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THE AMERICAN NATURALIST [Vol. XLVIII 



fication as the area is restricted from California to the 

 Pacific Coast region of Southern California, and finally 

 to the San Bernardino region. The totals reflect the trend 

 in each group. While in the largest area the number of 

 genera is considerably less than double what it is in the 

 smallest, the number of species is more nearly tripled. 

 The Southern California area is intermediate. 



TABLE VII 



Speciation of Eesident Birds in Australia and Tasmania 

 Data from North (1901-1909) 



Table VII shows a comparison of the families, genera, 

 and species of resident birds of Australia and Tasmania, 

 from North (1901-1909). Here again, in addition to a 

 very marked diminution of the total number of types in 

 Tasmania as compared with Australia, each group shows 

 a considerable decrease in the ratio of genera to families, 

 namely, from 4.35 in Australia to 2.83 in Tasmania, and 

 of species, to genera going from 2.30 in Australia to 1.22 

 in Tasmania. 



Table VIII is a similar comparison of (a) the resident 

 birds of Ireland, from Hartert (1912), (b) the resident 

 birds of all the British Isles, from Hartert (1912), (c) all 

 the species of the Palaearctic region, the great majority 

 of which are resident in one part or another, from Dresser 

 (1902), (d) all the species of Japan, many of which are 

 not resident, from Ogawa (1908), and (e) all the species 

 of Kamtschatka, where the majority are resident, from 



