THE PRINCIPAL BIRD GROUPS 93 



and grey. The young are hatched covered 

 with down, but remain in the nest until fledged. 

 Not a few of the species are migratory, and 

 some must be classed amongst the most widely 

 ranging of birds. The Ospreys are speci- 

 ally remarkable for the structure of their feet. 

 The outer toe is reversible, and the soles of 

 the feet are thickly covered with spicules, whilst 

 the claws or talons are exceedingly curved 

 and sharp. These birds live on fishes, which 

 they catch by plunging upon them like a Gannet 

 or a Tern. In their reproduction they closely 

 resemble the typical forms. About 350 species 

 are included in this order. 



The next order we shall notice is the Coracii- 

 formes, a most heterogeneous assemblage, which 

 is divisible into no less than seven sub-orders 

 and nineteen families, each of which constitutes 

 a fairly compact group. The first of these sub- 

 orders (Coraciae) includes the Coraciidae or 

 Rollers, the Momotidae or Motmots and Todies, 

 the Alcedinidae or Kingfishers, the Meropidae or 

 Bee-eaters, the Bucerotidae or Hornbills, and the 

 Upupidae or Hoopoes. The second (Striges) 

 includes the Strigidae or Owls. The third (Capri- 

 mulgi) includes the Caprimulgidae or Goat- 

 suckers, the Podargidae or Frogmouths, and the 



