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allf.n’s naturalist’s library 
some time doubted in England, though well-known in Ger- 
many ; but the question was set at rest by two English orni- 
thologists, Mr. Henry Seebohm and Mr. H. J. Elwes who, were 
collecting together in Holland, and who received a nest of 
Redstart’s eggs, one of which, larger than the rest, was said to 
be that of a Cuckoo. The eggs proved to be hard-set, with 
well-formed young inside They were alike blue in colour, 
but on trying to blow the larger egg, the foot of the little bird 
— a zygodactylc foot — protruded from the hole, and effect- 
ually proved that the liny occupant was a veritable Cuckoo. 
In England the most common victims are the Pied Wagtail, 
the Reed-Warbler, and the Meadow Pipit ; and in each case 
there is a remarkable similarity in colouring of the Cuckoo’s 
egg to that of the foster-parent which she selects. It is sup- 
posed that the coloration of the Cuckoo’s egg is an hereditary 
faculty, and that each female Cuckoo lays a particular type of 
egg. This is in all probability the case, ami Cuckoos which 
lay blue eggs come of a stock which has been hatched from 
blue eggs, and will continue to lay them, and deposit them in 
the nest of some blue-egg-laying species. 
Among tlie various types of Cuckoo’s eggs in the collection 
of the British Museum are many which are exact copies of the 
eggs of other birds. In some instances the likeness is truly re- 
markable, and it is curious to see the large egg lying in the nest 
by the side of the smaller ones of the righu'ul parent, precisely 
similar in colour, but double the siiie, looking in fact, like a 
double-yolked egg of the species. In the above-named collec- 
tion are Cuckoo’s eggs showing the e.xact colour and markings 
of the eggs of the birds victimised by the parasitic bird — Pied 
IN’aglairs, Yellow IVagtail’s, Blue-headed IVkagtail’s, Meadow- 
Pipit’s, Tree-Pipit’s, Skylark’s, Chaffinch’s, Reed-Warbler’s, 
Sedge-Warbler’s, Orphean Warbler’s, &c. But these eggs are 
not always deposited in the nests of the species where the eggs 
of the foster-parent exactly resemble those of the interloper. 
In none of the Hedge-Sparrow’s nests, for instance, have we a 
blue Cuckoo’s egg, and it is curious to find an egg like that of 
a Skylark or a Tree-Pipit deposited in the nest of a Marsh- 
Warbler or a Chiff-chaflj the eggs of which are so differently 
coloured that the sombre Cuckoo’s egg lies in striking con- 
trast, and it is wonderful that the little owners of the nest 
do not detect the fraud. This dissimilarity in the colour of 
