SWIFTS. 



the flight of all hirundines is influenced by, and 

 adapted to, the peculiar sort of insects which fur- 

 nish their food. Hence it would be worth inquiry 

 to examine what particular genus of insects affords 

 the principal food of each respective species of 

 swallow. 



Notwithstanding what has been advanced above, 

 some few sand-martins, I see, haunt the skirts of 

 London, frequenting the dirty pools in St. George's 

 Fields, and about Whitechapel. The question is, 

 where these build, since there are no banks or 

 bold shores in that neighbourhood ? Perhaps 

 they nestle in the scaffold-holes of some old or 

 new deserted building. They dip and wash as 

 they fly sometimes, like the house-martin and 

 swallow. 



Sand-martins differ from their congeners in the 

 diminutiveness of their size, and in their colour, 

 which is what is usually called a mouse-colour. 

 Near Valencia, in Spain, they are taken, says 

 Willoughby, and sold in the markets for the table, 

 and are called by the country people, probably 

 from their desultory, jerking manner of flight, 

 Papillon de Montagna. (The mountain -butterfly.) 



* 



XXI. 



As the swift or black-martin is the largest of 

 the British hirundines, so it is undoubtedly the 

 latest comer. For I remember but one instance 

 of its appearing before the last week in April ; 

 and in some of our late frosty harsh springs, it has 

 not been seen till the beginning of May. This 

 species usually arrives in pairs. 



