318 THE STRUCTURE AND LIFE OF BIRDS chap. 



produced, and if the sexes show a difference in adorn- 

 ment, it is almost always the male that is more 

 brightly coloured. In many butterflies, and in some 

 fishes and crustaceans, there are such differences. 

 Among sea-urchins and starfish there is thought to be 

 in some cases a superiority in point of colour in the 

 male over the female. 1 It is very important, if we 

 are to come to a right conclusion upon this question, 

 that all the facts should be considered, and one of the 

 most important facts is this which Professor Geddes has 

 emphasized, that in many of the lower animals, and as 

 a rule among the higher, we find the male possessing 

 some superior adornment. Here we have an undoubted 

 tendency, however we may seek to account for it. 

 But to explain the Peacock's enormous plumes we 

 require something further. We want to know why 

 the regulating law of the Survival of the Fittest has 

 not reduced their growth. If we ask why a Peacock 

 is encumbered by a train that may easily lose him 

 his life, it is no answer to be told that in a certain 

 species of crustacean {Squilla sty lifer a for instance) 

 the male is rather more brilliantly coloured than the 

 female. 



Mr. Stolzmann has, I believe, supplied the clue to 

 this puzzle. According to him it is advantageous to 

 the species that the number of cock-birds should be 

 kept down, and their grand plumage helps towards 

 this end. This is an extension of Dr. Wallace's view 

 that it is the female which mainly needs protection. 

 Mr. Stolzmann maintains that the cock-bird in many 

 species not only needs no protection, but that it is 

 1 See Beddard's Animal Coloration, p. 255. 



