98 
HELICID^, 
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 strise 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. Fefms. 
Prod, n.223. — Discus crystallinus. Fitz. Syst. 99. — Polita 
crystallina. Held. Isis.^ 1837, 916. — Helicella crystallina. 
Beck.^ Ind. 7. — ? Helix hydatina. Rossm. Icon. f. 529. — ■ 
Helix vitrea. Brown., Edinh. Jour. i. t. 1. f. 12, 13, 14. — 
Helix crystallina. Muller., Verm. 223.; Drap. p. 118. t. 8. |, 
f. 13 — 18.; Gray, Med. Rep. 1821, 239.; Alder, Cat. 108.; 
Turton, Man, ed. 1. 58. f. 42. ; Jeffreys, Linn. T?^ans. 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. 
Yar. Helix hyalina. Ferus. Tab. Moll. 224. ? ; Alder, Cat. 108. 
In wet meadows, among moss and leaves. {Gray^ 
1821.) i 
Animal milky white ; neck long ; tentacles dark, | 
long. Very active. 
Shell, when enclosing the animal, very shining I 
white, fulvous on the spire, hardly the eighth of an i 
