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the great group of Vertebrates ; but this type must 

 have been inferior to the simplest of the Fishes, such, 

 for instance, as the existing Amphioxus. An animal 

 so deprived of all bony parts naturally could not 

 be preserved in geological strata. As regards the tran- 

 sition between the Fishes and the Amphibians, we 

 ought to expect types with but slightly ossified skele- 

 tons ; we can hardly find much more than their 

 teeth, the importance of which is too slight to give 

 the sought-for link. Finally, just like Darwin, 

 Neumayr pleads the insufficiency of our palseonto- 

 logical discoveries, and trusts that a happy chance 

 may some day bring to light types which will 

 enable these great gaps to be filled up. 



There remains, it is true, the embryological 

 method, of which Haeckel has given the exact 

 formula as follows : " The individual development 

 is a shortened repetition of the ancestral develop- 

 ment." This interesting law meets with a few 

 happy applications in palaeontology, especially in 

 the group of Ammonites and in that of the Verte- 

 brates ; but it requires to be handled with the most 

 extreme prudence. 



However this may be, it is certain that in the 

 earliest fossiliferous strata all the fundamental types 

 of the animal kingdom existed, with the exception 

 of the Vertebrates. It is, moreover, probable 

 that there have existed still earlier faunas, of which 

 all the species have disappeared through the meta- 

 morphism of the corresponding strata. As regards 

 these really primitive faunas the night is complete, 

 and there is every indication that the veil will 

 never be lifted. 



