26 DESCRIPTION OF NEW 



Unio simus. Plate VIII. fig. 20. 



Testa ovata, transversa, compressa, inosquilaterali, postice subangulata ; valvulis subcras- 

 sis; natibus prominulis ; epidermide luteola, radiatd ; dentibus cardinalibus parvis ; laterali- 

 bus longis crassisque; margarita alba et iridcscente. 



Shell ovate, transverse, compressed, inequilateral, subangular behind ; valves some- 

 what thick; beaks somewhat prominent ; epidermis somewhat yellow, radiated ; cardi- 

 nal teeih small ; lateral teeth long and thick ; nacre white and iridescent. 



Hab. Cumberland River, Ten. Professor Troost. 



My Cabinet. 

 Cabinet of Professor Troost. 

 Diam. -6, Length 1, Breadth 1.7 inches. 



Shell ovate, transverse, inequilateral, compressed, subangular be- 

 hind ; substance of the shell somewhat thick, thinner behind ; beaks 

 ■ somewhat prominent; ligament rather short; epidermis somewhat 

 yellow, indistinctly rayed ; cardinal teeth small, double in the left and 

 single in the right valve ; lateral teeth long, thickened towards the pos- 

 terior end ; anterior cicatrices distinct ; posterior cicatrices confluent ; 

 dorsal cicatrices placed in the centre of the cavity of the beaks ; cavity 

 of the shell shallow; cavity of the beaks angular; nacre white and 

 iridescent behind. 



Remarhs. — This shell was procured by Professor Troost from the 

 Cumberland River, but whether near Nashville or not, I am not in- 

 formed. It resembles the Cumherlanilicus (nobis), but is a thicker 

 and heavier shell. 



