176 WEST COAST SHELLS 



eastern species found in San Francisco Bay, espe- 

 cially around the oyster beds. It was probably intro- 

 duced with young oysters from the Atlantic coast as 

 were so many of the foreign creatures found in that 

 bay, and it has now become quite common. In size 

 and appearance it considerably resembles Murex 

 circumtextus, Figure 157, but the shell is thinner and 

 the spire longer and more pointed. 



In fact, my first knowledge of its existence in San 

 Francisco Bay was brought by a bright boy who told 

 me that among the shells he had gathered on the Ala- 

 meda beach were specimens of Ocinehra circuintexta. 

 I knew that that species loved the breakers of the sea 

 too well to flourish in the calm waters of a quiet bay, 

 and I assured him that he must be mistaken; but he 

 brought specimens to prove that he really had found 

 the shells, and then it became evident that an unex- 

 pected species had appeared. 



As the name indicates, the shell is ash-colored, 

 though it is reddish internally. Specimens may read- 

 ily be captured at low tide, and often the little egg- 

 vases may be observed, attached to stones or posts. 

 This species is not a welcome addition to our western 

 fauna, for the "Drill" is a determined enemy of the 

 oyster, boring holes into the young ones and quickly 

 destroying them. It is thoroughly detested by the 

 oystermen, who would be glad to exterminate the 

 whole species. 



Our next species is named '^rophon belcheri^ Hds., 

 Belcher's Trophon, (Chorus belcheri). This large 

 mollusk, whose shell is so well shown in Figure 167 

 is found chiefiv on the coast of southern California. 



