a. Points of mandibles overlapping.
Curvirostra. Tarsus shorter than middle toe. Bill much compressed, elongate falcate, with the points crossing like the blades of scissors. Claws very large; lateral extending beyond the base of the middle. Colors red or gray. Streaked in juv.
b. Points of mandibles not overlapping.
Ægiothus. Tarsus equal to the middle toe. Bill very acutely conical; outlines and commissure perfectly straight. Lateral toes reaching beyond the base of the middle one. No ridge on the side of the lower mandible. Streaked; a crimson pileum (except in one species).
Leucosticte. Culmen slightly decurved; commissure a little concave. Bill obtusely conical; not sharp-pointed. A conspicuous ridge on the side of the lower mandible. Claws large; the lateral not reaching beyond the base of the middle one. Colors red and brown.
D. Hind claw much the largest; decidedly less curved than the middle anterior one. Tarsus longer than the middle toe. Lateral toes equal; reaching about to the base of the middle claw. Hind toe as long or longer than the middle one. Bill very variable; always more or less curved and blunted. Palate somewhat tuberculate; margins of lower jaw much inflexed. Tail slightly emarginate or even. Wings one half longer than the tail. First quill as long as the second.
Plectrophanes. Colors black and white. With or without rufous nape or elbows. Much white on tail.
Genus HESPERIPHONA, Bonap.
Hesperiphona, Bonap. Comptes Rendus, XXXI, Sept. 1850, 424. (Type, Fringilla vespertina.)
