800 HELIX. 



to this family, and to differ principally from the Variety B in 

 having a much narrower umbilicus. 



INVOLVULUS. 8. Shell umbilicated, slightly keeled, 

 white, with the summit mucronated, and 

 the whirls convex and striated ; aperture 

 roundish, and the lip reflected. 



Helix Involvulus. Midler Verm. ii. p. 84. Gmelin, p. 

 3638. 



Inhabits 



Shell about eleven lines long, and thirteen broad ; it is nearly 

 allied to H. Oculus- Capri, from which it may be known by 

 having the base as far as the keel marked with very fine lon- 

 gitudinal striae, and the shell above this is also more strongly 

 striated transversely ; the outer-lip is reflected, but not so 

 broadly marginated as in H. Oculus-Capri ; all the speci- 

 mens which I have seen are wholly white, but MuUer men- 

 tions a Variety with a red band and spots. 



ALBELLA. 9. Shell umbilicatcd, flat above, and the 

 base gibbous ; aperture semi-heartshaped. 



Helix albella. Linncdus Si/st. Nat. p. 1242. 



Helix explanata. Muller rerm. ii. p. 26. 



Helix Planorbis marginatus. Chemnitz, ix. part 2. p. 84. 



1. 126. f. 1102. 

 Helix Rhenana. Gmelin, p. 3622. 

 Helix, No. 325. Schroeter Einl. ii. p. 270. 

 Helix Planorbis, Var. /3. Gmelin, p. 3617. 

 Helix umbilicaris. Olivi Adr. p. 177. 

 Planorbis umbilicatus margine interrupto. Schroeter Fluss. 



p. 244. t. 5. f. 31. 

 Lister Conch, t. 64. f. 62, and 1. 140. f. 46. Petiver Gaz. 



1. 17. f. 1. Gualter,t.3.f.N. 

 Variety/ ? With a reddish band in the middle of the whirls, and 

 the umbilicus small. 

 Helix albella. Chemnitz, ix. part 2. p. 87. t. 126. f. 1105 



and 1106. Gmelin, p. 3615. Schreibers Conch, i. p. 



291. 

 Junior. With three whirls, and a dotted band in the middle. 

 Helix maculata. Muller Verm. ii. p. 25. Gmelin, p. 



3615. 

 Inhabits rocks in Europe. Linnaus. France, Virginia, and 



Jamaica. Lister. Neighbourhood of Rome. Petiver. 

 SheU half, or sometimes three-quarters of an inch in diameter. 



