104 
sexual selection: birds. 
PaR 1 
It 
f stiec’^ 
sion that as vocal and instrumental organs are ot 4 
service only to the males during their courtship) i|( j 
organs were developed through sexual selection ^ 
continued use in this sex alone — the successive 
tions and the effects of use having been from th® ^ 
limited in their transmission in a greater or less d e o 
to the male offspring. ^ \y 
$ 
tits* 
Many analogous cases could be advanced ; llir 
J}. 
stance the plumes on the head, which are g eDe ^ of 
longer in the male than in the female, someth® 1 ' j„ 
equal length in both sexes, and occasionally abse’h^ 
the female, — these several cases sometimes occ®^ , ( i 
in the same group of birds. It would be difr 0 " ^ 
account for a difference of this kind between the ^ ^ 
on the principle of the female having been beneth^ 
possessing a slightly shorter crest than the male, 
consequent diminution or complete suppression i,]e 
natural selection. But. I will take a more fa 1° 
case, namely, the length of the tail. The 
of the peacock would have been not only inco»' r 
but dangerous to the peahen during the period o 
bation and whilst accompanying her young- . (I' 1 
there is not the least a priori improbability t ^ 
development of her tail having been checked t 
natural selection. 
•I)®!' 
But the females of van 0111 ’ 
sauts, which apparently are exposed on their op 1 ’ 1 ^. 
/ 
to as much danger as the peahen, have tail- 0 ^ 
siderable length. The females as well as f' 10 
of the Menura euperba have long tails, and fluff 
a domed nest, which is a great anomaly in so 
m 
.iii. 
bird. Naturalists have wondered how the fc®® 1 ^t 1 
nura could manage her tail during incubation > 
— ^ s i^ ( 
been dangerous to tliem during incubation. He adds, tb»^ 
view may possibly account for the inferiority of the femal e 
in plumage. 
