DESCRIPTION OF FIFTY-TWO SPECIES OF UNIONID^. 53 



Shell smooth, quadrate, somewhat compressed, slightly flattened at the sides, 

 very inequilateral, obtusely angular behind, rounded before ; valves somewhat 

 thick, thicker before ; beaks somewhat prominent ; epidermis dark olive, without 

 rays ; cardinal teeth small, subcorneal, sulcate and double in both valves ; lateral 

 teeth rather long and somewhat curved ; nacre purplish and very iridescent. 

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



Hah. — Neuse Eiver, North Carolina, Prof. E. Emmons. 



My cabinet. 

 Diam. -8, Length 1-2, Breadth 22 inches. 



Shell smooth, quadrate, somewhat compressed, slightly flattened at the sides, 

 very inequilateral, obtusely angular behind and rounded before ; substance of the 

 shell somewhat thick, slightly thicker before; beaks somewhat prominent; ligament 

 rather thin and dark brown ; epidermis dark olive, without rays and with distant 

 marks of growth ; umbonial slope obtusely angular ; posterior slope subcarinate 

 and narrow elliptical ; cardinal teeth small, subconical, sulcate and double in both 

 valves ; lateral teeth rather long, lamellate and somewhat curved ; anterior cica- 

 trices distinct, well impressed and corrugate; lateral cicatrices confluent, large, 

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

 cavity of the shell not deep ; cavity of the beaks scarcely perceptible ; nacre pur- 

 plish and very iridescent. 



Remarks. — A single specimen was received a long time since from Dr. Emmons. 

 The description has been deferred with the hope of other and better specimens 

 being found. The beaks being eroded, the character of the tips cannot be observed. 

 In outline it is near to hebes (nobis), but it is not so high on the carina. It reminds 

 one of suhgibhosus (nobis). 



Unio dissimilis. pi. 18, fig. 52. 



Testa Isevi, sublata, corapressa, ad latere planulata, valde insequilaterali, postiee obtuse angulari, antice 

 rotunda; valvulls subtenuibus; natibus prorninulis; epidermide tenebroso-fusca, rnicanti, eradlata; 

 dentibus cardinalibus parviusculis, subcompressis, sulcosis, in utroque valvule duplicibus; lateral- 

 ibus prselongis, lamellatis subrectisque ; margarita alba et valde irideseente. 



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

 obtusely angular behind, round before ; valves rather thin ; beaks slightly promi- 

 nent ; epidermis dark brown, shining, without rays ; cardinal teeth rather small, 

 someAvhat compressed, sulcose, double in both valves ; lateral teeth very long, 

 lamellar and nearly straight ; nacre white and very iridescent. 

 Proc. Acad. Nat. Sci., 1872, p. 161. 



14 



