This fine game bird in its size and mottled plumage resembles the _Rhynchotus rufescens_ of the pampas, which it represents in the Patagonian district south of the Rio Colorado. It differs externally in the more earthy hue of its plumage, which is protective and harmonizes admirably with the colour of its sterile surroundings; also in having a shorter beak, and in being adorned with a long slender black crest, which, when excited, the bird carries directed forwards like a horn. There is, however, an anatomical difference, which seems to show that the two species are not very near relations. The structure of the intestinal canal in the Martineta is most peculiar, and unlike that of any other bird I have ever dissected: the canal divides near the stomach into a pair of great ducts which widen towards the middle and extend almost the entire length of the abdominal cavity, and are thickly set with rows of large membranous claw-shaped protuberances. The Martineta inhabits the elevated tablelands, and is found chiefly where patches of scattered dwarf scrub occur among the thorny thickets. Apparently they do not require water, as they are met with in the driest situations where water never collects. They are extremely fond of dusting themselves, and form circular, nest-like hollows in the ground for that purpose; these hollows are deep and neatly made, and are visited every day by the same birds throughout the year. They live in coveys of from half a dozen to twenty or thirty birds, and when disturbed do not as a rule take to flight at once, but jump up one after another and run away with amazing swiftness, uttering as they run shrill, squealing cries, as if in the greatest terror. Their flight, although violent, is not so sounding as that of the Pampas Tinamou (_Rhynchotus_), and differs remarkably in another respect. Every twenty or thirty yards the wings cease beating and remain motionless for a second, when the bird renews the effort; thus the flight is a series of rushes rather than a continuous rush like that of the _Rhynchotus_. It is also accompanied with a soft wailing note, which appears to die away and swell again as the flapping of the wings is renewed. The call-note of the Martineta is never heard in winter; but in the month of September they begin to utter in the evening a long, plaintive, slightly modulated whistle, the birds sitting concealed and answering each other from bush to bush. As the season advances the coveys break up, and their call is then heard on every side, and often all day long, from dawn until after dark. The call varies greatly in different birds, from a single whistle to a performance of five or six notes, resembling that of _Rhynchotus_, but inferior in compass and sweetness. They begin to breed in October, making the nest in the midst of a small isolated bush. The eggs vary in number from twelve to sixteen; they are elliptical in form, of a beautiful deep green in colour, and have highly polished shells.