The mists of night had lifted, revealing clumps of tall bamboo and the beginning of heavy forest. In the top of the very first trees sat a group of large monkeys, red, with golden backs, properly called howling monkeys; they were the authors of the terrific chorus we had just heard. How an animal that rarely attains a weight of thirty pounds can produce such loud sounds is most remarkable; the hyoid bone is developed into a huge cup which gives resonance to the voice. The howlers are rather sluggish and seldom descend from the trees. Their roaring, which can be heard several miles, resounds through the forest morning and night; whether it is merely a form of amusement with them, or is used to intimidate enemies, seems to be unknown. [Illustration: The _Caldas_ fast on a sand-bar in the Cauca River.] [Illustration: Bamboo rafts on the Cauca River.] Very little is known about the habits of howling monkeys, despite their abundance and wide distribution. They are usually found in small family parties, including young of various sizes; but I have noticed, on various occasions, that the females desert from the troop when their babies are males and do not rejoin it until the young are half-grown, perhaps fearing that the old males will kill them; but I do not know if this is always the case. C. William Beebe, in the course of a lecture at the American Museum, stated that he had on several occasions watched troops of these animals feed, in British Guiana. The older ones sent their small young to the tip of the slender branches that they, themselves, could not venture upon on account of their weight, to pick fruits; then they pulled the little ones back and robbed them of their food. This was repeated a number of times. The second night we tied up near a heavy growth of forest, at a place called Riofrio. This is one of the few sections of the Cauca Valley still retaining its original stand of virgin jungle. We slung our hammocks between the trees. The nets furnished ample protection from the mosquitoes, but not from an army of foraging ants that chanced our way. From across the river came the whine of an ocelot, and the sharp snort of deer, while more than once we were awakened by the pattering and shuffle of cautious feet close at hand, some light, some heavy as if belonging to a large animal. Contrary to her custom, the _Caldas_ steamed on after dark on the third night of her voyage. A train of bright sparks trailed far behind, and when the wind blew it carried them into the boat where they set fire to clothing and baggage alike. Within a short time we had reached the port of Cartago, found the _arriero_ who was awaiting us with the animals, and were off for Cartago a league away. The town was enveloped in inky blackness, and fast asleep, notwithstanding the early hour. A stray dog barked and a mule whinnied, but there were no other signs of life. CHAPTER IV CARTAGO TO THE PARAMOS OF RUIZ AND SANTA ISABEL