wever, or whether they are mere races, and how far any of
them are identical with the Sumatran Orang, as Mr. Wallace thinks the
Mias Pappan to be, are problems which are at present undecided; and
the variability of these great apes is so extensive that the
settlement of the question is a matter of great difficulty. Of the
form called "Mias Pappan," Mr. Wallace observes: "It is known by its
large size, and by the lateral expansion of the face into fatty
protuberances, or ridges, over the temporal muscles, which have been
mistermed callosites, as they are perfectly soft, smooth, and
flexible. Five of this form, measured by me, varied only from 4 feet
1 inch to 4 feet 2 inches in height, from the heel to the crown of the
head, the girth of the body from 3 feet to 3 feet 71/2 inches, and the
extent of the outstretched arms from 7 feet 2 inches to 7 feet
6 inches; the width of the face from 10 to 131/4 inches. The color and
length of the hair varied in different individuals, and in different
parts of the same individual; some possessed a rudimentary nail on the
great toe, others none at all; but they otherwise present no external
differences on which to establish even varieties of a species.

"Yet, when we examine the crania of these individuals, we find
remarkable differences of form, proportion, and dimension, no two
being exactly alike. The slope of the profile, and the projection of
the muzzle, together with the size of the cranium, offer differences
as decided as those existing between the most strongly marked forms of
the Caucasian and African crania in the human species. The orbits vary
in width and height, the cranial ridge is either single or double,
either much or little developed, and the zygomatic aperture varies
considerably in size. This variation in the proportions of the crania
enables us satisfactorily to explain the marked difference presented
by the single-crested and double-crested skulls, which have been
thought to prove the existence of two large species of Orang. The
external surface of the skull varies considerably in size, as do also
the zygomatic aperture and the temporal muscle: but they bear no
necessary relation to each other, a small muscle often existing with a
large cranial surface, and vice versa. Now those skulls which have the
largest and strongest jaws, and the widest zygomatic aperture, have
the muscles so large that they meet on the crown of the skull, and
deposit the bony ridge which se