1905.] 



Slugs and Snails. 



595 



The common field slugs are practically omnivorous, but others 

 prefer certain kinds of food, though they will devour almost 

 anything under stress of circumstances. Unlike a snail, a 

 slug has no external shell, except in one genus ( Testacelld) ; the 

 shell is present, however, as a small flat plate, sometimes almost 

 only a mass of granules, hidden just under the skin. ..Their soft 



^S/^Y passed 



£ fit doJL^A 



The 



lie ex- 



, c. Shells 

 jpiratory 

 idl (z)j 



in the 

 l long, 

 Dvided 



witn transverse rows or m<&ci^ ... range - 



ment in different mollusca. It is by means of this structure, 



EEE2 



