32 Earliest Fishes. 



small number of these. Now, not only is the list of species, 

 and even of genera, proper to these formations, considerably 

 increased, but the more ancient deposits are daily increasing 

 more and more the number of types to add to our catalogues. 

 The strata of the devonian system, and those of the silurian 

 system, have in their turn furnished a contingent which con- 

 tinually goes on increasing. And if recognisable remains of 

 fishes below the inferior Ludlow beds, which form part of the 

 Silurian system, have not yet been discovered, I do not think 

 that we must thence conclude that fishes do not go back to 

 the most ancient fossiliferous formations ; for their extra- 

 ordinary frequency in the devonian strata and their presence, 

 which has been well ascertained, in the silurian deposits, 

 where they are, it is true, very ill preserved, sufiiciently indi- 

 cate that, in its appearance on the surface of the globe, this 

 class of animals is contemporary with the development of the 

 most ancient types of all the classes of invertebrate animals. 

 With regard to the period of their first appearance, we can 

 no longer speak of differences among the classes, but such as 

 are of little importance, in a biological development con- 

 sidered as a whole ; and it is henceforth demonstrated that 

 fishes entered into the plan of the earliest organic combina- 

 tions, which have been the point of departure in the develop- 

 ment of all the living beings which have peopled our globe in 

 the series of time. It follows from this, that the most an- 

 cient faunas are composed of representatives of all the classes 

 of invertebrate animals, and only one class of vertebrates, 

 namely fishes ; while reptiles, birds, and mammifera, did not 

 appear till later, and in succession. There is, then, a remark- 

 able and important contrast to be observed between the pro- 

 gressive development of vertebrates and that of the radiata, 

 moUusca, and articulata, in which all the classes are contem- 

 porary, as we have seen above. 



In devoting ourselves in this manner to the study of the 

 remains of organized beings imbedded in the most ancient 

 geological formations, we revive, as it were, the earliest re- 

 presentatives of creation. These fossils, in fact, may be 

 called the first parents of all the beings that lived afterwards. 

 In calling them up before us, we are present, so to speak, 



