48 ORNITHOLOGICAL EXPLORITIONS. 



feathers commences, the ear-tufts at the same time making their ap- 

 pearance ; these are at first of an isabella-brown color, afterwards chan- 

 ging into pale straw-j'ellow, (|)late ii, fig. 4). The under parts of the 

 new plumage are darker (though never glossy), and the contrast be- 

 tween the under tail-coverts and the rest is, consequently, less con- 

 spicuous, but the most radical change occurs in the coloration of the 

 face, which now assumes the white " mask," and the young of the year 

 is now indistinguishable from the old birds as far as plumage is con- 

 cerijed. 



As mentioned above, the material at hand seems to justify the con- 

 clusion that remiges and rectrices are not shed at this moult, but at 

 the next one, which takes place in September (earlier or later accord- 

 ing to circumstances), or when the incubation is finished. At this 

 moult the long ear tufts are thrown off, the white "mask" is replaced 

 by blackish gray feathers; all the other feathers are likewise shed, 

 without any change, however, in the general color of the rest of the 

 plumage. It has also been mentioned above that the time when the 

 moult takes place is very variable in different individuals, a fact which 

 should always be borne in mind. On the 22d of August, 1882, I ob- 

 served a single old bird, with large red bill, having already changed 

 its mask and dropped the ear-tufts, but it was the only one in a large 

 flock of many hundreds ; on the other hand, individuals are found which 

 have not assumed their winter plumage as late as the end of October. 

 The adult bird in winter is represented in fig. 2, pi. i. 



Parallel with and corresponding to this moult of the plumage the re- 

 markable shedding of the basal parts of the bill takes place. Mr. Bureau 

 has the honor of first having pointed out this fact, but for want of suffi- 

 cient material he had to content himself mostly with hyiwtheses and as- 

 sumptions, consequently falling into several errors. Dr. Dybowski 

 afterwards observed parts of the process, but, not content with the facts 

 observed, went on speculating, and, needless to say, consequently, also 

 made grave mistakes. It will, therefore, be expedient to point out and 

 correct these befoi e proceeding to a detailed account of the process as 

 it actually takes place. 



The figures representing the heads of Lunda cirrhata, and accompany- 

 ing the two articles of Mr. Bureau are not only crude, but in several 

 points absolutely erroneous, it being sufficient to compare fig. 4 of pi. 

 V, Bull. Soc. Zool. France, 1877, with those on pi. iii, op. cit., 1879, 

 particularly the grooves, the crest, and the lower end of the horny 



