DIVISIONS OF BIEDS. 



297 



food. In the Charadriidce are comprised the Oyster-catchers, Turn- 

 stones, Lapwings, Plovers, Thick-knee, and many other familiar 

 Birds. Lastly, the Otidm comprise only the Bvistards, which are ex- 



Fig. 211. — Grallatores, Common Heron (.4rdea czTierca). 



clusively confined to the Old World, and make a decided approach 

 to the Kasorial Birds. 



Order III. Rasores. 



The Scratching Birds — or as they are often called, the Gallinace- 

 ous Birds — are characterised by the fact that the upper mandible 

 of the bill is convex and vaulted (fig. 213), and has a membranous 

 space at its base, in which the nostrils ai-e pierced. The nostrils are 

 also covered by a cartilaginous scale. The legs are strong and mus- 

 cular, and are often covered with feathers as far as the ankle-joint. 

 There are four toes (fig. 212, A), three in front, and a short hind-toe 

 placed on a higher level than the others. AH the toes, in the typical 

 members of the order, are provided with strong blunt claws, suitable 

 for scratching. The food of the Rasores consists chiefly of hard 

 grains and seeds, and in accordance with this, they have a large 

 crop, and an extremely strong and muscular gizzard. They generally 

 lay their eggs upon the ground, and they are mostly polygamous, 



