400 MY LIFE [Chap. 



very destructive to eggs and young birds. I also point out 

 that there are here comparatively few other groups of fruit- 

 eating birds like the extensive families of chatterers, tanagers, 

 and toucans of America, or the barbets, bulbuls, finches, 

 starlings, and many other groups of India and Africa, while 

 in all those countries monkeys, squirrels, and other arboreal 

 mammals consume enormous quantities of fruits. It is clear, 

 therefore, that in the Australian region, especially in the 

 forest-clad portions of it, both parrots and pigeons have 

 fewer enemies and fewer competitors for food than in other 

 tropical regions, the result being that they have had freer 

 scope for development in various directions leading to the 

 production of forms and styles of colouring unknown 

 elsewhere. It is also very suggestive that the only other 

 country in which black pigeons and black parrots are found 

 is Madagascar, an island where also there are neither 

 monkeys nor squirrels, and where arboreal carnivora or fruit- 

 eating birds are very scarce. The satisfactory solution of 

 these curious facts of distribution gave me very great 

 pleasure, and I am not aware that the conclusions I arrived 

 at have been seriously objected to. 



Before I had written these two papers I had begun the 

 study of my collection of butterflies, and in March, 1864, 

 I read before the Linnean Society a rather elaborate paper 

 on " The Malayan Papilionidae, as illustrating the Theory of 

 Natural Selection." This was published in the Society's 

 Transactions, vol. xxv., and was illustrated by fine coloured 

 plates drawn by Professor Westwood. I reprinted the intro- 

 ductory portion of this paper in the first edition of my " Con- 

 tributions to the Theory of Natural Selection" in 1870, but 

 in later editions it was omitted, as being rather too technical 

 for general readers, and not easily followed without the 

 coloured plates. I will therefore give a short outline of its 

 purport here. 



I may state for the information of non-entomological 

 readers that the Papilionidae form one of the most extensive 

 families of butterflies, and from their large size, elegant forms,, 



