Winter 
plumage. 
Young. 
512 NATATORES. CATARACTES. 
broad bar and the extreme tip white; the rest having 
only triangular white tips. Secondaries and tertials 
with white ends. In winter the head and neck are 
streaked with grey or pale broccoli-brown ; the rest of 
the plumage remaining as in summer. 
The young have been mentioned above ; but may be known 
from those of L. marinus and L. argentatus, by the 
shorter bill, and the less livid hue of their feet and legs. 
Genus CATARACTES, Ray. SKUA. 
GENERIO CHARACTERS. 
Bitt of mean length, strong, thick, compressed at the 
point ; having the base of the upper mandible covered as far 
as the horny tip, with a cere; culmen rounded: Dertrum 
hard, convex, and hooked. Under mandible forming a sa- 
lient angle from the symphasis, and fitting into the upper 
one. ‘Tomia bending slightly inwards, sharp, and cutting. 
Nostrils lateral, placed immediately behind the dertrum, im 
the front of the cere, or soft corneous part of the bill, diago- 
nal, narrow, anteriorly widest, and pervious. 
Wings elongate, with the first quill-feather exceeding the 
others in length. Tail rounded, with the intermediate fea- 
thers more or less produced. 
Legs having the lower part of the tibiae naked, covered in 
the back part with rough scales. Feet of four toes, three 
before and one behind. ‘The front toes webbed; the hind 
toe very small, and articulated nearly on the same place with 
the front ones. Nails falcated, and sharp; the inner’ one 
being the strongest and most hooked. 
By many of the earlier systematists, the Skuas were in- 
cluded in the Gulls, but as essential characteristics (not pos- 
