. The descent of man, and selection in relation to sex. Evolution; Natural selection; Sexual selection in animals; Human beings -- Origin; Sexual dimorphism (Animals). Chap. XVIL] MEANS OF DEFENCE. 251 offspring alone; and thus the great inequality in size be- tween the sexes of the Scotch deer-hound may probably be accounted for. The males of some few quadrupeds possess organs or parts developed solely as a means of defence against the attacks of other males. Some kinds of deer use, as we have seen, the upper branches of their horns chiefly or ex- clusively for defending themselves; and the O
. The descent of man, and selection in relation to sex. Evolution; Natural selection; Sexual selection in animals; Human beings -- Origin; Sexual dimorphism (Animals). Chap. XVIL] MEANS OF DEFENCE. 251 offspring alone; and thus the great inequality in size be- tween the sexes of the Scotch deer-hound may probably be accounted for. The males of some few quadrupeds possess organs or parts developed solely as a means of defence against the attacks of other males. Some kinds of deer use, as we have seen, the upper branches of their horns chiefly or ex- clusively for defending themselves; and the Oryx ante- lope, as I am informed by Mr. Bartlett, fences most skil- fully with his long, gently-curved horns; but these are likewise used as organs of offence. Rhinoceroses, as the same observer remarks, in fighting parry each other's side- long blows with their horns, which loudly clatter together, as do the tusks of boars. Although wild- boars fight desperate- ly together, they sel- dom, according to Brehm, receive fatal blows, as these fall on each other's tusks, or on the layer of gristly skin covering the shoul- der, which the German hunters call the shield; and here we have a part specially modified for defence. With boars in the prime of life (see Fig. 63) the tusks in the lower jaw are used for fighting, but they become in old age, as Brehm states, so much curved inward and upward, over the snout, that they can no longer be thus used. They may, however, still continue to serve, and even in a still more effective manner, as a means of defence. In com- pensation for the loss of the lower tusks as weapons of offence, those in the upper jaw, which always project a. Fte^e:^ Fig. 63.—Head of common-wild hoar, in prime of life (from Brehm).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles,
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