FRESHWATER AND LAND SHELLS. 35 



Unio gibber. Plate X. fig. 30. 



Testa triangulata, compressh, inoRquilaterali, postich subbiangulata ; valvulis subcrassis; 

 natibus prominulis ; epidermide tenebroso-fuscd ; dentibus cardinalibus parvis ; lateralibus 

 dedivibus; margaritct salmonis colore tinctd. 



Shell triangular, compressed, inequilateral, behind subbiangular; valves rather thick ; 

 beaks somewhat prominent; epidermis dark brown ; cardinal teeth small; lateral teeth 

 inclined ; nacre salmon colour. 



Hab. Carryfork River, Ten. Professor Troost. 



My Cabinet. 



Cabinet of Professor Troost. 



Diam. '7, Length 1, Breadth 1"8 inches. 



Shell triangular, compressed, inequilateral, behind somewhat bian- 

 gular, elevated on the dorsal margin ; substance of the shell rather thick, 

 thinner behind ; beaks somewhat prominent ; ligament short ; epider- 

 mis dark brown, apparently without rays ; cardinal teeth small and 

 deeply cleft in the left valve ; lateral teeth inclining towards the pos- 

 terior angle; anterior cicatrices nearly distinct; posterior cicatrices 

 distinct; dorsal cicatrices in the centre of the cavity of the beaks; ca- 

 vity of the shell very shallow; cavity of the beaks angular; nacre 

 salmon colour and iridescent behind. 



Remarks. — Among the numerous interesting species sent to me by 

 Professor Troost, is this species from Carry fork river. In its general 

 character it approaches the U. crassidens (Lam.), (cuneatus, Bar.). It 

 is, however, a very much smaller shell and more triangular. All the 

 specimens submitted to me (five) were of a fine salmon colour. It 

 may, however, be found to vary, like the crassidens and complanatus. 



