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ON THE CLASSIFICATION OF BIRDS. 



( 1 36.) The most extraordinary shaped foot among the 

 Grallatorial birds is that of the jacanas, or spur-winged 

 water-hens. These birds, whose geographic range 

 appears restricted to the tropical latitudes of both hemi- 

 spheres^ are particularly common on the low and in- 

 undated grounds of Brazil ; and we have frequently 

 seen twenty of them at once, in different parts of a 

 swamp, walking almost upon the water. Such, at least, 

 is their appearance ; and, although startling to one who 

 is a stranger to their habits, the deception can be thus 

 explained : — More than two- thirds of the surface of these 

 swamps, where the water is generally shallow, is partially 

 covered with the broad leaves of water lilies and other 

 aquatic plants : it is upon these that the jacana walks 

 while seeking the aquatic insects upon which it feeds. 

 It is clear, however, that, to accomplish this, it must 

 have a very peculiar shaped foot; for, otherwise, the bird 

 would sink in the soft mud below by its own weight. 

 The toes and claws are therefore developed to a most ex- 

 traordinary length, in order that the bird should be sup- 

 ported by the great extent of surface which its foot covers. 

 The African jacana*, whose body is about the size of 



our green woodpecker, has yet such an enormous foot, 

 that its fore toes measure no less than three inches and a 

 quarter, and its hind one (fig. 86. a) two inches and a 

 half: the claws are obviously constructed for the sole 

 purpose of supporting the bird upon a smooth and level 

 plain : they are perfectly straight, and of such uncom- 

 mon length, that the hinder one measures at least 

 two inches. By this remarkable structure the bird is 

 enabled to walk upon half floating leaves, which would 

 * Zoological Illus. vol. ii. pl. 2. 



