LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

debcbiption of species 130
ATau/iIiw aeeri/ft Anderson, n. sp.
(Plat* 10, figura 2)
Mature shell large, sub-globose; umbilicus nearly closed; scetion of whorl broader
than high; septal sutures simple, curving normally forward above the umbilical
border and slightly backward near and upon tbe ventral surface; surface of holotype
retaining little of the shell, showing only faint growth lines rising vertically on
the lower half of tho whorl but curving sharply backward on the upper part of the
side, and forming a sharply rounded sinus in the ventral zone,
The holotype (Calif. Acad. Sci. type Coll.) is unlike any other species described
from the West Coast. It is an immature, although well-preserved, shell having the
following dimensions: maximum diameter, 72 mm,; width of umbilicus, 3 nun.;
height of whorl, 40 mm.; width of whorl, 48 mm. A fragment of a larger example,
obtained from the same bed, shows a miiimutn diameter of 110 mm. and a thickness
proportional to that of the holotype. The holotype was found by Chas. V. Averill
at Locality 1347 (Calif. Acad. Sci.), in the Barr zone, near the middle of tbe Horsetown
group, 5 miles south of Ono, Shaata County. It was associated with Acroleuthi*
aboriginalis nov., Parahnplit&idce up,, Gabbioca-as wintunium nov., Chelonieerat sp.,
and Syncyclonema califomica (Gabb). This is the earliest spcciea of Nauliltit yet
recorded from the Cretaceous of the West Coast.
AMMONOIDEA
PHYLLOCEBATIDAE Zittel
PhylloccraJ Stiesa
Phylloccras occidentale Anderson, n. sp.
(Plat* 12, Sgura 1, 5}
No complete example of this species has yet been obtained, although four imperfect
specimens in tbe California Academy of Sciences seem to belong to it. They
were found in three different zones, the lowest in the upper beds of the Paskenta
group, the next in the lowest beds of the Horsetown group, and the other in the Barr
eone of the latter.
The last example is the holotype (Calif. Acad.Sci. type Coll.); it is wholly septate,
containing no part of the body-chamber. The shell ia roundly inflated, ongustumbilicate,
deeply involute and distinctly castatc. The shell increases rapidly in section,
which is broadly ovate, the greatest thickness being a little below the ventral border.
Between the broad coatae are broader interspaces, about 27 to the whorl. Most of
the ribs arise near the umbilical border, although some secondary riba arise near the
middle of the aides. All the riba are much reduced in strength in crossing the abdomen.
The primary riha are inclined rather strongly forward near the umbilicus,
but ascend on the sides nearly vertically and show a alight forward curve on the
ventral zone, Tbe umbilicus, quite narrow nt bottom, expands into a broad funnelform
depression, the walla sloping upward from the center. The specics has much
resemblance to Phylloceras infundibulum d'Orbigny, from the lower N'eocomian
(lower Barremian or upper Hauterivian) of western Europe, but it is thicker in form
and has fewer and more widely spaced riba. Tbe holotype (Calif. Acad. Sci. type
Coll.) has the following dimensions: greatest diameter, 48 mm.; diameter of umbilicus,
2 mm.; height of whorl, 18 mm.; width of whorl, 23.5 mm.; umbilical ratio,
.0-12:1.
The aepta have tbe form and character of those of PAjfJtoeeras rouyanum d'Or-