240 THE MAMMALIA. 



have differentiated much more from the original 

 form than the other plant-eaters ; but even in the 

 case of these latter, a similar course from the 

 general disposition to the specialised form of to-day 

 has been pointed out. Thus, at the close of this 

 short chapter, our elephants cannot any longer be 

 said to stand as inexplicable wonders of creation. 



In the Middle Eocene deposits westwards of the 

 Eocky Mountains, there have been discovered, among 

 many other animal forms, numerous remains of 

 powerful plant-eaters of the size of elephants ; their 

 skull possessed two or three pairs of horns, and 

 the upper jaw showed gigantic canines (Fig. 44). 

 These Dinocerata are believed by Marsh and Cope 

 (and with some degree of probability) to be de- 

 scendants of the Coryphodonta (see above, p. 199), 

 and although the possibility of their being related 

 to trunked -animals is not excluded, still meanwhile 

 it is a mere vague analogy. The Brontotheriae 

 from the Lower Miocene eastwards of the Eocky 

 Mountains, which are likewise colossal creatures, 



half of the jaw), the increased slowness in the succession of the 

 teeth, and the corresponding increase in the number of ridges, 

 in short, the dentine which by degrees becomes worn off point to 

 the fact that the later mastodons had discontinued the mode of 

 life practised by their ancestors, and had adapted themselves to 

 a life on land.' 



