NATURAL SCIENCES OP PHILADELPHIA. 161 



vis, snbconicis, silicosis, in utroque valvulo duplicibus ; laterali- 

 bus sublongis, lamellatis subcurvisque ; margarita purpurescente 

 et valde iridescente. 



Hab. Neuse River, N. C. Prof. E. Emmons. 



TJnio dissimilis. 



Testa laavi, sublata, compressa, ad latere planulata, valde 

 insequilaterali, postice obtuse angulari, antice rotunda ; valvulis 

 subtenuibus ; natibus prominulis ; epidermide tenebroso-fusca, 

 micanti, eradiata ; dentibus cardinalibus parviusculis, subcom- 

 pressis, silicosis, in utroque valvulo duplicibus ; lateralibus 

 prcelongis, lamellatis subrectisque ; margarita alba et valde iri- 

 descente. 



Hab. Long Creek, Gaston Co., and Pfeiffer's Pond, Mecklen- 

 berg Co., N". C. C. M. Wheatley. 



TJnio bellulus. 



Testa laevi, oblique, tumida, ad latere parum planulata, valde 

 insequilaterali, postice obtuse angulari, antice oblique rotundata ; 

 valvulis percrassis, antice crassioribus natibus pyramidatis, fere 

 terminalibus ; epidermide luteola, valde radiata; dentibus cardi- 

 nalibus subcrassis, rugosis ; lateralibus curtis, crassis nigosisque; 

 margarita argentea et valde iridescente. 



Hab. Holston River. Dr. Edgar. Tenn. River. Rev. G. White. 

 Mussel Shoals, Tenn. River, Alabama. C. M. Wheatley. 



TJnio basalis. 



Testa lsevi, oblonga, subinflata, ad latere subplanulata, inffiqui- 

 laterali, postice obtuse biangulari, antice rotundata, ad basim 

 recta ; valvulis crassiusculis ; natibus prominulis ; epidermide 

 luteola, radiata; dentibus cardinalibus parviusculis, subcom- 

 pressis, sulcatis ; lateralibus sublongis, lamellatis subcurvisque ; 

 rnargarita vel albida vel purpurascente et iridescente. 



Hab. Carter's Creek, near Columbus, Georgia. G. Hallenbeck. 



