^82 Classification of Fishes 



"The main argument on which Miller rested was the 'high 

 state of organization of the ancient fishes of the Paleozoic for- 

 mations, and this was apparently combined with a confident 

 assumption of the completeness of the geological record. As 

 to the first idea, we know of course that evolution means the 

 passage from the more general to the more special, and that as 

 the general result an onward advance has taken place; yet 

 'speciaHzation' does not always or necessarily mean 'highness' 

 of organization in the sense in which the term is usually em- 

 ployed. As to the idea of the perfection of the geological 

 record, that of course is absurd. 



"We do not and cannot know the oldest fishes, as they 

 would not have had hard parts for preservation, but we may 

 hope to come to know many more old ones, and older ones stiU 

 than we do at present. My experience on the subject of fossil 

 ichthyology is that it is not likely to become exhausted in our 

 day. 



"We are introduced at a period far back in geological his- 

 tory to certain groups of fishes, some of which certainly are 

 high in organization as animals, but yet of generalized type, 

 being fishes and yet having the potentiality of higher forms. 

 But because their ancestors are unknown to us, that it is no 

 evidence that they did not exist, and cannot overthrow the 

 morphological testimony in favor of evolution with which the 

 record actually does furnish us. We may therefore feel very 

 sure that fishes or ' fishdike vertebrates ' lived long ages before 

 the oldest forms with which we are acquainted came into exist- 

 ence. 



"The modem type of bony fishes, though not so 'high' in 

 many anatomical points as that of the Selachii, Crossopterygii, 

 Dipnoi, Acipenseroidei, and Lepidosteoidei of the Palseozoic 

 and Mesozoic eras, is more specialized in the direction of the 

 fish proper, and, as already indicated, speciahzation and 'high- 

 ness' in the ordinary sense of the word are not necessarily coin- 

 cident. But ideas about these things have undergone a won- 

 derful change since those pre-Darwinian days, and though we 

 shall never be able fully to unravel the problems concerning the 

 descent of animals, we see many things a great deal more clearlv 

 now than we did then." 



