As we were slowly drifting along the bank to get the benefit of the current, which was strongest there on account of a bend in the river, I discerned the dark outline of some large object lying upon an immense fallen tree-trunk. Approaching nearer, we found to our astonishment that it was an enormous boa-constrictor curled up fast asleep sunning himself. As our rifle was out of order I took deliberate aim with the shot-gun, and at a distance of some ten metres let fly at him. The hideous monster jumped up and, after lashing his tail wildly about two or three times, plunged with a splash into the water but a few metres from our canoe and was lost to sight. From our short view of him we perceived that he was of a dark-brown colour, except his belly, which was white and about ten inches in diameter; his length being, as near as we could judge, some twenty or twenty-five feet. These reptiles are fairly numerous on the Putumayo. Along here we noticed that the river followed a regular system of long windings. First one bank would be eaten into by the strong current that swept past it, while the opposite shore would be protected by an extensive sand or gravel _playa_, often a kilometre or so in width. Then the current would in the course of a couple of kilometres reach the other bank and begin its scouring operations there, while the first would commence to accumulate a _playa_. This system of long curves or windings extends along the whole course of the Putumayo, and it is to be observed in most of the large rivers of the Amazon basin. It is this that makes the Putumayo so wide and shallow and accounts for the numerous sand islands thrown up in mid-stream. In low water the channel cut out by these everchanging currents must be strictly followed by all steamers and launches in order to prevent grounding. At eleven o'clock we stopped and had lunch, which I had cooked previously while Perkins was performing the rôle of _boga_, on a nice shady _playa_ on the right bank. Here I managed to kill a good-sized turkey, and, after continuing about two hours, I got another, so that for dinner we had an excellent meal, the chief _pièce de résistance_ being roast turkey. This operation concluded, we tied up the canoe securely, and instead of building a _rancho_ both went to sleep in the canoe under the _pamacari_. It was a little crowded, but we got along all right and passed the night quite comfortably.