Mimetic Insects 293 
so that it even deceived the acute senses of the foraging ants; 
other species, belonging to a closely-related genus (Ptero- 
chroza), imitate leaves in every stage of decay, some being 
faded-green, blotched with yellow; others, as in the species 
figured, resemble a brown withered leaf, the resemblance 
being increased by a transparent hole through both wings 
that looks like a piece taken out of the leaf. In many butter- 
flies that resemble leaves on the under side of their wings, the 
wings being raised and closed together when at rest so as to 
hide the bright colours of the upper surface, there are similar 
transparent spots that imitate holes; and others again are 
jagged at the edge, as if pieces had been taken out of them. 
MOSS INSECT 
Many chrysalides also have mirror-like spots that resemble 
holes; and one that I found hanging from the under side of 
a leaf had a real hole through it, formed by a horn that pro- 
jected from the thorax and doubled back to the body, leaving 
a space between. Another insect, of which I only found two 
specimens, had a wonderful resemblance to a piece of moss, 
amongst which it concealed itself in the daytime, and was 
not to be distinguished except when accidentally shaken out. 
It is the larval stage of a species of Phasma. 
The extraordinary perfection of these mimetic resem- 
blances is most wonderful. I have heard this urged as a 
reason for believing that they could not have been produced 
by natural selection, because a much less degree of resem- 
blance would have protected the mimetic species. To this 
it may be answered, that natural selection not only tends to 
pick out and preserve the forms that have protective resem- 
