ZONITES, 
93 
especially about the umbilicus, which is large and 
very deep ; aperture oblong crescent-shaped, com- 
pressed, oblique, as long as it is wide, 
Mr. Alder observes that continental specimens of 
this shell are larger, and rather more open in the 
umbilicus, than British ones, which induced M. de 
Ferussac to think that they might be distinct. The 
same remark is applicable to Helix nitidula ; but in 
both cases he thinks it amounts to nothing more than 
a variety. H, nitens (Fer. Tab. Moll.) is only the 
English variety of the species in a small state. 
H nitens of Michaud, if we may judge from the 
figures, is H, nitidula Drap. Mr. Alder suspects 
Michaud’s H, nitidula is, like that of Pfeiffer, the 
H, nitidula var. ^ of Drap., which is his H. radia’- 
tula. 
27. 3. ZoNiTES purus. Delicate Snail. ~ Shell de- 
pressed, rather shining, transparent white, 
slightly striated or wrinkled, with four shining 
whorls set diagonally ; under side more flattish 
than the upper, and without any appearance of 
opacity ; umbilicus rather large, (t. 4. f. 43.) 
Helix crystallina. Flem. B. A. 262. (?)— Helix viridula. Menke^ 
Syn. 127. — Helix lenticula. Held. Isis, 1837, 304. — Polita 
nitidosa and P. clara. Held. Isis, 1837, 916. — Helicellaniti- 
dosa. Beck, Ind. f. — Plelix electrina. Goidd, Boston Jour. 
N. H. iii. 423. t. 22. f. 2, — Helix pura. Alder, Cat. 12. n. 
46.; Mag. Zool. and Bat. ii. 108.; Turton, Man. ed. 1. 59. 
(not the figure). — Helix nitidula var. (3. Drap. Moll. 117. 
t. 8. f. 21, 22.; Jeffreys, Linn. Trans, xiii. 511. — Helix Alderi. 
Bean, MSS., Brit. Mus. — Zonites purus. Gray, Man. 
171. t. 4. f. 43.; Forbes and Hanley, B. M. iv. 27. t. 221. f. 
5, 6. — Z. (Aplostoma) purus. Moq. Tandon, Moll. Franc. 
ii. 87. t. 9. f. 22. 25. 
