34 
MOLLUSCA. 
Some of tliese have ribs pi’ojecting’ internally* * * § , and there aie 
others in which the last whorl is suddenly recurved, (in the adult,) 
assuming an irregular and plaited formf. 
ViTRiNA, Drap. — Helico-Limax, Feruss. 
The Vitringe are Helices with a very thin flattened shell, without 
an umbilicus; the aperture large, hut its margin not tumid; the 
body too large to be completely drawn into the shell ; the mantle has 
a double border:|;, the upper one, which is divided into several lobes, 
extends considerably beyond the shell, and being reflected over it, 
polishes it by friction. 
The known European species inhabit wet places, and are very 
small§. Hot climates produce larger ones. 
There are some species of Helix, in which the body can hardly 
enter the shell, although not furnished with this double border, which 
shovdd be approximated to them 1]. 
When the crescent of the aperture is higher than it is wide, a 
disposition which always obtains when the spire is oblong or elon- 
Sfated, it constitutes the 
Bulimus Terrestris, Briuj. 
Which requires a still further subdivision : 
Bulimus, Lam, 
Margin of the aperture tumid in the adult, but without denta 
tions. 
Hot climates produce large and beautiful species, some of which 
are remarkable for the volume of their ova, the shell of which is of a 
stony hardness ; and others for their left shell. 
Several moderate-sized or small species are found in France, 
one of which, the Helix decoUata, Gm.; Chemn., cxxvi, 1254, 
1257, bas the singular habit of successively fracturing the whorls 
of the summit of the spire. This is the example referred to, as 
a proof that the muscles of the animal can be detached from 
* Hel. sinuata ; — II. lucerna; — II. lychnuchus ; — H. cepa; — H. isognomostoma ; — 
H. sinuosa ; — H. punctata, &c. 
f Ilel. ringens, Chemn., IX, cix, 919, 920, the Axostoma of Lam., or Tomo- 
GERES, Montf. ; an analogous fossil shell is the Strophostoma, Deshayes. See, 
also, pi. V, vi, vii, viii, of Draparn., with the accompanying descriptions ; the works 
of Sturm and Pfeiffer on the German species, but particularly see the splendid folio 
of M. de F^russac on the “ Mollusques terrestres et fluviatiles.” 
+ Termed by M. de F^russac “ une curiasse ct un colirlier.” 
§ Hel. pellucida, Miill. and Geoff. ; Vitnna pellucida, Drap., VIII, 34 — 37p — 
tiie Helicarion, CLnoy and Gaym., Zool. de Freycin., pi. Ixvii, 1 ; Ftn-uss., pi. ix, 
f. 1—4. 
11 Hel. rufa and hrevipcs, Feruss., Drap., tTII, 20 — 33. 
