312 NEW UNIONIDiE, MELANID^, ETC. 



tical, carinate, with two impressed lines from the beaks to posterior margin; cardinal 

 teeth rather small, conical and crenulate ; lateral teeth rather long and straight ; 

 anterior cicatrices distinct, small and deeply impressed ; posterior cicatrices confluent, 

 rather large and slightly impressed ; dorsal cicatrices placed over the centre of the 

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

 rather deep and angular ; nacre white and iridescent. 



Remm-Tcs. — Four specimens before me, sent from Swamp Creek, Georgia, by Major 

 Downie, are not, perhaps, either of them full-grown. The largest is nearly one and a 

 half inches wide, — a male, which is figured. A single specimen — a female — was 

 brought by Prof. Cope from the head-waters of the Holston. This is two inches wide, 

 and no doubt mature. This species is allied to radians (nobis), and so near to that 

 species that I have doubted until recently whether it was not a variety only. But it 

 differs in being less wide, less yellow in the epidermis, and in having higher beaks. 



TJnio Lincecumii. PI. 49, fig. 125. 



Testa plicata, rotundata, subglobosa, valde insequilaterali ; valvulis percrassis, antice crassioribus ; 

 natibus prominentibus, tumidis, incurvis, ad apices minute undulatis ; epidermide tenebroso-fusca, 

 nigricante, eradiata; dentibus cardinalibus percrassis, solidis, erectis corrugatisque; lateralibus 

 longis, subcrassis et obliquis ; margarita argentea et valde iridescente. 



Shell plicate, rounded, subglobose, very inequilateral ; valves very thick, thicker 

 before; beaks prominent, swollen, incurved, minutely undulate at the tips; epidermis 

 dark brown, blackish, without rays; cardinal teeth very thick, solid, erect and 

 corrugate; lateral teeth rather thick and oblique; nacre silver-white and very 

 iridescent. 



Proc. Acad. Nat. Sci. 1868, p. 144. 



Eah. — Dallas Co., Texas, Prof. Forshey ; Brazos River, Central Texas, Dr. Gideon 

 Lincecum. 



My cabinet and cabinet of Smithsonian Institution. 

 Diam. 1-5, Length 1-9, Breadth 2.4 inch. 



Shell plicate, rounded, subglobose, very inequilateral, rounded before and behind ; 

 substance of the shell very thick, thicker before ; beaks prominent, swollen, incurved, 

 minutely undulate at the tips ; ligament rather short, very thick and chestnut-brown ; 

 epidermis dark brown, blackish, polished towards the beaks, without rays, with 

 rather close marks of growth ; umbonial slope raised and rounded ; posterior slope 

 cordate, slightly raised ; cardinal teeth large, very thick, solid, erect, corrugate and 

 crenulate ; lateral teeth rather thick, slightly curved and oblique; anterior cicatrices 

 distinct, rather small, corrugate and deeply impressed ; posterior cicatrices confluent 

 and very slightly impressed ; dorsal cicatrices placed above the cavity of the beaks ; 



