SYLVIIDAE. 



SYLVIA ATRICAPILLA (L). 



The eggs of this species are subject to considerable variation in 

 size as well as colour; their relation to those of simplex is parti- 

 cularly close. The spots are mostly not so sharply outlined and 

 occur as a rule more thickly than those on simplex-eggs; the colour of 

 the spots is connected with the ground colour: those with a 

 whitish, reddish or brownish ground colour are spotted brightest, 

 those with a greyish ground colour faintest. On by far the most 

 eggs the lower and middle spots dominate; blending together they 

 frequently cover the larger part of the surface, thereby giving the 

 eggs a marbled appearance. 



In the ,, Catalogue of the Collection of Birds' Eggs in the British 

 Museum", part IV (1905), two eggs are depicted on plate VIII (fig. 

 10 and 14) which, on a white ground colour, are marked on the 

 surface with large chestnut brown spots round the thicker end and 

 for the rest with a few small spots and speckles of like colour. 



Erythrism frequently occurs. 



SYLVIA SIMPLEX LATHAM. 



Eggs of which — as is frequently the case — the lower and 

 middle spots are blended together while the uppermost are wholly 

 lacking or almost so, have a marbled appearance. As is also the 

 case with atricapilla the uppermost spots are rarely large, and they, 

 as well as the speckles, are usually surrounded by 2l penumbra. The 

 ash-grey and yellowish brown spots are always the largest. On the 

 whole the ground colour is brighter than that of atricapilla-eggs; 

 the latter never have the large loam-brown spots which occur on 

 simplex-eggs while the reddish ground colour, which is frequently to 

 be found on atricapilla-eggs, does not seem to occur on simplex-eggs. 



