410 THE ANIMALS AND MAN 



less limited to certain parts of the region. Attempt may 

 next be made to find out why. Are there barriers? If 

 so, of what nature ? They cannot well be barriers of temper- 

 ature or climate, unless a mountain is included in the region, 

 but may be concerned with food, suitable hiding-places, 

 proximity to man, necessity of water for breeding in, etc. 

 This is a study, all of which must be made in the field, 

 and where much ingenuity in observing and reasoning 

 must be used. 



For a reference-book on the subject of animal distribution see Heil- 

 prin's "Distribution of Animals," or Beddard's "Zoo-geography." 



