Whole head, neck (except the throat), and upper parts, continuously uniform unvariegated brownish-black; that of the neck meeting narrowly across the lower part of the throat, leaving the whole throat almost immaculate white. Posterior lower parts fine, deep pinkish-ochraceous; tibiæ deep reddish-ochraceous; upper tail-coverts plain rufous. _Hab._ Central America (from Tres Marias, Western Mexico, to Costa Rica and Veragua) … var. _costaricensis_. Tibiæ and lower tail-coverts always with distinct transverse bars. Tail often with more or less complete transverse bars of black to the base. Lower parts with an excess of ochraceous and darker markings, frequently wholly blackish. Varying, from individuals distinguishable from the darker examples of var. _borealis_ only by the presence of bars on the tibiæ and crissum, through others with various degrees of rufous tinge and dusky spotting and barring beneath, to a perfectly melanistic condition, in which the bird is almost uniformly black, and the tail with continuous, regular bars of black to the base. _Hab._ Western Province of North America, from the Rocky Mountains to the Pacific … var. _calurus_. 6. =B. harlani.= Wing, 15.00–16.20; tail, 8.80–10.50; culmen, 1.00; tarsus, 2.75–2.90; middle toe, 1.50–1.70. Lateral toes nearly equal; tibial plumes much developed, reaching below the bases of the toes. Entirely brownish-black (except the tail), the concealed bases of the feathers snowy-white. _Adult._ Tail confusedly mottled with dusky and white, upon a grayish ground; sometimes more or less tinged with rufous. _Young._ Tail grayish-brown, with nine very regular, sharply defined bands of brownish-black, about equal in width to the gray ones. Lower parts wholly dusky. _Hab._ Southwestern United States, east of the Rocky Mountains, from Kansas to Texas. 7. =B. cooperi.= Wing, 15.75; tail, 9.10; culmen, 1.10; tarsus, 3.25; middle toe, 1.70. _Adult._ Head, neck, and beneath, pure white, the head above and nape streaked with dusky; lining of the wing white, with a large black patch. Above nearly uniform dusky, the primaries plumbeous. Tail longitudinally mottled with light rufous, cinereous, and dusky; the former prevailing. _Hab._ Santa Clara County, California. Buteo pennsylvanicus (WILS.). BROAD-WINGED HAWK.