Ammonites from the

'a Zones in 

Northwestern California 

and Southwestern Oregon

GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B
Ammonites from the

'a Zones in 

Northwestern California 

and Southwestern Oregon

By RALPH W. IMLAY and DAVID L. JONES

JURASSIC (TITHONIAN) AND CRETACEOUS BUCHIA ZONES IN 

NORTHWESTERN CALIFORNIA AND SOUTHWESTERN OREGON

GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B

Some Late Jurassic and Early Cretaceous 

ammonites date the Buchia zones and furnish 

correlations with the Boreal and Tethyan Realms

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

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price $1.25 (paper cover)
CONTENTS

Page 

Abstract.__________________________________________ Bl

Introduction. _ _____________________________________ 2

Biologic analysis.___________________________________ 2

Stratigraphic relationships of ammonites to Buchias__ 5 

Ages and correlations of the ammonite faunules________ 11

Jurassic ammonites-____________________________ 11

Tithonian ammonites from the Buchia piochii

zone____________________________________ 11

Tithonian ammonites from the Buchia aff. B.

okensis zone______________________________ 12

Cretaceous ammonites-_________________________ 12

Berriasian ammonites from the Buchia uncitoides

zone____________________________________ 12

Page

Ages and correlations of the ammonite faunules Continued 

Cretaceous ammonites Continued

Valanginian ammonites from the Buchia pacifica

Valanginian ammonites from the Buchia keyserlingi zone. _______________________________

Valanginian ammonites from the Buchia crassicollis solida zone. ___________-___-______---

Comparisons of ammonites with other ammonite faunules-- 

Geographic distribution______-__________--_____----_

Systematic descriptions________ _____________________

References ___________-______--------------__------

Index _____-______-___-_-------_-----_-_-----------

B14

16

17

1 7

19

2? 

53

£7

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Phylloceras, Phyllocerasf, Bochianitesf, and Bochianites.

2. Lytoceras and Phylloceras.

3. Kossmatia, Proniceras, Spiticeras, and S. (Kilianicerast).

4. Spiticeras.

5. Groebericerast.

6. Groebericeras? and Protacanthodiscus.

7. Tollia and Polyptychites.

8. Tollia, Polyptychites, and Olcostephanus.

9. Olcostephanus and Pclyptychites.

10. Blanfordiceras and Substeueroceras.

11. Parodontoceras.

12. Aulacosphinctesf, Sarasinella, and Parodontoceras.

13. Thurmanniccras and Paskentites.

14. Neocomites, Neocosmocerasl, Neocosmoceras, and Kilianella.

15. Groebericeras"!.

FIGURE 1. Stratigraphic relationships of ammonites with species of Buchia____________________---__--------------

2. Correlation of latest Jurassic (Tithonian) and earliest Cretaceous (Berriasian and Valanginian) faunas in 

California and Oregon.____________________________________________------------___-_----------_

3. Index map of ammonite localities in the Buchia beds of southwestern Oregon_ __________________________

4. Index map of ammonite localities in the Buchia beds of northwestern California-____________-_____---_-__

5-8. Detailed index map of ammonite localities 

5. In west-central part of the Colyear Springs quadrangle, California____ ----------------------------

6. In the Paskenta area, California -------------------------------------------------------------

7. Near Newville, Calif_ ---------------------------------------------------------------------

8. In the Elk Creek area, California___ --------------------------------------------------------

in

Page 

B6

8

19

19

19
IV CONTENTS

TABLES

Page

TABLE 1. Some ammonite genera in Tithonian, Berriasian, and Valanginian beds in northern California and so^thwestern Oregon showing biological relationships of the genera, relative numbers available for study, and 

stages represented-___________________________________________________________________________ B3

2. Geographic distribution of ammonites in the uppermost Jurassic (Tithonian) and Lower Cretaceous Buchia

beds of northwestern California and southwestern Oregon_____________-_____________-__________ .___ 20
JURASSIC (TITHONIAN) AND CRETACEOUS BUCHIA ZONES IN NORTHWESTERN CALIFORNIA

AND SOUTHWESTERN OREGON

AMMONITES FROM THE BUCHIA ZONES IN NORTHWESTERN CALIFORNIA

AND SOUTHWESTERN OREGON

By EALPH W. IMLAT and DAVID L. JONES

ABSTRACT

Ammonites from the UMcTwa-bearing strata of northwestern 

California and southwestern Oregon represent the Tithonian 

stage at the top of the Jurassic and the Berriasian and Valanginian stages at the base of the Cretaceous. These ammonites 

are associated with various species of the pelecypod Buchia, 

which from oldest to youngest include B. piochii (Gabb) and 

B. aff. B. oJcensis (Pavlow) of Tithonian age, B. uncitoides 

(Pavlow) of Berriasian age, B. pad flea Jeletzky of early to 

middle Valanginian age, B. Jieyserlingi (Lahusen) of middle to 

early late Valanginian age, and Buchia crassicollis solida (Lahusen) of late Valangdnian age. The ages cited are based primarily on the ammonites present but partly on the similarities 

of the Buchia succession ito that in British 'Columbia and in the 

Arctic region. As the succession of the species of Buchia is 

similar to that in western Canada, the strata characterized by 

the species are herein considered assemblage zones in conformity with the usage in Canada.

Ammonites of Tithonian age have been found mostly along 

the west side of the Sacramento Valley, Calif. They include 

Kossmatia from the lower to middle parts of the B. piochii 

zone, Parodontoceras and Spiticeras from the upper part of the 

B. piochii zone, and Substeueroceras, Parodontoceras, Proniceras, Spiticeras, and Blanfordiccras from the B. aff. B. okensis 

zone. Of these ammonites, Kossmatia, by comparisons with the 

sequence in Mexico and Argentina, is evidence for a middle 

Tithonian age, but it occurs also in New Zealand in beds of 

late Kimmeridgian age and probably also in beds of middle 

Kimmeridgian age. Parodontoceras is good evidence of a middle to late Tithonian age on the basis of its range in Mexico 

and Argentina. The various ammonites listed from the B. aff. 

B. okensis zone are excellent evidence for a late Tithonian age 

equivalent to the highest Jurassic beds in Mexico and Argentina. An age not older than middle Tithonian for the lowest 

part of the Jurassic sequence along the west side of the Sacramento Valley is indicated by the absence of species of Buchia, 

such as B. mosquensis (Von Buch) and B. rugosa (Fischer), 

which occur in beds of middle Kimmeridgian to middle Tithonian age from the State of Washington northward into Alaska 

and as high as the Dorsoplanites panderi zone (lower middle 

Volgian) on the Russian platform.

Ammonites of Berriasian age from California and Oregon 

belong mostly to the subgenera Spiticeras (Negreliceras) and 

8. (Spiticeras) but include also the genus Neocosmoceras. The

subgenus Negreliceras in California ranges through the low^r 

two-thirds of the Buchia uncitoides zone and dates that pprt 

as not younger than Berriasian.

Ammonites of middle and late Valanginian age are well 

represented in California and Oregon. That beds of early Valpnginian age are present has not been proved faunally. In Cr.lifornia, however, some specimens of Thurmanniceras in the 

lower part of the Buchia pacifica zone could be dated as early 

Valanginian on the basis of stratigraphic position. The middle 

part of the B. paciflca zone has furnished species of Thurmanniceras and Kilianella that, by comparisons elsewhere, suggest a middle Valanginian age. The upper part of the B. pacifva 

zone contains a species of Tollia that is similar to a species 

from the middle Valanginian of East Greenland. The preserve 

of Tollia itself is good evidence of an age not younger than 

middle Valanginian.

The overlying zone of Buchia keyserlingi in the Paskenta 

and Elk Creek quadrangles, California, contains such typi?al 

Valanginian ammonites as Sarasinella, Polyptychites, and Thurmanniceras. The last two ammonites in the upper part of the 

zone are associated with Crioceratites and Neocraspedites, 

which in Eurasia are not known in beds older than late Valanginian. The upper part of the zone, therefore, is dated as late 

Valanginian, but the lower part could be middle Valanginian,

The highest Buchia zone, characterized by B. crassicollis 

solida (Lahusen), has furnished diagnostic ammonites only in 

Oregon. These consist of Homolsomites and Olcostephanus that 

by comparisons with species in Eurasia could be either latest 

Valanginian or earliest Hauterivian. A Valanginian age is 

favored by the association of these ammonites with Buchia tfnd 

by their stratigraphic position directly below beds containing 

early Hauterivian ammonites.

The affinities of most of the ammonites of latest Jurassic f nd 

earliest Cretaceous ages from California and Oregon are southern or Mediterranean. Only Tollia and Homolsomites are distinctly Boreal. In addition, the genera Polyptychites and Neocraspedites range from the Mediterranean to the Arctic but are 

most common in central and northern Eurasia and are probably 

not of Mediterranean origin.

Ammonites are rather uncommon in the Uttcftia-bearing sequence of northwestern California and southwestern Oregon 

except at the very top of the beds characterized by Buchia 

paciflca Jeletzky. Those beds also have furnished a fair variety 

of pelecypods and gastropods. Elsewhere throughout the sequence the only common fossil is Buchia itself.

Bl
B2 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

The ammonites on which this study is based total 454 specimens, of which 57 are assigned a Tithonian age, 103 a Berriasian age, and 294 a Valanginian age. One new genus, Paslientites Imlay and Jones, of middle Valanginian age is described 

herein. New species include Phyllocerasl contrarium Imlay and 

Jones, Proniccras maiipincnsc Imlay and Jones, Spiticeras 

(Negreliceras) stonycnsc Imlay and Jones, Grocbericcrast 

baileyi Imlay and Jones, and Neocosmoccras cuchrense Imlay 

and Jones.

INTRODUCTION

The primary aim of this study is to determine the 

ages of the Buchia-be&r'mg strata in northwestern California and southwestern Oregon by means of the ammonites present. It has been necessary, therefore, to 

study those ammonites thoroughly, to compare them 

with similar ammonites elsewhere in the world, and to 

determine their stratigraphic positions relative to the 

species of Buchia with which they are associated. This 

has involved a simultaneous study of the characteristics and ranges of the species of Buchia in California 

and Oregon and comparisons of those species with the 

various species of Buchia from western British Columbia described by Jeletzky (1965). That has led in turn 

to recognition of a number of mappable Buchia zones 

of which some are identical with zones in British 

Columbia.

This study includes all ammonites of latest Jurassic 

(Tithonian) and earliest Cretaceous (Berriasian) ages 

from northwestern California and southwestern Oregon that are available in the California Academy of 

Sciences, in the Museum of Paleontology at the University of California in Berkeley, and in the laboratories 

of the U. S. Geological Survey. It includes, also, some 

Early Cretaceous (Valanginian) ammonites for which 

new information is available. It does not contain descriptions of many other Valanginian ammonite species that are described by Imlay (1960), although most 

of those species are mentioned and listed herein. It does 

contain descriptions and evaluations of most of the 

Tithonian-Valanginian ammonites described by Anderson (1938, 1945).

The authors are grateful for assistance and loan of 

specimens to Leo G. Hertlein and G. Dallas Hanna of 

the California Academy of Sciences at San Francisco, 

to Wyatt Durham and Joseph H. Peck, Jr., of the 

University of California at Berkeley, and to Horace 

G. Richards of the Philadelphia Academy of Natural 

Sciences.

BIOLOGIC ANALYSIS

The ammonites of latest Jurassic (Tithonian) and 

earliest Cretaceous (Berriasian and Valanginian) ages 

that are described herein total 454 specimens. Their

distribution by families, subfamilies, genera, and subgenera is shown in table 1. This table shows that the 

Olcostephanidae include 70 percent and the Perriasellidae 17 percent of the specimens examined. Among 

the genera studied, Spiticeras includes abou4:. 24 percent, TolTia 44 percent, Thurmanniceras 6 percent, and 

Neocomites 7 percent of the 454 specimens. Among 

these specimens the Tithonian is definitely represented 

by 55 and questionably by two, the Berriasian by 101 

and questionably by two, and the Valanginian by 294. 

These figures include all ammonites of Tithonian and 

Berriasian ages but only part of the ammonites of 

Valanginian age that have been found in northern 

California and southwestern Oregon. Only those Valanginian ammonites are described herein that have not 

been described previously (Imlay, 1960), or that have 

some bearing on correlations and age determinations, 

or that are better preserved than any found previously. 

On the generic and subgeneric level moft of the 

ammonites listed agree in most features with various 

taxa denned in the "Treatise on Invertebrate Paleontology'' (Arkell and others, 1957). Some ammonites 

that are assigned questionably to Kilianiceras, Aulacospliinctes, and Neocosmoceras are represented by immature fragmentary specimens that do not show 

enough diagnostic features to place them def nitely in 

their proper genus or subgenus. Other ammonites that 

are assigned questionably to Phylloceras, Bochianites, 

and Groebericeras bear features that are not known in 

those genera but that may not be of more than specific 

value. Thus PJiyUoceras^ contrarium Imlay and Jones, 

n. sp. has rursiradiate ribs on the upper parts of the 

flanks and venter, whereas in typical species of Phylloceras the ribbing either crosses the venter transversely or arches gently forward. The generic assignment of Bocliianites\ glennensis Anderson is questioned because its venter bears transverse rib^1 instead 

of chevron-shaped ribs. The generic assignment of 

Gi'oebericeras ? bayleyi Imlay and Jones, n. sp. is questioned because of the presence of umbilical tubercles.

The family Perisphinctidae is represented only by 

three small immature specimens of Kossmatia. These 

show such characteristic generic features rs fairly 

regular rib branching on the middle third of tl °- flanks, 

chevronlike arrangement of ribs on the venter, presence 

of constrictions, and absence of tubercles.

The family Olcostephanidae is represented mostly by 

the genera Tollial and Spiticeras. It also includes a 

few specimens belonging to Proniceras, Groebericeras^ , 

Olcostephaiius, and Polyptychites.

In the subfamily Spiticeratinae the identification of 

Proniceras is based on the presence of perisphinctoid
AMMONITES FROM THE BUCHIA ZONES B3

TABLE 1. Some ammonite genera in Tithonian, Berriasian, and Valanginian beds in northern California and southwestern Oregon 

showing biological relationships of the genera, relative numbers available for study, and stages represented

Family

Phylloceratidae__- ___ _

Lytoceratidae

Bochianitidae

Perisphinctidae. __ __ _

Olcostephanidae _

Berriasellidae_ _ _

Subfamily

Phylloceratinae

_ Lytoceratinae.

Bochianitinae

Ataxioceratinae

Spiticeratinae. _ _

Tolliinae _ _ _ _

Olcostephaninae. _ _

Polyp tychitinae

_ _ _ Berriasellinae

Himalavitinae___ __

Neocomitinae_

Genus and subgenus

Phylloceras _________

Phyllocerast . ______ __ _ _

Lytoceras _ _____ _ ___.

Bochianites*? _ __ ______

Bochianites- _______

Kossmatia. __ _ ____ ___

Proniceras,. _ _ ____ _ ___.

Spiticeras... . ____ _ ____.

S. (Kilianicerasl) _ ___ __ _ _.

S. (Negreliceras).. _ __ __ _ _

Groebericerasl __ _____ ___

______ Tollia--...---...----.-. ______

_ _ Olcostephanus ----- __ _ ___ _.

_ Polyptychites _

_ _ Blanfordiceras.- _ _ _____

Substeueroceras . _ ___

Protacanthodiscus.. . _____

Parodontoceras- _ ____ ___

Aulacosphinctes?--- __ _ _

__ _ Paskentites n. gen _ __ _____

Thurmanniceras _ _ ___ ___

Neocomites.. ___ ___ _ _____ _

Kilianella .. _____ _____ _.

Sarasinella...... _._ _______

Neocosmoceras.. .. ...

Neocosmocerasl _ ___ __ ___

Number of

specimens

______ 8

______ 5

.-____ 12

______ 1

______ 15

. _ - _ O

______ 6

______ 10

______ 3

_____ 90

______ 1

______ 200

. __ _ 1

______ 2

______ 3

_____ 6

_____ 1

,.____ 9

4

______ 8

______ 27

_____ 32

..____ 3

_____ 2

_____ 1

_____ 1

Stages

T, V

T

T, V

T?

V

T

T

T, B

B,V

B

T

V

V

V

B

T

T?

T

T

V

V

V

V

V

B?

B?

ribbing on the flanks, a chevronlike rib pattern on the 

venter, and pronounced forwardly inclined constrictions and on the absence of tubercles and swellings. 

The subgenus Spiticeras differs from Proniceras by the 

presence of acute umbilical tubercles, by rib branching 

from these tubercles as well as higher on the flanks, 

and by the ribs on the venter arching forward only 

gently. In addition, one specimen bears lateral tubercles 

on its inner whorls, and other specimens bear radial 

swellings that are prolonged ventrally from the umbilical tubercles. The subgenus Negreliceras differs from 

the subgenus Spiticeras by being compressed from early 

growth stages, by having umbilical tubercles only, by 

the presence of many weak secondary ribs, and by a 

tendency for the body chamber to become smooth, particularly on the lower parts of the flanks. The subgenus 

Kilianicems, doubtfully represented, differs from 

Spiticeras by having much coarser ribbing and two 

rows of tubercles that persist onto the larger whorls. 

The genus >Groebericeras resembles the subgenus 

Negreliceras in having a compressed form and in developing a nearly smooth body whorl but differs by 

being smoother from an earlier growth stage and by 

lacking tubercles except possibly on the smallest 

whorls.

The subfamilies Olcostephaninae and Polyptychitinae are represented respectively by fragmentary specimens of Olcostephanus and Polyptychites that are

typical of those genera and are similar to specimens1 

previously described (Imlay, 1960, p. 203, 204).

The subfamily Tolliinae is represented in the collections studied by the genus Tollia. This genus has s. 

compressed and fairly involute shell. The venter may 

be narrowly rounded or acute on the inner whorls but 

is moderately rounded on the outer whorls. The ribs 

on the inner whorls are sharp, fine, bifurcate near themiddle, and project slightly forward on the venter. 

During growth the primary ribs become blunt, prominent, and concave forward, and the secondary ribs arisecommonly by twos and threes but in some species by 

fours and fives. On the largest septate whorls many 

secondary ribs arise freely on the flanks and a smooth 

area may develop between the primary and secondary 

ribs. All ribbing tends to fade on the largest septate 

whorl preceding the adult body chamber. The adult 

body whorl is smooth or nearly smooth. Constrictions 

are common on the internal molds of the septate whorls 

and on the body whorl. The suture line is characterized 

by its first lateral lobe being shorter than its ventral 

lobe.

Within the Tolliinae the genus Tollia bears some 

resemblance to Homolsomites (Crickmay, 1930, p. 63; 

Imlay, 1956, p. 1143-1146; 1960, p. 201; Jeletzky, 1965, 

p. 39; Shulgina, 1965, p. 81-88). It differs by having p, 

wider and shallower umbilicus, a rounder whorl section, longer primary ribs, fewer secondary ribs per
B4 JURASSIC AND CRETACEOUS BVCHIA ZONES IN CALIFORNIA AND OREGON

primary rib, less distinct junctions of secondary ribs 

with the primary ribs, rib branching at only one level, 

less forward projection of secondary ribs oil the venter, loss of ribbing on the venter of the adult body 

whorl, and a shorter first lateral lobe relative to the 

ventral lobe.

Tottia differs from Wellsia Imlay (1957, p. 275; 

1960, p. 205-207; Shulgina, 1965, p. 84) in most of the 

same features that it differs from Homolsomites. In 

addition it differs by having much stronger primary 

ribs that branch near instead of above the middle of 

the flanks and that persist on the flanks to a later 

growth stage.

The family Berriasellidae is fairly well represented 

by the subfamilies Berriasellinae, Neocomitinae, and 

doubtfully by the Himalayitinae. The genera listed 

under these families in table 1 are all represented by 

typical specimens except Aulacosphinctes and Blanfordiceras. The presence of Aulacosphinctes is questioned because the specimen is too immature for certain 

generic identification. The specimens assigned to Blanfordiceras are smaller and more compressed than most 

species of that genus but closely resemble B. wallicJii 

(Blanford) (Uhlig, 1910, pi. 29) and B. acuticosta 

Uhlig (1910, p. 201-203, pi. 37, figs. 2a-c) from India 

and related species from Pakistan (Spath, 1939, p. 45, 

pi. 6, figs. 10, 13, 14) and Madagascar (Besairie, 1936, 

p. 136, pi. 11, figs. 17, 18). They also resemble "Hoplites" australis Burckhardt (1903, p. 64, pi. 11, figs. 

9-12) from Argentina, which Arkell and others (1957, 

p. L352) place in Blanfordiceras and Spath (1925, p. 

145) assigns to his genus Pseudoblanfordia.

The genus Blanfordiceras typically has an elliptical 

to subcircular whorl section that becomes stouter during growth. Its ribs are slightly sigmoidal, are highest 

near the middle of the flanks, project forward on the 

shoulders, and terminate in tubercles that border a 

smooth midventral area. In most species the primary 

ribs bifurcate near the middle of the flanks; however, 

in some species the primary ribs on the outer whorls 

become loosely connected with the secondary ribs, and 

other secondary ribs arise freely on the upper parts of 

the flanks. Adorally on the adult body chamber the 

ventral groove weakens or disappears and the primary 

ribs become widely spaced. In addition, tubercles or 

large knots may develop at furcation points near the 

middle of the flanks on the inflated species. Blanfordiceras differs from Berriasella by its ribs being more 

sigmoidal on the flanks, more projected on the venter, 

highest near the middle of the flanks instead of near 

the umbilical edge, and much more widely spaced on 

the body chamber.

The genus Siibsteueroceras is characterized by a 

moderate to narrow umbilicus, a vertical umbilical 

wall, a broadly rounded to flat venter on the adult, a 

lack of constrictions and tubercles, and by fine, generally high flexuous ribs that branch at various heights 

on the flanks, arch forward on the venter, and tend 

to disappear or weaken on the adult body whorl. The 

ribs may be di-, tri-, or bidichotomous, or unbranched, 

but are not virgatomous. A ventral groove is present 

on the internal mold but is not present on the adult 

wherever shell material is preserved. Siibsteueroceras 

differs from Kossmatia by lacking constrctions and 

by having a broader and flatter venter, finer ribs, irregular rib branching at various heights instead of on the 

middle third of the flanks, less strongly projected ribs 

on the middle third of the flanks, less strongly projected ribs on the venter, and a tendency of the ribs to 

fade out on the adult. Its rib pattern shows more 

resemblance to that of Siibthurmannia, but it differs 

from that genus by lacking constrictions and umbilical 

tubercles and by its ribs not forking at th°, umbilical 

edge.

The assignment of one small specimen from California to Protacanthodiscus is based on the presence of 

biplicate Berriasellid-like ribbing on the flanks, lateral 

and ventral tubercles, weak umbilical swellings, and a 

flat, nearly smooth venter.

The genus Parodotitoceras is characterized by a moderate to narrow umbilicus; by coarse geniiy flexuous 

ribs that incline forward on the flanks, bifurcate on 

the middle third of the flanks, and cross the venter 

nearly transversely; by the presence of constrictions; 

and by the absence of a ventral groove on adult whorls. 

It closely resembles Bernasella but differs by being 

more involute, by having much looser and more variable ribbing, and in particular by lacking a ventral 

groove on the adult body chamber wherevor the shell 

is preserved. Its inner whorls differ from the inner 

whorls of Siibsteueroceras by having constrictions, a 

more marked ventral groove, and less projected secondary ribs. Its outer whorls differ from those of S'ubsteueroceras by having much stronger and higher ribs, 

by fairly regular bifurcation near or above the middle 

of the flanks instead of bi- or trifurcation at various 

heights, and by the presence in some species of many 

single ribs.

The subfamily Neocomitinae is represented by many 

specimens of Thurmanniceras and Neoccmites^ rare 

specimens of Kilianella, Sarasinella and Feocosmoceras, and probably also by the new genus Paskentites. 

Of these, Thurmanniceras is characterized by having 

a compressed moderately to fairly evolute shell, con-
AMMONITES FROM THE BUG HI A ZONES

strictions, lateral and ventral tubercles, and gently to 

strongly flexuous ribs that arise singly at the umbilical 

edge, bifurcate near the middle of the flanks, and cross 

the venter transversely with slight or no reduction in 

strength. Many simple ribs may be present. Its inner 

whorls have a flattened venter, and its outer whorls a 

gently rounded venter. It differs from Neocomites by 

having an oblique instead of a vertical umbilical wall, 

a gently rounded instead of a truncated venter on adult 

whorls, and by its ribs on adults arising singly at the 

umbilical edge and forking mostly near the middle 

of the flanks. It differs, also, by lacking umbilical 

tubercles and a smooth midventral area except at a 

very small size.

The genus Neocomites is characterized by having an 

involute compressed shell, flattened flanks, a smooth 

flat venter that has rather sharp edges, a vertical 

umbilical wall, umbilical and ventral tubercles only, 

and rather fine, fairly closely spaced flexuous ribs that 

incline gently forward on the flanks and cross the venter transversely. These ribs may arise singly or in 

pairs from small umbilical tubercles, commonly bifurcate again near the middle of the flanks, terminate 

ventrally on the septate whorls in small obliquely 

arranged tubercles that border a smooth midventral 

area, and on the adult body whorl may cross the venter 

transversely.

The genus Kilianella is characterized by having a 

small evolute shell; an elliptical to suboctagonal whorl 

section; deep constrictions; a few weak umbilical, lateral, and ventral tubercles; a smooth venter; and strong 

gently flexuous ribs of which many remain simple. The 

ribs commonly bifurcate on the middle of the flanks 

and rarely at the umbilical edge. The ventral terminations of the ribs are commonly broad and fairly strong. 

Adult specimens of KiUaneUa resemble immature specimens of Thurmanniceras but may be distinguished by 

their ribs being more flexuous and generally much 

thicker ventrally and by bearing a few umbilical 

tubercles.

The genus Sarasinella resembles Neocomites in shape, 

involution, and ornamentation but differs by having 

lateral tubercles on its inner whorls, by its umbilical 

tubercles becoming increasingly stronger on its outer 

whorl, and by its ribs on the outermost whorls commonly arising in pairs from umbilical tubercles.

The genus Neocosmoceras has a wide umbilicus, a 

polygonal whorl section, and a venter that changes 

from concave to gently convex during growth. Its ribs 

are straight and widely spaced on the flanks and are 

interrupted on the venter. It bears three rows of strong 

to fairly strong tubercles of which the umbilical and

365-J28 O 70 2

lateral are conical to radially elongate and the ventral 

are spirally elongate. Its aperture bears prominent 

lateral lappets. Its outer whorl shows some resemblance 

to that of Protacanthodiscus but differs by the presence 

of lateral lappets and of spirally arranged tubercles 

Its inner whorls differ from those of Protacanthodiscus 

by the presence of coarse, simple, widely spaced trituberculate ribs instead of closely to moderately spaced 

biplicate ribs that bear only lateral and ventral 

tubercles.

The new genus Paskentites is characterized by r, 

compressed shell, evolute coiling, coronate inner whorls 

resembling Stephanoceras, perisphinctoid outer whorls^ 

and strong projection of ribs on the venter.

STRATIGRAPHIC RELATIONSHIPS OF AMMONITES 

TO BUCHIAS

The stratigraphic positions and ranges of the ammonites described or mentioned herein relative to the 

species of Buchia with which they are associated are 

shown diagrammatically in figure 1, which summarizes 

the stratigraphic data presented in detail under the 

locality descriptions. A stratigraphic arrangement of 

the most characteristic ammonites relative to the species of Buchia is shown in figure 2. These figures do 

not include certain species of Valanginian age from 

California and Oregon whose associations with particular species of Buchia are uncertain or unknown.

The ammonites of Tithonian age have been found 

mostly in the Paskenta-Elk Creek area in northwestern 

California, west of Corning and Orland. In that area 

the ammonite Kossmatia occurs from 4,000 to 5,000 

feet above the base of the beds containing Buchia 

piochii (Gabb) and also near the middle of those beds. 

Considerably higher, but at least 2,000 feet below the 

base of the beds containing Buchia aff. B. okensis 

(Pavlow), occur a few ammonites belonging to Parodontoceras, Groeberi-cerasl, Aulacosphinctesl, and 

Phylloceras. Associated with B. aff. B. okensis (Pavlow) in the upper 500-1,000 feet of the Jurassic ar^ 

the ammonites Phylloceras, Lytoceras, Proniceras, Spiticeras, Blanfordiceras, Siibsteueroceras, Parodontoceras, and questionably Aiilacosphinctes.

The only ammonite of probable Jurassic age found 

in southwestern Oregon is an immature specimen of 

Proniceras (Mesozoic loc. 2074) that is associated with 

N eocosmoceras i many specimens of Buchia uncitoides 

(Pavlow), and a few specimens of B. piochii (Gabb). 

The specimens of B. piochii and Proniceras have a 

slightly different matrix than the other fossils, which 

suggests that they were obtained from different bedf. 

N'eocosmoceras could also be late Tithonian in ag?. 

judging by its stratigraphic distribution in Pakistan
B6 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

= I

c -; _
NvucrasperiitvK yiynntt UK Imlay 

Blanfunlicei'as mlifornicMni Imlay and Jones, n. sp 

sp. undet

cf. S ktlhttui Imlay 

Prota/'atithfidifrun taffi (Anderson) 

Pamrfontorrrui stnrrxi (Stantonl 

cf. P storrsi (Stanton) 

refill ( Anderson ) 

Aidneospliuictex't ditiblnetisin Anderson 

? jenvinsi Anderson 

? sp. juv 

Paskentitfn paskentiit'tixis Imlay and Jones, n. sp 

cf. P itagkviitiiensis Imlay and Jones, n. sp 

Thurmnnnicvnis stippi ( Anderson 1 

cf T. stippi ( Anderson) 

jenkitisi (Anderson) 

cf. T.jenkinsi (Anderson) 

ralifornirum (Stanton) 

Neormmtex cf. AT. wichmunni Leanza 

cf . N. neueoniiensla (d'Orbigny) 

cf. N. nencot/iieiisis var premultea (Sayn) 

sp 

KilianeUa enisxiplicata (Stanton) 

Sarasinflln cf.S xnhspinusa Uhlig 

atigidatn (Stanton) 

cf S iihligi Spath 

sp 

Neucnumnrerns eurfirenut' Imlay and Jones, n. sp 

? cross?' (Anderson)

A 

----- ~-Y

A

A

........?

- -Y

............?

A

.............Y

. ... ...... -Y

.......... ...Y

.. .. ..Y

A

. ......... Y

FIGURE 1. Stratigraphic relationships of ammonites with species of BucMa. A questionk mark(?) indicates that asso

a particular species of Buehia is uncertain. Black bars show known stratigraphic ranges of the ammonite spe

the Buchia zones. An X indicates that the exact stratigraphic position or range within the BucMa zone is un
B8 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

European

series and

stages

Characteristic fossils

rthwestern California

southwestern Oregon

Characteristic fossils

in western

British Columbia

(after Jeletzky, 1965)

Valanginian

!H 8

Tallin mutabili

Biicftia aff. 

B. okensis

Buchia

elderettsis

Not 

identified

Buchia cf.B 

blaiiforditinti

Tollia Htutabilis

Tollia spp.

FIGUEE 2. Correlation of latest Jurassic (Tithonian) and earliest Cretaceous (Berriasian and Valanginian) faunas in California and Oregon.
AMMONITES FROM THE BVCHIA ZONES B9

Characteristic fossils

in Mexico

(Imlay 1943, 1M44, 1952, 

Erben,19571

Characteristic fossils,

in Argentina

(After Windhausen, 1918; 

Gerth, 1925; Weaver, 

1931; Leanza, 1945; Giovine, 195IJ; Arkell, 19561

Southern Europe 

(After Barbier, Debelmas, 

and Thieuloy, 1965, Enay, 

1964; Barthel, 1962)

Russian platform 

(After Sachs and Shulgina, 

1964; Sachs, 1965; Gerasimov and Mikhailov, 1967)

European

Series and

stages

nlcustephanua curtui

Liswfiia ? (('( rui 

(not zoned)

Pu! apt a flutes michulskii

and P Ktyserhngi

Valanginian

Tollia tulli 

in Ural Mts.

Alyenti>iiceras nodtiliferu>n

and 

Neocosaiueerus vgreyiu m

Mitiapilites

and 

Hybonotitfr

Cruspedites subditui

Berriasella

del phi

Dorsoi-ilanites patnleri

Subpla n Hex pxe udoscytli i

FIGUBE 2. Continued.
BIO JURASSIC AND CRETACEOUS BVCHIA ZONES IN CALIFORNIA AND OREGON

(Fatmi, 1966, table 3), but the genus is generally considered indicative of a Berriasian age (Arkell and 

others, 1957, p. L358).

The previous record of the late Tithonian genus 

Pronicems at several other localities (Mesozoic Iocs. 

3348, 3349, 25183, 25184) in southwestern Oregon (Imlay and others, 1959, p. 2780) was based mainly on 

fragments that could belong to the related genus Spiticeras of late Tithonian to Berriasian age. Furthermore, 

the presence of Buchia uncitoides (Pavlow) at Mesozoic Iocs. 3348, 25183, 25184 indicates a Berriasian 

rather than a Tithonian age. It appears that the Tithonian is represented in southwestern Oregon only by 

beds containing Buchia piochii (Gabb) that crop out 

from the Dillard area (Imlay and others, 1959, fig. 1 

on p. 2771) south westward to the coast. No occurrence 

of Buchia aff. B. okensis (Pavlow) has yet been found 

in Oregon.

Ammonites of Berriasian age have been found with 

Buchia uncitoides (Pavlow) in a few places in both 

California and Oregon and have hitherto been interpreted as of Tithonian age. This mistake in age was 

based mainly on the fact that crushed and immature 

specimens of B. uncitoides are difficult to distinguish 

from B. piochii (Gabb) and that ammonites are not 

common. In both States the ammonite evidence for a 

Berriasian age consists of Neocosmoceras and Spiticeras (Negreliceras), although both occur rarely in 

beds of late Tithonian age. Other ammonites associated 

with Buchia uncitoides (Pavlow) include /Spiticeras 

(Spiticeras), 8. (Kilianiceras'l), and Phylloceras. The 

subgenera Negreliceras and Spiticeras range throughout most of the lower two-thirds of the beds containing 

Buchia uncitoides (Pavlow) in the area between Elder 

Creek and Grindstone Creek in northwestern California. In Oregon the stratigraphic positions of these 

genera have not been determined with respect to the 

base or top of the beds containing B. uncitoides 

(Pavlow).

Ammonites of Valanginian age are much more common in California and Oregon than are ammonites of 

Berriasian age or of Tithonian age older than the 

zone of Buchia aff. B. okensis (Pavlow). Most of the 

Valanginian ammonites from California are associated 

either with Buchia pacifica Jeletzky or with B. keyserlingi (Lahusen). In Oregon the association of certain 

Valanginian ammonites, such as Olcostephanus and 

Homolsomites, with B. crassicollis solida (Lahusen) is 

well established.

In California the relative positions of the ammonites 

within the Buchia pacifica zone are known mainly for 

the Paskenta area. Among these ammonites, Thurmanniceras cf. T. stippi (Anderson) is from the lower 150 

feet. Paskentites and Kilianella, Lytoceras, and Thurmanniceras are from the middle third. Kilianella occurs 

also about 200 feet below the top. The upper 100-200 

contain an abundance of Tollia mutabilis (ftanton) 

and Bochianites paskentaensis Anderson along with a 

few specimens of Sarasinella.

In the Buchia keyserlingi zone near Paskenta, Calif., 

Thurmanniceras jenkinsi (Anderson) ranges throughout, T. stippi (Anderson) ranges through the middle 

and upper parts, Neocraspedites and Polyptychites 

occur near or a little above the middle, and Sarasinella 

occurs near the base. Other ammonites associated with 

B. keyserlingi but of uncertain stratigraphic position 

because of faulting include Lytoceras saturnale Anderson, Cnoceratites sp., some specimens of Neocraspedites and Polyptychites tnchotomus (Stanton). In 

addition, Olcostephanus, Neocomites, and one specimen of Polyptychites were obtained from the lower 

part of the B. keyserlingi zone near the Soi^th Fork 

of Cottonwood Creek in the west-central part of the 

Colyear Springs quadrangle.

In Oregon some of the ammonites of Valanginian 

age are not associated with Buchia in the collections, 

or the specimens of Buchia present are crurhed and 

unidentifiable, or the collections were made over a 

considerable distance and may contain Buchias from 

different beds than the ammonites (Mesozoic Iocs. 

4386, 2154). Nonetheless, the ammonites Spiticeras 

(Kilianicerasi.) (Mesozoic loc. 24702) and Sffrasinella 

hyatti (Stanton) (Mesozoic loc. 4386) are associated 

with larger crushed Buchias that probably 13long to 

B. pacifica Jeletzky. Sarasinella hyatti is, also, associated with B. keyserlingi at three localities (Mesozoic Iocs. 4384, 4386, 26405; see Imlay, 196C, p. 187, 

188).

The presence of Buchia keyserlingi in Oregon is not 

by itself evidence for correlating the beds in which it 

occurs with the Buchia keyserlingi zone in northwestern California because B. keyserlingi in California 

occurs also with B. pacifica Jeletzky and in western 

British Columbia occurs as low as B. uncitoides (Pavlow) . Also, in Oregon the position of Sarasinella hyatti 

and Buchia keyserlingi at Mesozoic Iocs. 4384 and 

4386 appears to be lower stratigraphically than the 

beds containing Tollia mutabilis (Stanton) and large 

crushed Buchias at Mesozoic loc. 2154 (Imlay, 1960, 

p. 173, 174). Evidently the sequence of Buchias and 

ammonites has not yet been as well established in 

southwestern Oregon as in California.

In Oregon the zone of Buchia crassicollis solida has 

furnished the ammonites Olcostephanus pecki Imlay,
AMMONITES FROM THE BUCHIA ZONES Bll

O. popen-oi Imlay, and Homolsomites quatsinoensis 

(Whiteaves) from several hundred feet of beds exposed on the South Umpqua River near Days Creek 

in Douglas County (Imlay, 1960, p. 184, 185). These 

were obtained directly beneath beds containing Hauterivian ammonites (Imlay and others, 1959, p. 2775 

2782-2784).

AGES AND CORRELATIONS OF THE 

AMMONITE FAUNULES

JURASSIC AMMONITES 

TITHONIAN AMMONITES FROM THE BTJCHIA PIOCHII ZONE

The lower 5,000-6,000 feet of the Buchia piochii zone 

in the Paskenta quadrangle of northwestern California 

is definitely Late Jurassic age, younger than early 

Kimmeridgian, as shown by the presence of the ammonites Kossmatia and Durangites^ (Anderson, 1945, p. 

981-983; Stanton, 1895, p. 82) from 7,000 to 7,500 feet 

below the top of the B. piochii zone. The age of these 

beds is probably younger than Kimmeridgian, however, considering the ranges of Kossmatia and Durangites in Mexico (Imlay, 1939, p. 22, 23), the resemblance of Buchia piochii (Gabb) to species near the 

top of the Jurassic in the Boreal region (Pavlow, 1907, 

p. 82, 83), and the absence of Buchia mosquensis (von 

Buch) and B. rugosa (Fischer). The absence of the 

last two species in California seems particularly significant because they are common elsewhere in North 

America in beds of middle Kimmeridgian to middle 

Tithonian ages (Imlay, 1955, p. 74, 75, 85; 1959, p. 

157) and are common in Russia in the Volgian zones 

of Siibplanites sokolovi to Dorsoplanites panderi inclusive (Gerasimov and Mikhailov, 1967, p. 9, 19, 20). 

This range is equated by the Russian paleontologists 

just quoted with the southern English zones of Siibplanites spp. to Zaraiskites albani inclusive (Arkell, 

1956, p. 10), which confirms an earlier statement by 

Spath (1936, p. 166, 167).

The presence of Durangites, if verified, would be 

particularly useful for an age determination, as the 

genus is known elsewhere near the top of the Jurassic 

in Mexico (Burckhardt, 1912, p. 143, 205; Imlay, 

1939, p. 22, 23, 46-49) and in Cuba (Imlay, 1942, p. 

1433, 1436, 1452, pi. 3, figs. 5-7). In Mexico it occurs 

commonly in association with Kossmatia, Micracanthoceras, and Hildoglochiceras just below beds containing Siibsteueroceras. In California Durangites was 

recorded by Anderson (1945, p. 1001) from CAS loc. 

29694, which is 600 feet north of Hull's gate in sec. 35, 

T. 25 N., R. 7 W., Paskenta quadrangle, and, therefore, at about the same stratigraphic position as two

species of Kossmatia described by Anderson (1945, pi. 

2, figs. 1, 3). Unfortunately, the specimen from California illustrated by Anderson (1945, pi. 2, figs. 4a, b) 

as Durangites is now lost, and a positive generic identification cannot be made from the illustrations.

The presence of Kossmatia in California is of considerable age value because the genus occurs in Mexico 

in abundance near the middle of the Tithonian sequence 

below beds characterized by Siibsteueroceras and above 

beds characterized by Pseudolioceras, Subplanites, anc1 

Aulacosphinctoides (Burckhardt, 1912, p. 220-222, 

1930, table 11 opposite p. 112; Imlay, 1939, p. 22, 23; 

1943, p. 538, 539). Likewise, in Argentina, it occurr 

high in the Tithonian (Krantz, 1928, p. 49) associated 

with Aulacosphinctes and above beds containing Parodontoceras and Corongoceras, which in turn overlie 

beds containing Pseudolissoceras zitteli Burckhardt. 

By contrast, in southern Europe and northern Africa 

Kossmatia is reported to range through the entire 

Tithonian (Mazenot, 1939, p. 129, 130) and its total 

worldwide range is Kimmeridgian through upper 

Tithonian (Arkell and others, 1957, p. L323).

The Kimmeridgian age for Kossmatia given bj* 

Arkell is based on his studies of ammonites from $. 

thick and apparently comfortable sequence exposed or 

the shore of Kawhia Harbour in New Zealand (Fleming, 1960, p. 264-268; Fleming and Kear, 1960, p. 17- 

45; Stevens, 1965, p. 22-32, 132-135). At this place 

Kossmatia occurs above the ammonites Idoceras, Subneumayria, and Epicephalites of early Kimmeridgiar 

age and mostly below the ammonite Aulacosphinctoides 

of late Kimmeridgian to middle Tithonian age. It 

occurs also within the lower part of the local range 

of Aulacosphinctoides. Its age, therefore, at Kawhk, 

Harbour is definitely late Kimmeridgian and, on the 

basis of stratigraphic position, is partly middle Kimmeridgian.

The upper 4,000-5,000 feet of the Buchia piochii 

zone is definitely middle to late Tithonian in age as 

shown by the stratigraphic position between occurrences of Kossmatia below and Siibsteueroceras above 

and by the presence of the ammonites Parodontoceras 

and Spiticeras. Of these, Parodontoceras (Mesozoic loc. 

1084), found several thousand feet below the top of 

the zone, is excellent evidence for an age not older 

than late middle Tithonian, and Spiticeras (Mesozoic 

loc, 1085), found a few hundred feet below the top of 

the zone, is evidence of an age not older than late 

Tithonian. Also, the presence of an ammonite resembling Groebericeras (Mesozoic loc. M2024), found 

about 2,100 feet below the top of the zone, favors an 

age not older than late Tithonian because that genus
B12 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

lias been found only in beds of Berriasian age in 

Argentina (Leanza, 1945, p. 82).

Only part of the Buchia piochii zone of California, 

as defined herein, is equivalent to beds in western British Columbia and Arctic Canada that supposedly are 

characterized by B. piochii (Gabb) (Jeletzky, 1965, 

fig. 2 opposite p. 2). Exact equivalence seems unlikely 

because the specimens of Buchia piochii (Gabb) from 

California, including the type specimen, show scarcely 

any resemblance to the varieties assigned to that species by Jeletzky (1965, pi. 1, figs. 3-6, 9). Furthermore, 

the specimens of Buchia from the lower part of the 

B. piochii zone in California, described by Anderson 

(1945, p. 965-967, 973) under the names B. sollasi 

(Pavlow), B. sp. A, B. aff. B. mosquensis (von Buch), 

and B, elderensis (Anderson), all show considerable 

resemblance to Buchia cf. B. blanfordiana (Stoliczka) 

of Jeletzky (1965, pi. 2, figs. 3, 4, 6, pi. 3, figs. 4-8), 

which in western British Columbia occurs at the top of 

the Jurassic sequence beneath a disconformity. This 

comparison indicates that the lower part of the B. 

piochii zone in California is equivalent to the B. cf. 

B. blanfordiana zone of western British Columbia and 

that the upper part of the Buchia piochii zone in California may be represented in western British Columbia 

by the disconformity below the basal Cretaceous zone 

of Buchia okensis as suggested by Jeletzky (1965, p. 

17, 18). These correlations, if valid, explain why specimens resembling the holotype of B. piochii (Gabb) 

have not been illustrated from Canada and why thevarious varieties of B. piochii described by Jeletzky 

have not been found in California.

TITHONIAN AMMONITES FROM THE BUCHIA 

AFF. B. OKENSIS ZONE

The beds in California that contain Buchia aff. B 

okensis (Pavlow) are considered to be of latest Jurassic 

(late Tithonian) age because they contain the ammonites Sufosteueroceras, Parodontoceras, Blanfordiceras,- 

Proniceras, and Spiticeras (Spiticeras) and are stratigraphically just beneath a sequence characterized by 

the pelecypod Buchia. uncitoides (Pavlow) and the 

ammonite Spiticeras (Negreliceras}. The presence of 

of these ammonites is excellent evidence for a Late 

Jurassic age because Spiticeras and Blmifordiceras have 

not been found in beds older than late Tithonian 

(Djanelidze, 1922, p. 29, 36), Proniceras is characteristic of the upper Tithonian (Djanelidze, 1922, p. 48, 

52), Parodontoceras in Mexico (Imlay, 1939, table 3 

opposite p. 24; 1942, p. 1433, 1434) and Argentina (Leanza, 1945, p. 91, 92) occurs only in beds of middle to 

late Tithonian age, and Substeueroc&ras is characteristic of the topmost Jurassic beds in Mexico (Imlay, 1939,

table 3 opposite p. 34) and Argentina (Lesnza, 1945, 

p. 91, 92).

Additional evidence for a Late Jurassic age consists 

of the close resemblance of the species of Substeueroceras and Parodontoceras in California to species of those 

genera in Mexico or Argentina. Thus, Siibsteueroceras 

stantoni Anderson (1945, p. 982, pi. 11, figs. 3, 4, pi. 15, 

fig. 3) is similar to 8. siibqimdratum Imlay (1939, p. 

49, pi. 15, figs. 8, 12-15) from Mexico. Another species 

of Substeueroceras, erroneously assigned to Berriasella 

storrsi (Stanton) by Anderson (1945, p. 980, pi. 7, fig. 

1) closely resembles S. kellumi Imlay (1939, p. 50, pi. 

14, figs. 1-4) from Mexico and S. koeneni (Steuer) 

(1897, p. 171, pi. 17, figs. 1-5) from Soutl America. 

In addition, Parodontoceras reedi (Anderson) (1945, 

p. 978, pl.6, fig. 10, pi. 7, fig. 3) resembles eome specimens of Parodontoceras from Mexico described as Berriasella cf. B. calistoides (Behrendsen) by Burckhardt 

(1906, pi. 19, fig. 9; 1912, pi. 39, fig. 7). It also shows 

considerable resemblance to the finer variants of Parodontoceras calistoides (Behrendsen) from Argentina 

(Steuer, 1897, pi. 17, figs. 13-16; Leanza, 1945, pi. 5, 

figs. 5, 6) and could fall within the range of variation 

of that species.

The Buchia aff. B. okensis zone has not yet been 

recognized in southwestern Oregon. Its absence may be 

due to either a disconformity or a lack of detailed collecting. Likewise, in western British Columbia, the 

zone has not been recognized and probably is represented by the disconformity beneath the B. okensis 

zone (Jeletzky, 1965, figs. 1 and 2 opposite p. 2, p. 

17). The beds in California that contain Buchia aff. 

B. okensis (Pavlow) are not equivalent to the B. okensis zone in western British Columbia (Jeleftzky, 1965, 

p. 20-26, fig. 1 opposite p. 2) or in northern Alaska 

(Imlay, 1961, p. 5, 6) because they lack the extremely 

coarse ribbed variant of B. okensis (Pavlow) that occurs in the other areas (Jeletzky, 1965, pi. 4, figs. 1, 

19, 20, pi. 5, fig. 7, pi. 6, figs. 1, 2, 4-6, pi. 7, fig. 3; 

Imlay, 1961, pi. 7, figs. 5, 9, 12, 17-20).

CRETACEOUS AMMONITES 

BERRIASIAN AMMONITES FROM THE BUCHIA UNCITOIDES ZONE

The Buchia uncitoides zone in California is considered to be mainly of Berriasian age as shown by its 

stratigraphic position directly above beds containing 

the latest Tithonian ammonites Substeuerocera-s, Parod&nfoceras, and Proniceras and by the presence of 

Spiticeras (Negreliceras} and S. (/Spiticeras) throughout the lower two-thirds of the zone. Of these ammonites, the subgenus Negreliceras is characteristic of the
AMMONITES FROM THE BUCHIA ZONES B13

Berriasian, is represented by only one species from the 

upper Tithonian, and is unknown from the Valanginian 

(Djanelidze, 1922, p. 48, 49, 51). The subgenus 

/Spiticeras ranges from the top of the Tithonian through 

the Berriasian but no higher (Djanelidze, 1922, p. 51). 

On the basis of ammonites, therefore, most of ih&Biichia 

uncitoides zone in California cannot be younger than 

Berriasian and is unlikely to be as old as Tithonian. The 

upper third of the B. uncitoides zone, however, has not 

furnished ammonites and could be younger than 

Berriasian.

The beds in Oregon that contain Buchia- uncitoides 

are similarly dated as Berriasian because of the presence 

of /Spiticeras (Negrelicera-s}, 8. (Spiticeras), 8. (Kilianicemsl.), and Neocosm-oceras, a genus known mainly 

from the Berriasian (Mazenot, 1939, p. 179,182; Wright 

in Arkell and others, 1957, p. L358). The stratigraphic 

position of these ammonites within the BucJim uncitaides zone in Oregon is not known.

The BucJiia uncitoides zone is widespread in northwestern California and in southwestern Oregon. In 

California it directly overlies the B. aft1 . B. okensis 

zone. In Oregon, by contrast, the B. uncitoides zone 

rests directly either on beds containing Buchia piochii 

(Gabb) or on basement rocks. BucJiia uncitoides (Pavlow) is the characteristic species in the type section 

of the Riddle Formation exposed on the South Umpqua 

River near Days Creek. In that section the species 

ranges upward about 1,000 feet from 20 feet above the 

basal conglomerate into the third conglomerate (Imlay 

and others, 1959, p. 2776).

The BucJiia uncitoides zone in California and Oregon 

may be correlated approximately with the Buchia uncitoides zone in western British Columbia on the basis 

of having the same characteristic species of BucJiia and 

the same genera and subgenera of the ammonite Spiticeras (Jeletzky, 1965, p. 27-35, fig. 1 opposite p. 2). 

That ammonite on the west coast of Vancouver Island 

(Jeletzky, 1965, pi. 11, figs. 2, 3, 7, pi. 12, figs. 4, 5) 

ranges from 21 to 128 feet above the base of the BucJiia 

uncitoides zone, which is about 270 feet thick, and 

dates the lower part of the zone as not younger than 

Berriasian. Additional evidence for a Berriasian age 

is furnished by a small fragment of an ammonite (Jeletzky, 1965, pi. 11, figs. 4a-d) belonging probably to 

ProtacantJwdiscus or Neocosmoceras that was collected 

about 167 feet above the base of the zone. The upper 

103 feet of the zone has not furnished any ammonites 

and could be younger than Berriasian.

The BucJiia uncitoides zone in California differs 

markedly from that zone in British Columbia by a 

near absence of B. okensis (Pavlow), by a much greater

365-128 O 70 3

abundance of the ammonite Spiticeras (Negreliceras), 

and by its stratigraphic position directly on beds of 

probable latest Jurassic age. Presumably the lower part 

of the B. uncitoides zone in California is equivalent 

to the B. okensis zone of British Columbia. An alternate explanation would be that the BucJiia okensis zone 

in British Columbia is actually of Late Jurassic age 

and equivalent to the beds in California that contain 

BucJiia aft'. B. okensis (Pavlow). This possibility, however, seems unlikely because in British Columbia B. 

okensis and B. uncitoides are associated throughout 

their range, whereas in California B. aff. B. okensis 

(Pavlow) is associated with B. terebratuloides (Lahusen) but not with B. uncitoides (Pavlow). Also, th?, 

BucJiia okensis zone in British Columbia contains r,n 

extremely coarse ribbed variant of B. okensis that do^s 

not occur in the B. aff. B. okensis zone in California.

In summation, the Buchia uncitoides zone in California and Oregon contains ammonites of Berriasim 

age. It is correlated with beds in British Columbia that 

contain both B. okensis (Pavlow) and B. uncitoides 

(Pavlow) as well as ammonites of Berriasian age. In 

both California and British Columbia the upper third 

of the B. uncitoides zone has not furnished ammonites 

and could be as young as Valanginian.

Correlation of the BucJiia uncitoides zone in California, Oregon, and British Columbia with the faunal 

zones in northern Eurasia presents difficulties as discussed by Jeletzky (1965, p. 34, 35). Apparently in 

northern Eurasia B. okensis (Pavlow) ranges fnna 

the base of the Cretaceous through the zone of Surites 

spasskemis (Nikitin) (Sachs and others, 1963, p. 61- 

63, table 7) and is associated with B. uncitoides (Pavlow) only at the top of its range (Suntes analogus 

subzone). The species B. uncitoides (Pavlow) definitely 

ranges upward through the zone of Tollia tolli (Sachs 

and others, 1963, p. 65), which the Russian paleontologists consider of late Berriasian age, and Jeletzl'y 

(1965, p. 34) considered of early Valanginian age. Still 

higher in the lower or middle Valanginian zone of 

PolyptycJiites micJialskii are recorded B. uncitoides 

(Pavlow and B. cf. B. uncitoides (Pavlow) (Sachs 

and others, 1963, p. 67, 68, 70, table 7). These records 

show that in northern Eurasia the species B. uncitoides, 

if correctly identified, ranges from about middle Berriasian to middle Valanginian.

This apparent discrepancy between the vertical range 

of Buchia uncitoides in northern Eurasia as compared 

with its range in western Canada has been noted by 

Jeletzky (1965, p. 34, 35), who suggested that in Eurasia the Berriasian species of Buchia may have been 

reworked into beds of Valanginian age or that tie
B14 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Berriasian and Valanginian species of Buchia may 

have been concentrated within a single thin bed as a 

consequence of extremely slow deposition. It is possible, 

of course, that B. uncitoides in western North America 

actually ranges into the Valanginian or that it has a 

slightly different range than in Eurasia. Accurate correlations and age determinations of the Buchia uncitoides zone in western North America must await the 

discovery of well-preserved ammonites in the upper 

part of the zone.

VALANGINIAN AMMONITES FROM THE BUCHIA PACIFICA 

ZONE

The age of the Buchia pacifica zone in California on 

the basis of ammonites is probably entirely early to 

middle Valanginian. Its lower part, about 150 feet 

above its base, has furnished the ammonite Thurmanniceras, whose presence suggests an age not older than 

Valanginian (Busnardo, LeHegerat and Magne, 1965, 

p. 27, 32). Its middle part has furnished species of 

Thurtnanniceras and Kilianella that could be of early 

Valanginian age but suggest a middle Valanginian age 

because the species present resemble species of middle 

Valanginian age known elsewhere (Imlay, 1960, p. 

172). Its upper part is definitely Valanginian, as shown 

by the presence of SarasineUa, and is not younger than 

middle Valanginian, as shown by the presence of Tollia. 

That genus in Russia ranges from the upper part of 

the zone of Surites spasskensis (middle Berriasian) 

into the zone of Temnoptychites hoplitoides (early 

Valanginian) (Sachs and others, 1963, p. 68, tables 7, 

8; Sachs and Shulgina, 1964, table opposite p. 10). A 

middle Valanginian age for T. mutdbilis (Stanton) is 

supported, however, by the resemblance to T. paucicostata (Donovan) (1953, p. 110, pi. 23, figs, la, b), 

which occurs in East Greenland in association with 

the middle Valanginian ammonites Polyptychites and 

Euryptychites. A middle Valanginian age is supported, 

also, by the stratigraphic position of the B. pacifica 

zone below beds that have furnished ammonites of 

late Valanginian age.

The Buchia pacifica zone in southwestern Oregon is 

represented by the typical Buchia species at many 

localities from Riddle westward to the Pacific coast, 

but the stratigraphic position of the zone relative to 

the adjoining Buchia zones has not been studied. Furthermore, some of the older collections, such as from 

Mesozoic loc. 2154 and 2155, were made over distances 

of about a mile and probably include collections from 

more than one Buchia zone. The B. pacifica zone appears to be represented, however, by collections containing Sarasinella hyatti (Stanton) (Imlay, 1960, p.

172-174) and Tollia mutdbilis (Stanton) (Imlay, 1960, 

p. 174).

The Buchia paci-fica zone in California and Oregon 

may be correlated with the Buchia pacificc1. zone in 

western British Columbia on the basis of having the 

same species of Buchia, of having the same stratigraphic position relative to older species of Buchia, 

and of also containing Tollia mutdbilis (Str.nton) in 

the upper part of the zone. This species ir western 

British Columbia was obtained only in tin Bridge 

River area and was identified by Jeletzky (1964a, pi. 

6, figs. 1, 8, 9; 1965, p. 47, 53, pi. 18, figs. 1, 6, 7) as 

Dichotomites cf. D. giganteus (Imlay), a species which 

was originally described from California as Neocraspedites giganteus Imlay (1960, p. 204, pi. 32, figs. 1-6).

Examination of plaster casts of the ammorites from 

the Bridge River area show that they differ markedly 

from N. giganteus Imlay found in California. They 

have an oblique instead of a vertical umbilical wall; 

a gently rounded instead of an abrupt umbilical edge; 

sharp, narrow primary ribs instead of broad indistinct 

primary ribs; and less flattened flanks. Furthermore, 

one specimen (Jeletzky, 1964a, pi. 6, fig. 9b) bears a 

conspicuous constriction at a size much larger than in 

any genus of the subfamily Polyptychitinae, which includes both Dichotomies and N eocraspedites (Wright 

in Arkell and others, 1957, p. L348). Evidently the 

ammonites from the Bridge River area do not belong 

to the same genus or subfamily as N. giganteus Imlay.

In contrast the three ammonites from tr.e Bridge 

River area, British Columbia, illustrated as Dichotomites cf. D. giganteus (Imlay) by Jeletzky (1965, pi. 

16, figs. 1, 6, 7), agree very well in umbilical shape, 

whorl shape, sharp primary ribbing, fine dense secondary ribbing, and presence of constrictions with Dichotomites tehaniaensis Anderson (1938, p. 158, pi. 28, fig. 

2, pi. 30, fig. 6), which Imlay (1960, p. 201, pi. 28, figs. 

18-22) considers to be a finely ribbed variant of T. 

mutdbilis (Stanton). Likewise, the specimens from 

northeast British Columbia illustrated as Dichotomizes 

cf. D. giganteus (Imlay) by Jeletzky (1964b, pi. 12, 

figs. 11-13) are similar to T. mutdbilis tehaniaensis 

(Anderson). They have finer and denser secordary ribs 

than those on the holotype illustrated by Anderson 

(1938, pi. 28, fig. 2; Imlay, 1960, pi. 28, fig?. 18, 19) 

but are not much finer ribbed than one specimen illustrated by Imlay (I960, pi. 28, fig. 21).

Considering the close resemblances of these specimens from British Columbia to T. mutdbilis tehamaensis (Anderson), it is rather strikng that the other 

variants of T. mutdbilis have not been found in association as in California. This might be explained as a
AMMONITES FROM THE BUCHIA ZONES B15

happenstance of collecting, or perhaps the finely ribbed 

variant of T. mutabilis has a different geographic or 

stratigraphic range than the normal or the coarsely 

ribbed variants. Such differences would justify a subspecific rather than varietal rank for T. mutabilis 

tehamaetisis.

The ammonites from British Columbia that Jeletzky 

called Dichotomites cf. D. giganteus (Imlay) were considered by him (1965, p. 41, 53) to be closely related 

to Tollia mutabilis (Stanton) and to Olcostephanus 

quatsinoensls Whiteaves (1882, p. 82, fig. 1; Jeletzky, 

1965, p. 52, 53, pi. 20, figs. 3-5, 14, 15). The last mentioned species was referred by him (1965, p. 41, 53) at 

one time to Dichotomites, but after examination of the 

type species of Dichotomites was assigned on the basis 

of the suture line to Homolsomites (Jeletzky, 1965, 

footnote on p. 39), which is in the family Craspeditidae 

rather than in the Olcostephandidae. His final conclusions evidently are close to those presented herein concerning the generic and family assignments of the 

ammonites from British Columbia under discussion.

The Buchia pacifica zone in British Columbia was 

considered by Jeletzky (1965, p. 47, 48) to be mostly 

or entirely of middle Valanginian age on the basis of 

its stratigraphic position between the Buchia tolmatschowi zone of probable early Valanginian age and the 

B. crassicollis zone of late Valanginian age. An age not 

younger than middle Valanginian for the upper part 

of the B. pacifica zone is substantiated by the presence 

of the ammonite Tollia. Whether the lower part of the 

B. pacifica zone in British' Columbia is older than 

middle Valanginian must await the discovery of ammonites in that part. Nonetheless, such an age is favored by the presence of certain ammonites that have 

been found associated with B. pacifica Jeletzky in the 

upper part of the underlying B. tolmatschowi zone.

These ammonites from the Buchia tolmatschowi zone 

in British Columbia have been discussed in detail by 

Jeletzky (1965, p. 41-43), who concluded that they are 

probably of early Valanginian age. Stratigraphically 

the zone could be either late Berriasian or early to 

middle Valanginian. Faunally its upper part, which 

contains an association of Buchia pacifica Jeletzky and 

B. tolmatschowi (Sokolov), has furnished ammonites 

that Jeletzky (1965, p. 38) identified as follows:

Neocomites (Parandiceras) cf. N. (P.) rota

(Spath)

Tollia (Tollia) mutabilis (Stanton) sensu lato 

T. (T.) mutabilis var. burgeri (Anderson) 

T. (T.) mutabilis var. tehamaensis (Anderson) 

T. (T.) paucicostata (Donovan) 

T. (T.I) aff. T. simplex (Bogoslovsky)

On the basis of these fossils, the upper part of the 

B. tolmatschowi. zone was correlated by Jeletzky (19C5, 

fig. 2 opposite p. 2) with the upper part of the lower 

Valanginian, although the genus Tollia ranges slightly 

higher. The first four ammonites listed above from the 

upper part of the Buchia tolmatschoioi zone were resigned by Jeletzky (1965, p. 43) to the top of the lower 

Valanginian and were correlated with the Tollia mutabilis beds in California (Imlay, 1960, p. 174) on the 

basis of his identification of Tollia, mutabilis (Stantor ). 

The last two ammonites listed were considered by Jeletzky (1965, p. 38) as probably a little older than the 

first two species listed and are assigned an early Valanginian age on the basis of the presence of Tollia paucicostata (Donovan) (1953, p. 110, pi. 23, figs, la, V}. 

That species in East Greenland, however, was associated with species of Polyptychites and Euryptychites 

(Donovan, 1953, p. 102,110, pi. 20, figs. 4-6, pis. 21 and 

22) that are accepted as of middle Valanginian age 

(Jeletzky, 1965, p. 42, 43; Donovan, 1953, p. 33, 1£4; 

Sachs and Shulgina, 1964, table opposite p. 10). Such 

an age is a little younger than the age that Jeletzky 

(1965, fig. 1, p. 42, 43) assigned to the upper part of 

the B. tolmatschowi zone, but he suggested that the 

ammonites from Greenland may represent a mixture 

of several zones.

Examination by the writers of plaster casts of the 

ammonites from the Buchia tolmatschowi zone of we?tern British Columbia confirms the assignment of most 

of the ammonites to Tollia. Furthermore, the assignment of Olcostephanus mutabilis Stanton to Tollia 

(Jeletzky, 1965, p. 39, 40) instead of Homolsomites 

(Imlay, 1960, p. 200, 201) seems reasonable and agrees 

with the studies of Shulgina (1965, p. 82, 86). Exception is made, however, to the specific identification of 

four small crushed fragments as Tollia mutabilis (Stf/nton) because the fragments are too poorly preserved for 

positive identification. Exception is made, also, to the 

generic identification of one small immature ammonite 

as Neocomites (Parandiceras) cf. N. (P.) rota (Spath) 

(Jeletzky, 1965, pi. 16, figs. 5a, b). The specimen differs from Neocomites in the strict sense by lacking 

umbilical tubercles, by lacking rib branching at the 

umbilical edge, and by having fairly regular rib branching near the middle of the flanks. Its comparison with 

Parandiceras is not apt because it is much smaller th^.n 

any illustrated specimen of that genus (Spath, 1939, 

p. 76-79, pi. 13, figs. 2, 3a-d, pi. 15, figs, la, b, pi. 18, 

fig- 3).

The identification of Tollia paucicostata (Donovan) 

in western British Columbia by Jeletzky (1965, pi. 13, 

figs. 2, 5, 6, 7, 9, pi. 14, figs. 4-6, 8) is based on 10
B16 JURASSIC AND CRETACEOUS BUG HI A ZONES IN CALIFORNIA AND OREGON

laterally crushed ammonites of various sizes. These 

differ from the holotype of T. paucicostata (Donovan) 

from East Greenland by being appreciably more evolute and by having sparser and coarser ribbing at a 

comparable size. They differ from T. mutdbilis (Stanton) (Stanton, 1895, pi. 15, figs. 1-5; Imlay, 1960, pi. 

28, figs. 1-22; Jeletzky, 1965, pi. 14, figs. Ta, b, 9, pi. 

14, figs. 5a, b) by having coarser and sparser ribbing, 

a more narrowly rounded venter, and more evolute 

coiling. The more finely ribbed variants of the Canadian specimens bear ribbing comparable to that on the 

most coarsely ribbed variant of T. (T.) mutdbilis 

(Stanton) (see Imlay, 1960, pi. 28, figs. 1-4), as noted 

by Jeletzky (1965, pi. 14, figs. 8a-c). Overall, the Canadian specimens differ appreciably from both T. paucicostata (Donovan) and T. mutdbilis (Stanton) and 

cannot be used, therefore, for precise correlations with 

beds containing those species. The presence of the genus 

Tollia itself merely indicates an age not older than 

middle Berriasian or younger than middle Valanginian.

One other ammonite from Vancouver Island was 

illustrated by Jeletzky (1965, pi. 13, figs. 8a, b) as 

Tollia (Tollial) aff. T. (T.*) simplex (Bogoslovsky) 

(1902, p. 138, pi. 14, figs. 6a, b) and compared also with 

Surites poreckoetisis Sasonov (1951, p. 60, pi. 1, fig. 2) 

from Russia. Of these, T. simplex (Bogoslovsky) occurs in Russia in the lower part of the Polyptychites 

michalskii zone of early Valanginian age and is listed 

under the name Temnoptychites (Sachs and others, 

1963, table 7). The Canadian specimen differs from 

that species as well as from the species of Surites by 

having less regular rib bifurcation and some simple and 

intercalated ribs. It could be a coarsely ribbed variant 

of the Canadian species that Jeletzky refers to Tollia 

paucicostata (Donovan). Similar coarsely ribbed biplicate species of the Tolliinae, as discussed by Jeletzky 

(1965, p. 42), occur in Russia in beds of middle Berriasian to early Valanginian age.

In summation, the ammonites from the upper part 

of the Buchia tolmatschowi zone in British Columbia 

do not permit an exact age determination. The presence 

of the genus Tollia itself shows that the zone is not 

older than middle Berriasian or younger than middle 

Valanginian (Sachs and others, 1963, p. 64, 65, tables 

7, 8). The specimens of Tollia that are present either 

are too fragmentary for specific identification or are 

different from described species and hence do not permit an age determination closer than that indicated by 

the genus. The specimen assigned to Neocomites differs 

considerably from that genus and is of little age value. 

As all these ammonites occur in the lower part of the 

range of Buchia pacifica Jeletzky, they should be older

than Tollia mutdbilis (Stanton), which in California 

occurs at the top of the range of Buchia pacifica and 

is most probably of middle Valanginian age. On the 

basis of stratigraphic position, therefore, th°- Buchia 

tolmatschowi zone is probably at least as old as early 

Valanginian.

VALANGINIAN AMMONITES FROM THE BUCHIA KEYSERLINGI

ZONE

The age of most of the Buchia keyserling* zone in 

the Paskenta quadrangle in California is definitely 

Valanginian, as shown by the presence of Sarasinella 

near the base (Mesozoic loc. M3060) and Polyptychites 

about 1,250 feet above the base (Mesozoic loc. M1577). 

Furthermore, the association of Neocraspedites, Criocemtites, and Polyptychites at one place (Mesozoic 

Iocs. 1009, 1087) is good evidence that the beds at that 

place are of late Valanginian age (Imlay, 1960, p. 172, 

174; Wright in Arkell and others, 1957, p. L208, L348), 

as Polyptychites is not known higher than the upper 

Valanginian and the other genera listed are not known 

lower. Unfortunately, the association of tl ?>se three 

genera is in a faulted area in which the br.se of the 

Buchia keyserlingi zone cannot be determined. Their 

occurrence, however, appears to be considerably above 

the base of that zone and probably in the upper half.

The age of the highest part of the Buchia kiyserlingi 

zone in the Paskenta area is not older than kte Valanginian or younger than early Hauterivian, as indicated 

by the association of Thurmanniceras jenkinsi (Anderson) with the larger paratype of Neocraspedites giganteus Imlay at USGS Mesozoic loc. 1091 (eouals 2266 

and M1579). The abundance of Thurmanniceras at this 

locality favors a Valanginian age because the genus 

attained its greatest abundance during tl °, middle 

Valanginian.

The age of the basal part of the Buchia keyserlingi 

zone in the Paskenta area is not older than Ipte middle 

Valanginian, as indicated by the superposition of that 

part on the Buchia paci-fica zone whose upp^r part is 

probably of middle Valanginian age.

The age of the Buchia keyserlingi zone in the Colyear 

Springs quadrangle is likewise definitely Valanginian, 

as shown by the presence low in the zone of Olcostephanus, Polyptychites, and Thumn-annicems (Imlay, 

1960, table 2 on p. 172; Busnardo, LeHegarat, and 

Magne, 1966, table 6 on p. 27). Among these genera, the 

first two listed are not known below the Valanginian, 

Thurmanniceras is uncommon below the Valanginian, 

and Polyptychites is not known above the Valanginian. 

Furthermore, an age not older than middle Valanginian 

is suggested by the presence of a coarsely ribb?-d species
AMMONITES FROM THE BUG HI A ZONES B17

of Olcostephanus similar to O. atherstoni Baumberger 

(non Sliarpe). The Buchia keyserlingi zone in the 

Colyear Springs quadrangle cannot represent the latest 

Valanginian because it is overlain by beds characterized 

by Buchia crassicoUis (Keyserling) subspecies solida 

(Lahusen) of late Valanginian age.

In summation, the stratigraphic and f aunal evidence 

concerning the age of the Buchia keyserlingi beds in 

northwestern California shows that those beds are of 

late middle to early late Valanginian age.

In western British Columbia a distinct zone dominated by Buchia keyserlingi has not been recognized. 

Failure to recognize the zone may be related to a lack 

of exposures on the west coast of Vancouver Island 

(Jeletzky, 1965, p. 44, 49) and to the presence of volcanic rocks in the Harrison Lake area between the 

zones of B. pacifica and B. crassicoUis (Jeletzky, 1965, 

p. 49, fig. 4 on p. 65). Nonetheless, an association of 

B. pacifica with B. crassicoUis in the basal beds of the 

B. crassicoUis zone in western Canada (Jeletzky, 1965, 

p. 49, 51) suggests that a distinct zone of B. keyserlingi 

is truly absent and that Buchia pacifica is overlain 

directly by B. crassicoUis.

VALANGINIAN AMMONITES FROM THE BUCHIA CRASSICOLLIS 

SOLIDA ZONK

The age of the Buchia crassicoUis solida zone is latest 

Valanginian because it contains the highest Buchias 

found in the Pacific Coast region, because its characteristic Buchia species is common in Eurasia in the 

upper part of the Valanginian (Jeletzky, 1965, p. 54), 

because it directly underlies beds containing early 

Hauterivian ammonites on the South Umpqua Kiver 

near Days Creek, Oregon (Imlay and others, 1959, p. 

2775; Imlay, 1960, p. 175), and because at the same 

locality near Days Creek it is associated with the 

ammonites Olcostephanus and Homolsomites.

Of these ammonites, Olcostephanus is represented by 

O. pecki Imlay (1960, p. 202, 203, pi. 29, figs. 1-5, 7-9, 

pi. 30, fig. 7), a species which closely resembles O. jeannoti (d'Orbigny) (1841, p. 188, pi. 56, figs. 3-5) from 

the latest Valanginian and early Hauterivian of 

France. Homolsomites is represented by the species H. 

quatsinoensis (Whiteaves) (formerly referred to H. 

stantoni McLellan by Imlay, 1960, p. 201, pi. 27), which 

is similar to H. lojarkensis Shulgina (1965, p. 84, pi. 

1-4, pi. 5, fig. 2) from northern Siberia. This latter 

species is considered to be of early Hauterivian age by 

the Kussian paleontologists because it overlies beds 

containing Dichotomites Shulgina (1965, p. 83), which 

in their stratigraphic scheme is defined as marking the 

uppermost Valanginian (Sachs and others, 1963, table

8). Nonetheless, the association of H. bojarkensis Shulgina with Buchia crassicoUis (Keyserling) and B. sublaevi-s (Keyserling, but not with any ammonites of 

definite Hauterivian age (Sachs and others, 1963, tables 

7, 8), suggests that the early Hauterivian age of Homolsomites in Siberia is not well established.

The characteristic ammonites of the Buchia crassicoUis solida zone in Oregon have not been found in 

northern California but are associated with B. crassicoUis solida in northwestern Washington (Imlay, 1960, 

p. 175, pi. 27, figs. 1-13; Jeletzky, 1965, p. 54, pi. 20, 

figs. 2, 5-7, pi. 21, figs. 4, 9, 10) and in western British 

Columbia (Jeletzky, 1965, p. 52, pi. 20, figs. 3, 4,13-15, 

pi. 21, fig. 11). In these areas north of California 

Homolsomites quatsinoensis (Whiteaves) has been 

found only in the lower part of the Buchia crassicoUis 

solida zone (Imlay and others, 1959, fig. 2 on p. 2775; 

Jeletzky, 1965, p. 52).

Buchia crassicoUis solida (Lahusen) has been found 

in California only in the Colyear Springs quadrangle 

north of the Elder Creek fault. In southwestern Oregon the species is widespread from the Riddle ar^a 

westward to the coast. On the South Umpqua River 

near its junction with Days Creek, east of Riddle, the 

subspecies ranges through 330 feet of beds comprising 

units 2-4 of the published section (Imlay and others, 

1959, p. 2775, 2782) of the Days Creek Formation. Its 

lowest occurrence in this section is only 65 feet above 

the highest occurrence of Buchia uncitoides (Pavlovr). 

Unless a disconformity is present, that 65 feet mrst 

correspond to the B. pacifica and B. keyserlingi beis 

of northwestern California.

Beds characterized by Buchia crassicoUis solida 

(Lahusen) have been found in western British Columbia in the Quatsino Sound area of Vancouver Island 

and in the Harrison Lake area (Jeletzky, 1965, p. 4V). 

At Quatsino Sound such beds rest unconformably on 

Middle Jurassic intrusive igneous rocks. At Harrison 

Lake they are underlain by volcanic rocks that in turn 

are underlain by beds containing Buchia pacifica 

Jeletzky (1965, fig. 4 on p. 65).

COMPARISONS OF AMMONITES WITH OTHER 

AMMONITE FAUNULES

The ammonite faunule of latest Jurassic (Tithonian) 

age in California and Oregon is dominated by genera 

that are characteristic of the Mediterranean (Tethyan) 

region and of South America as far south as Argentina 

but that are unknown in the Arctic region. Such gene-ra 

include Kossmatia, Parodontoceras, Substeueroceras, 

Proniceras, G-roebericerasl. , and Spiticeras. All of them 

are represented by species that closely resemble or are
B18 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

possibly identical with species in Mexico or in Argentina. None of them are known north of Oregon with 

the possible exception 011 Vancouver Island of one 

small crushed berriasellid ammonite that shows a little 

resemblance to immature forms of Siibsteueroceras 

(Jeletzky, 1965, p. 18, pi. 2, fig. 5). None are related 

even on the family level to ammonites of latest Jurassic 

age in northern Canada (Jeletzky, 1966, p. 3-23, 43).

The Tithonian of California is represented also by 

several specimens of Blanfordiceras in association with 

small Buchias that probably belong to B. piochii 

(Gabb). These were obtained at a spot very near beds 

characterized by B. aff. B. okensis (Pavlow) and should 

be of late Tithonian age. This occurrence is interesting 

paleogeographically because the genus hitherto has been 

found definitely only in India, Pakistan, Indonesia, 

and Madagascar in beds of Tithonian or probable 

Tithonian age and questionably in Argentina in beds 

of Berriasian age. The presence of Blanfordiceras in 

California, therefore, is far north of all other known 

occurrences.

Other ammonite genera present in the highest Jurassic beds in California and Oregon include Phylloceras 

and Lytoceras. These were once considered to be characteristic of the Mediterranean region because they are 

common in Jurassic beds of that region, become uncommon northward in central Europe, and are uncommon in the Arctic region of Eurasia (Ortmami, 1896, 

p. 265; Haug, 1907, p. 119; Spath, 1932, p. 151, 152). 

Both genera are now known, however, to be fairly 

common in Jurassic beds bordering the Pacific Ocean 

(Fleming, 1960, p. 267; Sato, 1962, p. 58; Imlay, 1953b, 

p. 59, 60; 1955, p. 78), and hence their presence in California and Oregon does not signify that they are of 

southerly origin. Rather, their absence in the Jurassic 

of the western interior of the United States (Imlay, 

1953a, p. 12), their scarcity in central Europe, and 

their abundance in lands bordering the Mediterranean 

Sea and the Pacific Ocean favors the suggestion made 

by Spath (1932, p. 151, 152) that they were pelagic 

organisms and were not adapted to live in the shallow 

epicontinental seas.

All the ammonites of Berriasian age in California 

and Oregon belong to genera and subgenera of distinct 

Mediterranean affinities. These include Spiticeras, S. 

(Negreliceras], S. (Kilianicerasl) , Neocosmoceras, and 

Protacanthodiscus. All species of these genera are similar to species in the Mediterranean region including 

Mexico. Some are also similar to species from Vancouver Island in western British Columbia (Jeletzky, 

1965, p. 33, pi. 11, figs. 2^t, 6, 7, pi. 12, figs. 5, 6), but

none are similar even generically to ammonites in the 

Arctic region of Canada (Jeletzky, 1964b, pis. 1-4) and 

northern Eurasia (Sachs and others, 1963, tables 7, 8). 

Comparisons with northern Alaska cannot be made because Berriasian ammonites have not yet been found 

there, except for one specimen of Phylloceras (Imlay, 

1961, p. 55, pi. 12) whose age is determined by its 

association with Buchia okensis (Pavlow). Likewise, 

comparisons with southern and southwestern Alaska 

cannot be made because of the lack of ammonites, 

although the presence of Buchia uncitoides (Pavlow) 

indicates that the Berriasian is represented there.

The ammonites of Valanginian age in California and 

Oregon, as discussed previously (Imlay, 1960, p. 181, 

182), bear strong affinities with those of the Mediterranean (Tethyan) region and some affinities also with 

ammonites of central and northern Eurasia Genera 

characteristic of the Mediterranean regior include 

Criocemtites, Olcostephanus^ Thurmanniceras, Neocomites, Sarasinella, KilianeUa, and Acanthodisvus. Genera characteristic of the Arctic region include Homolsomites and Tollia (Shulgina, 1965; Jeletzky, 19Mb, table 

1; 1965, fig. 2 opposite page 2; Sachs and others, 1963, 

tables 7, 8). Ammonites that range from the Mediterranean to the Arctic include Bochianites, Polyptychites, 

and Neocms'pedites; of these, the last two gerera listed 

are reported most commonly from central and northern 

Eurasia. Also, present in the Valanginian of the Pacific 

Coast are a few representatives of Phylloceras and 

Lytoceras, which, as previously discussed, are not necessarily of Mediterranean origin. It is evident, therefore, that the Valanginian ammonite fauna in California and Oregon contains an association of genera 

derived from both southerly and northerly directions 

but that the genera of Mediterranean affinities predominate.

In summation, in California and Oregon the ammonite genera of Tithonian and Berriasian ages are 

entirely of southern or Mediterranean origin except for 

Phylloceras and Lytoceras; the ammonites of Valanginian age are mostly of southern origin, but include 

two genera that are characteristic of the Arctic region 

and several genera that could have come from the 

Arctic region, the Mediterranean region, or areas in 

between.

These facts are significant from ecological and correlative viewpoints because the ammonites are associated 

with the pelecypod Buchia, which numerically is much 

more common than the ammonites and clearly is of 

northern derivation (Jeletzky, 1965, p. 57; Imlay, 1965, 

p. 1034). Furthermore, Buchia in California and Ore-
AMMONITES FROM THE BUG HI A ZONES

FIGURE 3. Index map of ammonite localities in the Buchia 

beds of southwestern Oregon. Numbers on map show 

positions of fossil localities given in table 2 and in locality 

descriptions.

___OREGON 

7" CALIFORNIA

Redding 

> O

TEHAMA

° 

Q5 Red

U n8

/-' | GLENN

( J ,-

\ \ COLUSA

( \^

\

'-K

>"NAPA\

CAS 28494 x 

\

\

.Sacramento / \ \-~^^Z~-\

( CCONTRA t

SAN FRANCISCO^T^^f'D^ ^ ^

20 30 40 50 MILES W* -txPAC unnumber, V^

FIGURE 4. Index map of ammonite localities in the Buchia 

beds of northwestern California. Rectangles numbered 5-8 

show areas covered by figures 5-8, which are detailed index 

maps of ammonite localities.

gon is represented by a succession of intergrading species that is nearly identical with a succession in western 

British Columbia (Jeletzky, 1965, p. IT-55) and contains some species in common with successions of 

Buchia in Alaska, northern Canada, Greenland, and 

northern Eurasia. Evidently the latest Jurassic and 

earliest Cretaceous succession of ammonites and Buchia 

in California and Oregon will be useful in correlating 

the diverse molluscaii assemblages of those ages in the 

Arctic and Mediterranean regions.

GEOGRAPHIC DISTRIBUTION

The occurrences of the Tithonian, Berriasian, and 

Valanginian ammonites from California and Oregon 

described herein are shown by State and locality in 

table 2 and in figures 3-8. Detailed descriptions of the 

individual localities are given in the following table. 

Abbreviations used include UC for the University of 

California Museum of Paleontology at Berkeley, GA S 

for the California Academy of Sciences, USNM for 

U.S. National Museum, and USGS Mesozoic loc. for 

U.S. Geological Survey Mesozoic locality.

R 8 W.

27

23

35

R. 7 W.

19

29

T. 26 N

2 MILES

FIGURE 5. Detailed index map of ammonite localities in we?tcentral part of the Colyear Springs quadrangle, California. 

Numbers on map show positions of fossil localities given in 

table 2 and in locality descriptions.
B20 JURASSIC AND CRETACEOUS BVCHIA ZONES IN CALIFORNIA AND OREGON

TABLE 2. Geographic distribution of ammonites in the uppermost Jurassic (Tithonian)

cf. S. (S.) MAKffiBurckhardt.-. __._.._.._. ..........................

jenkinsi ( Anderson) _ _ _ _ _ . ......

Neocomites cf. N. wichmanni Leanza- ..

cf. N. neocomiensis (d'Orbigny)

Kilianella crassiplicata (Stanton)......

cf . S. uhligi Spath.

Neocosmoceras euchrense Imlay and Jones, n. sp _ ..

tcrossi (Anderson) _ ................ ........... ...

Oregon

Douglas 

County

X

IM 

O

S

X

00

X

X 

X

Curry 

County

8 o

X

California

Tehama County

en

ID «

I

X

1

X

X

3

X

o

I I 1

i

X

1

X

1

6

X

X

6

X

I

X

§

S

N

X

en

X

X

C-l

I

,

X

S! 00

X

1

X

CAS unnumbered

X

1

X

X

1O

6

X

X

X

oo 10

X

X
AMMONITES FROM THE BUCHIA ZONES 

and Lower Cretaceous Buchia beds of northwestern California and southwestern Oregon

B21

C alifornia C ontinued

Tehama County Continued

c«

X

eo ft

--

O5

X

X

CAS unnumbered

v

X

I 

?i

v

X

1

-

X

X

S)

--

X

X

3>

o

s

--

X

X

o

-

X

» 

0

i

--

X

§

X

X

--

13

-- --

X

1

X

X

o 

3

X

S

X

X X

X

S

g

i

X

I I

00o>

t^ 13

1 

«

6 P 1

X

f»

05<! 

o 8 s

p

--

-

-

X

7

§

3

m<< 

O

ei

05

<1

O i

Glenn County

1

X

8

9 

S

8 

?

? 

o P

t05

<1

0

X

X

X

s

i

X

s

S3

s

X

I

"O i>« 

"O

i

u?

I

X

i

CAS 28037 near 

M2604A

X

i

s

1

s

Colusa 

County

S

IM

n

05

<)

O

X

Napa 

County

I

05

<

0

X

Con*,ra 

Costa 

Couity

Philadelphia Academy Sciences 

unnumbered

X

365-428 O 7C
B22 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

R.7 W.

22

- 27

x

\

~\

34

Fellow0

3

10

15

22

27

34

23

26

Af /

^x-iUjsL/'-x

CAS

35 

Hull

2

11

14

23

26

35

X 666

24

^^v 

/ 25

I

1

nnumbered

36

1003 x

1084

1

 P^ ~i-/^~ 1 ' 2

13

X UC-A-2921

24

25

36

' 1 ' \ '

R. 6 W.

19

fii'k'VKici

29558

30

29489x Oakes

31

6

X 29591

/ 

X-'Cooper 

V1085

7

9588 " M3 

xx

29589

o 18

Kelly

. X M4066

(' 9

CAS 28667

29505^*- ^

UC-A-2

Henderson

30 1001

31

"\ Lowrev ^--v^

 'f) ^

x ^_c^y

B-5091-5094

(

29 ^

J-\/

^( M3

/

/

/ M3092

 ^ /

V/

/

s^f O  ~~"^~^-^

1

(

M3082 28 

x XVI3084

x

083 X 1087

1009

33

v 1088 X UC-2605

n^Vilcox

X 109

> 29595, Ml 578

M3096 5 

5

s~~- ^ ~^~

8 295S

D61 (=1010 = 11 

29593X 29E

17

Ruff o

20

0B

339

4 M1577

x

29594

29597

6x ,<x XM305

)93)>r|\/|3060 

X29487 

98 9

^. 16 UC-B-

^ ^

21

art ^ '' ^

^^/

22

27

34

L ( = 2266) ( = M

3

 ll ' ~~ -J*^

8

10 

Shelton

5085

'%

\

22 ^

j-rartV-^

- - -

92^^ x - x,->CAS 33502 ( = M1580)

O CAS 144 28

( = 1095)

29

\_

 

33

_ Paskenta

6 1 5 11 4

27

34

^^^

Y

23

26

35

1579)

-O'lPftf-

"^-v^

\

11

14

23

-"^

~~ \ \

26

/" 35

y

1 r

T.

1.

1.

T

3 MILES

FIGTJEB 6. Detailed index map of ammonite localities in the Paskenta area, California. Numbers on map slow 

positions of fossil localities given in table 2 and in locality descriptions.
AMMONITES FROM THE BUCHIA ZONES

R. 6 W.

18

\

i Newville

29493

T. 22 N.

FIGUBE 7. Detailed index map of ammonite localities near 

Newrille, Calif. Numbers on map show positions of fossil 

localities given in table 2 and in locality descriptions.

Special attention is called to the fact that the descriptions of GAS Iocs. 28037 and 29694 as recorded by F. M. 

Anderson prior to 1945 are not in line with data shown 

on the more recently published topographic sheets of 

the Elk Creek and Paskenta quadrangles. The localities, when plotted 011 these quadrangles with reference 

to ranch houses, bridges, or natural features as described by Anderson, are- in different sections, or different parts of sections, from those described by 

Anderson. These differences apparently mean that 

Anderson did not have adequate base maps. Such a 

lack is shown especially on a map of the Paskenta area 

published by him in 1933 (Anderson, 1932, fig. 2 on 

p. 314) in which the positions of the ranch house are

R.7 W.

12

Grindstone^

1~3

24

25

36

1

12

R 6 W.

7

19

30

31

6

7

8 \\

 31

17

20

29

32

5

Elk

8

UC-B-5120 

M1574 

M2253 

M3030 

GAS 28037

M2605 " 

M2604A

21

28

10

M25« 15 

M2998

I

(

{

r

11

_^

23

26

I ~\ 

33 / 33/34 / 35

I / /

4

2286

Creek /

9°J

X V.M703 

A

,' 

10

2

"

T 21 N.

T. 20 N.

FIGUBE 8. Detailed index map of ammonite localities in the 

Elk Creek area, California. Num'bers on map show positions 

of fossil localities given in table 2 and in locality descriptions.

related to the drainage pattern as shown on the 1952 

Paskenta quadrangle, but are not so related to section 

lines. Accordingly, the locality descriptions published 

herein (unnumbered table) include revisions as well as 

the original descriptions.

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon

USGS Collector's field Nos. Localities of other 

Mesozoic Iocs. institutions

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

3351--------- 6761----_-__--_________________ Diller, J. S., and Storrs, James, 1905. On South Umpqua River Yz mile above

mouth of Days Creek, Douglas County, Oreg. Tithonian. Buchia uncito^des

zone. 

24702. __ _________ _ __ _ Rice, Claude, 1898?. From Wilson Creek near Riddle, Oreg. Valanginian.

3348___---___ 6738-__________________________ Diller, J. S., and Storrs, James, 1905. Mouth of Iron Mountain Creek on Cow

Creek, 1 mile north of Nichols station, Douglas County, Oreg. Berriasian. 

4390_________ S-9_--.________________________ Storrs, James, 1907. % mile below forks of Elk River, Curry County, O-eg.

Valanginian. 

2154 __ _ 5446- Diller, J. S., 1900. Elk River between the forks and the mouth of Blackberry

Creek, SE>i sec. 14, NWtf sec. 23, NE}£ sec. 22, T. 33 S., R. 13 W., Agness

15-min quad., Curry County, Oreg. Valanginian. 

2074__-_-_-._ 6015_-__ Diller, J. S., and Storrs, James, 1899. On beach north of mouth of Euchre

Creek, sec. 5, T. 35 S., R. 14 W., Port Orford quad., Curry County, O~eg.

Tithonian? and Berriasian. Buchia uncitoides and B. piochii zones. 

29616-------------_-______________-__ ______ Aalto, Kenneth, 1967. From northeast bank of Southeast flowing tributarj' of

Windy Creek, 1 mile N. 94° E. of Snow Camp Lookout, T. 37 S., R. 12 E.,

Collier Butte 15-min quad., Curry County, Oreg. Valanginian.
B24 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon Continued

USGS Collector's field Nos. Localities of other Collector, year of collection, description of locality, stratigraphic assignment, and age 

Mesozoiclocs. institutions

M2679-______ 64-JCS-32______________________ Jones, D. L., 1964. East slope of a small knoll on west bank of South Fork of

Cottonwood Creek at boundary line between sees. 2 and 11, 500 ft west of 

SE. cor. sec. 2, T. 26 N., R. 8 W., Colyear Springs 15-min quad., Tehama 

County, Calif.

M2680-______ 64-jCS-33______________________ Jones, D. L., 1964. East bank of Cottonwood Creek, 300 ft west and 650 ft

south of NE. cor. sec. 11, T. 26 N., R. 8 W., Colyear Springs 15-ru'n quad., 

Tehama County, Calif.

29557________ 67-jCS-4_______________________ Jones, D. L., 1967. North side of South Fork of Cottonwood Creek directly

north of junction with Quail Creek and 800 ft west of and 100-2CO ft stratigraphically below Mesozoic loc. 29556. Valanginian.

29556__ ______ 67-JCS-3 _____________________ Jones, D. L., 1967. North side of South Fork of Cottonwood Creek about 400 ft

due west of Mesozoic loc. 29555. Valanginian.

29555-_______ 67-jCS-2_______________________ Jones, D. L., 1967. North side of South Fork of Cottonwood Creel: at southwestend of hairpin loop, 1,000 ft east and 1,350 ft south of NW. cor. sec. 12, 

T. 26 N., R. 8 W., Colyear Springs 15-min quad., Tehama County, Calif. 

Valanginian. Probably Buchia keyserlingi zone.

29485- --_-___ 66-JIJ-5 _____________ _ _ _ _ _ Jones, D. L., and Imlay, R. W., 1966. South side of South Fork of Cottonwood

Creek at north end of hairpin loop, 1,350 ft east and 670 ft south of NW. 

cor. sec. 12, T. 26 N., R. 8 W., Colyear Springs quad., Tehama County, 

Calif. Valanginian.

M2040_ ______ 265____________________ __ _ Bailey, E. H., 1963. On Sunflower Trail on north bank of Red Bank Creek,

1,200 ft west and 600 ft south of NE. cor. sec. 20, T. 26 N., R. 7 W., Colyear 

Springs 15-min quad., Tehama County, Calif. Valanginian.

666__________ 2463- -_---_---_________________ Diller, J. S., 1889. On ridge about 3 miles directly west of the Lowrey Ranch

house. Probably in the north-central part of sec. 24, T. 25 N., R. 7 W., 

Tehama County, Calif. Tithonian. Probably from 6,000-7,000 ft below top 

of Buchia piochii zone.

M2025-______ 246____________________________ Bailey, E. H., 1963. Recollected by Imlay, R. W., 1965. North side of Middle

Fork of Elder Creek at spillway from a pond, 1,052 ft east ard 1,900 ft 

north of SW. cor. sec. 20, T. 25 N., R. 6 W., Colyear Springs 15-min quad., 

Tehama County, Calif. Berriasian. About 2,000 ft above base of Buchia 

uncitoides zone.

_____________________________ UC-B-5091 ___ Young, Gerald C., 1957. Middle Fork of Elder Creek, on south side, 10 ft east

of junction with small tributary from south, about 570 ft stratirraphically 

below a massive sandstone, SEtfNEtf SWJ4SEK sec. 19, T. 25 N., R. 6 W., 

Colyear Springs 15-min quad., Tehama County, Calif. Late Tithonian.

-----_..-_____________________ UC-B-5092____ Young, G. C., 1957. Middle Fork of Elder Creek, 40 ft east of junction with

small tributary from south, 550 ft below base of massive sandstone, SE>4NE>£ 

SW}£SE}£ sec. 19, T. 25 N., R. 6 W., Colyear Springs 15-min quad., Tehama 

Calif. Late Tithonian. Buchia aff. B. okensis (Pavlow) zone.

_____________________________ UC-B-5093_ _ _ _ Young, G. C., 1957. Middle Fork of Elder Creek, about 105 ft downstream from

junction with small tributary from south, 80 ft stratigraphically above

UC-B-5091, and 490 ft stratigraphically below a massive sandstone, SEH 

NEtf SW%SE>£ sec. 19^ T. 25 N., R. 6 W., Colyear Springs 15-min quad.,

Tehama County, Calif. Late Tithonian.

____________________ _ _ _ UC-B-5094__ Young, G. C., 1957. About 205 ft downstream from point where tributary

enters the Middle Fork of Elder Creek from south, 105 ft stratigraphically 

above UC-B-5093 SE}£NE}4 SWJ4SEK sec. 19, T. 25 N., R. 6 W., Colyear 

Springs 15-min quad., Tehama County, Calif. Late Tithonian. Trom upper 

few hundred feet of Jurassic sequence.

M2024_ ______ 244_____________ ___ Bailey, E. H., 1963. South side of Middle Fork of Elder Creek, 1,000 ft east

and 450 ft south of NW. cor. sec. 30, T. 25 N., R. 6 W., Colyear Springs 

15-min quad., Tehama County, Calif. Tithonian. About 2,100 ft below top 

of Buchia piochii zone.

29558-_______ 67-JCS-8_ ___________________ _ Jones, D. L., 1967. Middle Fork of Elder Creek, 450 ft E. and 300 ft south of

NW. cor. sec. 30, T. 25 N., R. 6 W., Paskenta 15-min quad., Tehama County, 

Calif. Tithonian. About 2,300 ft below top of Buchia piochii zone.

29489-_______ 66-JIJ-9_____________________ Jones, D. L., and Imlay, R. W., 1966. From thin interbeds of graywacke and

mudstone containing limestone concretions exposed in creek bed 300 ft 

southwest of Oakes Ranch house (abandoned), 2,500 ft west of SE. cor. and 

just north of south line of sec. 30, T. 25 N., R. 6 W., Paskenta 15-min quad., 

Tehama County, Calif. Late Tithonian. Buchia aff. B. okensis (Pavlow) zone.

M3082_ ______ 65-JCS-30-____________ _____ Jones, D. L., 1965. South side of road from Paskenta to Red Bluff, 800 ft

southeast of BM 870 near South Fork of Elder Creek, 400 ft east and 2,000 

ft south of NW. cor. sec. 28, T. 25 N., R. 6 W., Paskenta 15-min quad., 

Tehama County, Calif. Valanginian. Buchia keyserlingi zone.

M3083_______ 65-JCS-31_____________________ Jones, D. L., 1965. On south side of road to Red Bluff, 1,100 ft east and 1,750

ft north of SW. cor. sec. 28, T. 25 N., R. 6 W. Paskenta 15-min quad.,

, __ A Tehama County, Calif. Valanginian. Buchia keyserlingi zone.

M3084.______ 65-JCS-32.____________________ Jones, D. L., 1965. On top of small knoll 600 ft north of road and £00 ft northeast of Mesozoic loc. M3083, 1,700 ft east and 2,150 ft south cf NW. cor 

sec. 28, T. 25 N., R. 6 W., Paskenta 15-min quad., Tehama County, Oalit. 

Valanginian. Buchia keyserlingi zone.
AMMONITES FROM THE BUCHIA ZONES B25

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon Continued

USGS 

Mesozoic Iocs.

Collector's field Nos. Localities of other 

institutions

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

1009(=1087)__ 15--____--_____________-_______ Diller, J. S. and Storrs, James, 1893. About halfway between the Lowrey and

Wilcox ranch houses, on hill about 500 ft east of road in south-central part 

of sec. 28, T. 27 N., R. 6 W., Paskenta 15-min quad., Tehama County, 

Calif. Valanginian. Buchia keyserlingi zone. 

___--_____--_________---_____ C AS un- Anderson, F. M., and Rist, R. L., 1937(?). Middle Fork of Elder Creek al nut

numbered. 1 mile east of the Kleinsorg chromite mine and 1 mile south of the Soledad 

ranch house, sec. 26, T. 25 N., R. 7 W., Paskenta 15-min quad., Tehama 

County, Calif. Tithonian. 

M3092_ ______ 65-JCS-40. _________________ Jones, D. L., 1965. South Fork of Elder Creek, 2,400 ft east and 2,500 ft south

of NW. cor. sec. 32, T. 25 N., R. 6 W., Paskenta 15-min quad., Tehama 

County, Calif. Berriasian. Near base of upper third of Buchia uncitoides zone 

which is about 5,500 ft thick. 

1088 _________ 91 _____________________________ Diller, J. S., Stanton, T. W., and Storrs, James, 1893. About % mile east of road

and % mile north of the Wilcox Ranch house, north-central part of sec 33, 

T. 25 N., R. 6 W., Tehama County, Calif. Valanginian. Near base of Buchia 

keyserlingi zone. 

_____________________________ UC-2605- ______ P_ ______ F. L., year unknown. About 2% miles south of Lowrey's house, l/z mile

north of Wilcox's house,, and 800 ft east of road. Probably about same place 

as USGS Mesozoic loc. 1088, Tehama County, Calif. Valanginian. 

1003_________________________________________ Same as loc. 1084.

1084_________ 86_____________________________ Storrs, James, and Stanton, T.W., 1893. From sandstone 1 mile northwest of

Cooper's Ranch house. Probably in NE% sec. 1, T. 24 N., R. 7 W., Paskenta 

15-min quad., Tehama County, Calif. Same as loc. 1003. Tithonian. Probably 

2,000-3,000 feet below the top of the Buchia piochii zone. 

29591 _ _______ I67-10-23B_____________________ Imlay, R. W. and Ross, Wm. O., 1967. About }_mile north-northeast of Ray

Borellos ranch house (formerly Cooper's), about 150 ft east of road, and 200 

ft stratigraphically below conglomerate on east side of valley. South-certral 

part of SEJ4NWH sec. 6, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama 

County, Calif. Late Tithonian. Probably near middle of Buchia aff. B. 

okensis zone. 

29592________ I67-10-23C_____________________ Imlay, R. W., 1967. About % mile south of loc. 29591 at same stratigrar»hic

position, north-central part NEKSWJ4 sec. 6, T. 24 N., R. 6 W., Paskenta 

15-min quad., Tehama County, Calif. Late Tithonian. 

1085_ ________ 87_____________________________ Storrs, James, and Stanton, T. W., 1893. Near South Fork of Elder Creek just

west of Cooper's house in NE. cor. SWtfSWtf sec. 6, T. 24 N., R. 6 W., 

Paskenta 15-min quad., Tehama County, Calif. Late Tithonian. Near ton of 

Buchia piochii zone. 

M3096_ ______ 65-JCS-41_ ___________________ Jones, D. L., 1965. East bank of South Fork of Elder Creek, 300 ft east and

2,000 ft south of NW. cor. sec. 5, T. 24 N., R. 6 W., Paskenta 15-min qu^d., 

Tehama County, Calif. Berriasian. A little below middle of Buchia uncitoides zone which is about 5,500 ft thick. 

5339_________ 24_____________________________ Storrs, James, 1908. > mile west of Wilcox ranch house in NW# sec. 4, T. 24

N., R. 6 W., Tehama County, Calif. Valanginian. Near middle of Buchia 

pacifica zone. 

_____________________________ GAS un- Anderson, F. M., about 1930. About 5 miles north of Paskenta and } _ mile south

numbered. of the Wilcox (now Schuchart) ranch house near center of NWK sec. 4, T. 24 

N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Probably sr.me 

place as Mesozoic loc. 29595. Valanginian. At top of Buchia pacifica zone. 

29595_____.__ I67-10-17B_____________________ Imlay, R. W. and Ross, Wm. O., 1967. Near top of hill on south slope, 1,7CO ft

east and 1,750 ft south of NW cor. sec. 4, T. 24 N., R. 6 W., Paskenta 15-min

tnn ^ quad., Tehama County, Calif. Valanginian. At top of Buchia pacifica zone. 

1091_________ 94_____________________________ Stanton, T. W., Diller, J. S., and Storrs, James, 1893. About % mile eas*, of

Wilcox Ranch house in NEtfNWtfNEtf sec. 4, T. 24 N., R. 6 W., Tehr.ma 

County, Calif. Same as Iocs. 2266 and M1579. Valanginian. About 1,550 ft 

above base of Buchia keyserlingi zone. 

??T?^-- - 536 -------------------------- Stanton, T. W., 1900. Same as loc. 1091.

M1579_______ 62-P-4____.____________________ Jones, D. L., and Imlay, R. W., 1962. North of north tributary to Mill Creek,

1,200 ft west and 500 ft south of NE. cor. sec. 4, T. 24 N., R. 6 W., Paskenta

15-min quad., Tehama County, Calif. Same as USGS Mesozoic loc. 1091

and 2266. Valanginian. About 1,550 ft above base of Buchia keyserlingi zone.

M1577_______ 62-P-2____,____________________ Jones, D. L., and Imlay, R. W., 1962. Near north tributary to Mill Creek,

1,600 ft west and 1,900 ft south of NE. cor. sec. 4, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Valanginian. About 1,250 ft 

,,., __0 _,.. above base of Buchia keyserlingi zone. 

M1578____.__ 62-P-3___________________._.___ jones, D. L., and Imlay, R. W., 1962. Near north tributary to Mill Creek,

1,800 ft west and 1,900 ft south of NE. cor. sec. 4, T. 24 N., R. 6 W., Faskenta 15-min quad., Tehama County, Calif. Valanginian. About l,07f ft 

on _ n . T above base of Buchia keyserlingi zone. 

29594._______ I-67-10-17A____________________ Ross, W. O., and Imlay, R. W., 1967. Near top of hill on south slope 1,800

ft east and 1,700 ft north of SW. cor. sec. 4, T. 24 N., R. 6 W., Paskenta 

15-min quad., Tehama County, Calif. Valanginian. At top of Buchia pacific 

zone.
£26 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon Continued

USGS Collector's field Nos. Localities of other Collector, year of collection, description of locality, stratigraphic assignment, and age 

Mesozoic Iocs. institutions

29588.--_-_-- I67-10-13A _______ _ _________ Imlay, R. W., 1967. Maupin Flat, east-central part NWJiSWtf sec. 7, T. 24

N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Late Tithonian. 

Near base of zone of Buchia aff. B. okensis.

29589._______ I67-10-13B_____________________ Ross, W. O., 1967. Maupin Flat, a little southeast and about 15C ft higher

stratigraphically than loc. 29588. SEJiNW>£SW}4 sec . 7, T. 24 N., R. 6 W., 

Paskenta 15-min quad., Tehama County, Calif. Late Tithonian. Buchia 

aff. B. okensis zone.

29597._______ I67-10-20C.__________________ Imlay, R. W., 1967. On west slope of hill about 200 ft east of dry gulch that

drains north into Mill Creek, 1,250 ft east and 1,050 ft south of NW. cor. 

sec. 9, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. 

Valanginian. About 200 ft below top of Buchia pacifica zone.

29596________ I67-10-20A_ ____________________ Ross, W. O., 1967. About 750 ft east and 1,650 ft south of NW. cor. sec. 9,

T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Valanginian. Near base of upper third of Buchia pacifica zone.

1010____._.__ 16 and 17_____--__----___----_- Diller, J. S., and Storrs, James, 1893. About tf mile northwest of Shelton's

Ranch houses in NW}£ sec. 9, T. 24 N., R. 6 W., Tehama County, Calif. 

Valanginian.

M3061_ ______ 65-I-4_ ________________________ Imlay, R. W., 1965. Top of knoll at elevation of 1,157 ft, about % mile south

of "Mill Creek, 1,500 ft east and 2,400 ft south of NW. cor. sec. 9, T. 24 N., 

R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Valanginian. At 

top of Buchia pacifica zone. Same as USGS Mesozoic Iocs. 1010 and 1093.

1093-________ Sta 96_-___-_______--_____-___- Diller, J. S. and Storrs, James, 1893. About }£ mile northwest of Shelton's

ranch house in NW}£ sec. 9, T. 24 N., R. 6 W., Tehama County, Calif. 

Valanginian. Same spot as Mesozoic loc. 1010 and M3061.

M3060_______ 65-I-3---_--_____-----___-_-_-- Imlay, R. W., 1965. Just south of crest of ridge about }_ mile south of Mill

Creek and at base of northeast end of a prominent knoll, 1,750 f*; east and 

2,000 ft south of NW. cor. sec. 9, T. 24 N., R. 6 W., Paskenta 15-min quad., 

Tehama County, Calif. Valanginian. In lower 200 ft of Buchia keyserlingi 

zone.

M3059_ ______ 65-1-2. _ _______________________ Imlay, R. W., 1965. On hill >. mile south of Mill Creek, 2,200 ft east and 2,000

ft south of NW. cor. sec. 9, T. 24 N., R. 6 W., Paskenta 15-min quad., 

Tehama County, Calif. Valanginian. About 450 ft above base of Buchia 

keyserlingi zone.

M3058-______ 65-1-1.________________________ Imlay, R. W., 1965. On hill % mile south of Mill Creek, 1,900 ft west and 2,000

ft south of NE. cor. sec. 9, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama 

County, Calif. Valanginian. About 1,530 ft above base of Buchia keyserlingi 

zone.

29593__._____ I67-10-16B_____________________ Ross, W. O. and Imlay, R. W., 1967. In gully 400 ft north and 1,400 ft west

of SE. cor. sec. 8, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama County, 

Calif. Valanginian. In lower 150 ft of the Buchia pacifica zone.

29598._______ I67-10-20D-___________________ Ross, W. O., 1967. About 500 ft west and 1,700 ft north of SE. cor. sec. 8, T.

24 N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. Valanginian. 

About top of lower third of Buchia pacifica zone.

29487._______ 66-JIJ-7_______________________ Jones, D. L., 1966. About % mile south of Mill Creek and K mile south of loc.

M3061, 1,150 ft east and 2,000 ft north of SW. cor. sec. 9, T. 24 N., R. 6 W., 

Paskenta 15-min quad., Tehama County, Calif. Valanginian. Top of Buchia 

pacifica zone.

_____________________________ TJC-A-2921 _ _ _ _ Rist, R. L., 1937. In west-central part of sec. 13, T. 24 N., R. 7 W., 950 ft west

of road to Fellow's Place just over saddle in first ridge, Paskenta 15-min 

quad., Tehama County, Calif. Tithonian. About 4,000 ft, above fault contact 

of Jurassic Bwc/iia-bearing beds with Franciscan rocks and about 5,000 ft 

below top of B. pibchii zone.

_____________________________ UC-B-5085- _ _ _ Young, Gerald C., 1957. In tributary to Nevada Creek, NWtfNEtfNWJ_SEtf

sec. 16, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehama County, Calif. 

Valanginian. About 2,450 ft stratigraphically above base of Buchia keyserlingi beds.

M4066-______ 66-JBP-15.____________________ Jones, D. L. and Bailey, E. H., 1966., 500 ft west of road to Maupin Flat,

2,500 ft east and 1,700 ft south of NW. cor. sec. 19, T. 24 N., R. 6 W., 

Paskenta 15-min quad., Tehama County, Calif. Berriasian. About 1,300 ft 

above base of Buchia uncitoides zone which is about 5,500 ft thick.

_____________________________ GAS 28667.____ Taff, J. A. and Cross, C. M., 1936. From McCarty Creek, south side of SE}4

sec. 19, T. 24 N., R. 6 W., Mount Diablo meridian, Tehama County, Calif. 

Berriasian? 

29505._______ PL1599-_______________________ Warren, John, 1965. On McCarty Creek, 1,600 ft west and 550 ft south of

NE. cor. sec. 30, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehami. County, 

Calif. Berriasian. About base of upper third of Buchia uncitoides zone and 

about 2,000 ft below base of B. pacifica zone. 

_____________________________ TJC-A-2925_ _ _ _ Rist, R. L., 1937. McCarty Creek, 625 ft west of wooden bridge between Burt's

and Henderson's ranch houses, NWK sec. 29, T. 24 N., R. 6 W., Paskenta, 

15-min quad., Tehama County, Calif. Valanginian. About 500 ft above base 

of Buchia pacifica zone.
AMMONITES FROM THE BUCHIA ZONES B27 

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon Continued

US GS Collector's field Nos. Localities of other 

Mesozoic Iocs. institutions

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

1001--------- 6 and 7__-___-__-_----_----____ Diller, J. S., and Storrs, James, 1893. % mile east of Henderson's house on

upper road leading from Paskenta to Lowrey's Ranch. NWJ4 sec. 29, T.

24 N., R. 6 W., Tehama County, Calif. Valanginian. Middle of Buchia

7)(tciiico> zone* 

1095--------- 98_-___-___-___-----_---:----- Diller, J. S. and Storrs, James, 1893. Same as loc. 1001.

_____________________________ CAS 144_______ Collector unknown. From south bank of McCarty Creek opposite Burt's

Ranch house in NE# sec. 29, T. 24 N., R. 6 W., Tehama County, Calif.

Valanginian. Buchia keyserlingi zone. 

__ __ ____-__________---__-_ CAS 33502.__._ Anderson, F. M., about 1930. 1,200 ft southeast of Burt's Ranch House in

McCarty Creek in NEK sec. 29, T. 24 N., R. 6 W., Tehama County, Crlif.

Valanginian. Buchia keyserlingi zone. 

M1580_ ______ 62-P-5_______________________ Jones, D. L. and Iinlay, R. W., 1962. McCarty Creek, 300 ft west and 1,£OT ft

south of NE. cor. sec. 29, T. 24 N., R. 6 W., Paskenta 15-min quad., Tehsma

County, Calif. Valanginian. About 1,000 ft above base of Buchia keyserlingi

zone. 

29493_____-__ 66-JIJ-13________-__--_________ Jones, D. L. and Imlay, R. W., 1966. From unnamed eastern tributary of

Heifer Camp Creek, }i mile above junction with the North Fork of Stony

Creek, 250 ft east and 1,400 ft north of SW. cor. sec. 3, T. 22 N., R. 6 W.,

Paskenta 15-min quad., Glenn County, Calif. Tithonian. Within 1,000 ft

of the top of the Buchia piochii zone. 

M4053------- 66-JBP-4a_________________ Jones, D. L. and Bailey, E. H., 1966. On Heifer Camp Creek, 850 ft east and

1,150 ft north of SW. cor. sec. 9, T. 22 N., R. 6 W., Paskenta 15-min quM.,

Glenn County, Calif. Tithonian. About 5,000 ft below top of Buchia piochii

zone.

-___-_--_---________--_______ UC-B-5120__ Dondanville, Richard F., 1957. Watson Creek, 320 ft east of bridge on road

from Elk Creek to Chrome and 430 ft north of a small cemetery, NWJ4SEJ4 

NE^NEK sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn County, 

Calif. Late Tithonian.

-_____-_--______-__-_________ CAS 28037-_-_- Anderson, F. M. and Jenkins, H. O. 1934. Also, Anderson, F. M., Taff, J. A.,

and Cross, C. M., 1936. Recorded in Calif. Acad. Sci. locality book as 6^ 

miles north of Window bridge in SEtfSWJi sec. 10, T. 21 N., R. 6 W., 

Mount Diablo meridian, western Glenn County, Calif. The fossils were 

obtained, however, mostly from 400 ft of beds exposed on and near Watson 

Creek east of bridge on road from Elk Creek to Newville (Anderson, If45, 

p. 942). This locality in the Elk Creek quadrangle (1957 ed.) is in the 

NEJ4NEK sec. 16, T. 21 N., R. 6 W., or about % mile west-southwest of the 

location given in the record book. Late Tithonian. Upper 400-500 ft of Jurassic 

beds.

M1574___.___ 62-EC-l_______________________ Jones, D. L., and Imlay, R. W., 1962. On Watson Creek 550ft west and 80? ft

south of NE. cor. sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Gbnn 

County, Calif. Late Tithonian. About same stratigraphic position as M2"53 

and UC-B-5120.

M2253---_---_--__---______________________ Jones, D. L., 1964. On Watson Creek northeast of road, 500 ft northwest of

cemetery, 600 ft west and 700 ft south of NE. cor. sec. 16, T. 21 N., R. 6 W., 

Elk Creek 15-min quad., Glenn County, Calif. Late Tithonian. Buchia aff. 

B. okensis zone.

M3030_______ 65-W-7________________________ Jones, D. L., 1965. On Watson Creek 293 ft southeast of bridge which is 1,100

ft west and 800 ft south of NE. cor. sec. 16, T. 21 N., R. 6 W., Elk Cr?ek 

15-min quad., Glenn County, Calif. Late Tithonian. Buchia aff. B. okensis 

zone.

M1575_______ 62-EC-2_______________________ Jones, D. L., and Imlay, R. W., 1962. Just north of junction of Watson Creek

and Grindstone Creek, 900 ft east and 1,400 ft south of NW. cor. sec. 15, 

T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn County, Calif. Valanginian.

M2605-______ Grindstone ________________ Jones, D. L., 1964. On south bank of Grindstone Creek, 775 ft west of east

64-12. line of sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn County,

Calif. Tithonian. Within a few feet of top of Buchia piochii zone just below 

zone of B. aff. B. okensis.

M2599__-____ Grindstone ________________ Jones, D. L., 1964. On south bank of Grindstone Creek, 450 ft west of east

64-6. line of Sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn County,

Calif. Late Tithonian. About base of upper third of Buchia aff. B. okensis 

zone which is 450 ft thick.

-----___.____________________ CAS near Anderson, F. M., year unknown. From 1,200 ft west of iron bridge across

28037. Grindstone Creek. Probably near line of sees. 15 and 16, T. 21 N., R. 6 W., 

^ Elk Creek 15-min quad., Glenn County, Calif. Tithonian or Berriasian. 

MJb04A______ Grindstone ________________ Jones, D. L., 1964. On south bank of Grindstone Creek, 560 ft west of east

64-11A. line of sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn Courty, 

/-I Calif. Late Tithonian. A little below middle of Buchia aff. B. okensis zone. 

_..._ Grindstone 64-5---______________ Jones, D. L., 1964. On south bank of Grindstone Creek, 300 ft west of east

line of sec. 16, T. 21 N., R. 6 W., Elk Creek 15-min quad., Glenn County, 

Calif. Berriasian. Within a few feet of base of Buchia uncito>'des zone. 

___.______________ _ ___________ Chuber, Stewart, 1957 or 1958. 2,050ft east and 500ft south of NW. cor. sec. 3,

T. 20 N., R. 6 W., Elk Creek 15-min quad., Glenn County, Calif. Valanginian. Buchia pacifica zone.
B28 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Descriptions of some Upper Jurassic and Lower Cretaceous fossil localities in northwestern California and southwestern Oregon Continued

USGS Collector's field Nos. Localities of other 

Mesozoic Iocs. institutions

Collector, year of collection, description of locality, stratigraphic assignment, and a-*e

2286. 554.

29612-_______ RWS-65-23.

_______________ Stanton, T. W., 1900. On east bank of Stony Creek about % mile northeast of

town of Elk Creek in SW. cor. sec. 3, T. 20 N., R. 6 W., Glenn County, 

Calif. Berriasian. From 425 ft of greenish-gray sandstone. Buchia uncitoides 

zone. 

________________ Rich, E. I., 1965. From sandstone bed in Bear Creek near culvert across road,

1J. miles north of turnoff to Wilbur Springs, 100 ft west and 2,400 ft south 

of NE. cor. sec. 16, T. 14 N., R. 5 W., Wilbur Springs 15-min quad., Colusa 

County, Calif. Valanginian. 

GAS 28842_____ Taflf, J. A. and Cross, C. M., 1937. Limestone ledges in gully 50-100 ft east of

Bear Creek road, 1 mile north of Wilbur Springs bridge and 1% mfes above 

mouth of Sulphur Creek, SW. cor. sec. 15, T. 14 N., R. 5 W., Mount Diablo 

meridian, Colusa County, Calif. Tithonian? 

GAS 28494_____ Griffith, Mr., 1935. From an oil prospect tunnel near highway in bluff on east

side of Capell Creek, near center of east half of sec. 29, T. 8 N., R. 3 W-, 

Mount Diablo meridian, Napa County, Calif. Tithonian.

Philadelphia Gabb, W. M., 1860? Bagley Creek near Mount Diablo, Contra Costa County, 

Academy Calif. 

Sciences 

unnumbered.

SYSTEMATIC DESCRIPTIONS

Family PHYLLOCERATIDAE Zittel, 1884 

Genus PHYLLOCERAS Suess, 1865

Phylloceras knoxvillense Stanton 

Plate 2, figures 4-11

Phylloceras knoxvillcnsc Stanton, 1896, U.S. Geol. Survey Bull.

133, p. 72, pi. 14, figs. 1-3 (not fig. 4). [Imprint 1895.1 

PhyUoccras knoxvillense Stanton. Anderson, 1945, Geol. Soc.

America Bull., v. 56, p. 976, pi. 11, fig. 5. 

Phylloceras capellcnsc Anderson, 1945, idem, p. 977, pi. 4, fig. 8.

This species is characterized by having very fine, 

closely spaced, gently flexuous ribs that are extremely 

fine and dense near the umbilicus but coarsen a little 

ventrally and on the venter are slightly wider than the 

interspaces. The shell also bears faint radial folds that 

become stronger adorally. The internal mold bears 

pronounced constrictions at diameters as much as TO 

millimeters.

The holotype is entirely septate and has a diphyllic 

first lateral saddle and a triphyllic second lateral saddle (Stanton, 1895, pi. 14, fig. 3). At a maximum 

diameter of 112 mm, its whorl height is 66 mm and its 

whorl thickness is 34 mm. Associated fragments indicate that the species attained a much larger size and 

developed fairly strong radial folds.

The assignment of this species to Phylloceras rather 

than C alliphylloceras is based on the presence of radial 

folds and a triphyllic second lateral saddle.

Types. Holotype, USNM 23083; hypotype, USNM 

158803; hypotype, CAS 8716 and 8735.

Occurrences. In California at USGS Mesozoic Iocs. 

1084 (equals 1003), 29558, and 29589 and CAS Iocs. 

28037 and 28494. In Oregon the species is represented

at Mesozoic loc. 3351. The holotype and the specimen 

from Oregon are associated with Buchia piochii 

(Gabb). The holotype was obtained, along vith the 

holotype of Parodontoceras storrsi (Stanton), several 

thousand feet below the top of the range of B. piochii. 

The plesiotype figured by Anderson (1945, pi. 11, fig. 

5) was obtained at CAS loc. 28037 near the top of 

Jurassic and probably above the range of B. piochii.

Phylloceras glennense Anderson 

Plate 1, figures 9, 10

Phylloceras glcnnensc Anderson, 1945, Geol. Soc. America Bull., 

v. 56, p. 976, pi. 11, figs. 1, 2.

This species, judging by the holotype, differs from 

P. knoxmlleme Stanton by having a stouter whorl 

section and by its ribs being coarser, sparser, more 

flexuous, and grouped in more prominent radial folds. 

It differs also, according to Anderson (1945, p. 976), 

by a lack of constrictions. This reported difference is 

questioned, however, because constrictions in Phylloceras are confined to the internal mold, which is not 

known on P. glennense Anderson.

P. glennense Anderson shows some reseml^ance to 

P. appenmicum Canavari in Burckhardt (1906, p. 106, 

pi. 28) from beds of early Tithonian age in Mexico 

but lacks strong folds on the lower parts of its flanks.

Type. Holotype, CAS 8720.

Occurrence. In California at CAS loc. 28037.

Phylloceras? contrarium Imlay and Jones, n. sp. 

Plate I, figures 1-8

This species is represented by five small septate 

specimens and by one large fragment of which less than
AMMONITES FROM THE BUG HI A ZONES P29

half is septate. Some shell material is preserved on all 

the specimens.

The shell is highly involute and compressed. The 

small specimens are elliptical in section, much higher 

than wide, and attain their greatest thickness a little 

below and middle of the flanks. The large specimen is 

subtrapezoidal in section and attains its greatest thickness at about the top of the lower fourth of the flanks. 

The flanks slope gently to the umbilicus and to the 

venter, which is narrowly arched. The body chamber 

is possibly partly represented by the adoral part of the 

largest specimen.

The small specimens bear very fine ribs that are faint 

near the umbilicus and that are slightly stronger ventrally. They trend almost radially near the umbilicus, 

curve strongly forward on the lower third of the flanks, 

recurve backward gradually on the middle third of the 

flanks, and then curve backward more strongly on the 

upper third of the flanks and on the venter. The ribs 

on the venter are distinctly arched backward or adapically. In addition, the flanks, near their middle, bear 

faint widely separated forwardly arched folds that 

either fade out high on the flanks or pass into some 

of the ribs on the venter. Constrictions are not present.

The largest specimen bears broad, faint, rather closely spaced flexuous ribs that likewise arch adapically on 

the venter. In addition, some broad, low, widely separated folds are present on the middle of the flanks. 

The rib arrangement, therefore, is the same as on the 

small specimens.

The specimen shown on. plate 1, figures 1-3, at a 

diameter of 51 mm has a whorl height of 34 mm and 

a whorl thickness of 19 mm.

The suture line, as exposed on one immature specimen, has tetraphyllic first and second lateral saddles.

This species is difficult to place generically. The 

absence of constrictions shows that it belongs in the 

subfamily Phylloceratinae rather than in the Calliphylloceratinae. The presence of folds on the flanks favors 

an assignment to Phyttocems, but the presence of tetraphyllic saddles is against such an assignment. The 

adapically arched ribs on the venter is not characteristic of any genus of the Phylloceratinae but is possibly 

only a specific characteristic.

Types. Holotype, USNM 158804; paratypes, 

USNM 158805-158807.

Occurrences. In California at USGS Mesozoic Iocs. 

M2605, M4053, 29489, and 29493. The species is associated with Buchia piochii (Gabb) at all localities except 29489, where it is associated with a Jurassic variant of B. okensis (Pavlow).

Family LYTOCERATIDAE Neymayr, 1875 

Genus LYTOCERAS Suess, 1865

Lytoceras colusaense (Anderson) 

Plate 2, figures 1-3

Atilacospliinctes'! colusaensis Anderson, 1945, Geol. Soc. America

Bull., v. 45, p. 980, pi. 13, figs. 1, 2. 

ILytoceras aff. L. Uebifji (Oppel). Anderson, 1945, idem, p. 977,

pi. 14, fig. 1. 

ILytoccras aff. L. exoticum Oppel. Anderson, 1945, idem, p. 977,

pi. 14, fig. 2.

The genus Lytoceras is represented by a few septate 

fragments from the highest Jurassic beds exposed on 

the west side of the Sacramento Valley. One of the 

fragments, named Aulacosphinctes ? colusaensis Anderson (1945, p. 980, pi. 13, figs. 1, 2), is assignee1 to 

Lytoceras because of the presence of radially trending 

crinkled growth lines that are characteristic of the 

genus. Other fragments include Lytoceras aff. L. liebigi 

Oppel of Anderson (1945, p. 977, pi. 14, fig. 1) and 

L. aff. L. exoticum Oppel of Anderson (1945, p. 977, 

pi. 14, fig. 2). Of these, the last named consists of two 

small whorls that bear very fine and dense growth 

lines. L. aff. L. liebigi Oppel consists of one mediumsized septate whorl whose adoral end bears widely 

spaced fine lines as on L. colusaense (Anderson) and 

whose adapical end bears fine, dense lines, as on L. cf. 

L. exoticum Oppel. These resemblances suggest that 

only a single species is represented by the three specimens described by Anderson. Nonetheless, the fragmentary condition of the three specimens precludes a 

definite specific diagnosis, or even comparisons vdtli 

such early Cretaceous (Neocomian) species as Lytoceras aulaeum Anderson (1938, p. 146, pi. 14, figs. 1-4; 

Stanton, 1895, pi. 13, fig. 11; Imlay, 1960, p. 195) and 

L. saturnale Anderson (1945, p. 145, pi. 13, fig. 1; Imlay, 1960, p. 195).

Type. Holotype, CAS 10446.

Occurrences. L. colusaense (Anderson) is from CAS 

loc. 28842. L. aff. L. liebigi Oppel and L. aff. L. exoticum are from CAS loc, 28037. Other fragments of Lytoceras have been found near the top of the Jurassic sequence at USGS Mesozoic Iocs. M1574, M2253, and 

M2604A, which are at or near CAS loc. 28037 and at 

TIC loc. B-5092. L. colusaense (Anderson) is probably 

represented at USGS Mesozoic loc. 29588 and UC loc. 

B-5093 near the top of the Jurassic.

365-428 O 7C
B30 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Family BOCHIANITIDAE Spath, 1922 

Genus BOCHIANITES Lory, 1898

Bochianites? glennensis Anderson 

Plate 1, figures 11, 12

Bochianites sp. Hanna and Hertlein, 1941, California Div. Mines

Bull. 118, p. 168, fig. 22 on p. 169. 

Bochianites glennensis Anderson, 1945, Geol. Soc. America Bull.,

v. 56, p. 984, pi. 7, fig. 2.

This species as based on the holotype has a nearly 

straight shaft, an ovate cross section, and weak to 

moderately strong annular ribs that become slightly 

stronger ventrally, incline forward on the flanks, and 

cross the venter transversely without reduction in 

strength.

In lateral view this species appears to be a typical 

representative of Bochianites^ but the ribbing on its 

venter differs markedly by being transverse instead of 

projecting strongly forward. It differs from Protancyloceras in the same manner but also is much straighter 

and lacks a ventral furrow. In regard to ventral ribbing it resembles Hamulina^ rosariensis Imlay (1942, 

p. 1457, pi. 9, figs. 1-11, pi. 12, fig. 1), the type species 

of Vinalesphinctes (Thieuloy, 1966, p. 287, fig. 2 on p. 

288) from middle Tithonian beds in Cuba. It differs 

from that species, however, by being much larger and 

by having finer, less regular, and more strongly inclined ribbing.

One possibility concerning the generic status of B. ? 

glennensis Anderson is that it actually was collected 

from a different locality than reported and represents 

some Cretaceous ptychoceratid such as Anahamulina 

of middle Hauterivian to Barremian age. Such a possibility is favored by the presence of a weak constriction that is most pronounced on the venter. The species 

differs from A. wilcoxi Imlay (1960, p. 200, pi. 25, figs. 

2, 56) from Hauterivian beds in California by having 

coarser ribbing and an elliptical instead of a circular 

whorl section. Comparable coarsely ribbed species of 

Anahamulina have been described by Uhlig (1883, pi. 

13, figs. 2-7) from Barremian beds in the Carpathian 

Mountains. Evidently the generic identification of B.\ 

glennensis Anderson must await the discovery of additional specimens that show the development of the 

species and whose stratigraphic position is certain.

Type. Holotype, GAS 5959.

Occurrence. In California at CAS loc. 28037.

Bochianites paskentaensis Anderson 

Plate 1, figures 13-15

Bochianites pasleentaensis Anderson, 1938, Geol. Soc. America 

Spec. Paper 16, p. 167, pi. 29, fig. 10.

The species has a straight shaft, an ovate cross section that is slightly higher than wide, faint annular 

ribs that become slightly stronger ventrally, and very 

widely spaced constrictions that are bordered by low 

broad swellings. Both ribs and constrictions cross the 

dorsum transversely, incline forward on the flanks, and 

arch forward on the venter. The suture line appears to 

be identical with that on the genotype species (Arkell 

and others, 1957, p. L206).

Types. Holotype, CAS 8790; hypotypes, USNM 

161184 and 161185.

Occurrences. In California at TJSGS Mesoznic Iocs. 

M3061 and 29595 at top of beds containing Buchia 

pacifica Jeletzky. The holotype (CAS unmimbered 

locality) was obtained one-half mile south of the Wilcox Ranch house at about the same place as Mesozoic 

loc. 29595.

Family PERISPHINCTIDAE Steinmann, 1890 

Genus KOSSMATIA TThlig, 1907

Kossmatia dilleri (Stanton) 

Plate 3, figures 5-7

Hoplitcs dilleri Stanton, 1896, U.S. Geol. Survey Bull. 733, p. 82,

pi. 18, figs. 6, 7. [Imprint 1895.1 

Kossmatia dilleri (Stanton). Burckhardt, 1912, In^t. Geol.

Mexico Bd. 29, p. 32. 

Kossmatia dilleri (Stanton). Imlay, 1943, Jour. Paleontology,

v. 17, p. 537.

The species is represented only by the holotype, 

which is a small septate internal mold that retains some 

shelly material and consists of four immature whorls.

The shell is compressed and discoidal. The outermost 

whorl embraces about one-third of the preceding whorl. 

The whorls are rounded in section, are broaclosr than 

high at the adapical end of the outer whorl but become 

higher than broad adorally. During growth tre flanks 

likewise change from highly convex to gently convex, 

and the venter changes from broadly rounded to moderately rounded. The umbilicus is moderately wide. 

The umbilical wall is vertical at its base and rounds 

evenly into the flanks. The body chamber is unknown.

The ornamentation consists of sharp, moierately 

spaced primary ribs and slightly less sharp, rather 

closely spaced secondary ribs. The primary ribs begin 

low on the umbilical wall, incline slightly forward 

on the flanks, and pass into two or three secondary ribs 

between the middle and the upper third of thQ, flanks. 

Wherever a primary rib passes into three secondary 

ribs, two of the secondary ribs arise a little- higher 

than the other. The furcation points are elevf.ted but 

are not tuberculate. The secondary ribs project strongly 

forward on the upper parts of the flanks and on the
AMMONITES FROM THE BVCHIA ZONES P31

venter and have a chevronlike arrangement along the 

midline of the venter. This arrangement is interrupted 

by a midventral groove on the internal mold, but the 

ribs persist across the venter wherever shelly material 

is preserved.

The holotype at a diameter of 31 mm has a whorl 

height of 12 mm, a whorl thickness of 11 mm, and an 

umbilical width of 11 mm.

Comparisons of the described species of Kossmatia 

from California with those from elsewhere in the 

world are difficult to make because the descriptions of 

the California species are based on small immature 

specimens whereas the descriptions of most species are 

based on large adult specimens. Nonetheless, K. dilleri 

(Stanton) shows considerable resemblance in its rib 

pattern to the specimens of K. aft'. K. victoris (Burckhardt) (1906, p. 132, 133, pi. 36, figs. 7-9) from the 

Mazapil area, Mexico. It differs mainly by having 

somewhat finer and denser ribbing. In that respect, it 

shows more resemblance to the holotype of K. victoris 

(Burckhardt) (1906, p. 131, pi. 36, figs. 1-6).

Type. Holotype, USNM 21573.

Occurrence. In California at USGS Mesozoic loc. 

666, which is recorded as about 3 miles directly west of 

Lowrey's Kaiich house and is shown on a 1890 edition 

of the Red Bluff quadrangle as 3i/^ miles slightly south 

of west of Lowrey's house. This location is definitely 

south of the easterly trending fault zone near the North 

Fork of Elder Creek and is in the middle third of the 

Jurassic Buchia-bv&Ting beds which appear to be about 

3 miles thick. It seems probable that the occurrence of 

Kossmatia at Mesozoic loc. 666 is a little higher strati - 

graphically than the other specimens of Kossmatia 

described by Anderson (1945, p. 981, 982) and reillustrated herein, although it occurs on or near the same 

sandstone ridge as those species.

Kossmatia tehamaensis Anderson 

Plate 3, figures 1, 2

Kossmatia tehamaensis Anderson. Hanna and Hertlein, 1941, 

California Div. Mines Bull. 118, p. 168, figs. 12 and 16 on 

p. 169. (Name not valid because of lack of description.)

Kossmatia tehamaensis Anderson, 1945, Geol. Soc. America 

Bull., v. 56, p. 981, pi. 2, figs. la-<?.

This species is represented only by the holotype, 

which is a small septate internal mold consisting of 

3i£ whorls.

The shell is discoidal and compressed. The outermost 

preserved whorl is subquadrate in section, wider than 

high, and embraces about one-third of the preceding 

whorl. The flanks on the inner whorls are gently convex and on the outermost whorl are nearly flat. The

venter on the outermost whorl is fairly narrow and 

nearly flat. The umbilicus is moderately wide. The 

umbilical wall is vertical at its base, rounds evenly into 

the flanks on the inner whorls and rather abruptly on 

the outer whorl. The body chamber is unknown.

The inner whorls exposed in the umbilicus bear fine 

forwardly inclined primary ribs, some of which bifurcate below the line of involution. The outermost septate whorl bears fairly sharp primary ribs that be^in 

on the umbilical wall and incline gently forward on 

the lower part of the flanks. Most of these primary 

ribs bifurcate below or near the middle of the flanks, 

but some remain simple. The furcation points are not 

elevated. The secondary ribs are slightly weaker than 

the primary ribs. All ribs on the upper third of the 

flanks project strongly forward and form a broad 

chevronlike pattern on the venter. A smooth groove is 

present along the midline of the venter on the internal 

mold. One pronounced constriction is present near the 

adoral end of the outer whorl. This constriction, is 

bordered adorally by fairly fine and dense ribbing.

The holotype at a diameter of about 48 mm has a 

whorl height of about 18 mm, a whorl thickness of 13 

mm, and an umbilical width of 17 mm.

This species differs from K. dilleri (Stanton) by its 

ribs branching mostly below instead of above the 

middle of the flanks, by the furcation points not being 

elevated, by its secondary ribs arising mostly in twos 

instead of twos and threes, and by the presence of more 

simple ribs. It was compared by Anderson (194£~ p. 

981) with K. aff. K. victoris (Burckhardt) (1906, pi. 

36, figs. 10-12, 15), but its ribs branch much lower on 

the flanks.

Type. Holotype, UC 5956.

Occurrence. In California at UC loc. A-2921. The 

holotype is reported to have been obtained about 4,575 

feet above the base of the Jurassic Buchia-be&ring heds 

(Anderson, 1945, p. 1001) and at about the s^me 

stratigraphic position as K. kleinsorgensis Anderson 

(1945, p. 982).

Kossmatia kleinsorgensis Anderson 

Plate 3, figures 3, 4

Kossmatia kleinsorgensis Anderson, 1945, Geol. Soc. America 

Bull., v. 56, p. 982, pi. 2, fig. 3.

This species, based on one small fragment, differs 

from K. dilleri (Stanton) and K. tehamaensis Anderson by having much higher, sharper, and more widely 

spaced ribs at a comparable size and by the presence of 

a linguiform sinus along the midline of the verter. 

Some of the primary ribs remain simple, but mos* of
B32 JURASSIC AND CRETACEOUS BVCHIA ZONES IN CALIFORNIA AND OREGON

them divide into two secondary ribs a little below the 

middle of the flanks. The furcation points are elevated 

but are not tuberculate.

This species greatly resembles some small immature 

specimens of K. pectinata Burckhardt (1912, p. 134, 

pi. 34, figs. 4, 6, 8, 9) from northern Mexico, but its 

ribs project forward much more strongly on the venter.

Type. Holotype, CAS 8711.

Occurrence. In California from about 1 mile east 

of the Kleinsorg chromite mine near the Middle Fork 

of Elder Creek and about 4,000 feet above the lower 

contact of the Jurassic Z?«cAm-bearing beds (Anderson, 1945, p. 982, 1001). This location should be in, or 

near, the SEi/4 sec. 26, T. 25 N., R. 7 W., Paskenta 

quadrangle.

Family OLCOSTEPHANIDAE Hang, 1910 

Genus PRONICERAS Burckhardt, 1919

Proniceras sp. juv. 

Plate 3, figures 9, 10

One small internal mold, consisting of parts of four 

whorls, bears ribbing similar to that on immature 

specimens of Proniceras from Mexico figured by 

Burckhardt (1921, pi. 16, figs. 5, 7, 13, 15) and to that 

on immature specimens of P. jacobi (Djanelidze (1922, 

p. 59, pi. 1, figs. 5a, b, 6a, b, 9) from southern Europe.

The coiling is fairly evolute. The whorls are stout, 

wider than high, depressed ovate, and are thickest 

below the middle of the flanks. The flanks are gently 

convex and curve evenly into a moderately rounded 

venter. The umbilical wall is vertical at the base, is 

fairly high, and rounds rather abruptly into the flanks.

The primary ribs are high and strong. They trend 

radially on the umbilical wall, incline forward slightly 

on the flanks, and then divide near, or a little below 

the middle of the flanks into pairs of slightly weaker 

secondary ribs. A few primary ribs remain simple. The 

secondary ribs incline forward on the flanks and form 

forwardly arched chevrons on the venter. The ribs on 

the internal mold are partially interrupted by a smooth 

band along the midline of the venter, and most of them 

are offset with respect to ribs on the opposite side of 

the midline. The interspaces on the internal molds are 

a little wider than the ribs. Each of the outer whorls 

bears a pronounced forwardly inclined constriction. 

Tubercles are not present.

This specimen is assigned to Proniceras rather than 

Spiticeras because of the idoceratoid character of its 

ribbing and the complete lack of tubercles or swellings.

Figured specimen. USNM 158808.

Occurrence. In Oregon at USGS Mesozoic loc. 2074 

in association with Neocosmoceras euchrense Imlay,

and Jones, n. sp., Buchia uncitoides (Pavlow), and 

some specimens of B. piochii (Gabb). These were obtained along a beach and may have been obtained from 

more than one bed.

Proniceras maupinense Imlay and Jones, n. sp 

Plate 3, figures 8, 11-16

This species is represented by five internal molds 

and one external mold. Some of these bear shelly 

material.

The shell is fairly evolute and moderately compressed. Its whorls are subovate in section, a little wider 

than high, become wider during growth, are thickest 

a little below the middle of the flanks, and overlap 

from 14 to 1/3 of the preceding whorl. The flanks are 

gently convex and become more convex during growth. 

The venter is moderately to broadly arched. TS umbilicus is fairly wide and shallow. The umbilical wall 

is fairly low, vertical at its base, and rounds evenly 

into the flanks. The body chamber occupies nearly a 

complete whorl but is incomplete.

The inner whorls exposed in the umbilicus bear 

sharp, fairly high moderately spaced forwardly inclined primary ribs and several deep constrictions per 

whorl. The outermost septate whorl similarly bears 

sharp primary ribs that extend to the middle of the 

flanks. From each of them arise two or thre°. much 

weaker secondary ribs that incline forward on the upper parts of the flanks, arch strongly forward on the 

venter, and are slightly weakened along the midventral 

line. A few secondary ribs arise freely on the upper 

third of the flanks, which bear about three secondary 

ribs for each primary rib.

Adorally on the largest preserved whorls the primary 

ribs become higher and more widely spaced, but vary 

somewhat in height and spacing from one specimen to 

another. These ribs pass just below midflank into three 

or four much weaker secondary ribs that arch forward 

on the venter. Adjacent bundles of secondary ribs are 

generally separated by single ribs that arise freely on 

the upper third of the flanks. All whorls bear several 

pronounced forwardly inclined constrictions.

The smaller specimen illustrated at a diameter of 

23 mm has a whorl height of 8 mm, a whorl thickness of 

9 mm, and an umbilical width of 9 mm. The other specimens illustrated have been slightly compressed rnd cannot be measured accurately.

The suture line has a large and long ventral lobe, a 

much smaller and shorter trifid first lateral lobe, a very 

short trifid second lateral lobe, and two auxiliary lobes 

of which the first is largest and is inclined obliquely to 

the other lobes. The suspensive lobe descendr rather
AMMONITES FROM THE BUG HI A ZONES B33

steeply to the umbilicus. The first lateral saddle is fairly 

large and is irregularly bifid.

This species is characterized by having moderate to 

fairly strong but nontuberculate primary ribs and numerous, rather fine secondary ribs. It shows some resemblance in side view to Proniceras aff. P. aguiterae 

Burckhardt (1919, p. 46; 1921, pi. 15, fig. 13) from the 

latest Jurassic of Mexico but has a stouter whorl section 

and finer and denser secondary ribs. It also resembles 

Proniceras gracile Djanelidze (1922, p. 76, pi. 2, figs. 6, 

7a, b) from the latest Jurassic of France in ribbing but 

appears to be less evolute and much stouter.

2'ypes. Holotype, USNM 161186; paratypes, 

ITSNM 161187-161189.

Occurrences. In California at USGS Mesozoic Iocs. 

29589, 29591, and 29592 in association with Buchia aff. 

B. okensis (Pavlow).

Genus SPITICERAS Uhlig, 1903

Spiticeras (Spiticeras) cf. S. (S.) cautleyi (Oppel)

Plate 3, figures 23, 24

One laterally crushed specimen is represented by an 

internal mold that retains some shell material and by 

part of an external mold. The shell is highly evolute 

and apparently compressed. The whorl section is probably elliptical and is higher than wide. The flanks are 

gently convex, and the venter appears to be narrowly 

rounded. The umbilicus is wide. The umbilical wall is 

low, gently inclined, and rounds gradually into the 

flanks. The adult body chamber occupies about threefourths of a whorl and terminates in a prolonged lateral lappet.

The ornamentation of the innermost whorls is not 

well preserved, but at one place the penultimate septate whorl bears umbilical tubercles from which 

branch pairs of ribs that incline forward. The septate 

part of the ultimate whorl bears weak radially trending primary ribs on the umbilical wall, radially elongate tubercles at the base of the flanks, and fairly 

sharp forwardly inclined ribs on the, flanks. The secondary ribs arise singly or in pairs from the umbilical 

tubercles, and some bifurcate again near the middle 

of the flanks.

Body chamber ornamentation consists of umbilical 

tubercles, of radial swellings from those tubercles, and 

of fine secondary ribs that outnumber the tubercles 

about 4: to 1. The ribs branch by twos and threes at 

various heights below the middle of the flanks, and 

some branch again near the middle. Some arise freely 

near the middle. All ribs incline strongly forward on 

the venter. Near the adapical end of the body chamber most rib branching occurs low on the flanks just 

above the tubercles. Adorally, however, some of the 

tubercles are prolonged ventrally as strong radial swellings of variable lengths, and consequently the position of rib branching varies from low on the flanks to 

near the middle. All whorls bear from three to four 

forwardly inclined constrictions.

The specimen is so crushed and distorted that accurate measurements cannot be made. The suture lire is 

too poorly preserved for tracing.

The Oregon specimen greatly resembles the holotype 

of Spiticeras cautleyi (Oppel) (1863, p. 279, pi. 78, fig. 

la, b; Uhlig, 1903, pi. 12, figs la-c) in its wide umbilicus, compressed whorl shape, pattern of ornamentation, 

and presence of lateral lappets. It differs mainly by 

being only about half as large and by some of its umbilical tubercles being prolonged ventrally as fairly 

prominent swellings. It likewise resembles S. eximius 

(Uhlig) (1903, p. 126, pi. 18, figs. 3a-d), but is much 

smaller and bears much stronger ribs on the lower 

parts of the flanks of the adult body whorl.

Figured specimen. USNM 158809.

Occurrence. In Oregon at USGS Mesozoic loc. 3348 

associated with Spiticeras (Negreliceras) and Buchia 

uncitoides (Pavlow).

Spiticeras (Spiticeras) spp. 

Plate 3, figures 17, 18, 20

The subgenus Spiticeras is represented in California 

by a number of fragmentary crushed specimens that 

may be compared to various described species. One distorted external mold (pi. 3, fig. 20) resembles Spiticeras 

serpent'mmn Burckhardt (1912, p. 180, pi. 43, figs. 7, 9, 

10,13,16) from beds of Berriasian age near San Pedro 

del Gallo in northern Mexico in having evolute coiling 

and strong ribs that arise in pairs from prominent 

umbilical tubercles. Another specimen (pi. 3, fig. 18), 

consisting of both external and internal molds, resembles the outer whorl of S. iMigi Burckhardt (1912, p. 

173, pi. 41, fig. 5, pi. 42, figs 1, 3-5) from the same beds 

in Mexico in having prominent radially elongate umbilical tubercles from which pass two or three broad 

ribs that branch again near the middle of the flanks. A 

third specimen (pi. 3, fig. 17), consisting of an internal 

mold that retains some shell material, resemble? S. 

obllquenodosum Ketowski (1893, pi. 9, fig. 18; Djanelidze, 1922, pi. 20, figs. 3a, b, pi. 21, fig. 6) in having 

evolute coiling, strong constrictions, and fairly acute 

umbilical tubercles from which pass bundles of three to 

five weak, closely spaced ribs. The bundling of the ribs 

at the umbilical tubercles distinguish this specimen
B34 JURASSIC AND CRETACEOUS BUCHTA ZONES IN CALIFORNIA AND OREGON

from similarly finely ribbed species of the subgemis 

Negreliceras, such as 8. (N.) negreli (Matheron) 

(Djanelidze, 192*2, pi. 18, figs. 1, 2).

Figured specimens. USNM 158810-158812.

Occurrences. In California /Spiticeras cf. 8. serpentinum Burckhardt occurs at USGS Mesozoic loc. 

M2598, 8. cf. 8. uhligi Burckhardt at Mesozoic loc. 

M3092, and 8. cf. 8. obliquenodosum Retowski at 

Mesozoic Iocs. M1574 and M2253. Associated pelecypods include Buchia uncitoides (Pavlow) at Mesozoic 

Iocs. M2598 and M3092 and a Jurassic variant of B. 

okensis (Pavlow) at Mesozoic Iocs. M1574 and M2253.

Spiticeras (Spiticeras?) n. sp. undet. 

Plate 3, figures 22, 25

Two laterally crushed internal molds that retain 

some shell material probably represent a new species. 

The smaller specimen is nonseptate and probably represents the adapical part of a body chamber. The 

larger specimen shows parts of the septate whorls, 

most of the body chamber, and a lateral lappet; on 

this specimen the coiling is evolute and the umbilicus 

is wide and shallow.

The septate whorls, as exposed in the umbilicus, bear 

strong, nearly radial fairly widely spaced primary ribs 

that are slightly swollen on the umbilical edge and 

bear small tubercles near the middle of the flanks. 

From these tubercles pass pairs of slightly weaker 

secondary ribs that incline gently forward on the 

flanks and on the venter. Adorally on the outermost 

septate whorl the tubercles disappear from the flanks, 

and the umbilical swellings become slightly stronger. 

Several constrictions are present on the septate whorls.

The body chamber bears long, low moderately spaced 

primary ribs that are weakly swollen 011 the umbilical 

edge, incline slightly forward on the flanks, and bifurcate at various heights on the middle third of the flanks. 

The secondary ribs are a little weaker than the primary 

ribs and incline forward more strongly. Many of the 

secondary ribs bifurcate again above the middle of the 

flanks. Adorally on the body chamber the secondary ribs 

become finer, more closely spaced, and outnumber the 

primary ribs about 4 to 1.

These specimens probably belong to the subgenus 

Spiticeras rather than to the subgenus Kilianiceras 

considering that bituberculation is weakly developed 

on the inner whorls and does not persist onto the outermost septate whorl. The persistence of long primary 

ribs onto the body chamber, however, favors an assignment to Kilianiceras. The loss of lateral tubercles at an 

early stage of development is similar to that on S. 

burckhardti- Djanelidze (1922, p. 192; Burckhardt,

1912, p. 175, pi. 43, figs. 1, 2, 6, 8), but that species has 

much finer and denser secondary ribs on its inner whorls 

and does not have long primary ribs on its largest whorl.

The California species is characterized by its evolute 

coiling, by bituberculate perisphinctoid ribbing on its 

inner septate whorls, by early loss of lateral tubercles, 

and by the presence on the body chamber of fairly 

long primary ribs that divide on the middle third of 

the flanks into many weak secondary ribs.

Figured specimen USNM 158813.

Occurrence. In California at USGS Mesozoic loc. 

M2605 asociated with Buchia piochii (Gabb).

Subgenus KILIANICERAS Djanelidze, 1922

Spiticeras (Kilianiceras?) sp. juv.

Plate 3, figures 19, 21

Three small laterally crushed, evolute ammonites 

from Oregon represent the inner whorls of a species 

possibly belonging to the subgenus Kilianiceras as 

shown by the presence of bituberculate ribs on the 

middle whorl of one ammonite. The outer whorls of 

these ammonites bear fairly strong, radially trending 

primary ribs that divide into two or three secondary 

ribs on the upper part of the flanks. The ornamentation is similar in plan to that on the inner whorls of 

8. (K.) daniesi (Steuer) in Leanza (1945, pi. 15, fig. 

4) and 8. (K.} gigas Leanza (1945, pi. 19, fig. 3) but 

differs by being much weaker.

Figured specimen. USNM 158814.

Occurrences. In Oregon at USGS Mesozoic Iocs. 

3348 and 24702. It is associated with Buchia uncitoides 

(Pavlow) at loc. 3348 and B. cf. B. pad flea Jeletzky at 

loc. 24702.

Subgenus NEGRELICERAS Djanelidze, 1922

Spiticeras (Negreliceras) stonyense Imlay and Jones, n. sp.

Plate 4, figures 1-22

This species is represented by about 90 specimens of 

which 63 are internal molds from USGS Mesozoic loc. 

2286. Most of the other specimens retain some shell 

material. Nearly all specimens are crushed laterally or 

distorted.

The shell is compressed and fairly evolute. The 

whorls are elliptical in section, a little higher than 

wide, overlap from 1/4 to 2/5 of the preceding whorl, 

and attain their greatest thickness near or a little below the middle of the flanks. The flanks are gently 

convex but become less convex during growth, and on 

the body chamber their lower parts become somewhat 

flattened. The venter is moderately to narrowly 

arched. The umbilicus is shallow and fairly wide. The
AMMONITES FROM THE BUG HI A ZONES B35

umbilical wall is low, nearly vertical at its base, and 

rounds evenly into the flanks. The body chamber occupies about four-fifths of a whorl. The aperture, 

wherever preserved, is marked by prolonged lateral 

lappets. All specimens in which the aperture is preserved bear lateral lappets.

The ribs on the inner septate whorls are fine to 

moderately fine, are generally as wide as the interspaces, begin near the line of involution, are radial on 

the umbilical wall, incline forward on the flanks, form 

chevrons on the. venter, and are slightly reduced in 

strength along the midventral line. Most of the primary ribs divide on the middle third of the flanks into 

two or three slightly weaker secondary ribs, but some 

primary ribs remain undivided. A few ribs arise 

freely on the flanks.

Adorally on the outer septate whorls the ribs become less strongly inclined forward on the flanks, less 

strongly arched on the venter, and do not form ventral 

chevrons. In addition, the primary ribs become more 

widely spread and on most specimens develop weak 

radially elongate swellings on the umbilical edge. 

Most of the primary ribs divide on the middle third of 

the flanks into two or three secondary ribs. Some 

secondary ribs branch above the middle of the flanks. 

Some ribs arise freely on the flanks.

Adorally on the adult body whorl the ribs weaken 

appreciably on the finely ribbed specimens and little 

or none on the moderately ribbed specimens. In general, the primary ribs weaken more than the secondary 

ribs. Weak radially elongate swellings on the umbilical 

edge are present on some adult body chambers and 

absent on others. Some specimens near the aperture 

develop striae, others bear indistinct broad radial undulations, and still others bear fairly strong ribs.

The ribbing of this species varies considerably in 

strength, in spacing, and in the number of secondaryribs per primary rib. Most larger septate and adult 

whorls bear fine to very fine densely spaced ribs and 

from three to four secondary ribs per primary rib. 

About one-sixth of the larger septate and adult whorls 

bear moderately fine and moderately spaced ribs and 

from 31/2 to 3 secondary ribs for each primary rib. All 

variations between these extremes are present.

Accurate measurements cannot be made because of 

lateral crushing of incomplete preservation. Likewise, 

the suture line cannot be traced in detail.

Two or three weak constrictions occur on each septate whorl. On some specimens the lateral lappet is preceded by a weak constriction or furrow.

This species resembles Spiticems (NegreUceras) 

pa.ranegreli Djanelidze (1922, p. 108-112, pi. 6, figs, 

la-c, 2, 3a--c; pi. 12, figs. 5a-^; pi. 22, figs, la-c) in size,

evolution, tuberculation, ribbing, and in range of variation. It differs from 8. pamnegreli, however, by having consistently stronger primary ribs on all its variants 

and hence less of a tendency toward effacement of ribbing during growth. As a consequence, the most finely 

ribbed variant of the California species has only slightly 

weaker ribbing than the most coarsely ribbed variant 

of 8. paranegreli Djanelidze (1922, pi. 6, fig. 2).

The finely ribbed variant of the species from California likewise resembles 8. (Negreliceras) planissimiim Djanelidze (1922, p. 113, 114, pi. 4, figs. lOa, b) 

but has somewhat stronger primary ribs and less distinct umbilical tubercles, or swellings. It differs from

#? proteus (Ketowski) (1893, p. 252, pi. 10, figs. Fa, b,

 1) by having finer ribbing on its inner whorls and more 

secondary ribs per primary rib on its body whorl.

ry/M.s. Holotype,USNM 158815; paratypes,U£NM 

158816-158833.

Occurrences. In California at TJSGrS Mesozoic loc. 

M2025, M3096, M4066, 2286 and 29505. In Oregon at 

Mesozoic loc. 3348. It is associated with BucJiia uncitoidcs (Pavlow) at all localities except M4066 T7here 

it is associated with B. okensi-s (Pavlow) and with B. 

Qi.B. uncitaides (Pavlow).

Genus GROEBERICERAS Leanza, 1945

Groebericeras? baileyi Imlay and Jones, n. sp.

Plate 5; plate 6, figures 1, 2, 5, 6, 8-11; plate 15

This species is represented by one entirely septate 

specimen that includes both internal and external 

molds. The outer two septate whorls are fragmentary 

and are crushed laterally. The shell is large for the 

genus, discoidal, compressed, moderately evolute, and 

becomes more evolute during growth. The innermost 

exposed septate whorls embrace about three-fifths of 

the preceding whorl. The outermost septate Miorl 

embraces about two-fifths of the preceding whorl. The 

whorls are elliptical in section, much higher than 

wide, and become higher during growth. The flanks 

are nearly flat in their lower half and converge gently 

above into a narrowly arched venter. The umbilicus is 

shallow, moderate in width, and becomes slightly wider 

during growth. The umbilical wall is low, steep, and 

rounds fairly abruptly into the flanks. The body chamber is not preserved.

The ribs on the innermost septate whorls up to a 

whorl diameter of about 30 mm are fairly strong, 

slightly wider than the interspaces, and mostly simple, 

although a few bifurcate low on the flanks. The ribs 

begin on the upper part of the umbilical wall, are 

slightly swollen on the umbilical edge, trend radially 

on the lower part of the flanks, incline slightly for-
B36 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

ward on the upper part of the flanks, and arch forward 

on the venter. They are slightly reduced in strength 

along the midventral line, and some are slightly offset 

with respect to the ribs on the opposite side of the 

venter.

At whorl diameters from about 30 to 110 mm the 

umbilical swellings during growth gradually develop 

into weak radially elongate tubercles. From these pass 

pairs of low ribs that incline slightly forward on the 

flanks, are generally faint near the tubercles, and 

become stronger and broader ventrally. Other ribs 

arise freely, or by branching, on the middle third of 

the flanks. All the ribs arch forward on the venter 

and form weak chevrons along the midventral line. 

At a diameter of 110 mm the ribs on the venter outnumber the tubercles about 3 to 1.

During subsequent growth the ornamentation decreases considerably in strength. The elongate tubercles gradually become indistinct blunt swellings. The 

ribs become very broad, low, widely spaced and less 

commonly branched. The third from the largest septate whorl bears many unbranched ribs, and the next 

two larger septate whorls at a diameter greater than 

about 220 mm bear only simple unbranched ribs. Such 

ribs on the largest septate fragment measure from 

15 to 18 mm from crest to crest.

Each whorl is also marked by three to four forwardly inclined constrictions. These are fairly deep 

on the smallest exposed whorl and are weak on all 

the other whorls.

The holotype at a diameter of 109 mm has a whorl 

height of 42 mm, an estimated whorl thickness of 28 

mm, and an umbilical width of 35 mm. The third 

from the largest septate whorl has a maximum diameter of about 250 mm and is probably only slightly 

compressed. The outer two septate whorls are too 

crushed for measurements, but their very presence 

suggests that the complete ammonite had a diameter 

several times larger than 250 mm.

The suture line is poorly exposed and cannot be 

described accurately.

The characteristics of Gr&ebericerasl bailey I shoAv 

that it belongs in the subfamily Spiticeratinae (Arkell 

and others, 1957, p. L345) but that it differs somewhat 

from any described genus or subgenus of that subfamily. 

Its innermost whorls resemble those of Pronicents, but 

it develops a much higher, more compressed whorl section, much coarser ribbing, and attains a much larger 

size. It differs from large specimens of the subgenus 

Spiticeras, as illustrated by Djanelidze (1922, pi. 14, 

fig. 1, pi. 16, fig. 1, pi. 17), by lacking lateral tubercles 

on its inner whorls and by having a more compressed

whorl section and fewer branching ribs. It differs from 

large specimens of 8. (Kilmniccras} (Steuer, 1897, pi. 

6, figs. 1, 4, pi. 15, fig. 1; Leanza, 1945, pi. 16, figs. 1, 

2, pi. 19, figs. 3, 4, 8; Djanelidze, 1922, pis. 8-10) by 

lacking lateral tubercles and by having weaker umbilical 

tubercles and flatter flanks. It resembles S. (Negrellceras} (Djanelidze, 1922, pi. 5) in whorl shape and 

in the presence of weak umbilical tubercles, but differs 

by having considerably fewer and broader secondary 

ribs that do not tend to fade out on the lower parts of 

the flanks. Its outer whorls greatly resemble those of 

Groebericerax bifrom Leanza (1945, p. 82, pi. 17, figs. 2, 

5; pi. 18, fig. 1, pi. 19, figs. 1,2,7) from basal Cretaceous 

beds in Argentina in size, whorl shape, abrupt umbilical 

edge, and sparseness of ribbing. That genus as defined, 

however, lacks umbilical tubercles, has weaker ribbing 

on the lower parts of the flanks, and has a more narrowly 

rounded venter.

Overall, Groebericerasl batieyi Imlay and Jones, n. 

sp. shows more resemblance to Groebericeras than to 

the other taxa listed above, and thus it could belong 

to that genus. A positive generic determination is not 

possible, however, because Groebericeras is to date 

represented only by a single species whose immature 

growth stages have not been illustrated and whose 

range of variation is unknown.

Groeberweras^ batteyi Imlay and Jones, n. sp. is 

named in honor of Edgar H. Bailey of the U.S. 

Geological Survey who collected the type specimen.

TV/*?. Holotype, TJSNM 158834.

Occurrence. In California at TJSGS Mesozoic loc. 

M2024 in association with Buchia piochii (Gabb) about 

2,000 feet below the top of beds containing BucJiia 

piochii (Gabb) and probably a thousand fe^t more 

below the top of the Jurassic.

Genus TOLLIA Pavlow, 1914

Tollia mutabilis (Stanton)

Plate 7, figures 1, 2, 4-12; plate 8, figures 1-10

OlcostcpJianus (Simbirskitcs) mutabilis Stanton, 1896, U.S.

Geol. Survey Bull. 133, p. 77-78, pi. 15, figs. 1-5 [Imprint

1895.] 

tiiibcraspcditcs'! mutabilis (Stanton). Spatli, 1923, Geol. Soc.

London Quart. Jour., v. 79, pt. 3, no. 313, p. 80S. 

Dichotomies mutabilis (Stanton). Anderson, 1938, Geol. Soc.

America Spec. Paper 16, p. 160. 

Dicliotomitcs tchamacnsis Anderson, 1938, idem., p. 158, pi. 28,

fig. 2, pi. 30, fig. 6. 

Dichotomies ffrcgcrscni Anderson, 1938, idem, p. 158, 159, pi.

28, figs. 3, 4.

Dichotomies burgcri Anderson, 1938, idem, p. 159, pi. 28, fig. 5. 

Homolsomites mutabilis (Stanton). Imlay, 1956, Jour. Paleontology, v. 30, no. 5, p. 1144, 1145.
AMMONITES FROM THE BUG HI A ZONES B37

Homolsomitcs mutaWis (Stanton). Imlay, 1960, U.S. Geol. Survey Prof. Paper 33-i-F, p. 200, 201, pi. 28, figs. 1-22.

Tollia (TolUa) mutabilis (Stanton). Jeletzky, 1965, Canada 

Geol. Survey Bull. 103, p. 38, 39, pi. 14, figs. 3, 7, 9, pi. 15, 

figs. 1, 3, 5:

The collections in hand contain nearly 200 septate 

specimens of this species from the Paskenta area, 

California. Most are from the same spot as the holotype (TJSGS Mesozoic loc. 1093), and the others were 

obtained within iy2 miles at the same stratigraphic 

position. All specimens are somewhat crushed laterally, but some are only slightly deformed.

The septate specimens are discoidal and moderately 

compressed. The whorl section is subelliptical, a little 

higher than wide, and thickest at about the top of 

the lower third of the flanks. The flanks are weakly 

convex and converge slightly ventrally. The venter 

is narrowly to moderately arched and apparently becomes broader during growth. The umbilicus is fairly 

narrow, its wall is fairly low, steep, and rounds evenly 

into the flanks. The body chamber is not preserved 

on any specimen from the Paskenta area, but is probably represented on one crushed adult ammonite from 

the Wilbur Springs area, California. On this ammonite (pi. 7, figs. 13, 14) the body chamber occupies a 

complete whorl and terminates simply. The aperture 

is preserved only on the venter.

The internal molds of the septate whorls bear from 

five to seven forwardly inclined constrictions per 

whorl.

The ribbing on the septate whorls inclines forward 

on the flanks, arches forward considerably on the 

venter, and is highly variable in strength, density, 

and in number of secondary ribs per primary rib. 

The primary ribs incline backward on the umbilical 

wall, incline forward on the lower part of the flanks, 

and divide near the midflank into two to four weaker 

secondary ribs that incline forward more strongly 

than the primary ribs. In addition, some secondary 

ribs arise freely on the flanks at or above the zone of 

furcation. During growth the primary ribs tend to 

become even stronger relative to the secondary ribs, 

and on some specimens they acquire a pinched appearance. All ribs weaken near the adoral end of the 

largest septate specimens (Jeletzky, 1965, pi. 14, fig. 

9; Imlay, 1960, pi. 28, fig. 18).

The high variability in ribbing that is characteristic of this species was discussed by Stanton (1895, p. 

77) and Imlay (1960, p. 201), who concluded that the 

variations were not of specific importance even though 

the extreme variants were strikingly different from 

each other. Additional fossils obtained recently from 

the type locality show clearly that the variants grade

into each other and are associated with each oth^r in 

the same beds.

The suture line is characterized by having long, 

nearly symmetrical lobes and by having auxiliary 

lobes trending nearly straight or ascending slightly 

to the umbilical seam. The first lateral lobe oil the 

holotype (Imlay, 1969, pi. 28, fig. 11) is a little longer 

than the ventral lobe. On two smaller specimens 

shown herein (pi. 7, figs. 5, 7; pi. 8, fig. 6), however, 

the first lateral lobe is a little shorter than the ventral 

lobe.

Olcostepliamis mutdbilis Stanton was assigned by 

Jeletzky (1965, p. 38, 39) to Tollia rather than Hotnolsomites because its outer septate whorls are subelliptical instead of subtriangular in cross section, its 

umbilicus is wider and shallower at all growth stages, 

its ribs branch mostly by twos and threes at only one 

level, its primary ribs are longer and coarser during 

early and middle growth stages, and the auxiliary 

lobes of its suture line ascend feebly instead of strongly to the umbilical seam.

Similar conclusions regarding Olcostepliamis mutabilis Stanton were reached independently by Shulgina 

(1965, p. 82)on the basis of studies of new species of 

Homolsomites from northern Siberia. Although she 

did not assign O. mutdbilis Stanton to Tollia, she 

showed clearly that it did not belong to Homolsomites. 

Furthermore, she said its characteristics fitted those of 

Tollia rather than Homolsomites except that its first 

lateral lobe was as long as or a little longer than its 

ventral lobe.

The presence of a long, slender first lateral lobe on 

Olcostephanus mutdbilis Stanton was also noted by 

Jeletzky (1965, p. 40) but was not considered by him 

to be of sufficient importance to bar assignment of 

that species to Tollia. He noted in particular that 

Tollia andbarensis (Pavlow) (1914, p. 27, pi. 4, figs. 

3a, b), which he considered typical of the genus: has 

a fairly long and slender first lateral lobe similar to 

that on O. mutdbilis. This comparison is not fully apt 

because on the holotype of T. andbarensis the first 

lateral lobe is actually shorter than the ventral lobe 

according to Shulgina (1965, p. 85), who noted that 

Pavlow (1914, p. 28) stated the opposite.

Nonetheless comparison of the suture lines of O. 

mutabilis Stanton, as herein illustrated, with the suture lines of species of Tollia from Siberia (Voronetz, 

1962, figs. 24-26, p. 67-70) supports Jeletzk/s assignment. On all the Siberian species the first lateral Icbe is 

shorter than the ventral lobe, but this relatiorship 

varies considerably, and on such species as T. pakhsaejisis Voronetz (1962, fig. 24) the lobes are almost equal in 

length. On the Siberian species, also, the suture lines

365-428 O - 70 - 6
B38 JURASSIC AND CRETACEOUS BUGHIA ZONES IN CALIFORNIA AND OREGON

are much more frilled (Pavlow, 1914, pis. 12, figs, la, 

2c, 3, pi. 13, fig. 2; Voronetz, 1962, p. 67, 68, TO, pis. 

31, 32, 33, 37 in part) than the suture lines of 0. mutdbilis, but this difference probably reflects the small 

size and immaturity of the California specimens on 

which the sutures are traceable. It appears, therefore, 

that 0. mutdbilis cannot reasonably be excluded from 

Tollia on the basis of its suture line.

The assignment of Olcostephanus mutabilis Stanton 

to Tollia made by Jeletzky (1965, p. 39, 40) assumes 

that the species in the adult develops a smooth, narrowly umbilicate body chamber marked only by constrictions. Unfortunately only one such specimen has 

been found in California, and it is much crushed and 

broken and is not associated with other specimens 

typical of the species. Its probable identity with 0. 

mutabilis Stanton, however, is indicated by the penultimate whorl-(pi. 7, figs. 13, 14)bearing ribs that are 

similar in strength and mode of branching to those 011 

the coarsely ribbed variants of that species. Its assignment to Tollia seems reasonable, but a definite specific 

assignment must await the discovery of better preserved specimens. It follows that the assignment of 

0. mutdbilis Stanton to Tollia. needs substantiation by 

the discovery of better preserved specimens that show 

the characteristics of the adult.

Tollia mutdbilis (Stanton) closely resembles and 

may include Dichotomies gregerseni Aiidersoii var. 

paucicostata Doiiovaii (1953, p. 110-112, pi. 23, figs. 

la, b) from Greenland. That variety was considered 

by its author to differ from D. gregerseni Andersoii 

(1938, pi. 28, figs. 3, 4) only by having a slightly 

smaller umbilicus and fewer ribs. It now appears, on 

the basis of abundant material from California, to 

have ribbing of intermediate coarseness between the 

typical variant of T. mutdbilis (Stanton) (Imlay, 

1960, pi. 28, figs. 5-10) and T, mutabilis var. cmssicostata Imlay (1960, pi. 28, figs. 1-4). It definitely 

has much weaker and denser ribbing than a specimen 

from California that Jeletzky (1965, pi. 14, fig. 3) 

identified as T. paucicostata (Doiiovan) but which appears to be a large septate narrowly umbilicate example of T. mutdbilis var. crassicostata Imlay. The 

specimens from British Columbia that Jeletzky (1965, 

p. 38, pi. 13, figs. 2, 5-7, 9, pi. 14, figs. 4-6, 8) identified 

with T. paucicostata (Donovaii) are considerably more 

evolute than that species and have sparser and higher 

primary ribs at a comparable size. They differ from 

T. mutdbilis var. crassicostata mainly by being appreciably more evolute.

Types. For previously listed types see Imlay (1960, 

p. 201). Other types illustrated herein are as follows: 

Hypotypes of T. mutdbilis (Stanton), USNM 161194-

161198; hypotypes of T. mutdbilis crassicostata Imlay, 

USNM 161199-161202; hypotypes of T. mutdbilis 

burgeri (Andersoii), USNM 161190-161192.

Occurrences. In Oregon at USGS Mesozoic Iocs. 

2154 and 4390. In California at USGS Mesozoic Iocs. 

1010 (equals 1093 and M3061), 29487, 29594, and 29595 

at or near the top of the BucJiia pacifica beds in the 

northeastern part of the Paskenta quadrangle. These 

occurrences in California are in fairly resistant nearly 

vertical beds, packed with buchias, that crop cut as 

vertical ledges on the tops of a series of small hills that, 

extend north-northeast from the northeast corner of 

sec. 20, T. 24 N., R. 6 W., to the south-central part 

of sec. 33, T. 25 N., R. 6 W. The adult ammonite herein compared with Tollia mutdbilis (Stanton) was 

obtained at USGS Mesozoic loc. 29612 in the Wilbur 

Springs quadrangle, California.

Genus OLCOSTEPHANUS Neumayr, 1875

Olcostephanus cf. 0. atherstoni Baumberger (non Sharpe)

Plate 8, figure 15; plate 9, figures 1-3, 6-10

This species is represented by six deformed and 

crushed specimens that show the various growth stages. 

The shell is stout and moderately involute. The adult 

body whorl, preserved on the largest specimen, is 

crushed laterally, but its whorl section appears to be 

depressed ovate and much wider than high. On the 

small septate specimens the whorls overlap almost to 

the umbilical tubercles; the umbilical wall ir low, 

nearly vertical, and rounds evenly into the flanks; the 

flanks are gently convex; and the whorl section is 

probably higher than wide. The adult body chamber 

occupies about three-fourths of a whorl. The aperture 

on the internal mold is marked by a deep constriction, 

that is preserved only on the lower part of the flanks.

The ribs on the small septate specimens (pi. 9, figs. 

7, 8) are fairly sharp, high, and are moderately spaced. 

The primary ribs are strong, trend nearly radially on 

the umbilical wall, and terminate ventrally in prominent radially elongate tubercles on the umbilical edge. 

From the tubercles pass two or three slightly weaker 

secondary ribs that incline forward on the flanks and 

cross the venter transversely. A few ribs arise freely 

on the flanks above the zone of tuberculation, and 

this results in about three secondary ribs for each 

primary rib. All secondary ribs become slightly broader and lower ventrally. Each whorl is also marked by 

two or three deep forwardly inclined constrictions.

On a larger septate whorl (pi. 9, figs. 1, 3, f), the 

ornamentation differs by being somewhat coarser. The 

tubercles are larger and more prominent, the secondary ribs are higher and more widely spaced, and the
AMMONITES FROM THE BUCHIA ZONES B39

constrictions are more conspicuous and generally followed or preceded by a prominent flare.

The ornamentation of the adult body whorl is not 

well preserved but apparently becomes coarser and 

sparser adorally. Secondary ribs outnumber ribs about 

4 to 1.

The suture line cannot be traced, and accurate 

measurements cannot be made.

The adult outer whorl of this specimen is similar 

in size and coarseness of ornamentation to the large 

outer whorls of Olcostephanus curacoensis Weaver 

(1931, p. 427, pi. 49, pi. 50, fig. 328; Leanza, 1945, pi. 

20, fig. 3) from Argentina, but apparently has fewer 

secondary ribs per primary rib. Close comparisons 

cannot be made, however, because the inner whorls of 

the Argentina species have not been illustrated or 

described.

The adult outer whorl of the California species 

differs from the holotype of 0. atherstoni (Sharpe) 

from South Africa as illustrated by Spath (1939, pi. 

20, figs. 4a, b) by having more prominent tubercles 

and fewer secondary ribs per tubercle. In these respects it, shows more resemblance to the large specimens of 0. atherstoni (Sharpe) from Switzerland as 

identified by Baumberger (1907, figs. 114-116 on p. 44, 

pi. 23, figs, la, b) but apparently has a less depressed 

whorl section.

The small specimens of the California species also 

bear ribbing similar to that on small specimens of 0. 

atherstoni (Sharpe) in Baumberger (1907, pi. 21, figs. 

3a, b, pi. 24, figs. 4a, b, 5) but apparently are more 

widely umbilicate. Their general appearance as regards both umbilical width and ribbing matches more 

closely with an ammonite described by Spath (1939, 

p. 28, pi. 19, figs. 3a, b) as O. cf. 0. madagascariensis 

(Lemoine). They differ, however, by having much 

flatter flanks.

Figured specimens. TJSNM 158835-158838.

Occurrences. USGS Mesozoic Iocs. M2680, 29485, 

29555, and 29556.

Genus POLYPTYCHITES Pavlow, 1892

Polyptychites sp. 

Plate 7, figure 3; plate 9, figures 4, 5

The genus Polyptychites is represented by three 

specimens from two localities. The smallest specimens 

are fairly involute and have a rounded whorl section, 

weak primary ribs, rather closely spaced umbilical 

tubercles, fine dense secondary ribs, and deep constrictions that are preceded by a prominent flare. The 

secondary ribs arise from the tubercles by twos and 

threes, and some ribs branch again on the flanks.

The larger specimen is fairly evolute and has a 

rounded whorl section, fairly strong primary rib1 * on 

the umbilical wall, a row of prominent acute tubercles 

at the umbilical edge, fairly sharp secondary ribs, and 

three deep forwardly inclined constrictions of which 

one is preceded by a prominent flare. The secondary 

ribs arise from the tubercles by threes. A few secondary ribs bifurcate again low on the flanks. Two 

inner whorls, partly exposed in the umbilicus, also 

bear prominent tubercles and sharp ribs.

The larger specimen differs from the small by teing 

more evolute and by having much coarser tubercles 

and ribs. It closely resembles the smallest cotyp*} of 

Polyptychites kcyserlingi (Neumayr and Uhlig) (1881, 

pi. 27, fig. 3) from Germany but appears to be more 

evolute and to have slightly weaker ribbing. In 

strength of ribbing and tubercles it shows even more 

resemblance to P. cf. P. keyserlingi (Neumayr and 

Uhlig) as illustrated by Jeletzky (1964b, p. 18, pi. 6, 

fig. 5) from beds of middle Valanginian age in northeastern British Columbia.

Figured specimens, USNM 158839,158840.

Occurrences. In California at USGS Mesozoic loc. 

M1577 in association with Thurmanniceras jenkinsi 

(Aiiderson) and at Mesozoic loc. 29555 in association 

with Olcostephccnus and Buchia cf. B. keyserlingi 

(Lahusen).

Polyptychites trichotomus (Stanton) 

Plate 8, figures 11-14

OleostcijJianiix (Polyptychitcs) trichotomus Stanton, 1896, U.S.

Geol. Survey Bull. 133, p. 78, pi. 16, fig. 1. [Imprint 1895.] 

Dichotomies tricJiotomus (Stanton). Anclerson, 1938, Geo1 , Soc.

America Spec. Paper 16, p. 159. 

Polt/ptychitcs trichotonuis (Stanton). Irulay, 1960, U.S. Geol.

Survey Prof. Paper 334-F, p. 204, pi. 31, figs. 13, 15.

This species, in addition to the holotype, whi^h is 

much crushed and distorted, is now represented by a 

fairly well-preserved internal mold that is only slightly compressed laterally. On the basis of both rpecimens the species may be redescribed.

The shell is compressed and moderately involute. The 

whorls are subovate in section and a little higher than 

wide. The flanks are flattened below and converge 

slightly above to a rather narrowly rounded venter. The 

umbilicus is moderate in width. The umbilical wall is 

vertical, fairly low, and rounds evenly into the flanks. 

The body chamber occupies about four-fifths of a 

whorl and is incomplete.

The septate inner whorls, as exposed in the umbilicus of the holotype, bear fairly strong, forwardly inclined primary ribs that are not tuberculate near the 

umbilicus. The body whorl bears fairly strong virga-
B40 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

tomous ribbing. The primary ribs are weak and trend 

radially on the umbilical wall, recurve at the edge of 

the umbilicus, are strong and forwardly inclined on 

the lower third of the flanks, and divide at from 1/4 

to 1/2 °f the height of the flanks into two appreciably weaker secondary ribs. Generally the adapical 

rib of each pair curves aclapically and then divides 

again on the middle third of the flanks into secondary 

ribs that recurve slightly adorally. All secondary ribs 

are of about equal strength, become slightly broader 

on the venter, and either cross the ventor transversely 

or arch gently adorally.

The suture line cannot be traced. The hypotype at 

a diameter of 73 mm has a whorl height of 26 mm, 

a whorl thickness of 25 mm, and an umbilical width 

of 27 mm.

This species differs from most species of Polyptychites by being compressed, by lacking umbilical tubercles or swellings, and by lacking rib furcation near 

the umbilicus. Its rib pattern greatly resembles that 

of P. ramuUcosta Pavlow (1892, p. 481, pi. 8 (5), 

figs. lOa, b, pi. 15 (8), figs. 6a, b) from the middle 

Valanginian of England and P. denslcosta (Pavlow) 

(1914, p. 26, pi. 5, figs. 3a-c) from the middle Valanginian of Russia, but it is more evolute and compressed 

than those species. It is distinguished from similar 

compressed species of Dichotomies (compare V. 

Koenen, 1902, pi. 3, figs. 6, 7, 10, pi. 47, figs. 1, 2, pi. 

53, figs. 1, 2) by lacking fairly regular bifurcation 

from umbilical swellings or tubercles.

Types. Holotype, USNM 23090; hypotype 161193.

Occurrences. USGS Mesozoic Iocs. 1087 and 29616.

Family BEKRIASELLIDAE Spath, 1922 

Genus BLANFORDICERAS Cossman, 1907

Blanfordiceras californicum Imlay and Jones, n. sp. 

Plate 10, figures 1-5, 10

This species is represented by two specimens, each 

of which includes both internal and external molds.

The shell is compressed and moderately evolute. The 

whorls are higher than wide and subquaclrate in section but become subovate on the body chamber. The 

flanks are flattened in their lower half and converge 

slightly above toward the venter. The venter is flattened along its midline and is moderately narrow. The 

umbilicus is moderately wide and shallow. The umbilical wall is low, is vertical at its base, but rounds 

evenly into the flanks. The body chamber occupies 

about three-fifths of a whorl, begins at a diameter of 

about 35 mm, and bears small lateral lappets.

The septate whorls bear high, narrow fairly widely 

spaced primary ribs that begin near the line of involution, incline slightly forward on the flanks, bifurcate at various heights on the middle third of the 

flanks, and are generally swollen at the point of furcation. A few primary ribs remain simple, and a few 

secondary ribs arise freely on the upper third of the 

flank. The secondary ribs incline forward more 

strongly and are weaker than the primary rite; they 

terminate ventrally in radially elongate tubercles that 

bound a narrow smooth area along the midline of the 

venter. Secondary ribs outnumber primary ribs slightly more than 2 to 1. The innermost septate whorls 

bear two or three constrictions per whorl.

On the body chamber the primary ribs remain high 

and narrow but become more flexuous and more widely 

and variably spaced. They incline slightly forward on 

the lower third of the flank, recurve slightly n^ar the 

middle, and then pass into pairs of weaker secondary 

ribs. The secondary ribs near their furcation points 

continue the same curvature as the primary r;bs and 

then recurve abruptly and incline forward 011 the 

margin of the venter. All ribs cross the venter of the 

body chamber with only a slight reduction in strength 

wherever the shell is preserved. On the internal mold, 

however, the ribs bound a smooth area along tl °, midline of the venter. Near the aperture many primary 

ribs remain simple. The lateral lappet is preceded by a 

single strong rib that curves forward a little below 

the middle of the flanks.

The small paratype at a diameter of 33 mm has a 

whorl height of 13 mm, a whorl thickness of 11.5 mm, 

and an umbilical width of 12 mm. On the holotype at 

a diameter of 41 mm, the dimensions are 15.5,13.5, and 

15 mm respectively. Most of the body chamber of the 

holotype has been crushed laterally and cannot be 

measured.

The suture line is characterized by the ventral lobe 

being distinctly shorter than the first later?! lobe, 

which is long and slender and has two prominent lateral branches. The second lateral lobe is much smaller 

and shorter than the first and is obliquely inclined. 

The auxiliary lobes are small, obliquely inclined, and 

descend steeply to the umbilicus. The first lateral 

saddle is fairly wide and unsymmetrically divided by 

a secondary lobe so that the larger part is on the 

ventral side. The second lateral saddle is bifid, symmetrical, and much narrower than the flrst. In general 

appearance this suture is remarkably similar to that 

of Blanfordiceras wallichi (Gray) (Uhlig, 191C, pi. 29, 

fig. 3b), the genotype species. It differs mainly by 

having a slightly shorter ventral lobe, a slightly lower 

second lateral saddle, and a more obliquely inclined 

second lateral lobe.
AMMONITES FROM THE BUG HI A ZONES B41

This species is assigned to Blanfordiceras rather 

than Berriasella because its secondary ribs project 

strongly forward on the margins of the venter, its 

ventral groove persists onto the adult body chamber, 

and its ribs become rather widely spaced on the body 

whorl. It is much smaller, however, than most described species of Blanfordiceras, and it bears a lateral 

lappet, a feature which has not been mentioned in the 

description of any species of Blanfordiceras. Among 

described species of Blanfordiceras it resembles B. 

acuticosta Ulilig (1910, p. 201, pi. 37, figs. 2a-c) from 

India in most features but differs by having slightly 

more flexuous ribbing and narrow saddles. Its rib pattern closely resembles that of B. wallichi (Gray) 

(Ulilig, 1910, p. 186, pi. 29) and B. rotundidoma Uhlig 

(1910, p. 189, pi. 83, figs, la, b, 2a, b), but it is much 

smaller and probably more compressed than these 

species.

Another similar appearing species is Hoplites australis Burckhardt (1903, p. 64, pi. 11, figs. 9-12; Leanza, 1945, p. 48, pi. 10, figs. 1-4) from the Berriasian of 

Argentina. This species was designated by Spath 

(1925, p. 145) as the type of Pseudo'blanfordia but was 

placed by Wright (in Arkell and others, 1957, p. L352) 

in Blanfordiceras. It differs from the species herein 

described mainly by its ribs being much straighter and 

more widely spaced, its saddles much broader, its first 

lateral lobe much shorter and broader, and its auxiliary 

lobes less steeply inclined.

The California species is also similar in coiling and 

coarseness of ribbing to the European Berriasian 

species Berriasella picteti (Jacob in Kilian) as figured 

by Mazenot (1939, pi. 2, figs, la, b, 2a, b) but is distinguished by its sigmoidal ribbing.

Types Holotype, UC 10099; paratype, UC 10100.

Occurrence. In California at UC loc. B-5120 associated with Buchia uncitoides (Pavlow) and an undescribed species of Inoceramm that has been found 

elsewhere in northern California associated with B. 

uncitoides.

Blanfordiceras sp. undet.

Plate 10, figures 6-9

Another species of Blanfordiceras is possibly represented by the internal and external mold of a single

<O

individual.

The shell is moderately evolute and compressed. The 

whorls are higher than wide and subquadrate in section. The outermost septate whorl embraces about 

two-fifths of the preceding whorl. The flanks are 

flattened below and converge slightly above, The 

venter is flattened and fairly narrow. The umbilicus is 

moderately wide and shallow. The umbilical wall is

low, steeply inclined, and rounds evenly into the flanks. 

The body chamber is probably represented in part by 

about one-fourth of a nonseptate whorl that terminates adorally in a sigmoidal curve suggestive of an 

aperture. A lateral lappet is not evident. The inner 

whorls are septate to a diameter of at least 54 mm, 

which is only half a whorl adapical from the apparent 

aperture.

The septate whorls bear sharp, moderately spaced 

ribs. The primary ribs begin near the line of iiT volution, incline gently forward on the flanks, recurve 

slightly near the middle of the flanks, bifurcate on 

the middle third of the flanks, and are generally 

strongest at or just below the furcation points. Some 

primary ribs remain simple, and some secondary ribs 

arise freely on the upper third of the flanks CT are 

indistinctly connected with the primary ribs. In places 

simple primary ribs alternate with short intercalated 

secondary ribs. The secondary ribs are weaker than 

the primary ribs, incline forward more strongly, and 

pass ventrally into radially elongate swelling? that 

bound a depressed area along the midline of the venter. 

The ribbing on the middle of the venter at a diameter 

of about 36 mm is considerably reduced but at a diameter of about 45 mm is only faintly reduced. The 

innermost whorls bear two or three weak constrictions 

per whorl.

The fragment that probably represents part of the 

body chamber bears high sharp, widely spacei sigmoidal ribs. Some of the primary ribs bifurcate near 

the middle of the flanks, and others remain simple. 

The secondary ribs are broader than but nearly as high 

as the primary ribs, incline forward on the flanks, arch 

forward on the venter, and are only faintly reduced in 

strength along the midline of the venter.

The septate part of the specimen illustrated at a 

diameter of about 34 mm has a whorl height of 14 mm, 

an estimated whorl thickness of about 11 mm, ?,nd an 

umbilical width of 11 mm. At a diameter of about 

45 nun the same dimensions are 18,14 and 13 mm.

The suture line cannot be traced.

This specimen differs from B. californicum Imlay 

and Jones, n. sp. by having appreciably weaker and 

more closely spaced ribs, by attaining a larger size, 

and by being slightly more compressed. Its association 

with that species suggests that it is only a finely ribbed 

variant, but that cannot be proven on the basis cf only 

one specimen. It is much finer ribbed than any described species of Blanfordiceras from India but only 

slightly less than B. molinensis Burckhardt (1903, p. 

66, pi. 11, figs. 13-17) from the Berriasian of Argentina.
B42 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

Its ribbing is more sigmoidal than in the genus 

BerriaseUa, although it bears some resemblance to 

Bernasella oppeli (Kilian) (Mazenot, 1939, pi. 3, figs. 

1-7) and to B. calisto (cVOrbigny) (Mazenot, 1939, 

pi. 4, figs. 6-12).

Figured specimen. UC 10101.

Occurrence. In California at UC loc. B-5120 associated with B. californicum Imlay and Jones, n. sp. 

and Buchia uncitoides (Pavlow).

Genus STTBSTETTEROCERAS Spath, 1923

Substeueroceras stantoni Anderson

Plate 10, figures 11-18

Substeueroceras stantoni Anderson, 1945, Geol. Soc. America 

Bull., v. 56, p. 982, pi. 11, figs. 3, 4; pi. 15, fig. 3.

This species has a subquadrate whorl section, a 

flattened venter, fairly evolute coiling, and high, thin, 

slightly flexuous ribs that are much narrower than the 

interspaces. The primary ribs incline slightly forward 

on the flanks and bifurcate a little above the middle 

of the flanks. The secondary ribs incline forward 

slightly on the upper parts of the flanks and cross the 

venter nearly transversely. They are considerably reduced in strength along the midventral line.

Substeueroceras stantoni Anderson is nearly identical in side view with 8. subquadratum Imlay (1939, 

p. 49, pi. 15, figs. 8, 12-15) from the highest Jurassic 

beds in northern Mexico. It has a flatter venter and 

a more distinct ventral furrow, and its ribs are not 

inflected forward as much on the middle of the flanks. 

It differs from S. alticostatum Imlay (1939, p. 51, pi. 

15, figs. 1-7) from Mexico in the same respects but is 

also much finer ribbed. All these species are represented only by small immature specimens. None of 

them show the loose ribbing that is typical of the adult 

whorl of Substeueroceras. The differences between the 

immature and adult whorls is illustrated by Substeueroceras intercostatum (Steuer) (1897, p. 172, pi. 22, 

figs. 1-5). In that species one immature specimen 

(Steuer, 1897, pi. 22, figs. 4, 5) at its adapical end 

bears fairly regular rib furcation similar to that on 

S. stantoni Anderson. Adorally on the same specimen, 

however, as well as on an adult whorl (Steuer, 1897. 

pi. 22, figs. 1, 2), the ribbing gradually becomes loose 

and rib furcation occurs at various heights on the 

flanks.

Andersen's assignment of the California species to 

Substeueroceras seems reasonable because of the presence of very high and thin ribs similar to those on 

small specimens of Substeueroceras from Mexico 

(Burckhardt, 1906, pi. 40; Imlay, 1939, pi. 15, figs. 

1-9, 12-15).

Types. Holotype, CAS 10452; paratypes CAS 

10453-10456.

Occurrence. In California at CAS loc. 28037.

Substeueroceras cf. S. kellumi Imlay 

Plate 10, figures 19, 20

Berriasella storrsi (Stanton). Anderson, 1945, Geol. Soc. America Bull., v. 56, p. 980, pi. 7, fig. 1.

The specimen described by Anderson is a laterally 

crushed, septate internal mold that retains a fer^ fragments of shelly material. The outer whorl overlaps 

about one-fourth of the preceding whorl. Before being 

crushed the specimen probably had a high subquadrate 

whorl section and flattened flanks. The venter is gently 

rounded. The umbilical wall is low, verticrl, and 

rounds rather abruptly into the flanks.

The ribs are fine, moderately spaced, and inclined 

gently forward on the flanks and are strongest on the 

venter. They are inflected slightly forward nsar the 

middle of the flanks and are arched gently forward 

on the venter. Some of the ribs are weakly swollen 

near the umbilicus, but none is tuberculate. Furcation 

occurs at various heights on the flank from n^ar the 

umbilicus to considerably above the middle. Some 

ribs bifurcate at two levels. Many secondary ribs are 

indistinctly connected with the primary rib?. The 

ribs are not thinned along the midline of the venter. 

Constrictions are not present.

This specimen is assigned to Substeueroceras rather 

than Parodontoceras because its ribs branch irregularly at various heights on the flanks instead c f regularly at or above the middle of the flanks, because its 

ribs are fine instead of coarse on the larger septate 

whorls, and because it lacks constrictions.

The California specimen closely resembles S. lanielUcostatum (Burckhardt) (1912, p. 167, pi. 40, figs. 1-4, 

6) and S. Mlumi Imlay (1939, p. 50, pi. 14, figs. 1-4) 

from the highest Jurassic beds in Mexico. It differs 

from both species by being less involute and by having finer ribbing on its outer septate whorl. Its ribs 

do not arch forward nearly as strongly on the venter 

as on 3. disputable (Castillo and Aguilera) (1895, p. 

14, pi. 14). Fine dense ribbing similar to that on the 

California specimen occurs also on a number of fragments of Substeueroceras figured by Burckhard^ (1906, 

pi. 39, figs. 1, 2; 1912, pi. 39, fig. 11; pi. 40, figs. 5, 

7-10; pi. 48, figs. 1-4).

The California specimen in comparison with species 

from South America greatly resemble Substeueroceras 

koeneni (Steuer) (1897, p. 45, pi. 17, figs. 1-5; Leanza, 

1945, pi. 7, fig. 4), but differs by having a wider umbilicus and less flexuous ribs that are less projected
AMMONITES FROM THE BUCHIA ZONES B43

forward on the upper parts of the flanks. In these 

respects it shows more resemblance to /S. fasciafum 

(Steuer) (1897, p. 46, pi. 18, figs. 1-3), but appears 

to have slightly sharper ribbing and lower points of 

rib branching. It differs from /S. permulticostatum 

(Steuer) (1897, p. 56, pi. 23, figs. 1, 2) by having a 

narrower umbilicus and more widely spaced ribbing. 

S. steueri (Gerth) (1925, p. 86, pi. 5, figs. 4, 4a) develops coarser ribs on its outer whorl.

The California specimen probably shows more resemblance to /S'. fasciatum (Steuer) than to any other 

South American species listed. That species, however, 

was considered by Gerth (1925, p. 83) to be no more, 

than a variety of S. koeneni (Steuer). Such a relationship was disputed by Leanza (1945, p. 28).

Overall, the California specimen probably shows 

greater resemblance to S. kellumi Imlay than to any 

other described species of Substeueroceras. Its finer 

ribbing may merely reflect the difference between ribbing preserved on an internal mold and the ribbing 

preserved on the original shell as on the holotype of 

S. kellumi. The greater involution of S. kellumi appears to be the only important difference.

Figured specimen. CAS 10463.

Occurrence. CAS loc. 28037.

Genus PROTACANTHODISCUS Spath, 1923

Protacanthodiscus taffi (Anderson)

Plate 6, figures 3, 4, 7

Aulacosphinctcs taffi Anderson, 1945, Geol. Soc. America Bull.,

v. 56, p. 979, pi. 7, figs. 4a, b. 

'iDixtoloccras ,sp. Anderson, 1945, idem, p. 983, pi. 14, fig. 4.

This species is represented by internal and external 

molds of the holotype, which is an immature specimen 

that has been slightly compressed laterally.

The shell is discoidal, compressed, and moderately 

involute. The outermost preserved whorl is subquadrate in section, is a little higher than wide, and embraces about two-fifths of the preceding whorl. The 

flanks are convex near the adapical end of the outer 

whorl, but adorally their lower part becomes flattened 

and their upper part converges toward the venter. The 

venter is moderate in width and is flat. The umbilicus 

is fairly narrow and deep. The body chamber is unknown.

An inner whorl, exposed in the umbilicus, bears 

sharp, fairly widely spaced ribs that terminate in 

prominent lateral tubercles at the line of involution. 

The outermost whorl bears sharp, moderately spaced, 

forwardly inclined primary and secondary ribs and 

lateral and ventral tubercles. The primary ribs arise 

on the upper part of the umbilical wall, incline slightly forward to the middle of the flanks, and ther generally pass into pairs of lower, broader secondary 

ribs that incline forward more strongly. Some rather 

weak secondary ribs arise freely along the zone of 

furcation. The furcation points are marked by fairly 

strong radially elongate tubercles. All secondary ribs 

terminate ventrally in tubercles that are nearly conical, 

are fairly closely spaced, and are slightly weaker than 

the lateral tubercles. Weak radially elongate umbilical 

swellings are present on the adoral end of the holotype. The venter is nearly smooth or is marked by 

faint transverse ribbing.

The holotype at a diameter of 20 mm has a whorl 

height of 8 mm, a whorl thickness of 7(?) mm, and 

an umbilical width of 5.5 mm.

Protacanthodiscus taffi (Anderson) is recorded from 

the same place as the following species:

Distoloceras sp. (Anderson, 1945, p. 979, pi. 14,

%. 4)

Protacanthodiscus sp. (Anderson, 1945, p. 962) 

Lytoceras aff. L. exoticum Oppel (Anderson, 1945,

p. 980) 

Inoceramus stantoni Anderson (1945, p. 961, pi.

15, fig. 2) 

"Aucella" fischeri d'Orbigny var. (Anderson,

1945, p. 962)

"A" stantoni Pavlow (Anderson, 1945, p. 9?0) 

Of these species, Distoloceras sp. (now probably 

lost) is similar in side view to Neocosmoceras euchrenxe Imlay and Jones, n. sp., described herein, and 

Inoceramus stantoni Anderson (not Sokolov) shows 

some resemblance to /. ovatus Stanton (1895, p. 47, pi. 

4, fig. 15).

The age of the faunule on the basis of the species of 

"Aiicel'lcF should be latest Jurassic (late Tithonian) 

rather than Berriasian, provided Andersen's identifications are correct. An age not younger than Berriasian is indicated by the presence of Protacanthodiscus. 

a trenus not known above the Berriasian. A Berriasian o

age is indicated by an ammonite that possibly represents the Berriasian genus Neocosmoceras. A\\ age 

near the boundary of the Jurassic and Cretaceous is 

indicated by the presence of an Inoceramus resembling 

Inoceramus ovatus Stanton, whose holotype was found 

(Mesozoic loc. 1086) in association with Buchia aff. B. 

okensis (Pavlow) and B. terebratuloides (Lalmsen) 

(Pavlow, 1907, p. 60, 83) of latest Jurassic age.

"Aidacosphinctes^ taffi Anderson is assigned to Protacanthodiscus rather than Neocosmoceras beer/use it 

has biplicate Bernasetta-\^&& ribs instead of simple 

ribs. Its small size, however, indicates that it is an 

immature form and precludes any meaningful com-
B44 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

parisons with the much larger specimens of Protacanthodiscm that have been described.

Type Holotype, CAS 8709 and 8709a (external 

mold).

Occurrence. In California CAS loc. 28037 according to Anderson (1945, p. 979). The holotype, however, was obtained on Grindstone Creek, 1,200 feet 

west of the iron bridge, whereas most of the specimens 

from loc. 28037 were obtained from nearby Watson 

Creek. Also, the holotype of Inoceramus stantoni Anderson (not Sokolov) (Anderson, 1945, p. 961) from 

the same spot on Grindstone Creek was reported by 

Anderson (1945, p. 961) to be from "a horizon very 

near that of loc. 28037 (Calif. Acad. Sci.) not far to 

the north."

All the specimens mentioned by Anderson as being 

obtained from 1,200 feet west of the iron bridge (now 

washed away) on Grindstone Creek are referred to 

herein, under the locality descriptions, as "near CAS 

loc. 28037."

Genus PARODONTOCERAS Spath, 1923

Parodontoceras storrsi (Stanton)

Plate 12, figures 11,16-18

HopUtcs storrsi Stanton, 1896, U.S. Geol. Survey Bull. 133, p.

79, 80, pi. 17, figs. 1, 2; pi. 18, fig. 5. [Imprint 1895.] 

IBerriasella, cf. B. storrsi (Stanton). Burekhardt, 1912, Inst.

Geol. Mexico Bol. 29, p. 162, pi. 39, figs. S-10. 

Not BcrriaseUa storrsi (Stanton). Anderson, 1945, Geol. Soc.

America Bull., v. 56, p. 980, pi. 7, fig. 1.

This species is represented in available collections 

only by the holotype, which consists of a fairly large 

septate internal mold that shows parts of two whorls 

and retains some shell material.

The shell is discoidal, compressed, and moderately 

involute. The whorls are subquadrate, much higher than 

wide, and embrace about half of the preceding whorl. 

The flanks are flattened, subparallel in their lower third, 

and convergent toward the venter in their upper twothirds. The venter is nearly flat. The umbilicus is moderate in width. The umbilical wall is low, very steep, 

and rounds evenly into the flanks. The body chamber 

is unknown.

The ribbing on the adapical end of the outermost 

preserved septate whorl is fairly sharp, moderately 

spaced, and gently flexuous. The primary ribs begin 

on the upper part of the umbilical wall, incline slightly forward on the lower two-fifths of the flanks, then 

recurve and generally bifurcate at or just above the 

middle of the flanks into equally strong secondary ribs. 

A few ribs remain simple. The secondary ribs arch 

forward gently on the upper parts of the flanks, thicken a little on the margins of the venter, cross the

venter transversely, and on the internal mold are reduced in strength along the midventral line. The 

interspaces are about twice as wide as the primary ribs.

Adorally on the outermost septate whorl both primary and secondary ribs become slightly broader, the 

interspaces become narrower, and the secondary ribs 

become a little thicker on the margins of the venter. 

Most primary ribs bifurcate a little above the middle 

of the flanks, but a few remain simple. Earely a secondary rib arises freely near the middle of the flanks. 

Secondary ribs outnumber primary ribs about 2 to 1. 

Four weak constrictions are present on the outermost 

septate whorl.

The holotype has been crushed slightly laterally but 

at a maximum diameter of 110 mm has a whorl height 

of 48 mm, a whorl thickness of 30 mm, and an umbilical width of 35 mm.

The suture line (Stanton, 1895, pi. 17, fig. 1) is characterized by a strongly retracted suspensive lobe and 

by a first lateral lobe that is much longer tha,n the 

ventral lobe.

One specimen from Mexico described by Cistillo 

and Aguilera (1895, p. 38, pi. 11, fig. 2) as Hoplites 

calisto (d'Orbigny) var. was considered by Stanton 

(1895, p. 80) to be closely related to Parodontoceras 

storrsi. It differs from that species, however, by being 

much more evolute and by having considerably coarser 

and sparser ribbing. Another specimen from Mexico 

described as Berriasella cf. B. storrsi (Stanton) by 

(Burekhardt, 1912, p. 162, pi. 39, figs. 8-10) is too 

poorly preserved for close comparisons with the holotype of P. storrsi, but apparently has a much stouter 

whorl section.

P. storrsi (Stanton) also shows some resemblance to 

P. calistoides (Behrendsen) (1891, p. 402, pi. 23, figs, 

la, b) from the highest Jurassic of Argentina, but 

differs from the holotype of that species by being more 

involute and by having much finer and denser ribbing. 

In these respects it shows more resemblance to the 

finer ribbed variants of P. calistoides (Behrendsen) 

illustrated by Steuer (1897, pi. 17, figs. 13-16) and 

Leaiiza (1945, pi. 5, figs. 5, 6) but appears to have 

more closely spaced and more flexuous ribs, fewer unbranched and intercalated ribs, and a more compressed 

subquadrate whorl section. Overall it differs from P. 

calistoides in much the same ways as it differs from 

P. reedi (Anderson).

Parodontoceras storrsi (Stanton) is much more involute than any of the described species of Parodontoceras from southern Europe. In rib pattern and whorl 

shape, however, it resembles P. paramacilenta Mazenot 

(1939, p. 127, pi. 20, figs. 1-3, pi. 21, fig. 1) from beds 

of early Berriasian age.
AMMONITES FROM THE BUG HI A ZONES F45

. Holotype, USNM 23092. 

Occurrence. In California at USGS Mesozoic loc. 

1084 associated with Buchia piochii (Gabb) from 

2,000 to 3,000 feet below the top of the range of that

species.

Parodontoceras cf. P. storrsi (Stanton)

Plate 12, figures 7, 8, 10

Two small specimens closely resemble the smallest 

exposed septate whorl of the holotype of Parodontoceras storrsi (Stanton) (1895, p. 79, pi. IT, figs. 1, 2) 

in amount of involution and fineness of ribbing. They 

are appreciably more involute and finer ribbed than 

specimens of P. reedi (Anderson) (1945, p. 978, pi. 6, 

fig. 10, pi. 7, fig. 3) at a comparable size.

Figured specimen USNM 161204.

Occurrence. In California at USGS Mesozoic loc. 

29489 associated with Buchia aff. B. okensis (Pavlow) 

in the lower part of its range. This occurrence is at 

least several hundred feet lower stratigraphically than 

that of P. reedi (Anderson) obtained about 1 mile to 

the north at UC loc. B-5094 and is several thousand 

feet higher than the occurrence of the holotype of P. 

storrsi (Stanton).

Parodontoceras reedi (Anderson) 

Plate 11, figures 1-11, plate 12, figures 9, 12

Aulacosphinctcs rccdi Anderson, 1945, Geol. Soc. America Bull.,

v. 56, p. 978, pi. 6, fig. 10; pi. 7, 'fig. 3. 

Aulacosphinctes watsoncnsis Anderson, idem, pi. 11, fig. 6 (not

described).

This species, as herein interpreted, is represented 

by six septate internal molds of which some retain a 

little shell material.

The shell is discoidal, compressed, and evolute. The 

whorls are subquadrate in section, higher than wide, 

become higher during growth, and embrace about onefourth of the preceding whorl. The flanks are flattened 

and subparallel. The venter is moderate in width and 

gently convex to nearly flat. The umbilicus is wide. 

The umbilical wall is low, steep, and rounds evenly 

into the flanks. The adult body chamber is not known.

The ribs on the smallest whorls (pi. 11, figs. 4, 5) up 

to a diameter of about 22 mm are sharp and moderately spaced. The primary ribs are radial on the umbilical wall, incline slightly forward on the flanks, recurve just above the middle of the flanks, and then bifurcate. The secondary ribs incline forward on the 

flanks and venter, are slightly reduced in strength 

along the midventral line, and are nearly as strong 

as the primary ribs.

The ribs on the next larger whorl (pi. 11, figs. 2, 3, 

8) up to a diameter of about 60 mm are similar to

those just described. They differ, however, by forking 

both above and below the middle of the flanks, by 

arching forward only slightly on the venter, and by 

not being reduced in strength along the midline of the 

venter except on the internal mold.

On the next larger septate whorl (pi. 11, figs. 7, 9), 

as represented by the holotype, the primary ribs are 

sharp, variably spaced, generally considerably narrower than the interspaces, and incline slightly forward 

to the middle third of the flanks. Bifurcation occurs 

at various heights but mostly on the middle third of 

the flanks and mostly below the middle. Some primary 

ribs remain simple. Some secondary ribs arise freely 

near the middle of the flanks, and some forked secondary ribs are indistinctly connected with the primary 

ribs. All secondary ribs incline forward gently on the 

upper parts of the flanks and cross the venter nearly 

transversely. Secondary ribs outnumber the primary 

ribs about 2 to 1 and are about as strong as the primary ribs.

On still larger septate whorls (pi. 11, figs. 1, 6, 10, 

11) the ribbing on the flanks varies considerably in 

strength from weak to coarse, and many ribs do not 

fork. The interspaces vary considerably in width and 

on the lower parts of the flank are from two to tl ree 

times wider than the primary ribs. The character of 

the ribbing on the adult body chamber is unknown. 

All septate whorls bear six or seven forwardly inclined 

constrictions.

Accurate measurements cannot be made because of 

poor preservation.

The suture line has a very broad unequally bifid 

first lateral saddle, a fairly narrow irregularly trifid 

second lateral saddle, a long irregularly trifid first 

lateral lobe that is considerably longer than the ventral lobe, and a suspensive lobe that descends fairly 

abruptly to the umbilicus. The appearance of the suture line is similar to that of Parodontoceras ctiistoides (Behrendsen) as figured by Steuer (1897, pi. 

17, fig. 15), which differs by having a shorter first lateral lobe and an evenly descending supensive lobe.

This species is characterized by its evolute coiling, 

irregular bifurcation, and the presence of many simple ribs on its larger septate whorls. Parodontoceras 

storrsi (Stanton), redescribed herein, is much nore 

involute, has fewer simple ribs, and rib furcation occurs somewhat higher on the flanks. Also, its suture 

line has a broader first lateral saddle and a more 

strongly retracted suspensive lobe.

Parodontoceras reedi (Anderson) in rib patterr resembles some specimens from the highest Jurassic beds 

in Mexico described by Burckhardt (1906, p. 139, pi.
B46 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

39, fig. 6; 1912, p. 162, pi. 39, fig. 7; 1921, pi. 19, fig. 9) 

as Berriasella cf. B. calistoides Behrendsen, but it is 

more evolute and develops looser ribbing. It has much 

weaker ribbing than Parodontoceras bifurcatwn (Castillo and Aguilera) (1895, p. 42, pi. 20, fig. 1) and 

slightly weaker and denser ribbing than a specimen 

described as Hoplites calisto (d'Orbigny) by Castillo 

and Aguilera (1895, p. 38, pi. 11, fig. 2). That specimen was considered by Stanton (1895, p. 80) and 

Burckhardt (1930, p. 80) to be related to Hoplites 

storrsi Stanton.

P. reedi (Anderson) shows considerable resemblance 

to the finer ribbed variants of P. calistoides (Behrendsen) from the highest Jurassic beds in Argentina as 

figured by Steuer (1897, pi. 17, figs. 13-16) and Leanza 

(1945, pi. 5, figs. 5, 6). Similarities include degree of 

involution, rib pattern, and presence of many simple 

and intercalated ribs. P. reedi is appreciably finer 

ribbed, however, than the holotype of P. calistoides 

(Behrendsen) (1891, p. 402, pi. 23, figs, la, b) but could 

be within the range of variation of that species, which 

according to Krantz (1928, p. 24) and Leanza (1945, 

p. 42) varies greatly in umbilical width, in shape, and 

in coarseness of ribbing. It is possible, therefore, that 

the California specimens herein called P. reedi (Anderson) may eventually be referred to P. calistoides 

(Behrendsen) when more complete and better preserved specimens are available for comparisons.

Compared with species of Parodontoceras from 

southern Europe (Mazenot, 1939, pi. 20, figs. 1-4; pi. 

21, figs. 1, 6-9; pi. 22, figs. 1-3, 5, 6), P. reedi (Anderson) shows great resemblance in coiling and rib pattern to P. ponticum (Eetowski) (1893, p. 256, pi. 10, 

fig. 9; Mazenot, 1939, p. 131, pi. 21, figs. 9a, b) from 

beds of early and middle Berriasian age. It differs 

mainly by having more unbranched ribs, furcation of 

ribs generally lower on the flanks, and a stouter whorl 

section. Both species greatly resemble P. calistoides 

(Behrendsen), but according to Mazenot (1939, p. 

132), P. ponticum, (Eetowski) differs by lacking a 

mid ventral furrow. In reality P. calistoides (Behrendsen) also lacks a ventral furrow wherever the shell is 

preserved on the venter according to Leanza (1945, 

p. 41,42).

Types. Holotype, CAS 8715; holotypes, USNM 

158845-158847 and UC 10097, 10098. The holotype 

of Auiacosphinctes watsonensis Anderson is CAS 8714.

Occurrences. In California at CAS loc. 28037, UC 

loc. B-5094, USGS Mesozoic loc. M2253, M2599, and 

M3030. It is associated with a Jurassic variant of 

Buchia okensis (Pavlow) at all these localities or was 

collected within a few feet of that species.

Genus ATTLACOSPHIBTCTES TThlig, 1910

Auiacosphinctes'? sp. juv.

Plate 12, figures 1, 2

One small ammonite has fairly evolute coiling, a low 

rounded whorl section, and strong perisphinctoid ribbing. The ribs begin low on the umbilical wall, incline 

gently forward on the flanks, and arch weakly forward 

on the venter. The primary ribs are strong ani fairly 

high, and most of them bifurcate near the middle of 

the flanks. The secondary ribs are slightly weaker than 

the primary ribs, and generally the adoral rib of each 

pair is in direct line with the primary rib. All secondary ribs terminate abruptly at a narrow, smooth area 

along the midline of the venter on the internal mold O

and also wherever shell material is preserved. The 

furcation points of the ribs are slightly swollen. Tubercles are not present. Interspaces are abont twice 

as wide as the ribs. Constrictions are not present.

This ammonite shows all the features characteristic 

of Auiacosphinctes, but it is too small and immature 

for a positive generic identification. It was considered 

by Stanton (1895, p. 82) to be a small specimen of 

Hoplites dilleri Stanton (now referred to Kossmatia), 

but it has much coarser ribbing than that species at a 

comparable size.

Figured specimen. USNM 23229.

Occurrence. In California at USGS Mesozoic loc. 

1003 in association with Buchia piochii (Gabb) and 

the holotypes of Parodontoceras storrsi (Stanton) and 

Phylloceras knoxvillense Stanton.

Auiacosphinctes? diabloensis Anderson 

Plate 12, figure 3

Auiacosphinctes diabloensis Anderson, 1945, Geol. Soc, America 

Bull., v. 56, p. 980, pi. 2, fig. 2.

The holotype is a small, fragmentary, and immature 

specimen. It is fairly evolute and has a rounded whorl 

section. The characteristics of the venter are unknown. 

The flanks bear sharp moderately spaced radially 

trending primary ribs of which most bifurcate high 

on the flanks into slightly lower and broader secondary 

ribs. The furcation points are slightly swollen. Constrictions are not evident.

The specimen is not well enough preserved for a 

definite generic determination. Its ribbing does not 

match with any of the small perisphinctoid ammonites 

described herein under Auiacosphinctes ?, Parodontoceras, or /Substeueroceras.

Type. Holotype, Philadelphia Acad. Sci. collection; plastoholotype, CAS 8710.

Occurrence. In California from Bagley C~eek near 

Mount Diablo, Contra Costa County.
AMMONITES FROM THE BUG HI A ZONES B47

Aulacosphinctes? jenkinsi Anderson 

Plate 12, figures 5, 6

Aulacosphinctes jcnldmi Anderson, 1945, Geol. Soc. America 

Bull., v. 56, p. 979, pi. 13, figs. 3a, b.

This species is represented by two crushed external 

molds. It is characterized by fairly evolute coiling and 

by high, thin, slightly flexuous, widely spaced ribs that 

bifurcate near the middle of the flanks and incline 

gently forward high on the flanks. The characteristics 

of the venter are unknown. Tubercles are not present 

at the furcation points.

The ribbing of this species resembles that on Siibsteueroceras stantoni Anderson (1945, p. 982, pi. 11, 

figs. 3, 4, pi. 15, fig. 3) but is a little stronger and 

much more widely spaced at a comparable size. The 

ribbing is likewise similar to that on the inner whorls 

of Substeueroceras santarosanum (Burckhardt) (1906, 

p. 124, pi. 35) and of Parodontocems 'bifurcatum (Castillo and Aguilera) (1895, p. 42, pi. 20, fig. 1). It is 

more flexuous than is typical of Aulacosphinctes, but 

without knowledge of the venter an assignment to that 

genus cannot be ruled out.

Type. Holotype, CAS 8712; paratype, CAS 8713.

Occurrence. In California at CAS loc. 28037.

Genus PASKENTITES Imlay and Jones, n. genus

This genus has a compressed, widely mnbilicate shell 

that becomes more compressed and less widely mnbilicate during growth. Its inner whorls are characterized 

by having high widely spaced primary ribs that bear 

tiny conical tubercles near the ventral margin. From 

these pass pairs of much weaker secondary ribs that 

project strongly forward on the venter. Its outer 

septate whorls are characterized by loss of tubercles, 

weakening of primary ribs, development of biplicate 

perisphinctoid ribbing, strong projection of secondary 

ribs on the venter, and a chevronlike rib pattern on 

the venter. A ventral groove is absent on septate 

whorls of medium to large size. Paskentites paskentaensis Imlay and Jones, n. sp. is designated as the 

type species of the genus.

The coronate inner whorls of Paskentites greatly resemble the adult whorls of the genus Hemispiticeras 

Spath (1925, p. 144) from the upper Tithonian of Argentina (Steuer, 1897, p. 154, pi. 8, figs. 1-4) but are 

a little more evolute and have more strongly projected 

secondary ribs. The perisphinctoid ribs on the outer 

whorls resemble those on the Late Jurassic ~e;enus

Kossmatia (Arkell and others, 1957, p. L353) but are 

less dense and are less branched. The early Hauterivian genus Speetoniceras (Arkell and others, 1957, p.

L349; Pavlow, 1886, pis. 1, 2) resembles Paskentites in 

appearance and in development, but its ribs branch 

lower on the flanks and project less strongly on the 

venter. The Tithonian genus Windhameniceras Leanza (1945, p. 22; 1949, p. 239-242) has coronate inner 

whorls and perisphinctoid outer whorls as does Paskentites, but its ribs branch somewhat lower on the 

flanks and cross the venter transversely.

Faskentites paskentaensis Imlay and Jones, n. sp. 

Plate 13, figures 11-17

This species is represented by eight specimens of 

which most are fragmentary and crushed laterally.

The coiling is highly evolute. The whorls are subquadrate in section, are higher than wide except possibly on the smallest inner whorls, and become higher 

during growth. The flanks are gently rounded on the 

small inner whorls but are flattened on the middle and 

outer whorls. The venter is narrowly rounded on the 

largest septate whorl and is probably moderately to 

narrowly rounded on the smaller whorls. The umbilicus is wide. Its wall is low, steep, and rounds evenly 

into the flanks. The body chamber is unknown but is 

possibly represented in part by the adoral one-frrirth 

of the outermost whorl of the holotype.

On the small inner septate whorls the primary ribs 

are high, narrow, and fairly widely spaced. They begin near the line of involution, incline forward slightly 

on the flanks, are highest on the lower part of the 

flanks, weaken a little just above the middle of the 

flanks, and then terminate in small conical tubercles 

on the margin of the venter. From these tubercles 

arise pairs of low broad ribs that incline strongly forward on the venter. The midline of the venter is poorly 

exposed, but appears to be marked by a groove on one 

specimen at a diameter of about 18 mm. Several v^eak 

constrictions are present on each whorl.

On the middle and large septate whorls the primary 

ribs adorally gradually become lower, the tubercles 

weaker, and the points of rib furcation somewhat lower on the flanks. On the largest known septate whorl 

(pi. 13, figs. 16, 17) the primary ribs are low, narrow, 

moderately spaced, incline slightly forward, are slightly swollen low on the flanks, and are nontuberculate. 

They pass at about three-fifths of the height of the 

flanks into pairs of weaker secondary ribs that incline 

strongly forward and form chevrons along the midline 

of the venter. A few secondary ribs arise freely on 

the upper parts of the flanks between the tubercles. 

The midline of the venter does not bear a groove. The 

largest septate whorls bear several weak constrictions.
B48 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

The holotype at a diameter of about 110 mm has a 

whorl height of 31 mm and an umbilical width of 55 

mm. The suture line cannot be reproduced or described.

The features of this species do not fit those of any 

previously described genus. Its inner whorls in side 

view greatly resemble those of Hemispiticeras steinmanni (Steuer) (1897, p. 28, pi. 8, figs. 1-4) from the 

latest Jurassic of Argentina (Gerth, 1925, p. 124, 128). 

Its middle and outer septate whorls differ, however, by 

gradual loss of tuberculation, by becoming compressed 

laterally, and by the strong forward projection of 

secondary ribs on the venter. The inner whorls of the 

California species likewise resemble the small septate 

whorls of Spiticeras (Kilianiceras] gigas Leanza(1945, 

p. 74, 75, pi. 19, figs. 3, 4) from the upper Berriasian 

of Argentina. Its outer septate whorls differ, however, from comparable-sized whorls on the Argentina 

species by having weaker and sparser ribbing, by losing the ventrolateral tubercles at a smaller size, and 

by lacking umbilical tubercles.

Type. Holotype, USNM 161205; paratypes. USNM 

161206-161208.

Occurrences. In California at USGS Mesozoic Iocs. 

29596, 29598, and questionably at M703 in association 

with Buchia pacified Jeletzky. South of Mill Creek it 

occurs in the middle third of Buchia pacifica beds and 

is associated with Kilianella crassiplicata (Stanton) at 

Mesozoic loc. 29596.

Genus THTTRMANNICERAS Cossman, 190V

Thurmanniceras stippi (Anderson)

Plate 13, figures 7-9

Ncocomites stippi Anderson, 1938, Geol. Soc. America Spec. 

Paper 16, p. 166, pi. 29, fig. 2.

Thurmanniceras stippi (Anderson), Imlay, 1960, U.S. Geol. Survey Prof. Paper 334-F, p. 216, pi. 39, figs. 1-5, 8-10.

Recognition of this species is a little difficult because 

the holotype is a fragmentary, crushed internal mold 

on which the ribbing is indistinctly shown and because 

well-preserved specimens have not been found at the 

type locality (CAS loc. 144) on McCarty Creek, Calif. 

Recently, however, one fairly well-preserved fragment 

(pi. 13, fig. 7) bearing ribbing similar to that in the 

holotype has been found (USGS Mesozoic loc. M3059) 

about 3 miles northeast of the type locality at a similar 

stratigraphic position. An associated small ammonite 

(pi. 13, fig. 9) that bears similar ribbing appears to be 

an immature form of the same species.

Thurmanniceras stippi (Anderson), as interpreted 

by these specimens, is characterized by a compressed 

whorl section, a moderately wide umbilicus, a steeply 

inclined umbilical wall, and fairly coarse gently flexuous ribs. All ribs begin singly near the umbilicus, and 

about two-thirds of them bifurcate on the middle third 

of the flanks. On the small whorls the ribs terminate 

ventrally in tubercles that bound a smooth mic1 ventral 

area. On the large whorls the ribs are slightly swollen 

ventrally but continue across the venter with only 

slight reduction in strength. Constrictions are present 

on the small whorls.

This species differs from T. californicum (Stanton) 

(1895, p. 76, 77, pi. 15, figs. 5, 6; Imlay, 1960, p. 214, 

pi. 39, figs. 11-15), which occurs at a lower stratigraphic level associated with Buchia pacifica Jeletzky, 

by its ribs being sharper, more flexuous, and more distinctly forked. It differs from T. jeiikinsi (Anderson) 

(1938, p. 165, pi. 29, fig. 1; Imlay, 1960, pi. 40, figs. 1, 

2, 6, 7, 9) by its ribs being much coarser, more- widely 

spaced, less flexuous, and not fasciculate.

Thurmanniceras stippi (Anderson) has been collected only in beds characterized by Buchia keyserlingi 

(Lahusen), above the range of B. pacifica Jeletzky 

and mostly below T. jenkinsi (Anderson). The holotype of T. stippi (Anderson) was recorded (Anderson, 1938, p. 166) from the south bank of McCarty 

Creek opposite Burt's Ranch house in the NEi/4 sec. 

29, T. 24 N., R. 6 W., Paskenta quadrangle. T «, holotype of T. jenkinsi (Anderson) was recorded (Anderson, 1932, p. 322; 1938, p. 165) about 1,000 fee* higher 

on the same creek. Similarly T. jenkinsi was found 

(Mesozoic loc. M3058) about 1,080 feet higher than T. 

stippi (Mesozoic loc. M3059) in the hills one-half mile 

south of Mill Creek in the central and east-central 

parts of sec. 9, T. 24 N., R. 6 W. Both species are recorded together, however, a little farther north about 

one-half mile east of the Wilcox Ranch hous°- in the 

NE34 sec, 4, T. 24 N., R. 6 W. (USGS Mesozoic Iocs. 

1091, M1579). Still farther north near the road in 

sec. 28, T. 25 N., R, 6 W., T. cf. T. stippi (Arderson) 

was found (Mesozoic loc. M3082) in beds that appear 

to underlie an occurrence of T. jenkinsi (Anderson) 

(Mesozoic loc. 3083). These last occurrences, however, 

are in a zone of faulting, and consequently the apparent superposition of beds may not be real.

Types. Holotype, CAS 10465; hypotypes, USNM 

129836,129837a, b,158848,158849.

Occurrences. In California at USGS Mesozoic loc. 

1091, M3059, and M3084 and CAS loc. 144. Fragments 

resembling immature forms of this species occur as 

Mesozoic Iocs. M1580, and M3082. The specie? is associated with Buchia keyserlingi (Lahusen) at all these 

localities. In addition, a fragment of Thurmanniceras 

(pi. 13, fig. 10) similar to T. stippi (Anderson) was 

found at Mesozoic loc. 29593 near the base of the beds 

containing Buchia pacifica.
AMMONITES FROM THE BUG HI A ZONES P49

Thurmanniceras jenkinsi (Anderson) 

Plate 13, figures 1-6

For synonymy and descriptions see Imlay, 1960, p. 215-216, pi. 

40, figs. 1, 2, 6, 7, 9.

This species is characterized by a compressed whorl 

section, by flattened flanks, and by its ribs being fairly 

thick, low, very closely spaced, strongly flexuous, and 

fasciculate. Some small specimens from a single locality are ilustrated herein to show the ribbing of the 

species and to supplement the illustrations previously 

published.

Types. Holotype, GAS 8775; hypotypes, USNM 

23223,129859,129860, and 158850.

Occurrences. In California at CA'S loc. 33502, UC 

loc. B-5085, and USGS Mesozoic Iocs. 1088, 1091, 

M1575, M1577, M1578, M1579, M3058, M3083, and 

probably also M2040. In Oregon at Mesozoic loc. 2154. 

In California the species occurs in the beds characterized by Buchia keyserlmgi (Lahusen). Its highest 

known occurrence in California is near Nevada Creek 

in the Paskeiita quadrangle (UC loc. B-5085) about 

2,450 feet above the top of the Buchia pacifica beds 

and about 680 feet below an occurrence of Hertleimtes 

pecH Imlay (UC loc. B-5089) (Imlay, 1960, p. 208, pi. 

43).

Genus NEOCOMITES TJhlig, 1905

Neocomites cf. N. wichmanni Leanza 

Plate 14, figures 1-15

cf. Neocomites iciclimanni Leanza, 1945, La Plata Univ. Nac. 

Mus. Anales, new ser., Paleontologia, sec. A, no. 1, p. 61, 

pi. 12, figs. 2, 3.

This species is represented by 30 fragmentary molds 

of which most have been crushed. The shell before 

crushing was probably discoidal, compressed, and moderately evolute. One small specimen (pi. 14, figs. 14,15) 

has a whorl section that is considerably higher than 

wide. One larger specimen (pi. 14, figs. 2-4) at its 

apparently undefomied acloral end is subquadrate in 

section and only slightly higher than wide. On this 

specimen the outermost preserved whorl embraces 

nearly half of the next inner whorl and has a vertical 

umbilical wall.

The ribs on the small specimens are high, narrow, 

moderately spaced, are inclined forward on the flanks, 

and become stronger ventrally. Some begin on the 

umbilical wall, and others begin low on the flanks. Many 

of the ribs are swollen radially on the umbilical edge. 

Forking of the ribs is common at the umbilical edge 

and on the middle third of the flanks, but many ribs 

remain simple. Some secondary ribs arise freely on the 

flanks, and others are indistinctly connected with the

longer ribs or with the umbilical swellings. All ribs terminate ventrally in the acute tubercles that incline forward and that, on the internal mold, border a smooth 

mid ventral area. The interspaces are a little wider t>an 

the ribs.

During growth the ribs on the flanks become somewhat coarser, more closely spaced, and more flexuous. 

On the largest preserved septate whorls the primary 

ribs on the umbilical wall are high, thin, widely 

spaced, are radially arranged, and terminate on the 

umbilical edge in weak radially elongate tubercles. 

From these tubercles arise pairs of ribs, or less commonly single ribs that are sharp, flexuous, and become 

slightly stronger ventrally. Some ribs fork again on 

the middle half of the flanks.

Other ribs arise freely at various heights on the 

flanks. All ribs are slightly swollen and are inclined 

forward on the margins of the venter but are not tuberculate ventrally. The midventral area on the internal mold bears weak, forwardly arched contir nations of the ribs.

This species is assigned to Neocomites rather than 

Siibthurmannia because of the presence of a vertical 

umbilical wall and the lack of constrictions. It differs 

from species of Thunnanniceras by having a vertical 

umbilical wall, umbilical tubercles, rib branching at 

the umbilical edge, and by lacking constrictions. It 

bears a general resemblance to Neocomites wichmanni 

Leanza (1945, p. 61, pi. 12, fig. 2, 3) from Valangmian 

beds in Argentina in having strongly flexuous, fairly 

closely spaced ribs and a fair number of simple ribs, 

but appears to have slightly coarser ribs on its inner 

whorls. Its general appearance is also similar to that 

of the typical variant of N. neocomiensis (d'Orbigny) 

(Sayn, 1907, pi. 3, figs. 10, 11), but it has fewer furcating ribs on the flank and is probably more involute.

Figured specimens. USNM 158841 a and b, 15PS42 

a-e.

Occurrences. USGS Mesozoic loc. M2679 and 

M2680.

Neocomites cf. N. neocomiensis (d'Orbigny)

Plate 14, figure 16

One ammonite is represented by a nearly uiideformed internal mold. It has a high subquadrate 

whorl section, a flat venter, and flat flanks that converge slightly toward the venter. The outer whorl 

embraces about half of the preceding whorl. The umbilical wall on the inner whorls is low, vertical, and 

rounds evenly into the flanks. On the outer whorl the 

umbilical wall becomes high, vertical, and rounds 

abruptly into the flanks. The outermost half whori is 

nonseptate. The aperture is unknown. The ribs are
B50 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

fine and rather closely spaced. They begin on the 

upper part of the umbilical wall, trend radially to the 

umbilical edge, and incline slightly forward on the 

flanks in a gently flexuous manner. They are distinctly 

swollen on the umbilical edge of the outermost half 

whorl. Most ribs bifurcate low on the flanks a little 

above the umbilical edge, and some bifurcate again 

above the middle of the flanks. Some ribs remain simple, and some arise freely low on the flanks. All ribs 

terminate ventrally in tubercles that on the internal 

mold border a smooth midventral area.

At a diameter of 39 mm, the whorl height is 18 mm 

and the umbilical width is 11 mm.

This ammonite differs from N. cf. N. wichmanni 

Leanza, with which it is associated, by having somewhat finer ribbing, a wider umbilicus, less distinct umbilical tubercles at a comparable size, and by rib 

branching occurring a little above instead of at the 

umbilical edge. In these respects it shows more resemblance to a finely ribbed variant of N. neocomiensis 

(d'Orbigny) figured by Sayn (1907, pi. 3, figs. 5a, b) 

as var. siibtemds, but has fewer furcating ribs on the 

upper parts of the flanks. The typical variant cf. N. 

neocomiensis (d'Orbigny) as figured by Sayn (1907, 

pi. 3, figs. 10, 11) apparently has slightly coarser and 

more flexuous ribbing.

Figured specimen. US7SM 158843.

Occurrence. USGS Mesozoic loc. M2680. The species is possibly represented also at Mesozoic Iocs. 29485 

and 29557.

Neocomites cf. N. neocomiensis (d'Orbigny) 

var. premolica (Sayn)

Plate 14, figures 17-19

One species is represented by the internal and external molds of a single specimen which has been compressed laterally. It has high flattened flanks, a narrow flattened venter, and a low, vertical umbilical 

wall. The outer whorl overlaps about three-fifths of 

the next inner whorl. The ribs are fairly high, moderately spaced, and gently flexuous. Most ribs arise on 

the umbilical wall and bifurcate at various heights on 

the middle third of the flanks. A few ribs remain simple. On the adoral fourth of the outer whorl all ribs 

are swollen at the umbilical edge, and some ribs arise 

in pairs from the umbilical swellings. All ribs terminate ventrally in forwardly inclined tubercles that 

border a smooth midventral area. The ribs are not 

swollen at their furcation points on the flanks.

This species is assigned to Neocomites rather than 

Thurmanniceras because of a lack of constrictions and 

because the ribs bifurcate at various heights on the 

middle third of the flank instead of at a uniform

height above the middle of the flanks. Its ribbing is 

comparable with that of some of the most coarsely 

ribbed variants of Neocomites neocomiensis (d'Orbigny) figured by Sayn (1907, pi. 3, figs. 4, 7, 8) as 

var. premolica and is appreciably coarser and le?s flexuous than the typical variant of that species (Sayn, 

1907, pi. 3, figs. lla,b).

Figured specimen. USNM 158844.

Occurrence. USGS Mesozoic loc. M2680.

Genus KILIANELLA Uhlig, 1905

Kilianella crassiplicata (Stanton)

Plate 14, figures 27-31

For synonymy and descriptions see Imlay, 1960, p. 21?, pi. 42, 

figs. 1-5, 7.

The close resemblance of this species to Kilianella 

roiibaudi (d'Orbigny), as discussed previously (Imlay, 

1960, p. 218), is strongly supported by the dircovery 

of several additional specimens. Two of these (pi. 14, 

figs. 29, 31) bear ribbing comparable in coarseness with 

some specimens figured by Sayn (1907, pi. 6, figs. lOa, 

b and 14). Another specimen (pi. 14, fig. 30) bears 

somewhat finer, sharper, and denser ribbing closely 

similar to that on another specimen of K. roiibaudi 

figured by Sayn (1907, pi. 6, fig. 9). Apparently K. 

crassiplicata (Stanton) differs from K. roiibaudi 

(d'Orbigny) mainly in having a more compressed 

whorl section.

Kilianella crassiplicata (Stanton) has been fcmid at 

four stratigraphic positions within the beds characterized by Buchia pacifica Jeletzky. Its lowest occurrence 

(UC A-2925) is about at the top of the lower fourth 

of those beds, or about 550 feet above their base. Its 

highest occurrence (USGS Mesozoic loc. 29£97) is 

about 200 feet below their top. The specimen herein 

shown on plate 14, figure 31, (USGS Mesozoic loc. 

29596) was collected about 650 feet below the top of 

the B. pacifica beds, or about at the base of their upper 

third. The other specimens described previously were 

obtained near the middle of the B. pacifica beds.

Types. Holotype, USNM 23094; hypotypes, USNM 

129684, 161210, 161211; hypotype, UC 10095.

Occurrences. USGS Mesozoic Iocs. 1001, 5339, 

29596, 29597; UC loc. A-2925.

Genus SARASINELLA Uhlig, 1905

Sarasinella cf. S. subspinosa Uhlig

Plate 12, figures 13-15

This species is represented by one specimen that includes a fairly complete external mold and part of an 

internal mold. Some shell material is preserved. The
AMMONITES FROM THE BUG HI A ZONES E51

internal mold is septate and mideformed at its adapical 

end and is crushed at its adoral end. It apparently 

represents part of a body chamber.

The shell is discoidal, moderately compressed, and 

fairly evolute. The whorls are ovate in section, probably a little higher than wide, and overlap about onethird of the preceding whorl. The flanks are gently 

convex and round evenly into the umbilical wall and 

venter. The venter is slightly flattened. The umbilicus 

is fairly wide. The umbilical wall is fairly low and 

steep at its base.

The innermost whorl, as exposed in the umbilicus, 

bears sharp widely spaced radially trending ribs of 

variable strength. Some of the strongest ribs bear 

lateral tubercles just below the line of involution. On 

the succeeding whorl the ribs are widely spaced, are 

alternately strong and weak, and the strong ribs bear 

both weak umbilical tubercles and prominent lateral 

tubercles. On the outermost septate whorl the ribs on 

the flanks are sharp, fairly widely spaced, and highly 

variable in strength. About every third or fourth rib 

is much stronger than the intervening ribs and bears 

prominent umbilical and lateral spines. The weaker 

intervening ribs are not tuberculate on the flanks, but 

some are slightly swollen on the lower part of the 

flanks near the zone of umbilical tubercles. Pairs of 

ribs arise from some of the umbilical spines. The 

characteristics of the ribs on the venter of the internal 

whorls are unknown.

On the outermost nonseptate half whorl the ribbing 

adorally becomes less sharp, nearly uniform in 

strength, and more flexuous. About every third or 

fourth rib bears a high conical umbilical spine from 

which branch a pair of ribs. A few of these ribs and 

a few of the intervening ribs bifurcate again between 

the middle and the upper fourth of the flanks. None 

of the ribs bears lateral tubercles, but all bear radially 

elongate ventral tubercles of slightly unequal strength 

that border a midventral furrow. The midveiitral area 

is marked by weak continuations of the ribs wherever 

the shell is preserved on the venter, but is fairly 

smooth on the internal mold.

This species bears ribbing on its outer whorl similar 

to that on SarasineUa subspinosa (Uhlig) (1910, p. 

239, pi. 90, figs. 4a-c; Spath, 1939, pi. 16, figs. 2a, b) 

but has much coarser ribbing on its inner whorls. It is 

more involute and has coarser ribbing than S. uhligi 

Spath (1939, p. 99, pi. 12, fig. 5, pi. 14, figs, la, b, pi. 

21, figs. 5, 6) at a comparable size, S. chichalensu Spath 

(1939, p. 101, pi. 21, figs. 3, 4) has much coarser and 

sparser ribbing.

Figured specimen. USNM 158852.

Occurrence. In California at USGS Mesozoic loc. 

M3060 in association with Buchia keyserlingi (Lalrusen) about 100 feet above beds containing Tollm 

mutabilis (Stanton) and the highest occurrence of 

Buchia pacifica, Jeletzy.

Sarasinella cf. S. uhligi Spath 

Plate 12, figure 4

One ammonite fragment has a fairly high vertical 

umbilical wall, a rounded umbilical edge, flatter 3d 

flanks, and fairly strong forwardly inclined ribs of 

which most arise in pairs from umbilical tubercles. 

Generally the adoral branch of each pair forks again 

on the middle third of the flank, and generally the furcation point is swollen or weakly tuberculate. The ribs 

become slightly swollen and project forward on the 

margin of the venter.

The fragment has a rib pattern similar to that on 

the larger septate whorls of SarasineUa uhligi Spath 

(1939, p. 99, pi. 14, figs, la, b, pi. 21, fig. 5a). Its ribbing also resembles that on S. campylotoxa, Uhlig 

(1902, p. 49, pi. 4, figs. 1-3; Sayn, 1907, pi. 4, fig. :.2) 

but appears to be less flexuous and to fork less commonly on the flanks.

Figured specimen. UC 10096.

Occurrence. In California at US loc. 2605. This 

locality should be near USGS Mesozoic loc. 1088 and 

either in the top of the Buchia pacifica beds or in the 

basal part of the Buchia keyserlingi beds.

Genus NEOCOSMOCERAS Blanchet, 1922

Neocosmoceras euchrense Imlay and Jones, n. sp.

Plate 14, figures 23-26

Wistoloccras sp. Anderson, 1945, Geol. Soc. America Bull., v. 

56, p. 983, pi. 14, fig. 4.

One internal mold, retaining some shell material, 

shows parts of three whorls and has been slightly 

compressed laterally.

The shell is discoidal, compressed, and highly evolute. The whorls are subquadrate in section, are a little 

higher than wide, become higher during growth, r-nd 

embrace about one-fourth of the preceding whorl. The 

flanks are flattened. The venter is flat on the inner 

septate whorls and is only slightly convex on the body 

chambers. The umbilicus is wide. The umbilical wall 

is gently inclined and rounds evenly into the flanks. 

The body chamber is represented by three-fifths of a 

whorl and is probably nearly complete, as indicated by 

the presence of forwardly arched flank ribs at the 

adoral end of the specimen. Such ribs are suggestive 

of the basal parts of lateral lappets.
B52 JURASSIC AND CRETACEOUS BUCHIA ZONES IN CALIFORNIA AND OREGON

The ornamentation on the smallest whorl consists 

of strong simple, unbranched ribs and of radially 

elongate lateral and ventral tubercles. The ribs begin 

near the umbilicus, incline slightly forward on the 

flanks, and terminate ventrally along a smooth midventral area. They are strong, high, and moderately 

spaced on the lower part of the flanks below the lateral tubercles and are a little lower, broader, and 

rather closely spaced on the upper part of the flanks.

The ornamentation on the next larger whorl consists mostly of simple, very widely spaced, nearly radial ribs and of prominent rounded lateral and ventral 

tubercles. The ribs begin weakly on the umbilical wall, 

are swollen at the umbilical edge, are fairly high and 

narrow on the lower parts of the flanks below the lateral tubercles, and are somewhat lower and weaker on 

the upper parts of the flanks. The ventral tubercles 

border a smooth midventral area.

The ornamentation on the outer whorl consists of 

strong widely spaced umbilical and ventral tubercles, 

of weak widely spaced lateral tubercles, and of irregularly spaced weak to fairly weak, slightly flexuous 

ribs. The umbilical tubercles are round, the lateral 

tubercles are round to radially elongate and become 

weaker adorally, and the ventral tubercles are spirally 

elongate. The ventral tubercles are merely the bases 

of prominent ventral spines of which one is preserved 

in the matrix. Most ribs arise singly from the umbilical tubercles, a few arise in pairs from the umbilical 

tubercles, and still others arise freely on the flanks. A 

few ribs bear a weak lateral tubercle. Some ribs terminate in the ventral tubercles, and other ribs terminate freely high on the flanks or between the ventral 

tubercles. The ventral tubercles generally mark the 

termination of two adjoining ribs that may or may not 

arise as a pair from an umbilical tubercle. The venter 

is nearly smooth except for broad undulations connecting the ventral tubercles. Faint flexuous striae are 

present on the flanks and the venter.

The specimen at a diameter of 62 mm has a whorl 

height of 25 mm, a whorl thickness of 20 mm, and a 

probable umbilical width of 21 mm. The whorl section before compression was probably a little thicker.

This species from Oregon is assigned to Neocosmoceras rather than Protacanthodiscus because of the 

presence of coarse unbranched widely spaced trituberculate ribs on its small septate whorls, of prominent 

widely spaced spirally elongate tubercles on the venter 

of its body chamber, and of forwardly arched flank 

ribs suggestive of lateral lappets at the adoral end of 

the body chamber. Protacanthodiscus, by contrast, has 

closely to moderately spaced biplicate ribs on its inner 

whorls; it does not develop umbilical tubercles until it

attains a fairly large size; its ventral tubercles on the 

adult body chamber are generally moderately to closely 

spaced and are arranged radially or tangentially; and 

its body chamber terminates simply instead of bearing 

lateral lappets.

Neocosmoceras euchrense Imlay and Jones, n. sp. is 

similar in side view to Distoloceras sp. of Anderson 

(1945, p. 983, pi. 14, fig. 4), which is recorded from 

1,200 feet west of the iron bridge across Grndstone 

Creek, Glenn County, Calif. Unfortunately tl °- specimen was not described and now appears to be lost. It 

was found at the same locality as Protacanthodiscus 

taffi (Anderson), redescribed herein, and could be an 

adult of that species.

N. euchrense differs from most species of Neocosmoceras by having somewhat weaker ornamentation 

and a more compressed whorl section. It shows some 

resemblance to a plesiotype of N. sayni (Simionescu) 

illustrated by Mazenot (1939, pi. 28, figs. 9a, b) but has 

less evolute coiling, weaker tubercles, and finer ribs. It 

differs from N. peromatus (Retowski) (1893, p. 270, pi. 

12, fig. 5) by having stronger tubercles and slightly 

weaker ribs. Its outermost septate whorl has much 

stronger ribbing than the fragmentary probable holotype of N. ? crossi (Anderson) illustrated herein.

Type. Holotype, USNM 158851.

Occurrence. In Oregon from outcrops along a 

beach at USGS Mesozoic loc. 2074 in association with 

Proniceras sp. juv., abundant Buchia uncitoides (Pavlow), and a few specimens of B. piochii (Gabb). The 

two species of Buchia are preserved in a sligMly different colored matrix, which suggests that tl °,y were 

collected from different beds.

Neocosmoceras? cross! (Anderson) 

Plate 14, figures 20-22

Protacanthodiscus crossi Anderson, 1945, Geol. Soc. America 

Bull., v. 56, p. 984.

This species was not illustrated by Anderson, but 

one fragment of a whorl in the California Acrdemy of 

Sciences fits the description fairly well, is from the 

correct locality, and is labeled "apparently holotype/'

The whorl fragment is subquadrate in section and 

is a little wider than high. It is characterized by the 

presence of widely spaced ventral and lateral tubercles and by widely spaced weak ribs. The ventral tubercles are prominent and spirally elongate. The lateral tubercles are weak and radially elongate. The 

flanks are almost smooth but bear variably weak forwardly inclined ribs of which some are connected with 

the lateral and ventral tubercles. The venter is even 

smoother than the flanks but bears faint traces of ribs
AMMONITES FROM THE BUCHIA ZONES P53

and striae. The umbilical edge and wall are not preserved. The dorsum bears the imprint of the venter of 

an inner whorl. This venter has a smooth midventral 

area and many low, broad, evenly spaced ribs that 

terminate ventrally in conical ventral tubercles. Evidently the venter of the inner whorl has much denser 

and more regular ribbing and tuberculation than the 

venter of the outer whorl.

The holotype of PA crossi Anderson is too fragmentary to warrant a positive generic identification, 

although the presence of prominent widely spaced, 

spirally arranged ventral tubercles suggests an assignment to N eocosmoceras rather than Protacanthodiscus. 

Also it shows some resemblance to the outermost septate whorl of the specimen of Neocosmoceras from 

Oregon described herein.

Type. Holotype, GAS 10448.

Occurrence. In California at CAS loc. 28667.

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INDEX

[Italic page numbers icdicate both major references and descriptions]

Acanthodiscus . -. ____._..__......_...... B18

acuticosta, Blanfordiceras... ............_.... 4,41

Age, ammonite faunules-.......- ........... 11

aguilerae, Proniceras.......................... 33

albani, Zaraiskites............................ 11

alticostatujn, Substeueroceras.................. 42

anabarensis, Tollia............................ 37

Anatiamulina,.--.............................. 30

wllcoxi................................... 30

analogue, Surites.............................. 13

appeninicum, Phylloceras..................... 28

atherstoni, Olcostephanus.............. 17, 38; pis.8,9

A ucella.-------------------................... 43

fischeri................................... 43

stantoni.................................. 43

Aulacosphinctes.................. 2, 4,5,11, 48; pi. 12

colusaensis................................ 29

diabloensis............................ 46; pi. 12

jenkinsi............................... 47; pi. 12

reedL------........................... 45; pi. 11

taffi...................................... 43

watsonensis........................... 46,"pl. 11

Aulacosphinctoides............................ 11

aulaeum, Lytoceras........................... 29

australis, Hoplites............................ 4,41

B

Bagley Creek..__.......................... 46

bayleyi, Groebericeras............... 2, 35; pis. 5,6,15

Berriasella............................... 4,41,42,43

californicum.............................. 42

calisto.---................................ 42

calistoides................................. 12,46

oppeli.................................... 42

picteti................... ...-.--....-.._ 41

storrsL.......................... 12,42,44; pi. 10

Berriasellidae..........______ _ ______. 2,4,^0

Berriaselllnae-- _-. ._ 4

bifrons, Groebericeras.......................... 36

bifurcatum, Parodontoceras.................... 46,47

Biologic analysis...__ ___._- ______- 2

blanfordiana, Buchia.......................... 12

Blanfordiceras................ 4, 5,12,18, 40,41; pi. 10

acuticosta............._................... 4,41

californicum........................ 40,41; pi. 10

molinensis................................ 41

rotundidoma.............................. 41

wallkhi................................. 4,40,41

Bochianites................................. 2,1S,SO

glennensis............................ 2,30; pi. 1

paskentaensis....................... 10,30; -pi. 1

Bochianitidae.. _-__-__- ____ 30

bojarkensis, Homolsoinites..................... 17

Boreal region. _________...____________________ 11

Buchia....-............ .................... 5,10

blanfordiana.............................. 12

zone....--....-.-.-.....----.......... 12

crassicollis. ............................... 15

zone.................................. 15,17

solida................................. 10

zone, Valaiiginian ammonites....... 10, 17

elderensis............ ................... 12

keyserlingi... .................... 10,39,48,49,51

zone, Valanginian ammonites......... 10, 16

Buchia Continued

mosquensis............ ................ B11.12

okensis ..... 5,10,13,18,29,33,34,35,43,45,46

zone, Tithonian ammonites. _________ 10, IS

pacifica. _.___.____ 10,16,17,30,31,38,48,49, 50,51

zone, Valanginian ammonites_. _____ 14,16 

piochii..- _ 5,10,12,13,18,28,29,32,34,36,45,46,52

zone, Tithonian ammonites. --------- 11

rugosa. ___________________________________ 11

sollasL................................... 12

sublaevis.................................. 17

terebratuloides. ____________________________ 13,43

tolmatschow i.............................. 15,16

zone......---........--.._.-....-.._-.15,16

uncitoides....... 5,10,17,18,32,33,31,35,41,42,52

zone, Berriasian ammonites__ _..... 1%

burckhardti, Spiticeras... ______________________ 34

burgeri, Dichotomites.......................... 36

Tolliamutabilis........................ 38; pi. 8

(Tollia) mutabilis......... ............ 15

Burt's Kanch house----.-----..-.-..--.--..-- 48

C 

californicum, Berriasella...................... 42

Blanfordiceras..................... 40, 41; pi. 10

Thurmanniceras................ ........ 48

calisto, Berriasella............................ 42

Hoplites.. ................................ 44,46

calistoides, Berriasella.-..--..... ..-. -.-. 46

Parodontoceras...................... 12,44,45,46

Calliphylloceras............................... 28

Calliphylloceratinae.------------------------ 29

campylotoxa, Sarasinella...................... 51

capellense, Phylloceras..................... 28; pi. 2

cautleyi, Spiticeras (Spiticeras)..---..--.... S3; pi. 3

chichalensis, Sarasinella..--................... 51

colusaense, Lytoceras........................... 89; 2

colusaensis, Aulacosphinctes................... 89

Colyear Springs quadrangle.....---------.- 10,16,17

Comparisons of ammonites with other ammonite faunules-.....--------.-.-.-- 17

Contra Costa County.... .... . --....._ 46

contrarium, Phylloceras.................. 2, 28; pi. 1

Corning, Calif - -- --------------- 5

Corongoceras............ .... .............. 11

Correlation, ammonite faunules-..----.--...- 11

Cottonwood Creek............................. 10

Craspeditidae--- 15

crassicollis, Buchia........................ .. 15

solida, Buchia............................ 10

crassicostata, Tollia mutabttis........ .... 38; pi. 8

crassiplicata, Kilianella................ 48,50; pi. 14

Cretaceous ammonites- -______.--. - --. 1%

Crioceratites.................................. 16,18

sp.-------................... -- 10

crossi, Neocosmoceras...................... 5%; pi. 14

Protacanthodiscus......................... 52

curacoensis, Olcostephanus.................... 39

D

damesi, Spiticeras (Kilianiceras).............. 34

Days Creek..._._.. __ ._.__........ 11,13,17

densicosta, Polyptychites....................... 40

diabloensis, Aulacosphinctes............... .46; pi. 12

Page 

Dichotomites.............. ... . B14,15,17,40

burgeri................................... 36

giganteus................................. 14,15

gregerseni................................. 36

paucieostata.......................... 38

mutabilis............... ------------------ 36

tehamaensis............................... 14,35

trichotomus............................... 39

DiUard, Oreg...... - ..-.. ---- 10

diUeri, Hoplites................ .- . 30,46

Kossmatia.......................... 30, 31; pi. 3

disputabtte, Substeueroceras...----............ 42

Distoloceras sp. --------------------- .-.. 4.3,51

Dorsoplanites panderL...............-..--.... 11

zone...---.---- -.- -------- ------ 11

Douglas County, Oreg------..--.. -------- 11

Durangites.... ... ------------------------- H

E

Elder Creek______.. . - 10 

MiddleFork.. 32

North Fork....-..-.-....-. --- 31

Elder Creek fault.--------------------------- 17

elderensis, Buchia-... ___ .- --_- 12

Elk Creek-..-------------------------------- 5

Epicephalites. -------------------------------- H

euchrense, Neocosmoceras........... 32, 43, 51; pi. 14

Euryptychites.-----.----.--------------- 14,15

exoticum, Lytoceras..-..--.-..----- 29, 43; pi. 2

F

fasciatum, Substeueroceras.. ... ... ......... 43

fischeri, Aucella. ... ...... ... ....... --- --- 43

G 

Geographic distribution.. .....-. . ---.. - 19

giganteus, Dichotomites. ---------------------- H 15

Neocraspedites . ..... ------------------- 14,16

gigas, Spiticeras (Kilianiceras) ..... ... .. .. 34

Glenn County--. -- -- -- ---------- 52

glennense, Phylloceras. --------------------- #8; pi- 1

glennensis, Bochianites ...... .......- --- 2, 30; pi. 1

gracile, Proniceras. .-...---. ---------------- 33

gregerseni, Dichotomites ----------------------- 36

paucieostata, Dichotomites ----------------- 38

Grindstone Creek----..---------------- 10,44,52

Groebericeras--.-. ............... 2,3,5,11,17,35,36

yi.- - --.-.- - 2, 35; pis. 5, 6, 15

-...-- --------------------------- 36

H 

Hamulina rosariensis. ......... ... . -- 30

Hemispiticeras. .... ....... ... ... - - .. . 47

steinmanni. .. ... ... ... ....... ..---. ---- 48

Hertleinitespecki. .............. .----------- 49

Hildoglochiceras .... ....-.--------------------- H

Himalayitinae ----------------------------- 4

Homolsomites... ................. 3, 4, 10, 15, 17, 1?,37

bojarkensis.. . - -- 17

mutabilis-.....--- .. . -- - - 36,37

quatsinoensis - --.... -------------------- 11,17

stantoni-----..--...---.- --------------- ^

B57
B58 INDEX

Page 

Hoplites australis............................ B4,41

caZisfo.................................... 44,46

dilleri... .................................. SO,46

storrsi.................................... 44, 46

hoplitoides, Temnoptychites..------------------ 14

Hull's gate.----------..-----................. 11

hyatti, Sarasinella...... ..........-_._..-_ . 10,14

jacobi, Proniceras----------------------------- 32

jeannoti, O?cos?ep/ia«us.______________________ 17

jenkinsi,Aulacosphinctes .................. 47; pi. 12

Thurmanniceras--------- 10, 16, 39, 48, 49; pi. 13

Jurassic ammonites._______________________ _ _ 11

kellumi, Substeueroceras- . ___ - 12,45; pi. 10

keyserlingi, Buchia _ _______________ 10, 39,48, 49, 51

Polyptychites--.. ________________________ 39

Kilianella---. ___.__._____.__.__-_ 4,5,10,14,18,50

crassiplicata.--. ____________________ 48,50; pi. 14

roubaudi- _________________________________ 50

Killaniceras ________ __- _______ ______ 2, 3,34

(Kilianiceras) damesi, SpiticeraS-- _____________ 34

gigas, Spiticeras- __________________________ 34

SpiticeraS- _____________ 10,13,18,34,36, 48; pi. 3

Kleinsorg chromite mine _____________________ 32

klelnsorgensls, Kossmatia---- ............... .?^; pi. 3

knoicillense, Phylloceras--^--. ___________ ?S, 46; pi. 2

koeneni, Substeueroceras-------------------. 12,42,43

Kossmatia. ................. 2,4, 5,11,17,30,31,46,47

dilleri--. ....__._.._______________._ 30,31; pi. 3

kleinsorgensis ___________________________ 3J; pi. 3

pectinata --_..-__-_.______________-_____-.. 32

tehamaensis---------------------------- 31; pi. 3

victoris-----....-..-._-____.___.-__-..__-.. 31

lamellicostatum , Substeuerocerasliebigi, Lytoceras. ___.-_....____

Lowrey's Ranch house. .__._...

5,10,

colusaense.- .-----.-.---............... 39

eioticuni-- __________________________ 29,43

Zz'e&M/' ------------------------- -------- 29

saturnale. ____________________________

Lytoceratidae --_________-_ __._ ______

42

pi. 2 

31

18,29 

29

; pi. 2 

pi. 2 

; pi. 2 

10, 22

M 

McCarty Creek___ _ ___________________________ 48

madagascariensis, Olcostephanus-----. _________ 39

maupinense, Proniceras -- -... _____________ 35; pi. 3

michalskii, Polyptychites----- _________________ 13,16

Micracanthoceras.- ---.------.................. 11

Mill Creek___. ----.-_-.._-_________._-_____._. 48

molinensis, Blanfordiceras -------- ............. 41

mosquensis, Buchia. -------------------------- 11, 12

Mount Diablo-------------------------------- 46

mutabilis burgeri, Tollia,---. ________________ 38; pi. 8

burgeri, Tollia (Tollia).-.. ________________ 15

crassicostata, Tollia-----. ______________ 38; pi. 8

D i'c/i o_o )?u7f s _ _ __ _ _._ __._ 36 

Homolsomites- ......................... ^.37.51

mutabilis, Tollia .......................... pi. 7

Olcostephanus... ....................... 15,37,38

(Simbirskites) ......................... 36

Subcraspedites . . . _____ _ ______ ____ 35

tehamaensis, Tollia. ....................... 14,15

ToZZfa (roZZ.fl) --.- ---- .. 15

To-.fa ---------------- 10, 14, 15, 16, Sfi, 38; pi. 7

mutabilis.-.. .......................... pi. 7

(Tollia). ........................... 15,16,37

N Page 

negreli, Spiticeras (Negreliceras).... ........... B34

Negreliceras................................. 3,12,34

(Negreliceras) negreli, Spiticeras............... 34

paranegreli, Spiticeras..................... 35

planissimum, Spiticeras................... 35

Spiticeras... .................. 10,12,13,18,33,36

stonyense, Spiticeras.................... 34; pi. 4

neocomiensis, Neocomites.................. 49; pi. 14

premolica, Neocomites................. 50; pi. 14

subtenuis, Neocomites..................... 50

Neocomites..................... 2,4,5,10,15,16,18,49

neocomiensis.......................... 40.' pi-14

premolica......................... 50; pi. 14

stippi ................................... 48

subtenuis............................. 50

loichmanni......................... 49,50; pi. 14

(Parandiceras) rota........................ 15

Neocomitinae.------------------------------- 4

Neocosmoceras................. 2,4,5,10,13,18,43,5i

cross....._.....--.---.-----.__----_ 52; pi. 14

euchrense..-..................... 32,43,5;,- pi. 14

perornatus................................ 52

sayni..................................... 52

2Veoer<ispe<....-s__..---.-.----.--------- 10,14,16,18

giganteus................................ 14,16

Nevada Creek ------------------------------ 49

O

obliquenodosum, Spiticeras..................... 33,34

Spiticeras (Spiticeras)..................... pi. 3

okensis, Buchia..... 5,10,13,18,29,33,34,35,43,45,46

Olcostephanidae._______.----___------_----- 2,15,32

Olcostephaninae..-------.---..----..--...--.. 3

Olcostephanus.---..-...-.---. 2,3,10,16,17,18,38,39 

atherstoni......................... 17,38; pis. 8,9

curacoensis................................ 39

jeannoti--.....--...-..---.-.........-.---- 17

madagascariensis-......................... 39

»7ii..ab.Z/s------------------------------ 15,37,38

pecki.. ................................. 10,17

._..._............-...- 11

....................... 15

popenoz....----------------

quatsinoensis...............

(Polyptychites trichotomus.

(Simbirskites) mutabilis.....

oppeli, Berriasella....----------

Orland, Calif.......-.--.......

ovatus, Inoceramus. ------------

36

42

5

43

paciftca, Buchia... . ___ 10,16,17, 30,34,38,48,49, 50,51

pakhsaensis, Tollia-.-------------------------- 37

panderi, Dorsoplanites.... .-_-___- ----------- 11

paramacilenta, Parodontoceras.---------------- 44

Parandiceras.... ------------------------------ 15

(Parandiceras) rota, Neocomites.... _ ____ __- 15

paranegreli, Spiticeras (Negreliceras) __ _-.- 35 

Parodontoceras..- ____________ 4,5,11,12,17,42,44,46

bifurcatum,-------------------------------- 46,47

calistoides.---------------------- 12,44,45,46

paramacilenta_.. -------------------------- 44

ponticum ------------------------------- 46

reedt..-.-- - -- . 12,44,45; pis. 11,12 

storrsi....-.-.-..-----..---.. 28,44,45,46; pi. 12

Paskenta, Calif...__----_------- --.- 5,10,37

Paskenta quadrangle.-.__-_._____-- 11,16,32,48,49

paskentaensis, Bochianites.-------------- 10,30; pi. 1

Paskentites..---.---------------------- 47; pi. 13

Paskentites.---------------------------- 4,5,10,47

paskentaensis....--------------------- 47; pi. 13

paucicostata, Dichotom ites gregerseni ----------- 38

Tollia.--..........---.-.--.---. 14,15,16,38

(Tollia). ----------------------------- 15

pecki, Hertleinites,- -------------------------- 49

Olcostephanus................-.--. -- 10,17

pectinata, Kossmatia.................-.-.--- 32

Perisphinctidae -__----------------_------- 2,30

permulticostatum, Substeueroceras............. 43

Page 

perornatus, Neocosmoceras..................... B52

Phylloceras..-........................ 2.5,10,18,28

appeninicum.............................. 28

capellense.............................. 28;pi.2

contrarium........................... 2,28; pi. 1

(/ZeraTzeTzse.----------------------------- 28;pi. 1

knoxvillense......------------------- 28,46; pi. 2

Phylloceratidae..___-_____________-___--.--_ 28

PhyUocerathiae......------------------------- 29

picteti, Berriasella...-------------------------- 41

piochii, Buchia,.------------------------------ 5,

10,12,13,18,28,29,32,34,36,45,46,52 

planissimum, Spiticeras (Negreliceras)..-...-.- 35 

Polyptychites.................. 2,3,10,14,15,16,18,30

densicosta................................. 40

keyserlingi.. ----------------------------- 39

michalskii................................. 13,16

zone...-__--------___---.---_---_----- 13,16

ramulicosta......-..........--........---. 40

trichotomus....---------------------- 10,30; pi. 8

sp.---.-...-- ----------------- -- 30; pis. 7, 9

(Polyptychites) trichotomus, Olcostephanus..... 30

Polyptychithiae.----------------------------- 3,14

ponticum, Parodontoceras...----------------- 46

popenoi, Olcostephanus. --------------------- 11

poreckoensis, Surites_...-...........---...-- 16

premolica, Neocomites neocomiensis..---- 50; pi. 14

Proniceras...........2, 3, 5,10,12,17,33, 36, 52; pi. 3

aguilerae.---......................-------- 33

graciZe..---------------------------------- 33

jacobL ------------------------------------ 32

maupinense........................... 3S; pi. 3

Protacanthodiscus................ 4, 5,13 18,43, 52, 53

crossi...-... . .----.- -- -------- 52

taffl...._.--------------------------- 43, 52; pi. 6

sp--_._----------------------------------- 43

Protancyloceras............................... 30

proteus, Spiticeras............................. 35

Pseudoblanfordia.............................. 4,41

Pseudolissoceras..... -------------------------- 11

quatsinoensis, Homolsomites................... 11,17

Olcostephanus............................. 15

R

ramulicosta, Polyptychites..................... 40

Red Bluff quadrangle.-----..------ -------- 31

reedi, Aulacosphinctes. -------------------- 4^; pi. 11

Parodontoceras.............. 12,44,45; pis. 11,12

Riddle, Oreg..------------------------------- 14,17

Riddle Formation..-----.-------------------- 13

rosariensis, Hamulina.. ---------------------- 30

rota, Neocomites (Parandiceras)....----------- 15

rotundidoma, Blanfordiceras................... 41

roubaudi, Kilianetta... ------------------------ 50

rugosa, Buchia..---.-------------------------- H

S 

Sacramento Valley... ._..-. --------- 29

santarosanum, Substeureroceras................ 47

Sarasinetta..... -------------- 4,5,10,14,16,18,50

campylotoia.... --------------------------- 51

chichalensis. __-... ---------------------- 51

hyatti..- ---------------------------------- 10' 14

subsp'mosa.-------------------------- SO; pi. 12

uhligi. ------------------- 51; pi. 12

saturnale, Lytoceras..------------------------- 10,29

sayni, Neocosmoceras ----------------------- 52

serpentinum, Spiticeras.... -------------------- 33,34

Spiticeras (Spiticeras)....----.----------- pi- 3

(Simbirskites) mutabilis, Olcostephanus.....-.-- 36

simplex, Tollia (Tollia).......---------------- 15,16

sokolovi, SubpZantos..------------------ - H

solida, Buchia crassicollis.........------------- 10
INDEX B59

Page 

sollasi, Buchia..... ... .................. B12

South UmpquaRiver.-__-_____._.._.-.- 11,13,17

spasskensis, Surites........................... 13,14

Speetoniceras................................. 47

Spiticeras....- --- 2,3,5,10,11,13,17,18,32,33,36

burckhardti.... ..................-....... 34

obliquenodosum--.----..---............._. 33,34

proteus...... __________-___..-_._-____.-_. 35

serpentinum. ---__-_--__.___-_____________ 33,34

uhligi...--------.--.------- --- . 33,34

(Kilianiceras) -------------- 10,13,18,34,48; pi. 3

damesi. - _____ __. 34

gigas....... ..... ................ 34

(Negreliceras).___-___._._-..__ 10,12,13,18,33,36 

negreli..-. .---............-. .---.. 34

paranegreli.................... .----. 35

planissimum. -----------..-... ...... 35

stony ense.. ........ ........... 34; pi. 4

(Spiticeras)................... 10,12,13,34; pi. 3

ca wffe ff i---------------------------- S3; pi. 3

obliquenodosum. -_----__-_____________ pi.3

serpentinum...................._..... pi,3

uhligi.-.--.-..-----.-......-.... pi.3

spp -_-------------------______________ 35

(Spiticeras) cautleyi, Spiticeras.... ____.___._ 33;pi. 3

obliquenodosum, Spiticeras................. pi. 3

serpentinum, Spiticeras..... .__._____..____ pi. 3

Spiticeras.-..-................ 10,12,13,34; pi.3

MMigi/, Spiticeras........ --_____._._____. pi. 3

spp., Spiticeras.......... ...._._._..____ 33

Spiticeratinae. ---_-_-__.______-._.___.___.__. 2,36

stantoni, Aucella..-..-.--.-.................._ 43

Homolsomites. ---.- . ... ......... 17

Inoceramus......-- ..--.-.---........._. 43,44

Substeueroceras. -............. 12, 4%, 47; pi. 10

steinmanni, Hemispiticeras.................... 48

Stephanoceras... . -.--.-.. . ............_. 5

steueri, Substeueroceras..- ....--... . .____ 43

stippi, Neocomites..-.... .................... 43

Thurmanniceras____- ..-. ... 10, 48; pi. 13 

stonyense, Spiticeras (Negreliceras).......... 34; pi. 4

storrsi, Berriasella... _____._-__-____. 12,45,44; pi. 10

flbpZae*.-.. .......................... 4.4,46

Parodontoceras.............. 28, 44, 45, 46; pi. 12

Stratigraphic relationships of ammonites to

Buchias. -------..---............. 5

Subcraspedites mutabilis.....-.-.-..._.___.____ 36

sublaevis, Buchia.............................. 17

Subneumayria............................._ n

Subplanites.

Spp ----------------------------------

zone... -------------------------------

subquadratum, Substeueroceras. ...............

subspinosa, Sarasijlella. ................... BO;

Substeueroceras ............... 4, 5, 1 1, 12, 17, 18,

disputabile .

intercostatum .... . .........................

kettumi. ........................... 12,42;

koeneni. ------------------------------- 12,

latnellicostatum ..... .................... -

permulticostatum... -----------------------

santarosanum. ----------------------------

stantoni....... .......... ....... 12, #, 47;

sfewen. ---------------- -------------------

subquadratum ... ..........................

subtenuis, Neocomites neocomiensis . ...........

Subthurmannia ............-..-.-.---.------..

Surites analogus . . ................ ... ---------

analogus subzone ___ _- 

poreckoensis .... . ..........................

spasskensis ...............................

zone... ------------------------ -------

Page 

Bll

11 

11 

11 

11

12,42 

pi. 12 

,#,46 

42

42

43 

42

pi. 10 

, 42,43

42

43 

47

pi. 10 

43

12,42 

50 

4,49 

13 

13 

16

13,14

13,14

T 

taffi, Aulacosphinctes.......................... 4s

Protacanthodiscus................... 48, 52; pi. 6

tehamaensis, Dichotomies..................... 14,35

Kossmatia.............................. 31; pi. 3

Tollia mutabilis........................... 14,15

(Tollia) mutabilis..................... 15

Temnoptych ites............................... 16

hoplitoides................................ 14

zone....-- ___ ______.- - 14

terebratllloides, Buchia___-. - .._-.------ 13,43

Thurmanniceras......... 2,4, 5,10,14,16,18, 48, 49,50

californicum.............................. 48

jenkinsi... ............... 10, 16, 39, 48, 49; pi. 13

stippi.............................. 10, 48; pi. 13

tolli, Tollia................................. 13

...................... 2,3,4,14,15,16,18,36

anabarensis............................... 37

mutabilis........... 10, 14, 15, 16, 36, 38, 51; pi. 7

burgeri............................. 38; pi. 8

crassicostata........................ 38; pi. 8

Tollia Continued rage 

mutabilis Continued

mutabilis...------ .................. pi. 7

tehamaensis......................... B14,15

- ._.. -- - 37 

. .. - 14,15,19,38

tolli...................................... 13

zone----------.-------------------- . 13

(Tollia) mutabilis...................... 15,11,87

mutabilis burgeri..-----.~.~ ....... 15

tehamaensis......................... 15

paucicostata.. -. . ---- 15

simplex.--.......................... 15,16

( Tollia) mutabilis, Tollia................... 15,1%87

mutabilis burgeri, Tollia................... 15

tehamaensis, Tollia.................... 15

paucicostata, Tollia....................... 15

simplex, Tollia............................ 15,16

TollLinae.- ----------------------- 3,16

tolmatschowi, Buchia.......................... 15,16

trichotomus, Dichotomites...................... 39

Olcostephanus (Polyptychites)......... .... 39

Polyptychites....................... 10, 39; pi. 8

U 

uhligi, Sarasinella....-.. .- --....- 51;p\12

Spiticeras................................. 33,34

(Spiticeras)........................... pi. 3

uncitoides, Buchia. . 5,10,17,18,32,33,34,35,41,42,52

V 

victoris, Kossmatia............................ 31

Vhialesphinctes ............................... 30

W 

wallichi, Blanfordiceras..................... 4,40,41

Watson Creek._-_ - 44

watsonensis,Aulacosphinctes......-....-.- ^/p1 . 11

WeUsia...- .......................... 4

wichmanni, Neocomites .............. 49, 50; p\ 14

Wilbur Springs.- . - -- - 37 

Wilbur Springs quadrangle. . ... 38 

Wilcox Ranch house.----------------------- 31,48

wilcoxi, Anahamulina......................... 30

Windhauseniceras............................. 47

ZaraiskUes albani............................. 11

zone.--.------ ------- --------------- 11

zitteli, PseudoHtsoceras........................ 11

PLATES 1-15
PLATE 1

[All figures natural size unless otherwise indicated]

FIGURES 1-8. Phylloceras? contrarium Imlay and Jones, n. sp. (p. B28).

1-3. Paratype, USNM 158806 from USGS Mesozoic loc. M2605. Shows adapically inclined 

ribbing on the upper parts of the flanks.

4. Suture line (X 2) of paratype, USNM 158807 from USGS Mesozoic loc. 29489. Suture 

line drawn at diameter of 30 mm and whorl height of 19 mm.

5. Lateral view of small nearly smooth paratype, USNM 158805 from USGS Mesozoic loc.

M2605. 

6-8. Cross section and ventral and lateral views of holotype, USNM 158804 from USGS

Mesozoic loc. 29493. Ventral view is oriented with adoral end down. 

9, 10. Phylloceras glennense Anderson (p. B28).

Holotype GAS 8720 from GAS loc. 28037. 

11, 12. Bochianites? glennensis Anderson (p. B30).

Ventral and lateral views of holotype, GAS 5959 from GAS loc. 28037. Generic assignment is

questioned because ribs cross venter transversely. 

13-15. Bochianites paskentaensis Anderson (p. B30).

13. Lateral view of a large nonseptate fragment of hypotype, USNM 161185 from USGS 

Mesozoic loc. 29595. Adoral end is on left.

14. 15. Lateral and ventral views (X 2) of hypotype, USNM 161184 from USGS Mesozoic 

loc. 29595. Adoral end is on right.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 1

PHYLLOCERAS, PHYLLOCERASt, BOCHIANITES1, AND BOCHIANITES
PLATE 2

[All figures natural size]

FIGURES 1-3. Lytoceras colusaense (Anderson) (p. B29).

1. Holotype, CAS 10446 from CAS loc. 28842.

2. Hypotype, CAS 10462 from CAS loc. 28037. Described by Anderson (1945, p. 977) as 

Lytoceras aff. L. exoticum Oppel.

3. Hypotype, CAS 10461 from CAS loc. 28037. Described by Anderson (1945, p. 977) as

Lytoceras aff. L. liebigi (Oppel). 

4-11. Phylloceras knoxvillense Stanton (p. B28).

4. 8. Hypotype, CAS 8735 from CAS loc. 28037.

5. Hypotype, CAS 8716 from CAS loc. 28494. Described by Anderson (1945, p. 977) as 

holotype of P. capellense Anderson.

6. 7. Hypotype, USNM 158803 from USGS Mesozoic loc. 29558. 

9-11. Holotype, USNM 23083 from USGS Mesozoic loc. 1084.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 2 

ft&~

^SS^S'1 ""*- "'"' ^&!§Sr"~^ yf^v

^^ * " lrO'%^ t^*^?"~j..f "V ££^ 'i "^-^- --*^* ^ (. r ^' **' t

\\\\\\ ^"^ -" »V*^<':r. '<Sfr*-*' -$-^ tf'^"l W". * N^m. -t^v-rs^ -?.-^^. ^ '-^fe

- ..

LYTOCERAS AND PHYLLOCERAS
PLATE 3

[All figures natural size unless otherwise indicated]

FIGURES 1, 2. Kosfmatia tehamaensis Anderson (p. B31).

Holotype, UC 5956 from UC loc. A-2921. 

3, 4. Kossmatia kleinsorgensis Anderson (p. B31).

Holotype, CAS 8711 from CAS unnumbered locality 1 mile east of the Kleinsorg mine in

sec. 26, T. 25 N., R. 7 W., Paskenta quadrangle, California. 

5-7. Kossmatia dUleri (Stanton) (p. B30).

Holotype, USNM 21573 from USGS Mesozoic loc. 666. 

8, 11-16. Proniceras maupinense Imlay and Jones, n. sp. (p. B32).

8. Rubber imprint of external mold of paratype, USNM 161189 from USGS Mesozoic loc.

29592.

11, 12. Holotype, USNM 161186 from USGS Mesozoic loc. 29589. 

13, 14. Lateral view and suture line (X 4) (drawn at whorl height of 8 mm) of paratype

USNM 161187 from USGS Mesozoic loc. 29589. 

15, 16. Internal mold with some shell adhering and rubber imprint of external mold of

paratype, USNM 161188 from USGS Mesozoic loc. 29591. 

9, 10. Proniceras sp. juv. (p. B32)

Ventral and lateral view (X 2) of specimen, USNM 158808 from USGS Mesozoic loc. 2074.

17. Spiticeras (Spiticeras) cf. S. (S.) obliquenodosum Retowski (p. B33).

Laterally crushed internal mold with some shell adhering of specimen, USNM 158812 from 

USGS Mesozoic loc. M2253.

18. Spiticeras (Spiticeras) cf. S. (S). uhligi Burckhardt (p. B33).

Rubber imprint of external mold of specimen, USNM 158811 from USGS Mesozoic loc.

M3092. 

19,21. Spiticeras (KUianicerasf) sp. juv. (p. B34).

Lateral views of internal molds of specimens, USNM 158814 from USGS Mesozoic loc.

24702. 

20. Spiticeras (Spiticeras) cf. S. (S). serpentinum Burckhardt (p. B33).

Rubber imprint of external mold of specimen, USNM 158810 from USGS Mesozoic loc.

M2598. 

22,25. Spiticeras (Spiticeras^) n. sp. undet. (p. B34).

Laterally crushed internal molds retaining some shell material. Note lateral lappet in figure

25. Specimens, USNM 158813 from USGS Mesozoic loc. M2605. 

23,24. Spiticeras (Spiticeras) cf. S. (S). cautleyi (Oppel) (p. B33).

23. Internal mold with some shell adhering. Specimen, USNM 158809 from USGS Mesozoic 

loc. 3348.

24. Rubber imprint of external mold of same specimen shown in figure 23.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 3

i&a x2i/^

Mmw:

KOSSMATIA, PRONICERAS, SPITICERAS, AND S. (KILLIANICERAS1)
PLATE 4

[All figures natural size]

FIGURES 1-22. Spiticeras (Negrdiceras) stonyense Imlay and Jones, n. sp. (p. B34). 

1, 2. Ventral and lateral views of paratype, USNM 158826. 

3, 4. Ventral and lateral view« of paratype, USNM 158822.

5. 10. Paratype, USNM 158823.

6. Paratype, USNM 158820.

7. Paratype, USNM 158825.

8. Paratype, USNM 158818.

9. Paratype, USNM 158827 from USGS Mesozoic loc. 3348.

11. Paratype, USNM 158833 from USGS Mesozoic loc. M4066.

12. Paratype, USNM 158831 from USGS Mesozoic loc. M4066.

13. Paratype, USNM 158832 from USGS Mesozoic loc. M4066.

14. Paratype, USNM 158829 from USGS Mesozoic loc. M2025.

15. Paratype, USNM 158819.

16. Paratype, USNM 158828 from USGS Mesozoic loc. 29505.

17. Paratype, USNM 158817.

18. Paratype, USNM 158821.

19. Paratype, USNM 158830 from USGS Mesozoic loc. M3096.

20. Paratype, USNM 158816.

21. Holotype, USNM 158815.

22. Paratype, USNM 158824.

All specimens shown in figures 1-8, 10, 15, 17, 18, 20-22 are from USGS Mesozoic loc. 2286.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 4

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SPITICERAS
PLATE 5

[Figure reduced to four-fifths natural size]

Groebericeras"! batteyi Imlay and Jones, n. sp. (p. B35).

Rubber imprint (X ^) of external mold of holotype, USNM 158834 from USGS Mesozoic loc. M2024. 

Other views of same specimen are shown on plate 6, figures 1, 2, 5, 6, 8 11.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 5

GROEBERICERAS1
PLATE 6

[Figures natural size unless otherwise indicated]

FIGURES 1, 2, 5, 6, 8-11. Groebericerasi baileyi Imlay and Jones, n. sp. (p. B35).

1. 5, 6, 11. Cross section, ventral, lateral, and apertural views of moderately 

small septate whorls of holotype, USNM 158834 from USGS Mesozoic loc. 

M2024.

2. Outer septate whorls of holotype (X ^2). The smallest whorl is next larger

than the outermost shown in figure 6. The largest whorl is the same as the

fragmentary outermost whorl shown on plate 5. 

8-10. Apertural, ventral, and lateral views of smallest whorls of holotype. Chevron

arrangement of ribs present on venter. 

3, 4, 7. Protacanthodiscus taffi (Anderson) (p. B43). 

3, 4. Ventral and lateral views of holotype. 

7. Lateral view of rubber imprint of external mold of holotype, CAS 8709 from

CAS locality on Grindstone Creek near CAS loc. 28037.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 6

iQ^Bfc&./lJfe^

GROEBERICERASl AND PROTACANTHODISCUS

11
PLATE 7

[Figures natural size unless otherwise indicated]

FIGURES 1, 2, 4-12. Tollia mutabilis mutabilis (Stanton) (p. B36).

1. Hypotype, USNM 161196 from USGS Mesozoic loc. M3061.

2. Hypotype, USNM 161195 from USGS Mesozoic loc. M3061.

4-7. Hypotype, USNM 161198 from USGS Mesozoic loc. 29594. Suture line (X 2) 

drawn at diamter of 26 mm and whorl height of 12 mm. Figure 7 (X 3), an enlargement of figure 4, shows details of suture line.

8. Hypotype, USNM 161194 from USGS Mesozoic loc. M3061.

9. Lectotype, USNM 230S9a from USGS Mesozoic loc. 1010. 

10-12. Hypotype, USNM 161197 from USGS Mesozoic loc. M3061. 

3. Polyptychites sp. (p. B39).

Lateral view of specimen, USNM 158839 from USGS Mesozoic loc. M1577. 

13, 14. Tollia cf. T. mutabilis (Stanton) (p. B37).

Lateral views of crushed and broken specimen, USNM 161203 from USGS Mesozoic 

loc. 29612. Shows complete body chamber. In figure 13 the adoral end of body chamber 

is missing on the flank but not on the venter.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 7

TOLLIA AND POLYPTYCHITES
PLATE 8

[Figures natural size unless otherwise indicated]

FIGURES 1-5. Tcilia mutabilis crassicostata Imlay (p. B38).

1. Hypotype, USNM 161199 from USGS Mesozoic loc. M3061.

2. Paratype, USNM 129692 from USGS Mesozoic loc. 1010.

3. Hypotype, USNM 161201 from USGS Mesozoic loc. M3061.

4. Hypotype, USNM 161200 from USGS Mesozoic loc. M3061.

5. Hypotype, USNM 161202 from USGS Mesozoic loc. M3061. 

6-10. Tollia mutabilis burgeri (Anderson) (p. B36).

6. 7. Suture line (X 2) and lateral view of hypotype, USNM 161192 from USGS Mesozoic loc.

M3061. Suture line measured at diameter of 30 mm and whorl height of 13.5 mm. 

8, 9. Ventral and lateral views of hypotype, USNM 161191 from USGS Mesozoic loc. M3061. 

10. Hypotype, USNM 161190 from USGS Mesozoic loc. M3061. 

11-14. Polyptychites trichotomus (Stanton) (p. B39).

Lateral, ventral, and apertural views of hypotype, USNM 161193 from USGS Mesozoic loc.

29616. 

15. Olcostephanus cf. O. atherstoni Baumberger (non Sharpe) (p. B38).

Apertural view of specimen, USNM 158835 from USGS Mesozoic loc. 29556. Other views on

plate 9, figures 1-3, 6-10.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 8

is ^^^r 14

TOLLIA, POLYPTYCHITES, AND OLCOSTEPHANUS

15
PLATE 9

[All figures natural size unless otherwise indicated]

FIGURES 1-3, 6-10. Olcostephanus cf. 0. atherstoni Baumberger (non Sharpe) (p. B38).

1. 3, 6. Apertural, ventral, and lateral views of specimen, USNM 158836 from USGS 

Mesozoic loc. 29555.

2. Lateral view of rubber imprint of external mold, USNM 158838 from USGS Mesozoic

loc. 29485. 

7, 8. Rubber imprints of external molds, USNM 158837 from USGS Mesozoic loc.

M2680. 

9, 10. Lateral and ventral views of specimen, USNM 158835 from USGS Mesozoic

loc. 29556. Apertural view is shown on plate 8, figure 15. 

4, 5. Polyptychites sp. (p. B39).

Ventral and lateral views (X 2) of specimen, USNM 158840 from USGS Mesozoic

loc. 29555.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 9

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OLCOSTEPHANUS AND POLYPTYCHITES
PLATE 10

[Figures natural size unless otherwise indicated]

FIGURES 1-5, 10. Blafordiceras californicum Imlay and Jones, n. sp. (p. B40).

1, 2, 10. Ventral and lateral views and suture line (X 4) drawn at whorl height of 8.5 mm.

Paratype, UC 10100 from UC loc. B-5120.

3, 4. Ventral and lateral views of internal mold of holotype, UC 10099 from UC loc. 

B-5120.

5. Rubber imprint of external mold of holotype, UC 10099 from UC loc. B-5120. 

6-9. Blanfordiceras sp. undet. (p. B41).

6. 7. Lateral and ventral views of largest specimen, UC 10101 from UC loc. B-5120.

Outermost one-fourth whorl is nonseptate. 

8, 9. Ventral and lateral views of rubber imprint of external mold of inner whorls of same

specimen shown in figures 6 and 7. 

11-18. Substeueroceras stantoni Anderson (p. B42).

11-13. Lateral and ventral views of paratype, GAS 10454 from GAS loc. 28037. Figure 12

is a rubber imprint of an external mold.

14. Lateral view of paratype, GAS 10453 from GAS loc. 28037.

15. 16. Ventral and lateral view of holotype, GAS 10452 from GAS loc. 28037. 

17, 18. Lateral and ventral views of paratype, GAS 10456 from GAS loc. 28037. 

19, 20. Substeueroceras cf. S. kellumi Imlay (p. B42).

Lateral and ventral views of specimen described by Anderson (1945, p. 980) as Berriasella 

storrsi (Stanton). Specimen, GAS 10463 from GAS loc. 28037.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 10

 u -i ' :*w-- it!i/£W^ ii\ ^^^Kj^n

BLANFORDICERAS AND SUBSTEUEROCERAS
PLATE 11

[All figures natural size]

FIGURES 1-11. Parodontoceras reedi (Anderson) (p. B45)

1. Lateral view of holotype of Aulacosphinctes watsonensis Anderson (1945, p. 1010). CAS

8714 from CAS loc. 28037.

2-5. Hypotype, USNM 158845 from USGS Mesozoic loc. M2599. The specimen shown in 

figures 4 and 5 are the inner whorls of the same specimen shown in figures 2 and 3.

6. Hypotype, USNM 158846 from USGS Mesozoic loc. M2253. Suture line shown on plate 

12, figure 9.

7. 9. Ventral and lateral views of holotype of AulacospMnctes reedi Anderson (1945, p. 978), 

CAS 8715 from CAS loc. 28037.

8. Hypotype, USNM 158847 from USGS Mesozoic loc. M3030. View of rubber imprint 

of external mold.

10. Hypotype, UC 10097 from UC loc. B-5094. Suture line shown on plate 12, figure 12.

11. Hypotype, UC 10098 from UC loc. B-5094.
GEOLOGICAL SURVEY

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PROFESSIONAL PAPER 647-B PLATE 11

11

PARODONTOCERAS
PLATE 12

[Figures natural size unless otherwise indicated]

FIGURES 1, 2. Aulacosphinctes? sp. juv. (p. B46).

Figured specimen (X 2), USNM 23229 from USGS Mesozoic loc. 1003.

3. Aulacosphinctes? didbloensis Anderson (p. B46).

Holotype, GAS 8710 from Bagley Creek near Mount Diablo, Calif.

4. Sarasinella cf. S. uhligi Spath (p. B51).

UC 10096 from UC loc. 2605. 

5, 6. Aulacosphinclesl jenkinsi Anderson (p. B47).

5. Paratype, GAS 8713 from GAS loc. 28037.

6. Holotype, GAS 8712 from GAS loc. 28037. 

7, 8, 10. Parodontoceras cf. P. storrsi (Stanton) (p. B45).

Figured specimens, USNM 161204 from USGS Mesozoic loc. 29489. Figure 10 is ventral

view of specimen shown in figure 7. 

9, 12. Parodontoceras reedi (Anderson) (p. B45).

9. Suture line (X \Yd of hypotype, USNM 158846 from USGS Mesozoic loc. M2253. Same

specimen shown on plate 11, figure 6. 

12. Suture line (X 13^) of hypotype, UC 10097 from UC loc. B-5094. Same specimen shown

on plate 11, figure 10. 

11, 16-18. Parodontoceras storrsi (Stanton) (p. B44).

Ventral, apertural, and lateral views of holotype, USNM 23092 from USGS Mesozoic loc. 

1084. 

13-15. Sarasinella cf. S. subspinosa Uhlig (p. B50).

Ventral and lateral views of specimen, USNM 158852 from USGS Mesozoic loc. M3060 

Figure 13 is from a rubber imprint of an external mold.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 12

AULACOSPHINCTESl, SARASINELLA, AND PARODONTOCERAS
PLATE 13

[All figures are natural size]

FIGURES 1-6. Thurmanniceras jenkinsi (Anderson) (p. B49).

Hypotypes USNM 158850 from USGS Mesozoic loc. M1577. Figure 2 is ventral view of

specimen shown in figure 1. 

7-9. Thurmanniceras stippi (Anderson) (p. B48).

7. 9. Hypotypes, USNM 158849 from USGS Mesozoic loc. M3059.

8. Hypotype, USNM 158848 from USGS Mesozoic loc. M3084. 

10. Thurmanniceras cf. T. stippi (Anderson) (p. B48).

Figured specimen, USNM 161209 from USGS Mesozoic loc. 29593. 

11-17. Paskentites paskentaensis Imlay and Jones, n. sp. (p. B47).

11. Paratype, USNM 161208 from USGS Mesozoic loc. 29596.

12. Paratype, USNM 161206 from USGS Mesozoic loc. 29596.

13. 14. Paratype, USNM 161207 from USGS Mesozoic loc. 29596. Figure 13 is from a rubber imprint of an external mold.

15-17. Ventral and lateral views of holotype USNM 161205 from USGS Mesozoic loc. 29598. 

Figure 17 is from a rubber imprint of an external mold.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 13

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THURMANNICERAS AND PASKENTITES
PLATE 14

[Figures natural size unless otherwise indicated]

FIGURES 1-15. Neocomites cf. N. wichmanni Leanza (p. B49).

I. Rubber imprint of laterally crushed external mold, USNM 158841a from USGS Mesozoic loc. M2679. 

2-4, 6, 7. Vertically crushed internal mold, USNM 158842a from USGS Mesozoic loc.

M2680. Figures 6 and 7 are from rubber imprints of interior whorls that bear umbilical

tubercles. 

5, 10. Lateral views of laterally compressed internal mold of a single specimen, USNM

158842b from USGS Mesozoic loc. M2680. 

8, 9. Lateral and ventral views of a laterally compressed internal mold, USNM 158842c

from USGS Mesozoic loc. M2680.

II, 12. Lateral and ventral views of a laterally compressed specimen, USNM 158841b from 

USGS Mesozoic loc. M2679.

13. Lateral view of internal mold, USNM 158842d from USGS Mesozoic loc. M2680.

14. 15. Lateral and ventral views of internal mold, USNM 158842e from USGS Mesozoic

loc. M2680. 

16. Neocomites cf. N. ncocomiensis (d'Orbigny) (p. B49).

Figured specimen, USNM 158843 from USGS Mesozoic loc. M2680. 

17-19. Neocomites cf. N. neocomiensis var. premolica Sayn (p. B50).

Figured specimen, USNM 158844 from USGS Mesozoic loc. M2680. Figure 17 is from a

rubber imprint of an external mold. Figures 18 and 19 are from an internal mold. 

20-22. Neocosmocerasf crossi (Anderson) (p. B52).

Ventral, lateral, and dorsal views of holotype, GAS 10448 from GAS loc. 28667. Note imprint of two rows of ventral tubercles on the dorsam. 

23-26. Neocosmoceras euchrense Imlay and Jones, n. sp. (p. B51).

Lateral and ventral views and cross section of holotype, USNM 158851 from USGS Mesozoic loc. 2074. 

27-31. Kilianella crassiplicata (Stanton) (p. B50).

27, 28, 31. Hypotype, USNM 161210 from USGS Mesozoic loc. 29596. Figure 28 is from a 

rubber imprint of an external mold. Figure 31 is from an internal mold. Suture line (X 4) 

was drawn at whorl height of 13 mm.

29. Hypotype, UC 10095 from UC loc. A-2925.

30. Hypotype, USNM 161211 from USGS Mesozoic loc. 29597.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 14

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NEOCOMITES, NEOCOSMOCERAS^, NEOCOSMOCERAS, AND KILIANELLA
PLATE 15

[Figure is natural size]

Groebericeras? baileyi Imlay and Jones, n. sp. (p. B35).

Lateral view of five septate whorls of holotype, USNM 158834 from USGS Mesozoic loc. M2024. The 

outermost whorl is the continuation of the innermost whorl shown on plate 6, figure 2, but is oriented 

nearly 180° from that figure. The next inner whorl shown on plate 15 is the same as the outermost whorl 

shown on plate 6, figure 6, but is oriented nearly 90° from that figure.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 647-B PLATE 15

GROEBERICERAS1

US. GOVERNMENT PRINTING OFFICE: 1970 O 365-428