 Specimens of "P. hylaeum" were caught in December in hollow trees near a lagoon; four pregnant females each contained a single embryo.Purportedly, captive female "P. aedium" have an estrous cycle of 10 days, a gestation period of 119 days, and apparently a single offspring.Recorded gestation has been 123–150 days and litter sizes of one to two young in this species, which are highly precocial, much unlike most rodents, which are totally helpless when born.