10 



BRITISH BIBDB 



Most singular is the recurved bill of the Avocet, and equally so 

 the under -jawed Khynchops, the terms used implying the peculiari« 

 ties in each case. There is no living bird which lacks a beak ; but 

 in some of the extinct and toothed birds, which are again referred 

 to later, the beak was absent. Its place was taken in them by the 

 teeth. 



Feet. 



Hardly less diversified in form are the feet of birds. The skeleton 

 of this part of the body is dealt with on another page ; here we are 

 concerned only with the external form of the feet and legs. Aquatic 



Fig. 5. — Foot of Pelican. 



Fig. 6.— Foot of 

 Perching Bibd. 



birds often have webbed feet, but not always. The Dipper, for 

 example, is a bird which lives largely on and under the water, but 

 . its feet are not in the least like those of a 



\i i/iiilJ Duck or Grebe. The webbed foot presents 



us with at least two varieties. In the Pehcan 

 tribe (fig. 5) the extreme of web-footedness 

 is to be seen. Here all the toes (four) are 

 connected by a webbing. In the Duck only 

 three of the toes are webbed Another kind 

 of webbed foot is termed pahnate. In the 

 Coots, for example, each toe is fringed with a 

 broad membrane, but there is no connection 

 between the fringes of successive toes. The 

 toes of birds are apt to be differently disposed. 

 In most birds (fig. 6) there are three toes 

 which are turned forwards, and one, the great 

 toe (hallux), which is turned backwards. But m the Trogons and 

 others two toes are turned forwards and two backwards, thus pro- 

 ducing a very efficient mechanism for holding on tightly to the bough 



Fig. 7. — Foot of 

 Kingfisher. 



