Repts. Internatl. Whaling Comm., Special Issue 3: 181-201. 6 tabs. 19 figs.

–Describes in detail the morphology and internal structure of the incisors and cheek teeth, and correlates their growth layers, size, and eruption with season of death, body length, puberty, and closure of cranial sutures. Growth layers were also observed in the tympanic bones and ribs, but not the humerus or malleus. Concludes that the tusks are best for age determination, that one growth layer group is deposited in them per year, and that marked accessory layering probably represents individual rather than latitudinal variation. Life span is in excess of 50 years. Puberty in both sexes occurs at 9 or more years of age in the Townsville population, but several years later in the Mornington Island population. The tusks of males erupt at about 12 and 14+ years in these two populations, respectively. An age-length growth curve for both sexes, based on number of dentinal growth layer groups, is presented. Techniques used in aging dugong teeth are also described on pp. 41-45 of this volume.