366 THE ZOOLOGIST. 



under favourable conditions in the direction of the long axis of 

 their bodies. This is shown in the most convincing manner by 

 such flocks as happen to pass immediately over the head of the 

 observer." 



The altitude at which birds fly, and the velocity they attain 

 during migration, are subjects to which Herr Gatke has paid 

 special attention, and on which he discourses at considerable 

 length. From experiments which have been made by other 

 writers to test the average speed of birds in flight, — swallows, 

 game-birds, falcons, and homing pigeons,* — we are inclined to 

 think that Herr Gatke has overrated the speed at which migratory 

 birds usually travel, except when moving before the wind ; but, 

 as he gives reasons for his conclusions, it would not be possible to 

 refute his statements without a more complete examination of the 

 details than could be here attempted. 



Herr Gatke's work is an extremely valuable one to naturalists, 

 not only because it embodies the results of fifty years' observations 

 made at one particular station, and on that account most reliable, 

 but also because it contains so many suggestive remarks which 

 deserve the consideration of other observers, who, though less 

 favourably situated than himself, may be able one day, with the 

 aid thus afforded them, to deal effectively with some of the 

 problems of migration as yet unsolved. 





ON THE EACES AND VARIETIES OF THE POLECAT. 



By Adolphe Drion, Jun. 



In the ' Bulletin de l'Academie Koyale des Sciences, des 

 Lettres et des Beaux- Arts de Belgique ' (ser. 3, t. xiv. pp. 365-68), 

 a Belgian naturalist, M. Drion, Jun., has published an article 

 with this title, which has probably escaped the notice of the 

 majority of our readers. Whether his views on this subject are 

 to be accepted seems to us questionable, considering the extreme 

 variation in colour to which the Polecat is liable. This animal 

 has now become so rare in most parts of England, in conse- 

 quence of being trapped by gamekeepers on every possible oppor* 



* See •Zoologist,' 1880, p. 299 ; 1888, p. 308; 1892, p. 362; * Nature,' 

 1887, pp. 335, 480, 552, 599 ; 1888, pp. 369, 474 ; ' Field,' 1887, pp. 114, 242 

 and 1891, Dec. 5th. 



