification between these two genera is exactly 

opposite. Syringonautilus has a great period of expansion near the beginning of its range and gradually 

declines. Syringoceras develops slowly and has its 

period of expansion in the Karnian, which is followed 

by a great decline in the Norian where only one species 

is recorded. The significance of the above distribution 

patterns is difficult to interpret in absence of careful 

first hand study of all the species involved. Admittedly 

also the paleontologic record is incomplete and the 

relationship of distribution may be merely a coincidence. 

Possibly the forms with the siphuncle in a nearly 

marginal position now included in Syringoceras are 

merely intrageneric variants that have been set apart 

on this one character. If this is true, the proportion of 

variants towards a nearly marginal siphuncle progressively increases.

No species of Syringonaulilus have as yet been 

recorded from the North American Triassic. However, 

the genus is widespread in Eurasia, having been reported from the Alps, Hungary, Germany, Greece, 

Himalayas, Timor, Japan and Spitzbergen.

Distribution of species of the genus Syringonautilus

Species

Syringonautilus bosnesis (Hauer) 1892 _

S. bullatus (Mojsisovics) 1873 ____ _ _

S. carolinus (Mojsisovics) 1882

S. japonicus Yabe and Shimizu 1927

S. lilianus (Mojsisovics) 1882

S. linearis (Miinster) 1841 _ _ _

S. longobardicus (Mojsisovics) 1882

S. nordenskjoldi (Lindstroem) 1865 _ _ _ _

S. obtusicarinatus (Reis) 1900 _ _ _ _

S. primoriensis (Martelli) 1904

S. spitiensis (Stoliczka) 1865 __

S. subbullatus Schnetzer 1934

S. subcarolinus (Mojsisovics) 1882

S. zinnae (Airaghi) 1902

S. nov. f. ind. Mojsisovics 1896

Stratigraphic distribution

_. ___do-__ —— ——— ----- ------------------

—— _do—— __- —— — — ---- ——— —— --

_-_-.do——— — . _______- — ——— _ — —— —

Geographic distribution

Alps, Greece, Timor.

Japan.

Alps, Yugoslavia . Alps.

Do.

Spitzbergen.

Yugoslavia, Greece.

Himalayas, India.

Germany.

Alps, Yugoslavia.

Alps, Roumania, Greece?

Genus SYRINGOCERAS Hyatt, 1894

Genotype: Syringoceras granulosostriatus (Klipstein)

When Hyatt (1894, p. 546), first described this genus 

he made the following comments:

This genus has been framed for Triassic species like the type, 

Syringoceras grarnriosostriatiis, which have a tubular, nepionic 

volution with the siphuncle subventran. The early nepionic 

shell is also ornamented with very closely set transverse ridges,

but it has no longitudinal ridges until a comparatively late stage. 

This nepionic ornamentation is like that of the genus Hercoceras 

at the same age. The impressed zone is present only after contact 

and is not deep. The genus includes the group of Nautilus 

barrandei of Mojsisovics, the equivalent of Nautilus linearis, 

Laube, and S. (Naut.) evolutum, sp. Mojsisovics.

In the above description Hyatt quite clear1 y designates Syringoceras granulosostriatus as the type (pi. 

18, figs. 5-8). However, Mojsisovics (1902, p. 214)
SYRINGONAUTILIDAE 61

listed Syringoceras barrandei (Hauer) as genotype 

(pi. 18, fig. 13). Every subsequent author who has 

referred to this genus has followed Mojsisovics' interpretation.

Syringoceras includes forms with rapidly expanded 

conchs and usually a small umbilical perforation. The 

early whorls are tubular, but grade into whorls that 

have well-defined and steep to broadly rounded umbilical shoulders and rounded but distinct ventral shoulders 

(text fig. 30). The cross section of a mature conch is 

subquadratic to slightly compressed. The width of 

the umbilicus averages 25 to 30 percent the diameter of 

the conch. The only ornamentation consists of a 

delicate network of lirae. The sutures show only a faint 

ventral saddle, a shallow lateral lobe, and an annular 

lobe. The siphuncle is very near the venter.

The ancestry of Syringoceras is problematic, and its 

affinities to any Permian forms are less obvious than 

for many other Triassic genera. This genus differs from 

Syringonautilus only in position of the siphuncle, the 

latter genus having the siphuncle more nearly central. 

Waagen (1879, p. 63-64) considered Pselioceras convolutum (Waagen) to be closely related to Syringonautilus spitiensis (Stolizska) of the Himalayan Anisian. 

He also mentions the shifting of the siphuncle to a more 

nearly marginal position in some Triassic species, citing 

Syringoceras brevis, S. evolutus, and S. eugyrus, which 

he considered as probable descendants of Syringonautilus spitiensis. Pselioceras is poorly known, and 

only by the three species from the Salt Range described 

by Waagen (1879). Waagen concluded from a study 

of these three species that there was an evolutionary

trend towards tighter coiling, and rounding of the whorl 

section. The Triassic genera Syringonautilus and 

Syringoceras he considered to be in a direct line of tl ^s 

trend. Waagen's interpretations may be correct but 

the meager data do not constitute proof.

The writer believes that a more convincing argument 

can be made for deriving Syringoceras and Syringonautilus from forms probably transitional between 

Stearoceras and G. (Domatoceras). The former genus 

has a depressed subquadratic conch with flattened 

venter and flanks, a moderate and deep umbilicus, and 

a simple suture with an annular lobe. G. (Domatoceras) 

includes compressed nautiloids with a more diversified 

suture. Between these two genera are many transitional forms. Whether all the species assigned to 

Stearoceras by Miller and Youngquist (1949) belong in 

that genus is not known but typical species, and those 

transitional to G. (Domatoceras), have a conch ve^y 

similar to typical Syringonautilus and Syringoceras 

except for being more evolute. The oldest species of 

Syringoceras and Syringonautilus are from the Anisian. 

Syringonautilus and Syringoceras are considered independent developments from the Stearoceras-Domatoceras 

transition complex, but only large collections can prove 

that they are different genera. Vagaries of the position 

of the siphuncle in Stearoceras and G. (Domatoceras) is 

great. Menuthionautilus, a descendant of G. (Domatoceras) from the Early Triassic of Madagascar has the 

siphuncle in a marginal position. Syringoceras is 

considered to be another experimental form, the 

siphuncle shifting to a position near the margin but it 

was a great deal more successful than Menuthionautilus.

Distribution of species of the genus Syringoceras

Species

Syringoceras ads (Munster) 1841 __ ______

S. altius Mojsisovics 1902 ____ __ _ ______

S. barrandei (Hauer) 1847 _ ___ ___ ____

S. breve (Hauer) 1860 ._._ ____ ____ ._ __

S. brevius (Mojsisovics) 1873. ____ _ _ _______ _

S. credneri Mojsisovics 1902 ___ __ ___

S. doubreeanum Mojsisovics 1902__ __ _ _

S. eugyrum (Mojsisovics) 1873 __________

S. evolutum (Mojsisovics) L873__ ___ _ _

S. externecavatum Welter 1915- ___ ___

S. malayicum Welter 1914______ _____

S. renzi Frech 1907 ____ __

S. spurri Smith 1927_ _ ___ ___ ___ ___ ___

S. zitteli Mojsisovics 1902 ____ _ _____

S. zitteli timorense Welter 1914_ _ _______

Stratigraphic distribution

_____do ____ _____ _________ ____ ______

_____do_-______ __-_--_--_---_--_------_-----

_____do______.___ __________________________ _

_____do_-_______ --_-_-----___--__----------_

_____do___.____ ____________________________ _

_____do___________ ___________ --__----__----_

-____do___ _____-_- — — — _ — — — -- — --

Triassic (upper) ___ ____ _________

Geographic distribution

Alps.

Alps, Greece.

Alps, Roumania, Greece.

Alps.

Do.

Do.

Do.

Do.

Alps, Greece.

Timor.

Timor.

Greece.

California.

Germany.

Alps, Greece?

Timor.

232820— 55
62

J k I

FIGURE 30.—Cross sections of the conch of A, Syringoceras credneri Mojsisovics 1902, pi. 6, fig. Ib, Diameter 110 mm; B, Syringoceras zitteli Mojsisovics 1902, pi. 6, flg, 3b, Diameter 

67 mm; C, Syringoceras breve (Hauer), after Mojsisovics 1902, pi. 9, flg. Ib, diameter 42 mm; D, Syringoceras barrandei (Hauer), after Mojsisovics 1902, pi. 5, flg. 2b, 

Diameter 85 mm; E, Syringoceras eugyrum (Mojsisovics) 1873, pi. 6, fig. 3b, Diameter 48 mm; F, Syringoceras evolvtum Mojsisovics 1902, pi. 7, flg. Ib, Diameter 136mm; 

Q, Syringoceras daubreeanum Mojsisovics 1902, pi. 5, flg. Ib, Diameter 37 mm; H, Syringoceras altius Mojsisovics 1902, pi. 6, flg. 2b, Diameter 60 mm; 7, Svringonautttus 

lilianut (Mojsisovics) 1882, pi. 82, flg. 4b, Diameter 40 mm, the genotype of Syringonautilus; J, Syringe-nautilus bosnensis (Hauer) 1892, pi. 1, fig. 3b, Diameter 40 mm; 

Kt Syringonautilus bullatus (Mojsisovics) 1873, pi. 5, fig. Ib, Diameter 126 mm; L, SyringonavtUus nordenskjSldi (Mojsisovics) 1886, pi. 16, fig. 3b, Diameter 90 mm.
SYRINGONAUTILIDAE

Syringoceras spurri Smith 

Plate 7, figures 6, 7; text figure 31

1927. Syringoceras spurri Smith, U. S. Geol. Survey Prof. Paper 

141, p. 106, pi. 104, figs. 8, 9.

The original description by Smith is quoted here: 

Form moderately robust, somewhat compressed laterally, with 

open though not very wide umbilicus and rounded venter. Surface 

shows fine, sharp backward-curving growth lines. Septa have 

only gentle curves; no real lobes nor saddles on the outside. 

Annular lobe not observed.

S. spurri resembles S. altius Mojsisovics but differs in being 

more compressed and less widely umbilicate.

Occurrence.—Upper Triassic Pseudomonotis subcircularis zone of the Star Peak formation, in Muttleberry 

Canyon, in the West Humboldt Range, about 8 miles 

southeast of Lovelock, Nevada.

FIGUBE31.—Diagrammatie cross section of the holotype of Syringoceras spurri 

Smith (T7.S.N.M. 74219) from Star Peak formation, Muttleberry Canyon, 

West Humbolt Range, Nevada, X 1.

Genus JUVAYIONAUTIIUS Mojsisovics, 1902 

Genotype: Nautilus heterophyllus Hauer 1849

The surficial features of the forms included in this 

Upper Triassic genus closely resemble those of G. 

(Domatoceras) . Juvavionautilus includes widely umbilicate perforate shells with flattened to broadly rounded 

ventral and lateral areas. The younger whorls are usually more rounded. The conch expands slowly and the 

impressed zone is usually a third the height of the 

whorl. The greatest width of the whorl is above the 

umbilical shoulder (pi. 18, figs. 1,2; text fig. 32). The 

sutures form a ventral saddle, a broad lateral lobe, a 

small saddle on the umbilical wall, and there is an 

annular lobe. The siphuncle is subcentral in position.

Mojsisovics discussed this genus rather thoroughly 

(p. 222-223, 1902) and believed that JuvavwnauttttisS 

was derived out of Syringonautilus. He pointed particularly to S. longobardicus as a transitional form. In 

this species a definite umbilical shoulder is developed in 

the phragmocone, whereas in most other species tl <^ 

umbilical shoulder is well developed only on the livir?? 

chamber. Mojsisovics also offered the possibility of a 

genetic relationship between Pselioceras and Juvavionautilus but any similarity between these two genera 

appears to be quite superficial. Both genera have a 

ventral saddle or a straight suture over the venter. 

Syringonautilus has a faint ventral saddle also. This 

genus (Syringonautilus) probably has its ancestry in tl °> 

Stearoceras-Domatoceras complex whose members possess 

a ventral lobe. Two species from Timor described by 

Kieslinger (p. 98-100,1924) as J. brouweri and J. geyeriformis, posses shallow ventral lobes in contrasf to 

ventral saddles found in all other species of Juvavionautilus. In all other characters these two species 

agree with typical representatives of this genus and are 

therefore retained in it. It is difficult to consider 

Pselioceras an ancestral form of Juvavionautilus. As 

pointed out by Mojsisovics, Pselioceras is little known ar d 

seems to be confined to the Permian. No forms that 

could possibly be transitional to the Upper Triassic 

Juvavionautilus are known. The writer feels that for 

the time being it is best to follow Mojsisovics' interpretation of deriving Juvavionautilus out of Syringonautilus.

Genus OXYNAUTILUS Mojsisovics, 1902 

Genotype: Nautilus acutus Hauer

This aberrant form derived from Juvavionautilus 

was considered by Mojsisovics to be a subgenus of 

Juvavionautilus. Diener (p. 777, 1919) considered this 

form to be sufficiently distinct to be raised to full 

generic rank, and his procedure is followed here. The 

genus includes nautiloids that have compressed conchs 

with a very narrow to acute venter and with or withorit 

a keel. Whorls expand rapidly, are extremely high 

with the widest portion just above the umbilical shoulders (pi. 19. figs, 1, 2; text, fig. 32). Each whHi 

embraces more than a third of the preceding whorl. 

The umbilicus is well defined, moderate in size and 

perforate, and the umbilical shoulders are abruptly

Distribution of species of the genus Juvavionautilus

Species

Juvavionautilus brouweri Kieslinger 1924 _ ____ ____

J.geyeri Diener 1919___ ___ __ ________ ________

J. geyeriformis KiesUnger 1 924 ____ _ _ ______ ____

J. heterophyllus (Hauer) 1849. ___________ _____ _

«/". subtrapezoidalis Mojsisovics 1902______ ________ _

J. trapezoidalis (Hauer) 1860 _ _____ ____ _______

Stratigraphic distribution

Triassic (upper) __ — ________ ______ ________

Triassic (Norian) ____________________________

---_ do - __ _-__ _ _____________________

__ do ----- ___ - -- _ _ --- _____ --__

Geographic distribution

Timor.

Alps.

Timor.

Alps.

Do.

Alps, Timor.
64 AMERICAN TRIASSIC COILED NAUTILOIDS

TIGTJEE 32.—Cross sections of the conch of A, Oxynautilus acutus (Hauer), after Mojsisovics 1902, pi. 3, flg. Ib, Diameter 138 mm; B, Juvarionautilus trapezoidatts (Hauer), after 

Mojsisovics 1902, pi. 4, flg. Ib, Diameter 116.5 mm; C, J. heterophyttus (Hauer), after Mojsisovics 1902, pi. 4, flg. 2b, Diameter 128 mm; D, Oxynautilus acutus (Hauer), 

after Mojsisovics 1902, pi. 2, flg. Ib, Diameter 163 mm; E, Juvavionautilus brouiveri Kieslinger 1924, flg. 24, Diameter 124 mm; F, J. subtrapezoidalis Mojsisovics 1902, pi. 

3, flg. 2b, Diameter 89 mm; G, J. geyeriformis Kieslinger 1924, flg. 25a, Diameter 52 mm; H, J. geyeri Diener 1919, flg. 19, Diameter 49 mm; /, Clymenonautuus ehrlichi 

(Mojsisovics) 1873, pi. 6, flg. 9b, Diameter 55 mm; J, Syringonautilus zinae (Airaghi) 1902, pi. 4, flg. 4b, Diameter 35 mm; K, S. longobardicus (Mojsisovics) 1882, pi. 83, 

flg. 6b, Diameter 62 mm; L, S. subcarolinus (Mojsisovics) 1882, pi. 83, flg. 2b, Diameter 65 mm.
PARANAUTILIDAE 65

rounded, and the umbilical flanks are slightly convex 

and vertical. The suture forms a narrow to pointed 

ventral saddle, a broad lateral lobe, and a small lobe on 

the umbilical wall, with a saddle on the umbilical 

shoulder. An annular lobe is present. The siphuncle 

lies three-quarters the height of the whorl from the 

venter.

Oxynauiilus is a monotypic genus known from the 

Norian of the Alps. Smith (p. 106-107, 1927) records 

the occurrence of Oxynautilus acutus from the

Upper Triassic Hosselkus limestone, above the coral zone at the 

base of the beds of Norian age at the east side of the north end of 

Brock Mountain, between Pit River and Squaw Creek, Shasta 

County, California.

Smith also states that

This specimen was completely shattered in the attempt to get 

it out of the splintery rock matrix and could not be illustrated.

Genus CLYMENONAUTILUS Hyatt, 1900 

Genotype: Nautilus ehrlichi Mojsisovics

As no definition of this monotypic genus was given 

by Hyatt, the original description of the genotype by 

Mojsisovics (1873, p. 15) is quoted here in part.

Rasch anwachsende Windungen von grosserer Hohe als Dicke 

involviren beilaufig ein Drittel der vorhergehenden Windung und 

bilden einen tiefen in der Mitte durchbrochenen Nabel. Der 

Uebergang von den Seiten in den Convextheil und zur Nabelwand 

ist gerundet. Die Seiten erscheinen ziemlich platt. Auf den 

inneren Windungen seiht man auf der Oberflache der Schale 

feine Querstreifen, gekreuzt von ebenso feinen Langsstreifen. 

Die atissere Windung scheint vollig glatt zu werden; doch kann 

dies vorlaufig nicht mit voller Sicherheit constatirt werden. 

Die Kammer-Scheidewande verlaufen liber den Convextheil 

nahezu gerade; innerhalb der Involutionsspirale bilden sie einen 

ziemlich tiefen zungenformigen Laterallobus, kehren jedoch 

noch vor Erreichung des Nabelrandes in die friihere gerade 

Richtung zuriick und wenden sich auf der Nabelwand etwas 

nach vorn. Die Stellund des Sipho konnte nicht ermittelt 

werden; derselbe scheint sich dicht am Convextheil zu befinden. 

Dimensionen—Durchmesser, 55 mm; Hohe desletztenUmganges, 

28 mm; Dicke des letzten Umganges, 24 mm; Nabelweite, 16 

mm.

(see pi. 7, figs. 8, 9).

Mojsisovics' description can be summarized as 

follows:

The conch is rapidly expanding; the whorls higher than wide 

and inclosing a third of the preceding whorls and forming a deep 

and perforate umbilicus. The ventral and umbilical shoulders 

are rounded. The whorl sides are flattened. On the inner 

whorls the shell has fine cross striae and longitudinal lines. 

The outer whorls appear to be smooth. The suture passes 

straight over the venter and forms a deep, tongue shaped lobe 

on the whorl sides. The position of the siphuncle is not known.

When Hyatt proposed the genus Clymenonautilus he 

placed it in the family Clydonautilidae. Mojsisovics 

(1902, p. 221) differed with Hyatt on the taxonomic

position of Clymenonautilus and made the following 

comments:

Diese Gattung wurde von Hyatt in die Familie der Clydonautilidae gestellt, wozu wohl nur der tiefe, zungenformi-je 

Laterallobus die Veranlassung darbot. Ich kann diese Auffrssung nicht theilen und erblicke in Clymenonautilus einen dur-sh 

die tiefe Ausbiegung eines schmalen Laterallobus abgeanderten 

Nachkommen des Syringonautilus-Stsaames. Die ganze Gestaltung des Gehauses und die Beschaffenheit der Schale weis?n 

deutJich darauf hin.

Die Involution der Umgange ist die gleiche wie bei Syringonautilus.

Ausser dem Laterallobus besitzt Clymenonautilus noch c"ie 

Andeutung eines schwachen Lateralsattels, welcne durch die flache 

Einsenkung eines Umbilicallobus hervorgerufen wird.

Mojsisovics' comments can be summarized as follows:

This genus was placed by Hyatt in the Clydonautilidae in 

which the only relationship is in the deep, tongue shaped lateral 

lobe. In this conclusion I can not agree and see in the character 

of the conch and the lateral lobe relationship to Syringonautilus. 

The involution is the same as in Syringonautilus. In addition 

to the lateral lobe Clymenonautilus has an indication of a wei.k 

lateral saddle which is caused by a shallow umbilical lobe.

There has always been considerable disagreement 

among students of nautiloids as to the value of certain 

morphologic features in taxonomy. Recent work on 

Tertiary nautiloids by Spath (1927), and Miller and 

Youngquist (1949) have stressed the priority of differences in the suture pattern and ornamentation over the 

shape of the conch in the determination of the taxonomic 

position of a genus or species of nautiloid cephalopod. 

In the present case, however, a species agrees perfectly 

with the one group (Syringonautilidae) in the shape of 

its conch and degree of involution text (fig. 32), ard 

with another group (Clydonautilidae) it agrees only in 

the over-all plan of the suture, that of having a deep 

lateral lobe. The lateral lobe in Clymenonautilus is 

rather narrow and confined to the mid point of the 

flanks. The straight course over the venter, in so far 

as the suture is concerned, indicates affinity between 

Clymenonautilus and Styrionautilus. However, the 

over-all similarity in the plan of the conch between 

Clymenonautilus and Syringonautilus, and the Syringonautilidae in general, is impressive. Clymenonautilus 

may represent a late evolutionary experiment on a 

relatively simple conch pattern that is convergent 

towards the Clydonautilidae. Clymenonautilus is a 

monotypic form from Norian rocks of the Alps, and 

until more material is found the question of its affinities 

will remain in doubt. For the present the classification 

of Mojsisovics are followed.

Family PARANAUTILIDAE Kummel, 1950

This new family is proposed to include two genera 

that Mojsisovics (1902) had placed in the family 

Clydonautilidae, along with genera that possessed no
66 AMERICAN TRIASSIC COILED NAUTILOIDS

annular lobe (with the exception of GonionautUus), 

involute conchs, and tended towards increased sinuosity of the suture. Two of the most primitive forms 

(Paranautilus and IndonautUus) are different from the 

remaining members of Clydonautilidae (namely Styrionautilus, Clydonautilus, ProclydonautUus, CosmonautUus, 

and Callaionautilus) in that their conchs are generally 

not so involute and the sutures remain essentially 

straight with only minor inflections. Spath (1927b, 

p. 24) was the first to suggest a new family, commenting

* * * Paranautilus and IndonautUus, Mojsisovics, though 

equally devoid of an annular lobe, must perhaps be referred to a 

separate family distinct also from Grypoceratidae.

Sibyllonautilus, which has an involute depressed 

conch and is characterized by the extraordinary expansion of the whorl section (especially in the living chamber) is also included in this new family. Sibyllonautilus, 

however, differs in one important characteristic from 

Paranautilus and IndonautUus—it has an annular lobe. 

Mojsisovics believed the annular lobe was of great 

systematic importance but other students, such as 

Diener, Kieslinger, Spath, and Miller, have minimized 

the absolute importance of this one character. Spath 

(1924b, p. 24) says:

There seems to be no doubt that this annular lobe cannot be 

used, by itself, for the classification of Jurassic and Cretaceous 

nautili, for it disappears early in Bi&iphytes and may persist in 

forms that otherwise cannot be separated from Eutrephoceras.

The similarity in conch pattern and suture between 

Paranautilus and Sibyllonautilus is striking. Even 

more impressive is the similarity to Liroceras of the 

family Liroceratidae, from which the Paranautilidae are 

thought to have developed. Mojsisovics (1902, p. 

235) considered Sibyllonautilus pertumidus to be most 

closely related to GermanonautUus. The only similarity 

between these two genera is the presence in both of 

annular lobes, the patterns of the conchs are very 

different. Arthaber Q.896) favored a relationship of 

Sibyllonautilus pertumidus to Acanthonautilus cornutus 

(Golovkinsky) (family Liroceratidae) of the Permian 

of Kussia.

The family Paranautilidae is thus proposed to include 

Triassic nautiloids having involute globular to compressed conchs and simple sutures, but which may or 

may not have an annular lobe. Only three genera are 

included in this family: Paranautilus, IndonautUus, and 

SibyttonautUus.

Geographically, the only genus in this family that is 

widespread is Paranautilus. It has been reported from 

beds ranging in age from Permian through the Triassic 

from North America, China, Timor, Himalayas, Sicily, 

Alpine region, and Germany. IndonautUus is a monotypic genus known only from Norian beds of the

Himalayas. Sibyllonautilus ranges from the Anisian 

to the Norian, and has been reported from Nevada, 

British Columbia, Spitzbergen, and the Alpine region.

PHYIOGENY

In most features Paranautilus is closely related to 

Liroceras and allied genera of the Liroceratidae (text 

figure 33, 34). Even though no Scythian species of 

Paranautilus are known, it is suggested that two 

Permian species should be placed in this genus. The 

Liroceratidae Miller and Youngquist (1949) as now 

interpreted contains the following genera: Liroceras 

Teichert, Coelogasteroceras Hyatt, Peripetocercs Hyatt, 

Condraoceras Miller and Unklesbay, and Acanthonautilus Foord. All these forms have smooth, involute, 

nautiliconic conchs which are considerably impressed 

dorsally. These features also characterize the Paranautilidae. Liroceras seems to be the main evolving 

stock of the Liroceratidae with the other genera representing specializations of a Liroceratid conct, Coelogasteroceras and Peripetoceras have conchs that are 

slightly flattened ventrally and laterally. Coelogasteroceras likewise has a ventral groove. Condraoceras 

has a more compressed conch than Liroceras. AcanthonautUus has a very rapidly expanded conch w:th spinelike projections on the unbilical shoulder.

The relationship of Liroceras to Paranautilus is very 

similar to that between Metacoceras and Mojsmroceras, 

Domatoceras and Grypoceras. In the latter case the 

Triassic forms were reduced to subgeneric rank to 

express the closeness of their relationships with the 

late Paleozoic stocks. Liroceras and Paranautilus 

may well have a similar relationship, however, the 

available data are insufficient to establish it.

The Paranautilidae are a small family of unspectacular Triassic nautiloids. Of the three genera 

included in this family Paranautilus is by far the most 

important and abundant. It gave rise to Sibyllonautilus and IndonautUus. Even more important, 

however, it appears to be the stock from which the 

Clydonautilidae arose. In its own evolutionary history 

Paranautilus shows a general trend towards more compression of the conch. Sibyllonautilus is an aberrant 

offshoot developing an extraordinarily expanded conch. 

This same type of specialization is found in Acanthonautilus of the late Paleozoic. Sibyllonautilus also has 

an annular lobe. IndonautUus is a monotypic form 

from Norian formations of the Himalayas. The form 

of the conch is similar to that of some grypoceratids 

with distinct ventral shoulders and rounded umbilical 

shoulders. A monotypic form like IndonautUus is 

difficult to place but in the sum total of its, characters 

it appears to lie closest to Paranautilus.
PARANAUTILIDAE

o

en 

en 

<

or

or LU CL

or

UJ 

Q_

FIGTJBE 33.—Diagram showing inferred phylogeny and geologic distribution of the Paranautilidae, Clydonautilidae, and Gonionautilidae.

Genus PARANAUTILUS Mojsisovics, 1902 

Genotype: Paranautilus simonyi (Hauer)

When Mojsisovics first described this genus (1902, 

p. 205, he diagnosed it as follows:

Extern abgerundete, hochmundige, enge genabelte, glattschalige 

Gehause mit einfachen, nur leicht gebogenen und gedrangt 

stehenden Kammerwanden ohne Internlobus. Sipho bei der 

typischen Art unterhalb der halben Miindungshohe der Internseite genahert, bei anderen Formen auch hoher. Mundrand bei 

altersreifen, ausgewachsenen Individuen auf den Flanken 

eingebogen. Laterallobus bios einen flachen Sinus bildend.

Umbilicalsattel kaum angeduetet. Externsattel bei den typischen Formen schwach angeduetet, einen breiten flachen Bog^n 

beschreibend.

Mojsisovics' description can be summarized as follows: 

Conch smooth, narrowly umbilicate, whorls higher than wide, 

venter rounded with only slightly sinuous septa and no annular 

lobe. Siphuncle generally below the center of the whorl section. 

Growth lines concave on the whorl sides. Lateral lobe shallow, 

umbilical saddle hardly noticable, ventral saddle broad and low.

Paranautilus has the simplest plan of conch of all the 

,Triassic nautiloid (text fig. 35). Mojsisovics con,-
68 AMERICAN TRIASSIC COILED NAUTILOIDS

PERMIAN TRIASSIC

Scythian Anisian Ladinian Karnian Norian Rhoetian

Gonionautilus

Callaionautilus

Cosmonautics

Proclydonautilus

Clydonautilus

Styrionautilus

Paranautilus

Sibyllonautilus

Indonautilus

FIGTJKE 34.—Range chart showing known stratigraphic occurrence of Paranautilidae, Clydonautilidae, and Gkmionautilidae. The width of the line is

proportional to the number of species.
PARANAUTILIDAE

sidered Nautilus peregrinus Waagen, an unusual 

species from the Middle Productus limestone of the 

Salt Range, as possibly the oldest species of this genus. 

Miller and Unklesbay (1942, p. 721) had tentatively 

placed this species in Stenopoceras. Reed (1944, p. 

362-363) considered it highly probable that Nautilus 

peregrinus should be placed in Paranautilus, but 

points out its close resemblance to Solenochilus mokouensis Yin (1933, p. 28, pi. 5, figs, la-b) of the Penchi 

Series North China and Solenochilus buriensis Reed 

(1944, p. 362, pi. 62, figs. 1, la-b) of the Upper Productus Limestone, Salt Range, India. The surficial 

features of the conch of Nautilus peregrinus and Solenchilus buriensis are very similar, but in the latter species 

the siphuncle is in a ventromarginal position, whereas 

in Nautilus peregrinus the siphuncle is more nearly 

central. Solenochilus mokouensis Yin is not a Solenochilus—one of the most diagnostic features of the 

genus is the ventromarginal position of the siphuncle. 

"Solenochilus" mokouensis has the siphuncle in a subcentral position "nearer the outer than the inner 

margin" and the species appears to be closely related to 

Nautilus peregrinus.

Unfortunately Waagen's Nautilus peregrinus is based 

on one poorly preserved and crushed specimen, making 

it difficult to ascertain all the morphological features. 

The conch is involute, compressed, and has a small and 

deep umbilicus. The venter is broadly rounded and 

the umbilical shoulders are rounded. The specimen 

has a shell diameter of 91 mm, diameter of the umbilicus 

6 mm, height of the last whorl 58 mm, and width of the 

last whorl 35? mm. The suture is nearly straigh t, showing a broad shallow lateral lobe and a shallow dorsal 

saddle. The siphuncle appears to be "within the 

outer third of the radial diameter of the section".

The assignment of Nautilus peregrinus to Stenopoceras 

by Miller and Unklesbay does not seem to be justified. 

Stenopoceras is a highly compressed form with a narrow 

venter (text fig. 23). There are no other genera of late 

Paleozoic nautiloids to which Nautilus peregrinus can 

be assigned. There are, however, affinities to Paranautilus. In general the height and width of the whorl 

section of Paranautilus are about equal. However, 

there are several species that show a compressed conch 

as in Waagen's species. The present writer agrees 

with Mojsisovics' conclusion as to the relationships of 

Nautilus peregrinus and assigns the species to Paranautilus. "Solenochilus" mokouensis Yin from the 

Penchi series of North China is also tentatively assigned to this genus. Yin's description of this species 

is very incomplete and his illustrations do not aid 

greatly in diagnosing the characteristics of this species. 

Paranautilus mokouensis is not as compressed as Paranautilus peregrinus but is a much larger shell—in

232820—53———6

fact, if the generic assignment is correct, it is the largest 

species of Paranautilus known, measuring more than 

20 cm in diameter.

The various species of Paranautilus show a lar^e 

variation in the shape of the conch (text fig. 35).

Variation in the shape of the whorls of 12 species of Paratoautilus, 

expressed as percent of the height to the width of the whorl

Species

Percent 

of height 

to width

._______-___._- 72

_______________ 76

_______________ 84

._______--_____ 84

.-_______-_____ 92

_______________ 92

.-_____-_-___._ 106

P. bambanagensis ------ _____________________ 113

P. sundaicus - ______________________________ 120

P. modestUiS--,. ---------------------------- 148

P. meridianus------------------------------ 157

P. peregrinus------------------------------- 165

P. multicameratus. 

P. tommasi______

P. anisi- ________

P. brembanus - _ _ _ _

i• sirTyioftyif — — — — -. — -.

P. indifferens-----

P. cassis--------.

Within the Triassic there appears to be a correlation of 

the percentage of height to width of whorl with geologic 

age. In general those species with compressed conchs 

and high percentages are confined to the Ladinian and 

Anisian. The high percentage for Paranautilus peregrinus may be due to error hi measurement of Waagen's 

crushed specimen. Variations in the shape of the 

conch itself can best be studied by referring to figure 35.

Paranautilus seems to show affinities with only one 

genus of Permian nautiloids, Liroceras of the family 

Liroceratidae. Liroceras has a globular rounded conch, 

deep, narrow umbilicus, and straight or very simple 

suture. The conch is in general much more depressed 

than in Paranautilus. However, the Triassic specks 

of Paranautilus appear to show a trend towards a mc^e 

compressed conch and if Liroceras is actually the 

ancestral form it fits into this evolutionary trerd. 

There are few other distinct and important differences 

between Liroceras and Paranautilus. Umbilical plugs 

are common in species of both genera. The sutures 

are, likewise, simple and have various minor inflections. 

Liroceras greenei has a shallow lateral lobe, L. obsoletum 

has a broad shallow dorsal lobe, L. liratum has a slight 

ventral lobe, and L. globulare may have an obscure 

ventral saddle. In Paranautilus the suture generally 

shows a weak ventral saddle and a broad shallow lateral 

lobe. However, shallow ventral lobes are present in 

Paranautilus meridianus, P. brembanus, P. cf . sundaicus, 

and possibly in P. bambanagensis. Neither of these 

two genera possess an annular lobe. The position of 

the siphuncle is varied hi both genera.

Paranautilus shows general affinities with the otl ^r 

genera in the Liroceratidae but these genera hsve
70 AMERICAN TRIASSIC COILED NAUTILOIDS

FIGURE 35.—Cross sections of the conch of A, Paranavtilus modestus (Mojsisovics) 1873, pi. 15, flg. 2b, Diameter 70 mm; B, SihyUrniavtUus pertumidut (Arthaber)*' S96, pi. 3,

P. simonyi (Hauer), the genotype of ParanautUus, after Mojsisovics 1902, pi. 1, fig. 2b, Diameter 76 mm.
PARANAUTILIDAE 

Distribution of species of the genus Paranautilus

71

Species

Paranautilus anisi (Arthaber) 1896. _ - -

P. arcestiformis Diener 1908 _ _ _ _

P. bambanagensis (Mojsisovics) 1896-

P. brembanus (Mojsisovics) 1882____ _

P. bullocki Diener 1907__------_--___ ___________

P. cassis Kieslinger 1924_ __ _ _ __ ____

P. indifferens (Hauer) 1892 __ ___________________

P. kashmiricus Diener 1913- ____

P. modestus (Mojsisovics) 1873 _ _ _

P.? mokouensis (Yin) 1933. _ _ _ _ _ _

P. multicameratus (Gabb) 1864- . . _ _

P.? peregrinus (Waagen) 1879. __

P. simonyi (Hauer) 1849___-

P. subbambanaqensis (Krumbeck) 1913

P. sundaicus Welter 1914_ _---_____

P. tommasi (Airaghi) 1902

Stratigraphic distribution

_ _ _ do -_- - -- ____'_

Triassic (Karnian)__ _____ ______ -__

Triassic (upper) - -

_____do _ _ ___ ________-_________-__----_-_

np-piQaa-Srt riiTyt"_ai'\

Triassic (Norian)__-_- _ _ _ __ - _

Permian (Penchi series)

Triassic (Anisian) ____ _ __ _ _ _ _

Permian (Middle Productus limestone)-

Triassic (Muschelkalk) ______

_ — _do— — — -_-- ------------------_----_

Triassic (Ladinian) _ _

Geographic distribution

Alps.

Himalayas, India.

Do.

Alps.

Himalayas, India.

Timor.

Yugoslavia.

Himalayas, India.

Timor.

Alps.

China.

Nevada.

Salt Range, Pakistan.

Germany.

Alps.

Indonesia, Iran.

Timor.

individual specializations that probably preclude considering them ancestral to Paranautilus.

Paranautilus is widely distributed in Eurasia and 

narrowly hi North America. There are two Permian 

species tentatively assigned to this genus. The range 

of Paranautilus in the Triassic is Anisian to Norian. 

Only two species are known from the North America, 

the remaining species are from Triassic areas within 

the Tethyian geosyncline.

Paranautilus multicameratus (Gabb) 

Plate 14, figures 7, 8

1864. Nautilus multicameratus Gabb, Geol. Surv. California, 

Paleontology, vol. 1, p. 20, pi. 3, figs. 4, 5.

1914. Paranautilus multicameratui> (Gabb). Smith, U. S. Geol. 

Survey Prof. Paper 83, p. 143, pi. 16, figs. 4, 5 (not pi. 

95, figs. 3, 4).

The description of the holotype by Gabb is as follows:

Shell broad, subglobose; whorls deeply embracing; sides 

compressed and rapidly converging; dorsum broadly grooved; 

umbilicus apparently quite small, partially obliterated in the 

specimen. Septa numerous, crowded, arching forward on the 

sides, and curving slightly backwards on the back. Siphuncle 

unusually large. Surface marked by revolving, somewhat 

irregular elevated lines.

The holotype was not available for study, but, Gabb's 

original description and figures of this species are sufficient to show the main characters. It is not even closely 

similar to the specimen placed in this species by Smith 

(1914, pi. 95, figs. 3, 4). Paranautilus multicameratus is 

unique in having a broad ventral groove and some 

ornamentation. Smith's specimen has a very rapidly 

expanded smooth conch and is made the holotype of a 

new species, Paranautilus smithi n. sp.

Occurrence.—"A single specimen was found by Mr. 

R. Hamfray at Dun Glen, near the Auld Lang Syne

Mine, Sierra District, Humboldt County, Nevr.da 

Territory." (Gabb, p. 20, 1864.) 

Holotype.—Location unknown.

Paranautilus smithi n. sp. 

Plate 4, figs. 11, 12; pi. 8, figures 12, 13; text figure 36

1914. Paranautilus multicameratua (Gabb). Smith, U. S. G<?ol. 

Survey Prof. Paper 83, p. 143, pi. 95, figs. 3, 4.

The specimen assigned by Smith (1914) to Gabb's 

species does not seem to be conspecific. This specimen 

(and holotype) measures 102 mm in diameter, 66.5 r>m 

in height of the most adoral part of the last whorl, 

and 77 mm in width. The conch is globose, involute, 

and rapidly expanding. The venter is flattened and 

grades imperceptably onto broad rounded ventral 

shoulders. The flanks are also broadly rounded, convergent towards the venter (text fig. 36). The living 

chamber measures 115 mm along the venter. The 

suture is almost straight over the venter and has a very 

shallow lateral lobe. No surface markings are present. 

The siphuncle is not visible.

Three conspecific specimens are available for study. 

One large one is complete, but somewhat distorted. 

An immature specimen (pi. 4, figs. 12, 13) that consists 

of the phragomcone only agrees hi all essential features 

with the holotype.

This species is very similar to Paranautilus mokouensis Yin from the Penchi series of North China. T 9 

involute globose conch with the slight flattening of the 

venter of the last whorl shows strong affinities between 

these two species. Paranautilus smithi differs from 

P. multicameratus in lacking the ventral furrow and the 

surface ornamentation.

Occurrence.—Holotype and figured plesiotype from 

Middle Triassic Daonella dubia zone, Ceratites tnno-
72 AMERICAN TRIASSIC COILED NAUTILOIDS

FIGURE 36.—Diagrammatic cross section of holotype of Paranautilus smithi n. sp. 

(U.S.N.M. 7445) from Damella dubia zone of Star Peak formation, Fossil Hill, West 

Humboldt Range, Nevada, X I.

dosus subzone, of the Buena Vista district; and of 

Fossil Hill, South Fork of American Canyon, 4 miles 

south of Fitting Post Office (formerly Foltz), West 

Humboldt Range, Nevada. Unfigured plesio types 

from Daonella dubia zone north side of South Canyon, 

New Pass, Desatoya Range, Lander County, Nevada. 

Types.—Holotype, U.S.N.M. 74445; figured plesiotype, U.S.N.M. 32644; unfigured plesiotypes, U.S.N.M. 

107096 and 107097.

Paranautilus sp. 

Plate 8, figures 8, 9

One small immature specimen, consisting of only one 

half of the conch, is available from the Upper Triassic 

Laming (?) formation, Shoshone Mountains, Nevada. 

It is 33 mm in diameter, 23 mm in maximum width of 

whorl, and 17 mm in height. The specimen is subglobular, and appears to represent one half of the first 

and second volutions. The penultimate half whorl 

height and width are 10 and 16 mm respectively. The 

whorl at this point is broadly elliptical with a slight 

amount of flattening on the flanks. The whorl at the 

most adoral part of the conch shows a little more flattening of the flanks, grading to a broadly rounded ventrolateral region and to a smooth flatly rounded venter.

The umbilicus is small and deep, measuring 7 mm in 

diameter, 5 mm in depth. The umbilical shoulders are

sharply rounded and the umbilical wall descends almost 

vertically to the umbilical seam. The only surface 

markings on the test are delicate but distinct growth 

lines that extend essentially straight across the umbilical 

wall and flanks of the conch, and'form a brop,d deep 

sinus on the venter.

There are 16 septa in about half volution of the 

conch. A very small part (about 5 mm) of the living 

chamber is also present. The suture forms a very 

shallow ventral and lateral lobe, and it passer across 

the umbilical wall to the seam in a straight line. The 

siphuncle is not visible.

Remarks.—The only available specimen seems to 

represent an immature individual. The septa f.re relatively widely spaced and the distance between septa 

increases adorally. It is considered inadvisable to 

name a new species or to postulate its affinities on this 

specimen only.

Occurrence.—U.S.G.S. 11773, the label accompanying 

this specimen reads as follows: "North side of Union 

Canyon about 1% miles above its mouth. From Triassic limestone above contact with Volcanic Rocks. 

Shoshone Range, Tonopah Quadrangle, Nevada." 

This is presumably from the Luning formation (Karnian). Collected by Ferguson, Cathcart, Hei^s, and 

T. W. Stanton, July 6, 1923.

Figured plesiotype.—U.S.N.M. 107098.

Genus INDONAUTILUS Mojsisovics, 1902

Genotype: Nautilus kraffti Mojsisovics

The description of the genotype by Mojsisovics 

(1899, p. 122) is as follows:

This cast chambered throughout shows a great resemblance 

to Nautilus mesodicus, Hau., and has a considerably more concentrated growth. The perforation of the umbilicus, which in 

Nautilus mesodicus amounts to about 12 mm., is in th? present 

cast only 2 mm. There are about one and a half whorls at the 

diameter of 48 mm. Sharp edges are not yet present at the 

beginning of the last whorl, but they are formed in the course of 

the latter. The flattening and the individualisation of the external part occurs simultaneously with the appearance of marginal 

angles.

Siphuncle.—The position of the siphuncle is very d3ep, near 

the internal part.

Sutures.—An internal lobe is not present.

The development of the flat external lobe occuping the breadth 

of the external part goes hand in hand with the appearance of the 

marginal angles. There is a broad flat lateral lobe at the sides 

as in Nautilus mesodicus. The crowded condition of the septa, 

which considerably increases towards the anterior fractured 

edge, is still remarkable. From this increasing shortness of the 

distance of the septa it must be concluded that the spec;men was 

broken off near the beginning of the body chamber.

(pi. 18, figs. 11, 12; text fig. 35).

When Mojsisovics (1902, p. 205) proposed tl e genus 

Indonautilus he made the following comment?:

Ich habe in meiner Arbeit iiber die obertriadischei Cepha-
PARANAUTILIDAE 73

lopoden des Himalaya (1896, p. 672) unter der Bezeichnung 

Nautilus ind. ex. aff. mesodici einen Typus beschrieben, welcher 

bisher in der europaischen Trias noch nicht beobachtet wurde. 

Gleichwohl erscheint es aber angezeigt, diesen Typus hier zu 

erwahnen und fur denselben sowohl eine eigene subgenerische 

Bezeichnung vorzuschlagen, als auch einen Artnamen nachzutragen. Ich wahle als sochen J. Kraffti.

Indonautilus unterscheidet sich von Grypoceras, mit welchem 

sonst die grosste Uebereinstimmung besteht, durch das Fehlen 

eines Internlobus und dies diirfte wohl darauf hindeuten, dass 

Indonautilus in genetischer Beiziehung zunachst an Paranautilus 

anzureihen sein diirfte. Die kantige Abplattung der Externseite 

und die hiermit gleichzeitige Herausbildung eines Externlobus 

kennzeichnen die gleiche Variationsrichtung, welche auch von 

Styrionautilus zu Clydonautilus fiihrt. Die grosse aussere 

Aehnlichkeit mit Grypoceras ware daher als eine Convergenzerscheinung aufzufassen.

Mojsisovics' comments can be summarized as follows:

Nautilus ind. ex. aff. mesodici which I have described from the 

Upper Triassic of the Himalayas is now considered as a distinct 

new form which I designate as Indonautilus kraffti.

Indonautilus differs from Grypoceras, with which it is closely 

similar, in the absence of an annular lobe, and in which it is 

similar to Paranautilus. The angular, flattened venter and the 

character of the ventral lobe are similar to variations found in 

the Styrionautilus-Clydonautilus line. The great similarity with 

Grypoceras must be due to convergence.

Two species have been referred to the genus: Indonautilus kraffti and /. subbambanagensis. The latter 

species does not appear to be properly classified and 

is referred to the genus Paranautilus. It is very closely 

related to Paranautilus bambanagensis. Indonautilus 

superficially resembles Grypoceras in general shape of 

the conch, but is much more involute, has a slightly 

different suture, and no annular lobe. It appears to 

be most closely related to and derived from Paranautilus. Monotypic genera such as Indonautilus, in 

which data are insufficient, are difficult to classify and 

at best can be only tentatively assigned to a family. 

In this report Indonauiilus is considered a late evolutionary development out of Paranautilus. The genotype species comes from Norian beds of the Himalayan 

region. Jaworski (1915, p. 131-132) described a specimen from Norian rocks on the Island of Misol that he 

believes is related to Indonautilus kraffti.

Genus Sibyllonautilus Diener, 1915

Genotype: Nautilus sibyllae Mojsisovics

In Part 8 of the Fossilium Catalogus, "Cephalopoda 

Triadica," Diener 1915 erected two new genera, Sybyllonautilus and Tumidonautilus (Genotype, Nautilus 

pertumidus Arthaber). Both genera include tightly 

coiled nautiloids that show a great expansion in the 

width of the whorl in mature specimens. Tumidonautilus differs from Sybyllonautilus essentially only 

in the greater expansion of the conch. The illustrations of Sibyllonautilus sibyllae and S. liardensis show

that not much of the living chamber is preserved in 

these specimens, which may explain the differences in 

the whorl expansion between these two genera. Nautilus sibyllae and N. pertumidus appear so closely rela ted 

and similar that they snould be brought together into 

one genus. Because Sibyllonautilus was listed first in 

Part 8 of the Fossilium Catalogus, Tumidonautilus is 

suppressed and its one species place in Sibyllonautilus. 

Diener gave no description of Sibyllonautilus, but 

the description of the type species is quoted here in 

full (Mojsisovics, 1886, p. 100):

Die sehr rasch in die Breite wachsende Art besteht in dem 

abgebildeten Exemplare bios aus anderthalb Umgangen. "Der 

gewolbte, nicht abgeplattete Externtheil trennt sich kaum von 

den leicht gewolbten Seitentheilen. Der Nabelrand ist auf dem 

ausseren, noch durchaus gekammerten Umgange deutlich r^arkirt. Die hohe Nabelwand fallt von demselben in schrager 

Flache zum tiefen, trichteformigen Nabel ab. Die Involution 

umfasst die halbe Windungshohe der umhiillten Windun7:en. 

Die grosste Dicke der Windungen fallt in die halbe Windungsl: ohe 

etwas ausserhalb des Nabelrandes.

Die Schale ist von kraftigen, eigenthumlich verlauferden 

Zuwachstreifen bedeckt. Auf den tiefen Sinus des Externtheiles folgt ein gegen vorne convexer Bogen am Rande zwischen 

Seiten- und Externtheil. Hierauf biegen sich die Streifen 

abermals zu einem kleinen Sinus zuriick, wahrend dieselben auf 

dem Nabelrande neuerdings einen gegen vorne convexen Bogen 

bilden und auf der Nabelwand ziemlich gerade zur Naht sich 

abwarts senken. Dieser, insbesondere durch den auf den 

Nabelrand fallenden zweiten Bogen bemerkenswerthe Verlauf 

der Zuwachsstreifen findet sich unter den europaischen Triasnautilen wieder bei Nautilus Suessi aus den Hallstatter Kalken, 

sowie man durch denselben auch an den Mundrand des perrnischen Nautilus cornutus Golovinski erinnert wird.

Loben. Gedrangt stehende Kammerwande, welche mit kaum 

merklichem Sinus tiber den Externtheil ziehen und auf den 

Seiten einen gleichfalls nur sehr schwachen, seichten Laterallobus 

bilden. Internlobus vorhanden.

Sipho. Konnte nicht beobachtet werden.

Dimensionen: Durchmesser—73 mm., Hohe derr letzten 

Windung—43 mm, Dicke—59 mm., Nabelweite—9 mm, Perforation—2 mm.

Mojsisovics' description of Nautilus sibyllae can be 

summarized as follows:

The conch is rapidly expanding, venter broadly arched and 

hardly separated from the rounded whorl sides. The umbilical 

shoulder is very distinct and the high umbilical wall slopes 

gradually to a deep funnel shaped umbilicus. The conch is 

involute, the whorls embracing about one-half of the preceding 

whorls. The shell has strong growth lines that form a deep 

sinus on the venter and a shallow sinus on the whorl sides. The 

suture is almost straight across the venter and with a shallow 

lateral lobe. An annular lobe is present. The position of the 

siphuncle is not known.

Mojsisovics (1902, p. 235) believed that Sibyllonautilus sibyllae occupied a more or less isolated position, 

but he pointed similarity to Nautilus cornutus.

Sibyllonautilus pertumidus is one of the most unusual 

of all the Triassic nautiloids. No other Triarsic
74 AMERICAN TRIASSIC COILED NAUTILOIDS

nautiloid shows such rapid expansion of the living 

chamber; Arthaber's specimen (1896, p. 42) measured 

75 mm in diameter, 40 mm for the height of the last 

whorl and 102 mm for the width of the last whorl 

(test fig. 35). The venter is flatly rounded on the 

early whorls, becoming arched on the living chamber. 

No distinct ventral shoulders are developed. The 

umbilical walls are steep, becoming arched where the 

whorls begin to expand rapidly. The whorls first 

begin their extraordinary expansion on the living 

chamber of a mature individual. The part of the living 

chamber preserved in Arthaber's specimen is one-third 

of a volution in length. The suture shows very shallow 

ventral and lateral lobes. An annular lobe is also 

present. The siphuncle is subcentral in position.

Arthaber recognized the unusual features of his 

species and thought it occupied a more or less isolated 

position among known Triassic nautiloid faunas but 

he did point out similarities to Nautilus tintoretti Mojsisovics and N. sibyllae Mojsisovics. However, Arthaber favored a possible relationship to N. cornutus 

Golovkinsky, which develops very long extended hornlike projections or rolls from the area of the umbilical 

shoulders. It was made the genotype of the genus 

Permonautilus Kruglov (1933), but Miller and Youngquist (1949, p. 120) suppressed Permonautilus as a 

synonym of Acanthonautilus Foord. The genotype of

Acanthonautilus is A. bispinosis Foord of the. Lower 

Carboniferous of Ireland. A. cornutus is from the 

Upper (?) Permian of Russia. SibyllonautUus differs 

from these two Paleozoic species in lacking the spinelike projections mentioned above.

Mojsisovics (1902, p. 235, footnote) suggested that 

the phragmocone of Nautilus pertumidus was very 

similar to Mojsvaroceras or Germanonautilus and that 

N. pertumidus could be considered an aberrant offshoot of Germanonautilus with subgeneric rank. It 

seems incorrect to place SibyllonautUus in the Tainoceratidae as suggested by Mojsisovics. SibyttonautUus 

does not have any type of ornamentation characteristic of the genera in that family. Likewise, with few 

exceptions, the genera of the Tainoceratidae are much 

more evolute than SibyllonautUus. The general shape 

of the conch and simplified suture ally SibyllonautUus 

with Paranautilus. The earliest representatives of 

SibyllonautUus appear in the Anisian. Parano,utUus is 

believed to be decended from Liroceras and SibyllonautUus, to represent an aberrant offshoot of Paranautilus, 

or possibly be a direct development from Liroceras. A 

genetic relationship between AcanthonautUus and SibyllonautUus seems unlikely. In the former genus the 

development of the extended horn-like project on from 

the area of the umbilical shoulder is considered an independent line of specialization.

Distribution of species of the genus Sibyllonautilus

Species

Sibyllonautilus fergusoni Kummel n. sp __. _ _ _ _

S. liardensis (Whiteaves) 1889 ___ ______ _ ______

S. pertumidus (Arthaber) 1896 _ __ _ _. _ ______

S. sibyllae (Mojsisovics) 1886____ ________________

Stratigraphic distribution

Triassic (Ladinian, Karnian) _ .__ ____ _ _

__-__do_______-_-_-_-__-__-___--_--_--__-__.

Geographic distribution

British Columbia.

Alps.

Spitzbergen.

Sibyllonautilus fergusoni n. sp. 

Flare 8, figures 10, 11; text figure 37

The Gabbs formation of Nevada has yielded two 

specimens that belong in the genus SibyllonautUus. 

One of these specimens is fairly well preserved and is 

septate throughout; the other is only a fragment of onethird volution and only the ventral part of the conch.

The holotype specimen is involute, subglobular, has 

a maximum diameter of 49 mm, a maximum width of 

65 mm, and height of the conch of about 30 mm. The 

conch is expanded orad very rapidly; height and width 

of the penultimate whorl are about 15 mm and 25 mm, 

respectively. The whorls are broadly rounded ventrally, showing no trace of a ventral shoulder, the flanks 

curve gradually to the venter (text fig. 37).

The umbilicus is very small and may be completely 

closed by successive whorls; the umbilical shoulders are 

sharply defined. The umbilical walls are flattened and

slope at a steep angle. No trace of surface markings is 

discernible.

The septa are only moderately close together and 

slope steeply adorally. The sutures are essentially 

straight, showing only a faint indication of ver tral and 

lateral lobes. The siphuncle is subcentral, ard closer 

to the dorsum than the venter.

Remarks.—The rate of expansion of the whorls in 

S. Jergusoni is much greater than that of S. liardensis 

or S. sibyllae but approaches that of S. pertumidus. 

However, in the latter species the great expansion of 

the whorls begins on the living chamber, in S. fergusoni 

the expansion is already very marked on the phragmocone. The umbilicus is much larger and the umbilical wall less steep in S. sibyllae. S. liardensis has a 

cross section more elliptical than that of S. Jergusoni. 

The species is named for H. G. Fergusson, who collected 

the specimens.
CLYDONAUTILIDAE 75

FIQUEE 37.—Diagrammatic cross section of holotype of SibyUonaviilusfergvAoni n. sp. 

(U.S.N.M. 107099) from Gabbs formation Gabbs Valley Range, Nevada, X 1.

Occurrence.—U.S.G.S. 13420, Gabbs formation, 2% 

miles north of the mouth of New York Canyon, Gabbs 

Valley Range, Nevada.

Types—U.S.N.M. 107099 (holotype), 108000 (paratype).

Sibyllonautilus liardensis (Whiteaves)

Plate 14, figures 9, 10

1889. Nautilus liardensis (Whiteaves), Contr. Canadian Paleontology, vol. 1, pt. 2, p. 137, pi. 18. figs. 1, la.

1927. Paranautilus liardensis (Whiteaves). Smith, U. S. Geol. 

Prof. Paper 141, p. 102, pi. 107, figs. 1, 2.

The description of the species by Whiteaves is as 

follows:

Shell broad, subglobose, but deeply though rather narrowly 

umbilicated: maximum breadth of the aperture about equal to 

the entire length, as measured from the centre of the outer lip 

to a corresonding point on the periphery of the opposite side. 

Volutions very closely embracing, the inner ones almost completely covered, the outer one increasing rapidly in size, but expanding much more rapidly in a lateral than in a dorso-ventral 

direction: periphery somewhat flattened, but probably abnormally so: sides and umbilical margin both rounded, the latter 

not at all angular: aperture a little more than twice as broad 

as high, transversely subreniform, or transversely and broadly 

elliptical but shallowly emarginate in the centre of the base by 

the encroachment of the preceeding volution.

Septa somewhat closely approximated, their average distance 

apart on the periphery, where their margins are nearly straight, 

being about six millimetres. Position of the siphuncle unknown.

Surface apparently almost smooth, and marked only by transverse striae of growth.

Dimensions of the only specimen collected: maximum length, 

fifty-seven millimetres; maximum breadth at the aperture, where 

the shell is broadest, fifty-eight mm; height of aperture in the 

centre, twenty-seven mm.

Liard River, about twenty-five miles below Devil's Portage, 

R. G. McConnell, 1887: a slightly distorted cast of the interior 

of the shell, with small portions of the test preserved, but with 

the greater portion of the chamber of habitation broken off. The 

number of septa whose margins are visible in this specimen is 

twenty-one, and the portion of the body chamber that remains 

is about three-quarters of an inch in length.

This shell appears to bear such a close resemblance to the 

Nautilus sibyllae of Mojsisovics, from the Trias of Spitsbergen 

in almost every respect, that it may possibly prove to be oily a 

local variety of that species. Still in the figures of N. sibyllae 

the umbilical margin is represented as rather distinctly angular, 

whereas that of N". liardensis is very regularly rounded.

Family CLYDONAUTIUDAE Hyatt, 1900

Hyatt (1900, p. 521-522) included in this family, a 

wide range of forms from the Mesozoic and Cenczoic 

eras—Clymenonautilus, Clydonautilus f Hercoglossa, 

Pseudonautilus, and Aturia. Mojsisovics (1902) greatly 

restricted this family to Triassic genera, and added 

several new ones. Mojsisovics placed in it Paranautilus 

Indonautilus, Styrionautilus, Clydonautilus, Pr^dydonautilus, and Gonionautilus. Kummel (1950) placed 

Paranautilus and IndonautUus in the ParanautilHae, 

and Gonionautilus, in the Gonionautilidae. The 

Clydonautilidae are now thought to include Clydono,utilus, Proclydonautilus, Styrionautilus, Cosmonaut'''lus, 

and Callaionautilus. Spath (1927b, p. 24) suggested 

that Callaionautilus does not belong in the Clydonr.utilidae and, although he gave no reason for his proposal, 

it may well be valid. Callaionautilus is a monot^pic 

genus known only from Norian beds of Timor ard is 

very difficult to classify, as are most more or less 

isolated monotypic forms. The writer is leaving Cattaionautilus in the Clydonautilidae on the basis of its e^rly 

ontogenetic development, which is so similar to that 

of Proclydonautilus and Cosmonautilus. Kieslinger 

(1924, p. 133) in fact, suppressed his new genus Callaionautilus along with Cosmonautilus in a supplement 

believing them to lie within the sphere of variation of 

Proclydonautilus.

The Clydonautilidae as here interpreted form a very 

closely integrated group. The family includes Tria^sic 

nautiloids with involute subglobular to compressed 

conchs and highly differentiated sutures (text figs. 

39-41). One of the most distinctive features of the 

genera in this family is the suture pattern, which forms 

the best evidence for interpreting phylogenetic relationships within the family. Variation in the shape of 

the conch is rather great in all of the genera but the 

basic plan of the suture remains constant. In all the 

genera there is a large, deep lateral lobe and the main 

difference between the various groups lies in the cl aracter of the suture in the ventral region of the cor oh. 

In Styrionautilus the suture is straight over the venter, 

in Clydonautilus the ventral lobe is divided by a small 

saddle, in Proclydonautilus there is only a large ventral 

lobe. Cosmonautilus and Callaionautilus are differentiated on features of ornamentation developed at seme 

stage in their ontogeny and have a suture similar to 

that of Proclydonautilus.
76 AMERICAN TRIASSIC COILED NATJTILOIDS

J

FIGURE 38.—Cross sections of the conch of A, Clydonawtil'us salisburgensis (Hauer), after Mojsisovics, 1902, pi. 12, fig. Ib, Diameter 184 mm; B, C. compressus Welter 1914, 

p. 217, fig. 92, Diameter 65 mm; C, C. salisburgensis (Hauer), after Kieslinger, 1924, pi. 3, fi?. Ib, Diameter 89 mm; D, Gonionautilus securis (Dittmar),tln genotype of 

Oonionavtilus, after Mojsisovics, 1902, pi. 1, fig. Ib, Diameter 110 mm; E, C. biangularis Mojsisovics 1896, pi. 22, fig, 2b, Diameter 83 mm; F, C. salisburgensis timorensis 

Welter 1914, p. 222, fig. 99, Diameter 194 mm; G, C. glaber Kieslinger 1924, pi. 2, fig. 2b, Diameter 55 mm; H, C. quenstedti (Hauer), after Mojsisovics, 1873, pi. 9, fig. Ib, 

Diameter 290 mm; /, Styrionauti lus sauperi (Hauer), after Mojsisovics, 1873, pi. 15, fig. Ib, Diameter 122 mm; J, S. discoidalis (Welter) 1914, pi. 31, fig. 9 Diameter 50 

mm; K, S. styriacus Mojsisovics 1873, pi. 14, fig. 7b, Diameter 74mm, the genotype of Styrionautilus.
CLYDONAUTILIDAE 77

FIGURE 39.—Diagrammatic cross section and representation of suture of StyrionautUus sp. (U.S.N.M. 108001) from Middle Triassic, South Canyon, New Pass, 

Desatoya Range, Nev., both X 1.

Geographically the genera in this family are world 

wide in their distribution. Cosmonautilus and Callaionautilus are more closely limited in their distribution 

than Styrionautilus, Clydonautilus and Proclydonautilus. StryionautUus ranges from the Anisian to the 

Norian, Clydonautilus fpom Ladinian to Norian, 

ProclydonautUus and Cosmonautilus from Karnian to 

Norian, and Callaionautilus is known only from the 

Norian.

PHYIOGENY

The dominant evolutionary trends within the family 

Clydonautilidae are the increasing sinuosity and the 

modifications of the suture pattern. The conch for 

the most part remained smooth, involute, and subglobular in shape. Minor elements of ornamentation 

are present such as the nodes on the early whorls of 

Cosmonautilus and Callaionautilus, but these features 

have no phylogenetic significance and are merely 

abberrant mutations superimposed on a basic conch 

pattern. The family reveals no distinct evolutionary 

trend in the shape of the conch. The affinities of the 

various genera and their interrelationships can best be 

studied on the basis of the evolution in the suture 

pattern (text fig. 41). The complexity of the suture of 

the Triassic Clydonautilidae is rivaled only by that 

shown in such Tertiary nautiloids as Aturia, Aturoidea, 

and possibly Hercoglossa (see Miller, fig. 7, 1947).

Among late Paleozoic nautiloids only "Aganides" 

bitauniensis Haniel (1915) from the Permian of Timor 

has a suture rivaling the complexity of that in the 

Clydonautilidae. The conch form places this species 

in the Grypoceratidae. The suture, however, is very 

uncommon for late Paleozoic nautiloids and is similar

only to the Late Triassic Clydonautilidae. This species 

should be placed in a separate new genus.

The family seems to stem from a paranautilid stock 

in the Ladinian. ParanautUus has a very simple 

globular conch with a nearly straight suture. On this 

basic conch and sutural pattern the genera of the Clydonautilidae were derived either directly or indirectly. 

Mojsisovics (1902, p. 206) indicated the great similarity 

in shape of the conch of StryionautUus to ParanautUus 

anisi. Styrionautilus is characterized by a suture 

passing straight over the venter, and a deep lateral 

lobe. Forms such as ParanautUus meridianus with a 

deep but very broad lateral lobe and ParanautUus 

sundaicus with a shallower lateral lobe and a ventral 

saddle seem to be somewhat transitional, at least in 

their suture pattern, to StryrionautUus. Five species 

of Styrionautilus are recognized, one from the Ladinir.n 

and the remaining species from the Karnian. Styrionautilus shows more similarity to its descendants in 

the shape of the conch than it does to the ancestral 

ParanautUus.

ProclydonautUus, an involute subglobose nautiloid, 

has a small ventral lobe dividing the ventral saddle. 

Forms such as Styrionautilus sauperi have such a 

ventral lobe developed on the last few septa and are 

believed to indicate clearly the genetic relationships of 

Styrionautilus and ProclydonautUus. Closely related 

to Proclydonautilus are two groups of nautiloids that 

develop features of ornamentation during at least part 

of their ontogeny on a Proclydonautilid conch and at tl ^ 

same time maintain a suture pattern very similar to 

that of the parent stock. The first, Cosmonautilus, 

develops nodes on the ventral shoulders, usually only 

on the inner whorls, and at maturity has a completely 

smooth conch very difficult to differentiate from typical 

Proclydonautilus. The second genus, Callaionautilus, 

has an ontogeny similar to that of Cosmonautilus in tl ^ 

formation of nodes on the ventral shoulders, but this 

phase grades into one in which the conch is ovoid in 

shape, smooth, and with a ventral nodose keel. Both 

of these genera are thought to be aberrant evolutionary 

offshoots, and the ornamentation consists of coenogenetic characters with no phylogenetic significance. 

ProclydonautUus and Cosmonautilus range through tl ^ 

Karnian and Norian, Callaionautilus is known only 

from the Norian.

From ParanautUus evolved the genus Clydonautilus, 

which has a suture pattern similar to that of ProclydonautUus except that a small saddle divides the ventral 

lobe. These two genera lived side by side throughout tl o 

Karnian and Norian and seem to represent two closeT y 

related but independent lines developing out of Paranautilus.
78 AMERICAN TRIASSIC COILED NAUTILOIDS

j

FIGUEE 40.—Cross sections of the conch of A, Prodydonautilus gasteroptycw (Dittmar), after Mojsisovics 1873, pi. 10, fig. Ib, Diameter 100 mm; 

B, P. ernesti Diener 1919, p. 773, flg. 14, Diameter 73 mm; C, P. singularis Welter, after Kieslinger, 1924, p. 78, flg. 11, Diameter 106mm; D, 

P. griesbachi Mojsisovics, 1896, pi. 22, flg. Ib, Diameter 87 mm, the genotype of ProdydonaiUilus; E, P. ermouii Diener 1919, p. 775, flg. 16, 

Diameter 117 mm; F, P. triadicus Mojsisovics, after Diener 1919, p. 766, flg. 6a, Diameter 138 mm; G, P. buddhaicus Diener 1919, p. 769, flg. 9, 

Diameter 113 mm; H, P. spirolobus (Dittmar), after Mojsisovics 1902, pi. 10, flg. 3b, Diameter 73 mm; I, P. tuvalicus Diener 1919, p. 772, flg. 

12, Diameter 150 mm; J, P. inflatus Welter 1914, p. 212, flg. 83, Diameter 94 mm.
J'lGURE 41.—Diagrammatic representation of sutures of A, Paranautilus meridianus Welter, 1914, pi. 31, flg. 6, XI; B, Paranautilus sundakusWetter, 1914, pi. 31, flg. 3, XI; 

C, Styrionautilus discoidalis (Welter) 1914, pi. 31, flg. 8, X2.34; J), Styrionautilus sauperi (Hauer), after Mojsisovics, 1902, p. 209, flg. 6, X0.8., a very late stage suture; E, 

Prodydonautilug ernesti Diener, 1919, p. 774, flg. 15, X1.6; F, Proclydonautilus goniatttes (Hauer), after Kieslinger, 1924, p. 77, flg. 10, X0.81; Q, Proclydonautilus griesbachi (Mojsisovics), 1896, pi. 22, flg. Ic, Xl.l, the genotype of Proclydonautilus; H, Proclydonautilut natosoni McLearn, 1946, pi. 2, flg. 2, X1.4; I, Callaionaut'lus 

turgidus Kieslinger, 1924, p. 94, flg. 21, X1.46; J, Cosmonautilus ditteri Hyatt and Smith, after Smith, 1927, pi. 54, flg. 2, X0.6; K, Clydonautilus biangularis Mojsisovics, 

1896, pi. 22, flg. 2c, Xl.l; L, Clydonautilus salisburgensis (Hauer), after Kieslinger, 1924, p. 68, flg. 6, XI; M, ClydonautilusnoricusMo]sisovics, 1873, pi. 11, flg. 2, XO 23; 

N. Clydonautilus quenstedti (Hauer), after Mojsisovics, 1873, pi. 9, flg. 3, X0.28.
80 AMERICAN TRIASSIC COILED NAUTILOIDS

Genus STYRIONAUTILUS Mojsisovics, 1902 

Genotype: Nautilus styriacus Mojsisovics

Mojsisovics (1902, p. 206) diagnosed his genus as 

follows:

Involute globose Gehause mit abgerundeter Eternseite. Geradlinig den Externtheil ubersetzender Externsattel, tiefer spitz 

gerundeter Laterallobus, grosser Lateralsattel, welcher sich aus 

dem kleinen Umbilicalsattel von Paranautilus entwickelt hat, 

und tiefer Nachtlobus. Kein Internlobus. Sipho subcentral. 

(pi. 18, figs. 9, 10).

Mojsisovics' diagnosis can be summarized as follows:

Conch globose, involute, with rounded venter. Ventral saddle 

straight, lateral lobe deep, acutely rounded, lateral saddle 

larger and developed from the small umbilical saddle of Paranautilus. No- annular lobe. Siphuncle subcentral.

The general shape of the conch of Styrionautilus is 

very similar to that of Proclydonautilus and Clydonautilus. It differs mainly in that the sutures form a 

straight line over the venter (text fig. 41). Mojsisovics 

pointed out the great similarity to Paranautilus anisi 

and believed Styrionautilus to be derived from Paranautilus and to be the forerunner of Proclydonautilus.

The evolutionary development was confined mainly to 

changes in the suture and especially in th Q. ventral 

saddle. Styrionautilus sauperi has a small lobe developed in the last few septa and is thought to be a form 

transitional to typical Proclydonautilus. No known 

forms show a transition between the shallow lobes 

of Paranautilus to the deep lobes of Styrionautilus. 

There are great differences in shape of the conch 

among the species of Styrionautilus. The genotype has 

an involute subglobular conch with an arched venter 

and rounded flanks (see text fig. 38). S. sauperi has a 

more compressed conch with a flattened venter and 

S. discoidalis is a very compressed form with a very 

narrow venter. All the species, however, agree in 

their suture pattern, that of a straight ventral saddle 

with deep lateral lobes. This relationship reflects the 

general evolutionary pattern of the family Clydonautilidae—the suture lines of the various genera are 

fairly constant in form, but the variation in shape of the 

whorl section between the species may be great. 

Proclydonautilus illustrates this relationship even more 

strikingly than Styrionautilus.

Distribution of species of the genus Styrionautilus

Species

Styrionautilus discoidalis (Welter) 1914. ___ ___

S. occidentalis (Tornquist) 1898_

S. sauperi (Hauer) 1846 _ __ ___

S. styriacus (Mojsisovics) _

S.BP- -----------------------------------------

Stratigraphic distribution

Triassic (upper) _ _______

_____do______________ _ ________________---.

Geographic distribution

Timor.

Alps.

Nevada.

Styrionautilus sp. 

Plate 15, figure 16; text figure 39

One fragmentary specimen consisting of two camerae 

can confidently be placed in this genus. The specimen 

is from the Middle Triassic, Desatoya Range, Nevada. 

The camerae measure 43 mm in height and approximately 44 mm in width near the umbilical shoulders. 

The venter is 10 mm wide and flattened, the flanks are 

also flattened to broadly arched, and converge towards 

the venter. The ventral shoulders are distinct and 

rounded (text fig. 39). The siphuncle lies closer to the 

dorsum than to the venter. The specimen is characterized by its suture, which traces a straight line across 

the venter, forms a deep, broad lateral lobe, and passes 

to a small saddle near the umbilical shoulder. The 

nature of the suture pattern and shape of the conch 

clearly place this specimen in Styrionautilus, and the 

shape of the whorl section suggests affinities to 

Styrionautilus sauperi.

Occurrence.—The specimen was collected by F. N. 

Johnston and the label with the specimen reads "Middle 

Triassic, South Canyon, New Pass, Desatoya Range, 

Nevada." This is presumably from bed 2b of Johnston's generalized Stratigraphic section (1941, p. 448) 

Daonella zone of late Anisian age.

Figured specimen.—U. S. N. M. 108001

Genus PROCLYDONAUTILTIS Mojsisovics, 1802

Genotype: Nautilus griesbachi Mojsisovics

When Mojsisovics first described this genur, he considered the group a subgenus of ClydonautUus which, 

however, has a small median saddle dividing the ventral 

lobe. The taxonomic status of Proclydonavtilus has 

been changed several times. Smith (1904, p. 401) 

raised Proclydonautilus to full generic rank, and Hyatt 

and Smith (1905, p. 205) Welter (1914, p. 2C Q ), Kieslinger (1924, p. 66) and Smith (1927, p. 102) concurred. 

Diener (1919, p. 766) maintained the classification first 

proposed by Mojsisovics.

Proclydonautilus may be briefly described as follows: 

The conch is nautiliconic and subglobular to compressed 

(text fig. 40), the whorls are generally rounded although 

the flanks may be somewhat flattened and converge 

towards the venter. The venter is broadly rounded to 

flattened, with well defined ventral shoulders. The 

umbilicus is small, umbilical shoulders well rounded.
CLYDON AUTILIDAE 81

Conch is smooth. The suture consists of a broad, 

shallow to deep ventral lobe dividing a large ventral 

saddle. The flanks are occupied by a large lateral lobe 

with a smaller lateral saddle and a second lateral lobe. 

Generally no annular lobe is present. However. 

Welter (1914, p. 213) described and illustrated specimens of Proclydonautilus (?) gasteroptychus timorensis 

that have an annular lobe but the external suture is 

of a typical proclydonautilid type. The siphuncle is 

central in position.

The writer follows Mojsisovics (1902, p. 206) in 

deriving Proclydonautilus from Styrionautilus. The 

only essential difference between these two genera is 

that the ventral saddle of Styrionautilus passes over

the venter in a straight line. Styrionautilus sauperi 

develops a small lobe on the ventral saddle in the ve~y 

late septa and seems to be a form transitional to 

typical Proclydonautilus.

Closely related to Proclydonautilus are CosmonautUus 

Hyatt and Smith and CattaionautUus Kieslinger. 

Kieslinger (1924, p. 63) suppressed CosmonautUus and 

placed all the species assigned to it in Clydonautilus 

and Proclydonautilus. He also suppressed Callaionautilus (Kieslinger, 1924, p. 133-138). The writer considers CallaionautUus and CosmonautUus valid genera 

closely related to Proclydonautilus. These three close^ 

related taxonomic groups show a great diversity in the 

form of the conch.

Distribution of species of the genus Proclydonautilus

Species Stratigraphic distribution Geographic distribution

Proclydonautilus angustus Kieslinger 1924. 

P. buddhaicus Diener 1908-_____________

P.? ermolli Diener 1919____--___-_____

P. gasteroptychus (Dittmar) 1866________

P. gasteroptychus timorensis Welter 1914. _ 

P. goniatites (Hauer) 1849_____________

P. griesbachi Mojsisovics 1896_______

P. hessi (Smith) 1927__________

P. inflatus Welter 1914_______________ __

P. mandevillei (Marschall) 1909__ ________

P. natosini McLearn 1946_______________

P. singularis Welter 1914_ ______________

B. spirolobus (Dittmar) 1866-___________

P. squawensis Kummel n. sp____________

P. stantoni Smith 1927___ _____________

P. triadicus (Mojsisovics) 1873__________

Triassic (upper)___ 

Triassic (Karnian).

Triassic (Norian)_________

Triassie (upper)__________

Triassic (Karnian)________

Triassic (Karnian, Norian). 

Triassic (Karnian)________

Triassic (upper)__________

Triassic (Norian)_________

Triassic (upper)__________

Triassic (Karnian, Norian). 

Triassic (Karnian)______

P. tuvalicus Diener 1919. 

P. ursensis Smith 1927_.

.do_ 

.do.

Timor.

Alps, Himalayas, Timor.

Alps, Timor.

Alps.

Timor.

Alps, Timor.

Alps, India, Timor.

California.

Timor.

New Zealand.

British Columbia.

Timor.

Alps, Timor, California.

California.

Do.

Alps, India, Timor, California. 

Alps. 

California.

Proclydonautilus triadicus Mojsisovics 

Plate 9, figures 1-20

1873. Nautilus triadicus Mojsisovics, K.-k. geol. Reichsanstalt 

Wien Abh., Band 6, Halfte 1, p. 27, pi. 14, figs. 1-4.

1882. Clydonautilus triadicus Mojsisovics, K.-k. geol. Reichsanstalt Wien Abh., Band 10, p. 281.

1891. Clydonautilus triadicus Mojsisovics, Foord, Catalogue of 

fossil Cephalopoda, Part 2, p. 182.

1902. Clydonautilus (Proclydonautilus) triadicus Mojsisovics, 

K.-k. geol. Reichsanstalt Wien Abh., Band 6, Halfte 1, 

Supplement Heft, p. 209.

1904. Clydonautilus (Proclydonautilus) triadicus Mojsisovics, 

Gemmellaro, I Cefalopodi del Trias Superiore della 

Regione Occidentale della Sicilia, p. 7, tav. 1, figs. 14, 

15, Palermo.

1904. Proclydonautilus triadicus Mojsisovics, Smith, Proc. 

California Acad. Sei. 3rd Series, vol. 1, no. 10, p. 401- 

402, pi. 46, fig. 2, pi. 47, fig. 2.

1905. Proclydonautilus triadicus Mojsisovics, Hyatt and Smith, 

U. S. Geol. Survey Prof. Paper 40, p. 206-207, pi. 49, 

figs. 1-3, pi. 50, figs. 1-17.

1908. Proclydonautilus triadicus Mojsisovics, Diener, Mem. 

Geol. Survey India, vol. 1, series 15, p. 50, taf. 1, fig. 1.

1914. Proclydonautilus triadicus Mojsisovics, Welter, Palao^-

tologie von Timor, I. Lieferung, p. 207-208, figs.

78, 79. 

1919. Clydonautilus (Proclydonautilus) triadicus Mojsisovics,

Diener, Akad. der Wiss. Wien, Denkschriften, Band 9",

p. 766-768, figs. 6, 7. 

1924. Proclydonautilus triadicus Mojsisovics, Kieslinger, Jaarboek Van Het Mijnwezen in Nederlandsch Oost-Indie,

Verhandelungen 3, p. 131. 

1927. Proclydonautilus triadicus Mojsisovics. Smith, U. S.

Geol. Survey Prof. Paper 141, p. 102-103, pi. 49 figs.

1-3, pi. 50, figs. 1-17.

This is one of the most common and widespread Upper Triassic nautiloids. The seven plesiotypes described 

and figured by Smith (1927, p. 102) are available for 

study. Smith's original description of these specimer<= 

is quoted here in part.

Involute, somewhat compressed laterally, high-whorled, with 

broadly rounded flanks and venter without any angle on either 

Umbilicus completely closed; broadly rounded umbilical shoulders. 

The whorl is slightly broader than it is high, and the greatest 

breadth is even with the projection of the top of the inner whorl. 

The height of the whorl is two-thirds of the total diameter. Tl •?
82 AMERICAN TRIASSIC COILED NAUTILOIDS

siphtmcle lies a little below the center. The surface is smooth and 

has no ornamentation except the exceedingly fine radial striae of 

growth, which bend backward on the venter, forming a broad 

hyponomic sinus.

The septa are sinuous, showing both lobes and saddles; the 

broad and deep ventral saddle is divided by a narrow and shallow 

abdominal lobe; the lateral lobe is long and rather broad; on the 

umbilicus there is a second lateral lobe, shallow and broad. 

There is no internal lobe.

The measurements (in millimeters) of the specimens 

illustrated are as follows:

U.S.N.M. No.

74027____._. __-----__-___

74027a___________________

74027b __________________

74027c____________. ______

74027d_. __-__-___-_-___._

74027e___._______________

74027f-----_---__---_-__-

Diameter

97

71

37

13

12

.7

3.5

Height of last 

whorl

62

40

23

7

7

3. 3

2

Width of last 

whorl

72

46

25

10

10

4.5

3.5

Occurrence.—Upper Triassic Hosselkus limestone, in 

both subzones of the zone of Tropites subbullatus, on the 

divide between Squaw Creek and Pit River, 3 miles east 

of Madison's ranch and half mile north of the trail to 

Brock's ranch, hi Shasta County, Calif.

Plesiotypes.—U.S.N.M. 74027, 74027a-f.

Proclydonautilus spirolobus (Dittmar) 

Plate 7, figures 10-19

1866. Nautilus spirolobus Dittma^r, Geognostische palaeontologische Beitrage, Band I, p. 352, pi. 13, figs. 1, 2. 

1873. Nautilus spirolobus (Dittmar). Mojsisovics, K.-k. geol.

Reichsanstalt Wien Abh., Band 6, Halfte 1, p. 28. 

1882. Clydonautilus spirolobus (Dittmar). Mojsisovics, K.-k.

geol. Reichsanstalt Wien Abh., Band 10, p. 281. 

1891. Nautilus (Clydonautilus) spirolobus Dittmar. Foord, Catalogue of fossil Cephalopoda, Part 2, p. 187-188, fig. 33. 

1902. Clydonautilus (Proclydonautilus) spirolobus (Dittmar).

Mojsisovics, K.-k. geol. Reichsanstalt Wien Abh., Band

6, Halfte 1, Supplement Heft, p. 211-212, pi. 10, fig. 3,

pi. 11, fig. 1. 

1914. Proclydonautilus spirolobus (Dittmar). Welter, Palaontologie von Timor, 1 Lieferung, p. 209-210, pi. 32, figs.

2, 3. 

1924. Proclydonautilus spirolobus (Dittmar). Kieslinger, Jaarboek Van Het Mijnwezen in Nederlandsch Oost-Indie,

Verhandelungen 3, p. 76, fig. 10. 

1927. Proclydonautilus spirolobus (Dittmar). Smith, U. S. Geol.

Survey Prof. Paper 141, pi. 88, figs. 6-14. 

1939. Proclydonautilus spirolobus (Dittmar). Muller and Ferguson, Bull. Geol. Soc. America vol. 50, p. 1605.

This Alpine Triassic species is represented in the collection by five specimens, four of which are the specimens described and figured by Smith (1927). This 

species has been recorded from California, Nevada, the

Alps, and Timor. The most diagnostic features are the 

ridgelike growth lines which are prominent ev^n on the 

internal mold. Conch is globose and involute with a 

well-rounded venter and no distinct ventrolateral 

shoulders. One of the paratypes with a diameter of 13 

mm has a smooth internal mold with delicate growth 

lines on the shell. One of the specimens has a portion of 

the aperture preserved and shows a shallow hTponomic 

sinus on the venter. Measurements (in millimeters) of 

the plesiotypes are as follows:

Height of last whorl._.__

14128

54

32

35

14128a

45

27

32

14128b

13

7

10.5

14128C

6. 5

3.5

4.5

Ornamentation is in general uncommor hi the 

Clydonautilidae. Proclydonautilus spirolobus is very 

easily distinguished from all other species of Proclydonautilus by its surface markings.

Occurrence.—Upper Triassic Hosselkus limestone, in 

the Tropites subbullatus, Juvavites subzone, at the 

north end of Brock Mountain, between Squaw Creek 

and Pit River, Shasta County, California.

Plesiotypes—U.S.^M. 14128, 14128a, 14128b, 

14128c.

Proclydonautilus stantoni Smith 

Plate 10, figures 1-6

1927. Proclydonautilus stantoni Smith, U. S. Geol. Survey 

Prof. Paper 141, p. 103, pi. 85, figs. 6-11.

Smith's original description is as follows:

Robust, involute, subspherical, with rounded flanks, subangular 

shoulders, and narrow flattened band on the venter, S irf ace with 

sinuous growth lines, making a broad, shallow backwr.rd-curving 

sinus on the venter. Septa with short narrow ventral lobe and 

deep lateral.

Measurements (in millimeters) of the specimens are 

as follows:

Diameter __________________ _ ____

Width of last whorl. ____ ____________

Height of last whorl _ _ ______________

Holotype

75

59

45

Paratype

30

23

18

Proclydonaubilus stantoni is most similar to P. 

triadicus, which, however, lacks the flattened venter.

Occurrence.—Upper Triassic Hosselkus limestone, 

at the lower horizon (Trachyceras subzono) of the 

Tropites subbullatus zone, 3 miles east of Hadison's 

ranch, on Brock Mountain, between Squr,w Creek 

and Pit River, Shasta County, California.

Types.—Holotype, U.S.N.M. 74123; paratype, 

U.S.N.M. 74123a.
CLYDONATTTILIDAE 8f

Proclydonautilus ursensis Smith 

Plate 11, figures 1-8

1927. Proclydonautilus ursensis Smith, U. S. Geol. Survey 

Prof. Paper 141, p. 103, pi. 84, figs. 1-3, pi. 85, figs. 1-5.

The holotype and two small paratypes are available 

for study. The conch of the holotype is large, robust, 

globular, and nautiliconic. The venter is broadly 

rounded, passing onto the flanks with no distinct 

ventral shoulders. The flanks are broadly convex and 

converge towards the venter. The umbilicus is completely closed. The living chamber appears to be 

nearly complete and is one-third volution in length. 

The shell is smooth except for conspicuous growth lines.

The two small paratypes agree hi most features with 

the holotype. There is no ventral lobe in the smallest 

paratype at a diameter of 8 mm. The larger paratype 

has a small ventral lobe. The measurements (in 

millimeters) of the specimens are as follows:

Diameter____ _ ._ _______

Width of last whorl __ __ _

Height of last whorl _

Holotype

125

75

69

Paratype

21

18

13

Paratype

5

6

5

The large robust globular conch of this species is 

uncommon in Proclydonautilus and direct comparison 

with other species is unnecessary.

Occurrence.—Upper Triassic Hosselkus limestone, in 

the upper part (Juvavites subzone) of the Tropites 

subbullatus zone, at Bear Cover, at the north end and 

east side of Brock Mountain, between Squaw Creek 

and Pit River, Shasta County, California.

Types.—Holotype, U.S.N.M. 74122; paratypes, 

U.S.N.M. 74122a and 74122b.

Proclydonautilus hessi (Smith) 

Plate 15, figures 12-15

1927. Clydonautilus hessi Smith, U. S. Geol. Survey Prof. Paper 

141, p. 107-108, pi. 88, figs. 15-19.

Conch small, involute, and compressed. The 

venter is flattened and rather broad, passing on to 

very distinct ventrolateral shoulders. At the maximum 

diameter of the conch the venter is 22 mm wide. The 

flanks are broadly rounded on the phragmocone but 

become more rounded on the living chamber. The 

umbilical shoulders are broadly rounded. On the 

phragmocone the venter is well rounded and the ventral 

shoulders are not distinct. No part of the shell is 

preserved but the surface of the internal mold contains 

impressions of the growth lines on the living chamber 

that clearly indicate the presence of a deep hyponomic 

sinus. The suture has a ventral saddle divided by a 

small bluntly pointed lobe, passing to a broad, deep

lateral lobe, and then to a narrow rounded lateral saddle 

just above the umbilical shoulder.

Smith placed this species in Clydonautilus on tb«. 

characters of its shape and septation. The shape c* 

the conch in the Clydonautilidae is highly variable and 

Proclydonautilus and Clydonautilus cannot be distinguished on this basis. The sutures of Proclydonavtilus hessi are typical of the1 genus, having only a small 

ventral lobe. In Clydonautilus there is a small saddle 

in the middle of the ventral lobe. This species is most 

closely related to Proclydonautilus sguawensis Kumme?, 

n. sp., differing in features of the ventral shoulderr. 

and in having a more inflated conch.

Occurrence.—Upper Triassic Hosselkus limestone, at 

the lower horizon (Trachyceras subzone) of the Tropites 

subbullatus zone, 3 miles east of Madison's ranch, on 

Brock Mountain, between Squaw Creek and Pit River, 

Shasta County, California.

Types .—Holotype, U.S.N.M. 74129; paratype, 

U.S.N.M. 74129a.

Proclydonautilus squawensis n. sp. 

Plate 8, figures 1-7, text figure 42

1927. Styrionautilus sauperi Smith, U. S. Geol. Survey, Pro*. 

Paper 141, p. 107, pi. 85, figs. 12-18.

The original assignment of the species to Styrionavtilus cannot be followed. Styrionautilus is charac terize i 

by a suture that passes over the venter in a straight 

line. Styrionautilus sauperi develops a narrow ventral 

lobe on the last few septa of a mature individual 

(Mojsisovics, p. 206, 1902). The present species has a 

distinct ventral lobe at a diameter of 13 mm. On thi« 

basis it seems advisable to place this species in 

Proclydonautilus.

The conch is involute, somewhat compressed, and 

smooth. The venter is broadly arched, terminating at 

sharply rounded ventral shoulders. The distinct ventral shoulders first develop at a diameter of approximately 15 mm. The flanks converge toward the 

venter and are concave on the ventral half, passing to 

a well-rounded umbilical shoulder (text fig. 42). Th^ 

surface of the conch is smooth except for growth lines 

that form a deep rounded hyponomic sinus on th°< 

venter. The suture has a small bluntly pointed ventral 

lobe, a deep lateral lobe, and a lateral saddle on the 

umbilical shoulder. The suture at a conch diameter 

of 13 mm has a shallow broad ventral lobe. Measurements (in millimeters) of the holotype and paratype* 

are as follows:

Diameter___ _____________

Width of last whorl__ _. __

Holotype 

74124

52

32

35

Paratype 

74124a

18

11

14

Paratype 

74124b

7

4.5

5.5
84 AMERICAN TRIASSIC COILED NAUTILOIDS

FIGURE 42.—Diagrammatic cross section of holotype of Proclydonavtilus squawensis 

n. sp. (U.S.N.M. 74124) from Hosselkus limestone Brock Mountain, Shasta 

County California, XL

The form of the conch in the Clydonautilidae is 

extremely varied. The general conch pattern of 

Proclydonautilus squawensis is similar to that of 

Proclydonautilus griesbachi, Styrionautilus sauperi, and 

Clydonautilus biangularis, but its suture pattern is 

different. It is also similar in conch pattern to some 

species of CosmonautHus but lacks the nodose ornamentation, and differs in suture pattern.

This species is named for Squaw Creek, which is 

near the outcrop area where the specimens were 

collected.

Occurrence.—Upper Triassic Hosselkus limestone, at 

the upper horizon (Juvavites subzone) of the Tropites 

subbuttatus zone, at Bear Cove, at the north end and 

east side of Brock Mountain, between Squaw Creek 

and Pit River, Shasta County, California.

Types.—Holotype, U.S.N.M. 74124; paratypes 

74124a and 74124b.

Proclydonautilus natosini McLearn

1946. Proclydonautilus natosini McLearn, Geol. Survey Canada, 

Paper 46-25, Appendix, p. 1, pi. 2, figs. 1, 2.

1947. Proclydonautilus natosini McLearn, Geol. Survey Canada, 

Paper 47-14, p. 5, 6.

The writer has not had the opportunity to study 

representatives of this species but McLearn's original 

description is quoted here.

The holotype is an incomplete shell of 90 mm in diameter; 

robust, involute, thicker than high whorls, with almost flat, 

converging sides, well-rounded ventral shoulder, low, rounded 

venter and nearly central siphuncle. Surface has fine, transverse, costae, nearly straight on sides, but bending back in a 

broad curve on venter; also longitudinal, short, low, closely 

spaced costae, forming with the transverse costae a delicate, 

textural ornament. Some specimens are larger than the holotype. Largest known specimen 200 mm in diameter, at which 

stage venter is wide and flat * * * Suture line like those 

of P. spirolobus Dittmar, P. goniatites Hauer and P. angustus 

Kieslinger; the ornament is different from these species, however, 

in having longitudinal as well as transverse ornament.

Occurrence.—Upper Triassic along Sikanni Chief 

River below Chicken Creek, northeastern British 

Columbia; from beds 'd' and V of measured section in 

McLearn (1946, p. 2, 3).

Types.—Geol. Survey Canada, holotype 9257, paratype 9260.

Genus COSMONAUTILUS Hyatt and Smith, 19^5

Genotype: CosmonautHus dilleri Hyatt and Smith

Hyatt and Smith (1905, p. 207) described the genus 

as follows:

Form involute, high whorled, laterally compressed, with 

narrow flattened venter and distinct abdominal shoulders. 

Surface at maturity smooth with only the striae of growth. 

Septa very sinuous, with broad rounded ventral lobe, long 

principal lateral, and a shallow small lobe outside o* the umbilicus. The internal septum has no lobe. Siphurole above 

the center.

In the adolescent stage this genus resembles Metacoceras (M.) 

cavatiforme Hyatt, Geol. Survey Texas, Second Ann. Rept., 

1890, p. 334, figs. 30-33). In these stages the whor1 is broad, 

much lower than at maturity, with simple septa, and a strong 

row of tubercles on the angular abdominal shoulders. The 

phylogeny of this group seems,to be as follows: TemnocheilusMetacoceras-Cosmonautilus.

Welter (1914, p. 218) followed Hyatt and Smith in 

according CosmonautHus full generic rank. Diener 

(1919, p. 770-771) pointing to the close similarity 

between CosmonautHus dilleri and Proclydonautilus 

buddhaicus came to the contusion that the former 

could at best be only considered a subgenus cf Proclydonautilus. Kieslinger (1924, p. 63 etc.) completely 

suppressed CosmonautHus and placed its species in 

Proclydonautilus. Smith (1927, p. 104) in his monograph on the Upper Triassic Faunas of North America, 

merely repeated the description by Hyatt and Smith 

(1905, p. 207) and made no reference to the work of 

Welter, Diener, or Kieslinger. The rather involved 

discussion of CosmonautHus and Proclydonautilus by 

Kieslinger, and the wide latitude he allows Proclydonautilus does not appear to be the correct or simplest 

approach to this problem.

The only essential difference between CosmonautHus 

and Proclydonautilus rests in the presence o* ventrolateral nodes on the early whorls of the former. These 

nodes, however, have no relationship whatsoever with a 

"Metacoceras" ancestry as believed by H^att and 

Smith. The present writer believes that CosmonautHus 

is derived from Proclydonautilus, and that the Clydonautilidae have their ancestry in the Paranautilidae 

(probably ParanautHus). In neither of these families 

are nodes of any form a dominant morphologies! feature, 

on the contrary both families are characterized by involute smooth forms generally lacking ornamentation. 

The development of nodes in Cosmonautilus is a coenogenetic character developed as a new feature and un-
CLYDONAUTILIDAE

Distribution of species of the genus Cosmonautilus

Species

Cosmonautilus dilleri, Hyatt and Smith 1905 _ _

C. dilleri var. spiralis Kieslinger 1924

C. hersheyi Smith 1927

C. jonkeri Kieslinger 1925 _ __

C. malayicus Welter 1914 _ _ _

C. pacificus Smith 1927

C. shastensis Smith 1927- _ ____

Stratigraphic distribution

Triassie (Karnian) _ _ ___

Triassie (upper).. ___ ___

Triassie (Karnian) ___ ___

do ______

Geographic distribution

California; Sonora, Mexico. 

Timor.

California.

Timor.

Do.

California.

Do.

related to the ancestral form. A similar feature is 

found in another smooth stock, that of the Grypoceratidae. In some species of Domatoceras and Plummeroceras, low ventrolateral and dorsolateral nodes are 

developed in late maturity. Gryponautilus also includes species that develop ventrolateral nodes. This 

genus is very similar in some respects to Proclydonautilus and has an annular lobe. It thus appears that the 

nodes on the early whorls of Cosmonautilus have no 

phylogenetic significance but are rather a new modification that developed on a proclydonautilid stock.

Cosmonautilus dilleri Hyatt and Smith 

Plate 12, figures 1-4; pi. 13, figs. 1-7; pi. 14, figs. 1-6.

1905. Cosmonautilus dilleri Hyatt and Smith, U. S. Geol. Survey 

Prof. Paper 40, p. 207-208, pi. 51, fig. 1; pi. 52, fig. 1; 

pi. 53, figs. 1, 2; pi. 54, figs. 1-4; pi. 55, figs. 1-11.

1914. Cosmonautilus cf. dilleri Hyatt and Smith. Welter, Palaontologie von Timor, 1, Lieferung, p. 128-220, figs. 

93-98; pi. 33, figs. 1-3.

1919. Cosmonautilus dilleri Hyatt and Smith. Diener, Akad. 

Wiss. Wien, Denkschriften, Band 96, p. 770-771.

1924. Proclydonautilus (Cosmonautilus) cf. dilleri Hyatt and 

Smith. Kieslinger, Jaarboek Van Het Mijnwezen in 

Nederlandsch Oost-Indie, Verhandelungen 3, p. 87, 

pi. 3, figs. 3a, b; text fig. 17, 18; p. 90, fig. 19.

1924. Proclydonautilus (Cosmonautilus) dilleri var. spiralis 

Kieslinger, Jaarboek Van Het Mujnwezen in Nederlandsch Oost-Indie, Verhandelungen 3, p. 90, pi. 6, 

figs, la, b.

1927. Cosmonautilus dilleri Hyatt and Smith. Smith, U. S. 

Geol. Survey Prof. Paper 141, p. 104, pi. 51, fig. 1; pi. 

52, fig. 1; pi. 53, figs. 1, 2; pi. 54, figs. 1-4; pi. 55, figs. 

1-11; pi. 90, fig. 1; pi. 91, figs. 1, 2; pi. 92, figs. 1, 2.

The original description of this species is as follows: 

Form involute, high whorled, somewhat compressed laterally, 

deeply embracing, and deeply indented by the inner volutions. 

Greatest breadth of the whorl at a point even with the projection 

of the inner volution. The height of the whorl is two-thirds of 

the total diameter of the shell, the width is six-sevenths of the 

height, and the indentation by the inner volution is less than 

one-third of the height. The whorl is broadly convex, and slopes 

up from the widest point to the abruptly rounded abdominal 

shoulders; the venter is flattened and its width between the 

shoulders is less than one-third of the greatest breadth of the 

whorl. The siphuncle is above the center of the chamber.

The septa are sinuous, divided externally into complex lobes 

and saddles. The long ventral saddle is divided by a broad

U-shaped ventral lobe, forming two very narrow tongue-shaped 

saddles on the abdominal shoulders; there is a deep and bread 

principal lateral lobe, with rounded extremity, and a sm«,ll 

shallow lateral on the umbilical slope. The internal septum 1 T,S 

no lobe nor saddles. The surface of the shell is smooth at maturity, having only fine cross striae of growth.

In youth, up to the diameter of 8 mm, the whorl is subglobose 

and perfectly smooth, with simple straight septa. At this s; ze 

the abdominal shoulders begin to develop, and very soon faint 

tubercles begin to appear on the shoulders; this sculpture rapidly 

grows strong, until the shape, sculpture, and septa are very like 

those of Metacoceras Hyatt. But by the time a diameter of 

12 mm is reached the septa already show the sinuous lobes and 

saddles characteristic of the mature form, except that they r.re 

not so complex. We thus find Metacoceras characters and those 

belonging to Cosmonautilus occurring simultaneously in the 

same individual, which may mean either that the Paleoz'oc 

characters are retarded in the development or that the Mesozoic 

characteristics are unduly accelerated in their appearance.

At the diameter of 35 mm the tubercles become obsolete and 

the shoulders lose their angularity. The shell is then entering 

on maturity, and from this time onward does not change in any 

essential characters, the whorls becoming proportionally higl -;r 

and more compressed laterally, but retaining their general 

characters. J. P. Smith has found a specimen of 280 mm 

diameter that agreed in all essentials with those of about 100 

mm.

Occurrence.—Upper Triassie Hosselkus limestone, in 

the Juvavites subzone of the zone of Tropites subbullatus, 

on the divide between Squaw Creek and Pit River, 

3 miles east of Madison's ranch and half a mile north 

of the trail to Brock's ranch, in Shasta County, California. At the same horizon at Terrup Chetta (Cottonwood Flat), near Squaw Creek, about 6 miles north 

of the locality just mentioned. Cerro Colorado (or 

Cerro de la Cruz) about 150 meters east of El Antimorio 

Sonora, Mexico; in red shale and platy limestor% 

probably zone described by Burchardt (1930) as r^d 

argillaceous shale with fossils of Karnic age.

Types.—Holotype and paratypes, U.S.N.M. 74028; 

plesiotypes 74463, 108003.

Cosmonautilus pacificus Smith

Plate 16, figures 1-14

1927 Cosmonautilus pacificus Smith, U. S. Geol. Survey Prof. 

Paper 141, pi. 86. figs. 1-15.

The holotype of this species is incomplete. T>Q 

conch is compressed and involute. The venter is flat-
86 AMERICAN TRIASSIC COILED NAUTILOIDS

tened, grading to sharply rounded ventral shoulders. 

At the maximum diameter of the conch, the venter is 

18 mm wide; where the phragmocone and living chamber 

meet, the venter is slightly arched and 12 mm wide. 

The most adoral part of the living chamber shows a 

trace of the apertural margin, which on the venter defines 

a shallow sinus. The living chamber is about one-third 

of a volution in length.

The flanks converge towards the venter, and are 

flattened, with broadly rounded umbilical shoulders. 

The surface of the conch has very fine closely set ribs 

from the umbilicus to the venter. On the internal 

mold of the living chamber the ribs are visible only to 

the midpoint of the flanks and absent on the umbilical 

shoulders. The suture forms a deep U-shaped ventral 

lobe adjoined by a rounded saddle on the flanks adjacent 

to the ventral shoulders. The lateral lobe is deep and 

asymmetrical, and there is a lateral saddle on the 

umbilical shoulder. The siphuncle is centrally located.

The largest paratype, with a diameter of 56 mm, has 

indistinct ventral shoulders and a well-arched venter. 

The Banks converge strongly towards the venter. The 

ribbing is especially prominent on the ventral shoulders. 

The second largest paratype has a flattened venter and 

distinct ventral shoulders. The flanks are also flattened 

and converge towards the venter. The adapical portion 

of the conch small nodes are present on the ventral 

shoulders. The third largest paratype, with a diameter 

of 18 mm, has a more compressed conch and a flattened 

venter. The pattern of ornamentation is similar to 

that of larger paratypes and consists of both nodes and 

ribs. The siphuncle is central. The smallest paratype, 

with a diameter of 12 mm, has a slight ventral lobe on 

the adoral half whorl but adapically, the suture is 

straight and conch smooth and rounded. The siphuncle 

is below the center.

A. weathered but complete topotype plus three fragmentary topotypes are also available. All of these 

specimens agree perfectly with the primary types. The 

measurements (in millimeters) of the type specimens 

are as follows:

Diameter____ _ Width of last 

whorl. _ ___

Height of last 

whorl _ _ _ _ _

Holotype 

74125

95

60

61

Paratype 

74125a

56

39.5

36

Paratype 

74126b

31

24

21.5

Paratype 

74125c

18

14

11

Paratype 

7412M

12

9

7.5

Occurrence.—Upper Triassic Hosselkus limestone, in 

the upper horizon (Juvavites subzone) of the Tropites 

subbullatus zone, at the north end of Brock Mountain,

between Squaw Creek and Pit River, Shasta County, 

California.

Types.—Holotype, U.S.N.M. 74125; paratypes, 

U.S.N.M. 74125a, 74125b, 74125c, 74125d; topotypes, 

U.S.N.M. 108002.

Cosmonautilus shastensis Smith 

Plate 15, figures 1-11

1927. Cosmonautilus shastensis Smith, U. S. Geol. Survey Prof. 

Paper 141, pi. 87, figs. 1-11.

The holotype and three small paratypes are available 

for study. The holotype is a fragment of a large, 

robust phragmocone. The conch is very involute, 

with its greatest width in the vicinity of the umbilical 

shoulders. The venter is broadly arched, measuring 

up to 25 mm in width on the most adoral part of the 

conch. The ventral shoulders are acutely rounded. 

The flanks adjacent to the ventral shoulders are concave, but where the shell is preserved this COE cavity is 

less pronounced. The central and dorsal part of the 

flanks is arched. The flanks converge strongly towards 

the venter.

The sutures have a rounded ventral lobe ai: d a deep 

lateral lobe with a lateral saddle adjacent to the umbilical shoulder. The position of the siphuncle is not 

observable on the holotype. The shell is preserved in 

a few places on the conch of the holotype. The shell 

is 3.5 mm thick on the venter and is 1.5 mm thick on 

the midpoint of the flanks. Strong growth lines are 

visible on the shell. The ventral shoulders I ^ar long, 

high nodes 15 to 20 mm apart.

The largest paratype is an immature individual that 

is 31 mm in diameter, 26 mm wide at the moH adoral 

part and 19 mm high. The shell has a broad, flattened 

venter and sharp ventral shoulders. The fhnks are 

flattened and converge strongly towards the venter. 

The ventrolateral nodes are very weakly developed. 

The second largest paratype is 15.5 mm in diameter, 

and has only a faint indication of flattening of the 

venter on its most adoral part. The preserved adapical 

part of the conch has a rounded venter and flunks with 

no prominent ventral shoulders. The surface iTM marked 

by conspicuous growth lines that show a shallow 

hyponomic sinus. The siphuncle is central. The 

smallest paratype is 7 mm in diameter, has r. broadly 

rounded venter, and flanks with no ventrolateral 

shoulders. The conch is involute, and has whorls 6 mm 

wide, 4 mm high. The siphuncle is below tH center.

The various species of Cosmonautilus are so distinctive that direct comparisons are not necessary.

Occurrence.—Upper Triassic Hosselkus limestone, 

at the upper horizon (Juvavites subzone) of the Tropites 

subbullatus zone, at Bear Cove, at the north end and
CLYDON AUTILIDAE 87

rast side of Brock Mountain, between Squaw Creek and 

Pit Kiver, Shasta County, California.

Types.—Holotype, U.S.N.M. 74126; paratypes, 

U.S.N.M. 74126a, 74126b, 74126c.

Cosmonautilus hersheyi Smith

Plate 10, figures 7-15

1927. Cosmonautilus hersheyi Smith, U. S. Geol. Survey Prof. 

Paper 141 pi. 89, figs. 1-9.

This species is the smallest American species of 

Cosmonautilus. The holotype and two small paratypes 

are available for study. The conch is involute, smooth, 

and has a narrow, arched venter. The ventral shoulders are subangular, and there is a groove just dorsad of 

the ventral shoulder. There are slight nodes on the 

ventral shoulder on the adapical half of the last whorl of 

the holotype. The flanks are convex and converge 

towards the venter. The greatest width of the conch 

is at the umbilical shoulders. The shell is smooth with 

delicate growth lines which form a sinus on the venter. 

The siphuncle is central.

The largest paratype measures 33 mm in diameter, 

22 mm in height of the last whorl and 22 mm in width of 

the last whorl. There is no groove on the ventral 

portion of the flank. The venter is more arched and the 

ventral shoulders not as distinct as on the holotype. 

The smallest paratype has a diameter of 19.5 mm, a 

height at the last whorl of 13 mm, and a width of 12.5 

mm. Distinct ventral shoulders develop at a diameter 

of 12 mm. Adapically the whorls are rounded, and 

have no distinct ventral shoulders. The growth lines 

are very conspicuous. The septa on this small paratype are like those on the mature specimens.

Occurrence.—Upper Triassic Hosselkus limestone, at 

the upper (Juvavites subzone) of the Tropites subbuLlatus 

zone, at the north end of Brock Mountain, between 

Squaw Creek and Pit Kiver, Shasta County, California.

Types.—Holotype, U.S.N.M. 74130; paratypes, 

U.S.N.M. 74130a, 74130b.

Genus CALLAIONATJTinjS Kieslinger, 1924 

Genotype: Callaionautilus turgidus Kieslinger

Kieslinger (1924, pp. 93-95) described the type species 

of his new genus as follows:

Die neue Gattung gehort in die Nahe der von Hyatt und 

Smith unter dem Namen Cosmonautilus zusamengefassten Formen.

Die inneren Windungen, bis zu einem Durchmesser von etwa 

70 mm, stimmen vollstandig mit Proclydonautilus (Cosmonautilus) Dilleri iiberein: Eine gedrungene, fast vollkommen involute 

Form, die Flanken kraftig aufgeblaht, jedoch gegen die Schultern 

hin ebenso stark komprimiert; mit scharfen Kanten setzt der 

flache Externteil an. Diese Kanten tragen im inneren Teile der 

Windungen, bei Durchmessern von durchschnittlich 35 mm, 

Knoten, die bald scharf und deutlich ausgepragt sind, bald kaum 

merklich hervortreten.

Zwei Exemplare zeigen eine etwas abweichende Externskulp+ur 

in diesem Stadium, namlich flache Quewulste auf den Externteil 

wie bei Proclydonautilus inftatus, andere Formen erscheinen 

wieder ganz glatt; die Variationsbreite dieser Formen ist also 

auszerordentlich grosz. Ein Bild von diesem Stadium gibt 

Text fig. 20 [fig. 43 of this report]. Einige Maszzahlen sollen es

naher erganzen:

Millimeters

Durchmesser_____.__-------__ 77 57 69

Windungshohe.---______.-.-_ 45 34 42

Lichte Hohe--_.____________ 31 20 30

Breite__....----.-_____----------__ 52 45 43(?)

Das von Welter (Timor, S. 225, Taf. 34, Fig. 4, 5) als Grypoceras cf. Suessiforme (Diener) beschriebene Exemplar scheint 

eine solche Jugendform eines Callaionautilus turgidus zu sein.

Bei einem Durchmesser von durchschnittlich 70 mm beginnt 

nun eine eigentiimliche Anderung: Die scharfen Kanten vers^hwinden, der Externteil wolbt sich auf, die Zone der groszten 

Breite riickt von der Nabelgegend gegen die Externseite bis in 

die Projektion des vorhergehenden Umganges. Der Querschnitt bildet nun ein fast einheitliches Oval. Nun beginnt sich 

in der Medianlinie des Externteiles ein plumper Kiel herauszuheben, der sich bald in eine Reihe groszer, langlicher, stumj fer 

Knoten auflost [pi. 19, figs. 6, 7, of this report]. Diese eigentiimliche Skulptur laszt sich etwa mit einem Hahnenkanm 

vergleichen. Beiderseits dieser Knotenkielreihe liegt eine flache 

Einsenkung, die durch ganz gerundete Schultern mit den Flanl'en 

zusammenhangt.

Die Schale aller Exemplare ist auffallend dick, auch bei ganz 

kleinen Formen. Gewissermaszen im Widerspruch hiezu s'ud 

die Kammerscheidewande bei fast alien Stticken zerstort, nur 

zwei zeigen schlecht erhaltene Fragmente, zwischen ein^m 

Gewirr von Serpuliden, welche das leere Gehause besiedelt 

batten.

Die Lobenlinie bleibt—ahnlich wie bei Prodydonautilus 

singularis Walter—lange Zeit in dem primitiven Stadium etwa 

eines Paranaulilus: ein einfacher Laterallobus, ein ebe.iso 

flacher, stumpfwinkeliger Externlobus (das Gehause zeigt in 

diesem Stadium eine deutliche Normallinie). Erst nach ein<*m 

Durchmesser von 40 mm beginnt sich der Laterallobus zu 

vertiefen, bzw. der Externsattel hoher zu werden. So entsfoht 

eine Proclydonautilus-Svtur. Ein groszeres Exemplar zeigt (bei 

einem Durchmesser von ca. 70 mm) einem spitzen Laterallofcus, 

der etwa an Proclydonautilus Dilleri erinnert.

Der Sipho konnte infolge des ungiinstigen Erhaltungs*ustandes nirgends beobachtet werden.

Dimensionen (am Steinkern gemessen):

Millimeters 

Durchmesser- _ _______________________________ 106

Windungshohe _..____-_______----__--_-__---- 60

LichteH6he--_. — _ —. — — — — . —— — — . 39 .

Breite _______________________________________ 58

Nabelweite__ _ -___-_--__-__.-______-__-_____ 11

Kieslinger's description of Callaionautilus turgidus 

can be summarized as follows:

This new genus is similar to Cosmonautilus Hyatt and Smith. 

The inner whorls, up to a diameter of approximately 70 mm, 

agrees completely with Proclydonautilus (Cosmonautilus) dilleri. 

Conch almost completely involute, whorl sides strongly inflated, 

but compressed towards the shoulders, venter flattened, shoulders 

angular. The ventral shoulders up to a diameter of the conch 

of 35 mm bears nodes which adorally disappear. The extent of 

variation in this species is very great. Grypoceras cf. suessiforme
88 AMERICAN TRIASSIC COILED NAUTILOIDS

(Welter, 1914, p. 225, pi. 34, figs. 4, 5) appears to be a young 

form of Callaionautilus turgidus.

At a diameter of 70 mm the whorl section begins to become 

oval and the angular ventral shoulders disappear. A median 

keel is formed on the benter on which soon develop large nodes. 

This peculiar sculpture is similar to a cock's comb. On both 

sides of the median nodose keel is a shallow furrow. The suture 

is similar to that of Proclydonautilus dilleri. The siphuncle was 

not observed.

In a supplement to his main article Kieslinger (1924) 

discussed Callaionautilus turgidus in greater detail and 

came to the conclusion that his new genus fell within 

the sphere of variation of Proclydonautilus and suppressed it. Whereas the early whorls show remarkable 

similarity to Cosmonautilus and Proclydonautilus, the 

transformation of the conch to a smooth oval whorl 

with a central nodose keel appears to be a definite 

evolutionary change (or advancement) over these other 

two genera. Callaionautilus can better be considered 

as another evolutionary development (similar to Gosmonautilus) out of a proclydonautilid stock and taxonomically ranked as a genus. It is, however, true that 

we are dealing with a monotypic genus in which all of 

the few specimens known came from the Upper Triassic 

of Timor. Probably when more material is available 

the relationships of Callaionautilus will be better understood. Spath (1927b, p. 24) believes that Callaionautilus probably does not belong in the Clydonautilidae, 

but gave no reasons for his opinion.

Genus CLYDONAUTILUS Mojsisovics, 1882

Genotype: Nautilus noricus Mojsisovics 

Mojsisovics' description of the genus is as follows:

Aus der ziemlich betrachtlichen Anzahl der triadischen 

Formen scheiden wir vorlaufig bios die auf die juvavische Provinz 

beschrankte Gruppe des Nautilus noricus als besondere Gattung 

unter der Bezeichnung Clydonautilus aus. Es gehoren dahin 

involute, hochmundige Formen mit geschlossenem oder sehr 

kleinem Nabel und drei ausserhalb des Nabels liegenden, tiefen, 

spitzgerundeten Loben, von welchen zwei ausserhalb der Projection der vorhergehenden Windung liegen. In hoherem Alter 

theilt sich der Externlobus durch einen grossen, sattelformigen 

Medianhocker in zwei getrennte, auf die Seitenflanken abgedrangte Partien. Ein Interlobus ist nicht vorhanden. Der 

Sipho steht unter oder uber der halben Mundhohe. Schalenoberflache entweder reticulirt oder quer gestreift oder mit schwachen 

Lateralfalten versehen.

A summary of Mojsisovics' description is as follows:

Conch involute, compressed, with a closed or very small 

umbilicus. Suture with deep sharply rounded lobes. The ventral lobe has a small median saddle. No annular lobe is present. 

The siphuncle lies either above or below the center of the whorl 

section. Shell reticulate, with cross striae, or with weak folds.

The conch of Clydonautilus is involute and of the same 

pattern as in Proclydonautilus, which was separated by 

Mojsisovics (1902) as a subgenus of Clydonautilus, but

FIGURE 43.—Diagrammatic cross section of young form of Callaionautilus turgidus 

Kieslinger, XI. (After Kieslinger, 1924, fig. 20).

the shell is generally more compressed. Generally the 

venter is flattened, at least during some stage of growth. 

The division of the ventral lobe by a small saddle 

("Medianhocker") is most highly developed in Clydonautilus noricus (see text fig. 41), in which the saddle is 

very deep and somewhat quadrangular in shape. In 

Clydonautilus salisburgensis and C. biangularis the dividing saddle of the ventral lobe is very slightly 

developed (text fig. 41). Other species such fs Clydonaulilus Quenstedti have a small saddle intermediate 

between that found in C. noricus and C. biangularis; it 

is, however, still rounded and not angular as in C. 

noricus.

Most species of Clydonautilus are smooth, but a few 

species show ornamentation. Clydonautilus cicatricosus 

Kieslinger has nodes developed on the ventral shoulders, 

as in typical representatives of Cosmonautilus, bnt it has 

a clydonautilid suture. Other species, as C. biangularis, 

have low flat folds on the flanks that extend in lesser 

degree over the venter.

The only essential difference between Clydonautilus 

and Proclydonautilus is the former has a median saddle 

dividing the ventral lobe. As pointed out by Kieslinger 

(1924) the median saddle does not develop until a late 

stage of growth in some species. The oldest known 

species of Clydonautilus seems to be C. kieslingeri 

Pakuckas from the Ladinian of Timor. Th?,se two 

genera, differing in only one feature, probably represent 

independent but closely related lines developing out of 

Styrionautilus. Cosmonautilus is thought to stem from 

Proclydonautilus but does show affinities to Clydonautilus through Clydonautilus cicatricosus.
GONIONAUTILIDAE

Distribution, of species of the genus Clydonautilus

Species

C. biangularis Mojsisovics 1896

C. cicatricosus Kieslinger 1924 __ _ _ _

C. compressus Welter 1914 _ ___

C. glaber Kieslinger 1924-- __-_ _____ ____

C. kieslingeri Pakuckas 1928 _ _ _.__

C. salisburgensis (Hauer) 1849 _ _

Stratigraphic distribution

_____do________ --__-----_-_--------_---- _--_

_____do__-_--------- ------------------------

Triassic (Ladinian) . ___ ______

T^TI fiQci f* f N"riTi?i n^

_____do---_ — ----- ------------------------

TTI ft Qdi f* f iTrmpT^

Geographic distribution

Himalayas, India.

Himalayas, India; Timer.

Timor.

Do.

Do.

Do.

Alps.

Timor.

Alps.

Alps, Timor.

Family GONIONAUTILIDAE Kummel, 1950 

Genus GONIONAUTILUS Mojsisovics, 1902

Genotype: Nautilus securis Dittmar

This monotypic genus includes one of the most 

specialized of Triassic nautiloids (pi. 19, figs. 4, 5). 

Mojsisovics considered Gonionautilus to be the end 

form in an evolutionary development beginning with 

ParanautUus through ClydonautUus. The genus has 

been recorded from Norian rocks of the Alpine region 

and from the Pinacoceras metternichi zone (Norian) of 

the Gabbs formation, southwestern Nevada (Muller 

and Ferguson, 1939, p. 1605).

Mojsisovics' original description of this genus is 

quoted here in full (1902, p. 207).

Die hochmtindigen involuten Gehause sind mit einem schmalen, biangularen Externtheil versehen und stimmen in alien 

wesentlichen Merkmalen mit den typischen Clydonautilen mit 

zweispitzigem Externlobus tiberein. Es uterscheidet sie bios 

ein, meines Wissens, bei Nautilen bisher noch neimals beobachtetes Merkmal', ein zwei spitziger Internlobus. Dem zweispitzigem Externlobus entspricht bei Gonionautilus auch ein zweispitziger Internlobus. Es ist sehr bemerkenswert, dass Gonionautilus ohne Passirung eines Zwischestadiums mit einspitzigem 

Internlobus sich aus einer Gattungsreihe herausgebildet hat, 

welche (iberhaupt keinen Internlobus besass.

Die Position des Sipho schwankt um die halbe Miindungshohe; 

bei der typischen Art steht der Sipho oberhalb der halben 

Miindungshohe.

Mojsisovics' description can be summarized as 

follows:

Conch compressed with a narrow, angular ventral area and 

similar to ClydonautUus in its double pointed ventral lobe. It 

is mainly characterized by its double pointed annular lobe. It 

is remarkable that Gonionautilus, belonging to a stock which 

possesses no annular lobe, attained a double annular lobe without 

an intermediate stage of a singular annular lobe. Siphuncle is 

in the upper half of the whorl section.

The shape of the conch, and the external suture place 

this genus close to the Clydonautilidae. However, the 

peculiar double annular lobe sets this form apart from 

other Triassic nautiloids. The Clydonautilidae do not 

have annular lobes.

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ERRATA

Page 

Page

Page 

Page 

Page 

Page 

Page

10, col. 1, line 31 — for mesodzscws read mesodicum 

19, table — take out F. ivynnei (Waagen) 1879

col. 2, line 8 — for cavatiformis read cavatiforme 

21, col. 2, line 9 — for aureculatum read auriculatum 

26, col. 2, line 53 — for goliathus read goliathum 

33, col. 2, line 38 — for Encoiloseras read Encoiloceras 

44. col. 1, line 40 — for Trachynatilus read Trachynautilus 

51, col. 1, line 27 (second table) — for gumbeli read gumbeli 

232820—53 ——— 7

Page 53, table—for guembeli read gumbeli

col. 2, line 3—for htinictis read hunicum 

Page 55, table—for parallelus read parattelum 

Page 59, col. 1, lines 4, 12—for convolutus read convolutum 

Page 60, col. 2, line 38—for granulosostriatus read granulosostriatum 

Page 61, col. 1, line 27—for evolutus read evolutiim *

col. 1, line 27—for eugyrus read eugyrum 

Plate 1—for sangamonensis read sangamonense

INDEX

[Italic numbers indicate descriptions]

A Page 

aberrans, Stearoceas-...-... __..__________________________________________ 58

abundans, Stenopoceras..._______________________________________ 58

acanthicus, Temnocheilus---. .__-_---___________________________.. 18

AcanthonautUus _____ — _________________ _______ _______________ 9,66,74

bispinosus- ______ __________-.-._______________________........ 74

cornutus.--... __________________________________________________ 66

ads, Syringoceras - -. .__..___.._.-.__________________ ___------._______ 61

Acknowledgments.. .___________________________________ ____________ 1-2

acutUobatus, Clydonautilus- -_______-___________________.________ 89

acutus, Nautilus.---. ___________________________________________ 5,63

OxynautUus_______._-________._-_________._.._________..____ 3,65

advena, Germanonaittilus—-.....—..----.....-................................ 28

Aganides bitauniensis- _..__________---._____________________________ 11,77

alaskensis, Pleuronautilus-_. _. ______________________________ 3

Pleuronautilus (Pleuronautilus)-.--------- _____________ 34, 36, pi. 4

attius, Srringoceras—-—-. ________——_.__

ambiguus, Pleuronautilus (Pleuronautilus)..

spirata, Pleuronautilus (Pleuronautilus) . 

ampezzanus, Anoploceras _.._ __.___._____

Nautilus—----- -_--_---__-_-_._-_--._--.

Pleurona utilus-- --------------- _-_-____

angulatum, Metacoceros-___-_-_-_--._—..__

Metacoceras (Metacoceras) ______—_.._

angustus, Prodydonautilus------------------

............................ 61

--______________-.-._.______ 36

- — — — ——— —-_ — _.. 36

- — — — — _— .......... 43

-_-.-__.-..__.__._...._.._._ 5

------_-_-.-.-_-----._..-_.. 33

- _ — _____-..-..-.-.-..... 19

- — - — — _-. —_-. — _•-_. 20 

_ — — .-_ — ..„.-_....... 81

anisi, Paranautilus__.._.________________________________ 69,71,80

Anoploceras-—--...... .....___-___._„-._______________ 5,6,7,12,17,33,45

ampezzanus--—----------------— _____________________.____ 43

(Anoploceras) rollieri, Pleuronautilus-------------------- _________........... 44

arcestiformis, Parinautilus--------------------_-.--.-9......_.______ 71

armatum, Metacoceras (Metacoceras)------.--- _________....____________ 20

arthaberi, Domatoceras-—________ ——.-..__._.__._ — _——........—_.._._ 51

Orypoceras (Domatoceras) ____ —— _.-..... — _.__._.__....__________ 55

artiense, Metacoceras (Metacoceras) piszovi.. ______ —...______________ 20

asiaticus, Temnocheilus__________.---.,._._.._.___.__...________. 18

atubercidatus, Temnocheilus--- _______________.-.______________._ 18

Aturia--- ———-—----------------- — --—— — .-——- 10,11,12,75,77

Aturoidea.- ______________________________________________________________ 10,11,77

augusti, Metacoceras (Mojsvaroceras) ____________.---. _ '_.___________. 21

Temnocheilus-----... _---_-_-----_--__-_-___-_--_--__-.__. _...____ 21 

Aulametacoceras------... ___-_______________._..______ 4,7,12,13,26,^7,32

mckeei---------------------------------------—--.---......... 4,13,25,27,32

rectangularis.... _______._-_--______.____._____.___ 7,13,28,32

auriculatum, Metacoceras (Mojsvaroceras).—.- ...-'-.-._.____.__.-__..___ 21

ausseeanus, Pleuronautilus (Enoploceras)..................... ___....._____ 41

Aviculopeclen- — _.__—__ ——.-_.-__——————...._________._ 31

bambanagensis, Paranautilus--------------------._._.___.. — _.———._. 69,71,73

banandei, Nautilus-- ______..________.___._.________...._ 60

Suringoceras------------ ____.---.._____________________............. 61

baylorense, Metacoceras (Metacoceras} ___--_-_--__-_,________......... 20

bellatulum, Parametacoceras.- ___________-__------_-___---___.. .___. 4,24

biangularis, Clydonautilus_____. — -. — -......„..._______...._ 84,88,89

Bibliography-_____________....______________....________ 89-93

bidorsatus, Germanonautilus-..----------------- _____-_____-_--.________ 28

Nautilus—-^-.---------..-- ——.-.--.-.---- ____________________ 4,28

binodosum, Metacoceras (Mojsvaroceras)-.------------------.--- _______. 21

biseriatum, Metacoceras------- _________________________________ 19

Metacoceras (Metacoceras) _________.---__.__.. __.__.....__. 20

bispinosus, AcanthonautUus..---- -.-_------_-.-__-_-_---__--__-.---_.____...._ 74

bitauniensis, Aganides— ___._--_-__---_. — —— -_.__.-.__.______ ——...___ 11,77

bituberculatum, Metacoceras (Metacoceras)----------------- _____ — -------_-. 20

blakei, Orthoceras_____.____..—..________-.___-_-...___.... 2

bosnesis, Syringonaiitilus. __._-.____--__ _--_______.__.......____ 60

trradyi, Domatoceras-... ... __________..____.._-__--__.______...___ 51

Orypoceras (Domatoceras)----———_______.—_____———____ 55

Paie 

brahmanicum, Orypoceras........... __-_.__-._.- — ___.--. ——— __-.__ 2,47,51

Orypoceras (Orypoceras).......__ ..—.........-- ..... .... ——. —....—— 53

brembanus, Paranautilus..... ________ -._ _- —— -----———--_ —— _—— 69,71

breunneri, Oermanonautilus... __-. — -.___ ——— -_-.___.-___-.--_-_ ——— —— - 28 

breve, Syringoceras... ________—_--.------_ — ---_ ———— —— _-.—— 61

brevius, Syringoceras... _.--___-__---_——-- ——.-_---__---_-- ———... 61 

brooksi, QermanonautUus_____..--__._-.__._-- — _____— —._. 3,28, 29, pi. 3

brouweri, JuvavionautUus-..---------------......--.-. — — -_-___- — -_——-- 63

buddhaicus, ProdyodonautUus..-- _..___ —,... — ---- —— __---------__-——— 81,84

bullatus, Syringonautilus........... _——_._-.---_-_----_----_._--------.—— 60

buttocki, Paranautilus.-.—............————————_————————.——— 71

bulogense, Metacoceras (Mojsoeiroceras).. — -_-- —— —- — __-___—— ——.—— 21 

buriensis, Solenochilus——_ —— — ——_-_.. —— -.._ —— __ —— — -_____-——— 69

C 

California, Triassic nautiloid occurrence._______-__--_..i. — _ —— _... 3

Callaionautilus—---——'- — --—---——------. 5,7,9,10.66,75,77,81,87,88

turgidus.-..——-—-—--—-— — — -------------- 5,87-88, pL 19

campanile, Orthoceras...... ------------ — -.__ — -_- — -._-_ ——._ ——— —— 2

Canada, Triassic nautiloid occurrence.-- — ---_-____- — __ —— - —..._._ — -. 3

cancellatum, Orypoceras (Orypoceras).---- ... ..-_- — --__ — ——.---_.- — —._ 53

carbonmus, Pleuronautilus (PleuronautUus)------------------ ___-__--. —— -_. 36

carinatum, Metacoceras (Metacoceras)... —— ----- — _-___ —— - — —— -------- 20

carolinus, Syringonautilus—— ——_____--_- —— -.__ — _--_.. —— ------_.._-_-- 60

cassianus, Oermanonautilus....-------------.---- -------- — _.___ — __-. —.- 28,30

Te.7mocfee.ZBS--_________------- — —._--- — __---__-.___- ——. 21

cassis, Paranautilus--.-.. ...—— —— -__- —— -_-- —— --- —— - —— --------_.— 69,71

cavatiforme, Metacoceras (Metacoceras)—— — __.--._ —— -_.-_-_-. —.- —— -_. 20 

Metacoceras_______.--._-___-__--. —... —— ___ — _ —._ — ___ — _ — _— 19

caDatum, Tainoceras... .-..--_--------—_.---. —.--.--.-.-. —— _-__ —— ___- 25

Ceratites trinodosus- ____——————_————————- ——— _ —— _————— 30,64,71

cheneyi, Metacoceras (Metacoceras)--- .....— — _--- —— —— - — _-- —— —— — 20

chittidilense, Metacoceras (Metacoceras).- —————— —————— _.——————— 20 

cicatricosus, Clydonautilus....————— —— _- — ------- —— - — ——— ——— 9,88,89

Classification, nautiloids—._.. —. —— __ ——— —— -__ —————— — — -. 3-5 

clathratus, Pleuromautilus (Trachynautilus)........ —... ———.——-- —.-. 44

clydense, Tainoceras—... _ — —————— _ — —— — _ — - — - — —— —— — — _ 25

Clydonautilldae-------------- ........ — ..— 3,4,5,6,7,9,10,11,45,65,66,75-88,89

Clydonautilus.- — -——. .„...————— 5,7,9,11,12,66,75,77,80,81,83,88,89

acutUobatus... _--——__- — -__----—— ---_.... ——— ——..—————— 89

biangularis— _. —.--- ———— -_— —————— ----- ———— —————

cicatricosus—————— ———.. ———— —— -- —— ——— ———— —— ---

compressus---- ——— __ ——————... —— ————— --- —————— ----

glaber.

hesri-.-...-————— —————— —————————— 83

kieslingeri— — -—-..-—.——————-——————-——- 88,'89

noricus-—............................................................ .. 88,89

noricus timorensis.- ————— _ ———————— ————————————————— 89 

quenstedtL-- ___ — ———— — ---- ——— --- —— —— -----------------

salisburgensis.. - - - ———-———-- — —— -_- — - — -------------- —— ---

salisburgensis timorensis......................- —— —— -.-._ — ——————. 89

spirolobus...------______-_- ———— -- —..---_--_-- —— _.-. —— -_.. 82

triadicus-................... ——————.-.. — —— ---___ ——————— _.-. 81

Clydonautilus (Prodydonautilus) trtadietus.... .—....—.. _——————————— 81

spirolobus_-..__-.-—...—— —————— —— — -.----_.- — ————— —— 82

(Clydonautilus) spirolobus, Nautilus...-......-...------------.... ————— —— 82

Clymenonautilus..-——— — ——————————— — — 5,7,10,11,59,60,65 75

ehrlichi..............- _..._-_„......——.———...—-— 5,65, p1 . 7

Coelogasteroceras._----------— —— -- —— ------- — — -- — ——— ——— —— 12.66

Coelonautilus-..------------------ ...- — - — __- —— --------- —— — ———.--. 28

coloradoense, Metacoceras..... _———._---__ — ---. —— __-_ — ---- ——— —— 19

Columbites.-.—-................................. ................ 2,24,30,31,38 42

eomplanatum, Orypoceras (Domatoceras)..... ——— — — ————————— — _ 55

compressus, Clydonautilus—————————'..-_ — -- — — ——————————— 89 

comptum, Tainoceras................ ———— ——— ——..——————————— 25

conchiferum, Stearoceras......———— ———— ——— ——— ——— ———————— 58

95
96 INDEX

Condraoceras__---_-__--_.__-.-_-

connectens, Pselioceras. _.--________.

convolutum, Pselioceras.............

cooperi, Grypoceras (Gryponautilus).

Page

66

59

61

56

GryponautHus--..-........................--......-------......... 3, 55, 56, pi. 7

Pleuronautilus (Phuronautilus).........................................._ 36

Stenopoceras.............................................................. 58

Cooperoceras........................................................... 4,12,13,25,27

texanum........................... ...................................... 4, 26

cornaJiae, Pleuronautilus (Pleuronautilus)--.-------.--..-.- .................. 36

cornufum, Metacoceras........................................................ 19

Metacoceras (Metacoceras)..... ____._._____.__.__________-.---_-__________. 20

cornutus, Acanthonautilus..................................................... 66

Nautil'is --...-..--.....-...----............---.--..-.----_--..-.------.__ 74

toronatus. Nautilus (Temnocheilus)--........................................__ 4,17

Cosmonautilus--............^.............. 3,5,7,9,10,11,66,75,77,81,84,85,86,87,83

dilleri....................................................... 3, 5,84, 85, pis. 12-14

spiralis..........................._................__.____..__.. 85

hersheyi-....................................... .................. 3,85,87, pi. 10

jonkeri--.................................................................. 85

malayicus--............................................................... 85

pacificus.--........................................................ 2,3, 85, pi. 16

shastensis-..................................................... .. 3, 85, 8(1, pi. 15

(Cosmonaut it us) dilleri, Proclydonautilus ................................ .... 85

costatum, Metacoceras (Metacoceras)............................. .---___.-_.___ 20

crassescens, Pleuronautilus (Pleuronautilus)------.-----.-... ................ . 36

jugulata, Pleuronautilus (Pteuronautilus).................................. 36

semijugulata, PJeuronautilus (Pleuronautilus)--......... .....--.-__.______ 36

crassus, Temnocheilus......................................................... 21

credneri, Syringoceras......................................................... 61

crux. Nautilus. .............................................................. 4, 27

Tirolonautilus-........................................................... 27

Cryptoceras-.................................................................. 12

D 

DaoneVa.. ............... .--.............. — -............-.-..................

Daonella dubia ............................................................. 30,

debile, Tainoceras. ------------------------------------------------------- _ ._

delidosum, Phloioceras. --_----___-_____---_--_____-_-------.___________ _._._.

Diadiploceras- __._.:.___.__.___........_______.......________.................

dientri, Pleuronautilus- _______________________________________________________

Pleuronautilus (Pleuronautilus).-----------------------------------------.

dilleri, Cosmonautilus- -----.............---.-................... 3, 5, 84, 85, pis.

Proclydonautilus (Cosmonautilus) -----------------------------------------

Cosmonautilus.--. —---- — - — ....- — --......-.------................-

discoidalis, Styrionautilus -----------------------------------------------------

discoideum, Metacoceras (Metacoceras) -----------------------------------------

(Discus) sangamonensis, Na utilus ---------------------------------------------

distinct us, Pleuronautilus (Holconautilus) --..-.-....--..........--..---------.

dolomificus, GermanonautituS- -----.-........--.......... ....................

Pleuronautilus (Pleuronautilus) -------------------------------------------

Do matoceras- _________ ........... ...... 5,9,10,11,20,45,47,48,51,54,58,59,63,

arthaberi. ____________.--_-___________----________-_--______--. .-------....

bradyi. ---------------....-........---.........--.... ... ------------ ... ...

hunicum— ----------------------------------------------- ... .-_.__-.-_....

2,80 

71,72 

25 

45 

12 

38

36,38 

12-14

moorei-- --- 

mosquensis. 

northropi- _

parallelussculptiJe- - 

shepherditoddanum-- ---------- ..-...--...........-......-...----........--... ......

umbtticatum,- --------------- ... _.___---.-.__ ..__-..-.._-_ _ ............ 5,

walteri... _ ..._ _ -.„.........- ___-_.-..______-.-. _ _ _ . _ ..........

williamst,- ---------------------------------------------------------------

(Domatoceras) arthaberi, GrupoceraS- ..... ------......... ------------------- ..

bradyi, Grypoceras ----------- --..........-.........---.....-----.........

complanatum, Grypoceras- ._...._......--_..___......-.-_......-_--__-....

fredericksi, Grypoceras---- -------------------------------------------------

hunicum, Grypoceras-.--------- ------------------------------------

inostranzewi, Orypoceras.— ............— ......-----.... — -- — .....

kleihegei, Grypoceras..---------- _.... _--.........._-......... ______

krotovi, Grypoceras --_.__--________---_--_-________--_______--__-____

minimum, Grypoceras-— _._....._.___----..__.____------____.. ......

moorei, Grypoceras.- .----........-.-..........----..................

mosguensis, Grypoceras. . ... ..........^.. .......--.-.--...-... ....

9,80 

20

4,19 

42 

28 

36

66,85 

51 

51 

51

48,51

48,51 

51 

51 

51 

51 

51 

51 

51

51,54 

51

48,51 

55 

5* 

55 

55

53,55 

55

55,57 

55 

55

55,57 

55

Page 

(Domatoceras) arthaberi, Grypoceras—Continued

nikitowkensis, Grypoceras . __________..._-_____-____----_________________ 55

northropi, Grypoceras _-_--__---_--_-_-__-_--.______-_____________--__-.___. 55

obsoletum, Grypoceras _-_-_-__________-___-___--_--__-____________.________' 55

parallelum, Grypoceras ____.____.________.._______.____.__.._._.. ......._ 53,55

planovolve, Grypoceras------ -_______-_--_-_-___-------___-______ .......... 55

sculptile, Grypoceras- ._ .__-_.-_-______-_-_-_.----.--_-..........__.__ 55

shepherdi, Grypoceras ................ ------------------------------------ 55

subquandrangulare, Grypoceras.----.--.-------------------------------- .. 55

umbtlicatum, Grypoceras--------- ... ___-___________.---......___._______ 55

walteri, Grypoceras—--------------- ______-___-_-_--___-______-.--__-___.., 55

wittiamsi, Grypoceras ____________..__._________^___.____ . __.____.__ 53,54,55

Domatoceratidae............................_............................. 45,54,59

dorini, Pleuronautilus (Pleuronautilus) __________________________________ __ 36

dorso-armatus, Pleutonautilus (Pleuronautilus)---------- ________....._...... 36

doubreeanum, Syringoceras. .._____._.______.__-______-_-_---._._..________.___ 61

dubia, Daonella....--.------.---------.---------------------------.-.-- .. 30,71,72

dubium, Metaccceras (Metacoceras) .____.------_____.-.-_--______-_______. _. 20

dumblei, Phacoceras, ..____-__---__.. __________...________._---..__._..___.____ 5,57

Stenopoceras------.-.------. .________.--_________--________._____.-_----.. 58

duttoni, Tainoceras—---------- _-_,___.___-_.-_--____---.-----_____--__--_--- 25

dyadicum, Fooridiceras.------. —------------------------------ _____________ 19

E

ehrlkhi, Nautilus.----. .-..___-_ . _____--_._-____-_---___-___________-----._ 5,65

Enclimatoceras_.._...--.--.-- ___... _________._.._______-....._.....__ —... 12

Encotloceras. ......... _.._____..______...._. ___-_..---..____._____ 5,7,12,17,33,_#

suferbus.-.........-..--.--.....--.--.---.-..-...----....----------...---. 42

(Encoiloceras) superbus, Pleuronautilus__..--......-..--.---..... ._._.____- 43

JSndolobus,------------------ —...-.-.- — -......--—......-----.--.-. — ...... 12

gibbosus ___.__._.____-_-_____-_-_--_-________.._-_--_---___-.--_-_.____- 5,58

Enoploceras—-.------------------------------------------- 4,6,7,12,17,33,39

(Enoploceras) ausseeanus, Pleuronautilus——_-_-_--_-_-___-----_-_-_____.___-- . 41

fischen, Pleuronautilus-.------ — -- —--------------- _______--._-.. —... 41

gaudryi, Pleuronautilus-—--------.-....---...-. ._-----.--._.-.-_-.._-.--. 41 ^

kossmati, Pleuronautilus---.--r --- —------------------- .................. Jl

lepsiusi, Pleuronautilus-.-.--.........-------------------------.--..-.-... 41

lepsiusiformis, Pleuronautilus-.---.--------------------. .--.--.-.-.--. ... 41

malayicus, Pleuronautilus-- __._.__.__-_________.__.--.---_-__-_._-_---_-.. 41

molengraaffi, Pleuronaitttlus. _.......------..-.-.----__---....---_.._-_.-, 41

neivelli, Pleuronautilus. —— _....-..----.. _-.____.-_.________.-. —.. 2,4^,pi."1

planilateratus, Pleuronautilus.--------------------- -..........---.----.-. 41

pseudoplamlateratus, Pleuronautilus--..------.-....----.-........-.- —... 41

pseudowulfeni, Pleuronautilus__..____._.__.__-_-_----_. ......._....._.. 41

semseyi, Pleuronautilus-------------- -........---.. _.._-_._._.---_-_--_.- 41

tibeficus, Pleuronautilus--------------------------- -------- -------------- 41

wulfeni, Pleuronautilus------------------. -..'-.----.... — ...-.-..-........ 41

wulfeniformis, Pleuronautilus-.---------------- — _____-.... — __ ....... 41

ermoUii, Proclydonautilus---- .....i.-..----- — ---.. — -.-- —--......---.-----.- 9,81

esinensis, Pleuronautilus (Pleuronautilus)------------------------ —..... .... 36

eugyrum, Syringoceras__._._-- ------- .-_---...-...----..--.--.-----------.- 61

Evolution, nautiloid.-------------------------------------------------------- 7-11

eeolutum, Syringoceras---------------- — -- ---------------------------- — --- 61

externecavatum, Syringoceras—____-..__-_--__-_-_--__----------____-_--------- 61

eiternelobatus,fleuronautilus (PleurcnautUus) ....—...--.........-....———— 36

F

falcattim, Metacocens (Metacoceras)-.-------------------- —------------------- 20

fergusoni, Sibyllonautilus.— _-___-- _.-____-----_----------------.-------- 2.7^,pi. 8

fischen, Pleuronautilus (Enoploceras)--.---------------------- --------- ------ 41

flemingianum, Foordiceras . -------------------------------- -- — ----------- 19

Foord, cited--.-.-.--.-------------------------------------------------------- 33

Foordiceras----- . — — .-. —- — — -- — — . — - 4,12,13, 17, 18,19.2*', 26,27,33,34

dyadicum- -....---....-..--....-. — -. — ------------------------- — ------- 19

flemingianum..----------------------------- —------------------ -------- 19

goliathum.- —------------------------------------------------------------ 19,26

grypoceroide..---------------------------- --- -- —.-.-------...---------- 19

loczyi.---------------------------------------- ------- — ----------- —.- 19

nodosocostatum---------------------------------------------- — ----- — -- 19

pleuronautiloide.----.------------------ - -------------------------------- 19

sumatrense—_..____.-_----_.-- — ----------------------- — - ——.-.. — - 19

ufimskemis---------------------------------------------------------- ---- 19

fredericksi, Grypoceras (Domatoceras).---—------------------------------------ 55

frenchi, Metacoceras (Mojsvaroceras) __-____--- ..-____---------.----- 2, £1, W, pis. 2,4

fugax, Tainionautilus—------------------------------------------------------- 27

furcatus, Pleuronautilus (Pleuronautilus)---------- —.---....--^--..--..-.--- 36

furlongi, Germanonautilus.—.---------- ---------- —— - — -- —----- 2,28,^9,pi. 3
INDEX

G Pa.e 

Gabb, quoted.--.____---_-_____-_-_-____---_--______-___-_____----_____-_ 53-54,71

galeatus, Grypoceras (Nautilus). _____________________________________________ 57

Gryponautilus--. _-___-_--_______-_______-_______---____-_______ __ __ 48,55,56

Nautilus--------------------- ------------.-- — ------- — -------- — -----.-- 5,55

gasteroptychus, Proclydonautilus.-------------------.-------------------------. 81

timorensis, Proclydonautilus----------------------------------------------- 10,81

gaudryi, Pleuronautilus (Enoploceras)-..... — _...._........-.-.-.--....... 41

gemmatum, Phloioceras--.----------------------------------------------------- 45

gemmatus, Nautilus—---------------------------------------- ---------------- 5,44

gemmellaroi, Temnocheilus- __. ______-__.----____.._-___---___-_-__-___-__-____ 18

geyeri, Juvavionautilus---------------------- -_-__ -______--____.__-_-_--___- 63

geyeriformis, Juvavionautilus. -___-----___---__--_-_._____-___-___-_________-__ 63

Germanonautilus— ________________________ 4,6,7,9,12,13,21,25, US, 29,30,31,32,66,74

advena-------------------------------------------------------------------- 28

bidorsatus- ____________-____--__------___---_____---_---__-_____-_---_-_-__ 28

breunneri-------- — -----------*------------------------------------------ 28

brooksi ---------------- ____-______.--_______._______.__-_... 3,28, SS, pi. 3

cassianus.--------------- _____---.__ _.__-_.___-_-____---__._______ 28,30,32

dolomiticus_._-___--____--_--_----_--------___--____-________----- .-...- 28

furlongi-------------- -------------------------- ________________ 2,28, 89, pi. 3

johnstoni__ --.-__________--___---____----_____________ __________ 2,28, SO, pi. 3

montpelierensis- _---__.-_____-----_-----------____--.-_-_-_-_----_- 2,28,30, pi. 3

nodosus,-----------.------------------------------ --------------------- 28

salinarius.------------- ______.__-_--_. __-_--_.__-_.-__-_----____________ 28,29

schloenbachi--------------------------------------------------------------- 28,30

spumosus...-------------------------------------------------------------- 28

SMes.cw*----------------------------- ---_-----------------------------_--_- 28

SPP.-. —— - —— -——.-- —— - —— —— -.--- —— - —— ....- —— —— .--- —— .

gibbosus, Endolobus...-----------. --------------------------------------------

StearoceraS----- -------------------------- -------------------------------

glaber, Clydonautilus __--_-____--_.__-.--___--_-_._____---__---._----____._____

globulare, Liroceras -_____--_--___-----__---------____--___-______-________-._.

goliathum, Foordiceras— ---------------------------------- ---------------------

goliathus, Nautilus- -______--_____.----__-------_-.--__ — __-_______-_. 4, 12, 17,

goniatites, Proclydonautilus--- ------------------------------------------------

Qonionau tilidae _-__-___----____------_.--------__--__ .--._.-.-.---- 5, 7, 9, 11,

GonionautUus _ ______..____-._____--__. ------___-_______________.___- 5, 7, 66,

securis- __-__--______--_________-__--_-______--_-______-____._________ 28, 9,

granulosostriatum, Syringoceras. ------------------------ ----------------------

gramtlosostriatus, Nautilus------ ------------------- .__._-_______ - _..___.__-

Syringoceras --------------------------------------------------------------

greenei, Liroceras _ -__-__---___-----------------__-________-.___.___._______-

gregarivm, Pleuronautilus (PleufonautUus).- . . ._________-.__.____-_______._-_

grewingki, Temnocheilus-- — ----------_------.--_________.__________.-_..-_._.

griesbachi, Grypoceras (Grypoceras) --------------------------------------------

Nautilus ... ----- ----------------------------------------------------------

Proclydonautilus --------------------------------------- ___--_________.__-

Grypocfros---- ----------------------------------- 5, 6, 11, 12, 46, 47, 48, 54, 55, 57,

brahmanicum- --------------------------------------------------------- 2,

haloricum--- ------------------------------------------------------------- .

hexagonalis— ------------- ---.-----------.-_____-_-_-__,__________________

involutum.---- -------------------- — _-_-_.-___. -_-_-__-_---_-_-________-_

laubeL— ------------------------------------------- ----------------------

mesodicum- ---------------------------------------------------------------

milleri- _----..---.------------------.--.-.-......__._-._._.-._._._________

obtusum- -,.-.-----------------------------.---.-----------------.-------.

pattadi _ ___-.---_-------_---_-------_-_-_-_____-____-____-_-_.. ___-_____-

privatum __ _.-__-___.. -___-_----_-______-____-.._._-_.._._._._._-_--_-_-

whitneyi- ------------------ -----------------_--.----.-...-.-__.......___.

Grypoceras (Domatoceras) ---------------------------------- ...^ 54, 55, 57, 58, 59,

arthaberi- _-.____- ____--_____.-__-_--_--_,____._.__._-_____________ .,._..

bradyi __ --...---------------------------..---------...-...-.-._..._. ____

fredericksiftMTM'CWm.-

kleihegei- -----

krotovi --------

minimum _ - 

rnooret--------

mosquensis 

nikitowkensisnorthropi __ _ 

obsoletum. ____ 

paraUelum __ 

jdanovolve _ -

sftepfterdL

5,58

58

19,26

18,34

81

75,89

75, 89

pi. 19

61

5

60

69

36

18

53

5,80

81,84

66,73

47,51

51

61

47

51

51

10,51 

47 

51

51,54 

51 

51

61,63 

56 

55 

55 

55

53,55 

55

55,57 

55 

55

55,57 

55 

55 

55 

55

53,55 

55 

55 

55

Page 

Grypoceras (Domatoceras)—Continued

subquadrangulare.-------------------------------------------------------- 55

umbilicatum-------------------------------------------------------------- 55

walteri----------------------------------- __-------_---------------.------ 55

wttliamsL—.-.---.—-——- — — — — - — ——— — -— — — 53,54.55

Grypoceras (Grypoceras) - 

brahmanicum- -.___- 

cancel tat urn.. .-__-_ 

griesbachi---------.-

guembeli- _ ________

hexagonalis 

irwolutnm - 

lambei.-- ...

..- — _------_-----------.--- 54

-_--_-- — - — ------------- 53

..-- — . — ...- — .-— — — — 53

.-.-.. —— - — — --.„ — -. 53 

_- — ____- — - — . — -_-- — — 53

- — --- — - — — — —-„ — 53

.___..__.__-___ --__._-__-_.__.-. 53 

_-__-_-. -.- — — — -.-,.-.... 53

_.---_-_--_ — — _ — -- — ---—.— — - — -—-- — — ---- 63

lilangense---,------------------------------------ -.__-_-----_-_-_----__-_-_ 53

mesodicum-----------.-- ------------------------------- —~ 51,55,55,1:1.5

roJHeri- — --- —-- — _----------------.- — ----- — ----- — --.- —--------- 2, 53. pi. 6

olitusum,- ----------------------------------------------------------------- 53

paHadi—--.—--. — - — -—— — — — — — - — -------------.—--- 53

privatum__-_-__.._.__--.-____.-_-_------_-_-.____-------_--------_.-— 53

gwadrawe«?M'ffl-------------------------------------------------------- __- 53

vihianum--------------------------- _---------._--_-__--_-_-____-.-__— 63

whitneyi--....-.-.----- _______--____--______--_._____-________--- 2,53,pis. 5,6

Grypoceras (Gryponautilus) cooperi-----.---.-.------- —----------------------- 06

Grypcceras (Nautilus) galeatus. ______--___-_______--______--____------______-_- 57

Grypoceras (Plummeroceras)-------------------------------------------------- 54

_--_.____-.--_-_---— 51, 54, 55, pi. 5

_ — ___-_-.-- — _- — - — . — — 53 

.- — - — .- — ..- — .—. — .-. 53

- — . — -„ — - — — ...- — -— 53 

___._..______-.-.____--.-__-.-__- 53

-- — ....- — — . — — .. — --- 53

---__.---_-____--- ______--_.- 63

._..-__-__-.-__.__.-_.-_-_-_-_ 63 

____--.--___----_ ___ _-.____- 53

-..----...--. — .— . _ - 53

mesodicum, Grypoceras _-_-.._____._.-______.._____----_-____. 51,53, 54, 55, pi. 5

mitten, Grypoceras- ____-_----_-__.._-__-_----___-----__-_--__-._ 2, 63, pi. 6

obtusum, Grypoceras.-... _---——-._----._-_-_--____------._-_- --.-__ -- 53

palladi, Grypoceras——— ------ — --___-.——.___--..-_--_-.--_____--_-__-- 53

privatum, Grypoceras__.---___—--.__-_----____-----_____-----___----__- 53

quadrangulum, Grypoceras. ________--__.___---_______-_____-_--_--_._._--. 53

riftianum, Grypoceras—-------------------------------------------------- 53

whitneyi, Grypoceras--------------- __--_--_------____-----_____- 2, 5S, pis. 5, 6

Grypoceratidae—— -- — ——. — ————.— - 3,4,5,6,7,9,10,11,45-59,77,85

grypoceroide, Foordiceras------------ ______-_---_____-_-_____-_-__-_--_--- 19

Gryponautllidae____-.--____------------__----__---_--____----_.__- 4 4c

--------- 5, 7, 9,10,11,45,47,48,55, 57,85

cooper.__-__-__ -_--__----------_------__------_----------_----- 3, 55, 56, pi. 7

galeatus-- _______-_______.__-----__-__--..__-_.-..-_- 48,55,56

-_---.---_------__-.-----.__----- 55 56

-----_.-----_----.---__----___-- 56

-___---__-- — -__------_- — - 56

------__-..---._.-----._-_.---__- 51

- _---__-----__----__-_— 53

(Grypoceras) brahmanicum, Grgpoceras. 

cancettatum, Grypoceras- .-___-__.-_ 

griesbachi, Grypoceras- ..__.____._--

guembeli, Grypoceras--. —-------- -

haloricum, Grypoceras..--.- — . — --- 

hexagonalis, Grypoceras_ __..___-_. 

involutum, Grypoceras__-_-_______

laubei, Grypoceras______________

lilangense, Grypoceras_-_-______-.

messiformh—-----------------

cooper., Grypoceras..----------

gumbeli, Grypoceras----—,- — _.

guembeli, Grypoceras (Grypoceras)-

H 

Halobia-..— ——. — — — —-—— — — .——— — -—.—.-- — — — ~ 31

haloricum, Grypoceras—.------------------------------------------------------ 51

Grypoceras (Grypoceras)-------------------------------------------------- 53

harneri, Temnocheilus____-_--__._____________---_____--____---_^___----_-_-. 18

hayi, Metacoceras.-, _.._---------_--_-___-_-__-__.---__-_-----__-._----- 19

Metacoceras (Metacoceras) __-_--.___-__.-..-.....-.._.-_----..-_--_ 20

Iledenstroemia-.---,--.------.---------.---------------—--------------------- 38

Heminautilus-.——__— ---------——_^_ ------------- —. — --_-.----___---- 10

Hercoglossa--.—-——.. — .-—'-——..————.-——— - 10,11,12,75,77

hersheyi, CosmonautUus------- _.-__.•_._-_______.__-_-__. 3,85,S7,pl 10

hespermm, Stearoceras__.---_-_-------_-.---____---__-_----__-_-----_-_--— 58

hessi, Clydonautiius----------------------------------------------------------- 83

Proclydojjautilus.----------------------------------------------- 3,81, S3, pi 15

heterophyllus, Juvavionautilus —---------------------------------------------- 63

Nautilus--.---- — --------.--.-------------____._.-.-_ _____---- 5 63

hexagonalis, Grypoceras- _------------------- —— -_------- — ------------— 47

Grypoceras (Grypoceras) ___._-------__.------_--.----_----_----_--- — _ 53

highlandensis, Stearoceras--—------------------------------------------------- 58

History, geologic, of nautiloids------ — -----------_-------- ——. — — -_-__ 5-7

hoernesi, Tirolonautilus- ---.---_--_---------_-------_------.------------------ 27

Holconautilus—.__.._.-.................—...._------- .. 5,6,7,10,12,17.42
98 INDEX

Page 

(Hokonautilus) distinctus, Pleuronautilus--.. __.__.____...___________ 42

intermedius, Pleuronautilus..------------ ______________________ 42

pichleri, Pleuronautilus.... ________________.____________ 42

ramsaueri, Pleuronautilus.—----------... _________________________ 42

scabiosus, Pleuronautilus-- ___________.__________!________ 42

semicostatus, Pleuronautitus_________________________________ 42

singular is, Pleuronautilus------- __-------_.._____________________ 42

stautei, Pleuronautilus----- __-_----------_______________________ 42

striatus, Pleuronautilus -------------- ___.____________________ 42

Huanghoceras___.__________._.__________________________ 34

hunicum, -Doma?oceras__ —.---_-_-__ _ _ _______________________________________ 51

Grypoceras (Domatoceras) __.--_-__-._____________________________ 53,55

Hyatt, cited-______-----------------------------_--_-.______._______________ 44

Hyatt, quoted._________________________.-_.___.____________... 48,60

Hyatt and Smith, quoted______.____________________________ 84,85

idahoensis, PleuronautihiS— ------------------------ __________________________ 34

Pleuronautilus (Pleuronautilus)—--- .... __---_-________.___ _ _ _ _ 2, 36, 57, pi. 4

inaeguilateralis, Temnocheilus --.__. _ ____ __ ___________ _ ____ _ ___________ 18

inaequiseptatum, Melacoceras (Af_.acoceras)__--_-__ — ______—__— ______________ 20

incertus, Pleuronautilus (Pleuronautilus)- _ __--____ _ __________ ___ _ _ ___ 36

inconspicuum, Metacoceras .. -_---__--_-------_----.__________________________ 19

Metacoceras (Metacoceras) ______ _ _-_----_--_._______ _ _________ _ _ _ 20

indifferens, Paranautitus - _-___-_--. _ _ _ _ ________ _ _________ _ ___ _ ____ 69, 71

IndonaiMlus--.-- _ ______ _ _ _ __ _ _ __-_----_____________ _ ____ 5,7,66,72,75

kraffti--—-- - — ----------.--- — .----- — - — — __.___——-. 73, pi. 18

— -_-____-_-...-.__.__.__.-.. 73

_ _______________ __ __ ... 58

_ _ ________ _ _ _ _____ __ 81

-__-_--_______________ _ ____ 58

__ _ _________ _ ____________ 55

_ _ _ _ _________ _ _________ 42

ineipectans, Stenopoceras . _.-_._______ _ _. _ ____ _ _______________ __ __ .

inflatus, Proclydonautilus. — -- — ________________ _ _ _ ________ _ _ _ _____

ingens, Stearoceras--.-- _ _ _ ____ _ _____ _ _----__-_--_______________ _ __

inostranzewi, Grypoceras (Domatoceras) __ .--.___ _ _________ _ __________

intermedius, Pleuronautilus (Holconautilus) - ______ _ _ _ _________ _ _______

Introduction— _——___———____—_ — ______. ——_____ — ____.__________________ 1-2

involutum, Orypoceras. — --—__— ____—- — — — ____— ___________ _ _____________ 51

Grypoceras (Grypoceras) _--__----_-.___-_-.________ _ _____________________ 53

jacksonense, Metacoceras (Metacoceras)-------------. ------------------ ___ _____ 20

japonicus, Syringonautilus— ---------- _ __.__ _ _ _ _____________ _ ________ 60

johnsoni, Temnocheilus __ _________ _ _ _ ..-__________ _ ____________ _ _____ 18

johnstoni, Germanonautilus-—. -___-------_-_--------_____________________ 28,50, pi. 3

jonkeri, Cosmonautilus- --___--------_---__--_--.______________________________ 85

iugatonodosus, ThuringionautUus _ _._ — — -____ _ _ _ ____ __ _ ___ _ _ 25,52

Trematodtscus. ____.---_________ _ _ _______ __ _______ __ __ ___ _ _ _ 4,32

jugulata, Pleuronautilus (Pleuronautilus) crassescens __ ___ __ __ _-..-. __ _ 36

Juvaeionautilus- ------- ___ ___________ _ _---.__________ _ _____ 5,7,9,10, 11,59,60,65

brouweri-.-- _ ____ __ ______________________ _ ___________ _ ____ __ _ _ 63

-------------------------------------------------------------- 63

geyeriformis- _ ____________ _ __,.___•________ _ _ ___________ ___ ______ 63

heterophyllus------. ___ -_------____-_-_-_-.______________ _ ___ __ _____ 63, pi. 18

subtrapezoidalis--. ___ _-_______---_-_.___.___ _ ____________ _ ___ __ _ 63

trapezoidalis---- _ _ ____ _ _ _ ______________ _ ______ _ __ _ ____ __ 63

Juvavites. ________ . _____ ____ _______ _ _______ __ __ __ 56,82,83,85,86,87

kagae, Metacoceras (Mojsvaroceras)_________________________________ 21

kasarmenskensis, Pleuronautilus (Pleuronautilus) ___-------_-_-___-.__________- 36

kashmtricus, Paranautilus-..--------. -------_____________ ____________________ 71

kellneri, Metacoceras (Mojsvaroceras) ______________________________________ 21

Kieslinger, quoted-...__________________________________________ 87

kieslingeri, Clydonautilus.-. ___.---_ ____._______________________________ 88,89

Menuthionautilus- _______________-_-_._____________________________ 57

Nautilus (Menuthionautilus)----... --_------._________________________ 5, 57

kleihegei, Domatoceras- _______________________________________________________ 48

Grypoceras (Domatoceras).- _____.----_.________________________- 55,57

klipsteini, Tainoceras- ————__--_-_-------_-.__.---_-.__________. 7.25

ThuringionautUus- _.._____-----_-_________ ____________ 32

Trematodiscus - -.. - _________-____--_-----.__________________________ 25

knighti, Metacoceras (Metacoceras) — ____--__--_-____.___________________ 20

kokeni, Pleuronautilus-.... ___.________..____________'_______________ 38

Pleuronautilus (Pleuronautilus) ______-______.-----.--_.-----_______ 36

Koninckioceras. __..__..____________..__._____________ 45,48,54,58

Koninckioceratidae_-.________-._----_«----______________ 54

kossmati, Pleuronautilus (Enoploceras)--------- __-_-_---.--__________ __ 41

kosswae, Temnocheilvsposttuberculatus-- —---------------... ____..--_..__ 18

Page 

kraffti, Indonautilus.... __. _________-_._______.._________ 73

Nautilus—-——- .................——— ........ — .-............... 5,72

krotovi, Grypoceras (Domatoceias) __._____-_______..-_______.---.— 55

loczyi, Foordiceras____..--____________._____________.----.__ 19

laevis, Pleuronautilus (Trachynautilus) - __-----__-_-________-___.-.-_-.-_ 44

Iambi, Metacoceras (Metacoceras)----..----------- ______ ——._ — _____--._.— 20

lasaUensis, Stearoceras—..-.-.. -____ —— ___ ——.. ——__.._._.——.__-______.-_ 58

lattissimus, Pleuronautilus (Pleuronautilus)- _______---__------.-- —— __ 36

lotus, Temnocheilus---------------..-------.-.----------.------------ 17, 18, pi. 1

laubei, Grypoceras________— — __.——___ — ______________________________ 51

Grypoceras (Grypoceras)-.—-------- .... _______________________ — ____—— 53

lepsiusi, Pleuronautilus (Enoploceras)-. ______._____-___-_-_-___-.___-___ -___ 41

lepsiusiformis, Pleuronautilus (Enoploceras) _————____--___ ___ __________ 41

liardensis,Nautilus--..---..... .....--.-. — -...--- — -- — - — .................- 75

Paranautilus-___..__---. ———— -___ — -_-_-_-_-________-----_._-_-_--_---- 75

fiS6yno7.ai.tfftM_-----------.-------------------------------- 3, 73, 74, 75, pi. 14

lilangense, Grypoceras (Grypoceras)—------------- -__---__-------_--_-_---- — __ 53

liUanus, Nautilus. —— - __—__——-___ — _._--________ —— __ — _ ————._. 5,60

Syringonautilus--- _--.--_.---_ — _________________________________________ 60

linearis, Nautilus, .___-_-_---- — —.........—— _______________ —— — _____ 60

Syringonautilus.... ______________ — _________ — _________ —._-_-_--..-_ 60

linchengense, Pleuronautilus (Pleuronautilus).-—- _____________________________ 36

liratum, Lyroceras____________-_____--.-__----__—_________._._______._--.-.__ 69

Liroceraa——--— — --.---.— — --- — ——--———-——---— 11,66,69,74

globulare..--_. — _—.___. __— — -- —---- — .— — _ — — — _ ______------._-. 69

liratum...—---—— — — — ---—- — —— - — ----- — —— — . 69

obsoletum... __________-___--____________--._---_ _ _.____._ —— _____ 69

Liroceratidae.--- — ——--------------- ---- ---------------- 7,9,10,11,66,69

Litoceras... ________________-__-___----------------------------------_--------- 1?

longinodosus, Pleuronautilus (Pleuronautilus)------------ ..................... 36

longobardkus, Syringonautilus——_ — __——— — _ — --_— —.---_-_-_.____-__ — - 60,63

Loretz, cited.___________--_--- ._______.______-___-__--_____--_---._---__-_- 43

M

mckeei, Aulametacoceras..--------------.--------------------------------- 4,13,

McLearn, quoted.__—__.--_------_ — _________ ________________ — _.---.—

magnicostatum, Pleuronautilus (Pleuronautilus)---------- .___--_________-_-_.

malayicum, Syringoceras.-..----- .... __ — ------ .-_--. —.__-._-.__ ——.-.-.

malayicus, Cosmonautilus-—_-_-______. _ -_-_-_____-_---------. — -_--_ ———

Pleuronautilus (Enoploceras)——___._-__ -___-_-.____....._ —._..--_-_._

mammiferum, Metacoceras... —----- ——— _-_.---_-__._——_________________._

Metacoceras (Metacoceras). _____-- — ________________________ — __-___-_-_.

mandevittei, Proclydonautilus—-.-.--—— __-_____-_-_-_-_-____. --_._._ — ______

mariani, Pleuronautilus (Pleuronautilus)--------- __________________ ———._

marmolatae, Pleuronautilus (Pleuronautilus)--—-----------------------------

medlicottianum, Metacoceras.-... _________.____________-—_-_-_-_-___--- — _____

Metacoceras (Metacoceras).— ----- ... ___---._. ——. — — _.—_ ___ -_-_-.

medioventralis, Temnocheilus-- ______ — __ —— — ._ — -_ — _-..___. _._._. —1_. ____

Meekoceras....... ._ —— _____ — ________-_-___--_.---_----__--_-__-.—__ — __

megaporum, Pleuronautilus (Pleuronautilus) ---------- — _ — --._ —— — — — .__

Menuthionautilus—.———----—- — ---- — — 5,6,7,9,10,11,45,47,48,54,

kieslingeri-............ . ————— _ —.-__ — -————---—————————i-

(Menuthionautilus) kieslingeri, Nautilus———. — _ ———.—————_ —— _.—— 

meridianus, Paranautilus...........-— _____-_ —— _-_-___.. ... — —— _ 69,71,

mesodicum, Grypoceras-..... —— ___ —— —.----__——_._.-__-.--. — _ ———._

Grypoceras (Grypoceras).... —_ — --_-_ __ — ___________ _______ 5J.5S, 55,

Nautilus—--.--___— — -.. — __.—.__-. — -_ ——— ________ — _--_- — _

Metacoceras— 4,9,10, Jl, 12,13,17,18, 19, 20,21,24,26,27,29.32,34,47,48,51,54,58, 

angulatum-....--___ — _ — — — -.----—-_- — — — — — — --- — — —_- — — -- —

biseriatum-.......-—. —— _. ——-—————_________ —— _—_____ — ______

cavatiforme.——__-_ ———_______________________________________________

coloradoense__._------__ — ___----_----- — __ _„. — _-_-_--_-_-—_-_-_-----

cornutum-------- —— -___- — __----__._____--_---__ ___._-_-_—.-_--- — _-

25,27

84

36

61

85

41

19

20

81

36

36

19

20

18 

2,39

36 

57,61

57

5,57

72,77

10,51

pi. 5

5,48

hayi.

...——.— —— -——. ———-— —— ——— — — - 19

--._-_--._--- — ------- —— -- —— ------ —— - 19

___-._—---------------------------------- 19

___-__ ——---------———,- — ------- — --------- 19

.___- — -—_.__ — _ — — ---— -----_— — ----- — -- 19

.__-.——--_-- — — —— - — ---—- — — — -------_ 19

inconspicuum ___.---_ —— __________________ — _________ — -----._--------- 19

mammiferum.- — - ———————— - — - ——— — -.-_•— ———____-.... ——. 19

medlicottianum.— ___- —— -.-___________---- — - — _. ___-_. _____-_____-_. 19

mutabile.... __ ———— _____-_-__.__-___-______- —— ——.___ —-._ ———— 19

nodosum....----- — — — — __.__*._ __________________.___.----___-- — ____ 19

sangamonense—— — —— ________— ———_-_-_—-- ——_ — _ — — — ---- — -_ 19, pi. 1

spinosus..--- __--__---_-_------.-------------__------ ------_------------_ 26

sublaeee——— — __ ——— — _ — _—_ —— .- — .—_ — ___ — — — — — ____--__-_ 19

sulciferum....... —————_.-.. —— ____-__------_-___ — ____ — ______ 13,26,27

walcotti..--—.-......----.-----------------------------.-------- —— ----- 19

sp. ————— _———.—- — - ———————— -—————----- —————— -- 37
INDEX

Metacoceras (Metacoceras) angulatum _____ __-.._ ..

armatum __ ------------ ....... ...... ....

baylorense .... ...... ...... ........... ...

biseriatum....- — - — . — — --....--- _ .. __ ....

bituberculatum.-- — . . .. .

carinatum —.. . ---_-.__-_--.-____--__ ....._..

cavatiforme .... -_ _______ --..... ....... _ .

cheneyi ...— ............. .. ......... — .....

chittidilense. -.---. .-.-..... .............. .....

coloradense.- .... ........ .... .... ... ... ... _ .

cornutum. ---------------- ........... .....

costatum .... ............ .. _. _ .............

dixcoideum.-- . ..-.-. ....it. ...... ......

dubium.--- ... ----- .. ...... — . ... .. .. .....

falcatum ... -------- ... .. .. ____ ---...._....

hayt-... -.- ..- --.----.-.. ---—-— --___.. -.

inaequiseptatum .... -_ ______________ _______

inconspicuum .. . ...... ___________ -______.

jacksonense.-- ... ..... ............. . .....

kmghtl— ..-- - — -—-..— -- — — — — --.- ...

Iambi-------..- -_-._ -------- _-. ...

mammiferum - . . . ..... __-.__ ....... _ .... _

medlicottianum ____ ....... .. _ _ ...... ....

muUituberculatum .. ... .... _ ..... ....... .

mutabile-- .. ....... .............. _ .......

nodosum . .... -. - ------ -... - .-..-.

ornatissimum.------.-- ... ... __ ...... _ ....

perelegans.. ... ...... ....... ....... _ _ ...

pernodosum ... -. - .. _ .. ---..... . _ --...

piszovi -..-- - .-.. -. ----- -. -... . ...

artiense.-...--.- ........ .. ______ ______

postcostatum—--— .. __ --------- ---------

pottsvillense .__ — ..____ — .... ...... ._ ___

reedianum...-- —-.. ... -... _ . — .. . ...

sangamonense.. . ....................... ... _

sinuosum----.-------.-----—.-. --------------

subglabrum... ----- -— ... .—. — .... . — ...„

subquadrangularis—. ... — ....... — _.__ .....

tricarinatum--.- --.-... ------------- -------

parvinodosum ... ............. ....... .. _

trigonotuberculatum-- ...... .... _....

tschernyschewi—..--- ... . .......... _ ......

tuberosum ..... - __ .. — . ... _-.--.-----..

unklesbayi.-.--.. ... ..._,- .. — .... .........

vagans. ... ..... ... _-___ ........ ._---. ... _

wakotti- ------ -.-.. ----- .. ... ...-.— . ...-

Metacoceras (Mojsvaroceras) augusti ..-.- .........

auriculatum.. — . — ._._--__-__ .--.......-..

binodosum. . ... ...... ______ __ — .-. .......

bulogense- __.---_... ... — .. .. - — - __ ...

fienchi. ------------ _ .... _ ....._ . _ .....

kagae-.-- ..... ... ...... ... ._______._- _. ___

keUneri- ....... .. . ....--. --......-.'....

morloti .... __ .-----._.___--. .... ._ . _______

neumayri.-.. ........... ... ______ .... _.__

nivicola. ................ .... ___ ____...____ ___

patens.. -----.--.--.-----..... ....... ______

perarmatum...-.-- ..... __ _ ...... -__-___

pironai. ....... ... _. __ —— .. — -_-.. — __ .

polygonium.--- .......... ........ .. .......

subaratum- ...---... ...... ....... .. ____

turneri.------ _-.-............. ____-._.______

ventricogum-- .... ________ —— _ ,___ __ ...

(Metacoceras) angulatum, Metacoceras.----- ......

armatum, Metacoceras ... .. — .. - — — . .,..

baylorense, Metacoceras ... .. __-_ _ -... _ __

biseriatum, Metacoceras .... ...... ... _ ... ...

bituberculatum, Metacoceras- ............. ....

carinatum, Metacoceras .... . _-.-.._--- _ ....

cavatiforme, Metacoceras--- __. _ _. -..----...

chittidilense, Metacoceras..---- .... .........

coloradense, Metacoceras _ _ ___ . __ „ ....

cornutum, Metacoceras- ...... ... . -__-__-____

costatum, Metacoceras-..-.- — ... . ...... .......

discoideum, Metacoceras. — -. — - .............

dubium, Metacoceras .-...-... _____'. ._._.___

falcatum, Metacoceras..----- -----------------

hay i, Metacoceras... ___ _.___. _ .. ... . _ _.

inaequiseptatum, Metacoceras ___ . __ ... ....

Page

.-. — -_--..-__..-______ 20

____________________________ 20

_ — ...- — ....-..-..-...... 20

._______._______._.______-_. 20

— .-_.._ — -._..___._______ 20

____________________________ 20

— -.. — — .,... — ........ 20

____________________________ 20

.____--._-__--__._-_.______. 20

....._-_..-.......-._.._.... 20

_-_-_-_._______-__-___.____. 20

____________________________ 20

— — — — - — ._..—...._ 20

...... — _ — — — — ..—. 20

________---_-.____-__._.__-_ 20

-_________.______.--________. 20

_-.- — - — ..- — — — . 20

____________________________ 20

--.-.. — --—— - — .... 20

_.. — — . — — _.—...___. 20

____________________________ 20

_.___-__ — __.____ — _____._ 20

.-__-______--____.____..__.. 20

.-.....— —..... — ....... 20

_ — - — --. — — — „..__._ 20

________-_---._-_-_--.._____ 20

_.-- — .- — ..- — .. — _._. 20

-_-.-... — — — . — -..... 20

........ . — ... — — ....... 20

..-.. — - ---_-.-__--____.._ 20

_________________ ___._____, 20

— .--_- — . — — — __.__ 20

____________________________ 20

____________________________ 20

- — — — — .- — „......_ 20

-.—.-.....-. — ........... 20

_ — - — .— .-- — — — — 20

------ — -----------_____ 20

____________________________ 20

____________________________ 20

___________________________ 20

__._______...-_-___-________ 20

.__.______- —..__.-__..__ 20

— .-... — .. — ....—..... 20

______-.._-__ _____--____._. 20

____________________________ 20

-- — „- — ..-. — _.___._ 21

— .-_-.-.. — .-. — ....... 21

.___-_________-_._.____.__.. 21

......— —. — . — ....... 21

___-_-__--_____. 2, 21, ^3, pis. 2, 4

...... ..-.-.--.._.--_.... 21

. — ... — . — ... — .-..... 21

....-...- — .......-....... 21

--—. — — — — — _-__ 21

21

____________________________ 21

._-_-__-_-----_---_--_-_____ 21

— _ — .-- — — .-.-..__.. 21

____________________________ 21

__ — - — — .-.._-- — _-.__ 21,24

_--______--_----____ 3, 21, S3, pi. 2

._____-_________-_______-... 21

-_______________-._.______.. 20

_-________-____-.__._-_--.. 20

-.-- — .. — — .-. — ,__-._. 20

--___________...____-_______ 20

-.-.——- — — - — .-..... 20

-.__._____________..______._ 20

___ ________________________ 20

____________________________ 20

____________________________ 20

.-........ — .... — . ....... 20

.__.______-._._____________. 20

-_-.-______-____-____,_____. 20

.________...-______________. 20

_--____-____-_-______._____. 20

_ _...__..- — .._ — .._.__. 20

..-.. — .--. — ....-......... 20

-...-..-.——.... — .-.... 20

Page 

(Metacoceras) angulatum, Metacoceras—Continued

inconspicuum, Metacoceras—... ..--. —---..-..-..---..-.---.--—————— 20

jacksonense, Metacoceras-..-. _____.___._-_----------_——— — ————— 20

knighti, Metacoceras-.------ _.._.._._--- —. — __-__—. ———————.— 20

Iambi, Metacoceras--------- ......_. —— --_-_.,- — _..- —— —'.———— 20

mammiferum, Metacoceras-...-_____-_— _____-_--.-. —— - .. —— ——— 20

medlicottianum, Metacoceras.... _____-_-_-__-_--.-----___— - ———..——— 20 .

muUituberculatum, Metacoceras______-... —... —— -...„.—.———-—— 20

mutabile, Metacoceras-....- __._.—— ----- — _...- —..... ——.-.. ——— — 20

nodosum, Metacoceras--.-- ... .......... — -.. ----------- —— — —— -.—— 20

ornatissimum, Metacoceras---. ..._--------- ————..-_ —— —— ————— 20

perelegans, Metacocfras....----.......—-...—.—.. — ------ —— —— —— 20

pernodosum, Metacoceras.-,....................— —— —— — ——————— 20

piszovi, Metacoceras..---------.----..---------.----.-----.-—---------- ... 20

artiense, Metacoceras..---.... ---------—.—---------————————— 20

postcostatum, Metacoceras...——..... —— --....- —— ------ — —. —— —— 20

pottsvillense, Metacoceras..--... r ... .... ———.————————-—————— 20

reedianum, Metacoceras-- ....—.._..-_-_----.- ——... ——...————— 20

sangamonense, Metacoceras-.-.-.............. ...— —— ——.- —— ———— 20

sinuosum, Metacoceras---.... ..___ _. —.....--- — ——— ——— — —— 20

subglabrum, Metacoceras.-....... ____.-...-. — - ——— _ — -. ——— —— -.-. 20

subquadrangularis, Metacoceras— ............ ———„---.- —— —. — -— 20

tricarinatum, Metacoceras...... .....— .— . ——————. —....————..-. 20

parvinodosum, Metacoceras..-----------—----—... —— -. —— — ——— 20

trigonotuberculatum, Metacoceras..-------. ...——— —...———. —— — 20

tschernyschewi, Metacoceras—.... ..... —.. — ——— - —— -.-. ———. ——. 20

tuberosum, Metacoceras....------------- — --------- ——— -.. ——— ——.. 20

unklesbayi, Metacoceras--.......... .... ——..——-———...———————— 20

vagans, Metacoceras--.-.-.......-.-.......... ————.-.-- ————........ 20

walcotti, Metacoceras- ...... — - —. ———. —— —————.———. —..-.. 20

metternichi, Pinacoceras.- __._-___.__. ——... ——...- ———. —. —— —... 89 

Mexico, Triassicnautiloid occurrence.------- — ——— ---- — - ——...--.-.— 3

militarium, Stearoceras........—.... ................. ....—— —...— — ——. 58

Miller and Youngquist, quoted...-.____-..--..-..— — ———... — — ------- 59

Miller, Dunbar, and Condra, quoted...—.. — ————— —— ————— ----— 17

milleri, Grypoceras... - —— ---- ———.. —— ------——... — — —. ——.-..— 47

Orypoceras (Orypoceras)............. —.......——-.................. 2, S3, pi. 6

minimum, Orypoceras (Domatoceras)... ....... ————— ._——————.———— 55

mingshanense, Tainoceras............ ..._ —.... ——— ———_-_____. ——... 25

minuens, Pleuronautilus (Trachynautilus).- --------- —— --...--..—— .. — 44

modestus, Paranautilus—......... ._..-___.... ————.——. ——... — ------- 69,71

Mojsisovics, quoted.... ——....... - 27,28,32,33,39,42-43,44,65,67, 72, 73,80,88,89

Mojsvaroceras———------ 3,4,6,7,9,10,11,12,13,19,20, SI, 24,29,32,47,48,51,66,74

perarmatum........ — ...... ——— ——————— --.--.. —————— — -—— 21

turneri.-------...-----__---------- —————.———„—————————— 23

(Mojsvaroceras) augusti, Afetacoceras.... ——— — ———— —— ---. ————— — 21

auriculatura, Metacoceras..-.......................... ___——— —— ———— 21

binodosum, Metacoceras................--...--—---.--.......-...-..-..... 21

bulogense, Metacoceras----------- ——— ——— —. —.... ——... —— -.-.. 21

frenchi, Metacoceras-........................................... 2, 21, SS, pis. 2, 4

kagae, Metacoceras--... ———————————————— ————— ———————— 21 

kellneri, Metacoceras-- ......................... —..—... —.———————— 21

morloti, Metacoceras...... .. ————— —— -. ——.. ——...- —— —— ——.. 21

neumayri, Metacoceras..--- ————————— — —— —— --------—————— 21

nivicola, Metacoceras---................. .... — —— ————— —— ————— 21

patens, Metacoceras-....... —— —. —— ----- ———. ———— — —— —— 21

perarmatum, Metacoceras...-.-------... —.-............ ....———.——— 21

pironai, Metacoceras. ------------------- ——— -----...... —— — ———— 21

polygonium, Metacoceras.................... ...... .. —————— —————— 21

subaratum, Metacoceras. ——————.. ———— --------— ——— —. — —— 21,24

turneri, Metacoceras................. ——.—_———_..———— 3, 21, 8S, p. 2

ventricosum, Metacoceras.-...........— —— —.-.. ————— — —————— 21

mokouensis, Paranautilus- ___„„_ ———— — —— __'__-—— ————— —— 69 71 

Solenochilus——-................................- — ...................... 69

molengraaffi, Pleuronautilus (Enoploceras)..— ....—... ———— _——————— 41

monolifer, Tainoceras——— — —— —— — - ———...... ————.... —. —... 25

montpelierensis, Qermanonautilus....- ...—... ——— ----------------- 2,28,30; p\ 3

moorei, Domatoceras-....—. —— — ——..--. ——...-. — _ ——— ------- —.-.. 48

Grypoceras (Domatoceras). .....——-——....—-————. —————————. 55 57

morloti, Metacoceras (Mojsvaroceras)........ ..... —— - —.-.-. — -----.- ——... 21

Temnocheilus-... ——————.——————— —.———____.-.-- ——— ——— 21

mosis, Pleuronautilus--.-------....------ — - ——.----.--__._ ————— — —— 33

Pleuronautilus (Pleuronautilus)... _.....----_———..... — —..---—— 36

mosguensis, Domatoceras............................... — ———— —— ——— 51

Orypoceras (Domatoceras)............-.--.___—...._— ——..-.--—— 55

multicameratus, Nautilus—............ ... ... ——— —.-. ————— —— ---—— 71

Paranautilus——- —— ---—................................... 2,69,71,pi 14

mutticostatus, Tainionautilus........... ..————— — - ———————— _————— 27

muUituberculatum, Metacoceras (Metacoceras)-.. ——— — ——————— ——— - 20
100 INDEX

mul'ituberculatus, Temuocheilus. ..._.._...

simensis, Temnocheilus. _____________

tastubensis, Temnocheilus - _ ___________

murrayi, Tainoceras__--____-_ __________

mutabile, Metacoceras---------------------

Metacoceras (Metacoceras)-------------

mufatum, Pleuronautilus (Pleuronautilus).

Page

18

18

18

25

19

20

36

N

narcissae, Pleuronautilus (Pleuronautilus'). 

Nathorstites---.---------------------------

Natica....... -----------------------------

------------.--..-------- 36

-___ — _ — — -._______.____ 3

-_-_----_- — -----__„_.___- 31

natosini, Proclydonautilus-- _— — — — ——————— — — _-_-------.—__—_ — 3,81,84

Nautilus.-.---- ----------------------------------_-_-_-________--__....-....-_ 5,31

acutus _.----——--------------------------------_--_----.--_-.-_-._......- 5,63

ampe~7a»H<s_———— ———— — — — ———— — ———— __ — _____- — — _ — — _ — 5

barrandei------- __--_____-_-.-____.__________._-___-_._-._____________ 60

bidorsatus------------------------------ ____._-___-_-____________________ 4,28

cor»M-M*--------------------------------------------_- — _-__,-___.________ 74

craz —.——._-__- — --_. — -—-----_---_-_--. —— ------.--_---_._-.....-- 4,27

ehrlichi——-- — ----------- ________-------______________...__ 5,65

paZea.MS———— — — —— ———— ————— — ———_-—_ — ________ — — — _____ 5, 55

gemiimatus-.- -- ——— — _-————_---------__________.—.__ — _... — ... 5,44

goliathus--.-. — . --——____ — — _ _ —— ___ ___ __________ ____ 4, 12, 17, 18,34

granulosostriatus.- —— — ———— ———— ————— — ———— _____.. — — .—_... 5

griiesbachi _ _ _ - — . — --_-_-_--_--___-_._-___ _ _ ____________________ 5,80

heterophyllus— ------------------- _ — — -_——— — — ____ _ _ ____._-._.__ 5, 63

krafftL 5,72

liardensis-------- —— - ———— — — ——— — _ — __ ——--- — — — _ — ________ 75

lilianus----------- — — — — ———____——--—__ — —_______--.--_______..- 5,60

linearis------------------------------------------------------------.---___ 60

wesod.c!/ w. — — — — ——— — ——— ———- -————— — — — - - — — - _ __ _...._..-- 5,48

multicameratus.---------- — ---_-___-___--___-_-_-.-_________..-__________ 71

noricus __----_----.--__----.--------_-_-------------_------_-__________.-- 5,88

ophioneus- ___.„-_ — - — _ — -_ ——. — _._-._____-_._.__- — ...__„______ 5,58

perfum«-M8------------------------— --__-_-__-_-________.._-_________ 73,74

ponderosus--.---------- —— _ — — —— — ————— — — — ——.____ — — — -— 5,59

quadrangulus __ — — ------_---------_-_------_---______-_-_-.-__------,__- 4,24

rectangularis----- — ----------- — _-- — --_ —__——_-- —. —______________ 25,27

securis---------- —---- — -. — - — -- — ------. ——— . — — -- — ...--„..___ 5,89

semicostatus.-------------- — — ------------------------ — -..,.._ _______ 5,42

sibyllae------- — ------------------ ——. — --------___-.--,--_-______- 5,73,74

simonyi-- — ---------------- — - — ————. — -------------_--._........-- 5

spirolobus—--------------------...------------... — _______.._...._ — ,_- 82

spitiensis—--------------------------------------------------------------- 59

sfyriacus---------------------------- — - ————- — — -—— —-.--— — — — — _ 5,80

superbits—---------------------------------------------------------------- 5

tintoretti-.---------------------------------------------------------------- 74

transitorius------------ — ------.--------........--......... -___...- — - 4,26,34

trautscholdi------------------------------------------------- .___ — —-_.-._ 26

— . — . — —....— —- — — .„ — —-. — „- — — 81

— — — — — —— — ..„ — —— ....—.„ — „ — — 26

—. — — — . — — — — . — — — — — -.- — - — — - 21

tubercutatus. 

verae—------

whttneyi---------------... _--_ —.___ — ------- —.._--.-__-.___________ 53

wulfeni--.- ____ — ____-__._.__._____________-.._____ 4,33,39

sp.---------- — ------- ——————— ------- —————.... — ____._.._-._--__ 3

Nautilus (Clydonautilus) spirolobus.- _______________________________________ 82

Nautilus (Discus) sangamonensis--.__.................. _____________________ 4,19

Nautilus (Menuthionautilus) kieslingeri—----------- _.-__-__--____________ 5,57

Nautilus (Pletironautilus)'sp—---------------------------- __________________ 38

Nautilus (Temnocheilus) coronatus.. _-_----_-__..-----_________________.______ 4,17

(Nautilus) galeatus, Grypoceras..— — - — _.__-__-.---________ — ______________ 57

nebrascense, Tainoceras.- ___ — __--_-__- — -___ — ---__--_-_-_--__.________ 25

neutnayri, Metacoceras (Mojsoaroceras)..-... ___------_-——-.____-__.... 21

TewnocAe-Z-W.-------------------------- — ---------- __________________ 4,21

Nevada, Triassicnautiloidoccurrence.--- .__._. —.-___--------_____. ________ 2

newelli, Pleuronautilus (Enoploceras) __.-____,___-____---._-______.___ 2,4/,pl.4

nikitini, Nautilus- _.------_---_----_-.-------.- ------__-__.---______._„_.._. 21

Parametacoceras------ _--------__--__-----_-_----- _----__----_-_-__-_-___ 24

Temnocheilus--------------------------------------------------,---------- 18

nikituwkensis, Grypoceras (Domatoceras}.--- -___---____-_-_-_._-__-___-... 55

nivicola, Metacoceras (Mojsvaroceras)----------------------------- ------------ 21

nodocarinatum, Tainoceras-------------------------.------- _---.___-___-_-___ 25

nodosocostattim, FoordiceraS--------------------------------------------------- 19

nodostriatus, Pleuronautilus (Pleuronautilus) ______-_---___-_-_. .___.___-_-___ 36

nodosum, Afetacoceras.--.-..------------------------------------.------.- — .-- 19

Metacoceras (Metacoceras)--------------------- — _-----l__---___--___._.. 20

nodosus, Germanonautilus-.----------------

nodulosus, Pleuronautilus (Trachynautilus) 

noettingi subglobosum, Tainoceras- _ -_-_--- 

nordenskjoldi, Syringonautilus---------. ----

Page

---------------------------- 28

--_--___-_ ___ -__._ ________ 44

.--_------_----- ------------ 25

------------ ---------------- 60

noricus, Clydonautilus _ _ ._-_---_--__-_____--_--.-__--------------_-_-------_ 88,89

NaulUus— —.--- — - — - — --—-.--——..— - — -- — - — ----- — ------ 5,88

timorensis, Clydonautilus..----------------- — .____-__-______-.--___-___-- 89

northropi, Domatoceras---------------------. ------------------- -------------- 51

Grypoceras (Domatoceras) -------- ____----__--_-----_--_---------------_-- 55

obsoletum, Domatoceras___-___.

Grypoceras (Domatoceras)...

Liroceras__.__--____--___- 

obtusicarinatus, Syringonautilus _ 

obtusum, Grypoceras ------------

Grypoceras (Grypoceras)—... 

occidental, Tainoceras----------

O

...__-.__ — — _-.__ — — — -._ — ____ 51

_ _..-___ v ___--___. ------ __._ — __ 55

________-__-.__-_- — __- — — __-_ — - 69

___ — _-_._ — __ — _.- - — --_-_-..__ 60

....___--.-_-_--.-------_--_-_----------_ 51

______--_ -_-_-__--_-_.-- — _-_ — — 53

..._-_-. — _._-_ — -_-- — _ -_-__--- 25

occidentalis, Styrionautilus.- -------- — __ — __._ — ----- —— _.---_---__-.--__-. 80

Occurrence, Triassie nautiloids..- ------ .___-__---_----_----_------_-----. -___ 2-3

oenanus, Pleuronautilus (Pleuronautilus)--— ------------------- --- ---------- 36

ophioneus, Nautilus.-------- ------------ --------------- -------------------- 5,58

Pselioceras----. ---------------------------------------------------------- 59

orientale, Tainoceras ---------------------------------------------------------- 25

ornatissimum, Metacoceras (Metacoceras) . ---------------------- ------------ 20

ornatissimus, Pleuronautilus (Pleuronautilus) --------------------------------- 36

ornatus, Pleuronautilus (Pleuronautilus)- 

Orthoceras blakei- ------------------------

campanile __ __...___--_-.-------_--

shastense-.- ---------- -_---__---_--._

sp-

------------------------------- 36

------------------------------- 2

-__---_--_----___-----_--____-- 2

---__-------------_----------_- 3

---------------------------- --- 3

OxynautiliLS— ------------------------------------------ 5,7,9,10,11,59,60,55,65

acutiu-. — — — -- — - — ---- — -------- --------------------- 3,65, pi. 19

pacificus, Cosmonautilus.---------------------------------------------- 2,3, 85,pi. 16

palladi, Qrypocems—--------------------------------------------------------- 51, 54

Grypoceras (Grypoceras)-------------------------------------------------- 53

parallelum, Grypoceras (Domatoceras)----------------------------------------- 53, 55

parallelus, Domatoceras------------------------------------------------------- 51

Parametacoceras----------------------------------------------------- 4,12,13,17, &£

bellatulum--------------------------------------------------------------- 4,24

crassus ---------- — ------------- — ___-_-_--__-_ — —.___ — ------------ 24

nikitini.----------------------------------------------------------------- 24

proec«rsor.-------------------------------------------------------------- ?4

schucherti---------------------------------------------------------------- 24

senustum ___-_-.-_--_---------_-_------___-__--_-------------------------- 24

Porono!__.rtdae_---------------------------------------------- 4,5, 7,P, 10,11,65-75,84

Parowo!_.«u*-_—.-_----.------------------- 6,6, 7,11,66,57,69, 71, 7., 75, 77,80,84,89

OKwi.—------------------------------------------------------- 69,71,80

arcestiformis-, ------------------------------------------------------------ 71

bambanagensis-.-- — - — __-___--_._-_-_-------_------------- — -----_. — 69, 71,73

brembanus------------------------------------ ---------------------------- 69,71

bullocki----------- ..- — — ———.-- — — - — — - — — — — — 71

cassis.-.—- — — -— — —- ——-—-—--- — - — -- — -- — —- 69,71 

indifferens------ —— — -_ — - — — ——— - —------- ——— -____-- — __ — — -_ 69,71

kashmiricus----.--- ----------------------------- — ---------—___-___-- 71

liardensis------------ — — -------- — --------------- — --_-- — _-___---— 75

meridianus.—------------------------------------------------------- 69,71,77

modestus---------------------------------------------------------------- 69,71

mokouensis.-- — _-_---_-----_----------- — ------------ ——- — — — — ——_ 69,71

multicameratus- --------------------------------------------- 2,69, 71, pi. 14

peregrinus---------. ------------------------------------- ---------------- 69,71

pseudobrembanus-—-------------------------------- —- ---- — ----------- 71

siculus— — — — — -—- — - ———- — — — — — —— - — _---.-----_-----------— 71

simonyi.-—------- — --------- — ------------- —— -_.__ — __ ———— ----- 67,69,71

smithi—-------------------------------------------------- 2, 71, pis.4,8

subbambanagensis--------------------------------------------------------- 71.

*Mnda.CM«-_------------------------------- --------------------------- 69, 71, 77

tommasi---- — ___-_-__- — ----—-------_ —-------------------- ----------- 69,71

sp_.------------------------------------ --------------------- 2,71?,pi.8

Parapopanoceras-.------ .— — --—-—— ——--—-- — — — -- — --— -------------- 3

paronai, PleuronautUus (Plueronautilus)— — — —— — — — — — — — — — ——— — — — 36

parvinodosum, Metacoceras (Metacoceras) Mcarinatiim------------------------- 20

patens, Metacoceras (Mojwaroceras)------------------ —_ ___— -__..-_- — --- 21

perarmatvm, Metacoceras (Mojsvaroceras)------------------------------------- 21

Mojssaroceras__..---,-.---- -—_- — ——— — — — — — --— — -—-- — — — — -- 21

peregrinus, Nautilus---------------------------------------------------------- 69

-------------------------------------- —— ---------——. __ 69,71
INDEX 1C1

perelegans, Metacoceras (Metacoceras).. . _. 

Peripetoceras-—-. ...........——_..-___..

permianum, Stearoceran ...-...--..-...-.....

Permonautilus-— ..——........ —........

pernodosum, Metacoceras (Metacoceras)__. 

pernodosvs, Pleuronautttus (Pleuronavtilus).

_._._....__......__.__...... 20

-——.— — ....-...-..___ 66 

. - — „......._...._._____ 58

-_-______________.. ........ 74

-- — -.-.-_-_-__-_._..___. 20

-------__--..--_.._.__ 36

pertumidus, Nautilus--,.--------- ___---.______-__-_______-._ ____..._._.__. 73, 74

Sibylla-nautilus_____---__------_----_._______-___-_-__-___________________. 66, 74

Phacoceras dumblei_---__---_---__-___________________-_______________-_., 5,57

PMoioceras—_.-- — -----------.-—. — — -_____..——— __—______ 5,7,17,32,44

deliciosum---,----.-----------------------.-----.----.----.-_-._---... ____ 45

gemmatum------- — -.-—.--.— ._..._____._......._........._., 45

welteri-.--.-- _______._——-....,..._______.............__.... 45

sp._—- — -..-—- — .. — — .—..-.-.................- — ......3, 44, 45, pi. 4

phosphoriense, Stearoceras,---- —— ---_----________-._________--________-___-._ 58

pichleri, Pleuronautttus (Holconautilus) _..____-----_-___--__________._______ 42

Pinacoceras metternichi-----.-.----..-, ..........................__._...-______ 89

pironai, Metacoceras (Mojsvaroceras). ___-_______--__________-___--_.__.._. 21

piszovi, Metacoceras (Metacoceras)-__...______..______............ 20

artiense, Metacoceras (Metacoceras)---...... .....____.___...___ 20

planilateralis, Pleuronautilut (Enoploceras)....______..___..____ 41

planovolve, Grypoceras (Domatoceras).. ..._.....___...____......___ 55

Plectoceras- — . — ...__._...____.________...______._._ 12 

Pleuronautilidae---------...—...___...__..___._________ 4,33

pleuronautiloide, Fooridceras-. „.._.-..__-------________.__... 19

Pleuronautttus- ........... 4,6,7,11,12,13,17,18,19,21,24,26,32, S3, 34,36,38,42,43,44

alaskensis——.- .....__.———__________________.__...... 3,34

ampezzanus..,..————————————___——____________ 33, pi. 17 

dieneri.......__.__ —._.-___________.___.__...... 38

idahoensis-..-- ......._..... —— _____.________._____.__ 34,39

kokeni.-. ......_____....___._____.____....______.__ 38

mosis.-------..-—.._---------.-______.__-_____--.---_.__.-_ 33

subgemmatus-.-.- __........__.......__..__........._...._... 5, 33,44

superbus——.——.-.- — -...-..__.._.___....__-_-...„..._.. 33

trinodosus-——.__._....—....___-________.____._-_....__ 4,33

sp...-. —-.- — ---- — -.- — -...--..-..-.- — .--.-... — -.-.---.-... 2,58,39

Pleuronautttus (Anoploceras) rollieri..... .______.........___...._ 43,44

Pleuronautilus (Encoiloceras) superbus-. ...------_-----------__-----_.. 42,43

Pleuronautttus (Enoploceras)------------------............................... 39

. ausseeanus. ...................————.——... — --....._..__--------- 41

fischeri—... ..._______._..._______......_____.....__ 41

gaudryi, ....-.--.-.-..... —............___._....._............._ 41

kossmati. ---------_...--.---..............__..__.______.__ 41

lepsiusi.-...------__._-_----_-________-...________.-.,..__ 41

lepsiusiformis.. - - - ... .J..... —— —.....__.-__.____....._-------_ 41

malayicus... ..__---------—--.._.._.____....___._....__. 41

molengraaffi___-.._.---__._...________..__._______ 41 

newelii-— -....___...———-_....______....______...-2,/jjf, pi.4

planilateralis— ----------- — _ —........____...__.....__...__ 41

pseudoplanilateralis-----... ......_-___...._......___.......... 41

pseudowulfeni___._---------_....__.....________........... 41

semseyi- — _..___...__--.......___...._._._.......... 41

tibeticus........__...........__...._.________________ 41

wulfeni... ....—-.-. —.. —— ......__.._..........__........_. 41

wulfeniformis.------- _................._._..__________............ 41

Pleuronautttus (Holconautilus) „___...__.._____.__................ 12,33

distinctus - -. ____...,______.....___._._____......__ 42

intermedius.-.-.... ......-.----....________..._______.__..-_._.. 42

pichleri------.............................._______.................... 42

ramsaueri_.__......._...____....___._.__...._....._..... 42

scabiosus... ...—.... ——. ——......_-..-.__...._____..-.-_ 42

semicostatus_...........-----.—......_............................... 42

singularis...____._ —— _.........__--...-......._._....._ 42

StaiUeL-.........-----.----------.------........................._-_--.. 42

striatus.- _________-______...___________...___-_...... 42

Pleuronautilus (Pleuronautttus) ..._...._.________._.._..._.--.-. 33

alaskensis--........._....___.______._........__.__ S/J,36, pi. 4

ambiguus- .................. — -...--........-.._....................... 36

ambiguus spirata— ......... — _.__-.._-_______--._-_-__._.___.. 36

carbonarius--.- ___--.-..__-______--___..i___-_._.. 36 

cooperi___....__........__...____-.___.._____...... 36

cornaliae------------- ....-.--.--...-.......__.............___............. 36

crassescens. ____________------___........____.._.......______ 36

crassescensjugulata---.-----------.------------------------------.----—--- 36

semijugulata.. __-----_____________.___________ 36

dieneri-.. ________....______.________............

dolomiticus.... 

dorini-___ 

dorso-armatus.

36,38

36

36

36

Pleuronautilus (Pleuronautilus)—Continued

esinensis---—... —— ——— ————— — ————— -———————————— 36

externelobatus. .......———..._.._. ——— —— ——— -- ————— —— —— 36

furcatus-..... __....______.________-__—————-——-- 36

gregarium... __—— ———...- — — - —— -- ——.... —. ————— -——— 36

idahoensis----------------_-.---.--.—- — — — .----- — —2,36,57, p'. 4

incertus_..-...--.------,------...-..- —._ — — —._ —— -------———— 36

kasarmenskensis.---------.-------------------------.-.---..---.-.-...----- 36

feofcen..------------------------------------------------------------------- 36

.-----———--—--_-—._——.—...—— 36

.—..._—....... -—-—-—————.——.. 36

.......... ...._..-.--._.......————.——. 36

-_-.—— — --—-—- — ——---——. — — .. 36

.—.__.——_-.—-——.- ——————-— 36

............................—...................— 36

..——-— — -- — ---—- — .----—--- — -- 36

..-_.___-_- — .-- — ._--—--.—---—-----... 36

.__..-.._-... — .—--—----—--- ——---.— 36

-..........-...-..-—.....-—...........——.... 36

—..——— —~~--i—-—----—-—--—.—— 36

-.-.....--_-.-————-—. — --——-..—— 36

— ..-—.....——-.-.——_...——————. 36

—....-..--.——————-.——-——--.-... 38

..._.....--.--......._-....-.._._....._........ 36

linchengense.... 

longinodosus.-- 

magnicostatummariani— ..... 

marmolatae.--- 

megaporum.--- 

mosis —--------

mutatum.....

narcissae-.-.. 

nodostriatus— 

oenanus-.—. 

ornatissimus. 

ornatus------

paronai.- — -.

pernodosus... _.-...______------—...-.--.......--------.-..-—— 36

praecursor,... ——.-.-...————_ —.... —— - ————... — - — - ———..— 36

ptychoides... —— -. —— ————. ——.-- —— —— -... ————.-- —..—— 36

guadrangulus-.- ———— -...--.-...--. ———..-. —... —— ——. —— -—— 36

scAa/Mit^t---------------------------------------------------------------- 36

seminodosus ....-...... ———— — —— - —— —— — —— -...—————— 36

shumardianum,-.. — —— ——————— — — ————.. ——— —— ——..... 36

simplicostatum.- ———..—————...... — — — -...—— ——— — —. 36

strangulatus..... ——..-..--.---.__——.. ——— -... —... ——... — —— 36

subquadrangulus.----------------------------------------------------... .. 36

taramelli-.——-- —.............................-.-....--.........—.. 36

tommasi--.. ......—— —————————— — — —— --... ————— —.—— 36

trinodosus.------- ————. ————— — — ———— —— -.-.-.. ——.. —— -. 36

triserialis---- —— -—.................... —.-——..—— — .-.—. 36

tsehihatscheffl—.—.....-....-...........-.—.-...—.................... 36

tubercularis-.. ——— ——— —————— — _ —.. ——— --_- — ——— ——— 36

venustum. --_.._.--- ——... ——— ————— ———————... —— —— ——— 36

verae... -...__..—————. —————————.—— ————— ----——————— 36

wangi_.._-_---_-_-------.-.--.--.-.---------.-—.--._.--.--—..———— 36

Pleuronautttus (Trackyntaitilua)---——————.—.——.----.-—— 12,33,44

clathratus. __...—————.— ——————.. —.—— —————— --.- —— -- 44

laevis-- —————-——.———————--————.................. 44

minuens......

nodulosus—-.. 

subgemmatus.. 

telleri----—

44

44

44, pi. 17

44

trilineatus——- ...————— ——.... ———————— ————————— ————— 44

(Plueronautilus) alaskensis, Pleuronautttus————......—.—————.. 36, 84, pi 4

ambiguus, Pleuronautilus------... ... —.——... ——— ———— --.—---- 36

ambiguus spirata, Pleuronautilus————... ————————————— —..... 36

carbonarius, Pleuronautilus-- --------------- — - —————— ——— —— — - 36

cooperi, Pleuronautilus-.--..-- ————————-—————————————— 36

cornaliae, Pleuronautilus-----—--_.-—------- ————— ——— —— —.. 36

crassescens, Pleuronautttus______—.-----.-----.—.————. —— — 36

crassescensjugulata, Pleuronautilus-- ——— ——————— —————————— 36

semijugulata, Pleuronautilus---- ————.- ——————————————— - 36

dieneri, Pleuronautilus-.---..... ...—————.————— — ———————.. 36,38

dorini, Pleuronautttus___-.--.--...—————.———————— —— ——— 36

dolomiticus, Pleuronautttus_____-.-_--.-...--.————————.——— 36

dorso-armatus, Pleuronautilus- ————— ——— —— —— ——— —————— 36

esinensis, Pleuronautilus-..— —————— ——.-——————————————— 36

externelobatus, Pleuronautilus---------- —— —.—————————————— 36

furcatu*, Pleuronautilus______————.—.——.————————— 36

gregarium, Pleuronautilua-..--——- ——————.——————————————— 36 

idahoensis, Pleuronautilus..----...-—--—..———.——-----— 2,36,57, pi 4

incertus, Pleuronautilus----— ——— ————————————————————— 36

kasarmenskensis, Pleuronautttus— ....—————.——————————————— 36

kokeni, Pleuronautttus-. __-_..__—————.——————————————— 38

latissimus, Pleuronautilus-------.—————...... ———————————— 36

linchengense, Pleuronautttus____-—————... ————————— ————— 36

longmodosus, Pleuronautilus-- ___—————...———.————————— 36

magnicostatum, Pleuronautttus————————.———————— -—————— 36

mariani, Pleuronautttus---- —.. ——— ————— ————————————.-- 36

marmolatae, Pleuronautilus.- ——.——-. ————— ———— ————————— 36

megaporum, Pleuronautilus- —— — ——————————————— ---——— 36

232820—53——8
102 INDEX

(Pleuronautilus) alaskensis, Plueronautilus—Continued 

mosis, Pleuronautilus- _________._.___...__....

mutafum, Pleuronautilus_--.-----.---._._.___._..

narcissae, Pleuronautilus— ---.------_-...._.._.___._

nodostriatus, Pleuronautilus..-.-. .__.______-.___._

oenanus, Pleuronautilus— -—-—-_—-——-—_________

ornatissimus, Pteuronautilus. _--.—. ——._____—____

ornatus, Pleuronautilus.-.......... .........______

paronai, Pleuronautilus- ___.-_.-__-__-_______.....

pernodosus, Pleuronautilus.----.-.-..-.........._._

praecursor, Pleuronautilus--------------------------

ptychoides, Pleuronautilus..................... _____

guadrangulus, Pleuronautilus.......... ...__________

schafhautli, Pleuronautilus.- __---__--_______________

seminodosus, Pleuronautilus....--.---...-........_._

shumardianum, Pleuronautilus.---.......... ...____

simplicostatum, Pleuronautilus...................___

strangulatus, Pleuronautilus.............-__.....__..

Page

-. — — — — . 36

- — „ — — .. 36

-- ——— -_ — — 36

- — - — — .._ 36

- — — -.- — — 36

- _-_ — -.... 36 

__-____.._____-. 36 

__- —— -_ — _. 36

- — ... — .... 36 

. — -.-..... — . 36

- — . — — . — - 36 

. — — — — — 36

- . — -.- — .- 36

-.... — — ...- 36

-. — .. — — .. 36

-.. — ....--. 36

....--- — ... 36

subquadrangulus, Pleuronautilus.. ------______________._..__.___._______„ 36

taramelli, Pleuronautilus----------. .........___________________. 36

tommasi, Pleuronautilus----------------.-.-...... _____-..__._____...... 36

trinodosus, Pleuronautilus... —-- — ---..-_._..._......._......__._....._. .. 36

triserialis, Pleuronautilus-... ..... — ..-__..__.___.__....._..._.... 36

tschihatscheffi, Pleuronautilus-—.--.----.--..... .............__....._ 36

tubercularis, Pleuronautilus.-. ..__ — .-.________....__.......___ 36

venustum, Pleuronautilus-----------------..--.-._.__.__.-_..._____..._... 36

verae, Pleuronautilus---------.---- ...---_-_-_---_._________.._.____._.. 36

wangi, Pleuronautilus.-. ..---.----------...-.................__.____.... 36

sp., Nautilus......----------.-------.---.-.-...---........-.__----------- 38

plummeri, Grypoceras (Plummeroceras)--- -__-_--_-_._____—____..______ 51, 54, pi. 5

Plummeroceras-------------------- -.......—_.___ —___________________ 5

Plummeroceras--...............—__......__.......___ 5,9,10,11,45,47,54,85

plummeri-------------------------- ----—.-.-.-.-.-.....--._...-_--_..-- 5

(Plummeroceras) plummeri, Orypoceras. — ————_— — — — _-_— — — ____ 51, 54, pi. 5

posttuberculatus, Temnocheilus- _—-— — - —----_--_--.____—— ___,-_. —___—_— 18

kossioae, Temnocheilus-----..--...-..-..........-.......--__....-._.__-_.. 18

waschkuricus, Temnocheilus..--......--....-......_-__-_. — ..___.......... 18

ponderosus, Nautilus— .---------.----------.----.---....._-.._._....__.....___ 5, 59

polygonium, Metacoceras (Mojsvaroceras)..... ___---._____.__.___.____.____.. 21

postcostatum, Metacoceras (Metacoceras)------ — --- ....________.._.____..____ 20

pottsvillense, Metacoceras (Metacoceras)-—----------... __.................... 20

praecursos, Parametacoceras- -----..-.----.-....---............__......__.._... 24

Pleuronautilus (Pleuronautilus)....------ — -----.........-........._.... 36

primoriensis, Syringonautilus....... ___.-.---... —....----..-.........._.... 60

privatum, Grypoceras (Grypoceras)—--..-..-.....-...........---_...._-__...... 53

Grypoceras------------------------------.-..----.--.--.-..---.--.-----.... 51

Proclydonautilus. —---- — --------.-- — 5, 7, 9,11, 66, 75, 77, 80, 81, 83, 84, 85, 88

angustus----.... — ---_—-- — — — --- ——_ ——-_._ — — _ — ___._.._____.__.. 81

buddhaicus- __..... — -__--_ — - — --- — ____--._________-__.__________. 81,84

ermolli. ....__... — ___---_____.._. — __ — „....._.......__...__.. 9,81

gasteroptychus... ..... — _________ — —— ____ — _______ — ____........... 81

timorensis........... —..---.-.- —— —....____________..__._ 10,81

goniatites..--- —--------------------------------------- ...-- — _____.____ 81

griesbachi.---_____.„..._.--.—-.__._......___._____._ 81,84

/.mL-------------------------------------_-___._--- 3, 81, 83, pi. 15

inflatus-------------------------------------...... — — -- ———_____—__— 81

mandevillei——----------------------------------------------.------------- 81

natoaini——— ——— —--- - --l-~ —-—- — — — - — .--...---. 3,81,54

spirolobus.-.------ _ — __-- —__- — ———_ — -_—--___ — _ ________ 2,3,81,Sg, pi. 7

squaixensis- — __.— —.--— — -.- — — _-. _-_-___----_..___-.__________ 3,81,S3,pi. 8

stantoni------------.------.---------- —------------------- 3,81,SS.pl. 10

triadkus—— -----.--------------.----—------------- — .— - 3,8/,pl. 9

tuvalicus---------------------------------------------------------------- 81

ursensis.--------------------------------------------------------- 3,81,SJ.pl. 11

Proclydonautilus (Cosmonautilus) rf?7/fn____-__________________._______________ 85

(Proclydonaulilas) spirolobus, Clydonautilus.- ..._-.......---....... ...____. 82

triadkus, CTj/do?.a«--i.ttS--------------------------------------------------- 81

Padioceras— — ———— ———————— — —-- — ——- 5.11,33.45,48, 58, 61,63

connectens------------------------------ — ----------- -._____.-__ —.-._ 59

conodutum-------------------..._.--——---. — -— —.. — -_. ——.... —... 59,61

ophioneus..._.._________—---__- — --_ — ___. — ___.__ — _--__—._-. ——.... 59

pseudobrembanus, Paranautilus-------------... __-.__—___—_ —______ —.—— 71

Pseudomonotis xubcircularis-------------------- — ----- — — --.-. —... — —.. 2,63

Pseudonautilus.----------------------------------------- -.---.-.---.. -...-. 75

pseudoplanilateraltus, Pleuronautilus (Enoploceras) ———— ------ — ---......— 41

pseudowulfeni, Pleuronautilus (Enoploceras)- __-----------———----------— 41

ptychoides, Pleuronautilus (Pleuronautilus).--- _————————.—__—— 36

Page

Q

quadratigulum, Grypoceras (Grypoceras)---,-- _ -..------.--....... __________ 53

Tainoceras.-, -.-.----.-.------..-.-.-...---.-------------.---_--_--_-... __ 25

quadrangulus, Nautilus- -..--.- —_____— —______— — ___—___ — ______ ________ 4,24

Pleuronautilus (Pleuronaittitus).. ___ _---_— ---__ — — _ — __ — __ — __ — ___ 36

quenstedti, Clydonautilus- __-_---------___-_____--_-____-______________________ 88,89

quinqueliratus, Temnocheilus-..-- __---____-.-_----__-----_-_________._____.__ 18

R 

ramsaueri, Pleuronautilus (HolconautUus)-.. _----- — _-_--_--_-___-__.___._____ 42

rectangularis, Aulametacoceras _ _..._____..__. __________________________ 7,13,28,32

Nautilus--.. .....— — - — — — -— -- — -. — -------------.-.-.. — .. 25,27

Thunngionautilus ... .....-.---......-..- _ ____________ _..____________._.' 32

Reed, cited.. __ ----------- ___ ................ _ ________________________ 27

reedianum, Metacoceras (Metacoceras). ..------------.---.--.-.-.----.- ________ 20

renzi, Syringoceras. .....-..-..-...- _ _ — -__ — _-- — ____-- _ ____ ... _ ________ 61

Rhineceratidae. ..................................... __ -_..______._____.._.. 4,44

Rhynchonella... ... ... .-... __ ----__-_--__ _ . _ __ ---._-_-_-_._.__________ 31

Rocky Mountains, Triassic nautiloids _ ...____-_.. _ ._..-..________._..._.__ 2

rottieri, Pleuronautilus (Anoploceras).- ...... _ -—_-_._. _ ___________________ 44

rotundatum, Tainoceras--. _-_ — -__-_.-_--_-___-_ _ . — — --- — -——__._ -.____ 25

Stearoceras. ... ... . __ ____ ... _ _. _ _ . __ ._. _ ----._-__---.-... 58

rouillieri, Stenopoceras _ _ . _ ..------.....-....--.--.--. _ _.___.. ..........j.. 58

Rutoceratidae.. _ ....--.___. _ .--_____ -____ — .. _ ........ _ _._.__.____.._ 44

S 

salinarius, Germanonautilus— -..__-.....__-__.__-________---.____.-_-. ......... 28,29

salisburgensis, Clydonautilus-----.------.-----------.---------.--------- _ .- 88,89

timorensis, Clydonautilus _ - __ _______________________ _ ___-___.___-___. 89

sanandreasense, Stearoceras -------- ....... ____________________________________ 58

sangamonense, Metacoceras--. -.-...----.-...--.... ______-_-______-_______-. 19.pl. 1

Metacoceras (Metacoceras) ......... ... .........-....----....-.---....... _ 20

sangamonensts, Nautilus (Discus). ........... __ _ ....................... _ 4, 19

sauperi, Styionautilus. _ ._-__- ...-..............-....-.--..-.----..... 77,80,83,84

scabiosus, Pleuronautilus (Holoconautilus). ...--. ....-............------ ...... 42

schafhautli, Pleuronautilus (Pleuronautilus)..-...-.--..-----.-.-.--..-.-----.. 36

schellbachi, Tainoceras ___ ._.---.--..___-—_-_---_____-_-_____-._-_ _ _._..-_ 25

schloenbachl, Germanonautilus ... --...........-.-.-..-..-.--..:.-.--..----.--. 28,30

Temnocheilus-.--- _ ._....--- _ ....-...-..--...-.-.-.-----.-------.----. 21

schucherti, Parametacoceras— ---------- ---------------------------------------- 24

sculptile, Domatoceras----------------.. ------ _._-_._- — --..__._---___--_-_.. _ 51

Grypoceras (Domafoceras) -------- ....-.-.--.--.-..-...-...-.------..--- ... 55

securis, Gonionautilus. ---------------------- --------------------------------- 2

ATaztfflMs.-.. -------------------------------------------------------------- 5,89

semicostatus, Nautilus.. ... .....---..... — ___------__-._____--_-—--__------_- 5,42

Pleuronautilus (Holconautilus) .... ... ... ..............-.....----...----... 42

semijugulata, Pleuronautilus (Pleuronautilus) crassescens. .--..---.----.....-.. 36

seminodosus, Pleuronautilus (Pleuronautilus).--.....----.-.--.----.--------.- 36

semseyi, Pleuronautilus (Enoploceras)-.-.........---...---...-- ... -.... ... .-.. 41

ShansinautiluS---.--. --------------------------------------------------------- 17

shastense, Orthoceras- --------------------------------------------------------- 3

shastensis, Cosmonautilus. --------------- —— __--._.__--_-___-------_ 3,85, 86, pi. 15

shepherdi, Domatoceras --..... .--- --------- ... .-- — - — ----------------------- 51

Gry'poceras (Domatoceras) —— -- — ..-- —— —— — - — __-_-___ — ---------- 55

shitmaraianum, Pleuronautilus (Pleuronautilus)--------------------,-.-------- 36

sibyllae,Nauttlus-- — ----------- --- ----------------------------------- 5,73,74

Sibyllonautilus--.- -------------------------------------------------------- 73,74

Sibynonavtnus.-— .-.-.-—— — - — — — ————-—— 5,6,9,10,66,73,74

fergusoni ..... ._-.__-__.- -„„...--...—-- — -.------- — - __-_-- 2,74, pi. 8

liardensis... ...... ... — .-.- — -- — — - — - — — ----- 3, 73, 74, 75, pi. 14

pertumidus- _ ________--— .- — _- — ----------- — _-__ —— _ ———— . ———— 66,74

aibgUae-.— ..- — --- — — - — --———- — ——- — — - — — -- 73,74 

siculus, Paranautilus _ --_____-_-__--__--__------.--__ — ---__-----_--_.---- ___ 71

simensis, Temnocheilus •niultiluberculatus.. ----------------- ------------------- 18

simonyi, Nautilus------------ ------------------------- ---------------------- 5

Paranautilus _ ___-___---—__——-— .__- — — — — — — — — — — — _- — _ — — 67,69, 71

fimplei, Stearoceras----------------------.------------------- ---------------- 58

simplicostatum, Pleuronautilus (Pleuronautilus) -.-- -------------------------- 36

singularis, Pleuronautilus (Holconautilus)-----.------------------------------ 42

sinuosum, Metacoceras (Metacoceras)-.- — ----------- ------------------------ 20

Smith, quoted—.. ----------- — — ———.„ — — — - — -- — - 29,63,81-82

smithi, Paranautilus-------.---.-------------- ------------------------ 2,7i,pls. 4,8

Stenopoceras. ------ _ --------------- —— ____-_ — —. — _—— — — — -— — --— 58

Solenochilus—-—. — - - ..-. — . — -—.—— — - — -—- ----- - 10,48,57,69

buriensis _ ..____..-__--------- —— _.—.___-_____--_---____---- — ----- --- 69

mokouensis-.... -. — ..--.-- ... ... . —— — —_ — _.__--.-_ — — - — --------- 69

South America, Triassic nautiloid occurrence-. —————— _-_ —— -- — ----- — 3

Spath, quoted. __ —————————————— . ———— ......... ————————— 66

spinosus, Metacoceras- ------- ----- — — ....._--. — ..-. — . — — - —— —— -- 26
INDEX 103

Page 

spiralis, Cosmonautilus dilleri... -----___----__-_.-__.__.______. ........__-_ 85

spirata, Pleura-nautilus (Pleuronautilus) ambiguus.-..... . ..................... 36

Spiriferina--. __-_____-______.___-_-_--_..-..____...______ _ _______________ 31

spirolobus, Clydonautilus.-...----- — .-......................_............... 82

Clydonautilus (Proclydonautilus) ____-.-______........__............... 82

Nautilus—. _--_____--_--_--__-.--__...___— ---__ — __ — — __ — ______-_ 82

(Clydonautilus)--------------------.... _________ ..............._.. 82

Proclydonautilus....... ____________________________________ _ __ 2,3,81, 8%, pi.7

spitiensis,Nautilus___________________ ........................-_---.._..._ 59

Syringonautilus----------------- _....._ .__..__._.-.______..... 60

spumosus, Germanonautilus-...-.-............. ____.._..._-.-.-........ 28

spurri, SyringoceraS----..---.....--............ ..... ................ 2, 61, 63, pi. 7

squawensis, Proclydonautilus--- ...--.-.-....... ...-. ................ 3, 81, 83, pi. 8

stantoni, Proclydonautilus--..------..-.......... ..................... 3, 81, 8S, pi. 10

stautei, Pleuronautilus (Holconautilus)................. ......._......___..._ 42

Stearoceraa..................................... .. 5, 10, 11, 45, 48, 54, 58, 59, 61, 63

aberrans- .......... ........._.............................___...... 58

conchiferum... .______.- -----..---------.---........................._._ 58

gibbosus.... ..______--..__.___— .---____— — __________________-___.--_. 58

hesperium-.... ._--____—_-_- — _-.........._........_____-__.__.... 58

highlandensis.... ....._...................... ........ ..._................ 58

ingens. ...______-___._______....._ ......._...-.._-_-........ ..__ 58

lasallensis.................. ................................________ 58

militarium-.......................................... ........._._........ 58

permianum. ............................................................. 58

phosphorieme................. .--_._..-____... .._...........__...._ 58

rotundatum............-..-.....—........................................ 58

sanandreasense........................ .................. __..._.._... 58

simplex..-......--.----.------.----...........-.-.-.-.-..__--..-........ 58

sublaeve............................................._.....---...-..-.... 58

toddanum—......................... _ _.__-_-_-._ —_-_______. ____ — -____._ 58

Stenopoceras...............^............. 5, 9, 10, 11, 27, 45, 47, 48, 51 54, 57, 58, 69

abundans............................... __._._._...._...__........ 58

cooperL.......... ......................__._.__.......___.._.__ 58

dumblei..-..............................................._____........ 58

inexpectans. ......-_-_-_-_-_-_-_--_.........__....______.____ 58

routaieri.....—.----..................................................... 58

smithi——--..-....--._.-----___..-.-....._____-__._.______ 58

tularosense................................................................ 58

whitei... ....___.--- __--_._-_--.-.._.__. ..._._...____. __...,. _._. 58

strangulatus, Pleuronautilus (Pleuronautilus).... ......................._.... 36

striatus, Pleuronautilus (Holconautilus").................................. .... 42

styriacus, Nautuus............................................................ 5, 80

StyrionautUus.... .-_.-__._______.._ ......_...__....... .............. 80

Styrionautilus------- ... ___-..___ _ ............ 3, 5, 6, 65, 66, 75, 77, 80, 81, 83, 88

discoidalis........ ............. ......... ................................ 9,80

occidentalis................................................................. 80

sauperi.........................................__________ 77, 80, 83, 84

styriacus............. ............................._..__-___..__. 80, 81, pi. 18

sp_--. ———— -..--..--.--.-...————..._...- —— - ———.———— 2, 80, pi. 15 

subaratum, Metacoceras (Mojsvaroceras)....................................... 21, 24

subbambanagensis, Indona-wtilus. _-_____--___-_ ...^............................ 73

ParanautUus.............................................................. 7!

subbuUatus, Syringonautilus. __-_-____-_-____. -...-.-.---.---_..-............. 60

Tropites................................................ 56, 82, 83, 84, 85, 86, 87

subcarolinus, Syringonautilus..... __-______________-_-__._._-___ .............. 60

subcircularis, Pseudomonotis....... ----_____--__.___._-______________-_-.-._-__ 2, 63

subgemmatus, Pleuronautilus--.-—........ __ _______________............. 5, 33, 44

Pleuronautilus (Trachynautilus).__-_.-__._______.-__._....._._.._._.. 44

subglabntm, Metacoceras (Metacoceras).--....--.-... ____-____.-.-_. ... __._._ 20

subglobosum, Tainoceras noetlingi.............. ---.____-_______-___-.-._._... 25

sublaeve, Metacoceras....---.....-...-.-.... ___.____-_ _________-.________._.- 19

Slearoceras..... .......................................................... 58

subguadrangulare, Grypoctras (Domatoceras)... .....-.-..-.__....-..... _______ 55

subquadrangularis, Metacoceras (Metacoceras).... ___-_-___--_____________-__._ 20

Temnocheilus............................................................. 18

subtjuadrangulus, Pleuronautilus (Pleuronautilus) __________________________ 36

subtrapezoidalis, Junavionautilus..... ______________________________________ 63

suessi, Gryponautilus................................. .-_._-__...-_-_-_________ 55, 56

suessiformis, Gryponautilus..... .-._.__. _______..- — — _—._._-___ 56

suevicus, Germanonautilus..................................-...... ___.__-__-.. 28

sulciferum, Metacoceras................................................... 13, 26, 27

sumalrense, Foordiceras..... --.-__________. ..................._..--______.. 19

sundaicus, ParanautUus................................................... 69, 71, 77

superbus, Encoiloceras......................................................... 42

Nautilus.......... — ...........................................__..... 5

Pleuronautilus___..._.__-----_.___.....________.__ 33

Pleuronautilus (Encoiloceras)......--....-................................ 43

Papre 

Svringoceras..--.--- — ---------------- — — — - — - 5,6,10, 11, 45, 57, 59, 60, 61

aczs.——- — ---—— — — ---- ———---- — — --- —----------- 61

aUius.......................... ----- . — -— — —.......——... — ... 61

barrandei.......................-.-.....-.-...-...-.--..-.-..-.-...... 61,pi. 18

breve....... ............ .___._.-_——_._____-__ — __.___-_-_____. ——.. 61

brevis........

credneri.——. 

doubreeanum. 

eugyrum.....

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

_..._-.........--.--...- ———- ——.- — — -.—-._ 61

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

..... ...- — ... — — .—— --.-_— — -.- — ,-.-_ 61

externecavatum.-....-......................... —— ____- __.._._ —. — — 61

evolutum..................................................--.............. 61

granulosostriatum................... ———.. —.- ——.. —— —— 60, 61, pi. 18

malayicum................................... ............................ 61

renzi................................-...-.^............................... 61

spurri...........

tenuireticulatum. 

ztiteli............

timorense....

2, 61,, 3, pi 7 

61 

61 

61 

Syringonautilidae.----...-----.------------.---.------ 4, 5, 6, 9, 10, 11, 48,59-65

Syringionautilus---...........- —............... 3, 5, 6, 10, 11, 31, 59, 60, 61, 63, 65

bosnesis.................................................-----_-___.. 60

buUatus...........................-.-.-........... _____.._-.-_____..... 60

carolinus.................................................................. 60

japonicus........................................... — ....—............. 60

lilianus....... _______._______...__..._------------_ 60, pi. 17

linearis....................-------------—__--__.---_-._-_ —..... ...... 60

longobardicus............. ..........._—— - ———————— —.—————— 60,63

nordenskjSUi............ ______—....——. ————— - ——— -.„..—— 60

obtusicarinatus.. --..-...-. -_-.-_- ——— —. —.-_._.--_-_.-._- — —.. 60 

primoriensis.......................-.......................--.------.-.-.. 60

spitiensis.................................................................. 60

subbullatus............... ______________ —.... —— _ ——— __ ——— ------- 60

subcarolinus.......................-.-.-....-.-........—------------ .... 60

zinnae................................................... — ............... 60

nov. fi. nd_._..______.—— . ——————-——. —————..——————— 60

T 

Tainionautilut—————————— ———— 4,6,12,13,17, SO, 27,32,33,34

fugax. -------

multicostatus. 

trachyceras... 

transitorius-.. 

uynnei.......

....................................................... 27

..........................................^........... 27

..— — .-...—.— — .— — — — —... — —...... 27

_-_____......-_.. — _—--- — --- — --.--- — -__- 26

- ...........-....-.....-,. — ...— — . — — ..—.-. 27

Tainoceras.......................................^...... 4,7,12,13,24 25,26,27,32,34

cavatum........................................... -.-. ——.-——... —— — 25

clydense..—-------.............. ..... _-_-_———...—.... ———.——— 25

comptum. ---------- — — ---_-.-_. — _ — _ — — _ —— — -.- — -----_-_.. 25

debile...... — ......................—........- .....- —...- ————.—-— 25

duttoni........----------_.-_.--___---_-.-.-_-_------—.-_ ——....... 25

Idipsteini...... ---------------- — -....-...-.-----------.--.----.- — —... 7,25

mingshanense.......................-.-.......... — -...........----------- 25

monolifer........... .....-.....—. . ———.——-...— „...-—...... 25

murrayi............--.

nebrascense...........

nodocarinatum........

noetlingi subglobosum. 

occidentale. ....______.

orientale...... .......

guadrangulum........

rotundatum.-...-.-.-. 

schellbachi.............

toulai..--..-...------.

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

___—__ — —_- — _- —-_-_-_-_-_- — -. 25

.--._--..._ — . — _. — — _ — — -- — _ — — 25

_---_-__- —— —— —— — _-----_——--_.. 25

__.-__ ——_ — -. — _-_ — - — ----_---.-. 25

.-. — -.-......-.-.. —-.. — ..-... — ....-... 25

..... ._._._._.--_----_-_-_-.---------.-.-. 25

.-. — — .-. — -.-_ — -. —— - — — —— .-.-... 25

...... — — -- -._..---------------- --_-_- 25

._._ ——. — ..._ ——— -.——— — — — — .- 25

.........— —— ...........-..----.... — .-.- 25

...-_._.___-__ -.-...... — ...... — .. — ...... 25

— ...... —— -. ——— -........ - — ._ — —.- 13

........ ——— .-.-....-....—— __-____ — .-. 25

—— — .....-.-. ——— -.- —— ......—......... 25

— __- _. — — -.--- __-_____-- — -.- —— -.— 25

Tainoceratidae------------------------------------ 4,6,7,9,10,11,12-45,47,48,54,74

taramelli, Pleuronautilus (Pleuronautilus)... __ —— ....-„ ————.—————— 36

tastubensis, Temnocheilus multituberculatus... ______.__--_--.--_-_____-_ — —. 18

telleri, Pleuronautilus (Tr achy nautilus)—.-......... .......................— 44

Temnocheili................................................................... 21

Temnochettidae—........................................................ 4,12,26,44

trautscholdi.. 

trimuense.... 

tuberculatum. 

unMesbayi... 

wyominyense. 

zmajevacense.
104 INDEX

quinqueliratus . 

schloenbachi. ..

Page 

TemnocheUua.......... ................................ ... .... ... .. ... 4,12,^7,18,33

acanthicus- ................................. ... . ______ ... ___ _ . 18

asiaticus. ............ ... .............. ....... ... ... ........... _____ .. 18

atuberculatus-.. .... — -- — .. - — . — — .——. — .__ ___ . __ ...... __ 18

augusti... ... ... . ... ..... ... ... ..... ... ............................ ... .... 21

cassianus. ........................ ... ... ....................... ...... ..... 21

crassus- .... — — ----—— — ------.- — ---- — ------_-........_-_._.___.__.___. 21

gemmettaroi. ----- ---------.----- — ------ — --- — -.-- .... .................. 18

grewingki.. .-.- — ...- — --.-.-. ....... - — ......--.-.-....-.....-.-.-....... 18

harneri . .... -_--_-_---__-_-.-.-__ — -.-.----_...-_-_-_-___-_._._ _ ..... .. 18

inaequilateralis — ............................................ .............. 18

johnsoni. ......--...- .. ... .... .. --------- _ .. ___ ....... _ .......... 18

tow*— ———— — —— — .- — - — ———--.— --.--..-—- 17, 18, pi. 1

medioventralis.-. ...'.-........................................ ..... .._.„__ 18

morloti ...... .. --.-----.----------.-.-.-----.-.--------..-----.-.-.-....... 21

muUituberculatus ..... ..................................................... 18

simensis. .................... ... - — ..-.-....... ........ _ .. _ ..... 18

tattubentis. .-..--.-..-..-.-.. — . .... — - ——- — -----_-----_-.__..-.-___ 18

neumayri. ... __-______-___-_-_._-_-------.---_._-----_.._.-..-___-. __ ... 4,21

nikttini..... — — ...-. — .-... ------- —— ----- ——— - — _ — _-._.-_...._. 18

ornatissimus.----- --------- --------------- ——---————---------- — ... 18

posttuberculatus.. ................ — -............-.. .... ... ..-..-...--.... 18

kosswae.--.- --______- __ ......-.---------.----.-... __ ............ 18

waschkuricus- __ ... _ _..__.——— — --.-._--_--_- ___ _ ...... _ 18

...... ... ... --------------------- — ..-- ——— ..-_-___.___ 18

...... . — .—.... .....--.. — -----.. ..... . ... ............... 21

iubrectangvtorti— ------------------------ ------ ——— ...- _ .-.-.-.-..... 18

tuberculatus. ... --------------------- ------------- — .--_ _ ------ _ .. 18

waageni ... ------------------------------- — -— ——— ..................... 18

winslowi ... _____--- —— .-.----...---- —— .. — .. —— _--..---.-....___. _ 18

(Temnochettus) coronatus, Nautilus .... ... ... .-...--......--...-.-.-.. ... ...... 4,17

tenuireticulatum, Syringoceras. .. — .... ........... .. ————— .-... — .......... 61

Terebratula. ... .. .... ...... ......... .... ....... .... .... . ....... ............ ... 31

texanum, Cooperoceras....-- — — -- ... ------ ———————— —— ..-.-.-....---.. 4,26

Thuringionautilus.. ..... _ ______ .. _ .. ___ . ___ .. __ .. 4,7,12,13,25,28,35

jugatonodosus. ........... ... . ... ...... ..... ................... ...... .... .. 25,32

klipsteini... ............................................................... 32

rectangularis... ......... ... .......... .... ... ... . ........ ........ .......... 32

tibeticus, Pleuronautilus (Enoploceras)........-.-.. ... -.-.—... __ .... _ ... .. 41

timorense, Syringoceras zitteli-------. .... ... ................................... 61

timarensis, Clydonautilus noricus.. ............................................ 89

Clydonautttus salisburgensis ....... ... ................... ... . ... ... ... ... .. 89

Prodydonautilus gasteroptychus .... .. ....--..---.....-......... .... ........ 10,81

tinloretti, Nautilus.. ... ....... ... .... ...... . .... ... ............ ..... ..... ..... 74

Ttrolites.. ... . ... ... ... . .......... .... ————— . ——— . —— . ———————— _. 2

Tirolonaufilus. .................................................... 4,12,13,26,27,33

crux.... --------------- — ..-'-..-. ———— ... — .-.. —— .- — ——— -... — 27

hoernesi. .... ---------------------- —— ------ —— —————— ------ — ... 27

Tttanocercu..— ...... .--.—.. ................ .................... 5,11,45,48,58,59

toddanum, Domatoceras. ............... ... —-- — —-—_------.----._..._..._.__ 51

Stearoceras .... .................... ... ... ... ---- ...... ...... ... .... ........ 58

tommasi, Paranautilus ....... ... ..... .... ............ ........ . .... . .... .... .... 69,71

Pleuronautilus (Pleuronautilus).-.- — . .......... ... ... ..... .... ... . ... ... 36

toulai, Tainoceras... ... . .... ...... ... .... ... .. ..... ... ... ... ... . .......... .... 25

Trachyceras— ..................... .. ——— - ———————— ... — - ————— ----- 82,83

trachyceras, Tainionautilus........ ... ... --------- — -.._-... — — .. — . — ... 27

TratAytMUtUus...... ........................................... 5,6,7,12,17,32,^,45

( Trachynautilus) clathratus,.Pleuronautilus ..... ... ..... . ... . ... ........... .... 44

laevis, Pleuronautilus . ... ............. ... ------------------------ —— .--._ 44

minuens, Pleuronautilus..--.--.. ... ... . ... . ...... ................ ... ..... 44

nodulosus, Pleuronautilus--...--.---------.-.^-------------- — -- ... ....... 44

subgemmatus, Pleuronautilus- .—. ------------------------------- — --..... 44

telleri, Pleuronautilus.....--..--.-. ......... ... ----- — -_-_---_.---...... 44

trilineatus, Pleuronautilus.. ............... ... ... .... .. —— — ------- —— .. 44

transitorius, Nautilus ... .... ------------------------- — ----- ------- — — 4,26,34

roimo7ioaf««s- ------------------------------------------------------ 26, 27

trapezoidalis, Juvavionautilus.— .-.-.-- ... --- ............. ... ... .... .... ... .... 63

trautscholdi, Nautilus... ... . ....... . ........ . ............ ......... ... . ........ 26

Tainoceras.... .... .... .. ..... ... - ---- ... ----- --- .... — — — — ——— ------ 25

----------------------------- —— .———...— 25,28,33

jugatonodosus. ------- ... ... ...... ... ...... .-. .... ——— ————— ————— 4,32

klipsteini... ................................ —... . ... ......... ... . ———— 26

Page 

triadicus, Clydonautttus................ ....-.— —.... ——...._-_...-........ 81

Nautilus... _._-.--_--___ ----_—_----_-.- — ...- — -._-.-._____.--_.__-. 81

Prodydonautilus--..--. — ..................................--------- 3, 81, pi. 9

Clydonautttus (Prodydonautilus).-...........................___....... 81

tricarinatum, Metacoceras (Metacoceras) —---------... -- — . — — — — — -.—-._._. 20

parvinodosum, Metacoceras (Metacoceras)—- ...-.--.-.-... —— -...--...-... 20 

trigonotuberculatum, Metacoceras (Metacoceras) -------------------_-..--..... 20

trilineatus, Pleuronautilus (Trachynautilus)--.....---...--- ... .. ........... 44

trimuense, Tainoceras............................... — ........................ 25

trinodosus, Ceratites.... _-._.___.__-_________-_-_-_-.——T _.___...__ 30,54,71

Pleuronautilus.... . —..-,—-.--.---.----.-..---------...--.__—..-.-. 4,33

Pleuronautilus (Pleuronautilus).--.----.----.-----..-.........___..... 36

triserialis, Pleuronautilus (Pleuronautilus).................--______._ 36

Trocholites.------.............. — ..... —..................................... 12

Tropites subbuttatus—...... ............. .................. 3,56,82,83,84,85,86,87

tschernyschewi, Metacoceras (Metacoceras)--...---.-..---...................... 20

tschihatscheffi, Pleuronautilus (Pleuronautilus)-..---.-......................... 36

tubercularis, Pleuronautilus (Pleuronautilus)....----....^..................... 36

tuberculatum, Tainoceras...................................................... 13

tuberculatus, Nautilus..-..-------------.------------.........--............... 26

TtemTiocftdiMS--.---------------------------------------------__.._..-.. 18

tuberosum, Metacoceras (Metacoceras).....---.-------.-....................... 20

tularosense, Stenopoceras...................................................... 58

Tumidonautilus............................................................... 73

turgidus, CaUaionautilus.......-....---........----------__________ 5,87-88

turneri, Metacoceras (Mojsvaroceras)-..--.. _-___—__-_____,_-----__ 3,21,53,pi. 2

Mojsvaroceras.- ............. — — . — .. — ....-.-.-..-.-.................... 23

tuvalicus, Prodydonautilus.-........ — — ............................——.... 81

U 

ufimskensis, Foordiceras.............--..............................---------- 19

umbilicatum, Domatoceras............................................------- 5,51,54

Grypoceras (Domatoceras)................................................. 55

unklesbayi, Metacoceras (Metacoceras)...---------... ......................... 20

Tainoceras................ ——... — ------------------- — __._ —— -------- 25

ursensis, Prodydonautilus.....-----——--____ — -——— — .____ 3,81,83,pi. 11

V

vagans, Metacoceras (Metacoceras)... .....

ventricosum, Metacoceras (Mojsvaroceras). 

venustum, Parametacoceras .... ...........

Pleuronautilus (Pleuronautilus)..---- 

verae, Nautilus.

..... . ..... ....... ... . ..... ... 20

. .... .......... ... ... ..... . .... 21

.... ..... — ----- — ------- — . 24

..-..-.---------.-.---- -... . ... 36

... ...... ...... . ———————— 21

Pleuronautilus (Pleuronautilus). ... ....................................... 36

vihianum, Qrypoceras (Grypoceras). ................ .... ----- — . ———————— 53

W

Waagen,dted— - — .———- — — — ——---——.--———-. — --. 18,26 

quoted.. ———————— ........ — ————— .... —————— . ——— - ——— 18

waageni, Temnochettus .. ... .. — — — — —— — . ——— —— — — --------- ——— 18

ualcatti, Metacoceras-.---.-- ... — — -- —— — — ——— - — — —— _.._-- — _ —— 19

Metacoceras (Metacoceras) ... -------------- — — _. —— -. —— .... — - — -. 20

watteri, Domatoceras. ... ————— ----- ——— - — —— ——————— . ————— . 51

Qrypoceras (Domatoceras)-..--.--- ... ,... ..... --------------------- — —— 55

wangi, Pleuronautilus (Pleuronautilus) .... . ... ...... ---------- __ ....---..... 36

waschkuricus, Temnocheilus posttuberculatus. ........ . .......... ------- ——— - . 18

weUeri, Phloioceras. .... ... .... .... ............. ... — -.-----—._ — .. ... .-. —— 45

Wliiteaves, quoted...... — -. — -. — — . — ----------- — - ---_-.__-_--_----- 75

whitei, Stenopoceras.... ........--.-. ... .... ..... ..... . .... ... ... .... .... ..... 58

uhitneyi, Qrypoceras....- .... - ....... - —— - ———— „-- —————— — - ——— - 51

Grypoceras (Grypoceras)...-.--.—- ... . ——— ... — - ——— - —— - 2,53, pis. 5,6

Nautilus—— ....................................................... ...... 53

wittiamsi, Domatoceras..... ... ................ ... ....... — ........ ... ------ .. 48, 51

Qrypoceras (Domatoceras)-.--.------ — - —— . —— . —— .-..—...-. —— 53,54,55

winslowi, Temnochettus....----- .... .... ... ....—-.... .... . .... .. .... .......— 18

wulfeni, Nautilus--.-------------------------.-------------------.-.----. 4,33,39

Pleuronautilus (Enoploceras) ... ........................................... 41,42

wulfeniformis, Pleuronautilus (Enoploceras)----- — - — ------------- _ --------- 41

wynnei, Tainionautilus--.... .-...-- — ...... .,-... ... - — .___.-. ..---------... 27

wyomingense, Tainoceras— ... —————— — --------.-.--...-- — ----- — ------ 25

zinnae, Syringonautilus.. ....-——. —— ————. —————————...————- 60

zitteli, Syringoceras... ___--_-- —— — —— — - — -_..__ ——. ——— —— --------- 61

timorense, Syringoceras... _____._.-..-_. —. —.. —....--. — ..--. — -.- 61

zmajevacense, Tainoceras...................... ...-------------...... —.—... 25

o
PLATES 1-19

232820—53-——9
PLATE 1

[All figures natural size]

FIGURES 1, 2. Temnocheilus latus (Meek and Worthen) (p. 17).

Holotype, University of Illinois, X-438A. From a formation of Pennsylvanian age, Carbon Cliff, Rock* Island

County, Illinois. 

3, 4, 5. Metacoceras sangamonensis (Meek and Worthen) (p. 19).

Holotype, University of Illinois, X-291 (11074). From the McLeansboro formation, Sangamon County, Illinois.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 1

TEMNOCHEILUS AND METACOCERAS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 2

12

METACOCERAS
PLATE 2

[All figures natural size

FIGURES 1-10. Metacoceras (Mojsvaroceras) frenchi Kummel, n. sp. (p. 23).

1. Holotype, U.S.N.M. 107069; 2, paratype, U.S.N.M 107070; 3, paratype, U.S.N.M. 107071; 4, 5, paratype, 

U.S.N.M. 107072; 6, paratype, U.S.N.M. 107073; 7, paratype, U.S.N.M. 107074; 8, paratype, U.S.N.M. 107075; 

9, paratype, U.S.N.M. 107076; 10, paratype, U.S.N.M. 107077. Figures 1-9, from upper shale member (Columbites zone) of the Thaynes formation, Montpelier Canyon, Idaho, sec. 31, T. 12 S., R. 45 E. Figure 10 from same 

horizon of Thaynes formation, Hot Springs, Idaho, sec. 18, T. 15 S., R. 45 E. 

11—14. Metacoceras (Mojsvaroceras) turneri Hvatt and Smith (p. 23).

11, 12. Holotype, U.S.N.M. 74026; 13, 14, paratype, U.S.N.M. 74026a. From Upper Triassic Hosselkus limestone, in the Juvavites subzone of the Tropites subbullatus zone, 3 miles east of Madison's ranch, between Squaw 

Creek and Pit River, Shasta County, California.
PLATE 3

[All figures natural size] 

FIGTJBES 1-10. Germanonautilus brooksi Smith (p. 29).

1, 2, Holotype, U.S.N.M. 74206; 3, 4, 5, paratype, U.S.N.M. 74206; 6, 7, 8, topotype, U.S.N.M. 107087; from 

U.S.G.S. locality 9384, south bank of Yukon River opposite mouth of Nation River, Alaska; 9, 10, Plesiotype, 

U.S.N.M. 107086. From U.S.G.S. locality 9385, Nation River, hillside one third mile northeast of mouth of 

Yukon Valley, Alaska. 

11. Germanonautilus montpelierensis Kummel, n. sp. (p. 30).

Holotype, U.S.N.M. 107089. From upper shale member (Columbites zone) of the Thaynes formation, Hot Springs,

Idaho, sec. 18, T. 15 S., R. 45 E. 

12, 13. Germanonautilus furlongi Smith (p. 29).

Holotype, U.S.N.M. 74444. From the Daonella dubia zone of the Star Peak formation, Fossil Hill, West Humboldt Range, Nevada. 

14, 15. Germanonautilus johnstoni Kummel, n. sp. (p. 30).

Holotype, U.S.N.M. 107088. From Star Peak formation, South Canyon, New Pass, Desatoya Range, Nevada.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 3

15

GERMANONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 4

10

i

12

PLEURONAUTILUS
PLATE 4

[Figures natural size except as indicated

FIGURE 1. Pleuronautilus (Enoploceras) newelli Kummel, n. sp. (p. 41).

1. Holotype, U.S.N.M. 107085. From upper shale member (Columbites zone) of the Thaynes formation, Montpelier

Canyon, Idaho, sec. 31, T. 12 S., R. 45 E. 

2, 3, 4. Pleuronautilus iddhoensis Kummel, n. sp. (p. 37).

2. Holotype, U.S.N.M. 107079. From upper shale member (Columbites zone) of the Thaynes formation, Hot Springs,

Idaho, sec. 18, T. 15 S., R. 45 E; 3, 4. Paratype, U.S.N.M. 107080. From same locality and horizon as figure 1. 

5, 6. Pleuronautilus alaskensis Kummel, n. sp. (p. 34).

Holotype, U.S.N.M. 107082. From U.S.G.S. locality 13749, Chitistone limestone (Upper Triassic, Karnian) from

the flats at base of Kennicott glacier, 5 miles north of Kennicott, Chitna Valley, Alaska. 

7. Phloioceras sp. (p. 44).

Ventral view. U.S.N.M. 107094. From point at north entrance to Herring Bay, Admiralty Islands, Alaska. 

8, 9, 10. Metacoceras (Mojsvaroceras') frenchi Kummel, n. sp. (p. 23).

Paratype, U.S.N.M. 107078. From same locality and horizon as figure 1. 

11, 12. Paranaiitilus smithi Kummel, n. sp. (p. 71).

Plesiotype, U.S.N.M. 32644. From Middle Triassic, Fossil Hill, Nevada.
PLATE 5

[Figures natural size except as indicated]

FIGTJBE 1. Grypoceras (Grypoceras) whitneyi (Gabb) (p. 53).

Holotype from Buena Vista District, Humboldt Mining region, Nevada, (after Gabb, 1863, pi 3, fig. 2). 

2, 3. Grypoceras (Grypoceras) mesodicum (Hauer) (p. 53). 

After Mojsisovics, 1873, pi. 8, fig. la, b). X 0.5. 

4. Grypoceras (Plummeroceras) plummeri Kummel, n. sp. (p. 54).

Holotype, Bureau of Economic Geology 7173, from Belle Plains formation, 2% miles west of Baird, Callahan County, 

Texas. X 0.83.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 5

DOMATOCERAS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 6

DOMATOCERAS
PLATE 6

[All figures natural size]

FIGURES 1-4. Grypoceras (Grypoceras) whitneyi (Gabb) (p. 53).

Plesiotype, U.S.N.M. 74459, from Middle Triassic, zone of Ceratites trinodosus, Wheeler mine, Buena Vista Canyon,

near Unionville, West Humboldt Range, Nevada. 

5, 6. Grypoceras (Grypoceras) milled Kummel, n. sp. (p. 53).

Holotype, U.S.N.M. 107095, from Dinwoody formation, Slight Canyon, Paris-Bloomington region, southeastern 

Idaho.
PLATE 7

>• [Figures natural size except as indicated]

FIGURES 1-5. Gryponautilus cooperi Smith (p. 56).

1, 2, 3. Holotype, U.S.N.M. 74127; 5, 6, paratype, U.S.N.M. 74127a. From the Upper Triassic Hosselkus limestone, upper or Juvavites subzone of the zone of Tropites subbullatus, Bear Cove, north end and east side of Brock 

Mountain, between Squaw Creek and Pit River, Shasta County, California. 

6, 7. Syringoceras spurri Smith (p. 63).

Holotype, U.S.N.M. 74219. From Pseudomonitis zone of Star Peak formation, Muttleberry Canyon, West Humboldt Range, Nevada. 

8, 9. Clymenonautilus ehrlichi (Mojsisovics) (p. 65).

After Mojsisovics 1873, pi. 6, fig. 9a, b. 

10-19. Proclydonautilus spirolobus (Dittmar) (p. 82).

10-11. Plesiotype, U.S.N.M. 14128; 12, 13, plesiotype, U.S.N.M. 14128a; 14, 15, 16, plesiotype, U.S.N.M. 14128b; 

17, 18, 19, plesiotype, U.S.N.M. 14128c. All specimens from same locality as figures 1-5.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 7

11

GRYPONAUTILUS, SYRINGOCERAS, CLYMENONAUTILUS, AND PROCLYDONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 8

13

PROCLYDONAUTILUS, PARANAUTILUS, AND SIBYLLONAUTILUS
PLATE 8

[Figures natural size except as indicated]

FIGURES 1-7. Proclydonautilus squawensis Kummel, n. sp. (p. 83).

1, 2. Holotype, U.S.N.M. 74124; 3, 4, paratype, U.S.N.M. 74124a; 5, 6, 7, paratype, U.S.N.M. 74124b. From 

Upper Triassic Hosselkus limestone, in the upper or Juvavites subzone of the zone of Tropites subbullatus, at the 

north end of Brock Mountain, between Squaw Creek and Pit River, Shasta County, California. 

8, 9. Paranautilus sp. (p. 72).

Plesiotype, U.S.N.M. 107098. From north side of Union Canyon about \Yz miles above its mouth, from Triassic 

limestone (Luning (?) formation) above contact with volcanic rocks, Shoshone Range, Tonopah Quadrangle, 

Nevada. 

10, 11. Sibyllonautilus fergusoni Kummel, n. sp. (p. 74).

Holotype. U.S.N.M. 107099. From U.S.G.S. locality 13420, Gabbs formation, 2/l 2 miles north of mouth of New

York Canyon, Gabbs Valley Range, Nevada. 

12, 13. Paranautilus smithi Kummel, n. sp. (p. 71).

Holotype, U.S.N.M. 74445. From Middle Triassic Daonella dubia zone, Fossil Hill, south Fork of American Canyon, 

4 miles south of Fitting post office (formerly Foltz), West Humboldt Range, Nevada.
PLATE 9

[Figures natural size except as indicated]

FIGURES 1-20. Proclydonautilus triadicus Mojsisovics (p. 81).

1, 2. Plesiotype, U.S.N.M. 74027; 3, 4, 5, Plesiotype, U.S.N.M. 74027a; 6, 7, 8, plesiotype, U.S.N.M. 74027b; 

9, 10, 11, plesiotype, U.S.N.M. 74027c; 12, 13, 14, plesiotype, U.S.N.M. 74027d; 15, 16, 17j plesiotype, 74027e, 

18, 19, 20, plesiotype, U.S.N.M. 74027f. From Upper Triassic Hosselkus limestone, in both subzones of the 

Tropites subbullatus zone, 3 miles east of Madison's ranch, between Squaw Creek and Pit River, Shasta County, 

California. .
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 9

PROCLYDONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 10

7 ate^^W 8

PROCLYDONAUTILUS AND COSMONAUTILUS
PLATE 10

Figures natural size except as indicated]

1—6. Proclydonautilus stantoni Smith (p. 82).

1, 2, 3. Holotype, U.S.N.M. 74123; 4, 5, 6, paratype, U.S.N.M. 74123a. From the Upper Triassic Hosselkus 

limestone, in the upper or Juvavites subzone of the zone of Tropites subbullatus, at the north end and west side 

of Brock Mountain, between Squaw Creek and Pit River, Shasta County, California. 

7-15. Cosmonautilus hersheyi Smith (p. 87).

7, 8, 9. Holotype, U.S.N.M. 74130; 10, 11, 12, paratype, U.S.N.M. 74130a; 13, 14, 15, paratype, U.S.N.M. 74130b. 

All from same Juvavites subzone as figures 1-6, at north end and east side of Brock Mountain, between Squaw 

Creek and Pit River, Shasta County, California.
PLATE 11

(Figures natural size except as indicated]

FIGURES 1-8. Proclydonautilus ursensis Smith (p. 83).

1, 2. Holotype, U.S.N.M. 74122; 3, 4, 5, paratype, U.S.N.M. 74122a; 6, 7, 8, paratype, U.S.N.M. 74122b. From 

the Upper Triassic Hosselkus limestone, upper or Juvavites subzone of the zone of Tropites subbullatus, north 

end and east side of Brock Mountain, between Squaw Creek and Pit River, Shasta County, California.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 11

\%

X 8

^^^L^^^^^rf^:/ '

PROCLYDONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 12

COSMONAUTILUS
PLATE 12

[Figures natural size except as indicated]

FIGURES 1-4. Cosmonautilus dilleri Hyatt and Smith (p. 85).

1, 2. Plesiotype, U.S.N.M. 74463a, front and rear views of specimen shown on plate 13, figure 1, X 0.87; 3, 4, 

plesiotype, U.S.N.M. 74463c. From Upper Triassic Hosselkus limestone, upper or Juvavites subzone of the 

zone of Tropites subbullatus, north end and west side of Brock Mountain, between Squaw Creek and Pit River, 

Shasta County, California.
PLATE 13

[ Figures natural size except as indicated]

FIGURES 1-7. Cosmonautilus dilleri Hyatt and Smith (p. 85).

1. Plesiotype, U.S.N.M. 74463, side view of specimen shown on plate 12, figures 1, 2, X 0.87; 2, 3, 4. Plesiotype, 

U.S.N.M. 74028; 5, 6, 7, plesiotype, U.S.N.M. 74028a. From Upper Triassic Hosselkus limestone, in the Juvavties 

subzone of the zone of Tropites siibbullatiis zone, 3 miles east of Madison's ranch, between Squaw Creek and 

Pit River, Shasta County, California.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 13

^ • OKv , * • -* . . »

COSMONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 14

X2

X 2

10

COSMONAUTILUS, PARANAUTILUS, AND SIBYLLONAUTILUS
PLATE 14

Figures natural size except as indicated]

FIGURES 1-6. Cosmonautilus dilleri Hyatt and Smith (p. 85).

1, 2, 3. Cotype; 4, 5, 6, cotype, U.S.N.M. 74028. From Upper Triassic Hosselkus limestone, in the Juvavites 

subzone of the Tropites subbullatus zone, 3 miles east of Madison's ranch, between Squaw Creek and Pit River, 

Shasta County, California. (After Smith, 1927, pi. 55, figs. 6-11). 

7, 8. Paranautilus multicameratus (Gabb) (p. 71).

Holotype from near the Auld Lang Syne Mine, Sierra district, Humboldt County, Nevada. (After Gabb, 1864,

pi. 3, fig. 4, 5). 

9, 10. Sibyllonautilus liardensis (Whiteaves) (p. 75).

Holotype from Upper Triassic on Liard River, 25 miles below Devils Portage, British Columbia, at horizon of 

Dawsonites canadensis. (After Whiteaves, 1889, pi. 18, figs. 1, la).
PLATE 15

[Figures natural size except as indicated]

FIGURES 1—11. Cosmonautilus shastensis Smith (p. 86).

1, 2. Holotype, U.S.N.M. 74126; 3, 4, 5, paratype, U.S.N.M. 74126a; 6, 7, 8, paratype, U.S.N.M. 74126b; 9, 10, 

11, paratype, U.S.N.M. 74126c. From the Upper Triassic Hosselkus limestone, upper or Juvavites subzone 

of the zone of Tropites subbullatus, Bear Cove, north end and east side of Brock Mountain, between Squaw 

Creek and Pit River, Shasta County, California. 

12-15. Proclydonautilus hessi (Smith) (p. 83).

12, 13. Holotype, U.S.N.M. 74129; 14, 15, paratype, U.S.N.M. 74129a. From same locality as figures 1-11. 

16. Styrionautilus sp. (p. 80).

U.S.N.M. 108001. From Middle Triassic (Anisian), South Canyon, New Pass, Desatoya Range, Nevada.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 15

COSMONAUTILUS, PROCLYDONAUTILUS, AND STYRIONAUTILUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 16

10

12 X2

COSMONAUTILUS
PLATE 16

[Figures natural size except as indicated]

FIGURES 1-14. Cosmonautilus pacificus Smith (p. 85).

1, 2. Holotype, U.S.N.M. 74125; 3, 4, 5, paratype, U.S.N.M. 74125a; 6, 7, 8, paratype, U.S.N.M. 74125b; 9, 10, 

11, paratype, U.S.N.M. 74125c; 12, 13, 14, paratype, U.S.N.M. 74125d. From the Upper Triassic Hosselkus 

limestone, Juvavites subzone of the zone of Tropites subbullatus, at the north end of Brock Mountain, between 

Squaw Creek and Pit River, Shasta County, California.
PLATE 17

[Figures natural size except as indicated]

FIGURES 1, 2. Pleuronautilus (Anoploceras) ampezzanus (Loretz) (p. 43).

From the Karnian of the Alps (after Mojsisovics, 1882. pi. 84, figs, la, b). X 0.66. 

3, 4. Pleuronautilus (Holconautilus) semicostatus (Beyrich) (p. 42).

From the Anisian of the Alps (after Mojsisovics, 1882, pi. 86, figs, la, b). X 0.7. 

5, 6. Phloioceras gemmatum (Mojsisovics) (p. 44).

From the Karnian of the Alps (after Mojsisovics, 1837, pi. 3, figs, la, b). X 0.5 

7, 8. Pleuronautilus (Trachynautilus) subgemmatus Mojsisovics (p. 44).

From the Anisian of the Alps (after Mojsisovics, 1882, pi. 85, figs. 2a, b). 

9, 10. Pleuronautilus (Encoiloceras) superbus (Mojsisovics) (p. 42).

From the Karnian of the Alps (after Mojsisovics, 1873, pi. 4, figs, la, b). X 0.65.
GEOLOGICAL SUEVEY PROFESSIONAL PAPER 250 PLATE 17

PLEURONAUTILUS AND PHLOIOCERAS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 18

JUVAVIONAUTILUS, SYRINGONAUTILUS, SYRINGOCERAS, STYRIONAUTILUS, AND INDONAUTTLUS
PLATE 18

[Figures natural size except as indicated]

FIGURES 1, 2. Juvavionautilus heterophyllus (Hauer) (p. 63).

From the Norian of the Alps (after Mojsisovics, 1902, pi. 4, figs. 2a, b). X 0.75. 

3, 4. Syringonautilus lilianus (Mojsisovics) (p. 60).

From the Anisian of the Alps (after Mojsisovics, 1882, pi. 82, figs. 3a, b). 

5, 6, 7, 8. Syringoceras granulosostriatum (Klipstein) (p. 60).

From the Karnian of the Alps (after Mojsisovics, 1882, pi. 82, figs. Sa, b; 9a, b). 

9, 10. Styrionautilus styriacus (Mojsisovics) (p. 80).

From the Karnian of the Alps (after Mojsisovics, 1873, pi. 14, figs. 7a, c). 

11, 12. Indonautilus kraffti Mojsisovics (p. 72).

From the Norian of the Himalayas, India (after Mojsisovics, 1896, pi. 21, figs. 2a, b). 

13. Syringoceras barrandei (Hauer) (p. 60).

From the Karnian of the Alps (after Mojsisovics, 1902, pi. 5, fig. 2a).
PLATE 19

[Figures natural size except as indicated]

FIGURES 1, 2. Oxynautilus acutus (Hauer) (p. 63).

From the Norian of the Alps (after Mojsisovics, 1902, pi. 3, figs, la, b). X 0.75. 

3. Tainionautilus trachyceras Frech (p. 27).

From the Scythian of the Salt Range, India (after Frech, 1905, pi. 26, fig. 2). X 0.6. 

4, 5. Gonionautilus securis (Dittmar) (p. 89).

From the Norian of the Alps (after Mojsisovics, 1902, pi. 1, figs, la, b). X 0.66. 

6, 7. Callaionautilus turgidus Kieslinger (p. 87).

From the Norian of Timor (after Kie4inger, 1924, pi. 5, figs, la, b). X 0.66.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 250 PLATE 19

2 *^^^^T 7 

OXYNAUTILUS, TAINIONAUTILUS, GONIONAUTILUS, AND CALLAIONAUTILUS