OF CONCHOLOGY. 63 



that the species was only a synonym of C. fornicata, and owed 

 its supposed distinctive characters to its habitation ivithin uni- 

 valve mollusca. The specimens now shown are true unguifor- 

 mis, and are growing on the external surface of the Pecten. 



Mr. Tryon exhibited specimens of Mercenaria pj"ceparca^ Say, 

 and remarked that M. Morto7ii, Conrad, and M. fulgurans, 

 Tryon, had both proved to be synonyms of it, the latter being 

 the young shell. 



Mr. Wm. H. Dall was elected a Correspondent, and Mr. 

 Charles Wilson Peale a member of the Section. 



