22 



east to the far west. Whether the latter fact be true or not, the 

 acceptance of the theory that the migration is conducted in a 

 broad front corresponding to the latitudinal area of the breed- 

 ing grounds will be found to be very difficult. Indeed, it may be 

 at once remarked that the evidence of other observers quoted on 

 p. 28 by Herr Gatke all points to the opposite conclusion. 



The spring migration of this species, as observed at Heligoland, 

 is described as being performed in very small parties, but in the 

 autumn almost always in assemblages of varying numbers, but 

 which sometimes during the first weeks of September, assume 

 considerable dimensions. An unusually marked migration 

 occurred on September 19th, 1858. This movement commenced 

 with small parties in the forenoon, and increased towards sunset 

 to one incessant stream of flocks of fifty, eighty, or even larger 

 numbers. These approached the island from the east and 

 disappeared from view in the far west, just as the majority of 

 species do. Now, though this migration, as regards numbers, 

 was abnormal and not likely to occur again for many years, yet 

 there is no reason to suppose that it was conducted in any but 

 the normal manner of flight. The author's theory of a broad 

 front should, therefore, still apply, as in the case of other 

 species. 



On witnessing a phenomena of this nature, Herr Gatke might 

 well express his wonder as to how such extraordinary numbers 

 of an uncommon species had banded themselves together, but 

 perhaps he had in view his theory of the " broad front " when 

 he hazards the opinion that only the endless forests of Euro- 

 pean and Asiatic Eussia could have given birth to such a 

 throng. For we must assume, to be in harmony with the above 

 theory, that still greater numbers were passing other localities 

 both north and south of the island a fact impossible of realisa- 

 tion in the case of so rare a species without concurring in his 

 remark on the necessarily vast area requisite to produce such 

 multitudes ; and in the latter case one is also impelled to 

 ask What became of all this great host and in what country did 

 its constituents find winter quarters? 



Though this migration was evidently of an exceptional 

 character as regards numbers, and perhaps akin in nature to that 



