NEW FRESH WATER AND LAND SHELLS. 209 



our eastern species, but others again resemble the smooth ones of the West. I 

 have made many attempts to obtain the shells of Ocmulgee river, the most 

 southern of the Atlantic basin, without success. It would be exceedingly desi- 

 rable to compare the species of the two basins, in order to designate the charac- 

 ters of those so nearly placed together in waters of so wide a drainage. 



Unio subangulatus. Plate 13, Fig. 23. 



Testa ellipticd, subinjlatd, postice suhangulata; valvulis tenuihus; natihus subfrominentihus; epider- 

 mide luted, radiatd, politd ; dentibus cardinalibus subgrandibus, erectisque ; lateralibus sublongis subrec- 

 tisque; margaritd salmonis colore tinctd et iridescente. 



Shell elliptical, somewhat inflated, subangulate behind; valves thin; beaks rather prominent; epidermis 

 yellow, rayed, polished; cardinal teeth rather large and erect; lateral teeth rather long and nearly straight; 

 nacre salmon-coloured and iridescent. 



Hab. Chattahoochee River, Columbus, Georgia. Dr. Boykin. 



My Cabinet. 

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



Shell elliptical, somewhat inflated, subangulate behind; substance of the shell 

 thin; beaks rather prominent, slightly undulate at the tip; ligament rather 

 short and thin; epidermis yellow, rayed over the whole disk, polished; cardinal 

 teeth double in both valves, erect, pointed; lateral teeth rather long and nearly 

 straight: anterior cicatrices distinct; posterior cicatrices confluent; dorsal cica- 

 trices placed on the under side of the cardinal tooth; cavity of the shell rather 

 deep; cavity of the beaks small and angular; nacre salmon-coloured and iri- 

 descent. 



Remarks. — In the examination of seven specimens of this species one proved 

 to have a white nacre and another to have obsolete rays. The whole disk is 

 usually covered with rays; the colour of the epidermis is of an ochry yellow. 



Unio pilaris. Plate 14, Fig. 24. 



Testd rotundatd, inflatd; valvulis crassis; natibus elevatis; epidermide striatd, tenebroso fused; den- 

 tibus cardinalibus subgrandibus; lateralibus longulis subrectisque ; margaritd albd. 



Shell rounded, inflated; valves thick; beaks elevated; epidermis striate and dark brown; cardinal teeth 

 rather large; lateral teeth rather long and nearly straight; nacre white. 



