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