Chap, XV. COLOUR AND NIDIFICATIOX. 173 



the females. This is a si2:niiicant 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, — 

 tbe males beino; alwavs 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. K. 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-blae 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 markin2:s. It is an interestins: fact, 

 as shewing how the same peculiar style of sexual 



"> See his ' Monograph of the Trogonidse,' first edition. 

 21 Namely Cyanalcyou. Gould's • Handbook of the Bhds of Aus- 

 tralia,' vol. i. p. 133; see, also, p. 130, 13G. 



