NESTLING FEATHERS OF THli MALLARD. G25 



Like plumose or metaptile feathers, the plumnlce vaiy in size, 

 colour, aud structure, but they, as a rule, consist of a calamus, 

 a shaft, and an aftershaft. The calanjus, especially well developed 

 in tlie Eider Duck, is barrel-shaped and contains relatively large 

 cones. As it leaves the skin it divides into two portions, an 

 outer which forms the short rhachis of the shaft, and an inner 

 which forms the still shorter rhachis of theaftershaft(Pl. V.fig. 18). 

 The shaft consists of a dozen or more pairs of very long slender 

 barbs from which spring numerous slender barbules, the proximal 

 portions of which are charactei'ized by pyramidal swellings, 

 while the distal portions like the preplnmulse have nodular 

 swellings. The aftershaft (PI. V. fig. 18) is always well developed, 

 and like the shaft is largely made up of long bai'bules having the 

 characteristic pyramidal swellings. When a pknnula is shed the 

 tip of the sheath of the growing new plumula is often found 

 attached to the calamus. Evidence of this we have in PI. Y. 

 fig. 19. 



(3) Prefiloplitmce and Filoplumce. 



Nitzscli, in his account of filoplumae, says they are strikingly 

 distinguished from the other three kinds of feathers (contour, 

 down, arid semiplume feathers) by their peculiar position, their 

 extraordinary slenderness, and by the entire deficiency or very 

 small size of their vane ; but he states subsequently that he 

 believes the narrow white down}'' feathers of the Cormorant must 

 be regarded as filoplumes, even though they are furnished with 

 perfect vanes. Nitzsch further mentions that filoiDlumes are 

 " associated with the contour feathers, one or even two filoplumes 

 standing quite close to every contour feather of the head, neck, 

 and trunk, apparently issuing almost out of the same pouch of 

 the skin." Filoplumes a.re usually regarded as degenerate 

 feathers because during development they have barbs arranged 

 after the fashion of a down (plumula) feather. 



In the Mallard daring development there are usually two or 

 more minute filaments at each side of the filaments containing 

 the wing-quill protoptiles. These minute filaments contain 

 prefiloplumse. In text-fig. 10 the two short filaments (P. 2) 

 lying in contact with the large protoptile filament are prefilo- 

 plume filaments. 



In the newly-hatched duckling the minute prefilopluma) and 

 the large wing-quill protoptiles escape simultaneously from their 

 sheaths — being barely visible to the naked eye, the prefiloplumaj 

 have apparently hitherto escaped the notice of oi'uithologists. 

 In course of time, as the protoptiles are pushed from the skin by 

 mesoptiles, the prefiloplumfe are pushed from the skin by 

 filoplumse. The wing-quill protoptile of a thii-ty-eight days' 

 duckling represented in PI. II. fig. 8 is attached to a developing 

 mesoptile. At the base of the mesoptile are three young filo- 

 plumes, two of which support prefiloplumes — a young filoplume 

 with a prefiloplume attached to its tip is also seen in PI. Y. tig. 17. 



42* 



