420 SEXUAL SELECTION. Fart 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 are 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 from the males to the females, 

 so it has been with the extraordinary horns of many 

 lamellicorn and some other beetles. So, again, 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. 



