DARWIN'S KOKLASS PHEASANT 43 



rather linear in its extent in a few individuals, though so faint and broken that one never 

 thinks of it as aught but indefinite mottling. In darwini we have a crystallizing of this 

 mottling, and in well-marked males we find, especially on the mantle, /^^r very distinct 

 longitudinal black lines on a more or less clear grey background. On almost all the 

 dorsal plumage this advance step in pattern complexity is evident, and clearly sets apart 

 the birds as a distinct species. A glance at darwini shows the dorsal plumage to be 

 doubly complex over that of xanthospila, just as the latter in turn doubles that of 

 macrolopha. 



The upper tail-coverts are much as in xanthospila, but as for the lateral rectrices, 

 while the black border around the central grey has increased, the oblique cross-bar has 

 disappeared, leaving either a faint spot, a short shaft line or no trace at all. The black 

 on the under tail-coverts has usurped almost all the basal part of the feathers, while the 

 white terminal portion has also increased. The chestnut is reduced to a small lateral 

 spot on each web. 



On the ventral surface we find a most interesting condition of affairs. We see 

 represented the phenomenon of correlated concentration and diffusion. The chestnut 

 mid-zone is in all conditions and states of degeneration, and even where most abundant 

 and pure, the entire under plumage is tinged strongly with the buff which hints of the 

 dissolving of the chestnut. There is no trace of white or even grey, except on the sides 

 of the upper breast. This variation in the chestnut of the lower plumage is individual 

 and wholly independent of age. 



In the most strongly marked birds the chestnut zone would be called merely a 

 broad line, while we often find an individual with only faint traces on a few feathers, or 

 with the line irregularly broken through below the breast. 



The extreme is seen in a fully adult individual, typically darwini in every other 

 way, in which the chestnut is wholly absent on the fore neck, breast and belly. 



Iris dark hazel ; mandibles black ; legs and feet blackish grey. Bill from nostril, 

 16 mm. ; length, 600; wing, 234; tail, 236; tarsus, 72 ; middle toe and claw, 61 ; spur, 

 about 15. 



Adult Female. — The variation among the females is very considerable, relatively 

 fully as great, although within much more narrow limits than in the males. We find 

 birds which are warmly suffused with rich rufous over the entire under surface, and 

 again through a series of gradations we pass to specimens which might well represent 

 the colour mates of the extreme styani type, of a colder buff below than any other 

 specimen of xaiithospila or macrolopha. 



The two lateral lines of black throat markings appear on the whole to be denser and 

 of greater extent than in any other female Pucrasia, but it is on the lateral rectrices that 

 the single important diagnostic character is to be found. As in the male, the distinction 

 from xanthospila lies in the absence of the oblique black cross-bar, the grey area being 

 entire except for the shaft-spot or short streak which is all that remains of the bar of 

 xanthospila. 



Bill blackish brown; iris hazel ; legs and feet leaden grey. Bill from nostril, 16; 

 length, 490; wing, 200; tail, 155; tarsus, 66 \ middle toe and claw, 56. Spur usually 

 a flat scale, occasionally a diminutive spur 3 mm. or more in length. 



