2. =F aurantius.=[56] Wing, 9.50–12.00; tail, 5.40–6.25; culmen, .96; tarsus, 1.50–1.60; middle toe, 1.75–2.10. Second quill longest; first longer than third. Crissum ochraceous, or white and rufous, with large transverse spots of black; upper tail-coverts sharply barred with pure white or pale ash. _Adult._ Above plumbeous-black, the feathers conspicuously bordered with plumbeous-blue. Throat and jugulum immaculate; white centrally and anteriorly, deep rufous laterally and posteriorly. Tibiæ plain rufous. _Young._ Above uniform dull black, the feathers sometimes bordered inconspicuously with rusty. Throat and jugulum varying from white to ochraceous or rufous (this always deepest laterally and posteriorly). Tibiæ sometimes thickly spotted transversely with black. _Hab._ Tropical America, north to Southern Mexico. 3. =F. rufigularis.=[57] Wing, 7.20–9.00 (♂, wing, 7.70; tail, 3.95–5.50; culmen, .45–.58; tarsus, 1.20–1.55; middle toe, 1.15–1.40). Second quill longest; first longer than third. Crissum uniform deep reddish-rufous, rarely barred with white and dusky. Upper tail-coverts obsoletely barred with plumbeous. _Adult._ Above plumbeous-black, the feathers lightening into plumbeous-blue on the edges and ends, and showing obscure bars on the posterior portions. Throat and jugulum ochraceous-white, the ochraceous tinge deepest posteriorly and without any streaks. _Young._ Above plumbeous-black, without lighter obscure bars, or with a brownish cast, and with faint rusty edges to the feathers. Throat and jugulum deep soft ochraceous, deepest laterally, the posterior portion usually with a few longitudinal streaks of dusky. _Hab._ Tropical America, north to Middle Mexico. Falco communis, GMEL. Var. =anatum=, BONAP. AMERICAN PEREGRINE FALCON; DUCK HAWK.