NATURAL SCIENCES OF PHILADELPHIA. 139 



more so on the shingle at the mouths of the estuaries that make 

 from the marshes into tlie harbor, where tlie best specimens may 

 be found. 

 Siliquaria bidens, Chemn. 



Common, on the beach only, where all the numerous specimens 

 were gathered. 



Solemya velum, Say. 



Not uncommon ; living specimens dredged, and taken on Bird 

 Shoals, a few inches below the surface. 



Mya arenaria, Linn. 



Not common, comparativelj^ ; occasional valves occur anywhere, 

 but the species is not known here as an article of food. 



Corbula contracta, Say. 



Dredged ; a few specimens. 



Myalina subovata, Conr. 



Dredged ; a few specimens. 

 Panopaea americana, Conr. 



Apparently rare; two specimens; one valve (No. 1818), very 

 large, worn, was found on the beach, in winter ; another (2494a), 

 fresher and smaller, was taken the next winter, after one of the 

 storms that threw up numbers of Raeta lineata. 



Gastrochsena, sp. 



Dredged ; one specimen. I do not find the name among Mr. 

 Smith's Mss., and think it was an identification of Mr. Morse's. 



Cochlodesma leanum, Conr. 

 Lyonsia byalina, Conr. 



Dredged, I think (label misplaced). 



Pandora trilineata, Say. 



One specimen (No. 2618) ; beach. 



Pholas costata, Linn. 



Beach, very common. 



Pbolas truncata, Say. 



Beach, frequent. As in the cases of several other species, I 

 found valves quite plentiful at intervals, between which none were 

 seen. 



1871.] 



