WHITE-BILLED DIVER. 183 



Total length, 29 inches; culmen, 37 ; wing, 15*2 ; tail, 2-95 ; 

 tarsus, 3-3. 



Winter Plumage. Similar to that of C. glacialis, but dis- 

 tinguished by the ivory white bill. Upper surface brown, the 

 feathers darker brown before the edges, which are light ashy- 

 grey and very broad ; lower back and rump uniform brown ; 

 wing-coverts like the back, but not quite so distinctly mar- 

 gined; quills and tail-feathers dark brown, the latter edged 

 with ashy-grey like the upper tail-coverts ; inner secondaries 

 edged with ashy-grey like the scapulars ; crown of head and 

 neck dark ashy-brown ; lores and sides of face white, like the 

 under surface of the body, the sides of which are brown with 

 ashy-whitish margins to the feathers. 



Characters. Professor Collett has given an excellent account 

 of the sequence of plumage in the White-billed Diver, in the 

 "Ibis " for 1894 (pp. 269-283, pi. viii.). This paper is especially 

 to be commended to the notice of those ornithologists who 

 imagine that there are few facts remaining to be discovered in 

 the economy of European birds. It is a matter of regret to me 

 that space prevents my reproducing his remarks in extenso. 



Professor Collett point out that the young birds of the year 

 have rounded or almost pointed feathers, instead of the square- 

 tipped plumes of the old birds. In the following year the grey 

 plumage is retained, and the worn winter feathering is still 

 found in the ensuing June. After the next autumn moult the 

 back is still grey, but the feathers are more square-cut, showing 

 an approach to the adult form. The bill is white, like that of 

 the old birds. When the birds are two years old the adult 

 plumage is assumed, but it seems probable that, as is the case 

 with C. glaciate, the birds do not breed in their first nuptial 

 dress. Professor Collett has found that, in addition to fresh- 

 moulted feathers, some of the adult plumes are donned by a 

 recoloration of the actual feather. For further details of the 

 characters of C. adamsi the reader is referred to the paper 

 itself. 



Range in Great Britain. That C. adamsi occurs more fre- 

 quently off the British coasts than is usually supposed, is very 

 probable, and now that attention has been called to the species, 

 it will doubtless be found that many examples exist in collec- 



