Smaller than the preceding; tail long, rounded. Adult, head above black; other upper parts dark brownish black, with a tinge of cinereous, darkest on the back. Throat and under tail-coverts white; other under parts fine light rufous, deepest on the tibiæ, and barred and spotted with white nearly obsolete on the breast, sides and tibiæ, the longitudinal dark lines on the shafts of the feathers, (conspicuous in _A. Cooperii_,) barely discernible on the breast. Quills, dark brown, edged exteriorly with ashy, and with bands of darker brown and white on their inner webs; tail, dark cinereous, tipped with white, and with four bands of brownish black, that near the base of the tail obscure. Young, head and neck behind, and upper part of the back, dark rufous, striped with brownish black; other upper parts umber brown; under parts white, with longitudinal narrow stripes of brown; wings and tail as in adult; upper tail-coverts tipped with white. “Iris, carmine,” Dr. Gambel. Dimensions. Total length, male, 15 inches, wing 9, tail 8 inches. Hab. California (Dr. Gambel, Mr. Bell); Mexico (Mr. Pease); Eastern? Spec. in Mus. Acad. Philada. Obs. Similar for the greater part, to _A. Cooperii_, but smaller, and with the tail and tarsi comparatively longer, and with the fine red of the under parts more uniform, the white stripes being nearly obsolete. Several specimens of both adults and young were brought in the fine collection made in California by Mr. J. G. Bell, of New York, and it was previously brought from the same country by Dr. Gambel, and from Mexico by Mr. Pease. III. SUB-FAMILY BUTEONINÆ. THE BUZZARDS. Bill short, strong, upper mandible curved, and with its edges festooned; wings long and broad; tail moderate, rather short; legs and feet moderate; toes rather short. General form heavy; flight vigorous, and capable of being long continued, but not so swift as in preceding sub-families. This group comprises about twenty-five species of all countries. I. GENUS BUTEO. Cuvier, Reg. An., I. p. 323. (1817.) PŒCILOPTERNIS. Kaup, Isis, 1847, p. 329. Bill short, wide at base, edges of upper mandible festooned; nostrils large, ovate; wings long, wide, fourth and fifth quills usually longest; tail moderate, rather wide; tarsi rather long, and having transverse scales before and behind, but laterally small circular scales; toes moderate, rather short; claws strong. Comprises about twenty species, inhabiting all countries.