SEXUAL COLOUR 87 
nesting cannot alone account for such great 
differentiation, for when males _ incubate, 
females are never more than slightly more 
conspicuously coloured. It appears, there- 
fore, that the difference in value between the 
sexes, or some other, factor, must be looked 
for to explain this. 
As with parental colour, so with sexual 
colour — conspicuous colours among preda- 
tory animals, or among night animals, would 
not be anticipated, nor is it found. 
So also sexual dimorphism should, accord- 
ing to the theory, not be found in aposematic 
animals, nor is it at all common; because, 
having few enemies, they are not very liable to 
attack. Sometimes secondary sexual char- 
acters occur before sexual maturity, as in the 
upland Goose (Chlaphaga Magellanica). In 
this case one would conclude that the society 
feels the great value of the female even at 
this early stage. 
Worthy of note and favouring the theory is 
the fact that in mimicry it is often only the 
female which seeks protection in this way ; 
the male, it would seem, purposely refraining 
from doing so, in order that, should the pair 
be attacked during mating or copulation, he 
will be destroyed at the saving of the female. 
