THE GREAT NORTHERN DIVER. 465 



Calathus, etc., also Phryganeidse, frequently Notonecta, larvae of 

 odonata, and diptera ; Crustacea (Gammari) . Also vegetable remains. 

 Distribution. — British Isles. — Resident. Generally distributed, 

 but less plentiful northern Scotland. In autumn, immigrants occur 

 east coast England, and in winter many go down to tidal waters* 

 Distribution. — Abroad. — From about lat. 62° north, southwards 

 throughout Europe to north Africa, eastwards at least to Ural. 

 Casual Faeroes and Canaries. Replaced by more or less closely- 

 allied forms in tropical and south Africa, various parts of Asia, 

 Australia, New Zealand. 



Family COLYMBIDM (Urinatorid^:). 



No dorsal vertebrae fused ; spina externa present, interna 

 absent ; sternum much longer than in Podicipidce, without notches. 

 Plumage quite different from that of Podicipidce, harder, not soft 

 and "furry." Tail very short but obvious, 16-20 rectrices. Ten 

 developed and one rudimentary primary. Pullus not striped. 

 Nests on land. Eggs oily-brown, spotted, without chalky covering. 

 One genus with 4 species, northern portion of Northern Hemi- 

 sphere. 



Genus COLYMBUS L. 



Colymbus Linnaeus, Syst. Nat., ed. x, 1, p. 135 (1758 — Type by subse- 

 quent designation, of Gray 1855, C. arcticus). 



Characters, see under Family Colymbid^e. 



Key to species of genus Colymbus. 



f Fore -neck black with bluish gloss . 2 



1 *{ Fore -neck rufous in middle . . C. stellatus ad., summer, p. 474 



(^ Fore -neck white 4 . 



2 /"Crown and hind -neck grey . . . C. arcticus, ad., summer, p. 471 

 \ Crown and hind -neck black . . 3 



{Bill black, culmen slightly curved . . C. immer, ad., summer, p. 466 

 Bill whitish, culmen straight . . C. adamsii, ad ., summer, p. 469 

 Upper-side with small white or whitish 



spots or bars C. stellatus, winter & juv., p. 473 



Upper-side with or without grey edges 5 



{Much larger, bill over 70 mm. . 6 



Much smaller, bill less than 70 mm. . C. arcticus, winter & juv., p. 470 

 / Culmen slightly curved . . . C. immer, winter & juv., p. 465 

 \ Culmen straight C. adamsii, winter & juv., p. 469 



{ 



COLYMBUS IMMER 



356. Colymbus immer Brunn.— THE GREAT NORTHERN DIVER. 



Colymbus immer Brunnich, Orn. Bor., p. 38 (1764 — Faeroes). 

 Colymbus glacialis Linnseus, Yarrell, iv, p. 96 ; Saunders, p. 709. 



Description. — Adult male and female. Winter. — Fore-head, crown 

 and back of neck dark brown, feathers of neck somewhat down -like 

 vol. 11. 2 H 



