SUMMARY OF THE CONTENTS. 459 



Phenomena which long-continued drought produces in the Steppe ; 

 sand-spouts, hot winds (Mirage) ; awakening of crocodiles and 

 tortoises from long summer sleep ..... 150 156 



Otomacs. General considerations on the practice of earth-eating 

 among particular nations or tribes. Clays and earths containing 

 Infusoria . . . . . . . . . 156160 



Figures graven on rocks throughout a zone running from east to 

 west, and extending from the Rupunuri, Essequibo, and the Pa- 

 caraima Mountains, to Caycara and the wildernesses of the Cassi- 

 quiare. Earliest notice (April, 1749) of these traces of former 

 civilization in the manuscript account of the travels of the surgeon 

 Nicolas Hortsmann of Hildesheim, found among D'Anville's papers 



160164 



The vegetable poison Curare or Ourari . . . . . 165 



Cataracts of the Orinoco p. 169 to p. 186. 



The Orinoco ; general view of its course. Ideas excited in Columbus 

 on seeing its embouchure. Its unknown sources are east of the 

 Mountain of Duida and the groves of Bertholletia. Causes of the 

 principal bends of the river . . . . . . 169 177 



The falls or rapids ; Raudal of Maypures enclosed by four streams. 

 Former state of the district. Island-like form of the rocks Keri 

 and Ocp. Grandeur of the view obtained on descending the hill of 

 Manimi, where a foaming river-surface of four miles in extent pre- 

 sents itself at once to the eye. Iron-black masses of rock rise like 

 castles from the bed of the river ; the summits of the lofty palm 

 trees pierce through the cloud of spray and vapor . 177 182 



Raudal of Atures; numerous islands; rocky dikes connecting one 

 island with another, and the resort of pugnacious golden Pipras. 

 Parts of the bed of the river at the cataracts are dry, from the 

 waters having found a passage by subterranean channels. We 

 visited the rocks at the closing in of night and during storm and 

 heavy rain. Unsuspected proximity of crocodiles . 182 183 



Celebrated cave of Ataruipe, the sepulchral vault of an extinct nation 



183186 



Scientific Elucidations and Additions p. 187 to p. 202. 

 The river-cow (Trichecus manati) lives in the sea at the place where, 

 in the Gulf of Xagua, on the south coast of the Island of Cuba, 

 springs of fresh water break forth .... 187 188 



Geographical discussion on the sources of the Orinoco . 189 193 

 The Bertholletia, a Lecythidea, a remarkable example of highly deve- 



