ON THE HEPATIC PLUMAGE OF THE CUCKOO. 323 



of the colouring matter of the feather, or, on the return season, 

 a gradual development of the same colouring matter in the 

 old feather. 



This is, I know, a subject of great importance, and one 

 which is not yet understood by ornithologists ; but I have been 

 patiently working at it for some years, and have collected such 

 a mass of information as to leave no doubt in my mind that my 

 theory is correct, for I can show feathers in all stages of fading 

 and acquiring the colouring matter, and also showing two distinct 

 and widely different states of plumage on one feather. 



So far as my experience goes, the chief moulting period for 

 wild birds is in the autumn, after the breeding season. Spring 

 moults are comparatively rare, and when they do occur are 

 generally only partial. 



This is obviously a subject which I cannot fully deal with in 

 this article. Suffice it to say that the two Cuckoos under notice 

 fully confirm my previous investigations. They show at a glance 

 both the hepatic and the adult stage, and show also that the cin- 

 namon or reddish colour is slowly fading away and giving place 

 to the grey stage, ivithout moulting. In the bird most advanced 

 towards the grey plumage there is not a trace of moulting, while 

 in the other there is one solitary rectrix moulting, but I think it 

 highly probable that this was to replace one accidentally lost, for 

 the new rectrix is of the hepatic and not the grey type. 



Mr. Harting (pp. 257, 258) has minutely described his bird 

 which was shot in April, and it will be seen that the whole of the 

 upper parts displayed the reddish tinge of colour. 



My first bird, shot on May 4th, shows on the crown of the 

 head the grey of the adult, but the feathers very faintly barred 

 in the middle with sandy brown, almost imperceptible until 

 they are divided. The sides of the head, the lores, chin, and 

 throat are a greyish white, suffused with pale brown and very 

 faintly barred. The whole of the neck, upper back, and breast 

 are of a cinnamon or light liver-colour, barred with blackish. 

 The primaries and secondaries are a faded brown, spotted and 

 barred on the outer and inner webs with reddish ; some of the 

 tertiaries are distinctly brown. The scapulars and all the wing- 

 coverts are grey, with very distinct brown spots. The back and 

 rump is grey, as in the adult, but with a trace of brown spots 

 here and there. The upper tail-coverts distinctly reddish, and 



2 c 2 



