150 NATURAL HISTORY OF SELBORNE. 



published already in the Philosophical Transactions; but 

 as nicer observation has furnished several corrections and 

 additions, it is hoped that the republication of them will 

 not give offence ; especially as these sheets would be very 

 imperfect without them, and as they will be new to many 

 readers who had no opportunity of seeing them when they 

 made their first appearance.] 



" The hirundines are a most inoffensive, harmless, enter- 

 taining, social, and useful tribe of birds; they touch no 

 fruit in our gardens; delight, all except one species, in 

 attaching themselves to our houses ; amuse us with their 

 migrations, songs, and marvellous agility ; and clear our 

 outlets from the annoyances of gnats and other troublesome 

 insects. Some districts in the south seas, near Guiaquil,* 

 are desolated, it seems, by the infinite swarms of venomous 

 mosquitoes, which fill the air, and render those coasts 

 insupportable. It would be worth inquiring whether any 

 species of hirundines is found in those regions. Whoever 

 contemplates the myriads of insects that sport in the sun- 

 beams of a summer evening in this country, will soon be 

 convinced to what a degree our atmosphere would be choked 

 with them was it not for the friendly interposition of the 

 swallow tribe. 



" Many species of birds have their peculiar lice ; but the 

 hirundines alone seem to be annoyed with dipterous insects, 

 which infest every species, and are so large, in proportion 

 to themselves, that they must be extremely irksome and 

 injurious to them. These are the Hippoboscce hirundines^ 

 with narrow subulated wings, abounding in every nest ; and 

 are hatched by the warmth of the bird's own body during 

 incubation, and crawl about under its feathers. 



*See Ulloa's Travels, 



