PALAEONTOLOGY OF CALIFORNIA. 



On comparing the Californian with the New Jersey species, I find that there 

 are differences in form sufficient to warrant their separation. Mr. Conrad having 

 proposed a new name for the Western shell, I am obliged to adopt it, though I 

 should have preferred his choosing some other appellation. The present species is 

 broader in proportion to its length, than the casts in the New Jersey marl, which, 

 though all more or less imperfect, seem to have been remarkably long and straight. 



PECTEN, Brug. 

 P. TRASKII, Gabb. 



PI. 32, Fig. 96. 

 (Pecten Traskii, Gabb; Pal. Cal., Vol. 1, p. 200, pi. 26, fig. 187.) 



This rare shell was originally known by but two specimens from the loose- 

 grained sandstones of Texas Flat, Placer County. A third has since been found 

 by myself in the greenish rock on the north shore of Departure Bay, near Nanaimo, 

 Vancouver Island, and which throws some additional light on the specific charac 

 ters. The shell is very thin, and the surface, of which a fine fragment is pre 

 served, has a slightly different ornament from the figure in the first volume. The 

 lines in the interspaces between the ribs, which I mentioned at the time as being 

 represented too numerous in the figure, are elevated threads, slightly irregular in 

 their direction, and radiate from the middle. The figure above quoted represents 

 their character near the side of the shell. The present figure represents the middle 

 of the surface. The imbrication of the ribs is produced by these fine lines crossing 

 them. So far as we know at present, the species is confined to the Chico Group. 



P. MARTINEZENSIS, n. s. 



PI. 33, Fig. 96. 



SHELL minute, thin, elongate, equivalve, equilateral; sides 

 straight above, below forming with the base a regular curve. 

 Lower valve, right auricle deeply emarginate, narrow; left smaller. 

 Upper valve, right auricle small ; left large, margin slightly sinuous. 

 Surface ornamented by numerous fine radiating ribs. 



Length from beak to base, .34 inch. 

 Not common in the Martinez Group, Martinez. 



From the other Pectens of the California Cretaceous, this species can be dis 

 tinguished by its small size and radiating ribs. I was formerly inclined to believe 



