Yerkes, space Perception of Tortoises. 



21 



TABLE II. 

 Reactions to Spatial Conditions of 



Chrysemys picta. 



Nanemys guttata. 



Terrapene Carolina. 



those which are land inhabiting ; (2) Total inhibition of the re- 

 action, i. e., failure to crawl over the edge of the board in the 

 60 minutes, appears at a much less height for the land species 

 than for the water-land and water forms. 



This quantitative expression of the amount of hesitation 

 exhibited by different species of tortoises under the same spatial 

 conditions clearly indicates a close relation between the de- 

 mands of the natural environment of the species, so far as spa- 



