140 M. Agassi z on the Classification of Fishes, 



those to which they rise. The names of the families which do 

 not come down to the present creation are inscribed on the 

 trunks which represent them ; those which have no fossil re- 

 presentatives are simply indicated by broad lines on the level 

 which denotes the present creation. Finally, the convergence 

 of all these vertical lines indicates the affinity of the families 

 with the principal trunk of each order. I have not, however, 

 connected the lateral branches with the principal trunks, be- 

 cause I am convinced that they do not descend the one from the 

 other,by way of direct procreation, or successive transformation, 

 but that they are materially independent of each other, although 

 forming an integral part of one systematic whole, the connect 

 tion of which cannot be traced but by the creative intelligence 

 of its Author. Having ascertained that the species of each for- 

 mation are always different from those of other epochs, I have 

 drawn lines of demarcation from the geological levels, across 

 all the ascending lines of the families, in order to shew that 

 the genealogical development of the species is often interrupt- 

 ed, and that |if, notwithstanding, each trunk shews a regular 

 progression, this filiation is not the result of a continued de-r 

 scent, but rather a repeated manifestation of an order of things 

 determined beforehand, tending towards a precise object, and 

 methodically realised in the order of time. I have not pre- 

 tended to express in a limited synoptical table, of a class so 

 numerous as that of fishes, all the facts I have studied, and 

 what I could have developed in this place, even to an enume- 

 ration of all the species. I have only wished to present a 

 sketch, which might express the general idea of which my 

 whole work may be regarded as a detailed exposition, and 

 which a glance at the figure will render easily understood. 

 Two orders of the class appear alone, appertaining to the ear^ 

 liest periods of the developement of life on the surface of the 

 globe : they appear there simultaneously with the representa- 

 tives of all the classes of invertebrate animals, while they con- 

 tinue for a long period the only existing types of vertebrate 

 animals. The principal development of these two orders, 

 namely, the Ganoides and the Placoides, takes place in the for- 

 mations anterior to the chalk, and their typical families be- 

 come extinct before the present creation, where they are re- 

 presented only by a few species ; such are, in the order of the 



