163 



number. In regard to his own species, he says he is aware of the 

 extreme difficulty of severation, arising from the fact of the existence 

 of the vast number of species now described, and their consequent 

 inosculation ; but that he has endeavoured, by careful examination, to 

 satisfy himself that their characteristics were persistent. 



The following are descriptions of the new species embraced in this 

 paper : — 



Unio compressissimus. Testa, laevi, sub triangular!, vald6 compress^,; val- 

 vulis crassis ; natibus compressis ; epidermide . . . ; dentibus cardinali- 

 bus parvis, crenulatis ; lateralibus magnis, crassis curvisque ; margarita alb4,. 

 Hab. Holston River, Tenn. — President Estabrook. 



Unio pellucidus. Testa, laevi, obovatA, subcompressa, pellucida,; valvulis per- 

 tenuibus; natibus prominulis, ad apices undulatis; epidermide tenebroso- 

 fusca, ; dentibus cardinalibus parvis, compressis erectisque ; lateralibus longis, 

 rectls lamellatisque ; margarita cseruleo-alba et iridescente. Hab. Chatahoo- 

 chee River, Geo. — Major Leconte. 



Unio per Twdosus. Testa pernodosa, rotundata, subcompressd; valvulis cras- 

 sis ; natibus elevatis ; epidermide luteo-fusca, ; dentibus cardinalibus magnis j 

 lateralibus brevibus, crassis subrectisque ; margarita alba. Hab. North Ca- 

 rolina.— B. W. Budd, M.D. 



Unio atrocostatus. Testa, plicata,, subquadrata., inflata ; valvulis crassis ; na- 

 tibus prominentibus ; epidermide nigra, striata,; dentibus cardinalibus mag- 

 nis ; lateralibus sublongis subrectisque ; margarita alba et iridescente. Hab. 

 Claiborne, Ala. — Judge Tail. Tuscaloosa, Ala. — jB. W. Budd, M.D. Alexan- 

 dria, Louis. — Josiah Hale, M.D. 



Unio latecostatus. Testa crebr6 plicata, elliptica, compressa. ; valvulis cras- 

 sis ; natibus prominulis ; epidermide tenebroso-fusca, valde striata ; dentibus 

 cardinalibus magnis ; lateralibus longis subrectisque ; margarita alba et valde 

 iridescente. Hab. Tuscaloosa, Ala. — B. W. Budd, M.D. 



Unio hippopoEus. Testa plicata, elliptica, vald6 inflata ; valvulis subcrassis ; 

 natibus prominulis; epidermide luteo-fusca, striata; dentibus cardinalibus 

 subgrandibus ; lateralibus parvis curvisque ; margarita alba et iridescente. 

 Hab. Lake Erie.— jB. W. Budd, M.D. 



Unio simplex. Testa laevi, elliptica, subinflatA; valvulis subcrassis; natibus 

 subprominentibus ; epidermide lutea ; dentibus cardinalibus parvis ; laterali- 

 bus longis, crassis subrectisque ; margarita alba et iridescente. Hab. Black 

 Warrior River, Ala.— B. W. Budd, M.D. 



Unio unicolor. Testa laevi, subrotunda, subcompressa; valvulis crassis; na- 

 tibus subprominentibus ; epidermide fusca ; dentibus cardinalibus parvis ; la- 

 teralibus longis subrectisque; margarita alba, et iridescente. Hab. Tusca- 

 loosa, Ala— B. W. Budd, M.D. 



Unio flavescens. Testa laevi, elliptica, subinflata; valvulis subtenuibus; nati- 

 bus subprominentibus; epidermide luteo-cornea, striata; dentibus cardinali- 

 bus parvis ; lateralibus sublongis, subrectisque ; margarita aM et iridescente. 

 Hab. Black Warrior River, Ala.— 5. W. Budd, M.D. 



