CHIEFLY OF THE UNITED STATES. l.*; 



the right valve, but sometimes disposed to be double in the right valve. Some of the 

 specimens are larger than the one figured, but they are very imperfect. 



Unio indefinitus. PL 4, fig. 12. 



Testa IcBvi, oblonga, inflata, ad latere planulata, valde inaequilaterali, postice biangulata, antice I'otun- 

 data; valvulis subcrassis, antice parum crassioribus ; natibus subprominentibus ; epidermide fusco- 

 nigrioante; dentibus cardinalibus parviusoulis, tuberculatis, striatis; lateralibus loagis, lamellatis 

 subourvisque ; margarita alba, aliquaado purpurea et iridesoente. 



Shell smooth, oblong, inflated, flattened at the sides, very inequilateral, biangu- 

 lar behind, rounded before ; valves somewhat thick, slightly thicker before ; beaks 

 somewhat prominent ; epidermis blackish brown ; cardinal teeth rather small, 

 tuberculate, striate ; lateral teeth lamellar and somewhat curved ; nacre white, 

 sometimes purple and iridescent. 



Proo. Acad. Nat. Sci., 1863, p. 192. 



Hub. — Long Creek, Mecklenberg County, North Carolina, C. M. Wheatley ; and 

 Neuse River, near Raleigh, E. Emmons, M. D. 



My cabinet and cabinets of C. M. Wheatley and Dr. Emmons. 

 Diam. :S, Length 1-9, Breadth 2-4 inches. 



Shell smooth, oblong, inflated, flattened at the sides, very inequilateral, biangular 

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

 before ; beaks somewhat prominent ; ligament rather short, thick and dark brown ; 

 epidermis dark brown, inclining to black, usually without rays, sometimes obscurely 

 rayed, with rather close marks of growth ; umbonial slope swollen and rounded ; 

 posterior slope rather wide and somewhat carinate ; cardinal teeth rather small, 

 tuberculate, striate, double in the left valve and disposed to be so in the right ; 

 lateral teeth long, lamellar and somewhat curved; anterior cicatrices distinct, 

 rather large and well impressed ; posterior cicatrices confluent, large and slightly 

 impressed ; dorsal cicatrices placed immediately above the centre of the cavity of 

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

 deep and angular ; nacre usually white, sometimes purple and iridescent. 



Remarks. — A number of specimens, of different ages, are before me. The old 

 individuals are nearly black, the young are greenish brown. It belongs to the 

 complanatus group, and is allied to quadrilaierus, herein described, but has not so 

 high a carina, is higher on the umbonial slope and rather more inflated. 



Unio perlatus. pi. 4, fig. 13. 



Testa laevi, perlata, valde compressa, ad latere planulata, valde inrequilaterali, valvulis tenuibus, 

 antice parum crassioribus ; natibus prominulis, ad apices undulatis ; epidermide fusco-virente, 

 obsolete radiata ; dentibus cardinalibus parvissimis, tuberculatis, in utroque valvule duplicibus; 

 lateralibus prselongis, acicularis reotisquc ; margarita caeruleo-alba et valde iridesccnte. 



