51 



on the centre of the foot, and covered with a tfhin mantle, 

 with a thickened edge, which is itself covered with an ex- 

 ternal spiral shell, which has a plaited pillar in all its ages." 



CARYCHIUM. 



GENERIC CHARACTER: The shell spiral, thin, conic 

 ovate ; mouth oblong, longitudinal, two or three toothed, 

 compressed, rather oblique, rounder at each end ; peris- 

 tome interrupted, thickened, and rather refiexed. 



C. MINIMUM, Helix Carychium. Turt. Lin. Turbo C. 

 Mont. Test. Brit. vol. 2, p. 339. C. M. Flem. Brit. An., 

 p. 271. Gray's Turt., p. 221, fig. , p. 219. Not un- 

 common. 



CYCLOSTOMA. 

 GENERIC CHARACTER : Shape of the shell variable; 

 whorls of the spire cylindrical; aperture round, regular ; 

 the margins circularly united, or reflected by age. An 

 operculum. 



Mr. Gray constituted this a family under the name of 

 Cyclostomidas, His generic character of Cyclostoma is : 

 shell ovate, spiral; mouth simple, united all round; oper- 

 culum of a few flat whorls, with a simple shelly internal 

 coat; the foot divided into two parts by a longitudinal 

 central groove. 



C. ELEGANS. Turbo Tumidus. Turt. Lin. Pen. Brit. 

 Zo., vol. 4, pi. 82, fig. 110, T. Elegans. Mont. Test. 

 Brit., vol. 2, p. 342. C. E. Fiem. Brit. An., p. 257. 

 Gray's Turt., p. 275, and fig. 1, 2, 3, p. 273, and pi. 7, 

 fig. 75. I have only obtained a specimen, by gift, from 

 the west of the county. 



LIMNJEANA. 

 The shell spiral, the outer surface mostly smooth ; right 

 margin of the aperture acute, and not reflected. 



Mr. Gray denominates the family Limnaeadae; and observes 

 that the forms of the shells vary much in dilferent genera, 

 "in shape and form;" but the group is natural, from the 

 similarity of the animals. 



LIMNJEUS. 



GENERIC CHARACTER: The shell ovate, thin, dex- 

 tral, transparent, spiral ; mouth ovate, with a single, 

 oblique plait on the middle of the column, running into 

 the axis: Gray; who observes, this genus is known from 

 Amphipeplea and Physa by the inner lip not being ex- 

 tended over the body whorl of the shell; and from Ap- 

 lexus by the shell being dextral and having the pillar 

 plait. 



* L. PEREGER. Helix Peregra. Turt. Lin. H. Putris. 

 Pen. Brit. Zo., vol. 4, pi. 86, fig. 137. H. P. Mont. Test. 



