312 BRITISH BIRDS. [vol. vn. 



(and other birds, as for instance Rooks) should begin to 

 moult their primaries just when they have the extra 

 labour of procuring food for their young as well as 

 for themselves, but that this is so we can confirm by 

 personal observation, in any case as to the Lesser 

 Black-backed Gull. 



Exactly when these three Gulls attain the mature 

 plumage, unfortunately remains uncertain from 

 Kennedy's notes. Of one Lesser Black-backed Gull 

 he states that, in third winter-plumage it was adult 

 save for the colouring of the soft parts, but other 

 specimens in third winter show a considerable amount 

 of immature-plumage. 



In the case of the Great Black - backed Gull, it is 

 evident from the photograph that a bird in its third 

 winter-plumage is still not quite mature, the tail-feathers 

 being shghtly mottled. It is probable, therefore, that 

 these Gulls do not usually attain the complete adult- 

 plumage until the fourth winter. 



An interesting point is, that the scutellge of the 

 tarsus are shed (this is illustrated in one of the coloured 

 plates), and that the bill " flakes " apparently during 

 both the spring- and autumn-moults in immature birds, 

 though whether this is so also in mature birds remains 

 to be shown. 



In conclusion, we have to thank Mrs. Macdonald for 

 giving us the opportunity of drawing the attention of 

 ornithologists to her brother's work, which, though 

 necessarily incomplete, is nevertheless most interesting 

 and valuable. 



H.F.W. 



