90 
HELICIDJE. 
Helix ; for while their edge teeth show no appear- 
ance of bifurcation, the heel to the apex may pos- 
sibly be looked upon as an approach toward it. 
Their sagittate central tooth corresponds with that of 
Vitrina ; and a similarly shaped central tubercle in 
Helix fulva connects them with the true Helices^ 
which have a simple aculeate tubercle. 
The jaw is like those of Limax and FzYrzTza, broad, 
smooth, with a central rostrum. 
The animal can entirely withdraw itself into the 
shell ; and this genus is at once known from the 
Helix by the thinness and generally polished state 
of the shell, and also by its being depressed and 
destitute of any internal rib round the edge of the 
mouth. 
It is intermediate between the Helices and the 
foreign genera Stenopus and Nanina of the family 
Arionidce, The animal also resembles the latter in 
some respects, but wants the gland on the end of the 
foot. According to M. Moquin Tandon, there is a 
small lono;itudinal slit at the end of the tail of 
Zonites nitidiis. It is very probable that other 
peculiar characters will be found when the animals 
of the different species of Helicidce have been de- 
scribed and compared together, as Mr. Nunneley has 
so excellently well done with the species of slugs. 
a. Shell depressed^ yellowish; luhorls moderately en- 
larging ; umbilicus large. (Aplostoma.) 
25 . 1. TAO^iT^^alliarius. Garlic Snail. — Shell nearly 
flat, slightly globular, thin, transparent, horn- 
coloured, very shining, nearly smooth ; whorls 
