66 MOLLUSCA. 
snails, interesting from the great variations of the shell. 
The eggs are laid in capsules (Fig. 69), in a jelly-like 
mass, late in the spring. In the winter they hibernate in 
thé mud; 320 species are known. 
Land-Snails (Hedicide).—Three thousand three hun- 
dred and thirty-two species of these are known in various 
Fic. 70.—Air-breathing gasteropods: Snails and slugs. A, garden snail 
(Helix) ; B, B, slug Testace//a—one disappearing into the ground, and 
only the tail showing ; C, the great gray slug (Lzmax); s, shell; ¢, ten- 
tacles ; e, eyes; 4, breathing-hole. 
parts of the world. They are easily kept in a fernery and 
their habits watched. Many of the snails (Fig. 70, A) de- 
posit large white or yellow eggs with a calcareous covering. 
The Bulimus (Fig. 71), an ally, rolls two leaves together 
and fastens the eggs between. Some of their eggs are as 
large as a pigeon’s, 
