io6 A MONOGRAPH OF THE PHEASANTS 



and under tail-coverts are heavily glossed with blue, and the former show slight traces 

 of the white freckling. The mid-ventral plumage is mostly dull blackish. 



Irides hazel-brown ; facial skin vermilion ; nape wattle is sometimes fairly well 

 developed, and in a breeding male the facial shield of skin stands up ridge-like above 

 the crown feathers ; mandibles pale horn, blackish toward base ; legs and feet bluish 

 grey. The single pair of spurs are long, stout and curved, and average 25 mm. in 

 length. Measurements are, bill from nostril, 17; wing, 245; tail, 162; tarsus, 79; 

 middle toe and claw, 51 mm. 



VARIATIONS OF PLUMAGE 



Adult Male. — About fifty per cent, of adult erythrophthalnms males have the 

 shafts of the ventral plumage, especially on the breast, conspicuously white, thus 

 approximating the very specialized corresponding feathers of the '^oxnt2Si pyronohis. 



As regards the status of Acomus inornahis. In 1879 Salvadori described a bird 

 from Mount Singalan, on the west coast of Sumatra, as a new species of Crestless 

 Fireback. Since then a second similar specimen has been obtained. Both are said 

 on good evidence to be males, and yet curiously enough are almost identical in colour 

 with the females of the two other species of Acomus, the chief point of distinction 

 being the scaly appearance of the dorsal surface, owing to the steel-blue colour being 

 confined chiefly to the distal fringe of the feathers. 



Upon examination of many scores of specimens of erythrophfhahnus collected by 

 myself and in various museums, I find so much variation to exist that I cannot bring 

 myself to accept inornatus even as a sub-species. Both Johore and Sumatran specimens 

 show all gradations between complete gloss and a narrow terminal fringe, and as to 

 the freckling and iridescent back and rump I have two black-tailed males trapped in 

 the same line of nooses in north Johore with four perfectly normal males, which show 

 only the barest trace of white, while the dorsal colour is absent from one and extremely 

 imperfect in the other. In fact, when skinning the first I sexed the bird merely as 

 a matter of habit and was most surprised to find that the individual was a male, with 

 full-developed generative organs, and yet in the plumage of a female. I can offer as 

 explanation only that this most interesting phenomenon is doubtless correlated with 

 the very unusual approximation of colour in the sexes of this genus, a character so 

 unlike their nearest relatives — the crested firebacks {Lophurd). The close association 

 of the two phases, and their occurrence in both the Malay Peninsula and Sumatra 

 would seem to indicate that its occurrence is no more than a variation such as the 

 so-called Lophophorus chambanus in a wild state, or Chrysolophus obscurus or Pavo 

 nigripennis in captive birds. 



Adult Female. — Forehead, crown and occiput dark brown, chin, throat and 

 ear-coverts paler, smoky grey. Upper plumage black, strongly glossed with steel-blue 

 on the exposed portions of the feathers. The gloss dies out on the secondaries and 

 tail-feathers, which are black, the primaries being brown. The under-parts show very 

 little gloss, this being confined to the breast, sides and under tail-coverts, the remainder 

 being dull, brownish black. Many females show a small round white spot or mottled 

 patch on the feathers of the crown and side of the nape. Correlated with the other 



