The hair of the crown is short and directed backwards; the tail is long and perfectly prehensile, being naked and sensitive for a considerable distance back from the tip. The limbs are moderately long, and the thumb and great-toe are well developed, the nails of the digits being compressed and pointed. In regard to the skeleton, the skull of _Lagothrix_, as Dr. Slack points out, can be readily distinguished from that of the Capuchins by a broad, well-marked, articulation taking place between the pre-maxillary and the nasal bones at right angles to the suture between the latter, while in the Capuchins no true articulation takes place between these bones. The lower jaw is larger than in _Cebus_, approaching the size and form of _Mycetes_. The incisor teeth are small and unequal, the upper inner incisor being the largest; the canines are very large and grooved in front. The Woolly Monkeys are slow in motion, gregarious, diurnal, and arboreal. The "Barrigudos," as they are called by the Portuguese colonists, live exclusively on fruits, and are larger and less active than the Capuchins. They are confined to the forests of the Ecuador district of the Upper Amazon Valley, and along the slopes of the Andes, north to Venezuela and south to Bolivia. They are of a mild disposition, and, as Mr. Wallace remarks, they are the species "most frequently seen in confinement, and are great favourites, from their grave countenances, which resemble the human face more than those of any other Monkeys, their quiet manners, and the great affection and docility they exhibit." {222}I. HUMBOLDT'S WOOLLY MONKEY. LAGOTHRIX LAGOTHRIX. _Simia lagothrica_, Humb. and Bonpl., Obs. Zool., i., p. 322 (1811). _Lagothrix cana_, Id. tom. cit. i., p. 354 (1811). _Lagothrix lagotricha_, Id. tom. cit. p. 354. _Lagothrix humboldtii_, Geoffr., Ann. Mus., xix., p. 107 (1812); Scl., P. Z. S., 1863, p. 374, pl. xxxi.; Schl., Mus. Pays Bas, vii., p. 162 (1876, part.). _Lagothrix canus_, Geoffr., Ann. Mus., xix., p. 107 (1812). _Gastrimargus olivaceus_, Spix, Sim. et Vespert., Bras., p. 39, pl. 28 (1823). _Lagothrix tschudii_, Pucher., Rev. et Mag. de Zool., 1857, p. 296. _Lagothrix geoffroyi_, Pucher., t. c. p. 297. _Lagothrix cana_, Schl., Mus. Pays Bas, vii., p. 162 (1876; part.). _Lagothrix olivaceus_, Spix, ?; Bates, Nat. River Amazon, ii., p. 320 (1863). (_Plate XX._) CHARACTERS.--Body large and heavy; face naked, black, and wrinkled; forehead low, the eyes projecting; a few scattered white hairs on lips. Hair of under surface hoary, and longer than that of the upper surface. ADULT MALE.--General colour blackish, hoary-grey, the hairs being dark grey, tipped with black. Head, chest, hands, under surface of body, and tip of tail, black. Length of the body, from 19 or 20 inches to 27 inches in very large specimens; tail from 24 to 26 inches.