224 Studies in Animal Behavior 



characteristic bodily attitude and remain quiet. The 

 attitude assumed by the female is similar to that 

 observed in the ordinary thigmotactic reaction of 

 amphipods and may, perhaps, be but the same form 

 of response somewhat modified and specialized in 

 relation to the function of reproduction. When the 

 males are torn away from the females they soon 

 seize their partners again and roll them about into 

 the proper position and then proceed on their way in 

 apparent contentment. The female, as soon as 

 seized by the male, curls up and allows herself to be 

 rolled and tumbled about without a show of resist- 

 ance or protest. The males, as a rule, are larger 

 than the females and usually get their partners into 

 the desired position quite readily; but when a small 

 male attempts to carry a large female he experiences 

 much difficulty. I observed a male Hyalella en- 

 deavoring to carry a female somewhat larger than 

 himself. After seizing the female he would turn 

 her around until she finally came into the proper 

 position for transportation, but owing to the larger 

 size of his partner the male could not reach around 

 her body so as to carry her away. No sooner was 

 the female properly adjusted than the male would 

 lose hold of her round body and the same efforts had 

 to be repeated. During all this performance the 

 female remained dutifully passive. After watching 

 the further struggles of the male for over half an 

 hour I became convinced, although he was not, that 

 he had undertaken an impossible task, and discon- 



