LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

216 lower cretaceotffi deposits in california and oregon
Hamiticcras pilsbryi Anderaoo, a. sp.
(Flit* 79, Spin t)
Helicanajlus atQuicosiaiut GABB (in part only), Paleont, Calif,, vol, 2, 18SG, p. 141,
pi. 25, 30b, c, d, e, f, (T g), all belonging to a single individual; locality
not certainly known,
This remarkable species ia of medium aise; its limbs are circular in section but
ace diverse in form and ornamentation; the smaller limb, which is also the longer,
possesses oblique ribs of two kinds, alternately smooth and simple, and trituberculate
thicker ribs; body-chamber sharply bent, not ahown in Gabb's figures; ribs on the
smaller limb interrupted on the siphonal line by a nearly smooth depression bordered
by ventro-lateral tubercules; larger limb heavily costate, with simple noii-tubereulate
ribs, much stronger than those on the amaller limb; near the dorsal border the
ribs are reduced in strength and bent forward; all are more prominent on the ventral
side; intercostal apace* broader than the ribs. The trituberculate ribs on the similar
limb show its ancyloceratid character, aa do also the aepta, as drawn by Gabb (1606,
pi. 25, fig. 20g). The several fragments illustrated by Gabb (ISM, pi. 25, figs. 20b,
c. d. e. f) have DO close relation to the others (Gabb, pi. 25, figs. 20,2&V) which belong
to a distinct genus. The holotype of this species is in the museum of the Academy
of Natural Sciences of Philadelphia and waB loaned to the California Academy o(
Sciences for study and illustration. It has tho following dimensions: total length,
62 mm.; maximum diameter of larger limb, 33 mm.; maximum diameter of smaller
limb, 28 mm.; width across both limbs, 59 nam, An example of this spedes has been
found by W. P. Popeaoe and B. W. Scharf in the Argonaut zone on the North fork of
Cottonwood Creek, near Ono, Shasta County, and tho horiion of the holotype is
believed to be the same.
Hamilietrat philadelphium Anderson, n sp.
(PUta 19, fiffurtit 3, S)
In the collections of tbe Academy of Natural Sciences of Philadelphia there ie a
well-preserved example of this genua—the holotype of the present apeciea. It bears
Gabb's label, "Helieancylu* aequicastatus" Gabb, and is No, 4707 (Acad. Nat. Sei.
Phila ); it is said to have been found on the North fork of Cottonwood Creek, Shasta
County. It has the following dimensions: total length, fll mm.; width aero® both
limbs, 45 mm.; maximum diameter of larger limb, 20 mm.; section of both limba,
nearly circular. A line of faint tubereulca appears on the side of the smaller limb,
and a row of depressed bullae ie shown on the ventral border. As far as can be
seen this apecies is not unlike the figures given by Stolley (1912, p. 11, 14, pi, 1) for
"Ancyloceras" pataffonicunt, from the district of Lugo San Martin in western Argentina,
Stolley regards hie species as rapresenting an upper Xeoconiian or Aptian
horizon, perhaps near that of the present species. The nearest European analogue
foe which a description has hcon found is N Aneyioc«ra»" ofiomfwm von Koernsa. Moat
of the species and examples of Hamiticeras so far obtained from the Cottonwood
district belong in, or above, the Argonaut zone of the Horsetown group, here regarded
aa being middle Aptian in age.
Hamiiicerai aequic-osialum (Gabb)
(Flute IT, Siurra I, Si, 3; plila ft. Stun 4)
Pfythoctras aeijuicostatus GABB, Paleont. Calif., vol. 1, lfKH> p. 74, pi. 13, fig. 20;
North fork of Cottonwood Creek (not Hehcanajlus aequicoiiatua GAUD, vol. 2,
1869, p. 141, pis, 25,20, SOa),
Hamites (Piyckoa>raB) aequicosiatua (Gahb) ANDERSON, Calif. Acad. Sci., Pr,,
3d ser., vol. 2,19€2, p. 30; Locality as by Gabb.