312 journal of Comparative Neurology afid Psychology. 



(5) The first chelipedes or first pair of walking legs. Owing 

 to the close proxmity of these with the mouth parts it was difficult 

 to obtain a reaction that was due to the stimulation of these org-ans 

 alone. Repeated trials were made with each animal, however, 

 and no result was noted unless it was clearly from the stimulation 

 of these members only. These were the most sensitive organs, 

 next to the mouth parts. Every animal responded energetically. 

 The responses were such as closing the forceps of the member 

 stimulated as though closing on a bit of meat, in ten cases bringing 

 the cheliped to the mouth and usually accompanying this with 

 chewing movements, and in four cases the orientation of the 

 mouth to the stimulus. 



(6) The second chelipedes. Here the responses w^re not so 

 vigorous, although they occurred in every case. In eight cases 

 the member was brought to the mouth or moved in that direction, 

 and in five cases this was accompanied by chewing movements of 

 the mouth parts. 



(7) The third chelipedes. Here there were six failures to 

 respond, and four of the responses were only by a slight movement 

 of the member stimulated. In two cases the chelipedes were 

 moved toward the mouth, and in four cases the animal turned to 

 the stimulus. 



(8) The fourth chelipedes. Out of the fifteen animals experi- 

 mented upon only four responded to this stimulus, and three of 

 these did so only by a slight movement of the member. One 

 animal reacted with chewing movements and turned toward the 

 source of the stimulus. 



(9) The pleopods and the ventral surface of the abdomen. It 

 was not always possible to get at these readily since the animals 

 frequently kept the abdomen tightly flexed, so that the pleopods 

 were covered by the telson. By holding the animal on its back 

 in the air for a few moments, however, it could usually be brought 

 to straighten out. In this way they would remain straight for a 

 few minutes after being put back into the water, and out of the 

 total number eleven animals reacted to the stimulus. In two cases 

 the animals faced about to the stimulus, in another the chelae were 

 closed and then brought to the mouth, and in still another case 

 there were chewing movements accompanied by a general rest- 

 lessness. In two cases there was a most interesting; reaction. 

 The animal raised itself on the chelae and telson, bowing up into 



