In the Sadong, where I observed it, the Mias is only found when the country is low level and swampy, and at the same time covered with a lofty virgin forest.

From these swamps rise many isolated mountains, on some of which the Dyaks have settled and covered with plantations of fruit trees.

These are a great attraction to the Mias, which comes to feed on the unripe fruits, but always retires to the swamp at night.

Where the country becomes slightly elevated, and the soil dry, the Mias is no longer to be found.
For example, in all the lower part of the Sadong valley it abounds, but as soon as we ascend above the limits of the tides, where the country, though still flat, is high enough to be dry, it disappears.

Now the Sarawak valley has this peculiarity--the lower portion though swampy, is not covered with a continuous lofty forest, but is principally occupied by the Nipa palm; and near the town of Sarawak where the country becomes dry, it is greatly undulated in many parts, and covered with small patches of virgin forest, and much second-growth jungle on the ground, which has once been cultivated by the Malays or Dyaks.
Now it seems probable to me that a wide extent of unbroken and equally lofty virgin forest is necessary to the comfortable existence of these animals.