COLOUR AND PROTECTION. 
225 
C« 
4 P- XVI. 
tyi". °^ er thirteen species, three belong to genera in 
jj. lt ^ the sexes usually differ from each other, yet they 
til'. 6 sexes alike. In the remaining ten species, 
differs from the female; but the diffei •ence is 
J! IUe ^ chiefly to the under surface of the plumage, 
i( h is concealed when the bird crouches on the 
0ol UlKl ; the head and back being of the same sand- 
°ured hue in both sexes. >So that in these ten 
the upper surfaces of both sexes have been 
kr i 0n aa ^ rendered alike, through natural selection, 
tli le sake ot protection; whilst the lower surfaces of 
'^ules alone have been diversified through sexual 
S( ^ ! ' tlou . for the sake of ornament. Here, as bot h 
I' f ' ft are equally well protected, we clearly see that the 
tj, l ' 68 have not been prevented through natural selcc- 
Wfi' 1 * 10111 inheriting the colours of their male parents : 
sit, 1°°^ to the law of sexually limited trausinis- 
! l; as before explained. 
hii/'/'ii parts of the world both sexes of many soft- 
especially those which frequent reeds 
or 
il] U . a ^ i'“ 
Co ,^ are obscurely coloured, bio doubt if their 
°' ] Irs had been brilliant, they would have been 
t| ( ! 1 n:| o re conspicuous to their enemies ; hut whether 
hi- 1 tints have been specially gained for the 
protection seems, as far as I can judge, rather 
still more doubtful whether such 
( 1 , 
« of 
C 11 '" 
It 
IS 
bi 
nt. 
tj nts can have been gained for the sake of orna- 
We must, however, bear in mind that male 
though dull-coloured, often differ much from 
' rQalea > as witl1 tlie C0 |n 'nou sparrow, and this 
N nr ”" 65 
tlq' ’ to tlle belief that such colours have been gained 
of I’!* 11 sexual selection, from being attractive. Many 
ii, soft-hilled birds are songsters ; and a discussion 
° rmer chapter should not be forgotten, in which 
' s shewn that the best songsters are rarely orna- 
u. 
