26 Mr. A. R. Wallace on the Habits of the Orang-Utan. 



III. — On the Habits of the Orang-Utan of Borneo. 

 By Alfred R. Wallace. 



The two species of Pithecus which it is believed have now been 

 proved to exist in Borneo, appear to have habits so similar that 

 we shall not attempt to divide them, but shall speak of the 

 genus in the following observations, in which we shall for brevity 

 use the native name " Mias ^' as applied to both species. 



There seems little reason to doubt that the Sumatran Orang 

 is identical with the larger Bornean species, or that possessing 

 the lateral cheek-ridges. All these animals confine themselves 

 strictly to the low, level and swampy districts which occupy 

 so large a portion of the surface of both these islands ; and this 

 circumstance sufficiently accounts for the peculiarity of their 

 distribution. It seems at first sight surprising, that though 

 they are abundant on almost all the north-west coast of Borneo, 

 and in the south and south-west districts as far north as Sambas, 

 yet in the territory of Sarawak they are quite unknown. But 

 when we know the habits of the animal, we see a sufficient 

 reason for this in the peculiar physical features of the Sarawak 

 district. The Mias frequents those districts only which are so 

 low and level as to be marshy, and are at the same time covered 

 with a lofty virgin forest. In the midst of these plains are 

 isolated mountains, on many of which the Dyaks have settled 

 and planted numerous fruit-trees, which are much sought after 

 by the Mias, which traverses these hills in all directions, but 

 always retires to the swamp at night. Wherever the country 

 becomes slightly elevated, and therefore dry, the Mias is no 

 longer found. Thus, in the lower part of the Sadong River the 

 Mias is abundant ; but immediately above the limit of the tides, 

 where the country, though still flat, is just high enough to be 

 dry, it disappears. Now the Sarawak valley has this peculiarity, 

 that the lower portion, though swampy, is not covered with con- 

 tinuous lofty forest, but is principally occupied by the Nipa palm, 

 while at a short distance above the town of Sarawak the country 

 becomes dry and covered with low undulations, the greater 

 portion of which is second- growth jungle, having been at dif- 

 ferent times cultivated by the Malays and Dyaks. It is probably 

 the vast extent of unbroken and equally lofty forest which is the 

 principal attraction to the Mias. These forests are its open 

 country, the place best adapted to its mode of life, where it can 

 roam in every direction with as much facility as the Indian in 

 the prairie or the Arab in the desert. The dry grounds are 

 more frequented by man, more cut up by clearings and by low 

 second-growth jungle, in which progression is more difficult, 



