62 COLIMACEA. 



9. Helix cbenella, pi. VII, f. 6, 7. 



Helix crenella, Montagu, Test. Brit., p. 441 ; Amplexus cre- 

 nellus, Brown, Illust. Conch., 1st Ed., pi. 41, f. 78, 79; Helix 

 pulchella, var., Drapernaud, p. 112, pi. 7, f- 30, 31, 32; Helix 

 costata, MiiUer, Verm., p. 31, No. 233; Pfeiffer, I, p. 41, pi. 2, 

 f. 31 ; Gmelin, Linn. Syst. Nat., I, p. 3633, No. 67 ; Alten, 

 Erd-und Flussconchyl., S. 60, pi. 6, f. 1 1 ; Gartner, Conchyl. 

 der Wetterau, S. 26; Rossmassler, VII, p. 5, pi. 31, f. 439; 

 Fleming, Brit. An., p. 263 ; Helix pulchella, var., Alder, Mag. 

 Zool. and Bot., 11, p. 109; Forbes, Mai. Mon., p. 9; Turbo 

 helicinus, Lightfoot, Phil. Trans., 1776, pi. 3, f. 1 to 4 ; Helix 

 crenella. Brown, Illust. Conch., p. 45, pi. 14, f. 78, 79; lb.. 

 First Ed., pi. 41, f. 78, 79. 



Shell milk-white, subopaque ; spire depressed, consisting of 

 three well defined, rounded volutions, and terminating in an 

 acute apex, which is but little elevated above the body volu- 

 tion, and beautifully rounded ; its base provided with a large 

 and deep umbilicus, exposing in its cavity the inner sides of the 

 volutions of the spire ; aperture circular ; the outer and pillar 

 lips continuous, smooth, white, opaque, and reflected, but a 

 little separated on the columella; whole surface covered by 

 numerous, strong, regular, longitudinal, concentric ribs. Dia- 

 meter one-tenth of an inch. Some specimens have a yellowish- 

 brown epidermis. 



Some authors affirm that this species is always found in damp 

 situations, while the habitat of H. pulchella is constantly in dry 

 localities. We have met with both shells plentifully in Caro- 

 lina Park, near Edinburgh, and also at Portmarnock, Ireland. 

 In the former locality, however, we always met with the two 

 species in separate situations. 



This shell is as widely spread as the H. pulchella, both in 

 England and Ireland, and in the same kind of habitat. In the 

 North of Ireland, Mr. Thompson says this species is more 

 common on dry sea banks than the H. pulchella. Forbes has 

 found the H. crenella on walls in the Isle of Man, and I have 

 met with it in a similar locality, in the King's Park, at Edin- 

 burgh. I have likewise observed both specimens in damp 

 situations, but very rarely. 



