The Cumanacoa plains, scattered with farms and tobacco plantations, are surrounded by mountains, which are higher in the south. Everything suggests that the valley is an ancient seabed. The mountains that once formed its shores rise vertically from the sea. When excavating foundations near Cumanacoa, beds of round pebbles mixed with small bivalve shells were found. According to many reliable people two enormous femur bones were discovered, about thirty years ago. The Indians took them, as do people today in Europe, for giant's bones, while the semi-educated country people, who try to explain everything, seriously claimed that they are nature's sports, not worthy of consideration. They were probably the gigantic femur of elephants of a vanished species.

May 5th. We set off on foot following our boat, which had reached Caìo Pimichín by portage. We had to wade through numerous streams. This journey demands caution because water snakes teem in the marshes. Indians pointed out tracks in the wet clay left by the small black bears that are so common on the Temi banks. They are different in size from the Ursus americanus: missionaries call them oso carnicero to differentiate them from the oso palmero or tamanoir Myrmecophaga jubata) and the oso hormiguero or tamandua ant-eater. Two of these animals, which are good to eat, defend themselves by rising up on to their hind legs. Buffon's tamanoir is called uaraca by the Indians: they are irascible and brave, which is strange given that they are without teeth. As we advanced we came across some accessible clearings in the jungle. We picked new species of coffea, a Galega piscatorum, which Indians use like the jacquinia, and a composite plant of the Temi river, as a kind of barbasco to stun fish; and a large liana known locally as bejuco de mavacure, which gives the famous curare poison.

May 10th. Overnight our canoe was loaded and we set off a little before dawn to go up the Río Negro to the mouth of the Casiquiare and begin our researches on the true course of this river linking the Orinoco and Amazon. The morning was beautiful, but as the heat rose the sky began to cloud over. The air is so saturated with water in these forests that water bubbles become visible at the slightest increase of evaporation on the earth's surface. As there is no breeze the humid strata are not replaced and renewed by drier air. This clouded sky made us gloomier and gloomier. Through this humidity Bonpland -lost the plants he had collected; for my part I feared finding the same Río Negro mists in the Casiquiare valley. For more than half a century nobody in the missions has doubted the existence of communications between the two great river systems: the important aim of our journey was reduced to fixing the course of the Casiquiare by astronomic means, especially at its point of entry into the Río Negro, and its bifurcation with the Orinoco. Without sun or stars this aim would have been frustrated, and we would have been uselessly exposed to long, weary deprivation. Our travelling companions wanted to return by the shortest journey, along the Pimichín and its small rivers; but Bonpland preferred, like myself, to persist in the original plan we had traced out while crossing the Great Cataracts. We had already traveled by canoe from San Fernando de Apure to San Carlos along the Apure, Orinoco, Atabapo, Temi, Tuamini and Río Negro for over 180 leagues. In entering the Orinoco by the Casiquiare we still had some 320 leagues to cover from San Carlos to Angostura. It would have been a shame to let ourselves be discouraged by the fear of a cloudy sky and the Casiquiare mosquitoes. Our Indian pilot, who had recently visited Mandavaca, promised us sun and 'those great stars that eat up clouds' once we had left the black waters of the Guaviare. So we managed to carry out our first plan and returned to San Fernando along the Casiquiare. Luckily for our researches the Indian's prediction was fulfilled. The white waters brought us a clear sky, stars, mosquitoes and crocodiles.

In the snake-bitten Indian's hut we found balls, some 2 to 3 inches thick, of an earthy, dirty salt called chivi, which Indians prepare meticulously. In Javita they make salt by burning the spadix and fruit of the seje palm. As well as this they also distil the ashes of the famous cupana, a liana. A missionary seldom travels without seeds prepared from the cupana. This preparation requires great care. The Indians break up the seeds and mix them with cassava flour wrapped in banana leaves and leave the mixture to ferment in water until it becomes a saffron-yellow colour. This yellow paste is dried in the sun and taken in the morning as a tea. The drink is bitter and stomachic, though I found it repulsive.

Having reached the south of the Caravine raudal we saw that the winding Casiquiare again approached San Carlos. By land the distance from the San Francisco Solano mission, where we slept, is only 2. leagues, but by river it was 7 or 8. I spent part of the night outside, vainly waiting for stars to appear.

We followed the same route as Columbus had taken on his first voyage out to the Antilles. It is well known that during the crossing from Santa Cruz to Cumana, or from Acapulco to the Philippines, sailors barely have to worry about working the sails. We crossed the ocean as if descending a river, and would have been in no greater danger if we had made the voyage in an open boat.