{16}Olfactory lobes of brain covered by the cerebrum; convolutions and grooves of cerebrum similar to those in normal Lemurs. Intestine 26 inches long; no striped tissue in the muscular sheath of the gullet at the anterior end of the stomach. Digastric muscle (for moving the jaws) very much developed in accordance with the great gnawing powers of the species. Fur on back, flanks, tail, and limbs dark brown, nearly black, but with the white of the basal half of the hairs shining through; hair woolly at base; long hairs on top of head and back of neck tipped with white; short hairs of face dirty white. Nose and lips naked, flesh-coloured; ears black; sides of head and throat greyish-yellow; chest often bright yellow, the chin paler. Inner sides of limbs yellowish-white, and on the under surface of the body the basal part of hairs showing through, producing a pale yellowish-white, or sub-rufous, colour. Feet and digits black. Tail black, at its base greyish-white or greyish-brown, and often with long white hairs throughout. The species is more nearly related to the members of the genus _Galago_ to be described later on, than to any other of the _Lemuroidea_. DISTRIBUTION.--The Aye-Aye is confined to the island of Madagascar. It makes its home in the dense parts of the great forest that runs along the eastern border of its central plateau, but only in that part of it which separates the Sihànaka Province from that of the Betsimisàraka, which is about 25 miles from the east coast, in latitude 17° 22[prime] S. It is more common than has been supposed, its noctural habits and the superstitious awe with which it is regarded accounting for its apparent rarity, and for the contradictory reports given of its habits.