54 CALIFORNIA SEA SHELLS. 



as its name indicates. It would be impossible 

 to give a figure which would illustrate all its 

 phases, for it is exceedingly variable. Normally, 

 it is an oval little shell, with regular sculpturing. 

 But it has a habit of getting into a hole in the 

 recks and growing to fit the premises ; so it fre- 

 quently is much distorted, generally growing 

 long and narrow. The ligament is external ; the 

 hinge teeth often become nearly obsolete, as well 

 as the sculpturing, and the shell becomes thick 

 and rough. Color, white ; breadth, from one- 

 half to three-fourths of an inch ; length, one to 

 two inches. 



Tapes tenerrima, Cpr., Fig. 2, PL I, is often 

 four or five inches in length. It is thin, flat, and 

 marked by innumerable fine radiating lines, and 

 many small concentric ridges. The cardinal hinge 

 teeth are near the anterior extremity of the shell ; 

 the ligament is long and external ; the pallial 

 sinus is very deep. This species is sometimes 

 thrown up from deep water, by storms. Its color 

 is white, somewhat yellowish in places. 



Rupellaria lamellifera, Conr., Fig. 4, PI. XI Y, 

 is a nestler among rocks. It has a strong, white 

 shell about an inch in length, and may be easily 

 known by the ten or twelve large, thin, concen- 

 tric lamina?, which mark its sides. It has no ra- 

 dial lines, and can thus be distinguished from 

 the variety ruderata, Desh., of Tapes s'.aminea. 



The largest of all that class of mollusks com- 

 monly called clams, is known by the name Schi- 

 zothoerus JVtittallii, Conr., though by some it is 

 called by the more simple term, u Washington 

 Clam." It is a huge, burrowing mollusk, some- 



