UNIO 693 
Margaron (Umi) fisherianus Lea, Syn., 1852, p. 37; 1870, p. 
Go: 
Unio nasutus CONRAD (part), Monog., IT, 1838, pl. xvii, fig. 1. 
It is difficult to separate this at all times from the northern 
form of what I believe is U. preductus. It is generally nar- 
rower and more drawn out behind, and the posterior ridge 
is almost invariably curved down in the middle, which is 
scarcely ever the case with productus. 
UnIo EMMONSII Lea. 
Shell rather large, elongated, irregularly ovate, convex, sub- 
solid, inequilateral; beaks slightly elevated, compressed, their 
sculpture consisting of strong, corrugated ridges that nearly 
follow the growth lines; posterior ridge strong, angled, curved 
down in the middle, ending behind about at the median line in 
a sharp, up-curved point; base line almost straight, curved up- 
ward towards the posterior end; surface with uneven growth 
lines, somewhat sulcate; epidermis tawny or yellowish-green 
and rayed in young shells, becoming brown in old specimens ; 
left valve with two strong, rough pseudocardinals and two lat- 
erals; right valve with two pseudocardinals, the upper small, 
and one lateral; muscle scars impressed; nacre dirty, pale 
brownish or purplish, iridescent behind. 
Length 111, height 45, diam. 25 mm. 
North Carolina. 
Type locality, Roanoke River, Weldon, N. C. 
Unio emmonsit Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 86, 
Pee Ne ocr Philas. WV, 19025.p.50, pt 11, fig. 203; Obs., 
VIII, 1862, p. 60, pl. 11, fig. 203.—Sr1mpson, Syn., 1900, p- 
£35: 
Maregaron (Unio) emmonsti Las, Syn., 1870, p. 60. 
This is a large edition of Unio fisherianus. Its dimensions 
are greater in every way, it is considerably solider, and some- 
what more inflated; the posterior ridge is higher and sharper. 
UNIO SUBINFLATUS Conrad. 
Shell subrhomboid, higher behind than in front, subsolid, 
subcompressed, inequilateral; beaks apparently very low and 
compressed ; anterior end rounded; dorsal line straight, meet- 
