On the 28th of March I was on the river bank trying to measure the width of the Apure river, which was 206 toises. It was thundering everywhere; the first storm and rains of the rainy season. The river was whipped up by an east wind into large waves, then it suddenly calmed down, and then many large cetaceans, resembling the dolphins of our seas, began to play in long lines on the river surface. The slow and lazy crocodiles seemed to fear these noisy and impetuous animals as they dived underwater when these animals approached. It is extraordinary to find these mammals so far from the coast. The mission Spaniards call them toninas, as they do dolphins; their Tamanaco name is orinucna. They are 3 to 4 feet long, and on bending their backs and whipping the water with their tails they reveal part of their back and dorsal fins. I did not succeed in catching any of them, though I often paid Indians to shoot at them with arrows.

April 21st. After spending two and a half days in the little village of Maypures near the Great Cataracts, we embarked in the canoe that the Carichana missionary had got for us. It had been damaged by the knocks it had received in the river, and by the Indians' carelessness. Once you have passed the Great Cataracts (107) you feel you are in a new world; that you have stepped over the barriers that nature seems to have raised between the civilized coasts and the wild, unknown interior. On the way to the landing-stage we caught a new species of tree frog on the trunk of a hevea. It had a yellow belly, a back and head of velvety purple, and a narrow white stripe from its nose to its hind parts. This frog was 2 inches long; probably allied to the Rana tinctoria whose blood, so it is said, makes the feathers that have been plucked out of a parrot grow again in frizzled yellow and red if poured on to its skin.

Most of our animals were locked in small reed cages, but some rail freely about the boat. When it threatened to rain the macaws started a terrible racket, the toucan tried to fly to the shore to fish, and the titi monkeys ran to hide under Father Zea's long sleeves. These spectacles were common, and allowed us to forget the torment of mosquitoes. To camp at night we built a kind of leather box (petaca), held our provisions; next to it we placed our instruments and the animal cages; around this we hung our hammocks and a little further out the Indians' hammocks. Around the outside we lit fires to scare off jungle jaguars. The Indians often spoke of a small nocturnal animal with a long snout, which traps young parrots in their nests and uses its hands to eat like monkeys. They call it guachi; it is doubtless a coati. Missionaries forbid the eating of guachi flesh. Superstition claims that it is an aphrodisiac.

If you compare the Río Negro with the Amazon, the River Plate or the Orinoco it is but a river of the second order. Possessing it has been, for centuries, of great political interest for the Spanish Government because it affords its rivals, the Portuguese, easy access into the Guianan missions to worry the Capitanía-General of Caracas in its southern limits. Three hundred years have passed in pointless territorial disputes. In different times, according to their degree of civilization, people have leaned either on papal authority or on astronomy. As they have generally been keener to prolong this dispute rather than solve it, only nautical science and geography have gained anything. When the affairs of Paraguay and the possession of the Sacramento colony became important for the two Courts of Madrid and Lisbon, commissioners were sent out to study the boundaries of the Orinoco, Amazon and River Plate. Besides the idle, who filled archives with their complaints and lawsuits, there were a few educated engineers and some naval officers acquainted with the means of determining the position of a place. The little we knew up to the of the last century about the geography of the interior of the Continent is due to these hard-working men. It is pleasing to remind ourselves that the sciences gained accidentally from these border commissions, often forgotten by the states that sent them out.

The cave, known by the Indians as a 'mine of fat', is not in the Caripe valley itself, but some 3 leagues to the west-south-west. On the 18th of September we set out for that sierra, accompanied by the alcaldes and the majority of the monks. A narrow path led us first for an hour and a half south through an attractive plain covered with beautiful grass; then we turned west and ascended a rivulet that issues from the cave mouth. We followed this for three quarters of an hour, sometimes walking in the shallow water, or between the water and the rocky walls on very slippery and muddy ground. Many earthfalls and uprooted tree trunks, over which the mules labored, and creeping plants made this stretch very tiring. We were surprised to find here, at barely 500 toises above sea-level, the cruciferous plant Raphanus pinnatus.

It took us five long days from the Villa de Pao to the port of Nueva Barcelona. As we got closer the sky became clearer, the ground more dusty and the air more burning hot This oppressive heat does not arise from the temperature but from fine sand floating in the air, which irradiates heat in all directions, and whips your face and the ball of the thermometer. In fact I never saw the mercury rise above 45. once in this sand wind in America.

We spent only one day at San Fernando de Atabapo, despite the village, with its pirijao palms and their peach-like fruit, promising us a delightful refuge. Tame pauxis (Crax alector) ran round the Indian huts; in one of which we saw a very rare monkey that lives on the banks of the Guaviare. It is called the caparro, which I have made known in my Observations on Zoology and Comparative Anatomy. Its hair is grey and extremely soft to touch. It has a round head, and a sweet, agreeable expression.