'JO CALIFORNIA ACADEMY OF SCIENCES. 



same species. A bird might accordingly develop a 

 brilliant scarlet color in its plumage through the instru- 

 mentality of sexual selection, while the female, through 

 partial inheritance, would be colored yellow upon cor- 

 responding parts of the body. In the same manner 

 various colors in one sex might be imperfectly inherited, 

 producing a female bird but little inferior to her mate, 

 although quite differently marked. The instance of the 

 upland goose {Bernicla luugdlanica) in which "the 

 female is a rich brown diversified by white marks, while 

 the male is black and white," would be a case in point. 

 To the suggestion that the structure of the feather offers 

 greater facilities mechanically, for the display of color, 

 the objection has already been raised that only the tip 

 of the feather is colored. In another connection I have 

 suggested * that the absence of brilliant colors in mam- 

 mals, may be due to the fact that they are characteristi- 

 cally nocturnal in their habits, and the faculty of color 

 perception would very naturally be less exercised and 

 less highly developed than among birds. That the 

 color of birds may be influenced by the removal of the 

 sexual organs is an undoubted fact, but it does not 

 throw any light upon the origination of the color. 

 Even though a color had been developed by sexual selec- 

 tion, it would eventually become an attribute of one sex 

 only, and might be expected to change if the bird were 

 unsexed. 



Prof. Beddard also calls attention to the difficulty of 

 believing in a highly developed esthetic sense, which has 

 been urged by Wallace with such force. He alludes to the 

 excitability during the breeding season of animals among 

 which there is no pairing, but this does not appear to be 

 as significant as he imagines. Granting it to be a fact 

 that low forms of life do show signs of excitability 



*Zoe, ii, p. 209. 



