+Buteo swainsoni+, _Scl. et Salv. Nomencl._ p. 118; _Withington, Ibis_, 1888, p. 469 (Lomas de Zamora); _Baird, Brew., et Ridgw. N. A. B._ iii. p. 263. +Buteo obsoletus+, _Sharpe, Cat. B._ i. p. 184. +Buteo albicaudatus+, _Scl. et Salv. P. Z. S._ 1869, p. 634 (Buenos Ayres). _Description._--Above blackish brown; scapulars slightly variegated with rufous; upper tail-coverts white, tinged with rufous; tail dark greyish brown, crossed by several ill-defined blackish bars: beneath white or pale ochraceous; a broad band covering the whole breast reddish brown; bill black; feet yellow; claws black: whole length 20·0 inches, wing 15·0, tail 8·5. _Female_ similar, but larger. _Hab._ North and South America. The figure given herewith (Plate XVI.) represents a fine adult female specimen of this Buzzard, obtained by Mr. Frank Withington at Lomas de Zamora, on the 4th of February, 1886, and now in Sclater's collection. Swainson's Buzzard is a North-American species, which has only recently been ascertained to occur in the southern part of the Western Hemisphere. Full details concerning it are given in the standard work on "North-American Land-birds," to which we have referred above. Messrs. Baird, Brewer, and Ridgway divide the species into two subspecies, "_swainsoni_" and "_oxypterus_" to the latter of which they refer the southern specimens, but they acknowledge that it is "difficult to express points of absolute difference" between these subspecies. It appears from what these authorities say (_l. c._ p. 268) that a young specimen procured by Hudson at Conchitas in 1860, and referred by Messrs. Salvin and Sclater with doubt to _B. albicaudatus_, really belongs to _B. swainsoni_. A second undoubtedly Argentine example is that procured by Mr. Withington and now figured. Like other Buzzards, _B. swainsoni_ varies much in plumage, and occasionally assumes a melanistic form, under which it was described and figured by Sclater in 1858 as _Buteo fuliginosus_ (_cf._ P. Z. S. 1858, p. 356, and Trans. Zool. Soc. vol. iv. p. 267, pl. lxii.). Mr. Gurney is of opinion that d'Orbigny's _Buteo unicolor_ is also referable to this form of _B. swainsoni_ (_cf._ Ibis, 1889, p. 134). A well-known writer on North-American birds (Capt. C. E. Bendire) gives the following account of the nesting of _Buteo swainsoni_ in Arizona:--