RESEMBLANCES AMONG ANIMALS. 123 



external form and colouring of animals is adapted to 

 be useful to them, either by concealing them from their 

 enemies or from the creatures they prey upon. It has, 

 I hope, been shown that the subject is one of much 

 interest, both as regard a true comprehension of the 

 place each animal fills in the economy of nature, and 

 the means by which it is enabled to maintain that 

 place; and also as teaching us how important a part 

 is played by the minutest details in the structure 

 of animals, and how complicated and delicate is the 

 equilibrium of the organic world. 



My exposition of the subject having been necessarily 

 somewhat lengthy and full of details, it will be as 

 well to recapitulate its main points. 



There is a general harmony in nature between the 

 colours of an animal and those of its habitation. 

 Arctic animals are white, desert animals are sand- 

 coloured ; dwellers among leaves and grass are green ; 

 nocturnal animals are dusky. These colours are not 

 universal, but are very general, and are seldom re- 

 versed. Going on a little further, we find birds, 

 reptiles, and insects, so tinted and mottled as exactly 

 to match the rock, or bark, or leaf, or flower, they 

 are accustomed to rest upon, and thereby effec- 

 tually concealed. Another step in advance, and we 

 have insects which are formed as well as coloured so 

 as exactly to resemble particular leaves, or sticks, or 

 mossy twigs, or flowers; and in these cases very 

 peculiar habits and instincts come into play to aid 

 in the deception and render the concealment more 



