JOURNAL 



OP THE 



ACADEMY OF NATUEAL SCIENCES 



OF PHILADELPHIA. 



Art. I. — Neio Unumidoi, Melanidce, etc., cldefly of the United States. 



By Isaac Lea. 



Unio quadrilaterus. PL 1, fig. 1. 



Testa Isevi, oblonga, subinfiata, ad latere planulata, injequilaterali, postice biangulata et truncata ; valvulis 

 crassiusculis ; natibus prominulis, ad apices undulatis ; epidermide tenebroso-fusca, eradiata vel obscure 

 radiata ; dentibus cardinalibus parviusculis, tuberculatis, in utroque valvule duplioibus ; lateralibus 

 sublongis, lamellatis subreetisque ; niargarita albida vel purpurea vel salmonea et valde iridescente. 



Shell smooth, oblong, somewhat inflated, flattened at the sides, inequilateral, bian- 

 gular and truncate behind; valves somewhat thick; beaks a little prominent, undu- 

 late at the tips ; epidermis dark brown, without rays or obscurely rayed ; cardinal teeth 

 rather small, tuberculate, double in both valves ; lateral teeth rather long, lamellar 

 and nearly straight ; nacre whitish, purple or salmon and very iridescent. 

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



Eab. — Abbeville District, South Carolina, Dr. Barratt ; Neuse River, near Raleigh, 

 Dr. Emmons ; and Catawba River, North Carolina, C. M. Wheatley. 



My cabinet and cabinets of Dr. Emmons and Mr. Wheatley. 

 Diam. '7, Length 1-4, Breadth 2-3 inches. 



Shell smooth, oblong, somewhat inflated, flattened at the side, inequilateral, bian- 

 gular and truncate behind ; substance of the shell rather thick ; beaks slightly promi- 

 nent, undulate at the tips ; ligament rather small and dark brown ; epidermis dark 

 bi'own, without rays or obscurely rayed, with distant marks of growth ; umbonial slope 

 raised and obtusely angular ; posterior slope rather narrow, raised into a carina ; car- 



