[249] 



Art. VI. — New Unionidce, Melanidch, eic, chieflij of the United States. 



By Isaac Lea. 

 Unio Homsensis. pi. 29, fi- 03. 



Testa plicata, suboblonga, inKquilaterali, ad latere planulata, postice angulata ; valvulis crassis, antice 

 crassioribus ; natibus prominulis, ad apices valde corrugatis ; epidermide tenebroso-fusea, micanti ; 

 dentibus cardinalibus crassis, erectis crenulatisque ; lateralibus longis, crassis subrectisque ; mar- 

 garita vel purpurea vel salnionea et iridescente. 



Shell plicate, somewhat oblong, inequilateral, flattened at the sides, angular behind ; 



valves thick, thicker before; beaks rather prominent, much corrugated at the tips; 



epidermis dark brown and shining; cardinal teeth thick, erect and crenulate ; lateral 



teeth long, thick and nearly straight; nacre purple or salmon colored and iridescent. 



Proc. Acad. Nat. Sci. 1864, p. 285. 



Hah. — Lake Homs, (ancient Emesa,) River Orontes, North Syria, C. M. Wheatley. 



My cabinet and cabinet of Mr. Wheatley. • 



Diam. -8, Length 1-4, Breadth 2-5 inches. 



Shell plicate, somewhat oblong, inequilateral, flattened at the sides, angular behind ; 

 substance of the shell thick, thicker before; beaks rather prominent, much corru- 

 gated at the tips; ligament large and long; epidermis dark brown, shining, with six 

 to eight nearly equidistant marks of growth ; umbonial slope rounded ; posterior 

 slope compressed and filled with small folds; cardinal teeth thick, erect and crenu- 

 late, single in the right and double in the left valve ; lateral teeth long, thick and 

 nearly straight ; anterior cicatrices distinct, deeply impressed and corrugate ; posterior 

 cicatrices distinct, large and well impressed; dorsal cicatrices placed on the upper 

 part of the cavity of the beaks; cavity of the shell rather shallow; cavity of the 

 beaks rather deep and angular; nacre purple or salmon colored and iridescent. 



Remarhs. — Two fine specimens and two odd valves were received ; one is beauti- 

 fully perfect and corrugate for some distance from the tips. The epidermis is with- 

 out rays, is smooth and shining, and the marks of growth very regular. The folds 

 on the most perfect specimen are numerous and very regular. This species is so much 

 like some of the very thick U. fluvlatilis, which have been found in the interior of 

 Pennsylvania and some from Virginia, that one might be mistaken for the other, but 



