116 
HELICID^. 
middle of the lowest volution and continues round 
the base of the rest, not penetrating the aperture : 
this band is often faint, rarely wanting; aperture 
semielliptic, longer than wide, produced at the pillar 
side, with the margin slightly reflected and white, 
with a white internal rib. 
The young shells have a thin lip, with a slight 
white internal rib. 
It varies — 1. In colour, from dark chestnut to 
pale yellowish white, with only a few whiter specks. 
2. In the thickness of the shell, the thinner speci- 
mens being generally destitute of the band. 
3. In the presence or absence of the band. 
4. In the size, according to the locality. The 
small mountain variety has been called a species by 
the Swiss shell dealers. 
It is sometimes distorted — 1. by the whorls being 
reversed ; 2. the spire more or less elevated or 
depressed ; 3. very rarely the whorls are elevated 
and separated from one another. (See Ferus, Hist. 
t. 29. f. 1, 2, 3.) 
d. Shell subdiscoidal^ above flat^ beneath umbilicated ; 
broion, one-coloured ; mouth trigonal^ edge more or 
less toothed ; periostraca hispid^ with long hairs. 
(Trigonostoma Fitz.^ 
40 . 7. Helix obvoluta. Cheese Snail. — Shell or- 
biculate, flat umbilicated, bald, reddish brown; 
spire rather concave ; mouth triangular, edge 
slightly reflexed, with a small tooth on the in- 
side of the lip; lips reddish white, (t. 11. £ 
131.) 
