The Cauca, a swift, muddy stream four or five hundred feet wide at this point, is hemmed in on both sides by the steep slopes of the Western and Central Andean Ranges, the forest extending down to the water. It is navigable from here on down to a small settlement called Cáceres, but rafts and canoes only are employed in making this journey, which requires half a day going down and two days coming up. The natives are a careless lot while on the water, and numbers of lives are lost annually. About the first thing we saw was the body of a man floating down the river, with a vulture perched on it. We asked Don José, owner of the place, why he did not send some of his peons in a canoe to recover it. He replied that if he did he would be required to care for the body until a government official from Yarumal came to view it, and then he and every one present would have to go back with the coroner to give their testimony as to the finding of the cadaver. This entailed so much trouble that it was customary not to pay any attention to such occurrences. In few places have I seen such an abundance of interesting fauna as at Puerto Valdivia. The forest was teeming with birds; mammals were plentiful; shoals of fish and even caimans swarmed in the river; there were also insects enough to cheer the heart of an entomologist. [Illustration: A naturalists’ camp in the forest.] [Illustration: A native hunter with a red howling monkey.] In such a region the naturalist has no idle moments. When we tired of working with birds and mammals, which were of chief interest to us, we had only to step to the river-bank, where vast swarms of brilliantly colored butterflies settled in thick masses in the mud or rocks to drink. A single sweep of the net often ensnared several score of the insects. A species of _Urania_ of a black and green color predominated, but a _Diana_, deep red above and spotted with silver dots on the under-side was not uncommon. Fish could always be secured in abundance. If we attempted to catch them with hooks we usually landed catfish or small eels. It is unlawful to use dynamite in Colombia, but Don José had a goodly supply stored away and did not hesitate to use it when occasion required. The _peons_ detailed for that purpose selected a spot in the river where logs and brush had grounded to form a drift, or where the water eddied against a sharp bend; they tied a rock to the explosive, lit the fuse and threw it into the water. After a few moments, during which the water hissed and bubbled as the gases from the burning fuse rose and escaped, a dull thud followed and, almost immediately, the surface was littered with numbers of dead and stunned fish. They were invariably a species of “Pacu” (_Prochilodus nigricans_), weighing from one to four or five pounds, and proved to be excellent eating.