- 1 An account of the breeding cycle of Arctocephalus pusillus is given based on an examination of 184 specimens.
- 2 The specimens were grouped in age classes separated by the stage of closure of the skull sutures. It was not found possible to age the specimens by growth rings in the teeth.
- 3 A. pusillus remains. at its breeding rookeries throughout the year but the young are born mostly in the late spring, the birth of first pups occurring rather later than those of multiparous females.
- 4 Oestrus occurs about a week after parturition.
- 5 There is a delay in implantation of about four months.
- 6 The averae period of gestation, including the period of delayed implantation, is 259 days.
- 7 There is a phase of follicular activity in the ovaries at the time of implantation of the blastocysts.
- 8 Lactation is prolonged and may last until the birth of a succeeding pup.
- 9 A full description is given of the histological changes in the different parts of the reproductive tract during the breeding cycle.