124 



BRITISH BIRDS. 



memory I feel sure that however the migrational 

 movement as a whole is effected, the way in which the 

 Swallow returns year after year to the same old beam m 

 the same old barn is simply memory— topographical 

 knowledge of the chief natural features and the general 

 mould of the country in the neighbourhood of its nestmg 

 home. 



