SEXUAL SELECTION 



as organs of offence. The same observer remarks that rhi- 

 noceroses, in fighting, parry each other's sidelong blows 

 with their horns, which clatter loudly together, as do the 

 tusks of boars. Although wild boars fight desperately, they 

 seldom, according to Brehm, receive fatal wounds, as the 

 blows fall on each other's tusks, or on the layer of gristly 

 skin covering the shoulder, called by the German hunters 

 the shield; and here we have a part specially modified for 

 defence. With boars in the prime "of life (see Fig. 65) the 

 tusks in the lower jaw are used for fighting, but they be- 

 come in old age, as Brehm states, so much curved inward 

 and upward over the saout that they can no longer be used 

 ia this way. They may, 

 however, still serve, and 

 even more effectively, as 

 a means of defence. In 

 compensation for the loss 

 of the lower tusks as 

 ■weapons of offence, those 

 in the upper jaw, which 

 always project a little 

 laterally, increase in old 

 age so much in length 

 and curve so much up- 

 ward, that they can be 

 an 

 of six 



In the full-grown male Babirusa pig of Celebes (Fig. &Q) 

 the lower tusks are formidable weapons, like those of the 

 European boar in the prime of life, while the upper tusks 

 are so long and have their points so much curled inward, 

 sometimes even touchiog the forehead, that they are utterly 

 useless as weapons of attack. They more nearly resemble 

 horns than teeth, and are so manifestly useless as teeth that 

 the animal was formerly supposed to rest his head by hook- 



'f^fM^A'^' 



PiO. 05.— Head of Common Wild Boar, to prime 

 of life (from Brehm). 



used for attack. Nevertheless, 

 old boar is not so dangerous to man as one at the age 

 or seven years. °° 



»» Brehm, "Thierleben, " B. ii. s. 729-732. 

 Deaeent— Vol. II.— 11 



