110 NEW ZEALAND NATURE-STUDY BOOK 
tip of each of the upper horns. As the horns are retractile 
the eye can at any time be withdrawn from danger. 
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Fig. 71.—Section of Horn, showing Eye. 
A, Hye extended. B, Eye withdrawn. 
The lower surface of the body is known as the foot—it 
is strong and muscular, and on it the animal crawls along. 
The food of the Snail consists of young tender leaves ; these 
it is able to strip off the plants by means of its tongue, 
which is furnished with rough tooth-like projections. Its 
mouth is situated below the smaller pair of horns. | 
The Snail is a land molluse and an air-breather. The 
mantle fold under the shell encloses a lung cavity in the 
walls of which are numer- 
ous blood vessels. The 
opening leading to the 
lung cavity and known as 
the respiratory pore, 
is placed on the right side. 
aS During the winter months 
Fig. 72.—Section of Snail’s Head. the Snail remains in a 
torpid condition under 
stones and logs or along the bottom of fences in places of 
shelter. 
The Slugs which are so plentiful and destructive in our 
gardens are almost identical in structure—unlike the Snail, 
however, they do not possess tentacles or horns, and the 
shell is not visible, being hidden in a fold of the mantle. 
