71 



we shall see the differences from living forms 

 more and more accentuated. On the other hand, 

 the faunas of two stages resemble each other 

 the more the nearer the two epochs are to one 

 another. In the most ancient formations the 

 animal population is almost special ; the principal 

 part is taken by classes and orders now vanished, 

 such as the Tetracorals, the Graptolites, the 

 Cystidea, the Blastoids, the Trilobites, the Euryp- 

 teridae, etc. On the other hand, there are not 

 found with them any signs of the very important 

 groups of the existing world the Amphibians, 

 Reptiles, Birds, and Mammals ; a few rare genera of 

 this epoch have descended to us, but not a single 

 species. As we go higher in the series of strata, 

 these foreign elements diminish and disappear, 

 replaced by genera and species more and more near 

 to ours. It seems impossible to explain, apart 

 from the descent hypothesis, this progressive regu- 

 larity of the development of beings in the direction 

 of our existing world. Yet, if we attempt to es- 

 tablish a direct genetic connection between these 

 organisms of the ancient world and the totality 

 of our existing one, we only come to probabilities. 

 Thus from the most distant times, such as the 

 Cambrian epoch, we already note the presence of 

 all the great fundamental types of the Animal 

 Kingdom, with the exception of the Vertebrates. 

 Classes, orders, and even some genera common to 

 living nature are there represented by types already 

 highly specialized, which bar us from further 

 research in that direction. 



Thus compelled to abandon the study of evolution 



