206 THE HAUNTS OF LIFE 



the shore, for the conditions of life are more 

 than half terrestrial when the tide is out. 



In his fine introduction to Zoology, called 

 Animal Life, Professor F. W. Gamble gives a 

 vivid picture of the four chief kinds of animal 

 locomotion. He takes the case of a man in a boat 

 on a river, who can make headway against the 

 current in four ways. ( i ) He may take a boat- 

 hook and, fastening it to the roots on the bank, 



FIG. 22. A JERBOA. 

 A leaping Biped belonging to the Rodent Order. 



pull himself forward. So does a star-fish pull 

 itself up a rock; so does a leech pull itself for- 

 ward when it fixes its mouth. This is the pulling 

 method. (2) He may take a pole, or an oar for 

 that matter, and, pressing it against the bed of 

 the stream, lever himself forward. So does 

 the beetle push its legs against the ground ; so 



