UNIO 673 
Unio strumosus Lea, Pr. Ac. N. Sci. Phila., II, 1872, p. 158; 
Wie 2e7a ep. 4esenjl ce Nooct Phila “Vill, 1874, p. 37, 
pens, ue. 55; Obs... Xl, 1874, p. Ox, pl.. xix; fig. 55— 
SIMPSON, Syn., 1900, p. 729. 
Appears to be near to U. dorsatis, but is smoother ; it scarce- 
ly has a double posterior ridge, and its beaks and posterior 
ridge are not so elevated. 
UNIO PuRUS Lea. 
Shell between subrhomboid and _ subelliptical, somewhat 
elongated, convex, inequilateral; beaks not much elevated or 
inflated, their sculpture not seen; posterior ridge high, round- 
ed, curved up in the middle, ending in a rounded point near 
the base of the shell; surface with uneven growth lines; epi- 
dermis dirty yellowish-green or dirty brownish-green, rather 
smooth in young shells, becoming dull in old ones; pseudo- 
cardinals low, solid, rough, double in both valves; laterals 
curved, strong, remote; muscle scars round, distinct; nacre 
purplish, a little thicker in front. 
Length 76, height 42, diam. 25 mm. 
Type locality, Neuse River, near Raleigh, North Carolina. 
Oniorpirds Teserr Ac. N. Se: Phila. 1, °1858, p. 41; Jl. 
Ac. N. Sci. Phila., V, 1862, p. 61, pl. 1v, fig. 209; Obs., VIII. 
1862, p. 65, pl. Iv, fig. 209.—Simpson, Syn., 1900, p. 720. 
Margaron (Unio) purus Lea, Syn., 1870, p. 43. 
A rather neat, finely formed species, which does not seem 
to connect with anything else. The outline is between rhom- 
boid and elliptical, the posterior ridge is rounded and curved 
up in the middle. 
UNIO SUBNIGER (Lea). 
Shell subrhomboid, scarcely subsolid, convex, inequilateral ; 
beaks apparently neither full nor high; posterior ridge strong, 
subangular or narrowly rounded, curved up in the middle, 
ending behind in a blunt point near the base line; base line 
incurved a little; surface with decided concentric sculpture ; 
epidermis blackish, scarcely shining; pseudocardinals small, 
