292 MISS NEWBIGIN ON THE [ Feb. 18, 
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, Pl. XI. fig. 15 represents three barbules from the 
yellow edging of a wing-quill of Athopyga seherie, and Pl. XI. 
fig. 16 three faintly metallic barbules from the border of the tail- 
quill of Anthreptes malaccensis (? represented in Pl. XII. fig. 18). 
With these should be compared the brilliantly metallic barbules 
from the tail-quill of Zthopyga seherie (Pl. XII. fig. 20). Similarly 
the barbules from the olive tip of a contour-feather of a species 
of Cinnyris (Pl. XII. fig. 24) should be compared with the metallic 
barbules of Cinnyris 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 (Phasianus colchicus). 
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 burnished 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 differ little from the green metallic barbules. The modi- 
fication is probably a common one, and Pl. 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 auriceps, according to Shelley, the wing- 
quills of the female have olive edgings which are absent in the 
male. 1t seems reasonable to suppose that a tendency to variation 
1 See also some of Gadow’s figures, ¢. g., of a red barbule of Athopyga; no 
allusion, however, is made to these in the text. 
