1896.] METALLIC COLOUES OF BIEDS. 2&6 



EXPLANATION OF PLATES XL & XII. 



Fig. L Violet metallio feather of Ciniiyris ameihjstina, showing three zones: 

 o=npical raetiillic zone ; 6=browii pigmented zone with closely 

 connected barbules and basal indentation ; c=downy basal zone. 

 Fig. 2. Two downy barbules from eamo : Z=rudimentary lamina; /=filament- 

 ous region, much elongated and with rudimentary oilite. Objective 

 i", Ocular B. 



Fig. 3. Proximal radius from region 6 of same, showing well-developed lamina, 

 slightly pigmented and marked with cross-bars, and filamentous 

 region with well-developed cilia. Ob. J", Oo. B. 

 Fig. 4. Proximal radius of same, showing transition to metalliccondition. The 

 lamina is rudimentary, and the filamentous region is pigmented and 

 somewhat expanded. Ob. J", Oc. B. 

 Fig. 5. Metallic radius of same, shiiwing shape, compartments, and peculiar 

 flattening. The last three figures are all of radii taken from different 

 levels on the same barb. 

 Fig. 6. Fragment of metallic barb under low power, to show position of 



barbules: 7)=proximal radii; rf=distal. Ob. 1", Oc. B. 

 Fig. 7. Metallio feother from gorget of Ba-iilinna, leucotis: «=naked barbs, 

 corresponding to zone a of fig. 1; 6 = metallic region of feather, 

 corresponding to zone b of fig. 1 ; c=downy region. 7 a is a diagram- 

 matic croas-seolion of a single barb, to illustrate the formation of the 

 surface-ridges of the feather: (i= distal radius; p=proximal radius; 

 J = barb. 



Fig. 8. Proximal radius from the base of one of the metallio barbs of above 

 feather. Tlie lamina is only faintly pigmented. Ob. \", Oc. B. 



Fig. 9. Distal radius from brilliantly metallio region of same. The lamina is 

 deeply pigmented and has a folded-in edge. The filament is without 

 pigment. Ob. V. Oc. B. 



Fig. 10. Fragment of metallio barb of s.Tme with distal barbules only, to illus- 

 trate normal position of barbules. Owing to the angle of insertion of 

 the filamentous region, this is not visible in surface view. Ob. \", 

 Oc. B. 



Fig. II. Tip of barb of breast-feather of Eui'teplianus fernandens'S J, to illus- 

 trate apical modification of barbules. The lower barbules in the 

 figure are metallio. Ob. 1", Oo. B. 



Fig. 12. Tip of barb of goiget-foather of Basilinna leucotis, with naked barb 

 furnished only with rudiments of apical barbules. Ob. 1", Oc. B. 



Fig. 13. Barbules from three different levels on a barb of a contour-feather of 

 Phacthomis curyiwme to show details of the modification of the original 

 apical barbules. Note in passing towards the apex of the barb the 

 reduction of the lamina and Battening of filamentous region. The 

 filamentous region is, however, unpigmented. Ob. J", Oc. B. 



Fig. 14. Fragment of barb of Cinnyrh ameihijslina for comparison, and to show 

 junction of metallio and non-inetalhc regions. Ob. 1", Oc. B. 



Fig. 15. Three barbules from the yellow edging to a quill oiJSthopyga, sekeritg. 

 Ob. 1", Oo. B. 



Fig. 16. Three barbules from metallic edging of quill of Anthreptes malaccensis. 

 Ob. i", Oc. B. 



Fig. 17. Tail-quill of Anthreptes malaccensis (?), with metallio edging on right 

 side {pi). 



Fig. 18. Three non-metallio barbules from above. Ob. J", Oc. B. 



Fig. 19. Three metallio barbules from tail-quill of Eustephanus fernandensis, 

 Ob. i", Oo. B. 



Fig. 20. Three brilliantly metallic barbules from central tail-quill ot Mthopyga 



Sfihprl/p. Ob. J- , Oc. B. 



Fig. 21. Barbules from some quill, but much nearer rachis ; they show partial 

 transformation, and in their natural position exliibit a faint tliougli 

 distinct metalhc sheen. This partial transformation occurs chiefly in 

 the case of distal barbules, and produces a visible elfect to the unaided 

 eye. Ob. \", Oo. B. 



