The bird-life of the Caquetá is typical of the Amazonian forest, and many of the species are found on the lower river two thousand miles away. This is caused by the uniformity of topographical conditions, and the lack of a barrier that would interfere with the range of a species. On all of our visits to the headwaters of the Amazon’s tributaries, in Colombia, Bolivia, and Brazil, a large proportion of the mammals collected were new to science and differed greatly from those found lower down the river’s course. Such large animals as spider-monkeys (_Ateleus_), “flying” monkeys (_Pithecia_), and cats represented forms heretofore unknown to science; the smaller mammals also were new in many instances. Of course, we must not lose sight of the fact that the power of flight gives greater mobility to the birds and accounts for the wider range of some of them, but not for the equally vast distribution of the ground-inhabiting and almost flightless species. After a strenuous three weeks at La Morelia we returned to our first stopping-place near Florencia. The rainy season was at its worst, and low clouds covered the forest day after day, while torrents of water fell almost continuously. The journey back to Guadaloupe was far more difficult than had been our entrance into the region, for the greater part of it lay up-hill and mud and water had accumulated in spots until it was waist-deep. The cold grew more intense as we neared the top of the range. We were never warm or dry until we reached our destination. The maximum time allowed for work in Colombia had expired. Although I had spent over eighteen months in the republic, they had flown all too rapidly, and I heartily regretted that it was not possible to visit the numerous other places that invited exploration. The next best thing was to hope for a return trip in the future--a hope that was realized several years later in our expedition to the Antioquian Highlands. The homeward trip was accomplished without noteworthy incident. At first there was a ride of five days’ duration down the desert-like valley of the Magdalena to Neiva. The river is not navigable in this part of its course on account of rapids and shallow water. At Neiva a _champán_, or flat-bottomed freight-boat, was secured. The crew of twenty men rowed it down to Giradot in three days; it takes them thirty days to pull the craft back up-stream to the starting-point. The remainder of the journey to Puerto Colombia was merely a matter of travel on river-steamers and train, and required two weeks’ time. In summarizing the work of the expedition to the Caquetá, Doctor Chapman, in “The Distribution of Bird Life in Colombia,” writes as follows: