418 helicidj:. 



Shell nearly globular ; whorls five, rounded ; suture distinct ; 



epidermis brownish, covered with numerous sharp, rigid hairs ; ap- 

 erture very narrow, almost closed by an elongated, lamelli- 



^'^^'' form tooth, situated on the pillar lip, and extending from 

 the centre of the Ijase nearly to the junction of the lip with 

 the outer whorl ; lip narrow, very much depressed and re- 

 flected against the body whorl, with a deep cleft or fissure 

 near the centre of the inner margin ; base convex ; umbili- 

 cus wholly closed. Greatest diameter, one third of an inch ; 



ordinary size less than one fourth of an inch diameter. 



Animal whitish, head and tentacula slate colored ; foot slender, 



semi-transparent, length less than twice the breadth of the shell ; 



cavity of the tentacula ajjparent when they are drawn in, l)y two 



dark lines, with a whiter space between. 



Found from New England to Kansas and Virginia. Also in the 



post-pleiocene beds of the Mississippi Valley. Nova Scotia ( Willis}. 

 This very peculiar snail is at once distinguished from every other 



New England species by the singular fissure on the inner edge of 



the lip. There is sometimes a minute, tooth-like process on the 



inner and upper part of the lip, which is visible only on looking into 



the aperture. Sometimes its hairy vesture covers it at every part ; 



at other times it is quite smooth. Dr. Binney has once or twice 



noticed a white band on the body whorl. 



Helix monodon. 



Fig. 113. 



Shell rather depressed, dusky horn color, hispid ; aperture semi-lunar ; lip white, 

 reflexed; with a single elongated tooth fixed obliquely to the pillar; umbilical 

 region excavated. 



Helix monodon, Eackett, Lin. Trans, xiii 42, pi. 5, fig. 2 (1822) ; ed. Chenu, 269, pi. 

 27, fig. 5. — Wood, Tndex, Suppl. pi. 7, fig. 15 (1828) ; ed. Hanley, 226, fig. 15. — 

 Binney, Best. Journ. Nat. Hist. iii. 360, pi. 10, fig. 1 (1840) ; Terr. Moll. ii. 147, 

 pi. 41, lower figures. — Gould, Inv. 174, fig. 113 (1841). — Adams, Vermont Moll. 

 159 (1842). — W. G. Binney, Terr. Moll. iv. 60. — De K.4Y, N Y. Moll. 35, part, 

 excl. syn., pi. 3, fig. 19 ; not fig. 21, a, b (1843). —MBf9. Gray, Fig. Moll. An. pi. 

 193, fig. 11, ex Bost. Journ. no descr. — Billings, Canadian Nat. ii. 100, fig. 6 

 (1857). — Pfeiffer, Mon. Hel. Viv. iv. 320. — Morse, Am. Nat. i. 151, figs. 12, 

 13 (1867). 



Helix convexn, Chemnitz, part (excl. syn. et tab. 66, figs. 24, 27), pi. 10, figs. 17, 18. — 

 Pfeiffer, Mon. Hel. Viv. iii. 268 (excl. (9 et y). — Deshayes, in Lam. viii. 112; 

 Encyc. Me'th. ii. 253 (1830) ; 3d ed. iii. .308; in Fer. 1. c. i. H4. — Reeve, Con. 

 Icon. No. 696 (18.52), excl. syn. ; No. 717 (1854). 



Helicodonta hirsuta, Ferussac, Tabl. Syst. 101, no dcscr. 



