family helichxe — helix. 29 



Helix thyroidus. 



PLATE II. FIG. 8. A. B. Immature. —(STATE COLLECTION.) 



Cochlea umbilkata. Lister, Conch, pi. 91, fig. 91. 



Helix thyroidus. Sir, Nich. Encyc. Vol. 4. Id. Acad. Nat. Sc. Vol. 2, p. 161. 



H. id. Id. American Concliology, pi. 13, fig. 1. 



H. id. Ferussac, Histoire des Mollusques, pi. 49, A. fig. 4. 



H. thywidierme. Lamarck, An. sans vert. Ed. Brui. Vol. 3, p. 309. 



H. thyroidus. Gould, Invertebrata of Mass. p. 171. 



Description. Shell rounded, convex. Whorls convex, about five in number, with minute 

 parallel oblique striae ; the suture distinctly impressed. Aperture moderately large, lunate. 

 Lip broadly reflected, and partially covering the umbilicus. Pillar-lip in the adult with an 

 oblique tooth. Umbilicus exhibiting one volution, and sometimes entirely closed. 



Color. Epidermis yellowish brown. Animal granulated, and of a soiled yellow. 



Diameter, 0"5 -0-8. 



We have strongly marked varieties in this vicinity of a light chocolate-brown, with dis- 

 persed dark spots, and interrupted revolving lines; the pillar-lip smooth; diameter 0*8; 

 animal of a light amber-color. I have thought that it would be more instructive to give this 

 variety in the plate above referred to, than the typical form, which may be found in most of 

 our conchological works. 



This species is common in moist shady places, from New- York to Missouri. It is more 

 rare in the Eastern States. 



Helix alternata. 



PLATE U. FIG. 9. — (STATE COLLECTION.) 



Helix alternata. Say, Nich. Ency. Vol. 4, pi. 1, fig. 2. Id. Jour. Acad. Nat. Sc. Vol. 2, p. 101. 



H. scabra. Lamarck, An. sans verteb. Ed. Brui. Vol. 3, p. 292 



H. alternata. Gould, Invertebrata of Mass. p. 177. Adams, Am. Jour. Vol. 40, p. 273. 



Description. Somewhat depressed, slightly convex above. Whorls five or six, flattened, 

 and roughened above with lines of growth ; smooth beneath. In young specimens, there is a 

 prominent ridge between the upper and under surfaces. Lip simple, thin and brittle, and 

 regularly curved. Umbilicus wide and deep, exhibiting all the volutions. 



Color. Epidermis dusky. Shell light brown, alternating or varied with zigzag bars of 

 deep reddish brown, becoming smaller as they converge towards the umbilicus. These bars 

 are interrupted by a light colored revolving band. Lip within glossy and pearly. Animal: 

 Head and tentacles light slate ; back brown ; remainder of the upper surface brownish orange. 



Diameter of the shell, 0-8 - 1 -0. 



Common every where in ditches and moist places, and under the bark of decaying trees. 

 Its geographical limits southwardly and westwardly not known. It has been observed from 

 Maine to Maryland. As Deshayes has properly observed, the name imposed by Lamarck 

 must be expunged, that of Say having distinctly the priority. 



