384 BRITISH BIRDS. 



entrust the care of its eggs to foster-parents of the same species as those 

 which tended it in its infancy. The eggs of the Cuckoo are laid from the 

 last week in May to the first week in July. It would be impossible to 

 describe or figure all the variations to which they are subject. The three 

 commonest types are nos. 11, 12, and 13 in the Plate (which are usually 

 laid in the nest of the Reed- War bier), nos. 2, 5, 8, 9, and 14 (usually 

 entrusted to the care of the Meadow- and Tree-Pipits), and nos. 10 and 15 

 (of which the foster-parents are Pied or White Wagtails). It is very seldom 

 that the Cuckoo's egg is found without small round dark markings, like 

 fly-spots. These spots are sometimes almost obsolete ; and I have taken 

 a young Cuckoo out of a blue egg on which they were so pale as to almost 

 escape notice (' Zoologist/ 1880, p. 361). They vary in length from TO 

 to 1*8 inch, and in breadth from '75 to '61 inch. The following is a 

 list of the eggs figured on the Plate, giving the locality where they were 

 procured, and the number of eggs found in the same nest : 



1. Pomerania, with 5 of Gar den -Warbler. 



2. Cheshire, with 3 of Meadow-Pipit. 



3. Asia Minor, with 4 of Orpheus Warbler. 



4. Malaga, with 1 of Cuckoo and 4 of Orpheus Warbler. 



5. Cheshire, with 4 of Meadow-Pipit. 



6. Eastbourne, with 1 of Cuckoo and 1 of Reed-Warbler. 



7. Holland, with 4 of Redstart. 



8. Cheshire, with 3 of Meadow-Pipit. 



9. Cheshire, with 1 of Cuckoo and 3 of Meadow- Pipit. 



10. Cheshire, with 4 of Pied Wagtail. 



11. Pomerania, with 2 of Common Wren. 



12. Pomerania, with 3 of White Wagtail. 



13. Derbyshire, with 2 of Hedge- Sparrow. 



14. Surrey, with 3 of Yellow Hammer. 



15. Pomerania, with 4 of White Wagtail. 



Most of these eggs closely resemble those belonging to the foster- 

 parents ; but no. 6 was probably intended to be placed in the nest of a 

 Pied Wagtail, nos. 11, 12, and 13 in nests of Reed- Warblers, and no. 14 

 in that of a Tree-Pipit. 



The change of plumage in the Cuckoo is extremely puzzling but the 

 following appears to me to be the best explanation of the variation to be 

 found in a large series of skins. Young in first plumage have the feathers 

 of the upper parts barred with chestnut and tipped with white, males 

 differing from females in having no chestnut on the rump and upper tail- 

 coverts and very little on the tail, whilst the white tips are purer in colour 

 than in the female. After the first spring moult the difference between 



