Length of arm was taken on only 19 individuals, 16 males and 3 females. The longest arm measured 675 millimeters (2 feet 3 inches), which is not so long as the average Caucasian arm, though more out of proportion to the height, in this case being nearly half the latter measurement. The shortest arm, that of an adult female, was 539 millimeters (21 inches). So far from being ape like in appearance, some of the Aeta are very well-built little men, with broad chests, symmetrical limbs, and well-developed muscles hardened by incessant use. This applies of course only to the young men and boys just approaching manhood, and is especially noticeable in the southern regions, where the Aeta are generally more robust and muscular. The younger females are also as a rule well formed. In the case of unmarried girls the breasts are rounded and erect, but after marriage gradually become more and more pendant until they hang almost to the waist line. With advancing age the muscles shrink, the skin shrivels up until an individual of 40 to 50 years usually has the decrepit appearance of an octogenarian; in fact, 50 is old age with the Aeta. (See plates.) Anthropometric observations fall naturally into two groups, dealing with the proportions of the head and body, the latter of which have already been discussed. Great interest attaches also to the relative proportions of the different dimensions of the head and especially to the cephalic index obtained by multiplying the maximum breadth by 100 and dividing by the maximum length. Heads with an index of 75 or under are called _dolichocephalic;_ those between 75 and 80, _mesaticephalic;_ and those over 80 _brachycephalic._ The beads of the Aeta are essentially _brachycephalic._ Owing to the lack of proper calipers during the greater part of my stay among them, I was able to measure only 19 individuals, but of those all but 5 were in the _brachycephalic_ group, one instance being noted where the index was as great as 92; the lowest was 78. The average of the males was 82 and of the females 86.