16 DESCRIPTION OF NEW 
greenish, with obscure rays, and the undulations of the beaks are less pronounced than 
those of the complanatus. It is somewhat like U. folliculatus, (Nobis,) but is a thinner and 
less transverse species. ‘The older specimens are very much compressed in the middle, 
near to the basal margin. 
Unio mervus. Pl. XV. Fig. 10. 
Testa levi, ellipticd, subinflaté; valvulis crassis; natibus subprominentibus, ad apices undulatis; epider- 
mide luted, radiata, nitidd; dentibus cardinalibus magnis, crenulatis ; lateralibus longis, rectis, a cardinalibus 
separatis; margarita alba et iridescente. 
Shell smooth, elliptical, somewhat inflated; valves thick ; beaks somewhat prominent, undulated at the beaks; 
epidermis yellow, radiated, shining; cardinal teeth large, crenulate; lateral teeth long, straight and separated from 
the cardinal tooth; nacre white and iridescent. 
Hab. Abbeville District, S.C. J. P. Barratt, M. D. 
My cabinet and cabinet of Dr. Barratt. 
Diam. .6, Length 1, Breadth 1.5 inches. 
Shell smooth, elliptical, rather inflated, somewhat striate, rounded before and angular 
behind; substance of the shell thick, thinner behind; beaks somewhat prominent, rather 
coarsely undulated at the tip; ligament short and rather thick; epidermis yellow, obscurely 
radiated, shining; umbonial slope subangular; marks of growth distant and distinct; car- 
dinal teeth large, compressed, crenulate, pointed, single in the right and double in the left 
valve; lateral teeth long, straight, lamellar, separated from the cardinal tooth; anterior 
cicatrices approximate; posterior cicatrices confluent; dorsal cicatrices situated on the 
under side of the cardinal tooth; cavity of the shell shallow; cavity of the beaks small and 
angular; nacre white and iridescent. 
Remarks.—In its general character, this species resembles U. Congarzus, (Nobis.) It 
is not, however, so much compressed, and the angle of the umbonial slope is much less 
expressed. Of the six specimens before me, five have white nacre. The sixth and largest — 
is slightly tinted with salmon colour. 
Unio concavus. Pl. XV. Fig. 11. 
Testa levi, ellipticd, inflata; valvulis subtenuibus; natibus prominulis; epidermide pallido-luteola, virido- 
striata; dentibus cardinalibus parvis, compressis; lateralibus longis reclisque; margarita alba et iridescente. 
Shell smooth, elliptical, inflated; valves rather thin; beaks slightly prominent; epidermis pale-yellow, with 
green rays; cardinal teeth small and compressed; lateral teeth long and straight; nacre white and iridescent. 
Hab. Abbeville District, S.C. J. P. Barratt, M. D. 
My cabinet. : 
Diam. .8, Length 1.2, Breadth 2.2 inches. 
Shell smooth, elliptical, inflated, rounded before and subangular behind; substance of 
the shell rather thin, slightly thickened before; beaks slightly prominent, nearly medial; 
ligament rather long and thin; epidermis pale-yellow, with numerous green rays reaching 
to the margin, smooth and polished, scarcely showing the lines of growth; cardinal teeth 
compressed, single in both valves, and abruptly terminated; lateral teeth long, straight, 
