_Ibycter_, _Phalcobaenus_, and _Senex_ are kindred Neotropical genera of a greenish-black colour, with a variable amount of white on the tail, lower parts, and even the wings and nape; the cheeks and throat are naked and red in the first, and orange in the second, while the cheeks only are yellow in the third. _Phalcobaenus_ has a slight crest, _P. carunculatus_ a fleshy orange caruncle at the base of the bill, _Senex_ rufous thighs. _Ibycter ater_ occurs in Amazonia, _I. americanus_ from Guatemala and Honduras to Brazil, _Phalcobaenus megalopterus_ from Chili to West Peru, _P. carunculatus_ in Ecuador and New Granada, _P. albigularis_ in Patagonia, while _Senex australis_ is the "Johnny Rook" of the Falklands. Close allies are _Milvago chimachima_ and _M. chimango_, ranging from Panama to Paraguay, and from about lat. 20° S. to Tierra del Fuego respectively; the former is brown, with creamy head, neck, tail, and under-parts, and rectrices barred with brown; the latter has the head rufous and black, the lower surface streaky-looking yellowish-brown, the tail greyer. The lores and naked orbits are pinkish. These forms are similar in manners to _Polyborus_, but _Milvago_ is {153}more terrestrial, and chiefly frequents grassy plains; it is moreover less energetic, and has an easy and loitering though protracted flight, with a custom of uttering its whistling or mournful notes in chorus, the head being thrown back as in the Carancho. The nest of sticks, lined with grass, hair, and wool, may be on trees, in grass, or rushes, _Senex_ preferring sea-girt cliffs; the eggs, from two to five in number, are cream-coloured, or reddish with darker markings, and vary as in _Polyborus_. Human beings are very rarely molested by "Carrion Hawks," though birds seem to fear them greatly.