_L. argentatus_, our Herring Gull, has a blue-grey mantle; the black primaries shew white tips and "mirrors" or round white marks, as well as a grey wedge on the inner web; the feet are flesh-coloured, {307}the orbits yellowish. In winter the head is streaked, and in the young the plumage is mottled with brown. This species extends over Northern Europe and most of North America, ranging to the south of those countries in the cold season; its representative in the Mediterranean and Central Asia is _L. cachinnans_, with yellow feet and red orbits, and in Arctic Siberia _L. vegae_, chiefly differing from the last-named in its pinkish legs. _L. audouini_ of the Western Mediterranean has blackish feet, and a crimson bill with black band. _L. canus_, the Common Gull, found throughout Northern Europe and Asia, and migrating to the Mediterranean, the Nile, the Persian Gulf, and China, has white mirrors on the first three primaries, yellow bill, and greenish-yellow feet. It has occurred in Labrador, and breeds in North Britain on islands, lakes, and flat stacks, though rarely, if ever, on cliff-faces; the shrill note is more like that of the Herring Gull than the harsh cry of our Black-backs. The smaller and darker _L. brachyrhynchus_ occupies North-Western America, reaching California in winter; the paler _L. delawarensis_, with a subterminal black band on the yellowish bill, frequents lakes and marshes in North America, and breeds towards the north; _L. californicus_, with little black on the beak, inhabits western North America. Of the Black-backed Gulls, _L. marinus_, the Great Black-back, largest of the Family except _L. glaucus_, is found from Arctic Europe to North-East America, migrating as far as the Mediterranean, the Canaries, and Florida; it has a grey wedge on the primaries like the Herring Gull, and pinkish feet. Somewhat scarce in Britain in summer and comparatively non-gregarious, it is noted for its fierceness, and will even attack sheep. The smaller _L. dominicanus_, with olive feet, ranges from lat. 10° S. in South America to South Africa and New Zealand, with the corresponding Antarctic Seas; _L. schistisagus_ of the North Pacific being intermediate between this and the next species. _L. fuscus_, the Lesser Black-back, found both on our shores and inland, has yellow feet; its main range covers North Europe, excluding Iceland; but it even breeds in Morocco and on the Red Sea, extending in winter still further southwards. The similar _L. affinis_ of North Russia and West Siberia, with coarser feet, migrates to Somaliland, India, and occasionally other districts; the very stout-billed _L. occidentalis_ represents our species on the Pacific coast of North America.