INSESSORES. 



65 



Much importance, I tliink, attaches to this remark, 

 for practical ornithologists must be well aware how 

 frequently they are enabled to distinguish one 

 species from another at a distance by means of its 

 note. In the case of nearly allied species, attention 

 to this point is of great utility, and when taken in 

 connection with the flight and motion on the ground, 

 it is surprising at what a distance a bird may be 

 named with certainty, even when too far off to dis- 

 tinguish colour. 



The Greyheaded Wagtail is so very nearly allied 

 to its congener the Yellow Wagtail, that it is not 

 surprising that they are frequently confounded. 



In the immature state it is not easy to distinguish 

 them. When fully adult^ the chief points of differ- 

 ence between these two species may, perhaps, be 

 best set down as follows : — 



Yellow Wagtail. 



Head . . pale oUve. 



Over eye . . yellow line. 



Chin and throat yellow 



Two outer tail-feathers on 

 each side white, with a 

 streak of black on the 

 inner side. 



All the others brownish-black. 



Geeyheaded Wagtail. 



Head . . grey. 



Over eye . . white line. 



Chin . . white. 



Tivo outer tail-feathers on 

 each side white, with a 

 black border on the inner 

 side of each ; that of the 

 second feather being broader 

 than that of the first. The 

 third feather black, with a 

 narrow outer edge of white. 

 The six central tail-feathers 

 nearly uniform black. 

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