422 HELICID^. 



Helix tridentata. 



Fig. 115. 



Shell depressed, yellowish horn colored ; whorls obliquely wrinkled ; aperture 

 contracted, three-lobed, two teeth on the outer lip, and a curved one on the pil- 

 lar ; lip reflexed, white ; umbilicus deep. 



Helix tridentata, Say, Nicli. Encyc. pi. 2, %. 1 (1817, 1818, 1819) ; Binney's ed. 6, pi. 

 70, fig. 1. — Eaton, Zool. T. B. 193 (1826). — Ferussac, Tab. Syst. 38 ; Hist pi. 1, 

 fig. 3. — Wood, Index, Suppl. 21, pi. 7, fig. 2 (1828) ; ed. Hanley, 226, fig. 11. — 

 Deshayes, Encyc. Meth. ii. 213 (1830) ; in Lamarck, viii. 115; 3d cd. 309; in 

 Feu. 1. c. i. 72. — Eisney, Best. Joiirn. Nat. Hist. iii. 382, pi. 17 (1840), part; in 

 Terr. Moll. ii. 183, pi. 27. —Adams, Vermont Moll, 160 (1842). — Gould, Inv. 173, 

 fig. 115 (1841). — Pfeiffer, Mon. Hel. Viv. i. 412; in Chemnitz, 2d ed. i. 84, pi. 

 10, figs. 7, 8. — PoTiEz et Michaud, Gul. i. 114. — Mrs. Gray, Fig. Moll. An. 

 pi. 291, fig. 3 (ex Best. Journ. no descr.). —Reeve, Con. Icon. No. 690 (1852). — 

 "W. G. Binney, Terr. Moll. iv. 70. — Bland, Ann. N. Y. Lye. vii. 423. — Morse, 

 Am. Nat. i. 150, figs. 8, 9 (1867). 



Triodopsis lunula, Kafinesque, En. and Ace. 3; ed. Binney and Tryon, 68. 



Triodopsis tridentata, Tryon, Am. Journ. Conch, iii. 50, pi. 9, figs. 6, 13 (1867). 

 Lister, pi. 92, fig. 92. 



Shell flattened, slightly convex above and below, yellowish horn 

 colored ; whorls four and a half to six, slightly convex, crossed 

 obliquely with numerous fine and regular lines of 

 Fi.£:-680. growth; aperture contracted, rendered trilobate by 



the presence of two small, pointed teeth on the outer 

 lip ; opposite the middle lobe, placed obliquely on the 

 inner lip, is a thin, somewhat curved, white tooth ; 

 lip broad, white, partially reflected, with a constric- 

 tion behind it ; umbilicus not large, deep, and partly 

 covered by the extremity of the reflected lip. Diam- 

 „ . . , , , eter about half an inch. 



H. tridentata. 



Animal dark bluish-slate color, deeper on the head, 

 back, and tentacula ; foot nearly twice as long as the diameter of 

 the shell. 



This well-marked species is not found near the sea-coast, and but 

 rarely in the forests, at the western part of this State. From Can- 

 ada through all Eastern North America. 



It varies much in size and other respects, in diflerent localities. 

 Specimens from this region have the lip narrow, the teeth small, 

 the aperture but slightly contracted, the spire depressed, and are of 

 a medium size. In Ohio it is larger, in Florida much smaller. 



Dr. Binney regards the H. fallax of Say as a variety of this spe- 

 cies, in which the spire is more elevated, and the parts about the 



