Char. Bill variable, usually almost straight; sometimes curved. Commissure generally nearly straight, or slightly concave. Upper mandible wider than lower. Nostrils exposed. Wings moderate; the outer primaries not much rounded. Tail variable. Feet large; tarsi mostly longer than the middle toe.
The species are usually small, and of dull color, though frequently handsomely marked. Nearly all are streaked on the back and crown, often on the belly. None of the United States species have any red, blue, or orange, and the yellow, when present, is as a superciliary streak, or on the elbow edge of the wing.
In the arrangement of this subfamily, as of the others belonging to the Fringillidæ, we do not profess to give anything like a natural system, but merely an attempt at a convenient artificial scheme by which the determination of the genera may be facilitated.
A. Tail small and short; considerably or decidedly shorter than the wings, owing either to the elongation of the wing or the shortening of the tail. Lateral toes shorter than the middle without its claw. Species streaked above and below. (Passerculeæ.)
a. Thickly streaked everywhere above, on the sides, and across the breast. Wing pointed; longest primaries considerably longer than the secondaries. Tail forked.
Centronyx. Hind claw very large; rather longer than its digit. The hind toe and claw, together, as long as or longer than the middle toe and claw. Other toes as in Passerculus. Claws gently curved. Tertials shorter than the secondaries. Tail forked, but the lateral feathers shorter.
Passerculus. Hind claw as long as its digit; the toe equal to the middle one without its claw; lateral toes falling considerably short of the middle claw. Wings very long; first primary longest. Tertials as long as the primaries. Tail forked; feathers acute.
Poocætes. Hind claw shorter than its digit; the whole toe less than the middle toe without its claw. Lateral toes nearly equal to the middle one, without its claw. Tertials but little longer than secondaries. Tail stiffened, forked; feathers acute, outer ones white.
b. Moderately streaked above, on the sides, and on the breast, the latter sometimes unstreaked; the dorsal streaks broader, the others fainter than in the last. Wings short, reaching a little beyond the base of the tail. Not much difference between the primaries and secondaries. Tail short, graduated, and the feathers lanceolate, acute.
Coturniculus. Bill short; thick. Tertials almost equal to the primaries; truncate at the end. Claws small, weak; hinder one shorter than its digit. Outstretched feet not reaching the tip of the tail. Tail-feathers not stiffened. (In one species tail nearly equal to the wing.)