300 Hirundinidce. 



over our gardens, sweeps round our houses or skims over the 

 pool : now it will wheel and sport high up in the air, hurrying 

 here and there on the lightest wing in the gladness of its heart - t 

 anon it will float without effort in the vast expanse, as much 

 at home and at ease as other birds when perched on a tree 

 or motionless on the ground; and for this aerial life how admir- 

 ably their structure is adapted : observe the shape of the body, 

 how full the forepart, how gradually tapering towards the tail, 

 which is exactly the principle on which the fastest sailing ships are 

 constructed : then see the plumage, how firmly compacted, how 

 little liable to be ruffled by the breezes in a long and rapid flight; 

 mark the wings stretching out like oars of vast length, and moved 

 by muscles of extraordinary power : note the long forked tail> 

 supplying a never-failing rudder to guide the bird through those 

 numerous windings in which it delights. Other characteristics 

 of this family, in addition to those belonging to the whole tribe, 

 are very short beak, very broad at the base and slightly bent ; 

 head quite flat, and neck scarcely visible : their note is rather 

 a continued twitter than a song, though some of the species will 

 scream in a high and wild key, and others have a not unpleasing 

 though monotonous and very gentle melodious warble. All the 

 four species of this family with which we are acquainted are 

 summer visitants, leaving us in the autumn. It used to be 

 asserted by older naturalists, before the habits of birds had been 

 so closely observed as of later years, that the Hirundines did 

 not leave this country in the winter, but retired to caves or holes, 

 and there remained dormant, like the bats and dormice. Others 

 maintained the wilder theory that they plunged into the beds 

 of rivers and lakes, and there amidst the sedge and mud and 

 reeds at the bottom, slumbered away the dreary months of ice 

 and snow, till the genial breezes and warmth of April roused 

 them from their torpor to renewed life and activity. These idle 

 tales have long since been exploded, and we all know that the 

 bulk of these birds collect in enormous numbers in the autumn, 

 migrate in vast flocks, and steer their course due south, though 

 doubtless a few stragglers are often left behind, perhaps physi- 



