ROOK. 303 



others. Mr. Hancock figures such a specimen, in which' 

 " the whole of the plumage is hlack, each feather having a 

 greyish bar close to the extremity; on the under parts of 

 the body the bars are narrow, but on the upper parts they 

 are wide and very conspicuous ; the quills are likewise found 

 marked in the same manner, and the tail feathers show 

 slight indications of similar bars. The marking is quite 

 symmetrical, and suggests the appearance of the spotting 

 of the first or nest plumage so general in the PasseresJ" 

 This gentleman says he has seen two more specimens of this 

 interesting variety, and others are known to the Editor. 

 They are all nestlings, and the bird mentioned by Hunt, 

 being kept in confinement, lost all its mottled feathers at 

 its first moult and assumed the ordinary black plumage. 

 The hint thrown out by Mr. Hancock seems to supply an 

 explanation of this aberration, which may perhaps be regarded 

 as an example of what many naturalists term "Keversion" — 

 that is, a tendency occasionally exhibited in a species to 

 return to what was in all likelihood the appearance of a 

 remote ancestor. 



Malformations of the beak are by no means uncommon 

 among birds, and in the present species a monstrous growth 

 of the horny covering (as figured on the next page) has been 

 frequently noticed, the more so since it has been supposed 

 to bear on a question for a long time discussed and not yet 

 entirely set at rest. 



This question is whether the nudity of the adult Rook's 

 face is produced by the abrasion of the feathers through the 

 constant act of digging in the ground for food, or whether it 

 arises as a natural peculiarity. Waterton, Mr. Blackwall, 

 Mr. Knox and others have made a few trials, which from 

 their inconclusive nature are hardly to be termed experi- 

 ments, of keeping young Rooks in confinement to find whether, 

 when the birds have no opportunity of digging, the feathers 

 at the base of the beak will yet fall off. This it seems they 

 will do, but not always, and all that appears to have been 

 proved is that captivity in some cases retards this external 

 sign of maturity as it retards many others in many other 



VOL. II. K li 



