144 PROCEEDINGS OP THE ACADEMY OP 



shoals and mud-bars of the harbor, and the mud of the marshes, 

 in some places so thickly that no step can be taken without tread- 

 ing them under foot. They may be dredged at all depths ; and 

 bleached shells are heaped in some places. Such numbers, in 

 devouring decaying vegetable substances, must exercise decided 

 influence in the natural economy of the locality. The dead shells 

 of this as well as of tlie species of the next genus afl?ord the most 

 usual accommodations of the smaller Eupaguri. Many specimens 

 may be found with the apex perfect ; but in such cases it is 

 usually lighter colored and more fragile than the rest of the shell, 

 as if already devitalized. 



Nassa vibex, Say. 



Common. 

 Nassa trivittata, Say. 



Common. 

 Nassa T 



Several undetermined specimens; and others marked ^^Nassa 

 vibexV^ 

 CeritMopsis terelsralis, C. B. Ad. 



Dredged, in the channel. 



Acus dislocatus, Say. {Cerithium petitii,^.) 



Yery abundant. The species lives mostl}^ on the shoals and in 

 the shallower dredgings ; dead shells are found everywhere. 



Rapana (Fusus) cinerea, Say. (Buccimmi plicosum, Menke.) 



Common on the beach and dredged in various places. The shells 

 are too numerous to be likely to escape ordinary observation (and 

 the species may have been accidentally omitted from Dr. Stimp- 

 son's list). " I have some doubt about this identification, as there 

 appears to be some difiference in the canal and outer lip; but if not 

 this, I do not know what it is." 



Busycon pyrum, Dillw. (Fulgttr pyruloides, Say.) 



Not common ; two or three specimens only, dead, from the 

 beach. 

 Busycon canaliculatum, Linn. 



Common, but less so than the next. While the many speci- 

 mens examined seemed to me constant in form, the colors are 

 notably variable. Nearly all are white, more or less pure, outside, 

 but the older ones have a rough brownish epidermis ; inside, the 



[July 25, 



