52 NEW UNIONID.^ OF THE 



(liiial teeth large, thick, double in both valves; lateral teeth very long, lamellar and 

 rather curved; nacre white or salmon color. 

 Proc. Acad. Nat. Sci. 1857, p. 84. 



5-rt6._Abbeville District, South Carolina. J. P. Barratt, M. D. 



My cabinet and cabinet of Dr. Bai'ratt. 

 Diam. -8, Length 1-4, Breadth 2-6 inches. 



Shell smooth, oblong, rather inflated, flattened on the sides, very inequilateral, bi- 

 angular behind, subemarginate ; substance of the shell thick ; beaks a little prominent 

 and minutely wrinkled; ligament rather long and somewhat thick; epidermis brown, 

 sti'iate, with distant rather broad marks of growth and indistinct small green rays ; 

 umbonial slope raised, obtusely angular and somewhat inflated ; posterior slope raised 

 into a carina ; cardinal teeth large, thick, pointed, oblique and double in both valves ; 

 lateral teeth very long, lamellar, rather curved, enlarged towards the end, single in 

 the right and double in the left valve ; anterior cicatrices distinct ; posterior cicatrices 

 confluent ; dorsal cicatrices small and placed immediately over the centre of the cavity 

 of the beak ; palleal cicatrix distinctly impressed ; cavity of the shell shallow ; cavity 

 of the beak very shallow ; nacre white or salmon color. 



RemarJcs. — Many years since, I received from Dr. Barratt a number of this species, 

 but while it seemed to me to be distinct enough from the widely distributed U. com- 

 planatus, it was so closely allied, that I hesitated to separate it. Having received 

 subsequently some good suites of different ages, I am perfectly satisfied that it is dis. 

 tinct. The outline is nearly the same, but the Ahhevillensis is more biangular behind 

 and has usually a higher umbonial slope. The marks of growth are also diflferent, 

 being much wider apart. In the color of the nacre also they differ, the compkinatus 

 being usually purple, though often white and sometimes salmon, while this species is 

 nearly always salmon, and rarely white, but I have never seen a specimen purple. I 

 am not, however, prepared to say that it may never occur purple, as this group of 

 shells is very much inclined to that color. Generally there are no rays observable ; 

 but where they are, they will be found to be linear and closely placed. In the right 

 valve the upper lobe of the cardinal tooth is very small. In the left valve they are 

 nearly of the same size. 



Unio Jamesianus. pi. 6 fig. 3-5. 



Testa Isevi, elliptioa, compressa, vald6 inaequilaterali, postice valde compressa, ad basim emarginata ; valvu- 

 11s suberasBis ; natibus prominulis, ad apices concentraliter undulatis ; epiderruide lutea, polita ; denti- 

 bus cardinalibus compressis, crenulatis ; lateralibus longis, lamellatis valdt* curvisque ; margarita alba, 

 et iridescente. 



Shell smooth, elliptical, compressed, very inequilateral, very much compressed be- 

 hind ; emarginate at base, valves rather thick ; beaks a little prominent, concentri- 



