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Show 310 SEXUAL . SELECTION : l\1Al\Il\IALR. l'AHT II. until the animal is nearly maturo.'15 Tho naked skin of tho face differs wouderfully in colour in tho varions species. It is often brown or ilesh~colour, with parts perfe~tly white, and often as black as that of tho most sooty negro. In the Brachyurus the scarlet tint is brighter than that of tho most blushing Caucasian damsel. It is sometimes more di~tinctly orange than in any Mongolian, and in several species it is blue,. passing into violet or grey. In all the species known to Mr. Bartlett, in which the adults of both sexes have strongly-coloured faces, the colours are dull or absent during early youth. ~rhis likewise holds good with the Mandrill and Rhesus, in which the face and the posterior parts of tho body are brilliantly coloured in one sex alone. In these latter cases we have every reason to believe that tho colours wore acquired through sexual selection; and we are naturally led to extend tho same view to the foregoing species, though both sexes when adult have their faces coloured in the same manner. Although, according to our taste, many kinds of monkeys are far from beautiful, other species are universally admired for their elegant appearance and brjght colours. The Semnopithectts nemmus, though peculiarly coloured, is described as extremely pretty; tho orange-tinted face is surrounded by long whiskers· of glossy whiteness, with a line of chesnut-red over tho eyebrows; the fur on the back is of a delicate grey, with a square patch on tho loins, tho tail and the fore-arms all of a pure white; a gorget of chesnut surmounts the chest; the hind thighs are black, with the legs chesnutred. I will mention only two other monkeys on account of their beauty; and I have selected those as they present light sexual differences in colour, which renders it 43 llttios, ''rho Nnturalist on tho Amazons,' 1 G3, vol. ii. p. 310, CIIAI'. XVJlf. QUADiWl\1ANA. 311 in some degree probable that both sexes owe their elegant appearance to R 'Xnfl.l selection. In the moustaeho- monkey (Oe't·copithews cephus) tho general colour of the fur is mottled-greenish, with tho throat white; in the male the end of the tail is chcsnut; but the face is tho most ornamented part, tho skin boino· chiefly bluishgrey, shading into a blacki h tint beneath the eye.·, with the upper lip of a delicate blue, clothed on the lower edgo with a thin hlnck mon. tache; tho whiskers Fig. 7U. CercopiLb~cLl~ Vlmta (from l.lrtluu). |