LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

DESCRIPTION OF SPECIES 107
birsk. Tbe California forma, although of Neocomian age, more nearly resemble
those illustrated by him (Pavlow, 1907, pi. 3, figs- 18a, b, e) from the Aquilonian
beds of Khoroohovo, The left valve is long and narrow, with an acuminate beak;
the right valve is not less acute, but shorter. The species is found in the lowest
beds of the Paakenta group on McCarthy Creek, Tehama County, and at the Go vernment
dam aita, near Elk Creek village, Glenn County. The figured examples art
from this locality. Good examples of the species were found by Bruce G. Martin
at Locality 27 (Calif. Acad. Sei.), nearly 2 miles north of Myrtle Creek village,
Douglas County, Oregon. The young of this species often resemble the young forms
of AuceUa piochi Gabb, but tbe more mature stages of growth are readily distil
guished, being longer, narrower, and lacking the expansion of A. piochi is the
posterior part of the left valve.
Aucella piochi Gabb
Jnoceramue piochii GABB, Paleont. Calif., vol. 1, 1864, p. 187, pi. 25, fig. 173 only
(not HE. 174); north aide of Mount Diablo, Contra Costa County, California.
AuceUa piochii GABB, Paleont, Calif,, vol. 2,1869, p. 194, (not pi. 32, figa. 92a, b, C)
—STANTON (in part), U. S, Geol. Surv., Bull. 133,1S95, p. 42, (not pis. 4, 5).
BucJu'o. piochi CAICKUAT, Am. Midi, Nat., vol. 13, no. 1, 1932, p. 1-7; (Upper Jumsa'tc
strata of HuAs.na district, San Luis Obispo County, California,
In the earlier literature on the Lower Cretaceous Qf California and Oregon, this
species is often listed, and was usually regarded as indicating a low position in the
Cretaceous sequence on tbe West Coast, More recently it baa been held to be one
of the leading spcciea of the Knoxville series, and to range almost throughout this
aeries. Search at the type locality of the apeeica shows it to be not very abundant,
but mingled with other species of the genus, and rarely among them a berriaacllid,
resembling B. caliato d'Orbigny. It ia often found also in transported boulders
buried in the basal conglomerates of tbe Shasta aeries, as on the northwest Sank
of Mount Diablo, and in the Berkeley Hills. A similar if not identical species has
recently been collected from e ale uremia beds in the Berryessa Valley, Napa County,
mingled with types of Aucella and other Mollusca that characterize the basal beds
of the Paskenta group. For this reason tbe species is included here as one that in
exceptional places in the Great Valley embayments may have survived the events
which normally clued the Knoxville period. The species ranges throughout tho
Knoxville series in its type area.
Attcella indigtnalis Anderson, a. «p.
(FKFE 7, fipim S„ 6; PIaU g, 10)
This species has the general form of Aucclia keyserlingi Lahuscn, as figured by
Pavlow (19C7, pi. B, figa. 17a, b, c), but differs from it notably. The left valve has. a
higher and more prominent beak, which overhangs the right valve in a hook-like
curve; the margins of the right valve meet above at a larger angle (near 85 degrees),
and the umbonal ridge on the left valve ia much more oblique.
The holotype (Calif. Acad. Sci, type Coll,) was found with other examples of tbe
eame species, at "Locality 77," 2 miles north of the Indian village of Skidegote,
Graham Island, by R, M. Klein pell and E. W. Gallihcr. It hme the following dimensions:
length of left valve, nun.; greatest width, 35 mm.; thickness, 20 mm.;
length of right valve, 42 mm.; width, 30 mm, j thickness, 10 mm.
It was found associated with Lyioeeras argonautarum Anderson, Desmecerax uflirt
Anderson, and with other species of Aucella, It is regarded M being of Aptian age.