Thurid and the therns could not have come this way. By stumbling upon the wrong course I had lost the trail, and they had gained so much ahead of me that now I might not be able to find them before it was too late, if, in fact, I could find them at all.

It had taken several hours to force my way up to the falls against the strong current, and other hours would be required for the descent, although the pace would be much swifter.

With a sigh I turned the prow of my craft down stream, and with mighty strokes hastened with reckless speed through the dark and tortuous channel until once again I came to the chamber into which flowed the three branches of the river.

Two unexplored channels still remained from which to choose; nor was there any means by which I could judge which was the more likely to lead me to the plotters.

Never in my life, that I can recall, have I suffered such an agony of indecision. So much depended upon a correct choice; so much depended upon haste.

The hours that I had already lost might seal the fate of the incomparable Dejah Thoris were she not already dead--to sacrifice other hours, and maybe days in a fruitless exploration of another blind lead would unquestionably prove fatal.

Several times I essayed the right-hand entrance only to turn back as though warned by some strange intuitive sense that this was not the way. At last, convinced by the oft-recurring phenomenon, I cast my all upon the left-hand archway; yet it was with a lingering doubt that I turned a parting look at the sullen waters which rolled, dark and forbidding, from beneath the grim, low archway on the right.

And as I looked there came bobbing out upon the current from the Stygian darkness of the interior the shell of one of the great, succulent fruits of the sorapus tree.

I could scarce restrain a shout of elation as this silent, insensate messenger floated past me, on toward the Iss and Korus, for it told me that journeying Martians were above me on that very stream.

They had eaten of this marvelous fruit which nature concentrates within the hard shell of the sorapus nut, and having eaten had cast the husk overboard. It could have come from no others than the party I sought.

Quickly I abandoned all thought of the left-hand passage, and a moment later had turned into the right. The stream soon widened, and recurring areas of phosphorescent rock lighted my way.

I made good time, but was convinced that I was nearly a day behind those I was tracking. Neither Woola nor I had eaten since the previous day, but in so far as he was concerned it mattered but little, since practically all the animals of the dead sea bottoms of Mars are able to go for incredible periods without nourishment.

Nor did I suffer. The water of the river was sweet and cold, for it was unpolluted by decaying bodies--like the Iss--and as for food, why the mere thought that I was nearing my beloved princess raised me above every material want.

As I proceeded, the river became narrower and the current swift and turbulent--so swift in fact that it was with difficulty that I forced my craft upward at all. I could not have been making to exceed a hundred yards an hour when, at a bend, I was confronted by a series of rapids through which the river foamed and boiled at a terrific rate.

My heart sank within me. The sorapus nutshell had proved a false prophet, and, after all, my intuition had been correct--it was the left-hand channel that I should have followed.

Had I been a woman I should have wept. At my right was a great, slow-moving eddy that circled far beneath the cliff's overhanging side, and to rest my tired muscles before turning back I let my boat drift into its embrace.

I was almost prostrated by disappointment. It would mean another half-day's loss of time to retrace my way and take the only passage that yet remained unexplored. What hellish fate had led me to select from three possible avenues the two that were wrong?

As the lazy current of the eddy carried me slowly about the periphery of the watery circle my boat twice touched the rocky side of the river in the dark recess beneath the cliff. A third time it struck, gently as it had before, but the contact resulted in a different sound--the sound of wood scraping upon wood.