BB. Hind toe inserted on the level of the rest. Nostrils opening beneath soft swollen membrane COLUMBÆ. Nostrils otherwise. Bill cered and hooked RAPTORES. Bill otherwise. Secondaries only six (_Cypseli_) PICARIÆ. Secondaries more than six (_a_) PASSERES. (_a_) Primaries 10; the 1st more than 2/3 as long as the longest. (_Clamatores_) PASSERES. Primaries 10; the 1st not 2/3 as long as the longest. (_Oscines_) PASSERES. Primaries 9. (_Oscines_) PASSERES. Recurring now to consideration of the North American _Families_ of the foregoing higher groups, I take up the latter in the natural order in which they have been presented, giving under head of each such group an analysis of the North American families by which it is represented, reiterating the caution that the characters are drawn up only with reference to the North American genera, and are, consequently, not necessarily or always applicable upon wider considerations. These analyses are made as nearly natural as the state of the case permits, but I seize upon any obvious external characters which may be afforded, without regard to their morphological significance or taxonomic value. ANALYSIS OF THE FAMILIES OF PASSERES. A. Oscines. Musical apparatus highly developed. Back of tarsus undivided, or formed of a few scutella distinct from those lapping over the front. First primary wanting, spurious, or at most not over two thirds the length of the longest. _a._ Each side of tarsus covered with a plate undivided in most or all of its length, and meeting its fellow in a sharp ridge behind. _b._ Primaries only nine. _c._ Bill triangular, depressed, about as wide at base as long; the gape twice as long as the culmen, reaching to about opposite the eyes; tomia straight or gently curved. No obvious rictal bristles. Tarsi not longer than the lateral toe and claw. Wings long and pointed, the first primary equal to or longer than the second. Central tail-feathers not half as long as the wing … _Hirundinidæ_. _cc._ Bill variously conico-elongate or slender, or, if depressed, with long rictal bristles; gape not nearly twice as long as culmen; tomia straight or gently curved. Nostrils not obviously nearer culmen than tomia. Tarsus longer than lateral toe and claw. Bill very slender, acute; culmen rather concave at base. Longest secondary acuminate, nearly or quite equal to the primaries in the closed wing. Hind claw little curved, about twice as long as the middle claw. Hind toe and claw longer than middle toe and claw … _Motacillidæ_.