NAIADES OF MISSOURI 147 
Sex Length Height Diameter Locality 
O65) ox 360% xe Bom (Miss. R., Hannibal ) 
Cu Sse eS Sir Xe GG” (Meramec R., Fern Glen ) 
Co ex SO XE eS Ln (Osage R., Proctor) 
OES Sek a4 Si exe GO e Gee ” Greenwell Ford) 
OUP Aw XurU ule xa oes til ind (ee ” Osceola) 
Juvenile shell with three nodulous expansions on post-umbonal 
ridge, deep furrows between nodules; ligament bright pea green; 
epidermis straw-color; slopes of dorsal ridge slightly ribbed; 
beaks high upon dorsal line; posterior peculiarly roundly lipped 
for the branchial opening. 
MISCELLANEOUS REMARKS:—The shell characters of metanevra, 
typical of the whole genus, are highly emphasized. The enormous 
supra-anal opening and yellow mantle border at the siphonal 
opening are characteristic of its soft-parts. This species is well 
represented in Central Missouri and in the Des Moines and Miss- 
issippi, but is seldom found in North or South Missouri. The 
writer has only found it in the Grand River of North Missouri 
and while he himself has not found it in South Missouri, yet Mr. 
Walker has it in his collection from Black River, Popular Bluff, 
Missouri. Simpson ‘(1900b p. 774) reports it for general distri- 
bution throughout the Mississippi drainage area except its southern 
portion, extending to the Tennessee and Arkansas rivers. Its 
favorite habitat is sandy or gravelly shoals and, as its shell responds 
to its surroundings, the general form of shell may vary so much 
as to make it appear as a different species, or sub-species. Its 
breeding season is found to be tachytictic. 
Quadrula metanevra wardii (Lea). 
(‘“‘Monkeyface.’’) 
Not Figured. 
1861— Unio wardii Lea. Pr. Ac. N. Sci. Phila., V, p. 372; Jl. A. C.N. 
Sel Enilay Ven Pa oy le PRONG VA) figs 2157. 
ANIMAL CHARACTERS:—Identical with those of its parent 
species. 
SHELL CHARACTERS. 
EXTERNAL CHARACTERS:—Shell more elongated than its 
species, comparatively smooth, heavier, more solid, post-umbonal 
ridge with an expansion just before reaching basal line; otherwise 
