CHAPTER VIII 



SNAILS AND SLUGS 



THE largest species of our common shell-bearing Gastropod 

 molluscs is the garden-snail, Helix aspersa. The animal is to be 

 found hiding in the crevices of stone walls, heaps of stones, etc. ; 

 or in warm damp weather crawling among vegetation and doing 

 considerable damage to low-growing foliage. The shell is of a 

 brown colour crossed by transverse darker patches ; its " lip " 

 is nearly white. It is spirally coiled, and exhibits numerous 

 fine " lines of growth " which run parallel with the margin of 



FIG. 30. Garden snail, a, suture ; , lines of growth ; c t eye ; d t mouth ; 

 e, pedal gland ; f, genital opening ; g, foot ; h t pulmonary opening. 



the shell (" lip "), and indicate the successive positions occupied 

 by the free edge during growth. The increase of one year can 

 usually be determined by the interval between more pronounced 

 lines of growth, and sometimes by slight differences of colour. 

 The length of life probably never exceeds five years. When 

 growth does take place it is very rapid, as much as a centimetre 

 of shell being known to be added in five days. The fresh portion 



is very thin and flexible for some days while consisting only of 



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