40 



had been gradual, differing in no essential respect from those 

 still in progress. Strangely enough, the corollary to this propo- 

 sition, that Life, too, had been continuous on the earth, formed 

 at that date no part of the common stock of knowledge. 



In the physical world, the great law of " Correlation of 

 forces " had been announced, and widely accepted ; but in the 

 organic world, the dogma of the miraculous creation of each 

 separate species still held sway, almost as completely as when 

 Linnasus declared : " There are as many different species as 

 there were different forms created in the beginning by the 

 Infinite Being." But the dawn of a new era was already 

 breaking, and the third period of palaeontology we may 

 consider now at an end. 



Just twenty years ago, science had reached a point when the 

 belief in "special creations" was undermined by well estab- 

 lished facts, slowly accumulated. The time was ripe. Many 

 naturalists were working at the problem, convinced that Evo- 

 lution was the key to the present and the past. But how had 

 Nature brought this change about ? While others pondered, 

 Darwin spoke the magic word — "Natural Selection" and a 

 new epoch in science began. 



The fourth period in the history of Palasontology dates from 

 this time, and is the period of to-day. One of the main char- 

 acteristics of this epoch is the belief that all life, living and 

 extinct, has l/een evolved from simple forms. Another prom- 

 inent feature is the accepted fact of the great antiquity of the 

 human race. These are cpiite sufficient to distinguish this 

 period sharply from those that preceded it. 



The publication of Charles Darwin's work on the " Origin 

 of Species," November, 1859, at once aroused attention, and 

 started a revolution which has already in the short space of 

 two decades changed the whole course of scientific thought. 

 The theory of "Natural Selection," or as Spencer has hap- 

 pily termed it, the " Survival of the Fittest," had been worked 

 out independently by Wallace, who justly shares the honor of 



