Ornithology of Japan. 181 



of which I have seen no skins dated later than October. 

 Spring examples of males of the year only differ from adults 

 in having the pale tips to the greater wing-coverts and inner- 

 most secondaries. The greenish-blue and purplish-blue fore- 

 heads and crowns are found in both adults and males of 

 the year. 



MOTACILLA BLAKISTONI. 

 MOTACILLA AMURENSIS. 



Capt. Blakiston now regards these two forms as adult and 

 young of one species, and I feel very much inclined to agree 

 with him. The fact that the geographical distribution of 

 the two forms, so far as it is known, coincides, is of itself 

 strong presumptive evidence that both belong to one species. 

 On this hypothesis M. amurensis can only be the bird of the 

 year of M. blakistoni. One must lay the blame of having 

 committed the blunder of separating them upon somebody ; 

 and we propose to ascribe it to the complete ignorance of, 

 and apparent indifference to, the facts connected with the 

 moulting of birds displayed by all English ornithologists. 

 Wagtails appear to have a complete moult, which includes 

 their wing and tail-feathers, in their first autumn. M.japo- 

 nica moults at once into its adult plumage. M. amurensis 

 appears to have an intermediate stage between the young in 

 first plumage and the adult after the second autumn moult. 

 In the adult plumage I have described the bird as M. blakis- 

 toni. In spring a partial moult takes place : all the small 

 feathers of the bird of the year are moulted into the summer 

 plumage of the adult, but the wing- and tail-feathers are not 

 changed. In this stage I have described the bird as M. 

 amurensis in adult spring plumage. This hypothesis leaves, 

 however, two difficulties, which may be explained as follows : 

 The amount of white on the wing of birds of the year must 

 vary so much that what I have taken to be birds of the year 

 of M. blakistoni are really only birds of the year in which 

 the plumage is more adult than usual. We must also as- 

 sume that the amount of black on the head varies to a still 

 greater extent, so that the birds with black heads which I 



