FUNDAMENTAL RELATIONS OF ANIMALS 99 



duction of these ever changing beings which constitute the organic 

 world, and whicii exhibit, as a whole, such striking evidence of con- 

 nected thoughts! 



SECTION XXII 

 LOCALIZATION OF TYPES IN PAST AGES 



The study of the geographical distribution of the animals now liv- 

 ing upon earth has taught us that every species of animals and plants 

 has a fixed home, and even that peculiar types may be circumscribed 

 within definite limits upon the surface of our globe. But it is only 

 recently, since geological investigations have been carried on in re- 

 mote parts of the world, that it has been ascertained that this special 

 localization of types extends to past ages. Lund ^-^ for the first time 

 showed that the extinct Fauna of the Brazils, during the latest period 

 of a past age, consists of different representatives of the very same 

 types now prevalent in that continent; Owen^^^ has observed similar 

 relations between the extinct Fauna of Australia and the types now 

 living upon that continent. 



If there is any naturalist left who believes that the Fauna of one 

 continent may be derived from another portion of the globe, the 

 study of these facts in all their bearing may undeceive him. 



It is well kno'^vn how characteristic the Edentata are for the present 

 Fauna of the Brazils, for there is the home of the Sloths (Bradypiis), 

 the Tatous (Dasypiis), the Ant-eaters {Myrmecophaga); there also 

 have been found those extraordinary extinct genera, the Megathe- 

 rium, the Mylodon, the Megalonyx, the Glyptodon, and the many 

 other genera described by Dr. Lund and Professor Owen, all of 

 which belong to this same order of Edentata. Some of these extinct 

 genera of Edentata had also representatives in North America during 

 the same geological period,^-^ thus showing that though limited 



"^ Peter V. Lund, Blik paa Brasiliens Dyrverden for sidste Jordomvceltning (Copen- 

 hagen, 1841). 



^"^''On the Geographical Distribution of Extinct Mammalia," Annals and Magazine 

 of Natural History, XVII (1846), 197. 



^-"Joseph Leidy, A Memoir on the Extinct Sloth Tribe of North America (Smith- 

 sonian Contributions to Knowledge, VII, Washington, 1855). 



