HELIX. 



425 



— Mrs. Gray, Fig. of Moll. An. pi. 191, fig. 11, no dcscr. from Bost. Joiirn. — 

 Morse, Am. Nat. i. 99, figs. 6, 7 (1SG7). — Not of Tfeiffer, Mon. Ilel. Viv iii. 

 and iv. ; not of Chemnitz, ed. 2 (rotinerl). 



Shell imperforate, flattened, convex on the upper surface, convex 

 below ; epidermis yellowish horn color, immacu- 

 late ; spire depressed ; whorls five, with delicate, 

 parallel oblique strias ; suture distinct, not deeply 

 impressed ; aperture contracted by the peristome, 

 flattened towards the plane of the base ; peristome 

 thickened, white, broadly and abruptly reflected; 

 parietal wall with a prominent, white, tooth-like 

 process nearly parallel with the lower margin of 

 the aperture, not projecting towards the umbilicus; 

 base convex. Greater diameter twenty-three, les- 

 ser eighteen, height ten millimetres. 



From Maine to Virginia and to Ohio. It prefers 

 mountainous country. 



Readily distinguished from the allied species by the very angular 

 and broad reflection of the peristome. 



H. dentifera. 



Helix thyroides. 



Fig. 108. 



Shell convex, yellowish horn color ; whorls five, delicately wrinkled ; aperture 

 rounded; lip white, widely reflected; pillar with a single white tooth; umbilicus 

 partial. 



Helix thijroidtts. Say, Nich. Encyc. (Amer. cd.) 1817, 1818, 1819; Journ. Acad. i. 123 

 (1817); Amer. Conch. (18.31) No. 2, pi. 1,3; ed. Binnet, 33, pi. 13; ed. Chenu, 

 Bibl. 3, 22, pi. 3, fig. 3. — Eatox, Zool. T. B. 193 (1826). — Ferussac, Hist. pi. 

 49 a, fig. 4 ; pi. 50 a, fig. 6 ? — Deshayks, Encyc. Meth. ii. 230 (1830) ; in Lamarck, 

 An. sans Vert. viii. 114; 3d ed. iii. 309 ; in Fer. i. 209. — Bixxey, Bost. Jonrn. 

 Nat. Hist. i. 438, pi. 18 (1837) ; Terr. Moll. ii. 129, pi. 11. — Leidy, Terr. Moll. 

 U. S. i. 2.57, pi. 11, fig. 7-9 (18.51 ) anat. — De Kay, N. Y. Moll. 29, pi. 2, fig. 8.— 

 Gould, Inv. 171, fig. 108 (1841). —Adams, Vermont Moll. 1.59 (1842). — Mrs. 

 Gray', Fig. Moll. An. pi. 291, fig. 6, from Bost. Journ., no descr. 



Helix tlii/roid'S, Ffeiffer, Mon. Hel. Viv. i. 345; in Cfiemnitz, 2d ed. i. 331, pi. 58, 

 figs. 8, 9 (18.50). —Beeve, Con. Icon. No. 677. — W. G. Binney, Ter. Moll. iv. 53. 

 — Morse, Am. Nat. i. 98, fig. 3 (1867). 



Anchistoma tJujroidcx, H. and A. Adams, Gen. pi. 78, fig. 3, no descr. 



Mesodon thyroides, Tryon, Am. Journ. Conch, iii. 41, pi. 8, fig. 1 (1867). 



Shell rounded, convex, of a uniform yellowish-brown or russet 

 color ; whorls about five, convex, marked with delicate and parallel 

 lines of growth; suture distinct; aperture broad, semi-lunar, con- 



