ILLUSTRATIONS (47). THE BEARDED APE. 141 



Indian names mutilated, or exchanged for those of Christian 

 saints. 



(46) p. 19 "Huge masses of leaden-coloured granite" 



In the Orinoco, and more especially at the cataracts of 

 Maypures and Atures (not in the Black River or Rio Negro), 

 all blocks of granite, even pieces of white quartz, wherever 

 they come in contact with the water, acquire a grayish black 

 coating, which does not penetrate beyond O'Ol of a line into 

 the interior of the rock. The traveller might almost suppose 

 that he was looking at basalt, or fossils coloured with graphite. 

 Indeed, the crust does actually appear to contain manganese 

 and carbon. I say " appears" to do so, because the phenomenon 

 has not yet been thoroughly investigated. Something per- 

 fectly analogous to this was observed by Rozier in the syenitic 

 rocks of the Nile (near Syene and Philae) ; by the unfortu- 

 nate Captain Tuckey on the rocky banks of the Zaire ; and 

 by Sir Robert Schomburgk at Berbice.* On the Orinoco these 

 leaden-coloured rocks are supposed when wet to give forth 

 noxious exhalations, and their vicinity is believed to be con- 

 ducive to the generation of fevers. f It is also remarkable 

 that the South American rivers generally, which have black 

 waters (aguas negras], or waters of a coffee brown or wine 

 yellow tint, do not darken the granite rocks ; that is to say, 

 they do not act upon the stone in such a manner as to 

 form from its constituent parts a black or leaden-coloured 

 crust. 



(47) p. 20 " The rain-foreboding howl of the bearded ape." 



Some hours before the commencement of rain, the melan- 

 choly cries of various apes, as Simia seniculus, Simla beelzebub, 

 &c., fall on the ear like a storm raging in the distance. The 

 intensity of the noise produced by such small animals can 

 only be explained by the circumstance that one tree often 

 contains a herd of seventy or eighty apes. I have elsewhere 

 spoken of the laryngeal sac, and the ossification of the larynx 

 of these animals.J 



* Reisen in Guiana und am OrinoTco, s. 212. 

 f See my Relat. hist., t. ii. pp. 299-304. 



J See my anatomical treatise in Recueil d 'Observations di Zoologie, 

 vol. i. p. 18. 



