LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

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