LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON
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100 3WJWEH <strong>CRETACEOUS</strong> <strong>DEPOSITS</strong> IN <strong>CALIFORNIA</strong> <strong>AND</strong> <strong>OREGON</strong><br />
/iMffffluiM avatoidea Anderson, n. sp.<br />
(FL»T» S, FL*UN> 3}<br />
Shell large, somewhat robust, elongated, aubtriangular, inequivalve, hinge short,<br />
anterior margin straight, left valve having a strongly incurved, spiral bcakj anterior<br />
margin deeply rounded; right valve flattened, longer than broad, beak nearly terminal,<br />
acuminate; surface of cast nearly smooth, or marked only by faint concentric<br />
undulatione; inner layers of shell smooth, often pearl-bearing; prismatic layers<br />
thick, brittle, not often preserved; outer surface not well preserved; form somewhat<br />
variable. This shell often attains a length of IS to 17 cm., and incomplete shells<br />
have bean found which had an original length of 20 cm.; the width is usually about<br />
half the length. In general form and markings the ahell recalls that of L owHtU<br />
Stanton, but it is much larger and leas clearly marked by concentric undulations,<br />
and is relatively narrower. It is abundant in the Mitchell zone in the Bald Hills,<br />
Shasta County, where it is usually accompanied by Ancyloctrot ajax, A. durrelli,<br />
and Acroteuihit onoenxis nov. It marks the Barremios and lower Hauterivian<br />
strata in the Cottonwood district, and its hnrison ia a little higher than tbat of<br />
I, omfm.<br />
The holotype {Calif. Acad. Sci. type Coll.) was obtained at Locality 1347 (Calif.<br />
Acad. Sci.) and measures as follows: length, 160 mm.; greatest width, 95 mm.;<br />
greatest thickness of left valve, 30 mm.<br />
Near the bridge at Ono, a somewhat similar but smaller species is found associated<br />
with Ntocrarptditt* afuila, PhyllottTas occtdeniale, and a large form of Lytoceraa,<br />
in strata regarded aa lower Hauterivian.<br />
InOceramut eolomcua Anderson, n. ap.<br />
(Hat* 4, fisuns 10, It, IS; Finn J, flaw* t)<br />
Shell of moderate size, narrow, elongated, with thick shell, snd very unequal<br />
valves; left valve with it strongly incurved beak; right valve with a narrow terminal<br />
beak; shell brittle, and rarely found complete. The shell of this species resembles<br />
that of I. 6vttlQidst in general form and surface markings, but ia narrower relative<br />
to length, the left valve has a longer and more incurved beak, and its stratigraphic<br />
range is apparently greater. It is abundant at Locality 1353 (Calif, Acad. Sci.),<br />
where it is accompanied hy Meocraaptdiiet aguiia and many other invertebrate<br />
species. Its name is taken from its apparent habit of living in close colonies. A<br />
single example of the specie a was found on McCarthy Creek, Tehama County, about<br />
1000 feet west oi the Paskenta—Lowry road, associated with Hibolil*» eigarroidei,<br />
Aeroteuthis anaensia, and -4. nhonUrm* nov.<br />
The holotype (Calif. Acad, Sci. type Coll.) and the paratype were obtained at<br />
Locality 1631 (Calif. Acad. Sci.), a mile west of the Murphy ranch house, and a mile<br />
south of Roaring River, Shasta County, where it was associated with Sftasfierioeeras<br />
pomente, Acriocerae starrkingit Peeadocriocertu Mentor, and Aeroteuthis shaxtcnais, in<br />
strata regarded as Bsrremian. The holotype measures as follows: length, 110 mm.;<br />
width, 50 mm.; thickness of left valve, 20 mm. The paratope is somewhat smaller.<br />
Inoeeramus willejotnsis Anderson, n. sp.<br />
(Plile 6, fijiiffr it<br />
Shell very large, eubquadrate in outline, broad, beaks sub-terminal; binge line<br />
short; surfaces marked by only concentric undulations 2 to 4 cm. apart; valvea<br />
Battened, not much inflated; shell brittle, not well preserved. A single example of