386 lutrariinjE. 



Conrad, in his description of Cryptodon, states that the 

 shell has the general aspect and character of Lutraria, but 

 is deeply channelled along the hinge-margin. The animal 

 is furnished with two siphons, bearing at the extremity two 

 corneous valvular appendages which close the orifices of 

 the tubes; it inhabits salt marshes, bare at low water, in 

 the vicinity of Santa Barbara. 



Species of Labiosa. 



anatina, Spengl. papyracea, Lam. 



cyprina, Gray. 



Genus RAETA, Gray. 



Shell cordate, ventricose, thin, slightly produced and 

 rather gaping behind; hinder slope keeled, narrow. Hinge 

 with the cardinal teeth strong; hinder lateral teeth small, 

 distinct; ligament sub-external, marginal, not separated 

 fi'om the cartilage. 



Ex. R. canaliculata, Say, pi. 102, fig. 4, 4, a. 



The species of Ra'eta are thin and plicate, and some- 

 what resemble in appearance the genus Harvella ; they 

 are from the south coast of America and the China seas. 



Species of Ra'eta. 



canaliculata, Say. rostralis, Desk. 



lyrala, Hinds. tenera, Desk. 



papyracea, Ghent. tenuis, Hinds. 



pellicula, Desh. undulata, Gould. 

 pulchella, Adams and Reeve. 



Genus C^CELLA, Gray. 



Shell oblong, sub-equilateral. Hinge with the cardinal 

 tooth of left valve broad, triangular, notched ; lateral teeth 



