98 HELICID.E. 



Shell about one quarter of an inch in diameter ; 

 it very much resembles Z. lucida, but may be dis- 

 tinguished from it by its greater convexity both 

 above and below, and by its peculiarly large umbili- 

 cus ; the whorls are also rather more convex and 

 more closely set, and the outer whorl is not so large 

 in proportion to the rest; the striae are rather 

 stronger, the animal lighter coloured, and it fre- 

 quents a different situation. The shell varies in 

 being paler. 



b. Shell depressed, diaphanous; whorls enlarging 

 very gradually ; axis perforated. (Discella.) 



32. 8. ZONITES crystallinus. Crystalline Snail. 

 Shell flat, glossy, of a greenish-crystalline trans- 

 parency, with six very gradually increasing vo- 

 lutions ; aperture semi-lunate ; umbilicus small, 

 (t 4. f. 42.) 



Helix eburna. Hart. N. alp. i. 234. Helix cristallina. Ferus. 



Prod. n. 223. Discus crystallinus. Fitz. Syst. 99. Polita 



crystalline Held. Jsis, 1837, 916. Helicella crystallina. 



Beck, hid. 7. ? Helix hydatina. Rossm. Icon. f. 529. 



Helix vitrea. Brown, Edinb. Jour. i. t. 1. f. 12, 13, 14. 



Helix crystallina. Midler, Verm. 293. ; Drop. p. 118. t. 8. 



f. 13 18.; Gray, Med. Rep. 1821, 239.; Alder, Cat. 108.; 



Turton, Man. ed. 1. 58. f. 42.; Jeffreys, Linn. Trans, xiii. 



341. 511.; Pfeiffer, Helic. i. 59. Zonites crystallinus. 



Leach, Moll. Syn. 76. ; Gray, Man. 176. t. 4. f. 42.; Forbes 



and Hanley, B. M. iv. 41. t. 122. f. 1, 2. 

 Var. Helix hyalina. Ferus. Tab. Moll. 224. ? ; Alder, Cat. 108. 



In wet meadows, among moss and leaves. ( Gray, 

 1821.) 



Animal milky white ; neck long ; tentacles dark, 

 long. Very active. 



Shell, when enclosing the animal, very shining 

 white, fulvous on the spire, hardly the eighth of an 



