91 



plains covered with forests ; the Indian of the 

 forests of Oroonoko there beholds open savan- 

 nahs, where the inhabitants are never stung by 

 moschettoes. 



Arrived farther toward the south, where the 

 system of yellowish-brown waters commences, 

 generally called black waters, aguas negras, on 

 the banks of the Atabapo, the Tuni, the Tuamini, 

 and the Rio Negro, we enjoyed a repose, I had 

 almost said a happiness, unexpected. These 

 rivers cross thick forests, like the Oroonoko, but 

 the tipulary insects, as well as the crocodiles, 

 shun the proximity of the black waters. Are 

 these waters, which are a little colder, and 

 chemically different from the white waters, ad- 

 verse to the larvae and the chrysalids of tipulary 

 insects and gnats, which may be considered as 

 real aquatic animals ? Some small rivers, the 

 colour of which is deep blue, or yellowish brown, 

 the Toparo, the Mataveni, and the Zama, are 

 exceptions to the almost general rule of the 

 absence of moschettoes over the black waters. 

 These three rivers swarm with them ; and the 

 Indians themselves fixed our attention on the 

 problematic causes of this phenomenon. In go- 

 ing down the Rio Negro, we breathed freely at 

 Maroa, Daripe, and San Carlos, villages situate 

 on the boundaries of Brazil. But this improve- 

 ment of our situation was of short continuance ; 

 our sufferings recommenced as soon as we en- 



