844 QUADRULA 
median ridges; epidermis brownish, not shining ;. pseudocar- 
dinals elevated, exceedingly ragged and torn; lateral of the 
right valve usually single; beak cavities deep, compressed; 
anterior scars small; nacre white, thinner and slightly irides- 
cent behind. 
Length 96, height 85, diam. 53 mm 
Ohio, Cumberland, and Tennessee river systems; westward 
probably to Minnesota, Nebraska, and Kansas. 
Type locality, Scioto River, Ohio. 
Unio fragosus Conrap, Monog., II, 1836, p. 12, pl. v1, fig. 2.— 
Kuster, Conch. Cab. Unio, 1861, p. 173, pl. Lv, fig. 1.— 
Reeve, Conch. Icon., XVI, 1864, pl. 1, fig. 2; pl. vu, fig. 27. 
Margarita (Umno) fragosus Lea, Syn., 1836, p. 14; 1838, p. 15. 
Margaron (Unio) fragosus LEA, Syn., 1852, p. 22; 1870, p. 33. 
Unio fragosa CatLow and Reve, Conch. Nom., 1845, p. 59. 
Quadrula fragosa SIMPSON, Syn., 1900, p. 778. 
Unio tragosus HANLEY, Biv. Shells, 1843, p. 178, pl xx, fig. 4o. 
A robust, rude, short quadrate species with strong tubercles, 
which sometimes are knob-like on the posterior and median 
ridges. The epidermis is brown, rayless and dull. It is gen- 
erally much more quadrate than lachrymosa and has stronger 
sculpture, though there are intermediate specimens that are 
sometimes difficult to place. 
QUADRULA FORSHEYI (Lea). 
Shell rather short, subquadrate, subinflated, nearly or quite 
equilateral, solid; beaks elevated but not inflated, their sculp- 
ture sharply doubly-looped ridges; posterior ridge well de- 
veloped, single above, double below, ending at the base of the 
shell in a biangulation and having in front of and behind it 
a radial depression; anterior end round; base line incurved 
in front of the posterior ridge; posterior end almost squarely 
truncated, with a sinus just above the termination of the poste- 
rior ridge; surface with uneven growth lines, more or less 
covered throughout with rather small tubercles; epidermis 
greenish in young shells, brownish or ashy-brown in old ones ; 
pseudocardinals strong, triangular, not greatly torn; lateral 
