v LARIDAE 301 
pointed, while comparatively slender; in the Rhynchopinae, 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 seutellated in front, being usually smooth behind, though 
rougher in Pagophila ; 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 Lewcophaeus, and is rudimen- 
tary or absent in Rissa. In the Sterninae and Rhynchopinae the 
metatarsus 1s short — especially in the latter, where the web 
between the inner and middle digits is deeply incised, as are both 
webs in Hydrochelidon 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 Nema, Hydrochelidon, Naenia, and 
Rhynchops, graduated or cuneate as in Lhodostethia, Anous, and 
Gygis; all the twelve feathers being rounded or acute: in the 
Stercorartvinae 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. Maenia has elongated plunes 
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 
