"From the sand beyond the plain of Zachor," replied Garth. "It gushes up from a large lake; but there are men who say that it tunnels underground from the great desert of the north. Many of us have journeyed thither, but none have found these words to be true." "We found a Croixilian lying dead in the sand close to the river of which you speak," said the correspondent. "See! here is his dagger." Garth took the weapon and examined it carefully. "Certain it is that this belonged to one of us," he exclaimed. "See the sign of the Knights of St. Peter, an Order to which all of us here present belong." "How long ago did the man die?" asked Reeves. "That I cannot say. For years past we have journeyed into the desert, and many of us have not returned." "Why did they go?" asked Hugh, who was able to follow the conversation with tolerable ease. "To seek a sign," replied the man briefly, and in a manner that showed that he was unwilling to enlighten his listeners further on the matter. "But here we turn aside. Were it a clear day we might be able to perceive the city from this hill; but ere we cross the river we must needs travel a long distance down the valley." Between the river and the rocks that rose steeply on the north side of the valley ran a broad path, which ages ago had doubtless been formed by the action of the water, showing that the stream had been far greater than it was now. The cliffs, jagged and showing signs of volcanic agency on their higher parts, were smooth and rounded at their bases; while on the stiff mud that formed the floor of the valley tropical vegetation grew profusely. "This river, if properly held, ought to keep back your enemies, the Arabs," observed Reeves. "And would do so if it encircled Croixilia," replied their guide. "From this side we fear no foes, but from the east and from the west the infidels frequently appear in vast numbers." "And where does the river flow to?" asked the Englishman. "That also I cannot tell you," was the reply. "Away to the south for more than fifty leagues we have followed its course, but----" The man stopped hesitatingly, as if speaking of some mystery; then, setting spur to his horse, he cantered on ahead to join the horsemen who were leading the cavalcade, leaving the three comrades to their own companionship. Presently the cliffs on either side of the river began to converge, till they formed a gate or narrow pass barely fifty yards in width. Here the path plunged abruptly into a natural tunnel, where, in the sudden contrast from the glare of the sun, the Englishmen were unable to see a yard ahead. "Pull up till we get used to the gloom," exclaimed Reeves, "or we shall be banging our heads against the solid rock."