G4 DISTRIBUTION OF ANIMALS. [part i. 



the antipodes of each other, would be most inconvenient, even 

 if there were not such difference of opinion about them. There 

 can be little doubt, for example, that the most radical zoological 

 division of the earth is made by separating the Australian re- 

 gion from the rest; but although it is something useful and 

 definite to know that a group of animals is peculiar to Australia, 

 it is exceedingly vague and unsatisfactory to say of any other 

 group merely that it is extra-Australian. Neither can it be said 

 that, from any point of view, these two divisions are of equal 

 importance. The next great natural division that can be made 

 is the separation of the Neotropical Kegion of Mr. Sclater from 

 the rest of the world. We thus have three primary divisions, 

 which Professor Huxley seems inclined to consider as of 

 tolerably equal zoological importance. But a consideration of 

 all the facts, zoological and palaeontological, indicates, that the 

 great northern division (Arctogaja) is fully as much more impor- 

 tant than either Australia or South America, as its four compo- 

 nent parts are less important ; and if so, convenience requires 

 us to adopt the smaller rather than the larger divisions. 



This question, of comparative importance or equivalence of 

 value, is very difficult to determine. It may be considered from 

 the point of view of speciality or isolation, or from that of 

 richness and variety of animal forms. In isolation and speciality, 

 determined by what they want as well as what they possess, the 

 Australian and Neotrojiical regions are undoubtedly each com- 

 parable with the rest of the earth (Arctoga?a). But in richness 

 and variety of forms, they are both very much inferior, and are 

 much more nearly comparable with the separate regions which 

 compose it. Taking the families of mammalia as established by 

 the best authors, and leaving out the Cetacea and the Bats, 

 which are almost universally distributed, and about whose 

 classification there is much uncertainty, the number of families 

 represented in each of Mr. Sclater's regions is as follows : 



I. Pal?earctic region has 31 families of terrestrial mai)imalia. 



11. Ethiopian „ „ 40 „ „ 



III. Indian „ „ 31 



Iv. Australian ,, „ 14 „ „ „ 



V. Neotropical „ „ 26 „ „ „ 



VI. Nearctic „ ,, 23 



