Obliterative Colouring 
the white fur of the back and the dark fur of the 
sides. Similarly the crocodiles are supposed to 
mistake a flamingo for the sky at sunrise or at 
sunset ! 
There is doubtless something in this theory of 
obliterative colouration. 
Any one can see, by paying a visit to the South 
Kensington Museum, that an animal which is of 
a lighter colour below than above, is less con- 
spicuous in a poor light than it would be were 
it uniformly coloured. There is then no doubt 
that this scheme of colour, which is so common 
in nature, has some protective value. 
To this extent has Mr Thayer made a valuable 
contribution to zoological science. But when 
he informs us that obliterative colouring is a 
‘universal attribute of animal life,” we feel 
sorely tempted to poke fun at him. 
We would ask all those who believe in the 
universality of obliterative colouring to observe 
a flock of rooks wending their way to their 
dormitories at sunset. 
Let us now pass on to the examination of the 
more orthodox theories of animal colouration. 
OBJECTIONS TO THE THEORY OF CRYPTIC 
CoLoURING 
Before criticising the theory of cryptic colour- 
ing, we desire to state distinctly that we admit 
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