The orang-utan is found in the large Asiatic islands of Borneo and Sumatra, more frequently in the former island. It is particularly common a few days’ journey to the west of Sungi-Kapajan, on the river Sampiet, in Kotaringin, and in other remote districts on the southern and western coasts.[113] The Dyaks of Long-Wai told the traveller Bock that the orang was also found further to the north, and at Teweh, as well as in Dusem, to the west of Kutai.[114] Wallace states that this animal is widely diffused in Borneo, inhabiting many parts of the south-west, south-east, north-east, and north-west coasts, but that it is restricted to the low-lying marshy forests. It seems at first sight inexplicable that this ape should be unknown in Sarawak, while it abounds in Sambas on the west, and in Sadong on the east, but a closer acquaintance with the habits and mode of life of the orang enables us to discern sufficient grounds for the apparent anomaly in the physical conditions of Sarawak. In Sadong, where Wallace observed the orang, he only found it in low marshy districts which were at the same time covered with primeval forests. Many isolated hills rise from these marshes, upon which the Dyaks have settled, and have planted them with fruit trees. These are a great attraction to the orang, which devours the unripe fruits, and then retires again to the marsh. He cannot live on high and dry ground. Thus, for example, he comes in troops into the low parts of the Sadong valley; but on reaching the limits where the ebb and flow of the tide are perceptible, and the ground, though flat, is dry, the orang is no longer found. The lower part of the Sadong valley is indeed marshy, but it is not covered throughout with a growth of tall trees, only for the most part with the Nipa palm; and near the town of Sarawak, the country becomes dry and hilly, interspersed with scattered tracts of primeval forest, and with jungle which was formerly cultivated by the Malays and Dyaks. The orang is more rare in Sumatra than in Borneo, and in the former island is chiefly found in the north-eastern districts of Siak and Atjin. Rosenberg states that the orang only frequents the flat, marshy forests on the coast between Tapanoli and Singkel, living in thick woods which, on account of their impenetrability, are seldom trodden by the foot of man. The chimpanzee also frequents the marshy forests which are not too thickly overgrown, while the gorilla prefers such tablelands as are not wholly devoid of water.