Basal joint of middle toe shorter than that of the inner toe, united to the outer for about two thirds, to the inner for about one half, its length. Tarsus longer than middle toe and claw. Gonys more than half the length of the under jaw. Bill very weak and slender, little decurved or notched at tip. Very small,—under six inches long. (Tarsi booted in _Regulus_, distinctly scutellate in _Polioptila_.) … _Sylviidæ_. _ff._ Basal joint of middle toe quite free from the inner, and not united with the outer more than half-way. Nostrils linear, low. No bristles or bristly points whatever about the mouth. Wings short, rounded, concavo-convex. Tail very short, nearly concealed by its coverts. Tarsi booted … _Cinclidæ_. Nostrils oval. Bristles or bristly points about the mouth. Wings very long and pointed, reaching, when folded, beyond the middle of the short, square, or emarginate tail, and one and a half times or more the length of the latter; tip formed by second, third, and fourth quills; outer secondary reaching only about two thirds way to end of longest primary; spurious quill very short. Tarsi booted … _Saxicolidæ_. Nostrils oval. Bristles or bristly points about the mouth. Wings moderate, not reaching, when folded, beyond the middle of the tail, and not over one and a third times as long as the latter; tip formed by third to sixth quill; outer secondary reaching in closed wing three fourths or more the length of the longest primary. Spurious quill longer, sometimes one half the second. Tarsi scutellate in _Miminæ_, booted in _Turdinæ_ … _Turdidæ_. _aa._ Outside of tarsus covered with two series of scutella,—one lapping entirely around in front, the other entirely around behind, and meeting at a groove on the inside; hind edge blunt. First primary spurious or apparently wanting. Hind claw much lengthened, scarcely curved. Nostrils with antrorse bristly feathers. Bill conico-elongate … _Alaudidæ_. B. Clamatores. Outside of tarsus covered with a series of plates variously arranged, lapping entirely around in front and behind, to meet at a groove on the inner side.