VOL. vii.] PLUMAGES OF THE ROOK. 129 



In the moult from juvenile- to first winter-plumage, 

 which takes place in July and August, the head moults 

 last, and all the feathers in the regions which afterwards 

 become bare are renewed in a normal manner. The 

 old feathers are cast very rapidly, so that almost all the 

 new feathers in these regions are in sheath together 

 (Plate 4, Fig. 2) and are afforded practically no pro- 

 tection by the old feathers. If damage were done at 

 any time to the feathers by the bird digging in the 

 ground with its bill, as has often been suggested, surely 

 it would be at this stage, when the feathers are just 

 breaking from the sheath, that they would be most 

 prone to injury. Yet when full grown the new feathers 

 are perfect and show no sign whatever of abrasion. 



I have examined microscopically feathers taken from 

 the chin twenty-two millimetres from the angle of the 

 lower mandibles^ of Rooks in juvenile- and first winter- 

 plumage and can find no essential difference in their 

 structure, though the juvenile-feathers are of a looser 

 texture, their rami and radii being further apart than in 

 the first winter-feathers (Plate 6). But the feathers of this 

 region of the chin and throat which afterwards becomes 

 bare, are even in the first winter of a somewhat degenerate 

 character : the rhachis projects beyond the rest of the 

 feather and is almost bare at its distal end ; the distal 

 rami are the same : the rami are far apart, and the radii 

 are also far apart and comparatively long and straggly, 

 not interlocked. The peculiar structure of these feathers, 

 which is markedly different from that of feathers lower 

 down on the throat (Plate 7), may have some significance 

 in relation to the bare patch, but it must be remarked that 

 aU other members of the Corvidse which I have examined 

 have feathers of similar structure in this region, even 

 in aduH -plmnage. Another circumstance which may 

 be significant is that some of the feathers on the chin, 

 generally those nearest the angle of the lower mandibles, 



* This being the centre of the region which afterwards beconies bare. 



