is definitely known of the affluents of the Morona, Pastaza and Tigre, as the territory through which they run has been but slightly explored. The Santiago, which enters the Marañon near the Pongo de Manseriche, is formed by the confluence of the Paute, which rises in the province of Azuay, and the Zamora, which has its source among the mountains of Loja. According to Alexander Garland (_Peru in 1906_), the rivers of eastern Ecuador are navigable at low water for steamers of 2 to 4 ft. draft for an aggregate distance of 1503 m., as follows:-- Miles. Napo, to the mouth of the Aguarico 559 Curaray, up to Canonaco 286 Tigre, up to Cunambo-Huiviyacu confluence 416 Pastaza 31 Morona, up to the Rarayacu 211 These same rivers are navigable at high water for steamers of 19½ ft. draft for an aggregate distance of 1330 m., including 68 m. of the Aguarico, and for steamers of 2 to 4 ft. draft for an additional 733 m. The last aggregate includes an extension of 93 m. on the Pastaza, 99 on the Morona, 186 on the Napo, and the balance on the Manhuasisa, Cangaima, Pucacuro, Corrientes, Cunambo and Huiviyacu. On the western versant of the Andes of Ecuador there are three river systems of considerable size--the Mira, the Esmeraldas and the Guayas. The sources of the first--the Rioblanco, Pisco and Puntal--are to be found on the northern slopes of the transverse ridge which culminates in the Imbabura volcano. Its course is north and north-west to the Colombian frontier, thence westward and north-west to the Pacific, breaking through the Western Cordillera on its way. It forms the boundary line for some distance between Ecuador and Colombia, but near its mouth where the river turns northward Colombia has taken possession of the left bank and all the territory covered by its large delta. Its principal tributaries on the left are the San Pedro, Paramba, Cachiyacu, Chachavi and Canumbi, and on the right the San Juan, Caiquer and Nulpe. The delta channels of the Mira are navigable, being tributary to the Colombian port of Tumaco. The Esmeraldas drains all that part of the central plateau lying between the transverse ridge of Tiupullo on the south, and the Imbabura ridge on the north, together with the western slopes of the Cordillera between Iliniza and Cotocachi, and a considerable part of the lower plain. It is formed by the confluence of the Quininde and Toachi with the Guaillabamba between 40 and 50 m. above its mouth, and discharges into the Pacific in lat. 1° N., long. 79° 40' W., through a narrow and precipitous gorge. The volume and current of the river is sufficient to freshen the sea 2 m. from the coast. The Guaillabamba is the larger and more important tributary, and should be considered the main stream. It