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4° and 8° of north latitude, and the Mountains 

 of Brazil, between 15° and 28° south latitude. 

 This singular distribution of great inequalities 

 of soil produces three plains or basins, that con- 

 stitute altogether a surface of 420,600 square 

 leagues, or four-fifths of all South America, east 

 of the Andes. Between the chain of the coast 

 of Venezuela and the group of Parime, the 

 plains of the Apure and the Lower Oroonoho ex- 

 tend ; between the group of the Parime, and 

 that of the Mountains of Brazil, the plains of 

 the Amazon, the Rio Negro, and the Madeira, 

 and between the groups of Brazil and the 

 southern extremity of the continent, the plains 

 of Rio de la Plata, and of Patagonia. As the 

 group of the Parime in Spanish Guyana, and 

 that of Brazil (or of Minas Geraes and Goyaz)^ 

 do not join the Cordillera of the Andes of New 

 Grenada and Upper Peru, towards the west, the 

 three plains of the Lower Oroonoko, the Ama- 

 zon, and the Rio de la Plata, communicate to- 

 gether by land-straits of considerable breadth. 

 These straits are also plains stretching from 

 north to south, and crossed by ridges imper- 

 ceptible to the eye, but forming divortia aqua- 

 rum. These ridges (and this striking pheno- 

 menon has not hitherto fixed the attention of 

 geognosts), these ridges, or lignes de faites, are 

 placed between the 2° and 3° of north latitude, 

 and the 16° and 18° of south latitude. The 



