52 DESCRIPTION OF FIFTY-TWO SPECIES OF UNIONID^. 



Unio oblongus. pi. 1 8, fig. 50. 



Testa Iffivi, oblonga, compressa, ad latere planulata, valde insequilaterali ; postice obtuse biangulari, 

 antice rotundata ; valvulis parum crassioribus; natibus prominulis ; epidermide luteola, micanti, 

 radiata vel eradiata ; dentibus cardinalibus parvis, lobatis, corrugatis, in utroque valvule duplici- 

 bus ; lateralibus prselongis subrectisque ; margarita alba vel purpurascenti vel salmonis colore 

 tincta et iridescente. 



Shell smooth, oblong, compressed, flattened at the sides, very inequilateral; 

 obtusely biangular behind, rounded before ; valves somewhat thick ; beaks a little 

 prominent; epidermis yellowish, shining, radiated or without rays; cardinal teeth 

 small, lobed, corrugate, double in both valves; lateral teeth very long and straight; 

 nacre white, purple or salmon color and iridescent. 

 Proc. Acad. Nat. Sci., 1812, p. 158. 

 Hah.— Irwin's Creek, North Carolina, C. M. Wheatley. 

 My cabinet and cabinet of C. M. Wheatley. 

 piam. -9, Length 1-4, Breadth 3 inches. 



Shell smooth, oblong, compressed, flattened at the sides, very inequilateral; 

 obtusely biangular behind, rounded before; substance of the shell somewhat thick; 

 beaks a little prominent ; ligament long, somewhat thick and brown ; epidermis 

 yellowish, radiated or without rays and with distant marks of growth ; urabonial 

 slope rounded; posterior slope carinate; cardinal teeth small, lobed, double in both 

 valves ; lateral teeth very long and straight ; anterior cicatrices distinct, large and 

 well impressed ; posterior cicatrices distinct, large and moderately impressed ; 

 dorsal cicatrices placed over the centre of the cavity of the beaks ; cavity of the 

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

 purple or salmon color and iridescent. 



Remarks. — I have several specimens of this species, but none perfect enough 

 in the beaks to give the character of the tips. Some have a few rays ; generally 

 they were without rays, the prevailing character of the epidermis being yellowish. 

 All the specimens but two had white nacre: one was purple and one salmon 

 colored. This species is nearly allied to Raensis and aberrans (nobis), also to 

 suhjMrallelus herein described. 



Unio ratus. PI 18, fig. 51. 



Testa Isevi, quadrata, subcompressa, ad latere subplanulata; valde insequilaterali, postice obtuse angu- 

 lata, antice rotunda; valvulis subcrassis, antice crassioribus; natibus prominulis; epidermide 

 tenebroso-olivacea, eradiata; dentibus cardinalibus parvis, subconicis, sulcosis, in utroque valvulo 

 duplicibus; lateralibus sublongis, lamellatis subcurvisque ; margarita purpurascente et valde 

 iridescente. 



