NEW UNIONID^E OF THE UNITED STATES. 57 



undulate at the tips ; ligament long, thick and dark brown; epidermis dark brown, 

 raved, shining above and striate below; umbonial slope somewhat raised and obtusely 

 angular; posterior slope long, narrow and very slightly raised; cardinal teeth rather 

 large, compressed, crenulate and double in both valves; lateral teeth very long, lamel- 

 lar, straight and enlarged towards the posterior end ; anterior cicatrices distinct, 

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

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

 of the shell shallow and wide; cavity of the beaks very shallow, scarcely observable; 

 nacre white and iridescent. 



Remarks. — This is a fine species, belonging to the group of which nasutus, Say, is 

 the type. It is closely allied to Fisher ianus, (nobis}, but differs in being larger, 

 stouter, and a more expanded shell. The young and more perfect specimens have 

 rays, which are obsolete in the old and more imperfect specimens. There are three or 

 four undulations of the tips which are coarser than in nasutus. It is with great pleasure I 

 dedicate this fine species to Prof. E. Emmons, to whose kindness I am indebted for so 

 many interesting new species, collected in various parts of North Carolina, during his 

 important geological survey of that State. 



Unio Genthii. PI. 2, fig. 204. 



Testa teevi, obliqua, inflata, inaequilaterali, postice obtuse angulata; valvulis subcrassis, antice crassioribus ; 

 natibus prominentibus; epidermide tenebroso-fusca, polita obsolete radiata ; dentibus eardinalibus sub- 

 grandibus, obtuse conicis crenulatisquej lateralibus crassis, curiis rectisque; margarita alba ct iridescente. 



Shell smooth, oblique, inflated, inequilateral, obtusely angular behind ; valves some- 

 what thick, thicker before; beaks prominent; epidermis dark brown, polished, ob- 

 scurely rayed ; cardinal teeth rather large, obtusely conical and crenulate ; lateral 

 teeth thick, short and straight; nacre white and iridescent. 

 Proc. Acad. Nat. Sci. 1857, p. 85. 



Hub. — Catawba River, Gaston Co., N. C. ; Dr. Genth and C. M. Wheatley. Deep 

 River, Gulf, N. C. Prof. Emmons. 



My cabinet, and cabinets of Dr. Genth, Mr. Wheatley and Prof. Emmons. 

 Diam. -7, Length 1, Breadth 10 inch. 



Shell smooth, oblique, inflated, inequilateral, obtusely angular behind and rounded 



before; substance of the shell somewhat thick, thicker before; ligament short, thick 



and light brown; epidermis dark brown, polished on the sides towards the beaks and 



striate below; umbonial slope raised, obtusely angular; posterior slope wide and dark 



brown; cardinal teeth rather large, compressed, obtusely conical, crenulate and double 



in both valves ; lateral teeth thick, short and straight; anterior cicatrices distinct, 



rather large and well impressed; posterior cicatrices continent, rather small and 



slightly impressed; dorsal cicatrices placed near the centre of the cavity of the beaks 



15 



