34 WEST COAST SHELLS 



inches and a half in length. With pieces of these mussels, 

 sharpened to an exquisite edge and point, the Indians head their 

 harpoons and other instruments for lishing; they fasten them on 

 with a kind of resinous substance." 



Mytilus edulis^ Linn., the Edible Mussel, is the 

 same species that is found on both shores of the 

 Atlantic. The shell is smooth and regular, and is 

 covered with a dark, glossy epidermis. The shell of 

 this species is smaller than that of the last, and it 

 is more often found living in quiet water. In San 

 Francisco Bay a variety, glomeratus^ Gld., is found 

 clinging in large groups to posts and wharves. Its 

 length is seldom more than two inches. It is one of 

 the few mollusks commonly found for sale in the 

 San Francisco markets. 



There is another mussel, found chiefly in the south, 

 concerning which there has been much discussion. In 

 a former volume it was called Mytilus bifurcatus^ 

 Conr., but it seems to have been confounded with 

 another shell of the same name. In 1898 it was 

 renamed Mytilus stearnsi^ Pils. & Raym., Stearns' 

 Mussel, in honor of the late veteran conchologist of 

 this coast. Dr. Robert E. C. Stearns, and by this 

 name we trust that it will continue to be known. 

 Externally it greatly resembles Figure 16, though 

 it is usually considerably smaller. Internally it may 

 be distinguished from a Septifer by the 

 absence of a deck across the point of the 

 umbo. 



Figure 16 is a good picture of the little 



shell which resembles the one referred to 



above. Its name is Septifer bifurcatus^ 



FiT^is Rve, the Branch-ribbed Septifer. Its gen- 



