NEW EXOTIG UNIONID.E. 393 



Anodonta Forbesiana. PI. 47, fig. 301. 



Testa laevi, suboblonga, ventricosa, insequilaterali ; valvulis, crassiusculis ; natibus elevatis, inflatis ; epi- 

 dermide luteo-fusea, micante, vel eradiata vel obsolete radiata ; margarita albida et valde iridescente. 



Shell smooth, suboblong, ventricose, inequilateral, valves somewhat thick ; be tl ks 

 raised, inflated ; epidermis yellowish-brown, shining, without rays or very obscurely 

 rayed ; nacre whitish and very iridescent. 



Eab. — Uruguay River, South America, Prof. J. Wyman. 



My cabinet and cabinet of C. M. Wheatley. 

 Diam. 2-1, Length 2-6, Breadth 4-5 inches. 



Shell smooth, suboblong, very much inflated, inequilateral, obliquely rounded be- 

 fore and subangular behind ; substance of the shell somewhat thick ; beaks raised, 

 large and inflated ; ligament large, long and dark-brown ; epidermis yellowish-brown, 

 shining, darker before and behind, without rays, or obscurely rayed, and with very 

 distant marks of growth; umbonial slope much inflated and obtusely angular ; pos- 

 terior slope very wide, raised into an obtuse angle and very dark-brown ; anterior 

 cicatrices very large, distinct and well impressed ; posterior cicatrices very large, 

 confluent and slightly impressed ; dorsal cicatrices invisible ; cavity of the shell very 

 wide and very deep ; cavity of the beaks rather deep and rounded ; nacre whitish and 

 very iridescent. 



Remarks. — Several specimens are before me, all of which have been more or less 

 injured on the posterior margin, which has caused a change of outline in that part, 

 and perhaps has made it more inflated. All the specimens are more or less open 

 at the anterior basal margin. Neither of the specimens are perfect enough to show 

 any undulations at the tips. The sinus at the end of the ligament is large and 

 triangular. The nacre of all is more or less spotted with green or reddish epidermal 

 matter. Two of the specimens are inclined to salmon color in the cavity. This 

 species inclines to trapezialis, Lam., on one side, and anserina, Spix, on the other, 

 but trapezialis is more triangular and by no means so quadrate or so ventricose. In 

 outline it is near to Anodonta doliaris (my MSS.), from Stewart's Mill, Union County, 

 N. C. I name this species after R. B. Forbes, Esq., of Boston, whose liberality 

 assisted so much in the development of the natural history of the Uruguay River. 



Anodonta Uruguayensis. PI. 48, fig. 302. 



Testa l;evi, obovatil, ventricosa, valde inasquilaterali ; valvulis subcrassis, antice aliquanto crassioribus; 

 natibus subelevatis, turnidis ; epiderrnide tenebroso-oliva, eradiata ; margarita cceruleo-alba et valde 

 iridescente. 



Shell smooth, obovate, much inflated, very inequilateral ; valves rather thick, 



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