AND DESCRIPTIONS OP NEW SPECIES. 73 



My Cabinet. 

 Cabinet of Prof. Vanuxera. 

 Cabinet of P. H. Nicklin. 

 Cabinet of H. C. Carey. 

 Cabinet of the Academy of Natural Sciences, Philadelphia. 

 Diam. -7, Length -1, Breadth 1-6 inches. 



Shell elliptico-rhomboidal, transverse, somewhat flattened at the 

 sides; posterior slope furnished with slight undulations; substance 

 of the shell thin ; beaks slightly prominent, and furnished with par- 

 allel concentric undulations near the tips; ligament short; epidermis 

 yellow, and yellowish brown; rays green and numerous; cardinal 

 tooth oblique, compressed, and slightly cleft in the left valve — in the 

 right single ; lateral teeth long, slightly curved and enlarged towards 

 the posterior end ; anterior cicatrices distinct ; posterior cicatrices con- 

 fluent; dorsal cicatrices situated under the plate, between the cardi- 

 nal and lateral teeth ; nacre satin like, and beautifully iridescent. 



Remarks. — I obtained several specimens of this shell, on the shores 

 of the Congaree, at Columbia, S. C. It resembles the radiahis (Gme- 

 lin) and complanatm* (Solan.), which species are frequently mistaken 

 for each other, and this may readily be confounded with either of 

 them. It has, like the radiatus, many rays, but differs in being more 

 angulated on the umbonial slope, and in measuring less from the pos- 

 terior dorsal margin to the basal margin. It differs from the com- , 

 planulus in its rays, and in having slight undulations on the posterior 

 slope. It is more diminutive in size than either, not being more in 

 volume than one-fifth of the complanatus from the same locality. 



Unio Oriens. Plate VI. fig. 5. 



Testa longo-ovatd, transversa, inaquilaterali. compressa et radiis pulcherrimis 

 pictd, valvulis tenuibus; 7iatibus subprominulis et retusis ; dentibus cardinalibus 



* For reclamation of this species, see Vol. III. p. 416. 



Vol. IV.— T 



