THE SKUA GULLS AND THEIR RECENT MIGRATION. 95 
terms, such as “Arctic Skua,” &c., having been applied to 
several species. 
Several examples have also been recorded of the capture of 
the Long-tailed or Buffon’s Skua, the species to which Linneus 
gave the name of Larus parasiticus ; and as Stercorarius parasiticus 
it ought be known, although unfortunately that name has some- 
times beer erroneously applied to the preceding species. Linneus 
gave an unusually precise and accurate description, calling the 
central tail-feathers “longissimis,” and stating that the shafts of 
the two outer primaries are white—the inference being that the 
shafts of the other primaries are not white. Now, this is just the 
feature which serves to distinguish the two species in all ages, 
whilst there are other points which prevent any mistake in the 
adults. It is true that the young of Buffon’s Skua is rather 
smaller, and, so far as one can judge from the few specimens 
available, it is of an uniformly smoky colour, mottled with 
greyish, but without any of that brown shade so frequent in 
Richardson's ; the central tail-feathers also project more than in 
Richardson’s of the same age. These distinctions are, however, 
not always so strongly marked as could be wished; but a 
reference to the primaries will decide the question. In the 
Buffon’s Skua the shafts of the two outer primaries are white, 
those of the remaining primaries being dusky ; whilst in Richard- 
son’s Skua the shafts of all the primaries are white throughout 
the greater part of their extent; and even in young birds it is 
only towards the tips that the shafts are of a shade at all 
approaching that of the webs. In the young of all three species 
the feet are variegated, being of a livid or clay colour posteriorly, 
and blackish towards the nails, becoming black at maturity; so 
that these marks are no specific distinction. In the adult 
Buffon’s Skua the central rectrices project about eight inches 
beyond the others, whilst in Richardson's they seldom exceed the 
lateral feathers by more than three inches. 
Buffon’s Skua occurs throughout the whole of the Arctic 
Region, and has been found breeding on the fells of Lapland, on 
Novaya Zemlya, and in portions of Siberia; but its autumnal 
and winter range is somewhat difficult to trace with precision, 
owing to the confusion which exists with regard to this and the 
preceding species. I do not at present feel any certainty respecting 
the correctness of its identification beyond the Straits of Gibraltar, 
