e searched the horizon with so eager a
gaze, that he scarcely heeded a strident call from the half-breed, a
hundred yards in the rear.

Dolores turned and calmly observed:

"Antonio's horse has fallen."

"Antonio can follow us," said Simon.

For a few moments, they had been riding through a rather more uneven
tract of land, covered with a sort of downs with precipitous sides,
like cliffs. A fairly steep incline led to a long valley, filled with
water, on the brink of which the bandits' trail was plainly visible.
They entered the water, making for a place on the opposite edge which
seemed to them, at a distance, to be trampled in the same way.

The water, which barely reached the horses' hocks, flowed in a gentle
current from left to right. But, when they had covered a third of the
distance, Dolores struck Simon's horse with her long reins:

"Hurry!" she commanded. "Look . . . on the left. . . ."

On the left the whole width of the valley was blocked by a lofty wave
which was gathering at either end into a long, foaming breaker. It was
merely a natural phenomenon; as a result of the great upheaval, the
waters were seeking their level and invading the lower tracts.
Moreover, the flow was so gradual that there was no reason to fear its
effects. The horses, however, seemed to be gradually sinking. Dragged
by the current, they were forced to sheer off to the right; and at the
same time the opposite bank was moving away from them, changing its
aspect, shifting back as the new stream rose. And, when they had
reached it, they were still obliged, in order to escape the water,
which pursued them incessantly, to quicken their pace and trot along
the narrow lane enclosed between two little cliffs of dried mud, in
which thousands upon thousands of shells were encrusted like the cubes
of a mosaic.

Only after half an hour's riding were they able to clamber to a
table-land where they were out of reach. It was as well, for their
horses refused to go any farther.

The darkness was increasing. How were they to recover the tracks of
Isabel and her kidnappers? And how could their own tracks, buried
beneath this enormous sheet of water, be recovered by Antonio and his
men?

"We are separated from the others," said Simon, "and I don't see how
our party can be got together again."

"Not before to-morrow, at all events," said Dolores.

"Not before. . . ."

And so these two were alone in the night, in the depths of this
myster