190 PALEONTOLOGY OF THE SURVEY. 



coast deposits, consisting of recent species, among which I recognize Pachydesma crassatelloides , 

 Con. Venus Nuttali, Saxidomus Nuttali, and other species -which live in the same latitude. This 

 is most likely a recent, or post-Pliocene formation. It occurs in the valley of San Luis Ooispo 

 and at Santa],Barbara. 



The laro-e Pectens, so like to Virginia species to which I have alluded, suggest the probability 

 that lart^e species of Busycon may yet be found in California. If so, it will be very interesting 

 to compare them with the eastern forms. 



I have no doubt but that the Atlantic and Pacific oceans were connected at the Eocene period ; 

 and the fossils herein described afford strong evidence that the connection existed during the 

 Miocene period. 



Of the Miocene shells collected by Mr. Blake in California, and described by me, I believe 

 that no species, except Pecien deserti, and perhaps Anomia subcostata, is to be found in the present 



collection. , 



Yours, &c., T. A. CONRAD. 



Dr. Antisell. 



HINNITES, Defranct. 



HraNiTES CRASSA, PI. 1, figs. 1 and 2. — Ovate or subovate, thick, irregular, with large, rounded, 

 unequal, radiating, irregular ribs, squamose, and with foliated spines on the lower part of the 

 valves or near the base ; intervals of the ribs with 3 or 4 squamose, prominent lines ; hinge 

 profoundly thickened ; fosset profoundly excavated, angular ; muscular impression very large. 



Locality. — Santa Margarita, Salinas valley. 



This species is remarkable for the thickness of the hinge and the upper part of the valves in 

 old specimens. It resembles the recent Californian species E. gigantea, Gray ; and it probably 

 attains a larger size than the latter. 



PECTEN, Un. 



Pecten Meekii, pi. 1, fig. 1. — Suborbicular, compressed; ribs about 19 ; lower valve convex, 

 with broad ribs, not very prominent ; convex depressed on the back, angulated on the sides, 

 about as wide as the intervening spaces^ and scarcely prominent at the base ; upper valve con- 

 vex depressed, with narrower and less prominent ribs, ears equal, moderate in size. 



Locality. — San Raphael hills, California. 



Named in honor of F. B. Meek. A very large species, comparable to P. Jeffersonius in size, 

 but very distinct from all of the large Pectens of the Atlantic States. The upper valve is 

 nearly flat, and both are thin for so large a shell. 



Pecten deserti, Conrad, (Blake's collection, desc. p. 15.) — Suborbicular, both valves convex; 

 ribs about 23, rounded, somewhat flattened towards the base, about as wide as the interstices, 

 in the lower valve much wider than the interstices, and the valve more convex than the opposite 

 one • ears equal in the upper valve ; left ear of lower valve extended downward, and very 

 obliquely striated ; cartilage pit profound ; a submarginal channel parallel with the upper 



margin. 



Locality. — Carrizo creek, Colorado desert ; Cafrizo creek of Estrella river. 



Pecten discus, PL 3, fig. 1.— Suborbicular, slightly oblique, profoundly compressed or dis- 



