LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

DESCRIPTION of SPECIES 211
consists of a body-chamber, net known to belong to the earns individual, although
to one of the same size. The holotype, par&type, and smaller fragments of other
individuals were found at Locality 1661 (Calif. Acad. Sci.) in beds near the bottom
of tho Mitchell zone in the lower part of the Horsetown group, a mile west of the
Murphy house south of Roaring River, The holotype has the following dimensions:
length along siphonal line, 230 mm.; diameter of shaft at top, 60 mm.
AwlraH&erea White ho use 1029
Genotype, "Crioceras" jacki Etheridge Jr.
According to its author, "the genus is proposed for a group of species richly
represented in the Australian Aptian," and it is known also in other countries. He
gives the following diagnostic notes (Whitehouss, 1026, p. 213):
"Crioceratid shells with initial whorls trituberculate, later whorls without tubercules
until the adult body-chamber, which ia trituberculate; ccwtae simple or
bifurcating near the umbilical margin; septal suture (I. U. L. E.) with prominently
bifid, relatively short-stemmed saddles and regularly trifld lobes."
No less than sic species of this genus are described by Whitehouse from the Aptian
of Australia. The number of species found in corresponding horizons in California
is leas, although it appears that at least two exist, and there are indications of still
others in fragmentary examples.
•rluslraiicfrtw argus Anderson, n. sp.
CPlite ?0, HtuiM 1, is, lb, 1)
Shell rather large, robust, subcircular in section of whorl, coiling crioceratid,
heavily costate; riba nearly straight, or curving forward in mature examples (5 to
6 inches ia diameter); in young stages below 76 mm. costae alternately simple and
trituberculate, the latter being much heavier; at a diameter of 85 to 90 mm. the costae
all become simple and rounded, without tubercules, except an occasional ono near
the ventral border; coatae cross the ventral sone with a forward sinus, and the flattened
dorsal area with a backward bend; shell aeptate up to a diameter of 9.5 inches,
not known beyond this point; septa not well exposed. In its mode of coiling, coatation,
and other characters, this shell bears some resemblance to Auslralicerae robusfum
Whitehouse (not von Koencn), f rom the upper Bedoulian of central Queensland,
Australia. However, there are obvious differences, as in the single minor ribs
in the present species, instead of two or more, in its less prominent outer tubercules,
in its forward curving ribs, and in its relatively higher section. The holotype (Calif.
Acad. Sci. type Coll.) was found on Bee Creek, 4 miles south of Ono, Shasta County,
on the Shoup ranch, and stratigraphically a little below the Argonaut zone containing
Tropaeum pereestalatn (Gabb), Phylloctras enatme Stanton, and Parahopliloidet
shoupt nov. A larger example, somewhat distorted by rock pressure, was
found in the same zone H miles farther south. Fragments of this, and perhaps other
species of the genus, have been found at other places in the Bald Hilla of the Roaring
River diatrict south of Ono, but not sufficiently complete for description.
Tropaeum J, de C, Sowerby, 1837
Genotype, "Crioccratiles" bouserbanki Sowerby
The genus Tropatttm of Sowerby was revived by Hyatt (1900, p. 571). According
to Whitehouse (1926, p. 213):
"the genus WAS derived from Australiccras, with which it 1B identical in coiling,
costation and septal sutures, but it appears to have developed along aevcral lines.
Tropaeum, aa represented by its genotype, is non-tuberculate, while most if riot all