46 LAND MAMMALS IN THE WESTERN HEMISPHERE 



a study of series of living animals, such as lizards and butter- 

 flies, in which the development of a definite scheme of coloura- 

 tion may be followed step by step. Young animals very fre- 

 quently retain more or less distinct traces of the ancestral 

 colouration, which disappear in the adult, for the develop- 

 ment of the individual is, in some respects at least, an abbre- 

 viated and condensed recapitulation of the history of the species. 

 In many mammals which, in the adult condition, have a solid 

 body-colour, the young are striped or spotted, a strong indi- 

 cation that these mammals were derived from striped or spotted 

 ancestors. Thus, the Wild Boar has a uniform body-colour 

 in the full-grown stage, but the pigs are longitudinally striped ; 

 many deer are spotted throughout life, as in the Fallow Deer, 

 the Axis Deer of India and others, but the great majority of 

 the species, including all the American forms, have uniform 

 colouration, while the fawns are always spotted. Lion cubs 



Fig. 5. — Fawns of the Mule Deer (Odocoileus hemionus). Compare with Fig. S3, 

 p. 167. (]}y perniiHsion of the N. Y. Zoolog. Society.) 



are also spotted and the adults have a uniform tawny colour, 

 and many such examples might be given. 



The study of colouration among existing animals has led 

 to the conclusion that in mammals the primitive colour- 



