178 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



treme terms of the series, there remains none the 

 less between all these animals a family likeness, 

 which, thanks to the paucity of transitions, gives 

 one the idea of a direct affiliation. Lastly, I will 

 remark that this branch of the Brachyodus only 

 presents one fairly restricted discontinuity be- 

 tween the upper Stampian and the lower Miocene. 

 We are commencing, moreover, to recognize a 

 small-sized mutation of the Brachyodus onoidens 

 from Chitenay, which already diminishes the wholly 

 provisional gap which separates the Stampian type 

 from the large species of the sands of the Orleanais. 



It would be easy to construct a series, analogous 

 to the preceding, among the Anthracotheria, a 

 branch in which the highest term only is lacking, 

 for the reason that this group became extinct at 

 the end of the Oligocene. On the other hand, 

 while the Brachyodus have shown us an almost 

 monophyletic branch, with the exception of the 

 small lateral twig of the Brachyodus Cluai, the 

 Anthracotherium series is polyphyletic, and ought 

 itself to be broken up into three parallel sub- 

 branches, of which two are constituted of small 

 forms, and one leads up by a gradual increase in 

 size to the Anthracotherium magnum of the higher 

 Oligocene, with dimensions comparable to those of 

 the great Miocene Brachyodus. 



Instead of describing in detail the mutations of 

 the Anthracotherium, it seems preferable to change 

 to another group, and to examine the very in- 

 structive pedigree of the Proboscidians, of which one 

 well-known branch alone, that of the Elephants, 

 has continued down to our own times. The Pro- 



