246 DESCRIPTION OP 



Read October 21s/, 1842. 



Unio Dariensis. Plate 26, Fig. 61. 



Testa oblongd, subinflatd, intBquilaterali, postict perangulata, ad lalerd planulatd ; valvulis subcras- 

 sis; natibus prominulis ; epidermide luteo-fusca; dentibus cardinalibus compressis, lateralibus longissi- 

 mis lamellatisque ; margarild alba. 



Shell oblong, subinflated, inequilateral, angular behind, flattened on the sides; valves somewhat thick; 

 beaks rather prominent; epidermis yellowish brown; cardinal teeth compressed; lateral teeth long and 

 lamellar; nacre white. 



Hab. Near Darien, Georgia. J. H. Couper, Esq. 



My Cabinet, and Cabinet of Mr. Couper. 

 Diam. 1.2, Length 1.8, Breadth 2.3 inches. 



Shell oblong, rather inflated, inequilateral, with an elevated, rather acute 

 angle on the umbonial slope, and flattened on the sides; substance of the shell 

 rather thick, thinner behind; beaks rather prominent and flattened; ligament 

 rather long and somewhat thick; epidermis yellowish brown, and obsoletely 

 rayed; posterior slope elevated into a prominent carina and corrugate; cardinal 

 teeth rather small, compressed; lateral teeth long, lamellar and nearly straight; 

 anterior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices 

 placed under the plate posterior to the cardinal tooth; cavity of the shell deep 

 and angular; cavity of the beaks rather shallow; nacre white. 



Remarks. — This shell is remarkable for its high, acutely angular umbo- 

 nial slope, and its flattened sides. Having but a single specimen before me, 

 and that with eroded beaks, I am unable to say any thing respecting the 

 undulations of the beaks. On the sides near to the basal margin there are four 

 or five indistinct folds, but this may not be found to be permanent with the 

 species. In its acute angle and flattened side it has a strong resemblance to 

 An. angulata, (nobis.) It seems to be more nearly allied to U. CongarcBUS, 

 (nobis,) than to any other Unio. 



