542 DIVING-BIRDS. 



on the wing except during the periods of migration, divers fly in a straight, arrow- 

 like course, somewhat after the manner of ducks. The notes of all the species are 

 harsh and grating. Arriving at its breeding-haunts in the Arctic regions, about 

 the end of May or beginning of June, synchronously with the breaking up of the 

 ice, the great northern diver forthwith sets about the work of nesting. For choice, 

 an island is selected, but, failing this, the shelving shore of some lonely lake, or 

 even of a mountain tarn, is taken for a site. The nest, which is constructed of 

 grass and sedge, is placed in an exposed position, where the sitting bird may 

 readily receive warning of approaching danger, upon which it takes at once to the 

 water. This might at first sight seem fraught with danger to the eggs; but it 

 appears that the safety of these is generally sufficiently assured by their protective 

 resemblance to their inanimate surroundings; their colour being dark brown 

 speckled with blackish. The usual number of eggs in a nest is but two ; and both 

 sexes take their share in the work of incubation. 



THE GREBES. 

 Family PODICIPEDID^E. 



Best known by the little dabchick of our English meres and rivers, the family 

 of the grebes is distinguished from that of the divers by the toes being lobated instead 

 of webbed, and furnished with broad, flat nails, rounded at the tips ; by the presence 

 of twelve primary quills in the wing ; by the rudimentary condition of the tail ; 

 and by the number of vertebrae in the neck varying from seventeen to twenty-one. 

 In all of them a bare stripe extends across the lores from the beak to the eye ; the 

 beak, although very variable in form, is always much elongated ; and the nostrils 

 are never protected by an overhanging lobe. The wings are short and concave, 

 and when closed have the primaries concealed by the secondaries ; while in the 

 aborted tail a tuft of downy, soft feathers takes the place of the usual stiff rectrices. 

 On the lower surface of the body, the plumage, which is usually of a pure white 

 hue, is remarkable for its soft silky texture and brilliant lustre. 



The grebes are more addicted to fresh- water than any other members of the 

 order, some of them being inhabitants of lakes and rivers throughout the year, 

 while others are oceanic during a large portion of their existence. They are 

 represented by some sixteen species, ranging over the temperate and subtropical 

 regions of both hemispheres ; five of these being European, and two out of the 

 latter breeding in the British Islands, while the other three are but winter visitants 

 thereto. The eggs differ from those of the divers in the creamy white colour of 

 their shells, and their green tinge when viewed by transmitted light ; the usual 

 number in a clutch being either three or four. 



The Typical Using the term Podicipes in a wide sense, it will include the 



Grebes. greater number of species of the group, or all those in which the 

 length of the slender beak varies from 2J to 6 times its basal depth. Among the 

 larger members of the genus, the western grebe (Podicipes occidentalis) is the sole 

 representative of a group characterised by the great length of the neck and beak, 

 and the smooth head, which is devoid of tufts a,t all seasons of the year, while there 



