3:18 'Journal of Comparative Neurology and Psychology. 



to the stimulus. (5 and 6) First and second chelipedes. There 

 was a very decided reaction to each stimulus, consisting usually of 

 a quick grasping by the member stimulated and bringing it to the 

 mouth, where it was rubbed by the maxillipedes. (7 and 8) 

 Third and fourth chelipedes. Three of the animals quickly drew 

 the member away, the other two jumped and faced toward the 

 stimulus. (9) Ventral surface of abdomen. Two animals sprang 

 away from the stimulus, one faced toward it, one bowed up on the 

 telson and chelae, rubbing and pulling at the pleopods with the 

 second and fourth chelipedes, while the fifth bowed up likewise, but 

 rubbed with the fourth chelipedes not the ventral but the dorsal 

 surface of the abdomen — a much more difficult feat to accomplish. 

 (10) Telson. The telson was usually folded and the abdomen 

 sharply flexed. (11) Carapace. When the back of the carapace 

 was touched there was a quick start and in one case the spot was 

 scratched with the second, third and fourth chelipedes of both sides 

 at once, the animal meanwhile lying flat on its ventral surface. In 

 another case the animal grasped at the spot with the second cheli- 

 ped as if to pull something away. 



In one case where the left eye was stimulated the animal rubbed 

 and dug at both eyes with the second and third chelipedes; in 

 another case when a first cheliped was stimulated the eye on the 

 same side was rubbed with the first and second chelipedes, while 

 in a third case the stimulation of the antennule was followed by 

 rubbing the eye with the second cheliped. In the latter case, how- 

 ever, the eye may have been stimulated directly by the diffusing 

 liquid. The manner in which the animals rubbed the part stim- 

 ulated seemed quite human in a way, and reminded one of the 

 instinctive fashion in which we rub a slight bruise or burn. 



One animal was tried with a 50 per cent, solution of hydro- 

 chloric acid. When the antennx were touched they were jerked 

 away quickly, and the antennules when stimulated were clawed 

 at vigorously. Touched on the chelae the animal writhed and 

 struggled as if in great pain until the solution diffused. Stimulated 

 on the mouth, the animal scratched and clawed and dug and 

 scraped both the back of the carapace and the abdomen, drew in 

 its eyes (a thing which had not occurred before in any of the chem- 

 ical experiments) and. rubbed them violently, and in general ex- 

 hibited every sign of intense pain. The faintest trace on the telson 

 caused the animal to roll up in a ball digging furiously at the spot. 



