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not accompany the patos careteros in their mi- 

 gration from the Oroonoko to the Rio Branco. 

 These regular migrations of birds from one part 

 of the tropics toward the other, in a zone which 

 is daring the whole year of the same temperature, 

 are very extraordinary phenomena. The south- 

 ern coasts of the West India islands receive 

 also every year, at the period of the inundations 

 of the great rivers of Terra Firma, numerous 

 flights of the fishing birds of the Oroonoko, 

 and of it's tributary streams. We must pre- 

 sume, that the variations of drought and hu- 

 midity in the equinoctial zone have the same 

 influence, as the great changes of temperature 

 in our climates, on the habits of animals. The 

 heats of summer, and the pursuit of insects, call 

 the humming birds into the northern parts of 

 the United States, and into Canada, as far as 

 the parallels of Paris and Berlin ; in the same 

 manner a greater facility for fishing draws the 

 palmipede and long legged birds from the north 

 to the south, from the Oroonoko toward the 

 Amazon. Nothing is more marvellous, and 

 nothing is yet known less clearly in a geogra- 

 phical point of view, than the direction, extent> 

 and term of the migrations of birds! 



After having entered the Rio Negro by the 

 Pimichin, and passed the small cataract at the 

 confluence of the two rivers, we discovered, at 

 the distance of a quarter of a league, the mission 



