170 BIRDS OF INDIA. 



of rocks, buildings, or in hollow trees, for clinging to the vertical 

 sides of which their claws are so well adapted. They are said 

 not to be able to rise from a plane surface, but Mr. Blyth records 

 instances where both the English and common Indian Swift rose 

 from the ground. They are all more or less gregarious, feed 

 on insects, and they convey pellets of their insect prey to their 

 young, accumulated and held beneath the tongue as in a pouch. 

 They form variously constructed nests, and their eggs are always 

 white. Their voice is usually a scream or twitter, but the most 

 aberrant are said to have a kind of song. 



Swifts are found throughout the whole world, excepting the cold 

 regions of the North, and they migrate from cold countries during 

 winter; but in tropical and temperate regions, although they 

 appear to wander about a good deal, they do not perform regular 

 migrations. 



They contain four well marked types of structure, all of which 

 are represented in India. 



Gen. AcANTHYLis, Boie. 



Syn. Chcetura, Steph. 



Char. — Toes three in front nearly equal ; the hallux shorter, 

 opposable, but also reversible to the front ; tarsus covered with a 

 naked skin ; tail short, even, or wedged, the feathers with the 

 shafts ending in rigid spines. 



This very remarkable genus, of which we have three represen- 

 tatives in India, is found in Asia, Africa, Australia, and America. 

 It has been divided into two groups, one Acanthylis verus, chiefly 

 from America, the other Pallene, of larger size ; but this last group 

 has, I see, been further divided into Hirundapus, and Pallene, to 

 which the large species of the Himalayas and Southern India are 

 respectively assigned. 



1st. — Acanthylis (verus.) 



Of small size. 



95. Acanthylis sylvatica, Tickell. 



J. A. S. XV. 284. 



