28 
SHELL GALLERY. 
The eggs of Land-Snails vary in texture, size, and in numbers : 
they are usually white, but in some instances yellow and pale green. 
Those of some of the large South- American forms are as hard as 
that of a hen, and more than an inch in length (Case 120). 
Slugs (Cases 106, 107) are very like Snails without external shells ; 
most of them, however, possess a small internal shelly plate, or a few 
Case 136. 
British Land-Snail (Helix pomatia). 
a, eye-bearing tentacles ("horns"); b, lower or smaller tentacles. 
calcareous granules hidden beneath the skin of the back. Some have 
a large slime-pore at the end of the foot, and others are slightly 
phosphorescent. Like the Snails, they are fond 
of damp localities, and at times become great 
pests to farmers in devouring the young shoots 
of the growing corn. Testacella, which is found 
in this country, differs from the Slugs in having 
an external shell at the tail-end of the foot. 
It is not slimy, and lives under ground, feeding 
upon earthworms. 
Class III.— SCAPHOPODA * 
The "Tooth-shells" (DentaUidce) form a 
distinct group, the shells of which are very 
unlike those of any other mollusc, but closely 
resembling the shelly tubes constructed by 
certain kinds of marine worms. The Dentalia 
* From the Greek : scaphe, a small boat, and pons, 
a foot— the foot of some Scaphopods being somewhat 
pointed like the prow of a vessel. 
British Tooth-shell. 
(Dentalium tarentinum). 
a. The shell, b. The an- 
imal, removed from 
its shell ; /, the foot. 
