ROOK. 101 



two or three other birds (not British) are now known to 

 exhibit this peculiarity, which has been considered specific. 



White, pied, and cream-coloured varieties of the Rook 

 sometimes occur. Mr. Plunt, of Norwich, says, " A gen- 

 tleman of his acquaintance had in 1816 a young Rook of a 

 light ash-colour, most beautifully mottled all over with 

 black, and the quill and tail-feathers elegantly barred. 

 This curiosity he was naturally anxious to keep; when 

 upon the bird moulting, all its mottled plumage vanished 

 entirely, it became a jet black Rook, and in this state 

 was suffered to join its sable tribe, as a fit companion, in 

 the fields." This agrees with my own observations. Acci- 

 dental varieties will generally be found to be smaller and 

 weaker birds than those which are truly characteristic of 

 the species. As these young birds increase in age, and 

 gain constitutional power, the secretions become perfect, 

 and the plumage assumes its natural colours. The as- 

 sumption of white feathers by old birds is probably the 

 effect of the converse operation of this physiological law. 



Malformations of the beak are by no means uncommon 

 among the species of the genus Corvus, particularly in the 

 Rook, and some remarks by John Blackwall, Esq., in his 

 Researches in Zoology, refer to a question not yet entirely 

 set at rest. 



" A Rook preserved in the Manchester Museum, has its 

 mandibles crossed near their extremities, but so slightly, as 

 not to have interfered materially with the mode of pro- 

 curing food usually employed by that species, as is clearly 

 evinced by the denuded state of the nostrils and the ante- 

 rior part of the head, both of which are entirely destitute 

 of feathers. Another specimen, in the possession of Mr. 

 R. Wood, a zealous collector of objects in natural history, 

 residing in Manchester, has the mandibles greatly elon- 



