2O 



THE ANIMAL KINGDOM. 



not, however, think that the shell of a snail or mussel is 

 in any way like the case in which the articulated animals 

 live. You have been told that in the crab and similar 

 animals this covering is the external skeleton, but in the 

 Mollusks it has no connection with the body of the animal 



Example of Mollusks or Soft-bodied Animals. 



THE SNAIL. 



it is merely a hcuse, which it carries on its back, and 

 into which it can withdraw itself. 



Further, you know the snail which you see in the 

 garden has a shell ; whilst the slug, which is nearly the 

 same in every respect, has not ; and there are others 

 which have a mere remnant of a shell, which seems just 

 left to remind them that some of their relations have com- 

 fortable houses to dwell in ; and thus you will see that 

 the hard casing is not always possessed by the Mollusks. 



