1896.] ON THE METALLIC COLOURS OF BIRDS. 283 
EXPLANATION OF PLATE X. 
Fig.1. Hypetra leucoptera, p. 264. Fig. 16. Jolaus nursei, 3, p. 251. 
2. Emmiltis nigrescens, p. 267. 17. Pupa of Teracolus halimede, 
8. Ephyra rufistrigata, p. 267. pp. 246, 253. 
4. Aporodes albilinealis, p. 274, 18. Pupa of Teracolus pleione, 
5. Crambus leucozonellus, p. 269. p. 245. 
6. Eublemma ecthemata, p. 262. 19. Eublemma seminivea, p. 262. 
7. Nephopteryxr  metamelana, 20. Acidaliastis micra, p- 267. 
p. 271. 21. Crinipus leucozonipus, p. 277. 
8. Heliothis pictifascia, p. 259. | 22. Nephopteryx nigristriata, 
9. Xanthoptera mesozona, p. 261. p. 272. 
10. Aplectropus leucopis, p. 275. 23. Archinola pyralidia, p. 259. 
11. Metachrostis  atribasalis, 24. Hremocossus proleuca, p. 276. 
p- 261. 25. Spilosoma arabicum, p. 258. 
12. Parasa fulvi-corpus, p. 276. 26. Pseudaglossa fumosa, p. 266. 
13, Pupa of Teracolus phisadia, 27. Nemoria pulvereisparsa, p. 268. 
pp. 245, 252. 28. Hromene pavonialis, p. 269. 
14, Pupa of Teracolus yerburii, 29. Hurycreon albifascialis, P. 276. 
pp. 246, 254. 30. Hpicrocis erubescens, p. 272. 
15. Pupa of Teracolus protomedia, 31. Pseudophia aclirtboici, p- 264. 
p- 256. 
83. Observations on the Metallic Colours of the Trochilide 
and the Nectariniide. By Miss Marion I. Newsiern, 
B.Sc.! 
Received January 13, 1896. 
(Plates XI. & XIL) 
The metallic colours of birds form a subject of great interest, 
and one, moreover, which has not yet been fully investigated. 
The great interest of the subject lies in the fact that metallic 
colour in birds is often almost entirely confined to the male sex. 
Tf the colours and ornaments of the male sex are, as Wallace and 
others have maintained, an expression of his greater “ vitality and 
growth-power,” it may reasonably be asked why this vitality 
should so frequently express itself in structural colour, which can 
hardly be supposed to have much physiological importance. 
Although the present paper does not profess to attack the problem 
of the origin in the physiological processes of the individual of 
these colours, yet it is hoped that some of the points discussed 
may ultimately prove of service in the solution of this problem. 
The families of the Humming-birds and Sun-birds were chosen 
for two reasons. In the first place, both families include species or 
genera exhibiting metallic colouring of extraordinary brilliancy, 
and also other genera and species which are devoid of all metallic 
colouring. In the second place, the two families present marked, 
if superficial, points of resemblance, although systematists are all 
agreed in separating them very widely. On this account it was 
thought that a detailed comparison of their colouring would disclose 
facts of interest. 
1 Communicated by F. E. Bupparp, F.R.S. 
