AN INVISIBLE MONKEY 
In most English dictionaries the verb “to mimic” has for 
its synonyms “to ape, imitate, counterfeit, or mock”; and 
it is thus intimately connected with the monkey tribe, whose 
imitations of human gestures and actions form one of their 
most prominent characteristic features. Till a few years 
ago naturalists were, however, totally unacquainted with 
any instance among these animals of “mimicry” in its 
scientific sense—that is to say, no case was known where 
a monkey, for the sake of protection, resembled in form 
or coloration either some other animal or an inanimate 
object. During a journey to Mount Kenya and Lake 
Barengo, in East Africa, Dr. J. W. Gregory, late of the 
Natural History Museum, discovered that the peculiar type 
of coloration characterising certain African monkeys is 
protective in its nature, and that these monkeys, when 
in their native haunts, are thereby rendered practically 
invisible. 
The monkeys in question (one of which is represented 
in the annexed plate) are known to the natives of certain 
districts of East Africa by the name of “guereza.”” They 
belong to the group of thumbless apes (Co/odus), which 
are restricted to the African continent, where they take the 
place of the langurs, or sacred apes, of India and other 
Oriental countries. From the other thumbless apes the 
guerezas (or those species to which that name properly 
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