LARIDAE 



301 



pointed, while comparatively slender ; in the Wiynchopinae, the 

 maxilla, which moves vertically with ease, is much shorter than 

 the mandible, and both are compressed anteriorly until they 

 resemble truncated knife blades. The tibia is generally partly 

 bare ; the metatarsus is fairly long in the first two Sub-families, 

 and is scutellated in front, being usually smooth behind, though 

 rougher in PagopJiila ; the anterior toes are fully webbed, with 

 claws which vary from weak to moderate, or even to strong and 

 hooked, as in the Stercorariinae. The elevated hallux is joined 

 by a membrane to the inner toe in Leuaophaeus, and is rudimen- 

 tary or absent in Rissa. In the Sterninae and Ehynchopinae the 

 metatarsus is short — especially in the latter, where the web 

 between the inner and middle digits is deeply incised, as are both 

 webs in Hyclrochelidon and Gygis ; the claws are long, slender, and 

 curved. The pointed wings, excessively lengthened in the two last- 

 mentioned Sub-families, have eleven primaries, of which the outer is 

 particularly small, and from fifteen to twenty-three secondaries. 

 The tail may be nearly even as in Larus, deeply forked as in Sterna 

 generally, less excised as in Xenia, Hydroclielidon, Naenia, and 

 Ehyricliops, graduated or cuneate as in Elwdostethia, Anous, and 

 Gygis ' all the twelve feathers being rounded or acute : in the 

 Stercorariinae the two central rectrices project beyond the others, 

 being decidedly pointed in Stercorarius crepidatus and S. para- 

 siticus, but rounded and twisted in the shaft until the webs are 

 vertical in S. pomatorhinus. The furcula is U-shaped, the syrinx 

 tracheo-bronchial, the tongue lanceolate, the nostrils are pervious ; 

 an after-shaft is present, while both adults and young have abund- 

 ant down, that of the latter commonly shewing a mixture of white, 

 with grey, yellowish, slaty, or brown. Naenia has elongated plumes 

 at the gape, and a few Terns have slight nuchal crests. 



Gulls and Skuas are widely-ranging and essentially marine 

 birds, even those species which nest inland being commonly 

 observed near salt water, and seeking the coast when incubation 

 is over. They are always inclined to be gregarious, and are more 

 or less resident in Britain, but the undoubted influx of birds from 

 abroad in autumn makes it difficult, or even impossible, to deter- 

 mine their exact status in every case. Their untiring and easy 

 flight is only second to that of the larger Petrels ; the majestic style 

 of the Great Black-backed Gull, and other forms, being a great con- 

 trast to the wavering but graceful movements of the Kittiwake or 



