202 



GEOLOGICAL SUCCESSION OF ANIMALS. 



unknown to the former ages, as well as to the actual period. 

 They are little-chambered shells, known to 

 geologists under the name of Nummulites, 

 from their coin-like appearance, and form very 

 extensive layers of rocks (Fig. 167). 



Fig. 167. 



490. But what is more important, in a philosophical point 

 of view, is, that the aquatic animals are no longer predomi- 

 nant in the Creation. The great marine or amphibian 

 reptiles give place to numerous mammals of great size. 

 For which reason we have called this age the Reign of 

 Mammals. Here are also found the first distinct remains 

 of fresh- water animals. 



491. The lower stage of this formation is particularly 

 characterized by great Pachyderms, among which we may 

 mention the Paleotherium and Anoplotherium, which have 

 acquired such celebrity from the researches of Cuvier. 

 These animals, among others, abound in the Tertiary form- 

 ations of the neighborhood of Paris. The Paleotheriums, of 



Fig. 168. Fig. 169. 



which several species are known, are the most common ; 

 they resemble (Fig. 168), in some respects, the Tapirs, 

 while the Anoplotheriums are more slender animals (Fig. 

 169). On this continent are found the remains of a most ex- 

 traordinary animal of gigantic size, the Basilosaurus, a true 

 cetacean. Finally, in these stages, the earliest remains of 

 Monkeys have been detected. 

 492. The fauna of the upper stage of the Tertiary forma- 



