ARRIVALS OF MIGRANTS 



241 



as the Polar regions are concerned the division into 

 Nearctic and Palsearctic is a purely arbitrary one. 



The migration of birds is a subject which interests all 

 naturalists, and is a very attractive one to a great number 

 of persons who do not pretend to any scientific knowledge 

 of ornithology. The dates and order of arrival of 

 migratory birds present so many points of interest that, 

 for the sake of comparison, the following list has been 

 made of all those birds which we had reason to believe to 

 be migratory in the Ust-Zylma district, leaving out those 

 to which, from their rarity or localness, considerable 

 doubt attaches as to their date of arrival : — 



April 

 May 



This list is necessarily very imperfect. In addition 

 to the difficulty of ascertaining the date of arrival of 

 rare or local birds, we had a still greater difficulty to 

 contend with. There can be no doubt that Ust-Zylma 

 lies somewhat out of the line of migration, which is 



Q 



