450 'Journal of Comparative Neurology and Psychology. 



body, and open the mouth to bite. I have never observed any- 

 thing of that kind in a palaeencephahc animal. 



Probably it is due to the neencephalon, too, that first in the 

 reptiles we meet with individual differences. Within the same 

 species there are indolent and excitable, dull and lively individuals. 

 Everyone who has kept many mud turtles knows this. 



Reptiles learn more easily and quickly than fishes. One can 

 teach turtles to come to be fed at the sound of clapping. They 

 also learn to follow correctly the path which leads to good food 

 and will work all day long against obstacles. Siegwart's turtles 

 worked themselves repeatedly through successively narrower grat- 

 ings to an aquarium containing Proteus. They even climbed 

 over fences which were interposed and placed themselves on edge 

 in order to get between the bars. Finally, reptiles which naturally 

 follow only jumping prey learn to recognize resting prey. 



Aside from the obtaining of food, the life of reptiles consists 

 merely in resting and sunning themselves. Therefore, in so far, 

 we recognize no very marked differences between reptiles and 

 amphibians. Most important in the psychological behavior of 

 reptiles is the fact that the animals are no longer always dependent 

 upon the sense impression of the moment, but that earlier impres- 

 sions influence them. Further, they associate certain sense 

 impressions which lie within the realm of the olfactory and oral 

 senses, and turn them to account; they learn more easily than 

 fishes and amphibians; occasionally they foresee; and they exhibit 

 individual differences. There can be no doubt that all of these 

 facts are referable to the appearance of a cortex in the neen- 

 cephalon. 



So far as our observations go at present, genuinely psychological 

 processes make their appearance at this point in the animal series. 

 It is certainly possible that they may occur even in the selachians 

 and particularly in the amphibians in connection with the begin- 

 nings of the cortex, but they are so rudimentary that they will 

 probably be found only when attention is especially directed 

 toward them. 



From the brain of the reptiles two different types of brain are 

 derived. One, the type found in the lower mammals, develops 

 by increase of the cortex; the other is the avian type. 



In birds the cortex is more highly developed than it is in reptiles. 

 The increase in the bulk of the brain, however, actually results 



