27 



of Great Britain ; and it must have been observed, 

 by every one who is attentive to natural history, 

 that towards the latter end of September, swallows, 

 hirundines rusticae, as well as martins, hirundines 

 vrbicae, congregate in great numbers, and are fre- 

 quently seen sitting on the tops of houses, and' on 

 rocks near the sea. These meetings usually con- 

 tinue for several days, after which they suddenly 

 disappear *. 



Swifts, hirundines apodes, also begin to assemble 

 in large bodies previous to their departure, early in 

 July : their numbers daily increase, and they soar 

 higher in the air, with shriller cries, and fly differ- 

 ently from their usual mode. Such meetings con- 

 tinue till towards the middle of August, after which 

 they are seldom seen. 



Sand martins, hirundines ripariae, likewise flock 

 together in autumn. Some years ago they are said 

 to have appeared in great numbers in London and 



its neighbourhood. 



;J ^P 

 * Swallows seldom perch on trees, except in autumn, 



shortly previous to their disappearance, and they then choose 

 dead trees in preference. I have known them sit on trees 

 earlier in summer, when the weather has been very cold. 



