534 THE DESCENT OP MAN. 



dinary a manner as the adult male mandrill (C. mormon). The 

 face at this age becomes of a fine blue, -with the ridge and tip 

 of the nose of the most brilliant red. According to some authors, 

 the face is also marked with whitish stripes, and is shaded in 

 parts with black, but the colors appear to be variable. On the 

 forehead there Is a crest of hair, and on the chin a yellow beard. 

 "Toutes les parties superieures de leurs cuisses et le grand espace 

 "nu de leurs fesses sont ogalement colores du rouge le plus vif, 

 '"avec un melaiige de bleu qui ne manque reellement pas 

 "d'elggance."" "When the animal is excited all the naked parts 

 become much more vividly tinted. Several authors have used the 

 strongest expressions in describing these resplendent colors, 

 which they compare with those of the most brilliant birds. An- 

 other remarkable peculiarity is that when the great canine teeth 

 are fully developed, immense protuberances of hone are formed 

 on each cheek, which are deeply furrowed longitudinally, and 

 the naked skin ovfer them is brilliantly-colored, as just described. 

 (Fig. 69.) In the adult females and in the young of both sexes 

 these protuberances are scarcely perceptible; and the naked parts 

 are much less bright colored, the face being almost black, tinged 

 with blue. In the adult female, however, the nose at certain regu- 

 lar intervals of time becomes tinted with red. 



In all the cases hitherto given the male is more strongly or 

 brighter colored than the female, and differs from the young of 

 both sexes. But as with some few birds it is the female which is 

 brighter colored than the male, so with the Rhesus monkey (Ma- 

 cacus rhesus) the female has a large surface of naked skin round 

 the tail, of a brilliant carmine red, which, as I was assured by 

 the keepers in the Zoological Gardens, periodically becomes even 

 yet more vivid, and her face also is pale red. On the other hand, 

 in the adult male and in the young of both sexes (as I saw in 

 the Gardens), neither the naked skin at the posterior end of the 

 body, nor the face, show a trace of red. It appears, however, 

 from some published accounts, that the male does occasionally, 

 or during certain seasons, exhibit some traces of the red. Al- 

 though he is thus less ornamented than the female, yet in the 

 larger size of his body, larger canine teeth, more developed whis- 

 kers, more prominent superciliary ridges, he follows the common 

 rule of the male excelling the female. 



I have now given all the cases known to me of a difference in 

 color between the sexes of mammals. Some of these may be 

 the result of variations confined to one sex and transmitted to 



"■ Gervais, 'Hist. Nat, des Mammiferes,' 1854, p. 103. Figures are given 

 of the skull of the male. Also, Desmarest, 'Mammalogie,' p. 70. Geof- 

 frey St.-Hilaire and F. Cuvier, 'Hist. Nat. des Maium.' 1824, torn. L 



