18 



FOSSIL SPECIES. 



28, P. antiquum Braun Germany. 



exauct. (fideMicliaud.) 



29. P. contortum Prime Pittsfield, Mass. 



Anomalies. 



X. P. variabile Prime Cambridge, Mass. 



A monstrosity, having 

 a suture up the 

 valves as in P. sinu- 

 atura, Bgt. 



Y. P. Recluzianum Bourguignat...Belfast. 



ex auct., a marine shell. 



Z. P. splendidum Parreys ? 



ex auct., a Nucula. 



