132 



LAND AND FRESH-WATER SHELLS OF N. A. [PART I. 



sometimes bifid, and even trifid, and very much inflected ; the 

 parietal tooth extends quite to tlie base of the shell, and unites 

 with the extremity of the peristome ; the aperture is nearly filled 

 up by the teeth and the contraction of the peristome. 



Fig. 223. 



Helix iiitrofereics, Bland. — Shell umbilicate, globose, depressed, 

 thin, with lib-like sti'i?e, yellowisli hoin-colored ; spire convex ; whirls 

 six, moilerately convex, the last scarcely descending, uiulIi constricted at 

 the aperture, with two exterior pits, subangular at the peri- 

 phery, convex beneath, grooved within the nnibilicus; aper- 

 ture oblique, lunate, with a well-developed, arcuate parietal 

 tooth ; peristome white, thickened within, reflected ; on the 

 right margin an obtuse inflected tooth, at the base a sub- 

 marginal lamelliform tooth, with transverse tubercle in the 

 centre; the basal lamella continued within the aperture, 

 where it forms a strong white tubercle. Greater diam. 15, 

 lesser 13 ; height 7 mill. 



Helix intrqferens, Blaxd, Ann. N. Y. Lye. VII, 117, pi. iv, f. 3, 4 (1860). 

 Triodopsis introferens, Tryon, Am. Journ. Conch. HI, 51, pi. ix,f. 5 (1867). 



Gaston County, N. C. ; Salem, N. C. 



This shell is closely allied to H. vultuosa, and also to IT. fallax. 

 It differs from the latter in the narrower umbilicus, which only 

 shows the penultimate whirl ; in the groove in the last whirl 

 within the umbilical opening, the character of the basal tooth, 

 and the internal tubercle, which does not prevail in fallax and 

 its immediate allies tridentata and hopetonensis. In H. intro- 

 ferens the upper tooth is less deeply seated and less inflected, 

 and the basal one is broader, and more elevated than in vultuosa, 

 the parietal tooth is more arcuate, being indeed subangular, but 

 is without the indication, noticeable in vultuosa, of a callus ex- 

 tending from its lower termination towards the upper angle of 

 the peristome. H. vultuosa is even smaller than the var. minor 

 of this species, which is only 11 mill, in diameter. 



Helix Itopetonensis, Shuttleworth. — Shell with a narrow, 

 scarcely pervious umbilicus, depressed-globose, with numerous rib-like 



