THE GLACIAL RANGE CONTRACTION, ETC. 125 



The above table brings to light some profoundly 

 interesting facts. Taking France and Germany, say, as 

 our base, the symbols attached to the various birds on 

 the left side of the table indicate the emigrations of 

 these species in the British Islands, or entirely across 

 that area to Norway ; whilst the symbols attached to 

 the same species on the right side of the table indicate 

 the emigrations of other individuals of the same species 

 across Belgium and Holland to Denmark, Sweden, and 

 Norway in that direction. These latter symbols may 

 also indicate emigrations from more southern areas east 

 say of E. long. 10°. The table contains 211 species. 

 Ninety of these have unquestionably reached Scandinavia 

 by Emigration across the British area, as well as by way 

 of Belgium, Holland, and Denmark, as is proved by the 

 present lines of Migration followed by those species, but 

 in a few cases the palpable scarcity of the migrants 

 across our area shows that the dominant line of north- 

 ward extension was continental. The White Wagtail, 

 the Black-tailed Godwit, the Crane, and the Sclavonian 

 Grebe may be cited as instances that confirm this. The 

 northern Emigration of a very high percentage of 

 individuals, however, was continental. No less than 85 

 species have undoubtedly reached Scandinavia by way 

 of Belgium, Holland, and Denmark only — a fact which 

 is proved by the absence of those species from the 

 northern portions of our area, or their northern extension 

 on both routes not being sufficient to render it by any 

 possibility continuous at its highest limits. Continuing 

 the analysis still further, we find that only three species 

 have succeeded in reaching Scandinavia — or rather 

 Norway only — by an emigration across our area, a fact 

 which is proved by the absence of such species from 



