The Descent of Man 



exertion of choice. When, however, we come 

 to the Arthropoda and Vertebrata, even I 

 lowest classes in these two great sub-kingdoms, 

 sexual selection has effected much; and it de- 

 serves notice that we here find the intellectual 

 faculties developed, but in two very distinct 

 lines, to the highest standard, namely in the 

 Hymenoptera [ants, bees, etc.], among the 

 Arthropoda [many insects, spiders, etc.], and 

 in the Mammalia, including man, among the 

 Vertebrata. 



In the most distinct classes of the animal 

 kingdom — in mammals, birds, fishes, insects 

 and even crustaceans — the differences between 

 the sexes follow almost exactly the same rules. 

 The males are almost always the wooers; and 

 they alone are armed with special weapons for 

 fighting with their rivals. They are generally 

 stronger and larger than the females, and are 

 endowed with the requisite qualities of courage 

 and pugnacity. They are provided, either 

 exclusively or in a much higher degree than the 

 females, with organs for vocal or instrv mental 

 music, and with odoriferous glands. They are 

 ornamented with infinitely diversified append- 

 ages and with the most brilliant or conspicuous 

 colors, often arranged in elegant pat! 

 while the females arc unadorned. When the 

 sexes differ in more important structures it is 

 the male which is provided with special smse- 

 organs for discovering the female, with : 

 motive organs for reaching her, and often with 

 59 



