Family SYLVIIDAE. 

 Hypolais hypolais (L.) — Icterine Warbler. 



(Plate 58, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 38, No. 88). 



Colour of surface of shell 



Colour of spots: 



Average dimensions: 

 Average weight of shell: 

 Texture of shell: 



Shape : 

 Nest: 



Site of nest: 



Number of eggs: 

 Breeding season: 

 Duration of incubation: 



rose-pink. 

 My examination of eggshells 

 proved that Thienemann's sta- 

 tement, namely that of this 

 species the shell is coloured 

 r o s e-p ink through and through to 

 the inner membrane, is incorrect. 

 The pigment impregnation only 

 extends to the uppermost layer 

 of carbonate of lime; below that 

 the shell is chalky white thickly 

 dotted with extremely fine red 

 specks visible only to theaided 

 eye. 



dark brown. 

 The spots are now and again surrounded 

 by a faint penumbra, and are often accom- 

 panied by a few very fine veins. 



18.47 X 13.4 millimetres. 



0.092 gram. 



is distinguished from that of all other species 

 of the Family by a much finer granulation. 



mostly oblong ovoidal. 



is built of vegetable materials, especially of 

 much seed down, and material spun by 

 insects, mostly covered on the outside with 

 birch-bark and sometimes with feathers as 

 well; lined with hair and in some instances 

 with feathers. 



generally at about 3 Metres from the ground — 

 sometimes lower, sometimes much higher — 

 in bushes and in the lower branches of trees. 



5-6. 



May— July. 



about 13 days. 



