Warblers

Bill of moderate length, slender, straight, a little broader than high at the base, compressed toward the end; upper mandible with its dorsal line straight and declinate, convex at the end, the tip small, acute, the notches small; lower mandible with the angle of moderate length and narrow, the dorsal line straight, the sides convex, the tip narrow. Nostrils basal, oval or oblong. Head rather large, ovate; neck short; body rather slender. Feet of ordinary length, slender; tarsus compressed, with seven anterior scutella; toes moderate, compressed; first stouter, second and fourth nearly equal, third much longer, and adherent at the base; claws moderate, arched, slender, compressed, acute. Plumage soft and blended. Bristles short or weak. Wings of moderate length or long; the first quill very small, the second, third, and fourth longest. Tail long or of moderate length, of twelve feathers. Tongue, sagittate, slender, tapering to a slit and lacerated point. OEsophagus rather narrow, without crop; proventriculus oblong; stomach a gizzard of moderate strength, with the muscles distinct, the epithelium dense and rugous; intestine of moderate length; coeca very small. Trachaea simple, with four pairs of inferior laryngeal muscles. 

Of this family, which in Europe is so numerous, there are in North America only two genera, Regulus and Sialia, the former composed of very small birds, allied in manners to the Tits, the latter approaching the Thrushes in form. The connecting links being wanting with us, these genera might seem at first sight very dissimilar.