Chap. XI. 
SUMMARY ON INSECTS. 
423 
anomalous cases, the females are more beautiful than 
the males. We shall often find, in the same group of 
birds, every gradation from no difference between the 
sexes, to an extreme difference. In the latter case we 
shall see that the females, like female insects, often 
possess more or less plain traces of the characters which 
properly belong to the males. The analogy, indeed, in 
all these respects between birds and insects, is curiously 
close. Whatever explanation applies to the one class 
probably applies to the other ; and this explanation, as 
we shall hereafter attempt to shew, is almost certainly 
sexual selection. 
END OF VOL. I. 
