the Economy of the Cuckoo. 181 



game-keeper, a man of long-proved exactitude. The fifth, pre- 

 cisely like the others in colour and markings, is of the size of a 

 small Cuckoo's egg in my collection ; yet do I entertain the least 

 doubt as to its origin ? Certainly not. It is unquestionably an 

 egg of S. arundinacea. I really am afraid to say how many eggs 

 of Cuckoos' I have found in the nests of this bird in the course 

 of my annual experience ; but in no one instance can I trace the 

 smallest resemblance, or tendency to resemblance, between the 

 eggs of the two species. The same is the case with Cuckoos' 

 eggs found in the nests of Accentor modularis and Salicaria 

 phragmitis, of which I myself have discovered many. In one 

 instance, on the 30th of June 1863, I found a remarkable 

 Cuckoo's egg in a nest of S. phragmitis, together with two of 

 that bird's. This differed much from the usual type of tlie 

 Cuckoos' eggs found by me in the valley of the Huntingdonshire 

 Ouse, round St. Neot's ; but instead of the divergence in colour 

 and markings approaching to those of S. phragmitis, the result 

 was to make the difference much greater and more conspicuous. 



Of the cases quoted by Dr. Baldamus, that which rests on the 

 strongest evidence is a Cuckoo's egg, in the nest of Hypolais 

 vulgaris, resembling those of that bird. Herr Braune shot the 

 Cuckoo when leaving the nest, and took out of her another egg, 

 ready for exclusion, and similar in colour to the one deposited. 

 This testimony appears to be strong, and I therefore cite it here ; 

 but I think that eggs taken out of a bird by dissection are not 

 to be relied on as showing the matured colour. I do not, how- 

 ever, wish to underrate the value of this instance. 



Another egg, described by Dr. Dehne (' Naumannia,' 1853, 

 p. 203), was laid by a Cuckoo in a cage, and was destined, as 

 Dr. Baldamus thinks " very likely," for the nest of Ruticilla 

 tithys. Now we all know that the eggs produced by captive 

 birds cannot in the least be depended upon. I have several very 

 curious specimens which illustrate this point. 



Dr. Baldamus says it is a fact without doubt " that there are 

 Cuckoos' eggs which in colouring and marking are like the eggs 

 of those Sylviidce in whose nests they are laid," that nature has re- 

 gulated these circumstances to " make easier the existence of the 

 species " and that the Sylviida then become " blind " with regard 



