Daubentonia madagascariensis, Geoffr., Décad. Philos., iv., p. 193 (1795); Dahlbom, Studia, p. 326, t. 12.
Chiromys madagascariensis, Cuv., Leçons d'Anat. Comp., Tabl. de Class., 1 (1800); Owen, Tr. Z. S., vol. v., p. 33; Peters, Abhandl. K. Akad. Berlin, 1865, p. 79.
(Plate I.)
PLATE I.
THE AYE-AYE.
Characters.—Head short and round; face short-snouted, with a patch of bristles below the eye, between the ear and the angle of the mouth; eyes round, prominent; eyebrows long and bristly; pupils wide, furnished with a false eyelid (a nictitating membrane); ears large, rounded, directed backwards, naked, and studded with small protuberances; tail longer than the body, bushy, with hair 3-4 inches long; hind-limbs longer than the fore-limbs, the thigh-bone being one third longer than the humerus, the hand the longest segment of the fore-limb; fingers long—the fourth the longest—with compressed and pointed claws, which are proportionately much longer than the toes; the middle or third digit slender and very remarkable, being extremely attenuated and wire-like; thumb opposable, and placed at an acute angle to the short index; great toe opposable, set at an open angle to the other digits, its nail flat; the remaining toes with pointed compressed claws (like the second toe of Lemuridæ and second and third of Tarsiidæ). Teats, two, placed low down on the abdomen. Length of body and tail together 36 inches. Skull highly arched, convex transversely; muzzle short and deep; bony palate not extending behind the middle of the posterior molar tooth; lower jaw with condyle elongated from before backwards and on a level with the cheek-teeth, its two halves united at an acute angle by elastic tissue, allowing each half to play independently of the other. Its dental formula, I11, C00, P10, M33 = 18. Incisors very large, curved, with persistent pulp, and enamel only in front, growing up as fast as worn away; canines absent (the last two characters as in the Rodents); long vacuity between incisors and pre-molar; pre-molar much smaller than molars; molars with flat crowns and very indistinct tubercules; milk-teeth agreeing more in number and form with those seen among Lemurs than with the permanent set; the upper jaw having its full set of two incisors, one canine, and a pre-molar tooth present; the lower jaw having one incisor, no canine, and one pre-molar tooth on each side. Dorsal and lumbar vertebræ together 18, sacral 3, and caudal 22-27.
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′ 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.