We tried to find some traces of the wreck of the Undine, or of
anyone having lived there, but we found nothing beyond a great heap
of oyster shells that had been thrown into one corner. But Carver
Kinlay might very well have existed comfortably in this immense
place, for, besides the dried fish that he was said to have found
among the wreckage, there was a fine bed of oysters within easy
reach of the entrance to the cave, and these shellfish are good
enough eating, I believe. How he managed to keep Thora alive for so
long without other food was, however, a thing I could with
difficulty understand, unless she fed upon the sea-birds' eggs.
Thora, herself, remembered nothing of having been in the cave
before, but she was very anxious to reach its furthest limits, and,
trusting to me to follow her, she went fearlessly onward.

Sometimes she would stoop to lift a stone, and would throw it in
front of her to discover if there was a clear passage, for the
light burned but dimly. Once when she did so the stone fell upon
something that gave a peculiar hollow sound, as though some wooden
box or barrel had been struck.

I took little notice of this, for I was at the moment groping my
way into a side chamber of the cave. I was feeling my way back
towards the torch, when Thora called me to her as though she had
made some new discovery. But as I hurried in the direction whence
her voice sounded, I was startled by a loud and piercing scream
which filled the cavern and re-echoed through the empty corridors.
For a moment I fancied it was the shrieking of some monster
inhabitant of the cave and was about to beat a retreat when I heard
my name called again.

"Halcro! Halcro! Help! help!"

And then the whole place was in utter darkness, and I heard nothing
but the dying echoes, and a strange purling of running water.

I made my way as speedily as I could to where I had last seen the
lighted torch, and as I got further and further into the cave, the
sound of running water grew more distinct, until I heard it just at
my feet. It was not the singing ripple of a shallow rivulet, but
the sonorous sound of a deep stream that, so far as I could make
out, ran athwart the cavern. I went down on my knees and put my
hand in the water to feel which direction it took, for I did not
now doubt that my companion had fallen in, and was even now
struggling somewhere in the dark water that was rushing past me.

My first impulse was to throw myself