CHIEFLY OF THE UNITED STATES. 317 



feet specimens, leaves no doubt of the identity of the species. It belongs to the same 

 group with negatus and Estabroolcii (nobis), but cannot be mistaken for either. It is 

 not so stout nor so triangular as negatus, nor is it as triangular as Estahroohii, or as 

 much sulcate. The furrows are very small, and in the worn specimens are not very 

 observable. The posterior portion of the nacre of two specimens is of that peculiar 

 golden color — satin-like — which some of the Uniones exhibit. The rays are on the 

 flattened sides before the umbonial slope, and are maculate, being interrupted by the 

 marks of growth. 



&' 



Unio eefulgens. pi. 51, fig. 130. 



Testa nodulosa, rotandata, lenticulari, insequilaterali ; valvulis subcrassis, antice crassioribus ; natibus 

 prominulis ; epidermide rufo-castanea, aliquanto polita; dentibus cardinalibus subgrandibus, 

 eleganter corrugatis crenulatisque ; lateralibus longiusculis, obliquis, minute corrugatis ; margarita 

 albida, ad marginem purpurescente et elegantissime iridescente. 



Shell nodulous, rounded, lenticular, inequilateral ; valves somewhat thick, thicker 

 before; beaks slightly prominent; epidermis reddish-chestnut color, somewhat 

 polished ; cardinal teeth rather large, beautifully corrugate and crenulate ; lateral 

 teeth rather long, oblique and minutely corrugate ; nacre whitish, purplish at the 

 margin and beautifully iridescent. 



Proc. Acad. Nat. Sci. 1868, p. 145. 



Eah. — Oktibbeha River, Lauderdale Co., Mississippi, W. Spillman, M.D. 



My cabinet and cabinets of Academy of Natural Sciences and Dr. Spillman. 

 Diam. 1, Length 1-6, Breadth 1-9 inch. 



Shell nodulous, rounded, lenticular, inequilateral, disposed to be very obtusely 

 angular at the posterior basal margin ; substance of the shell somewhat thick, thicker 

 before ; beaks a little prominent ; ligament rather short and light brown ; epidermis 

 reddish chestnut-brown, somewhat polished, with rather distant marks of growth, 

 with two indistinct rays on the posterior slope on each valve ; umbonial slope 

 slightly raised into an obtuse angle ; posterior slope raised almost to a wing, and 

 furnished with a few nodules ; cardinal teeth rather large, double in the left and 

 treble in the right valve, beautifully corrugate and crenulate; lateral teeth somewhat 

 thick and long, oblique, minutely and beautifully corrugate; anterior cicatrices dis- 

 tinct and well impressed ; posterior cicatrices confluent and large ; dorsal cicatrices 

 placed on the plate above the cavity of the beaks ; cavity of the shell rather 

 shallow ; cavity of the beaks deep and angular ; nacre pearly-white in the cavity, 

 beautifully purple towards the margin and refulgently iridescent. 



Remarks. — Among a number of Unionido} sent to me from the State of Mississippi 

 by Dr. Spillman were three specimens of this species, which I have not heretofore 

 seen. It has some resemblance to verrucosus, Bar., from Tennessee, in outline, but 



