OF SELBORNE 177 



among some abrupt sand-hills, and in the banks of some 

 few rivers. 



These birds have a peculiar manner of flying ; flitting 

 about with odd jerks, and vacillations, not unlike the 

 motions of a butterfly. Doubtless the flight of all 

 hirundines is influenced by and adapted to, the peculiar 

 sort of insects which furnish their food. Hence it would 

 be worth inquiry to examine what particular group 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, fre- 

 quenting the dirty pools in Saint George's-Fields, and 

 about White-Chapel. The question is where these build, 

 since there are no banks or bold shores in that neigh- 

 bourhood : 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 diminu- 

 tiveness of their size, and in their colour, which is what 

 is usually called a mouse-colour. Near Valencia in Spain, 

 they are taken, says Willughby, and sold in the markets 

 for the table ; and are called by the country people, pro- 

 bably from their desultory jerking manner of flight, 

 papilion di moniagna. 



LETTER XXI 



Selborne, Sept. 28, 1774. 

 Dear Sir, 



As the swift or black-martin is the largest of the British 

 hirundines, so is it undoubtedly the latest comer. For I 

 remember but one instance of its appearing before l\\9 



