472 Mr. A. R. Wallace on the Orang-Utan or Mias of Borneo. 



I have preserved the skins, either in spirits or dried. Of seven I 

 have perfect skeletons, and of the remainder the skulls ; and of 

 all, the sex, colour and other external peculiarities were accurately 

 noted at the time, as well as all the principal dimensions. I 

 have besides two other skeletons and two skulls, the sex and 

 external characters of which are determined on the authority of 

 Europeans or natives who saw them when freshly killed. Of 

 this extensive series sixteen are fully adult, and their skulls are 

 therefore strictly comparable with each other, nine of them being 

 males and seven females. They were moreover all obtained in 

 a very limited tract of country watered by the same small river 

 and of very uniform physical features. We may therefore as- 

 sume, unless the contrary can be supported by the very strongest 

 evidence, that the male and female specimens are sexes of the 

 same species, whether they be one or more. 



The males procured by me may be divided into two groups, 

 differing considerably both in the external characters and in 

 those of the cranium. The first and most abundant is the 

 large animal known among the natives as the ^^ Mias pappan " 

 or " Mias chappan/' the latter name being used by the Dyaks 

 as well as that of " Mias Zimb/^ while the former is, on the 

 authority of Sir James Brooke, a name applied to it by the 

 Malays. It is known by its large size and by the lateral expan- 

 sion of the face into fatty protuberances or ridges over the tem- 

 poral muscles, which have been mistermed 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| inches, and the extent of the outstretched 

 arms from 7 feet 2 inches to 7 feet 8 inches ; the width of the 

 face from 10 to 13|- 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 dif- 

 ferences on which to establish even varieties of a species. Yet 

 when we examine the crania of these individuals we find remark- 

 able 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 zygo- 

 matic 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- 



