RESEMBLANCES AMONG ANIMALS. 1138 
while its companion of sober brown was looked upon 
as the female. I discovered, however, that the reverse 
is the case, and that the rich and glossy colours of 
the female are imitative and protective, since they 
cause her exactly to resemble the common Euplca 
midamus of the same regions, a species which has 
been already mentioned in this essay as mimicked 
by another butterfly, Papilio paradoxa. I have since 
named this interesting species Diadema anomala (see 
the Transactions of the Entomological Society, 1869, 
p. 285). In this case, and in that of Diadema misippus, 
there is no difference in the habits of the two sexes, 
which fly in similar localities; so that the influence 
of “external conditions” cannot be invoked here as 
it has been in the case of the South American Pieris 
pyrrha and allies, where the white males frequent 
open sunny places, while the Heliconia-like females 
haunt the shades of the forest. 
We may impute to the same general cause (the 
greater need of protection for the female, owing to 
her weaker flight, greater exposure to attack, and 
supreme importance)—the fact of the colours of female 
insects being so very generally duller and less conspi- 
cuous than those of the other sex. And that it is 
chiefly due to this cause rather than to what Mr. 
Darwin terms “sexual selection” appears to be 
shown by the otherwise inexplicable fact, that in the 
groups which have a protection of any kind inde- 
pendent of concealment, sexual differences of colour 
are either quite wanting or slightly developed. The 
I 
