70 DESCRIPTION OF NEW 



confounded with any other, except one from the Chatahoochee, for which I propose 

 the name of pellucidus. It is more triangular than that shell, and differs in the peculiarity 

 of the lateral teeth in both valves being single, while in that shell it is double in the right 

 valve. 



Unio atro-costatus. PI. II. Fig. 5. 



Testa plicatd, subquadratd, injlatd; valvulis crassis; nalibus prominentibits ; epidermide nigra, striata: 

 dentibus cardinalibus magnis; lateralibus sublongis subrectisque ; margaritd alba et iridescente. 



Shell folded, somewhat quadrate, inflated; valves thick; beaks somewhat prominent; epidermis black and 

 striate; cardinal teeth large; lateral teeth rather long and nearly straight; nacre white and iridescent. 



Hab. Claiborne, Alabama — Judge Tait. Tuscaloosa, Alabama — B. W. Budd, M. D. 

 Alexandria, Louisiana — Josiah Hale, M. D. 



My cabinet and cabinets of Dr. Budd and Dr. Hale. 

 Diam. 1.6, Length 2.5, Breadth 3 inches. 



Shell folded, somewhat quadrate, inflated; substance of the shell thick, thinner behind; 

 beaks large, rounded, and rather prominent; ligament rather short and thick; epidermis 

 black and striate; cardinal teeth very large, thick, and wide, double in the left and dis- 

 posed to be treble in the right valve; lateral teeth rather long and nearly straight; 

 anterior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices on the under 

 side of the plate near to the cardinal tooth ; cavity of the shell rather deep and rounded; 

 cavity of the beaks shallow and angular ; nacre white and iridescent. 



Remarks. — The late Judge Tait sent me several specimens of this species, many years 

 ago, and subsequently I have received specimens from Drs. Hale and Budd, which have 

 cleared up my previous doubts of its being distinct from its allied species V. undulatus, 

 Barnes. It may be distinguished by the outline of atro-costatus being more rounded — 

 scarcely taking a quadrate form — in having a more elevated umbo, and in being quite 

 black, where the individual is mature — the young being usually a dark-green. 



The specimens, six in number, sent to me by Dr. Budd, are all from Tuscaloosa, and 

 are only slightly folded, the surface of the disk presenting small, irregular undulations, 

 which give it a somewhat varicose or subnodose appearance. The largest of them is 

 only two and a half inches wide, while the largest from Claiborne is nearly five inches 

 wide. There is a slight purple tint on the posterior margin of those from Alexandria. 



Unio pellucidus. PI. II. Fig. G. 



Testa Ixvi, obovald, subcompressd, pellucida; valvulis pertenuibus; nalibus prominulis, ad apices undulatis; 

 epidermide tenebroso-fuscd ; dentibus cardinalibus parvis, compressis ercctisquc; lateralibus longis, rectis 

 lamellalisque; margaritd cieruleo-albii et iridescente. 



Shell smooth, obovate, rather compressed, pellucid; valves very thin ; beaks slightly prominent, undulated at 

 the beaks; epidermis dark-brown; cardinal teeth small, compressed, and erect; lateral teeth long, straight and 

 lamellar; nacre bluish-white and iridescent. 



Hab. Chatahoochee river, Georgia. Major Le Conte. 

 Cabinet of Major Lc Conte. 

 Diam. .5, Length .8, Breadth 1.3 inches. 



