140 STUDIES IN LIFE AND SENSE. 



description of animal and plant distribution, moreover, besides 

 affording no exact details of the boundaries of its regions, gives no 

 information concerning the causes which limit an animal to a small 

 area in one case, or which extend an animal's range over a wide area 

 in another. On the contrary, when, taking as our guide the natural 

 divisions of earth's population, we discover the exact distribution of 

 animals and plants, we lay thereby the foundation of the knowledge 

 which shows how that distribution has been attained and regulated. 



It is not sufficient, for instance, 



"^^^^^^^^, for any intellectual purpose, to know 



why kangaroos are found in Aus- 

 tralia alone. The mind naturally 

 proceeds further, and inquires, why 

 should these animals be limited to 

 the region in question ? It by no 

 means conveys any adequate infor- 

 mation concerning the distribution 

 of the marsupial or " pouched " 

 order of quadrupeds to be told that 

 all known members of the group, 

 kangaroos included, are confined to 

 the Australian region, with the single 

 exception of the true opossums or Didelphida these latter animals 

 occurring in the New World, but being absent from Australia. The 

 natural queries, why should kangaroos be confined to Australia, and 

 why should the opossums (fig. 12) alone of all marsupials be found 

 without the bounds of Australia, are not answered by the mere geo- 

 graphical descriptions of former days. Nor do these descriptions in- 

 dicate why, to select other examples, Australia is practically destitute 

 of all higher quadrupeds ; or why antelopes have their headquarters in 

 Africa, where, south of the great desert, deer do not typically occur, 

 whilst deer are found in all other regions save Australia. So also the 

 mere note of an animal's country as politically defined, and the mention 

 of the fact that bears inhabit Europe, Asia, and North America, gives 

 no explanation why these animals are absent from tropical and South 

 Africa. 



The pigs, again, are common over Europe and Asia down to 

 New Guinea, yet Southern Africa knows not this race any more 

 than it includes the deer amongst its denizens. Nor can we explain 

 according to ordinary geographical notions, why tapirs should exist 

 in regions so far apart as Malaya and South Africa, or why camels 

 and llamas should inhabit the Asian deserts and the slopes of the 

 Andes respectively.- Or, last of all, how impossible of explanation, 

 on ordinary grounds, is the fact that the anthropoid or man-like apes 

 occur in regions so widely separated as Western Africa and Borneo. 



