CHIEFLY OF THE UNITED STATES. 9 



Shell smooth, elliptical, somewhat compressed, inequilateral, a little flattened on 

 the sides ; valves rather thin, thicker before ; beaks scarcely prominent ; epidermis 

 dark brown, without rays ; cardinal teeth very small, compressed, very oblique ; lateral 

 teeth rather small, lamellar and pointed; nacre whitish and iridescent. 

 Proo. Acad. Nat. Sci., 186-3, p. 191. 



Hah. — Near Charlotte, Mecklenberg Co., North Carolina, E. Emmons, M. D. 



My cabinet. 

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



Shell smooth, regularly elliptical, rather compressed, inequilateral, slightly flattened 

 at the sides, obtusely biangular behind and rounded before ; substance of the shell 

 somewhat thin, thicker before ; beaks very slightly prominent ; ligament rather small, 

 light brown ; epidermis very dark brown, without rays, with rather distant marks of 

 growth ; umbonial slope inflated and rounded ; posterior slope narrow elliptical and 

 somewhat carinate ; cardinal teeth very small, striate, compressed, very oblique and 

 disposed to be double in both valves ; lateral teeth rather small, lamellar and sharp 

 at the end ; anterior cicatrices distinct, very large and moderately impressed ; poste- 

 rior cicatrices confluent, very large, very slightly impressed ; dorsal cicatrices very 

 small and placed under the posterior end of the cardinal tooth ; cavity of the shell 

 shallow and very wide ; cavity of the beaks very shallow and obtusely angular ; nacre 

 white and iridescent. 



Remarhs. — This is a very distinct species, and is not very closely allied to any one 

 I know. The teeth are very small and peculiar. It is to be regretted that a single 

 specimen only was sent by Dr. Emmons. Others might difi'er in the size of the teeth, 

 but this in all respects is a perfect specimen, except a slight erosion of the beaks, 

 which forbids any observations as to the undulations of the tips. In this specimen 

 the margin beyond the deposit of the nacre is disposed to be purj^lish. 



Unio lucidus. pi. 2, fig. 6. 



Testa lasvi, elliptioa, inflata, valde iuajquilaterali, postioe subbiaugulata, aiitice rotunda ; valvulis subteuu- 

 ibus; natibus prominulis, epidermide rufo-fusea vel fusco-virente, radiata, ad latere mioante ; dentibus 

 cardinalibus parvis, obtuso-conicis, crenulatis, in utroque valvule duplieibus ; lateralibus sublongis, 

 lamellatis subcurvisque ; margarita C£eruleo-alba et valde iridesoente. 



Shell smooth, elliptical, inflated, very inequilateral, subbiangular behind, round be- 

 fore ; valves somewhat thick ; beaks a little prominent ; epidermis reddish brown, 

 rayed and shining on the sides ; cardinal teeth small, obtusely conical, crenulate, 

 double in both valves ; lateral teeth rather long, lamellar and somewhat curved ; 

 nacre bluish white and very iridescent. 



Proo. Acad. Nat. Sci. 1863, p. 192. 



