220 OBSERVATIONS ON THE CHANGES OP 



moult ; the other two were mottled, and the points of the feathers were 

 edged with brown. They were receiving new feathers extensively on 

 every part of their bodies ; one of the birds would probably have been 

 in full plumage in a week, the other was less advanced, and would have 

 required a longer time. Whether these were young birds receiving 

 their bright colours for the first time, or old birds renewing their co- 

 lours by a fresh moult, I could not ascertain. 



The arguments of Dr Flemming (vol. II., p. 26, 27) in favour of 

 his theory that a spring moult is unnecessary to a change of colour in 

 feathers, as confirmed by the examination of Captain Cartwright on 

 the Ptarmagin (Tetrao lagopus) of Labrador, is very far from being sa- 

 tisfactory to my mind ; on the contrary, it appears to me that Cart- 

 wright's own notes, taken on the spot, ought to have caused the Doctor to 

 have hesitated, before he adopted, so confidently, a theory which may 

 yet be discovered, on a more careful examination, to be wholly founded 

 in error. The following is an extract from the Captain's Journal (see 

 Transactions, On the Coast of Labrador, vol. I., p. 278): "When I was 

 in England, Mr Banks [Sir Joseph Banks], Dr Solander, and several 

 other naturalists, having inquired of me respecting the manner of these 

 birds changing colour, I took particular notice of those I killed, and 

 can aver for a fact, that they get at this time of the year (September 

 28) a very large addition of feathers, all of which are white, and that 

 the coloured feathers at the same time change to white. In spring, 

 most of the white feathers drop off, and are succeeded by coloured ones, 

 or, I believe all the white feathers drop off, and they get an entire new 

 set. At the two seasons they change very differently; in the spring 

 beginning at the neck, and spreading from thence ; now they begin at 

 the belly, and end at the neck." Captain Cartwright here asserts that 

 the Ptarmagin, in autumn, receives a very large addition of white fea- 

 thers, but that the coloured feathers are changed to white. I perceive 

 no difficulty in explaining this autumnal change. Presuming that the 

 birds moulted in the middle of August, as is the case in Labrador, some 

 of the feathers would not come out pure white, but would gradually 

 become so, as is the case with other birds I have mentioned, and they 

 would thus, for a time, retain a mottled appearance. The summer 

 moult in birds extends over the whole body, even to the wing and tail 



