614 UNIO 
| have never seen anything, which I could refer to this spe- 
cies and am a little in doubt as to its systematic position. 
Conrad states that he found it in company with great num- 
bers of U. congareus in the Savannah River, at Augusta, and 
that it perhaps has more affinity with that than any other spe- 
cies. It is shorter and more rounded than U. merus or any of 
the forms of the crassidens group. If it were not that it is 
said to come from the Savannah River | should think it might 
be one of the Pleurobemas, and I am not sure but that it is. 
UNIO FRATERNUS Lea. 
Shell somewhat elongated, subsolid, subrhomboid, com- 
pressed or subcompressed, inequilateral ; beaks apparently not 
full or high, much eroded in the only shells examined ; poste- 
rior ridge well developed, angled, single above, faintly double 
below, ending near the base in a narrow, ill-defined biangula- 
tion; surface with feeble growth lines, strongly, radiately 
wrinkled on the dorsal slope; epidermis dark reddish-brown, 
scarcely lamellosely wrinkled, subshining ; left valve with two 
low, stumpy pseudocardinals, and two remote laterals; right 
valve with one pseudocardinal and one lateral; beak cavities 
shallow, with a row of dorsal scars just at the lower side of 
the hinge plate; muscle scars shallow; nacre purplish-white, a 
little thicker in front. 
Length 65, height 37, diam. 19 mm. 
Length 60, height 32, diam. 15 mm. 
Type locality, Abbeville District, South Carolina. 
Umo.fraternus. Lea, Vr. Am, Phill Sec, 1852, p.. 26s) pl: 
XVI, fig. 15; Obs:, V;, 1852, p. 10,epl. xvi, fies 15 Kose, 
Conch. Cab. Unio, 1861, p. 201, pl. Lxvi, fig. 2—SrImpson, 
Syn, 19G0,,\p., 700. 
Margaron (Unio) fraternus Les, Syn., 1852, p. 32; 1870, p. 
51. 
\ somewhat elongated, compressed shell, with reddish- 
brown epidermis and purplish nacre. It is more compressed 
and darker colored than U. congareus, to which it seems near- 
ly allied and its pseudocardinals are more stumpy. Dr. Lea has 
