_Avahi_, Jourdan, C. R., Journal l'Inst., ii., no. 62, p. 231 (1834).
_Avahis_, Milne-Edwards and Grandid., Hist. Nat. Madag., Mamm., i., p. 320 (with full synonymy).
This genus is monotypic, containing but a single species, whose characters include necessarily those of the genus.
_Lemur laniger_, Gm., Syst. Nat., i., p. 44, no. 10 (1788).
_Microrhynchus laniger_, Jourdan, Thèse inaug. Soc. Phys., Grenoble, 1834; Mivart, P. Z. S., 1866, p. 151, pi. xv.
_Avahis laniger_, Milne-Edwards and Grandid., Hist. Nat. Madag., Mamm., p. 325 (with full synonymy), Atlas, pls. 9, 10.
CHARACTERS.--Fur woolly; the head nearly round; the face short in proportion to the head; muzzle short, covered with hair; the nose and region of the chin hairy; nose-pad on lip large; nostrils opening into a cavity on the upper lip below the skin. Eyes large, the pupil vertical; ears small, concealed in fur. Tail a little longer than the body; body short, stumpy. Third, fourth and fifth fingers flattened; third and fourth toes united by a membrane as far as the first joint.
{ 95}Cranium more vaulted and the muzzle remarkably shorter than in the genera _Indris_ and _Propithecus_; eye-sockets very large; the space between the eyes hollow. Temporal ridges not uniting into a single median ridge. Nasal bones projecting as far as the front end of the very small pre-maxillary bone. Lower jaw remarkably deep and broad behind; line of union of its two halves nearly half the length of the jaw, and in a straight line with the incisor teeth. Toothless space in front of upper jaw greater than in the other two genera. Dentition of the upper jaw: _incisors_ small, the outer larger than the inner, set close to the canines and not at the inner edge of the toothless space; _canines_ vertically short; _pre-molars_, with no inner cusp, but having a prominent outer cingulum (a character seen in no other species of Lemur); _molars_, four-cusped. Lower jaw: _incisors_ larger than in the two other genera, and less horizontal, the inner ones more slender than the outer. Anterior and posterior _molars_, five-cusped. Hind margin of palate reaching to the middle of the median molar. Central bone of wrist wanting (of all Primates agreeing in this character only with Man, the Chimpanzees, the Gentle- and Sportive-Lemurs and the Endrina); fourth digit of the hands and feet longest. Tail long. The small intestine not spirally coiled upon itself, but folded many times transversely.