HELIX. 



129 



Fig. 217. 



Helix rtlgeli, Shuttlewoktii. — Shell imperforate, orbicularly-con- 

 vex, with granixlate striations anil few hairs, waxen horn-color ; spire short, 

 obtuse ; whirls five and a half, rather convex, the last suddenly falling iu 

 front, and strongly contracted at the aperture; aper- 

 ture depressed, narrowed by a tongue-shaped, llexu- 

 ose, strong, parietal denticle; peristome reflected, 

 within thickened, its right termination with a large, 

 obtuse, very deeply-seated tooth (whose position is 

 marked on the exterior of the shell by a groove or 

 pit), the basal terminus furnished with a smaller, 

 transverse, submarginal denticle. Greater diam. 13, 

 lesser 11;^; height 6^ mill. 



Helix rugcli, SncTTLEwoRTU, Bern. Mittheil. 18.'i2, 



198.— Pfeiffer, Mon. Hel. Viv. Ill, 2GS.— Gould in Terr. Moll. Ill, 

 18.— W. G. BiNSEY, Terr. Moll. IV, GO, pi. Ixxviii, f. 15.— Bland, 

 Ann. N, Y. Lye. VII, 420. 



Isognomostoma rugeli, Teyon, Am. Jouru. Conch. Ill, 55, pi. ix, f. 8 (1S(J7). 



Tennessee, North Carolina. 



Helix ruyeli, enlarged. 



Fig. 218. 



Helix tridentata, Say. — Shell umbilicated, orbicularly-depresst-d, 

 with crowded rib-like strife, light horn or cliestnut-colored ; spire very 

 short ; whirls five and a half, rather convex, the last 

 scarcely deflected in front; aperture lunar, subtri- 

 angular ; peristome white, reflected, its outer contour 

 rounded, thickened within, its terminations converg- 

 ing, joined by a light deposition of callus bearing a 

 tongue-like, erect, entering tooth, both the right and 

 basal portions bearing on the inner margin a stout, 

 acute denticle. Greater diam. 16, lesser 14 ; height 

 8 mill. 



Helix tridentata, Sat, Nich. Encycl. pi. ii. f. 1 

 (1817, 1818, 1819) ; Binney's ed. G, pi. Ixx, f. 

 1. — E.\T0N, Zool. Text-Book, 193 (182G).— mixtri.hntata. 



9 Sept., 1888. 



