46 



HELIX. 

 GENERIC CHARACTER: The shell orbicular, convex 



or conoida! ; sometimes globular, the spire rather elevated ; 



aperture entire, transverse, very oblique, contiguous to the 



axis of the shell ; the margins disunited by the projection 



of the penultimate whorl. 



Helix is distinguished from Pupa by the general form of 

 the shell, which is never cylindrical, and by the borders of 

 the aperture being disunited ; from Bulimus by the aperture 

 being rather transverse than longitudinal, and its plane very 

 oblique, and almost perpendicular to the axis of the spire; 

 and from Planorbis by the left margin of the aperture being 

 contiguous to the axis of the shell, whereas in that genus it 

 is very remote from it. The right margin, in the adult Helix, 

 is reflected outwards, contrary to what occurs in aquatic 

 shells. Helix is readily known by the projection of the 

 penultimate whorl into the aperture. Journal of Science, 

 vol. 15, p. 237. 



Mr. Gray denominates the family Helicidas, and charac- 

 terizes the genus Helix : shell globose or depressed; mouth 

 semilunar ; peristome rather thickened and reflected. 

 *H.ASPERSA. H. Hortensis. Turt. Lin. Pen. Brit. 



Zo., vol. 4, pi. 84, fig. 129. H. A. Mont. Test. Brit., 



vol. 2, p. 407. Flem. Brit. An., p. 263. Gray's Turt, 



p. 128, pi. 4, fig. 35. Snail. Common. 



* H. HORTENSIS. Mont. Test. Brit., vol. 2, p. 412. 

 Flem. Brit. An., p. 264. Gray's Turt., p. 130, pi. 3, 

 fig. 24. Common. 



* H. NEMORALIS. Pen. Brit. Zo., vol. 4, p. 137. Stew. 

 Elem., vol. 2, p. 414. Mont. Test. Brit., vol. 2, p. 411. 

 Flem. Brit. An., p. 264. Gray'a Turt., p. 132, pi. 3, 

 fig. 23. Common. 



* H. PISANA. H. Zonaria. Pen. Brit. Zo., vol. 4, pi. 85, 

 fig. 133. H. Cingenda. Mont. Test. Brit., vol. 2, p. 418. 

 H. P. Fern. Brit. An., p. 259. Gray's Turt., p. 158, 

 pi. 4, fig. 30. The only place in the west of England in 

 which this shell is found, is at St. Ives, chiefly about the 

 promontory north of the town ; where it exists in pro- 

 fusion. A sandy soil is perhaps necessary to its existence. 



* H. RUFESCENS. Mont. Test. Brit., vol. 2, p. 420. 

 Flem. Brit. An., p. 261. Gray's Turt., p. 156, pi. 3, 

 fig. 28. Common. 



* H. HISPIDA. Mont. Test. Brit,, vol. 2, p. 423, Flem. 

 Brit. An., p. 261. Gray's Tart., p. 154, pi, 4, fig. 41. 

 This species seems to be thinly scattered. Montagu found 

 it in some plenty near Penryn; and I have obtained it in 

 my own neighbourhood. 



