551 



Xr. VOLITATORES. GLIDERS. 



The birds of this order may be distinguished by characters 

 indicative of that peculiar adaptation to rapid, light, and long- 

 sustained flight, which has suggested tome the nameVoLiTAxoREs. 

 deeding almost exclusively on insects, which they seize in the 

 open air, they have a form, which, although moderately mus- 

 cular, is rendered buoyant by their extremely elongated though 

 very narrow wings. Their head is broad and depressed ; the 

 bill very short in proportion to its breadth, the mouth of ex- 

 treme width, and copiously supplied with a viscid mucus, 

 which enables them more easily to retain the insects on which 

 they feed. They have a peculiarly light and bounding flight, 

 glide along with astonishing speed, deviate on occasion as if 

 without effort, and seem to be scarcely liable to fatigue in their 

 aerial wanderings, which are therefore extremely protracted. 

 On the other hand, some of them are totally incapable of w^alk- 

 ing, and none ever advance to any distance on the ground. 

 Three distinct groups enter into this order, which is the same 

 as that named Chelidones by M. Temminck. 



The Hirundinoe, or Swallows, are characterized by their very 

 short, somewhat triangular bill ; extremely long and narrow 

 wings ; emarginate or forked tail ; and very small feet, of the 

 ordinary form, the first toe being directed backwards, and the 

 third considerably longer than the other anterior toes, and also 

 exceeding the tarsus. Their digestive organs do not difter ma- 



