SEXUAL SELECTION. 197 



strong on the wing and mount high in the air. In 

 birds such marked differences of colour are not required, 

 owing to their higher organization and more perfect 

 senses, which render recognition easy by means of a 

 combination of very slight differential characters. 



This principle may perhaps, however, account for 

 some anomalies of coloration among the higher animals. 

 Thus, while admitting that the hare and the rabbit are 

 coloured protectively, M r. Darwin remarks that the latter 

 while running to its burrow, is made conspicuous to the 

 sportsman, and no doubt to all beasts of prey, by its 

 upturned white tail. But this very conspicuousness 

 while running away, may be useful as a signal and guide 

 to the young, who are thus enabled to escape danger by 

 following the older rabbits, directly and without hesita- 

 tion, to the safety of the burrow ; and this may be the 

 more important from the semi-nocturnal habits of the 

 animal. If this explanation is correct, and it certainly 

 seems probable, it may serve as a warning of how impos- 

 sible it is, without exact knowledge of the habits of an 

 animal and a full consideration of all the circumstances, 

 to decide that any particular coloration cannot be pro- 

 tective or in any way useful. Mr. Darwin himself is not 

 free from such assumptions. Thus, he says : " The 

 zebra is conspicuously striped, and stripes cannot afford 

 any protection on the open plains of South Africa." 

 But the zebra is a very swift animal, and, when in herds, 

 by no means void of means of defence. The stripes 

 therefore may be of use by enabling stragglers to distin- 

 guish their fellows at a distance, and they may be even 

 protective when the animal is at rest among herbage 

 the only time when it would need protective colouring. 



