FRESHWATER AND LAND SHELLS. 27 



Unio Roanokensis. Plate VIII. fig. 21. 



Testa suboblongd, transversa, incequilaterali, postic^ biangulatd, compressd ; valvulis eras- 

 sis ; natibus prominulis; epidermide terebroso-fuscd ; dentihus cardinalibus parvis ; late- 

 ralibus longissimis subcurvisque ; margarita alba. 



Shell somewhat oblong, transverse, inequilateral, biangular behind, compressed ; 

 valves thick ; beaks somewhat prominent; epidermis dark brown ; cardinal teeth small; 

 lateral teeih long and rather curved ; nacre white. 



Hab. Roanoke River, North Carolina^ 



Altamaha, Geo. Professor Nuttall and Major Leconte. 

 My Cabinet. 

 Cabinet of Major Leconte. 

 Diarn. 1-2, Length 2-2, Breadth 4-7 inches. 



Shell somewhat oblong, transverse, inequilateral, biangular behind, 

 compressed, flattened on the umbonial slope; substance of the shell 

 thick; beaks somewhat prominent; ligament very large and long; 

 epidermis dark brown, apparently without rays; cardinal teeth small 

 and striate ; lateral teeth long, large, and somewhat curved ; anterior 

 cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices on 

 the superior part of the cavity of the beaks; cavity of the shell small; 

 cavity of the beak very small ; nacre white. 



Remarks. — In crossing the Roanoke some years ago, between Nor- 

 folk and Tarborough, I picked up a few specimens of this shell. Since 

 that, Professor Nuttall gave me a single valve from the JiUamaha, and 

 more recently some large specimens have been brought from the same 

 river by Major Leconte. I found at Tarborough several specimens, 

 which I presume to be the young of this species. This shell strongly 

 resembles a gigantic complanatus, and may be considered to belong to 

 that group. The nacre of all the specimens, however, which I have 

 seen is white, and filled with deposite of epidermal matter in a clouded 

 manner. It may perhaps be found sometimes purple. 



