The great northern diver, or loon, is called great because he exceeds the other divers in size; in this sense he is also great in relation to birds generally, since he is as big as a goose, and therefore the equal of the few species that are greatest. In form he differs widely from the geese. An oceanic bird that escapes from its enemies by diving, and is never seen on the wing except when migrating, and never on land except when breeding, his form has been modified so as to make swimming and diving as easy to him as careering through the air is to the swift, and climbing on trees to the woodpecker. The beak is straight, conical, and sharp-pointed; the head, neck, and body, grebe-like in form; and the legs set so far back that the bird is almost incapable of progression on land. It is very wonderful that a creature that spends so great a part of its time on and in the water, without leaving it, should yet retain wing-power sufficient to perform long bi-annual migrations. Probably it does not take very extended flights; when found on inland waters during migration, it often appears incapable of flight, and if in a small stream is easily taken. In its flying powers it appears, with the grebes and auks, to occupy a position midway between the ever-soaring, aërial gannet and the penguins, that are incapable of flight. In their dark rich, variegated upper, and white under, plumage, the divers again resemble the grebes. The glossy black back, thickly strewn with symmetrical white spots, gives the present species a beautiful and somewhat singular appearance. Out at sea it is a silent bird--silent and shy and solitary--with the cormorant-like habit of making itself invisible by sinking its body beneath the water. In the breeding season it utters cries of a very strange character, powerful and uncanny in their effect on the mind, and compared by different listeners to screams uttered by tortured children, and to shrieks of insane laughter. It is a winter visitor to the British Islands, chiefly to the west coasts of Scotland and England: but as it has occasionally been met with in summer in full nuptial plumage, it is thought by some ornithologists that a few pairs may remain to breed in some of the secluded lakes in the west of Scotland, the Outer Hebrides, the Orkneys, and Shetlands. It has not yet been found breeding anywhere in continental Europe; its known breeding-grounds are in Iceland, and in America, from Greenland to Alaska. It breeds in secluded lakes and tarns, at no great distance from the sea, and prefers an island to nest on; but where no island exists the nest is placed on the shore close to the water. Two eggs are laid, varying in ground-colour from olive-brown to russet-brown, spotted somewhat thinly with black. * * * * *