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whose real winter quarters are in the south of India down to the Sunda Isles, as, for instance, 

 the two named above. This line of flight diverges abruptly to the north when approaching the 

 Atlantic, in England, Western France, and Spain ; vide the immense numbers crossing the Straits 

 of Gibraltar. 



" This westerly current is cut at right angles by another host coming simultaneously down 

 from the extreme north of Europe and Asia, and steering due south for their winter quarters, 

 viz. the Willow- Warblers, Phylloseopus trochilus and rufus, which go from the North Cape of 

 Scandinavia to the Cape of Good Hope, P. tristis and borealis from Northern Europe and 

 Asiatic Eussia down to the south of India and China. The latter, together with Falco rufipes, 

 Motacilla citreola, Anthus cervinus, Emberiza aureola, and Limosa cinerea, all plentifully breeding 

 so close to Heliogoland as the Onega, Dvina, Mezen, and Petchora districts, but still never, or 

 very rarely, turning up here during their autumnal nights, proves in itself their southern course, 

 without the least western inclination, even if they were not observed down the Ural, the Black 

 Sea, Turkestan, &c. The most striking instance of such a movement is seen in Sylvia philomela, 

 which breeds in the south of Sweden, and nevertheless has been observed here but once during 

 the last forty years. A few can be pointed out as going from north-east to south-west, namely 

 Sylvia sicecica and Alauda alpestris. These and all the others enumerated are joined by hosts of 

 the more common ' million,' which are spread far and wide over the entire Northern Palsearctic 

 Region. 



"What under such circumstances becomes of the routes of birds by river-courses or 

 mountains ] How many great rivers Anthus richardi has to cross, almost at right angles, during 

 his autumnal flight from Dauria to France and Spain! I maintain that the migratorial move- 

 ment, particularly the vernal one, when in normal progress, is performed by the great majority of 

 birds far beyond the conception of man, and that what we see of the same are but the irregu- 

 larities and interruptions thereof, brought about by atmospheric agencies. Your opinion that 

 the spring line of flight is widely different from that of the fall, I most completely participate in. 

 All the different routes enumerated in the foregoing are dropped, and a more or less direct course 

 toward the polar regions adopted — the wide front of the winter quarters, extending from the 

 west of Africa to the east of China, the Philippines, Borneo, &c, concentrating during this 

 northerly passage to less than half its original stretch. 



" A proof of this latter assertion is rendered by the fact that of all the eastern birds which 

 visit Heligoland during their autumnal migration none appear during their return journey, the 

 track ' to the south which terminated their western flight having brought them to far lower 

 latitudes ; while in spring, as they pursue a direct course to their northern breeding-grounds, 

 they leave all these western countries to their left. 



"While the 'rare birds' here during the autumn are, without exception, eastern species, 

 those of the spring are as uniformly from the south-east — Greece, Asia Minor, Turkestan, &c. 

 Singular it is that almost no exceptional bird has come here from the south or west, i. e. so far 



