PHYLETIC BRANCHES AMONG THE VERTEBRATES 179 



boscidians are represented in Europe, during the 

 second half of Tertiary times, by three chief and 

 parallel branches of gigantic creatures, the Ele- 

 phants, the Mastodons, and the Dinoiheria. Of 

 these three groups, the first was introduced very 

 late into Europe, coming from the Indian regions 

 at the end of the Pliocene ; the other two arrived 

 earlier, but no less suddenly, at the commencement 

 of the Miocene. They had, moreover, a very 

 different fate. The Dinoiheria became extinct in its 

 gigantic forms at the end of the Miocene, while the 

 Mastodons survived them through the whole of 

 the Pliocene, and one of their sub-branches even 

 rolonged itself in North America by a final species 

 hich appears to have existed at the time of Qua- 

 ternary man. The table of the evolution of the 

 Proboscidians in Europe, in Africa, and in North 

 America may be represented in five branches, as on 

 the following page.* 



This table shows clearly the manner in which 

 e must understand the evolution of a group by 

 parallel branches not in contact and having no 

 transitional form from one branch to another. It 

 shows also, as mentioned above, the different 

 destiny of each of these branches. Finally, it 

 enables us to appreciate the variable rate of their 

 evolution. Thus the branch Dmotherium changed 

 very little since its apparition in our countries 

 at the beginning of the Miocene until its ex- 

 tinction at the end of that period. Everything 



* I have left on one side the curious Stegodon of India, often con- 

 sidered as forming a bridge between the Mastodons and the Ele- 

 phants, because the stratigraphical level of their species is still very 

 uncertain. 



