LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

DBBCBtmOK OP SPECIES 97
Sacramento embayment, it ia not confined to the Chico series. It has been found
in the lower beds of the Horsetown group at Ono, and in the upper, and perhaps the
lower beds of the Paskenta group in the Cottonwood district. It is congenerio with
Nemodon vaneouvertntit Meek, which belongs to a higher horizon, but their identity
can scarcely be maintained.
Nemodon (?) Itham&enria (Stanton)
Area tehamaeim's STANTON, U. 3. Geol, Surv., Bull. 133, 1SG5, p. £0, pi. 6, figure 8;
Shclton'e ranch, 5 miles north of Paskenta, Tehama County.
The holotype of this species is small, and Stanton regarded it as being "probably
an immature individual," stating also that he had "not seen the hinge," and that
"the general form of the shell makes it probabla that it belongs to the subgenus
Xtmodon." On the Shelton ranch it occura with Aucella cra&ricollit, "Olcotlrphonus"
muiabilit Stanton, and ether species of the Paekenttt group in the Shasta
series. As the stratigraphic position of this species on the Shelton r&neh appears
to be near tbat of Locality 113 (Calif, Acad. Sci.) in tbe Cottonwood district and
near the top of the Paskenta group in both, Stanton's holotype may well be the
young of a species of Nemodon found at Locality 113, and at other places in the
Cottonwood district, &s at Locality 1059 (Calif. Acad. Sci.) on Duncan Creek.
Nemodon (?) textrina (Stanton)
Area teitrinaSTANTON, U. 9. Geol. Surv., Bull. 133, 1996, p. 50, pi. S, figs. 6, 7; near
Stephenson's on the Cold fork of Cottonwood CrcBk, Tehama County.
This is a small species of distinctive form and sculpture, of which Stanton says,
ts part:
"surface marked by distinct, closely arranged lines of growth and by similar,
slightly larger radiating lines, which are not st all conspicuous to the unaided eye.
Although Stanton compared this form with "Gramalodait" internal us Whiteaves,
he states that "it should probably be referred to the subgenus Nemodon." Its form
and sculpture indicate that it does not belong to either of the preceding speoiee,
although it probably is a Netn&don. Its occurrence in Stanton's list (18W5, p. 14)
with Aucella cratticollit, "Belemnilet" impreMa, and Lima multilineata shows that
its position is i& the upper part of the Paakenta group. A similar form, probably
the name species, was found on the North fork of Cottonwood Creek, a mile or
more south of the diversion dam above Ono. Its position here is about 600 feet
beneath the lone of Thurmannia jupiter—that is, below the Eamlin-Broad zone of
the Psskeeta group.
ARCIDAB Doll
Glycymerit Da Costa
Glycytntrit amtui (Stanton)
Pietunculus (?) ot'OIIM STANTON, 17.S. Geol. Surv., Bull. 133, IBQSjp. 51, pi.G, figs,
10; Dear Stephenson's ou Cold fork of Cottonwood Creek, Tehama County.
The hinge characters of this shell as well as its general form and radial surface
markings, as given by Stanton, should leave little doubt as to its generic position.
It is the oldest form of this genus recorded from the Cretaceous of California, and
it is specifically unlike any other form of the genus yet found in these beds.
The species ia included in a list (Stanton, 1805. p. 14) of 13 other forms specifically