92 NEW UNIONID/Ti OF THE 



Unio aquilus. pi. 20, lig. 72. 



Testil Irevi, transversii, subcompressa, posticfe angulata, valde inajquilaterali ; valvulis crassiusculis ; natibus 

 prominulis, ad apices rugoso-undulatis ; epidermide tenebroso-fasca, nigricante, obsolete radiata, trans- 

 verse striata ; dentibus cardinalibus parviusculis, subelevatis crenulatisque ; lateralibus prjelongis, 

 lamellatis subrectisque ; margarita vel purpurea vel albil et -valde iridescente. 

 Shell smooth, transverse, somewhat compressed, angular behind, very inequilateral; 

 valves somewhat thick; beaks slightly prominent, rugosely undulate at the tip; 

 epidermis dark brown, blackish, obscurely rayed, transversely striate ; cardinal teeth 

 rather small, somewhat erect and crenulate ; lateral teeth very long, lamellar and 

 nearly straight ; nacre white or purple and very iridescent. 

 Proc. Acad. Nat. Sci. 1857, p. 172. 

 Hob. — FHnt River, near Macon, Georgia, J. C. Plant ; and Chattahooche River at 

 Roswell, Georgia, N. A. Pratt, Jr. 



My cabinet and cabinets of Mr. Plant and Mr. Pratt. 

 Diam. -7, Length 1-3, Breadth 2-fi inches. 



Shell smooth, transverse, somewhat compressed, very inequilateral, angular behind 

 and regularly rounded before ; substance of the shell somewhat thick, slightly thicker 

 before ; beaks a little prominent, with a number of rather rough, subconcentric undu- 

 lations at the tip ; ligament rather long and thin ; epidermis dark brown, blackish, 

 obscurely rayed, shining on the umbones and transversely striate, with three or four 

 rather distant and broad lines of growth ; umbonial slope slightly elevated into an 

 obtuse angle ; cardinal teeth rather small, somewhat erect, oblique, beautifully striate, 

 single in the right and double in the left valve ; lateral teeth very long, lamellar, 

 nearly straight and enlarged at the posterior end; anterior cicatrices distinct and well 

 impressed ; posterior cicatrices confluent and very slightly impressed ; dorsal cicatrices 

 deeply impressed and placed in the centre of the cavity of the beaks ; cavity of the 

 shell shallow and wide ; cavity of the beaks very shallow and rounded ; nacre white 

 or purple and very iridescent. 



Soft Parts. — Branchial uterus not charged, but ova were found in the ovarium. 

 BrancMo} large, thin, rounded below, inner one much the larger, free nearly the 

 whole length of abdominal sack. Palpi rather long, suboval, thin, united only a 

 short distance on the upper posterior edges. Mantle thin, with a rather broad margin. 

 Branchial openincj rather small, with coarse brown papilloe on the inner edges. Anal 

 opening small, with very small brown papillce on the inner edges. Super-anal opening 

 large, colored on the inner edges, and united for a short distance below. Color of the 

 mass whitish. 



Remarks. — Quite a number of this species of all ages were received from Mr. Plant 

 and Mr. Pratt, with others, in alcohol. In outline and many of its characters it is closely 

 allied to nasutu^, Say, and forms a handsome and well characterized member of the 

 group of which that is the type. It is not so transverse, and the undulations of the 



