146 THE AMERICAN MIDLAND NATURALIST 
Quadrula metanevra (Rafinesque). 
(‘‘Maple Leaf,” ‘“‘Monkey-face’”’ “‘Stranger.’’) 
Pl. XTX, Fags. 53 A and B. 
1820—Obliquaria (Quadrula) metanevra Rafinesque, Ann. Gen. Sci. 
Bruix, Viep. 305. bl DXxxodsie 15 and 16: 
1834— Unio metanevrus Say, Am. Conch., VI. 
1900b—Quadrula metanevra (Raf.) Simpson, Proc. U. S. Nat. Mus., 
Sep 774s 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening large with short 
feathered papillae; anal smooth to finely dentate; supra-anal very 
long, open, closely connected by mantle edges to anal; gills 
short and wide the anterior connection of outer to mantle far 
removed from base of palpi, inner laminae of inner gills free from 
visceral mass; palpi long, pointed, connected for one-third of their 
length; color of soft parts mostly a dingy white, the only different 
color being a straw-yellow of the mantle margin at branchial 
opening. 
REPRODUCTIVE STRUCTURES:—-All four gills marsupial, septa 
and water tubes (ovisacs) well developed, when gravid, marsupia 
moderately swollen, ventral margins sharpened; conglutinates 
white, broken, compressed, leak-like; glochidia average 0.180 x 
o.190mm., semi-elliptical, ventral margin rounded, spineless, 
medium size, hinge line undulate. ‘ 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell roughly pentagonal, alated, 
deeply furrowed between dorsal and post-umbonal ridges to 
emarginated post-dorsal portion; shallow radial furrow just 
in front of coarsely tuberculated and prominent post-umbonal 
ridge; disk with smaller, tear-like tubercles scattered all over; 
beaks rather apiculated, sculptured by coarse corrugations extend- 
ing out on disk; epidermis brownish yellow, pointed by irregular, 
downward pointing, green, chevron-like splotches. 
INTERNAL STRUCTURES:—Cardinals doubled in both valves; 
laterals also doubled, right faintly so; beak cavities deep, com- 
pressed; nacre pure white to pale pink, 
