564 



de Manseriche, in the province of Maynas, 

 the barometric measurement of the course of 

 this river, which is the thalweg of a plain 

 fifteen times the extent of the whole of 

 France, will not be neglected. 



2.) Part of the basin of the Amazon stretch- 

 ing from south to north. This is the zone or 

 land strait by which, between 12° and 20° of 

 south latitude, the plains of the Amazon 

 communicate with the Pampas of Buenos 

 Ayres. The western bank of this zone is 

 formed by the Andes, between the knot of 

 Porco and Potosi, and that of Huanuco and 

 Pasco. Part of the counters-forts of the Rio Beni, 

 which is but a widening of the Cordilleras of 

 Apolobamba and Cuzco # , and the whole 

 promontory of Cochabamba *f*, advance tow- 

 ards the east in the plains of the Amazon. 

 The prolongation of this promontory has 

 given rise to the idea that the Andes are 

 linked with a series of hills which the Serras 

 dos Parecis J, the Serra Melgueira, and the 

 pretended Cordillera of San Fernando, throw 

 out towards the west. The almost unknown 

 part of the frontiers of Brazil and Upper 



* Vol. vi, p, 432. 

 f Vol. vi, p. 419. 

 % Vol. vi, p. 538. 



