334 M. Agassiz on Fossil Fishes, 



appeared in their skeleton not less remarkable than in the 

 scales and soft parts of the body. Notwithstanding that, he 

 would have hesitated to insulate these fishes completely from 

 the other great families ; and particularly because, when their 

 small number is considered, it would have been contrary to all 

 methods, to place them on the same rank with the Placoids on 

 the one hand, and the osseous fishes on the other. But what 

 the study of recent fishes did not warrant, was justified by the 

 study of fossil fishes. We have met with an ichthyological 

 fauna possessed neither of the characters of the osseous nor of 

 the cartilaginous fishes, but which remind us in every respect 

 of the Bichir and Lepidosteus. Thus it is that these two genera 

 of fishes, which appear so exceptional in the existing creation, 

 really form a type by themselves, which, however small in 

 number in our days, is not the less, on that account, the expres- 

 sion of an entire order of things. By grouping round these 

 fishes all the numerous fossils whose scales are of the same 

 structure, M. Agassiz forms of them his division Ganoid, which 

 already contains many hundred species, and which promises 

 always to become more numerous ; for, as we shall afterwards 

 see, it is it which predominates in all the epochs anterior to the 

 chalk. M. Agassiz has determined many distinct families in 

 this order; the two principal are that of the Sauro'ids^ to 

 which the Lepidosteus and the Bichir belong, and that of the 

 Lepidoids, which comprehends inoffensive, and probably om- 

 nivorous fishes, similar in their physiognomy to our carps, but 

 which have no representative in the present era. 



To each of the four orders a volume is devoted, accom- 

 panied with a magnificent series of plates, in which all the species 

 described are represented. In the descriptions, which are often 

 very much in detail, the author has not confined himself to the 

 indication of the particular characters of the ichthyolite with 

 which he is specially occupied. It is seldom that he does not find 

 an opportunity of introducing some reflections of general inte- 

 rest on the family to which the fish he is describing belongs, 

 on its distribution or its mode of association with other fossils, 

 and on the circumstances in which it is probable the animal 

 lived. Besides, the study of the families or genera which have 

 representatives in the present period, is commonly preceded by 



