144 ELEPHANTS 



only five cross-ridges on the biggest and these ridges 

 tend to divide into separate cones (Fig. 13). So here, too, 

 we are approaching the ordinary mammals, of which we 

 may keep the pig and the tapir in mind as samples. But 

 the Mastodons still had the great trunk and huge tusks of 

 the elephants. 



Next we must look at Tetrabelodon (Fig. 17), and it is 

 this creature which has really revealed the history of the 

 strange metamorphosis by which elephants were produced. 

 The Tetrabelodon is known as " the long-jawed masto- 

 don," because, as was shown in a wonderfully well-preserved 

 skeleton from the Lower Pliocene of the centre of France, 

 set up in the Paris Museum, it had a lower jaw of 

 enormous length, ending in two large horizontally directed 

 teeth (Fig. 17). Instead of a lower jaw a foot long, as 

 in an elephant or in the common kind of mastodon this 

 long-jawed kind had a lower jaw 5ft. or 6ft. long! The 

 tusks of the upper jaw were large, and nearly horizontal 

 in direction, bent downwards a little on each side of 

 the long lower jaw. This lower jaw seemed incompre- 

 hensible, almost a monstrosity until it occurred to me 

 that it exactly corresponds to the elongated upper lip and 

 nose which we call the elephant's trunk and that the 

 trunk of " Tetrabelodon " must have rested on his long 

 lower jaw. In descending to Tetrabelodon we leave 

 behind us the elephants with hanging unsupported trunk ; 

 the lower jaw here is of sufficient length to support 

 the great trunk. When the lower jaw shortened in the 

 later mastodons and elephants the trunk did not shorten 

 too, but remained free and depending, capable of large 

 movement and of grasping with its extremity. Photo- 

 graphs, casts, and actual specimens of the extraordinary 

 skull of the long-jawed mastodon or Tetrabelodon and of 

 the creatures mentioned below may be seen in the Natural 

 History Museum. 



