294 THE STORY OF THE BIRDS 



of the Common Guillemot. A judiciously se- 

 lected collection of these eggs justly forms one 

 of the most wonderful attractions of the oolo- 

 gical cabinet. In no other known species does 

 the egg vary so widely. The ground colours 

 are dark green, yellowish green, reddish brown, 

 cream yellow, white, and pale blue, with every 

 intermediate shade ; the markings are browns, 

 and greys and pinks of every possible tint, and 

 take the form of spots, splashes, blotches, streaks, 

 zones, and intricate netted tracery. Then we 

 have certain species in which the individuals 

 produce distinct types ; as in the Grass Warbler 

 (Cisticola cursitaus), the eggs being either white 

 or blue spotted with rufous, and sometimes un- 

 spotted blue or white. The Common Cuckoo 

 is also known to produce several very distinct 

 types of eggs, one being unspotted blue. The 

 uniformity of colour in other groups is just as 

 remarkable. The Herons are always some shade 

 of blue or green ; the Game Birds, although dif- 

 fering considerably in general colouration, may 

 always be distinguished by the entire absence of 

 underlying markings ; the Pigeons are always 

 white or the palest of cream colour ; the Parrots 

 are white ; the Birds of Prey are marked with 

 reddish brown only ; most of the species in the 



