24 Jo2ii7ial of Comparative Neurology and Psychology. 



will leave the board if given plenty of time. This species is 

 more careful than the others in approaching the edge, and it 

 cranes the neck over even more frequently than does C. picta. 

 The inhibition of impulses frequently appears as in case of A'. 

 guttata. Unlike the other species, T. Carolina notices the spatial 

 relations from its position in the middle of the board, for when 

 1 80 cm. above the net an individual is frequently afraid to move, 

 and will remain for a long time just where the experimenter has 

 placed it. 



This study of the reactions to space of the three species of 

 tortoises already considered was supplemented by observations 

 of the behavior of several other species at the heights of 30 and 

 1 80 cm. In Table III, a summary statement of the results is 

 presented. ^ 



Without knowledge of the name of the species, but solely 

 on the basis of the results of the experiments, I classified the 

 species under the three categories Water, Land-Water, and 

 Land Species in order to determine the- value of reactions to 

 space as a sign of habits. 



Classification in accordance with reactions to space. 



Water Species. 



I^and-Water Species. 



Land Species. 



Chrysemys picta 

 Podocnemis mada- 



gascariensis 

 Chelodina novaehoUandiae 

 Tracheviys scabra 

 Polymedusa galeata 



E^nys meleagris 

 Na?iemvs guttata 



Terrapcne baitri 

 Terrapene Carolina 

 Xerohates polyphemus 

 Testudo vicina 

 Chelops insculptus 



This classification agrees fairly well with what is known of 

 the habits of the forms, except that Chelopiis inscidptiis is a land- 

 water rather than a land species. 



The Spatial Worth of Sense Data. 



For the purpose of ascertaining the relative importance for 

 reactions to space of the visual, tactual, muscular and organic 

 sense impressions some experiments were made with blindfolded 

 tortoises. The eyes, in these experimentLS were covered with 

 tin-foil caps which effectually excluded visual stimuli. 



