16 Dr Rose on Zinkenite, a new Mineral Species. 



the plumage of a young cock of such or such an age. It is 

 remarkable, that such a diversity should exist among circum- 

 stances tending to produce the same end. 



The observations of Mauduit had already shown, that hen 

 pheasants resembled the males in their old age ; that the change 

 in the plumage is gradually produced, and more decided, as 

 age advances; and that the ovary is so much obliterated in 

 many of such females, as to be no longer perceptible. It 

 should be presumable, that those in whom the ovary had thus 

 disappeared, were the examples in which the plumage was 

 most changed, which is not the case ; for this organ was not 

 found in females imperfectly resembling males, while I have 

 seen it, in the instance we have described, where the resem- 

 blance was absolutely perfect. 



To these facts my observations have contributed the follow- 

 ing additional ones : — that the change of plumage commences in 

 some females later than in others — that it may either manifest 

 itself some years after the female ceases laying, (though it de- 

 pends more or less directly on this phenomenon,) or concide with 

 that cessation — that it occurs usually in the fourth year, when 

 the change is perfected, and that the female has then- not only 

 the colours, but the splendour of the male — that, like him, 

 she may exhibit spurs — that the progression from dull, to 

 the brilliant plumage of the adult male, is effected differently 

 in the young male and in the old female, although the result be 

 precisely the same ; — and lastly, that the change of plumage in 

 old females among birds, is not a general fact ; and that, be- 

 cause it has been remarked in one genus, it does not even cer- 

 tainly exist in other genera of the same family ; while, on the 

 other side, many other distant groups appear to afford ex- 

 amples of this remarkable phenomenon. 



Having given the facts regarding the change of plumage in 

 the hen-pheasant, as detailed by M. Saint-Hilaire, it may be 

 proper to state, that such changes of plumage are by no means 

 confined to this species of bird. In a paper on this subject in 

 the Wernerian Transactions, by Mr John Butter, (vol. iii. 

 p. 183,) which M. Saint-Hilaire does not appear to have seen, 

 a number of facts are recorded of the plumage in female birds 



