In the valleys north of 30° in Chile, I saw several pair, either of this species, or of the _P. montanus_ of D’Orbigny, (if, as is probable, they are different) or of some third kind. From the circumstance of its not extending (as I believe) so far south even as the valley of Coquimbo, it is extremely improbable that it should be the _M. albogularis_,—an inhabitant of a plain country twenty degrees further south. On the other hand, the _P. montanus_ lives at a great elevation on the mountains of Upper Peru; and therefore it is probable that it might be found in a higher latitude, but at a less elevation. M. D’Orbigny says, “Elle aime les terrains secs et dépourvus de grands végétaux, qui lui seraient inutiles; car il nous est prouvé qu’elle ne se perche pas sur les branches.” In another part he adds, “Elle descend cependant quelquefois jusque près de la mer, sur la côte du Pérou, mais ce n’est que pour peu de temps, et peut-être afin d’y chercher momentanément une nourriture qui lui manque dans son séjour habituel; peut-être aussi la nature du sol l’y attire-t-elle; car elle y trouve les terrains arides qui lui sont propres.”[9] This is so entirely the character of the northern parts of Chile, that, it appears to me extremely probable, that the _P. montanus_, which inhabits the great mountains of Bolivia, descends, in Northern Chile, to near the shores of the Pacific; but that further south, and on the opposite side of the Cordillera, it is replaced by an allied species,—the _M. albogularis_ of Santa Cruz. 5. MILVAGO MEGALOPTERUS. Aquila megaloptera, _Meyen_, Nov. Act. Acad. Cæs. Suppl. 1834, p. 64. Pl. VIII.