Abstract
These 2 articles describe the sexual be-havior of Rhesus monkeys living in free ranging groups on a small island off Puerto Rico. Systematic observation of several behavior traits was made during estrus. The record of these observations is given in a 9-page table. Much of this behavior is to be considered as an integral part of estrus and not merely indicative of estrus. Estrus periods were found to be highly discrete. The period of estrus was 28 days. The inter-estroidal interval for 5 [female][female] averaged 19.4 days. The discussion on form of abnormal sex behavior includes several case studies.