LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

130 lower chetaceous deposits ijf california and oregon
in almost the earliest beds of tbe Paskenta group, but at best they are ram, and
the family does not attain prominence until the latter part Of Horsetown time
(early-middle Albian). Prom this time on, they appear in increasing numbers up to
the close of Horsetown time (late Albian) and they are plentiful in tbe lower beds
of the Chico series (late Albian and Cenomanian time). It is not supposed that the
several generic groups in this family have had local origin, although there are reasons
for believing that most of them belong in a common lineage. Moreover, there appears
to be sequential order in their appearance in the Great Valley embayments,
and it may be possible to find there antecedents for some of them.
Without attempting at this time a discussion as to their origin and development,
we may at least indicate here a number of generic groups and their stratigraphies!
sequence, as follows:
Mdchiarite* Spath first appears in upper-middle Horsetown (mid-Aptian) time,
and continues only to the baae of the Hulen beds (lower Albian time),
Deamacerat Zittel (group of D, ooj/t), found only in upper Aptian horizons.
Puzovia Bayle, found in upper bed* of the Horsetown group (upper Aptian to
upper Albian time), continuing into the Chico series (Cenomanian time).
De&maceraa (Lalidortdhi) (group of ZJ, mern'omt), appearing first in the Perrin
zone with DouuiUeiceraa niamnullaltim var. (middle Albian time), but having its best
development in the Neptune zone (upper-middle Albian time).
Btudaniicerat Hitiel is found first in the Neptune zone, with the preceding, and
continues into the Chico series (uppermost Albian time).
It maybe added that Puzosia (group of P. planulata) is found with Ozyt rapid/xerox
packardi nov. in the upper part of the Horsetown group (upper Albian); Desmoeeraa
(group of D. jugate and D, alamottise nov.) also appears in the lower beds of the
Chico series with Pemnflvtena injlatu var. These forms are followed in the Chico
series by various others that are referable to either Deanwcerws, Puzoaia, or later
to Haitericeras, but these will be considered at a later time,
Spath bos proposed for certain Valanginian members of this family the generic
name Eodeamoeeras, but no forms referable to thia group have yet been recognized
in the California Cretaceous, or perhaps on the Pacific Coast.
It may be noted in passing that in their stratigraphic order all the recognized
genera of Ecsaoccratidae are preceded by the earlier groups of Parahoplitidae—
namely, by Parahoplitoidea Spath, and, except for AfeJeAioriles of the Aptian, by
several species of Parahoplilc*. Spath has supposed, however, that the family
Deaanoccratidae includes a heterogeneous assemblage of types having origin in
Phyllocer&tid&c or in part in Lytoceratidae, both of which abound in the lower
beds of the Shasta series (Paskenta group).
Dtamoccraa utH/i Anderson
(Plata 10. fifura 4-7)
Deemocerae voyi ANBEKSON, Calif. Acad. Sci., Pr., 3d ser., vol. 2, 1902, p. 100, pi. 3,
figs. SO, 30; North fork of Cottonwood Creek, Shasta County.
Shell rather small, discoidal or slightly inflated; umbilicus deep and narrow;
ventral surface rounded, sides sloping gradually to the ventral border; marked by
numerous fine flexuous growth lines and about six flexuous transversa grooves, seen
more often on the cast; grooves bordered by a alight ridge on the shell i ridges more
prominent on the periphery, here bending Strongly forward, forming a sinus; section
of whorl semi-elliptical in specimens of 50 mm. diameter, whereas it is more nearly
circular in younger shells, The involution is deep, the outer whorl embracing more
than three-fourths of the preceding whorl. The suture line is Deamoccratid, similar