D IS TRIE U TION. 2 I 3 



there are birds which can cross even great seas like the 

 Atlantic Ocean. 



The Six Primary Regions. Of the systems of ani- 

 mal geography proposed up to the present time, the divi- 

 sion advocated by Sclater and Wallace finds most favor. 

 These English scholars distinguish the six following pri- 

 mary regions: (i) the palatarctic, comprising all Europe, 

 northern Africa as far as the Sahara, and northern Asia as 

 far as the Himalayas; (2) the ^Ethiopian, all of Africa 

 south of the Sahara ; (3) the oriental, including upper 

 and lower India, southern China, and the western Malay 

 Islands; (4) and (5) the nearctic and the neotropical regions, 

 which make up the American continents and are divided 

 by a line drawn at about the northern border of Mexico; 

 (6) the Australian, in which, besides Australia itself, are 

 included the larger and smaller islands of the Pacific Ocean 

 and the eastern Malay Islands, together with Celebes and 

 Lombok. 



(i) The Australian region is most sharply distinguished 

 from all the others, for undoubtedly the area of land in- 

 cluded under this name was earliest separated from the 

 rest of the mainland. The marsupial fauna is particularly 

 characteristic of it. The marsupials, which during the 

 tertiary period inhabited the whole earth's surface, have 

 become entirely extinct in Europe, Asia, and Africa, and 

 in America only the opossum family persists, but in Aus- 

 tralia they have undergone a higher development. Yet 

 until they were introduced by man Australia lacked the 

 higher placenta! mammals which have supplanted the mar- 

 supial fauna of the Old World. A few aquatic forms 

 are found there, as well as mice and bats animals which 

 are easily transported by flight, or by means of floating 

 wood. A few small carnivores, hoofed animals, and apes 

 exist only upon the islands bordering upon the oriental re- 

 gion. Further peculiarities of the Australian region are the 

 birds- of -paradise in New Guinea, the egg-laying mammals 

 Ornithorkynchus and Echidna, the remarkable Hatteria^ 



