LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description op 8pecles
have yet appeared ia tbe immediately underlying Knoxville (Upper Jurassic) beds
from which the stock might supposedly have been derived. Stanton has desoribed
five or six species of the genus Turbo alone,
Turbo Linnaeus
Turbo morganetuit Stanton
Turbo morganemia STANTOW, U, S. Geol. Surv., Bull. 133, 1895, p, 68, pi. 12, fig. 13;
Morgan Valley, Lake County.
This is the most ornate form of the several species of this genus that have yet been
found in the Lower Cretaceous of California. The original description is in part
as follows:
"Surface of the spire marked by two strong nodose revolving ridges that give the
whorls a biangular appearance, crossed on the first two whorls by small transverse
lines connecting tho nodea; body whorl in front of the two ridges bearing four or fiva
somewhat less prominent distant revolving lines."
Tho upper portion of the whorl is described and shown in tho figure as nearly
smooth.
The holotype of this species is one of four examples found in Morgan Valley,
a mile northwest of the Palmer ranch, on the road from Lower Lake to Knoxville.
The species is hero associated with Pecten complcxicosta Gabb, Astoria trapczoidalit
Stanton, and Attain* liratut Gabb.
The horizon represented by these several species Is low in the Paskenta group,
in an area in which these beds make a wide overlap upon pro-Cretaceous formations.
TVrfw fetiivus Anderson, n. ap.
(PUte 10, flrure 5)
Shell of medium size, suhgloboae, nacreous in texture; whorls few, angulated;
spire moderately high, conical; imperforate, aperture subcircular, inner lip thickened,
outer lip thin.
This species may perhaps belong in the section "Laeviturbo" of Cossmann, but
this cannot be determined at present, The whorls are angulated, with two ridge-like
threads on the whorls, one near, but above the suture, tbe other higher on tho whorl,
at the outer border of tho upper slope. There ia a slight appearance of beading on
the latter angle on one of the six examples obtained.
The holotype (Calif, Acad. Sci. type Coll.) measures: height, 26 mm.; greatest
width, 17 mm. All the examples were found at Locality 1353 (Calif. Acad. Sci.),
near the bridge on the North fork of Cottonwood Creek at Ono, in the lowest fossil
zone of tbe Horsetown group.
All the species described by Stanton are believed to have been found in the Paskenta
group in areas south of the delta axis; tbe appearance of the present species
in the Horsetown group in the Cottonwood district aids only in indicating the relationship
of tho groups.
Tar bo tritincalu* Stanton
7WiK> trilineatvi STANTON, U. S. Geol. Surv., Bull. 133. 1895, p. 66, pi. 12, fig. 12; 3
miles south of Lowry's, Tehama County.
This species is described as follows;
"Shell small, obliquely ovate, consisting of about four rapidly increasing convex
whorls; surface ornamented by three elevated, equidistant revolving lines that are
visible on the spire, by seven or eight fainter and more closely arranged revolving