LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

142 lower chetaceous deposits ijf california and oregon
Tho nearest European analogue, although much earlier, ia P. Tfi/undibujuni d'Orbigny.
This species does not appear to be closely related to either P. vciledae Michelin,
P. onoense Stanton, or P. aldcrgoni nov., but it belongs in tbe lineage of P. occidentals
nov. The holotype of this species is in the Museum of Paleontology, University
of California, and waa found by the writer at tbo old mining camp of Horsetown,
Shasta County, in the uppermost beds of the Horsetown group. A topotype of
tho apociea is in the collections of the California Academy of Sciences.
Phylloceraa onoerue Stanton
(Pluto 11, Bgura 1,2)
Ammonites RANTOATHA, GABS (not MEEK), Paleont. Calif., vol. 1, 1BW, p. 63, pi. 11,
figs. 12, 12a; pi. 12, fig. 12b; Lower Crctacooua, Cottonwood Creek, Shasta
County.
Phyllot-eroti onotnae STANTON, U. S. Geol. Surv,, Bull. 133, 1895, p. 74; Horsetown
beds, Shasta County.
Phylloeertu ramoswn (Meek) is a species belonging strictly to the Upper Cretaceous
(Senonian) of tbe West Coast, and has not been found in the Shasta scries.
Gabb erroneously identified a species found in the Cottonwood district with that
of Meek, as was pointed out by Stanton. Gabb's figuras of the Horsetown species
are defective, although there can be no doubt aa to the form he endeavored to represent.
To this species Stanton has given the name Phyiloceras oiutcnac.
The shell of this species is discoidal, compressed, or somewhat lenticular, with
a small but open umbilicus; sides flattened, but sloping to a narrowly rounded
periphery; surface at first almost smooth, but with growth it acquires numerous
rounded, radiating threads (18 to a ccntimeter in adult specimens), separated by
concavc interspaces, broader than tho threads; costal threads arising near the umbilicus,
curving at first forward, then rising vertically, and finally curving gently
forward on approaching the periphery. Gabb's (1S64, pi. 11, fig. 12) figure shows the
curvature of these lines to be backward, contrary to fact, and the suture lines do not
show correctly the pbylliform terminations that are characteristic of this species.
The smaller terminations on the saddles are obovate, showing the spccies to be a truo
PAjriioceras. Its horizon IB commonly in the middle Horsetown group (Bedoulian),
in which beds it is usually associated with ilytoceraa argonaularum, Parahoplilaidea
ccrrctensis nov,, and Acroteulhin aboriginalis nov. Six or more good specimens were
collected from the Argonaut zone at Locality 1347 (Calif. Acad. Sci.), half a mile
east of Mitchell Creek and 5 miles south of Ono, Shasta County.
The example figured by Gabb has been listed ae being in the Museum of Paleontology,
Univcreity of California, by Men-ism (1595, p. 1), but it has not been found.
Under the circumstances attached to this specimen, it seems better to propose a
lectotype for the specica, and a more complete example (Calif. Acad. Sci. type Coll.)
is selected to represent it. This example was obtained on the west branch of Bee
Creek, half a mile east of the Shoup ranch house, in the Argonaut zone. It has the
following dimensions: greatest diameter, 120 mm.; width of umbilicus, 7 mm.;
height of ivhorl, 65mm.; thickness of whorl, 35 mm.; umbilical ratio, .058:1. Some
fragmentary examples of the species have been found which indicate an original
diameter of 12 inches, although the usual size is about 4 to 6 inchca. It differs from
P. knoivilleMe Stanton in its finer ribbing, and distinctly different suture lines,
particularly in its broad, short sipbonal saddle. It also differs from P, cali/ornicum
no v., in its finer and more sinuous costal lines, in its thinner section, and in its lower
horizon.