222 THE NATATOEES. 



they rarely ascend into the air unless they are alarmed, or under 

 migrating impulse, which disperses them among the interior 

 lakes in the autumn, and compels them to select a favourable 

 breeding-place in the spring. 



The nest of the Grebe is usually placed in a tuft of rushes, 

 on the edge of the water. It is composed exteriorly of large 

 grassy plants roughly interlaced, and the interior is lined with 

 soft broken grasses delicately arranged. The eggs vary from three 

 to seven. On shore they cannot walk at all, but creep, so to 

 spieak ; for they must hold themselves nearl\' upright, supported 

 on the croup, the toes and the tarsi being extended laterallj^. But 

 ungraceful as they are on shore, so much greater is their elegance 

 on the water. They are covered with a close warm down — so close 

 and so lustrous, that muffs of a silver)' white are made of the down- 

 covered skins of their breast, which are impervious to water. 



M.Noury, Director of the ]Museum of Natural History at Elbreuf, 

 who has carefully studied the habits of the Grebes, relates of the 

 Castanean Grebe, P. cornutus, that its nest is a perfect raft, which 

 floats upon the surface of our ponds and lakes. It is a mass of 

 thick stems of aquatic herbs closely woven together ; and as these 

 materials contain a considerable Cjuantity of air in their numerous 

 cells, and from disengaging various gases besides in decomposing, 

 these aeriform sujDporters render the nest lighter than the water. 

 In this improvised ship, and upon this humid bed, the female Grebe 

 silently sits upon and hatches her progenj\ But if anything 

 unforeseen disturbs her security, this wild bird plunges one foot 

 into the water, which she employs as an oar to transport her 

 dwelling from the threatened danger. 



Grebes are inhabitants of the Old and "New Continents. 

 Among the European species may be noticed the Crested Grebe 

 {Podiceps cristafus), Fig. S3, about the size of a Duck, ornamented 

 with a double black crest ; the Horned Grebe (P. cornutus), pro- 

 vided with two long tufts of feathers, in form somewhat resemblino- 

 a horn ; the Eared Grebe (P. auritus), distinguished bv its beak, 

 the base of which is depressed, while the point is raised upwards. 

 Among the American species may be mentioned P. Caroliucnsis 

 and P. ruhricoUis, killed at the Great Slave Lake, alono- with 

 P. cridutus and P. cor/uitus. P. Chllensis and P. America i/i/s 



