CHARACTERS.--Face white; head grizzled grey, minutely punctulated with black, the hairs grey with black tips; outer side of fore-arm grizzled grey, but in some species golden; back {155}grizzled grey, washed with golden, the tips of the hairs black; tail short, thick and grey, but with the tip black. DISTRIBUTION.--The forests of Bolivia and Brazil. This is a common species, inhabiting the whole of the Peruvian Amazons, and may be met with on every stream. (_E. Bartlett._) HABITS.--Arboreal and gregarious, moving about in large numbers through the forest, feeding on insects--chiefly orthoptera and spiders--small birds, and fruits. II. THE BLACK-HEADED SQUIRREL-MONKEY. CHRYSOTHRIX ENTOMOPHAGA. _Callithrix entomophagus_, d'Orb., Voy. Amér. Mér., iv., Mamm. pl. 4 (1836). _Callithrix boliviensis_, d'Orb., Nouv. Ann. Mus., iii., p. 89 (1834). _Saimiris entomophagus_, d'Orb., Voy. Amér. Mér., iv., Mamm., text, p. 10 (1847); Is. Geoffr., Cat. Méth. Primates, p. 38 (1851). _Saimiri entomophagus_, Schl., Mus. Pays Bas, vii., p. 246 (1876). _Chrysothrix sciurea_ (nec L.), Frantz. in Wiegm. Arch. f. Nat., xxxix., p. 260 (1869). _Chrysothrix entomophagus_, Wagn., Ann. Nat. Hist., xii., p. 42 (1843); Gray, Cat. Monkeys Brit. Mus., p. 53 (1870). CHARACTERS.--Face grey, washed with yellow; ears haired; head black; hairs of back black, with long yellow tips, or yellow with black tips, producing a shade of brown washed with golden; outer side of upper part of arms and legs yellow, peppered with black; throat, under surface of body and inside of limbs yellowish-grey; tail long, black. {156}In some species the upper part of the head has a shade of yellow, caused by the colour of the lower half of the hairs showing through the black tips. DISTRIBUTION.--Bolivia; Veragua, Central America; and the warmer regions of Costa Rica, where it inhabits the humid forests. III. THE COMMON SQUIRREL-MONKEY. CHRYSOTHRIX SCIUREA. _Simia sciurea_, Linn., Syst. Nat., i., p. 43 (1766); Humb., Obs. Zool., p. 334 (var. _cassiquiarensis_). _Callithrix sciureus_, Geoffr., Ann. Mus., xix., p. 113 (1812). _Saimiri sciureus_, Cuv., Reg. An., p. 103, pl. 1 (1829); Schl., Mus. Pays Bas, vii., p. 242 (1876). _Chrysothrix lunulata_, Geoffr., Arch. Mus., iv., p. 18 (1844). _Chrysothrix sciurea_, Wagner in Schreb., Säugth. Suppl., v., p. 120, pl. 9, (1855); Gray, Cat. Monkeys Brit. Mus., p. 53 (1870); Sclater, P. Z. S., 1880, p. 395. _Chrysothrix nigrivittata_, Wagn., Abh. bay. Ak. München, v., p. 461. CHARACTERS.--Smaller than the two preceding species; face greyish-white; chin round and prominent; head blackish-grey; back grey, or grey washed with gold, the basal part of the hairs golden and the tips black; outer side of the fore-arm yellow; tail long, slender, grizzled grey, with the tip black. Length of the body, 10 inches; of the tail, 14 inches.