DIVISIONS OF BIKDS. 



297 



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

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

 Birds. Lastly, the Otidre comprise only the Bustards, which are ex- 



Fig. 211, — Grallatores. Common Heron (>lrf?w, cnovo). 



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

 to the Easorial Birds. 



Order III. Rasores. 



The Scratching Birds— or as they are (iften 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 membranor.s 

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

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

 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 Iiinil-toe 

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

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

 for scratching. The food of the Rasnres 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 mo:;tly polygamous. 



