Darwin s Theory of Sexual Selection 209 



of the body, which is confined to the male sex, is of the most 

 brilliant blue or green, and contrasts strikingly with the naked 

 skin on the hinder part of the body, which is vivid red. 



" Lastly, in the baboon family, the adult male of Cyno- 

 cephalus hamadryas differs from the female not only by his 

 immense mane, but slightly in the color of the hair and of 

 the naked callosities. In the drill (C. lencophceus)X)f\e. females 

 and young are much paler-colored, with less green, than the 

 adult males. No other member in the whole class of mam- 

 mals is colored in so extraordinary 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 fore- 

 head there is a crest of hair, and on the chin a yellow beard. 

 'Toutes les parties supdrieures de leurs cuisses et le grand 

 espace nu de leurs fesses sont dgalement colores du rouge le 

 plus vif, avec un melange de bleu qui ne manque r6ellement 

 pas d'el^gance.' When the animal is excited all the naked 

 parts become much more vividly tinted." 



Darwin sums up the evidence in regard to the differences 

 in color between the male and female in the following 

 statement : — 



" I have now given all the cases known to me of a differ- 

 ence in color between the sexes of mammals. Some of 

 these may be the result of variations confined to one sex 

 and transmitted to the same sex, without any good being 

 gained, and therefore without the aid of selection. We 

 have instances of this with our domesticated animals, as in 

 the males of certain cats being rusty-red, whilst the females 

 are tortoise-shell colored. Analogous cases occur in nature : 

 Mr. Bartlett has seen many black varieties of the jaguar, 

 leopard, vulpine phalanger, and wombat ; and he is certain 

 that all or nearly all these animals, were males. On the 



