never remove far from the locality whence they started. The disagreeable shrieking cry uttered by these birds varies but little in different species. Although the Terns are very sociable in their intercourse with their own kind, they appear to take but little heed of the rest of their feathered companions, even when, as is often the case, they associate with them in search of food. The diet of the Sea Swallows consists principally of fishes and a variety of creatures met with in the sea, their prey being always taken when on the wing. These birds are strictly monogamous: a few weeks before the commencement of the breeding season they begin to assemble in the vicinity of their meeting-place, returning year after year to the same locality. Such species as inhabit the sea-shore generally select coral-banks, islands, or long spits of bare sand for this purpose, while such as settle inland seek out similar, but less barren spots, in the vicinity of swamps and marshes, the various species usually breeding apart from each other. Such as resort to morasses lay their eggs in a mere depression of the ground. Their unpretending apologies for a nest are sometimes isolated, sometimes so crowded together as literally to cover the ground so thickly, that the brooding birds have all to sit with their heads in one direction, and a man cannot pass between them without crushing the eggs of contiguous nests. Even such species as resort to trees construct nothing in the shape of a nest, but deposit their eggs in chinks of the bark or inequalities of the branches. Most of the Terns lay three eggs, others two, whilst those that breed on trees deposit but one. The male and female brood alternately; during the heat of the day, however, they leave their eggs to be kept warm by the sun. The young are hatched in about a fortnight or three weeks, and make their appearance clad in down; they leave the hollow that has served as a nest on the day of their birth, and run at once down to the water's edge, quite as fast as their parents, by whom they are anxiously and carefully tended. [Illustration: _Plate 38, Cassell's Book of Birds_ STERNA HIRUNDO ____ COMMON TERN (_about 1/3 Nat. size_)] [Illustration: THE CASPIAN TERN (_Sylochelidon Caspia_).] * * * * * The RAPACIOUS TERNS (_Sylochelidon_) are the largest of the Sea Swallows, and distinguishable from other species by their proportionately strong, compressed body, as also by their large strong beak, which is longer than the head. The foot is small, and the web but little excised; their wing is long and sabre-like; the tail but slightly forked; and the general plumage close and thick. THE CASPIAN TERN.