The Descent of Man

for having looked over these four chapters on
birds, and the two following ones on mammals.
In this way I have been saved from making
mistakes about the names of the species, and
from stating anything as a fact which is known
to this distinguished naturalist to be erroneous.
But, of course, he is not at all answerable for the
accuracy of the statements quoted by me from
various authorities.)
CHAPTER XVII.
SECONDARY SEXUAL CHARACTERS OF
MAMMALS.
The law of battle—Special weapons, confined
to the males—Cause of absence of weapons in
the female—Weapons common to both sexes,
yet primarily acquired by the male—Other uses
of such weapons—Their high importance—
Greater size of the male—Means of defence—