196 ORNITHOLOGICAL EXPLORATIOKS. 



are " subject to an uninterrupted change from tlie moment when the 

 first dark feathers make their appearance in spring until the last one 

 has disappeared in fall." Additional material and subsequent observa- 

 tions force me to modify this statement to the effect that there are two 

 very different summer plumages indeed — one presestival and one post- 

 sestival, which, however, on account of the uninterrupted change dur- 

 ing the whole summer, are, during the middle part of the season, so 

 blended and mixed together as to justify the expression that there is no 

 marked limit between them. As to my failure in recognizing a third 

 summer plumage I refer here to some remarks further below. 



The first dark feathers of the summer plumage of the male make 

 their appearance on the upper part of the head about the beginning of 

 May. Still, in the middle of June, the greater part of the lower sur- 

 face, except the jugulum and prsepectus, are white, and many white 

 feathers of the old ijlumage are mixed among the dark ones on the 

 upper parts. These dark feathers are more or less uniform blackish ; 

 an explicit description of this plumage will be found further on, sub No. 

 89059. In some males the moulting proceeds more rapidly, in others the 

 process takes longer time. A male shot on the 11th of June, 1883, had 

 much more white than the one referred to above. From this time 

 feathers, more regularly transversely banded, and vermiculated with 

 brown, protrude between the first ones; similarly colored feathers take 

 the place of the white ones below; the first blackish feathers are also 

 shed, until the bird, a little later than the middle of August, has as- 

 sumed its full summer i^lumage, in which even the abdomen and the 

 tibiae are blackish, there being no other white feathers than those of 

 the wings. This perfect plumage lasts hardly fourteen days, as the 

 white feathers of the new winter plumage, simultaneously with the last 

 brown ones, now commence protruding from their sheaths. In the mid- 

 dle of October the bird has the white and brown similarly distributed 

 as in the middle of June, and before the middle of November the perfect 

 white plumage is completed. 



The moulting of the wing-feathers takes place about the time when the 

 summer plumage is most perfect, that is to say, about the middle of 

 August. The new primaries have then blackish shafts, a color which 

 in the following spring fades away, so that the old feathers when shed 

 have almost wholly white shafts. 



The late Prof, Sven Nilsson was the first who discovered that the 

 ptarmigans yearly shed their claws as regularly and completely as they 



