46 THR r.AMF. OF RRITISM RAST AFRICA. 



raising bristles all over the boilv to appear larger, or pufTing out the neck or raising 

 a crest on the head. 



To return, however, to the hen bird. It is more sombre and duller coloured 

 than the cock, at times with good reason, but at other times it seems as if there was 

 small need for such precautionary measures. 



There seems to be little doubt that the eggs, young, and females of most of the 

 ground-nesting birds are directly coloured for protective purposes. It is not, as 

 a rule, that the hens themselves have any foes to fear. It is for the purpose of 

 letting the eggs, when exposed, remain undetected, and for concealing the young 

 from kites and hawks, while they themselves, if not also suitably coloured, would 

 di close the presence of the nest. Elxamples of these protectively coloured birds 

 and eggs are common, but nearly all those which might be termed wonderful 

 adaptations to their surroundings occur among these ground-laying birds, birds 

 which nest or merely scratch a hollow for their eggs on the surface of great open 

 prairies, moors, fens, or beaches. Other birds, as a rule, seem to trust more to skill 

 in concealing their nests than to any coloration of their own or of their eggs. 



As to sexual selection, where the inales alone have tufts, ornaments, crests, or 

 other appendages or colours unpossessed by the female, no doubt this theory may be 

 made to explain their presence. Apart from such ornamentation and the ground- 

 nesting birds and a few other instances of real protective coloration, it seems as 

 if the theories of sexual selection and protective coloration can be made to account 

 for the colours of but few birds. Where the colours of both sexes are the same 

 it is difficult to explain them by the first theory. Still less can colours utterly 

 out of harmony with their surroundings be accounted for by the second theory. 

 Nor does any theory of utility seem to answer the question. What, then, were the 

 determining factors in the coloration of such birds as rooks and crows, the snowy 

 owl (for night work), flamingoes, egrets, and a host of others ? No existing theory 

 seems to fittingly explain them, but it seems very clear that there must be other 

 agencies at work if the colours of the greater part of the bird world are to be 

 accounted for by rule. 



It is probable that conditions of climate and environment are amongst these 

 agencies at work. For most of the more brilliantly coloured birds are found in 

 tropical climes, and the more sombre-clad birds in colder countries. 



The dull hues prevalent in desert bird and other life have often been noticed, and 

 in many cases they are quite apart from any need for escaping observation or 

 concealment. 



Now to turn to mammals, and more especially to those known collectively as 



