PEOTECTIVE COLOKATION. lO^ 



Mr. Jacoby's papers in the Proceedings of the Zoological Society 

 one cannot help being struck by the large absence of green 

 among the phytophagous Ooleoptera. There are plenty of 

 green tree-frogs, but, as has been already mentioned, there are 

 more that are not so uniformly coloured. Even about birds 

 living in tropical countries, and especially arboreal in their 

 habits, the most that can be said is that there are a good many 

 green species. 



Now, the reader must not assume that these few facts have 

 been brought together for the purpose of throwing discredit 

 upon the theory that a green coloration has been gradually 

 produced for protective purposes. Any one convinced of 

 the truth of this theory would at once triumphantly point 

 out a large number of omissions from the above very scanty 

 list ; it seems to me, however, that a prevalence of green 

 among arboreal animals cannot be proved; and thus there 

 might appear to be a certain weakness in the theory of 

 protective coloration as applied to these instances. 



In my own opinion the apparent weakness of the arguments 

 constitutes the real strength of the theory; it is precisely 

 because the sandy colour of desert animals and the trans- 

 parency of pelagic organisms is so universal, that some general 

 environmental cause appears to be necessary for the explanation 

 of the facts ; on the other hand, the picking and choosing among 

 arboreal animals savours distinctly of natural selection. There 

 are quite enough examples of green tree-frequenting creatures 

 to call for some theory to explain the facts, but there are not 

 too many to render a selection improbable. When a whole 

 group of animals shows a similar modification, adaptation 

 seems less likely. 



Deceptively-coloured African Mantids. 



Every naturalist traveller appears to have some instance to. 



