Swallows

Bill very short, much depressed and very broad at the base, compressed toward the tip; upper mandible with the dorsal line convex, the edges overlapping, with a small notch close to the slightly decurved tip. Head broad, depressed; neck very short, body moderate. Feet very short, tarsus very short, anteriorly scutellate; toes of moderate size; first large, all scutellate in their whole length; claws rather strong, compressed, well curved, acute. Plumage soft, blended, glossy. No bristles at the base of the bill. Wings extremely long, narrow, pointed, somewhat falciform; secondaries very short. Tail generally emarginate, of twelve feathers. Mouth extremely wide; oesophagus rather wide, without crop; stomach elliptical or roundish, muscular, with a dense rugous epithelium; coeca very small. Four pairs of inferior laryngeal muscles. Nest in holes in banks, buildings, or trees, or attached to the surface of these objects. Eggs from four to six, white, plain, or spotted.