Callovian (Jurassic) 

Ammonites from the 

United States and Alaska 

Part 2. Alaska Peninsula and Cook Inlet Regions 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 249-B 
Callovian (Jurassic) 

Ammonites from the 

United States and Alaska 

Part 2. Alaska Peninsula and Cook Inlet Regions 

By RALPH W. IMLAY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 249~B· 

Descriptions and illustrations of 

cephalopods of Late Jurassic age 

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 Office 

Washington 25, D. C. -Price $1.75 (paper cover) 
CONTENTS 

Abstract----------------------------~--------------

Page 

41 

41 

41 

48 

48 

48 

49 

49 

51 

54 

54 

55 

55 

55 

55 

Comparisons with other faunas-Continued 

Introduction ______________________________________ _ Pacific coast region of Canada and United States __ • 

Biologic analysis ___________________________________ _ 11exico ____ ~---------------~------------------- Stratigraphic summary ___ ------ ____________________ _ Ecologic considerations ___________________ ---- ___ ---_ 

Alaska Peninsula region _____________ -____________ _ Conditions of deposition ________________________ _ 

Shelikof formation ___________________________ _ Faunal assemblages _____________ - _____ -_- ___ ----

Cook Inlet region __ :.. ___________________________ _ Ecologic implications ___________________________ _ 

Chinitna formation _______________ ..: __________ _ Depth of water ___________ · ________ - _ - ___ ·- _ - _ 

Age of the faunas __________________________________ _ Temperature and climate ___ ..: __________ . _____ _ 

Comparisons with other faunas ______________________ _ IIabitats_:.. ________________________________ _ 

Western interior of the United States and Canada __ Geographic distribution __ . ___________ -- _____ -_- ___ -_--

Arctic region of Canada ________________________ _ Summary of results _____________________________ ·-_-_ 

Arctic region of Alaska ___________________ ~ _____ _ ·Systematic descriptions _____________ ------ __ ----_---_ 

East Greenland and Barents. sea _________________ _ References-----------------------------------------

Northwest Europe and central Russia-----~------- · IndeX----------------------------------------~----

FIGURE 3. 

4. 

5. 

6. 

7. 

8. 

9. 

ILLUSTRATIONS 

[Plates 25-55 follow index] 

PLATE 25. Phylloceras. 

26. Oppelia and Phylloceras. 

27, 30. Lilloettia. 

28, 29. Lilloettia and Xenocephalites. 

31-33. Kheraiceras. 

34-47. Cadoceru.s. 

48. Pseudocadoceras and Kepplerites. 

49. Pseudocadoceras1 Kepplerites, and Cosmoceras. 

5Q-52. Kepplerites. · 

53. Procerites, Cosmoceras, and Gowericeras; 

54. Procerites. 

55. Reineckeia and Grossouvria. 

Index map of the principal areas of Jurassic rocks in the Alaska Peninsula and Cook Inlet regions, Alaska _____ _ 

Index map showing Callovian localities at head of the Matanuska ·Valley _________________________________ _ 

Index, map showing Callovian localities in the Tuxedni Bay area _________________________________________ _ 

Index map showing Callovian localities near Chinitna Bay ___ · _______________ .:. ___________________________ _ 

Index map showing Callovian localities in the central and southern parts of the Iniskin Peninsula ____________ _ 

Index map showing Callovian localities in the Puale Bay to Portage Bay area_·------------------·-----------

Index map showing Callovian localities in the Wide Bay area ____________________________________________ _ 

TABLES 

Pag~t 

56 

56· 

57 

57 

.58 

59 

sg. 

61 

64 

65 

71 

72 

103 

105 

Par• 

58 

59 

60 

61 

62 

63 

64 

PAI'I 

TABLE 1. 

2. 

3. 

Morphological comparisons of the various groups or subgenera of Cadoceras _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 4 7 

Stratigraphic ranges of Callovian ammonite species in. Alaska Peninsula and Cook Inlet regions ____ .____________ 50 

Stratigraphic ranges of Callovian ammonites in Alaska_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 52 

4. European ranges of certain ammonites present in Alaska ______ ~---------------------------------.:._________ 54 

5. . Correlation of Jurassic formations in the Alaska Peninsula and Cook Inlet regions _________________________ Faces 60 

6. Geographic distribution of the Callovian ammonites ·of the Alaska Peninsula and Cook Inlet regions _________ Faces 72 

lU 

.· 
CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

PART 2. ALASKA PENINSULA AND COOK INLET REGIONS 

By RALPH w. IMLAY 

ABSTRACT 

'£he ammonites from the Chinitna formation of the Cook 

Inlet region and the Shelikof formation of the Alaska Peninsula 

show that these formations are of early Late Jurassic age, 

represent most of the Callovian stage, and correspond with the 

northwest European zones of ProplanuUtes koervigi to Erym-

'ltOceras corona tum. The basal Callovian zone of M acrocephalites macrocephalus is possibly represented locally by some basal 

shelly sandstones. The highest zones of the Callovian are probably represented by an unconformity at the base of the Naknek 

formation. The ammonites from the lower third of the Chinitna formation and from the lower siltstone member of the 

Shelikof formation are similar to species in the lower Callovian 

beds of the western interior of the United States and of East 

Greenland. The ammonites from the higher parts of the Chinitna and Shelikof formations are younger than the marine 

Callovian of the western interior region, or of East Greenland, 

and greatly resemble the ammonites from the middle part of 

the Callovian of England and central Russia. 

Studies of the vertical ranges of the ammonites from the 

Chinitna and Shelikof formations show that ammonite collections can be localized within the lo,ver, middle or upper third 

of the formations, some collections containing certain associa~ 

tions of ammonites can be localized within much smaller intervals, and some estimate of the amount of pre-Naknek erosion 

can be obtained. Such data should be valuable to the field men · 

in their attempts to divide the formations into mappable members, which, considering the thousands of feet of sedimentary 

rocks involved, is desirable economically. 

Most probably the Callovian marine sediments were deposited 

along a steep slope, fronting a major ocean and were derived 

from mountains that lay immediately to the north. A fairly 

shallow water origin for the basal sheUy sandstone of the 

Chinitna formation is indicated by the presence of Meleagrinella 

and Ostrea. Other sandstones higher in the Chinima, or in the 

Shelikof, contain benthonic forms characteristic of the neritic 

zone. The siltstones were mostly deposited below wave base 

as they contain few benthonic mollusks and show persistent, 

thin, even-bedding. The presence of PhylZoceras and the absence of nautiloids is probably related to depth of water rather 

than to temperature, as the opposite faunal condition exists in 

the Callovian deposits of the western interior of the United 

States, where the associated mollusks indicate an environment 

representing the littoral zone or the shallow part of the neritic 

zone. The association of the thin-shelled PhyUoceras with the 

thicker-shelled cardioceratids suggests that fairly deep waters 

approached the shore so that the shells of these ammonites . 

became mingled easily after death. A cooling of the boreal sea 

of Late Jurassic time as compared with seas farther south is 

suggested by· the absence of corals, the rarity of gryphaeas and 

exogyras, the provincial cparacter of the ammonites, the poverty 

in molluscan genera and species, and the scarcity of calcium 

carbonate other than as concretions. 

INTRODUCTION 

This study of the early Late Jurassic ammonites of 

the Alaska Peninsula and Cook Inlet regions is based 

almost entirely on collections mad~ by field parties from 

the Geological Survey since 1903. The principal collectors were T. W. Stanton and G. C. Martin in 1904,. 

A. A. Baker and F. H. Moffit in 1921, S. R. Capps in 

1921, W. R. Smith in 1922 to 1924, lJ. B. Kellum in 1944 

and 1945, C. E. Kerschner in 1946, Don J. Miller in 

1948, and John K. Hartsock and Arthur Grantz in 1948 

to 1950. The writer spent the summer of 1948 with 

Don J. Miller examining typical Jurassic sections and 

collecting fossils at or near Tuxedni Bay, Chinitn·a Bay, 

Iniskin Peninsula, Puale Bay, and Wide Bay. This 

provided first hand field information that has been very 

useful in subsequent ·paleontologic studies requested by 

field men and in the preparation and analysis of the 

present report. In its preparation the objectives have· 

been to describe and interpret both biologic and strati-· 

graphic data in such· a manner as to be .immediately 

useful to field men, to suggest problems for future field. 

consideration, and to show the relationships of the· . 

Jurassic sedimentary rocks and faunas involved to· 

those of the Jurassic of the en~ire North American continent and the boreal region. It is believed that the 

results of broad objectives frequently have useful local 

implications. 

BIOLOGIC ANALYSIS 

The Callovian ammonites from Alaska now in the 

Geological Survey's collections include about 795 specimens of ammonites that are specifically identifiable. 

Among these the Phylloceratidae is represented by 29 

specimens, the Oppelidae by 24 specimens, the Macrocephalitidae by 84 specimens, the Cardioceratidae by 

621 specimens, the Cosmoceratidae by 36 specimens, the 

Morphoceratidae by 1 specimen, and the Perisphinctidae by 5 specimens. The Cardioceratidae numerically 

comprise 78 percent of the ammonites. Within this 

family the genus Oadoceras comprises 61 percent and 

the genus Pseudocadoceras 17 percent of the total num41 
42 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

• ber of ammonites. Considering the number of species, 

the Phylloceratidae is represented by 5, the Oppelidae 

by 2, the Macrocephalitidae by 14, the Cardioceratidae 

by 24, the Cosmoceratidae by 13, the Morphoceratidae 

by 1, and the Perisphinctidae by 4. The ammonites 

are distributed among 19 genera and subgenera and 62 

species. Of these 1 subgenus and. 38 species are described as new, 8 species have been described previously 

from Alaskan collections, 9 have been described previously from collections from British Uolumbia, 1 is 

identified with a species from Greenland, 1 is compared 

with a European species, and 5 are not named because 

they are inadequately preserved. 

The Phy lloceratidae is represented in the Callovian 

deposits of Alaska by Phylloceras, Oalliphylloceras, 

M acrophylloceras, and Partschiceras. The Oppelidae 

is represen,ted by 2 species of Owycerites that are similar to species described from Europe. Owycerites has 

been obtained in Alaska, only from the· lower twothirds of the Chinitna formation and from the lower 

member of the Shelikof formation. 

The Macrocephalitidae in Alaska includes Lilloettia, 

X enocephalites and Kheraiceras. Lilloettia, known 

only from Alaska and British Columbia, differs from 

M acrocephalites, sensu strictu, by being more involute 

and generally more inflated, by having broader and 

more closely-spaced ribbing on the venter of its inner 

whorls, and by becoming smoother at an earlier growth 

stage. Lilloettia was suspected by Spath (1932, p. 156) 

as being identical with .A..rctocephalites of the Boreal 

region. However, on Lilloettia the umbilicus is consistently more narrow, the body shape generally more 

rotund, and the body chamber a little longer. Its ribbing is much more flexuous on the flanks, ge~erally 

arches forward on the venter, and tends to disappear 

from the flanks earlier than in Arctocephalites. In 

the young individuals of Lilloettia the ribs are low on 

the flanks, thick, rounded, and closely-spaced on the 

venter and have sloping sides. This contrasts with 

the thin, high ribs of Arctocephalites at comparable· 

growth stages. Another closely comparable form is 

Eurycephalite.s (Spath, 1928, p. 175), fro~p. South 

America and southern Mexico. It resembles, Arctocephalites more ·than Lilloettia in width of umbilicus 

and sharpness of ribbing, but its ribbing is flexuous as 

in Lilloettia. It is distinguished from both by a much 

simpler suture line. It is questionable whether any of 

these forms are worthy of more than subgeneric rank 

under M acrocephalites. Their differences may . be in 

part provincial and in part stratigraphic. Eurycephalites in South America occurs at several levels, associated with ammonites that indicate both late Bathonian and early Callovian ages (Burckhardt, 1903, p. 21; 

1930, p. 26, 27; Stehn, 1924, pp. 143-151). Arctocephalites is probably restricted to the upper Bathonian, as 

it is found in Montana, in the Richardson Mountains 

of northern Canada, and in east Greenland immediately below beds containing Arcticoceras, which genus 

marks the basal Callovian, as discussed elsewhere 

(Imlay, 1948, p. 14, 15). Lilloettia has been found in 

southwestern Alaska in the upper part of the lower 

member of the Shelikof formation and in most of the 

lower two-thirds of the Chinitna formation except the 

lowermost 500 to 600 ft. This occurrence probably cor_. 

responds to the calloviense and jason zones of northwest 

Europe. Unfortunately, Arctocephalites has not been 

found in southwestern Alaska, although a similar 

macrocephalitid, Oranocephalites, which immediately · 

underlies Arctocephalites in Greenland, has been found 

at many places a few hundred feet below the lowest 

occurrence of Lilloettia. Regardless of the explanation for the absence. of Arctocephalites, the ammonite 

genera associated with Lilloettia show that it occurs in 

beds younger than those with Arctocephalites. The 

speculation by Spath (1932, p. 156) that Eurycephalites spread to the boreal set via Alaska implies that 

Lilloettia and Arctocephalites were probably derived 

from Eurycephalites. This ·may be true, but the 

characteristics of Lilloettia and its stratigraphic position suggest that descent from .A..rctocephalite'8 is just 

as probable. 

The occurrence of several species of X enocephalites 

in southwestern Alaska is very interesting because the . 

genus appears to be fairly distinctive of the lower Callovian of the Pacific Province. One species is known 

from southern Mexico (Burckhardt, 1927, p. 33, pl. 16, 

figs. 4-9); five species and varieties from South America 

· ( Stehn, 1924, pp. 86-92, pl. 1, figs. 3-6), one species from 

east Greenland (Spath, 1932, p. 44, pl. 14, figs. 4 a-d), 

and two undescribed species from Montana. In ·Alaska 

X enocephalites ranges through the lower two-fifths 

of the Chinitna formation, but occurs also in underlying beds containing Oranocephalites. The species from 

Alaska and Montana were ·at first referred to K amptokephalites but their generic position in X enocephalites 

is indicated by their extremely narrow umbilicus, depressed whorl section, small size, and the early appearance of prominent, very flexuous ribs, that become very 

widely-spaced on the body chamber. The immature 

forms of X enocephalites differ from comparable forms 

of Kheraiceras by having much coarser, higher, more 

widely-spaced ribs and from comparable forms of Oranocephalites by having much thicker, more flexuous ribs. 

K heraiceras has been found in lower and middle Callovian'deposits in many parts of the world, but is probably nowhere represented by such variety as in Alaska. 

The adult is more ·or less inflated and has a very small 

umbilicus, a hook-like body chamber, and generally a 

pronounced apertural constriction. The suture line is 

finely divided and has broad saddles and lobes. The 

immature forms differ from similar forms of· Pleurocephalites by being sphaeroceratid in lateral view. They 
ALASKA PENINSULA AND COOK INLET REGIONS 43 

· differ from immature forms of Oadoceras by their 

smaller umbilicus, broader whorl section, and flexuous 

ribs. They differ from immature forms of Oranocephalites, or Arctocephalites by. being more inflated and 

by having weaker, denser, more flexuous ribbing. The 

adult whorls. of some of the least inflated species of 

f{h(}raice1'as resemble the adult whorls of Oranocephalites, but Kheraiceras can generally be distinguished 

by the sudden coarsening of the ribbing on the body 

chamber. The suture line, if preserved, is a certain 

means of distinction, as the highly frilled, broad saddles 

and lobes of Kheraiceras contrast greatly with the 

rather simple sutural elements of Oranocephalites. In 

southwestern Alaska Kheraiceras occurs in the lower 

two-thirds of the Chinitna formation and near the base 

of the Shelikof formation. 

The Cardioceratidae in the Callovian deposits of 

southwestern Alaska include the genera Oadoceras and 

. Pseudocadoceras, but not Arcticoceras. The absence of 

the Arcticoceras is probably significant, as the genus 

is abundant in the western interior of the United States 

and Canada and along the Arctic coast of Canada and 

Alaska. Spath ( 1932, pp. 50-52) has noted the great 

resemblance of A1·cticoceras to the slightly older Arctocephalites and to the slightly younger Pseudocadoceras 

and Longaeviceras. He also notes (1932, p. 53) the 

resemblance of the young Arcticoceras to the early 

whorls of Oadoceras s1,1ch as 0. stenolobum (Keyserling). Thus, Arcticoceras occupies a position biologically and strat.igra phically between the Macrocephalitidae and the Cardioceratidae. Its inner and intermediate whorls rese1nble the Cardioceratids by their 

lateral compression, narrowed venter, and· forwardly 

inclined ribbing.· Its adult whorls resemble the Macrocephalitids by their high degree of involution and 

absence of an umbilical edge. 

0 adoceras was defined by Fischer ( 1882, p. 394) as 

a subgenus of Stephanoceras in the following words 

(translation) : 

Shell very swollen; umbilicus narrow, carinate; last whorl 

entirely smooth. Preceding whorls with the ribs forming an 

angle directed forward on the ventral region. Ex. 0. modiolare 

Lui d. 

Spath (1932, p. 58) notes that the name modiolare 

is pre-Linnean and selects Ammonites sublaevis J. 

Sowerby (1814, vol. 1, p. 117, pl. 54, large figure) as 

the genotype because he considers it identical with the 

form described by Lhuyd. 

Since 0 adoceras was first defined, the name has been 

applied by most geologists to a genus and usually in a 

broader sense than that specified by Fischer in order 

to include forms that are closely allied (Nikitin, 1884·, 

pp. 142, 143; 1885, pp:51, 52; Douville, 1912, pp. 14-19; 

Spath, 1932, pp. 58-64). Thus a definition of Oadoceras, 

sensu latu, as currently employed, may be phrased as 

follows: 

Shell compressed to swollen, generally stout to globose in 

the adult; umbilicus narrow to fairly wide, wall steep to nearly 

vertical, edge sharp to rounded; ripbing weak to strong, gently 

to strongly inclined forward on flanks, faintly to strongly arched 

· forward on venter, never sickle-shaped or angulate; umbilical 

tubercles present or absent in intermediate and adult whorls, 

when present forming a .characteristic festoon on umbili.cal 

edge; body whorl generally smooth but ribbed in some species 

.and there may be rejuvenescence of ribbing near the aperture 

after a smooth stage; aperture slightly sinuous, inclined forward, without rostrum or lateral lappets, preceded by a weak 

constriction; suture line fairly complex, first lateral lobe t;ifid 

and generally longer than external lobe, second lateral lobe 

generally much shorter than external lobe, external saddle 

asymmetrically divided. 

The features that especially cha.racterize Oadoceras 

are the smooth, or nearly smooth adult body chamber, 

the steep, smooth umbilical wall of the adult body 

whorl, the rounded, depressed adult venter and the.regular arching of the ribs on the venter. These features 

exclude Pseudocadoceras, which has a strongly ribbed 

body chamber, a rounded umbilical wall, and a sharpened adult venter, although Pseudocadoceras greatly 

recembles the intermediate-sized whorls of some species 

of Oadoceras, such as 0. stenolobwm (Keyserling) 

(1846, p. 329, pl. 20, fig. 7, pl. 22, figs. 13, 14; Sokolov, 

1912, pl. 1, fig. 4) or 0. nikitini· Sokolov (1912, p. 53, 

pl. 1, figs. 3 a-d), and might conceivably be the ancestor 

of some species included in Oadoceras. These features 

also exclude Longaeviceras because the latter has keeled 

inner whorls, sicklelike ribs that are angulate on the 

venter,· and a low umbilical wall at all growth stages. 

Longaeviceras is generally considered a subgenus of 

Quenstedtoceras (Spath, 1932, pp. 47; 48), but its features are transitional between those of Qu:enstedtoceras 

and Pseudocadoceras and its range from the calloviense 

to the at'hleta ·zone fits that of a transitional form. 

Q1.tenstedtoceras itself is distinguished from Oadoceras · 

essentially by a sharpened venter and angulate ventral 

ribbing but may develop a cadoceratid adult body whorl · 

as in the subgenus Eboraciceras. 

The genus Oadoceras as defined herein is d~visible 

into seven groups, of which two are characterized sufficiently biologically and stratigraphically to ·merit 

recognition as subgenera. Probably some of the other 

five groups will be considered subgenera when they are 

better known. These groups are distinguished primarily on the characteristics of the umbilicus and on 

the changes in the shape of the whorl section during 

growth. Useful secondary distinctions include the 

presence or absence of tubercles, the shape of the tubercles, and the amount of forward inclination of the 

ribbing. The last seems to vary directly with the degre~ of compression of the shells and is strongest on 

the species with the most narrow venters. The characteristics, relationships, and occurrences of these seven 

groups will now be discussed. 
44 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

GROUP 1 

Group 1 includes forms with evolute whorls that are 

compressed in the young and stout in the adult. The 

· umbilicus is fairly wide for the genus (umbilical ratio 

about 23 to 33). The umbilical edge is rounded on the 

inner whorls but generally abrupt on the adult body 

whorl. The ribbing is weak to strong, is inclined £orward considerably on the. flanks, arched forward on the 

venter, and may disappear on the body chamber. Bifurcation of the ribs occurs at one-£ourth to one-hal:f 

of the height of the flanks, but single ribs are common 

in some species. Tubercles are weak or absent. 

This group constitutes an easily recognized subgenus 

for which the name Paracadoceras Crickmay .(1930, 

p. 55, pl. 16, figs. 1, 2) is available. The type, P. harveyi Crickmay, does not have a well-defined umbilical 

edge, but it is probably an immature specimen. Its primary ribs bifurcate near the middle of the flanks on the 

body whorl (see pl. 43, fig. 12) instead of being s_ingle 

as suggested by the original illustrations. Paracadoceras is not accorded more than subgeneric rank because most species develop a typical Oadoceras-like wall 

on the body chamber and because there is a close resemblance with the species of Oadoceras in group 2. 

· The following species belong to P aracadoceras: 

a. elatmae (Nikitin) 188lb, p. 116, pl. 11 (IV), figs 20, 

21, 23; 1885, p. 54, pl. 10 (VIII), fig. 47. 

a. br,eve Blake 1905, p. 48, pl. 5, fig. 1. 

0. harveyi (Crickmay) 1930, p. 55, pl. 16, figs. 1. 2. 

a. ammon (Spath) 1932, p. 78, pl. 21, figs. 5a, b. 

a. chisikense Imlay. 

a. tonniense Imlay. 

0. rnAtltitorme Imlay. 

0. mo{fiti Imlay. 

The following species may belong to· Paracadoceras: 

0. frearsi (D'Orbigny) 1845, p. 444, pl. 37, figs. 1, 2; Nikitin, 1881b, pl. 11, figs .. 22a, b ; Nikitin, 1885, pl. 12, 

fig. 52. 

0. schumarowi Nikitin, 1884, p. 68, pl. 3, fig. 16. 

0. psettdoisl~mae Spath, 1932, p. 77, pl. 8, figs. 6a, b. 

Among these species, 0. harveyi, 0. schumarowi and 

0. amurrwn do not have a well-defined umbilical edge. 

However, the first two species are probably based on 

imature specimens that had not developed an umbilical 

edge and the last is a crushed specimen. 0. sclvwrnarowi 

bears considerable resemblance to the inner whorls of 

0. moffiti Imlay. 0. harveyi resembles the immature 

forms of 0. wultiforrrie Imlay. 0. pseudoishmae has 

a narrower um·bilicus than the other species of Parac~­

doceras but a:grees well in whorl shape and character of 

ribbing. Spath (1932, p. 59) considered it transitional 

between Arcticoceras and Oadoceras. 0. frearsi has a 

tdgonal venter in the adult. It is interesting that the 

inner whorls of Paracadoceras at diameters less than 

36 mm greatly resemble the adults of Pseudocadoceras . . ' 

whiCh in Alaska occurs a little higher stratigraphically 

than Paracadoceras. 

\ 

P aracadoceras is characteristic of the lower part of 

the. Callovian in the boreal region. . In Alaska five 

species have been found in the lower two-fifths of the 

Chinitna formation. In British Columbia P. harveyi 

is associated with forms of Oadoceras which are identified ( Crickmay, 1930, pp. 56, 57) with species in the 

lower third of the Chinitna formation. In Russia 

0. elatmae (Nikitin) and 0. freaTsi (D'Orbigny) oc-~ur 

in beds that Arkell ( 1946, p. 25) correlates with the 

zones of M acrocephaiites mac_rocephalus and Proplanulites koenigi in northwest Europe. o~ schumarowi 

Nikitin (1884, pp. 68, 143, pl. 3, fig. 16), however, occurs in·the Russian zone of Oa(loceras rmilaschevici and 

must represent some part of the middle Callovian. 

0. a111J/11J,on Spath from Greenland occurs with other ammonites that indicate a correlation with the zone of 

S'igaloceras calloviense. · In England 0. breve Blake 

occurs in the upper part of the Cornbrash. Judging 

from these occurrences Paracadoceras first appears in 

the zone of M acrocep:halites macrocephalus, ranges 

through at least the zone of Sigaloceras calloviense, and 

is not common above the zone of Proplanulites koenigi. 

GROUP 2 

Group 2 includes forms with evolute, ovate to compressed i1mer whorls and broadly rounded, depressed 

outer whorls. The umbilicus is fairly wide for the 

geims (umbilical ratio about 27 to 37) and is fairly deep 

in the adult. The umbilical edge is rounded on the 

inner whorls but sharp on the outer whorls. The ribbing ranges from weak to moderately strong, is mod-. 

erately to strongly inclined forward on the flanks, and 

may disappear on the body whorl. · Bifurcation of the 

ribs occurs at one-third to one-half of the height of the 

flanks. Single ribs are fairly common. Commashaped umbilical swellings are moderate to stronO' and • b 

persist to a later growth stage than the ribbing. 

The inner whorls of the species of this group greatly 

resemble the intermediate and adult whorls of Paracadocwas. The outer whorls in contrast are broadly 

rounded and depressed, have a sharp umbilical edge, 

persistent comma-shaped umbilical swelling, and the 

ribs, where present, do not incline forward as strongly 

on the flanks or on the venter. 

The following species represent group 2: 

a. tschernyschewi Sokolov, 1912, pp. 19, 51, pl. 1, fig. 2, 

pl. 2, fig. 1 

0. quenstedti Spath, 1932, p. 59; Quenstedt, 1887, p. 672, 

pl. 79, fig. 7 . 

0. simulans Spath, 1f!32, p. 61; Nikitin, 1885, p. 52, pl. 11 

a. victor Spath 1932, p. 67, pl. 16, figs. 6 a-c . 

a. caly:r: Spath 1932, p. 69, pl. 20, figs. 1 a, b 

a. brooksi Crickinay 1930, p. 57, pl. 16, figs. 3-5 

0. catosto·ma Pompeckj 1900, p. 263, pl. 5, figs. 1 a-e, 2 a. b. 

0. comma Imlay 

a. glabrum Imlay 
ALASKA PENINSULA AND COOK INLET REGIONS 45 

Among these species 0. calyx has the coarsest ribbing 

and 0. glabrwm the finest. 0. brooksi is based on a 

fragmentary specimen and may be identical specifically 

with one of the Alaskan forms. 

Group 2 in Alaska is abundant in the lower twothirds of the Chinitna forma~ion except for the basal 

few hundred feet. It occurs also in the upper part of 

the lower member of the She.Iikof formation. The 

Greenland species occur in beds that probably represent 

the zone of Sigalocer{))S calloviense. The Russian 

species, 0. tschernyschewi Sokolov and 0. simulans 

Spath occur in the Russian zone of 0 adoceras elatmae. 

The Arcticoceras beds in Montana and Wyoming have 

not furnished any species of this group. Judging from 

these occurrences, the species of Oadoceras in Group 2· 

occur in the lower part of the Callovian and do not range 

above the zone of 0 os1noceras ja..'wn. 

GROUP 3 

Group 3 includes forms similar to group 2 in their 

evolute inner whorls and broadly round~d outer whorls, 

but differ essentially by having an evenly rounded 

umbilical edge and by lacking tubercles. The following species ar~ included: 

!

Madsen, 1904, p. i93, pl. 9, figs. 1-3, ·pl. 10, 

C. crassum fig. 1, 

Spath, 1932, p. 64, pl. 16, figs. 3a, b. 

C. variabile Spath, 1932, p. 75, pls. 18, fig. la, b, pl. 19, 

figs. la-c, 2a, b. 

a. variabile var. occlusum Spath, 1932, p. 76, pl. 19, fig. 2. 

These forms are all from Greenland from beds that 

are correlated with the S~galoceras calloviense zone. 

GROUP 4 

Group 4 includes forms that are characterized by a 

fairly narrow, step-like umbilicus (umbilical ratio 

about 20 to 26). The venter is evenly arched. The umbilical edge is abrupt to sharp. The ribbing is fine to 

strong and nearly disappears on the body chamber. 

Weak comma-shaped swellings are present on the umbilical edge. The body chamber is stout but not globose. 

The group is represented by the following species : 

C. wosnessenskii ( Grewingk) , 1850, p. 344, pl. 4, figs. 1 

a-d; Pompeckj, 1900, p. 251, pl. 5, fig. 5 a-c. 

a. doroschini (Eichwald), 1871, p. 138, pl. 7, fig. 6, pl. 8, 

figs. 1, 2. 

C. tenuicostatum Imlay 

a. kialagvikense Imlay 

These species have a considerable vertical range in. 

southwestern Alaska in the middle two-thirds of the 

Chinitna formation and in the lower and middle members of the Shelikof formation. They are absent from 

the basal few hundred feet of both formations. 

GROUP 5 

Group 5 includes forms that are characterized by a 

narrow umbilicus (umbilical ratio about 18 to 26) hav218128-53-2 

ing a tubula.r or corkscrew-like shape. The whorls are 

moderately to broadly rounded. The umbilical edge is 

generally evenly rounded and is never sharp. The ribbing ranges from fine to strong and is inclined moder-· 

ately forward. Weak conical tubercles may be present 

in the inner whorls. The body chamber is globose and . 

smooth. 

"The following species represent group 5. 

C. jranciscus Spath, 1932, p. 74, pl. 20, figs. 2 a-c. 

C. treboldi Spath, 1932, p. 65, pl. 18, figs. 2a, b. 

C. shoshonense Imlay, 1948, p. 22, pl. 7, figs. 13, 16, 17. 

C. Sttrense Nikitin, 1885, · p. 57, pl. 12, figs. 53-55, text fig. 

4 on p. 58. 

?C. subpatrutt'tn Nikitin, 1885, p. 58, pl. 13, fig. 58, text fig. 

5 on p. 59. 

0. franciscus Spath and 0. freboldi Spath appear to 

be less depressed than the other species in this group. 

The group is represented in the lower Callovian of 

Montana by several species that show variation in shape 

from a globose form, such as 0. shoshonense Imlay, to 

a moderately compressed form similar to 0. franciscus. 

The inner whorls of 0. surense Nikitin resemble the intermediate-sized whorls of Paracadoceras, but the deep, 

corkscrew-shaped umbilicu~ of the adult is quite 

different. 

0. subpatruum Nikitin is provisionally placed in this 

group because of its narrow, corkscrew-like umbilicus 

and because the ribbing of its inner whorls is 'described 

as similar to that of 0. surense, but its venter is narrowed more than the other species in the group. The 

adult whorl bears considerable resemblance to· Arcticoceras henryi (Meek and Hayden), but has a wider 

umbilicus. 

Species of group 5 occur in the Western Interior of 

the United States at three levels associated respectively 

with Arcticoceras, Gowericeras, and Kepplerites tychonis.Ravn. This association indicates a lower Ca.Ilovian age corresponding to the European zones of Macrocephalites macrocephalus, Proplanulites koenigi, and 

Sigaloceras calloviense. The described species from 

Greenland and Russia are from beds that probably represent the Sigaloceras calloviense zone. 

.GROUP 6 

Group 6 includes forms that are characterized by a 

moderately narrow, deep, crater-like umbilicus ( umbilical ratio about 24 to 30). The venter ·is broadly 

rounded. The umbilical edge is sharp, or abruptly 

rounded. The -ribbing ranges in strength from moderate to strong and is gently inclined forward. Conical 

tubercles may be present. The body chamber ·is globose 

and smooth or nearly smooth. This group di_ffers from 

group 5 by having a sharp or more abrupt umbilical 

edge in the outer two adult whorls, a somewhat wider 

umbilicus, and generally a more depressed whorl 

section. 
46 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

The group is represented by the following species: 

0. sublaeve ·(J. Sowerby), 1814, Mineral conchology, vol. 

1, p. 117, pl. 54 (large figure) 

0. sublaeve var. commune Spath, 1932, p. 60 . 

0. sublaeve var. rugosum Spath, 1932, p. 60, Buckman, 1922, 

pl. 275 

0. orbis Spath, 1932, p. 61 ; . D'Orbigny, Pal. Fran~aise; 

Terr. Jur. vol. ;1., 1847, p. 468, pl. 170 · 

0. toiype Buckman, 1922, pl. '406 

?0 aurum (Buckman), 1922, Yorkshire Ammonites, vol. 

4, pl. 283 ; 1929, pl. 3 

0. bathyomphalum Imlay . 

0. tchefkini (D'Orbigny), 1845, p. 439, pl. 35, figs. 10-15·; 

Nikitin, 1884, pl. 3, fig. 15 

0. svsolae Khudyaev, 1927, p. 506, pl. 27, figs. 1, 2. 

The species from England represent the Zones . of 

Proplamulites koenigi and 'Sigaloceras calloviense. 

The Greenland species· probably represents ·the calloviense zone. 0. tchefkini occurs in the Russian zone of 

Oadoceras milaschev·ici, which Arkell (1946, p. 25) correlates with the calloviense to coronatwm zones of 

northwest Europe. It is interesting that only one 

species of group 6 has been found in Alaska and none 

in the western interior of the United States, whereas 

the group is fairly common in northwest Europe and 

includes the genotype species, 0. sublaeve. 

GROUP 7 

Group 7 includes moderately large, compressed forms 

with narrow umbilicus (umbilical ratio about 14 to 23) 

and· narrowly to evenly rounded venter. The umbilical 

edge is rounded on the inner whorls and abrupt on the 

body whorl. The ribbing varies from fine to coarse, 

is gently inclined on the flanks, arches forward slightly 

on the venter, and may nearly disappear on the body 

chamber. Rib-branching generally occurs between the 

lower third and the middle of the flanks. Tubercles 

are weak or absent. 

As group 7 has certain distinctive characters that 

distinguish· it clearly from the somewhat similar 

Pseudocadoceras Buckman ( 1918, p. XIV; 1919, pl.· 

121c) and Longaeviceras Buckman (1918, p. XIV; 1919, 

pl. 121a), it is herein defined as a new subgenus, Stenocadoceras, and 0. multicostatwm Imlay (see p. 90) is 

designated the type. The inner whorls of Stenocadoceras greatly resemble the adult whorls of Pseudocadoceras, but the umbilicus is somewhat narrower and does 

not widen during growth and the venter is not sharpened. The adult whorls of Stenocadoceras are distinguished from those of Pseudocadoceras by a rounded 

.venter, an abrupt umbilical edge, and by weakening of 

the ribbing on the body chamber.· The adult Stenocadoceras is similar in general appearance and size to 

Longaeviceras (compare L. funiferum (Phillips) in 

D'Orbigny, 1847, pl. 156, fig. 3; Douville, 1912, pl. 3 · 

(IX), fig. 6, text-figs. 16, 17; Nikitin, 1885, pl. (X) 

XII, figs. 56,57; also compare L. placenta (Simpson) in 

Buckman, 1920, pl. 148, and Sokolov, 1912, pl. 2, fig. 2), 

but the latte.r has much more strongly inclined secondary ribs, does not develop an abrupt umbilical edge, 

and its inner whorls are keeled. . 

The following species are included in Stenocadoce'l'as: 

0. steiwlobum (Keyserling) 1846, p. 329, pl. 20, fig. 7, pl. 

22, figs. 13, 14; Sokolov, 1912, p. 52, pl. 1, fig. 4. 

0. stenolobum var. densicostatum Spath 1932, p. 62; 

Nikitin 1881b, p. 121, pl. 12, figs. 28-30. 

0. milaschevici Nikitin 1881a, p. 66, pl. 3, fig. 25 ; 1881b, 

p. 121, pl. 12, · figs. 26; 27. 

0. compressum Nikitin, 1881a, p. 67, pl. 3, figs. 26, 27. 

0. dubium Spath 1932, p. 73, pi: 22, figs. 2a, b. 

0. multicostatum Imlay. 

0. striatum Imlay. 

0. iniskinense Imlay. 

d. bowserense Imlay. 

0. pomeroyense Imlay. 

0. stenoloboide Pompeckj 1900, p. 255, pl. 7, figs. 2, 3. 

0. nikitini Sokolov, 1912, p. 53, pl. 1, figs. 3a-d. 

The body whorl of some of these specl.es is comparable in stoutness with that of group 4 although the umbilicus is narrower and the shape of the inner whorls 

is quite different. Such species include 0. stenolobum 

var. densicostatwm Spath, 0. milaschevici Nikitin, 0. 

nikitini Sokolov, 0. stenoloboide Pompeckj, and 0. 

pomeroyense Imlay. 

The Russian species listed under group 7 are from 

the Russian zone of Oadoceras milaschevici which 

Arkell (1946, p. 25) correlates with the northwest European zones of. Sigaloceras calloviense,. Oo~oceras 

jason and EryWJWceras coronatum. 0. dubiwm from 

Greenland probably represents the Sigaloceras calloviense zone. The Alaskan species range through the upper five-sixths of the Chinitna formation, but are common only in the upper two-fifths. 

Pseudocadoceras was named by Buckman ( 1918, p. 

XIV; 1919, pl. 121c; 1929, p. 22), who designated 

P. boreale Buckman (1919, pl. 121B) as the type. The 

genus includes small, compressed forms characterized 

by a narrow to moderately narrow, shallow, umbilicus 

and a sharpened to narrowly rounded venter. The umbilical ratio ranges from about 20 to 30 and the umbilicus generally enlarges during growth~ The ribbing 

varies from fine to coarse, is gently to moderately inclined forward on the flanks, is arched gently to · 

strongly on the venter, and does not weaken on the body 

chamber. Bifurcation of the ribs occurs a little below 

the middle of the flanks. Single rips and intercalated 

ribs are common. Tubercles are not present. The suture line is somewhat simpler than in Oadoceras but 

has the same general pattern . 

The species belonging to Pseudocadoceras were placed 

in Oadoceras by Pompeckj ( 1899, p. 86; 1900, pp. 258-

267) , but since its definition by Buckman the genus has 

been considered distinct. It differs from 0 adoceras essentially by having a strongly ribbed body chamber 

in the adult and by its umbilical wall remaining 

rounded an~ ribbed instead of becoming steep and 
I 

I 

Group or subgenus Whorl shape 

1. Paracadoceras. C. (P.) Compressed, 

harveyi Crickmay. then evenly 

arched. 

2. Group of C. comma Ovate, then 

Imlay. depressed. 

3. Group of C. crassum Depressed 

(Madsen). 

4. Group of C. doroschini 

(Eichwald). 

Evenly arched 

5. Group of C. shosho- Moderately to nense Imlay. broadly· 

· arched. 

6. Group of C. sublaeve Broadly arched 

(J. Sowerby). 

7. Stenocadoceras. C. (S.) Narrowly to 

multicostatum evenly 

Imlay. arched. 

• 

Table !.-Morphological comparisons of groups of Cadoceras 

Umbilicus (Adult) Rib inclination 

Shape Width Edge Flanks I Venter 

Shallow, open Fairly wide Generally Strong Moderately 

Ratio=22:33. abrupt. arched. 

Fairly deep, Fairly wide Sharp Moderate to Gently arched 

open. Ratio=27:37. strong. 

Fairly deep and Fairly wide Evenly rounded Moderate Gently arched 

open. Ratio=24:30. 

Step-like Fairly narrow Abrupt to sharp Gentle Slightly arched 

Ratio=20:26. 

Tubular or ·Narrow Evenly rounded Moderate to Slightly arched 

corkscrew- Ratio= 18:26. to abrupt. gentle. 

like. 

Deep, crater- Moderately Sharp Gentle Slightly arched 

like. wide. 

Ratio=24:30. 

Shallow to Narrow Abrupt Gentle to Slightly arched 

moderately Ratio= 14:23. moderate. 

shallow. 

Tubercles 

Weak or absent 

Comma-shaped, 

persistent. 

None 

Weak, comma- shaped. 

Weak, conical, or absent. 

Conical or absent. 

Absent, or weak 

swellings. 

----

Body chamber 

Fairly stout. 

Stout. 

Stout. 

Stout. 

Globose. 

Globose. 

Compressed 

to moderately stout. 

-

> t'l 

> Ul 

~ 

> 

"'d 

t?:l 

2: 

z 

Ul 

0 

t'l 

> 

> z 

~ 

n 

0 

0 

~· 

z 

t"4 

l".l 

8 

!:::0 

t?:l 

·a 

H 

0 

z 

Ul 

~ 

.....:( 
48 CALLOVIAN (JUP,ASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

smooth. It bears some resemblance 'to the innermost . 

whorls of Paracadoceras (see plate 42, figures 1, 2, 5, 7) 

and to the intermediate-sized whorls of Stenocadoceras (see pl. 20, figs~ 1-12), both of which develop a 

Oadoceras-like body chamber. It greatly resembles 

Longaeviceras, but its ribbing is less arched ventrally 

and does not weaken on the body chamber. Maire 

. ( 1938, p. 12) considers that Pseudocadoceras is intermediate between 0 adoceras and the species of Quenstedtoceras in which the ribs form a V on the venter, 

such as in the subgenus Bourkelamberticeras. It is 

.conceivable that Pseudocadoceras arose from Paracadoceras, which immediately preceded it in Alaska, but 

morphologically an origin from some strongly-ribbed 

:species of Arcticoceras seems much more probable.- It 

probably did not develop into Longaeviceras, as the latter occurs as low as the Sigaloceras calloviense zone. 

Rather, the characteristics and stratigraphic ranges of 

Pseudocadoceras, Stenocadoceras, and Longaeviceras 

indicate that they ·arose indepe;ndently of each other 

from lower Callovian forms similar to Arcticoceras. 

'The following species belong to Pseudocadocerqs: 

!P. boreale Buckman, 1919, pl. 121B ; Maire, 1938, p. 12, 

pl. 1, figs. 1, 1a. . 

P. concinnum Buckman, 1927, pl. 735. 

P. Zaminatum Buckman, 1927, p. 727. 

P. nanseni ( Pompeckj) , 1899, p. 86, pl. 2, figs. 1-3, 5, 6, 

text figs. 16, 17 ; Spath, 1932, pl. 9, fig. 2, pl. 11, fig. 4. 

P. orbignyi Maire, 1932, p. 197; 1938, pl. 1,. fig. 3; D'Orbigny, 1848, pl. 179, figs. 7, 8. 

P. grewingki (Porilpeckj), 1900, p. 258, pl. 6, figs. la-d 

only. 

P. petelini ( Pompeckj), 1900, p. 267, pl. 6, figs. 4-6. 

P. crassicostatum Imlay. 

P. chinitnense Imlay. 

P. schmidti (Pompeckj), 1900, · p. 265, pl. 5, figs. 3a-d, 

4a, b. 

Pseudocadoceras .in northwest Europe ranges from 

;the Sigaloceras calloviense zone through the Erymnoceras coronatwm zone but is most common in the calloviense and jason zones. In southwest Alaska Pseudocadoceras ranges through the upper two-thirds of the 

Chinitna formation and from the upper beds of the 

lower member of the Shelikof formation through the 

middle member. Pseudocadoceras grewingki shows this 

entire range. P. petelini has been found only in the middle member of the Shelikof formation. P. crassicostatium has been found in the upper third of the Chinitna formation and in the middle member of the Shelikof. P. chinitnense occurs throughout the upper third 

of the Chinitna formation. 

The Cosmoceratidae are represented mostly by K epplerites, of which genus eight species have been found 

in southwestern Alaska in the lower two-thirds of the 

Chinitna formation and near the base of the Shelikof 

formation. Gowericeras includes three species, each 

represented by single specimens. Two species were 

found near the base of the Chinitna formation and one 

in the lower part of the middle third. One specimen 

of Oosmoceras, comparable to 0. spinoswm ( J. de C. 

Sowerby), was found as float near the top of the middle 

third of the Chinitna formation. Several fragments 

belonging to Guliel1niceras were obtained near the base 

of the Chinitna formation. All the species of Kepplerites in Alaska are referred to the subgenus Sey1nourites, 

which differs from the typical K epplerites in central 

Europe accor~ing to Spath ( 1932, p. 83) by its 

. . . large size, the tendency of the peristome to become flared, 

with a preceding shallow constri-ction, the loss of runcination 

· at an earlier stage than in the Wurtemberg examples, and 

especially the finer ribbing in the young. . . . 

Spath suggests that these differences reflect diffel~­

ences in habitat, but notes that the typicall{epplerites 

in Europe occurs in the M acrocephalites macrocephalus 

zone, whereas the known species of Seymourites appear 

to be from slightly younger beds. In this regard it may 

be significant that K epplerites has not yet been found 

associated with Arcticoceras in North America. 

The ~1orphoceratidae is represe1i.ted in the Callovian 

of Alaska by two specimens of' Reineckeia. One of 

these, found near the base of the Shelikof formation 

at Wide Bay, is assigned to the subgenus Kellawaysites 

rather than to Reineckeites because of the presence of 

long, closely spaced primary ribs, weak tuberculation, 

and restriction of tubercles to the inner whorls. The 

other specimen, found near· the base of the Chinitna 

formation on the Iniskin Peninsula (Mes. loc. 21320), 

bears prominent tubercles at a size that suggests assignment to typical Reineckeia. One other specimen of 

Reineckeia is known from the Iniskin Peninsula, from 

the mi&dle part of the Bowser member of the Tuxedni 

formation (Mes. loc. 20745), which on the basis of the 

presence of Oranocephalites is considered to be of early 

or middle Bathonian age. The occurrence of Reineckeia 

in southwestern Alaska is especially interesting, as the 

genus is characteristic of the Mediterranean province, 

is uncommon in northwest Europe, and has not been 

recorded as far north as ~orkshire, England, or northern Germany (Spath, 1932, pp. 148, 149; Arkell, 1946, 

p. 16). 

The Perisphinctidae are represented in the basal beds 

of the Chinitna formation of southwestern Alaska by 

a few specimens of Procerites and a single specimen of 

Grossouvria. Fragments probably belonging to Procerites occur also in the undeilying beds characterized 

by Oranocephalites. The occurrence of Procerites and 

Grossouvria in the Chinitna formation is not surprising, 

as both ·genera occur in lower Callovian beds in ~!fontana.· 

STRATIGRAPHIC SUMMARY 

ALASKAN PENINSULA REGION 

SHELIKOF FORMATION 

Three lithologic members have been recognized within the Shelikof formation in the Wide Bay and Puale 
ALASKA PENINSULA AND COOK INLET REGIONS 49 

Bay (formerly Cold Bay) areas. · These include a 

lower &iltstone member ranging from 800 to 1,800 ft 

thick; a middle sandstone member ranging from 1,000 

(or less) to 3,500 ft thick; and an upper siltstone mem· 

her ranging from 900 to 1,500 ft thick (Capps, 1922, 

pp. 97-101; Smith and Baker, 1925, pp. 169, 176-178; 

Smith, 1925, pp. 196-197; Smith, 1926', pp. 71-85; Kel· 

lum, Daviess, and Swinney, 1945, p. 8, fig. 2) .

1 

The lower member in the Wide Bay area consists 

mainly of gray siltstone and sandy siltstone that is 

generally soft and brown weathering in the lower part 

of the member but becomes harder and darker gray 

upward on both fresh and weathered surfaces. It, also, 

contains many sandy interbeds from a few inches to as 

much as 200ft thick. Thin beds of white to yellowish·. 

brown, .fine·grained material, probably volcanic ash, 

are fairly common in the lower part of the member and 

serve to distinguish the basal siltstones of the Shelikof 

formation from similar soft siltstones in the underlying 

IGalagvik formation. Limestone concretions that 

weather brown and gray are abundant at many levels. 

Faunally the member is characterized throughout by 

the ammonite OadocerCM, and its middle and upper parts 

contain many specimens of PseudocadocerCM and Lilloettia. . 

The lower member at Puale Bay is represented by 

about 800 ft of brown-weathering siltstone that in· 

eludes many concretions. The brown appearance of 

the outcrops is due to the presence of ashy beds re· 

sembling those in the lowest beds of the Shelikof formation in the Wide Bay area. The siltstone is underlain 

by about 100 ft of coarse conglomerate that rests on 

Lower Jurassic siltstone. One fossil collection (Mesozoic loc. 3106), obtained .near the top of the member, 

contains OaxiocerM and-PseudocadocerCM. 

The middle member of the Shelikof formation consists dominantly of massive gray sandstone but contains 

interbeds of siltstone and lenses of conglomerate. The 

conglomerate consists of granitic and dioritic rocks, is 

generally fine, but in places contains boulders as much 

as 2 ft in diameter. . Locally, the sandstones in the 

upper part appear to. pass laterally into siltstones of 

the upper member. From the middle member have 

been obtained a considerable number of pelecypods, and 

some gastropods, belemnites, ammonites and brachiopods. PseudocadocerCM is more abundant than 

OadocerCM. 

The upper member of the Shelikof formation consists 

mostly· of hard, dark gray, gray ·weathering siltstone. 

Near Wide Bay the siltstone contains thin interbeds of 

sandstone and limestone. Near Puale Bay the siltstone contains lenses oryellowish-weathering limestone 

1 The following description of the Sbelilwf formation is condensed 

from an unpublished memorandum by D. J. Miller and R. W. Imlay 

based on field work in the Wide Bay and Puale Bay areas in 1948. 

It also takes into account unpublished information obtained by L. R. 

Kellum and Jacob Freedman in 1945. 

that greatly resemble limestone lenses in the·upper part 

of the Chinitna formation on the Iniskin Peninsula. 

The known fossils from the upper member of the Sheli· 

kof formation consist only of pelecypods, gastropods, 

and belemnites. PseudocadooerCM has been found near 

the top of the middle member at several localities and 

possibly occurs in the upper member at Mesozoic ·locaiity 10813, southwest of Wide Bay. 

COOK INLET REGION 

CHINITA FORMATION 

The Chinitna formation occurs in the area extending 

from Iniskin Bay to Tuxedni Bay (Moffit, 1927, pp. 

~3-31, 66; IGrschner and Minard, 1949). The name 

has likewise been used · in the Matanuska Valley 

(Chapin, 1918, pp. 33, 34; Paige and Knopf, 1907, 

pp. 20-24) for several thousand feet of beds that contain 0 adoceras and are reported to differ from the 

typical Chinitna formation of the Chinitna Bay area 

by containing some conglomerate and massive sandstone. Actually the Chinitna formation of the 

Matanuska Valley as mapped may include beds older 

than the typical Chinitna, because one lot (Mesozoic 

loc. 8573) from the Matanuska Valley contains Oranocephalites and Gryphaea im;pressimarginata McLearn,. 

of Middle Jurassic Age. 

The Chinitna formation west of Cook Inlet consists 

dominantly of medium- to dark-gray siltstone that 

weathers reddish brown, contains local lenses of gray 

sandstone at various levels, generally is marked basally 

by several hundred feet of shelly sandstone, and ranges,, 

in thickness from about 3,200 to 4,500 ft. It likewise 

c:.ontains many gray to brown calcareous concretions that 

may be as much as 2ft in diameter and are commonly 

fossiliferous. · The concretions occur singly and in 

layers parallel to the bedding. Most of the concretions 

are rounded, but the upper third of the formation co~­

tains many elongate concretions. 

Attempts have been made in the field during the past. 

few years to subdivide the Chinitna formation into 

mappable members on the basis of certain thick ~andstone units, but careful traversing of all the creeks has 

shown that the sandstone units are not persistent 

enough for mapping. One example of this is the series 

of strata defined by Kirschner and Minard ( 1949) as 

·the Tonnie member of the Tuxedni formation, primarily on the basis of the section at the head of Tonnie 

Creek in the central part of the Iniskin Peninsula. 

The section exposed at this place consists, from bottom 

to top, of ( 1) 440 ft of massive, rather soft gray siltstone containing interbeds of _fine-grained greenishgray sandstone and a few brown to gray concretions, 

(2) 580 ft of massive, dark-gray siltstone that contains 

many yellowish-brown-weathering concretions, and 

(3) 410 ft of fine-grained gray or greenish-gray sandstone that is interbedded with some sandy siltstone and 
50 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Chinitna formation 

Genus and species Lower 

·third 

Middle 

third 

Phylloceras (Phylloceras) bakeri Imlay, n. sp . .:.-----------

P. (Calliphylloceras) freibrocki Imlay, n. sp: -------- -----+--~-+----ij....; 

P. ( Partschiceras) subobtusiforme Pom peckj-----------.--

P. (Partschiceras) grantzi Imlay, n. sp:---- ---------.,.---- - P. (Macrophylloceras) grossicostatum Imlay, n. sp.-------: 

Oppelia (Oxycerites) chinitnana Imlay, n. sp.- ------------ 0. (Oxycerf,tes) sp.---------------------.-----.----------

Lilloettia buckmani (Crickmay)- --- -"'-- -----------------

L. milleri Imlay n. sp.----- -----------------------------

L. mertcrnyarwoodi Crickmay ---------------------------

L. lilloetensis Crickmay·------------ -------------------

L. stantoni Imlay n. sp.----- ---------------------------

Xenocephaljtes hebetU.s Imlay, n; sp.----.,---------------·- -

X. vicarius Imlay, n: sp.------ ---------------------- ---J,....---+-

X. hartsocki Imlay, n. sp:-- --- ~--------- --- ------ ------

Kheraiceras magniforme Imlay, n. sp. -------------------1---~-

K. martini Imlay, n. sp.------ ---------------------------

K. abruptum Imlay, n. sp.--------------------------.----- -- K. varicostatum Imlay, n. sp.--·---- ------ --·---- --------- - . K. intermedium Imlay, n. sp.---------- -----------------

K.? parviforme Imlay, n. sp~---------------------------1----

Cadoceras catostoma Pompeckj -----~-------------------1----+---~ 

C. comma Imlay, n. sp·. ----------:----------------------

C. glabrum Imlay, n. sp.-~-----------------------------

C. bathomphalum Imlay, n. sp.--------------------------

C. tenuicostatum Imlay, n. sp.--------------------------

C. doroschini (Eichwald)--,.------------------- ------ ----

C. wosnessenskii (Grewingk)------- ----------------------

- - C. kialagvikense Imlay, n. sp.---------------------------

C. (Paracadoceras) motfiti Imlay, n. sp.-----------------

C. (Paracadoceras) multiforme Imlay, n. sp:·------------- ~ 

C. (Paracadoceras) tonniense Imlay, n. sp.---- ------ ------1---_..-

C, (Paracadoceras) aft. C. tonniense Imlay--------------- f.--

C. (Paracadoceras) chisikense Imlay n. sp.--~-- ------------

C. (Stenocadoceras) multicostatum Imlay n. sp.- ----------

C. (Stenocadoceras) striatum ·Imlay, n. sp:------ ----------

C. (Stenocadoceras) iniskinense Imlay, n. sp.-- -----------

C. (Stenocadoceras) bowserense Imlay, n. sp:------------"' -

C. ($tenocadoceras) stenoloboide Pom peckj--------------

C. (Stenocadoceras) pomeroyense Imlay, n. sp:------------

Pseudocadoceras petelini (Pompeckj)· -------------------

P. grewingki ( Pompeckj)- -------·--- -------------- ~ ----

P. crassicostatum Imlay, n. sp. --------------------------

P. chinitnense Imlay, n. sp:-----------------------~-----

P. schmidti ( Pom peckj)--------------------------------

Kepplerites (Seymourites) alticostatus Imlay, n. sp.-- ----- ---

K. (Seymourites) multus (McLearn)-,..------------------- -

-

K; (Seymourites) tychonis Ravn------- ----------------- -

K. (Seymoutites) ingr.ahami (McLearn)-----------~----- ---+----+ 

K. (Seymourites) mcevoyi (McLearn)-- ------------------ -

K. (Seymourites) gitt".nsi (McLearn)-.,------------------- ~ 

K. (Seymourites) abruptus (McLearn)------- ------------ --

K. (Seymourites) plenus (McLearn)-- -------------------

Gowericercis snugharborense Imlay, n. sp:--- ------------ - G. spinosum Imlay, n. sp.-----·-------------------------

G. sp.---~--------------------~---------------------- ---

Cosmoceras cf. C. spinosum (J. de C. Sowerby)- -----------

Cosmoceras (Gulielmiceras) alaskanum Imlay, n. sp:---- -- -

Reineckeia (Kellawaysites) shelikofana Imlay, n. sp.------

Procerites spp.-------------------------------------·-- - P.? irregularis Imlay, n. sp . .:. __________________________ 1--

Grossouvria sp. -------------------------------------- ~-

- -

Upper 

third 

-

Shelikof formation 

Lower Middle Upper 

member member member 

-

- -

-

-

Table 2.-Stratigraphio distribution of Callovian ammonite species from Alaska Peninsula and Oook Inlet regions 
ALASKA PENINSULA AND ·COOK INLET REGIONS 51 

grades into the underlying massive siltstone. This 

sandstone unit at the top seems to disappear southward 

across the Iniskin Peninsula, and has not· been recognized as a persistent unit south of Fitz Creek. In addition, recent fossil collections have disclosed that the 

fauna of the Tonnie member, as mapped on Tonnie 

Peak by IGrschner and Minard, and the fauna of the. 

lower third of th'e Chinitna formation, wherever it ~as 

been examined; are identical. For this reason, and because of the lack of a persistent sandstone unit at the 

top, the Tonnie member has been placed in the Chinitna, 

forming roughly the lower third of the formation. 

Similarly, it was attempted to subdivide the upper 

two-thirds of the Chinitna formation on the basis of a 

massive sandstone about 30 ft thick that lies about 

1,000 ft below the top of the formation on the south 

shore of Chinitna Bay .. This sandstone seemed to be 

similar lithologically and stratigraphically to about 

80 ft of massive gray sandstone that lies 950 ft below 

the top of the Chinitna form!ttion. at Tuxedni Bay. 

Mapping of the intervening area as well as the area 

southwest of Chinitna Bay, however, suggests that the 

sandstones in question pass laterally into siltstone and 

that similar sandstone lenses appear at the same or at 

other levels. 

The boundaries of the Chinitna formation are rather 

sharp. The basal siltstones or shelly sandstones rest 

on massive ridge-forming sandstone or sandy siltstone 

at the top of the Bowser member of the Tuxedni formation. In places the highest beds of the Chinitna formation are overlain by conglomerate or sandstone at 

the base of the Naknek formation. In other places, 

as on Chinitna Bay, the formations appear to grade into 

each other through about 100 · ft of interbedded sandstone and siltstone. The boundary with the Tuxedni 

formation may mark a minor sedimentary break, as 

the highest beds of the Bowser member contain Oranocephalites and there is no record of Arctocephalites in 

the basal Chinitna, although that genus immediately 

succeeds Oranocephalites in East Greenland and is 

widespread in boreal Jurassic .deposits. The boundary 

of the Chinitna with the Naknek formation affords 

convincing physical evidence of a marked change in 

conditions of sedimentation and faunally marks a disconformity equivalent to the late Callovian, as the 

abundance of Pseudocadoceras and Oadoceras in the 

upper 100 ft of the Chinitna indicates an age not 

younger than the 'Erymmoceras coronatwm zone and the 

abundance of Quenstedtoceras (Scarburgiceras) near 

the base of the· Naknek indicates an age not older than 

that of the Quenstedtoceras mariae zone. 

Discussion of the stratigraphic distribution of the 

fossils would have been facilitated by division of the 

Chinitna formation into members. As this has not 

yet been done, in the present paper the Chinitna formation is arbitrarily divided into three parts which will 

be called thirds. Of course, the locality descriptions 

(pp. 65-71) furnish as exact stratigraphic data as are 

known. 

In the lower third of the Chinitna formation, formerly called the Tonnie member, the ammonites consist mostly of Oadoceras, Paracadoceras, Kepplerites, 

Lilloettia, Kheraiceras, and X enqtJephalites (see table 

3) . K heraiceras and X enocep halites occur throughout 

the lower third. · Lilloettia has not been found in the 

lowermost 500 to 600 ft of the Chinitna . formation. 

Procerites a:rid Grossouvria are uncommon and occur 

only in the basal beds. Kepplerites and Paracadoceras 

have been found within 70 ft of the base. Gulielmi-

. ceras has been found within several hundred feet of 

the base. On Chisik Island Gowericeras was obtained · 

within a zone 30 to 80ft above the base of the formation. 

In the middle third of the Chinitna formation the 

common ammonites are PhyUoceras, Oroycerites, Lilloettia, Oadoceras, Pseudocadoceras, and Kepplerites. 

One specimen of GoweTiceras was found in the lower 

part of the middle third, associated with· Pseudocadoceras, Oadoc&ras, Paracadoceras, Xenocephalites, and 

Kheraiceras. In the upper third of the Chinitna for~ 

mation the only ammonites found are Phylloceras, Lilloettia (rare), Oadoceras, and Pseudocadoceras. Most 

of the species of Oadoceras in the upper third are compressed and are included under a new subgenus, Sterwcadoceras. Pseudocadoceras is common only in the 

lower part of the upper third. 

AGE OF THE FAUNAS 

The lower third of the Chinitna formation contains 

the Callovian ammonites · K ep·plerites, 0 osmoceras 

( Gulielmiceras), Gowericeras, Oadoceras, 0. ( Pa:racadoceras) , Lilloettia and Grossouvria. Longer-ranging 

ammonites include Phylloceras, Oppelia ( Oroyoerites), 

Xenocephalites, f{heraiceras, and Procerites. T}:lis assemblage differs from that in the middle third of the 

Chinitna formation by the absence of Pseudooadooeras, 

except possibly at the very . top, by the presence of 

abundant Paracadoceras, Kheraiceras, and Xenooephalites, and by the presence of rare Gulielmiceras, Groasouvria and Procerites. An early Callovian age is 

clearly shown by the abundance of Paracadoceras, 

which includes such European forms as 0. elatmae 

(Nikitin) and 0. breve Blake. The presence of Gulielm'ioeras only· a few hundred feet above the base of the 

Chinitna formation indicates an age not older than the 

Sigaloceras calloviense zone of northwest Europe for 

most of the lower third. The presence of Gowerioeras 

near the base of the Chinitna formation on Chisik 

Island suggests that the basal 200 to 300 ft represent the · 

Proplanulites koenigi zone. This is supported by the 

presence of Procerites in these basal beds and by the 

. similarity of the species of Gowericeras and X eno-
52 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Chinitna formation. Shelikof formation 

Genera, subgenera, 

Middle Middle and groups · Lower Upper · Lower Upper 

third third third . member member member 

Phylloceras (Phylloceras) - P. (Calliphylloceras) 1---"--

P. (Partschiceras) 

P~ (Macrophylloceras) 

Oppelia (Oxycerites) -

Lilloettia 

Xenocr3phalites 

Kheratceras -

Cadoceras ( Paracadoceras) 

Group.of C. comma· Imlay -

Group of .C. sublaeve (J. Sowerby) -

Group of C. doroschini (Eichwald) 

Cadoceras (Stenocadoceras) 

Pseudocadoceras I 

Kepplerites -

Gowericeras . 

Cosmoceras ( Cosmoceras) ?-

c. ( Gulielmiceras) -

Reineckeia· (Kellawaysites) -

Procerites ~ 

Grossouvria 

TABLE 3.-Stratigraphic ranges of Callovian ammonites in Alaska 
ALASKA PENINSULA AND COOK INLET REGIONS 53 

cephalites to species in the Gowericeras subitum beds in 

Montana (Imlay, 1948, pp. 15, 16). It is supported too 

by the presence of Kepplerites tychonis Ravn on Chisik 

Island about 80 ft above the lowest exposure and apparently from a slightly higher bed than that which 

furnished Gowerice1·as. This species characterizes the 

K epplerites tychonis beds of East Greenland (Spath, 

1932, pp. 145, 146) and of Montana (Imlay, 1948, p. 16), 

which beds probably correspond to the lower part of the 

Sigaloceras calloviense zone. The correlation is supported by the presence of a fragment of Kepplerites, 

probably belonging to K. tychonis Ravn, associated with 

Gulielmiceras at U.S.G.S. }les. loc. 20755 on Iniskin 

Bay. The evidence seems rather strong, therefore, that 

the basal beds of the Chinitna formation cor:relate with 

the Prop'lanulites koenigi zone and the remainder of the 

lower third with at least the lower part of the Sigalocera8 calloviense zone of northwest Europe. It is interesting that evidence has not been found jn southwestern 

· Alaska ;for the presence of beds of the Macrocephalites 

macrocephalus zone. It is possibly represented locally 

at the base of the Chinitna formation by shelly sandstone that has furnished such ammonites as Phylloceras, 

Lytoceras, X eno.cephalites, Kheraiceras, and some small 

undeterminable macrocephalitids. However, not a single specimen of Arcticoceras has been found in these 

beds, in marked contrast to the abundance of Arcticoceras at the base of the Callovian in the boreal region, 

including northern Alaska and the western interior of 

North America. Failure to find Arcticoceras implies 

(1) an unconformity, (2) some kind of barrier between 

the Jurassic seas of southern and northern Alaska, (3) 

unfavorable ecological conditions, or ( 4) collecting 

failure. 

The middle third of the Chinitna formation has furnished many ammonites belonging to Oadoceras, Pseudocadoceras, K epplerites, Lilloettia, Owycerites and 

Phylloceras. Paracadoceras, Kheraiceras, Xenocep'halites, and Gowericeras occu.r rarely in the lower part 

of the middle third. This assemblage represents the 

middle of the Callovian, as shown long ago by Pompeckj 

.( 1909). It probably corresponds with the zone of 0 osmoceras jason, as indicated by str~tigraphic position 

and by the ranges of the ammonites. In Europe 

Pseudocadocer:a.(] ranges from the Sigaioceras calloviense to the Erymnoceras coronatum zone; 0 adoceras 

ranges from the M acrocephalites macrocephalus into 

the E. coronatum zone; Kepplerites ranges from the 

M. macrocephalus to the S. calloviense zone in England 

and apparently into the E. coronaium zone in northern 

Russia. Paracadoceras is most common in the zones of 

M. macrocephalus and Proplanulites koenigi but ranges 

at least as high as the S. calloviense zone. Gowericera.(j 

is characteristic of the P. koenigi ·zone but occurs rarely 

in the 8. calloviense zone. These ranges show that the 

middle third of the Chinitna cannot be older than the 

8. calloviense zone and part of it may be younger. The 

basal part of the middle third C(Orrelates with the 

S. calloviense zone because of the association of Gowericera8 and Paracadoceras with Pseudocadoceras. Its 

stratigraphic position above beds containing Kepplerites tychonis Ravn and Gulielmiceras shows that it 

represents only the upper part of the S. calloviense zone. 

An age slightly younger than that of the S. calloviewt3 

zone for most of the middle third is indicated by comparisons of the species of 0 adoceras and K epplerites 

with . those in the lower Callovian beds of Montana. 

The common species of 0 adoceras differ from those 

found in Montana by having an angular instead of a· 

rounded umbilical edge and persistent comma-shaped 

tubercles instead of nonpersistent conical tubercles and 

by tending to lose the ribbing on the lower part of the 

flanks before losing the ribbing on the venter. The 

species of K epplerites in the middle third of the Chinitna differ from those in Montana by nearly complete 

absence of ventral flattening in the young .forms. 

Possible additional evidence of age is furnished by 

one specimen of Oosmoceras, similar to 0. spinoswm 

( J. de C. Sower by) , obtained as float on the east shore 

of Iniskin Bay. This specimen shows little evidence 

of weathering or rounding, and probably was derived 

from nearby beds in the upper part of the middle third 

of the Chinitna formation. As forms similar to Oos1noceras spinosum range from the Erymnoceras coronatwm to the Quenstedtoceras mariae zone, it may be 

that the specimen was derived from the lower part 

of the Naknek formation, which corresponds to the Q. 

mariae zone. 

The siltstone of the upper third of the Chinitna formation contains abundant Pseudocadoceras and Oadoceras and some Phylloceras. Most of the forms of 

Oadoceras are compressed and resemble 0. milaschevici (Nikitin) and 0. stenolobum (Keyserling). This 

assemblage probably corresponds with the E'uropean 

zone of Erymnoceras coronatum because Pseudocadoceras is not known to range higher. The absence of 

such ammonites as Paracadoceras, K epplerites, Lilloettia, Kheraiceras_ and Xenocephalites, that occur in the 

. siltstone of the middle third of the Chinitna,. cannot 

be explained by ecological differences, and implies a 

fairly high position in the Callovian. The presence of 

Pseudocadoceras in the upper 100 ft of the siltstone 

of the Chinitna shows that no part of the formation 

is as young as the Oxfordian. · 

The Shelikof formation is considered to be the 

equivalent of the Chinitna formation as it contains the 

same species of ammonites. As discussed under th.e 

stratigraphic summary, the Shelikof formation consists 

of a lower siltstone member 1,500 ft or less in-thickness, 

a middle sandstone· member at least several thousand 

feet thick, and an upper siltstone member from 700 to 

1,000 ft thick. At Wide Bay· the lower member has 
54 CALLOVIAN (JURASSIC) AMM:ONITES FROM THE UNITED STATES AND ALASKA 

.Callovian Oxfordian 

Genera c c ro ro c 

or 

·u 0 0 ...c ·ro- +-' 

subgenera . m ro 

m ;::s 

~ ~ -~ ........:> ~ ~ ~ ~ 

~ ~ '"tj ~ C/;) ~ ~ 

~ ~ ;::s -~ C/;) C/;) 

-~ C/;) 0 -+-=:> ·~ ~ .Q ·~ -~ ~ 

~ ........:> Q ~ ·~ -~ 

~· ~ ~ ~ ·~ ~ 0 0 ~ ~ ~ ~ ~ ~ ~ C/;) ·~ '"tj ~ ~ 0 ~ ...c ·~· ~ ·~ 

·~ ;::s ~ 0 0 ........:> 

~ ........:> ~ '"tj Q ~ 

~ ~ ........:> ~ ~ ~ ~ ~ ·~ ~ ~ ~ 

~ 0 ~ ·~ 0 ~ ~ ~ 0 ~ ~ ~- C/;) 

....!C Q Q ~ -..;:, ~ ~ Q '"tj ~ 

Kheraiceras 

Cadoceras, s. s. 

Paracadoceras 

Pseudocadoceras 

Kepplerites ? 

Gowericeras 

Cosmoceras, s. s. 

Gulielmiceras . 

. Kellawaysites 

Reineckeia, s. s. 

Procerites 

Grossouvria 

TABLE 4.-European ranges of certain ammonites present in Alaska 

furnished Oxycerites, Reineckeia, Oadoceras, Kepplerites, Pseudocadoceras, and Lilloettia. The last two 

genera were found only in the upper part of the lower 

member .. At Wide Bay and Puale Bay (formerly Cold 

Bay) the middle member has furnished Oadoceras and 

Pseudocadoceras. The presence of Reineckeia (KellaW'aysites) about 350 ft above the base of the Shelikof 

formation at one locality on Wide Bay shows that the 

basal part of the formatipn is not older than Callovian. 

COMPARISONS WITH OTHER FAUNAS 

WESTERN INTERIOR OF THE UNITED STATES 

AND CANAUA 

The ammonite assemblage in the Callovian of southwestern Alaska has the appearance of being quite distinct from that in the western interior of North Amer~ 

ica, because nearly all the species are distinct, a number 

of genera and subgenera found in one area are not found 

in the other, and the relative abundance of certain 

genera seems to be different in the two areas. For example, Phylloceras, Ovycerites, Kheraiceras, Paracadoceras and Reineckeia have been found in southwestern Alaska and not in the western interior. Arcticooeras has been found in the Callovian of the western 

interior but not in southwestern Alaska. The abundance of Gowe1·iceras in the western interior. contrasts with its scarcity in southwestern Alaska. The 

genus Oadoceras is represented by different subgenera 

or groups in the two areas. However, much of this. 

apparent <listinctness is due to the fact that most of 

the Callovian ammonites from southwestern Alaska 

have been obtained from beds that are younger than 
ALASKA PENINSULA AND COOK INLET REGIONS 55 

any Callovian beds yet identified in the western interior. 

The faunal differences are not nearly as great if beds 

of the same age are compared. Thus, the lower third 

of the Chinitna formation has furnished a few specimens of Gowericeras, f{epplerites, Oosmoceras ( Gulielmiceras) , and X enocephalites that are either closely 

comparable or identical specifically with ammonites in 

the lower Callovian of the western interior. Contrast 

is furnished by the presence in the lower third of the 

Chinitna of Phylloceras, and certain groups of Oadoceras, such as Paracadoceras,. that are not found 

in the western interior. These differences are probably ecologic, as P hylloceras is rare in deposits of the 

ably ecologic, as Phylloceras is rare in deposits of the 

of Oadoceras varies considerably from place to place 

wi~hin the boreal region. 

ARCTIC REGION OF CANADA 

In the Richardson Mountains of northwestern Canada near tl?-e Arctic Ocean the upper Bathonian is represented by the Arctocephalites beds and the lower 

Callovian by the A rcticoceras beds, just as in the western interior of North America and in East Greenland, 

and similarly Oadoceras is associated with Arcticoce1·as . 

but not with Arctocephalites. Close affinities with the 

lower Callovian of East Greenland is shown by the 

presence of a Uadoceras, probably identical with 0. 

calyw Spath (1932, pp. 69-70, pl. 20, figs. 1a, b) and. 

an Arcticoceras similar to A. kochi Spath (1932, pp. 

53-56, pl. 12, fig. 1, pl. 13, figs. 4-5, .Pl. 14, figs. 1-3, pl. 

15, figs. 1, 4, 6), but having coarser ribbing on the small 

specimens than on the immature forms that Spath 

places in A. kochi. 

ARCTIC REGION OF ALASKA 

The Callovian ammonites found in the Kingak shale 

along the west bank of the Canning River at the mouths 

of Eagle and Cache creeks show both boreal and cen"' 

tral European affinities. Arcticoceras occurs a little 

above the middle of the formation and about 1,000 ft 

above shales containing Pseudolioceras and Erycites, of 

lower Bajocian age. Another 1,850 ft higher at· the 

same locality the shale has furnished many specimens 

of Oosmoceras castor (Reinecke), a species which in 

northwest Europe occurs in the zone of Erymnoceras 

coronatum. This zone is much younger than any Callovian yet found in Greenland or in the western interior 

of the United States, but is probably represented in 

southwestern Alaska. 

EAST GREENLAND AND BARENTS SEA 

The history of the Callovian Sea and the composition 

and distribution of its faunas for the area comprising 

East Greenland and the present Barents Sea (including mainly King Karl Land, Franz Josef Land, Petchora Land, Novaja Zembla a:na Spitzbergen) have been 

discussed in considerable detail by Rosenkrantz ( 1929) , 

Frebold (1929, 1930, 1935), and Spath (1932). From 

their discussions it is apparent that the major movements of the Callovian boreal sea and the succession of 

its molluscan faunas were essentially the same as in the 

western interior of North America and somewhat different from those in southwestern Alaska. Thus, both the 

boreal sea and the western interior sea underwent a 

major transgression.during the early Callovian (zones· 

of M acrocephalites macrocephalus to Sigaloceras calloviense) and a major regression during the late Callovian. In contrast, in southwestern Alaska marine 

waters persisted throughout most of the Callovian. 

Faunally the lower Callovian of the East GreenlandBarents Sea area differs from the ·lower Callovian of 

Alaska by an abundance of Arcticoceras, a scarcity of 

X enocephalites and P aracadoceras and an absence of 

P hylloceras, Lilloettia, and Kheraiceras. It seems 

probable that the differences noted reflect different environmental conditions, as the Callovian seas of the 

western interior and of the Greenland-Barents Sea area 

represent extensive, very shallow floodings of continental masses, whereas the Callovian sea of southwestern Alaska bordered highlands or mountains compa~­

able with those of the present day. 

NORTHWEST EUROPE AND CENTRAL RUSSIA 

. The striking similarities of the Callovian ammanite 

assemblages from England through north west Europe 

into central Russia have been discussed recently by 

Arkell (1939, pp. 196-214: 1945, pp. 340-345, 355; 1946, 

pp. 23-25). Comparisons of these assemblages with 

those from east Greenland and the Barents Sea are~ 

have been made by Spath (1932, pp. 138-157), who 

notes the greater diversity of the cardioceratids in England than farther north and the absence of certain 

groups, such as Ohamoussetia, from the A~ctic areas 

north 9f central Russia. He also notes that in .Europe 

Keppltqrites is replaced southward by Reineckeia and is 

typical of the. zone of M acrocephalites macrocephalus, 

whereas in east Greenland it is abundant in higher beds 

that are probably equivalent to the zone of Sigaloceras 

callo'Viense. He shows that the groups of Oadoceras 

and Kepplerites present in the Arctic areas are in general distinct from those in northwest Europe. He 

ascribes the rarity of cosmoceratids in the Arctic areas 

to the scarcity or absence of deposits of late. Callovian 

age (1932, p. 80). Spath considers that the Arctic seas 

were freely connected with the seas in northwest Europe 

and that the northward changes in the ammonite assemblages favors the existence of climatic ·zones. 

Many of these distinctions between the Callovian ammonite assemblages of northwest Europe and those in 

the Greenland-Barents Sea area apply equally in comparisons between northwest Europe and southwestern 

Alaska, although some of the apparently greater di-
56 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

versity of cardioceratids in England than elsewhere 

may be a matter of description rather than reality. 

Completely missing from the Alaskan Callovian are 

such common European genera as 0 hamoussetia and 

Proplanuiites in the lower Callovian and Erymnoceras 

in the upper Callovian. Xenocephalites is the one distinctive Pacific element in the Alaskan fauna unknown 

from Europe. Lilloettia is probably only a local race 

of M acrocephalites. Kheraiceras is interesting because 

of its abundance in Alaska and because it has not been 

recorded before from Arctic areas, but it has a nearly 

world-wide distributi9n and is represented in Europe 

by similar forms. The Alaskan Callovian is particularly characterized by a greater abundance and diversity of Oadoceras and Pseudocadoceras than exists in 

northwest Europe, according to published records. 

Thus the subgenus Paracadoceras seems to be much 

~ore abundant than in Europe. The group represented 

by 0. doroschini (Eichwald) does not appear to be 

present in Europe. On the other hand the group represented by 0. sublaev·e (J. Sowerby) is.very scarce in 

Alaska. The rarity of Oosmoceras in southwestern 

Alaska cannot be explained by the absence of upper 

Callovian deposits, because the Chinitna formation includes at least the European zones of Oosrnoceras jason 

and Erymnoceras coronatwm. The rarity more likely 

has an ecologic explanation, especially considering that 

the genus is locally abundant· in Montana and on the 

Canning River in northeastern Alaska. 

PACIFIC COAST REGION OF CANADA AND UNITED STATES 

The Jurassic rocks of the Pacific coast r·egion of 

North America have certain features in common that 

distinguish them from the Jurassic of the western interior of the continent and ·of the Barents Sea area. 

They were laid down in fairly narrow troughs that 

received thousands of feet of clastic sediments and volcanics derived from nearby upli~ts. Thicknesses of 

15,000 to 20,000 ft occur in southwestern AlasJra, of 

10,000 to 15,000 ft in western British Columbia, over 

16,000 ft in central Oregon (Lupher, 19~1, p. 227), and 

well over 30,000 ft in northern California (Taliaferro, 

1942; Anderson, 1945, p. 917). Limestones are rare in 

the Jurassic in Alaska and western British Columbia, 

are much subordinate to coarse clastic sedimentary 

rocks in Oregon and _California, and occur mainly in 

the Lower Jurassic and the Bajocian. This occurrence 

may be partly of climatic significance, as the ammonites 

of the Lower Jurassic and Bajocian belong mostly to 

cosmopolitan g_enera whereas the ammonites of the· Bathonian and Upper Jurassic north of California belong 

mostly to genera that are either distinctly boreal or related to those in northwestern Europe. These include 

Oadoceras, Paracadoceras, Pseudocadoceras, Lilloettia, 

Kepplerites, and Oosmosceras in the Callovian, Oardio-. 

ceras in the lower Oxfordian, and Amoeboceras in the 

upper Oxfordian. Perisphinctid ammonites are as rare 

as in the Boreal province. In. the Uppe~ Jurassic of 

northern California some of the ammonites characteristic of the Boreal province occur in the same forip.ation with perisphinctids such as characterized the Upper Jurassic of Mexico and the Mediterranean province. 

Thus the Mariposa slate, of Kimmeridgian age, contains Amoeboceras ( Amoebites) of boreai affinities 

(Reeside, 1919, p. 38, pl. 24, 'figs. 5-8) and perisphinctids of Mediterranean affinities (Crickmay, 1933, pp. 

56-58) . The Knoxville formation, of Portlandian age, 

contains ammonites that are entirely of Mediterranean 

aspect. It appears, therefore, that during the Late 

Jurassic northern California occupied a position between the faunal provinces comparable to that occupied 

by central Europe and southern England (Spath, 1932, 

. pp. 146-150). 

Concerning diastrophism in the Pacific coast region 

south of Alaska, it may be significant that to date ammonites of latest Callovian and middle and late Kimmeridgian ages have not been identified. This is 

consistent with the absence in the western interior of 

marine upper Callovian, Kimmeridgian and Portlandian, and perhaps even upper Oxfordian.' Also, in East 

Greenland and the Barents Sea areas, there is no faunal 

evidence of the upper Callovian, representing the zones 

of Oosmoceras jason, Erymnoceras coronatum and Peltoceras athleta, or of the middle Kimmeridgian (Spath, 

1932, pp. 146-157; 1935, pp. 66, 70, 80). The evidence 

is sufficiently strong to show that there were two major 

marine regressions, culminating in the upper Callovian 

and the middle Kimmeridgian. 

MEXICO 

This region has been discussed in considerable detail 

elsewhere (Burckhardt, 1930; Imlay, 1943). The Callovian has been identified faunally only in southern 

Mexico, where it is represented by more than 2,000 ft 

of dark marine shale and limestone (Burckhardt, 

1927). The lower part of the Callovian grades downward into the Bathonian and contains the ammonites 

Reineckeia, Reineckeites, X enocephalites, Eurycephalites, Pleurocephalites, Ohoffatia, and Subgrossowvria of 

early Callovian age. The upper 275 ft of the Callovian contains the ammonites Reineokeia, Erymnoceras, 

Kellawaysites, and Peltoceras, of later Callovian age. 

Spath (1933, p. 769) considers these highest beds upper 

Callovia~ but not as high as the P eltoceras athleta zone 

o:f northwest Europe, probably because of the abundance 

of reineckeiids and the scarcity of perisphinctids. 

Faunally, the affinities are mainly with the Mediterranean province, as shown by the abundance of reineckeiids and peltoceratids. Among the ammonites only 

Kellawaysites and Xenoqephalites_ have been found in 

southwestern Alaska. Of these, Kellawaysites is 

known only from one specimen and X enocep,halites 
ALASKA PENINSULA AND COOK INLET REGIONS 57 

seems to be a Pacific element common to the Callovian 

of both North and South America. The close resemblances of Ewrycephalites to Lilloettia suggests that 

the two are only geographical variants of the same 

genus. Contrasts with the Alaskan Callovian among 

the other invertebrates include an abundance of gastropods and brachiopods and a scarcity of belemnites. · 

ECOLOGIC CONSIDERATIONS 

CONDITIONS OF DEPOSITION 

The Callovian sedimentary rocks now exposed in 

the Matanuska Valley, the northwest side of Cook Inlet, and the f)outheast side of the Alaskan Peninsula 

were deri;ved from mountainous highlands that lay 

immediately to the north or northwest. This is shown 

by the southward thinning of thick masses of sandstone 

in the Shelikof formation of the Alaskan Peninsula and 

by a southeastward decrease in sandy material in the 

lower part of the Chinitna formation on the Iniskin 

Peninsula. Nearness to land is shown by the pebbly 

character of some. of the Callovian beds on the Alaskan 

Peninsula and in the Matanuska Valley, by the presence locally of granitic boulders as much as 2ft in diameter, and by the thick lenses of massive sandstone _in the 

Chinitna formation northwest of Cook Inlet. The con-

. siderable thickness of Callovian sedimentary rocks 

( 4,000 to 6,000 ft), implies rapid· subsidence of the sea 

bottom and an ample source of sediment. The many 

thin seams of tuffaceous material in the siltstone suggest deposition below wave base. However, the presence of some massive sandstone beds and the local reworking of fossiliferous Callovian cqncretions into conglomeratic zones within the Callovian sequence indicates that at least locally the sea bottom was subjected 

to strong wave and current action. That the Callovian 

sediments of southwestern Alaska were deposited along 

a steep slope fronting a major ocean rather than in a 

shallow arm of the sea comparable to the present Cook 

Inlet is suggested by the abundance of the thin-shelled 

ammonite, Phylloceras, by the persistent thin banding 

in most of the siltstones, and by the rapid lithologic 

change southward from conglomerates to siltstone 

within the Shelikof formation. Probably the sea shore 

was indented by many small bays similar to those 

existing today. 

Vulcanism in the area of southwestern Alaska during Callovian time is attested by the occurrence in the 

siltstones of many thin beds of ashy material that 

weathers reddish brown. Such ashy material is not evident in the sandstones although possibly it causes the 

greenish color of most sandstone beds. Also, the general composition of the sandstones and conglomerates 

within the Shelikof formation indicates that their source 

rocks were mostly granitic and dioritic. 

Possibly related to vulcanis1n is the occurrence of 

numerous calcareous concretions in the Callovian siltstones associated with ashy beds. The concretions may 

crop out singly or in rows. In many places the conditions of collecting do not permit close observation of 

the bedding relationships of the concretions, but on 

some steep banks the concretions cr:op out in rows that 

appear to coincide with thin tuffaceous beds. 

The Callovian beds are bounded by disconformities 

that are determinable faunally (as discussed under the 

stratigraphic summary), and also include minor sedimentary breaks or diastems without faunal significance. 

One example of such is present at the northwest. end 

of Chisik Island in Tuxedni Bay, according to observations by Don J. Miller and R. W. Imlay. At this place 

about 200 ft of interbedded concretionary sandstone 

and siltstone are truncated abrubtly by a channel-like 

coarse conglomerate that consists mostly of concretions 

containing Callovian ammonites _and Inoceramus. The 

base of the conglomerate rests in beds that contain 

Kheraiceras and Procerites and represent the basal part 

of the Chinitna formation. The upper part of the conglomerate passe$ laterally into a pebbly sandstone from 

the top of which. issue many springs and which lies with 

apparent conformity between Callovian siltstones. 

The conglomerate and associated pebbly sandstone· appear to be isolated on Chisik Island as they have not 

been found in the Callovian beds several miles to the 

southwest on the south side of Tuxedni Bay. From 

these relationships it seems evident that the sea bottom 

in the area of Chisik Island was scoured during early 

Callovian time by a river or by a shore current that 

removed a considerable amount of sediment locally and 

concentrated the concretions in the resulting submatine 

channel. 

Another example of local scouring during Callovian 

time was observed by Don J. Miller and R. W. Imlay 

on the southwestern side of Wide Bay on the Alaskan 

Peninsula. Along the shore of Wide Bay from 3 to 

4 miles southwest of Hartman Island, the middle sandstone member of the Shelikof formation rests sharply 

on the lower siltstone member. A bed of coarse conglomerate ranging from 5 to 45 ft above the base of the 

·sandstone consists mostly of volcanic and granitic rocks 

but, also, consists partly of limestone concretions tl.lat 

contain Pseudocadoceras grewinglci (Pompeckj), Oadoce;as stenoloboide Pompeckj, and Lilloettia bucknwni 

· ( Crickmay) . As these same ~pecies were collected 

from concretions in the lower siltstone member at the 

same locality it seems evident that the concretions in 

the conglomerate were eroded from the siltstone 

member. 

A similar coarse conglomerate consisting mostly of 

quartz diorite and granite but containing some fossiliferous concretions of Callovian age was noted by 

Smith (1926, pp. 73-75) about 5,000 ft below th'e top 
58 . CALLOVIAN (.JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

of the Shelikof formation near the. head of Salmon 

Creek about half way between Wide Bay and Puale 

Bay. It seems likely that the stratigraphic position of 

this conglomerate is near the base of the middle sandstone member of the Shelikof formation. 

These examples afford positive proof of local inter-

. ruptions in sedimentation during Callovian time as a 

result of current action or a change in base level. It is 

inferred that many other similar .breaks,. or r_muses in 

deposition, exist th:roughout the . Callovian sequence, 

particularly in places where there is a sharp boundary 

between siltstone and sandstone beds. Local thick 

masses of sandstone may reasonably be interpreted as 

channel deposits filling in depressions from which silt-. 

stone has been scoured. The ammonites occurring in 

concretions in such massive sandstone may have originally been embedded in siltstone and subsequently 

washed into the depressions. 

54" 

164 

FAUNAL ASSEMBLAGES 

The ammonites in the Callovian,beds of southwestern 

Alaska are the most conspicuous faunal element. · They 

are dominated by the fairly thick-shelled Cardioceratidae, belonging to the genera Oadoceras and Pseudo-

. cadoceras, that comprise rriore than 80 percent of the 

ammonite specimens. The Macrocephalitidae are second in abundance and are represented by Lilloettia, 

Xenocephalites, and Kheraiceras. Much less common 

are the Cosmoceratidae, represented mainly by Kepplerites but including rare specimens of Gowericeras and 

Oosmoceras. The Op:Qeliidae is represented only by 

Oppelia ( Owycerites) . .,. The Phylloceratidae are represented by Phylloceras, Oalliphylloceras, M acrophylloceras, and Partschiceras. Two specimens of Reineckeia 

represent the Morphoceratidae. 

Among these ammonites only Phylloceras, Oadoceras 

and Pseudocadoceras occur in the highest Callovian 

2. Matanuska Valley 

3. Tuxedni Bay Area 

4. Chinitna Bay Area·_, 

5. lniskin Peninsula · 

6. Puale Bay to Portage· 

Bay Area 

. Wide. Bay Area 

\: 

~ ~ . 

I D 

FIGURE 3.-Index map of the principal areas of Jurassic rocks in the Alaska Peninsula and Cook Inlet regions. Alask~. (See figures 4-9). 
ALASKA PENINSULA AND COOK INLET REGIONS '59 

beds. Pseudocadoceras has not been found. in the 

lowest beds. Gow·ericeras and Reineckeia have been 

found only fairly low stratigraphically. Paracadoceras, 

a subgenus of Oadoceras, has not been found above the 

lower two-fifths of the Callovian. 

The ~mmonites occur mostly in concretions in siltstones but some occur in concretions in sandstone. 

Some of the larger concretions contain many- ammonites, others have a single ammonite in the center. 

Many of the· concretions barely encompass a single ammonite, and commonly the ammonite protrudes much 

beyond the concretion.· In addition, many undeformed 

. ammonites not associated with concretions occur in 

siltstone or in massive sandstone. As these ammonites 

consist of calcium carbonate and as many are lined 

internally with crystals of calcite, they were probably 

preserved and hardened by the chemical process that 

formed the concretions. Crushed ammonites are most 

common in the thin-bedded sandstones, generally not 

associated with concretions. Possibly some of the ammonites that occur in the massive sandstones have been 

winnowed out of siltstones by submarine erosion. This 

may be true of the ammonites in the massive sandstone 

at the top of the siltstone of the Chinitna on the north 

slope of Mount Pomeroy at the southern end of the 

Iniskin Peninsula, as these ammonites are conspecific 

with those in the middle part of the siltstone of the 

Chinitna at the north end of the Iniskin Peninsula. · 

The faunal elements other than ammonites in the 

Callovian beds consist . of belemnites, pelecypods, gastropods, brachiopods, crustaceans, ·worm tubes, plant 

leaves, and wood fragments. These have been examined 

only casually. Belemnites are common in the Shelikof 

formation and rather uncommon in the siltstone of the 

Chinitna. They appear tobe generically distinct from 

the belemnites in the Callovian beds of the western interior of the United States, in agreement with the 

generic assignments made by Spath ( 19;32, p. 154). 

Pelecypods ·are fairly common throughout the Callovian. beds of southwestern Alaska, but not nearly as 

conspicuous as the ammonites. They are more common 

in sandy or silty beds than in concretions where most of 

the ammonites occur. Some of the pelecypod genera 

have been listed by Stantqn in l\fartin (1926, pp. 164, 

200, 228). Other genera represented include Tancredia 

and Quenstedtia. It is interesting that such shallowwater forms as Meleagrinella .and Ostrea ar€ rare in 

Alaska except in the shelly sandstone at the base of the 

Chinitna formation on the Iniskin Peninsula. The 

listing of Gryphaea from the siltstone of the Chinitna 

of the Matanuska Valley probably represents ·a misidentification of the formation, as the specimens in question are associated with Ormnocephalites and are identical with G.ryphaea impressimar'ginata (McLearn), 

which occurs in the Bathonian beds in the western interior. -Of the other classes of organisms, the gastropods and brachiopods are rather uncommon but occur 

more frequently in the Shelikof formation than in the 

siltstone of the Chinitna. The crustaceans, plant leaves, 

and wood fragments· are all rare and occur in concretions. 

40' . 147~ 20' 

62' 

FIGURE 4.-Index map showing Callovian localities at the bead of Matanuska Valley, Cook Inlet region. Numbers on map refer to those 

given in the locality list (p. 65) and in the distribution table: 

ECOLOGIC IMPLICATIONS 

DEPTH OF WATER 

The probability that much of the siltstone in the 

Callovian sequence was deposited below wave base as 

indicated by the persistence of thin bands of ashy 

material has aiready been discussed. Further evidence 

are the fair abundance of Phylloceras, the absence of 

Gryphaea and nautiloid cephlapods, and the scarcity 

of M eleagrinella and Ostrea. This condition contrasts 

with the Callovian deposits of the western interior of 

the United· States in which Ostrea, Gryphaea, and 

M eleagrinella are very abundant, nautiloids are fairly 

common, and Phylloceras is absent. This co!ldition 

likewise contrasts with that in the Middle Jurassic beds 

of southwestern Alaska in which M eleagr'inella is common and the other . forms mentioned are represented. 

Of course, the absence of Gryp·haea and the rarity of 

M eleagrinella and 0 strea ·in the Callovian beds of 

southwestern Alaska might be explained on the basis of 

temperature rather than depth of water, or may reflect 

changes in both temperature and depth. 'Wha~ever the 

explanation, pelecypods are much less common in numbers, species and genera in the Callovian beds than in 

the underlying Middle Jurassic and do not contain cer~ 

tain genera that are abundant elsewhere in the shallowwater deposits of the Jurassic. The presence of Phylloceras and the absence of nautiloids in the Callovian of 

southwestern Alaska is more clearly related to depth o£ 

water than to temperature, as the opposite faunal condition exists in the shallow-water Callovian deposits of 

the western interior of the United States, and Phylloceras is now kno'Yn from the Canning River area of 
60 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Arctic Alaska in association with such boreal forms as 

il.ucella and Amoeboceras: Also, the scarcity of the 

thin-shelled ammonites Phylloceras and Lytoeeras in 

the Jurassic of East Greenland ( 1932, pp. 151, 152) 

contrasts with their abundance there during the Lower 

Cretaceous (Spath, 1946, pp. 6, 7) and may be more 

ru,..r 

Eo N; 

152° 40' 

B A Y 

easily explained by changes in depth of water rather 

. than in temperature. This does not necessarily mean 

that Phylloceras and Lytoceras lived exclusively in deep 

water, as postulated by Haug (1907, p. 1119), but that 

because of their thin ·shells they avoided the shallowest 

waters of the epeiric and shelf seas. In some places, 

EXPLANATION 

0 1 i 1 Miles L-~--L-~--L-----------~~~------~--------~ 

/ - _l 

L' 

/ ~-"-~ "\ 

60° .... - I' ........ 

10' .... .::,. --:..:;. ' ........... 

........... ... ......... 

- --...... .... .... ./ - .... 

... 

.J 

\ 

~------------------------------7/--~~, 

~----~'~ ... ~-------------------e~r·r~L----~~(1_~--~~ e'-='-______ _,r-r-------1\ 

~--------~'~,------------0~~~~--~---~J~ __ ___,I - ---. 

12 

~ 

1\ 

1\ 

- ~\' 

-.--.-

Contact 

Unsurveyed streams 

,\ 

I\ 

1\ 

IJ 

~ I 

1\ 

1\ 

I 

v \ 

\ Jl 

~ 

After F. H. Moffit and Don J. Miller 

FIGURE 5.-Index map showing Callovian localities in the Tuxedni Bay a rea, Cook Inlet region. Numbers on map refer to those given in the 

locality list (p. 65) and in the distribution table. 

ALASKA PEN~SULA AND COOK ~ET REGIONS 61 

such as Alaska, where fairly deep waters approached 

the shores, the shells of such ammonit~s might easily. 

become intermingled after death with those of thickershelled ammonites that lived in shallow waters. 

TEMPERATURE AND CLIMATE 

Cooling of the boreal sea and the development of 

climatic zones during late Middle Jurassic time and 

Late Jurassic time is suggested by the absence of. corals 

and the rarity of gryphaeas and exogyras in the boreal 

\ 

Jurassic aft~r early Bajocian time, by the change -in 

the character of the ammonites and belemnites from 

cosmopolitan to provincial during ·Middle Jurassic 

time, and by the scarcity of deposits of calcium carbonate other than as concretions in the Middl~ and 

Upper Jurassic sediments. The existence· of climatic 

zones in the Jurassic much less distinct than today has 

been upheld by N eumayr ( 1883, 1885), Haug ( 1907, 

p. 117), Stanton (1910), Uhlig (1911, pp. 435-448), 

Burckhardt (1930, p. 123), and Spath (19.32, pp. 146-

D . ) f-0: ~> <t<t 

Alluvium :::>Z 

·o 

~~ ffiD] :g . ~ ~ Naknek formation Vl 

Vl 

~ f?jj(J <t 

a: 

::S Chinitna formation :::> 

~.~ [ ·-<:I ~~ ~H; 

~ . 'S Tuxedni formation 

Contact 

x20 

A Callovian locality 

B y 

GULL 

ISLAND 

0 I Mile 1! 59° 50' 

FIGunrn 6.-Index map showing Callovian localities near Chinitna Bay, Cook Inlet region. Numbers on map refer to those given in the l.OcaJity 

list (pp. 66, 67) and in the distribution table. 

... ·.-....c 

~":\: J~ 
62 CALLOVIAN (JURASSIC) .AMMONITES FROM THE UNITED STATES ,AND ALASKA 

153) because of the dissimilarity of the ammonite 

faunas of the Mediterranean and Boreal Provinces. 

Also, Gothan (1908) and Antevs (1925) consider that 

EXPLANATION 

D 

Alluvium 

·~j ~ Naknek []]]] formation 

ll: ~ r~;:~;a // ::5 Chinitna formation 

~·"{ ~~ lii ~ Tuxedni ~ formation 

Contact 

)(85 Callovian locality 

RIGHT 

the marked rings in the Jurassic woods from Spitzbergen and the absence of rings in Jurassic woods from 

East Africa indicate marked . climatic zones. Some 

0 L 

8 A Y 

0 2 MILES 

153 "20' 153"15' 153°10' 

FIGURlll 7.-Index map showing Callovian localities In the central and southern parts of the Iniskln Peninsula, Cook Inlet region. Numbers on 

map refer to those given In the locality list (pp. 67-69) and in the distribution table. 
ALASKA PENLNSULA AND COOK LNLET REGIONS 63 

workers have believed that the faunal dissimilarities are 

due to physical barriers or isolation ( Salfeld, 1921 ; 

Nikitin, 18.86) or have suggested that the faunas compared are possibly not of the same age (Frebold, 1929," 

p. 18). The evidence has been smpmarized recently by 

Spath (1932, pp. 146-153; 1935, pp. 75-78), who shows 

that the Late Jurassic ammonite faunas change gradually from north to south across Europe and that in central Europe and ·southern England occur an admixture 

of boreal and Mediterranean genera that would. not 

have been possible if .the boreal sea had been isolated. 

Likewise, among the belemnites in central Europe oc~ 

curs an association of genera of the Mediterranean 

Province with genera of the Boreal Province. He presents rather convincing evidence that the boreal sea was· 

connected with the Mediterranean sea through several 

straits, including at least the Shetland Straits, Mackenzie. Straits, and a strait in eastern European Russia. 

It is conceivable that constriction of these straits might 

lead to cooling of the boreal sea, but against this idea 

BAY 

A~ek 5~ ~+R~~~OY~tH+H~~~~~~~rr~~~47~~+¥~~~~--~----------------------~----_, a 

Cape lgvok 

i 

5 0 S.Miles 

156'00' 

EXPLANATION 

>-

D JI . 

. 

Alluvium 

0 

Intrusive rocks }! 

Naknek • formation 

0 

u; 

(f) 

<( 

0:::: 

:::> 

Shelikof formation .., 

-~[ ~ 

~ ~ ~ Sandstone, shale, j .3 and conglomerate 

.~( ~ l ~ . 2 ·~ ~ ~ <( 

~ Thin-bedded 0:: 

g. limestone and chert ..,_ 

~ 

155 40' 

Contact 

Callovian locality 

. 155"20 

After S. R. Capps, W. R. Smith, 

A. A. Baker and Don J .. Miller 

FIGURE 8.-Inde.:t map showing Callovian localities in the P nale Bay to Portage Bay area, Ataska Peninsula region. 

Numbers on map refer to those given in the locality list (pp. 69-70) and in the distribution table. 
64 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

is the fact that the boreal sea was much more widespread in the Late Jurassic than in the Early Jurassic, 

when the waters were apparently warmest, as indicated 

by the gryphaeas, corals, and ammonites, although some 

writers have presented contrary evidence (Schuchert, 

1914, pp. 280, 281) based on dwarfing of insects and 

the abundance of black shale and coal in the Lias. Another fact suggesting that the Boreal Province was 

cooler than the Mediterranean Province is the poverty 

of the northern faunas in molluscan genera and species, 

and the abundance of individuals of the species, which 

relationship is reversed in the Mediterranean Province. 

A similar relationship is reported to exist today between the Arctic or Antarctic and the equatorial seas 

(Twenhofel,. 1939, pp. 159, 160; Russell and Y ~:mge, 

1936, p. 58). 

·More direct evidence that the Callovian s:as of southwestern Alaska were cooler than marine waters farther 

south is furnished by the absence of Exogyras, Gryphaeas, and corals. The absence of Emogyra is no~ surprising, as the genus is typically Mediterranean and is 

absent even from the Jurassic deposits of the western 

interior of the United States. However, the absence 

of Gryph.aea contrasts with the abundance of the genus 

in the Callovian in the western interior region, in central Europe, and locally in the Mediterranean Province, 

such as in southern Mexico. Its absence in southwest-: 

ern Alaska cannot be ascribed to the lack of a suitable 

substratum, although the genus occurs in greatest abundance in soft calcareous shales, or to the lack of shallow 

water as, at least locally, some of the sandstone units 

EJ 

Alluvium 

·a mrn ~ 

~ Naknek formation 

~ w;:;A ~ 

~-i~ She~motion i · ~ Kialogvik formation 

show evidence of -scouring. Rather, the absence of 

Gryphaea can readily be explained by a temperature 

too -low for its growth, by rapid subsidence of the sea. 

bottom, and by the scarcity of readily available calcium 

carbonate in the sea water. The absence of limestone 

beds in the Callovian might itself reflect low temperature of the sea water, or be due to dissemination of the 

calcareous material throughout the thousands of feet 

of Callovian siltstone and sandstone. However, such 

dissemination has not occurred as the Callovian siltstones are mostly noncalcareous and many of the sandstones are noncalcareous. It appears, in fact, that most 

of the calcareous material present is in the concretions 

and fossils and that the origin of many of the concretions is related to deposition of volcanic ash. 

The absence of corals above the lower Bajocian in 

southwestern Alaska may likewise be explained by an 

'unravorable temp~rature of the seawater, by lack of 

cv.lcareous material, or by unsuitable bottom. condi-

-tions. Certainly the absence of corals in the Jurassic 

throughout the entire Boreal province north of Yorkshire, England, and southwestern Alaska is more likely 

to be related to an unfavorable temperature than to bottom conditions, which vary from place to place and 

·would probably be suitable for coralline growth in 

some parts of the province. 

HABITATS 

Most of the Callovian fossils from southwestern 

Alaska represent free-swimming organisms, such as 

ammonites, belemnites, pectens, pterias, and oxytonias. 

These are found both in the sandstones and siltstones, 

FIGURE 9.-Index map showing Callovian localities in the Wide Bay area, .Alaska Peninsula region .. Numbers on map refer to those given in 

the locality list (pp. 70, 71) and in the distribution table. 
ALASKA PENINSULA AND COOK INLET REGIONS 65 

and are best preserved in the concretions. On the soft 

mud bottoms, now preserved as dark gray siltstone, 

lived such organisms as Nucula, Nuculana, Grammatodon, Astarte, Thracia, Goniomya, Plewrom;ya, Pholadomya, Pinna, Trigonia, Inoceramus, Tancredia, 

Quenstedtia, and some gastropods and brachiopods. 

The last two classes were much more common on the 

sandy bottoms associated with Trigonia and Inoceramus 

but were not common in the thick sandlenses. None 

of these molluscan genera is indicative of the littoral 

zone and they could represent the deeper part of the 

neritic zone. The basal shelly sandstones of the Chinitna formation were probably deposited in the shallow 

part of the neritic zone ·as they contain a few M eleagrinella and Ostrea. Microfossils are singularly uncomiPon in the siltstones. It. seems unlikely that the 

cephalopods could have derived any appreciable part 

of their food supply from the other organisms now 

preserved as fossils. -

GEOGRAPHIC DISTRIBUTION 

The occurrence by area and locality of the 62 species 

described in this report is indicated in the table facing 

p. 72. The position of the various areas 'of Callovian 

sedimentary rocks is shown in figure 3, and the general 

position of each locality is shown in figures 4 to 9. Detailed descriptions of the·individuallocalities are given 

in the following list. 

Localities at which ammonites were collected from the Callovian strata of southwestern Alaska 

No. on Geological 

fi Survey Meso- Collector's field numbers 

gs. 4-9 zoic locality Collr.ctor, year of collection, description of locality, and stratigraphic assignment 

1 

2 

3 

3 

4 

5 

5 

6 

7 

8 

8 

8 

9 

10 

11 

11 

12 

12 

13 

3700 

8571 

3016 

21291 

21287 

'3015 

21286 

21273 

10250 

3014 

12074 

21272 

2992 

21285 

2~91 

21290 

2990 

22554 

21288 

6AK156__________ Adolph Knopf, 1906. Talkeetna Mountains, near headwaters of Nelchina River, about 

10 miles N. 10° E. of mouth of Billy Creek at altitude of 5000 ft. Float from Chinitna 

formation. · 

20 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ G. C. Martin, 1913. 'Talkeetna Mountains, tributary to Boulder Creek from north, 

3 miles above East Fork.. Float from Chinitna formation. 

920______________ T. W. Stanton, 1904. Tuxedni Bay, northeast shore of Chisik Island. Chinitna formation, near top of middle third. 

48AI72___________ R. W. Imlay and D. J. Miller, 1948. Tuxedni Bay area, north shore of Chisik Island, 

2.86 miles N. 76° E. of Fossil Point. Chinitna formation, middle third, from 75 to 100 

ft below the sandstone unit at base of upper third. 

~8AI7L__________ R. W. Imlay and D. J. Miller, 1948. Tuxedni Bay area, northwest shore of Chisik Island, 

1.57 miles N. 77° E. of Fossil Point, about 80ft above base ot Chinitna formation. 

919______________ T. vV. Stanton, 1904. Tuxedni Bay, north end of Chisik Island about X mile northeast 

of point formed by massive conglomerate, Chinitna formation, lower third. 

48Al70___________ R. W. Imlay.and D. J. Miller, 1948. Tuxedni Bay area, northwest shore of Chisik Island 

1.35 miles N. 88° E. of Fossil Point, about 30 ft above base of Chinitna formation. 

48AI69~---------- D. J. Miller and R. W. Imlay, 1948. Tuxedni Bay area, northwest shore of Chisik Island, 

1.3 miles N. 90° E. of Fossil Point, from 50 to 100 ft above lowest exposure, Chinitna 

formation, near ba~e. 

Q_ _ _ _ __ _ _ __ ___ _ _ C. N. Fenner, 1919. Tuxedni Bay, Chisik Island, northwest end from beds above massive 

conglomerate, Chinitna formation, lower third. 

918 ______________ T. W. Stanton, 1904. Tuxedni Bay area, north end of Chisik Island, 1.25 miles S. 81° E. 

of Fossil Point, 1 ft below base of channel conglomerate, Chinitna formation, near base. 

A________________ W. R. Smith, 1923. Tuxedni Bay area, Chisik Island, 5 miles north of cannery and across 

bay fr01n Fossil Point. · Chinitna formation, lower third. _ 

48AI68 ____ _:______ D .. T. Miller and R. W. Imlay, 1948. Tuxedni Bay area, northwest shore of Chisik Island, 

1.25 miles S. 81° E. of Fossil Point, 1 ft below base of channel conglomerate, Chinitna 

formation, near base. 

913______________ T. W. Stanton, 1904. Tuxedni Bay, west shore of Chisik Island, near northwest end. 

Chinitmi. formation, lower third, from shale overlying a massive conglomerate. 

48AI67___________ R. W. Imlay and D. J. Miller, 1948. Tuxedni Bay area, west shore of Chisik Island, 

1.5 miles S. 70° E. of Fossil Point, about 20 ft below top of sandstone unit from which 

.. issue many springs. · Chinitna formation, near .top of lower third. 

912b_____________ T. W. Stanton, 1904. Tuxedni Bay, west shore of Chisik Island. Chinitna formation, 

upper third, several hundred feet below top. , 

48AI55 ________ _,__ R. W. Imlay and D. J. Miller, 1948. Tuxedni Bay area, wesfshore of Chisik Island, 3.94 

miles S. 43° E. of Fossil Point. Chinitna formation, upper third, from 300 to 375 ft 

below top. 

912a _____________ T. W. Stanton, 1904. Tuxedni Bay, west shore of Chisik Island near entrance to Snug 

Harbor.· Chinitna formation near top of upper third. 

50AHa69_________ Arthur Grantz, 1950. Chisik Island, west shore, near top of Chinitna formation. 

48AI83 ______ . _____ R. W. Imlay and D. J. Miller, 1948. Tuxedni Bay area, head of stream entering Bear 

Creek from the southeast at first outcrop above mouth, 5.2 miles S. 17° W. of Fossil 

Point. Chinit.na formation, lower third, about 600 ft above base. 
66 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Localities at .which ammonites were collected from the Callovian strata of southwestern Alaska-Continued 

No. on Geological 

ft Survey Meso- Collector's field numbers 

gs. 4-9 zoic locality Collector, year of collection, description of locality, and stratigraphic assignment 

3019 923b _____________ 

3020 923c ____________ ~ 

21343 48AI 19 _________ - _ 

21342 48AI18 _____ - _----

21774 49AHa62 _______ - _ 

10978 F 1--------------

21777 49AGz33_ --------

21347 48AI23 _________ --

21776 49AG19 ___ -- _----

21778 49AG34 __________ 

109.97 ABF4 _________ .;. __ 

11011 ABF19 ______ -----

21346 48AI22 ___________ 

22421 50AHa30 _________ 

21348 48AI25 ___________ 

22438 50AHa.36 _________ 

22437 50AHa.34 ____ ~ ____ 

21341 40AI15 ___ .:. _______ 
No. on figs. 4-9 

35 

36 

37 

38 

39 

40 

41 

42 

43 

43 

44 

45 

46 

46 

47 

48 

49 

50 

51 

52 

53 

. 54 

55 

56 

57 

ALASKA PENINSULA AND . COOK INLET REGIONS 67 

Localities· at which ammonites were collected from the Callovian strata of southwestern Alaska-Continued 

Gcolo~al Survey . eso- zoic locality 

21340 

22556 

21339 

21322 

21324 

21331 

21321 

21325 

21327 

21330 

21326 

21329 

21328 

21332 

22442 

11041 

10982 

21320 

21333 

21334 

11047 " 

10986 

21335 

21349 

20761 

Collector's field numbers 

48AI14 ___________ 

46AKr192 ________ 

48AI13 ___________ 

48AI38 ___________ 

48AI4Q ___________ 

\ 

48AI 4 7 ___________ 

48AI37 ---- _______ 

48AI4L _________ .: 

48AI43 _____ -- ____ 

48AI46 ___________ 

48AI42 _________ · __ 

48AI45 ___________ 

48AI44 ___________ 

48AI48------~----

50AHil3 __ ---- ___ 

ABF5Q ___________ 

F4a ______________ 

48AI49 ___________ 

48AI50 ___________ 

48AI5L __________ 

ABF56 ___________ 

F8---------~-----

48AI52 ___________ 

48AI53 _____ -- ____ 

46AKrl63 ________ 

Collector, year of collection, description of locality, and stratigraphic assignment 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, first tributary entering Park 

Creek from the southeast above the mouth, 2.95 miles S. 86° ·E. of dock at mouth of 

Fitz Creek, about 900 ft above base of middle third of Chinitna formation. 

C. E. Kirschner, 19_46. Iniskin Peninsula, 4 miles S. 84° E. of dock at mouth of Fitz 

Creek, Chinitna formation, upper part of middle third. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, first tributary entering Park 

Creek from the southeast above mouth, 3.1 miles S. 84° E. of dock at mouth of Fitz 

Creek, about 1,200 ft above base of middle third of Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, northeast side of Tonnie Creek 

valley near head, 1, 750 ft S. 35° E. of Tonnie Peak, from limestone concretions 565 

to 585 ft above base of the Chinitna formation. 

R. W_. Imlay and D. J. Miller, 1948. Iniskin Peninsula, northeast side of Tonnie Creek 

valley near head, 2,000 ft S. 37° E. of Tonnie Peak, float obtained about 400 ft above 

base of the Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, near head of Tonnie Creek, 2,000. 

ft S. 30° E. of Tonnie Peak, 425ft above base of the Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, northeast side of Tonnie Creek 

Va.lley near head, 2,100 ft S. 45° E. ·of Tonnie Peak. From 350ft above base of Chinitna 

formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, northeast side of Tonnie Creek 

Valley near head, 2,400 ft S. 50° E. of Tonnie Peak, from siltstone about 350 ft above. 

base of Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Peninsula, near heP.d of Tonnie Creek, 2,600 

ft S. 43° E. of Tonnie Peak, 70 ft above base of the Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. · Iniskin Peninsula, same as loc. 21327 but nearer 

Tonnie Creek, about 70 ft above base of the Chinitna formation. 

R. W. Imlay and D. J. Miller, 1949. Iniskin PE-ninsula, divide between Tonnie Creek and 

Forky Creek, 2,850 ft S. 55° E. of Tonnie Peak,. about 100 ft above base of Chinitna 

formation. 

R. W. Imlay and D. J. Miller, 1948. lniskin Peninsula, near head of Tonnie Creek, 2,400 

ft S. 39° E. of Tonnie Peak, from 130 to 155 ft above base of the Chinitna formation. 

it. W.- Imlay and D. J. Miller, 1948. Iniskin Peninsula, near bead of Tonnie Cree>k, 2,500 

· ft S. 43° E. of Tonnie Peak, from 90 to 100ft above base of tlie Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. lniskin Peninsula, near·head of Tonnie Creek, float 

from same locality as 21328, about 90 to 100 ft above base of the Chinitna formation. 

D. M. Hill, 1950. lniskin Peninsula, 2.8 miles N. 35° E. of Front Mountain. Chinitna. 

formation, near base of middle third. 

A. A. Baker, 1921. lniskin Peninsula, near head of Bowser Creek about 1. 7 miles N. 17° 

E. of Front Mountain. Chinitna formation, a little below middle of lower third. 

F. H. Moffit, 1921. Iniskin Peninsula, head of Bowser Creek, south side of valley, 1.7 

miles N. 42° E. of Front Mountain. Chinitna formation, upper part of middle third. 

D. J. Miller and R. W. Imlay, 1948. lniskin Peninsula, 4. 7 miles S. 15 ° E. of Tonnie Peak, 

Chinitna formation, near base. 

R. W. Imlay and D. J. Miller, 1948. lniskin Peninsula, on stream entering Bowser Creek 

from southeast, 4.32 miles S. 19° E. of Tonnie Pe>ak, a little below middle of the lower 

third of the Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. lniskin Peninsula, on stream entering Bowser Creek 

from southeast, 4.42 miles S. 20° E. of Tonnie Peak, a little above middle of the lower 

third of the Chinitna formation. 

A. A. Baker, 1921. Iniskin Peninsula, on tributary to Bowser Creek about 1.1 miles N. 

20° E. of Front Mountain. C~initna formation, near top of lower third. 

F. H. Moffit, 1921. Iniskin Peninsula, tributary to Bowser Creek from south, next below 

head branch of creek, about 1 mile N. 26° E. of Front Mountain. Chinitna formation, 

near top.of lower third. 

R. W. Imlay and D. J. Miller, 1948. lniskin Peninsula, on stream entering Bowser Creek 

from southeast, 4.52 miles S. 21° E. of Tonnie Peak, near top of the lower third of the 

Chinitna formation. 

R. W. Imlay and D. J. Miller, 1948. Iniskin Pe~nsula, on stream entering Bowser Creek 

from the southeast, 4.62 miles "S. ~1 ° E. of Tonnie Peak, about 100ft above base of the 

Chiriitna formation. 

C. E. Kirschner, 1946. Iniskin Peninsula, 0.8 mile N. 20° E. of Front Mountain. Chinitna formation, middle third. 
8 

No. on figs. 4-9 

58 

59 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

69 

70 

71 

71 

72 

73 

74 

75 

75 

75 

76 

77 

78 

78 

79 

80 

80 

CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Localities at which ammonites were collected from the Callovian strata of southwestern Alaska-Continued 

Geolo~cal Survey eso- Collector's field numbers 

zoic locality 

20753 46AKr168 ________ 

20762 46AKr169 _______ -

- 11052 AB F63 ___________ 

11049 ABF58 ___________ 

11050 ABF59 to 6L _____ 

22427 50AHa25 _________ 

22559 50AHilO _________ 

22425 50AHa22 _________ 

22430 50AHa23 _________ 

20760 · 46AKr109 ________ 

11052a ABF68 ___________ 

3042 934b _____________ 

20759 46AKr105 ________ 

2941· ------------------

20757. 46 AKr9l _________ 

22429 50AHa20 ___ ~ _____ 

22451 50AGz18 _________ 

22452 50AGzl9 _________ 

22446 50AGziO _________ 

2920 ------------------

20755 46AKr189 ________ 

22448 50AGzl2 _________ 

22428 50AHa13 __ - ______ 

22431 50AHaL _________ 

10989 F11 ______________ 

22433 50AHa7 ____ --- ___ 

3028 929 ______________ 

22422 50AHa1L----- ___ 

22432 50AHa2 _______ -~ _ 

Collector, year of cQllcction, description of locality, and stratigraphic assignment 

C. E. Kirschner, 1946. Iniskin Peninsula, 0.75 mile N. 52° W. of Front Mountain. 

Chinitna formation, at base. 

C. E. ~irschner, 1946. Iniskin Peninsula, 0.55 mile N. 57° W. of Front Mountain. 

Chinitna formation, top of lower third. 

A. A. Baker, 1921. Iniskin Peninsula, about 0.5 mile N. 14° E. of Front Mountain. 

Chinitna formation, middle third. 

A. A. Baker, 1921. Iniskin Peninsula, about 0.8 mile N. 46° E. of Front Mountain. 

Chinitna formation, middle third. 

A. A. Baker, 1921. Iniskin Peninsula, about 0.8 mile N. 61° E. of Front Mountain. 

Chinitna formation, probably near top of middle third. 

R. W. Juhle and J. K. Hartsock, 1950. Iniskin Peninsula, east side of valley of Bowser 

Creek 0. 9 mile S. 87° W. of Front Mountain. Chinitna formation, basal sandstone. . 

David Hill, 1950. Iniskin Peninsula, 4.4 miles N. 63° w .. ·of Front Mountain: Float 

near base of Chinitna formation. 

R. W. Juhle, 1950. Iniskin Peninsula, east ~ide of valley of Bowser Creek 1.4 miles S. 

61° W. of Front Mountain. · Chinitna formation, base of middle third. 

R. W. Juhle and J. K. Hartsock, 1950. Iniskin Peninsula, 1.5 miles S. 59° W. of FJ;Qnt 

Mountain. Chinitna formation, base of middle third. 

C. E. Kirschner, 1946. Iniskin Peninsula, 1.7 miles S. 50° W. of Front Mountain. Chinitna formation, middle third. . 

A. A. Baker, 1921. Iniskin Peninsula, northeast corner of Oil Bay. Chinitna formation, 

probably near top of middle third.-

T. W. Stanton, 1904. Iniskin Peninsula, northeast shore of Oil Bay. Chinitna formation; upper part of middle third. 

C. E. Kirschner, 1946. Iniskin Peninsula, northeast corner of Oil Bay, 2.3 miles S. 44° W. 

of Front Mountain. Chinitna formation, near top of middle third. 

G. C. Martin, 1903. Iniskin Peninsula, northeast shore of Oil Bay. From 72X ft·above 

base of measured section (See Martin, 1926, p. 162). Chinitna formation, near base of 

upper third. 

C. E. Kirschner, 1946. Iniskin Peninsula, 3.5 miles S. 53° W. of Front Mountain on 

southwest side of Oil Bay. Chinitna formation, near base of upper third. 

R. Hoare, R. W .. Juhle, J. K. Hartsock, 1950. Iniskin Peninsula, west side of Oil Bay 

3.6 miles S. 53° W. of Front Mountain, Chinitna formation, near base of upper third. 

A. Grantz, 1950. Iniskin Peninsula, west of head of Oil Bay, 3.75 miles S. 55° W. of 

Front Mountain, Chinitna formation, near base of upper third. 

A. Grantz, 1950. Iniskin Peninsula, 3.8 miles S. 56° W. of Front Mountain. Chinitna 

formation, near base of upper third. 

A. Grantz, 1950. Iniskin Peninsula, 250 yd north of mouth of Keystone Creek, 5.45 

miles S. 72° W. of Front Mountain. Chinitna formation, basal beds. 

G. C. Martin, 1903. Iniskin Peninsula, east shore of Iniskin Bay. Same locality as 20755. 

Chinitna formation, near base. 

C. E. Kirschner, 1946. Iniskin Peninsula, 5.6 miles S. 72° W. of Front Mountain. Same 

as loc. 11057. Chinitna formation, near base. 

A. Grantz, 1950. Iniskin Peninsula, from mouth of Keystone Creek northward 175 yd, 

5.5 miles S. 70° W. of Front Mountain. Chinitna formation, near b~se. 

J. K. Hartsock, 1950. Iniskin Peninsula, reef between mouths of Keystone Creek and 

Pomeroy Creek, 5.6 miles S. 70° W. of Front Mountain. Chinitna formation, near 

middle of lower third. 

J. K. Hartsock, 1950. Iniskin Peninsula, from 10ft of siltstone. on beach between mouths 

of Keystone and Pomeroy Creeks· 5. 7 miles S. 69° W. of Front Mountain. Chinitna 

formation, middle of lower third. 

F. H.Moffit, 1921. Iniskin Peninsula, east shore of Iniskin Bay, south of trail to Oil Bay. 

Chinitna formation, middle third. 

J. K. Hartsock, 1950. Iniskin Peninsula, at mouth of first creek south of Pomeroy Creek, 

·5 .. 5 miles S. 69° W. of Front Mountain. Chinitna formation, middle of lower third. 

T. W. Stanton, 1904. Iniskin Peninsula, east shore of Iniskin Bay about 0.65 miles 

N. 5° W. of Mt. Pomeroy. Chinitna formation, near base of middle third. 

J. K. Hartsock, 1950. Iniskin Peninsula, talus from sea cliff 5.62 miles S. 67° W. of Front 

Mountain. Chinitna formation, lower part of rriiddle third. 

R. W. Juhle and R. D. Hoare, 1950. Iniskin Peninsula, sea cliff from 30 to 150 yd southward from Mes. loc. 22422 on east shore of Iniskin Bay. Chinitna formation, lower 

part of middle third. 
No. on figs. 4-9 

81 

82 

83 

84 

85 

86 

86 

86 

86 

87 

88 

89 

90 

91 

92 

93 

94 

95 

96 

96 

97 

98 

99 

100 

100 

101 

102 

103 

ALASKA PENINSULA AND COOK INLET REGIONS 69 

Local-iUes at which ammonites were collected from the Callovt"an strata of southwestern Alaska-Continued 

Geolo~al Survey . eso- Collector's field numbers 

zoic loca!lty 

22419 50AHa3 __________ 

22411 50AHa8 __________ 

22415 50AHa17 _________ 

22434 50AHa14 _________ 

20763 46AKr 190 ________ 

3029 929a _____________ j 

10990 F12-----~--------

10991 F13 ______________ 

10992 F14 _______________ 

2921 ------------------

22435 50AHa15 _________ 

3030 929b---------~---

11060 ABF76 ____ -------

21354 48AI113 _____ - ____ 

10818 1-126 ____________ 

3105 916 ______________ 

3106 94 7- - - - - - -- - - - - - -

3103 944 ______________ 

10824 c ________________ 

12386 F8----------~----

3104 945 ______________ 

12385 F7 _______________ 

12387 F9 _______________ 

3117 ------------------

10822 3----------------

10790 1-57 _____________ 

3113 954 ______________ 

2943 ------------------

218128-53--3 

Collector, year of collection,.description of-locality, and stratigraphic assigilment 

R. ·w. Juhle, 1950. Iniskin Peninsula, ~mile up the stream just south of Pomeroy Creek, 

5.42 miles S. 67° W. of Front Mountain. Chinitna formation, lower third. 

J. K. Hartsock, 1950. Iniskin Peninsula, float in first stream south of Pomeroy Creek, 

5.4 miles S. 67° W. of Front Mountain. Chinitna formation, lower third. 

A. Grantz, 1950. Iniskin Peninsula, north slope of Mt. Pomeroy, 5 miles S. 63° W. of 

Front Mountain, Chinitna formation, 300 ft below top. · 

A. Grantz and J. K. Hartsock, 1950. Iniskin Peninsula, 5.9 miles S. 67° W. of Front 

Mountain on east shore of Iniskin Bay. Chinitna formation, from 100 ft of siltstone 

C<~lying 200 ft below top. · · 

C. E. Kirschner, 1946. Iniskin Peninsula, east shore of Iniskin Bay, 6 miles S. 67° W. of 

Front Mountain. Chinitna formation, near top of middle third. 

T. W. Stanton, 1904. Iniskin Peninsula, east shore of Iniskin Bay, about 0.5 miles N. 65° 

W. of Mt. Pomeroy. Chinitna formation, upper part of middle third. 

F. H. Moffit, 1921. Iniskin Peninsula, east shQre of Iniskin Bay 1 mile south of trail to 

· Oil Bay, about 0.5 mile N. 65° W. of Mt. Pomeroy Chinitna formation, probably top of 

middle third. 

F. H. Moffit, 1921. Iniskin Peninsula, Float at same general location as loc. 10990. 

Chinitna formation. 

F. H. Moffit, 1921. Iniskin Peninsula, same location as 10990. Chinitna formation, 

probably top of middle third. 

G. C. Martin·, 1903. Iniskin Peninsula, ea~t shore of Iniskin Bay. Chinitna formation, 

upper 1200 ft. 

A. Grantz and J: K. Hartsock, 1950. Iniskin Peninsula, 6.25 miles S. 66° W. of Front 

Mountain on east shore of Iniskin Bay. Chinitna formation, upper 200 ft. 

T. W. Stanton, 1904. Iniskin Peninsula, east shore of Iniskin Bay about 0.9 mile S. 70° 

W. o{Mt. Pomeroy. Chinitna formation, upper 100ft of upper third. 

A. A. Baker, 1921. Iniskin Peninsula, on east shore of Iniskin Bay about 750 ft south of 

Mushroom Rocks, 1 mileS. 78° W. of Mt. Pomeroy. Chinitna fo.;.·mation, upper third, 

at very top. · 

R. W. lip.lay and D. J. Miller, 1948. Puale BaY<, sea cliff on northeast shore, 2,400 to 

2,600 ft north\\ est of mouth of Portag~ Creek, interbeds of hard gray siltstone· near top 

of sandstone mPmber and about 2,200 ft below the top of the Shelikof formation. 

S. R. Capps, 1921. Puale Bay, northeast shore, 4 miles northwest of mouth of bay. 

Shelikofformation, middle member. · 

T. W. Stanton and R. W. Stone, 1904. Puale Bay, northeast shore about 4 miles northwest of Cape Kekurnoi. From thin bed at top of 200 ft of dark shale in Shelikof formation, middle member. 

T. W. Stanton and R. W. Stone, 1904. Puale Bay,· northeast shore about 3 miles northwest of Cape Kekurnoi. Shellkof formation, tower member. 

T. W. Stanton, 1904. Puale Bay, west shore about~ mile w~thin entrance to bay. Shelikof formation, middle member. 

S. R. Capps, 1921. Puale Bay, southwest shore. Shelikof formation. 

W. R. Smith, 1924. Alaskan Peninsula, ,southwest side of Puale Bay. Same locality 

as 10824. Shelikof formation. 

T. W. Stanton, 1904. Puale Bay, west shore near Cape Aklek. Shelikof formation, 

middle member, from conglomerate .100 ft above base of section (See Martin, 1926, 

p. 198). 

W. R. Smith, 1924. Alaskan Peninsula, head of Oil Creek: Shelikof formation, upper 

member. 

W. R. Smith, 1924. ·Alaskan Peninsula, Puale Bay area, n.:lar summit of hill 1~ miles 

southwest of head of bay. Shelikof formation. 

R. W. Stone, 1904. Puale Bay, southwest side, near head of small creek near Cape Aklek. 

Shelikof formation, middle member. 

S. R. Capps, 1921.· Puale Bay, southwest side, head of small creek near Cape Aklek. 

Shelikof formation, middle member. 

S. R. Capps, ·1921. Puale Bay area, about 3Yz miles above mouth of Rex Creek, Alaskan 

Peninsula. Shellkof for-mation. 

T. W. Stanton, 1904. Four miles west of Puale Bay on west side of Oil Creek, Yz mile 

above its mouth and at an elevation· of 500 ft above· the creek. Shelikof formation, 

middle member. 

G. C. Martin, 1903. Kanatak area, Dry Bay, near mouth of Oil Creek, Alaskan Peninsula. 

Shelikof formation, middle member. 
70 

No. on figs. 4-9 

104 

105 

106 

107 

108 

109 

110 

111 

112 

113 

114 

CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Localities at which ammonites we~e collected from the Callovian strata of southwestern Alaska-Continued 

Oeolo~cal Survey eso- zoic locality 

Collector's field numbers 

12382 F4------------~--

12384 F6 _______________ 

12381 F3 _______________ 

12411 F33 ______________ 

12380 F2 _______________ 

10803 1-101 ____________ 

12398 F20----------~---

19902 45AKmF92'" ______ 

19911 45AKmF10L _____ 

10805 1-105 ____________ 

21357 48AI94 ___________ 

.Collector, year or collection, description of locality, and stratigraphic assignment 

W. R. Smith, 1924. Alaskan Peninsula, Salmon Creek in draw east of. large seepage, 

Kanatak area. Shelikof formation. 

W. R. Smith, 1924 .. Alaskan Peninsula, Salmon Creek in draw east of large seepage, 

Kanatak area. Shelikof formation from beds lower than loc. 12382. 

W. R. Smith, 1924. Alaskan Peninsula, Salmon Creek-just above large oil seepage, Kanatak area. Shelikof formation. · 

W .. R. Smith; 1924. Alaskan Peninsula, large draw near crest of dome on -Balmon Creek 

in Kanatak area. Shelikof formation. 

W. R. Smith, 1924. Alaskan Peninsula, East branch of Kanatak Creek, !.mile north of 

Kanatak. Shelikof formation. 

S. R. Capps, 1921. Wide Bay near point 1Yz miles south of mouth of Big Creek. Shelikof 

formation, lower member. 

W. R. Smith, 1924. Alaskan Peninsula, Wide Bay area, 1~ miles up west branch of Des 

Moines (Lee) Creek. Shelikof formation, lower member. 

L. B. Kellum, 1945. Alaskan Peninsula, Wide Bay area, 5.2 miles N. 32° W. of west end 

of Hartman Island, Float near elevation of 478ft in Shelikof formation. 

L. B. Kellum; 1945, Alaskan.Peninsula, Wide Bay area, 1.0 mile N. 64%0 E. of Mt. Shannon 

at elevation of 412 ft in Shelikof formation. 

S. R. Capps, 1921. Wide Bay, about 1 mile west of mouth of Pass Creek. Shelikof 

formation, lower member. 

R. W. Imlay and D. J. Miller, 1948. Wide Bay area, on divide at head of stream entering 

Short Creek about 1 mile northwest of beach, 5.37 miles N. 68%0 W. of w_est end of 

Hartman Island. Siltstone about 40 ft below base of sandstone. sequence and about 

1,140 ft above the base of the Shelikof formation. 

115 21356 48AI93 ___________ R. W. Imlay and D. J. Miller, 1948. WideBay area, near head of tributary entering 

Short Creek about 1 mile northwest of beach, 5.2 miles N. 70° W. of west end of Hartman 

Island about 1,100 ft above the base of the Shelikof formation. 

116 19744 44AKmF5 ________ ~.B. Kellum, 1944. Alaskan Peninsula, Wide Bay area, first gully that enters Short Creek 

from north about% mile above junction at elevation of 950ft. Float about 660ft above 

base of Shelikof formation. 

117 21355 48AI92 ___________ R. W. Imlay and D. J. Miller, 1948. Wide Bay area, tributary entering Short Creek 

118 11072 

119 19781 

120 21360 

121 21359 

122 21358 

123 10813 

124 10812 

125 19793 

126 12407 

127 12408 

128 19873 

M5 ______________ 

44AKmF5L ______ 

48AI99 ___________ 

48AI98--------~-~ 

48AI97 ___________ 

1-117 ____________ 

1-116 ____________ 

44AKmF63 _______ 

F29 ______________ 

F30 ______________ 

F66------~--~----

about 1 mile northwest of beach, 5.05 miles N. 72° W. of west end of Hartman Island. 

From base of abundant limestone concretions in gray siltstone about 350 ft above base 

of Shelikof formation. 

Ernest Marquardt, 1921. Wide Bay, about 3 miles northwest of shore on creek that 

empties into bay 4 miles southwest of .mouth of Des Moines (Lee) Creek. Shelikof 

formation, probably base of middle member. · · · 

L. B. Kellum, 1944. Alaskan Peninsula, Wide Bay area, 7.2 miles N. 82~ 0 W. of west end 

of Hartman Island, 1500 ft above base of Shelikof formation. 

R. W. Imlay and D. J. Miller, 1948. Wide Bay area, southwest face of mountain front on 

northwest side of bay, 6.70 miles N. 96° W. of west end of Hartman Island, limestone 

concretions in siltstone about 1,600 ft above base of the Shelikof formation. 

R. W. Imlay and D. J. Miller, 1948. Wide Bay area, southwest. face of mountain front 

on northwest side ofbay, 6.61 miles N. 97° W. of west end of Hartman Island, limestone 

concretions in siltstone about 1,400 ft above the base of the Shelikof formation. 

R. W. Imlay and D. J. Miller, 1948. Wide Bay area, southwest face of mountain front 

6.60 miles N. 97%0 W. of west end of Hartman Island, Gray siltstone 20 to 40 ft below 

the :first.prominent sandstone bed at this place·and about 1,000 ft above the base of 

the Shelikof formation. 

S. R. Capps, 1921. Same locality as 10812 but higher in the section. Shelikof formation. 

S. R. Capps, 1921. Wide Bay area, near head of creek that enters Wide Bay from northwest 

at sout.hwest end of bay. Shelikof formation, probably base of middle member. 

S. N. Daviess, 1944. Alaskan Peninsula, Wide Bay area, 2.6 miles N. 59° E. of Mt. Alai, 

500 ft above base of Shelikof formation. 

W. R. Smith,,1924. Alaskan Peninsula, Wide Bay, southwest side, near summit of Lone 

Hill. Shelikof formation, lower member. 

W. R. Smith, 1924. Alaskan Peninsula, southwest side of Wide Bay on south side of 

Lone Hill. Shelikof formation, lower membe·r. 

L. B. Kellum, 1945. Alaskan Peninsula, Wide Bay area, 4.4 miles S. 67~ 0 E. of Mt. Alai 

at elevation of 985ft. Shelikof formation, 1,080 ft above base. 
ALASKA ·PENINSULA AND COOK INLET REGIONS 11 

LocaliUes at which ammonites were collected from the Callovian t>trata of southwestern Alaska-Continued 

No. on. Oeoloi\:cal Survey eso· Collector's field numbers Collector, year of collection, description of locality, and stratigraphic assignment figs. 4-9 zoic locality 

129 19896 

• 

130 21362 

45AKmF86. ______ 

48AI102 __________ 

-

J. Friedman and L. B. Kellum; 1945, Alaskan Peninsula, Wide Bay area, 7.4 miles S. 

54° W. of west end of Hartman Island at elevation of 289 ft, and 330ft above base of 

Shelikof formation. 

R. W. Imlay and D. J. Miller, 1948. Wide Bay area, Talus blocks and outcrops along 

sea cliff on southeast side of Wide Bay from a point 4.20 miles S. 39° W. of west end of 

Hartman Island northeastward along beach to ~nd of peninsula. Fossils occur in 

limestone concretions forming part. of a coarse conglomerate f~om 5 to 45 ··ft above the 

top of the lower siltstone member of the Shelikof formation. 

131 21361- 48AI10L _________ R. W. Imlay and D: J. Miller, 1948. Wide Bay area, sea cliff on southeast shore, 3.60 

to 3.70 miles S. 34° W. of west end of Hartman Island. Hard, gray, siltstone 15 to 25 

ft below base of Ir).assive sandstone and conglomerate and in top of lower siltstone 

member of Shelikof formation. 

none 1496 ------------------ D. F. Be9ker and W. H. Dall, 1895. Northeast side of Puale Bay, Alaskan Peninsula, 

Shelikof formation. 

n~me 1.497 ------------------ C. W. Purington, 1895. Puale Bay from first bench on high ridge west of stream that 

drains into northeast end of Puale Bay. Shelikof formation, upper member. 

none 2707 ---------------~-- A. H. Brooks, 1901. Iniskin Bay, near entrance to Cook Inlet. Chinitna formation. 

none 10814 1-118 ____________ S. R. Capps, 1921. 'Vide Bay, north shore, about 4 miles from .its southwest end. Loose 

boulder derived from the Shelikof formation. 

none 22132 81 _______________ Wm. J. Fisher, about 1900. From Wide Bay area of Alaskan Peninsula. Shelikof 

formation. 

1. 

2. 

SUMMARY OF RESULTS 3. 

The de$cribed Callovian ammonites :from the Alaskan Peninsula and Cook Inlet regions include 19 

genera and 62 species. Of these, 1 subgenus, Stenocadoceras, and 38 species are new. Tl;le genus Oadoceras comprises 61 percent and the genus Pseudocadoceras 17 percent o:f the total number of 

ammonite specimens :found. Paraca¢oceras and 

Stenocadoceras_ are considered subgenera of Oado-

·ceras. Of especial intere13t are the occurrences in the 

lower part of the Callovian sequence. of such ammonites ·as /{heraiceras, Xenocephalites, Lilloettia, 

Paracadoceras, Gulielmiceras, Gowericeras, Procerites, and Reineckeia ( K ellawaysites). 

The exact stratigraphic positions :of the· :fossil col- · 

lectionshave been difficult to ascertain because of the 

tho.usands of :feet of Callovian sedimentary rocks 

that are present, the lack of distinctive, persistent 

marker beds, and the probability that locally considerable thicknesses have been removed during late 

Callovian time prior to the deposition of the Naknek 

formation. The presence o:f a middle sandstone 

member within the Sheliko:f :formation is of· some 

aid stratigraphically, although this member appears 4. 

to grade laterally as well as vertically into the adjoining siltstone members~ As :for the· Chinitna :formation, the :fossil collections can readily be localized · 

within the lower, middle, or upper thirds and some 

collections can be localized within a certain number 

of :feet of the boundaries o:f the :formation. 

The lower third of the Chinitna :formation is 

characterized by Oadoceras, Par.acadoceras, Kepplerites, Lilloettia, X enocephalites, Kheraiceras, 

Gowericeras, Gulielmiceras, Procerites and G_rossouvria .. The last three have been :found only within 

a few hundred :feet of the base of th~ :formation. 

Kepp·lerites tychonis Ravn was :found near the base 

on Chisik Island. 

The middle third o:f the Chinitna formation contains commonly Phylloceras, Oppelia ( Owycerites), 

Lilloettia, Oadoceras, -Pseudocadoceras, and Kepplerites. Near the lower part o:f the middle third 

these may be associated with Kheraiceras, Xeno~ 

cephalites, P arctcailoceras, and Gow~riceras. Pseudocadoceras grewingki (Pompeckj) is the most common :fossil in the middle third, although it ranges 

higher. 

The upper third of the. Chinitna :formation contains the ammonites Phylloceras, Oadoceras, 0. 

( Stenocadoceras), Pseudocadoceras, and Lilloettia. 

The latter occurs rarely. Stenoc(l(ioceras and 

Pseudocadocera8 are the most common . ammonites. 

Faunally the lower siltstone member .of the Sheliko:f :formation is correlated with approximately the 

lower third o:f the Chinitna :formation and the middle 

sandstone member is correlated with the middle third 

o:f the Chinitna. The upper siltstone member of the 

~ Sheliko:f has not :furnished ammonites, except possibly at one locality. 
72 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

5. The Chinitna and Shelikof formations are correlated with the lower and middle parts of the Callovian stage,- corresponding to the northwest European zones of Proplanulites koenigi to Erymnoceras 

coronatum. This correlation is based on comparisons of the ammonites of these formations with the. 

Callovian ammonites from the western interior of 

the United States, from East Greenland, from the 

Barents Sea area, and from northern Europe. The 

basal Callovian zone of M acrocephalites '11UUJrocephalus has not be~n identified faunally, although 

possibly represented locally by a basal shelly sandstone. Likewise, the highest European zones of the· 

Callovian have not been identified faunally but are 

probably represented by an unconformity at the base 

of the Naknek formation. 

6. The lower siltstone member of the Shelikof formation and the lower third of the Chinitna formation are correlated with the zones of Proplanulites 

koenigi and the lower part of the zone of Sigaloceras calloviense on' the basis of the presence of such 

ammonites as Gowericeras, Paracadoceras, Gulielmiceras, and K epplerites tychonis Ra vn. Similar or 

identical species occur in the upper part of the lower 

Callovian sequence in Montana and East Greenland. 

7. The middle sandstone member of the Shelikof 

formation and the middle third of the Chinitna formation are correlated with the upper part of the zone 

of Sigaloceras calloviense and with the zone of Oosmoceras jason (1) on-~he basis of superposition, (2) 

because of the association of Gowericeras,_ Paracadoceras, and Pseudocadoceras in tl}e lower part of the 

middle third of the Chinitna, (3) because of -the 

abundance of Pseudocadoceras throughout, and ( 4) . 

because the species of Oadoceras and Kepplerites are 

quite distinct from those in Montana and in East 

Greenland. 

8. · The upper third of the Chinitna formation is 

correlated with the European z9ne of Erymnoceras 

coronatum- because of the abundance of compressed 

Oadoceras (Stenocadoceras) similar to forms in cen- · 

tral Russia, because Pseudocadoceras is not known 

to range- higher, and because the absence of many 

genera that are common lower in the Chinitna formation implies a fairly high position in the 

Callovian. 

. 9. It seems likely that the Callovian sediments of the 

Alaska Peninsula and Cook Inlet areas were deposited along a steep slope fronting a major ocean and 

were derived from mountains that lay immediately 

to the north or northwest. An ample source of sedimentary material and rapid subsidence is implied 

by thicknesses ranging from 4,000 to 6,000 ft. Locally the sea bottom was subjected to strong wave 

and current action, although most of the siltstones 

appear to have been deposited below wave base. 

Such distinctive shallow water forms as M eleagrinella and 0 strea are lacking, except in the basal shelly 

sandstone of the Chinitna formation. The association of the thin-shelled Phylloceras with the thick-

. er-shelled cardioceratids suggests fairly deep waters 

near shore. · The presence of Phylloceras and the absence of nautiloids is probably related to depth• of 

water rather than to temperature, as the opposite 

faunal condition exists iii the Callovian deposits of 

the western interior of the United States. A 'cooling of the boreal sea of Late Jurassic time, as compared to seas farther south is suggested by the absence of corals, the rarity of gryphaeas and exogyras, 

the provincial character of the ammonites, the poverty in molluscan genera and species as compared 

with the Mediterranean seas, and by the scarcity of 

calcium ca:.;bonate other than as concretions. 

SYSTEMATIC DESCRIPTIONS 

Genus Phylloceras Suess 1865 

Subgenus Phylloceras, sensu stricto 

Phylloceras bakeri Imlay, n. sp. 

Plate 25, figures 10, 14 

The species is represented by six specimens .. .lform 

discoidal, compressed; whorls elliptical, much higher 

than wide, widest near the middle of the flanks; flanks 

slightly convex; venter highly arched. Umbilicus 

very narrow ; wall low, vertical at base, rounding 

rapidly into flanks. :Body chamber incomplete; represents one-fourth of outer whorl of holotype. 

The ornanientat~on consists of slightly flexuous ribs 

that. ·incline forw·ard nipderately on the flanks and 

arch forward on the venter. They are fine and threadlike near the umbiFcus, but widen considerably ventrally. On the upper parts of the flanks and on the 

venter they- are broad, nearly flat-topped, have steep 

anterior and posterior margins, and are separated by 

much narrower interspaces. On the middle· parts of 

the flanks are many low, broad radial folds that include 

from three to five ribs. 

The suture line is imperfectly preserved. 

Measurements cannot be made as all the specimens 

are partly crushed, but the proportions are probably 

about the same a~ on Oalliphyllocerasfreibrocki Imlay. 

This species is characterized by broad, nearly flattopped ribs on the venter and upper part of the flanks~ 

. Otherwise its ornamentation agrees with that of the 

group of species related to Phylloceras heterophyllwm 

( J. Sower by), as discussed by N eumayr ( 1871, pp. 308-

321). 

This species is named in honor of Arthur A. Baker of 

the Geological Survey, who collected the holotype. 

Holotype, U.S.N.M. 108004; paratype, U.S.N.M. 

108005. 
Mat&· I nuska Tuxedn!Bay Chillitna Bay 

Table B.-Geographic DiBt~"bu.tion of Callovian Ammonitu From Alaska Penimula and Cook Inlet Region& 

[Numbers from 1-131 refer to numbers ou figs. 4-0. Hlgber numbers are Geolo(icaJ Survey M~lc locality numbecs] 

Cook lnlct region 

Central and southwestern parts or Iniskln Peninsula 

Chinitna formation 

Alaska Peninsula region 

Puale Bay to Port&ie Bay Wide Bay 

Sbelikof formation 

218128-52 (Faces p. 72) 
ALASKA PENINSULA AND COOK INLET REGIONS 73 

Chinitna formation, upper part of upper third, 

U.S.G.S. Mes.locs. 2990, 10997,21347,21777,21778, and 

22554. 

Subgenus Calliphylloceras Spath 1927 

Phylloceras (Calliphylloceras) freibrocki Imlay, n. sp. 

Plate 26, :figur~s 7-11 

The species is represented by 10 specimens. Form 

discoidal, compressed; whorls elliptical, much higher 

than wide, widest near middle of flanks; flanks slightly 

convex; venter highly arched. Umbilicus extremely 

narrow ; wall low, vertical, rounding rather abruptly 

into flanks. Body chamber unknown. 

The ornamentation consists of pronounced flexuous 

constrictions and fine ribbing. Both constrictions and 

ribbing incline forward moderately on the lower part 

of the flanks, recurve slightly on the upper part of the 

flanks, a.nd then arch forward strongly on the venter. 

There are .7 constrictions .on the small specimens and 

8 or 9 constrictions on the largest specimens. Constrictions are not visible where the shell is preserved. The 

ribs have a short, steep anterior slope, a long, gentle 

posterio~· slope, and a sharp crest. They are scarcely 

stronger than striae near the umbilicus but become a 

little stronger ventrally. 

The suture line is typical of Oalliphylloceras. The 

saddles and lobes are about equal in width. ·The external saddle is bifid and the first and second lateral saddles tend to be trifid. 

The dimensions in millimeters and ratios of w hor 1 

height and thickness to the diameter are as follows : 2 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Pnratype (pl. 26, figs. 8, 9) ___________ 51 26(0. 51) 20 (0.39) ? 

Do ----------.. -.. -----... -.......... -... ----- 66 36( .54) 28 ( .42) 7(0.10) 

Holotypo (pl. 26, flg.lO) _____________ 166 94( . 57) 58?( . 34) ? 

2 In tho following page~ this statement will be abbreviated to "Dimensions in 

milllmotors and ratios arc as follows": 

This species resembles Oalliphylloceras demidoffi 

(Rousseau) (see Loczy, 1915, p. 291, pl. 1, fig.' 2, pl. 2, 

figs. 3-5, pl. 3, fig. 1; Arkell, 1939, p. 141) in number 

of constrictio~s and in ornamentation. It appears to 

have flatter flanks, a broader venter, and wider saddles. 

This species is named in honor of Mr. Eric Freibrock, 

owner of the Snug Harbor Cannery, who has kindly 

helped members of the Geological Survey on many 

occasions. 

Holotype, U.S.N.M. 108006; paratypes,. U.S.N.M. 

108007, 108008. 

Chinitna formation, lo~er two-thirds, U.S.G.S. Mes. 

locs. 2941, 3015, 11'047, 20763, 21286, 21287, 22427, and 

22456. Shelikof formation, base of middle member, 

Mes. loc. 3104. 

Subgenus Partschiceras Fucini 1923 

Phylloceras (Partschiceras) subobtusiforme Pompeckj 

Plate 25, figures 1-3, 8 

Phylloceras S1tbobtusiforrne Pompeckj, Russ. K. Min. Gesell. St. 

Petersburg Verb., ser. 2, Band 38, p. 247, pl. 7,. figs. la-d, 1900. 

Four specimens of this species are available. Form 

small, discoidal, moderately stout; whorls subovate, 

higher than wide, widest at' about two-thirds of the 

height of the flanks ; flanks flattened in lower part and 

diverging slightly, rounding rapidly above into rather 

broad venter. Umbilicus very narrow; wall steeply 

inclined, rounding evenly into flanks. Body chamber 

represented by at least three-fifths of a whorl. Aper 

ture unknown. 

The ornamentation of the outer whorls consist of 

fine growth lines or ~striae on the lower parts of the 

flanks that. pass into low, rounded ribs on the upper 

parts of the flanks. The growth lines are radial near 

the umbilicus and strongly inclined forward on the 

flanks. The ribs incline forward slightly on the upper 

parts of the flanks and arch forward gently on the 

venter. They are about as wide as the interspaces. 

. The suture line as illustrated h~;rein has a longer 

external lobe th~n on the type of . the species and the 

saddles are a little wider. 

The dimensions in millimeters ·and ratios of the diameter are as follows: 

Diame- Whorl ter height Specimen Whorl 

thickness 

Holotype ______________________________________ _ 17 

30 

11. 5(0. 68) 8(0. 47) 

Plesiotype (pl. 25, figs. 2, 3). ___________________ _ 18 ( .60) 14( .47) 

Pompeckj .( 1900, p. 249) notes that this species is 

distinguished from Phylloceras subobt'tisum Kudernatsch (1852, p. 7, pl. 2, figs. 1-3), from the Bathonian 

of Europe, by the forward arching of the ribs on 

the venter and by a simpler suture line. It is also much 

stouter. P. chantrei Munier-Chalmas (see Sayn and 

Roman, 1930, p. 216, pl. 21, figs. 11, 11a, text fig. 33), 

from the Callovian and Oxfordian of Europe, is even 

more compressed than P. subobt'IMum. 

Plesiotypes, U.S.N.M. 108009-108011. 

Chinitna formation, middle two-thirds, U.S.G.S. Mes. 

locs. 3029, 21348, 22411, and 22434. 

Phylloceras (Partschiceras) grantzi Imlay, n. sp. 

Plate 25, figures 4-7, 9 

~he species is represented by two specimens. Form 

small, ·discoidal, fairly stout; whorls subquadrate 

higher than wide, widest near the middle of the flanks~ ~anks ' flattened and nearly .parallel, rounding rapidly 

Into rather broad venter. Umbilicus very narrow wall 

steeply inclined, rounding evenly into flanks. Body 
74 CALLOVIAN (JURASSIC) AMMONITES FROM. THE UNITED STATES AND ALASKA 

. - chamber represented by about two-thirds of a whorl. 

Aperture sigmoid, strongly inclined forward, bordered 

on internal mold by a constriction which is followed 

by a weak swelling. 

. The ornamentation of .the body whor:l consists of fine, 

flexuous, forwardly inclined growth lines on the flanks 

and of low, broad, forwardly arched ribs on the venter. 

The. ventral· ribs. are a little narrower than the interspaces, are . variable in strength, and become broader 

and stronger anteriorly. 

, The suture line is essentially the same as in P. sUbobtusiform.e Pompeckj. 

,. The dimensions in millimeters and ratios of the diametEir· are as follows : 

Specimen Diame- Whorl Whorl ter height thickness 

,Holotype (pl. 25, figs. 4, 5) _______________________ _ 27 16(0. 59) 12. 5(0. 46) Do __________ -------- ________________________ _ 39 23( . 59) 16 ( . 41) 

Paratype (pl. 25, figs. 6, 7) _______________________ _ 47 29( .61) 20 ( .42) 

. This species differs from P. subobtusiforme PompecKj by its ribbing, which appears at a later growth 

~tage, is confined to the venter, and is much coarser. 

. This species is named in honor of Arthur Grantz, ge-· 

ologist with the Geological Survey, who has studied the 

Jurassic rocks of the Cook Inlet region. 

Holotype, U.S.N."J_\1. 108012;. paratype, U.S.N.M. 

108013. 

Chinitna formation, middle third, U.S.G.S. Mes. loc. 

22432. 

Subgenus Macrophylloceras Spath 1927 

Phylloceras (Macrophylloceras) grossicostatum Imlay, n. sp. 

Plate 25, figures 11-13, 15, 16 

Six_specimen~ .of this species are·known. Form discoidal, compressed; whorls elliptical, much higher than 

wide, widest near the middle of the flanks; flanks gently 

convex; venter highly arched. Umbilicus extremely 

narrow; wall very low, vertical at base, romiding evenly 

into flanks. Body chamber unknown. 

. Fine, gently flexuous ribbing is barely visible at a 

diameter of 26 mm. ~his ribbing i~ scarcely stronger 

than striae near the umbilicus, ·becom~s a little stronger 

ventrally an.d persists to a diameter of about 60 mm. 

In addition, at a diameter of about 30 mm some broad, 

low, widely spaced fold-like ribs appear on the upper 

two-thirds. of the flanks. These ribs curve forward 

· near the middle of the flanks, but recurve higher on the 

flanks and cross· the venter tr.ansversely. They tend to 

fade out on the venter at diameters less than about 60 

mm but at greater diameters are as strong on the venter 

as on the flanks. Anteriorly these ribs become .:fairly 

prominent and are separated by broad flat interspaces. 

Most o:f these ribs are separated at diameters greater 

than 60 ~ by short ribs that do not extend below the 

upper fifth of the flanks but are as strong on the ve1i.ter 

as the long ribs. 

The suture line shows the high external lobe characteristic of Macrophylloceras. The saddles are a little 

stouter than the lobes. The external saddle is bifid and 

the first lateral saddle is nearly trifid. 

Accurate measurements o:f the holotype cannot be 

made owing to crushing. The paratype shown on plate 

25, figures 12 and 13, at a diameter o:f 59 mm has a whorl 

height of 36 mm and a whorl thickness o:f 23 mm. 

The. ribbing o:f this species resembles that o:f the Cretaceous Phyllopachyceras Spath (1927; p. 36; D'Orbigny, 1842, pl. 39, figs. 4, 5) ·more than· that o:f the. 

Jurassic Macrophylloceras Spath (1927, p. 36.; Zittel, 

1868, ·p. 68, pl. 7, figs. 3, 4), but the high external lobe is 

quite different from that of Phyllopachyceras. 

Holotype, U.S.N.M. 108014; paratypes, U.S.N.M. 

108015-108017. 

Chinitna :formation, lower two-thirds, U.S.G.S. MAQ 

locs. 2921, 3015, 3029, 11047, 22442, and 22448 . 

Genus Oppelia Waagen 1869 

Subgenus Oxycerites Rollier 1909 

Oppelia (Oxycerites) chinitnana Imlay, n .. sp . 

Plate 26, figures 3-6 

This species is represented ·:for certain only by the 

holotype. Shell fla~tened, discoidal; outer whorl 

wedge-shaped in section, much higher than wide almost completely embracing preceding whorl, thickest 

a little below middle o:f flanks; flanks nearly flat in 

lower half; gently convex in upper half; venter bearing blunt keel. Umbilicus very narrow; wall low and 

vertical, rounding abruptly into flanks. Body chamber represented by hal£ a whorl. Aperture imperfectly· 

preserved, but the character of the ribbing suggests the 

presence o:f long lateral lappets. 

The ornamentation consists o:f striae on the lower 

part o:f the flanks, o:f low, broad ribs on the upper part 

o:f the flanks, and o:f a :faint spiral groove slightly above 

the middle o:f the ·flanks. The striae and ribs together 

:form sickles that are strongly inflected :forward along 

the spiral groove and become increasingly more inflected anteriorly. The ribs are barely visible on the 

septate posterior p·art of the body whorl but become 

stronger rapidly on the body chamber. They curve 

:forward sharply on .the venter and then disappear, resulting in a smooth area between their terminations and 

the keel. There are about 20 ribs on the body chamber. 

The suture line has rather broad lobes and saddles. 

The first lateral lobe is shorter than the external lobe. 

The second lateral lobe is nearly as wide as the first 

lateral lobe but much shorter. 

The holotype at a ·diameter of 63 mm has· a whorl 

height o:f 35 mm, a whorl thickness o:f 11.5 mm, and an 

umbilical width o:f 5 mm. 

~'..'· 'I 
') 

ALASKA PENINSULA AND COOK INLET REGIONS 75 

The species is characterized by the sickle-like ribbing 

on its body chamber and by its very narrow umbilicus. 

None of the described European species of Owycerites 

bears a close resemblance. ' 

Holotype, U.S.N.M. 108018. 

Chinitna formation, middle third, U.S.G.S. Mes. loc. 

3029. 

Oppelia (Oxycerites) sp. 

Plate 26, figures 1, 2 

near the middle of the flank into two stronger secondary 

ribs. Between most successive pairs of forked ribs is 

an intercalated rib. At diameters greater than 60 mm 

effacement of the ribs begins near the umbilicus and 

during growth gradually spreads ventrally. On the 

anterior part of the penultimate whorl the' lower half of 

the flanks is quite smooth but the ventral ribs are still 

fairly strorig and persist onto .the posterior third of the 

body whorl. The anterior two-thirds of the body 

whorl is fairly smooth, bearing faint striae on the flanks 

and broad indistinct ribs on the venter. 

The suture line is not well exposed on the larger · 

Alaskan specimens. On one immature specimen the 

first lateral lobe is about the same length as the external 

lobe. The saddles are nearly symmetrical and a little 

wider than the lobes. 

The dimensions in millimeters and ratios of the diameter are as follows.: 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype _________ ------- ____________ 102 47(0. 46) 70(0.68) 6?(0.06) 

Plesiotype (pl. 27, figs. 7, 9) __________ 86 46( .53) 59{ • 68) 4 ( .04) 

Do _________ ------------- _________ 106 56( • 53) 62( .58) 5 ( .05) 

Plesiotype (pl. 27, fig.!) _____________ 98 52( . 53) 62{ .63) . 4 ( . 04) 

Most of the Callovian oppelids in the Alaskan collections are fairly smooth, or exhibit feeble striae and i'ibs 

only under oblique lighting. The smooth forms are 

possibly comparable to 0. callo'lliensis Parona and Bonarelli (1897, p. 127, pl. 2, fig. 5; Corroy, 1932, p. 94, 

pl. 6, fig. 10). Some small, feebly ribbed forms possibly 

represent the inner whorls of 0. chinitnana just described. However, six specimens at diameters greater 

than 45 mm differ from 0. chinitnana by having feebler 

and more widely spaced ribbing on the upper part of 

the flanks. Their general ap.pearance is similar to that 

of Oppelia ( Owycerites) aspidoides (Oppel) (1862, 

p. 147, pl. 47, figs. 4a, b), and particularly to the forms 

figured by J. Roemer (1911, pl. 4, figs. 1-6, pl. 6, figs. 

1-4, pl. 10, figs. 6-9). The latter appear to be a little 

more inflated and to have a slightly wider umbilicus. 

0. tilli Loczy ( 1915, p. 342, pl. 16, ( 4), figs. 2-4) is like- This species has the coarsest ribbing of any described . , fo.rm of Lilloettia and 1"s second only to L. mille-: Imlay wise very similar except for a slightly wider umbilicus. ' (I in amount of inflation. It is easily distinguished from The suture line of one of the Alaskan specimens is similar to that of 0. aspidoides (Oppel) except that it is the latter by its much coarser ribbing. Comparison of 

less. frilled and the second lateral lobe is much shorter. · the Alaskan specimens of L. buckmani with the haloFigured specimens, U.S.N.M. 1o8019. type shows that the latter is about average for the 

species as regards strength of ribbing and inflation .. Chinitna formation, lower two-thirds, U.S.G.S. Mes. Comparison of the inner whorls of L. buckmani with 

locs. 3020, 3028, 20760, 21337, and 21349. Shelikof for- similarly coarsely ribbed inner whorls of Arctocephrtmation, lower member, Mes.loc. 21358. l' (S . h 9 2 1 fi 3 4 1 fi I 12 fi 

Genus Lilloettia Crickmay 1930 

Lilloettia buckmani (Crickmay) 

Plate 27, figures 1-9 

·· Buckinaniceras buckmani Crickmay, Canada Nat. Mus. Bull. 63, 

. p. 62, pl. 20, figs. 1-4, text fig. 7, 1930. 

This species is. represented by 21 specimens. Form 

stout; whorls depressed, wider than high, widest at top 

of lower third of flanks except at anterior end of body 

chamber where the greatest width is near the umbilicus, 

embr·acing almost completely; flanks and venter evenly 

convex. Umbilicus extremely small; wall fairly low, 

vertical at base, rounding evenly into flanks except near 

aperture~ Body chamber represented by about fivesixths of a whorl, aperture curved strongly forward. 

The ornamentation consists of prominent, flexuous 

ribs that are particularly strong and wide on the venter. 

On the internal whorls at diameters less than about 60 

mm the primary ribs are narrow, prominent, anq divide 

ztes pat , 1 3 , p . 6, gs. , , p . 8, g. 2, p . , g. 

2, pl. 15, figs. 2a, b, pl. 16, figs. 1a, b; Newton and Teall, 

1897, pl. 40, figs. 2a, b) shows that the latter may be dis-. 

tinguished from Lilloettia by less flexuous ribbing, by 

fewer se~ondary ribs that do iwt become thickened ventrally until a much larger size is attained, and by a consistently larger umbilicus: 

Plesiotypes, U.S.N.M. 108021.:...108025, 108026a, b. 

Chinitna formation, U.S.G.S. Mes. locs. 2921, 3029, 

21322, 21332, 21333, and 22556. Shelikof formation, 

· middle member at Mes. locs. 19781, 19896, 19902, 21359, 

21360, and 21362. 

Lilloettia milleri Imlay, n. sp. 

Plate 28, figures 11, 13-15; plate 29, figures 14, 15 

This species is based mainly ·on two complete specimens, of which one has been broken down in order to 

study the inner whorls. Form globose; whorls depressed, much wider . than high, widest at the top of 

the lower fourth of the flanks, becoming a little higher 
76 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

during growth, embracing nearly completely; flanks and 

venter evenly convex except. at extreme anterior end of 

body chamber where the venter tends to flatten. Umbilicus extremely small, wall fairly low, vertical at 

base, round~ng evenly into flanks on inner wh~rls, 

rounding abruptly into flanks on outer whorls. Body 

chamber represented by about three-fourths of a whorl. 

Aperture curved strongly forward, anterior extremity 

~ truncated on flanks, bent down on the venter; internal 

mold marked by a broad constriction followed by a _ 

weak swelling that is not apparent where the shell is 

preserved. 

The ornamentation of the broken paratype at a diameter of about 50 mm consists ·of low,. broadly rounded 

ribs that begin low on the flanks and are separated by 

narrower interspaees. During growth the ribs become 

lower, irregular in strength, bifurcate indistinctly at 

about the top of the lower third of the flanks, and tend 

to become effaced on the flanks. The adult body chamber is nearly smooth, but under oblique lighting shows 

faint forwardly curved riblets that are a little stronger 

on the venter than on the flanks. 

One srriall specimen from the Chinitna formation, 

shown on plate 28, figures 11, 14, probably represents 

the inner whorls of L. milleri because it agrees closely 

as regards ornamentation and inflation with the innermost exposed whorls of the paratype just described. 

The ornamentation of this small specimen presents an 

interesting contrast with that of similar small inner 

whorls of Arctooephalites from the western interior of 

Canada (Buckman, 1929, pl. 1, figs. 4-7, pl. 3) and 

from east Greenland (Spath, 1932, pl. 4, figs. 7 a--c, pl. 

6, fig. 3, pl. 9, figs. 3a, b, pl. 15, figs. 2a, b) in which 

the ribs are high and thin even on the venter and h!tve 

nearly vertical sides. In contrast, on the inner whorls 

of Lilloettia the ribs are generally low on the flanks, 

are thick and rounded on the venter, and have sloping 

sides. 

The dimensions in millimeters and ratios of the 

diameter are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Para type (pl. 29, figs. 14, 15) _________ 85 50(0. 59) 74(0. 87) 8(0.09) 

Do ______________ ---------- _______ 112 61( • 54) 89( . 79) 8( .07) Do _______________________________ 145 77( .53) 95( • 65) 9( .06) 

Holotype (pl. 28, figs. 13, 15) _________ 120 66( .55) 91(. 76) 5( . 04) Do ______________________ . _________ 135 70( .52) 96( . 71) 4( .03) 

This species is by far the most globose in the genus 

Lilloettia. It is named in honor of Don J. Miller who 

collected the specimens. 

Holotype, U.S.N.M. 108027; para types, U.S.N.M. 

108028, 108029. 

Chinitna formation, middle of lower third, U.S.G.S. 

Mes. loc. 21322. 

Lilloettia mertonyarwoodi Crickmay 

Plate 30, figures 3, 5-7, 9-11 

Lilloettia mertonyarwoodi Crickmay, Canada Nat. Mus. Bull. 63, 

p. 62, pl. 19, figs. 1, 2, text fig. 7, 1930 

·Three specimens from Alaska represent this species. 

Form fairly stout; whorls subovate, a little wider than 

high on outer two whorls, widest near the middle of the 

flanks in the inner whorls but widest at the top of the 

lower fourth of the flanks on the body whorl, embracing 

nearly completely; flanks on inner whorls flattened below, evenly convex above; flanks on outer two wliorls 

gently convex, upper three-fourths conv:erging to a 

moderately narrow venter; venter changing from. 

evenly arched on inner whorls to rather narrowly 

arched on body whorl. Umbilicus extremely narrow, 

helicoid; wall low, vertical, rounding rather abruptly 

into flanks. Body chamber represented by at least fivesixths of a whorl. Aperture not preserved. 

The ribbing of the whorl preceding the penultimate 

is shown on plate 30, figures 3, 7, 10. On this whorl the 

ribs curve forward strongly on the lower part of the 

flanks, recurve slightly on the upper part of the flanks, 

and arch forward gently on the venter. The primary 

ribs are sharp-topped, triangular in section, and bifurcate again a little above the middle of the flanks. 

Some of the sets of branched ribs are separated by 

short intercalated ribs. The secondary ribs are triangular in section near the furcation points but become 

broadly rounded on the venter .. At a diameter of 

51 mm there are 22 primary ribs and 71 secondary ribs. 

· The ribbing on the penultimate whorl, shown on 

plate 30, figures 9, 11,- is strongly inclined but less 

flexuous than on the preceding whorl and becomes effaced anteriorly on the lower part of the flanks. 

Wherever the shell is preserved the ribs are much more 

conspicuous than on the internal mold. At a diameter 

of 72 mm there are 92. secondary ribs.· Anteriorly on 

the body whorl (plate 30, figure 9) effacement of the 

ribbing from the flanks spreads more and more ven-

. trally. Concomitantly the ventral ribs become broader 

and fainter but are still visible at the anterior end of 

the shell. 

The suture line as detailed on ·one of the Alaskan 

specimens has a longer external lobe than on the holotype. This is possibly explained by the rather eroded 

and fragmentary condition of the holotype. Otherwise 

the sutures compare very well. The lobes and saddles 

are of about equal width: and th~ saddles are nearly 

symmetrically divided by secondary lobules .. 

The dimensions in millimeters and ratios of the diameter are as follows : 
ALASKA PENINSULA AND COOK INLET REGIONS 77 

8p('cimcn Diame- Whorl Whorl Umbilical tcr height thickness width 

Plcsiotypc (pl. 30, figs. 3, 7, 10) _______ 51 2S(O. 55) 30 (0. 60) 3(0:06) 

Plcsiotypc (pl. 30, fig. ll) ____________ so 45( . 56) 52 ( .65) 3( .04) 

Holotypc. ___ -------------- __________ so 46( . 57) 49 ( • 61) 3( .04) 

Plcsiotypc (pl. 30, figs. 6, 9) __________ 9S 54( . 55) 65?( • 66) 3( .03) 

This species differs from L. lilloetemis Crickmay by 

its thicker whorl section, more strongly converging 

flanks, and finer, sharper ribs. L. milleri is much more 

inflated and has lower, broader ribs. The distinction 

between Lilloettia and Arctocephalites may be illustrated by comparing the inner whorls of L. mertonyarwoodi on pl. 30, figs. 3, 7, 10 with Arctocephalites ellipticus Spath ( 1932, p. 33, pl. 13, figs. 6a, b) . It may be 

noted that the former has a smaller umbilicus, much 

more flexuous ribbing, and· that the ventral ribs are 

wider and more closely-spaced. 

Pleosiotypes, U.S.N.M. 108030-108032. 

Chinitna formation, lower third, U.S.G.S. Mes. loc. 

3028 and 21322; Shelikof formation, top of lower member at 1\.fes. loc. 21362. 

Lilloettia lilloetensis Crickmay 

Plate 30, figures 1, 2, 4, 8 

Lilloettia UlloetensiJ Crickmay, Canada Nat. Mus. Bull. 63, p. 

62, pl. 18, figs 1-4, text fig. 7, 1930. 

The Alaskan collections eontain 4 specimens of this 

speeies. Form discoidal, compressed; whorls ovate, a 

little higher than wide, thickest at top of' lower fourth 

of flanks, embracing nearly completely; flanks gently 

convex, upper three-fourths converging slowly to highly 

arched venter. Umbilicus extremely narrow, wall low, 

vertical, rounding rather abruptly into flanks. Body 

chamber represented by five-sixths of a whorl. Aperture marked on internal mold by a broad, forward1y 

curved constriction that is followed by a low swelling. 

The ribbing of tlw inner whorls of the holotype at a 

diameter of 28 mm is flexuous, strongly inclined forward, and of moderate strength and density for the 

genus. The primary ribs bifurcate near the middle of 

the flanks. Most pairs of forked ribs are separated by 

single intercalated ribs that begin near the middle of 

the flanks. All secondary ribs become fairly thick on 

the venter where they are separated by interspaces about 

as wide as the ribs. 

On the penultimate whorl (plate 30, figures 1, 4) the 

ribs are fairly distinct at the posterior end. The primary ribs are low, broad and divide near the middle 

of the flank into narrower secondary ribs. Single ribs 

are interealated between the paired ribs. On the venter 

all secondaries are moderately broad, low and are separa:ted by interspaces. of similar width. ·Anteriorly on 

the penultimate whorl eff~icement of the ribs takes place 

218\128-53-4. 

rapidly until the anterior end h~ ribs only on the 

venter. The body whorl appears quite smooth except 

for a few faint ribs on the venter at the posterior end. 

·The suture line is essentially the same as that on 

L. mertonyarwoodi and both agree in pattern with the 

sutures of Arctocephalites and Oranocephalites figured 

by Spath (1932, pl. 3, figs. 5, 7, pl. 5, fig. 7b, pl. 1l, 

fig. 7b). 

The holotype at a diameter of 100 mm has a whorl 

height of 57 mm and an estimated whorl thickness of 

50 mm. 

This species is characterized by its compressed form 

and its rather low, fairly dense ribs. L. stantoni Imlay 

is similarly oompresed but has much coarser, more 

persistent ribbing. L. mertonyarwoodi Crickmay (1930, 

p. 62, pl. 19, figs. 1, 2, text-figure 7) has a thicker whorl 

section, more convergent flanks, and sharper ribs. 

Plesiotypes, U.S.N.M. 108033, 108034. . 

Chinitna formation, middle third, U.S.G.S. Mes.locs. 

21340 and 22442; Shelikof formation, lower member at 

Mes. locs. 10814 and 21360 .. 

Lilloettia stantoni Imlay, n. sp. 

Plate 29, figures 1-5, 9, 10 

The species is represented by 10 specimens. Form 

discoidal, compressed; whorls higher than wide, widest 

a little below the middle of the flanks, embracing nearly 

completely; flanks nearly flat in lower half, gently convex in upper half, passing evenly into highly arched 

venter. Umbilicus extremely narrow; wall low, vertical at base, passing rather abruptly into flanks. Body 

chamber represented by_ at least five-sixths of a whorl. 

The ape:rture is not preserved but probably very little 

of the shell is missing. 

The ribbing on the septate part of the shell is vigprous, flexuous, and rather strongly inclined forward. 

The primary ribs are sharp, triangular in section, and 

bifurcate near the top of the lower third of the flanks. 

Many of the furcation points are indistinct. Most pairs 

of forked ribs are separated by short, intercalated ribs. 

The secondary ribs are stronger and rounder than the 

primary ribs and attain their greatest strength on the 

venter. The ribs curve backward on the umbilical 

shoulder, curve forward strongly on the lower part of 

the .flanks, recurve slightly on the upper part of the 

flanks, and arch forward on the venter. At the posterior end of the body chamber the ribbing disappears 

abruptly on the lower half of the flanks, and is replaced 

-by weak, flexuous striae, but the ventral ~ibbing remains 

strong. Anteriorly effacement of the ribbing ex'tends 

farther and farther ventrally so that the anterior third 

of . the body chamber is marked only by striae that 

curved· strongly forward. o 

The suture line is imperfectly preserved. 
78 . CALLOVIAN (JURASSIC) AMMONITES FROM 'l'HE. UNITED STATES AND ALASKA 

The dimensions in millimeters and ratios of the diam ~ 

eter ·are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

---- 0 Paratype (pl. 29, fig. 5) _______________ 32 18(0. 56) 15?(0. 47) 1. 5 (0.05) 

Holotype (pl. 29, figs. 9, 10)-------~-- 43 23( .53). 21 ( .48) 3 ?( .07) 

Paratype (pl. 29, fig. 1) _______________ 53 28( .53) ? 3 ( .06) 

Holotype (pl. 29, figs. 2, 3) ___________ 79 46( .58) 40 ( .50) ? 

This species is characterized by vigorous ribbing that 

does not disappear on the lower part of the flanks on . 

the· septate portion of the shell. Among the Alaskan 

species of Lilloettia ·only L. buckmani ( Crickmay) exc~eds ~t in coarseness of ribbing. It is otherwise distinguished from L~ buckmani by its compressed whorl· 

section, flatter fla:r{ks, more persistent primary ribs, and 

somewhat weaker secondary ribs. It is distinguished 

from L. lilloetensis Crickmay ( 1930, p. 62, pl. 18, figs. 

1-4) by having much coarser ribbing, more persistent 

primary ribs, and by attaining its greatest thickness 

higher on the flanks. The ribbing on the inner whorls 

of L. stantoni compares in sharpness with that on the 

inner whorls of Arctocephalites arcticus (Newton and 

Teall, 1897, p. ·500, pl. 40, figs. 1, 1a; 'Vhitfield, 1906, 

p. 131, pl. 18, fig. 2; Spath, 1932, p. 32, pl. 12, fig. 2). 

However, O:t;l L. stantoni the ribbing is more flexuous, 

the primary ribs are more widely spaced, the secondary ribs are thicker and more closely s·paced, and the . 

umbilicus is smaller. 

Holotype,_ U.S.~.M. 108035; paratypes, U.S.N.M. 

108036, 108037 a, b. 

Chinitna formation, middle third· and lower part of 

upper thir_d, U.S.G.S. Mes. locs. 3028, 11049, 22434, and 

22556 ; Shelikof formation, lower member at Mes. loc. 

21359. 

Genus Xenocephalites S~ath 1928 

Xenocephalites hebetus Imlay, n. sp. 

Plate 29, figures 6-8, 11 

This· species is definitely represented in the Survey 

collections by only two specimens, although the imma~ 

ture form shown on plate 29, figures 12, i3 possibly be~ 

longs to the species. Shell small, globose·; whorls de~ 

pressed ovate, wider than high, widest a little below 

middle of flanks, embracing nearly completely except 

on body whorl; flanks evenly convex, merging _evenly 

into broadly rounded venter. Umbilicus extremely 

narrow, widening· at anterior end of ·body chamber; 

wall low and rounding evenly into flanks. Body chamber represented by a little mor.~ than half a whorl. 

Aperture abruptly truncated. 

are ·prominent and widely separated. They bend back~ 

ward on the umbilical wall, strongly forward on the 

lower half of the flank, then backward toward the ven~ 

ter but cross the venter transversely .. Most of the ribs 

bifurcate at the top of the lower third of the flanks. 

In addition there are some intercalary ribs that begin 

along the zone of furcation. 

The suture line is poorly preserved on the type speci~ 

. mens. On a small specimen (plate 29, figures 12, 13), 

which may be a young form of X. hebetus, the suture 

has very broad saddles and its first lateral lobe is much 

shorter than the external lobe. . 

The dimensions in millimeters and ratios of the di~ 

ameter are as follows : 

Specimen Diame~ Whorl whorl Umbilical ter height thickness .width 

Paratype (pl. 29, figs. 6, 7) ___ -------- 46 23(0. 50) 28 (0.60) 8 (0.17) 

Holotype (pl. 29, figs. 8, 11) __________ 33 20( • 60) 25 ( . 76) 2 ( .05) 

Xenocephalites sp. juv. (pl. 29, figs. 

12, 13) ----------------:-------------I 17 9( . 53) 12. 5( . 73) 1.5(.08) 

This species is characterized by its globose form and 

i by the ribbing of the body chamber becoming strongly 

: flexuous, widely spaced, and prominent ventrally. It 

: differs from X. vicmius Imlay by being more globose 

i and more densely ribbed. X. hebetus compares closely 

;.in form and sculpture with Xenocephalites neuquensis 

· (Stehn) (1924, p. 86, pl. 1, fig. 3, text fig. 11) from Ar-

: gentina. The latter has slightly weaker ribbing and its 

, umbilicus enlarges rapidly at the anterior end of the 

:body whorl. This last fe'ature cannot be proven for 

; X. hebetus · with the material in hand. X. boreriliis 

:Spath (1932, p. 44, pl. 14, figs. 4a-d), from east Green-

: land, has much coarser ribbing than X. heb'etus at a· 

:comparable size. 

The small specimen, plate 29, figures 12, 13, differs 

. ; from the immature forms of any species of 0 adoaeras 

: known from Alaska by its smaller umbilicus, broader 

i whorl section, and flexuous ribs that· branch by twos 

: and threes on the lower third of the flanks. Its lateral 

:aspect is sphaeroceratid and thus, quite different than 

; that of the immature forms o:f Pleurocephrilites figured 

i by Spath ( 1928, p. 171, pl. 36, figs. 4-6) . Its aspect is 

:similar to some immatm;e Oranoaephalites from Alaska 

; except that the latter have high, thin ribs. 

Holotype, U.S.N.M. 108038; paratype, U.S.N.M. 

; 108039. 

. Chinitna formation, near base, U.S.G.S. Mes. locs. 

21329 ·and 22434. 

Xenocephalites vicarius Imlay, n. ,sp. 

The ribs on the penultimate whorl are broadly . . Plate 28, figures 1-8 

rounded and~ a little wider ·than the. interspaces. On The Survey collections ·contain eight specime~s of 

the last whorl the ribs become progressively higher and ·this species. Shell small, compressed in young, mod~ 

narrower than the interspaces and on the body chamber . erately in·flated in adult; whorls ovate, wider than high, 

•• 

.. 
ALASKA PENINSULA AND COOK INLET REGIONS 79. 

- 'becoming depressed during growth, widest a little be- slopes. l\1ost of the primary ribs branch a little below 

low the .middle of the flanks, embracing nearly com- the middle of the flanks and many of the pairs of forked 

pletely; flanks gently convex, venter evenly arched in ribs are separated by single, short, intercalated ribs. 

young, becoming broadly arched on body whorl. Urn- The suture line is poorly preserved. 

bilicus extremely narrow, enlarging slightly at anterior . The holotype at a diameter of 30 mm has a whorl 

end ·of body whorl; wall very low, vertical, and round- height of 16 m~ and a whorl thickness of 18 mm. 

ing evenly into flanks. Body chamber represented by Compared with X enocephalites vicarius Imlay this 

three-fourths of a whorl. The aperture is· inclined species is a little more inflated and has less prominent, 

strongly forward and abruptly truncated. less widely spaced ribbing on its body whorl. X. parvus 

The. ribs on the inner whorls are fine, dense, ahd var. angustiumbilioatus (Stehn) (1924, p. 92, pl. 1, fig. 

nearly radial. On the body whorl they become high and 6, text-fig. 13) from ~he Callovian of Argentina is very 

thick ventrally, widely spaced, strongly flexuous on similar. It appears to have a stouter form and higher 

the ilanks, and arched forward gently on the venter. points of rib branching. 

The thick ribs on the venter have longer posterior than This species is named in honor of John K. Hartsock, 

· an.terior slopes. Some ribs remain simple, but most of the Geological Survey, who has spent several sumribs branch slightly below the middle of the flanks. mers studying the Jurassic in the Cook Inlet area. 

Some of the branch ribs are indistinctly connected with · Holotype, U.S.N.M~ 108045; paratype, U.S.N.M. 

the primary ribs and, in places, unbranched ribs alter- 108046. 

nate with short ribs that begin near the middle of the , Chinitna formation, lower two-fifths, U.S.G.S. Mes. 

flank. locs. 21341 and 21349. 

The suture line is not preserved. 

The holotype at a diameter of 33 mm has a whorl 

height of 17 mm, a whorl thickness of 19 mm, and an 

umbilical width of 3 mm. 

This. species is distinguished by the high, blunt, 

widely spaced ribs on its body whorl. X. hebetus Imlay 

has a more robust form and a more rapid change from 

fine to coarse ribbing. X. nilcitini (Burckhardt, 1927, 

· p. 33, p1. 16, figs. 4-9) has less dense ribbing and a more 

rounded whorl section. Reference to Xenocephalites 

rather than Kamptooephalites is indicated by the extremely narrow umbilicus, the depressed whorl section, 

the small size, and the early appearance of prominent, 

strongly flexuous ribs. 

Holotype, U.S.N.M. 108041; paratypes, U.S.N.M. 

108042-108044. 

Chinitna formation, lower third, U.S.G.S. Mes. locs. 

3028, 11041,21321,21329, 22437, 22438, and 22556. 

Xenocephalites hartsocki Imlay, n. sp. 

Plate 28; figures 9, 10, 12 

The species is repr:esented by three specimens. Form 

small, moderately inflated; whorls subquadrate, a little 

wider than high, widest slightly . below the middle of 

the flanks, embracing nearly completely; flanks somewhat flattened on lower part, rounding evenly into 

broadly rounded venter. Umbilicus extremely narrow; 

wall low, rounding rapidly into flanks. Body chamber 

incomplete but represented by at least five-sixths of a 

whorl. 

The ribs on the penultimate and body whorls are 

sharp and strongly flexuous. On the penultimate whorl 

they are closely spaced and have uniform steep slopes, 

but anteriorly on the body whorl they become widely 

spaced and develop vertical or overhanging posterior 

Genus Xheraiceras Spath 1924 

Xheraiceras magniforme Imlay, n. sp. 

Plate 31, figures 5-8 

This species is based on five specimens including two 

adults. Shell globose; whorls depressed, much wider 

than high, widest at the top of the lower fourth of the 

flanks, embracing nearly completely except for body 

chamber; flanks evenly convex, merging gradually into 

broadly rounded venter. Umbilicus extremely small, 

but enlarging rapidly on anterior fourth of body whorl; 

wall fairly low and rounding evenly into flanks. Body 

chamber represented by about three-fifths of a whorl, 

hook-shaped in lateral view, depressed anteriorly but 

not constricted transversely. Aperture not perfectly 

· preserved, but marked by an abrupt il).ward bending of 

the shell which probably was not followed by a swelling. 

The ribs on the septate posterior . part of the last 

whorl are low, rounded, a little narrower than the interspaces, and indistinct near the umbilicus. Anteriorly 

on the -body chamber the ribs become progressively 

broader and more widely spaced and are rather prominent at the anterior end of the shell. The primary ribs 

begin on the upper part of the umbilical wall, incline 

forward slightly on the lower third of the flanks and 

then pass into two or three secondary ribs that curve 

forward gently near the middle of the flanks, but cross 

the venter transversely. Single intercalary ribs occur 

between most rib pairs. · 

The suture line is finely divided and shows the broad 

saddles and lobes characteristic of the genus. The general sutural pattern is similar to that of Kheraieeras 

cosmopolita (Parona and Bonarelli) figured by Spa:th 

(1928, pl. 47, fig. 6), although more complex and having 

a shorter first lateral lobe. 

, .. 
80 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

The holotype at a diameter of 79 mm has a whorl 

height of 47 mm and a whorl thickness of 66 mm. At 

the anterior end of the holotype the diameter is 95 mm, 

the whorl height 40 mm, and the whorl thickness 70 mm. 

The septate portion of K. magniforme compares 

closely in size and shape with the septate holotype of 

K.? globulatum (Quenstedt). (1887, p. 661, pl. 78, fig. 

2}, but its ribbing appears to be much finer. K. stansfleldi Spath (1925, p. 15, pl. 1, figs. 2a, b) has a similar 

shape, but its ribs appear to be weaker and more inclined 

forward. K. cosmopolita (Parona and Bon-arelli) 

(1897, p.146; Waagen, 1875, p.129, pl. 32, figs.1a, b) has 

weaker ribbing and a narrowed body chamber. 

Holotype, U.S.N.M. 108047. 

The holotype was obtained from the Iliamna Bay 

area, but its exact .. location is unknown. It most likely 

came from the lower part of the Chinitna formation 

because all the other species assigned to Kheraiceras are 

from the lower two-thirds. Other specimens of K. 

magnifoiwte are from the Chinitna formation at 

U.S.G.S. Mes.locs. 3028, 22427, and 22448 .. 

Kheraiceras martini Imlay, n. sp~ 

Plate 32, figures 1, 4, 6 

The species is represented for certain only by the 

holotype. Shell stout; whorls depressed, higher than 

wide, widest a little below the middle of the flanks, embracing nearly completely except for the body chamber; 

flanks evenly convex on penultimate whorl, becoming 

flattened on body chamber, merging evenly into broadly 

rounded venter. Umbilicus extremely small but enlarging rapidly on the anterior third of the body 

chamber; wall low, steep and rounding evenly into 

flanks. Body chamber represented by three-fourths 

of a whorl, hook-shaped in lateral view, depressed anteriorly but not constricted transversely. Aperture 

marked on flanks by a pronounced, forwardly inclined 

constriction that is followed by a slight swelling which 

terminates in a sharp edge. -

-The ribs on the septate posterior part of the last 

whorl are low, rounded, much narrowerthan the inter-

. spaces, and 'become stronger ventrally. Anteriorly on 

the body chamber the ribs become broader, more widely 

spaced, stronger on the flanks, but remain rather low on 

the venter. The primary ribs b_egin low on the umbilical wall, are nearly radial on the lower third of the 

flanks and pass into three or four secondary ribs that 

are likewise nearly radial. There are some intercalated 

ribs between the bundles of ribs. 

The suture line is very complicated and not very well 

preserved. It appears to be very' similar to that of 

Kheraiceras magniforme lmlay except that it is more 

_ frilled. 

The h~lotype at a diameter of 108 mm has a whorl 

height of 57 mm, and a whorl thickness of 70 mm. A 

quarter of a whorl .anteriorly the corresponding dimensions are 122, 61, and 72 inm. Near the end of the 

shell the corresponding -dimensions are 121, 54, and 

75mm.' 

This species is distinguished from K. inagruiforme 

Imlay by its higher whorl section, longer body chamber, 

-and finer ribbing on the body chamber. 

This species is named in honor of George C. Martin, 

who spent many years studying the geology of Alaska. 

Holotype, U.S.N.M. 108048. 

Chinitna formation, basal beds, U;S.G.S. Mes. loc. 

22446. 

Kheraiceras abruptum Imlay, n. sp. 

Plate 33, :figures -1, 7, 11, 13 

The species is represented by five adult specimens, of 

which the holotype has the most prominent ribbing. 

_ Shell stout; whorls depressed, wider than high, widest 

at the top of the lower fourth of the flank, embracing 

ne~rly completely except for the body chamber; flanks 

somewhat flattened in their lower parts, gently convex 

above and rounding evenly into broadly rounded venter. 

Umbilicus extremely small, but enlarging rapidly on 

anterior half of body chamber; wall very low, rounding evenly into flanks. Body chamber represented by 

about three-fourths of a whorl, depressed anteriorly but 

not constricted transversely. Aperture marked by a 

pronounced forwardly inclined constriction that is followed by a weak swelling. 

The ribs on the penultimate whorl are moderately 

high, rounded, and are a little narrower than the interspaces. The primary ribs incline forward on the lower 

third of the flanks and pass into two, or three slightly 

weaker secondary ribs that curve forward strongly but 

cross. the venter transversely. There are many intercalated ribs. 

At the beginning of the body chamber the ribbing 

suddenly becomes much coarser and more widely spaced 

and the coarsening increases greatly anteriorly. Most 

of the primary ribs branch on the lower third of the 

flanks into two sharper secondary ribs, but some primary ribs do not branch. In addition single short ribs 

occur between most pairs of branched ribs. 

The suture line is poorly preserved but the elements 

appear to be broad and shallow as in other species of 

K heraiceraB. 

- The holotype at a diameter of 120 mm has a whorl 

height of 61 mr;n. At the anterior end of the holotype 

the diameter is 139 mm and the whorl height is 53 ·mm .. 

This species is characterized by the coarse ribbing 

of its body chamber and by the abrupt change from 

fine to coarse ribbing at the beginning of the body 

chamber .. 

Holotype, U.S.N.M. 108049. 
ALASKA PENINSULA AND COOK INLET REGIONS 81 

Chinitna formation, lower third, U.S.G.S. Mes. locs. 

22433, 22428, and 22431 ; Sheliko£ formation, lower 

member, Mes. loc. 19793. 

Xheraiceras varicostatum Imlay, n. sp .. 

- Plate 33, figures 2, 4, 5 

The ~pecies is r:epresented by one specimen whose 

body whorl is niuch eroded on one side and on the ven"' 

ter. Shell globose; whorls depressed, much wider than 

high, widest at the top of the lower third of the flanks, 

embracing nearly completely except for body chamber; 

flanks evenly convex, merging gradually into broadly 

rounded venter. Umbilicus extremely small, but enlarging rapidly on anterior fourth of body whorl; wall 

. moderate in height and rounding evenly into flanks. 

Body ·chamber represented by about three-fifths of a 

whorl, anterior_ hal£ becoming rapidly evolute, de- · 

pressed anteriorly but only slightly n~rrowed transversely. -Aperture marked by a pronounced forwardly 

inclined constriction that is followed by a slight 

swelling. . . 

The ribs on the ·septate posterior part of the last 

. whorl are fine, rather widely spaced, and flexuous. The 

ribs curve backward on the umbilical wall, curve forward on the middle of the flanks, and then recurve 

slightly and cross the venter with only a gentle forward 

arching. The primary ribs divide· into two slightly 

weaker secondaries at the top of the lower third of the 

flanks. Generally· one of the secondaries is indistinctly 

connected. In addition most pairs of branched ribs are 

separated by il!tercalary ribs that begin along the zone 

of furcation. This results in aqout 3 secondary ribs 

for every primary. Anteriorly on the body chamber 

theribs become progressively stronger and more widely 

spaced and are moderately prominent at the anterior 

end of the shell. Also, they become inclined more 

strongly forward. 

The highly frilled sutureline has even broader saddles than that of K. magniforme Imlay. The first lat-

. erallobe i~ also more slender and longer. The general 

. pattern greatly resembles that of the suture of a specimen of Ammonites platystomus Quenstedt ( 1887, pl. 

78, fig. 25) ~ -

,The holotype at a diameter of 65 mm has a whorl 

height of 32 mm and an estimated whorl thic_kness oL 

42mm. · 

This species differs from K. magniforme by its much 

smaller size, i,ts more widely spaced ribbing, and by its 

bodyehamber· being lesshook-like in lateral view. K. 

cosmopolita (Parona arid Bonarelli) (Waagen, 1875, 

p. 129, pl. 32, fig. 1) has a more narrowed body chamber 

and weaker ribbing. 

Holotype; U.S.N.M. 108050. 

Chinitna formation, base of middle third,. U.S;G.S. 

' Mes. loc. 20760. . · 

/ 

Kheraicera.s ~ntermedium Imla~, n. sp. 

Plate 31, figures 1-4; plate 32, figures 2, 3, 5, 7, 8 

· The species is based on four specime~s, including 

three adults. Shell medium stout; whorls ovate depressed, wider than high, widest on the lower fourth of 

the flanks, embracing· considerably ; ·flanks gently convex, merging into evenly rounded venter. Umbilicus 

small; wall low and rounding evenly into flanks. Body 

chamber represented.by three-fifths of a whorl, not depressed anteriorly. Aperture on internal mold marked 

by a deep, forwardly inclined constriction 1ollowed by 

a gentle swelling .. 

The ribs on the penultimate whorl are narrow, are 

separated by somewhat wider interspaces, incline for- . 

ward gently on the flanks, and arch forward slightly on 

the venter. Most of the primary ribs bifurcate below 

the middle of the flanks, but some remain simple and 

some are indistinctly connected ·with secondary ribs. 

Other ribs arise along the zone of furcation resulting in · 

nearly three secondary ribs for every primary. ,.On 

the body chamber the ribs are low, narrow, and fairly 

widely spaced. They incline backward on the umbilical wall and incline forward gently on the flanks· and 

venter. Most of the primary ribs bifurcate at the top 

of the lower two-fifths of the flanks and about hal£ of 

the rib pairs are separated by intercalary ribs. 

The suture line, fairly well-preserved on the halotype, is similar to that on K. magniforme Imlay, but 

has broader saddles and is somewhat less frilled. 

The dimensions in miliimeters and ratios of the 

diameters are as follows : 

·-

Specimens Diame- Whorl Whorl Umbilical · ter height thickness width 

-----------

Holotype (pl. 31, figs. 3, 4) ___________ 73 41(0. 56) 44(0. 60) 3(0.04) 

Holotype (pl.31, figs. 3, 4)----------- 86 43( .50) 50( .58) 12( .]4) 

Paratype (pl. 31, figs. 1, 2) ___________ 1 69 37( .53) 39( .5(,1) ? 

Paratype (pl. 32, figs. 7, 8) ___________ 62? 26(. 39) 31( .46) ? 

I 

This species is distinguished from most o£ the species 

of Kheraiceras described herein by its much less inflated 

form and its weaker ribbing.· K.? parvifo1"l}?;e Imlay is 

more compressed. Inclusion of K. i1itermedium in the 

genus Kheraiceras is indicated by its small umbilicus, 

contracting body whorl, and pronoqnced apertural 

constriction. Furthermore, similarly compressed forms 

have been reJerred to K. quenstedti (J. Roemer) (1911, 

p. 42; Spath, 1925, p. 16; Quenstedt, 1887, pt 77, figs. 

7, 8) and K. microstoma (Quenstedt) (1887, pt 78, 

fig. 5) (non d'Orbigny)~ The latter appears to differ 

from K. intermedium mainly in its -smaller size and narrowed body chamber. 

Holotype, U.S.N.M. 108223; para types, U.S.N.M. 

108051, 108224, 108225. 

Chinitna £.ormation, ·lower third, U.S.G.S. Mes. locs. 

21272, 21273, and 21334. 

l 
... 

ALASKA PENINSULA :ANtfi COOKYIN·L"ET i{E.GIONS · · . ... 83 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

---------------------- Plcsiotypc (pl. 34, figs. 2, 3) _ _' _________ 32 13(0.40) 12. 5(0. 39) 10(0. 31) 

Plcsiotypc (pl. 34, figs. 7, 13) __________ 57 23( .40) 33 ( .57) 18( . 31) 

Plcslotypc (pl. 34, ftgs.1, 4) ___________ 88 35( .39) ? 27( . 30) 

Plesiotypc (pl. 34, figs. 12, 14) ________ 103 45( .43) 55 ( .53) 33( .32) 

. This species is characterized by the high, sharp rib- . 

bing of its inner whorls, by the rather abrupt disappearance of ribbing near the beginning of the body 

chamber, by the abrupt reappearance of ribbing on the 

anterior part of the body chamber, and by the outer : 

whorls being much more involute than the inner whorls .. 

Of the assocjated Alaskan species it is most similar to 

· 0. com'rna, but is readily distinguished by its coarser 

ribbing and less inflated form. 0. simulans Spath 

(1932, p. 61; Nikitin, 1885, p. 52, pl. 11), from Russia, 

has similar ribbing but is much more inflated. The 

Rmall forms of 0. catostorna have ribbing similar to 

that of 0. elatrnae Nikitin (1881b, pl. 11, figs. 20-22; 

1885, pl. 10, fig. 47) or of 0. crassum M~dsen (1904, p. 

193, pl. 9, figs .. 1-3, pl. 10, fig~ 1), but the medium and 

large forms develop a distinct umbilical rim which is 

not present in . these species. 0 adoceras quenstedti 

Spath (1932, p. 49, Quenstedt, 1887, p. 672, pl. 79, fig. 7) 

is similar to 0. catostoma in lateral view but has a 

stouter form. 

Plesiotypes, U.S.N.M. 108054a, b, c, 108055a, b, 

108056. . 

Chinitna formation, lower two-thirds, U.S.G.S. Mes. 

loc~ 2707, 2921, 3020, 3028, 3029, 11052a, 21288, 21348; 

21349, 22419, 22430, 22432, and 22437. Shelikof formation, lower m·ember, locs. 10803, 21359, and 22132. 

Cadoceras comma Imlay, n. sp. 

Plate 35, figures 1-8; plate 36, figures: 1-5 

This species is represented by about 80 specimens, 

representing various growth stages . 

Shell moderately inflated in young, globose in adult; 

whorls ovate in young,.much depressed in adult, widest. 

· at· the umbilical edge, embracing about four-fifths; 

flanks gently convex in young, not separable from venter in adult; venter evenly arched in young, becoming: 

broad in adult. Umbilicus fairly narrow, 5tep-like in 

young, becoming funnel-shaped in adult; wall steep 

and fairly high; edge fairly abrupt in young~ becoming 

Sharp in adult. Body chamber represented by about 

five-sixths of a whorl. 

The ribs are strong and widely spaced on the small 

and intermediate sized whorls up to a diameter of about 

6.3 em. They then begin to disappear first on the venter 

and then on the flanks and are replaced on the penultimate and body whorls by many, fine, forwardly inclined 

striae. The ribs are nearly ·radial on the upper part 

of the umbilical wall, bend .abruptly forward just above 

the umbilical· edge, and are arched for.ward gently on 

th~ venter .. On the young the ribs are sharp on the 

upper part of the umbilical wall and on the lower part 

of the flanks and bifurcate on the lower third of the 

flanks into broad, strong secondaries. During growth 

the ~ibs become higher and sharper on the umbilical 

edge, broader and lower on the flanks and venter, the 

· furcation points become indistinct, and some of the 

forked r.ibs are separated by intercalary ribs. Continuation of this change results in the last two whorls 

being nearly smooth except for lines of growth and for 

rather conspicuous comma-shaped umbilical swellings 

that persists nearly to the anterior end of the body. 

· chamber. The aperture is marked on the internal mold 

by a pronounced forwardly inclined constriction fol- · 

lowed by a low swelling that projects forward on the 

venter. 

The suture line is similar to that of 0. catostorna 

Pompeckj except that the second lateral lobe is nearly 

as long as· the external lobe and much longer than in 

most species of 0 adoceras. 

The dimensions in millimeters and ratios of the diameters are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

-- Paratype (pl. 35, figs. 4, 5) ___________ 31 13. 5(0. 43) 15(0. 48) 8(0.26) 

Paratype, (pl. 35, figs. 7, 8) ___________ 44 -21 ( .47) 30( . 68) 13( . 29) 

Paratype, (pl. 36, fig. 5)-------------- 62 25 ( .40) 40( .64) 18( . 29) 

Holotype (pl. 36, figs. 1, 2) ___________ 75 32 ( .42) 53(. 70) 25( .33) 

Paratype (pl. 35, fig. 6) _______________ 130 58 ( .44) 73( . 56) 39( .30) 

This species is characterized by its globose, coronate 

form, by coarse ribbing that passes into striae on the 

last two whorls, and by the persistence of commashaped swellings on the. umbilical edge. It differs from 

0. catostoma Pompeckj by being more inflated at· all 

growth stages and by having lower, weaker ribbing 

.that disappears earlier. Its ribbing is intermediate in 

strength ~etween 0. catostorna Pompeckj and 0. 

glab'f"'llmA Imlay, n. sp. Its general appearance is very 

similar to 0. sim'Ulan8 Spath ( 1932, p. 61; Nikitin, 1885, 

p. 52, pl. 11), but its form is much less globose. 0. 

sublaeve var. rugosum Spath (1932, p. 60; Buckman, 

1922, vol. 4, pl. 275) is more coarsely ribbed, the ribs 

are more persistent, and the form is more inflated. 

Holotype, U.S.N.M. 108057; paratypes, U.S.N.M. 

108058a,b,108059a,b,c,108060-1U8063. 

Chinitna formation, lower two-thirds, U.S.G.S. Mes. 

locs. 292~, 3020, 3028, 3029, 3042, 10989, 11052, 20759, 

21338, 21339, 21344, 21348, 21349, 21781, 22425, 22432-. 

22435, 22438, and 2245_2; Shelikof formation, lower 

member at Mes. locs. 19781 and 19911. 
84 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Cadoceras glabrum Imlay, n. sp. 

Plate 36, figure 6; plate 37, figures 1-9 

This species is represented by 40 specimens, including 

6 that are less than 2% em in diameter and 8 are adult 

specimens more th.an 10 em in diameter. 

Shell compressed in young, moderately inflated in . 

adult; whorls ovate in young, depressed in adult, widest 

at the umbilical edge, embracing about five-sixths; 

flanks evenly convex in young, not separable from 

venter in adult; venter evenly arched in _young, be-

. coming fairly broad in adult. Umbilicus fairly narrow, funnel-shaped; wail steep and moderately high, 

becoming lower on the body whorl; edge evenly rounded 

· in young, becoming sharp on the outer three whorls. 

Body chamber represented by nearly a complete whorl, 

anterior third withdrawn slightly from umbilical edge 

of preceding whorl. 

The ornamentation of the inner whorls up to a diameter of about 50 mm consists of moderately strong ribs 

that are radial on the upper part of the umbilical wall, 

incline strongly forward on the lower part of the flanks, 

and arch forward gently on the venter. They are high 

and sharp on·the umbilical edge and low and broad on 

the venter. Bifu;rcation occurs between th'e lower third 

and lower two-fifths of. the flank, but at diameters 

greater than 30 mm the furcation points are indistinct. 

In addition there are a number of intercalary ribs. At 

diameters greater than 50 mm the ribbing disappears 

rapidly from the vent.er and flanks, and at diameters 

greater than 70 mm the shell is smooth. The outermost 

whorl is marked only by weak growth striae. The 

aperture is marked by a sb·allow, forwardly inclined 

constriction followed by ·a low swelling. Two similar 

constrictions occur on the sutured part of the holotype. 

One ·constriction is about four-fifths of a whorl posterior to the beginning of the body chamber. The other 

constriction (plate 37, figure 5) occurs about one and 

one-quarter whorls posterior to the first. 

The suture line is rather deeply dissected as compared with 0. com;ma Imlay and is similar to the 

suture of. iJ. calostoma Pompeckj. Its first lateral lobe 

is much longer th~an the external lobe and the second 

lateral lobe is much shorter. 

The dimensions in millimeters and ratios of the diameters are as follows: 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype (pl. 37, figs. 8, 9) ____________ 94 37(0.39) .. 66(0. 70) 32(0.34) 

Paratype (pl. 37, fig. 2)--------------- 57 22( .38) 35( • 61) 16( . 28) 

Paratype (pl. 37, fig. 3) --------------- 80 33( .41) 52( .65) 22( .27) 

Paratype (pl. 36, fig. 6). __ ------------ 130 47( .36) ? 50( .38) 

This species is characterized by becoming smooth at a 

fairly small size. It resembles Oadooeras comma Imlay 

in shape, but may be distinguished by finer, sharper 

ribbing on its inner whorls and by much earlier loss of 

ornamentation. 0. wosnessenski {Grewingk) is more 

compressed and has coarser ribbing that persists to 

the body whorL 0. dorosohini (Eichwald) is more 

compressed, has finer,· more persistent ribbing, and its 

umbilicus is step-like instead of funnel-like. 0. 

tsohernysohewi Sokolov {1912, p. 51, pl. 1, fig. 2; pl. 2, 

fig. 1) has coarser ribbing and more persistent umbilical 

swellings. 0. sysolae Khudyaev (1927, pp. 506; 519, pl. 

27, figs. 1, 2, 2 text-figs.) appears to have a lower whorl 

section,· but comparisons ar~ difficult because the ornamentation of its inner whorls is unknown. 

Holotype, U.S.N.M. 108064; paratypes, U.S.N.M. 

108065a, b, c, 108066, 108067. 

Chinitna formation, middle. third, U.S.G.S. Mes. 

locs. 2921, 3028, 3029, 20761, 21774, 22422, and 22432 on 

the Iniskin Peninsula and from loc. 8571 in the Matanuska Valley. -Shelikof formation, lower member, at 

Mes. loc. 19781. 

Cadoceras bathomphalum Imlay; n. sp. 

Plate 38, figures 1, 5, 6 

This species is described on the basis of only one 

specimen, and it is broken across the middle in such 

a manner as to expose a great deal of the inner whorls. 

Shell globular; whorls depressed, much wider than 

high, becoming more depressed during growth, embracing about five-sixths; flanks and venter not separable, forming together a broad low arch.' Umbilicus 

fairly narrow, funnel-like; wall high, vertical at base, 

steeply inclined above; edge abrupt on smallest whorls, 

sharp on intermediate and large whorls. Body chamber not preserved. 

On the inner .whorls up to a diameter of about 55 

mm the ribs are radial on the upper part of the umbilical wall and curve gently forward on the combined 

flanks. and venter. The ribs are broad, rounded, rather 

low, ·and strongest along the midventral line, and are 

separated by ~uch narrower interspaces. They are 

swollen on the umbilical edge and then bifurcate or 

trifurcate. On the outermost whorl, which is probably 

the penultimate, the ornaine~tation consists of commashaped swellings on the umbilical edge and of faint, 

broad, forwardly arched swells on the venter. On 

these swe1ls are superimposed weak striae. 

The suture line is unknown. 

The dimensions of the holotype in millimeters and 

ratios of the diameters are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype (pl.-38, figs. 1, 5, 6) __________ 55 26(0. 47) 46(0.83) 12 (0. 22) 

Holotype _______________________ - ____ 67 30( .44) 64( ,95) 15. 5( . 23) 

Holotype ____________________________ 79 36( . 45) 75( . 95) 20 ( . 25) 

·~ 
( 

•'\"' 

~· 

ALASKA PENINSULA AND COOK INLET REGIONS 85 

This species is characterized by its broad, low ·whorl 

section and deep narrow umbilicus. None of the ·associated Alaskan species resembles it closely. Its shape 

is very much like OadocerCl8 orbis Spath (1932, p. 61, 

D'Orbigny, 1847, p. 468, pl. 170), but it has a smaller, 

deeper umbilicus, a sharper umbilical edge, and ap'" 

parently coarser ribbing. O.·tolype Buckman (1923, 

pl. 406) has coarser ribbing and a less sharp umbilical 

edge. 0. sublaeve (J. Sowerby) (1814, p. 117, pl. 54)· 

has a very similar form but is reported to have a nodate 

umbilical rim on the immature whorls. 

Holotype, U.S.N.M. 108068. 

Shelikof formation, lower n1ember, U.S.G.S. Mes. 

loc. 12408. Small immature forms possitfly belonging 

to this species occur in the Shelikof formation at 

U.S.G.S. Mes. loc. 12387, and in the lower part of the 

Chinitna format1on at U.S.G.S: Mes. locs. 3029, 21343, 

and 21348. 

Cadoceras tenuicostatum Imlay, n. sp. 

Plate 38, figures 2-4, 7-12 

~'his species ·is represented by 33 specimens. Shell 

discoidal, moderately compressed; whorls ovate, width 

and height about equal in small forms, much wider than 

high in the intermediate and adult forms, wide5t at the 

umbilical edge, embracing about four-fifths; flanks 

gently convex in young, becoming broadly rounded in 

adult; venter evenly rounded, becoming broader during 

growth. Umbilicus fairly narrow, step-like; wall steep 

and moderate in height; edge fairly abrupt in young, 

becoming sharp in the adult. Body chamber represented by three-fourths of a whorl. 

On the smallest whorls (plate 38, figures 3, 4, 10, 11) 

the ribs are thin on the flanks, thick on the venter, and 

moderate in height and density. They are radial on 

the upper part of the umbilical wall, incline gently 

forward on the flanks, and arch forward slightly on the 

venter. They are slightly 5wollen on the umbilical edge 

but do not give rise to tubercles. Most ribs bifurcate 

on the lower third of the flanks. Intercalary ribs are 

common. On the larger whorls the ribs become finer 

and closer-spaced anteriorly and on the penultimate 

whorl are scarcely stronger than striae. The weak 

umbilical swellings persists to about the middle of the 

penultimate whorl. The body whorl is nearly smooth, 

being marked only on the venter by faint striae that 

arch strongly forward. The aperture is marked on the 

·internal mold by a pronounced forwardly inclined constriction that is followed by a prominent swelling. 

The sutur~ line is typical of the genus. The first 

lateral lobe is as long as the external lobe. The second 

lateral lobe is much shorter. The external and first 

lateral saddles are a5ymmetrically divided. 

The dimensions in millimeters and ratios of the diameters are as follows : 

Specimens Diame- Whorl Whorl Umbilical ter height thickness width 

Paratype (pl. 38, figs.10, 11) _________ 34 16 (0. 47) 16(0.47) 5.5(0.13) 

Paratype (pl. 38, figs. 3, 4) ___________ 43 19. 5( • 45) 20( .46) 8.5( .20) 

Paratype (pl. 38, fig. 2) _______________ 66 29 ( .·44) 38( • 57) 17 ( • 25) 

Holotype (pl. as; figs. 8, 9) ___________ 83 37 ( . 44) 53( .64) 22 ( .26) 

Holotype (pl. 38, fig. 12) _____________ 106 49 ( . 46) 58( • 55) 26 ( .24) 

Compared with OadocerCl8 doroschini (Eichwald) 

this species has a thicker whorl section and much finer 

ribbing. 0. milaschevici (Niki~in) (1881a, p. 66, pl. 3, 

figs. 25-27; 1881b, p. 121, pl. 12, figs. 26, 27) has a higher 

trigonal whorl section .. 0. tcheflcini (D'Orbigny) 

( 1845, p. 439, pl. 35, figs. 10-15; Nikitin, 1881a, p~ 64, 

pl. 3, figs. 21-23) is inuch more inflated. 

Holotype, U.S.N.M. 108069; paratypes, U.S.N.M. 

108070-108073. 

Chinitna formation, lower part of upper half, 

· U.S.G.S. Mes. locs. 2921, 3029, · 3030, and 20763. 

Shelikof formation, lower and middle members, at locs. 

3103, 3106, 3113, 10818, and 21356. 

Cadoceras doroschini (Eichwald) 

Plate 39, figures 1-12 

Ammonites doroschini Eichwald, Halbinsel Mangischlak und die 

A.leutischen Inseln, pp. 138-142, pl. 7, fig. 6, pl. 8, figs. 1-2, 

1871. 

The Survey collections contain 31 specimens that are 

referable to this species. In addition there are specimens less than 2¥2 em. in diameter that niay belong to 

the species. Shell discoidal, compressed in young, becoming moderately inflated in adult; whorls subquadrate in young, depressed ovate in adult, as high as wide 

in the small forms, much wider than high in the intermediate and adult forms, widest -at the umbilical edge, 

embracing about four-fifths;· flanks flattened in young, 

evenly convex in adult; venter evenly rounded, becoming broader during growth. Umbilicus fairly narrow, 

step-like, wall steep and moderate in height; edge 

fairly. abrupt in young, becoming sharp in the adult. 

Body chamber represented by about three-fourths of 

a whorl. 

The ribs are moderate in strength and density on the 

inner whorls, diminish gradually in strength on the 

penultimate whorl, and are compl~tely lacking on most 

of the body whorl. The ribs are nearly radial on the 

upper part of the umbilical wall, are swollen slightly 

on the umbilical edge, incline forward gently on the 

flanks, and arch forward a little on the venter. Most 

ribs bifurcate on the lower third or fourth of the flank, 

but a few ribs remain simple. There are a few intercalary ribs that. begin on the lower third of the flanks. 

The ribs begin to disappear first on the lower third of 
86 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

the flanks. and then on the venter. The weak swellings 

on the umbilical edge persist as far as the posterior end 

of the body chamber. ·The aperture is marked on the 

·internal mold by a pronounced forwardly inclined constriction. followed by a _prorni~ent swelling that projects 

forward on the venter. · 

. The sub~re line greatly resembles that of ·o. tenuicostatu~ Imlay. 

The dimensions in millimeters and ratios of the 

diameters are as follows: 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Plesiotype (pl. 39, fig. 5).·------------ 37 17(0.46) 14(0.38) 7. 5(0. 20) 

Plesiotype (pl. 39, figs. 8, 9) __________ 42 20( .47) 18( .43) 8.5( .20) 

Plesiotype (pl. 39, fig. 11)------------ 67 29( .43) 39( .l)!l) 18 ( • 27) 

This species differs from 0. stenoloboide Pornpeckj by 

its lower whorl section, slightly wider and deeper umbilicus, and . more pronounced .a pertural constriction. 

Identity with t:Q.e forms that Eichwald assigned to A. 

doroschini is indicated by the moderately compressed 

form, deep apertural constriction, the small, step-like 

umbilicus, and the presence of small umbilical swellings 

· on the inner whorls. The only other species in the 

Alaskan collections with this combination of characters 

·is 0~ tenuicostatu~·Imlay, described her~in, which differs from 0. doroschini (Eichwald) by being a little 

~ore inflated and byhaving much finer ribbing. Eich-

·wald (1871, p. 142) notes that the young individual of 

0. doroschini differs from 0. wosnessen8kii (Grewiilgk) 

(1850, p. 344, pl. 4, figs. la-d) by having a step-like 

umbilicus, forwardly arched instead of straight, inclined ribs, and knots on the umbilical edge.· Pornpeckj 

(1900, pp. 253, 254) considers that the small specimen 

which Eichwald (1871, pl. 8, fig. 2) assigned to 0. doroschini resembles 0. wosnessenskii much more than the 

·large, flatter specimen that Eichwald (1871, pl. 7, fig. 6, 

pi: 8, fig.1) lik~wise assigns· to 0. doroschini, but that 

Eichwald's descriptions and remarks are not precise 

enough to permit comparisons.' Material now in hand 

indicates that the immature forms of 0. doroschini are 

finer-ribbed and less stout than those of 0. wosnessenskii 

and that the adult body whorl of 0. doroschini differs 

·from the comparable whorl of 0. wosnessenskii by having a narrower umbilicus, a thinner whorl section, a less 

distinct unbilical edge, and by a complete loss of 

ornamentation. 

Plesiotypes, U.S.N.M. 10807 4a, b, c, 108075a, b, 

"108076. 

S~elikof forrnatio~, rn.iddle member, at U.S.G.S. Mes. 

locs. 3113 and 12387. Chinitna formation, middle third 

. and lower part . of ~pper third, Mes. locs. 2941, 3018, 

3028,3029,3030,3700,20763,21344, and22435. i 

. · Cadoceras wosnessenskii (Grewingk) 

Plate 40, figures 1-12 

.Ammonites wosnessenskii Grewingk, Russ. K. Min. Gesell. St 

Petersburg Verb. 1848-1849, p. 344, pl. 4, figs. la-d, 1850 

Oadoceras wosnessenskii Pompeckj,_ Russ. K. Min. Gesell. St 

Petersburg. Verb., ser. 2, Band 38, pp. 251-254, pl. 5, fig 

5a-c, 1900. ' · 

The Survey collections contain 75 specimens of this 

species, including 11 that are less than 2¥2 ern in diam 

eter and 3 that exceed 10 ern in dia~eter. 

Shell compressed in young, becoming moderately in 

flated in adult; whorls ovate, slightly wider than high 

in young, becoming much wider than high in adult 

widest at the umbilical edge, embracing about four 

fifths; flanks slightly convex in young, evenly convex 

in adult; venter evenly rounded, becoming broader dur 

ing growth. Umbilicus fairly narrow, step-like on 

inner whorls; wall fairly steep and moderately high on 

body whorl; edge evenly rounded in young, becoming 

fairly abrupt in adult. Body chamber represented by 

about five-sixths of a whorl. 

The ribs are fairly strong and fairly widely spaced 

on the young and intermediate-size whorls up to a diameter of about 7lh ern. At greater diameters they begin to disappear on the venter but remain fairly strong 

on the ·flanks as far as the body whorl. The ribs are 

nearly radial on the upper part of the umbilical wall, 

bend abruptly forward just above the umbilical edge, 

and are arched forward gently on the venter. On the 

young the ribs are fairly sharp on the upper part o"f 

the umbilical wall and on the lower part of the flanks 

and bifurcate on the lower two-fifths of the flanks into 

slightly weaker secondaries that broaden and become 

lower on the venter. During growth the ribs become 

. higher and sharper on the umbilical wall, broader and 

lower on the flanks and venter, the furcation points become indistinct, and a few intercalary ribs appear. The 

anterior two-thirds of the body whorl is nearly smooth 

except for lines of growth and for persistent, small, 

comma-shaped umbilical swelling. The aperture is 

marked on the internal mold by a forwardly inclined 

constriction followed by a low swelling that projects 

forward on the venter. 

The suture line is similar .to that of 0. doroschini 

(Eichwald) and 0. tenuicostatu~ Imlay, previously 

described. 

The dimensions in millimeters and ratios of the diarneters are as follows : . 

Specimen Diame- Whorl Whorl Umbilical ter height . thickness width 

Plesiotype (pl. 40, fig. 8) _________ ·--- 32 14 (0.43) 15. 5(0. 48) 8. 5(0. 26) 

Plesiotype (pl. 40, figs. 5, 6) __________ 48 21.5( .45) 24 ( . 50) 11 ( • 23) 

Plesiotype (pl. 40, figs .. 2, 3)---------- 65 31 ( . 47) 36 ( .55) 15 ( • 23) 

Plesiotype (pl. 40, figs. \1, 12) _________ 114 44 ( ·.38)' 54 ( .47) 33 ( .29) 

Holotype_. ___________________ -- __ --- 48 21. 5( • 45) 27 ( .56) 9. 5( 20) 

.~ 
) 

ALASKA PENINSULA 'AND COOK INLET REGIONS . 87 

·This species 1~esembles 0. com1na Imlay in the persistence of comma-shaped umbilical swellings, 'brt~'.inay be 

distinguished by its more compressed :form, more narrow ubilicus, and finer, closer-spaced ribbing that persists to a later growth stage. The immature forms have 

ribbing similar to that of 0. victor Spath (1932, p. 67, 

pl. 16, figs: 6a-c), but thei.r umbilicus is smaller and 

their whorls more compressed. 

Plesiotyp.es; U.S.N.M. 108077a, · b, c, 108078a, b, 

108079, 108080. . . . . . 

Chinitmi formation, middle two-thirds, U.S.G.S. 

Mes. locs. 2921, 3018, 3029, 3042, 10982, 20763, 21344, 

21348, 22411, 22421, 22434, and 22435. Shelikof formation, lower Inember, at locs. 19781, 19873,' 21359, and 

21360. Tl-ie holotype is reported to have been obtained 

in the Shelikof formation on the Alaskan Peninsula 

w~st of Sutwik ·Island, which l.s presumably in the 

Chignik Bay area. · . 

Cadoceras kialagvikense Imlay, n. sp. 

Plate 41, figures 1-7 

.Oadoceras doroschini Kellum, Daviess and Swinney (not Eichwald) Geology and oil,possibilities of the southwestern part 

of the Wide Bay anticline, A.laslm: U. S. Geol. Survey Pub., 

figs. Sa, b, 1945. 

Four specimens of this species, including two. adults 

:are available in the Alaskan collections. 

Shell stout at diameters greater than 4 em; whorls 

broadly ovate, much wider than high, becoming wider 

·during growth, widest at the umbilical edge, embracing 

about three-fourths on inn~r whorls and five-sixths on 

lbody whorl; flanks evenly convex; venter broadly · 

rounded. Umbilicus narrow, steplike on inner whorls, 

·funnellike on outer two whorls; wall very steep and 

·fairly high, becoming lower and n1uch less steep near 

.aperture; edge abruptly rounded in young, becoming 

sharp on outer two whorls. Body chamber represented 1

by five-sixths of a whorl. Aperture marked on internal 

:mold by a fairly deep, forwardly inclined constriction 

that is followed by a fairly broad swelling. 

The ribs are fairly strong on the inner whorls, but 

:begin to weaken ventrally oh the anterior part of the 

p(multimate whorl. On the body whorl they are in-

-distinct on the venter and weak on the flanks. The · 

ribs are radial on the upper part of the umbilical wall, . 

incline forward gently on the flanks and arch forward 

·On the venter. On the innermost whorls the ribs are 

moderate in strength and a little narrower than the 

:interspaces. Anteriorly they become broader and 

·lower, but remain somewhat narrower than the inter-

:spaces. On the inner whorls the ribs are only slightly 

higher on the umbilical edge than on the flanks. On 

·the outer two whorls the ribs rise on the umbilical edge 

. into distinct comma:-shaped swellings that persist to 

~he aperture. 

The suture line rivals in complexity that of 0. stenolobwm (Keyserling) in Nikitin (1881b, pL 12 (5), fig. 

30) . - The first lateral lobe is a little deeper than the 

external lobe. The second lateral lobe is much shorter. 

The umbilical edge passes through the inner branch of 

the second lateral saddle. 

The dimensions in millimeters and ratios of the diameters are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype (pl. 41, figs. 1-3) ____________ 57 26(0.45) 35?(0. 61) 10(0.17) 

Paratype (pl. 41, figs. 5, 6) ___________ 93 38( .41) 64 ( .68) . 20( . 21) 

Paratype (pl. 41, figs. 5, 6) ___________ 121 56( .46) ·? 28( • 23) 

This species is much stouter than 0. doroschini ( Eichwald), has coarser, more persistent' :ribbing, and the 

umbilicus is deeper and more funnel-shaped. Compared 

with 0. wosnessenskii ( Grewingk), it is appreciably 

stouter and has a narrower, deep·er umbilicus. 0. 

comma Imlay has a much wider umbilicus and loses its 

ribbing earlier. The inner whorls of 0. kialagvikense 

greatly resemble the inner whorls of 0. sublaeve var. 

r'IJ)gosu1n Spath ( 1932, p. 60; Buckman, 1922, pl. 2~ 5) in 

·stoutness and shape, but the body whorl is much less 

depressed and the umbilical wall is lower. 

Holotype, U.S.N.M. 108081; ·paratypes, U.S.N.M. 

108082, 108083. 

Chinitna form~tion, middle third, U.S.G.S. Mes. 

locs. 20763 and 21345; Shelikof formation, lower member, Mes. locs.: 12408 and 19744. 

Subgenus Paracadoceras Crickmay 1930 

Cado'ceras (Paracadoceras) moffiti Imlay, n. sp. 

Plate 42, figures 3, 4, 9 

This species is represented by a specimen that shows 

the penultimate whorl and part of the body whorl. The 

.specimen was originally in a concretion but was partly 

exposed to weathering before it was collected. It was 

probably compressed slightly .after burial. 

Shell compressed; whorls ova:te, wider than high in 

adult, widest at the umbilical edge, embracing about 

three-fourths; flanks of outer two whorls gently convex.; venter evenly arched, becoming .broader during 

growth .. Umbilicus moderate .in width; wall fairly low, 

steep; edge abrupt on outer two whorls. Body chamber incomplete, but represented by. at least half a whorl. 

The ribs on the penultimate ~horl iricl1ne backward 

on the umbilical wall, recurve on the umbilical edge, 

incline forward moderately on the flanks, and arch forward gently on the venter.. They are moderately spaced, 

coarse, highest on ·the umbili.cal edge·, broadest -and 

lowest on the venter. Some ribs remain simple; but 

-most ribs branch on the lower third of the flanks.· Anteriorly the furcation points become indistinct. There 
88 CALLOVIAN (JURASSIC) AM+\{ONITES FROM THE UNITED STATES AND ALASKA 

are a few intercalary ribs that extend below the middle 

·of the flanks. On the body whorl the primary ribs 

become high, widely spaced, and strongly inclined forward; the secondary ribs become very weak and outnumber the primaries 3 to 1; and the umbilical wall 

becomes nearly smooth .. 

The suture line is poorly preserved. 

Tlie holotype ·at a diameter of 83 mm has a whorl 

height of 32 mm, an umbilical width of 25 mm, and 

an estimated whorl thickness of 47 mm . 

. The penultimate whorl of this species has some resemblances to the whorls at a comparable diameter on 

0~ catostoma Pompeckj, but its ribbing is much coarser. 

The body whorl is distinguished from that of any other 

0 adoceras in Alaska by having ·prominent, strongly 

inclined,· widely spaced primary ribs. Among European forms it shows some resemblance to 0. elatmae 

(Nikitin) (1881b, p. 116, pl. 11, figs. 20, 21, 23; 1885, 

p. 54, pl. 10, fig. 47) but has stronger, more widely 

spaced, more persistent ribbing, a narrower umbilicus, 

and a more compressed form. · 

This species is named in honor of F. H. Moffit, who 

has spent more than forty years studying the geology 

of Alaska. 

Holotype, U.S.N.M. 108084. . 

.· Chinitna formation, top of lower third, U.S.G.S. Mes. 

loc. 10986. 

Cadoceras (Paracadoceras) multiforme Imlay, n. sp. 

Plate 42, figures 1, 2, 5-8, 10 

This species is represented by six specimens. Shell 

compressed in young, higher than wide, becoming much 

wider than high in adult; widest a little below middle 

in young, becoming widest at umbilical edge in intermediate and adult forms; embracing about two-fifths 

on innermost whorls, about three-fifths on adult whorls. 

Flanks on innermost whorls rather high and flat, rounding evenly into highly-arched venter; on intermediate 

and adult whorls the flanks are convex and round 

evenly into a broadly arched venter. Umbilicus wide 

for genus; wall on innermost whorls is low, vertical, 

and rounds evenly into flanks; wall on intermediate. and 

outer whorls is fairly high, steep, arid rounds sharply 

into flanks. Body chamber· represented by five-sixths 

of a whorl. Aperture marked on internal mold by 

a broad, shallow forwardly inclined constriction. The 

anterior part of the body whorl contracts slightly from 

· the preceding whorl, resulting in an umbilical · 

enlargement. 

The inner whorls at diameters less than 30 mm 

clo~ly resemble Pseudocadoceras grewingki (Pompeckj) in ribbing and proportions. · The ribs are narrow, moderately spaced,. and. stronger on the venter 

than on the flanks. They are radial on the umbilical 

wall, inclined forward moderately on the flanks, and 

arch forward on the venter. They are inflected gently 

forward below the middle of the flanks along the zone 

of furcation. Single ribs outnumber forked ribs. 

There are a few short intercalated ribs, and many of 

the secondary ribs are indistinctly connected with primary ribs. The ribs are swollen at the points of fur- . 

cation hut not tuberculated. Compared with PseudocadoceraB grewingki (Pompeckj) the ribs are less prom~ 

inent, bifurcate lower on the flanKs, and bifurcate less 

frequently. The ribbing at this size also resembles 

that on the inner whorls of 0. frearsi (Nikitin) ( 1881b, 

pl. 11, figs. 22a, b) . 

At diameters greater than 30 mm 0. multiforme contrasts greatly with P. grewinghi by acquiring stouter, 

more involute whorls, a definite umbilical edge, blunter 

ribbing, and distinct, small, comma-shaped umbilical 

tubercles. It retains its inclined ribbing on the flanks, 

arched ribbing on the venter, and fairly open umbilicus, which features characterize the subgenus Paracadoceras. At diameters greater than 45 mm the ribbing 

is indistinct on the umbilical wall, most o:f the primary 

ribs bifurcate and there are :few short intercalated ribs. 

Furcation occurs at about one-fourth o:f the height of 

the flanks rather than at the umbilical tubercles. The 

ribbing fades out quickly at the anterior end o:f the 

penultimate whorl and only traces o:f ribs are visible at 

the posterior end o:f the body chamber. The commashaped tubercles persist longer but are faint on the 

anterior half of the body chamber. The sharp umbilical edge persists to the aperture. 

The suture line is much less disected than in most 

species of Oadoceras, but its proportions are typical. 

Dimensions in millimeters and ratios o:f the diameter are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Paratype (pl. 42, figs. 5, 7) ___________ 19 8. 5(0. 44) 7 (0.37) 6 (0. 31)-

Paratype (pl. 42, figs. 5, 7) ___________ 28 11. 5( 0 41) 9. 5( .34) 9 ( 0 32)-

Paratype (pl. 42, figs. 1, 2) .. _________ 36 15 ( .41) 14 ( .39) 8. 5( . 23} 

Paratype (pl. 42, figs. 1, 2) ___________ 47? 20 ( .42) 22 ( .47) 11 ( 0 23)-

Paratype (pl. 42, fig. 10) ______________ 71? 27 ( 0 38) ? 20 ( • 28)-

Holotype (pl. 42, fig. 8) ______________ • 111 41? ( 0 37) ? 39 ( .35)· 

This species is distinguished :from 0. tonniense Imlay 

by coarser ribbing, more distinct umbilical tubercles, a 

more sharply defined umbilical edge, a steeper umbilical 

wall, and a wider, deeper umbilicus. 

Holotype, U.S.N.M. 108085; paratypes, U.S.N.M. 

108086a,b,108087. 

Chinitna :formation, lower part of middle third at 

U.S.G.S. Mes. locs. 3019 and 21348. 

Cadoceras (Paracadoceras) tonniense Imlay, n. sp. 

Plate 43, figures 9-11, 13 

Six specimens of tliis species are on hand. Shell 

compressed, becoming less so during growth; whorls 

( 
ALASKA PENINSULA AND COOK INLET REGIONS 89 

ovate, higher than wide on innermost whorls, becoming 

wider than high on body whorl, widest at the umbilical 

edge, embracing about 'three~ fifths; flanks evenly 

rounded; venter highly arched in young, evenly arched 

in_adult, becoming broader during growth. Umbilicus 

fairly narrow but wide for genus; wall low and gently 

inclined, becoming steeper on body whorl; edge evenly 

rounded on inner whorls, abrupt on outer two whorls. 

Body chamber represented by about four-fifths of a 

whorl. 

The ribs are radial on the upper part of the umbilical 

wall, incline forward strongly on the flanks, and arch. 

forward gently· on the venter. Most of them bifurcate 

a little below the middle of the flanks, but some remain 

single. They are broad arid low on the flanks and 

venter and are slightly raised on the umbilical edge. 

The ribs begin to disappear on the venter of the penultimate whorl and are represented on the body whorl only 

by lines of growth and by weak swellings on the umbilical edge. The aperture is marked by a constriction that 

is strongly inclined forward. 

The suture line is similar to that of 0. oatostoma 

Pompeckj. The external saddle is not as deeply cut as 

in most species of Oadooeras. 

The dimensions in millimeters and ratios of the diameters are as follows : 

Specimen Diame· Whorl Whorl Umbilical ter height thiqkness width 

Paratypc (pl. 43, fig. 13) ______________ 57 23(0.40) 30 (0.52) 15. 5(0. 27) 

Holotypc (pl. 43, figs. 9, 11) __________ 60 26( .43) ·28 ( .47) 15 ( • 25) 

Holotypc (pl. 43, figs. 9, 11) __________ 92 40( .43). 48?( • 52) 24 ( .26) 

This species is characterized by its low, gently inclined umbilical wall and moderately compressed form. 

These features result in a more shallow and open umbilicus than in most species of 0 adooeras from Alaska. 

Among the Alaskan species, 0. wultiforme Imlay has 

coarser ribbing and a steeper umbilical wall. 0. harveyi (Crickmay) (1930, p. 55, pl. 16, figs. 1, 2) is very 

similar in whorl shape, umbilical width, and ornamentation (see pl. 43, fig. 12) to 0. tonnieme, but lacks a 

well-defined umbilical edge, has a steeper umbilical 

wall, and its ribs are a little wider spaced. The apparent loss of ribbing on the outer whorl that was suggested on the published photographs of 0. harveyi is 

not real, but due to weathering. The primary ribs 

actually bifurcate in a manner similar to that on 0. 

tonniense. 

Holotype, U.S.N.M. 108088; paratype, U.S.N.M. 

108089. 

Chinitna formation, lower two-fifths, U.S.G.S. Mes. 

locs. 20753,. 20762, 21324, 21331, 21328, 11049, and 21326. 

Ca.doceras (Paracadoceras) aff. C. tonniense Imlay 

Plate 43, figures 1, 4 

One septate mold differs from 0. tonnieme by having 

finer ribbing, a more open. umbilicus, and by lacking of 

a distinct umbilical edge except at its extre~e anterior 

end. It differs from 0. harveyi (Crickmay) by having 

a much wider umbilicus. It has been crushed laterally 

but appears to be more compressed than either of these 

species. 

Figured specimen, U.S.N.M. 108090. 

Chinitna formation, lower ·part of middle third at 

U.S.G.S. Mes. loc. 3019. 

Cadoceras (Paracadoceras) chisikense· Imlay, n. sp. 

Plate 43, figures 5, 6 

This species is based on one specimen that has been 

partly crushed laterally, but which shows distinctive 

ribbing unlike any other in the Alaskan collections of 

the Survey. 

Shell moderately compressed; whorls ovate, becoming wider than high in adult, widest at the umbilical 

edge, e~bracing about two-thirds; flanks evenly 

rounded; venter evenly arched, becoming broader during growth. Umbilicus moderate in width; wall 

moderate in height, very steep ; edge evenly rounded on 

inner .whorls, becoming abrupt on outer two whorls. 

. Body chamber incomplete but represented by at ·least 

half a w hor I. 

The ribs are nearly radial on the upper part of the 

umbilical wa:ll, incline forward strongly on the flanks, 

and arch forward gently on the venter. The innermost whorls, as exposed in the umbilicus, have fine, 

closely spaced ribbing. On the penultimate whorl the 

ribs are moderately spaced. They are high and nar~ 

row on the umbilical edge and on the lower part of the 

flanks, but are low and indistinct on the venter. Anteriorly the ribs become stronger on the umbili~al edge 

and weaker on the venter. On the posterior end of the 

penultimate. whorl the ribs consist mostly of long unbranched primaries alternating with short secondaries, 

but some of the latter are indistinctly united with the 

primaries a little below the middle of the flanks. On 

the anterior end of the penultimate whorl the lower 

part of the flanks has pronounced primary ribs, and 

the venter is nearly smooth. The body chamber is 

marked only by strong, rather widely spaced primary 

ribs. 

The suture line is poorly preserved. 

The holotype is too crushed for accurate measurements. 

Among Alaskan forms of 0 adooeras this species 

most nearly resembles 0. moffiti Imlay, but may be 

distinguished by its deeper umbilicus, finer ribbing, 

and by the disappearance of secondary ribbing on the 

body whorl. It has a general resemblance to 0. harveyi 
90 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED. STA,T:ms AND ALASKA 

Crickmay .(1930, p. 55, pl. 16, figs. 1, 2), but. its body 

whorl has wider-spaced primary ribs and a distinct umbil~cal_ edg·e. It, also, greatly resembles 0. elatmae in 

form and sculpture,- but has somewhat weaker, more 

widely :spaced ribbing; · 

Holotype, U:S.N.M. 108091. 

· · Chirtitna. ·formation, basal part, U.S.G.S .. Mes. loc. 

10250. 

Subgenus Stenocadoceras Imlay, n. subgen. 

(See p. 46) 

Cadoceras (Stenocadoceras) multicostatum Imlay, n. sp. 

Plate 44, figures 1-16 

This species is represented by 62 specimens. Shell 

discoidal, compressed; whorls subovate, considerably 

~igher than wide in young forms, about as wide as high 

in adults, embracing about three fourths; flanks nearly 

flat in young, gently con~ex in adult; venter narrow, 

but becoming less so with growth. Umbilic.us narrow; 

wall low andnearly vertical in young, becoming moderately high and vertical in adult; umbilical edge 

rounding abruptly into flanks. Body chamber represented by about four-fifths of a whorl. 

The ribs are fine, closely spaced, and slightly stronger 

on the venter than on the flanks. They recurve backward on the umbilical wall, incline gently forward on 

th.e flanks, .and arch· forward slightly on the venter. 

On the smaller whorls most of the ribs branch between 

the lower third and the middle of the flanks, but some 

remain simple. During growth single ribs become 

fairly numerous, some ·short intercalary ribs appear, 

many of the furcation points become indistinct, and the 

rib.s tend to· become weaker near the umbilicus and 

stronger on the venter and the upper part of the flanks. 

Near the body chamber the ribbing weakens considerably and the body chamber appears to be fairly smooth. 

However, its flanks bear very fine, closely spaced, forwardly ihclined ribs and its venter has low, broad swellings that are much less numerous than the flank ribs. 

The mouth border is marked by a rather shallow, moderately inclined constriction. 

The suture line is characterized by both the first· and 

second lateral lobes being irregularly trifid and rather 

slender. . 

· The dimensions of the types in millimeters and in 

ratios of the diameter are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

-- Paratype (pl. 44, figs. 7, 8, 12) ________ 28 13(0. 46) 8.5(0.30) 6(0.21) 

Paratype (pl. 44, fig. 11) _____________ 41 19( .46) 13.5( .33) 8( .19) 

Holotype (pl. 44, figs. 1, 2) ___________ 51 24( .47) 17 ( .33) 11 ( . 21) 

Para type (pl. 44, figs. 4, 5) __________ 67 30( .45) 27 ( .40) 14( • 21) 

Paratype (pl. 44, fig. 14) _____________ 76 36( . 47) 37 ( .48) 20( .26) 

The· immature forms of 0. multicostatum greatly 

resemble Pseudocadoceras petelini ( Pompeckj·) ,. but 

have flatter. flanks, a slightly Sina_ller umbilicus, and 

finer, denser ribs that tend to become faint near t_he 

umbilicus instead of becoming more prominent, p 0 nanseni (Pompeckj) (1899, p. 86, pl. 2, figs. 1-3, 5, 6, text 

figs. 16, 17; Spath, 1932;p. 62, pl. 9, fig. 2, pl. 11; fig. 4) 

has more widely ·sp-aced ribs and a rounder venter. 

0. striaturn Imlay, described herein, has a much more 

compressed form and a smaller umbilicus. 0. stenolo:-

bum var. densicostatu1n Spath ( 1932, p. 62; Nikitin, 

1881b, p. 121, pl. 12, figs. 28-30) h_as a less narrowly 

rounded ·venter and de.velops an umbilical rim. 

Holotype, U.S.N.M. 108092; paratypes, U.S.N.M:. 

108093,108094a-d,108095a-c. 

Shelikof formation, middle member, U.S.G.S. Mes. 

locs. 3105, 10813, 12380, and 12386. Chinitna formation, 

upper two-thirds, U.S.G.S. Mes. locs. 2991, 3016, 3028, 

302~, 10978, 21290, 21342, 21346, 21347, 21776, 2177J, 

21778. Most of .the collections from the Chinitna formation are from its upper 400 ft. The specimens 

assigned to this species from locs. 3028 and 3029 in the 

middle part of the Chinitna formation, are less than 25 

mm in diameter, and may not be correctly identified. 

Cadoceras (Stenocadoceras) striatum Imlay, n. sp. 

Plate 45, figures 4-7 

Four specimens are .assigned to this species. Shell 

discoidal, compressed; whorls elliptical, considerably , 

higher than wide at all growth stages, embracing about 

four-fifths·; flanks flat, venter narrow. Umbilicus narrow, wall low and steep, edge rounding evenly. Body 

chamber represented by three-Jourths of a whorl. 

. The ribs are fine, closely spaced, .and slightly stronger· 

on the venter than on the flanks. Up to diameters of 

about 65 mm the ribs curve backward on the umbilical 

wall, incline gently forward on the flanks, ·and arch 

forward on the venter. Most of the ribs branch between 

the lower third and the middle of the flanks, but some 

remain unbranched, and there are many short intercalary ribs. The furcation points become less distinct 

during growth. At diameters greater than about 65 

mm the umbilical wall is smooth, the primary ribs split 

up· on the lower third of. the flank into fine, threadlike 

rigs and striae that pass into low, distinct ribs on the 

upper part of the flanks .and on the venter. The body 

chamber is nearly smooth but when viewed under oblique light the surface exhibits faint, forwardly inclined striae. The aperture, partly preserved on the 

largest specimen (side not figured), is marked by a 

shallow inclined constriction. 

The suture line is rather indistinct. 
)· 

ALASKA PENINSULA AND COOK INLET REGIONS 91. 

·T~1e dimensions of the types in millimeters and in 

ratios of the diameter are as follows : 

Specimen Diamc- Whorl Whorl Umbilical ter height thickness width 

Rolotypc (pl. 45, fig. 6) ______________ 67 34(0.50) 20(0.30) 9.5(0.14) 

Paratypc (pl. 45, figs. 5, 7) ___________ 135 65( .48) 44( .32) 21 ( .15) 

This species greatly resemble 0. multico8tatum but 

has a smaller umbilicus, its w11orl section remains high 

and narrow during growth, and its ribbing is a little 

finer. 

Holotype, U.S.N.l\1:. 108096; paratypes, U.S.N.M. 

108097a, b. 

Chinitna formation, upper part_ of lower third, 

U.S.G.S. Mes. loc. 21291. 

Cadoceras (Stenocadoceras) iniskinense Imlay, n. sp. 

Plate 46, figures 1, 4-9 

This species is represented by 23 specimens, but only 

3 show the adult character. Shell discoidal, compressed; whorls elliptical, higher than wide at all 

growth stages, embracing about four-fifths; flanks 

flattened; venter narrow~y rounded but not sharpened. 

Umbilicus narrow;. wall low and steep in young, moderately high and vertical in adult; edge evenly rounded 

~n young, becoming abruptly rounded in adult. Body 

chamber incomplete, but represented by at least an 

entire whorl. · 

The dbbing is fairly coarse. On th.e immatu~e forms 

the ribs are thin and high on the umbilical edge and 

flanks and are thick and moderately high on the venter. 

This condition exists as far as the anterior end of the 

penultimate whorl where the ribbing becomes less vigorous on the middle part of the flanks. Reduction in 

ribbing continues on the body whorl whose anterior 

end is marked only by faint broad ribs and striae and 

weak comma-shaped umbilical swellings. T;he ribs 

curve backward on the upper part of the umbilical wall, 

incline forward gently on the flanks, and arch forward 

slightly on the venter. On forms up to a diameter of 

about 25 mm about half the ribs bifurcate on the lower 

third of the flanks. The remaining single ribs alternate regularly with intercalary ribs that begin on the 

lower third of the flanks. At. greater diameters most . 

of the ribs remain single and are separated by 1 or 2 intercalary ribs that begin between t)le lower third and 

the middle of the flanks. 

The sut~re line is not well en.ough preserved ~o illustrate. 

Dimensions in millimeters and ratios of the diameters 

are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Paratype (pl. 46, fig. 6)-------------- 24 11.5(0.48) 8.5(0.35) 4:5 (0.18) 

Holotype (pl. 46, figs. 7, 9) ___________ 127 58' ( .45) ? 24 ( .19) 

The immature forms of the species have ribbing <?Omparable in coarseness with P. grewingki (Pompeckj), 

. but are distinguishable by a much narrower umbilicus 

and a more eyenly rounded venter. P. 8chmidti 

(Pompeckj) has· a wider umbilicus and slightly finer 

ribbing. The adult form differs from 0. 8tenolob'll!l11; 

(Keyserling) (Sokolov, 1912; p. 52, pl. 1, fig. 4) by its 

weaker ribbing. In this respect it is intermediate between 0. stenolobwm and 0. gtenoloboide Pomp.eckj. 

Holotype, U.S.N .M. 108098 ; para types, U.S.N .M. 

108099a, b, 108100. 

Shelikof formation, lower ·and middle members, 

U.S.G.S. Mes. locs. 3105, 3106, 3117, 10812, 10824. 

Chinitna formation, upper half, locs. 3018, 3029, 3030, 

10990. 

Cadoceras (Stenocadoceras) bowserense Imlay, n . .sp. 

Plate 43, figures 2, 3, 7, 8 

This species is known by only two specimens. Shell 

discoidal, compressed; whorls subquadrate, higher than 

wide, embracing about five-sixths; flanks flattened, 

venter evenly rounded. Umbilicus narrow; wall low. 

and vertical, edge abruptly rounded. Incomplete body 

chamber represented by two-thirds of a whorl. 

The ribs are weak, closely spaced, and a little stronger 

on the :venter than on the flanks. They incline forward 

rather strongly on the flanks ·and arch forward gently 

on the venter. They a:fise on the upper part of the 

umbilical wall, pass into weak tubercles on the umbilical 

edge, and then divide at or just above the tubercles into 

two or three secondary ribs. In addition there are a 

few intercalary ribs that begin on the lower fourth of 

the flanks. On the. body chamber the ribbing changes 

int~ fine, forwardly inclined striae. 

The suture line is typical of the genus and shows no 

unusual feature. · 

The holotype at a diameter of 63 mm has a whorl 

height of 30 mm, a whorl thickness of 28 mm, and an 

umbilical width of 10.5 mm. 

This species represents the only compressed Oadoceras 

found thus far in the lower third of the Chinitna formation. Among the Alaskan species it resembles 0. 

stenoloboide fompeckj in general form, but is ·much 

finer ribbed. 0. milaschevici (Nikftin) (1881a, pp. 66, 

67, pl. 3, figs. 25-27) differs by having a trigonal instead of a subquadrate whorl section. 

Holotype, U.S.N.M. 108101; paratype, U.S.N.M. 

108102. 

Chinitna formation, near. base, U.S.G.S. Mes. loc. 

11041. 
92 CALLOVIAN (JURASSIC) A:M::M:ONITES FROM THE UNITED STATES AND ALASKA 

Cadoceras (Stenocadoceras) stenoloboide Pompeckj 

Plate 46, figure 3; plate 47, figures 1-15 

Oadoceras stenoZoboide Pompeckj. Russ. K. Min. Ges~ll. St. 

Petersburg Verh., ser. 2, Band 38, p. 255, pl. 7, figs. 2a-e, 3a, b, 

1900. 

This species is represented in the Survey collections 

by about 60 specimens that show all the growth 5tages. 

Shell discoidal, compressed; whorls ovate, a little higher 

than wide at all stages but becoming lower during 

growth, embracing about four-fifths; flanks flattened 

in young, becoming gently convex in adult; venter 

evenly rounded, becoming broader during growth. 

Umbilicus narrow; wall low and vertical; edge evenly 

rounded in young, fairly abrupt in adult. Body chamber represented by four~fifths of a whorl. 

The ribs are sharp on the flanks, fairly thick on the 

venter, and are moderately spaced. They curve backward on the upper part of the umbilical wall, incline 

gently forward on the flanks, and arch forward slightly 

on the venter. On the umbilical edge they rise into 

weak comma-shaped swellings that persist to near the 

end of the body chamber but can scarcely be classed 

as tubercles. On the smallest whorls most ribs bifurcate 

on ·the lower third of the flanks, but at diameters greater 

than about 30 mm the furcation points become indistinct 

and some ribs remain unbranched. . In addition· there 

are many short ribs that begin between the lower third 

and the middle of the flanks .. As a result, at a diameter 

of 52 mm there are about 21h times as many ribs on 

the venter as on the lower third of the flanks. The 

ribbing becomes lower and less distinct on the anterior 

end· of the penultimate whorl and on the body whorl 

is very low, widely spaced, and obvious only under 

oblique light. The body whorl also bears some striae 

that -\vith the low ribs are inclined strongly forward. 

The aperture is marked on the internal mold by a shallow forwardly inclined constriction that is not apparent 

where the shell is preserved. 

The suture line is similar to that of 0. multicostatwm 

but is less dissected and the lobes are wider. 

Dimen5ions in millimeters and ratios of the diameters 

· are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Plesiotype (pl. 47, figs. 7, 8) __________ 26 12(0.46) 9 (0.34) 5 (0.19) 

Plesiotype (pl. 47, fig. 12) ____________ 31 15( . 48) 11 ( .35) 6 ( .19) 

Plesiotype (pl. 47, figs. 3-5) __________ 51 25 ( .49) 22 ( .43) 9.5( .18) 

Plesiotype (pl. 4 7, figs. 10, 14) ________ 57 26( .45) ~5( .39) 11 ( .19) 

Plesiotype (pl. 47, figs. 13, 15) ________ 100 49( .49) 47 ( .47) 20 ( .20) 

This species differs from 0. stenolobum (Keyserling) (Nikitin, 1881b, p. 121, pl. 12, figs. 28-30; Sokol?v, 

1912, p. 52, pl. 1, fig. 4) by its flatter flanks and much 

finer ribbing. It di:ffe~s from 0. iniskinense Imlay by 

its Jess compressed form and finer rihbing. 

Plesiotypes, U.S.N.M. 108103a, b, 108104--108109. 

Shelikof formation, middle member and top of lower 

member, U.S.G.S. Mes. locs, 2943, 3117, 10822, 10824, 

12386, 12387, 12408, 21354, 21356, 21357, 21362. Chinitna formation, upper two-fifths, locs. 2921, 3030, 

10990, 11052a,20757,21342, 21777. · 

Cadoceras (Stenocadoceras) pomeroyense Imlay, n. sp. 

Plate 45, figures 1-3; plate 46, figure 2 

Only one specimen of this species is known. It consists of the penultimate whorl and the beginning of the 

body chamber. Form moderately compressed; whorls 

subtrigonal on inner whorls, wider than high, becoming 

subovate on body chamber, embracing about five-sixths; 

flanks somewhat flattened and sloping from umbilical 

edge to narrowly rounded venter .. · Umbilicus fairly 

narrow, crater-like; wall moderately high and steeply 

inclined; edge abrupt on penultimate whorl and sharp 

on body chamber. Length of body chamber unknown. 

On the innermost whorls exposed in the umbilicus 

the ribs are sharp,., radial, and begin at the line of 

involution. At the beginning of the last septate whorl 

the ribs begin to disappear from the lower part of the 

umbilical wall and at end of the septate whorl the wall 

is completely smooth. The ribs incline forward 

strongly on the flanks, bifurcate on the lower onefourth to one-third of the flanks, and arch forward in 

an angular manner on the venter. They are high and 

narrow on the umbilical edge and a little lower and 

broader on the flanks and venter. They are vigorous 

at the beginning of the last septate whorl but gradually diminish in strength anteriorly and are completely 

absent at the beginning of the body chamber. 

The suture line is poorly preserved .. 

Dimensions in ·millimeters and ratios of the diameters are as follows : 

Specimen Dlame- Whorl Whorl Umbilical ter height thickness width 

Holotype (pl. 45, figs. 1-2) ____________ 62 27(0. 43) 39(0.63) 14(0. 22) 

Do _______________________ -------- 77 32( .41) 49( . 63) 20( • 26) 

This species is characterized by the vigorous, strongly 

inclined ribbing and subtrigonal shape of its penultimate whorl and by its fairly stout form. It has a wider 

whorl section and stronger ribbing than any other 

Alaskan sp~cies of Stenocadoceras. OadoceratS stenolobum (Keyserling) (Sokolov, 1912, p. 22, 52, pl. 1, 

. fig. 4) from northern Russia is more compressed, has 

finer ribs that branch higher, and is much larger. The 

adult of 0. nildtini Sokolov (1912, pp. 24, 53, pl. 1, figs. 

3 a-d, pl. 3, fig. 13) is very similar to 0. pomeroyense in 

stoutness and in character of ribbing, but the immature 

forms are much more compressed and the rib branching occurs consistently much higher on the flanks. 

·( 

< 

( 
.. 

ALASKA PENINSULA AND COOK INLET REGIONS 93 

·Holotype, ·U.S.N.M. 108110. 

Chinitna formation, upper third, U.S.G.S. Mes 

loc. 22415. 

Genus Pseudocadoceras Buckman 1919 

Pseudocadoceras petelini (Pompeckj) 

Plate 48, figures 1-6, 15 

Oaaoceras petelini Pompeckj, Russ. :K. Min. Gesell. St. Petersburg Verh., ser. 2, Band 38, p. 267, pl. 6, figs. 4-6, 1900. 

Pseudocadocems petelini . (Pompeckj). Buchman, Yorkshire 

type Ammonites, vol. 2, p. 121 c, 1919. 

Pseuaocadoceras petelini (Pompeckj). Spath, Meddelelser om 

GrS!Snland, Band 87, no. 7, p. 62, 1932. 

The collections in hand contain 30 specimens of this 

species. Shell discoidal, compressed; whorls subovate, 

considerably higher than wide, becoming lower during 

growth, thickest on lower third of fla!lks, embracing 

two-thirds; flanks flattened on inner whorls, becoming 

gently convex on outer whorls, converging above into 

narrow venter. Umbilicus fairly narrow; wall low and 

nearly vertical, rounding abruptly into flanks. Body 

chamber represented by about half a whorl, but· aper-

,ture is not preserved. 

The r.ibs on the inner whorls are fairly 'strong and 

sharp, are separated by interspaces a little wider than 

themselves, mostly bifurcate below the middle of the 

flanks, curve backward on the umbilical wall, incline 

slightly forward on the flanks, and arch forward on the 

venter. During growth the primary ribs become wider 

spaced aud higher and sharper on the lower fourth of 

the flanks, many of the secondary ribs become indistinctly connected with the primary rib, and intercalary 

ribs appear. As a r·esult, on the largest whorls the 

ribbing consists 1nostly of· unbranched primary ribs 

separated by two intercalary ribs that extend slightly 

below the. middle of the flanks. On the venter the 

strength and spacing of all ribs are about equal. 

The suture line is much simpler than in species of 

Oadocaras, but the proportions are similar. 

Dimensions in ml.llimeters and ratios of the diameter 

are as follows : · . 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

-- Plcsiotypc (pl. 48, figs. 5, 6) __________ 32 14(0. 44) 10(0. 31) 8(0.25) 

Plcsiotypo (pl. 48, figs. 1, 2) __________ 23.5 11( . 46) 7.5( .32) 5( . 21) 

This spe~ies differs from P. grewingki (Pompeckj) 

by having flatter whorls, finer ribbing, fewer single 

ribs on the immature whorls, and a narrower umbilicus. 

It differs from P. nanseni (Pompeckj) (i899, p. 86, pl. 

2, figs. 1-3, 5, 6, textfigs. 16, 17) by having more closely 

spaced ribbing and a narrower venter. It greatly resembles immature forms of 0. multicostatum Imlay described herein, but may be distinguished by coarser, 

more widely spaced ribbing. 

Plesiotypes, U.S.N.M. 108111-108113. 

Shelikof formation, middle member, U.S.G.S. Mes 

locs. 3113, 10822, 12385, 12386 and 12387 in the Puale 

Bay area. -

.Pseudocadoceras grewingki (Pompeckj) 

Plate 49, figures 1-12 

Ammonites b{plex ( ?) Sow. Zieten. Grewingk, Russ. 'K. Min 

Gesell St. Petersburg Verh. 1948-1849, pp. 273, 274, pl. 4, 

. figs. 2a-c, 1850. 

Ammonites milletianus D'Orbigny. Eichwald, Halbinsel Mangi 

schlak und die aieutischen Inseln, pp. 14~146, pl. 9, fig. 4 

not 3, 1871. 

Oadoceras grewingki Pompeckj, Russ. K. Min. Gesell. St. Peters 

burg Verh., ser. 2, Band 38, p. 258, pl. 6, fig. la-d, not 2a-c 

1900. 

Pseudocadoceras grewingki (Pompeckj). Buckma,n, Yorkshire 

type Ammonites, Vol. 2, p. 14, 1918; same volume, 1919, p 

12lc. 

Pseuaocaaoceras grewingki (Pompeckj). Spath, Meddelelser 

om GrS!Snland, Band 87, no. 7, p. 62,1932. 

This species is represented by about 100 specimens in 

the Geological Survey's collections. Shell discoidal 

compressed; inner whorls subovate, considerably higher. 

than wide; outer whorls only slightly higher than wide 

thickest on lower part of flanks, embracing froin one 

half to three-fifths; flanks flattened, converging above 

into na.rro~ venter. Umbilicus fairly wide; wall low 

and. steep, rounding abruptly into flanks. Body chamber on the largest specimens represented by about half 

a whorl but aperture not preserved. 

The ribs are strong and sharp. They are. closely 

spaced on the inner whorls, but become fairly widely 

spaced on the outer whorl. They curve backward on 

the umbilical wall, incline gently forward on the flanks 

and arch forward rriore strongly on the venter. They 

are highest ·and sharpest on the lower half of the flanks 

and become rather broad on the venter. Bifurcation 

occurs fairly regularly a little below the middle of 

the flanks. On the inner whorls the secondary branches 

are generally distinctly un:ited with the primary ribs. 

Anteriorly one of the branches, usually the· anterior, 

becomes loosely united with the primary rib. Some 

ribs remain unbranched. 

The suture line has been well described by Pompeckj. 

Dimensions in millimeters and ratios of the diameter 

are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Lectotype ______________ ~ ______________ 32.3 14 (0.46) 12. 8(0. 40) 9(0.28) 

Plesiotype (pl. 49, figs. 11, 12) _________ 43 17.5( .40) 14 ( .32) 10( .23) 

Plesiotype (pl. 49, figs. 3, 4) ___________ 32 13. 5( • 42) 11 ( .34) 9( .. 28) 

Plesiotype (pl. 49, fig. 10) _____________ 21 10 ( . 47) 6. 5 ( . 31) 5(. 24) 

On the basis of the material now in hand it is evident that the specimens included by Pompeckj (1900, 

pp. 258-263, pl. 6, figs. 1"""'3) in his Oadoceras greu,ingki 
94 CALLOVIAN (JURASSIC) AMMONITES FROM 'l'HE UNIT-ED· STATES AND ALASKA 

really represent two species. As Pompeckj did not 

!:?elect a holotype; the specimen represented by his figure 

la-d, which was fir5t figured by Grewingk (1850, pl. 4, 

figs. 2a-c) , is hereby designated the lectotype of P. 

grewingki (Pompeckj). The specimen figured by Pompeckj on his pl.- 6, fig. 2a-c is herein referred to a new 

species, Pseudooadooeras orassioostatum Imlay, which 

differ~ from P. grewingki by its coarser, more widely 

spaced ribbing, more inflated whorl section, and deeper 

iuribilicus. P. grewingki has ribb~ng very similar to 

that of Pseudooadooeras orbignyi ·Maire ( 1932, p. 11; 

1938, pl. 1, fig. 3; D'Orbigny, 1848, pl. 179, figs. 7, 8), 

but itl? venter is less narroweq,, its whorl section wider, 

and it has more single ribs. It differs from Pseudooadoceras boreale Buckman (Hh9, pl. 121b) by having a 

much wider umbilicus, a rounder venter, and more 

widely spaced ribs which branch lower on the flanks. 

It differs.from P.? oonoinnum Buckman (1927, pl. 735) 

by having thinner ribs that are more widely spaced. 

Plesiotypes, U.S.N..M. 108114, 108115a, b, 108116, 

108117. 

· Chinitna formation, middle two-thirds, U.S.G.S. Mes. 

iocs. 2921, 3018, 3028, 3029, 3030, 20757, 20763, 21344, 

21348, 22429, 22432, 22435, 22451, and 22452. Shelikof 

formation, middle member and top of lower member at. 

U.S.G.S. Mes. locs. 3105, 3113, 10813, 10822, · 12386, 

21358, 21362. 

:Pseudocadoceras crassicostatum Imlay, n. sp. 

Plate 49, figures 19, 20, 22-24 

Ammonites milletianus D'Orbigny. Eichwald, ... Halbinsel 

. Mangischlak und die Aleutischen Inseln, pp. 145., 146, pl. 

9, fig. 3, 1_871. 

Oadoceras grewingki Pompeckj, Russ.-K. Min. Gesell, St. 

Petersburg. Verh., ser. 2, Band 38, p. 258, pl. 6, figs. 2a-c, 

not la-d, 1900. 

This species is represented in available collections 

by four sp~cimens, of which two are fragments of the 

outer whorl. Shell discoidal, compressed; whorls 

ovate, wider than high in early stages, becoming slightly 

higher than wide in adult, thickest il.ear the umbilicus, 

embracing a little more than one-half; flanks convex; 

venter broadly rounded on inner whorls, somewhat 

narrowed on outer whorl. Umbilicus wide, wall moderately high and steep. Body chamber represente~ by 

at least half a whorl. 

The ribs are very strong, widely spaced, sharp .on the 

internal molds, but well rounded where the shell is 

preserved. . They curve backward on the umbilical wall 

and incline gently forward on the flanks and venter. 

About two-thirds of the primary ribs bifurcate below 

the middle of the flanks and the remainder- remain 

single. The points of furcation are ·commonly· indistinct, particularly on the body whorl. 

The suture line differs from that of P. grewingki 

(Pompeckj) by having .broader saddles and a more 

slender first htteral lobe. 

Dimensions in millimeters and ratios of the diameter 

are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype (pl. 49, ~gs. 22, 24) _________ 41 18(0. 44) 16. 5(0. 40) 12. 5(0.30) 

Paratype (pl. 49, figs. 19, 20) _________ . 33 15( • 45) 12( .36) 8. 5( • 26) 

Pseudooadooeras.~ laminatum Buckman (1927, pl. 

727) appears to have a smaller umbilicus and thicker, 

more closely spaced ribs. The apparently small umbilicus on the specimen figured by Eichwald (1871, pl. 9, 

fig. 3) is probably a result of crushing, as many other 

specim~ns from Alaska show similar distortion. · 

Holotype, U.S.N.M. 108118; para type, U.S.N.M. 

108119. 

· Ch,initna formation, upper third, U.S.G.S. Mes. loc. 

11060. Shelikof formation, middle ·member, at locs. 

3105 and 12387. 

:Pseudocadoceras chinitnense Imlay, n. sp .. 

Plate 48, figures 7-10 

Four specimens of this species are in hand. Shell 

discoidal, compressed; whorls elliptical, much higher 

than wide, thickest on the lower third of the .flank, embracing two-thirds; flanks gently convex, converging 

above into narrow venter. Umbilicus fairly narrow;. 

wall low and nearly vertical, rounding fairly abruptly 

into flank. Body chamber represented by at least threefourths of a whorl but aperture is not preserved. 

The ribs on the penultimate whorl are high, sharp, 

and moderately spaced. The primaries curve backward on the umEilical wall, incline forward moderately 

on the flanks, and bifurcate at about one-third of the 

height of the whorl. The secondaries are nearly as 

strong as the primaries and arch forward .gently on the 

venter. Most forked ribs are separated by single; intercaliuy ribs. On the body whorl the primaries become higher and much more widely spaced, and are 

especially prominent at the furcati?n points. The posterior branch of many forked ribs is indistinctly connected with the primary rib, so that in places there are 

unbranched primary ribs separated by two intercalary 

ribs that extend below the middle of the flanks. All 

secondary and intercalary ribs are of equal strength, 

are most pronounced on the venter, incline forward 

considerably on the upper parts of the flanks, and arch 

forward strorrgly on the venter. The strength of the 

ribbing increases steadily toward the anterior end of 

the body chamber. 

The suture line is poorly preserved. 

All the specimens have been crushed laterally, but 

the form shown on plate 48, figs. 7, 8 appears to be only 
ALASKA PENINSULA AND COOK INLET REGIONS 95. 

slightly deformed. At a diameter of 32 mm, its whorl 

height is 15 mm, its. wh.orl thickness 11 mm, and its 

umbilical width 8 mill. · 

. This species is characterized by the prominent, 

widely spaced primary ribs on the ·body whorl. P. 

m·assioostatu1n !:inlay has stouter whorls, a wider umbilicus, and fe,ver, stronger secondary ribs. P. petelini (Poinpeckj) is more compressed and has weaker, 

more Closely spaced ribbing. 

· Holotype, U.S.N.M. 108120; paratype, U.S.N.M. 

108121, 108122. 

Chinitna formation, upper two-fifths, U.S.G.S. Mes. 

locs. 2991, 10978, 21777 and 21778. 

Pseudocadoceras schmidti (Pompec~j) 

Plate 49, figures 17, 18 

Oaaoceras schmiati Po1npeckj, Russ. K. Min. Gesell. St. Petersburg Verb., ser. 2, Band 38, p. 265, pl. 5, figs. 3a-d, 4a, b, 1900. 

Pseuaocaaoceras schmiati (Pompeckj). Buckman, Yorkshire 

type Ammonites, Vol.2, p.121c, 1919. 

Only one .specimen has been found in the Survey collections from southwestern Alaska that agrees with 

Pompeckj's description and illustrations of 0. sohmidti. 

The anterior end of this specimen has been somewhat 

crushed laterally, but otherwise is excellently preserved. 

It may be described. as follows: 

Shell discoidal, compressed; whorls subquadrate, 

higher than wide, thickest on the lower third . of the 

flanks, embracing ·a little more than one-half; flanks 

flattened, venter evenly ro.unded. Umbilicus fairly 

wide; wall low and i1early vertical, rounding rather 

abruptly into flanks. Body chamber represented by 

about three-fourths of a whorl. 

The ribs are fairly closely spaced, sharp and elevated 

on the flanks, and thickened and less elevated on the 

venter. They curve backwa:r;d on the umbilical wall, 

incline forward gently on the flanks, and arch forward 

slightly on the venter. Most of the ribs fork near the 

middle of the flanks, but some remain simple. Anteriorly the furcation points become indistinct resulting in the alternation of long unbranched ribs with 

short secondary ribs. 

The suture line is only partly preserved, but agrees 

fairly well with those figured by Pompeckj. 

This species differs from P. grewingki by its flatter 

flanks, evenly rounded venter; finer, denser ribbing, and 

fewer single ribs. Its ribbing is similar to that of 0. 

inisk'inense, described herein, but it has a much wider 

umbilicus and a thinner whorl section. ·compared with 

P. na'liseni (Pompeckj) (1900, p; 86, pl. 2, figs. 1-3, 5, 6, 

text figs. 16, 17) it has a wider umbilicus and coarser 

ribbing. 

Plesiotype, U.S.N.M. 108123. 

Shelikof formation, middle member, U.S.G.S. Mes. 

loc. 10824. 

· Genus Kepplerites Neumayr 1892 . . 

Subgenus Seymourit.es Kilian and Reboul ~909 

Kepplerites (Seymourites) alticostatus Imlay, n. sp. 

Plate 48,· figures 11, 16 

Only three internal molds of this species are available. Form moderately stout; body whorl. subquadrate, slightly wider than high; flanks high, flattened, 

nearly parallel at posterior end of body whorl, gently 

convergent at anterior end, rounding· rather rapidly 

into venter, rounding abruptly into umbilical wall; · 

venter moderately wide, nearly flat along mid-line~ 

Umbilicus narrow on inner whorls, widens slowly on 

anterior half of body whorl until it embraces only threefifths of the penultimate whorl; wall moderate in 

height, vertical or nearly vertical. Body chamber· represented by a nearly complete whorl that is not contracted anteriorly. Aperture not preserved, but the 

weakness of the last rib suggests that the shell is· 

nearly complete. · 

The ribs are narrow and widely separated.. They 

are low on the septate part of the body whorl, but 

anteriorly on the body chamber rapidly become very 

high and sharp. The primary ribs on the septate part 

of the shell are scarcely stronger than the secondary 

ribs, but anteriorly become much higher. They are 

radi~l on the umbilical wall, curve backward on the 

· umbilical shoulder, curve forward gently on the flanks, 

and terminate at about one-third of the height of the 

flanks in tubercles. The latter are weak on the septate 

part of the shell but become prominent anteriorly on 

the body chamber. The secondary ribs curve forward 

on.the middle of the flanks, then recurve, and cross the 

venter transversely. Bifurcation and trifurcation are 

about equally common. In case of trifurcation one of 

the branches is generally indistin<?tly connected with 

the tubercle. In addition,· single intercalary ribs occur 

between most sets of branched ribs. The holotype has 

34 primary ribs and 109 secondary ribs on its body . 

whorl. 

The suture line is not well preserved. 

The dimensions in millimeters and ratios of the 

diameter are as follows : 

Specimen Diame- Whorl Whorl Umbilical • ter height thickness width 

Holotype (pl. 48, figs. 11, 16) _________ 93 33(0. 35) 35(0.37) 19(0. 20) 

Do ________________ "- _______ ------ 104 50( • 48) 52( .50) . 25( • 24) 

This· species is characterized by the high, thin ribbing 

on its body chamber. It differs also, from other Alaskan 

species described herein by its longer and less evolute 

body. chamber. It is distinguished from Kepplerites 

·zoganianus (Whiteaves) (1876, pl. 8, fig. 2), judging 

from a plaster cast of the type before me, by being more 
\ 

' 

96 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ;ALASKA 

compressed and less evol~te, and by having shorter 

primary ribs and much higher, thinner secondary ribs. 

K. plenus (McLearn) ( 1929, p. 5, pl. 1, fig. 1, pl. 2, figs. 

1, 2) has a thicker whorl section, is more evolute, and 

has less elevated ribbing. K. mclearni Imlay -(1948, 

p. 24, pl. 8, figs. 1, 2, 5, 7-10, Pl· 9, fig. 1) is more compressed and its ribbing is not as high and sharp. K. 

acuticostatwm Kobayashi (1947, p. 28, pl. 7, fig. 2) has 

similar high, thin ribs but is much more evolute. 

Holotype, U.S.N.M. 108124. 

Chinitna formation, lower third, at U.S.G.S. Mes. 

locs. 2992, 22431, and 22433. 

Kepplerites (Seymourites) tychonis Ravn 

Plate 48, figures 14, 17 

YMacrocephalites sp. cf. compressus (Quenstedt) Madsen, Meddelelser om GrfiSnland, Bind 29, p. 192, 1904. 

Kepplerites tychonis Ravn, Meddelelser om GrfiSnland, Bind 45, 

p.490,pl.37, fig. 1,1911. 

J(epplerites (Seymourites). tychonis Ravn. Spath, Meddelelser 

om GrfiSnland, Bind 87, pp. 83-87, pl. 23, figs. 1-3, pl. 24, fig. 

6, pl. 25, figs. 1-3, pl. 26, figs. 3, 6, 1932. 

Kepp~erites (Seymourites) cf. K. tychonis Ravn. Imlay, U. S. 

Geol. Survey Prof. Paper 214-B, p. 25, pl. 8, figs. 3, 4, 6, 1948 .. 

One specimen from Alaska agrees s~ cl~sely with K. 

tychonis in its compressed form and the dense, untuberculate ribbing of its outer whorls th~t specific identity 

seems certain. At a-diameter of 100 mm, which marks 

the beginning of the body chamber, the whorl height is 

51 mm, the whorl thickness is 45 mm, and the umbilical 

width is 14 mm. The umbilicus enlarges rapidly be-· 

yond this diameter, as shown by an impressed line on the. 

mold marking the position of the body chamber. This 

impressed line indicates that the body chamber occupied 

about three-fourths of a whorl. Only a part of the 

po_sterior end of the body chamber is preserved, but this 

part has ribbing similar to that on the penultimate 

whorl, which bears sharp, closely spaced primary and 

secondary ribs. . There are . three to · four secondary 

ribs to each primary, but abo:ut one rib out of four 

arises independently of the primaries along the ·zone of 

furcation. The ventral ends of the primaries are elevated but not distinctly tuberculated. Compared with 

the illustrated Greenland forms of K; tychonis, the 

Alaskan form appears to be more involute, but since it 

is septate to a larger diameter this difference is probably 

not important. Allowing for the· slightly larger size 

of the Alaskan form, its degree of involution greatly 

resembles that of some forms from Greenland (Spath, 

. 1932, pl. 26, fig. ~; Ravn, 1911, pl. 37, fig. 1a). Also, in 

this regard Spath (1932, p. 86) notes that some Greenland specimens are much more involute than others. 

Plesiotype; U.S.N.M. 108125. 

Chinitna formation, near base, U.S.G.S. Mes. loc. 

21287; probably represented at Mes. loc. 20755. 

Xepplerites (Seymourites) multus (McLearn) 

Plate 51, figures 1, 4 

Seymo,urites multus McLearn, Canada Nat. Mus. Bull. 54, p. 7, 

pl. 3, fig. 2, 1929. 

- The Alaskan collections contain two specimens of 

this speCies. These are only about two-thirds as large 

as the holotype, but as they agree very closely in whorl 

shape and ornamentation the difference in size is discounted. Among other ammonites, for example some 

species of Scaphites, even greater size differences have 

been noted. · 

Form stout; whorls ovate,_ wider than high; flanks 

and venter evenly rounded. Umbilicus narrow on inner whorls, enlarges very rapidly on anterior half of 

body whorl; wall high, vertical on lower part, steeply 

inclined above, rounding abruptly into flanks. Body 

chamber represented by at least half a whorl. Aperture not preserved. 

The ribbing of the inner whorls is not known. On 

the penultimate whorl, exposed in the umbilicus, the 

ribbing is fine and dense. Four· or five secondary ribs 

branch from tiny tubercles at the ends of the primary 

ribs. On the body whorl the primary ribs are moderately strong, angular in cross-section, radial on the urn-_ 

bilica1 wall, inclined gently forward on the flanks, and 

terminate in small, acute tubercles at about one-third .of 

the height of the flanks. From the tubercles arise 

three, or generally four secondary ribs, and between the 

branched ribs are some intercalary ribs. This results 

in about five secondary ribs for each primary rib. The 

secondary ribs are fine, low, and fairly closely spaced, 

although · separated by somewhat wider interspaces. 

They incline forward rather strongly on the· ml.ddle of 

the flanks, then recurve, and cross the venter transversely. 

The suture line cannot be determined on the Alaskan 

. specimens, owing to crushing of the septate part of the 

body whorl. 

The dimensions in millimeters and ratios of the diameters are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype, Nat. Mus. Canada 9001. .. 145 55(0. 38) 62(0. 42) 50(0.34) 

Plesiotype (pl. 51, figs. 1, 4) __________ 110 40( ~ 36) 55( .50) 34( . 31) 

This species is characterized by its dense ribbing, 

rather inflated body whorl, and high umbilical wall. 

K eplerites mcevoyi (McLearn) ( 1928, p. 20, pl. 4, figs . 

1, 2) has similar ribbing but has a much more compressed body whorl. K. tychonis (Ravn) (1911, p. 490, 

pl. 37, fig. 1) has a much higher whorl section, denser 

primary ribbing, and weaker tuberculation. 

Plesiotype, U.S.N.~1. 108126. 
• 

ALASKA PENINSULA AND COOK INLET REGIONS 97 

Chinitna formation, top of middle third, U.S.G.S. 

Mes. loc. 20763. The holotype is from a sandstone bed 

near the top of the Y akoun formation on the northeast 

shore of Maude Island. 

Kepplerites (Seymourites) ingrahami (McLearn) 

l:'lnte 48, figures 12, 13; plate 50, figures 1-4 ;. plate 51, figure 2 

Yalcottnoceras ingrahami McLearn, Canada Nat. Mus. Bull. 54, 

p.9,pl. 7,figs. 1,2,1929. 

Yakotmites sp. A, Kellum, Daviess, and Swinney, U. S. Geol. 

Survey prelim. Report on geology and oil possibilities of 

the southwestern part of the ·wide Bay anticline, figs, 9a, b, 

1945. 

This species is represented in the Alaskan collections 

by 15 specimens of which 6 are fairly complete adults. 

Most of these retain much more of the shell than the 

holotype and consequently show the ornamentation to 

better advantage. The small specimen shown on plate 

48, figures 12, 13 may be a young individual of K. 

ingrahand. ' 

Form moderately stout; whorls subquadrate, a little 

wider than high; flanks flattened or nearly flat, becoming gently convex on the body chamber, rounding fairly 

abruptly into venter and umbilicus; venter flattened, 

especially on anterior end of body chamber. Umbilicus widens rapidly on anterior end of ultimate whorl; 

wall low, vertical at base, steeply inclined above. Body 

chamber represented by a little more than half a·whorl, 

becomes slightly contracted at anterior end. Aperture 

marked on internal mold by a broad forwardly inclined 

constriction which is scarcely apparent where the shell· 

is preserved. The constriction is followed by a low 

swelling that is abruptly truncated. 

The ribs are narrow, moderately elevated, and separated by much wider interspaces. They trend backward on the umbilical wall, curve forward strongly on 

th~ flanks, and cross the venter transversely. The 

primary ribs are thicker and higher than the secondary 

ribs and terminate at about two-fifths of the height of 

the flanks in small, compressed tubercles that are very 

small on the septate part of the shell and fairly prominent on the body chamber. Bifurcation and trifurcation are about equally common. Many rib branches 

are separated by intercalary ribs that begin along the 

line of tubercles. During growth the ribbing gradually 

becomes stronger and more widely spaced. This condition prevails nearly to the very edge of the aperture 

where only the last rib is weaker than the preceding 

ribs. The holotype has about 29 primary ribs and 115 to 

120 secondary ribs. The form illustrated on plate 50, 

figure 2 ·has about 30 primary ribs and 113 secondary 

ribs. The form illustrated on plate 50, figures 1, 3 has 

about 42 primary ribs and 123 secondary ribs. 

The suture line of the Alaskan specimen ·shown on 

plate 50, figures 1, 3 and plate 51, figure 2 resembles 

that of K. plenus (McLearn) (1929, pis. 1 and 2) but 

is less dissected. The first lateral lobe is about the same 

length as the external lobe and its median lobule is not 

especially elongate. The second lateral lobe is short 

and rather narrow. The saddles are much wider than 

the lobes. The external saddle is unequally divided by 

a long lobule into a large outer branch and a small, 

slender inner branch. The first lateral saddle is about 

two-thirds as large as the external saddle, is slightly 

longer than wid~, and is nearly symmetrical. The 

second lateral saddle is much smaller than the first, is 

nearly symmetrical, and has its inner branch on the 

umbilical margin. 

The dimensions in millimeters and ratios· of the diameters are as follows : 

.Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Holotype __ -------------------------- 105 35(0.33) 44. 6(0. 42) 33(0. 31) Holotype ____________________________ 78.3 46( • 58) 57. 3( . 73) ? 

Plesiotype (pl. 50, fig. 2) _____________ 95 32( . 33) 38( . 40) 32( . 33) 

Plesiotype (pl. 50, figs. 1, 2)--~------- 89 36( . 40) 43( . 48) 26( . 29) 

This species is characterized by its subquadrate whorl 

shape and flattened venter .. It differs from K. gitinsi 

(McLearn) (1929, p. 8, pl. 3, fig. 1, pl. 4, fig. 1, pl. 8, fig. 

5) by having denser ribbing, fewer secondaries per. primary rib, and a flattened venter. It is not as stout as 

l{. abruptus McLearn ( 1929, p. 9, pl. 5, fig. 1, pl. 6, figs. 

1, 2) and has fewer prin1ary ribs. K. tychonis Ravn 

(1911, p. 490, pl. 37, fig. 1) has much denser ribbing 

and a higher, rounder whorl section. 

Plesiotypes, U.S.N.M. 108127-108129. 

Chinitna formation, lower two-thirds, U.S.G.S. Mes. 

locs. 20763, 1207 4, and 22431. Shelikof formation, 

middle member, Mes. loc. 19793 .. The holotype is from· 

the upper part of the Yakoun formation at Alliford 

Bay in the Queen Charlotte Islands, British Columbia. 

Kepplerites (Seymourites) mcevoyi (McLearn) 

Plate 51, figures 3, 5-8 

Yakounitcs rncevoyi McLearn, Canada Geol. Survey Bull. 49, 

p. 20, pl. 4, figs. 1, 2, l928. 

This species is represented in the Alaskan collections 

by two specimens that show the characteristics of the 

outer two whorls. 

Fonn moderately stout, becoming compressed .on 

body chamber; whorls ovate, wider than high; flanks 

flattened on penultimate whorl, becoming gently convex 

on body whorl, merging gradually into evenly arched 

venter. Umbilicus narrow on inner whorls, widens 
98 CALLOVIAN (.JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

·Gonsiderably but slowly on outer whorl; wall-low, vertical, rounding rather abruptly into flanks. Body 

chamber represented by about half a whorl, eontracted 

considerably at anterior end._ Aperture marked on 

internal .mold by a broad, shallow, forwardly inclined 

~onstriction that is n~ar ly sm~o~h .. 

: The ribbing is rather fine ~nd dense. The primary 

ribs are narrow, angular, are radial_ or incline slightly 

backward on the umbilical wall, incline gently forward 

'on the flank~, and pass- into acute tubercles at about 

one-third of the height of the flanks. Ori the penultimate whorl the secondary ribs branch by threes or fours 

and on· the body whorl by fours or fives. In· addition 

there are many inter_ca:lary ribs that arise along the zone 

of tuberculation. The· secondary ribs are fine, low, and 

separated by somewhat wider interspaces. They in-

·cline :forward on-the flanks, but cross the venter transversely. The body"whorl of the:Iargest specimen (plate 

51, figures 6, 8) has 31 primary ribs and about 152 

secondary ribs. .. 

· The. sutur-e line is well shown on one of the Alaskan 

specimens. The first lateral lobe is a little longer than 

the· external lobe and has_ a long median lobule. The 

second lateral lobe is much shorter than the first. The 

saddles are a little wider than the lobes. The external 

.saddle is divided on its inner side by a long, narrow. 

.'lobule. The first lateral saddle is considerably smaller 

than the external saddle and is ·nearly- symmetrically 

'divided by ·a secondary lobule. The second lateral saddle is ventral to the umbilical edge. 

The dimensions in millimeters and ratios of the diam-

. eter are as follows : 

Specimen Diame- Whorl Whorl Umbilical ter height thickness width 

Plesiot'ype (pl. 51, figs. 5, 7) __________ 75 34(0.45) 41(0. 54) 15(0. 20) 

Holotype Nat. Mus. Canada 5018 ____ 95 35( .37) 41( .43) 26( • 27) 

Plesiotype (pl. 51, figs. 6, 8) __________ 96 38( .40) 44( .46) 29( .30) 

Plesiotype (pl. 51, figs. _6, 8) __________ ilO 37( . 33) 45( .41) 39( • 3~~ 

From these dimensions it ·appears that the. holotype 

is not quite as stout as the Alaskan specimens. However, the difference- is -not- gre~t and the holotype is 

clearly somewhat deformed. As regards ornamentation, there is no obvious difference. 

· K. moevoyi differs from [{. multus (McLearn) by 

having a much more shallow umbilicus, a more slowly 

enlarging umbilicus, and a thinner whorl section. Its 

shape somewhat resembles K. rosenhrantzi Spath (1932, 

p. 89, pl. 26, figs. la, b), but the ornamentation on its 

body chamber is much stronger and it remains tuberculate to the aperture. 

Plesiotypes, U.S.N.M. 108131, 108132. 

Chinitna formation, top of middle third, U.S.G.S. 

Mes. locs. 10992 and 20763. 

Kepplerites ·(Seymourites) gitinsi (McLearn) 

Plate 52, figures 1, 2 

Yalcounoc~ras gitinsi McLearn, Trans. Roy. Soc. Canada 3d ser ; 

vol. 21, sec. 4, p. 72, pl. 1, fig. 2, 1927. 

Yalcounoceras gitinsi McLearn, Canada Nat. Mus. Bull. 54, 

p. 8, pl. 3, fig. 1, pl. 4, fig. 1, pl. 8, fig: 5, 1929. 

This species is represented in the Alaskan collections 

by two specimens both showing part of the body chamber and one showing part of the penultimate ~horl .. 

The _adult whorl section appears to be a little wider 

than that of the holotype but the latter has been slightly 

crushed laterally. Otherwise the Alaskan specimens 

agree very well as regards ornamentation and· the 

rather slowly enlarging umbilicus. · 

. Plesiotype, U.S.N.M. 108130. 

Chinitna formation, upper part of middle third at 

U.S.G.S. Mes. loc. 29~1. 

Kepplerites (Seymourites) abruptus (McLearn) 

Plate 52, figures 3-6 

Yalcounoceras abr.uptum McLearn, Canada Nat. Mus. Bull. 54, 

p. 9, pl. 5, fig. 1, pl. 6, figs. 1, _2, 1929 .. 

Two adult and two septate shells from the Alaskan 

, Jurassic are assigned to this species. Form very stout 

on penultimate whorl and fairly stout on adult whorl. 

Whorls subquadrate, wider than high. Flanks nearly 

flat, rounding rather abruptly into umbi_lical wall, 

merging evenly into venter, which is broadly rounded 

on the penultimate whorl and flattened on the body 

whorl. Umbilicus narrow on the penultimate whorl 

but widens. rapidly on. the anterior half of the body 

whorl; wall low, vertical at base, steeply. inclined 

above. Body chamber represented by three-fourths of 

a whorl. Aperture marked on-internal mold by a broad 

forwardly inclined constriction that is followed by a 

promjnent swelling which is abruptly truncated. 

The ribs are high and thin where the shell is preserved but rather low and rounded on the internal mold. 

They incline backward on the umbilical wall, incline 

forward considerably on the flanks, and cross the venter 

transversely. The primary ribs are considerably 

thicker and higher than the secondary ribs and terminate at about one-third of the height of the flanks in 

radially compressed tubercles that are fairly prominent 

on the outer two whorls. Trifurcation is the common 

mode of branching a;nd most sets of branched ribs are 

separated by single intercalary ribs. During growth 

the ribbing gradually becomes more widely spaced on 

the venter but does not become stronger anteriorly. 

The holotype has about 35 primary ribs and 120 secondary ribs. The specimen shown on plate 52, figure 1, 

has about 40 primary ribs and 136 secondary ribs. ' 

The external saddle and the first lateral lobe of the 

specimen shown on plate 52, figures 3-5, are more 

.... 
•. 

. t 

.,. 

'l;.. 

I l 

ALASKA P:jl)NINSULA AND·· COOK INLET REGIONS 99 

slender than those of the holotype but were drawn at a 

considerably smaller diameter. 

The dimensions in millimeters and ratios of the diameter are as follows : 

Specimen Diame- Whorl Whorl Umbilical tor height thickness width 

Holotypc. ___________________________ 118 44(0. 37) 56(0. 47) 31(0. 26) Holotypo ____________________________ 98 46( .47) 54( • 55) 15( .15) 

Plcslotypo (pl. 52, fig. 6) _____________ 152 46( .30) ? 48( .31) Ploslotypo sarr.e __________________ 131 51( .39) 55?( . 42) 34( .26) 

Plcslotypo (pl. 52, figs. 3-5) __________ 76 40( .53) 47( .62) 11.5(.15) 

· K. abT'uptus (McLearn) is cliaracterized.by the small 

umbilicus and stoutness of its penultimate whorl, by 

the rapi4 umbilical enlargement on the anterior half 

of the body whorl, and by the sharpness of its ribbing~ 

Its ribbing is similar to that of K. gitin.si (McLearn) 

but its whorl section is much stouter. K. alticostatus · 

Imlay has a more compressed whorl section and more 

prom~nent ribbing on the body whorl. · 

Plesiotypes: U.S.N.M. 108133, 108134. 

Chinitna for:mation, lower third, U.S.G.S. Mes. locs. 

21330, 22433, and 22559. The holotype is from a sandstone bed near the top of the Y akoun formation on the 

northeast shore of Maude Island, British Columbia. 

Xepplerites (Seymourites) plenus (McLearn) 

Plate 49, figure 21 

Yakounites pZenus McLearn, Tran~. Roy. Soc. Canada Sd ser., 

vol. 21, sec. 4, p. _71, pl. 1, fig. 1, 1927. 

Seymo'ltrite8 plenu8 (McLearn); Canada Nat. Mus. Bull. 54, p. 5, 

pl. 1, fig. 1, pl. 2, figs. 1, 2, 1929. 

One specimen from southwestern Alaska is very similar to the holotype of K. plenus (McLearn) in size, 

stoutness of whorls, umbilical enlargement, and ornamentation. The tubercles may be a little more prominent but this probably reflects better preservation. 

Also, the anterior end of the body chamber has a flat-

. tened mid ventral area about 15 mm in width which 

cannot be demonstrated on the holotype because of 

crushing. 

It seems possible that K. plenus is a synonym of 

K. loganianus (Whitea ves) ( 1876,. ·p. 27, pl. 8, fig. 2), 

as they have very similar ornamentation. McLearn 

(1929, pp. 6, 7) notes that K. plenus "at the same stage 

of grow'th is somewhat larger and has relatively stouter 

whorls and somewhat smaller umbilicus than Seymouritesloganianus (Whiteaves) ." However, the difference 

in size does not seem to be beyond the.range in variation 

shown by other species of ammonites. The difference 

in stoutness may be explained by the obvious greater 

lateral crushing of the type of K. loganianus than· of 

K. plenu8. The difference in the width of the umbilicus 

is certainly minor as shown by actual measurements 

and by inspection of plaster casts of the types. · The 

settlement of possible synonymy· of- these species will 

-have to await additional collecting and comparing of 

large numbers of specimens, as the holotype of K. 

loganianus is too imperfect to warrant definite 

identification. 

Plesiotype, U.S.N.M. 108135 .. 

Shelikof formation, lower me~ber, at U.S.G.S. Mes. 

loc. 19793. · · · 

Genus Gowericeras Buckman 1921 

Gowericeras snugharborense Imlay,· n. sp . 

Plate ~3, figure 9 

The species· is represented· for certain only by the 

holotype, which has been crushed laterally. It appears 

that the whorl· section is ovate, probably· wider than 

high, and that·lhe flanks-and venter are evenly convex. 

The umbilicus is moderately wide and enlarges gradually during growth. The u~bilical wall· is fairly high, 

·-vertical at base, rounding rapidly into flanks. The 

body chamber is not completely preserved but is repr~­

sented by at least five-sixths of a whorl.· 

The inner whorls, exposed in the umbilicus, bear 

prominent, rather widely · spaced primary ribs that 

terminate in conical tubercles just below. the line of 

Involution. On the body whorl the primary' ribs are 

moderate in strength, are radial on· the umbilical wall, 

incline slightly forward on the lower third of th~ 

flanks, and terminate in small 9onical tubercles. . From 

. each of these arise three, or less commonly two, secondary ribs that are a little weaker than the primary ribs 

and are only slightly inclined forward. ·Between sets 

of branched ribs are generally single intercalary ribs 

that begin along the zone of furcation. It is estimated 

that the body whorl has 40 primary ribs arid 140 secondary ribs. The primary ribs are more closely spaced 

at the anterior end of the body whorl than at the posterior end . 

This species resembles Gowericeras toricellii ( Op.pe~) 

( 1862, p. 153; Buckman, 1922, pl. 292) but appears to 

have denser primary ribbing, more prominent tuberCles, and a thicker body whorl. G. childanum Buckcan ( 1923, pl. 404) has wider-spaced ribbing and a 

smaller umbilicus. G. trichophorum Buckman (1922, 

pl. 291) has weaker ribbing and a smaller umbilicus. 

Holotype, U.S.N.M. 108137. 

Chinitna formation, near base, lJ.S.G.S. Mes. loc. 

3015. 

Gowericeras spinosum Imlay, n • .sp. 

Plate 53, figures 8, 11 

The species is known by only one slightly crushed 

specimen. Whorl ovate in section, a little wider than. 

high, embracing about three-fifths except at anterior 

end of body whorl. · Flanks and venter evenly convex. 
100 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

Umbilicus fairly wide, enlarging rapidly near anterior 

end of body chamber; umbilical wall moderate in 

height, vertical, rounding rather abruptly into flanks. 

The body chamber is represented by about three-fourths 

of a whorl. The aperture is abruptly truncated and is 

preceded by several weak primary ribs. 

The body whorl and the penultimate whorl bear 

coarse, widely spaced primary ribs that incline backward on the umbilical wall, incline slightly forward 

on the flanks and terminate in prominent, conical tubercles at about two-fifths of the height of the flanks. 

From the tubercles arise two or. three sharp secondary 

ribs that are considerably weaker than the primary 

ribs and incline forward gently on the flanks. Single 

ribs arise along the zone of. furcatioh between the sets o£ 

branched ribs. The body whorl has 28 primary ribs 

and about 100 secondary ribs. 

The first lateral lobe is slightly longer than the external lobe. The second lateral lobe is very short. The 

external saddle is wider than the first lateral lobe or 

the first lateral ·saddle. The tubercle is in the inner 

branch of the first lateral saddle. 

The holotype at a diameter o£ 94 mm has a whorl 

height of 24 mm, an umbilical width of 38 rom, and an 

estimated whorl thickness ·of 35 mm. 

This species greatly resembles Gowericeras ventrrile 

Buckman (1922, pl. 288) but has longer primary ribs 

and fewer secondary ribs. Compared with G. approwimatum (Buckman) (1922, pl. 336), it has more prominent tubercles, more secondary ribs, and a thicker 

whorl section. 

Holotype, U.S.N.M. 108138. 

. Chinitna formation, lower part of middle third, at 

U.S.G.S. Mes. loc. 22432: 

G.owericeras sp. 

Plate 53, figures 6, 7, 10 

One specimen from the same locality as G. snugharborense differs apparently from that species by having 

a thicker whorl section, weaker primary ribs and more 

strongly inclined secondary ribs. However; direct comparisons cannot be· made because only a small part of 

the body chamber is preserved. The suture line is well 

pr~served. The first lateral lobe is slightly longer than 

the external lobe. The second lateral lobe is very short. 

The external saddle is a little wider than the first lateral 

lobe and is asymmetrically divided by a short lobule. 

The first lateral saddle is as wide as the external saddle . 

and is nearly symmetrically divided by a short lobule. 

The tubercle is in the outer branch of the second lateral 

saddle. 

Figured specimen, U.S.N.M. 108139. 

Chinitna formation, near base, U.S.G.S. Mes~ loc. 

.3015. 

Genus Cosmoceras W aagen 1869 

Subgenus Cosmoceras, sensu stricto 

Cosmoceras (Cosmoceras) cf. C. spinosum (J. de C. Sowerby) 

Plate 53, figures 4, 5 

One specimen has poorly preserved inner whorls and 

has been crushed ventrally in such a manner as to make 

the flanks bulge out. However, it is clearly markedly 

evolute for the genus, has a fairly thick whorl section, 

and a broad flat venter. On the inner whorls the primary ribs are high, narrow, fairly widely spaced; and 

terminate in prominent spines along the line o£ involution. In several places two adjoining primary ribs 

unite in a spine. On the outer whorl the ribs ·are similarly high, sharp and fairly widely spaced, and are 

nearly as prominent on the venter as on the flanks. 

They are radial, or inclined forward slightly on the 

flanks but cross the venter transversely. About hal£ 

of the ribs pass from the umbilicus to the venter without bifurcating or bearing tubercles on the flanks. 

These alternate fairly regularly with ribs that bifurcate 

at or slightly above the middle of the flanks and bear 

fairly prominent lateral tubercles. All the secondary 

ribs bear distinct ventral tubercles and none are joined 

at the ventral tubercles. 

This species seems to be intermediate between 0. compressum (Quenstedt) (Arkell, 1939, p. 191) and 0. 

spinosum (J. de C. Sowerby) (Arkell, 1939, p. 187). 

It resembles 0. spinosum in its evolute form, thick whorl 

section, and numerous unbranched ribs. It differs in 

its finer ribbing, less prominent ventral tubercles, and. 

broader venter; in these respects it is more like 0. compres sum. The failure o£ any of its secondary ribs to 

join at the ventral tubercles suggests that it is distinct 

from either o£ these species. 

Figured specimen: U.S.N.M. 108140. 

Chinitna formation ( ? ) at U.S.G.S. Mes. loc. 10991. 

The specimen was found as float, but the sharpness of 

its ribbing shows that it was not carried far. Its location suggests that it was derived from the upper part 

of the middle third of the Chinitna formation. 

Subgenus Gulielmiceras Buckman 1920 

Cosmoceras (Gulielmiceras) alaskanum Imlay, n. sp. 

Plate 49, figures 13-16 

. The species is represented by two external molds and 

one ·internal mold. Form compressed, discoidal; 

whorls subquadrate, considerably higher than wide; 

flanks high, flattened, parallel below,eonverging gently 

above, rounding abruptly into umbilicus; venter truncated, fairly narrow, concave but becoming less so near 

aperture. Umbilicus fairly narrow, enlarging slowly; 

wall fairly low and vertical. Length of body chamber 

not known. Aperture marked by a prolonged lateral 

lappet . 
ALASKA PENINSULA AND COOK INLET REGIONS 101 

The ribs are thin, moderate in height and spacing, 

·and gently flexuous. The primary ribs are a little 

n1ore prominent than the secondary ribs. They incline backward on the upper part of the umbilical wall, 

incline forward on the flank, and terminate in small 

conical tubercles at about one-third of the height of 

. the flanks. The primary ribs are swollen on the umbilical edge but do not form tubercles there. The secondary ribs incline forward in a gently flexuous manner 

on the inner whorls and on the posterior part of the 

body whorl. Anteriorly on the body whorl they bend 

forward increasingly near . the middle of the flank. 

Near the ·aperture they form a prominent bulge that 

is prolonged 'l.n the lateraf lappet. The secondary ribs 

pass from the lateral tubercles mostly in pairs, but on 

the body whorl some of the secondaries are indistinctly 

connected with the lateral tubercles and a few secondaries arise free of any tubercle. All the secondaries 

ter1ninate ventrally in small radially elongated tubercles that bound the flattened ventral area and are connected across the venter by ribs that are a little weaker 

than the flank ribs. 

The suture line is not preserved and the specimens are 

too i1nperfect for accurate measurements. 

This species is very similar to 0. knechteli Imlay 

from the Kepp.lerites mclearni beds of Montana (Imlay, 

1953, p. 31). In lateral view it greatly resemble_s a 

Gulielmice'ras from England figured by Brinkmann 

(1929, pl. 1, fig. 1) as G. gulielrnii Sowerby but considered by Arkell ( 1945, p. 341) an unnamed species. It 

differs from most of the described species of Gulielmiceras (e. g. Buckman, 1920, pl. 194; 1924, pl. 531, 

532) · by lacking a distinct umbilical tubercle and by 

having a ribbed venter. However, a speci.es from Russia described by Nikitin ( 1881a, p. 70, pl. 4, fig. 31) 

does not have umbilical tubercles, but only swellings at 

the edge of the umbilicus, ·as in the Alaskan species. 

Also, a species from east Greenland (Spath, 1932, p. 96, 

pl. 24, figs. 3a, b, pl. 26, fig. 5) lacks both umbilical and 

lateral tubercles and has ventral ribbing on the anterior 

part of the body whorl. Spath (1932, p. 97) notes that 

similar feebly tubercuhite forms occur in the Kellaways 

beds in Yorkshire. The ornamentation of the Alaskan 

species is similar to that of immature forms of some 

species of Kepplerites except for greater compression, 

more flexuous ribbing, and the prolonged lateral lappet. 

Assignment to Sigaloceras is not possible because that 

genus develops a smooth body chamber, is typically un-

. tuberculate, and generally has much denser ribbing. 

Likewise Gulielmites is distinguished by a smooth body 

whorl and an absence of lappets. 

Holotype, U.S.N.M. 108141, paratypes, U.S.N.M. 

108142a, b. 

Chinitna formation, near base, U.S.G.S. Mes. locs. 

2920 and 20755. 

218128-53-5 

Genus Reineckeia Boyle 1878 

Subgenus Kellawaysites Buckman 1925 

Reineckeia (Kellawaysites) shelikofana Imlay n .. sp. 

Plate 55, figures 1, 2, 5-8 

This species is represented only by the holotype . 

Form moderately stout; whorls evolute, inner whorls 

o-reatly depressed a11d having divergent flanks, outer 

~horls ovate, slightly depressed, and thickest uear the 

middle of the flanks. Venter on inner whorls very 

broad, depressed, and making a sharp angle with the 

flanks alono- the line of tuberculation. During growth 0 

the venter becomes more convex and on body whorl 

rounds evenly into flanks.· Umbilicus very wide; wall 

steep at base, rounding evenly into flanks, mod~ratel~ 

high, becoming higher during growth. Char~cters of 

body chamber not known as shell is septate to end. The 

protoconch is well exposed and represents about onefifth of a whorl. ..... 

The ornamentation changes consider:.ably during 

growth. The first two whorls are smooth. The th~rd 

whorl. which attains a diameter of about 2Inm, has faint 

swellings along the middle of the flanks.. The fourth 

and fifth whorls haye widely-spaced, prominent nodes 

along the flanks just below the line of involution .. Th~se 

nodes mark the termination of low, broad ribs that begin on the upper part of the umbilical wall, trend radial 

at first, and then incline strongly . :forward. On the 

sixth and seventh whorls, :from diameters o:f 8 to ·37 mm, 

the priinary ribs gradually become closer space~, narrower, less strongly inclined, and . their terminations 

are marked by :fairly regular alteration of weak and 

strong nodes. These nodes mark the bases of high 

spines that are preserved at several places. The se~­

ondary ribs are exposed only on the outer seventh to 

ninth whorls :from diameters o:f 37 to about 160 mm. 

They are slightly stronger than the primary ribs, closer 

spaced, triangular in cross-section, and arch :for:ward 

strongly mi the venter. On the seventh and eighth 

whorls the secondary ribs generally branch :from the 

strong nodes by three's and from ·the weak nodes by 

two's. Some of the secondary ribs arise singly from 

weak nodes. On the ninth whorl the secondary ribs 

become more·widely spaced, bifurcate :from weak tubercles and o-enerally one of the branches is indistinctly . ' b • . . connected with the tubercle. A weak median Sinus Is 

evident on the venter of the seventh whorl. It cannot 

be seen on the outer two whorls. · 

The suture line is excellent confirmation o:f the generic position o:f R. shelikofa;na, as shown by the obliquity o:f the suture with respect to the radius o:f the shell, 

by the considerable width of the saddles, ·by the greater 

length of the external lobe than o:f the first lateral lobe, 

and by the small, oblique second lateral lobe. The general pattern of the suture is similar to that on R. (K) 

owyptychoides (Spath) (1933, pl. 126, fig. 1). The 
102 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNITED STATES AND ALASKA 

main difference is in the outer branch of the first lateral 

saddle, which is shorter than the inner branch on the 

Alaskan specimen. The shortness of this branch is pos-. 

sibly related to its position on the ventral shoulder or 

to the location of tubercles; 

The proportions at a dimneter of about 113 mm are 

shown on the outline drawing on plate 55, figure 2. 

The outer two wh~rls ar~ too crushed for accurate 

measurement. 

This species is distinguished by the rather closely 

spaced ribbing on its outer whorls and its rather high 

point of rib branching from such ·species as R. multicostata (Petitclerc) ( 1915, p. 98, pl. 12, fig. 2), R. OW!)p!-

tychoides Spath ( 1928, p. 266, pl. 4, figs. 5a, b), and 

R. greppini (Oppel) (1862,p. 154; Neumayr, 1870, p. 

151, pl. 8, fig. 2'). The density of its ribbing is approached by R. bulcowslcii Till (1911, p. 13, pl. 1, figs. 

7, 8), which Loczy (1915, p. 374,433, pl. 19, figs. 6-8) 

consideJ;S a synonym of R. plana Lee, but the latter 

has flatter flanks and a higher whorl section. None of 

the Mexican or South American species of Reineckeia 

are closely comparable. Forms comparable in size with 

the Alaskan species have been figured by Loczy (1915, 

pl. 20, fig. 5, pl. 21, fig. 1). 

Holotype, U.S.N.M. 108143. 

Shelikof formation, about 350 feet above base at 

U.S.G.S. Mes. loc. 21355 at Wide Bay. 

Genus Procerites Siemiradzki 1898 

Procerites spp. 

Plate 53, figures 1-3 

Fragmentary speci~nens referable to Procerites have 

been found at the very base of the Chinitna formation 

at several localities. One species (pl. 53, fig. 1), from 

Mesozoic localities 22446 and 22448, bears ribbing similar to Procerites evolutits (Neumayr) (1871, p. 41, pl. 

14, figs. 2a, b). It differs mainly by having a more 

compressed whorl section and by the secondary ribs 

arching forward on the venter. Many of the bifurcation points are indistinct and some of the secondary 

ribs arise independently of the primary ribs. Deep 

constrictions occur on two fragments. The ribbing is n, 

little coarser and more even than on the inner whorls of 

Procerites? irregularis described herein. 

Another species (pl. 53, figs. 2, 3), from Mesozoic 

locality 22446, resembles P. funatws (Oppel) in NeuInayr (1871, pl. 14, figs. la, b) in whorl shape, degree ot 

involution. and strength of ribbing, but its secondary 

ribs are fewer in number and arch forward on the 

venter. A constriction is present on the penultimate 

whorl. Arching of the ribs similar to that on these 

Alaskan specimens occurs on P. hians (Waagen) (1875, 

p. 153, pl. 17, figs. 2a~) from India and on a Procerite8 

. from Hungary figured by Loczy ( 1915, p. 425, text-fig. 

139). . 

Figured specimens, U.S.N.M. 108144, 108145. 

Chinitna formation, near base, at U.S.G.S. J\tles. locs. 

22446 and 22448. 

Procerites 1 irregularis Imlay, n. sp. 

Plate 54, figures 1, 2 

This species is represented by only one large spec]- · 

n1en from a level near the base of the Chinitna fornlation on Chisik Island. The specimen has been much 

crushed laterally so that measurements are useless and 

the whorls appear to be nearly flat. Originally the 

whorls were probably nearly ovate. The body whorl 

embraces·the penultimate whorl about one-third. The 

umbilicus is wide and the mnbilical wall is low and 

gently inclined. The body chamber. is represented by 

five-sixths of a whorl and its aperture is not preserved. 

The ribbing on the sutured whorls is moderate but 

irregular in strength and inclined forward. The ribs 

begin weakly on the umbilical wall and are strongest at 

the line of involution. There are 6 or 7 constrictions 

per whorl and a similar number of swollen ribs. Portions of the venter exposed at a dimneter of 30 n1m 

show that the ribs becmne broader and lower on the 

venter, are arched forward less strongly than on the 

flanks and that some ribs bifurcate. On the body whorl 

the ribs become weaker and broader but more uniform 

in strength. Most of them begin at the line of involution but some begin near the middle of the flanks and 

a few occur only on the venter. 

The suture line is distinguished from that of other 

described species of Procerites by a somewhat broader 

first lateral saddle and a longer se<;ond lateral lobe. 

This species is tentatively placed in Procerites because it is more evolute and has more single. ribs than 

any of the· described species. However, it would certainly appear much less evolute if it were not crushed. 

Similarly large and evolute species of Ohotfatia are distinguished by coarser and more widely spaced pri1nary 

ribs and generally by more numerous secondary ribs, 

although Spath (1931, p. 357, pl. 79, figs. 5a, b) figures 

a specimen of Ohotfatia having an outer whorl similar 

to that of the Alaskan species. The large specimens of 

Sivajiceras from India described by Spath ( 1931, pp. · 

287-295) have much coarser ribbing on their inner 

whorls and are more robust. 

Holotype, U.S.N.M. 108146. 

Chinitna formation, near base, U.S.G.S. Mes. loc. / 

21273. 

Genus Grossouvria Siemiradzki 1898 

Grossouvria sp. 

Plate 55, figures 3, 4 

The genus Grossouvria is repr~sented by half a whorl 

that has been much crushed. The fragment shows 

prmninent, sharp, rather widely spaced primary ribs, 

most of which divide rather high on the flanks into 

... 
·_-., 

~· 

... 

).. 

ALASKA PENINSULA AND COOK INLET REGIONS 103 

secondaries that curve backward strongly on the venter. 

Three sets of parabolar nodes on the ventral margins 

mark the tenninations of pairs of primary ribs. Species 

of Grosso'ltvria having similar ornamentation are illustl·ated in monographic works by Cm·roy (1932, pl. 17, 

figs. 7, 8, pl. 18, figs. 6-9) and Pfaehler-Erath (1938, 

pl. 1). 

Figured specimen, U.S.N.M. 108147. 

Chinitna formation; lower third, U.S.G.S. Mes. loc. 

22431. 

REFERENCES 

Anderson, F. M., 1945, Knoxville, series in the California Mesozoic: Geol. Soc. America Bull., vol. 56, pp. 909-1014, 15 pls. 

Antevs, E;, 1925, The climatologic significance of annual rings 

in fossil woods, Am. Jour. Sci., 5th ser., vol. 9, pp. 296-300. 

Arkell, W. J., 1939, 'l'he ammonite succession at the ·woodham 

Brick Co's. pit: Geol. Soc.· London Quart. Jour., vol. 95, 

pp. 13fl-222, pls. 8-11. 

---1945, The zones of the Upper Jurassic of Yorkshire: Yorkshire Geol. Soc. Proc., vol. 25, pt. 5, pp. 339-358. 

-.-- 1946, Standard of the European Jurassic: Geol. Soc. 

America Bull., vol. 57, pp. 1-34, 4 tables. 

Blal•e, J. F., 1905, Fauna of the Cornbrash: Paleontogr. Soc. 

Pub., 106.pp., 9 pis. 

Brinkmann, R., 1929, Monographic cler Gattung Kosmocm~((,S: 

Gesell. Wiss. Gottingen, Math.-phys. Kl., Abh~, N. F., Band 

13, no. 4, pp. i-vii, 1-123, 1 pl. 

Buckman, S. S.,· 1909-1930, [Yorkshire] Type Ammonites, 7 vols. 

--- 11)29, Jurassic AuHnonoidca ·in Meso~oic paleontology of 

Blairmore region, Alberta: Canada Nat. Mus. BulL 58, Geol. 

Ser. 50, pp. 1-27, 3 p1s., 1 fig. 

Burcl{hardt, Carlos, 1903, Beitriige ~ur Kenntniss der Jura-und 

Kreicleformation der Cordillere: Palaeontographica, Band 

50~ 144 pp., 16 pis. 

--- 1927, Cefal6podos del Jnra.sico medio de Oaxaca y Guerrero : Inst. geol. Mexico Bol., no. 47, 108 pp., 34 pls. 

--- 1930, Etude synthetique sur le mesowique mexicain : 

Schweizer. palaeont. Gesell. Abh., vols. 49-50, 280 pp., 11 

tables, 32 figs. 

Capps, S. n., 1.922, 'J~he Cold Bay district: U. S. Geol. Survey 

Bull. 739, pp. 77-116, 1 pl., 2 figs. 

Cllllpin, 'l'heodore, 1!)1.8, 'J~he Nelchiua-Susitna region, Alaska: 

U. S. Geol. Survey Bull. 668, 67 pp., 10 pis., 4 figs. · 

Cort·oy, G., 1932, Le Callovien de la Bordure Orientale du Bassin 

de Paris: Carte geol. France Mem., 337 pp., 29 pls., 62 figs. 

Crickmay, C. H., 1.930, Fossils ft·om Harrison Lake area, British 

Columbia: Canada Nat. Mus. Bull. 63, pp. 33-66, 82-1.13, 

pls. 8-23. , 

--- 1933, Some of Alpheus Hyatt's unfigured types from the 

• Jurassic of California: U. S. Geol. Survey Prof. Paper 175, 

pp. 51-64, 5 pls. 

Douville, Robert, 1912, lDtude sur les Cardioceratides de Dives, 

Villers-sur-Mer, et quelques autres gisements: Soc. geol. 

France Mem., Paleontologic, vol. 19, pp. 1-77, pis. I-V, 84 

text-figs. 

Eichwald, E., 1871, Geognostisch-Palaeontologische Bemerkungen i.lber die Halbinsel Mangischlak und die Aleutischen 

Inseln ; 200 pp., 20 pls. 

Fischer, P., 1880-1887, Manuel de conchyliologie et de Paleontol-

. ogie conch~'liologique : 1369 pp., 23 pls. 

Frebolcl, Hans, 1929, Oberen Lias und unteres Callovien in 

Spitzbergen: Skrift. om Svalbard og lshavet, no. 20, pp. 

5-24, 2 pis., 5 figs. 

--- 1930, Verbreitung und Ausbildung des Meso~oikums in 

Spitzbergen: Skrift. om Svalbard og Ishavet, no. 31, 126 pp., 

23 pis. 

---1935, Geologie von Spitzbergen, der Bareninsel, des KonigKarl- und des Franz-Joseph-Landes: Geologie. der Erde. 

Gothan, ,V., 1908, Die Frage der Klimadifferenzierung im Jura 

und in der Kreideformation im Lichte palli.obotanischer 

Tatsachen: K. preuss. geol. Landesanst. Jahrb., Band 29, 

pt. 2, no. 2. 

Grewingk, C., 1850, Beitrag zur Kenntniss der orographischen 

und geognostischen Beschaffenheit der Nord-'Vest-Kuste 

Ame~·ikas mit den anliegenden Inseln: Russ. K. min. Gesell. 

Verb. 1848-49, pp. 76-366, pis. 4-7. 

Haug, E., 1.907, Traite de geologie. I, Les phenomenes geologiques. 

, II, Les periodes geologiques. 2021 pp., (Paris). 

!Inlay, R. ,V., 1943, .Jurassic formations of Gulf region : Amer. 

Assoc. Petrol. Geol. Bull., vol. 27, pp. 1.407-1533, 14 figs., 

6 tables. 

---, 1948, Charac.teristic marine Jurassic fossils from the 

western interior of the United States: U. S. Geol Survey 

Prof. Paper 214-B, pp. 13-33, pis. 5-9. 

Kellum, L. B., Daviess, S. N., and Swinney, C. M., 1945, Geology 

and oil possibilities of the southwestern end of .the . Wide 

Bay anticline, Alasl\:a: U. S. Geol. Survey Prelim. Rept., 

17 pp., 9 figs. 

Keyserling, A. Graf, 1846; Wissenschaftliche Beobachtungen auf 

einer reise in das Petschora-Land im .Jahre 1843, p. 331. 

Khudyaev, .J., 1927, The Mesozoic deposits in the region of the 

Sysola River (Southern part of the I~echora-l.;and) : Com: 

geol. Leningrad. Bull., vol. 46, no. 5, pp. 497-521, pis. 27, 28. 

Kirschner, C. E. and Minard, D. L., 1949, Geology of the Iniskin 

Peninsula, Alaslm: U. S. Geol. Survey Oil and Gas Invest. 

Prelim. Map 95. 

Kobayashi, Teiichi, 1947, On 'the occurrence of Seymowrites in 

Nippon and its bearing on the Jurassic paleogeography: 

Japanese Jour. Geology and Geography, vol. XX, pp. 1.9-31, 

pls. 7, 8. 

Kudernatsch, J., 1852, Die ammoniten von Swinitza ': K. K. geol. 

Reichsanst. Abh., Band I, pp. 1-16, 4 pls. 

Loczy, Ludwig, 1.915, Monographic der Villanyer Callovien-Am- . 

moniten : Geologica Hungarica, vol. 1, pts. 3-4, pp. 255-509, 

pis. 13-26. 

Lupher, R. L., 1941,· .Jurassic stratigraphy of central Oregon; 

Geol. Soc. America Bull., vol. 52, pp. 219-269, 4 pls., 3 figs. 

·Madsen, V., 1.904, On Jurassic fossils from East Greenland: 

Meddelelser om Gronland, Bind 29, pp. 1.57-210, pls. 6-10. 

Maire, V., 1.932, Note comph~mentaire sur le gisement d'Authoison (Haute-SaoJle) ; Soc. grayloise d'Emul. Bull., no. 21, 

p. 197. 

---1.938, Contribution a la connaissance des Cardioceratides: 

Soc. geol. l!,rance Mem., N. S., vol. 15· (Mem. 34), 134 pp., 

20 pls. 

Martin, G. C., 1.926, The Mesozoic stratigraphy of Alaska: U: S . 

Geol. Survey Bull. 776, 493 pp., 13 figs. 

McLearn, F. H., 1927, Some Canadian Jurassic ofaunas: Royal 

Soc. Canada Trans., 3d ser., vol. 21, sec. 4, pp. 61-73, 1 pl. 

--- 1928, New Jurassic ammonoidea from the Fernie formation, Alberta: Canada Geol. Survey Bull. 49, Geol. Ser. no. 

48, pp. 19-22, ·pls .. 4-8. 

--·- 1929, Contributions to the stratigraphy and paleontology 

· of Skidgate Inlet, Queen Charlotte Islands, British Columbia: Canada Nat. Mus. Bull. 54, Geol. Ser. no. 49, pp. 1-27, 

16 pls. 

Moffit, F. H., 1927, The Iniskin-Chinitna Peninsula and the Snug 

Harbor district, Alaska: U. S. Geol. Survey Bull. 789, 71 pp., 

11 pis., 1 fig~ 
104 CALLOVIAN (JURASSIC) AMMONITES FROM THE UNI'l.'ED STATES AND ALASKA 

Neu~nayr, M., 1870, Uber einige neue oder weniger bekannte 

Cephalopoden der Macrocephalen-Schichten: K. K. geol. 

Reichsanst. Jahrb:, Band 20, pp. 147-156, pls. 7, 8. 

--- 1871, Jura Studien, III. . Die Phylloceraten des. Dogger 

und Maim: K. K. geol. Reichsanst. Jabrb., Band 21, pp. 297-

354, pls. 12-17. 

--- 1883, Uber klimatische zonen wlihrend der Jura-und 

Kreidezeit: K. Akad. Wiss. Wien Denkschr., .Math.-naturh. 

Kl., Band 47, pp. 277-310. 

---1885, Die geographische Verbreitung der Jura-formation, 

K. Akad. Wiss. Wien Denkschr., Math.-naturh. Kl., Band 50, 

pp. 57-144, 1 pl., 2 maps. 

Newton, E. T. and Teall, J. J. H., 1897, Notes on a collection of 

rocks and fossils from Franz Josef Land ... : Geol. Soc. 

London Quart. Jour., vol. 53, pp. 477-519, pls. 37-41. 

Nikitin, S., 1881a, Die Jura-ablagerungen zwischen Rybinsk, 

Mologa und Myschkin an der oberen Wolga : Acad. Imp. 

Sci. St. Petersbourg Mem., 7 ser., vol. 28, no. 5, 98 pp., 7 pls. 

---1881b-1885, Der Jura der Umgegend von Elatma; Lief. 1 

(1881), pp. 83-133, pls. I-VI (VIII-XIII); Lief. II (1885), 

pp. 43-66, pls. VII-XI (IX-XIII) : Soc. Imp. Natur. Moscou 

Nouv. Mem., vols. 14, 15. 

--- 1884, Allgemeine Geologische Karte von Russland. Blatt 

56. Jaroslaw1, Rostov. Kaljasin, Wesiegonsk, Poschechonije: Com. geol. St. Petershourg Mem., vol. 1, no. 2, 137 

pp;, 3 pls. 

--- 1886, Uber die Beziehungen zwischen der russischen und 

der westeuropliischen Jura-formation: Nenes Jahrb. 1886, 

Band 2, H. 3, pp. 205-248. 

Oppel, A., 1862-1863, Uber .Jurassic Cephalopoden: PaUiont. 

Mitt. Mus.· Bayer;-staats, pt. 3, pp. 127-162, pls. 4Q-50 

(1862); pp. 163-266, pls. 51-74 (1863). 

D'Orbigny, Alcide, 1842-1851, Pa!eontologie Fran~aise. Terrains Jurassiques, V\Jl. 1. 

---in Murchison, Verneuil et Keyserling, 1845, Geologie de la 

Rossie d'Europe ... , vol. 2, Terrains Second., Syst. Jurass., 

Mollusques, pp. 419-488, pis. 28-42. 

Paige, Sidney and Knopf, Adolph, 1907, Geologic reconnaissance 

in the Matanuska and Talkeetna Basins, Alaska: U. S. 

Geol. Survey Bull. 327, 71 pp., 4 pis., 4 figs. 

Parona, C. F. and Bonarelli, G., 1897, Sur la faune du Callovien 

inferieur (Cbanasien) de Savoie: Acad. Sci. Savoie Mem., 

4 ser., vol. 6, pp. 35-211, pis. 1-11. 

Petitclerc, P., 1915, Essai sur la faune dn Cailovien du Departement des Deux-Sevres, ... etc., pt. I, pp. 1-151; 

pt. 2, pp. 1-11, pis. 1-14 (Vesoul). 

Pfaebler-Erath, Irene, 1938, Sur quelques Grossottvria et .Ohoffatia du Callovien de Chezery (Jura francais) : Schweizer. 

palaeont. Gesell. Abh., vol. 60, 29 pp., 4 pls. 

Pompeckj, J. F., 1899; The Jurassic fauna of Cape Flora, Franz 

Josef Land, in ·Nansen, F., The Norweigian North Polar 

Expedition, 1893-96, Sci. Results, vol. 1, no. 2, 147 pp., 3 pls. 

--- 1900, Jurafossilien a us Alaska: Russ. K. min. Gesell. 

Verb., 2nd ser., Band 38, pp. 239-278, pls. 5-7. 

Quenstedt, F.·A. v.; 1883-88, Die Ammoniten des Schwlibischen 

Jura, 3 Bfinde, 1140 pp., 126 pls. (Stuttgart). 

Ravn, J. P. J., 1911, On Jurassic and Cretaceous fossils from 

North-East Greenland: Meddelelser_ om Gronland, vol. 45, 

pp. 433-500, pls. 32-38. 

Reeside, J. B., Jr., 1919, Some American Jurassic ammonites' 

of the genera Quenstedticeras, Cardioceras, and Amoeboceras, family Cardioceratidae: U. S. Geol. Survey, Prof. 

Paper 118, 64 pp., 24 pls. 

Roemer, J., 1911, Die Fauna der . Aspidoides-Schichten von 

Lechstedt bei Hildesheiin. lnaug. Diss. Gottingen, 64 pp., 

12 pis. · 

Rosenkrantz, Alfred, 1929, Preliminary account of the geology 

of the Scoresby Sound district in Koch, Lauge (1929), The 

Geology of East Greenland : Meddelelser om Gronland, vol. 

73, no. 2,pp. 135-154,figs. 41-45. 

Russell, F. S., and Yonge, C. M., 1936, The Seas, 379 pp., 384 ill., 

Frederick Warne and Company, Ltd., London and New York. 

Salfeld, Hans, 1921, Das Problem des borealen Jura und der 

borealen Unterkreide: Centralbl. Mineralogie 1921, no. 6, 

pp. 169-174. 

Sayn, G., and Roman, F., 1928-1930, Monographie stratigraphique et paleontologique du Jurassique moyen de la Voultesur-Rhone: Lyon Univ. Lab. geologie Travaux, fasc. 13, 

14 (Mem. 11), 256 pp., 21 pls. 

Schuchert, Charles, 1914, Climates of geologic time: Carnegie 

Inst. Washington Pub. 192, pp. 265-298, paleogeographic 

maps. 

Smith, W. R., 1925, The Cold Bay-Katmai district: U. S. Geol. 

Survey Bull. 773, pp. 183-207. 

--- 1926, Geology and oil development of the Cold Bay 

district: U. S. Geol. Survey Bull. 783, pp. 63-88, 1 pl., 1 fig. 

Smith, W. R., and Baker, A. A., 1924, The Cold Bay-Chignil\: 

district, Alaska: U. S, GeoJ. Survey Bull. 755, pp. 151-218, 

5 pis., 1 fig. 

. Sokolov, D. N., (1912), Zur-ammonit~nfauna des Petschoraschen 

J.ura: Com. geol. St. Petersbourg, Mem., N. S., livr. 76, pp. 

1-65, 3 pls., 11 text figs. 

Sowerby, James, and Sowerby, J. de C., 1812-1846, Mineral 

Conchology: 7 vols., pls. 1-337 (1812-1822) by J. Sowerby; 

pls. 338-648 (1822-1846) by J. de C. Sowerby. 

_ Spath, L. F., 1925, Jurassic cephalopoda from Madagascar: 

Bull. Am. Paleontology, vol. 11, no. 44, 30 pp., 1 pl.· 

---1927-1933, Revision of the Jurassic cephalopod fauna of 

Kachh ( Cutch). Palaeontologia Indica, new ser., vol. 9, 

6 parts, 945 pp., 130 pls. 

---1932, The invertebrate faunas of the Bathonian-Callovian 

deposits of Jameson Land (East Greenland) : Meddelelser 

om Gronland, Bind 87, no. 7, 158 pp., 26 pls., 14 text-figs. 

---1946, Preliminary notes on the Cretaceous Ammonite 

faunas of East Greenland: Meddelelser om Gronland, Bind 

132, no. 4, pp. 1-12. 

Stanton, T. W.,l910, Paleontologic evidences of climate: Popular 

Science Monthly, vol. 77, pp. 67-70. 

Stehn, 1'~ .• 1924, Beitra.ge zur Kenntnis des Bathonien und Callovien in Sudamerika: Neues Jahrb., Beilageband 49 (1923), 

pp. 52-158, 8 pis. 

Taliaferro, N. L., 1942, Geologic history and correlation of the 

Jurassic of southwestern Oregon and California: Geol. 

Soc. America Bull., vol. 53, pp. 71-112, 3 figs. 

Till, A., 1910-11, Die ammoniten fauna des Kelloway von 

Villany _ (Ungarn) : Beitr. PaUiontoiogie Oesterr.-Ungarns 

n. des Orients, vol. 23, pp. 175-199, 251-272, pis. 16-19 

(1910) ; vol. 24, pp. 1-49, pls. 1-8 (1911). 

Twenhofel, W. H., 1939, Principles of sedimentation, 610 pp., · 

McGraw-Hill Book Co., Inc. · 

Uhlig, V., 1911, Die marinen Reiche des Jura und der UnterKreide: Geol. Gesell. Wien Mitt., Bd. 4, H. 3, pp. 329-448, 

1 map. 

Waagen, W., 1873-:-75, Jurassic fauna of Kutch. The Cephalopoda: Palaeontologia Indica, vol. I, Pt. 1, pp. 1-22, pis. 1-4 · 

(1873) ; Pt. 2, pp. 23-76, pls. 5-14 (1875) ; Pt. 3, pp. 77-106, 

pls. 15-24 (1875); Pt. 4, pp. 107-247, pls. 25-60 (1875). 

Whiteaves, J. F., 1876. On some invertebrates from the coalbear-ing rocks of the Queen Charlotte Islands: Canada Geol. 

Survey Mesozoic Fossils, vol. 1, pt. 1, pp. 1-~2, ill. 

Zittel, K. A., 1868, Die Cephalopoden der Stramberger Schichten: 

· Mus. K. Bayer.-Staates, Pal. Mitt., Band 2, pt. 1, pp. viii, 

118, 24 J?lS. 

-~ 

~. 

·~ 
.... 

INDEX 

[Italic numbers indicate descriptions] 

A Page 

abruptum, Kheraiceras. _ ----------------------------------------------------80, pl. 33 Yakounoceras _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ 98 

abruptus, Kepplerites. __ ------------------- __ --------------------------------- 97, 99 

Kepplerites (Seymottrites) __ -------- ________ ------------------------ ____ 98, pl. 52 

alaskanum,. Cosmoceras ( Gulielmiceras) ________ ~--------------------------~ 100, pl. 49 

alticostatus, Keppletites (Sevmourites).-------------------------------------- 95, pl. 48 A moebites ____________________________________ -_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 56 

Amoeboceras -------------------- ____________ :_ ----~-- ----------------------- __ 56, 60 

ammon, Cadoceras. ______ ------------ ___ ---------- _____ -------------.------ ____ 44 

Cadoceras (Paracadoceras) ---------------------- _________ --------------- __ _ 44 

Ammonites, occurrence.~--------- ______ ---------- ________ : _______ ---------___ 59 

Ammonites biplex. ------------------------------ ________ : _________ ------- _____ 93 

doroschini_ ______ --·---------- ___________ ----------------------.--- __________ 85, 86 

milletianus ____________ ----~- ____ ---- ________ ----- ___ . ____ ----- _____________ 93, 94 

platvstomus _--------------- ______________ -_______________________________ ._ 81 

sublaevis ____ --- _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ __ __ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ 43 

wosnessenskiL ___ --------- _____________ ------- __ ------- ______ ----- ___ _____ 86 

angustiumbilicatus, Xenocephalites parvtts ____ ---------------- ____ __ _____ ___ ___ _ 79 

approximatum, Gowericeras _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 100 

Arcticoceras.--------------------------------·---------------- 42, 43, 44, 45, 48, 53, 54,55 henrgi_ _________ -------- _________________ ----- __ ---------- ___ _____ ____ ____ _ · 45 

kochL •• -------------- __ ----- __________________________ --------- ___ ------- _ 55 

Arctocephalites.--------------------------------------------------- 42, 51, 55, 75, 7G, 77 arcticus ___ • __________________________________________________________ ~ _ _ _ _ 78 

ellipticus __________ ----- __ -------- __ ----- ______________ ------------ _ _ ___ ___ 77 

arcticus, Arctocephalites ____ ... _____________ ---- ___ ------- ____________ .__ _ __ ___ ___ 78 

aspidoides, Oppelia ( Oxvcerites) -------------------- ______ ------- ___ ___ ___ __ ___ _ 75 

athleta, Peltoceras. ___ ------- ______ -------------------------------------------- 56 A ucella. ______ -_________________________ ·- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 60 

B 

bakeri; Phylloceras ________ ______ ----------------- ____ --------------------- __ 7£, pl. 25 bathvomphalttm, Cadoceras_____ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___ __ _ _ 46 

Biologic analysis ____ ---- __ ----- _________ .. _____________________________________ 41-48 

biplex, Ammonites. __ ---------------------------- ___________ --------__________ 93 bombur, J(heraiceras ____ _______ --- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 82 

boreale, Pseudocadocera8 __________________ ------------------------ __________ 46, 48, 94 

Bourkelamberticeras _ ----- ____ --- ___________ ~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 48 

bowserense, Cadoceras (StenocadocerasJ---------------------------------- 49, 91, pl. 43 breve, Cadoceras. _ _ _ _ __ _ _ _ ___ __ _ _ _ __ _ _ _ _ _ __ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ 51 

Cadoceras (Paracadoceras) ____ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 44 

brooksi, Cadoceras. -------------------------------- __ -------------------------- 44, 45 

~uck;i~~~t:;~~~~~~~c_e:~~ :_-_-_-_-_-_-_-_-_-_-_-.-_-_-_-_-_-_-_-_-_-_-_-_-_~ ---~-_-_-_-_-_-_-_-_-_-_-_~----57-,-7 6 :7s~ pl. ;; . 

Buckmaniceras buckmanL~ ------------------- _______ ------------------------- 75 

bukowskii, Reineckeia _______________ __ -------- ___________________ -------------- 102 : 

0 

Cadoceras ••••• -----------------.----- 41, 43, 44, 46, 48, 49, 51, 53, 54, 55, 56, 58, 59, 71, 72,78 : 

ammon.------------------------------------------------------____________ 44 , 

bathyomphalum ••• ------------------------- _____ --------------------=----- 46 breve •• _----_-- ______ -----••• __ • __________________ .________________________ 51 

brooluL ---••••••• __ • ____ --- ____ ••• _. ___ • _____________ •• _. _________________ 44, 45 

calyx ___ ---------------•• --.-.-••••• ~ •• _-- ___ •• --.~ ••• _____ ••••••• _----- 44, 45, 55 

catostoma •• ------------------------------------------------ 44, ~2,84, 88, 89, pl. 34 · 

comma ••• -------------------.--------------------------- 44, 47, 83, 84, 87; pis. 35,36 ; crassum _____ ---------- _________________________________ .. _______________ 45, 47, 83 

· .doroschinL------------------------------------------- 45, 47, 56, 84, 85, 86, 87, pl. 39 , · dttrum •••• ---.-.-••• --••• _____ --•••• _. _. ________ c _________________________ 46, 47 

elatmae ••• ---------------------------------------------------- 44,.45, 51, 83, 88,90 : franciscus ••• ---- __ -- _ _ _ __ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ __ __ _ __ _ __ _ _ _ _ _ __ _ _ _ __ _ 45 ! 

freboldi_ _____ _____________________________________________________________ • 45 · 

glabrum __________ • --------------------------- ___ ---- ______ · 44, 45, 83, 84, pls. 36,'37 

grewingki.. ----------------. ____ ---------- ______________ ------------------ 93, 94 kialagvikense ••••• ____ • _. _ •• _. __________ • _. _. ________________________ 45, 87, pl. 41 

milaschevicL. ---------------------------------------~------------ 44, 46, 53, 83,91 

nikitini_ _______ --------- __ ------------ _____________________ -~ ______ -------- 43, 92 orbis ___ • ____________________________________________________________ ~ _ _ _ _ _ 46 

petelini. _ -------------- ___________________________ ~ ________________ ------- 93 

quenstedti.. ___ ------- _____________________________________________________ 44, 83 

schmidti_ ___ ____ •• _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 95 

schnmarowi. _____________________________________________________________ _ 44 

Page 

Cadoceras-Oontinued 

shoshonense ____ _ ------------------------------------- ____ -- __ -- ___________ 45, 47 

simulans ___________ ---------------~------------- ---------- _____________ 44, 45, 83 

stenoloboide •• _____ -------------------------------------------------- 57, 86, 91, 92 

stenolobum ..... -------------------------------------------------- 43, 53, 87, 91,92 sublaeve ____ _______ . ______________________________________ "" _____________ 46, 47, 56 

sublaeve commune ___ ------------------- ____ ------------------------------- 46 

sttblaeve mgosum ____ --------------------------------------------------- 46, 83, 87 subpatruum ____ ______________________________ -_________________________ • _ _ 45 

surense ••• ____ -- _____________________________ -___________________ • ___ • ___ • 45 

:~;;}~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~.~ ~ ~ ~ ~ ~ ~ ~ ::: :: 

tenuicostatum .• -------------------------------------------------- 45, 85, 86, pl. 38 tolgpe __ _________________________ -- ____ -- ____ ----- _-- __ ----- _____ -- _ _ _ _ _ _ _ _ 46 

tschernyschewL----~ ___ ------------------------------------------------ 44, 45, 84 variabile _____ _____________________________________________ -.- _ _ _ __ __ _ _ _ _ _ _ _ _ 45 

occlusum ___ ________ -------- ________ -------------------------------- __ 45 

victor--------- __ -----" ________ · _____ ----------------- ___ ----- _____ ------- ___ 44, 87 

wosnessenskiL---------------------"-------------------------- 45, 84, 86, 87, pl. 40 

Cadoceras, group L ____ ------------------------------------ _ ----- _ ------------ 44, 47 

group 2 ______ ------------------------ _ -------------- __ ---------- 44-45, 47 

group 3--------·--- ___ --------- _ ---------- _ --- _ --- _ --------------- __ 45, 47 

group 4 .• ------------- _____ ------- ______ ----------- ________ ------- _ 45, 47 

group 5 _____ -------------- _____ ·---------- _ ------------------------ 45, 47 

group 6 _____ : -------------- __ -- ____ ------ __ ------------------ ___ 45-46, 47 

group 7-- ____ ------- _________ --- __ ---- ___ ---------------------- ____ 46-48 

Cadoceras (Paracadoceras) ------------- ~- ----------- ---~- --- _ ------------- --~ __ 51, 88 ammon. ______ -- _____________________ ~:.. _________________________________ ._ 44 

breve _____________________________________________________________________ • 44 

chisikense. __ -------------------------------------------------------- 44, 89, pl. 43 elatmae. ___________ • --- _______ • __ • __ --- __ • _. ___ • _ --- __ ·_. _________________ • 44 

frearsi_ _____ _ ------- ____ ---- ____ -- _- _-.--- _ ---.-.------- _ -- ___________ --- _ _ 44, 88 

~:;::~~~ ~~ ~ ~ ~ ~~ ~ ~~ ~~ ~ ~~~~~ ~~ ~ ~~ ~~~ ~~ ~ ~~ ~ ~ ~~~ ~ ~~~ ~~ ~ ~ ~~ ~~ ~ ~ ~~ ~ ~ ~ ~- 44:87:89, ~~: ~: multiforme ..• ---------------------------- __ -------- ----~--------- 44, 88, 89, pl.42 pseudoishmae ______ __ •• -- _______________________ -- ______ -- _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ 44 

schumarowi. ________________________________________ -- ______ ~ ______ • _ _ _ _ _ _ 44 

tonniense. ___ ---------------------------------------------------- 44, 88, 89, pl. 43 

Cadoceras (Stenocadoceras) __ --------------•-------- _______ :_ _______________ ~--- 71, 72 

bowserense .... -----------------------.------------------------------- 46, 91, pl. 43 compressum______ _ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ ___ _ _ ___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . 46 

dubium. _______ --.- _______________________ • ___ • _. _ •• ___ •• __ • _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 46 

iniskinense _________________________________________ ~---------- 46, 91, 92, 95, pl. 46 

milaschevici ____ • __ • _ __ _ _ _ _ ___ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ 46 

multicostatum _________________________________________ "_ 46, 47, 90, 91;92, 93, pl. 44 

nikitini. _________________ •• __ .. _________ • _____ • _ __ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ ____ _ __ 46 

pomeroyense. ---- _. _______________ : ________________ ------------- 46, 92; pls. 45, 46 

stenoloboide. ___ ---------------------------------------·------ "·- _ 46, 9£, pls. 46, 47 stenolobum ___ __ • _. _______ • ________ • __ • _________ • ______ • _______ • _ _ __ ___ _ __ _ 46 

:~~~~~;:~-~~~~~~~ ~~~-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-46:9o. ~~: :~ Calliphylloceras __ ------------------------------------------------------------- 42, 58 demidoffi __ _________ • _____ • _______ • _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ ___ _ _ __ _ _ __ _ _ __ _ _ _ 73 

( Calliphylloceras), Phylloceras ___ ------------------------------------ ____ ------ 73 

freibrocki, Phylloceras ________ ~.-------------------------------------- 72, 73, pl. 26 calloviense, Sigaloceras ____________________ : __________________ 44, 45, 46, 48, 51, 53, 55,72 

calloviensis, Oppelia _____________ ------------------ ___ ------------- ____ -------- 75 

calyx, Cadoceras _______________________ __ ----- ---------------------------~-- 44, 45, 55 

Cardioceras ____ • _. ___ • _______________ • __________ •••••• _ •• ____ • _____ • ______ ~ __ • 56 

Cardioceratidae ____ ___ • ____________ · __________________________________ ., ________ 43, 58 

castor; Cosmoceras ••..• __ . ___ • ___ • ___ • __________________ ~ •• ~- _ __ __ _ _ _ _ ___ _ ___ _ _ _ 55 

catostoma, Cadoceras •• _ -----------"-----:---------------------- 44~ 82, 84, 88, 89, pl. 34 

Chamoussetia •• ------------------- ____ : __ ------------------------------------ _ 55, 56 chantrei, Phylloceras ___________________________ __ ------- ___________ ------ ____ __ 73 

childanum, Gowericeras _______________ ______________ ------- __ ---~------------ __ 99 

Chinitna formation _________________________________________________ ----------- 49-51 

chinitnana, Oppelia (Oxycerites) __ -------~---------------------------------- 74, pl. 26 chinitnense, Pseudocadoceras _____________________________________________ 48, 94, pl. 48 

chisikense, Cadoceras (Paracadoceras) __ ---------------------------------- 44, 89, pl. 43 Choffatia ____________________________ __________________ ------ _________________ 56, 102 

Collection of specimens ___________________ .. , _________ ------------------------ 41 

comma, Cadoceras __________________________________________ 44, 47, 83, 84, 87, pls. 35,36 

commune, Cadoceras sublaeve. _ ------- _______________ -------------------------- 46 

105 
106 INDEX 

compressum, Cadoceras (Stenocadoceras) •. ___________________________ • ________ _ 

.Cosmoceras ••••• ___________________ • _____________________________________ _ 

compressus, Macrocephalites .•. ------------ __________________________ -------- __ 

Concretions._. ____ --------- ____ ------------- _______________ ------------- ____ _ 

Page 

46 

100 

96 

57 

concinnum, Pseudocadoceras _____ _______________________ ------ _________________ 48, 94 

Conglomerate. ________________ ------ _________________ ------__________________ · 57 

coronatum, Erymnoceras __________________________________________ 46, 48, 53, 55, 56,72 

cosmopolit11;, Kheraiceras ___ ________________________________ ~ ________ -------- 79, 80, 81 

Cosmoceras ____________ ----------- _________________________ --------------- 56, 58, 100 castor __ ~__________________________________________________________________ 55 

compressum ______ ______________________________ -~ ________ ----------------- 100 

jason.-------------------------------------------------------- 45, 46, 48, 53, 56,72 spinosum ____ ___________________ ---~- _______ ~--- ______________________ 48, 53, 100 

(Cosmoceras) spinosum ___ -------------------------------------------- 100, pl. 53 ( Gulielmiceras) ________________________________ ------ _____________________ 51, 55 

alaskanum _____________________________ ----------------------- ____ 100, pl. 49 

(Cosmoceras) spinosum, Cosmoceras ______ ~-------------------------------- 100, pl. 53 

Cosmoceratidae ____________ -.-- _______________ ----------------------- _________ 48, 58 

Cranocephalites _____________________________________________ 42, 43, 48, 49, 51, 59, 77,78 

crassicostatum, Pseudocadoceras. _ -----------------------~------------ 48, 94, 95, pl. 49 eras sum, Cadoceras ____ ------- _____ ------ _____ ::-___________ ------- __________ 45, 47, 83 

D 

demidofji, Calliphylloceras ________ ------ _ --------- _________________ -------- ___ ._ 73 

densicostatum, Cadoceras (Stenocadoceras) stenolobum. _ ------------------------ 46, 90 

Deposition of Callovian sediments·------------------------------------------- 57-58 

Depth of water ________________________________________________ -~- _______ ----- 59-61 

· doroschini, Ammonites ________________________________________________________ 85, 86 

Cadoceras ____________________________________________ 45, 47, 56, 84, 85, 86, 87, pl. 39 

durum, Cadoceras. ______ ------------- ________ -----------·------------- _ ______ __ 46 

Cadoceras (Stenocadoceras) __________ . ___________ ----------------- ___ ___ _ ___ 46 

E 

Ecology. _____________ " ___ --- ____ --.------------ _______________________________ 57-.65 

elatmae, Cadoceras _______________ ------ ____ ------ ____ --------- ____ 44. 45, 51, 83, 88, 90 

Cadoceras (Paracadoceras) _________ ---------- _____________ ------- ___ ___ ____ 44 

ellit:ticus, Arctocephalites _______ ------ __________ ------------- ___________ ------ _ 77 Erycites___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 55 

Ergm'lioceras .. ________________________________________________ ~ ________ .. __ c _ _ _ 56 

coronatum •••• -------------------------~--------------·-------- 46, 48, 53, 55, 56,72 

Eurycephalites _ ---------~------- --------- ______________ ------- ___ ------- ___ 42, 56, 57 

· evolutus, Procerites ... ~----- ----- __ -------- ______ ------- ____ _ _ _ ___ _ __ __ __ ___ ___ i02 

Exogyra ________ __________________ ------ ___________________________________ ~--- 64 

F 

Faunal assemblages._------- ______________ --------------'---------- ___________ 58-59 

Fischer quoted __ ------------------------------------------------------------- 43 (ranciscus, Cadoceras. __________________ ~- ________ ~ _ _ _ _ _ _ __ _ __ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 45 

frearsi, Cadoceras (Paracadoceras) _____ ------------------------ _________ ------- 44, 88 

freboldi, Cadoceras ____ ____ ----------------------------------------- ___ ___ _ ___ __ 45 

lreibrocki, Phglloceras (Calliphglloceras) __________________________________ 72, 73, pl. 26 

funatus, Procerites __ ------------------ _______________ ------------- ___ _ __ _ ___ __ 102 

funiferum, Longaeviceras _ _ ____ ___ ____ ___ __ __ _ ___ ___ ____ ___ __ __ ___ _ __ _ ___ _ _____ 46 

G 

gitinsi, Kepplerites ____________________________________________________________ 97, 99 

Kepplerites (Seymourites) ______ --------------------------------------- _ 98, pl. 52 Yakounoceras ___________________________________________________ ; _. _ _ _ _ _ _ _ 98 

glabrum, Cadoceras ____________________________________________ 44, 45, 83, 84, pls. 36,37 

globulatum, Kheraiceras _ ------------------------------------ __________ -------- 80 

Gowericeras _____ ~---------------------------------------- 48, 51, 53, 54, 55, 58, 59, 71,72 approximatum _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ __ 100 

childanum. -·------------------- ___ ------- ____ ----------------------------- 99 

snugharborense"·-------- ____________ ---------·--- _ ---------------~- 99, 100, pl. 53 

spinosum. --------------------------------------------- ____ ------------ 99, pl. 53 toricelli. _. _ _ _ __ _ _ __ __ __ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 99 

trichophorum ••. ___________________ ~ ________ ·_ _ _ _ __ _ _ __ _ _ _ _ _ ___ _ _ _ _ _ _ _ _ _ _ _ _ _ 99 

ventrale _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 100 

sp _____________ -- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 100 

grantzi, Phyiloceras (Partschiceras) __________________________________________ 73, pl. 25 

greppini, Reineckeia ____ _______ ------- ________________________ ------------ _____ 102 

grewingki, Cadoceras ________________ _____________________________ ---------- ____ 93, 94 

Pseudocadoceras ______________________________________ 48, 57, 71, 88, 91, 93, 95, pl. 49 

Grossouvria.------------------------------------------------- 48, 51, 71,102, 103, pl. 55 

Gryphaea. __ ------------------ _____ ~ _________________________________ --------- 59, 64 

impressimarginata _________ ____________ ------ _______________ ---------- _____ 49, 59 

Gulielmiceras _______________________________________________________ 48, 51, 53, 71,100 

gulielmii. ____ ------------------ _________ ------ _ __ _ _ _ ___ __ _ _ __ _ _ _ _ ___ ______ 101 

( Gnlielmiceras) alaskanum, Cosmoceras.---------------------~-----------"- 100, pl. 49 

oulielmii, Gulielmiceras ______ __ --- c __ ---- ________ --- ____ __ _ _ _ _ __ _ _ _ _ __ _ __ _ __ ___ 101 

Gulielmites ________ _____________________ ----- ____________________________ ------ 101 

H Page 

Habitats, Callovian. ________________________ • ________________________________ 64-65 

hartsocki, Xenocephalites ___ ___________________ • _____________________________ 79, pl. 28 

harveyi, Cadoceras (Paracadoceras) _______________________________________ • _____ 44, 89 

Paracadoceras ______ ___ ------- __ -- ________ • _______________________________ • 4(47 

hebetus, Xenocephalites .• --- __ -- _ --- _ --- ______ • ___ ~ _________________________ 78, pl. 29 

henryi, Arcticoceras _________ __________________ • ___ • ________ ------- _ ___ _ ___ _____ 45 

heterophyllum, Phylloceras. __ ___ ___ _ _ ___ __ _ _ __ _ _ __ _ ___ __ _ _ ____ _ __ _ __ _ _ _ _ _ _ _ ___ _ 72 

hians, Procerites .••• ---------- _ ------ _ __ __ _ _ __ ___ _ __ _ _ _ _ _ _ __ _ __ _ _ __ ___ _ ___ _ _ __ _ 102 

I 

impressimarginata, Gryphaea. __ -- _____ -- __ ---- __ ------------ ____________ ------ 49, 59 

ingrahami, Kepplerites (Seymourites) __ ______ ----------------------- 97, pls. 48, 50,51 Yakounoceras ___________________________________________ ~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 97 

iniskinense, Cadoceras (Stenocadoceras) _____________________________ 46, 91, 92, 95, pl. 46 

Inoceramus --------------------------- ________ ----------- ______ ------ ____ ----- 57 

intermedium, Kheraiceras _______________________________________________ '81, pls. 31,32 

Iutroduction _____________ ~ -------- __ ----- _______________ -------- _ ~ __ _ __ _ __ ____ 41 

irregularis, Procerites ____ ___ ------------ ____________________ -.-- ___________ 102, pl. 54 

J 

jason, Cosmoceras _________ ~------·------------------------------------ 45, 46, 48, 56,72 

K 

Kamptocephalites. ______________ ------------ ____ ------- __ _ __ _ __ _ _ __ _ ___ _ __ _ ___ 79 

Kellawausites .• ----------------------------------------------------- 48, 54, 56, 71,101 (Kellawaysites) oxyptychoides, Reineckeia ______ . __ __________ ------ ____ _ ___ ____ ___ 101 

shelikofana, Reineckeia _____ • ____ --------- ____________________ ~ ------- __ 101, pl. 55 

Kepplerites .•. --------------------------------------- 48, 51, 53, 54, 55, 56, 58, 71, 72,101 

abruptus _______ _ ----- _ ---------- __ --- _______ ------- _ --- _ ------- _ ---------- 97, 99 

gitinsL ____ ____ • ___ -- ____ -- ___ -_-- ___________ -_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 97, 99 

loganianus .. ------- ______ · ________ ---------------- _ -.----------- ___ -------- _ 95, 99 

mcevouL ------------------------- _ ------------------------------- ___ --·--- 96 mclearni. _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 101 

multus ____________ ____________________________ -------- ________ ------ _ __ ___ 98 

plenus _______ _______________ · ______________________________________________ 97, 99 

rosenkrantzi. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 98 

tychonis _____ ---------------------------- _______ ---- ___ --- _ ------ ____ 53, 71, 72, 96 

Kepplerites (Seymourites) abruptus _ ------------------------------------ 98, pl. 52 

alticostatus-------------------------------- ___ ------- ___________________ 95, pl. 48 

oitinsi_ ________ --------------------------------------------------------- 98, pl. 52 

ingrahamL------------------------------------------------------ 97, pls. 48, 50,51 

mcevoyi. _ --------------------------------- _ --- _ ------ ___ --- ____________ 97, pl. 51 

multus __________ ----------------- ___ --- ___ ---------------------- _______ 98, pl. 51 

tychonis _____________ _______ ----- _____ --------------------------- _______ 98, pl. 48 

Kheraiceras .• ----------------------------------· 42, 43, 51, 53, 54, 55, 57, 58, 71, 80, 81,82 

abruptum ••.. -------------------------------------------------·----- ___ 80, pl. 33 bombur ____________ • ______________ -- ___________ • ___ •• _ __ __ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ 82 

cosmopolita •• •• ______________ ------------ ___________ ------- _______ ----- 79, 80, 81 

globulatum ___ __________ -- _______________________ -- ________ --- _ _ _ _ __ _ _ _ _ _ _ _ 80 

intermedium. -------------------------- ___ --------------------- ____ 81, pls. 31, 32 

magniforme •• ---------------------------------------------------- 79, 80, 81, pl. 31 

:~;:;::~~-;-~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~· pl.:; 

parviforme. ---------- _ ---------------------------- _ ------- _ --------- 81, 82, pl. 33 quenstedti. __________________ ._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 81 

varicostatum. ____ --- _ ----------------- _____ ------ _ ---------------- _____ 81, pl. 33 

kialagvikense, Cadoceras. __ ------------------------ ________ ----------- ___ 45, 87, pl. 41 

kochi, Arcticoceras ________________ _ ------- __________ --------------------------- 55 

koenigi, Proplanulites. _ -------~-----------------------·----------- 44, 45, 46, 51, 53, 72 

L 

laminatum, Pseudocadoceras ______ _ --- _ -- _______ ---------------.--- _____________ 48, 94 

Lilloettia ________________________________________ 42, 49, 51, 53, 54, 55, 56,.57, 58, 71, 75,76 

buckmanL------------------------------------------------------- 57, 75, 78, pl. 27 

lilloetensis ______ --------·-------------- __ .__ ----------- _ -- _ ------------ 77, 78, pl. 30 

mertonyarwoodi. _______ ------------------ __ ----------- ________ --------- 78, pl. 30 

milleri. ------------------------- _ -~- ---------- _ --- _ ----- __ --- ____ 75, 77, pls. 28, 29 

stantoni_ ________ --------- _ --- __ ----- _ ---------- _ --- _ ------ ____ --------- 77, pl. 29 

lilloetensis, Lilloettia ____ _____ ------------- ________ ------- _____________ --- 77, 78, pl. 30 

Localities, descriptions. ________ ---------- __________________ --------- ___ ------ 65-71 

·loganianus, Kepplerites _______ _ --- _ ------ ________ --- _ ----- _ --- _____ ------------ 95, 99 

Longaeviceras. _ ---------------- __ --------- _______ --- _ -- _________ -- _ -------- 43, 46, 48 

funiferum _________ . _______ -------------- _____ ----- _ --- _ --- __ -- ____ -~- ------ 46 

placenta._.-------_------------_--- _________ ----- ___ --_-- __ --_---_-------- 46 

Lytoceras .• _____ ---••• ___ ---- _ --------------------- _ ----- __ --- _____ -- _ ----- ___ 53, 60 

M 

mcevoyi, Kepplerites ____ -------- _ -------------------- _ -- _ ---------- _ --- _ ------· 96 

Kepplerites (Seymourites) _ ----------------·---------------------------·-- 97, pl. 51 

Yakounites _________ --------------------------------,------ _ -- __ ---- __ _ __ _ __ 97 

mclearni, Kepplerites _____ _ ---- ___ ---- _ --- ________ ---- _____ --- _ -- __ -- _ _ _ _ _ _ _ _ _ _ 101 
.>-· 

,.,... 

·r--

. INDEX 107 

Page Macrocephalites _______________________ ·_ __ _ _ _ _ _ _ _ _ _ _ _ __ _ _ __ __ __ _ _ _ _ _ _ _ __ _ _ _ __ _ _ 56 

compressus _____ _______________________________________ -- ____ -'- ________ ~- __ 96 

macrocephalus _________________________________________________ 44,45,48, 53, 55,72 

Macrocepballtidae ••• ----- ___ ----- ______________ ----- -----~----- ___________ 42-43, 58 

macrocephalus, Macrocephalites •.•• -------------------------------- 44, 45,48, 53, 55, 72 

Macrophglloceras _____ ------- __ ----- _____ ---------- _______ ----- _____________ 42, 58, 74 

(Macrophylloceras) grossicostatum, Phylloceras ________ ------ ________________ 74, pl. 25 

magniforme, Kheraiceras •••• ------------------------------------------ 79,80,81, pl. 31 martini, Kheraiceras ______________________________________________ ---------- 80, pl. 32 

Meleagrinella. ____________ -~--- _______ ------- _____________ ----- _______________ 59, 72 

milaschevici, Cadoceras _______________________________________________ 44,46, 53,85,91 

Cadoceras (Stenocadoceras) ___________ -------- _ _ _ __ __ __ _ __ _ _ _ _____ ____ ___ __ 46 

mertonyarwoodi, Lilloettia .. ------------------------------------------------ 76, pl. 30 microstoma, l(heraiceras •.• __________________________ ------- _____ _ _ ___ ____ _ __ __ 81 

milleri, Lilloettia. --------•. --- _______________________ ----- __________ .75,. 77, pis. 28, 29 

milletianus, Ammonites ••• _________________ • ________________ ----- ________ . _____ 93, 94 

mojfiti, Cadoceras (Paracadoceras). ---------------------"------------ 44, 87, 89, pl. 42 Morphoccratidae. ------- __ • _________________ • _____ • ______ ----- _______________ 48, 58 

multicostata, Reineckeia ••• __ ----••• __ • ___________________ • __ __ _ __ ____ _ __ _ _ _ _ __ 102 

multicostatum, Cadoceras (Stenocadoceras) __ ----------------- 46, 47, 90, 91, 92, 93, pl. 44 

multiforme, Cadoceras(Paracadoceras) ________________ ·---------------- 44,88,89, pl. 42 

nmltus, Kepplerites. ------- __ • ____________________ -"--- __ • _ ___ __ _ __ __ _ _ _ __ _ __ _ 98 

Kepplerites (Seymourites) •• _. ~ _________________ ------ ____________ .,- ___ 9fi, pl. 51 

Sey1nourites •.. _ ------. ________ • ___________________ ----- __ __ _ __ _ _ _ _ __ __ _ __ _ 96 

N 

nanseni, Pseudocadoceras ____ •• _ -----•• ----- _______ ~ _____________________ 48; 90, 93, 95. 

neuquensis, Xenocephalites .• _____________ ------ _____ ----- __ • _ ____ __ _ __ _ __ _ _ _ __ 78 

nikitini, Cadoceras. ___________________________________________________________ 43, 92 

Cadoceras (Stenocadoceras) ___ _. ________________ ----- _ _ _ _ _ __ _ _ _ _ _ _ __ __ ___ _ _ _ 46 

Xenocephalites •• _______________________________ • ___ ---- __ _ _ _ __ _ __ _ __ __ ____ 79 

0 

occlusum, Cadoceras variabile ••• _ ------ _ _ _ ___ _ __ __ _ _ _ __ ___ __ ___ __ __ __ __ _ __ ___ __ 45 

Occurrence of ammonite species, table ••• ---------------------------------- facing 72 Oppelia calloviensis. _. ---•• ___ ----- _________________ ----~-- -- ___ __ __ _____ ___ __ .75 

Oppelia (Oxycerites) •••• ~------------------------------------------------ 51, 58, 71,74 aspidoides __ •• _ •• _. ___ •• _. __ • ____ • _ ••• __ • _____________ •. _. _______________ ~ _ 7 5 

chinitnana •• ---------------.--- __ • ---------. __ • ---------•• ---- ___ ----- __ 7 4, 75, pl. 26 

sp. ------------------ __ ---- __ ------- -~---- __ ------- __ ----- _____________ 75, pl. 26 

Oppelldae ••••• --- __ ----- __________ ----------------------------- __________ ----- 58 

orbigngi, Psettdocadoceraa ••.. _ ------------ ________ -------- _ ----- _ ------ ________ 48, 94 

orbis, Cadoceras •••••••••• ___ ----- _____________ ---------------- ____ ------- _ ____ 46 

Ostrea ••••••••• _. __ •• _. _ •• -.-•• ___ •• ___ • ___ • _. _____________ • _ •• _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ 59, 72 

Oxgcerites •••••• ___________________________________________________ 51, 53, 54, 71, 74,75 

( Oxgcerites) aspidoides, Oppelia _______ ---------- __ ----------------------------- 75 

chinitnana, Oppelia ••• ---------------------------------------------- 74, 75, pl. 26 

Oppelia, sp_. ----~ -------- ________ ------------------------ _____________ 75, pl. 26 

oxyptychoides, Reineckeia. -------- __ ----------- __ ------------------------------ 102 

Reineckeia (Kellawagsites) ••• ~-- __ ------ _____ --------- __ ----------- _ __ ____ _ 101 

p 

Paracadoceras ______________________________________ 44,45,48, 51,53, 54,55,56,59, 71,72 

harveyL •••••. ---------- _______ --------- _____ ----- _______ -- _______ ------- __ 44, 47 

(Paracadoceras) ammon, Cadoceras •• ------- _______ ------------ __ _ __ __ __ _ __ ____ 44 

breve, Cadoceras ••••.• ____ ---------- _________ • _ --~ ______ •. __ __ __ _ ____ __ __ _ _ 44 

chisikense, Cadoceras. _ ---------------------------------------------- 44, 89, pl. 43 elatmae, Cadoceras .• ___ ------------------ ________ ------ __ _ _ ___ _ _ __ __ __ ____ 44 

frearsi, Cadoceras. _. _ ---------- __ ----- _______________ •••. _________________ 44, 88 

harveyi, Cadoceras. ------------- ___________________________ .• : _____________ 44, 89 

mojfiti, Cadoceras ••••.•.•.•.• ------------------------------------ 44,87,88, pl. 42 multiforme, Cadoceras _____________________________ ~-------------- 44,88,89, pl. 42 

1JSeudoishmae, Cadoceras •• ------------------------------------------------ 44 schumarowi, Cadoceras ______ ---------- _____________ -----·- _ ___ __ __ _ ____ __ _ _ 44 

tonniense, Cadoceras ••.•••••• ------------------------------------ 44,88,89, pl. 43 parvus angustiumbilicatus, Xenocephalites ______________________________________ . 79 

Partschiceras •• __ ----------------- ____ ----- ___________ ----- ______ ----- __ ------- 42, 58 

(Partschiceras), Phylloceras _____ __ ----- _________________ ----- __ _ _ _ __ __ ___ __ __ __ 73 

grantzi, Phglloceras ••• -------------------------------------------------- 79, pl. 25 subobtusiforme, Phylloceras. _ ----------- _________ ----- _____ • _________________ 79, pl. 25 

parviforme, Kheraiceras •• _ ---------------------------------------------- 81, 8£, pl. 33 Peltoceras •••••••••.• ----- ________________________ ------- _. --- __ ___ __ _____ ___ __ 56 

athleta •• -·--------- ___ ---- ______________________ -----•. _ _. __________ ------- 56 

petelini, Cadoceras _. _________ --- __ __ _ ____ __ ___ __ _ _ ___ __ _ _ ___ __ _ _______ _____ ___ 93 

Pseudocadoceras ______________________________________________ 48,90,9£,95, pl. 48 

plenus, Yakounites •. _____ •. ----- _ ------- _____________ -------- _____ ___ __ __ ___ __ 99 

Phylloceras •• _ ---------------------------------- 42, 51, 53, 54, 55, 57, 58,.59, 60, 71, 72-74 

bakerl •••• __ --- ___ • _______________ -----~-- __ ----- _____ ----- __ ----------· 7£, pl. 25 chantrei. _________ • _____________________ • _____________ • ___________________ • 73 

heterophyllum •• ____________________ ·------------- __ ------------------- __ _ __ 72 

subobtusiforme ••• _______________ ------- ___________ ------ ____ ----- _________ 73, 74 

subobtusttm. ---- __________ ----- __ ------·------------------- _ ___ _ _ ___ ____ _ _ 73 

Page 

Phulloceras ( Calliphylloceras) __ ---- ________ ---.... __ ..•.... --.... ____ . _ --... _ _ _ 73 

freibrockL .. ------------------------------------. ____ . _· _______ ---- __ 72, 79, pl. 26 

Phylloceras (Macrophylloceras) grossicostatum ____________________ "----~----- 74, pl. 25 

Phylloceras (Partschiceras) ______________ _. _____________ _ ---.---.-------.---- ____ 73 

grantzi_ __________________ ----------- ____ ------. __ .. ___ .. __ . -~ _____ .. --- 79, pl. 25 

subobtusiforme •. -----·---------------- ___ . _____________________________ 79, pl. 25 

Pbylloceratidae _____________ ---------- ~ _____________________ --.- __ -------- __ 41-42, 58 

Phyllopachyceras •• _ ------ ___________________ ... __ _ __ ____ __ ___ _ _ _ _____ _ _ _ __ __ __ 74 

placenta, Longaeviceras ••... ____________________ • --- _ ___ _ _ _ ___ _ _ _ __ __ _ _ _ _ _ _ __ _ _ 46 

plana, Reineckeia. __ ----- __ ------ _ ----- ___________________________ • _ _ _ __ _ _ ___ _ 102. 

platystomus, Ammonites ...•• _____ • ____________ .•. _____________________ ------__ 81 

plenus, Kepplerites _____ ____________ ~ _ ------ __ .... _________________ • ___________ 97, 99 

Seymourites ___ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 99 

Pleurocephalites •..• -------------------- ___ • ________________ • _______________ 42, 56, 78 

pomerogense, Cadoceras (Stenocadoceras) ----------------------------- 46, 92, pis. 45, 46 Procerites ________________________________________________________ 48, 51, 54, 57, 71, 102 

evolutus .••.• ------- ____ • ------- ___ ------ __ . _ _ _ _ _ _ _ _ _ ___ _ ___ _ __ __ _ __ _ ___ _ _ _ 102 

funatus •.• ------------- ___ --------- ____ . ----. ___________ ---- _ _ _ _ _ _ _ _ _ _ __ _ _ 102 

hians ___________ ----- ______ ----- ___ -----.----- _ ___ _ __ _ _ _ _ ___ _ __ __ _ _ _ _ _ __ ___ 102 

irregularis ____________ ___ --.---- _ -------·- ____ . _________________ • __ • ____ 10£, pl. 54 

. spp ___________ . -------- _ ------ ____________ --- _________________________ 102, pl. 53 

Proplanulites _____ ________________ ---------- ______________________ •• _ __ _ ___ _ _ _ _ 56 

koenigL _ ---------- ___________________________________ ------ __ 44, 45, 46, 51, 53, 72 

Pseudocadoceras ___________________________ 41,43,44,46,48,49,51, 53,54, 56, 58, 59, 71,72 

boreale •.• --------- __________ --------- __________________________________ 46, 48, 94 

chinitnense .•. __________ ----- ________________ --- ________________ • ____ 48, 94, pl. 48 

concinnum •..• ------- _____________ ------- _ ------ _________ ----- ____________ 48, 94 

crassicostatum ..•• ~-------------------------------------~--------- 48,94, 95, pl. 49 

grewingki. ..• ---------------------------------------- 48,57,71,88,91,99,95, pl. 49 laminatum .•. ___________________ ----- _____________________________________ 48, 94 

nanseni. .•. ------ __________________ · ________ • --- _________________ . ___ 48, 90, 93, 95 

orbigngi_ ___________ ------------------------------------------------------- 48, 94 

petelini. ----------- ________________________________ -------- ___ 48, 90, 92, 95, pl. 48 

schmidti.. _________________________________________ ~-------------- 48, 91, 95, pl. 49 

pseudoishmae, Cadoceras (Paracadoceras) -------- ______________________ ------ _ __ 44 

Pseudolioceras. ----- __ . __ :. __ • __ •• _ •• __ • ____ •...... _________ •• ___ .• __ •.••..• ---. 55 

Q 

quenstedti, Cadoceras •. ----- ________________ -- _ --- ________ --------------.. _ ---- 44, 83 

Kheraiceras ___________ ----- ___ ----- _ --------- ________ -------------------. _ 81 

Quenstedtia. _. _. _ ••• _. _. _. __ •• _. ___ • ______ •.. _ ... _________________________ •••• 59 

Quenstedtoceras. ________________ •• ____ --· ___ . ------- ______ ------.• -----.------ 43, 48 

R 

Reineckeia ••• ----------------------------------------------: •. ~ 48,54,55,56, 58,59, 71 bukowskii. •• __ . _______________________ ••.• -·-. ________ --~ •• __ --. _ ---. _..... 102 

greppini. •••. ------------------ __ • __ --- ~----. _ ---.---.-------------------- 102 

· multicostata .•.•••.•• ------- ____________ -----. __________ ------ ____ ---- _ --- _ 102 

plana •. _.---- _____________ ._ .• ________ •...•.•• ___ • ____ . __ •. _._ ••. _ ..••... _ 102 

oxvptgchoides ______ ___________ . ________ -~----. ____ ---- _ ----. __ ----------- __ 102 

shelikofana ••.•.... ---------.----- _ .... ---.----.---------------.----------- 101 

Reineckeia (Kellawaysites) __________________ ---.-- ____ --- ~- _ ---------------.-- 54, 101 

oxgptgchoides. ________ • ________________ . __ .... _____________ • _. _ •••• _ •• _.... 101 

shelikofana ••••.. ------- ___ ----- _________ .. --. ____ • ----.---- _· ___ . _ ----. 101, pl. 55 

Reineckeites •. ________ ~-- ____________________ ----. ____ -------- ______ ---··-----. 48, 56 

rosenkrantzi, Kepplerites •••••. ______________ . --... __ --·------- _ ---------------- 98 

rugosum, Cadoceras sublaeve ... ______ -- _____ • _. ____ ------ ________________ • __ 48, 83, 87 

s 

Sandstone. ____ -·---- _____________________ ------- ____ .-.--_---.---_ •. --..• __ ..• 57 

Scaphites _____ _____ . _____ ------ __ ----- _____ ...•...• __ .. ----- __ . --- _ ------------ 96 

schmidti, Cadoceras ______ ----------- _______ ---.---- __________ --- _____ ----. _ __ __ 95 

Pseudocodoceras _____ ----- ____ • ________ .• ----- _____________ ----"-- 48, 91, 95, pl. 49 

schumarowi, Cadoceras. ________ ----- ______ .• ------- ____________ -------- __ ----- 44 

Cadoceras (Paracadoceras) ----- ________ .. ---..•. _ .. _ ------.. --------------- 44 

Scouring during deposition of sediments._------------------------------------ 57 

Sediments, conditions of deposition.---------------------------------·--------- 57-58 

(Segmourites) ___ ----- ___________ -------- __ --.. ---. --.----.--- _ --- _ ----.----.-- 48 

multus ______ ----•• -------------------·-. ----.---.------.. --.. __ • -- _·_ -----.. 96 

plenus ••.. --------------------- _______ . ------------ ____ . ___ . ___ .. __ . ----.. 99 

abruptus, Kepplerites •... ----------------------------------------------- 98, pl. 52 

alticostatus, Kepplerites. __ ----------------------------------------------95, pl. 48 

gitinsi, Kepplerites _. ----------- _____ -------......... -------. __ . ---...•.• 98, pl. 52 

ingrahami, Kepplerites ________________________ ------------------- 97, pls. 48, 50, 51 

mcevogi, Kepplerites ___________ ________ -----••••. ---.---.----------.---- 97, pl. 51 

multus, Kepplerites ••. ·------------------------------------------------- 96, pl. 51 

tgchonis, Kepplerites •.•• --~---. ________ ... ----. _ ... : _. -----.-- _ --------- 96, pl. 48 

Sbelikof formation ________________________ --.. --- __________ ----------------- __ 48-49 

shelikofana, Reineckeia ___________ --- __ --------.---. __ . ___ • --------------------- 101 

Reineckeia (Kellawaysite~)----------------------------------~---------- 101, pl. 55 

shoshonense, Cadoceras. ___ ----- _____________ .. ---- ________ ------------ ________ 45, 47 
108 INDEX 

Page 

Sigaloceras _________ _________ ----- _____ -- _ ---- _ ----------- _ -------------------- 101 · calloviense _______________________________________ ~------- 44, 45, 46, 48, 51,.53, 55,72 

Sivajiceras _____ ------ __ -------------------.-- _ -----.-------------------------- · 102 

simulans, Cadoceras __________ ~------------ _________ --------------------. ___ _44, 45, 83 

snugharborense, Gowericeras.------------------------------------------- 99, 100, pl. 53 

spinosum, Cosmoceras _____ --------- ____ ••• ------------- _ ----------- _______ 48, 53, 100 

Cosmoceras ( Cosmoceras) ------------------------------- ___ ------------ 100, pl. 53 Gowericeras ______ _____ • ________________________________________ -------- 99, pl. 53 

stantoni, Lilloettia ••..... ___ . __ . __ . __________________ . ________ . ------ __ . --- _ 77, pl. 29 

Stenocadoceras. ____ ------ ____ --------- _______ ... _ ---------.-----.--------- _ 46, 48, 71 

(Stenocadoceras), Cadoceras ______ __________ ------------------------ _ --.----.---- 71, 72 

bowserense, Cadoceras ______________ . ___ -------"----------------- ____ 46, 91, pl. 43 

compressum, Cadoceras ___ ------ ___ . -------"------- __ ------ _______ -------- 46 

dubium, Cadoceras ___________ . ----.• ------------- ____ --------------------. 46 iniskinense, Cadoceras _________________________________________ 46, 91, 92, 95t pl. 46 

milaschevici, Cadoceras ___________ ---------- ______ . ----- _ --- ____ -__ . -------. 46 

multicostatum, Cadoceras ________________________________ 46, 47, 90, 91, 92, 93, pl. 44 

nikitini, Cadoceras ___________ ------- ~-- ___ . __ . ___ ------ _ ---.-------------- 46 pomeroyense, Cadoceras __________________________________________ 46, 92, pls. 45,46 

stenoloboide, Cadoceras.--~--------------------------------------- 46, 92, pls. 46,47 

stenolobum, Cadoceras. ____________ ---.----- _ ----------- _ ------------------ 46 

stenolobum densicostatum, Cadoceras -------------------------------------- 46,90 

striatum, Cadoceras _ ------------------------------------------------ 46, 90, pl. 45 stenoloboide, Cadoceras __ . _______ ------ ___________ . _____________ . __ --~ --- 57, 86, 91, 92 

Cadoceras (Stenocadoceras) ___ ----------------------------------- 46, 92, pls. 46,47 

stenolobum, Cadoceras ________________________________________________ 43, 53, 87, 91,92 

Cadoceras (Stenocadoceras) __ . ______ . -----... -... ----------------------.--- 46 

densicoStatum, Cadoceras (Stenocadoceras) __ • ·----------------------------- 46,.90 

Stephanoceras ____________________ .. ____ •.. -.--- _-•.• __ -.- _-. _. ____ • _.--.... --- 43 

Stratigraphic summary ____ . __________ --··-------_-----.---------.. ----------- 48-51 

striatum, Cadoceras (Stenocadoceras)---~----·------------------·-----·--- 46, 90, pl. 45 

Subgrossouvria .. __ . _ .. _ .. _. __ . __ • -.- ___ . __ --..... _ .. _ .. -··. _ ..... _____ .--.-----. 56 

sublaeve, Cadoceras ____ _______ ------ ______ -------·---·------ ____________ ----. 46, 47, 56 

commune, Cadoceras. __ -----·--------- ____________ ------------------------ 46 

rugosum, Cadoceras. ___________ ·---- _ --------- ___________________ ------ 46, 83, 87 

:~~~~~::;f:r::~;~~~:~c~;~; ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 73, ~! Phylloceras (Partschiceras) _ _. ___ • ________ _. __ ----- ______ . _____ . ___ . ------ 79, pl. 25 

subobtusum, Phylloceras ___ __________ -·. --· ----- _ --.--------••. --------------·- 73 · 

subpatruum, Cadoceras _____ ------ __ ------------------------- _ ------------.---- 45 

Summary, faunal and stratigraphiC------------------------------------------· 71 

surense, Cadoceras. _ ----···--------- __ ----------.. ---------·------------------· 45 

sysolae, Cadoceras •.. _________ . _____ -------.... _. ---.-.----.--------·--. ---•.. -- 46, 84 

T Page 

Tancredia. ____ ---;------·-------·-----. _. ---------·------------- ~--- --------- 59 

tchefkini, Cadoceras ... _____ _. ___________ ------------------------------------·--- 46, 85 

Temperature and climate _____ .------ _____ - __ -------------------------·--.---- 61-64 

tenuicostatum, Cadoceras .. -------------------------·---·------------- 45, 85, 86, pl. 38 

tolype, Cadoceras ______ ---------·-. ------------------ --~- --·----·--·· ---------- 46 

tonniense, Cadoceras (Paracadoceras) _ ----------·----·---------··---·- 44, 88, 89, pl. 43 

toricelli, Gowericeras ______ --------·--· -·- _ -------.----------.----------------- 99 

trichophorum, Gowericeras __ · ______ ·-·--- _ -~--:-- ---.--------------------------· 99 

tschernyschewi, Cadoceras .. -------------. ___________ ------------------------ 44, 45, 84 tychonis, Kepplerites ____________________________________________________ 53, 71, 72,96 

Kepplerites (Seymourites) •• --------------------------------·----------- 96, pl. 48 

v 

V(lTiabile, Caddceras. __ . ------ _ ·-- _________ ---.. --- _- ---.---.------------------ 45 

occlusum, Cadoceras __ •. _______________ ----------.----------·--·----------- 45 

varicostatum, Kheraiceras ___ . ______ --------------.-----------·-----. -----··- 81, pl. ~3 

ventrale, Gowericeras. __________________ ------------- ----------~-- ------------- 100 vicarius, Xenocephalites _________________________________________________ 78, 79, pl. 28 

victor, Cadoceras __ ----------------------------------. ------··-·-•••••• ----··-- 44, 87 

Vulcanism ____ -------·-------------------------·-·-·--··-···-·------.-------- 57 

w 

Wosnessenskii, Ammonites ... ___ . ____ ----------------_-----··· ••• _---.--·--~-- 86 

Cadoceras.------------------------------··---------··-----··-- 45, 84, 86, 87, pl. 40 

X 

Xenocephalites _________ ~------------------------------------ 42, 51, 53, 55, 56, 58, 71,79 

hartsockL ____ . ___ . ___ . --------------. ____ . ___ . ___ .. ________ . ---------· 79, pl. 28 

hebetus _____ _____ ------------ ____ --------------· -------- _ ---- _ ---------- 78, pl. 29 

neuquensis ..• _ •• ______ " _____ . ___ . ___ . ____________ • _____ . _. __ ...• _. _ .. --.. -- 78 

nikitini. ______ . _. _. _ .•. __ ••• _ •. _ •• __ .•. _ .•. __ ...... _ ... _ .. __ • _____ -_------ 79 

parvus angustiumbilicatus •• -------------~-------------- ----·---. ---------- 79 

vicari'~s •. ____ ·-------------- ____ ----------------- ____ ----~------ -- _. 78, 79, pl. 28 

y 

Yakounites mcevoyL. ___ • _______________ ~ ____ -- __ .. ------- _ --·- ____ . ___ --·--- 97 

plenus .... -"------------ -~- ---------·--·---------.-- _ ----.---.---.-------- 99 sp. A. _______________________ ---·---- ____________________________ . ___ .---- 97 

Yakounoceras abruptum ___ _________ -------.• ----· •• -----------------------.---- 98 

gitinsi. __ --·------ ____________________ • ___________ . --------.----.--.. -----. 98 

ingrahami. •.••.• ___ . _________ . ________ . --------. _ ... ---..... _ ---.. _ .. ----. 97 
PLATES 25-55 

'· 

.· 
PLATE 25 

[All figures natural size] 

FIGURES 1-3, 8. Phylloceras (Partschiceras) subobtusiforme Pompeckj (p. 73). 

1. Plesiotype, U.S.N.M. 108010, from U.S.G.S. Mes. loc. 22411, Chinitna formation. 

2, 3. Lateral and ventral views of plesiotype, U.S.N.M. 10801.1, from U.S.G.S. Mes. loc. 21348, Chinitna formation. · 

8. Plesiotype, U.S.N.M. 108009, from U.S.G.S. Mes. loc. 3029, Chinitna formation. 

4-7, 9. Phylloceras (Partschiceras) grantzi Imlay, n. sp. (p. 73). . 

4, 5, 9. Holotype,·u.S.N.M. 108012, from U.S.G.S. Mes. loc. 22432, Chinitna formation. 

6, 7. Paratype, U.S.N.M. 108013, from U.S.G.S. Mes. loc. 22432, Chinitna formation. 

10, 14. Phylloceras bakeri Imlay, n. sp. (p. 72). 

10. Paratype, U.S.N.M. 108005, from U.S.G.S. Mes. loc. 2990, Chinitna formation. 

14. Holotype, U.S.N.M. 108004, from U.S.G.S. Mes. loc. 10997, Chinitna formation. 

11-13, 15, 16. Phylloceras (Macrophylloceras) grossicostatum Imlay, n. sp. (p. 74). 

11. Suture line of paratype, U.S.N.M. 108017, from U.S.G.S. Mes. loc. 11047, Chinitna formation. 

12, 13. Paratype, U.S.N.M. 108015, from U.S.G.S. Mes. loc. 2921, Chinitna formation. 

15. Suture line of paratype, U.S.N.M. 108016, from U.S.G.S. Mes. loc. 3029, Chinitna formation. 

16. Holotype, U.S.N.M. 108014, from U .. S.G.S. Mes. loc. 3015, Chinitna formation. 

~.· 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 25 

~ I 

9 

16 

PHYLLOCERAS 
GEOLOGICAL SURVEY _, PROFESSIONAL PAPER 249 PLATE 26 

PHYLLOCERAS AND OPPELIA 
. ,, 

·a 

PLATE 26 

[All figures natural size] 

FiGuREs 1, 2. Oppelia (Oxycerites) sp. (p. 75). Lateral view of specimen, U.S.N·.M. 108019 from U.S.G.S. Mes. ~oc. 3020, Chinitna 

formation. 

3-6. Opp'elia (Oxycetites) c'hinitnana Imlay, n. sp. (p. 74). Lateral, apertural, ventral views and suture line of holotype, 

U.S.N.M .. 108018 from U.S.G.S. Mes. loc. 3029, Chinitna formation. 

7-11. Phylloceras (Calliphylloceras)freibrocki Imlay, n. sp. (p. 73). 

7. Paratype, U.S.N.M. 108007 from U.S.G.S. Mes. loc. 2941, Chinitna formation. 

8, 9. Paratype, u:s.N.M. 108008 from U.S.G.S. Mes. loc. 11047, Chinitna formation. 

10, 11. Holotype, U.S.N:_.M. 108006 from U.S.G.S. Mes. loc. 3104, Shelikof formation. 
PL.ATE·27 

[All figures natural size] 

FIGURES 1-9. Lilloettia buckmani (Crickmay) (p. 75). 

1. Plesiotype, U.S.N.M. 108022 from U.S.G.S. Mes. loc. 21322, Chinitna formation. 

2, 5, 8. Plesiotype U.S.N.M. 108025 from U.S.G.S. Mes. loc. 21359, Shelikof formation. Figs. 2 and 8 represent ~ 

rubber mold of the interior of the specimen shown in fig. 5. 

3. Plesiotype, U.S.N.M. 108026b from U.S.G.S. Mes. loc. 21360, Shelikof formation. 

4. Suture line of plesiotype, U.S.N.M. 108023 from U.S.G.S. Mes. loc. 19902, Shelikof formation. 

6. Plesiotype, U.S.'N.M. 108024 from U.S.G.S. Mes. loc. 21332, Chin.itna formation. 

7, 9. Plesioty~e, U.S.N.M. 108021 from U.S.G.S. Mes. loc. 3029, Chinit~a formation. 

~· 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 27 

LTLLOETTIA 
~ .. 1'. t .. . 't 1 t 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 28 

3 

LlLLOETTIA AND XENOCEPHALTTES 
··' 

,. 

... 

PLATE 28 

[All figures natural size] 

FIGURES 1-8. Xenocephalites vicarius Imlay, n. sp. (p. 78). 

1, 2: Lateral and ventral views of complete body chamber of paratype, U.S.N.M. 108042 from U.S.G.S. Mes. loc. 

22437, Chinitna formation. 

3, 4. Lateral views of paratype, U.S.N.M. 108043 from U.S.G.S. Mes. loc. 3028, Chinitna formation. 

5, 6. Paratype, U.S.N.M. 108044 from U.S.G.S. Mes. loc. 21321, Chinitna formation. 

7, 8. Lateral and ventral views of complete body chamber of holotype, U.S.N.M. 108041 from U.S.G.S. ,Mes. loc .. 

22437, Chinitna formation. 

9, 10, 12. Xenocephalites hartsocki Imlay, n. sp. (p. 79). 

Ventral, lateral and apertural views of holotype, U.S.N.M. 108045 from U.S.G.S. Mes.loc. 21341, Chinitna formation. 

11, 13-15. Lilloettia milleri Imlay, n. sp. (p. 75). 

11, 14. Paratype, U.S.N.M. 108029 from U.S.G.S. Mes. loc. 22434, Chinitna formation. 

13, 15. Holotype, U.S.N.M. 108027 from U.S.G.S. Mes. loc. 21322, Chinitna formation. 
PLATE 29 

[All figures natural size] 

FIGURES 1.:...5, 9, 10. Lilloettia stantoni Imlay, n. sp. (p. 77). 

1. Plesiotype, U.S.N.M. 108037b; 5, plesiotype, U.S.N.M. 108037a. Both from U.S.G.S. Mes. loc. 21359, 

Shelikof formation. · · 

2, 3, 9, 10. Holotype, U.S.N.M. 108035 from U.S.G.S. Mes. loc. 11049, Chinitna formation. Figs. 9 and 10 

are from a rubber cast of the interior of the holotype. 

4. Paratype, U.S.N.M. 108036 from U.S.G.S. Mes. loc~ 3028. 

6-8, 11. Xenocephalites hebetus Imlay, n. sp. (p. 78). 

6, 7. Ventral and lateral views of complete body chamber of paratype, U.S.N.M. 108039 from U.S.G.S. Mes. 

loc. 22434, Chinitna formation. . 

8, 11. Aperttiral and lateral views of holotype U.S.N.M. 108038 from U.S.G.S. Mes. loc. 21329, Chinitna 

formation. 

12, 13. Xenocephalites sp. juv. cf. X. hebetus lmlay n. sp. (p. 78). 

Specimen U.S.N.M. 108040 from U.S.G.S. Mes. loc. 3028, Chinitna formation. 

14, 15. Lilloettia milleri Imlay, n. sp. (p. 75). 

Septate penultimate whorl from which the body chamber bas been removed. Paratype, U.S.N.M. 108028 

from U.S.G.S. Mes. lac. 21322, Chinitna formation. 

,. 

.. 

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GEOLOGICAL SURVEY 

1 

r 

....... 

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LILLOETTIA AND XENOCEPHALITES 

PROFESSIONAL PAPER 249 PLATE 29 
GEOLOGICAL SURVEY 

1 

5 

9 

LILLOETTIA 

10 

PROFESSIONAL PAPER 249 PLATE 30 

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PLATE 30 

[All figures natural size] 

· FIGURES 1, 2, 4, 8. Lilloettia lilloetensis Criekmay (p. 77). 

1, 2. P~esiotype, U.S.N.M.108034 from U.S.G.S. Mes.loc. 21360,· Shelikof formation. About balfa whori·of 

body chamber has been removed. '. 

4, 8. Plesiotype, U.S.N.M. 108033 from U.S.G.S. Mes.loc. 21340, Chinitna formati'on. 

· 3, 5-7, 9-11. Lilloettia mertonyarwoodi Crickmay (p. 76). 

5, 11. Plesiotype, U.S.N.M. 108030 from U.S.G.S. Mes. loc .. 30~8, Chinitna formation. 

6, 9. Plesiotype, U.S.N.M. 108031 from U.S.G.~. Mes. loc. 21322. About one-third of .a whorl has bee1.1 

removed. · 

3, 7, 10. Plesiotype, U.S.N.M. 108032 from U.S.G.S. Mes. loc. 21362, Shelikof formation. 
PLATE 31 

[All figures natural size] 

FIGURES 1-4. Kheraiceras intermedium Imlay, n. sp. (p. 81). 

1, 2. Paratype, U.S.N.M. 108225 from U.S.G.S. Mes. loc. 3014, Chinitna formation. Body chamber complete, but 

partly crushed. · 

3, 4. Holotype, U.S.N.M. 108223 from U.S.G.S. Mes.loc. 21272, Chinitna formation. 

5-8. Kheraicera·s magniforme Imlay, n. sp. (p. 79). 

Holotype, U.S.N~M. 108047 from Chinitna formation on east shore of Iniskin Bay. Exact location unknown. 

..... ~· 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 32 

KHERAICERAS 
PLATE .32 

[All figures natural size] 

FIGURES 1, 4, 6 .. Kheraiceras martini Imlay, n. sp. ·(p. 80)., 

Holotype, U.S.N.M. 108048 from U.S.G.S. Mes. loc. 22446, Chinitna formation. 

2, 3, 5, 7, 8: Kheraiceras intermedium Imlay, n. sp. (p. 81). 

2, 3, 7, 8. Paratype, U.S.N.M. 108051 from U.S.G.S. Mes.loc. 21334, Chinitnaformation. Figs. 2 and 3 are from 

a rubber cast of the interior of specimen shown in figs. 7 and 8. 

5. Paratype, U.S.N.M .. 108224 from U.S.G.S. Mes. loc. 21273, Chinitna formation. Represents an immature 

form. 
FIGURES 1, 7, 11, 13. 

PLATE 33 ·' 

[All figures natural size] 

Kheraiceras abruptum Imlay, -n. sp. (p. 80). 

V m1tral and lateral views of both penultimate 

U.S.G~S. Mes. loc. 22433, Chinitna formation. 

· chamber. · 

and body whorls of holotype, U.S.N.M. 108049 from 

Note abrupt coarsening of ribbing at beginning of body 

2, 4, .5 .. Kheraiceras v(Lricostatum Imlay, n. sp. (p. 81). 

Suture line, lateral and ventral' views of holotype, U.S.N.M. 108050 froin U.S.G.S. Mes. loc. 20760, 

3,6,8-10, 12. 

Chinitna formation. · 

Kheraiceras? parviforme Imlay, n. sp. (p. 82). 

3. Paratype, U.S.N.M. 108053c; 6, paratype, U.S.N.M. 1080538.; 12, paratype, U.S.N.M. 108053b. All 

from U.S.G.S. Mes. loc. 21334, Chinitna formation. · 

8-10. Holotype, U.S.N.M. 108052 from U.S.G.S. Mes. loc. 21334, Chinitna· formation. Note apertural 

constriction. 
GEOLOGICAL SURVEY PROFESSIONAl, PAPER 249 PLATE 33 

KHERAICERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 34 

-·

CADOCERAS 
.).. 

• 

PLATE 34 

. [All figures natural size] 

FIGURES 1-14. Cadoceras catostoma Pompeckj (p. 82). · 

1, 4, 5. Plesiotype, U.S.N.M. 108056 from U.S.G.S. Mes loc. 21288, Chinitna formation. 

2, 3. Plesiotype, U.S.N.M. 108054c; 6, plesiotype, U.S.N.M .. 108054b; 12, 14, plesiotype, U.S.N.M. 108054a. 

All from U.S.G.S. Mes. loc. 2921, Chinitna formation. 

7, 11, 13. Plesiotype, U.S.N.M. 108055a; 8-10, plesiotype,. U,S.N.M. 108055b. Both from ·u.S.G.S. Mes. loc. 

3028, Chinitna formation . 
PLATE 35· · 

[All figur~s natural size] 

FIGURES. 1-8. Cadoceras comma Imlay, n. sp. (p. 83). 

1, 2. Paratype, U.S.N.M. 108063 from U.S.G.S. Mes. loc. 21349, Chinitna formation. 

3. Suture line of paratype, U.S.N.M. 108059b from U.S.G.S. Mes. loc. 3029, Chinitna formation . 

. 4, 5. Paratype, U.S.N.M. 108058b from U.S.G.S. Mes. loc. 21348, Chinitna formation. 

6. Paratype, U.S.N.M. 108059a from U.S.G.S. Mes .. loc. 3029, Chinitna formation. 

7, 8. Paratype, U.S.N.M. 108059c from U.S.G.S. Mes. loc~ 3029, Chinitna formation. 

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GEOLOGICAL SURVEY 

CADOCERAS 

PROFESSIONAL PAPER 249 PLATE 35 

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GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 36 

CADOCERAS 
.PLATE 36 

[All figures natural size] 

FIGURES 1-5. Cadoceras comma Imlay, n. sp. (p. 83). 

1, 2. Holotype, U.S.N.M. 108057 from U.S.G.S. Mes. loc. 21348, Chinitna formation.· 

3. Sectional view of paratype, U.S.N.M. 108060 from U.S.G.S. Mes. loc. 2921, Chinitna formation. 

4. Paratype, U.S.N.M. 108061 from U.S.G.S. Mes. loc. 3020, Chinitna formation. 

5. Paratype, U.S.N.M. 108058a from U.S.G.S. Mes. loc. 21348, Chinitna formation. 

6. Cadoceras glabrum Imlay, n. sp. (p. 84): Paratype, U.S.N.M. 108067 from u:s·.G.S. Mes. loc. 3029, Chinitna formation. Shows complete body chamber. 
PLAT;E· 37 

[All figures natural size] 

FIGURES 1-9. Cadoceras glabrum Imlay, n. sp. (p. 84). 

1. Inner whor~s.of paratype U:S.N.M. 108065c; 2, paratype, U.S.N.M. 108065b; 4, paratype, U.S.N.M. 108065a . 

. AH from U.S·.G.S. Mes. loc. 2921, Chinitna formation. · 

3, 7 .. Pa~~type, U~S.N.M. 108066 from U.S.G.S. Mes. loc. 3028, Chinitna formation. Body chamber incomplete. 

5, 6, 8, 9. Holqtype, U.S.N.M.-108064 from U.S.G.S. Mes. loc. 19781, Shelikof formation.· Body chamber incomple~e. · Note co_nstriction on inner whorls shown in fig. 5. · 

·-11 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 37 

CADOCERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 38 

,.---

CADOCERAS 
• 

... 

PLATE 38 

[All figures natural size] 

FIGURES 1, 5, 6. Cadocems bathomphalum Imlay, n. sp. (p. 84). Holotype, U.S.N.M. 108068 from U.S.G.S. Mes. lac. 12408, 

Shelikof formation. Body chamber not preserved. 

2-4, 7-12. Cadoceras tenuicostatum Imlay, n. sp. (p. 85). 

2. Paratype, U.S.N.M. 108072 from U.S.G.S. Mes. lac. 20763,. Chinitna formation. 

3, 4. Paratype, U.S.N.M. 108073 from U.S.G.S. Mes. lac. 21356, Shelikof formation. 

7. Suture line of paratype, U.S.N.M. 108070 at a diameter of 56 mm., U.S.G.S. Mes. lac. 3029, Chinitna· formation. · .·· .. 

8, 9, 12. Holotype, U.S.N.M. 108069 from tJ.S.G.S. Mes. lac. 3029, Chinitna formation .. Fig. 12 shows complete body chamber.· . 

10, 11. Paratype, U.S.N.M. 108071 from U.S.G.S. Mes. lac. 3113, Shelikof formation . 

I, 
PLATE 39 

[All figures natural size] 

FIGURES 1-12. Cadoceras doroschini (Eichwald) (p. 85). 

I I 

1, 3, 7. Plesiotype, U.S.N.M. 108074b from U.S.G.S. Mes. loc. 3028, Chinitna formation. 

2, 4, 11. Plesiotype, U.S:N.M .. 108076 from U.S.G.S. Mes. loc. 3113, Shelikof formation. 

5. Plesio.type, U.S.N.M. 108074c from U.S.G.S. Mes. loc. 3028, Chinitna formation. 

6. Plesiotype,. U.S.N.M. 108075a from U.S.G.S. Mes. loc. 3029, Chinitna formation. 

8, 9. Plesiotype, U.S.N.M. 10S075b from U.S.G.S. Mes. loc. 3029, Chinitna formation. · 

10, .12; Plesiotype, U.S.N.M; 108074a from U.S.G.S. Mes. loc. 3028, Chinitna formation. 

-· 
GEOIJOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 39 

CADOCERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 40 

CADOCERAS 
FIGURES 1-12. 

PLATE ~40 

[All figures natural size] 

Cadoceras wosnessenskii (Grewingk) (p. 86). 

1, ·4. ·Septate plesiotype, iJ.S.N.l\1.108080 from U.S.G.S. Mes. loe. 21360, Shelikof formation .. 

2, 3. Plesiotyp.e, U.S.N.M. 108078b; 5, 6, plesiotype, U.S.N.M. 108078a. Both from .. U.S.Q.S. Mes. Joe. 2921, 

Chinitna formation. 

7. Plesiotype, U.S.N.M. 108079 from U.S.G.S. Mes. loe. 3018, Chinitna formation. 

8. Plesiotype, U.S.N.l\1. 108077e; 10, 11, plesiotype, U.S.N.M. 10S077b; 9, 12, Plesiotype, U.S.N.M. 108077a 

All from U.S.G.S. Mes. Joe. 3029, Chinitna formation. 
BL~TE-~1 

[All figures natural size] 

FIGURES 1-7. Cadoceras kialagvikense Imlay, n. sp. (p. 87). • ·:,: ,., .: ... _ ._. , 

· 1, 2, 4. Lateral and sectional views of holotype, U.S.N.M. 108081 from. U.S.G.S. Mes:.'loc,-'l2408,:Shelikof forlli,~tiori. . 

. 3, 7~ Suture line and septate penultimate whorl of paratype, U.S.N.M. 108083 from U.S.G.S. Mes. loc. 21345, 

· Chinitna formation. The body chamber is partly crushed and has been removed. 

5, 6. Paratype, U.S.N.M. 108082 from U.S.G.S. Mes. loc: 19744, Shelikof formation. Shows complete body 

chamber. 

'-. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 41 

CADOCERAS 
GEOLOGICAL SURVEY 

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5 

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/ 

PROFESSIONAL PAPER 249 PLA'rE 42 

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2 

CADOCERAS 
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PLATE 42 

[All figures natural size] . 

FIGURES 1, 2, 5-8, 10. Cadoceras (Paracadoceras) multiforme Imlay, n. sp. (p. 88). 

1, 2. Inner whorls of paratype,. U.S.N.M. 108087 from· U.S.G.S. Mes. loc. 21343, Chinitna formation. 

Part of one whorl removed from fig. 1. 

5, 7_. ·Inner whorls of paratype, U.S.N.M: 108086b from U.S.G.S. Mes. loc. 3019, Chinitna formation. 

6, 10. Paratype, U.S.N.M. 108086a from U.S.G.S. Mes. loc. 3019, Chinitna formation. Suture drawn 

. from posterior end of body chamber which has been removed to show the.inner whorls. 

8. Holotype, U.S.N.M. 108085 from U.S.G.S. Mes. loc. 3019, Chinitna formation. Shows nearly complete 

body chamber. 

3, 4, 9. Cadoceras (Paracadoceras) moffiti Imlay, n .. sp. (p. 87). 

Lateral and sectional views of holotype, U.S.N.M. 108084 from U.S.G.S. Mes. loc. 10986, Chinitri.a formation. In fig. 4 the incomplete body chamber is removed in order to show the strong ribbing of the penultim.ate :whorl. · ' · 
;FIGURES 1, 4. 

2, 3, 7, 8. 

PLATE 43 

[All figures natural size] 

Cadoceras (Paracadoceras) aff. C. tonniense Imlay, n. sp. (p. 89). 

Specimen, U.S.N.M. 108090 from U.S.G.S. Mes. loc. 3019, Chinitua formation. 

Cadoceras (Stenocadoceras) bowserense Imlay, u. sp. (p. 91). · 

2, ·8. Paratype, U.S.N.M. 108102 from U.S.G.S. Mes. loc. 11041, Chinitna formation. 

3, 7. Holotype, U.S.N.M. 108101 from U.S.G.S. Mes. loc. 11041, Chinitna formation. 

5, 6 .. Cadoceras (Paracadoceras) 'chisikense Imlay, n. sp. (p. 89) . 

9-11, 13. 

. Holotype, U.S.N.M. 108091 from U.S.G.S. Mes. loc. 10250, Chiuitna formation. Fig. 5 shows the ribbing of the 

penultimate whorl. 

Cadoceras (Paracadoceras) tonniense Imlay, n. sp. (p. 88). 

9-11. Hoiotype, U.S.N.M. 108088 from U.S.G.S. Mes. loc. 21340, Chiuitua formation. Only about one-fourth of a 

whorl is body chamber. 

13. Paratype, U.S.N.M. 108089 from U.S.G.S. Mes. loc. 21326, Chinitna formation. 

12 .. Cadoceras {Paracadoceras) harveyi (Crickmay) (p. 44). 

Lateral view of plaster cast of holotype from Harrison Lake area, British Columbia. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 43 

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CADOCERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 44 

1 

CADOCERAS 
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PLATE 44 

[All figures natural size] 

FIGURES 1-16. Cadoceras (Stenocadoceras) multicostat'um Imlay, n. sp. (p. 90). 

1, 2. Holotype, U.S.N.M. 108092 from U.S.G.S. Mes. loc. 2991, Chinitna formation. 

3, 9. Paratype, U.S.N.M. 108095c from U.S.G.S. Mes. loc. 12386, Shelikof formation. 

4, 5. Paratype, U.S.N.M. 108094b from U.S.G.s·. Mes.loc; 21290, Chinitna formation. 

6. Paratype, U.S.N.M. 108095a from U.S.G.S. Mes. loc. 12386, Shelikof formation. 

7, 8, 12. Paratype, U.S.N.M. 108095b from U.S.G.S. Mes. loc. 12386, Shelikof formation. 

10, 14. Paratype, U.S.N.M. 108094c from U.S.G.S. Mes. loc. 21290, Chinitna formation. 

11. Paratype, U.S.N.M. 108094d from U.S.G.S. Mes. loc. 21290, Chinitna formation. 

13, 15. Paratype, U.S.N.M. 108094a from U.S.G.S. Mes. loc. 21290, Chinitna formation. Shows complete body 

chamber. 

16. Paratype, U.S.N.M. 108093 from U.S.G.S. Mes. loc. 10813, Shelikof formation. 
PLATE 45 

[All figures natural size] 

FIGURES 1-3. Cadoceras (Stenocadoceras) pomeroyense Imlay, n. sp. (p. 92). · 

Holotype, U.S.N.M. 108110 from U.S.G.S. Mes. loc. 22415, Chinitna formation. Part of body chamber shown in 

fig. 1. Note ventral view in pl. 46, fig. 2. 

4-7. Cadoceras (Stenocadoceras) striatum Imlay, n. sp. (p. 90). 

4. Septate paratype, U.S.N.M. 108097b; 5, 7, septate holotype, U.S.N.M. 108096; 6, paratype, U.S.N.M. 108097a 

showing about one-half whorl of body chamber. All specimens from U.S.G.S. Mes. loc. 21291, Chinitna formation. 
GEOI,OGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 45 

CADOCERAS 
GEOLOGICAL SURVEY l'ROFESSJONAL PAPER 249 PLATE 46 

CADOCERAS 
1;: 

PLATE 46 

[All figures natural size] 

FIGURES 1, 4-9. Cadoceras (Stenocadoccras) iniskinense Imlay, n. sp: (p. 91). 

1, 8. Lateral views of paratype, U.S.N.l\1. 108100 from U.S.G.S. Mes. loc. 3117, Shelikof formation.· 

4, 5. Paratype, U.S.N.l\1. 1o"8099a; 6, paratype, U.S.N.M. l08099b. Both from U.S.G.S. Mes.loc. 3030, Chiniina 

formation. 

)· 7, 9. Lateral views of holotype, U.S.N.M. 108098 from U.S.G.S. Mes. loc. 3030, Chinitna formation. 

2. Cadoceras (Stenocadoceras) p.omeroyense Imlay, n. sp. (p. 92). 

Ventral view of holotype, U.S.N.M. 108110 from U.S.G.S. Mes. loc. 22415, Chinitna forrriation. 

3 . . Cadoceras (Stenocadoceras) stenoloboide Pompeckj (p; 92). 

Plesiotype, U.S.N.l\1. 108108 from U.S.G.S. Mes. loc. 21357, Shelikof formation. Note sutural pattern. 
PL~t\.TE 47 

[All figures natural size] 

FIGURES 1'-15. Cadoceras (Stenocadoceras) stenoloboide Pompeckj (p. 92). 

1, 2, 6. Plesiotype, U.S.N.M. 108106 from U.S.G.S. Mes. loc. 12387, Shelikof formation. 

3-5. Plesiotype, U.S.N.M. 108105 from U.S.G.S. Mes. loc. 11052a, Chinitna formation. 

7, 8. Plesiotype, U.S.N.M. 108103b from U.S.G.S. Mes. loc. l2386, Shelikof formation. · 

9. Suture line of plesiotype, U.S.N.M. 108108 from U.S.G.S. Mes. loc. 21357, Shelikof formation. Same specimen 

shown on pl. 46, fig. 3. ·-< 

10, 14. Plesiotype, U.S.N.M. 10~107 from U.S.G.S. Mes. loc. 12408, Shelikof formation. 

11. Plesiotype, U.S.N.M. 108109 from U.S.G.S. Mes. loc. 21777, Chinitna formation. Note abrupt weakening of 

tlbbing at beginning of body chamber. 

12 .. Plesiotype, U.S.N.M. 108104 from U.S.G.S. Mes. loc. 3030,· Chinitna formation. 

13, 15. Plesiotype, U.S.N.M. 108103a from U.S.G.S. Mes. loc. 12386, Shelikof formation. Note apertural constriction on internal mold . 

• 
GEOLOGICAL f':PRVEY PROFESSIONAl~ PAPER 249 PLATE 47 

CADOCERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 48 

5 6 

7 

9 

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/ I 

15 

16 

PSEUDOCADOCERAS AND KEPPLERITES 
\ 

I 

PLATE 48 

[All figures natural size] 

FIGURES 1-6, 15. Pseudocadoceras petelini (Pompeckj) (p. 93). 

1, 2. Plesiotype, U.S.N.M. 108112 from U.S.G.S. Mes. loc. 12386, Shelikof formation. 

3, 4. Plesiotype, U.S.N.M. 108111 from U.S.G.S. Mes. loc. 10822, Shelikof formation. 

5, 6, 15. 'Plesiotype, U.S.N.M. 108113 from U.S.G.S. Mes. loc. 12387, Shelikof formation. Suture line drawn 

at whorl height of 9 mm. 

7-10. Pseudocadocer:as chinitnense Imlay, n. sp. (p. 94). 

7, 8. Paratype, U.S.N.M. 108121 from U.S.G.S. Mes. loc. 10978, Chinitna formation. 

9, 10. Holotype, U.S.N.M. 108120 from U.S.G.S. Mes. loc.· 21777, Chinitna formation. 

11, 16. Kepplerites (Seymourites) alticostatus Imlay, n. sp. (p. 95). 

Holotype, U.S.N.M. 108124 from U.S.G.S. Mes. loc. 2992, Chinitna formation. 

12, 13. Kepplerites sp. juv. aff. K. ingrahami (McLearn) (p. 97). 

Specimen, U.S.N.M. 108136 from U.S.G.S. Mes. loc. 22431, Chinitna formation. 

14, 17. Kepplerites (Seymourites) tychonis Ravn (p. 96). 

Plesiotype, U.S.N.M. 108125 from U.S.G.S. Mes. loc. 21287, Chinitna formation. Beginning of .body chamber 

shown in last inch of anterior end of specimen. Note impression of body ·chamber on penultimate whorl. 
PLATE 49 

[All figures natural size] 

FIGURES 1-12. Pseudocadoceras grewingki (Pompeckj) (p. 93). 

1, 2, 8. Plesiotype, U.S,N.M. 108115b from U.S.G.S. Mes. loc. 12a86, Shelikof formation. 

3, 4, 9. Plesiotype, U.S.N.M. 108116 from U.S.G.S. Mes. loc. 20757, Chinitna formation. 

5-7. Plesiotype, U.S.N.M. 108117 from U.S.G.S. Mes. loc. 21348, Chinitna formation. 

10. Plesiotype, U.S.N.M. 108115a from U.S.G.S. Mes. loc. 12386, Shelikof formation. 

11, 12. Plesiotype, U.S.N.M. 108114 from U.S.G.S. Mes. loc. 3030, Chinitna formation .. 

13-16. Cosmoce~as (Gulielmiceras) alaskanum Imlay, n. sp. (p. 100). 

13, 14. Paratype, U.S.N.M. 108142b; 16, paratype, U.S.N.M. 108142a. Both from U.S.G.S. Mes. loc. 20755, 

Chinitna formation. Fig. 16 is from a rubber cast. 

15. Holotype, U.S.N.M. 108141 from U.S.G.S. Mes. loc. 2920, Chinitna formation. Photographed from a rubber 

cast. 

17, 18. Pseudocadoceras schmidti (Pompeckj) (p. 95). 

Plesiotype, U.S.N.M. 108123 from U.S.'G.S. Mes. loc. 10824, Shelikof formation. 

19, 20, 22-24. Pseudocadoceras crassicostatum Imlay, n. sp. (p. 94). 

19, 20. Paratype, U.S.N.M. 108119 from ·u.S.G.S. Mes. loc. 11060, Chinitna formation. 

22-24. Holotype, U.S.N.M. 108118 from U.S.G.S. Mes. loc. 12387, Shelikof formation. The suture line drawn 

lies.directly behind the body chamber at a diameter of 34 mm. 

21. Kepplerites (Seymourites) plemts (McLearn) (p. 99). 

Plesiotype, U.S.N.M. 108135 from U.S.G.S. Mes. loc. 19793, Shelikof.formation. 

·1 
GE OL OGI CAL SUR VEY PROFESSIONAL PAPER 249 PLATl<: 49 

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18 

19 

PSEUDOCADOCERAS, KEPPLERJTES, AND COSMOCERAS 
GEOLOGICAl, SURVEY PROFESSIONAL PAPER 249 PLATE 50 

KEPPLERITES 
1 .. 

PLATE 50 

[All figures natural size] 

FIGURES 1-4. Kepplerites (Seymourites) ingrahami (McLearn) (p. 97). 

~~, . 

· 1, 3. Plesiotype, U.S.N.M. 108127 from U.S.G.S. Mes. loc. 12074, Chinitria f~rmation. Note ventral flattening. 

2. Plesiotype, U.S.N.M. 108129 from U.S.G.S. Mes. loc. 20763, Chinitna formation. 

4. Plesiotype, U.S.N.M. 108128 from U.S.G.S. Mes. loc. 19793, Shelikof formation. 
P.L~TE 51 

[All figures natural size] 

FIGURES 1, 4. · Kepplerites (Seymourites) multus (McLearn) (p. 96) • 

. Plesiotype, U.S.N.M. 108126 from U.S.G.S. Mes. loc. 20763, Chinitna formation. 

2. Kepplerites (Seymourites) ingrahami (McLearn) (p. 97). 

Suture line of plesiotype, U.S.N.M. 108127 shown in pl. 50, fig. 1. 

-3, 5-8. Kepplerites (Seymourites) mcevoyi (McLearn) (p. 97). 

3, 6,.8. Plesiotype, U.S.N.M. 108132 from U.S.G.S. Mes. loc. 10922, Chinitna formation. Note weak ~pertural 

constriction. 

4, 5. Plesiotype, U.S.N.M. 108131 from U.S.G.S. Mes. loc.' 20763, Chinitna formation. 

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GEOLOGJCA L SURVEY PROFESSIONAL PAPER 249 PLATE 51 

KEPPLERITES 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 52 

KEPPLERJTES 
FIOURT~B 1, 2. 

. 3-6. 

~LATE 52 

. [Allfigures natu:l'al size] 

Kepplerites (Seymourites) gitinsi (McLearn) (p. 98). 

_. 

Incomplete penultimate whorl and body chamber of plesiotype, U.S.N.M. 108130 from U.S.G.S. Mes. loc. 2921, 

Chinitna formation. 

Kepplerites (Seymourites) abruptus (McLearn) (p. 98) . 

3-5. Septate plesiotype, U.S.N.M: 108133 from U.S.G.S. Mes.loc. 21330, Chinitna formation. Suture line drawn 

at whorl height of 28 mm. · 

6. Plesiotype1 U.S.N.M. 108134 from U.S.G.S. Mes. loc. 22433, Chinitna formation. Note apertural constriction. 
PLATE 53 

[All figures natural size unless otherwise indicated] 

FIGURE 1. Procerites-sp. {p. 102). 

Septate fragment, U.S.N.M .. 108145 from U.S.G.S. Mes. loc. 22448, Chinitna formation. 

2, 3. Procerites sp. (p. 102). 

Posterior part of body chamber and sectional view of specimen U.S.N.M. 108144 from U.S.G.S. Mes.loc. 22446, Chinitna 

formation. A fragment of the penultimate whorl has been omitted from photograph. 

4, 5. Cosmoceras (Cosmoceras) cf. C. spinosum (J. de C. Sowerby) {p. 100). 

Ventral and lateral views of specimen, U.S.N.M. 108140 from U.S.G.S. Mes. loc. 10991. Float probably derived from 

Chinit.na. formation. 

6., 7, 10. Gowericeras sp. (p. 100). 

Specimen, U.S.N.M. 108139 from U.S.G.S. Mes. loc. 3015, Chini.tna formation. Suture line drawn· at diameter of 

48mm. 

8, 11. Gowericeras spinosum Imlay, n." sp. {p. 99). 

Holotype, U.S.N.M. 108138 from U.S.G.S. Mes. loc. 22432, Chinitna formation. Suture line drawn is about one inch 

posterior to body whorl. 

9. Gowericeras snugharborense Imlay, n. sp. {p. 99). 

I_Iolotype, U.S.N.M. 108137 from U.S.G.S. Mes. loc. 3015, Chinitna. formation. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 53 

PROCERJTES, COSMOCERAS, AND GOWERICERAS 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 249 PLATE 54 

2 

PROCERITES? 
PLATE 54 

[Figures slightly reduced or enlarged as 'indicated) 

FIGURES 1; 2. Procerites? irregularis Imlay, n. sp. (p. 102). 

Holotype, U.S.N.M. 108146 from U.S.G.S. Mes. loc. '21273, Chinitna formation. Suture line·froin about 1% fn. 

posterior to body chamber. 
PLATE 55 

(Figures natural size unless otherwise indicated] 

FIGURES 1, 2, 5-8. Reineckeia (Kellawaysites) shelikofana Imlay, n. sp. (p. 101). 

Holotype, U~S.N.M. 108143 from U.S~G.S: Mes. loc. 21355, Shelikof formation. Figs. 1 and 7 are enlargements of internal whorls. Suture line shown in fig. 6 drawn at diameter of 17 mm. Suture line shown in fig. 5 

drawn at diameter of 40 mm. Sectional view of fig. 2 drawn from point ·A to A'. Note specimen is entirely 

septate. 

3, 4. Grossouvria sp~ (p. 102). 

Lateral views of crushed specimen, U.S.N.M. 108147 from U.S.G.S. Mes. loc. 22431, Chinitna formation. 
GEOLOGICAL SURVEY 

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REINECKEIA AND GROSSOUVRIA 

PROFESSIONAL PAPER 249 PLATE 55 

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