GEOGEAPHICAL DISTEIBUTION OF ANIMALS. 541 



imagine the possibility of exchange so multiplied between 

 two regions, the faunae of which were primitively distinct, 

 that they can only now offer at the present moment species 

 common to both, and thus nothing can reveal to the eyes of 

 the naturalist their original separation : but when a country 

 is found to be peopled with a considerable number of species 

 not to be found elsewhere, even where the local circumstances 

 most resemble, we shall be authorized to think that such a 

 portion of the globe has always been a distinct zoological 

 region. 



[Buffon was the original author of the great practical thought 

 or theory included in the preceding paragraph ; he it was who 

 discovered and first spoke of " centres of creation." It has been 

 ascribed by some English writers to a former student of mine, 

 Mr. E. Forbes, who assuredly never claimed it in his own name. 

 But he ought to have disavowed it when ascribed to him by 

 .others, whose motives for doing so may very readily be guessed 

 at. 



M. Schlegel, in his admirable work on the Physiognomy of 

 Serpents, has written a memoir on this subject, which I should 

 with much pleasure have added to this work, were it not that the 

 subject in reality belongs to the philosophy of zoology, a matter 

 which the author does not profess to treat of in this valuable 

 elementary work ; from it, however, I give the following passage, 

 reminding the reader that the work was written at least twenty 

 years ago. 



" By cultivation the earth loses its primitive aspect. Serpents 

 are peculiar in many respects, and their natural history is emi- 

 nently calculated to elucidate the great questions of foci or centres 

 of creation, and the immutability of species." (p. 197.) The 

 ophidians of Japan are distinct from all others ; so also are those 

 of Madagascar. " SCHLEGEL. E. K.] 



What the naturalist ought to inquire into is, not how it 

 happens that the various points of the globe are inhabited at 

 the present day by different species, but rather how these 

 animals have been able to spread themselves to a distance 

 over the surface of the globe, and how nature has set to this 

 diffusion variable limits, according to the species. This last 

 question especially presents itself to the mind, when we 

 observe how unequal is the extent of the domain occupied by 

 different animals. The oran-outan, for example, confined 

 to the Island of Borneo and the neighbouring territories ; the 

 musk-ox, limited to the most northern parts of America, 

 and the llama, to the elevated regions of Peru and of Chili ; 



