LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of species 173
diameter, 220 mm,; diameter of umbilicus, 78 ram.; height of whorl, 85.5 mm.; width
of whorl, mm.; umbilical ratio, 0.355:1.
The holotype was obtained from the North fork of Cottonwood Creek, probably
above the Argonaut zone, by J, W. Gardner. It ia now in the collection* of the California
Academy of Sciences.
Acanlhvplitet perrini Anderson, n. sp.
(Plata 38, 6(UJ« I)
Shell large, thickly discotdal, laturnbilicate, rounded on the periphery, heavily
costate; umbilicus broad, with abrupt walla, rounded on the borders; having slightly
curved, rounded primary and secondary ribs; primary ribs mostly simple, occasionally
branching, arising on the umbilical wall as a backward sloping ridge, curving
on the umbilical border and rising nearly at right angles across the side to the ventral
zone; nearly twice aa many secondary ribs as primary, arising at or above the middle
of the aide; all ribs cross the ventral zone without interruption; suture line, as shown
in the figure, has a deeply cleft aiphonal saddle, showing asymmetry with reference
to the siphonel plane, and asymmetry in the successive divisions of tho lobes.
The holotype (Calif. Acad. Sci. type Call.}, almost wholly septate, affords the
following measurements: greatest diameter, 230 mm.; diameter of umbilicuB, 90
mm.; helghtof whorl, SO mm.; width of whorl, 65 mm.; umbilical ratio, 0.39:1.
This specimen was obtained in the Ferrin zone on the west branch of the east fork
of Hulen Creek, cast of Ono, at Locality 145 (Calif. Acad. Sci.). It was associated
with Chtloniccra* sp., CUoniceToi cf. lecontei, Nautitut gabbi, and other species. Its
position is above that of the Buenaventura zone of the Hulen beds referable to a lower
middle Albian horizon.
This species seems to have ita nearest analogue in Aeanihoplites notani (Seunea),
as illustrated by Sinzow (1007, pi. S, fig. 1) from the Caucasus Mountains. The
species is named in honor of the late James Perrin Smith, for many years Professor of
Paleontology at Stanford University,
Acanthtiptocs tpaihi Anderson, n. sp.
(Plate 41, flpirn 3-&)
Like the preceding forma, thia ahell ia of moderate size, discoidal, inflated, with
moderately broad umbilicus; section of whorl subcircular, rounded on aides and
periphery; walls of umbilicua sloping, rounded above, blending with the sides; 32
to33elevated primary and aecondary ribs; primary ribs arising on the umbilical wall,
rectiradiate, often branching in younger stages of growth, and bearing short spinelike
processes at the points of division; secondary ribs, in older stages of growth,
arising near or above tbe middle of the side; shell in younger stages having the aspcct
of Cheloniccras; interspaces between ribs deep, sa broad aa the riba themselves.
The holotype (Calif, Acad. Sci. type Coll.) affords the following measurements:
greatest diameter, 70 mm.; width of umbilicus, 20 mm,; height of whorl, 25 mm.;
thickncss of wborl, 25 mm.; umbilical ratio, 0.371:1. In older stages the branching
of the ribs and the spines become obsolete and are finally lost, the ventral tone
becomes flattened, and the ribs become more prominent on the periphery. The
species appears to belong to a group represented by AcanlAoptftea abithi (Anthula)
as figured by Sinzow (1007, pi. 0, figs. 1-3). Tbe holotype and the other figured examples
were found at Locality 1346-A (Calif. Acad, Sci.), on the west branch of Hulen
Creek, in the Buenaventura zone, or just beneath it, ia the upper part of the Horsetown
group. It has been found also on Alderson Creek and on Bee Creek, presumably
in the same zone. Its horizon is near the top of the Aptian portion of the
Horsetown group.