38 



ISLAND LIFE. 



[part I. 



We find, that out of a total of 118 British Passeres there are: 

 82 species which range to North Africa and Central or 

 East Asia. 



25 species which range to Central or East Asia, but not 



to North Africa. 

 43 species which range to North Africa and Western Asia. 

 6 species which range to North Africa, but not at all into 

 Asia. 



6 species which range to West Asia, but not to North Africa. 

 6 species which do not range out of Europe. 



These figures agree essentially with those furnished by the 

 mammalia, and complete the demonstration that all the tem- 

 perate portions of Asia and North Africa must be added to Europe 

 to form a natural zoological division of the earth. We must also 

 note how comparatively few of these overpass the limits thus 

 indicated ; only seven species extending their range occasionally 

 into tropical or South Africa, eight into some parts of tropical 

 Asia, and six into arctic or temperate North America. 



Range of East Asian Birds. — To complete the evidence we 

 only require to know that the East Asiatic birds are as much 

 like those of Europe, as we have already shown to be the case 

 when we take the point of departure from our end of the 

 continent. This does not follow necessarily, because it is 

 possible that a totally distinct North Asiatic fauna might there 

 prevail ; and, although our birds go eastward to the remotest 

 parts of Asia, their birds might not come westward to Europe. 

 The birds of Eastern Siberia have been carefully studied by 

 Hussian naturalists and afford us the means of making the 

 required comparison. There are 151 species belonging to the 

 orders Passeres and Picarise (the perching and climbing birds), 

 and of these no less than 77, or more than half, are absolutely 

 identical with European species; 63 are peculiar to North 

 Asia, but all except five or six of these are allied to European 

 forms ; the remaining 11 species are migrants from South- 

 eastern Asia. The resemblance is therefore equally close 

 -whichever extremity of the Euro-Asiatic continent we take 

 as our starting point, and is equally remarkable in birds as in 

 mammalia. We have now only to determine the limits of this, 



