The Descent of Man

jaw, or in both, are much larger in the males
than in the females, or are absent in the latter,
with the exception sometimes of a hidden rudiment.
Certain antelopes, the musk-deer, camel,
horse, boar, various apes, seals, and the
walrus, offer instances. In the females of the
walrus the tusks are sometimes quite absent. (4.
Mr. Lamont ('Seasons with the Sea-Horses,'
1861, p. 143) says that a good tusk of the male
walrus weighs 4 pounds, and is longer than
that of the female, which weighs about 3
pounds. The males are described as fighting
ferociously. On the occasional absence of the
tusks in the female, see Mr. R. Brown, 'Proceedings,
Zoological Society,' 1868, p. 429.) In the
male elephant of India and in the male dugong
(5. Owen, 'Anatomy of Vertebrates,' vol. iii. p.
283.) the upper incisors form offensive weapons.
In the male narwhal the left canine alone
is developed into the well-known, spirallytwisted,
so-called horn, which is sometimes
from nine to ten feet in length. It is believed