144 THE AMERICAN MIDLAND NATURALIST 
supra-anal region. This lack of mantle connection is a constant 
character in this species, whereas this deciduity is inconstant among 
other Quadrulae. The fact of its partial union of the inner laminae 
of the inner gills with the visceral mass is also a departure from 
the general characters of this genus and a step toward the modern 
arrangement. In this latter character nobilis is somewhat like 
Megalonaias heros. From the fact that females were found sterile 
all through. early and mid summer, it may be inferred that its 
breeding season is very short and begins early in spring, or like, 
heros begins late in the season. Later investigations may 
relate this species more closely to Megalonaias for the physiolo- 
gical reasons as well as for the morphological. 
Quadrula verrucosa Rafinesque. 
(‘‘Deer Horn,’’ ‘‘Buck Horn.’’) 
BE SLAG Hags) 50-8 
1820— Unio (Obliquaria) verrusoca Rafinesque, Ann. Gen. Phys. Brux. 
1823— Unio tuberculata Barnes, Am. Jl. Sci., VI, p. 125, Pl. VII, figs., 
8a, 8b. 
1899—Tritogonia tuberculata Simpson, Pr. U. S. Nat. Mus., p. 608. 
1912a—Quadrula tuberculata Ortmann, Ann. Car., Mus., p. 254. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening densely ° set 
with arboreal papillae, anal crenulated, supra-anal smooth, very 
large, slightly (even deciduously) connected to anal by mantle 
edges; gills very long, comparatively narrow, inner broader, 
inner Jamina of iuner gills connected to visceral mass except for 
a short distance anteriorly; palpi very’ long, connected antero- 
dorsad for a little more than half their length; color of soft parts, 
mostly solid white, gills brown. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES :—Shell rather large, elongate, roughly 
trapezoid; male shell shorter, more pointed posteriorly and 
angled dorsad; female shell much longer, biangulated post-ventrad; 
disk profusely tuberculated, the coarser tubercles located ventrad; 
post-umbonal ridge prominent and nodulated; slopes of post- 
dorsal ridge faintly costated, beaks rather small, apiculated, 
sculptured with double-looped, zigzag markings that extend out 
on the disk; epidermis chestnut brown to dark horn color, 
