Family MACROPTERYGIDAE. 



Apus apus (L.) — Swift. 



(Plate 91, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 53, No. 129). 



Colour of surface of shell: 

 Average dimensions: 

 Average weight of shell: 

 Texture of shell: 



Shape : 



Nest: 



Site of nest: 



Number of eggs: 

 Breeding season: 

 Duration of incubation: 



dull white. 



24.7 X 16 millimetres. 



0.22 gram. 



characterized by a fine uniform granulation 

 (Quite incorrectly described as „coarse 

 grained" by some authors). 



elongated. 



consists of straws, leaves, hair and feathers, 

 all sorts of rags, etc., agglutinated together 

 with mucous saliva, which soon dries by 

 the action of the air, and gives it a var- 

 nished appearance. 



in holes and crevices in the walls of towers 

 and other buildings; under roof-tiles, etc. 

 in forests: in tall hollow trees; always in 

 colonies. 



2 (in exceptional cases 3-4). 



end of May-June. 



about 16 days. 



