This genus includes a single species, the _P. unicinctus_, with its two climatic races, _unicinctus_ of South America and _harrisi_ of Middle America. It is most nearly related to the genus _Urubitinga_, of tropical America, the species of which are sluggish and almost Caracara-like in their habits, though they are hardly more so than our own _Buteones_. The genus _Craxirex_ of Gould having been founded upon _Buteo galapagoensis_, a species strictly congeneric with _B. borealis_, it is necessary that a new generic name should be instituted for the present species, since it so well merits separation to that rank. I accordingly propose the name given at the head of this chapter. Species and Races. =P. unicinctus.= Wing, 11.65–14.60; tail, 9.00–11.00; culmen, .82–1.10; tarsus, 2.78–3.75; middle toe, 1.52–2.00. _Adult._ General color brownish-black or blackish-brown, uniform, or slightly variegated by light spotting; the lesser wing-coverts and tibiæ deep rufous, or chestnut. Tail black; the end and base white, as are also the tail-coverts. _Young._ Plumage greatly variegated. Above blackish-brown, the feathers edged with rusty; head and neck streaked with pale ochraceous. Lower parts pale ochraceous or yellowish-white, the breast and abdomen with longitudinal ovoid spots of blackish; tibiæ with transverse bars of dark rusty; lower tail-coverts with black shaft-streaks. Lesser wing-covert region only washed with rufous. Tail grayish-brown, whitish at the tip, and crossed by narrow bands of dusky. _Adult_ with the blackish much broken up by lighter spotting. Wing, 11.65–14.60; tail, 9.00–10.50; culmen, .82–1.02; tarsus, 2.78–3.40; middle toe, 1.52–1.85. _Hab._ South America … var. _unicinctus_.[86] _Adult_ with the blackish continuous and uniform. Wing, 12.35–14.50; tail, 9.80–11.00; culmen, .90–1.10; tarsus, 3.15–3.75; middle toe, 1.65–2.00. _Hab._ Middle America, north into southern border of United States … var. _harrisi_. Parabuteo unicinctus, var. harrisi (RIDGWAY). HARRIS’S BUZZARD. _Falco harrisi_, AUD. B. Am. pl. cccxcii, 1831.—IB. Orn. Biog. V, 30. _Buteo harrisi_, AUD. Synop. 1839, 5.—BONAP. List, 3.—DE KAY, Zoöl. N. Y. II, 11.—_Craxirex unicinctus_, var. _harrisi_, RIDGWAY, P. A. N. S. Philad. Dec. 1870, p. 142. _Buteo unicinctus_, var. _harrisi_, COUES, Key, 1872, 215. “_Craxirex unicinctus_, TEMM.” CASS. Birds N. Am. 1858, 46.—DRESSER, Ibis, 1865, 329 (Texas).—COUES, P. A. N. S. 1866, 13 (Arizona).