38 



the month of March. So accurately does the above 

 mentioned variety agree with Lister's figure and de- 

 scription, that I cannot doubt the identity. The 

 species is, perhaps, most closely allied to U. cariosus, 

 its common associate in the Delaware and Schuylkill. 

 The specimen figured has a double cardinal tooth in 

 each valve. 



UNIO xNASUTUS. 



Plate XVIII.— Fig. 1. 



DESCRIPTION. 



Shell elongated, compressed, thin; disks slightly 

 flattened; anterior side short; posterior side rostrated, 

 tapering, angular at the extremity; umbo not promi- 

 nent; beaks small, eroded; umbonial slope profoundly 

 oblique, angulated; ligament margin rectilinear, ele- 

 vated; posterior superior margin profoundly oblique 

 and slightly concave; within bluish, iridescent, rarely 

 purple or salmon; cardinal teeth compressed and 

 oblique, double in each valve. 



SYNONYMES. 



U. nasutus, Say. Nich. Enc. (Amer. ed.) art. Conch, pi. iv. 

 fig.. I. 



U. ROSTRATA, ValetlC. 



Lister, tab. 151. fig. 6. 

 Cab. A. N. S.No. 1123. 



OBSERVATIONS. 



A common species in the tide waters from Florida 



