56 THE THEORY OF NATURAL SELECTION 
Examples of this kind in which the shape of an 
animal leads to its concealment are less numerous 
than those in which protection is afforded by an obscure 
pattern or inconspicuous colour. Indeed, some re- 
semblance between the colour of an animal and its 
surroundings is to be traced in the majority of the 
members of many groups. Familiar examples are 
afforded by the white colour of animals which live in 
snow, the tawny grey colour of most desert species, 
the green of grass-frequenting animals, and so on. It 
is perhaps not quite certain that in some of these cases 
the peculiar colour is not evoked by the direct action 
of some cause which affects different species in the same 
way; but such a cause awaits discovery, and in the 
meantime natural selection has certainly a strong 
claim to be regarded as the proper explanation. 
A more strict use of the term mimicry, however, is 
to restrict it to cases where one species apes the colour 
pattern or other external character proper to another 
species which inhabits the same region ; and the idea 
of mimicry has been put forward as especially appro- 
priate in cases where the mimicked species is common, 
and can be thought to possess some special means of 
protection. Numerous supposed examples of this 
phenomenon have been described among insects, espe- 
cially in the case of various butterflies from Africa, 
Malaya, and South America. It would be beyond the 
scope of this work to do more than call attention to the 
fascinating subject, the literature of which includes a 
large number of papers to be found in the Proceedings 
of the Linnean Society and elsewhere. For a general 
