FAUNAL MIGKATION. 13 



South American forms. Similarly, the extinct proboscideans, mam- 

 moth and mastodon, are of later date in America than in Eurasia, 

 and are in all probability to be traced back to the latter region for 

 the place of their birth. 



The countries of the Old World present to us perhaps no less 

 direct evidence as to the origination of, or the lines of migration 

 taken by, specific groups of organisms. The European mammalian 

 fauna is at the present time not very unlike in its general features 

 that of North America, but in the geological period immediately 

 preceding the present one it numbered a host of forms wholly dif- 

 fering from anything known to have existed in the corresponding 

 period of American history, and, indeed, quite different from any- 

 thing now inhabiting Europe. Such, for example, were the mam- 

 moth, African elephant, hippopotamus, African lion, leopard, the 

 spotted and the striped hyena, several species of rhinoceros, &c., 

 forms the greater number of which are at the present day associated 

 with the region lying south of the Mediterranean. The question 

 that here presents itself is one, perhaps, that cannot be fully an- 

 swered, but yet one whose partial solution is made very nearly certain. 

 Did this fauna become suddenly exterminated, through some agency 

 or other, in the region inhabited by it, or did it migrate elsewhere? 

 There can be but little doubt that both conditions took place. The 

 mammoth and the several species of (fossil) rhinoceros are now all 

 extinct, and there is every reason to believe that their tribes per- 

 ished gradually, without their having accomplished much migration 

 immediately preceding final extermination. The case is, however, 

 different with the other forms, for the fact of their inhabiting the 

 African continent leads one to suspect that they may have found 

 their way thither by way of some land connection no longer remain- 

 ing. That such a connection uniting the two continents did exist 

 within a comparatively recent geological period, permitting of an 

 interchange of the respective faunas, is certain, as is proved by the 

 numerous ties which bind together the faunas of the opposite shores 

 of the Mediterranean. The Barbary ape of the Rock of Gibraltar 

 inhabits Morocco, while the ichneumon of Spain, the porcupine of 

 Italy, and the fallow-deer of the south of Europe generally, are all 

 forms inhabiting the north of Africa as well. These animals evi- 

 dently crossed over the intervening sea by some route or other, and, 

 as has already been stated, in comparatively recent times, otherwise 



