Vol. xxxiii.] 68 



from eclipse- to breeding-plumage and vice versa can be 

 induced to grow by pulling out feathers either in early 

 autumn or in late spring. 



Mr. H. F. Witherby exhibited specimens of the Rook 

 {Corvus f. frugilegus) to show the various stages by which 

 the u face" becomes bare. He had already given in 

 ' British Birds ' (vol. vii. pp. 126-139) a detailed account of 

 his investigations, and now briefly explained that the Hook's 

 head went through the following stages : — 



"Juvenile. The head is normally feathered and there is a 

 thick growth of bristle-like feathers over the nostrils. Some 

 of the feathers on the chin are very often white. 



"First ivinter. After a normal moult in July and August 

 the head is again completely feathered like that of the 

 Carrion- Crow. 



" In January (or, in some individuals, rather later) a 

 gradual moult commences on the chin, the fallen feathers 

 are mostly replaced by ' pins ' showing no feather-growth, 

 and here and there by degenerate down-like feathers resem- 

 bling plumules in structure. The plumules themselves and 

 the filoplumes on the chin and throat are not moulted. 



"By the time the chin is half bare the small feathers and 

 bristles at the base of the mandibles begin to fall out, and 

 the moult creeps up to the region under the eyes and the lores, 

 and, lastly, the nasal bristles are lost. In all these regions 

 the proximal feathers fall first and, while some of the papillae 

 remain dormant and a distinct cavity is left where the feather 

 fell out, most produce short knob-like " pins " from which 

 no feather-growth appears. The whole process is a lengthy 

 one, and even by the middle of June is not complete in some 

 specimens. As the summer advances the downy growth 

 on the chin and throat gradually wears away and the skin 

 becomes hard. 



" At the second autumn-moult, and at every subsequent 

 autumn-moult of the adult Rook, the bare part of the chin 

 and throat becomes well-covered with a blackish-grey down- 

 like growth, which consists of plumules, filoplumes, and 



