510 COLYMBIM] 



and white ; breast and abdomen, white ; long under tail- 

 coverts, sides, and flanks, mostly black. 



Adult female nuptial. Similar in plumage to the male. 



Adult winter, male and female. Chin, throat, fore-neck, 

 breast, and abdomen, white ; back, scapulars, and wings, 

 chiefly deep ashy-brown ; top of head and back of neck, 

 light brown, becoming darker on the sides of the neck ; 

 sides and flanks, brownish-black. 



Immature, male and female. Resembles the adult 

 winter-plumage except that the feathers of the back, the 

 scapulars, wing-coverts, rump, and upper tail-coverts, are 

 brownish, broadly margined with grey. 



BEAK. Bluish-black. 



FEET. Brownish-green. 



IRIDES. Bed. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 27'5 in. Female smaller. 



WING 11-75,, 



BEAK 2'4 ,, 



TARSO-METATARSUS ... 3'4 ,, 



EGG 3-25 x 2'15 in. 



Allied Species and Representative Forms. C.pacificus, 

 paler on the nape and on the back of the neck, inhabits the 

 north-western parts of North America, migrating south to 

 California in winter, and it has been recorded from Japan 

 (W. R. Ogilvie-Grant, Cat. Birds Brit. Mus., vol. xxvi, pp. 

 495-96). 



RED-THROATED DIVER. Colymbus septentrionalis (Linnaeus). 



Coloured Figures. Gould, ' Birds of Great Britain,' vol. v, pi. 

 45 ; Dresser, * Birds of Europe,' vol. viii, pi. 628; Lilford, 

 ' Coloured Figures;' vol. vi, pi. 47. 



The Bed-throated Diver is common and widely-distri- 

 buted in autumn and winter on British waters. It appears, 

 as a rule, in the latter end of October, though I have seen 



