Chap. XY. 
COLOUR AND NIDIFICATION. 
173 
the females. This is a significant fact, for such differ- 
ences in colour must be accounted for on the principle 
of some of the variations in the males having been from 
the first limited in their transmission to the same sex ; 
as it can hardly be maintained that these differences, 
especially when very slight, serve as a protection to 
the female. Thus all the species in the splendid group 
of the Trogons build in holes; and Mr. Gould gives 
figures of both sexes of twenty-five species, in all of 
which, with one partial exception, the sexes differ some- 
times slightly, sometimes conspicuously, in colour, — 
the males being always more beautiful than the females,, 
though the latter are likewise beautiful. All the 
species of kingfisher build in holes, and with most of 
the species the sexes are equally brilliant, and thus far 
Mr. Wallace’s rule holds good ; but in some of the 
Australian species the colours of the females are rather 
less vivid than those of the male; and in one splen- 
didly-coloured species, the sexes differ so much that 
they were at first thought to be specifically distinct.^^ 
Mr. E. B. Sharpe, who has especially studied this 
group, has shewn me some American species (Ceryle). 
in which the breast of the male is belted with 
black. Again, in Carcineutes, the difference between 
the sexes is conspicuous: in the male the upper sur- 
face is dull-blue banded with black, the lower surface 
being partly fawn-coloured, and there is much red 
about the head ; in the female the upper surface is 
reddish-brown banded with black, and the lower surface 
white with black markings. It is an interesting fact, 
as shewing how the same peculiar style of sexual 
See his ‘ Monograph of the Trogonidse,’ first edition. 
Namely Cyanalcyon. Gould’s ‘Handbook of the Birds of Aus- 
tralia,’ vol. i. p. 133; see, also, p. 130, 136. 
