destroyed the regularity of the majestic Cordilleras; in this inter-Andean region are also fertile valleys marking the courses of streams which have their origin in the Nudos of Vilcanota or Cerro de Pasco, and which flow between the ranges, until an opening occurs to give them passage to the plains of the mighty Amazon. The abundance of moisture carried by the winds from the Atlantic, and deposited on the Andean summits in the form of snow, accounts for the existence of several lakes at great altitudes in this region; in most cases, an opening in the surrounding mountains has caused an overflow into lower levels, thus originating the greatest river system of South America. There are evidences in the plains and valleys of the high sierras that these were at one time lakes, their waters having disappeared in consequence of the gradual wearing away of the opening and the levelling of the bed of the lake by sediments deposited in the course of ages. A few of these inter-Andean lakes still remain. The famous Lake Titicaca, which lies partly in Peruvian and partly in Bolivian territory, and which covers an area of more than eight thousand square kilometres, at an altitude of twelve thousand five hundred feet above sea level, is one of the most remarkable bodies of water in the world; it is the highest navigable lake on the globe, and is celebrated in South American tradition as the cradle of the Inca dynasty. Steam navigation was established on this lake in 1867, between the Peruvian port of Puno, at the Titicaca terminus of the Southern railway from Mollendo, and the Bolivian port of Guaqui, at the Titicaca terminus of the La Paz railway. The trip across the lake by steamer takes from twelve to fifteen hours, during which one may enjoy a most unusual experience, not only “on a sea above the clouds” but at times in view of a whole range of resplendent snow summits, glistening under a sky of marvellous blue. Many rivers and streams flow into Lake Titicaca, though only one, the Desaguadero, has its source in that lake. From the Nudo of Vilcanota at the north flow the rivers Suchis, Huancane, and Ramis, with their affluents; from the west, having their origin in the high sierra between Arequipa and Puno, descend the Cabanillas and Lampa, confluents of the Coata; and from the south, the Blanco, Juli, and smaller streams empty into the great lake. Besides Titicaca, Peru has several lakes of less extensive area, the most noted being the Laguna de Junin, famous as the site of the historic victory won by the patriot army over the colonial forces of Spain; Rimachuma in the Department of Loreto, and Arapa in Puno, are of considerable importance. [Illustration: THE BELL ROCK OF ETEN.] [Illustration: QUEBRADA SANTA ROSA, ANCASH DEPARTMENT.]