LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

203 LOWER CRETACEOUS DEPOSITS IN CALIFORNIA. AND OREGON
102 mm.; diameter of umbilicus, 32 mm.; height of whorl, 43 urn; width of whorl,
36mm.; umbilical ratio, 0.313:1.
The inner whorla are more compressed than tho outer whorlB, and the rihs tend to
develop tubercules on the umbilical borders, which later disappear, leaving the border
of the older whorls smooth. Only three examples of this shell have been found.
Its horizon is near that of its congeners, which is about 900 feet below the top of the
Horsetown group in tbe Hulen Creek district. Tho holotype was found in the Perrin
zone at Locality 152 (Calif. Acad. Sei.) on the east branch of Hulen Creek, where it
was Associated with Deamaceras merriami, DouvilleiceTas ma>nmi(ioiuw var., and
Phylloceraa thereeae nov. Spath has referred S. aacrameniica (Anderson) to "Pleuro-
•pachydiecua'' Hyatt, whose genotype is Dexmaceras merriami (Anderson), to which
it has little resemblance except in tbe character of the suture lines. The name
"PieuropotJijifTJcui" Hyatt is clearly a nomen nudum.
Sonnerada stanloni Anderson
(Plata SO, figuro {, 4,7)
£onnera(ICI«tofttoni AKSBRSOM, Calif. Acad. Sei., Pr., 3d ser., vol. 2,1902, p. 105, pi. 3,
figs, 91-03; pi. 10, fig. 108; Horsetown, Shasta County, California.
The original description of thia specieB, somewhat emended, reads in part as
follows:
"Shell small, not often above a diameter of 35 mm.^discoidal, laterally compressed
and flattened; sides converging gently toward the periphery; ventral surface rounded
or subquadrate; umbilicus not Large, less than one-third the total diameter, generally
funnel-form, due to its sloping sides and the increasing thickness of the whorls;
surface ornamented by about 30 transverse flexuoua ribs which usually cross the
ventral surface, arising at the umbilical border In distinctly tuberculide nodes, from
which they branch in pairs. The surface of the shell, both on tbe ribs and in the
interspaces, shows fine striae, always parallel to the ribs. The Buture tine ia simple,
consisting of a few broadly rounded saddles, and wide lobes with very short branches.
The saddles are but little indented, are aividod by rounded incisions; lobes unequally
tripartita."
This apecies was once abundant at Horsetown, and many were collected at this
place by the writer but most of them were lost in the San Franoisco fire of 1D0G.
Many of its congeners have since been found on the east branch of Hulen Creek,
about 000 feet below the top of the Horsetown group.
This species was proposed as the genotype of "Colobdceraa" by Crickmay (1927,
p, 603-616) hut upon what characteristics and for what practical use ia not made
clear, and It is therefore disregarded aa not sufficiently defined for adoption.
Sonneralia erotai Anderson, n. sp,
(Pint* 49. I. S, », 7)
Shell small, discoidal, compressed, having a email umbilicus and rounded, nearly
smooth sides and ventral border; sides flattened, ornamented chiefly by lines of
growth, costate only on and near the umbilical border, upon which appear 20 or more
rounded linear nodes, not rising to the middle of the side; only faint costal lines
appear on the ventral border, inclining forward; section of whorl narrowly clliptical;
Suture lines similar to those of .Sonncrajia atantoni, with which it occurs.
The holotype (Cftlif. Acad. Sci. type Coll.) was found by the writer at tbe old
mining camp of Horsetown, where it waa associated with PUJTOJI'O JtojJmanni, Bfudanticeras
breweri, and Beudanliccraa haydeni Gabb, This is Locality 1344 (Calif.
Acad. Sci.) on Clear Creek, Shaata County. Four examples of the specics wera
found here, but it has not been found at any other locality.