98 HELICID^. 



Shell about one quarter of an inch in diameter ; 

 it very much resembles Z. luc.ida, 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 strife 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. ZoNlTES 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. St/st. 99. — Polita 

 crystallina. Held. Tsis, 1837, 916. — Helicella crystallina. 

 Beck, Ind. 7. — • ? Helix hydatina. Hossin. Icon. i'. 529. — 

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

 Helix crystallina. Milller, Verm. 223.; Drap. p. 118. t. 8. 

 f. 13 — 18.; Gray, Med. Rep. 1821, 2.39.; Alder, Cat. 108.; 

 I'urton, 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 Avhite ; neck long ; tentacles dark, 

 long. Very active. 



Shell, when enclosing the animal, very shining 

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



