132 INTRODUCTION TO ZOOLOGY CHAP. 



it smooths over the walls. The winter sleep continues 

 usually until April. 



The eggs are the size of small peas, and have much the 

 colour and consistency of mistletoe berries. They are laid in 

 June, in a hollow in the earth. The young hatch in from 

 21 to 45 days and make their first meal off their egg-shells. 



M. Gaspard has experimented to test the sight of these 

 snails, and believes that they are quite blind, and that the 

 so-called " eyes " are only touch organs. 1 



Other Common Genera of Land Snails. 



Bulimus. The shell in this genus is oblong, with the 

 whorls drawn out into a long spire and the lip usually 

 reflected. Frequent on open downs 

 P. near the sea-coast ; very similar to Helix, 



except in relative length of spire. Its 

 generic name seems to bear reference to 

 fs/7fe its insatiable appetite, for it means " the 



Fio. 86. -B, 



montanus (nat. size) ; P, P u p a (the Chrysalis Snail). Small 

 Pupa cylindracea (en- gregarious forms found in moss or 

 larged, but with natural crevices in wa ll s or amO ngst roots of 

 size shown below). ... ,. . . . <? __ 



grasses ; shell cylindrical, spirally coiled, 



the last whorl only slightly, if any, bigger than the preceding 

 one ; the tip of the spire forms a sharp point. The mouth 

 of the shell is bordered with one or more teeth. 



Vertigo. A very small form, like Pupa, but with only two 

 tentacles, the lower front pair being absent ; shell in some 

 species sinistral and only -^ to 3 V inch in length. 



Clausilia (the Door-shell Snail). Some species common on 

 bark of tree, and under stones. Shell sinistral, with a long 

 pointed spire. The mouth of the shell is closed by a clau- 

 silium, a small white convex plate attached by a somewhat 

 cartilaginous, spirally-twisted, elastic foot-stalk, to the colu- 

 mella in the penultimate whorl. When the animal emerges 

 from its shell, the clausilium is pressed to one side out of 

 the way, but on the snail retiring again, it springs back 

 into position over the mouth of the shell. This curious little 



1 M. Gaspard in Annales des Sciences Nat. ; Professor Bell in vol. i. of 

 Zoological Journal. 



