50 THE GEOLOGICAL EVIDENCES 



when the group as such disappears. In other 

 words, the specialized animals of to-day, or rather 

 their representatives, become more and more 

 generalized as we trace them back in geological 

 time. Thus, the Carnivora lose much of the true 

 type of carnivore structure in the early part of the 

 Miocene period, and by almost insensible modifi- 

 cations pass off into a group of animals, their im- 

 mediate forerunners in the Eocene period the 

 Creodonta which combine about equally the 

 characters of the Carnivora with those of the Insect- 

 ivora. Thus, the Creodonta stand intermediate 

 between two of our modern groups which are 

 seemingly very far removed from one another. In 

 the same way, if we take some, of the more prom- 

 inent families of the Carnivora, the bears and 

 dogs, for example, we find that their special 

 structural features likewise disappear the bears 

 becoming less and less bears, and the dogs less and 

 less distinctively dogs, until we meet with an 

 animal, the Amphicyon, which is about as much the 

 one as the other. Similarlv, the cats become less 



