LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

176 lower chetaceqtfs depobits in california and oregon
In Gabb's (1864, p. 66, pi. 12, fig. 15) description of AcanthopliUt remondi (Gabb)
be referred to a "second form," which he also figured. His specimen has not been
found, although it may later be discovered among the collections in the Museum of
Paleontology, University of California.
An example now in the Museum of Paleontology was obtained by the writer in
1897 at the old mining oamp of Eoreetcvrn, Shasta County. This specimen seems to
fulfill the essentials of Gabb's figure and description. It is made tbe holotypB cf the
above species. In this example the shell la large, discoidal, with moderately broad
umbilicus, strongly coatate; with 34 ribs on the adult whorl, 55 on last whorl; umbilicus
deep, walla abrupt, rounded or auhangular on the border; ribs arising on the
umbilical wall, at first sloping backward, then rectiradlate, tubcrculata on younger
whorls only; ribe non-tuberculate above a diameter of 90 mm.; below this diameter
the riba bear three to five rounded, spinoie tubercules, not quite evenly spaced;
tubercules near the periphery stronger than below; umbilical nodes weaker in young
whorlB, becoming more developed in older BtageB; body-chamber occupying twothirds
of the last whorl upon which the umbilical bullae are well developed, giving
rise to two or three slightly Binuoua riba which cross the rounded ventral zone without
interruption.
On the holotype the greatest diameter is 153 mm.; diameter of umbilicus, 40 mm.;
height of whorl, 65 mm.; width of whorl, 75 mm.; umbilical ratio, 0.301:1.
According to Gabb's statement his figure represents the inner whorls of a much
larger shell, measuring 15 inches in diameter.
CEELONICERATIDAE Spath 1921
Spath baa included in thia family a number of related genera, of which only the
following two have been found in the Lower Cretaceous of California:
Prochtlonicera* Spath; genotype, .4mmoniUe »(aJ>i«Jtu (d'Orbigny) and
Chelonieerot Hyatt 1899; genotype AmmtmilM royerianut (d'Orbigny).
Both of these generic groups have been found in the upper part of the Shasta
series, the first in beds near the base of the Horsetown group (upper Barremian)
and the second near the hose of the Hulen beds in strata that seem referable to the
lower Albian.
Chelonicerat Hyatt 1003
Cheltmicerae j-fpitwfcflnHm (Gabb)
(Pluto 47, fiput 3)
Aimnenttft SLOJIEJFCANUA GABB, Paleont. Calif., vol. 2, 1800, p. 135, P!. S3, figs. 16,
10a; "Shasta Group," Cottonwood Creek, Shasta County, California.
AcontAoceros etalicxkanum Um.ro, Wemsdorfer beds, 1883, p. 264.
Douvilleic^rat aloliczkanum DouviLLfi; Valley of the Amazon, Ann. Soc. Zool. Malac.
Belg., T. 41, 1906, p. 116, pi. 1, fig. 1.
Chelonicerat etoiiczkanum BASSE, SOC. Geol. France, Bull, T. 28, 1928, p. 141, pi. 8,
fig.2 ; Middle Cretaceous, Republic of Colombia.
The characterization of thia spccics by Gabb seems to need no special comment.
Xcvertheleas, in view of its exceptional occurrences and interest, some additional
notes may be helpful in determining its geographic range.
The holotype of the species is in the Museum of the Academy of Natural Sciences
of Philadelphia. Gabb's drawing seems to have included a partial restoration, but
otherwise is excellent. The 29 ribs are of two kinde, major and minor, alternating
on parts of the shell only. The major ribs bear three rowa of lubcrculee, elongated
in the direction of the ribs, one row being on the umbilical harder, one on tbe ventral