It is at once evident that the differences between the Ilocano and the Valley Tinguian are very slight, in fact are less than those between the valley and mountain people of the latter tribe.  The Ilocano appear to be slightly taller, the length of head a little less, and the breadth a bit more; yet there is an average difference of only two points in the cephalic indices of the two groups.  The only other points of divergence are:  the greater percentage among the Ilocano of eyes showing the Mongolian fold, and the occurrence of straight hair in about half the individuals measured.  However, this latter feature may be more apparent than real; for the Ilocano cut the hair short, and a slight degree of waviness might readily pass unobserved.

As we pass from the Valley to the Mountain Tinguian, and from them to the Apayao, we find the average stature almost constant, but the head becomes longer; there is a greater tendency for the cheekbones to protrude and the face to be angular, and there is a more frequent development of the supra-orbital ridges.  The root of the nose is often flat and the bridge concave; while wavy hair becomes the rule in the mountains.  There is a slight decrease, in the Tinguian groups, of eyes showing the Mongolian fold, but in the Apayao the percentage again equals that of the Ilocano.

The Apayao present no radical differences to the Mountain Tinguian; yet, as already noted, the length and height of the head are slightly greater; the zygomatic arches more strongly developed; the face more angular; and the nose is broader as compared with its length.  Evidences of former extensive intermixture are here apparent, while at the present time there is rather free marriage with the neighboring Kalinga and Negrito.

Comparing these four groups with the Igorot, we find that the latter averages slightly taller than all but the Ilocano.  The breadth of the head is about the same as the Ilocano; but the length is much greater, and there is, in consequence, a considerable difference in the cephalic index.  Reference to our tables will show the Ilocano and both Tinguian divisions to be brachycephalic, while the Igorot is mesaticephalic.  The average index of the Apayao also falls in the latter classification; but the variation from Igorot is greater than is indicated, for the Apayao skull is actually considerably shorter and narrower.  In the length and breadth of the nose, the Igorot exceeds any of the groups studied, while the Malayan (Mongolian?) fold of the eye is reported in the great majority of cases.  The bodily appearance of the Tinguian and Bontoc Igorot differs little, although the latter are generally of a slightly heavier build.  Both are lithe and well proportioned, their full rounded muscles giving them the appearance of trained athletes; neither is as stocky or heavy set as are the Igorot of Amburayan, Lepanto, and Benguet.

There is great variation in color among the members of all these tribes, the tones varying from a light olive brown to a dark reddish brown; but in general the Ilocano and Valley Tinguian are of a lighter hue than the mountain people.