44 



SYNOPSIS OF 



t— ( 

 < 



H 

 O 



;>^ 



Ph 



;^ 

 o 



OBLONG. 



Alas, truncata.* Say. 



Unio cariosa. (Var. 2.) Lam. 



Unio varicosa. Lam. 



Unio calceolus. 'SV/y. not of Zrea. 



Mya regulosa. Wood. 



rugosa. Lea. 



Alas, rugosa. ^ar. ^«/. Hild. 

 Alas, abducta.t ^SV/y. 





TRIANGULAR. 



deltoidea. 



Zea. 



undulata. Lea. 



Alas, undulata. iS^ay. Bar. 

 Alas, sculptilis, (young.) /SVzy. 

 Mya undulata. Wood. 

 Unio hians. Valen. 

 Unio glabratus.t »S'o^^. 



OVAL. 



Raveneliana. Lea. 

 radiata.ij: Lea. 



* Several specimens of fine marginata have been sent to me from the west, 

 marked .Jllas. trimcata, Say, being one of his unpublished names, but given 

 by him to various conchologists under that name. I have never considered it 

 distinct from the marginata of the eastern rivers, although it is generally 

 larger and of finer colour in the exterior. 



f On the authority of Fcrussac. 



\ This shell, in the teeth, except in the size of them, very closely resem- 

 bles the An. areolatus, Swain, which Mr. Say described as Alas, edentula. 



