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 
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