PROTECTIVE AND AGGRESSIVE MIMICRY 265 



extent to which they are preyed upon by the higher 

 animals, their enormous fertility, and the rapidity 

 with which the generations succeed each other, are 

 reasons why natural selection operates more quickly 

 and more perfectly than in other animals, producing 

 mimetic resemblances or other forms of Protective 

 Kesemblance in number and fidelity of detail un- 

 equalled throughout organic nature. 



Protective Mimicry in Vertebrata 



Mimicry is by no means unknown among the Ver- 

 tebrate animals. Thus the brightly coloured snakes 

 of the genus Elaps, already alluded to, are closely 

 resembled by harmless snakes belonging to different 

 families. The names of several mimetic species, and 

 further instances of the same kind among African 

 snakes, will be found in Mr. Wallace's ' Darwinism.' 

 The same writer also gives many instances of Mimicry 

 in birds. Thus the powerful and aggressive friar- 

 birds in the Malay Archipelago are exactly mimicked 

 by weak and timid orioles, representative species of 

 both friar-bird and oriole occurring in several of 

 the islands. 1 



Two classes of Protective Mimicry 



Two classes may be distinguished among the pre- 

 ceding examples. In the vast majority of cases the 



1 Loc. tit. pp. 261-64. 



