REVIEW OF FOSSIL FISHES. 243 



higher living fishes. 1 "There is, then," he 

 concludes, " as we have said above, a certain 

 analogy, or rather a certain parallelism, to be 

 established between the embryological devel- 

 opment of the Cycloids and Ctenoids, and the 

 genetic or paleontological development of the 

 whole class. Considered from this point of 

 view, no one will dispute that the form of the 

 caudal fin is of high importance for zoolog- 

 ical and paleontological considerations, since 

 it shows that the same thought, the same 

 plan, which presides to-day over the forma- 

 tion of the embryo, is also manifested in the 

 successive development of the numerous crea- 

 tion which have formerly peopled the earth." 

 Agassiz says himself in his Preface : "I have 

 succeeded in expressing the laws of succes- 

 sion and of the organic development of fishes 

 during all geological epochs ; and science may 

 henceforth, in seeing the changes of this class 

 from formation to formation, follow the pro- 

 gress of organization in one great division of 

 the animal kingdom, through a complete se- 

 ries of the ages of the earth." This is not 

 inconsistent with his position as the leading 

 opponent of the development or Darwinian 



1 Recherches sur les Poissons Fossiles, vol. i. chapter v. p. 

 102. 



