seem to justify its separation from Solen. Like the spe- 

 cies of that genus, these reside in the sand on the sea shores, 

 secluded from observation. 



SOLECURTUS COSTATUS. 



SPECIFIC CHARACTER. 



Hinge nearly equidistant from the posterior termination 

 of the shell and the middle of the hinge margin. 



SYNONYM. 



Solen co status. Nobis. Joum. Jlcad. Nat. Sc. vol, 

 ii. p. 315. 



DESCRrPTION* 



Shell transversely elongate-oval, concentrically wrink^ 

 led, very much compressed, very thin and fragile : hinge 

 nearly equidistant from the posterior termination of the 

 shell and the middle of the hinge margin : teeth three, tw^, 

 and sometimes none, in each valve, the posterior ones up- 

 right, the anterior one inclining forward : within a strong, 

 broad, elevated rib passes almost perpendicularly from the 

 hinge towards the base and becomes obsolete near that 

 part : colour pale brownish, with a slight violaceous tinge 

 and two or three obsolete, paler rays ; within perlaoeous, 

 somewhat sericeous. 



PLATE XVIII. 



