512 NATATORES. CATABACTES. 



broad bar and the extreme tip white ; the rest having 

 only triangular white tips. Secondaries and tertials 



Winter with white ends. In winter the head and neck are 



streaked with grey or pale broccoli-brown ; the rest of 

 the plumage remaining a in summer. 



Young. 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. 



GENERIC CHARACTERS. 



BILL 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, in 

 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- 



