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exterior surface of the body wliorl ; at base the lip is adpressed 

 and covers the umbilicus ; labrum with a large, prominent, oblique, 

 lamelliform tooth ; umbilicus closed. 



Greatest transverse diameter nearly nine-twentieths of an inch. 

 Inhabits lower Missouri. 



The teeth of the labrum somewhat resemble those of tridentata; 

 but in the form of the groove behind the labrum, and the pillar- 

 tooth, it resembles H. hirsuia. Several specimens were found, but 

 all dead shells, and destitute of their epidermis. 



H. CLAUSA. — Shell fragile, slightly perforated, subglobular, 

 yellowish horn color, above convex ; whorls four or five : aperture 

 slightly contracted by the lip ; lip reflected, flat, white, nearly 

 covering the timbilicus. 



Inhabits Illinois. Greatest breadth from one half to three-fifths 

 of an inch. 



A small and handsome species, which somewhat resembles albo' 

 labris, but is much smaller, more rounded, and is subumbilicate. 

 This shell also occurs, though, perhaps rarely, in Pennsylvania. 



II. OBSTRICTA. — Shell depressed, with elevated lines forujing 

 grooves between them ; epidermis pale brownish, naked ; volutions 

 five, depressed above, beneath rounded, with an acute, projecting 

 carina ; umbilicus covered with a white callus, indented ; mouth 

 resembling that of H. palliata. 



Inhabits Ohio. Breadth nearlj' one inch. 



This species is very closely allied to Helix palliata, but the 

 epidermis is not covered with small elevations as in that shell, and 

 the carina is very prominent and remarkable. 



H. ELEVATA. — Shell pale horn color, spire elevated ; whorls 

 seven, regularly rounded; umbilicus none; aperture somewhat 

 angulated ; labrum dilated, reflected, pure white, at base adpressed 

 to the body whorl, abruptly nan-owed on the inner edge beneatli 

 the middle, and continuing thus narrowed to the superior termina- 

 tion, leaving a projecting angle behind the middle ; labium with a 

 large, robust, very oblique, subarquated, pure white tooth. 



Greatest breadth seven-eighths of an inch. Column nine-six- 

 teenths of an inch. 



Found rather common in the vicinity of Cincinnati, Ohio. It 

 seems to be distantly related to thyroidus by the tooth on the 

 labium, but this tooth is much more robust ; it difl'ers much more 

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