AND OTHER FAMILIES. 209 



Remarks. — This species has, perhaps, most resemblance in its exte- 

 rior to the marginalis (Lamarck), which comes from the great rivers 

 of India. In the interior, however, it differs much. Our shell is of a 

 very dark salmon colour. It is also a thicker shell, and the teeth are 

 much thicker. In the colour of the epidermis it somewhat resembles 

 the lanceolatus (nobis). 



Unio modiolifoumis. Plate XIII. fig. 40. 



Testd ovatd, transversci, inxqidlaterali, injlatu, antice angustd, postice lata ; 

 valvuHs tenuissimis ; natibiis minutis et fere terminalibus ; dentibus cardinalibus 

 parvis, compressis, laieralibus longis curvisque; margarild subpurpured, valde 

 iridescenti. 



Shell ovate, transverse, very inequilateral, inflated, narrow before and broad behind ; 

 valves very thin ; beaks small, nearly terminal ; cardinal teeth small, compressed ; 

 lateral teeth long and curved ; nacre slightly purple, very iridescent. 



Hab. Santee Canal, South Carolina. Professor Ravenel. 



My Cabinet. 



Cabinet of Professor Ravenel. 



Cabinet of P. H. Nicklin. 



Diam. 1-1, Length 1-5, Breadth 2-7 inches. 



Shell reversely ovate, transverse, very inequilateral, inflated, narrow 

 before and broad behind, emarginate at basal margin ; substance of the 

 shell very thin, diaphanous ; beaks small, nearly terminal, slightly un- 

 dulated ; ligament rather long and thin ; epidermis brown, shining ; rays 

 indistinct ; cardinal teeth small, compressed, disposed to be double in 

 the left and single in the right valve ; lateral teeth long, curved and ele- 

 vated in their direction ; anterior cicatrices distinct ; posterior cicatrices 

 confluent; dorsal cicatrices small, situated in the cavity of the beaks; 

 cavity of the shell deep ; cavity of the beaks shallow ; nacre slightly 

 purple, very iridescent. 



Remarks. — The spreading out of the posterior portion of the shell, 

 and the narrowness of the anterior portion, is very striking in this spe- 

 55 



