LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

description of species 175
In the Museum of Paleontology, University of California, there are a number of
specimens representing types found in France, and in the California Academy of
Sciences are others from western Europe. In an earlier study of these forms and
their analogues from California their close rel ationship was indicated by Anderson,
(1302a, p. 108), although the conclusion was reached that many of the surface char*
acters in the California examples, as well as thoBe from France, were not constant.
In addition to the remarks formerly given concerning the forms found in the Cottonwood
district, Shasta County, the following notes may bo of value.
The most common form in the upper Horsetown beds in the Cottonwood district
seems to extend through a considerable stratigraphic range, appearing first in the
Buenaventura zone, but also at higher levels, up to the Neptune zone, and thus being
found through at least 1350 feet of strata. A typical example from the Perrin zone
(Locality 1668, Calif. Acad. Sci.) affords the following measurements: greatest diameter,
84 mm.; width of umbilicus, 30 mm.; height of wborl, 30 mm.; width of whorl,
40 mm.; umbilical ratio, 0.357:1.
In this example, the last wborl is two-thirds septate and includes about 22 ribs;
the most spinose ribs (diameter 72 mm.) show seven nearly conical tubercules, of
which the bases are slightly elongated in the direction of tha rib, although this is not
constant; in earlier ribs the direction of elongation is transverse to that of the ribs;
ia younger whorls the tubercules of the second row shove the umbilical border are
more Bpine-Iike, some of the spines rising 2 mm. above their bases. An example
from the Buenaventura zone, west branch of Hulen Creek, showa the same form of
wborl, the same number and character of ribs, with the same broad interspaces, and
spines of tbe same kind, yet the interval between the two horizons is hardly less than
700 feet.
In most examples the ribs are narrower and the interspaces broader than in tho
examples illustrated by Spath.
DoutrilUieeras aurarium Anderson, n. sp.
(Pi»tn53, figim l)
A single example of a species cf Dauvill#ictra» related to tbe preceding was found
in the Bradley zona on the east brnnoh. of Hulen Creek. This example has been
carefully compared with others of the genus, but it shows specific differences from
all of its congeners. It possesses an umbilicus relatively broader than any of the
others, and, although tho number of ribs is nearly the same as in Douin'ikiceraj mammiUalvm,
tbe tubercules are less numerous, more rounded, and on the ventral borders
they are not always multiple and do not appear to be spinose. The holotype (Calif.
Acad. Sci. type Coll.) bos the following dimensions: greatest diameter, 85 mm.;
width of umbilicus, 35 mm.; height of whorl, 30 mm.; thickness of whorl, 40 mm.;
umbilical ratio, 0.412:1. In its younger stages, the costal tubercules appear in three
rows, in which their she varies greatly. The sulc&te ventral zone is rather narrow
and has a sone of mostly multiple tubercules bordering it on either side; a second row
consisting of single rounded tubercules appears near the middle ot the side; even in
its younger stages these rise in rather blunt points, scarcely to be called spines; a
third row, much reduced in size, is developed on the umbilical border, but only in
young stages of growth. In its more mature stages all the costal tubercules tend to
become obsolete.
Dottvilleiceran restitutum Anderson, n. sp.
(Flute H. flaur« 2)
Ammonites Jfemondii GABB (in part), Paleont. Calif., vol. 1,1864, p. 06, pi. 12, fig. 15,
only; "nodose variety" (not pi. 12, figs. 14, 14a); Cottonwood Creek, Shasta
County.