64 NAIADES OP MISSOURI 



Quadrula metanevra (Rafinesque). 



("Maple Leaf," "Monkey-face" "Stranger.") 



PL XIX, Figs. 53 A and B. 



1820 — Obliquaria (Quadrula) metanevra Rafinesque, Ann. Gen. Sei. 



Brux., V, p. 305- PI- LXXXI, fig. 15 and 16. 

 1834 — Unio metanevrus Say, Am. Conch., VI. 

 1900b — Quadrula metanevra (Raf.) Simpson, Proc. U. S. Nat. Mus., 



XXII, p. 774- 



ANIMAL CHARACTERS. 



Nutritive vStructures: — 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 difterent 

 color being a straw-yellow of the mantle margin at branchial 

 opening. 



Reproductive vStructures:- -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 

 0.190mm., 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. 



