20 MOLLUSKS FROM WEST COAST OF AMERICA— BALL. vol xviii. 



PERIPLOMA CARPENTERI, new species. 



This species is of inncli the outline of P. stearnsii, Ball, and is best 

 described by coiiiparisou with it. lu P. stcarnsii the shell is somewhat 

 less inflated and the beaks are nearer the posterior end, but nearer the 

 anterior end in P. carpentcri; in the latter the surface granules are 

 more crowded and coarser and not arranged in rows separated by a 

 clear space, as in P. stearnsii; the rostrum in P. carpenteri is less dis- 

 tinctly marked off from the arch of the base, the epidermis has a more 

 greenish tint, the interior is more j)early, with a larger pallial sinus, 

 and the chondrophore is wider and vertically, not obliquely, directed. 

 The right valve is 10 mm. in diameter, with a height of 39 and a length 

 of 47 mm. 



Only one right valve was dredged at the U. S. Fish Commission sta- 

 tion 3389, in 210 fathoms, mud, in the Gulf of Panama. 



Type.— No. 106891, U. S. N. M. 



This is the third orbicular species from West America. 



