LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

154 lower chetaceous deposits ijf california and oregon
POLTPTYCEITIDAB Spath, 1924
Polyplyehitea letoniei Anderson, n. sp,
(P1»t« S, l{iin 1; put* 23, Bcun 1)
Shall large, robust, thickly cost&te, broadly umbilicate; section of whorl in adult
stages subcircular, slightly broader than high, tbe ratio of height to breadth increasing
with the growth of the shell, sides slightly flattened; umbilical walls abrupt,
arising almost vertically; ribs numerous, branching from elongated umbilical bullae
below the middle of the sides into three, four, or five smaller ribs; ribs rarely subdividing
above; umbilical bullae elevated, narrow, rounded, not bearing tubercules,
arising within the umbilicus, sloping at first backward, then vertical on the umbilical
border, and thence inclining alightly forward before dividing; smaller costae rounded,
nearly straight, crossing the ventral zone without interruption or flattening; interspaces
broader than the costae; sides of shell crossed at intervals by broadly rounded
grooves, arising at tho umbilical border; suture lines as shown in the figures. The
holotype (Calif. Acad. Sci. type Coll.), wholly septate, affords the following measurements:
greatest diameter, 195 mm.; width of umbilicus, 58 mm.; height of whorl,
50mm.; width of whorl, 62 mm,; umbilical ratio, 0.352:1,
This species resembles "Olcoatephanus" tratki (Gabb) but differs from it in soma
notable respects, as will be seen upon comparison of the figures. In its ribbing
the ratio of tbe number of umbilical bullae to tbe peripheral ribs is about 1:3.7.
Among European species its nearest analogue seems to be Polyptychic pobjptychus
Keyserling, figured by Pavlow; its horizon appears to be nearly tbe same—namely,
middle or upper Valanginian.
The holotype was found id the Hamlin-Broad zone at Locality 113 (Calif. Acad.
Sci.), 4 miles southwest of Ono, Shasta County, by Dr. E. J. Broad of San Francisco,
who presented it to the California Academy of Sciences, with various other species
and genera from tbe same zone and locality. It was found with Polyptychic httperttu,
iSimWrsHtea browfi, Lytoeeras saturnale, Lylocera* aulaeum, Aipinacerae
hamlini, Anahnmulina I'fiperfina, Acroteulhis thastmria, Belemnoteulhis (Coneteuthis)
poeifica, and many other species representing the upper part of the Paskenta
group of the Shasta series in the Cottonwood district.
The horizon of this zone is atratigraphically about 500 feet beneath the lowest
beds assignable to the Horsetown group in the Shasta series.
Polypiychitei heeperius Anderson, n. sp.
(PUto 24, flcurn J, 2)
Shell large, robust or massive, thick, with heavy branching riba; section of whorl
broadly triangular, with strongly converging sides; periphery relatively narrow, but
rounded; umbilicus apparently not broad; umbilical nodes, or ribs, thick, arising
on the umbilical wall, curving at firBt backward, but inclining forward on the sides,
dividing below the middle into three, sometimes four, straight, rounded ribs which
cross the periphery; sutures as shown in the figure.
The holotype of this species (Calif. Acad. Sci, .type Coll.) was found by £. J.
Broad at Locality 113 (Calif. Acad. Sci.), 4 miles southwest of Ono, Shasta County,
at the head of Mitchell Creek. It is a large fragment representing a little less than a
quarter of a whorl, with a portion of an inner whorl. It ia septate throughout and
accordingly is a part of an inner whorl. In its general form and character it recalls
Poly ply c hi tee ephaericus von Koenen, but has fewer and heavier ribs. Its nearest
west European analogue seems to be Polypiychites tempiughi Pavlow, although there
are obvious differences. In the present species the section of the whorl ia more