86 THE CHICAGO ACADEMY OF SCIENCES. 
the lateral teeth and forms a flat, alate projection; anterior 
adductor muscle scar oval, deeply excavated, heavily striated; 
posterior adductor muscle scar rounded, slightly impressed, 
striated, confluent; protractor pedis muscle scar wider than long, 
very deeply excavated, striated; dorsal muscle scars situated on 
the posterior face of the cardinal teeth, under the connecting 
bridge, numerous, rounded, deeply pitted; pallial line deeply 
impressed anteriorly, crenulated; cavity of the beaks deep; 
nacre varying between mauve and purple, iridescent on the 
posterior portion, having a satin finish near the cavity of the 
beaks. 
Length, 83.00; height, 66.00; breadth, 35.00 mill. Q (8090). 
“64.50; 58.00; 27.00 “ (8090). 
Animal: Anal opening small with no papille; branchial 
opening very large, with many small brown papille; palpi sub- 
triangular, united one-half way posteriorly; branchiz not large, 
nearly semicircular, inner one the larger, free nearly two-thirds 
of the length of the abdominal sac; marsupia not developed. 
(Simpson. ) 
Distribution: Found generally throughout the Mississippi 
Valley and in the Ohio Valley. 
Geological distribution: Pleistocene. 
ffabitat: Found plentifully in the larger lakes and rivers, 
on a muddy bottom. 
Remarks: A characteristic species which bears no particular 
resemblance to any other mollusk found in the area. It is con- 
fined to the southern region, where it is found of large 
size and fine coloration. 
22. Quadrula pustulosa Lea, pl. xxiv., fig. 2; pl. xxv.; pl. xxvii., fig. 13. 
Unio pustulosus Lea, Trans. Amer. Phil. Soc., Vol. IV., p. 64, pl. viii., 
fig. 7, 1880. 
Unio schoolcraftensts (schoolcraftit) Lka, Trans. Amer. Phil. Soc., Vol. V., 
p. 37, pl. iii., fig. 9, 1832. 
Unio prasinus CONRAD, New Fresh-water Shells of the United States? p. 
44, pl. iii., fig. 1, 1834. 
Unio dor feutltanus Lea, Trans. Amer. Phil. Soc., Vol. VI., p. 73, pl. xvii., 
fig. 54, 1836. 
Unio mortont CONRAD, Monograph of Unio, p. 11, pl. vi., fig. 1, 1836. 
Unio bullatus RAFINESQUE, Conrad, Monograph of Unio, pl. xl., fig. 2, 
1838. 
Unio pernodosus Lea, Trans. Amer. Phil. Soc., Vol. X., p. 71, pl. iii., fig. 8, 
1845. 
Unio asperatus Lea, Journ. Phil. Acad., 2d series, Vol. V., p. 68, pl. vii., 
fig. 218, 1861. 
