326 APPENDIX. 
O. vespertina. Con. Jour. Acad. Nat. Sc., new series, vol. 2, part 4, p. 300. 
This species is very similar in form and plications to O. subfalcata, Con., of the Virginia 
Miocene. e 
37. o. HEERMANNI, Con. Acad. Nat. Sc., Philadelphia, Pl. , figs. .— Very irregular in form, 
ovate and often dilated ; lower valve shallow ; exterior very irregular, with large distant angu- 
lar radiating ribs, and with pits and irregular cavities; cartilage pit broad and oblique; upper 
valve flat or concave, with a profoundly irregular surface. Length 53 inches, height 6} inches.! 
Locality.—Carrizo creek, Colorado desert. Dr. Heermann. 
This large oyster shell probably belongs to the same deposit which contains O. vespertina and 
Anomia subcostata. The surfaces of most specimens have a resemblance to worm-eaten wood, 
having been evidently sculptured by some marine animal.? 
PENITELLA. 
38. P. sPELGA, Pl. V, 43, 43a, 43b.—O vate, ventricose, anteriorly inflated with fine radiating 
lines and transverse wrinkles, transverse furrow medial, angular, slightly oblique; posterior 
side cruneiform, truncated at the extremity, which is direct, and with prominent, acute, 
wrinkled concentric lines; front dorsal margin widely recurved, trisulcate; cardinal plate 
broad, sulcated process slender, direct, 
` Locality.—San Pedro. Recent formation. 
No trace of the coriaceous cup, characteristic of this genus, remains in the collection. It is 
widely distinct rom the recent species of the California coast, P. penita, Conrad. 
FISSURELLA, Lam. 
39. F. CRENULATA, Sow., Pl. V, fig. 44.—Oblong subovate, slightly contracted laterally oppo- - 
site the foramen. Shell with numerous radiating conspicuous compressed lines; foramen large, 
subovate, not nearly central; inner margin crenulated, thickened basal margin sinous ; inner 
margin of foramen broadly callous; cavity profound. 
F. crenulata, Sowerby, Tankerville catalogue. 
Locality —San Pedro. Recent formation. This is the largest fossil species I have seen. 
CREPIDULA, Lam. CRYPTA, Humph. 
40. c. PRINCEPS, Con., Pl. VI, fig. 52, 52a.—Oblong, ovate, thick and ponderous, contracted 
or compressed superiorly ; upper side or portion of the shell sloping ; back regularly rounded ; 
beak prominent, rounded, laterally curved ; apex distant from the margin of the aperture ; dia- 
phragm very large, with a very sinuous margin. 
Locality.—Santa Barbara. Recent formation. : 
This is the largest species that has come under my observation, and is very distinct from any 
that has yet been described. 
mer NARICA. 
41. N. DIEGOANA, Con., Pl. V, fig. 39.—Subglobose, sides flattened; obtuse above. 
Locality.—San Diego. Miocene? 
Partially embedded in the rock and its form not accurately determined. 
' The figures which are given in Plate — are from a smaller and more characteristic specimen than that of which the 
dimensions are given by Mr. Conrad. The specimen which is figured is, however, much worn and broken on the edges 
? These specimens were picked up by Dr. Heermann in the bed of the creek, and were undoubtedly derived from & wem 
of the stratum of shells that I found in situ. X 
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