LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

DESCRIPTION OF BPECIEB 197
The holotype affords the following measurements: greatest diameter, 60 mm.;
width of umbilicus, IS mm.; height of whorl, 23 mm.; thickness of whorl, 17 mm.;
umbilical ratio, 0.300:1.
This apecies is most closely related to SoniwraJiu stantoni Anderson. It is named
in honor of Mr, C. M. CroBS, whose work with J. A. Taflf on the Cretaceous sections
in the Diablo Range and in Tehama County has been of great help and value.
Sonntratia rogersi Hall and Ambrose
(Pint* 20, Crmi S, 7)
Sonwraiia TOQtrii HALL and AMBSOSB, Nautilus, vol. 30, 1910, p. 69, (not figured);
three-quarters of a mile south of Carnegie, Alameda County, California.
The holotype of this apeeies is in the Museum of Paleontology, Stanford University,
and has been carefully examined. Its original description shows clearly
its relation to the foregoing, to which it conforms in most essential features, except
for the number of costae on a single whorl. The surface of the shell is ornamented
by about 60 transverse flexueus coBt&e, which usually cross the ventral zone, and
terminate at the umbilical border in about one-fourth as many distinct tubercules.
Thia species was compared by the authors to Sonrwraita atantoni Anderson. It has
since been found sparingly on the cast branches of Hulen Creek, associated with
other species of the genus, and with PhyUocera* theretoe, Nemodon breweriana, and
Phaloddmya Aamgani Hall and Ambrose. Its horizon is about 900 feet below the
top of the Horsetown group, and the Hulen beds, and therefore somewhat lower than
the horizon of SenneraCia jloniont. The holotype affordB the following measurements:
greatest diameter, 4ft mm,; diameter of umbilicus, 12 mm.; height of whorl,
20 mm.; thickness of whorl, 13 mm.; umbilical ratio, 0.23:1,
Its horizon is regarded as near the middle, or a little below the middle, of the
Albion in the Cottonwood district,
PULCBSLUIDAS DouvilI6
FidcAciito Douvill6
PulcheUia popenaei Anderson, n. sp.
(Plata 13, Beam I, 3)
The shell of this species is of moderate size, discoidal, moderately inflated, broadly
costate; rihe flattened, branching near the middle of the aide, strongly flexed, bearing
numerous growth lines; ribs terminating at tbe ventral border in thin, elongated
nodes; umbilicus narrow, deep, with steeply sloping walls, flaring above, with
rounded borders; siphonal zone narrow, flattened, bordered on either side by moderately
elevated costal nodes. Beneath these terminal nodes the ribs are slightly
swollen, giving the appearance of a distinct ridge concentric with tho periphery.
The holotype, septate throughout, has the following dimensions: greatest diameter,
67 mm.; width of umbilicus, 5.6 mm.; height of whorl, 32 mm.; thickness of whorl,
17 mm.; umbilical ratio, 0,006:1.
This example is tho first recorded occurrence of PulcheUia in the Cretaceous cf
California, although it U common in the Barremian strata of the northern Andes and
has been found in Japan. The apecies belongs to the group represented by jPufcAeUia
leai (Forbes), from which it differs chiefly in the greater curvature of the ribs and in
the form of the umbilicus. The holotype was found by W. P. Popenoc and D. W.
Scharf on Roaring River, Locality 967, (Calif. Inst. Tech.), a quarter of a mile west
of the Millaap road, and beneath the Mitchell zone of the Horsetown group.
Only four identifiable examples have been found; they were associated with