LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

DESCRIPTION OF SPECIES 203
form, and having a tripartite first lateral lobe, in which the finer elements terminate
in sharp digitoid points.
This species belongs to the group of Moplocriocerm laevitueulum (von Koenen).
The holotype (Calif. Acad. Sei. type Coll.) was obtained at Locality 1661 (Calif.
Acad. Sci.), a mile west of the Murphy house in the Roaring River district, where it
was associated with Pseudocrioceraa indopadficum nov., /S/nuJicraecerat poniente
nov., and Inoceramus ovatoidta nov.
The holotype is much broken but permits of restoration, and its general form ia
shown in the drawing, which is made from careful measurements.
Haplocrioctrat yollabotlium Anderson, n. sp.
(PUtcTi, firun 3)
Because of the apparent "bundling" of the ribs at the umbilical border, this
apecies is placed here with some doubt as to its proper lineage. The shell ia large,
diseoidal, apparently compressed, having a crioceratid coil and strong, somewhat
"rurairadiate" primary ribs, between which the interspaces are relatively broad;
interspaces occupied by two to four fine secondary costae, which marge with the
primary ribs near the umbilical border; sides slightly flattened, section of whorl
higher than broad; whorls not contiguous, but apparently not leaving a regular spiral.
The holotype is a rook mold, represented by the plastotypo (Calif, Acad. Sci, type
Coll.), shown in the figure. It was found by A. I. Gregersen, on Browns Creek, 1}
miles southwest of the Clements ranch in eastern Trinity County. Its stratigraphic
position is apparently about 600 feet beneath the zone exposed at Clements ranch,
and probably not far from the horizon of Crioceras latum Gabb. It is thought to
represent an upper Paakenta horizon, not far from that of the Hamlin-Broad zone,
Locality 113 (Calif. Acad. Sci.), southwest of Ono, Shasta County.
In its ribbing and form this species has some resemblance to Criaccrai bederi
Gerth, though less to Crtoeeras andinum Gerth, from the Lower Crctsceous ef the
Rio Diamante, Argentina.
SAasiim'ceera! Anderson, n. gen.
In the group of crioceratid forms for which this name is proposed hoplitid characters
are more prominent than in other related groups found in the Shasta series
in California. These characters seem to rcfleet Neocomiies more nearly than any of
the other hoplitid groups, although no close relationship is apparent. Characteristics
of the genus are seen in its form, ribbing, ornamentation, manner of uncoiling,
and, with growth, its progressive changes in form and ornamentation. In its earlier
stages the coils are closely approximate but they soon become separated, and finally
the shell sends oS a long, curved arm (body-chamber), although without developing
a recurved limb. In none of the several apecies of this group so far found have any
traces of dorsal (umbilical) tubercules been observed, even in young stages of growth,
having a diameter cf 25 mm. or lesa. In all eseea the costae begin i n a short forward
flexure on the dorsal border, cross the sides in an openly sigmoid curve, and on the ventral
borders develop rounded tubercules, which in adult stages become the moit notable
feature of the shell, The sides are flattened, or but little convcx, the section of tho
whorl is subquadrate, the thickest part being n little above the dorsal margin, from
which zone the sides converge toward the periphery. The costae are at first fine and
crowded but with growth become heavier and more widely separated; in young stages
these often divide, though no such tendency ia seen later; all costae (or riba) cross the
ventral zone without interruption, although on the venter they may be somewhat