HELIX. 



425 



— Mrs. Gray, Fig. of Moll. An. pi. 191, {\ff. 11, no dcscr. from Bost. Jo urn. — 

 Morse, Am. Nat. i. 99, figs. 6, 7 (1867). — Not of Pfeiffek, Mon. Ilel. Viv iii. 

 and iv. ; not of Chemnitz, ed. 2 [roemeri). 



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

 below ; epidermis yellowish horn color, immacu- 

 late ; spire depressed; whorls five, with delicate, 

 parallel oblique strice ; 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 ]Maiiie to Virginia and to Oliio. It prefers 

 mountainous country. 



Readily distinguished from the allied species by the very angular 

 and broad reflection of the peristome. 



//. 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. 



IleUx llu/roidiis, Say, Nich. Encyc. (Amer. cd.) 1817, 1818, 1819; Jonrn. Acad. i. 12.3 

 (1817); Amer. Conch. (1831) No. 2, pi. 13; ed. Binney, 33, pi. 13; ed. Chenu, 

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

 49 a, fig. 4 ; pi. 50 a, fig. 6 ? — Deshayes, Encyc. Me'th. ii. 230 (1830) ; in Lamarck, 

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

 Nat. Hist. i. 488, pi. 18 (1837); Terr. Moll. ii. 129, pi. 11. — Leidy, Terr. Moll. 

 U. S. i. 2.57, pi. 11, fig. 7-9 (1851 ) anat. — De Kay, N. Y. Moll. 29, pi. 2, fig. 8.— 

 Gould, Inv. 171, fig. 108 (1841). —Adams, Vermont Moll. 159 (1842). — Mrs. 

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



Helix ihyroid's, Pfeiffer, Mon. Hel. Viv. i. 345; in Chemnitz, 2d ed. i. 331, pi. 58, 

 figs. 8, 9 (1850). —Reeve, Con. Icon. No. 677. — W. G. Binney, Ter. Moll. iv. 53. 

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



Anchistoma tJu/roidcfi, H. and A. Adams, Gen. ])1. 78, fig. 3, no descr. 



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



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

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

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



