UNIO 611 
Unio DANtErst B. H. Wright. 
Shell very solid, subinflated to inflated, inequilateral, sub- 
rhomboid; beaks full and high, their sculpture not observed; 
posterior ridge very full, sharp, becoming double below, be- 
hind which the posterior area is often abruptly truncated ; sur- 
face covered with rather wide growth lines and a thick, black 
epidermis, the posterior slope strongly plicate and rough; left 
valve with two triangular, rough pseudocardinals and two 
strong, curved laterals; right valve with one pseudocardinal, 
often with a small one above, and one lateral; beak cavities 
shallow ; muscle scars small and deep; nacre whitish, purplish 
or salmon, thicker in front. 
Tiength 80, height 51, diam. 34 mm. 
Length &o, height 62, diam. 46 mm. 
Type locality, Spring Creek, Decatur County, Georgia. Also, 
Escambia River, Florida. 
Unio danielsti B. H. Wricut, Naut., XIII, 1899, p. 31.—SiMp- 
SON, Syn., 1900, p. 708. 
This seems to bear about the same relation to U. mcrassatus 
that polymorphus does to forbestanus. It is a very solid, quite 
inflated form, decidedly truncated behind the posterior ridge 
and has a thick, black epidermis. 
UNIO PUSILLUS Lea. 
Shell subrhomboid, convex to subinflated, rather thin to sub- 
solid, inequilateral, with moderately full, but not high, beaks, 
their sculpture not observed; posterior ridge high and angled, 
often becoming double below, ending in a point or biangulation 
near the base of the shell; surface rather smooth ; dorsal slope 
having subradial wrinkles; epidermis dirty greenish-yellow, 
often feebly rayed; left valve with two subcompressed pseudo- 
cardinals and two rather delicate laterals ; right valve with one 
pseudocardinal, often with a second small one above it and 
one lateral; beak cavities shallow; muscle scars slightly im- 
pressed; nacre dull, bluish, purplish or lurid brownish. 
Length 58, height 34, diam. 22 mm. 
Length 43, height 26, diam. 16 mm. 
