Selection by Females 
the males, or selection by the female of one 
among several admirers. Thirdly, that the 
female selects, as a rule, the most attractive of 
her suitors. 
The evidence upon which Darwin founds this 
theory may be thus summarised :— 
1. In cases where the sexes differ in appear- 
ance, or power of song, it is almost invariably 
the cock who is the more beautiful or the better 
singer, as the case may be. 
2. All male birds that possess accessory plumes 
or other attractions, make a most elaborate dis- 
play of these before the females at the mating 
season, hence “it is obviously probable that 
these appreciate the beauty of their suitors.” 
3. Darwin was able to cite specific instances 
in which the hens showed preference. 
In the case of polygamous species there can 
be no doubt that there is considerable competition 
among males for their wives. It cannot be said 
that the contention is so well established in the 
case of monogamous species. D. Dewar suggests 
that circumstances may occur in which the hens 
have to fight for the cock, or in which the male is 
in the happy position of being able to select his 
mate. He states his belief that in many cases 
the selection is mutual, as in the case of human 
beings. 
“JT have seen,” he writes, on page 13 of 
Birds of the Plains, “one hen Paradise Fly- 
393 . 
