420 
SEXUAL SELECTION. 
Pakt II. 
times been coloured brilliantly so as to imitate other 
protected species inhabiting the same district. When 
the sexes resemble each other and both are obscurely 
coloured, there is no doubt that they have been in a 
multitude of cases coloured for the sake of protection. 
So it is in some instances when both are brightly 
coloured, causing them to resemble surrounding objects 
such as flowers, or other protected species, or indirectly 
by giving notice to their enemies that they are of an 
unpalatable nature. In many other cases in which the 
sexes resemble each other and are brilliantly coloured, 
especially when the colours are arranged for display, we 
may conclude that they have been gained by the male 
sex as an attraction, and have been transferred to both 
sexes. We arc more especially led to this conclusion 
whenever the same type of coloration prevails through- 
out a group, and we find that the males of some species 
differ widely in colour from the females, whilst both 
sexes of other species are quite alike, with intermediate 
gradations connecting these extreme states. 
In the same manner as bright colours have often 
been partially transferred Jfom the males to the females, 
so it has been with the extraordinary horns of many 
lamellicorn and some other beetles. So, asain, the 
vocal or instrumental organs proper to the males of 
the Homoptera and Orthoptera have generally been 
transferred in a rudimentary, or even in a nearly perfect 
condition to the females; yet not sufficiently perfect to 
be used for producing sound. It is also an interesting 
fact, as bearing on sexual selection, that the stridulating 
organs of certain male Orthoptera are not fully deve- 
loped until the last moult ; and that the colours of cer- 
tain male dragon-flies are not fully developed until 
some little time after their emergence from the pupal 
state, and when they are ready to breed. 
