12 NEW UNIONID^, MELANIDiE, ETC., 



and double in both valves ; lateral teeth very long, lamellar and slightly curved ; 

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

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

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

 shallow and rounded ; nacre white or purple and very iridescent. 



Remarlis. — I have before me six specimens, of different ages. The oldest has some 

 of the epidermis gone and the beaks much eroded. None have the beaks perfect 

 enough to make out the undulations of the tips. There is enough, however, to see 

 that the undulations are not very fine. This species belongs to the complanatus 

 group, and resembles Mecklenbergensis, herein described ; but it is not so thick a shell, 

 is not so high on the umbonial slope and differs in the cardinal teeth. 



Unio nasutulus. pi. 3, fig. 9. 



Testa IfBvi, valde transversa, eompressa, ad latere planulata, valde infequilaterali, postioe acute acuminata, 

 antice oblique rotundata ; valvulis subtenuibus ; natibus prominulis, fere terminalibus ; epidermide 

 • tenebroso-fusca, radiata; dentibus oardinalibus parvissimis, acuminatis, in utroque valvulo duplicibus ; 

 lateralibus prjelongis, tenuibus rectisque ; margarita subsalmonea et valde iridescente. 



Shell smooth, very wide, compressed, flattened at the sides, very inequilateral, 

 acutely pointed behind, obliquely rounded before; valves somewhat thin; beaks a 

 little prominent, nearly terminal ; epidermis dark brown, radiate ; lateral teeth very 

 long, thin and straight ; nacre somewhat salmon colored and very iridescent. 

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



JJab. — Livingston's Creek, Brunswick County, North Carolina, E. Emmons, M. D. 



My cabinet and cabinet of Dr. Emmons. 

 Diam. -40, Length -60, Breadth 1-70 inches. 



Shell smooth, very transverse, compressed, flattened at the side, very inequilateral, 

 acutely pointed behind and obliquely rounded before ; substance of the shell rather 

 thin ; beaks slightly prominent, nearly terminal ; epidermis dark brown, somewhat 

 shining, rayed, with distant marks of growth; ligament very small, thin and dark 

 brown ; umbonial slope slightly raised and subangular ; posterior slope very narrow, 

 dark, covered with rays and somewhat carinate ; cardinal teeth very small, acumi- 

 nate and double in both valves ; lateral teeth very long, thin and straight ; anterior 

 cicatrices distinct, rather small and well impressed; posterior cicatrices confluent, 

 rather small and slightly impressed ; dorsal cicatrices very small and placed behind 

 the centre of the cavity of the beaks; cavity of the shell very shallow and wide; 

 cavity of the beaks very shallow, scarcely observable ; nacre somewhat salmon and 

 very iridescent. 



Bemarks. — This is evidently a very small species. There are three specimens be- 

 fore me, all very nearly of the same size. It is most nearly allied to Flslieriaims, 



