58 A NATURALIST IN BORNEO 



term. The plumage is black, except for a red 

 ruff round the neck ; the sexes are similar. The 

 fully fledged young birds differ from the adults in 

 having the crown of the head covered with red 

 feathers like those round the neck, but after the 

 first year these are shed and replaced by the scurfy 

 scales. 



Bald-headedness in birds is uncommon and most 

 difficult to explain. The naked head and neck of the 

 Vulture are adaptations to a scavenger's life ; we may 

 even stretch a point and similarly account for the 

 bald cranium of the Adjutant Bird, though one might 

 have supposed that the long beak would keep the 

 head out of reach of the sullying offal on which this 

 bird feeds. But why should the insectivorous or 

 frugivorous Pityriasis and Allocotops calvus, one of 

 the Mountain-Babblers of Borneo, be bald ? The 

 latter species has no feathers, not even scurf on the 

 top of its head ; the bare skin is dull yellow in colour 

 and the female is as bald as the male. Sexual adorn- 

 ment, though it would be strange to apply the term 

 adornment to baldness and scurfiness, evidently cannot 

 be invoked, and the phenomenon remains a mystery. 

 The hypothesis that baldness in these birds is now 

 a normal condition, originally derived from a 

 pathological condition, is so wildly fascinating that 

 it must be repulsed as one of the wiles of the Evil 

 One. 



The exact systematic position of Pityriasis amongst 

 the Passeres is very uncertain. Some ornithologists 

 have regarded it as a sort of Shrike, others, as related 

 to the Starlings, whilst I always thought that it had a 

 very Crow-like appearance. Mr. Pycraft, however, our 



