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; œsophagus
rather wide, without crop; stomach elliptical or roundish, muscular,
with a dense rugous epithelium; cœca 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.
GENUS I. HIRUNDO, Linn. SWALLOW.
Characters as above; tail emarginate or forked.