SEXUAL SELECTION. 203 



therefore concludes are ornaments, developed through 

 selection of the larger-horned males by the females. 

 But it has been overlooked that these horns may be 

 protective. The males probably fly about most, as is 

 usually the case with male insects ; and as they gene- 

 rally fly at dusk they are subject to the attacks of 

 large-mouthed goatsuckers and podargi, as well as of 

 insect-eating owls. Now the long, pointed or forked 

 horns, often divergent, or movable with the head, 

 would render it very difficult for these birds to swallow 

 such insects, and would therefore be an efficient pro- 

 tection ; just as are the hooked spines of some stingless 

 ants and the excessively hard integuments of many 

 beetles, against the smaller insectivorous birds. 



Cause of the greater Brilliancy of some Female In- 

 sects. The facts given by Mr. Darwin to show that 

 butterflies and other insects can distinguish colours and 

 are attracted by colours similar to their own, are quite 

 consistent with the view that colour, which continually 

 tends to appear, is utilised for purposes of identifica- 

 tion and distinction, when not required to be modified 

 or suppressed for the purpose of protection. The 

 cases of the females of some species of Thecla, Calli- 

 dryas, Colias y and Hipparchia, which have more 

 conspicuous markings than the male, may be due to 

 several causes : to obtain greater distinction from other 

 species ; for protection from birds, as in the case of the 

 yellow-under wing moths ; while sometimes as in Hip- 

 parchia the lower intensity of colouring 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 



