THE EPIC OF EVOLUTION 



513 



goes on ; (6) that organic forms are derived from preceding forms ; 

 (c) that connecting Unks, beyond Darwin's fondest dreams, are now 

 known ; (d) that the rate of evohition varies in different kinds of ani- 

 mals and plants ; (e) that when a species is once extinct, there is no 

 reappearance of it. 



A table, indicating the rise and expansion of typical groups of 

 organisms, is shown in the accompanying record of geological chro- 

 nology. 



TABLE OF GEOLOGICAL CHRONOLOGY (Modified from Lull) 



