334 ORGANIC EVOLUTION CONSIDERED 



tirely lost, for among the earliest fossils are found 

 trilobites and cephalopods — " animals which can , 

 hardly be regarded as lower than the middle of the 

 animal scale." 



It must also assume that nearly all of the record 

 since the Primordial period has been obliterated, so 

 that the fossils which are known or can ever be 

 known, constitute but a few links in the chain of evo- 

 lution. 



Species succeed each other, even where the rocks 

 are continuous and without any evidence of breaks in 

 their formation, as if by substitution and not by 

 transformation, although the rocks may be full of 

 well-preserved fossils. For this reason Professor Le 

 Conte deems it necessary to assume that species have 

 been formed suddenly — perhaps in one or two or a 

 few generations. 



In the preceding pages I have endeavored to show 

 that throughout the various classes of the animal 

 kingdom there has been little progress in structure 

 during the whole of geological time, and I have in- 

 sisted that this almost total lack of progress is entire- 

 ly inconsistent with the enormous advance in struc- 

 ture and intelligence involved in evolving man from 

 protoplasm. 



I have called attention to the fact that many species 

 of plants and animals have undergone but little 

 change through long periods of time. 



Professor Huxley says: " The significance of per- 

 sistent types and of the small amount of change 

 which has taken place even in those forms which can 

 be shown to have been modified, becomes greater and 

 greater in my eyes, the longer I occupy myself with 

 the biology of the past." 



The long endurance of many species, the persist- 

 ence of types, the absence of generalized structures 



