LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

228 lower cbetaceoub depobits in california. and oregon
Although Stanton seems to have noticed tho species he did not have examples
complete enough for a satisfactory description and illustration, and this condition
has been but little improved since. Many fragments have been found in the area
between Elder and Thomes creeks, Tehama County, and similar fragments have been
found in the upper part of the Paskenta group in tha Cottonwood district, Shasta
County. According to Stanton's partial description:
"It apparently has about the form of B. tehamaenaia, but the alveolus, with an
apical angle of about 26", is inclined toward the ventral side, so that its apex ia midway
between tho center and the ventral side, making the axis of the guard very
eccentric."
In the excentrieity of its axis this species resembles A. onwnsf* nov. but, in
addition to having a thicker and stouter guard and a more nearly circular seotion,
it represents a lower position in the sestion, namely, for tbe moat part the uppermost
portion of the Paskenta group. The holotype (Calif. Acad. Sci. type Coll.) consists
of a fragment of the upper half of a guard, having a length of 38 mm. and a lateral
diameter of 27 mm. It contains the lower part of the alveolar pit, which is axccntric
to the surface of the guard, and shows the axis inclined toward the ventral aide. At
its lower end the axis is midway between the center of the guard and its ventral surface.
The figured examples were obtained on the Wilcox ranch, 5 miles north of
Paskenta, where they were associated with AtteeUa crassa, A. eraasieoUia, Diehoto~
mitea grtgerseni nov., and Bachiaailct patkcTitacnsis nov. Its stratigraphic position
is in the upper part of the Paskenta group.
Acroleuthia miUhelli Anderson, n. sp.
ffjat* 60, ftiuri* I, !»)
The guard of this species is rather large, with sides nearly parallel in the upper
half but tapering to an acuminate point below; the section of the guard ia subcircular
above, but becomes somewhat flattened below, the lateral diameter being greater
than the dorso-ventral; ventral groove deep and broad, extending along most of the
guard, and terminating below at a point near the apex. Apparently the phragmaeone
is concentric with the sides of the guard, and no evidence has been seen that the
axis is excentrio, The holotype (Calif. Acad. Sci. type Coll.) was found in the
Mitchell zone of tho Horsetown group, at Locality 16157 (Calif. Acad. Sei.), not far
above the mouth of Mitchell Creek, 7 miles south of Ono, Shaata County. It has the
following dimensions: length of guard (incomplete), 115 mm.; greatest diameter, 21
mm. The species appears to bo related to A. fernsiuts nov. but is larger, has a
broader and longer ventral groove, and a relatively broader aeetioa. Its atratlgrnphio
position is also higher in the Shasta series, being but little below the Barr
zone, whereas the highest position of A, kernenaiz yet found was in the Ono zone,
near Ono. A. mitchtlli has been found on Fiddler Creek, associated with A, sAot{«nand
Shaslicriaceraa ponxente, in strata thought to be of Barremian age.
Aerofetttftw barrana Anderson, n. ap.
(Plata tt. fliura 2,2i>
The guard of this apecies is relatively short and stout and somewhat conical in
form; tho section is subcircular, flattened on the ventral side; lateral diameter a
little greater than the dorso-ventral; ventral groove broad and shallow, extending
from the lower part of the alveolar pit to near the apex of the guard; alveolar pit
concentric with the sides, central, short. The holotype (Calif. Acad. Sci. type Coll.)
was found in the Barr zone at Locality 1347 (Calif. Acad- Sci.) in the lower part of the