THE F.VOLITIOXARY CAREER 



317 



Flowering Plants might be lost. It cannot be said that these 

 characteristic features of the evolutionary process are, as yet, 

 susceptible of satisfactory^ descriptions. 



106. ON THE EPISODES OF LIFE EVOLUTION 

 We may best present these in tabular form : 



In each episode some offshoot from the leading type has evolved 

 and become temporarily dominant. Such phases of dominance 

 we refer to as the " Age of Brachiopods," " Age of Trilobites," etc. 

 The episodial group appears rather suddenly in each case, becomes 

 established and dominant and then undergoes remarkable amplifi- 

 cation in unessential structure. As in the cases of the Trilobites, 

 the Mesozoic Cephalopods, the Permian, Triassic and Jurassic 

 Reptiles, etc., there are bizarre specializations of structure. Then 

 follows the phase of degeneracy of the episodial race and its total 

 extinction, or loss of dominance, to be followed by the survival 

 of only a few representatives. 



The Darwinian principles of natural selection and adaptation 

 have been employed to explain such features of the episodes. 

 Elaboration of structure has been taken to mean greater adaptation 



