DESCRIPTION OF FIFTY-TWO SPECIES OF TJNIONID^. 51 



rupted rays nearly cover the whole disk. This species is nearly allied to mundus 

 and Lawii (nobis), but is not so oblique as either. None of the specimens had the 

 beaks perfect enough to present the character of the tips. 



Unio infuscus. pi. 17, fig. 49. 



Testa Isevi, elliptica, siibinflata, insequilaterali, postice obtuse biangulari, antice rotundata ; valvulis 

 crassiS; antice crassioribus; natibus prominulis, ad apices parum undulatis; epidermide tenebroso- 

 fusca, submicanti, obsolete radiata ; (fentibus cardinaiibus subcrassis, compressis corrugatisque ; 

 lateralibns longis, lamellatis, rugosis subcurvisque ; margarita vel salmonia vel purpurascente et 

 valde iridescente. 



Shell smooth, elliptical, somewhat inflated, inequilateral, obtusely biangular 

 behind, rounded before ; valves thick, thicker before ; beaks somewhat prominent, 

 slightly undulate at the tips ; epidermis dark brown, somewhat shining, obscurely 

 radiate ; cardinal teeth somewhat thick, compressed and corrugate ; lateral teeth 

 long, lamellar, rugose and somewhat curved ; nacre salmon colored or purple and 

 very iridescent. 



Proc. Acad. Nat. Sci., 1872, p. 160. 



B:ah. — Fox River and Irwin's Creek, North Carolina, C. M. Wheatley. 



My cabinet and cabinet of Mr. Wheatley. 

 Diam. -9, Length, I'O, Breadth 2-8 inches. 



Shell smooth, elliptical, somewhat inflated, inequilateral, obtusely biangular 

 behind, rounded before ; substance of the shell thick, thicker before ; beaks some- 

 what prominent, slightly undulate at the tips; ligament rather large and dark 

 brown; epidermis dark brown, somewhat shining, obscurely radiate, with very dis- 

 tant marks of growth ; umbonial slope obtusely angular; posterior slope narrow^ 

 elliptical, carinate, with two indistinct impressed lines from beaks to margin ; car- 

 dinal teeth somewhat thick, compressed and corrugate; lateral teeth long, lamellar, 

 rugose and somewhat curved; anterior cicatrices distinct, large and well impressed; 

 posterior cicatrices distinct, large and slightly impressed ; dorsal cicatrices placed 

 above the centre of the cavity of the beaks ; cavity of the shell rather shallow and 

 wide ; cavity of the beaks shallow and rounded ; nacre salmon colored or purple 

 and very iridescent. 



Remarks. — Many specimens of various ages were received from Mr. Wheatley. 

 The younger showed small undulations at the tips. The nacre generally salmon 

 color, some of them quite brilliant ; some were purplish, none white. The rays on 

 the more perfect specimens are capillary ; on the old specimens they are obsolete. 

 This species is nearly allied to ligatus herein described, but it is more transverse, 

 with more distant bands and is higher on the umbonial slope. 



