Vol. xxix.] 42 



sometimes tipped with white, and with more or less white 

 towards the base. The middle pair, which are always the 

 last to appear, are attained towards the end of September 

 or early in October, and vary greatly in colour in different 

 individuals. 



'' Dealing first with the males : in October it will be found 

 that the middle tail-feathers are black, or black mottled 

 Avith grey, with or without white tips ; wholly white ; or 

 some intermediate mixture of coloration between these 

 two extremes, the feathers in some individuals looking as 

 though they might be gradually changing to pure white. 



" Through the kindness of the Marquess of Breadalbane 

 I have recently received two lots of freshly killed Ptarmigan 

 from Black Mount, Argyllshire, and these I exhibit here 

 to-night. They present the following peculiarities : — 



'' Of six males, three have the middle tail-feathers black 

 tipped with white, one having also some white on the basal 

 part of the webs ; two have one feather black tipped with 

 white and the other pure white, tlie position of the white 

 feather being reversed in the two specimens; in the sixth 

 example both middle tail-feathers are pure white. 



" In the British Museum collection there are specimens 

 with mottled middle tail-feathers, partially black and 

 partially white ; but I am now fully satisfied that these 

 mixed feathers are produced in that condition, and that, 

 in the present case at least, there are not the slightest 

 grounds for believing that any change of pattern takes place 

 after the feather is fully grown. 



In the female the middle pair of tail-feathers are usually 

 finely mottled with sandy-grey and black and tipped with 

 white, the white tips being often divided from the mottled 

 portion of the web by a narrow black band ; in some speci- 

 mens, however, both feathers are pure white, while in others 

 one is mottled and the other is Avhite. Wiien the nesting- 

 plumage is assumed the middle tail-feathers are usually cast 

 and replaced by black feathers barred and mottled with rufous 

 like the rest of the breeding-plumage. This remarkable 

 peculiarity, so far as I am aware, has not hitherto been 



