4 Mem' am Geographic Distribution of Life. 



zoological and botanical regions irrespective of the long recognized 

 geographic and political divisions.* It was found that different 

 degrees of relationship exist between the indigenous animals and 

 plants of different countries, and that as a rule the more remote 

 and isolated the region and the earlier in geologic time its sepa- 

 ration took place, the more distinct were its inhabitants from 

 those of other regions. Each of the larger islands lying near the 

 equator and the continental masses of the southern hemisphere 

 were found to possess not only peculiar species and genera, but 

 even families and orders not found elsewhere ; and it was dis- 

 covered that insular areas of considerable magnitude that have 

 had no land connection with other areas since very early times 

 possess faunas and floras remarkable for the antiquity of their 

 dominant types. In Australia, the most disconnected of all the 

 continents, the entire mammalian fauna, though wonderfully 

 diversified in appearance and habits, belongs to the primitive 

 orders of monotremes and marsupials, whose best known repre- 

 sentatives are the duck-billed platypus and the kangaroo. In 

 the latter group Australia and neighboring islands contain no less 

 than six families not found in any other part of the world. 



Madagascar is the exclusive home of the remarkable aye-aye 

 (Ghiromys) and Cryptoprocta, the latter believed to be intermedi- 

 ate between the cats and civets. 



Tropical America is alone in the possession of true ant-eaters 

 (Myrniecophagidae), sloths (Bradypodidse), marmosets (Hapalidde), 

 armadillos (Dasypodidus) and agouties (Dasyproctidae). 



Africa is the home of many groups not known elsewhere. 

 Among them are the giraffe, hippopotamus, Oryeteropus, elephant 

 shrews (Macroscelididas), Potomogale, and Chrysochloridse. 



Besides this class of cases, in which particular groups are re- 

 stricted to particular countries, there is another class, in which 

 the living representatives of single groups exist in isolated colo- 

 nies in widely separated parts of the world. Illustrations of this 

 kind are furnished by the tapirs, which inhabit tropical America 

 and the Malay Peninsula, but do not exist in intermediate lands ; 

 by the family Camelidse, represented in South America by the 

 llamas and in parts of Eurasia by the true camels ; and 1 >y a gr< m j > 



* Among the many distinguished naturalists who have contributed to the 

 literature of the subject may be mentioned Humboldt, Bonpland, Bullon, 

 De Candolle, Schouw, Engler, Agassi/, Baird, Asa Gray, Grisebach, Hux- 

 ley, Gill, Allen, Wallace, and Packard. 



