GULLS AND ALLIED SPECIES. 471 



young, at first clothed with close variegated down, very soon 

 walk, and readily take to the water, but, if not disturbed, 

 generally remain about the nest until they are able to fly. 



SYNOPSIS OF TEE BRITISH GENERA AND SPECIES. 



GENUS I. LESTRIS. SKUA. 



Bill shorter than the head, nearly as broad as high at the 

 base, compressed toward the end, with the tip decurved ; 

 upper mandible cerate, with the ridge broad, the nostrils 

 linear-oblong ; lower mandible with the crura broad and 

 erect, the angle little prominent, the tip compressed. Feet 

 of moderate length, rather stout ; tarsus moderately com- 

 pressed, with anterior decurved scutella, the posterior scales 

 convex and prominent; claws much curved, acute. Wings 

 very long, pointed ; tail of moderate length, of twelve feathers, 

 of which the two medial are more or less elongated. 



1. Lestris Catarractes. Co7nmon Skua. Bill two inches 

 and a quarter in length ; tarsus two inches and a half ; 

 middle tail-feathers scarcely an inch longer than the rest. 

 Bill and feet black ; upper parts dark greyish-brown, streaked 

 with brownish-yellow. 



2. Lestris Pomarinus. Poinaritie Skua. Bill an inch 

 and three-fourths in length; tarsus two inches, very rough 

 behind with pointed scales ; middle tail-feathers about two 

 inches longer than the rest. Bill greenish-grey ; feet black ; 

 upper parts blackish-brown ; throat and lower parts white. 



3. Lestris Michardsonii. Richardson'' s Skua. Bill an 

 inch and a third in length ; tarsus an inch and two-thirds ; 

 middle tail-feathers three inches longer than the rest, taper- 

 ing moderately until near the end, when they rapidly narrow 

 to a fine point ; feet black. 



4. Lestris parasitica. Parasitic Skua. Bill an inch and 

 a twelfth in length; tarsus an inch and a half; middle tail- 

 feathers six or more inches longer than the rest, tapering to 

 a fine point. 



