IN tropical America no order of mammals is represented by such a diversity of forms and abundance of individuals as the bats (Chiroptera); but in this region the reproductive habits of only a few species have been investigated. Tropical American bats in which the reproductive cycles are known fall into one of two groups: (1) those with the typical mammalian reproductive pattern of restricted sexual seasons and coincidence of copulation; (2) those with no well-defined sexual season and which breed throughout the year. The first group is represented by only one species, the phyllostomid bat, Glossophaga soricina, examined by Hamlett1 in Brazil, and it is doubtfully placed in this category, since the reproductive pattern was deduced from an investigation of relatively few specimens taken at only one time of the year. In the second group, again only one species can be included, the economically important vampire bat, Desmodus rotundus murinus, which was examined in Panama by Wimsatt and Trapido2. We have ourselves3 presented Colombian records which indicate thafc at least some tropical, equatorial phyllostomid bats, unlike North American forms, are polyœstrous and breed throughout the year, but our results were limited and based only on females.