26 Scientific Proceedings, Royal Dublin Society. 



for by the reverse of the conditions referred to above. The birds are 

 older and stronger ; the Atlantic further south is a great expanse of 

 ocean, across which few bird.s, whose home is not upon the open 

 sea, could ever pass unaided, and the easterly winds which so 

 often prevail in spring would also probably prevent, even the 

 most aquatic of the jAmerican birds, from visiting us at this 

 season. 



The very large proportion of these visitors which have been 

 recorded from the British Isles, especially from England, as com- 

 pared with the rest of Europe, is most striking ; but this arises 

 probably from the number of reliable observers being much greater 

 in England than upon the Continent. 



In conclusion, the most decided result which I have obtained is 

 the remarkable preponderance in the number of birds which have 

 visited us during the autumn and winter months, which I pro- 

 pose to join together as representing the autumn migration, both 

 because many of the birds must have arrived upon our coasts in 

 autumn, although not captured or recognised until long after- 

 wards, and others have been driven to us from time to time during 

 the winter, under the pressure of cold winds, snow, or a continu- 

 ance of unusually severe weather. 



Altogether we have forty-two arrivals for the spring migration, 

 during March, April, and May, to which I think we may fairly 

 add the nineteen more instances in June and July, making sixty- 

 one. While for the autumn migration there are 132 in September, 

 October, and November, to which, if we add the fifty-four winter 

 occurrences from December to February, we shall have 168 to 

 represent the autumn migration, which appears to be the period 

 during which we receive by far the greater number of our Trans- 

 atlantic visitors. 



