HIRUNDINID^. 75 



SUB -TRIBE 11. 



FissiEOSTRES DiuRNi. Dlumal Flssirostres. 



The Fissirostral birds tliat fly by day are at once 

 distiiiguisliable from tlie nocturnal species by the 

 closeness of their plumage, which is quite devoid of 

 that fleecy appearance so eminently characteristic of 

 the preceding tribe. 



FAMILY I. 



HiRUNDiNiD.E. The Swalloivs. 



Gex. Chakac. — Bill short and weak, very broad at the base, and suddenly 

 compressed towards the tip ; the wings are long, narrow, and pointed ; the 

 tail forked ; and the tarsi very short and feeble. This group comprises the 

 Swifts and the Swallows. 



These birds are remarkable for their powers of 

 flight and insectivorous appetite. Their legs are 

 short, and comparatively feeble ; but the toes are 

 furnished with sharp hooked claws, constructed for 

 the purpose of clinging to walls or the sides of 

 rocks. In the Swifts, the toes are all directed 

 forwards ; in the true Swallows, the hind toe is 

 reversible. The wings are long and pointed, and 

 the quill-feathers of a firm texture ; the general 

 plumage is close-set, smooth, sometimes polished 

 and glossy. The beak is small, depressed, broad at 

 the base, and with a wide ga^oe. Their food, con- 

 sisting of the smaller species of insects, is always 

 taken on the wing, and they often completely fill 

 their throat with insect prey, so as to distend it like 

 a pouch, doubtless in order that their nestlings may 

 have a full supply at each visit. The whole of the 

 active existence of these birds is passed in the air. 



