Family HIRUNDINIDAE. 

 Riparia riparia (L.) — Sand-Martin. 



(Plate 84, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 53, No. 128). 



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: 



white, less glossy than urbica-eggs. 



17.2 >< 12.4 millimetres. 



0.074 gram. 



the granulation is considerably finer than 

 that of urbica-eggs; the difference is visible 

 with the unaided eye. 



oblong ovoidal, usually still more pointed 

 than urbica-eggs. 



consists of vegetable materials, lined with 

 feathers. 



in burrows of from about 50 centimetres to 

 about 2 Metres depth, excavated by the 

 birds themselves in sandy banks, sand pits, 

 earthen embankments, etc. (in colonies). 



5, sometimes 6. 



end of May-middle of July. 



13 days. 



