One, at least, of the indispensable conditions of the development of urban life is fully realized in the district of Lake Nahuel Huapi and the Limay. It is a remarkable meeting-place of natural roads, and its economic value will increase in the future. It is the point where the road from eastern Patagonia by the sub-Andean depression, from the Gulf of San Antonio on the Atlantic, and from the Rio Negro by the Limay, and the roads that lead to Chile across the Cordillera, meet. The whole zone of the Andes between 36 deg. S. lat. and 42 deg. S. lat., the latitude of the southern part of the Chilean plain, has numerous and easy passes. There has always been close communication between the two slopes, and people have emigrated freely from one to the other. But north of 39 deg. S. lat. the passes are rarely lower than 5,000 feet. They are covered with snow in the winter, and can be used for traffic only in certain seasons. It is not the same south of the volcano Lanin. That is the beginning of the glacial valleys which go to the heart of the Cordillera, some of them crossing the mountains from east to west. They have not yet been entirely explored. The Bariloche pass, south of the Tronador, by which the Chilean missionaries reached Nahuel Huapi in the eighteenth century, is no longer used. The Cajon Negro pass, west of Lake Traful, through which Bailey Willis traces the line of a southern trans-Andean railway, was only recently discovered, and the valleys which run into it on the Chilean side are not yet well known. The two best-known trans-Andean routes to-day are the Perez Rosales road, which leads from Chile to Nahuel Huapi by the north of the Tronador, and further north, the road from Lake Lacar to San Martin. Both these have received some attention, and the lakes are connected by telegraph or telephone. The frequent need to unload and reload makes the traffic costly, but it is permanent and is not interrupted in winter. The reduction of the export of cattle to Chile has cut down the traffic for a time, but it is sure to recover. The permanent importance of it is one of the facts most clearly written by nature upon the soil of South America. * * * * *