ANNOTATIONS AND ADDITIONS. 155 



Orinoco these leaden-colored rocks are considered to give out per- 

 nicious exhalations when wet ; and their proximity is believed to 

 produce fevers. (Rel. hist. t. ii. pp. 299-304.) In the Rio Negro, 

 and. generally in the South American rivers which have " black 

 waters/' " aguas negras," or waters of a eoflfee-brown or yellow tint, 

 no such effects take place. No black color is imparted to the granite 

 rocks by the waters ; that is to say, they do not act upon the stone 

 so as to form from its constituent particles a black or leaden-colored 

 crust. 



( 47 ) p. 41. "The rain-announcing howlings of the bearded apes" 

 The melancholy howlings of the small apes, Simia seniculus, Simia 

 beelzebub, &c., are heard some hours before the rain commences : it 

 is as if the tempest were heard raging at a distance. The intensity 

 of the noise produced by such small animals can only be explained 

 by their number; seventy or eighty being often lodged in a single 

 tree. On the organs of voice of these animals, see my anatomical 

 treatise in the first chapter of my Recueil d' Observations de Zoologie, 

 vol. i. p. 18. 



(*) p. 41. "Often covered with birds." 



The crocodiles lie so motionless that I have seen flamingos (Phee- 

 nicoptefus) resting on their heads ; the body at the same time being 

 covered with aquatic birds, like the trunk of a tree. 



( 49 ) p. 41. "Down his swelling throat" 



The saliva with which the boa covers his prey hastens the process 

 of decomposition;, the muscular flesh thus becomes softened into 

 such a gelatinous state, that he can force jentire limbs of larger, and 

 bodies of smaller, animals down his throat without division. The 

 Creoles call this gigantic serpent, from these circumstances, " Traga- 

 venado," which means "Stag swallower;" they tell fabulous stories 

 of snakes being seen with the antlers of a stag (which it was impos- 

 sible to swallow) sticking in their throats. I have several times 

 seen the boa swimming in the Orinoco, and in the smaller forest 

 streams, the Tuamini, the Temi, and the Atabapo. It holds its head 

 above the water like a dog. Its skin is finely spotted. It is said to 



