INTRODUCTION 9 



1. The Holarctic Region includes the whole of Europe, Asia as 

 far south as the Himalayas, Africa north of the Sahara, together 

 with the corresponding portion of Arabia, and North America as 

 far south as Mexico. For convenience of reference it is often 

 customary to divide this region into two : its Eurasian portion is 

 then called the Palc&arctic, its American portion the Ncarctic 

 region. 



2. The Ethiopian Region includes Africa south of the Sahara, 

 Southern Arabia, and Madagascar with the adjacent islands. 



3. The Oriental Region includes India, Ceylon, South China, 

 the Malayan Peninsula, and what are known as the Indo-Malayan 

 islands, i.e. those islands of the Malayan Archipelago which lie to 

 the west of a line called Wallace's line passing to the east of 

 the Philippines, between Borneo and Celebes and between Bali 

 and Lombok. 



4. The Australian Region includes Australia, Tasmania, and the 

 Austro-Malayan islands, i.e. the islands of the Malayan Archipelago 

 lying to the east of Wallace's line. 



5. The New Zealand Region includes New Zealand and the 

 adjacent islands, such as the Chatham, Auckland, and Campbell 

 groups. 



6. The numerous groups of islands lying between Australia 

 and Southern Asia to the west, and America to the east, are 

 conveniently grouped together as the Polynesian Region. 



7. The Neotropical Region includes the whole of South and 

 Central America and part of Mexico. 



There are still two departments of zoological science to be 

 mentioned. As it is impossible to have a right understanding of 

 a machine without knowing something of the purpose it is in- 

 tended to serve, so the morphological study of an animal is im- 

 perfect without some knowledge of its Physiology, i.e. of the 

 functions performed by its various parts, and the way in which 

 they work together for the welfare of the whole. It is hardly 

 possible to give more than occasional references to physiological 

 matters in a text-book of Zoology, but in order to pave the way 

 for such references a brief account of the general principles of 

 Physiology will be given in the next section. 



Not only may we study the action of a given animal's organs, 

 but also the actions of the animal as a whole, its habits, its 

 relations to other animals, whether as friends, as enemies, or as 

 prey, to the vegetable kingdom, and to its physical surroundings, 

 such as temperature, humidity, &c. In a word, the whole question 

 of the relation of the organism to its environment gives us a final 

 and most important branch of Natural History which has been 

 called Ethology or Bionomics. 



