LIFE ON THE EARTH. 



statement by examples taken from the same classes 

 as in the former table, with the exception of Fishes 

 (F), which are here substituted for Cetacea. 



For comparison with the tables just given of 

 species and genera still living traced backward in 

 time, we may in like manner select species and 

 genera living in the older strata, and trace them up- 

 ward in the rocks, or forward in time, as in the 

 following examples. There being no Fishes in the 



