412 helicidj:. 



Shell discoidal, globose, or conoid, aperture transverse, oblique, 

 lunate, or rounded, margins distinct. 



Jaw arcuate, vertically ribbed, margins crenulated. 



Lingual membrane broad, teeth numerous, centrals tricuspid, lat- 

 erals bicuspid, uncini denticulated or serrated, centrals and laterals 

 sometimes simply conical with an acute tip. 



Helix alternata. 



Fig. 114. 



Shell orbicular, depressed, fawn colored, barred with oblique, zigzag lines of 

 dusky ; whorls five or six, with prominent wrinkles at the lines of growth ; lip 

 simple ; umbilicus large and deep. 



Helix alternata, Say, Nich. Encyc. iv. pi. 1, fig. 2, 1817, 1818, 1819 ; Journ. Acad. ii. 161, 

 1821 ; Binnky's ed. 6, 21, pi. 69, fig. 2. — Eaton, Zool. Text Book, 19-3 (1826). — 

 BiNNEY, Best. Journ. Nat. Hist. iii. 428, pi. 25 (1840) ; Terr. Moll. ii. 212, pi. 24. 



— Gould, Inv. 177, fig. 114 (1841). — Leidy, Terr. Moll. U. S. i. 2.5.3, pi. 7, figs. 

 2-5 (1851), anat. — De Kay, N. Y. Moll. 29, pi. 2, fig. 9 (1843). — Adams, Ver- 

 mont Moll. 162, figure (1842). — Ferussac, Tab. Syst. 44; Hist. pi. 79, figs. 8, 9, 

 10. — PoTiEZ and Micuaud, Galerie, 104. — Chemnitz, i. 2d ed. 181, t. 24, figs. 17, 

 18. — Peeiffer, Mon. Hel. Viv. i. 102. — Deshayes, in Fer. Hist. i. 89. — Reeve, 

 Con. Icon. 670 (1852). —Billings, Canad. Nat. ii. 99, figs. 4, 5 (1857). — W. G. 

 BiNNEY, Terr. Moll. iv. 98. — Bland, Ann. N. Y. Lye. vii. —Morse, Am. Nat. 

 i. 187, figs. 17, 18 (1867). 



Angulapira alternata, Morse, Journ. Portl. Soc. i. 11, fig. 15; pi. 4, fig. 16 (1864). — Try- 

 on, Am. Journ. Conch, ii. 261, pi. 4, fig. 47 (1866). 



Helix scabra, Lamarck, An. sans Vert. vi. part 2, 88. — Deshayes, Encyc. Me'th. ii. 

 219 (18.30) ; in Lam. viii. 66; 3d ed. iii. 292. — Chenu, 111. pi. 6, fig. 11. 



Helix infecta, Parreys MS. — Pfeiffer, Mai. Bl. 1857, 86 ; Mon. Hel. Viv. iv. 91, non 

 Keeve. 



Helix strornvflodes, Pfeiffer, Proc. Zool. Soc. 1854, 53 ; Mon. Hel. Viv. iv. 91. — Reeve, 

 Con. Icon. 1296 (18.54).— Vide W. G. Binney, Terr. Moll. iv. pi. 77, fig. 8. 



Helix mordax, Siiuttleworth, Bern. Mitt. 1852, 195. — Gould, in Terr. Moll. iii. 19. 



— W. G. Binney, Terr. Moll. iv. 99. — Pfeiffer, Mon. Hel. Viv. iii. 635. — 

 Bland, Ann. N. Y. Lye. vii. (and va.v.ferf/uso7ii). 



Helix diihiu, Sheppard, Tr. Lit. Hist. Soc. Quebec, i. 194. — McCullocii, (where?) 

 teste Binney, Terr. Moll. i. 192. 



Shell orbicular, depressed, slightly convex above and below ; gen- 

 eral tint a light fawn color, which, on the upper surface, alternates 

 in about equal proportions, with oblique, zigzag bars of dark-brown ; 

 these bars grow narrower and lighter on the lower surface as they 

 converge to the umbilicus ; they are generally interrupted by a light 

 colored zone which issues from the middle of the inner margin of 

 the aperture ; whorls five to six, flattened above, cons])icuously 

 plaited at the lines of growth so as to produce a rough surface 



