16 H. Doc. 129. 



This large oyster shell probably belongs to the same deposit which 

 contains 0. vespertina and Anomia subcostata. The surfaces of most 

 specimens have a resemblance to worm-eaten wood, having been evi- 

 dently sculptured by some marine animal.* 



PENITELLA. ^ 



37. P. SPELCEUM, Con., pi. , 43, 43a, 43&. Ovate, ventricose, 

 anteriorly inflated with fine radiating lines and transverse wrinkles, 

 transverse furrow medial, angular, slightly oblique; posterior side 

 cruneiforrn, 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 from the recent species of the 

 California coast, P. jpenita, Conrad. 



FISSURELLA, Lam. 



38. F. CRENULATA, Sow., pi. , fig. 44. Oblong subovate, slightly- 

 contracted laterally opposite the foramen . Shell with numerous radia- 

 ting 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, Zankerville catalogue. 



Locality. San Pedro. Recent formation. This is the largest fossil 

 species I have seen. 



CREPIDULA, Lam. CRYPTA, Humph. 



39. c. PRINCEPS, Con., pi. , fig. 52. Oblong, ovate, thick and 

 ponderous, contracted or compressed superiorly ; upper side or por- 

 tion of the shell sloping ; back regularly rounded ; beak prominent, 

 rounded, laterally curved ; apex distant from the margin of the aper- 

 ture ; diaphragm 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. 



NARICA. 



40. N. DIEGOANA, Con.,pl. , fig. 39. Subglobose, sides flattened; 

 obtuse above. 



Locality. San Diego. Miocene? 



Partially embedded in the rock and its form not accurately de- 

 termined. 



* These specimens were picked up by Dr. Heerman in the bed of the creek, and were un- 

 doubtedly derived from a portion of the stratum of shells that I found in situ. 



W. P. BLAKE. 



