Great diversity of Specie^ in Devonian System. 49 



replaced by others — can it ever be possible to express all 

 these relations by a linear arrangement in our zoological 

 systems 1 And, if what I have remarked in regard to fishes 

 be equally true in respect to all the classes of the animal 

 kingdom, ought we not eagerly to borrow from embryology 

 and palaeontology all the information they can furnish, in 

 order to enable us to appreciate more correctly the whole of 

 relations so varied, which connect all created beings with 

 each other ? 



Far from believing that this object can be completely at- 

 tained at present, I leave, in the mean time, these questions 

 regarding system, the solution of which will no doubt require 

 immense labour, to confine myself to the consideration of 

 this assemblage of fossil fishes, which constitute one of the 

 most interesting parts of the fauna of the old red sandstone, 

 in a last point of view, that is to say, as a simple group of 

 diverse, but contemporary, species. Viewing it in this man- 

 ner, apart from all systematic considerations, we are never- 

 theless struck with the great diversity which the species 

 really present. Who would have expected that we should 

 ever find, in spaces so limited as those which have hitherto 

 been explored, above a hundred species of fossil fishes, in 

 the devonian system alone, that is to say, in a stage of our 

 formations which was believed, a few years ago, to be con- 

 fined to the British islands, and to which in consequence only 

 a local value was assigned ? And yet, all other things re- 

 maining equal, the ichthyological fauna which this formation 

 contains, is as considerable as that which inhabits the coasts 

 of Europe ; and, even although the species of the old red 

 sandstone do not belong to so great a number of families as 

 the living species, they are not less varied in their forms and 

 general aspect, nor less curious in their external characters 

 and organization, nor less different from each other in size 

 and the degree of locomotive power with which they were 

 doubtless endowed.* 



* From Professor Agassi z' Monographic des poissons fossiles du vieux gres 

 rouge. 



VOL. XLI. NO. LXXXI. — JULY 1846. D 



