108 WEST COAST SHELLS 



while specimens of six inches are not uncommon. 

 Its name is Schizothczrus nuttallii, Conr., the Wash- 

 ington Clam. This huge mollusk burrows deeply in 

 the mud, and is therefore rather hard to capture. It 

 makes an excellent chowder, however, and a very 

 few clams are sufficient lor the wants of a large 

 family. 



The shell is more or less oblong, bulged, rather 

 thin, and it gapes widely at the end where the long 

 siphons pass out. The sinus, as might be supposed, 

 is very broad and deep. The hinge-teeth are small, 

 while the cartilage pit is large and deep. The white 

 shell is covered with a thin epidermis. This species 

 delights in muddy bays, and is found along the 

 whole coast. 



Passing now to a very different group of shells 

 we come first to ^hracia curta^ Conr., the Short 

 Thracia. In form and markings this shell resembles 

 Figure 43, though it is somewhat oblong and also 

 wrinkled at the rear end of the valves. Ligament 

 external, hinge-teeth small, sinus shallow, length 

 from an inch to two inches, thracia undulata^ 

 Conr., the Wavy Thracia, also called plicata^ is a 



rare species that is larger 

 and thinner than the last. 

 Figure 84 represents the 

 inside of the left valve of 

 Fcriploma planiscula^ Sb}^, 

 ,,. „, the Silver Lantern-shell. 



This is a pretty species 

 easily recognized by its peculiar spoon-like hinge- 

 teeth, one of which is found in each valve. Oblong, 



