'Mias Kassu', and 'Mias Rambi'. Whether these are distinct species,
however, 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 has been mis-termed 'callosities', 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 7 1/2 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 13 1/4 inches. The colour 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.

[footnote] *On the Orang-Utan, or Mias of Borneo, 'Annals of
Natural History', 1856.

"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