THE GLACIAL RANGE CONTRACTION, ETC. 109 



between Scotland, Iceland, and perhaps Greenland, and 

 the consequent entrance into the area beyond it of the 

 Gulf Stream was a much later event, as I think we have 

 some evidence to prove. Broadly speaking, the Post- 

 Glacial Emigration of birds in West Europe from the 

 south appears to have spread in two well-defined direc- 

 tions, one, which we may call Route A, by way of the 

 British Area, the Faroes, and Iceland to Greenland ; 

 the other, which we will term Route B, by way of 

 Holland, Belgium, and Denmark to Scandinavia. The 

 former stream of emigration took place most probably 

 in advance of the latter, owing to the genial influences 

 of warm ocean currents. The birds therefore that breed 

 or winter in the British area followed this A route north ; 

 the birds that followed the B, or continental route, north 

 are only abnormal visitors to our shores.- Of course it 

 must be clearly understood that many species — or the 

 individuals of many species — reached Scandinavia by 

 an emigration across the British Area and the once dry 

 land of the North Sea, and it is the descendants of 

 these individuals that still continue to reach us either as 

 passing migrants or as winter visitors from that country. 

 The following table contains West European species 

 that breed in or visit the various specified island areas 

 between the British Isles and Greenland, and which 

 form very interesting evidence, not only suggestive of 

 an ancient coast-line between the two countries, but of 

 a route of past Emigration and Migration. Owing to 

 the vast submergences which have taken place on this 

 route, it is nothing near so important a highway for 

 Migrants as was once the case. Sufficient evidence, 

 however, exists to testify to its former importance. 



