THE ARCTIC OR RICHARDSON’S SKUA. 
3G1 
not a bird which often thrives in conhnenient. By the time 
my little bird was a month old its cry precisely resembled 
that of the adult, though at first it was very different. 
There is no doubt that these unscrupulous birds feed on 
eggs occasionally. I have myself seen and handled eggs of 
the Common Gull from which the Shooi had just flown away. 
[I very much regret to be unable to throw any light from the 
MSS. on the still unsettled question as to the determining 
causes of the singular and very great variations in plumage so 
well known to occur in this species. There are casual allusions 
to white-breasted specimens, and also in one passage a pair is 
spoken of, the female of which was entirely brown, while the 
male was white underneath. Mention is likewise made of a 
specimen in which the carpal joint of the wing was very 
prettily mottled with white. Beyond this, nothing is said. 
In 1865 the author told me he had not been able to form any 
sort of theory upon the subject. Thomas Edmondston says 
C'Zool.” 1844, p. 466), ‘'This difference is apparent when the 
young birds are in the nest; and the parents may be both 
black, or both of the other kind, or one of the black and one 
of the white-bellied variety, and the young will be either two 
black, two white-bellied, or one of each indiscriminately. 
I have seen two black young birds in the nest of two white- 
bellied. I have shot, dissected, and domesticated many indi- 
viduals without obtaining any clue to this singular anomaly, 
the two varieties being precisely similar in every particular 
but that of colour.” This account would seem to make 
altogether against the belief entertained by some, that the 
variations are according to age. For black read blackish brown, 
from the context. — E d.] 
