COLYMBID.E. 7 1 1 



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 lo 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 



