OF EVOLUTION. 49 



Eocene period. 



Mammalia with numerous extinct families and 

 orders. With two or three exceptions, all 

 the genera extinct. Species all extinct. 

 I appeal to the facts before you, and ask, Could 

 there be a more beautiful demonstration of the rise 

 and fall of a fauna tending in the direction of gen- 

 eral succession ? Do we not see in the wreck of 

 the past faunas the roots of the fauna of our own 

 day, and can we close our eyes to the evidence 

 of development that is here presented to us ? A 

 skeptical mind may, however, still urge that this 

 is but a fortuitous succession, and that we have 

 failed to bring forward proof of such transformism 

 as will permit us to see that the modern groups 

 which succeed the more ancient ones are necessa- 

 rily developed from these. But proof in this 

 direction is by no means wanting. When we 

 trace back the histories of some of our existing 

 groups of animals we find that the characters by 

 which they are defined become less and less 



marked, until they are almost completely lost, 



(4) 



