Probably numbers perished of cold and hunger. As Swallows live entirely on insects, the diminution in their numbers is a serious matter. It is sometimes necessary, in order to preserve the proper order of things, to describe what every one knows. The most striking characteristics of the Swallow, which distinguish it from its congeners are as follows: Brow and throat a beautiful chestnut brown; breast, back, wings, and tail a fine black with a bluish metallic lustre. With regard to the tail however, only the two middle feathers are pure black, on the others small whitish specks are discernible. The outer tail-feathers form a long pronged fork. The underparts are sometimes white, sometimes brownish. The beak is very small, the gape wide. The open jaw forms a kind of little pocket. The legs are small with sharp claws suitable for grasping. THE HOUSE MARTIN. (_Chelidon urbica._) While the Chimney Swallow builds inside houses, under some circumstances even in the fire-place--thus becoming a beloved member of the family,--the House Martin constructs its strong and comparatively large nest on the outside of the building. In mountainous districts it is found also in an overhanging position on the steep rocks, where it is sheltered from the rain. In many villages, where windows and doors of the upper floor are kept shut, so that the Chimney Swallow cannot come in, the latter is not found, and the House Martin then takes its place. This Swallow also lives entirely upon flying insects. It spends most of its time on the wing otherwise it could not live. It has, consequently, small, weak legs, which are only useful for clinging. It is as useful as its relative but has less confidence in man; it is less familiar. Neither does it please our ears with such a pretty twittering, and its enclosed, remote nest, affords us no insight to its family life. It arrives later in the spring than the Swallow, and assembles in the autumn in flocks, on towers, trees, roofs of houses and churches. One fine day we find they are all up and away--for the distant South. This bird deserves every care and protection. * * * * * I had been watching with interest the building of some nests of the House Martin one season, and enjoying the sight of the pretty creatures as they circled about a house I was staying in for a time, and the way they [Illustration: USEFUL. THE HOUSE MARTIN.]