54 -^(A History of Common Cuckoo. 



Handbook of British Birds, we find him following 

 Mr. Seebohm in the idea that the cuckoo which 

 lays blue eggs had itself come from a blue eg^, and 

 always lays blue eggs, and so with the other coloured 

 egg-laying cuckoos. But this seems to carry the 

 great difficulty only one short step further back. 

 How did the cuckoos get differentiated into different 

 coloured egg -layers ? It could not have been before 

 the habit had been formed of putting the eggs into 

 other birds' nests. If the cuckoos, then, became at one 

 step definitely classed as blue egg-layers, fly-spotted 

 blue egg -layers, light -brown blotched egg -layers, 

 or dark -brown blotched, or lark -like egg- layers, 

 and so on, is that not even as much a mystery as 

 though we were to allow some individual variation in 

 the coloration of eggs ? Let anybody look at the 

 fifteen different eggs of the cuckoo carefully engraved 

 and coloured in the supplement of Seebohm's British 

 Birds, or at the sixteen coloured specimens from Dr. 

 August Baldamus in Naumannia, and he will admit 

 that something wholly unexampled and exceptional 

 must apply to a class of birds producing such varied 

 eggs. The problems connected with the cuckoo are 

 not yet by any means settled ; so there is an interest- 

 ing field of observation and inquiry still left open for 

 any ambitious young naturalist. 



Among the blue eggs of Mr. Pralle's collection, 

 Mr. Seebohm speaks of blue eggs uniform, unspotted, 

 and of others with spots, — faint spots, like fly-spots. 

 Now, what I wish to ask on this head is, are the uni- 

 form blue eggs confined to one bird or definite family 

 of birds, and each of the variously fly-spotted eggs to 

 another bird or class of birds. By this process we 



