120 GENERAL EVOLUTION. 



belonging to the same classes. That is by herbivorous and car- 

 nivorous marsupials and monotremes, and by Varanid Sauria, all 

 of greater size than their predecessors. 



The same fact is well known of the Neotropical region, its 

 present peculiar Edentata having been preceded by giants of the 

 same type in the Post-Pliocene and Pliocene. 



In the Nearctic region peculiar existing genera, as Procyon, 

 Alces, Castor, Bos, Sciurus, Arctomys, Lepus, Ovibos, Sorex, Me- 

 phitis, Felis, Ursus, Menopoma, Aspidonectes, Crotalus, are rep- 

 resented by Post-Pliocene fossils. 



The same occurs in the later Palaearctic formations, where Cer- 

 vus. Bos, Canis, Mustelidae, Insectivora, Vipera, Alytes, Triton, 

 etc., are allied predecessors of existing types. In the Palaeotrop- 

 ical area a wonderful development of Elephas and Gavialis preceded 

 the same types of the present. 



Prior to these faunae another state of things has, however, ex- 

 isted. North America has witnessed a withdrawal of a Neotrop- 

 ical fauna, and the Palaearctic the retreat of an Ethiopian type. 

 During the Post- Pliocene in North America, Neotropical genera 

 were to Nearctic as 12 to 29, as the record now stands. In the 

 Pliocene beds of Pikermi (Greece) antelopes, giraffes, rhinoceros, 

 hippopotamus, huge manis,* monkeys, monitors, and other genera 

 and species of African relationship are the prevailing forms. 



Still earlier, a strong mingling of Nearctic, and more of Neo- 

 tropical types, abounded in the Palasarctic. The genera Chelydra, 

 Andrias, Podocnemis,t Platemys, Caviiform, Psammoryctid and 

 Hesperomys-like Rodentia, Opossums, and Raccoon-like Carnivora. 



We have, then, three important terms from which to derive a 

 theory of the creation : 1, the existing six faunae bear in many of 

 their parts developmental relations to one another ; 2, they were 

 preceded immediately by faunae similar to them in each case, but 

 more remotely by faunae like that now next lower. 



On the whole, there can be no doubt of the truth of the gen- 

 eralization : Tliat the Southern Hemisphere is a geologic stage 

 behind the Northern Hemisphere in progress, on account (1) of 

 its perfection in types extinct in the Northern, and (2) inferiority 

 in modern types prevalent in the Northern. 



In order, however, to demonstrate this j)oint more fully, let us 



* Ancylotherium, Macrotherium. 



f P. bowcrbankii {Platemys, Owen). P. Icevis {Emys, Owen). 



