The country extending from the eastern banks of the Rio Ucayali to the Rio Yavari, which separates Peru from Brazil, is almost entirely unknown. In its general features it appears to resemble the Primps del Sacramento. Some bills of considerable elevation rise on the plain between 74' and 75' W. long.; and north of 7' S. lat. they are called the Sends Hilts.
The Pampa del Sacramento extends southward to the banks of the Rio Pachitea. The country which extends south of this river, from the eastern chain of the Andes to the Rio Ucayali, is more broken ; awl the heights rise near the Andes into lofty mountains, but towards the Ucayali sink into hills. The country along the banks of the Ucayali is rather flat, and covered with forests. .
Ilydrography.—The rivers which descend from the western declivity of the Western Andes and fall into the Pacific are about CO in number.
They have a short course, and flow with great rapidity; are shallow, and have very little water during the greater part of the year; many of them indeed are quite dry for several months. They cannot con seqeently be navigated even by the smallest canoes, but the water is used to irrigate the adjacent flat tracts.
All the large rivers of Peru originate within the mountain region, and all the waters which collect in it are united in three large rivers, the Maranon, the Huallaga, and the Ucayali. These three rivers may be considered as the principal branches of the Rio Amazonas. The Marcia* is noticed under Aluzorras, of which river it is commonly regarded as the principal branch. It issues from the Lake of Llaurieocha on the table-land of Pasco, and runs north-north-west about 150 miles in a narrow valley, and with great rapidity; it then flows in a wide valley with a mach gentler current for more than 250 miles to the Pongo of Itentems, end is navigated by balsas and canoes. From the confluence of the Tnnimbusa the Marabou becomes the boundary line between Peru and Ecuador. From the Pongo of Rentema the river turns to the north-east, and then to the east ; and after a course of 150 miles more it descends into the plains by the Pongo do 3Ianseriche, a rapid about 7 miles in length. At the foot of the Poogo de Manseriche is the town of Boris (in Ecuador), from which place the river is navigable for yokels drawing not more than 7 feet. After he union with the Huallaga and Ucayali its depth is so much increased that it is navigable for the largest vessels.
The Ilsallaga, wbleh joins the Mershon near 5' S. lat., 76' W. long., rises in the Lake of Quiluacocha, which la also on the table-land of Pasco, mouth-east of the Lake of Llatiricocha. It runs nearly 600 miles.
The southern half of its course is north-north-west, and the northern half north north-east. The upper part of its course is full of rapids, which may however be descended. These rapids cease at Juan del Res, south of 0' S. lat.; and the river thence affords an easy navi gation as far north as 8' S. lat., where several rapids again occur.
North of 6' 40' S. lat. occur the last rapids, which render the river nearly unnavigable for about 30 mike. North of 6' 20' S. lat. the Huallaga flows through a level marshy plain to its junction with the Manshon, and is navigable for vessel. of considerable size.
The Ucayali brings to the Amazonas the drainage of the mountain region situated between 11' and 15' S. lat. This large river is formed by the junction of the rivers Urnbarnba and Tsmbo, which takes pkos near 9' S. lat. The Uruhamba is formed by the union of the rivers Pancartamba and Quilabemba, which drain the eastern portion of the table-land of Cuzco, and running north, meet near II' 30' S. lat.
The Rip Tembo is formed by the confluence of the rivers Apuriniao and }tenter°. The Apurimac, which drains the western portion of the table-land of Cusco, unites with the 'denten), which drains the valley of the Jauja, and in its upper part is called Rlo Janja. Not far below the place where the Urubamba and Tambo by their union have formed the Ucayali, is a great rapid or cataract called Vuelta del Diablo. From this place downward the river runs above 500 miles, first north-north-west and afterwards north-north-east, and no impedi ment to its navigation by large vessels occurs in this part of its course. Among its chief tributaries is the Rio Pachitea, which rises on the eastern declivity of the mountains which inclose the upper vale of the Huallaga, near 10° S. lat., and runs first east and then north; falliug into the Ucayali near 8° 30' S. lat. Nearly the whole of its course appears to be free from impediments to navigation ; but its banks are inhabited by native tribes who are in a state of continual enmity with the whites.