NATURAL SCIENCES OP PHILADELPHIA. 169 



Unio Mercerii Testa lsevi, late elliptica, compressa, postice compressa et 

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

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

 dinalibus parvis, tuberculatis striatisque ; lateralibus prselongis subcurvisque ; 

 margarita purpurea et valde iridescente. 



Hab. Lee Co., Geo., Dr. Mercer. 



* 



Unio Arkansasensis. Testa laevi, ovato-obliqua, insequilaterali, postice com- 

 pressa et obtuse biangulata, antice rotunda; valvulis crassiusculis, antice 

 paulisper crassioribus ; natibus subelevatis; epidermide flavescente, obsolete 

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

 longis, subrectis subcrassisque ; margarita alba et valde iridescente. 



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



Unio Be ale i. Testa laevi, elliptica, subcompressa, insequilaterali, 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, lamellatis ; 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, inflata, insequilaterali, postice 

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

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

 sis ; epidermide fulgida, 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. 



Anodonta Williamsii. Testa, lsevi, ovato-oblonga, inflata, subsequilaterali, 

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

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

 undulatis ; epidermide vel viridi vel luteo-oliva, fulgida, obsolete radiata vel 

 eradiata ; margarita caeruleo-alba et valde iridescente. 



Hab. Potomac River, at the White House below Mt. Vernon, H. C. Williams. 



Anodonta Tryonii. Testa, lsevi, obliquo-elliptica, subcompressa, sublenticu- 

 lar!, valde insequilaterali, postice subbiangulari, antice rotundata ; valvulis 

 tenuibus; natibus prominulis, subcompressis, ad apices undulatis, epidermide 

 fulgida, vel virente vel fuscescente, obsolete radiata; margarita caeruleo-alba, 

 et valde iridescente. 



Hab. Schuylkill River, above Philadelphia, Delaware River, at League Isl- 

 and, G. W. Tr'you, jr. Flemington, Con., Prof. Shepard. Westfield, Mass., 

 Dr. Shurtleff; and Potomac near Chain Bridge, above Washington, Prof. Henry. 



Description of a New Genus, (TRYPANOSTOMA) of the Family MELANID.E, 



and of forty-five New Species. 



BY ISAAC LEA. 



Family MELANIDJE. 



Genus Trypanostoma.'* Testa conica, apertura rhomboidea, inferne sub- 

 canaliculata. Labro expanso. Columella lsevis, inferne contorta. Operculum 

 corneum, ad spirans pertinens. 



The enormous number of species in the genus dfelama, has made it very de- 

 sirable to eliminate as many as possible, by founding new genera, when well- 

 characterised groups can be established. With this view, I proposed, in the 



* Tgt/Tavev, an auger, and ari/ma, a mouth. 

 1862.] 12 



