NAIADES OF MISSOURI 135 
Quadrula quadrula Rafinesque. 
(‘Maple Leaf,” ‘‘ Monkey Face,” ‘Tear Shell.’’) 
PIX. Fig: 19; Plo XVII. Figs 45 A—F. 
1820—Quadrula quadrula Rafinesque, An. Gen. Sci. Phys. Brux. 
Pp. 305. 
1828— Unio lacrymosus Lea, Tr. Phil. Soc., III, p.:272, pl. VI, fig. 8. 
1831— Unto asperrimus Lea, Tr: Am. Phil. Soc., IV, p..71, pl. V., fig. 3. 
1834— Unto quadrulus Say, Am. Conch, VI. : 
1898—Quadrula lachrymosa Baker, Moll. Chicago, Pt. I, p. 83, pl. 
ONOVE toa NOI ohio 2h 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening rather large 
with arboreal papillae; anal slightly crenulate; supra-anal very 
large closely connected to anal by mantle edges; palpi very long 
united about two thirds of their length antero-dorsad and heavily 
vein marked; inner laminae of inner gills free from visceral mass; 
color of most soft parts tanned flesh color. 
REPRODUCTIVE STRUCTURES :—All four gills marsupial; ovisacs 
wide in middle transversely, ventral positions being divided, 
giving the white conglutinates a double or triple split appearance, 
septa thickened at intervals leaving thin transparent elongated 
spots arranged regularly and transversely in the conglutinates; 
glochidia not found by writer; Dr. Surber reports it as the smallest 
of the Quadrulae; color. of charged marsupia brown; crenulated 
flap on post-dorsal part of foot; probably sexual in function as 
only. noted in females. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell medium in size, subquadrate 
to subtrigonal, dorsal ridge more or less alated with costae on 
slopes undulated or sulcated post-umbonal ridge prominently 
angled set with coarse tubercles, a valley or radial furrow in front 
bounded anteriorly by a row of more or less irregularly placed 
tubercles on center of inflated disk, presenting the appearance 
of drops of melted wax; epidermis varies from olive green to chest 
nut brown or even black, in some instances faintly rayed anteriorly 
and with continuations of green paintings ventrad to some of the 
tubercles; beaks high, full, furrowed, post-obliquely, sculptured 
with corrugated, concentric ridges that break into great numbers 
of small tubercles out on the umbonal region. 
