HORNS AND ANTLERS. 235 



to us. In addition to the horns the skulls of the males 

 were armed with long and formidable tusks in the upper 

 jaw, somewhat like those found in certain extinct tigers. 



The above are the three great types of offensive 

 armature with which the skulls of existing Mammals 

 are provided, and they are all of them, as already 

 observed, found in the order of Hoofed Mammals, and 

 nowhere else, at the present day. If, however, we go 

 back to the long-distant Mesozoic epoch, or period at 

 which our chalk was deposited at the bottom of the 

 sea, we find that certain herbivorous species of the 

 gigantic reptiles known as Dinosaurs, which are de- 

 scribed in Chapter VIII., were provided with paired 

 bony horn-cores on their skulls (Fig. 41), so exactly 

 resembling those of our own Oxen that some of them 

 when found detached were actually described as belong- 

 ing to an extinct Bison. In the later Tertiary beds of 

 Australia we also find a huge tortoise with somewhat 

 similar horn-cores on its forehead ; and since the horn- 

 cores, both in this and the preceding instance, so closely 

 simulate in structure those of the Oxen, we may fairly 

 infer that they were similarly sheathed with true horns 

 during life. 



Thus we learn that in long past epochs not only was 

 the place of the larger herbivorous Mammals of the 

 present day taken by various forms of giant herbi- 

 vorous reptiles, but that those reptiles were actually 

 armed with weapons precisely similar to those of the 

 Mammals of the present day. So true is it that there 

 is " nothing new under the sun." 



