COLYMBID&. 711 
THE WHITE-BILLED NORTHERN DIVER. 
CoLyMBUS ADAMSI, G. R. Gray. 
This Diver is the Arctic representative of the preceding species, 
from which it differs in several important particulars. The bill, 
which is yellowish-white at all seasons, is deeper and has the under 
mandible remarkably upcurved from the angle ; the head and upper 
neck are glossed with green, while the lower neck is tinged with 
purple (the reverse of the arrangement in the Great Northern Diver) ; 
the white streaks of the transverse band on the throat are not 
more than 8 in number, with fewer than 1o on the lower neck ; 
the white spots on the scapulars are decidedly longer than broad ; 
while those on the flanks and upper tail-coverts are smaller than 
in the sub-Arctic species; and finally, this high northern form is 
superior in size. Some of these distinctive features had attracted 
the attention of the late Sir James Clark Ross, who virtually dis- 
covered this bird on Boothia in 1830, though it was only named in 
1859 by G. R. Gray; but until Seebohm worked out and sum- 
marised the points of difference (Zool. 1885, p. 144), its claims to 
recognition were somewhat coldly received. 
Early in the spring of 1852 an example, which is now in the 
collection of Mr. J. H. Gurney, was shot at Pakefield near Lowestoft, 
and subsequently the late Dr. Churchill Babington figured in his 
‘Birds of Suffolk’? an immature specimen, believed to be from that 
county ; while one in winter-plumage, in the Museum at Newcastle, 
was obtained on the Northumbrian coast. One was killed by the 
late Mr. Booth on Hickling Broad in December 1872 ; and the Rev. 
J. E. Kelsall states that a specimen was secured in the winter of 
