196 THE POPULAR SCIENCE MONTHLY. 



ruminants, represented in our day by the oxen, sheep, goats, and 

 antelopes, the bony core or heart of the horn is protected by a 

 sheath of agglutinated hair, which continues to increase by layers 

 during life. This last form of horn is never shed, but persists 

 through the whole of the animal's existence. 



Historically, we know that the earliest ruminants, whose re- 

 mains are preserved for us in Tertiary strata, were quite hornless ; 

 and the gradual evolution of horns and antlers, from the simplest 

 to the most complex, has been traced out in full through succes- 

 sive geological ages by Gaudry, Boyd Dawkins, and other biolo- 

 gists. We can follow in detail the origin and rise of each tine 

 and spike from the mere boss or knob on the forehead of the an- 

 cestral form to the branching horns of the reindeer, the wapiti, 

 and the Irish elk. The camel, therefore, in its lack of horns rep- 

 resents for us an early undeveloped stage of the ruminant type, 

 when the ruminants had as yet only just diverged from the com- 

 mon ancestors of the horses and pigs. Darwin has shown that 

 horns and other familiar offensive weapons (especially when pe- 

 culiar to the males alone, as is the case with the antlers of stags) 

 have been developed in the struggle for mates, and are a necessary 

 result of sexual selection. But all such ornaments belong to the 

 higher and later stages of animal life, and are wholly wanting in 

 the unarmed, undecorated, ugly camel. He is, in fact, a ruminant 

 on which the higher types of selection have been little exercised, 

 though, as we shall presently see, his special adaptations for a 

 desert-life have been carried very far in particular directions, and 

 so have enabled him to hold out bravely in his own narrow and 

 restricted field against all more advanced and more highly spe- 

 cialized animals. 



The teeth of the camels and of their allies the llamas tell the 

 same tale in a somewhat different fashion. In all the higher rumi- 

 nants — giraffes, deer, oxen, antelopes, and goats alike — the weapons 

 of offense are the horns or antlers, and the teeth have almost or 

 entirely ceased to be used in fighting. They have also undergone 

 certain profound modifications of shape and arrangement (inter- 

 esting only to the technical anatomists), which fit them for crop- 

 ping grass or other low herbage, but get rid to a great extent of 

 their tearing powers. On the other hand, there is one other 

 group of ruminants besides the camels which is destitute of horns 

 — the little group of musk-deer — and in these pretty, small crea- 

 tures the canine teeth have been developed into long protruding 

 tusks, which thus take the place of horns as offensive weapons, 

 and are used by the males in their single combats for the posses- 

 sion of their mates. But, in the camels and llamas, no special 

 fighting-weapon of any sort exists. When camels fight at all — 

 which is very rarely — they fight merely by simple biting. They 



