34 MEMOIRS OF THE CARNEGIE MUSEUM. 



Co. Shell much longer than high. Groove of disk shallow, and covered with the same nodules 



as the anterior part of the shell Q. verrucosa. 



62. Shell siibtrapezoidal, with a broad and distinct posterior ridge. In front of this ridge, and behind, 

 a slight depression, but no distinct radial groove. Tubercles of this ridge generally 

 large. Rays of epidermis generally broken up into characteristic spots. 

 Ci. Shell subtrapezoidal or subrhomboidal, about as high as long. Sculpture of disk generally 



well-developed Q. metanevra. 



Co. Shell subrectangular, much longer than liigh. Sculpture of disk often poorly developed. 



Q. cylindrica. 



QuADRULA pusTULOSA (Lea) (1831). 

 Quadrula pustulosa (Lea) Simpson, 1914, p. 848. 



Plate III, figs. 4, 5. 

 Records from Pennsylvania: 



Harn, 1891 (Western Pennsylvania). 



Rhoads, 1899 (Oluo River, Coraopolis, Allegheny Co., and Beaver River, Wampum, Lawrence Co.). 



Ortmann, 19096, p. 199. 



Characters of shell: Shell of not more than medium size, but rather heavy. 

 Outhne subcircular, or obovate, about as high as long, not oblique, but rather 

 upright. Beaks moderately prominent. Beak-sculpture consisting of two to 

 three indistinct, concentric ridges, slightl}^ angled and nodulous behind, not con- 

 tinued upon the disk. Shell from rather swollen to rather flat, evenly convex, 

 without, or with very indistinct, posterior ridge. Basal margin evenly rounded. 

 Surface sculptured by very irregular and variable nodules or pustules, absent 

 towards the beaks. Sometimes the surface remains entirely smooth, but generally 

 the pustules begin at a certain distance from the beaks, and are larger or smaller, 

 rounded or transverse. Upon the posterior slope they are absent or present, and, 

 when present, generally smaller, and often arranged in radiating ribs, or they are 

 entirely rib-like. Epidermis yellowish brown to brown, when young, generally 

 with distinct green rays, one of which is characteristically broad, sometimes inter- 

 rupted so as to form blotches. Growth-rests dark brown. 



Hinge-teeth heavy, more or less ragged. Pseudocardinals slightly divergent. 

 Interdentum present, narrower or broader. Lateral teeth rather strong and short. 

 Beak cavity rather deep. Dorsal muscle scars upon the hinge plate. Nacre 

 always white. No difference whatever between the male and female shell.^* 



L. H. D. 



Size: Kelly, Cat. No. 61.4365 (largest at hand, c?) 72 mm. 70 mm. 36 mm. 



-' Call (1896a, p. 43) says that " the female is often somewhat emarginate." This is not always 

 so in the females at hand; in fact this slight emarginatioii of the posterior margin, which is actually 

 often observed in this species, has no relation to sex, 



"««»««— iMiiiin»imiiiiii Hm i i i wii 



