FORMATIONS BELOW CHALK, 315 



added a most interesting and curious set of rocks to the 

 geognostic system. They have connected, more nearly 

 than heretofore, the alluvial with the ficetz formations, 

 and have thus rendered more complete the series of rocks 

 which extends from granite to gravel. Not the least in- 

 teresting of the consequences resulting from the discove- 

 ries of these Naturalists, is the extension they give to 

 our views in regard to the former nature of the animal 

 world, and of the changes it has experienced during the 

 different periods of the earth's formation. 





