316 NATURAL HISTORY 



crevice ; and where they cannot pass on 

 their bellies they will turn up edgewise. 



.The particular formation of the foot dis- 

 criminates the swift from all the British 

 hirundines ; and indeed from all other 

 known birds, the hirundo melba, or great 

 white-bellied swift of Gibraltar, excepted ; 

 for it is so disposed as to carry omnes 

 quatuor digitos anticos,'' all its four toes for- 

 ward ; besides the least toe, which should 

 be the back-toe, consists of one bone alone, 

 and the other three only of two apiece. A 

 construction most rare and peculiar, but 

 nicely adapted to the purposes in which 

 their feet are employed. This, and some 

 peculiarities attending the nostrils and 

 under mandible, have induced a discern- 

 ing naturalist* to suppose that this species 

 might constitute a genus per se. 



In London a party of swifts frequents the 

 Tower, playing and feeding over the river 

 just below the bridge : others haunt some 

 of the churches of the Borough next the 

 fields ; but do not venture, like the house- 



* John Antony Scopoli, of Carniola, M. D. 



