132 BRITISH BIRDS. [vol. vn. 



of its oviduct proved that it had never laid eggs. In Volume IV., 

 p. 370, Mr. E. Dunlop mentioned that he had once seen a Rook that 

 was imdoubtedly breeding which had the face only partially bare of 

 feathers, and there is other evidence that such birds are sometimes 

 present in Rookeries in the breeding-season. It seems just possible 

 that such birds may act as " niu-ses," and I think the point w^ould 

 be well worthy of investigation, but it would be necessary after 

 watching such birds at the nest, to secure them and examine their 

 sexual organs. 



At the moult into second winter-plumage, and at 

 every subsequent autumn-moult when the bird is adult, 

 the bare space on the chin and upper-throat becomes 

 thickly covered with dark blackish-grey down (Plate 4, 

 Fig. 9) . This consists of the new plumules and filoplumes, 

 which moult annually, and a varying number of degenerate 

 plumule-lil^e feathers groAving from the true contour- 

 feather papillae, but many (probably the majority) 

 of the first-summer "'•' pins " remain and are not moulted. 

 The degenerate feathers are exactly smiilar in structure 

 (Plate 9) to those w^hich grow here and there at the first 

 summer-moult, but they are rather larger (about six 

 to eight millimetres in length) and more numerous. 

 Their rami and radii, being loose and comparatively 

 long, spread in all directions and hide the " pins," so 

 that the whole chin appears to be well covered. 



Only a few minute degenerate bristles grow here and 

 there on the nostril-region, fore-head, and on the sides 

 of the lower mandibles, and these are scarcely noticeable 

 without a glass. The papillae of these regions appear 

 to remain almost inactive at the moult, most of them 

 showing no sign whatever of feather-growth. The 

 " pins " which grew^ in the moult to first summer 

 remain, and have become roimded and compacted. 

 A varying number of filoplumes, however, grow in 

 these regions, some specimens having many and others 

 scarcely any. 



Unlilve the birds in their first year, there is now no 

 further moult until the following autumn. The down 

 on the chin and tliroat does not fall out, but becomes 

 gradually worn down by abrasion (Plate 4, Figs. 



