Cuckoos

Bill long or of moderate length, broader than high at the base, compressed toward the end, straight or somewhat arched; upper mandible with the dorsal line convex or arched, the ridge indistinct, the sides convex, the edges arched, sharp, without notch, the tip decurved; lower mandible with the angle rather short, the dorsal line straight or decurved, the ridge thin, the sides erect or convex, the tip slightly decurved, acute. Nostrils basal, oblong, generally marginate. Head of moderate size; neck of ordinary length; body rather slender. Feet of moderate length; tarsus with broad scutella; toes long, slender, flat beneath, outer directed outwards or backwards. Claws long or of moderate length, arched, compressed, acute. Plumage blended; wings generally long, with the first quill short, the third and fourth longest. Tail long, of ten feathers; upper mandible very narrow beneath, with three longitudinal ridges; tongue slender, emarginate, and papillate at the base, the tip horny, thin, lacerated, and slit; oesophagus rather wide, without dilatation; stomach large, round, with the muscular coat very thin, the epithelium soft, rugous; intestine of moderate length and width; coeca long, oblong, narrowed at the base. Trachea simple, with a single very slender pair of inferior laryngeal muscles.