LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of species 229
Hometown group on Mitchell Creek, where it is associated with A. aboriginalit nov.,
PoraAopIttoirfes sp., Nautilus aiieriiit nov., and Aucella sp., with striae radiating
from the beak, It has the following dimensions: length (incomplete), 84 mm.;
greatest lateral diameter, 23 mm.; dorso-ventral diameter, 21.5 mm.; phragmacone
broad and short.
The ventral side is but little curved longitudinally, whereas the dorsal side is
arched, thue inclining the apex toward the ventral side. Only a single example of
this species has been found.
Acroteulhie divergent Anderson, n. sp.
(PUta SO, Bgons fl, t&)
The complete guard of this species is evidently very long, although it is known
only from fragments, the longest of which is the holotype. This consists of the
central portion of the guard. At the top it shows the outline in section of the lower
part of tho phragmacone, which is centrally placed and extends below the top of the
ventral groove, uniting with a centrally placed axis. The section of the guard ia
subcircular, narrower at the top, and increasing in diameter downward. The most
striking feature of the guard is the divergence of its sides downward helow the
terminus of the phragmacone. The ventral furrow is rather broad and shallow; the
length of the holotype and its divergent sides indicate that the original length was as
much as 140 mm.; it could have been greater. The holotype (Calif. Acad. Sci. typo
Coil.) measures: length (incomplete), 98 mm.; diameter at top, 20 mm.; diameter at
lower end, 23 mm. This example was found in the lower part of the Mitchell zone
on Fiddler Creek, 10 miles south of Ono, Shasta County, where it was associated with
A. ahoatenaii, Shaalicrioceraa sp., and specics of Terebratula. It haB some resemblance
to, although not a near relationship with, A. mitchelli, from which it differs
in section, in tbe smaller depth of the ventral furrow, and in the divergence of its
sides.
Aulac-olcuthia Stollay 1911
Genotype, Bdemnilee abaoluliformia Sineow
Aulac&teuthit wynioomwn Anderson, n. sp.
(Plata so. fictm*