12 



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

 eradiata ; margarita cffiruleo-albii et valde iridescente. 



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



Anodonta Tryonii. — Testa, lam, obliquo-elliptica, subcompressa, sublenticu- 

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

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

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

 et valde iridescente. 



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

 and, G. W. Tryon, jr. Flemington, Con., Prof. Shepard. WestEeld, Mass., 

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



Descriptions of two new species of EXOTIC UNIONES and one 

 MONOCONDYLCEA. 



BY ISAAC LEA. 

 [Read April 22d, 1862.] 



Unio Paramattensib. — Testa crebre et leviter sulcata, elliptica, subinflata. 

 valde inaequilaterali, postice obtuse angulata, antice rotundata ; valvulis cras- 

 siusculis, antice paulisper crassioribus ; natibus prominulis, ad apices radiis 

 undulatis; epidermide tenebroso-fusca, nigricante, eradiata; dentibus cardi- 

 nalibus parvis, valde compressis, obliquis, valvulse dextras duplicibus ; late- 

 ralibus praslongis, lamellatis subrectisque ; margarita alba et valde iridescente. 



Hab. — Paramatta River, New South Wales, Smithsonian Institution. 



Unio PAzri.— Testa lavi, obliqua, antice inflata, valde inaequilaterali, postice 

 acuto-angulata et attenuate, antice rotundata ; valvulis crassiusculis, postice 

 paulisper crassioribus ; natibus tumidis, subterminalibus ; epidermide olivacei, 

 obsolete radiata et transverse late vittata; dentibus cardinalibus longis, 

 lamellatis, valde obliquis corrugatisque ; lateralibus praelongis, obliquis, 

 lamellatis corrugatisque; margarita vel alba vel casrulea et valde iridescente. 



Hab. — China. Sig. Patricio Maria Paz. 



Monocondlo3A Wheatleyi. — Testa laevi, oblonga, subcompressa, valde in- 

 aequilaterali, antice oblique rotundata, postice truncata ; valvulis subcrassis. 

 antice paulisper crassioribus ; natibus parvis, acuminatis, ad apices minutis- 

 sime undulatis ; epidermide lutea, nitida, eradiata ; dentibus cardinalibus 

 parvis, erectis, in utroque valvulo uno-tuberculatis ; margarita alba et valde 

 iridescente. 



Hab. — River Tigris, Assyria, Rev. Mr. Beadle, by C. M. Wheatley. 



