LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of bpbcte3 163
umbilicus abrupt, rounded above, but curving rapidly to the flattened aides; section
of whorl semi-elliptical, higher than broad, narrowing toward tho rounded periphery;
Strong umbilical ribB arising at the whorl suture, inclining strongly backward, thickened
to bullae on the margin; ribs branching from these into two, or rarely into three,
Smaller, rounded, sinuous ribs; between these groups are interpolated a few simple
ribs; other intermediary ribs arise at intervals above the middle of the Bides; all
ribs crossing the ventral zone without interruption and with a forward bend; the 60
or more costae on the periphery arc about three times the number occurring on the
umbilical border; the interspaces between the ribs are broader than the ribs, and
are concavely rounded; in adult stages the ribs bccome heavier and more widely
spaced; the sutures are hoplitid, although not clearly exposed.
This species greatly resembles Thurmannia boiaaieri (Pictet), as figured by tFhlig
(1903, pi. 80), and it may be its nearest California analogue. It differs from this
apecies in having a more rounded ventral border, in its more elongated umbilical
bullae, and its fewer intermediary ribs arising above the middle of the sides.
The holotype (Calif, Acad. Sci. type Coll.) was found in a calcareous concretion
buried in dark shale in the Hamlin-Broad zone 3 miles southwest of Ono, Shasta
County, and about 1600 feet above the local base of the Paskenta group. Its
stratigraphic position appears to be near that of Dichotomies, BcrriaseUa, and
Aucella crassicollis on tho Wilcox ranch and on McCarthy Creek, Tehama County,
and therefore aids in the correlation in the two districts, -
BBUMABELLIDAB Spath 1924
BerriatellQ Ublig 1903
Berriaaella angulata (Stanton)
Soplites ANPUTOLTM STANTON, U. S. Geol. Surv., Bull. 133,1896, p. 80, pi. 18, Bgs. 3, t;
Sheltoa's ranch, fi miles north of Paskenta, Tehama County.
Concerning this species Stanton says (in part):
"This species is evidently related to Hopliles storrti. but its whorls are proportionally
somewhat more convex, its sculpture is relatively coarser, with broader and
more strongly curved ribs, and the border of the umbilicus is more angular."
Stanton also compares it to a specimen from Speeton, England, figured by Pavlow,
which the latter regarded as "Hoplites" amblygontus Neumayr and Uhlig. According
to Burckhardt (1930, tables 0, 10) "Hoplites" alvrrsi Stanton should be regarded
as a Berrioeella, and seems to belong to the group of Berriasella calitto (d'Orbigny).
This observation should also apply to "Hoplites" angulatus Stanton, and to other
forms described from the lower part of the Paskenta group. The association of this
apecies with Auc«tfa cra-sso, A. croeticollis, "Simbirskitee" mutabilis Stanton, and
Bochianilcs, and other forms of Berriasella indicate a horizon not higher than the
upper part of the Paskenta group, and therefore not higher than Valangintan.
ifarrtaseiJa crassiplicata (Stanton)
Hoplites crassiplicalua STAKTCIJJ, U. 9. Geol. Surv., Bull. 133, 1895, p. 81, pi. 18, figure
8; 3 miles north of Paskenta, Tehama County, associated with Aucclla craasieollia.
Stanton compares this species with "Russian Lower Volgian species 'Hoplilc*'
rjaaensU Lahuacn," as figured by Xikitin, However, as noted by Stanton, the form
is perisphinctoid, and is characterized by a
"Surface ornamented by relatively large, distant riba that arise on the edge of the
umbilicus, and nearly all bifurcate after passing over about two-thirds of the distance
to the periphery, on which they are interrupted."