UNIO.-Pl.ATE XXII. 



tico obtuse rotundato, concmtrice liralu-slrialu, por- 

 tico oblique arcuato-expaiixo, deinde acmiimafo, versus 

 margwem ventralem pecuUttrikr vellicalo ; mtuluio- 

 fnsca. 

 The pincued L'nio. Shell elliptically ovate, anterior 

 side obtusely rounded, concentrically ridge-striated, 

 posterior side obliquely arcuately expanded, then acu- 

 minated, peculiarly pinched towards the ventral mar- 

 'Xm ; burnt-brown. 

 Ihih. Guatemala. 



A new species from Guatemala, of a reddish burnt- 

 brown colour, pinched in a characteristic manner towards 

 the posterior ventral margin. 



Species \U. (Mus. Cuming.) 

 Unio coccineus. I'll, testa subqnadrain-ovutii, irassd, 



latere antlco declivi-rot undnto, poslico truiicato-a>i//u~ 



lata ; olivaceo-fuscd. 

 The scarlet Unio. Shell somewhat squarely ovate. 



thick, anterior side slopingly rounded, posterior 



trnncately angled ; olive-brown. 

 Lea, Traus. Amer. Phil. Soe. 1834. Obs. vol. ii. p. IL'. 



pi. 5. f. 12. 



Uuio catUliis, Conrad. 

 JIab. Ohio Eiver, Nortli America. 



The interior of this species is sometimes white, but 

 generallv of a deep salmon-ved colour. 



