NEW UNIONID.E OF THE UNITED STATES. 71 



Unio Pyiusii. pi. G, fig. 210. 



Testa hvvi, ellipticii, inflatri, postieo obtuso angulata, in.xquilaterali ; valvulis subcrassis ; natibus prominulis, 

 ad apices undulatis ; epiderraide tenebroso-fusca, obsolete radiata ; dcntibus cardinalibus subgrandibus 

 obtuse angulatis, crenulatis ; lateialibus longis, lamellatis curvisque ; margarita vol purpurea vel salmonis 

 colore tiiicta et valdi; iridcscente. 



Shell .sinootli, elliptical, inflated, obtiisel}' angular behind, inequilateral; valves 

 rather thick ; beaks a little prominent, undulate at the tips ; epidermis dark brown, 

 obscurely ra3'ed ; cardinal teeth rather large, obtusely angular and crenulate ; lateral 

 teeth long, lamellar and curved ; nacre purple or salmon color and very iridescent. 

 Proc. Acad. Nat. Sci. 1858, p. 40. 



Hah. — Tennessee River, Tuscumbia, Alabama. B. Pybas. 



My cabinet, and cabinets of B. Pybas and L. B. Thornton, Esq. 

 Diam. -9, Length 1-4, Breadth 22 inches. 



Shell smooth, elliptical, inflated, obtusely angular behind, inequilateral; substance 

 of the shell rather thick ; beaks a little prominent, with a few parallel undulations ; 

 ligament rather long, thick and dark brown ; epidermis dark brown, obscurely rayed, 

 with rather distant marks of growth ; umbonial slope slightly raised and rounded ; poste- 

 rior slope narrow, elliptical, slightly raised, with two slightly impressed lines from the 

 beaks to the margin ; cardinal teeth rather large, obtusely angular and crenulate ; 

 lateral teeth long, lamellar and curved ; anterior cicatrices distinct, rather large and 

 well impressed ; posterior cicatrices confluent, large and moderately imj^ressed ; dorsal 

 cicatrices placed nearly across the centre of the cavity of the beaks ; cavity of the 

 shell rather deep and wide; cavity of the beaks rather shallow and subangular; 

 nacre purple or salmon color and very iridescent. 



Bemarks. — A number of specimens were sent to me by Mr. Pybas, after whom I 

 name it. It is nearly allied to Nashvillensis and Vaniixemii (nobis), but it is more 

 inflated than the latter, and of a ^ider ellipse than the former ; one of the specimens 

 was perfect in the beaks. The undulations are fine, but not so numerous as in 

 Nashvillensis. Usually the nacre is of a fine purple, with a mixture of salmon color, 

 and often with a white basal margin. 



Unio consanguineus. PL 7, fig. 217. 



Testa lievi, valdc o.bliqua, antic<? tumida et truncata, postice compressa et obtus6 angulata; valvulis crassis, 

 anticii paulisper crassioribus ; natibus tumidis, elevatis, incurvis terininalibus<|ue ; epidermide luteo- 

 castanea, obsolete radiata, transversa vittata; dentibas cardinalibus subgrandibus, striatis subcomprcs- 

 sisque ; lateralibus longis, crassis, corrugatis subcurvisque ; margarita argentea et iridescente. 



Shell smooth, very oblique, swollen and truncate before, compressed and obtusely 

 angular behind; valves thick, a little thicker before; beaks swollen, raised, incurved, 

 and terminal ; epidermis yellowish chestnut, obscurely rayed, transversely banded ; 



