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,
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