PALAEONTOLOGY OF THE SURVEY. 
191 
coidal, thin ; ribs about 17, rather distant, not very prominent, narrow, subtriangular, slender 
and more distant towards the lateral margins ; ears very unequal, rather small. 
Locality. —Between La Purissima and Santa Inez. 
This species is described from a cast beautifully preserved in indurated clay. The height is 
about 2 inches. The upper valve appears to have been nearly flat. 
Pecten magnolia, PI. 1, fig. 2. —Suborbicular, ribs 11, very large, prominent, convex- 
depressed on the back, -laterally angulated, longitudinally rugoso-striate. 
Locality. —Santa Inez mountains, Santa Barbara county, California. 
This species will compare in size with P. Jejfersonius, Say, and is so remarkably similar to it 
that it may prove to be the same species when more perfect specimens are collected. 
Pecten altiplicatus, PI. 3, fig. 2. —Obtusely ovate, thin ; ribs squamose, slender, 9 of 
them distant, profoundly elevated, an intermediate small rib and fine radiating strim, ears-. 
Locality. —San Raphael hills, Santa Barbara county. 
There is but one imperfect valve of this species in the present collection. . It is remarkable 
for the great prominence of its larger ribs. Height 2| inches. 
PALLIUM, Conrad. 
Pallium Estrellanum, PI. 3, figs. 3 & 4. —Suborbicular; lower valve ventricose; ribs about 
17, broad, flattened, not very prominent, with an intermediate small rib, longitudinal, sulcated 
below the umbo or bilinear ; ears rather small, equal, with 5 or 6 radiating prominent rugose 
lines. Height 4 inches. 
Locality. —Estrella, California. 
The flat valve of this species does not accompany the specimen of the other valve. The shell 
attains a larger size than any fossil janira (which it resembles) I have heretofore seen. The 
hinge is furnished with 6 distant diverging prominent teeth, and presents a marked contrast to 
that of the genus Pecten, more nearly resembling the hinge of Spondylus. The specimens are 
imperfect and worn, but there are indications on one or two that the ribs were carinated or 
sub-carinated on the margins. One small specimen has the ribs inferiorly ornamented with 
fine, rugose, prominent transverse lines, and each rib with three longitudinal prominent striae, 
and is also striated longitudinally. 
This genus originated in the Miocene period, and there it attained its maximum in size and 
prominence of the generic character. Hinnites also and pecten have similar gigantic propor¬ 
tions in the strata, which I have considered the equivalents of the English Miocene, and which 
certainly occupy a stratigraphical position immediately above the Eocene formation. 
SPONDYLUS, Rond. Lam. 
Spondylus Estrellanus, PI. 1, fig. 3. —Obtusely-ovate, both valves ventricose; ribs about 
17, not very prominent, rounded, rugose, interstices convex-depressed; valves with radiating 
striae, distinct about the base, obsolete above; posterior side sub-cuniform; cardinal area 
narrow. 
Locality. —Estrella valley, California. 
This species has thick valves, is about four inches in height, and has entire or unarmed ribs; 
the ears are broken, but they are apparently very unequal, and the beaks are not very distant. 
The lateral tubucles or teeth of the hinge are prominent, conical, and very robust. In some 
specimens the radiating striae are very distinct near the posterior margin. 
