46 THE GEOLOGICAL EVIDENCES 



there are superadded the edentates, or tooth- 

 less animals, the carnivores, sirenians, elephants, 

 and true monkeys. Per contra, the special Eocene 

 orders to which reference has just been made, have 

 completely disappeared, so that in the Miocene 

 period only those orders of quadrupeds are 

 represented which have living representatives in 

 our existing fauna. But it must not be construed 

 from this that there is a true faunal identity ; this 

 only appears in the most recent or Post-Pliocene 

 period. 



From the beginning of the Tertiary period 

 to the present day there is a steadily pro- 

 gressive approximation to modern type-structures, 

 but this approximation is a very gradual one. 

 This will appear clear to you when it is stated 

 that, with barely a single exception, not only are all 

 the Eocene species and genera of mammals differ- 

 ent from those of the present day, but even the 

 families are very largely different ; furthermore, 

 there are a number of orders indicated which have 

 no representation in the modern fauna. The only 



