468 THE DISTRIBUTION OF ANIMALS 



allow. In this case we know from fossils that lungfish were formerly 

 world-wide in distribution, and these represent three surviving relics. 



Geographic Realms 



Alfred Russel Wallace, the great explorer naturalist, divided the 

 world into six geographic realms on the basis of the animal life. Great 

 barriers such as the oceans, deserts or mountain ranges served to con- 

 tain certain forms of life in these areas. These realms are as follows. 



Australian Realm. This region includes Australia, New Zealand, 

 Tasmania, and certain neighboring islands in the East Indies. A di- 

 vision known as Wallace's line separates this realm from the rest of the 

 East Indies. The characteristic animals are the egg-laying mammals; 

 the marsupials, such as the kangaroo, the koala bear, and the phalangers ; 

 and birds, such as the cassowaries and apteryx. Absent from this area 

 are the higher mammals except man and his primitive dog, called the 

 dingo. This realm has been divided from the rest of the world for a 

 very long period and contains only the most primitive of the mammals. 

 When new orders developed in the rest of the world they were unable 

 to migrate to Australia. 



Oriental Realm. This region includes southern Asia south of the 

 Himalaya Mountains; in it we find India, southeastern China, the 

 Philippine Islands, and the large islands in the East Indies north of the 

 Wallace line. Characteristic animals are the orangutan, gibbon, Indian 

 elephant, tiger, tapir, peacock, and the jungle fowl which is our domes- 

 tic chicken. This is not as isolated as the Australian Realm and con- 

 tains many animals in common with other parts of the world. 



Ethiopian Realm. This region includes all of Africa south of the 

 Sahara Desert. Madagascar, which has many unique animals, also 

 belongs in this realm. The characteristic animals are the gorilla, chim- 

 panzee, zebra, African elephant, giraffe, and hippopotamus. 



Neotropical Realm. This includes South America, Central America, 

 Mexico, and the West Indies. Characteristic animals are the New 

 World monkeys, such as the marmoset and capuchin ; sloths, the anteater, 

 llama, peccaries, and the chinchilla. The great majority of humming- 

 birds are found in this realm and only a few species are found north of 

 Texas. Although the jungles of South America would seem similar to 

 those of Africa, it is strange to find that none of the larger mammals 

 are found in both places. 



Palearctic and Nearctic Realms. The Palearctic realm includes all 

 of Europe and Asia north of the Himalaya Mountains and a small strip 

 of Northern Africa as well as Japan and Iceland. The Nearctic realm 



