57 [Vol. xliii. 



accepting theoretical claims. A great part o£ Mr. Chance's 

 observations are based on experience with a single bird, 

 consequently no claim can be, or is, made to apply generally 

 to the habits o£ the Cuckoo. The Reed-Warbler Cuckoos 

 would necessarily behave in a totally different manner. 



After careful study of Mr. Chance's paper, I have looked 

 in vain for some proof that he actually saw the eggs laid, 

 but he states that he saw them deposited, which is quite a 

 different matter, and I doubt, even with the most modern 

 field-glasses, that it would be possible to see exactly what 

 took place at 150 yards, though it would be quite possible 

 to see the bird alight at a given or marked spot. 



I see nothing remarkable in a Cuckoo laying over 20 eggs, 

 if we take into consideration the great procreative powers 

 among birds generally. 



The Wryneck will, under a similar forcing process, 

 produce up to sixty-two eggs (' History of the Birds of 

 Kent,' p. 231), the Sparrow-Hawk twenty-two, and the 

 Ringed Plover sixteen. 



Until we have some concrete proof to the contrary, we 

 must not ignore entirely the possibility of closely related 

 females having produced these 21 eggs. 



Bearing in mind the admission that other Cuckoos were 

 seen on this restricted area, the difficulty of ascertaining the 

 proportions of the sexes (except by the notes) when more 

 than one or two are present must be borne in mind. 



I have carefully examined and weighed the whole of these 

 eggs, and noted according to the blow-holes the various 

 stages of incubation. The system adopted by Rey, and 

 apparently by Mr. Chance, of dating back incubated eggs 

 is, I consider, both dangerous and inconclusive in arriving 

 at the exact date of deposition, therefore too much importance 

 must not be attached to Rey's theory, i. e. that the Cuckoo 

 lays its eggs at intervals of 48 hours. 



I have two clutches with two Cuckoos' eggs each, each 

 pair obviously by the same female, and curiously enough 

 both with Yellow-Hammers ; the first was taken by Mr. W. 

 L. Leader in Norfolk on June 1, 1908 ; these two eggs are 

 of a very uncommon type with greenish-blue ground: 



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