LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

190 LOWER CRETACEOtffi DEPOSITS IN CALIFORNIA AND OREGON
but little variation they conform to the dimensions and sculptural features of tho
holotype, which measures aa follows r greatest diameter, 122 mm.; width of Umbilicus,
36 mm.; height of whorl, 52 nun.; thickness of whorl, 32 mm.; umbilical ratio, 0.295; 1,
The species ia found at other localities on the west border of the Great Valley embayments
as far south as Puerto Creek, but not abundantly. In the Neptune zona on
Hulen Creek it ia associated with Dcsmoceras mcrriami (Anderson), Lytoeeras nep-
{um'uni nov., Lytoeeras aurarivm nov., and Dowvilleiceras mammiUatitm var. Its
chronological horizon is regarded as upper-middle Albian, and its stratigraphic
position is about 450 feet below the top of the Horsetown group at thia locality
on the east branch of Hulen Creek.
Tha apecies grew to a considerable size; fragments of it have been found that
represent examples having a diameter of more than one foot (305 mm.), and a thickness
of 2 inches or more. In old age most of tho riba became obsolete.
A small example of the species has been sent to the California Academy of Sciences
by Dr. J. B. Reeaide from a locality "west of the big bend of Young Creek, Chitina
Valley, Alaska," elevation 3450 feet.
Beudcmticeras hulenense Anderson, n. sp.
crut« 44, tips 3,4)
This species is closely related to the preceding and occura with it in many places;
it differs from it in its smoother surface, smaller umbilicus, and thinner section.
Tbe shell is without conspicuous ribs and is often quite smooth; the umbilical walls
are abrupt, angulated at the top at its juncture with tbe flattened sides; surface
marked by faint growth lines which cross the ventral area, occasionally forming a
varex-like ridge on the periphery which has a slight sinus; surface markings irregularly
spaced. The holotype (Calif. Acad. Sci. type Coll.), partly septate, has the
following dimensions: greatest diameter, 125 mm.; width of umbilicus, 35 mm.;
height of whorl, S3 mm.; thickness of whorl, 32 mm.; umbilical ratio, 0.280:1. In
the collections of the California Academy of Sciences there are 25 or more examples
representing nearly all sizes of whorl . They were obtained at Locality 1659 (Calif.
Acad. Sci.), on the east branch of Hulen Creek, Shasta County. With little variation
they conform to the dimensions and sculptural characters of the holotype. The
same species has been collected at Horsetown and at other points in the Cottonwood
district; it occurs at the same horizon in western Glenn County and on Elder Creek,
Tehama County. An example was found by J. A. Taff and G. D. Hsnna on Elder
Creek, in a boulder buried in tho basal conglomerate of the Chtco series, evidently
derived from the upper part of the Horsetown group. Its horizon is thought to bo
that of tbe Xeptune zone, In which it occurs in its type district.
Beudanticeras haydeni (Gabb)
CPkta Sturm 3,3)
Ammonites Haydeni GABB, Paleont, Calif., vol. 1,1864, p. 02, pi. 10, figs. 3, 8a; North
fork of Cottonwood Creek, Shasta County.
Deemoceras {Puzosia) Haydeni WHITBAVES, Geol. Surv. Canada, Mes. Foss., vol, 1,
pt. 4,1900, p. 286: Maude Island, Queen Charlotte Islands—A.VDEBSON, Calif.
Acad. Sci., Pr., 3d ser., vol. 2,1902, p. 41; Horsetown beds, Shasta County.
According to Gabb's description, and as observed by the writer, the shell of thia
species is eompresscd, thin, and discoidal, flattened on the aides and narrowly
rounded on the periphery ; umbilicus relatively small, with abrupt walls. Flattening
of the ventral zone is rarely if ever seen, although Gabb notes this feature to his
description. The species is more frequently found in the basal beds of the Chico