Number of Animals in Geological Times. 361 



fossils of each of the natural subdivisions of these formations 

 shall have been grouped together and compared carefully, as I 

 have attempted to do in my Monographs of the Trigonia and 

 of the Myce of Switzerland and the adjoining countries, or as 

 Al. d'Orbigny has done, upon a much larger scale, in his 

 ' Paleontologie Francaise/ no correct ideas can be formed re- 

 specting the succession of animals and plants characteristic of 

 these long successive periods. I do not believe there is a single 

 palaeontologist, whose opinion is worth having, who can suppose 

 at this day that any of the animals, the remains of which are 

 buried in the lias, lived simultaneously with those of the inferior 

 oolite, or these with those of the Oxford clay, or these with those 

 of the upper division of the so-called oolitic formation. The 

 same may be said of the difFei-ent natural subdivisions of the 

 cretaceous formation, and of the subdivisions introduced of late 

 among the palaeozoic rocks, by Sir Roderick Murchison and Pro- 

 fessor Sedgwick, and in America by Professor J. Hall. 



But even after this separation of the fossils, the synchronism 

 of which may be fully established, our task is only fairly begun, 

 for then must begin the zoological identification of all the species, 

 which must be correct in every respect before general conclu- 

 sions can be drawn from it. 



In the first place, the specific identity of organic remains is not 

 so easily ascertained as many geologists would seem to suppose, 

 if we may judge from their statements; but unless the validity 

 of a species is sanctioned by a practised zoologist, it cannot be 

 taken as a basis for sound generalizations in reference to ques- 

 tions of a purely zoological character. The number of false 

 identifications which have been accumulated in geological works 

 is truly frightful. It would, however, be very unjust to accuse 

 geologists in general of inaccuracy on this account, the fault 

 is mostly to be traced to other parties from whom the names 

 were obtained. It should only be understood, that the materials 

 thus accumulated are no longer fit to be used for the discussion 

 of the questions which have been raised with the modern pro- 

 gress of geology, and that a thorough revision of all the identi- 

 fications made in former years is imperatively demanded by the 

 modern progress of palaeontology. It would, however, be some- 

 times amusing, were it not actually distressing, to see the manner 

 in which some geologists deal with fossils, considering them 

 simply as the characteristics of certain rocks, and hardly yet 

 dreaming that there may be such a thing as a special zoology of 

 the different geological periods, and that during each, local faunae 

 may have existed with peculiar animals, &c. The ideas about 

 characteristic fossils are still very crude, and nothing is more 

 absurd than the complaints about unnecessary multiplication of 



