I could see still less now; and it was doubtless my very limitation of vision which added to the sense of fear and awe that surged at me. An abyss here, dark and soundless, the air was heavy, motionless, save as it moved past us with our forward flight. Air that now was foul as though heavy with the hot breath of the unseen monsters. There was no visible ceiling, no walls. But, as though my pupils were expanding in this greater darkness, I saw presently a black surface beneath us; and in another moment saw that we were flying barely a hundred feet above it. A level spread of silent water. There may have been a black luminosity to it; a phosphorescence, black, yet visible. I seemed, after another interval, to be staring over a great distance. A silent sea lay spread here under us. A vast area of water lying here like a great black shroud. A scum seemed on its dead, unriffled surface. A silent sea, yet it breathed with a slow rise and fall, as though with labored breath it lay dying. A world apart. I had thought our turgid ocean depths fearsome. But here was a new quality--a dark foul sullenness--this silent sea aloof, remote here in the bowels of our earth. I shuddered as I stared, for it seemed to me suddenly that only the dead should gaze upon such a place as this. And yet I knew that there were living things here. Creatures alive, but only in that one thing akin to living humans. Monsters lurked here, foul spawn of things unnameable, of form and manner and horror beyond all conception of the human mind. I looked away at last. This soundless abyss! But presently I began to hear a murmur; a surge; a roar. The water roaring at the flood-gates. And soon I saw that there was no longer water beneath us; a naked black rock surface. Entt whispered suddenly. “Look--out there!” Far away I saw a dull-red point of light. No! It was not far; a few hundred feet--a dull-red smoldering torch. It moved. A black shapeless blur seemed with it. A living creature slithering away on the rock surface? Formless, soundless: I was grateful for the concealing darkness. There are things which it is not good for human eyes to see--things that mark the mind with horror. I did not want to see it, yet I stared. And with imagination beyond curbing, I futilely tried to supply a head out there on the black rocks, or a giant black body, or legs and a tail. They are all words with meaning to our human mind. But this was none of those. My imagination was blessedly futile! For this thing, though perhaps it was partially visible, was beyond my conception. The eye--was it an eye? Or a fiery breath, congealed in the air? Or a heart--the essence of the thing’s being--nakedly visible? The red glow mercifully vanished, with only a dim radiance remaining, lingering like an infernal wraith of something which had been there and now was gone. We flew onward. The sound of the rushing water was monstrous ahead of us.