50 COLYMBIFORMES CHAP. 
brane, but whereas Divers have the anterior toes fully webbed, 
their allies have them surrounded by large lobes of skin, con- 
nected only at the base. The claws are abnormally broad and 
flat in Grebes, the outer margin of the third being serrated. 
In the Colymbidae the wing is short, narrow, and pointed, with 
eleven primaries and about twenty secondaries; in the Podici- 
pedidae it is still shorter and concave in form, with twelve 
primaries but rarely twenty secondaries; in the latter no true 
rectrices can be distinguished, though a tuft of downy feathers 
exists, while in the former they are normal though much reduced, 
and number from eighteen to twenty. Grebes have bare lores, 
and are frequently adorned in the breeding season with crests or 
tippets of a golden or brownish colour; the dense glossy plumage 
being more commonly used for decorative purposes than the duller 
coats of Divers. The tongue is always long and pointed, the 
syrinx is tracheo-bronchial, the nostrils are pervious, an aftershaft 
is present, and both adults and young are uniformly downy. 
Fossil remains from the Oligocene of France and southern England, 
indicating a genus intermediate between the two Families, have 
been named Colymboides.' 
Fam. I. Colymbidae.—Colymbus septentrionalis, the Red- 
throated Diver of the Arctic and sub-Arctic parts of both worlds, 
is brownish black in summer, with white under-parts and white 
specks above ; the head and neck are lead-coloured, except the 
nape, which is black with white streaks, and the mid-throat, 
which is reddish-chestnut. C. areticus, the Black-throated Diver, 
found in the same regions though with a different distribution, 
as for instance in Scotland, is blacker, with white bars as well as 
spots ; the crown and hind neck being ashy grey, the sides of the 
latter striped with black and white, and the throat purplish-black, 
interrupted by a semi-collar of white with vertical black lies. 
C. pacificus of western North America is barely separable. C. 
glacialis, the Great Northern Diver, has a much more restricted 
range, breeding in Iceland, Greenland, and the Fur Countries as 
far west as the Great Slave Lake, where it meets ( adamsi 
(hardly differing except in the yellowish-white bill), which 
extends thence to Northern Asia, and possibly to Spitsbergen 
and Jan Mayen. The former is black above, with belts of white 
spots making a “chess-board” pattern; the lower surface is 
1 Lydekker, Cat. Fossil Birds Brit. Mus. 1891, p. 192. 
