11 



U.nio Gerhakdtii. — Testa subsulcata, elliptica, subcompressa, sublenticulari, 

 inaequilaterali, postice obtuse angulata, antice rotunda ; valvulis crassiusculis, 

 antice paulisper crassioribus ; natibus subelevatis ; epidermide straminea, radiis 

 eapillaribus ; dentibus cardinalibus parviusculis, compressis, in utroque valvule 

 duplicibus; lateralibus sublongis, Iamellatis subcurvisque ; margarita alba et 

 valde iridescente. 



Hab. — Chattanooga, Geo., Alexander Gerhardt. 



Ohio Mercerii. — Testa laevi, late elliptica, compressa, postice compressa et 

 biangulata, antice rotundata, valde inaequilaterali ; valvulis subtenuibus ; nati- 

 bus prominulis ; epidermide tenebroso-fusca, subnitida, eradiata ; dentibus car- 

 dinalibus parvis, tuberculatis striatisque ; lateralibus pralongis subcurvisque ; 

 margarita purpurea et valde iridescente. 



Hab. — Lee Co., Geo., Dr. Mercer. 



Csio Arkaxsasensis. — Testa, laevi, ovato-obliqua, inaequilaterali, postice com- 

 press;! et obtuse biangulata, antice rotunda ; valvulis crassiusculis, antice 

 paulisper crassioribus ; natibus subelevatis ; epidermide flavescente, obsolete 

 radiata; dentibus cardinalibus parvis, striatis crenulatisque ; lateralibus sub- 

 longis, 9ubrectis subcrassisque ; margarita alba, et valde iridescente. 



Hab. — Near Hot Springs, Arkansas, Byrd Powell, M. D. 



Usio Bealei. — Testa laevi, elliptica, subcompressa, inaequilaterali, postice 

 obtuse angulata, antice rotundata ; valvulis crassiusculis, antice crassioribus; 

 natibus prominulis ; epidermide vel tenebroso-fusca vel nigricante, obsolete ra- 

 diata; dentibus cardinalibus parvis, compressis, crenulatis, acuminatis, in utro- 

 que valvulo duplicibus ; lateralibus prselongis, subcurvis, Iamellatis ; margarita 

 vel alba, vel dilute salmonia, et valde iridescente. 



Hab. — Leon County, Texas, Lieut. E. F. Beale, U. S. Navy. Rutersville. 

 Texas, Prof. Forshey. 



Anodonta Leonensis. — Testa lavi, elliptica, inflate, inaequilaterali, postice 

 subbiangulata, antice oblique rotundata et paulisper sulcata ; valvulis tenuibus, 

 antice paulisper crassioribus ; natibus prominentibus, tumidis, ad apices nodo- 

 313 ; epidermide fulgidil, luteo-virente vel fuscescente, vel obsolete radiata vel 

 eradiata ; margarita caeruleo-alba. et valde iridescente. 



Hab. — Leon County, Texas, Lieut. E. F. Beale, U. S. Navy. 



A.vodosta Williamsii. — Testa laevi, ovato-oblonga, inflata. subaequilaterali. 

 postice subbiangulata, antice rotundata et paulisper sulcata; valvulis sub- 

 tenuibus, antice ad marginem incrassatis ; natibus prominulis, inflatis, ad apices 



