Smallest of the British Divers, the present species, the _Colymbus septentrionalis_ of Linnæus and modern authorities, is also the best known and the most widely distributed. It is also the least showy in nuptial dress. In this plumage the throat is marked with an elongated patch of chestnut; the head, and sides of the neck are ash-brown, the latter striped with black and white, the general colour of the upper plumage blackish-brown, sparingly spotted with white, and the under parts are white. The plumage, as in all the Divers, is remarkably dense and compact, adapted in every way to the aquatic habits of the bird. The Red-throated Diver is a fairly frequent visitor, during autumn and winter, off the English coasts, often entering bays and the mouths of wide rivers. In summer, however, it becomes much more local, retiring then to haunts in Scotland, especially in the Hebrides and along the wild and little populated western districts, from the Clyde northwards to the Shetlands. Outside our limits, this Diver has a very wide distribution, occupying in summer the Arctic and north temperate regions of Europe, Asia, and America; in winter migrating southwards for a thousand miles or more. The Red-throated Diver is certainly the most gregarious species, and in winter may not unfrequently be seen in gatherings of varying size. In connection with this trait, mention may be made of the extraordinary numbers of this bird that, on the 2nd and 3rd of December 1879, passed Heligoland. The movement was not strictly a migratory one, but a grand flight of storm-driven, frozen-out birds, seeking more congenial haunts. Gätke tells us that during this visitation, there was about thirteen degrees of frost, an easterly wind, and a snowstorm in the evening. The Divers were by no means alone in their distress, for hundreds of thousands of Ducks, Geese, and Swans, Curlews, Dunlins, and Oyster-catchers, passed from east to west. From early morning until noon, on both days in succession, the Divers were seen in one incessant stream, travelling north-east, in numbers estimated almost by the million! Well may Gätke have wondered whence such vast multitudes came, and whither they were going, and what was the initial cause of such gregarious instincts, never manifested in this Diver under any ordinary circumstances.