138 
BIRDS. PALMIPIDES. 
Cataractes* 
those which we have examined. It does not appear to be subject to much 
variation of plumage with age or seasons. Some individuals have been found 
having the chin and forehead tinged with ash-colour. — The common Skua is 
gregarious during the breeding season. It lays two eggs of a muddy green 
colour, marked with irregular brown spots, and intermixed with smaller white 
spots. — The nest is carelessly constructed of a few dried weeds, and is found 
in unfrequented moors. It breeds in the Zetland islands, where I have ob- 
served it, as in Foulah and Unst, and on Ilona’s Hill in Mainland. When 
the purposes of incubation have been accomplished, it retires from its sum- 
mer haunts, and leads a solitary life on the ocean. It is found in our seas at 
all seasons. It is rare in the southern parts of the kingdom ; and even about 
the Zetland islands it is by no means a common bird. 
222. C. parasiticus. Arctic Skua. — Plumage above black ; 
the two middle tail-feathers produced. 
Larus par., TAnn. Syst. i. 226. Penn. Brit. Zool. ii. 533 — Lestris par., 
Temm. Orn. ii. 796 — Teazer, Dung-hunter, Dung-bird, Scull, Boat- 
swain ; 5*, Faskidar, Badock, Allan, Scouti-allan, Dirten-allan ; W, Shui. 
— Common on all parts of the coast. Breeds in the Hebrides and 
Northern Isles. 
Length 21, breadth 43 inches ; weight 16 ounces. The bill is 2 inches in 
length, of a gre 3 dsh-black colour, darkest towards the point. The upper man- 
dible is rounded along the margin towards the base, a little prominent in front 
of the nostrils above, and bent downwards at the end. The under mandible is 
bent inwards at the edges, and at the apex forms a groove sloping downwards ; 
at the base it is grooved laterallj’- ; and, at the junction of the two sides beneath, 
there is an angular prominence. The eyes are surrounded with a narrow black 
orbit, and the irides are of a hazel-brown colour. The legs are of a black co- 
lour, rather slender. The claw of the outer toe is short ; that of the middle- 
toe broad and grooved below ; and of the inner toe narrow and arched. The 
tongue is fleshy and bluntly bifid. The middle of the palate, and a ridge on 
each side, are covered with cartilaginous reflecting teeth. The trachea at the 
division of the bronchise is furnished with a small bony plate. Bectum with 
too long broad vermiform appendages. Crown, nape, back, quills, tail and its 
under covers, brownish-black, deepest on the head and extremities of the 
wings and tail. Front, chin, cheeks below the eye, side of the neck, and be- 
low white. An indistinct collar of wiry-feathers round the neck. The wings 
reach beyond the lateral feathers of the tail ; the first quill the longest. Tail 
of 12 feathers ; the five exterior ones rounded, the extremity of the shaft pro- 
jecting ; the two middle produced feathers taper to a point. Female similar. 
.—Nest in heath, of dry grass. Eggs 2, dark olive-green, with irregular 
blotches of liver brown. The young have the head and hind neck grey, with 
brown streaks ; the back dusky-brown, the feathers with pale edges ; below 
blackish-grey, with a ferruginous tinge ; the base and tips of the quill and 
tail-feathers whitish. In its young state, and as it approaches to maturity, it 
is the (Larus crepidatus) Cepphus of Lysoii, Phil. Trans, xlii. 137., and the 
Black Toed-Gull of Pennant, Brit. Zool. ii. 532 — The “ Arctic Bird” of Ed- 
wards, tab. 148., frequently referred to as belonging to this species, appears to 
be distinct, as indicated by the bright yellow colour of the legs. — Like the pre- 
ceding species, the Arctic Skua is subgregarious onl}'^ in the breeding season, 
and remarkably bold in defending its nest. It has recourse to stratagem to 
lead intruders from its eggs or young, tumbling over, as if dying, or feigning 
a broken wing. It is worthy of remark, that this species breeds before it at- 
tains the plumage of maturity. * 
Gen. CI. LARUS. Gull. — Bill hooked; tail even.— -The 
Females are similar, to the Males in plumage, but less in 
