696 UNIO 
ridge moderate, narrowly rounded or subangulate, sometimes 
inclined to be double below, ending behind in a long point at 
or below the median line; anterior end rounded or cut away 
a little below ; base line nearly straight or lightly curved; dor- 
sal slope obliquely subtruncated; surface with fine, concentric 
sculpture ; epidermis dirty yellowish-green, profusely but feebly 
raved, rather rough and dull; pseudocardinals low, sometimes 
imperfect, double in each valve; laterals straight ; muscle scars 
shallow ; nacre whitish, tinged with dirty purple. 
Length 83, height 30, diam. 16 mm. 
Georgia. 
Type locality, Swift Creek, Macon, Ga. 
Unio rostreformys na, Pr. “Ac. N. Se Phila; VE, 1856, p. 
262.—SIMpson, Syn., 1900, p. 736. 
Unio rostriformis Lea, Jl. Ac. N. Sci. Phila., 1V, 1858, p. 64, 
pl. x, fie. -46°-Obs., Vi. 1858, p64, plas, fie. 46: 
Margaron (Unio) rostriformis LEA, Syn., 1870, p. 60. 
Unio maconensis Lea, Pr. Ac. N. Sci. Phila., 1X, 1857, p. 172; 
Ji AG IN: Seite Rhilas VW. S1Sis8. ip. 1034 pls sexe wher a7 Osa. 
Vi,1858, p2.03) pl Xx, fig73. 
Margaron (Unio) maconensis Lea, Syn., 1870, p. 60. 
Close to fisherianus but rougher and having a greener epi- 
dermis. ‘The posterior ridge of this species is generally 
straight, and sometimes curved up a little in the middle; that 
of fisherianus generally is curved down in the middle. U. ros- 
treformis is usually a little higher behind than fsherianus. 
UNIO DUTTONIANUS Lea. 
Shell long, subelliptical, the dorsal and ventral lines being 
nearly parallel, inequilateral, subinflated, solid; beaks appar- 
ently not much elevated; posterior ridge moderate, narrowly 
rounded, becoming almost double below, ending in a feeble 
biangulation on or a little above the median line; anterior end 
rounded; base line almost straight; epidermis dark brown, 
obscurely rayed; pseudocardinals very small, compressed ; lat- 
