UNIO 641 
cardinals and two curved laterals ; right valve with two pseudo- 
cardinals, the upper small, and one lateral; beak cavities gen- 
erally shallow ; nacre dirty bluish or purplish-white. 
Length 60, height 34, diam. 22 mm. 
Length 48, height 26, diam. 17 mm. 
Length 43, height 26, diam. 18 mm. 
North Carolina to Florida. 
‘Type locality, Roanoke River, Weldon, N. C. 
Unio msulsus Lea, Pr. Ac. N. Sci. Phila., I, 1857, p. 86; Jl. 
Ac seeock Pnitla, bX. 1862) p. 53, pl. 1, fig: 199; /Obs.,. VIII, 
1862, p. 57, pl. L fig. 199.—Stmpson, Pr. U. S. Nat. Mus., 
mV, 1802; p- 422. pl rxv, fies. 1, 5< Syn., 1900; p. 716. 
Margaron (Unio) insulsus Lea, Syn., 1870, p. 53. 
Unio hicidus Lea. Pr Ac. N. Sci: Phila, VIL, 1863, p. 192; 
joke. NO Se Phila. V1, 1866, pxo,-pl. 11, fig. 6; Obds., X61, 
FO07, p:-13, pl. 11, fig. 6. 
Margaron (Unio) lucidus Lea, Syn., 1870, p. 48. 
Unio cistelliformis Lea, Pr. Ac. N. Sci. Phila., VII, 1863, p. | 
[D2 fk Ac. SclLaPhilas NI, «1866, p: 10,, pl. vin fig. 375 
Obs. Ki 1867, pi 23, pl. viy fis. 17: 
Margaron (Unio) cistelliformis Lea, Syn., 1870, p. 52. 
Smaller, more generally and decidedly rhomboid than its 
near ally U. confertus. It is usually a rougher, dirtier, duller 
colored shell than that of confertus. 
UNIO OBNUBILUS Lea. 
Shell subrhomboid, convex or subinflated, subsolid to solid, 
inequilateral ; beaks not much elevated or inflated, their sculp- 
ture not observed; posterior ridge well developed, double, 
ending behind in a faint biangulation below the median line ; 
surface with low, irregular growth lines, rather smooth, cov- 
ered with a greenish-brown epidermis, which is rarely very 
feebly raved, subshining; left valve with two stumpy, rough- 
ened pseudocardinals and two curved laterals; right valve 
with two pseudocardinals, the upper low and indistinct, with 
