10 DESCRIPTION OF NEW 
Unio sorpipis. Pl). XU. Fig. 1. 
Testa levi, elliptica, subcompressa, inequilaterali, poslice rotundald; valvulis subcrassis; natibus promi- 
nulis; epidermide rufo-fuscda, striata; dentibus cardinalibus parvis ; lateralibus longis subrectisque: marga- 
rita alba et iridescente. 
Shell smooth, elliptical, rather compressed, inequilateral, rounded behind ; valves rather thick; beaks slightly Z 
prominent; epidermis reddish-brown, striate; cardinal teeth small ; lateral teeth long and nearly straight ; nacre 
white and iridescent. 
Hab. Abbeville District, 8. C. J. P. Barratt, M.D. 
My cabinet. 
Diam. .8, Length 1.3, . Breadth 2.4 inches. 
Shell smooth, elliptical, rather compressed, inequilateral, rounded before and behind; sub- 
stance of the shell rather thick, thinner behind; beaks slightly prominent and nearly terminal; 
ligament long and thick ; epidermis reddish-brown, obtusely rayed, with obscure equidistant 
marks of growth; umbonial slope rounded; cardinal teeth very small and striate, single 
in the right and double in the left valve ; lateral teeth long and nearly straight, separated 
from the cardinal tooth; anterior cicatrices distinct; posterior cicatrices confluent; dorsal 
cicatrices nearly in the centre of the cavity of the beak, under the cardinal tooth; cavity 
of the shell shallow; cavity of the beaks very shallow and subangular; nacre white and 
iridescent. 
Remarks.—A single imperfect specimen only of this was received by me, and I hesitated 
for some time to describe it, in hopes of getting more to determine its characters better, 
It is certainly very much like the widely distributed U. complanatus; but it seems to me to 
differ in its form, being more rounded behind, more rounded over the umbones, and more 
compressed over the umbonial slope. 
Unio Gizsesianus. Pl. XII. Fig. 2. 
Testa levi, elliptica, subcompressa, inequilaterali, poslice subbiangulatd; valvulis subcrassis; natibus 
prominentibus ; epidermide luteo-fusca, radiata, striata; dentibus cardinalibus parvis, tripartilis ; lateralibus 
prelongis subrectisque; margarita alba et iridescente. . 
Shell smooth, elliptical, somewhat compressed, inequilateral, subbiangular behind; valves rather thick; beaks 
prominent: epidermis yellowish-brown, radiated, striated; cardinal teeth small; lateral teeth very long and 
nearly straight; nacre white and iridescent. : 
Hab. Abbeville District, S.C. Louis R. Gibbes, M. D. 
My cabinet. 
Diam. 1, Length 1.5, Breadth 2.8 inches. 
Shell smooth, elliptical, somewhat compressed, inequilateral, rounded before and sub- 
biangular behind; substance of the shell thick; beaks prominent and submedial; ligament 
long and very thick; epidermis yellowish-brown, obscurely radiated, roughly striate near 
the margin, smooth on the umbones, marks of growth nearly equidistant and distinct; 
umbonial slope rounded; cardinal teeth small, slightly elevated, pointed and tripartite ; 
lateral teeth very long, nearly straight and thickened at the posterior end, separated from 
the cardinal tooth; anterior cicatrices distinct; posterior cicatrices distinct; dorsal cica- 
