302 G. V. HAMILTON 



attained the shelf he copulated with Maud in the manner des- 

 cribed in observation 1. After a few minutes he again mounted 

 her, but this time the female merely arose from a crouching to a 

 quadrupedal standing position, without displaying signs of sexual 

 excitement. There was no smacking of lips by either animal, 

 and the desultory efforts of the male to copulate terminated as 

 soon as he entered the female and made two or three strokes. 

 Both animals sat inactive for five minutes, then the male drew 

 the female's hind quarters towards him. He started to mount, 

 then desisted and began to inspect her genitalia with eyes, nose, 

 mouth and fingers. After two or three minutes of this behavior 

 he copulated, both animals displaying sexual excitement. During 

 the next half hour there was an alternation of perfunctory 

 attempts at copulation with more vigorous attempts, the latter 

 being immediately preceded by examinations of the female's 

 genitalia on the part of the male. 



Observation 4. 14-Jimmy II-M-c and 9-Gertie-M-cr (both 

 sexually mature young adults) had been at large together in 

 company with a number of other males and females for several 

 weeks. They had copulated, a number of times each day. 

 Their behavior during a half hour when they were perched 

 together upon the roof of the laboratory consisted in the same 

 alternation of perfunctory attempts at copulation with more 

 vigorous attempts, the latter being immediately preceded by 

 examination of the female's genitalia on the part of the male. 

 Jimmy II is more apt to follow me about when he is at large 

 than to stay with the tribe, and this may account for the fact 

 that he manifested the behavior just described less frequently 

 than did Timmy. 26-Skirrel-M-c manifests such behavior more 

 frequently than does Jimmy II and less frequently than does 

 Timmy. The mature rhesus male (16-Sobke-M-r) also inspects 

 the female's genitalia after a perfunctory attempt at copulation 

 and just before a vigorous attempt, but he is more apt to increase 

 his sexual excitement by chasing and biting the female. All of 

 my mature males, with the exception of the eunuchs and the 

 baboon, at times chase and bite their mates in apparent prepara- 

 tion for copulation, but only after prolonged access to them. 



Situation 3. Two males, confined in separate cages with 

 mates, are caused to exchange mates. 



