AND DESCRIPTIONS OF NEW SPECIES. 81 



(Nob.). It differs from it, however, in being less ventricose, in having 

 the beaks less elevated, in being usually more transverse, and in having 

 a paler brown colour. In the circulus, the line of division of the brown 

 and yellow is more distinct. In the lens, the brown is sometimes re- 

 placed, over the whole surface, by yellow. 



Unio Anodontoides. Plate VIII. fig. 11. 



Testa, angusto elliptica, transversa, incequilaterali, inflatd; valvulis subcrassis ; 

 natibus prominulis ; dentibus cardinalibus i?i valvulis ambabus duplicibus et valde 

 erect is ; dentibus lateralibus longis, a cardinalibus seiiaratis, subcurvatis ; marga- 

 ritd alba et colore sahnonis parum tinctd. 



Shell narrow-elliptical, transverse, inequilateral, inflated ; valves somevviiat thick; 

 beaks slightly prominent; cardinal teeth double in both valves and very erect; 

 lateral teeth long, slightly curved and separate from the cardinal teeth ; nacre pale 

 salmon and white. 



r Mississippi river, T. W. Robeson. 

 Hab. -< Alabama river. Judge Tait. 

 ^Ohio river, T. H. Taylor. 



My Cabinet. 



Cabinet of the Academy of Natural Sciences of Philadelphia. 



Cabinet of Professor Vanuxem. 



Cabinet of Dr Hildreth, Marietta, Ohio. 



Diam, 1-5, Length 1'9, Breadth 4'1 inches. 



Shell narrow-elliptical, much inflated, sometimes almost cylindrical : 



substance of the shell somewhat thick; beaks slightly prominent, 



placed near the anterior margin ; ligament long, narrow, and nearly 



straight; epidermis yellowish, very smooth, shining, posterior to 



the umbonial slope fuscous, rarely rayed ; cardinal tooth double in 



both valves, compressed, elevated ; lateral teeth lamellar, very long, 



slightly curved and separated from the cardinal teeth by the absence 



of a plate ; anterior cicatrices distinct ; posterior cicatrices confluent ; 



dorsal cicatrices situated across the cavity of the beaks ; cavity of the 



beaks rounded, and not deep ; nacre salmon or white and iridescent. 



Vol. IV.— V 



