The American Midland Naturalist 
PUBLISHED BI-MONTHLY BY THE UNIVERSITY 
OF NOTRE DAME, NOTRE DAME, NDIANA. 
VOL. IV. FEBRUARY, 1916. NO. 8. 
THE NAIADES OF MISSOURI.— VI. 
BY WILLIAM I. UTTERBACK. 
= JUN 14 1994 
Nephronaias ligamentina (Lamarck). » 
Pl. XXV, Figs. 85 A and B. ~<i2ma] Me 
1819— Unio ligamentina Lamarck, An. San. Vert., VI, p. 72. 
1900—Lampsilis ligamentina Simpson, Proc. U. §. Nat. Mus., XXII, 
z eee ligamentina (Lam.) Ortmann, An. Car. Mus., 
ert In. 325° 
ANIMAL CHARACTERS. 
NUTRITIVE CHARACTERS :—Branchial opening large with strong 
papillae; anal distinctly crenulated; supra-anal rather small, 
well separated from anal by thick mantle connection; gills very 
large, inner laminae of inner gills entirely connected to visceral] 
mass; palpi very large, wide and pointed; color of soft parts 
dingy white for most part, however, post-mantle edge brownish. 
REPRODUCTIVE STRUCTURES:—Marsupia occupying most of 
outer gills, consisting of' about sixty ovisacs well separated by 
thick septa, when gravid extending far below original edge of 
sterile marsupium, making a longitudinal line; mantle edge 
antero-ventrad to branchial opening with twenty-five or thirty 
low denticulations; conglutinates white, broad, leaf-like, solid 
when ova are present, cohesion lost when mature glochidia are 
developed; glochidia semi-elliptical, spineless, large, hinge line 
undulate, measures 0.220 x 0.260mm. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell rather evenly eliptical, solid, 
moderately inflated, beaks rather low, sculpture consisting of 
several fine, wavy, concentric lines most pronounced at foot of 
posterior and anterior slopes; disk smooth; epidermis brown or 
yellowish with broad, dark-green rays. 
