Family XIII. MOTACILLINAE. WAGTAILS.

Bill of moderate length, straight, slender, a little broader than high at the base, compressed toward the end; upper mandible with the dorsal line sloping, a little convex toward the end, the nostrils slight, the tip acute; lower mandible with the angle rather long and narrow, the dorsal line ascending and scarcely convex, the edges somewhat involute, the tip acute. General form slender; head ovato-oblong; neck short. Feet of ordinary length, slender; toes very slender, the lateral equal, the outer adherent at the base, the hind toe rather large; claws rather long, arched, compressed, acute, that of the hind toe generally very long. Plumage soft and blended. Bristles small. Wings long and pointed, one of the minor secondaries often much elongated and tapering. Tongue sagittate, slender, with the tip slit; oesophagus uniform; stomach a very muscular gizzard, roundish, with large tendons, and thin rugous epithelium, intestine of moderate length; coeca very small. Trachea simple, with four pairs of inferior laryngeal muscles.

This family is connected with the Turdinae by Seiurus, and with the Alaudinae by Anthus, which are the only two American genera.