Recognition Colours 



for if the two sides of an animal were unlike, 

 and the diversity of colouration among domestic 

 animals occurred in a wild state, easy recognition 

 would be impossible among numerous closely 

 allied forms." 



As examples of recognition colouration, Wallace 

 cites, among others, the white upturned tail of the 

 rabbit a " signal flag of danger," the conspicuous 

 white patch displayed by many antelopes, the 

 white marks on the wing- and tail-feathers of the 

 British species of butcher-birds, the stone-chat, 

 the whin-chat, and the wheat-ear. 



Wallace therefore asserts, firstly, that recog- 

 nition marks not only help herbivorous animals 

 to keep together, but act as a danger signal ; the 

 member of a flock which first catches sight of the 

 enemy takes to its heels, displaying its white 

 flag, which is the signal of danger to the other 

 members of the flock. Secondly, that recog- 

 nition marks prevent the evils of infertile crosses. 

 Thirdly, that the necessity of being able to recog- 

 nise one another has rigidly preserved bilateral 

 symmetry among animals in a state of nature. 



As regards assertion number one, we would 

 point out that where a flock of herbivora is being 

 stalked by a beast of prey, the member of the 

 flock nearest to the enemy that is to say, the 

 hindmost member will probably be the first to 

 observe him. As that creature will be more 

 unfavourably situated for escape than the rest of 



253 



