The Descent of Man

that the males use these horns for fighting together;
for "an unbroken one can rarely be got,
and occasionally one may be found with the
point of another jammed into the broken place."
(6. Mr. R. Brown, in 'Proc. Zool. Soc.' 1869, p.
553. See Prof. Turner, in 'Journal of Anat. and
Phys.' 1872, p. 76, on the homological nature of
these tusks. Also Mr. J.W. Clarke on two tusks
being developed in the males, in 'Proceedings
of the Zoological Society,' 1871, p. 42.) The
tooth on the opposite side of the head in the
male consists of a rudiment about ten inches in
length, which is embedded in the jaw; but sometimes,
though rarely, both are equally developed
on the two sides. In the female both are
always rudimentary. The male cachalot has a
larger head than that of the female, and it no
doubt aids him in his aquatic battles. Lastly, the
adult male ornithorhynchus is provided with a
remarkable apparatus, namely a spur on the
foreleg, closely resembling the poison-fang of a
venomous snake; but according to Harting, the