162 ON THE NUDITY OF THE ANTERIOR 
where it might have an opportunity of employing the 
means of procuring sustenance common to the species, 
and to let the other remain in the pen. This plan 
was frustrated by the unexpected death of one of the 
young birds soon after it came into my possession ; 
but the result of the experiment, as will be seen in 
the sequel, was not at all affected by this untoward 
circumstance. In the month of August the surviving 
Rook lost only a few feathers from various parts of its 
body, but did not moult regularly till July and Au- 
gust, 1$414, when the feathers at the base of the bill 
and on the anterior region of the head were cast off, 
and were not renewed, though the bird was remark- 
ably healthy and was never, on any occasion, suffered 
to leave the pen fora moment. On the 20th of June, 
1846, an unfortunate accident terminated its exis- 
tence. It lived long enough, however, thoroughly to 
establish the fact, that after the feathers are once 
shed from those parts in the act of moulting they are 
not renewed, as the denudation became rather more 
extensive and complete after the bird had moulted a 
second time in the summer of 1845, and continued 
unchanged to the day of its death, affording a con- 
vincing proof that this conspicuous feature in the 
adult Rook, which strikingly affects its physiogno- 
mical expression, must be regarded as a specific 
character. 
That Rooks in a state of liberty usually moult in 
the autumn of the year in which they are disengaged 
