8o THE GEOLOGICAL EVIDENCES 



Before dismissing this part of my subject I 

 must direct your attention to one phase of the 

 inquiry which is as well geographic as it is geo- 

 logic in its scope. It is a familiar fact that the 

 different parts of the earth's surface are to-day 

 characterized by distinct faunal associations. 

 Thus, we recognize a South American fauna as 

 distinguished from an African, a Eurasiatic 

 fauna as distinguished from an African or Aus- 

 tralian, and so on. Now if, as is contended by 

 the upholders of organic evolution, our exist- 

 ing faunas have been developed from their 

 immediate faunal antecedents, we must have 

 some indication or foreshadowing in the latest 

 geological formations of the faunal characters 

 which, in a broad way, serve to distinguish the 

 several zoogeographical regions. And this is 

 precisely what we find. You have already 

 learned that in the earlier Tertiary periods of 

 mammalian history the existing animal forms 

 were almost wholly different from the forms of 

 to-day, and that they became less and less 



