DISTRIBUTION OF SPECIES AND GENERA. 1/9 



South America nearly all of the Edentates and flat- 

 nosed monkeys ; Africa all of the hippopotamuses 

 and giraffes ; Madagascar most of the lemurs, and 

 all of these facts receive a ready explanation in 

 accordance with the descent theory. 



Present Distribution of Species and Genera. 



As a rule, it is found that the area occupied by 

 any species is a continuous one. For instance, the 

 habitat of the common European jay (Garrulus 

 glandarius) begins in the British isles, and extends 

 throughout Europe as far as the Ural Mountains, 

 the jay being common in this region everywhere 

 that the presence of forests gives it habitation. 

 Beyond the Urals it is never found, its place being 

 supplied by another species of the same genus (G. 

 brandti}. And this instance illustrates the very gen- 

 eral rule. It is a rule to which very few exceptions 

 occur, hardly more than a dozen good examples 

 being known. The marsh-tit (Parus palustris) is 

 found in Southern Europe and in China, while the 

 intermediate country is inhabited by a different 

 species. But most of these exceptions are readily 

 explained, and only serve to confirm the general 

 rule. A few peculiar cases will be noticed further on. 



Practically, the same rule holds good in the case 

 of genera, continuous generic areas being almost uni- 

 versal. As the localities inhabited by the different 

 species of a genus are compared, it appears that they 

 usually touch each other at these confines, or some- 

 times overlap; in either case, making an unin- 

 terrupted generic distribution. The genus of true 



