v COLOURS OF ANIMALS 373 
ing in the female may lead to more contrasted markings. 
Mr. Darwin thinks that here the males have selected 
the more beautiful females; although one chief fact in 
support of his theory of conscious sexual selection is, that 
throughout the whole animal kingdom the males are usually 
so ardent that they will accept any female, while the females 
are coy and choose the handsomest males, whence it is 
believed the general brilliancy of males as compared with 
females has arisen. 
Perhaps the most curious cases of sexual difference of 
colour are those in which the female is very much more gaily 
coloured than the male. This occurs most strikingly in some 
species of Pieris in South America, and of Diadema in the 
Malay islands ; and in both cases the females resemble species 
of the uneatable Danaide and Heliconidz, and thus gain a 
protection. In the case of Pieris pyrrha, P. malenka, and P. 
lorena, the males are plain white and black, while the females 
are orange, yellow, and black, and so banded and spotted as 
exactly to resemble species of Heliconide. Mr. Darwin 
admits that these bright colours have been acquired for 
protection ; but as there is no apparent cause for the strict 
limitation of the colour to the female, he believes that it has 
been kept down in the male by its being unattractive to her. 
This appears to me to be a supposition opposed to the whole 
theory of sexual selection itself. For this theory is, that 
minute variations of colour in the male are attractive to the 
female, have always been selected, and that thus the brilliant 
male colours have been produced. But in this case he thinks 
that the female butterfly had a constant aversion to every 
trace of colour, even when we must suppose it was constantly 
recurring during the successive variations which resulted in 
such a marvellous change in herself. But the case admits of 
a much more simple interpretation. For if we consider the 
fact that the females frequent the forests where the Heli- 
conidsz abound, while the males fly much in the open and 
assemble in great numbers with other white and yellow 
butterflies on the banks of rivers, may it not be possible 
that the appearance of orange stripes or patches would be as 
injurious to the male as it is useful to the female, by making 
him a more easy mark for insectivorous birds among his 
