However, the hills gradually sank into a level plain, and the river carried us through it at a rate that enabled us during the remainder of the day to reel off thirty-six kilometres, a record that for the first time held out promise.  Twice tapirs swam the river while we passed, but not near my canoe.  However, the previous evening, Cherrie had killed two monkeys and Kermit one, and we all had a few mouthfuls of fresh meat; we had already had a good soup made out of a turtle Kermit had caught.  We had to portage by one short set of rapids, the unloaded canoes being brought down without difficulty.  At last, at four in the afternoon, we came to the mouth of a big river running in from the right.  We thought it was probably the Ananas, but, of course, could not be certain.  It was less in volume than the one we had descended, but nearly as broad; its breadth at this point being ninety-five yards as against one hundred and twenty for the larger river.  There were rapids ahead, immediately after the junction, which took place in latitude 10 degrees 58 minutes south.  We had come 216 kilometres all told, and were nearly north of where we had started.  We camped on the point of land between the two rivers.  It was extraordinary to realize that here about the eleventh degree we were on such a big river, utterly unknown to the cartographers and not indicated by even a hint on any map.  We named this big tributary Rio Cardozo, after a gallant officer of the commission who had died of beriberi just as our expedition began.  We spent a day at this spot, determining our exact position by the sun, and afterward by the stars, and sending on two men to explore the rapids in advance.  They returned with the news that there were big cataracts in them, and that they would form an obstacle to our progress.  They had also caught a huge iluroid fish, which furnished an excellent meal for everybody in camp.  This evening at sunset the view across the broad river, from our camp where the two rivers joined, was very lovely; and for the first time we had an open space in front of and above us, so that after nightfall the stars, and the great waxing moon, were glorious over-head, and against the rocks in midstream the broken water gleamed like tossing silver.

The huge catfish which the men had caught was over three feet and a half long, with the usual enormous head, out of all proportions to the body, and the enormous mouth, out of all proportion to the head.  Such fish, although their teeth are small, swallow very large prey.  This one contained the nearly digested remains of a monkey.  Probably the monkey had been seized while drinking from the end of a branch; and once engulfed in that yawning cavern there was no escape.  We Americans were astounded at the idea of a catfish making prey of a monkey; but our Brazilian friends told us that in the lower Madeira and the part of the Amazon near its mouth there is a still more gigantic catfish which in similar fashion