NATURAL HISTORY OF SELBORNE 57 



breed the latest of all the swallow kind : in 1772 they had 

 nestlings on to October 2ist, and are never without un- 

 fledged young as late as Michaelmas. 



As the summer declines the congregating flocks increase 

 in numbers daily by the constant accession of the second 

 broods ; till at last they swarm in myriads upon myriads 

 round the villages on the Thames, darkening the face of 

 the sky as they frequent the aits of that river, where they 

 roost. They retire, the bulk of them I mean, in vast flocks 

 together about the beginning of October ; but have appeared 

 of late years in a considerable flight in this neighbourhood, 

 for one day or two, as late as November the 3rd and 6th, 

 after they were supposed to have been gone for more than 

 a fortnight. They therefore withdraw with us the latest of 

 any species. Unless these birds are very short-lived indeed, 

 or unless they do not return to the district where they are 

 bred, they must undergo vast devastations somehow, and 

 somewhere ; for the birds that return yearly bear no manner 

 of proportion to the birds that retire. 



House-martins are distinguished from their congeners 

 by having their legs covered with soft downy feathers down 

 to their toes. They are no songsters ; but twitter in a 

 pretty inward soft manner in their nests. During the time 

 of breeding they are often greatly molested with fleas. 



I am, &c. 



VOL. II. H 



