The time now coursed smoothly and happily along, Pippity entertaining us with his lively prattle, and Grilly, full of his antics and his learning, affording a never-failing fund of amusement. Nor did he ever omit, when the supply of cocoa-nuts was about exhausted, to go down and assemble his tribe, who forthwith took their places up the height, passed the nuts one to another, and, when they deemed we had enough, dispersed to their own wild homes of sylvan shade. One day Grilly was amusing himself turning over some stones that lay in a little heap in one corner of our vast chamber. I had always thought it strange that they were the only loose stones to be found either in the cavern or in the neighborhood, but had never troubled myself any further about them. Seeing Grilly busy with them, I thought I would join him in his work or sport, and in a little time we had the pile reduced to the floor. There, I saw, was a square slab, having on it certain characters and a drawing of a serpent held firmly in the talons of a condor. These symbols excited my curiosity not a little, and I noticed that the stone, which was about three feet square, was loosely resting in its place. I managed to pry it up, and found a dark cavity beneath. It was nearly square, but of its depth I could not judge, owing to the darkness. To satisfy myself on this point, I got a very long stem of one of those gigantic grasses that grow in the tropics, and, letting it down, found the hole to be about forty feet deep. I felt a great desire to descend into this pit, but dared not venture for fear of the foul and deadly air that might have to be encountered below. Such things as matches, of course, we had not, nor any fire whatever. I therefore delayed the experiment for several days, with the expectation that the air would improve considerably in that time. Then, by bracing my hands and feet against the sides, I descended slowly, and found the air good enough to breathe freely, which emboldened me to go to the bottom. There was just light enough to perceive that on one side was an opening about six feet in height, and somewhat more than a foot in width; and I could see rough steps leading down a slight descent. I followed them cautiously, until I came to a level place, which I found to be a passage about three feet wide and higher than I could reach. It was so dark here that I could no longer see, when, feeling the rock on either side, I came to a place where there was a recess about three feet above the floor of the passage. Raising myself into this recess, I found it to be about four feet in height. This led back a considerable distance,--how far I never discovered,--and as I was groping about, being obliged to stoop all the time, I stumbled over something that rolled and rattled like a bone. I felt for it, and found it to be one, and with it were a number of others. As far as I could judge in the darkness, they were the skeleton of a human being.