Coloration of the Mouths and Eggs of Birds. 265 



generally on the problems and generally-accepted theories of 

 animal coloration. 



All I will do here, therefore, is, first to give a brief 

 description of such few of these theories, and of my own 

 resultss, as bear more especially on the appearance of the 

 eggs and mouths of birds : this to avoid misunderstanding ; 

 and to discuss the explanation of the problems that their 

 appearance presents ; and, secondly, to describe in detail my 

 experiments on some egg-eating animals. I hope in a later 

 paper to give a fuller account of some of the other results 

 and to discuss their bearing on the coloration of adult 

 birds. 



I take this opportunity to thank very warmly Mr. D. P. 

 J. Odendaal, who helped to procure the eggs used in 

 experiment ; Mr. H. M. Wallis, who since I first stated 

 my results at the April meeting of the B. O. C. has sent 

 me much information of a most interesting character ; 

 and, for their kind permission to work at the eggs in their 

 respective museums and their help while I was doing so, 

 Mr. W. R. Ogilvie-Grant, Lord Rothschild and Dr. Hartert, 

 Dr. Peringuey (Cape Town), Mr. F. W. Fitzsimons (Port 

 Elizabeth), and Mr. E. C. Chubb (Durban). To no one am 

 I more indebted than to Mr. G. A. Boulenger, who, while 

 I was working at my nestlings in the Natural History 

 Museum, placed every facility afforded by the Reptile-room 

 at my disposal, and helped me much with information and 



2. Theories and Results referred to later. 



Concealing or procryptic coloration, with some beautiful 

 illustrations amongst birds, their nestlings and their eggs, 

 is, nevertheless, not worth going into here, except to draw 

 attention to the fact that, where a second, inner, surface is 

 available for exposure, concealing coloration often forms 

 a shield under which the most conspicuous warning (or 

 other) coloration is developed and safely carried by animals 

 whose unpleasantness to enemies is not so marked that they 



