When ascending the Despoblado, a branch of the valley of Copiapó in Northern Chile, I saw several brown coloured hawks, which at the time appeared new to me, but of which I did not procure a specimen. These I have no doubt were the _A. megaloptera_ of Meyen. In the British Museum there is a specimen, brought from Chile by Mr. Crawley. Mr. G. R. Gray suspects that this bird may eventually prove to be the young of the _Phalcobænus montanus_ of D’Orbigny, and as I saw that bird (or another species having a close general resemblance with it) in the valleys of Northern Chile, although not in the immediate vicinity, this supposition is by no means improbable. Meyen’s figure at first sight appears very different from that of the young of the _P. montanus_, given by M. D’Orbigny, for in the latter the feathers over nearly the whole body are more distinctly bordered with a pale rufous shade, the thighs barred with the same, and the general tint is of a much redder brown. But with the exception of these differences, which are only in degree, I can find in M. D’Orbigny’s description no other distinguishing character, whilst on the other hand, there are numerous points of close resemblance between the two birds in the shadings, and even trifling marks of their plumage. Meyen, moreover, in describing the habits of his species, says, it frequents a region just below the limit of perpetual snow, and that it sometimes soars at a great height like a condor. Those which I saw had the general manners of a _Polyborus_ or _Milvago_, and were flying from rock to rock amongst the mountains at a considerable elevation, but far below the snow-line. In these several respects, there is a close agreement with the habits of the _P. montanus_, as described by M. D’Orbigny. I will only add that the specimen in the British Museum appeared, independently of differences of plumage, distinct from the _M. albogularis_ of Patagonia, from the thinness and greater prolongation of its beak, and the slenderness of its tarsi. SUB-FAM.—BUTEONINÆ. CRAXIREX. _Gould._ _Rostrum Buteonis sed longius; mandibulæ superioris margo rectus; versus apicem subitò incurvus. Alæ elongatæ. Cera lata. Nares ferè rotundæ, apertæ. Tarsi mediocres, anticè squamis tecti. Digiti magni, fortes; ungues obtusæ._