540 
DIVIJVG BIRDS. 
a small first toe, and the absence of bare tracts on the sides of the neck; while the 
metatarsus is compressed and knife-like. In the divers the three front toes are 
fully webbed, and furnished with sharp claw-like nails; the number of primary 
quills in the wings is eleven; the tail, although short, is normal; and there are 
but fourteen or fifteen vertebrae in the neck. Moreover, the beak is long, sharp, 
and compressed; while the lores are completely feathered. Apart from the 
question of their relationship to the auks, the peculiar structure of the tibia 
seems clearly to indicate an intimate affinity between the divers and the grebes. 
Although an extinct representative of the family ( Colymboides) has left its 
remains in the Miocene deposits of the Continent, the existing divers, of which 
there are three well-marked species confined to the Arctic and cooler regions of the 
Northern Hemisphere, are included in the single genus Colymbus. The divers, al¬ 
though more slenderly 
formed, have some¬ 
what the appearance of 
geese when seen on the 
water; but on land, 
owing to the backward 
situation of their legs, 
are widely different. 
In plumage, the two 
sexes are alike; but 
the winter dress differs 
considerably from that 
of summer, as do the 
young from the adult. 
The typical representa¬ 
tive of the genus is the 
great northern diver 
( C. glacialis), attaining 
a length of some 33 
GREAT NORTHERN DIVER. 
inches, and character¬ 
ised by its glossy black head and neck, the presence of two gorgets of velvety black 
and white stripes on the throat, and the belts of white spots of varying size crossing 
the dark back; the under-parts being white. Not uncommon—especially in an 
immature state—on the British coasts, and thence wandering as far south as the 
Mediterranean, this diver breeds in Iceland, Greenland, and North-Eastern Canada; 
while in North-Eastern Asia and Western Arctic America it is replaced by a larger 
variety (C. adamsi), distinguished by the white or yellow hue of its beak. Next 
in point of size is the black-throated diver (C. arcticus), which does not exceed 26 
inches in length, and is characterised by its light grey head, the purplish black 
patch, surmounted with a black-and-white striped gorget on the throat, and the 
presence of two elongated areas on the black back between the shoulders, as well 
as others on the scapulars, marked by transverse white bands formed by nearly 
confluent square spots. The breeding-area of this species would seem to extend 
from the Hebrides and Scandinavia across Arctic Asia over the greater part of 
