When pleased it utters a reiterated shrill note, and draws back the corners of its mouth, producing a smile by contracting the same muscles as in the human face. II. THE WHITE-CHEEKED CAPUCHIN. CEBUS LUNATUS. _Cebus lunatus_ (Sajou cornu), male; F. Cuv., Hist. Nat. Mamm., pl. 70 (nec Kuhl). _Cebus vellerosus_, Is. Geoffr., Cat. Méth. Primates, p. 44 (1851, pt.). _Cebus leucogenys_, Gray, P. Z. S., 1865, p. 824, pl. xlv.; id. Cat. Monkeys Brit. Mus., p. 48 (1870). _Cebus frontatus_, Schl., Mus. Pays Bas, vii., p. 206 (1876). CHARACTERS.--Fur soft, elongate, silky, with thick under-fur. Hair on front of head elongate and reflexed, forming across the brow a short crest, higher above each eye; hair on top of head lying flat; that on cheeks short and adpressed; base of nose large, and corrugated longitudinally; toes long; tail longer than in other species; under surface of body less haired. General colour silky brown, almost black on the head and limbs, paler on the shoulders and arms; the whiskers forming a white, or sometimes pale yellow, band, bordering the cheeks from opposite the eyes to the chin. Face and hands naked, violet; skin below the hair of the same colour. The hair of the body is longer in winter than in spring; but the crests, or "horns," and the white whiskers appear only when the animal is fully adult. DISTRIBUTION.--Brazil. III. THE SLENDER CAPUCHIN. CEBUS FLAVUS. _Cebus barbatus_, Geoffr., Ann. Mus., xix., p. 110 (1812); Schl,. Mus. Pays Bas, vii., p. 197 (1876). {209}_Cebus albus_, Geoffr., t. c. p. 112 (albino). _Cebus flavus_, Geoffr., Ann. Mus., xix., p. 112 (1812); Kuhl, Beitr. Zool., p. 33 (1820); d'Orbig., Voy. Amér. Mérid., iv., Mamm., p. 1, pl. 3 (1847); Schl., Mus. Pays Bas, vii., p. 204 (1876). _Cebus gracilis_, Spix, Sim. et Vespert., Bras., p. 8, pl. 5 (1823, young). _Cebus libidinosus_, Spix, t. c. p. 5, pl. 2 (1823). _Cebus unicolor_, Spix, t. c. p. 7, pl. 4 (1823). _Simia flavia_, Schreb., Säugeth., pl. 31B (1840). _Cebus elegans_, Is. Geoffr., C. R., xxxi., p. 875 (1850). _Caiarára branca_, Bates, Nat. Amaz., ii., p. 100 (1863). _Cebus pallidus_, Gray, Cat. Monkeys Brit. Mus., p. 49 (1870). CHARACTERS.--Hairs of crown short and reflexed, forming a small short crest, separated by a median furrow on each side of the dark crown patch. Fur soft; the coronal patch on the back of the head small, black or brown; crest black. General colour golden fulvous or greyish fulvous; limbs and tail dark brown; beard golden-red. Varieties of this species are sometimes entirely fulvous, with the forehead white; others are entirely albino. DISTRIBUTION.--Bolivia. IV. THE SMOOTH-HEADED CAPUCHIN. CEBUS MONACHUS. _Cebus monachus_, F. Cuv., Hist. Nat. Mammif., livr. xix. (1820). _Le Saï a grosse tête_, male, F. Cuvier, _loc. cit._ _Cebus xanthocephalus_, Spix, Sim. et Vespert., Bras., p. 6, pl. 3 (1823); Gray, Cat. Monkeys Brit. Mus., p. 50 (1870).