6S0 THE DESCENT OF MAN. 



chestnut-red over the eyebrows; the fur on the back is of a 

 delicate gray, with a square patch on the loins, the tail 

 and the fore arms being of a pure white; a gorget of chest- 

 nut surmounts the chest; the thighs are black, with the 

 legs chestnut-red. I will mention only two other monkeys 

 for their beauty; and I have selected these as presenting 

 slight sexual differences in color, which renders it in some 

 degree probable that both sexes owe their elegant appear- 

 ance to sexual selection. In the mustache-monkey 

 (Cercopifhecus cephus) the general color of the fur is mot- 

 tled-greenish with the throat white; in the male the end of 

 the tail is chestnut, but the face is the most ornamented 

 part, the skin being chiefly bluish-gray, shading into a 

 blackish tint beneath the eyes, with the upper lip of a deli- 

 cate blue, clothed on the lower edge with a thin black 

 mustache ; the whiskers are orange-colored, with the 

 upper part black, forming a band which extends back- 

 ward to the ears, the latter being clothed with whitish 

 hairs. In the Zoological Society's Gardens I have often 

 overheard visitors admiring the beauty of another monkey, 

 deservedly called Cercopifhecus diana (fig. 78); the general 

 color of the fur is gray; the chest and inner surface of the 

 fore legs are white; a large triangular defined space on the 

 hinder part of the back is rich chestnut; in the male the 

 inner sides of the thighs and the abdomen are delicate 

 fawn-colored, and the top of the head is black; the face 

 and ears are intensely black, contrasting finely with a white 

 transverse crest over the eyebrows and a long white peaked 

 beard, of which the basal portion is black.* 



In these and many other monkeys the beauty and sin- 

 gular arrangement of their colors, and still more the diver- 

 sified and elegant arrangement of the crests and tufts of 

 hair on their heads, force the conviction on my mind 

 that these characters have been acquired through sexual 

 selection exclusively as ornaments. 



Summary. The law of battle for the possession of the 

 female appears to prevail throughout the whole great class 

 of mammals. Most naturalists will admit that the greater 



* I have seen most of the above monkeys in the Zoological 

 Society's (hardens. The description of tlie Semnopithecus nemmus is 

 taken from Mr. \V. C. Martin's "Nat. Hist, of Mammalia," 1841, p. 

 460; see also pp. 475. 523. 



