Recognition Colours 
to India, where they are replaced as residents by 
the Shaheen (fako peregrinator) and Indian 
Hobby (/. severus). Both these differ from the 
migratory forms by being blacker above and 
chestnut below, instead of cream colour. Thus 
the resemblance occurs in each race. A similar 
distinction, as noted by Blyth, exists between 
the Common Swallow (fzrundo rustica) and the 
Swallow (4. tyt/erz) of Eastern Asia, the latter 
having the whole ventral surface rufous instead 
of only the throat. Yet no one will suggest that 
swallows mimic falcons, or that there is mimicry 
between the peregrine and hobby. It is obvious 
that such parallel changes occur independently 
of mimicry. 
The Water-rail (Radlus aguaticus) and Baillon’s 
Crake (Porzana baillont) of Europe are distin- 
guished from their allies of Eastern Asia by 
having the sides of the head plain grey, whereas 
the Eastern Asiatic forms (A. zzdicus and P. 
pusilla) have a brown streak along each side of 
the face. Here, again, we have an instance of 
birds of the same family varying together with 
geographical distribution. 
‘“ RECOGNITION ” CoLouRS 
One of the prettiest conceits of the Wallaceian 
school of zoologists is the theory of recognition 
markings. 
“Tf,” writes Wallace, on page 217 of Darwznism, 
251 
