HELIX. 213 



Helix altcrnata, Adams, Vermont Mollusca, 12, and figure. 



Fekussac, Tab. Syst. 44 ; Hist. pi. 79, f. 8, 9. 10. 



PoTiEZ and Mich,, Galerie, 104. 



Chemnitz, 2 ed. tab. 24, f. 17, 18. 



Pfeiffer, Monog. Helic. Viv. I. 102. 

 Helix scahra, Lamarck, Anim. sans Vert. VI. 288. 



Deshayes, Encyc. Metli. II. 219; in Lamarck, VIII, 66. 



De Kay, New York Report, 31 ; Nat. Hist. pi. 2, f. 9. 

 Patula alternata, Held, in Isis, 1S37, p. 916. 

 Euryomphala alternata, Beck, Index Meth. 8. 



DESCRIPTION. 



Animal. Head and tentaculse light slate-color, back 

 brown, remainder of upper surface brownish-orange, eyes 

 black, base of foot grayish- white, collar saffron. Supe- 

 rior tentaculse one-third of an inch long, blackish at the 

 extremities. Foot not much excee<iing in length the 

 diameter of the shell, and terminating in a broad, obtuse, 

 and flat extremity. A light marginal line runs along 

 the edge of the foot from the head to the posterior part, 

 those of the two sides meeting in an acute angle. 



Variety. Head and neck blackish brown, tentacles 

 blackish, foot brownish, base dirty white. In a single 

 instance the whole animal was entirely black. 



SuELL. Flattened-convex ; epidermis variegated 

 with rufous bars and spots, arranged obliquely across 

 the whorls ; whorls in full-grown individuals six, striated 

 obliquely with raised, acute, equidistant, curved lines, 

 which give a roughness to the surface ; aperture, viewed 

 perpendicularly to its plane, nearly circular ; lip simple, 

 thin, brittle, within shming, sometimes pearly ; umbilicus 

 VOL. II. 54 



