292 MISS NEWBIGIN Olf THE [Veh. 18j 



the main contention of the relation between the two kinds of 

 feather-edging in Sun-birds. 



Microscopic examination shows that this analogy is not purely 

 superficial. PI. XI. fig. 15 represents three barbules from the 

 yellow edging of a wing-quill of JEthopyga seherice, and PI. XT. 

 fig. 16 three faintly metallic barbules frotii the border of the tuil- 

 quill of Anthreptes malacceiisis (? represented in PI. XII. fig. IS). 

 With these should be compared the brilliantly metallic barbules 

 from the tail-quill oi^iliopyga seherice (PI. XII. fig. 20). Similarly 

 the barbules from the olive tip of a contour-feather of a species 

 of Ginnyris (PI. XII. fig. 24) should be compared with the metallic 

 barbules of Ginnyiis amethystina (fig. 5 or 14)'. These figures 

 show that the barbules of the yellow edging of contour-feathers 

 or quills agree with metallic barbules in having a rudimentary 

 lamina and suppressed cilia, and in distinctly showing a system 

 of overlapping compartments. They differ from the true metallic 

 barbules in the absence of the great flattening visible in these, 

 and in the want of a considerable amount of dark pigment. 

 From the faintly metallic barbules of Anthreptes they seem to 

 differ only in the absence of pigment. The yellow colouring, at 

 least in the case of contour-feathers, is confined to the barbs, 

 the barbules are only very faintly pigmented with grey. The 

 metallic colouring of the Sun-birds is thus the result of an accen- 

 tuation of a type of feather-structure widely spread in the family. 

 I have noticed this occurrence of much modified barbules apart 

 from metallic colour also in the male Pheasant (Fhasianus colchious). 

 Some of the long tail-quills have here a very distinct longitudinal 

 edging of brownish colour and loose texture. Examined micro- 

 scopically, the barbules of this region show distinctly the " metallic" 

 structure although there is no visible metallic colour. Similarly 

 the chestnut feathers of the breast have a very distinct line across 

 them, the distal region having a somewhat burnialied surface, and 

 terminating finally in a dark green metallic tip. Examined micro- 

 scopically the barbules of the distal region show distinctly the 

 " metallic " structure, and except for the absence of black pigment 

 seem to diifer little from the green metallic barbules. The modi- 

 fication is probably a common one, and PI. XI. fig. 13 shows that 

 it is even suggested in the Humming-birds, though in this case it 

 does not appear to develop further. 



Gadow notices that metallic colour appears only on the exposed 

 parts of feathers; apparently the "metallic" modification also occurs 

 only on the exposed parts of feathers near the apices of the barbs. 



One of the most striking features of the coloration of the Sun- 

 birds is the almost universal absence of metallic colour from the 

 wing-quills, even though these sometimes have an edging of loose 

 structure. In Cinnyris aurieeps, according to Shelley, the wing- 

 quills of the female have olive edgings which are absent in the 

 male. It seems reasonable to suppose that a tendency to variation 



' See also Bomo of Giidow's figures, e. g., of a red biirbule of JEthopyga j no 

 allusion, however, is made to tlieso in the text. . 



