1s DESCRIPTION OF NEW 
Shell smooth, elliptical, rather inflated; valves somewhat thick; beaks somewhat prominent; epidermis dark- 
brown; cardinal teeth rather small and erect; lateral teeth long and nearly straight; nacre white and iridescent. 
Hab. Abbeville District, S.C. J. P. Barratt, M. D. 
My cabinet and cabinet of Dr. Barratt. 
Diam. .7, Length 1, Breadth 1.7 inches. 
Shell smooth, elliptical, rather inflated, rounded before and angular behind; substance 
of the shell rather thick, thinner behind; beaks somewhat prominent, submedial; ligament 
rather short and thin; epidermis dark-brown, with obscure rays, very smooth and polished; 
marks of growth distant, regular and well marked; cardinal teeth rather small, compressed, 
double in the left and single in the right valve; lateral teeth long, nearly straight and 
enlarged at the posterior end; anterior cicatrices distinct; posterior cicatrices confluent; 
dorsal cicatrices placed on the under side of the cardinal tooth; cavity of the shell rather 
shallow; cavity of the beaks shallow and angular; nacre white and iridescent. 
Remarks.—Dr. Barratt sent me three specimens of this species, one only being adult. 
Neither of them have the beaks sufficiently perfect to show any undulations. In outline 
it resembles U. concavus, (Nobis,) but it is more compressed, and differs much in the colour 
of the epidermis and the rays. The adult specimen is slightly salmon coloured in the 
cavity of the beaks. One of the younger specimens is distinctly salmon coloured. 
Unio premaus. Pl. XV. Fig. 14. 
Testa levi, elliptica, subcompressd, striata; valvulis subtenuibus; natibus subprominentibus ; epidermide 
tenebroso-fusca ; dentibus cardinalibus parvis; lateralibus linearis subcurvisque; margarita cxruled et 
iridescente. 
Shell smooth, elliptical, rather compressed, striate; valves rather thin; beaks somewhat prominent; epidermis 
dark-brown; cardinal teeth small; lateral teeth linear and slightly curved; nacre bluish and iridescent. 
Hab. Abbeville District, S.C. J. P. Barratt, M.D. 
My cabinet. 
Diam. .4, Length .7, Breadth 1.2 inches. 
Shell smooth, elliptical, rather compressed, striate, rounded before and angular behind; 
substance of the shell rather thin, thicker before; beaks somewhat prominent; ligament 
short and thin; epidermis dark-brown, striate, with obscure rays, and slightly polished; 
umbonial slope angular; marks of growth indistinct; cardinal teeth small, compressed; 
lateral teeth rather long, linear, slightly curved, and thickened at the posterior end ; 
anterior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices in the centre 
of the cavity of the beaks; cavity of the shell shallow; cavity of the beaks small and 
angular; nacre blue and very iridescent behind. 
Remarks.—This is a very small species, and a single valve only, (the right) has been 
received by me. I do not think this is quite adult. The beak is not sufficiently perfect 
to observe any undulations. This shell is about the size of U. fabalis, (Nobis,) and 
parvus, Barnes, but cannot be confounded with either of them. It is a thinner shell than 
the former and less inflated than the latter. 
