PALEONTOLOGY 89 



Metamorphism cannot, therefore, satisfactorily 

 account for the absence of fossils between Eozoon 

 and the various fossils of the Potsdam period. 



In order to bridge this vast interval of time between 

 Eozoon and the fossils of the Potsdam, a lost inter- 

 val is assumed, in which organic beings were numer- 

 ous on the earth, but of which we have no fossil 

 remains. 



This assumed lost interval, as already stated, was 

 probably equal to the whole of geological time from 

 the Primordial to the present. 



Here, then, at the threshold, as a necessary part of 

 the theory of evolution, we are asked to believe that 

 the first half of the history of life is lost, and that 

 during this almost infinite period evolution was 

 steadily going on until it resulted in the various 

 organic forms that are found in the Primordial. 



I know of no facts to justify this boundless assump- 

 tion. Besides, we shall find that this is only one of 

 an endless number of similar assumptions that must 

 be made in order to render possible a complete theory 

 of evolution. 



With regard to the animals of the Primordial, Le 

 Conte says: "If we could have walked along that 

 beach when it was washed by the primordial seas, 

 what would we have found cast ashore? We would 

 have found the representatives of all the great types of 

 animals, except the vertebrata. The Protozoa were 

 then represented by sponges and Bhizopods; the 

 Radiates by Hydrozoa (graptolites) and Cystidean 

 Crinoids; the mollusks by Brachiopods, Oasteropods 

 (Pleurotomaria), Pteropods, and even Oephalopods 

 (orthoceras) ; and the Articulates by Crustaceans 

 (trilobites, etc.,) and Worms. Plants are repre- 

 sented by Fucoids. These widely-distinct classes are 

 already clearly differentiated and somewhat highly 



