ANNOTATIONS AND ADDITIONS. 39 



aquarum" at the sources of the Baures and near Yillabella, 

 lat. 15 17. 



This Hue of separation of the waters is important in relation 

 to facilities of intercourse, and to the increase of cultivation 

 and civilisation : more to the north (2 3 N. lat.), a similar 

 line divides the basin of the Orinoco from that of the Ama- 

 zons and the Rio Negro. These risings or swellings in the 

 plains (called, by Frontin, terrse tumores) might be regarded 

 as undeveloped systems of mountains, which would have con- 

 nected two apparently isolated groups (the Sierra Parime 

 and the Brazilian mountains) with the Andes of Timana and 

 Cochabamba. These relations, which have been hitherto but 

 little attended to, are the ground of the division which I 

 have made of South America into three basins ; viz. those 

 of the lower Orinoco, of the Amazons, and of the Eio de 

 la Plata. The first and last of these are steppes or prairies ; 

 the middle basin, that of the Amazons, between the Sierra 

 Parime and the Brazilian group of mountains, is a forest- 

 covered plain or Hyl<ea. 



If we wish to trace, in equally few lines, a sketch of the 

 natural features of North America, let us cast our eyes first 

 on the mountain chain which, running from south-east to 

 north-west, at first low and narrow, and increasing both in 

 breadth and height from Panama to Yeragua, Guatimala, 

 and Mexico (where it was the seat of a civilisation which 

 preceded the arrival of Europeans), arrests the general equa- 

 torial current of the waters of the ocean, and opposes a 

 barrier to the more rapid commercial intercourse of Europe 

 and Western Africa with the eastern parts of Asia. North 



