THE ^WORLD'S BIRDS. 103 



animals. A familiar species is the Naked-throated 

 Bell-Bird (Chasmorhynchiis nudicollis), of the size 

 of a Dove, white, with bare green face in the male, 

 olive-green in the female, with a remarkable metallic 

 note ; it is usually on view in the Zoological Gardens, 

 where the common Cock-of-the-Rock (Rupicola croced) 

 has also been exhibited. 



Creepers (Certhiincz) are small birds ranging over 

 most of the world except South America. Their bill 

 is slender, and may be straight or curved; the outer 

 front toe is nearly as long as the middle one. They are 

 insect-eating climbers, place their nests in crevices, and 

 are usually brown in colour, like our familiar Tree- 

 creeper (Certhia familiaris), which is found all round the 

 Northern Hemisphere. The grey Wall-creeper (Ticho- 

 droma muraria), with rose-coloured marking on the 

 wings, is, however, an Old World species of Alpine 

 haunts. Both have been kept in captivity. 



Crows (Corvintz) are large birds for the Passerine 

 family, the biggest Ravens equalling a good-sized 

 fowl, and the smallest a Thrush. They have strong 

 and usually stout bills, with the nostrils generally 

 concealed by forwardly directed bristles. Their feet 

 are strong, and are used to hold down food while they 

 eat. Birds of this group are notably omnivorous, 

 and are usually social. There is no sex- difference 

 or seasonal change throughout the group. The nests 

 are generally open, and the eggs spotted. Many walk 

 when on the ground, and the flight has not the undulat- 

 ing character usual among Passerine birds. One type 

 or other of the group is found everywhere, but the 

 Magpies and Jays are absent from Australia, and the 

 typical Crows from South America. 



These typical forms are always at least as big as 

 Pigeons, with long wings and moderate tails ; their 

 plumage is generally black, as in the Carrion Crow 

 (Corvus corone) of the Old World, the American Crow 



