148 THE AMERICAN MIDLAND NATURALIST 
its external and internal shell structures are identical with those of 
QO. metanevra. 
Sex Length Height Diameter Locality 
O N86 x) FO) xX! 5am (Des Moines R., Dumas) 
MISCELLANEOUS REMARKS:—Shells from the type lot, sent to 
the National Museum and now under the label of variety wardii 
of Lea, and numbered 134,639, are now in the writer’s collection 
through the kindness of the collector, B. F. Bush. However, it is 
the opinion of the writer that this form may not deserve a name 
since metanevra is subject to so many intergrades due to local con- 
ditions. The above comparative description shows its departure 
not far from type, besides the form is inconstant. 
Quadrula cylindrica (Say). 
(“Razor Handle,”* Cob Shell,” “Rabbit's Foot,” 
“Spectacle Case.’’) 
Pl XIX. Figs. 520 and B. 
1816— Unto cylindricus Say. Nich. Ency., II, Pl. IV, fig. 3. 
1819— Unio naviformis Lamarck, An. Sans., Vert. VI, p. 75. 
1900b—Quadrula cylindrica (Say) Simpson, Proc. U. S. Nat. Mus., 
XSI Di 72785 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening moderately 
large with brownish yellow tentacles; anal finely papillose; supra- 
anal briefly connected to anal by mantle edge; gills very long and 
narrow, outer more narrow anteriorly, inner laminae free from 
visceral mass; palpi long, narrow connected one-third of their 
length antero-dorsad; color of soft parts peculiar, foot with orange 
back-ground striped in black, visceral mass uniorange, mantles 
with black pigment especially along the margins at siphonal 
openings. 
REPRODUCTIVE STRUCTURES:—Only sterile marsupia found, 
these with normal structures of Quadrula. Glochidia unknown. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell rectangular-elongate, length 
three times the height, dorsal posterior ridge, long, high, slightly 
costated; wide behind, abruptly rounded before; post-umbonal 
ridge high, hummocky and pustulate; umbones low, somewhat 
sharp pointed, incurved, sculptured by corrugated ridges breaking 
into tubercles out on disk; epidermis dark straw painted (as 
