NEW UNIONIDiE OF THE UNITED STATES. G7 



Unio Pybasii. PI. 6, fig. 210. 



Testa Irevi, elliptica, inflata, postice obtuse angulata, inrcquilaterali ; valvulis subcrassis; natibus prominulis 

 ad apices undulatis; epidermide tenebroso-fuscfi, obsolete radiata; dentibus cardinalibus subgrandibus 

 obtuse angulatis, crenulatis; lateralibus longis, lamellatis curvisque; margarita vel purpurea vel salrnonis 

 colore tin eta et valde iridescente. 



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

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

 obscurely rayed ; 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. 



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



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

 Biam. -9, Length 1-4, Breadth 2-2 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 impressed ; 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. 



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

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

 inflated than the latter, and of a wider 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. 



*& j 



Unio consanguineus. PL 7, fig. 217. 



Testa laevi, valde obliqua, antice tumida et truncata, postice compressa et obtuse angulata; valvulis orassis, 

 antice paulisper crassioribus ; natibus tumidis, elevatis, incurvis terininalibusque ; epidenuide luteo- 

 castanea, obsolete radiata, transverse vittata ; dentibus cardinalibus subgrandibus, striatis subcompres- 

 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 ; 



