horizon that was dimming in the growing twilight,
Masten halted the pony again, but only for an instant. In the next he was
urging it on furiously. For looking back fearfully, he saw Catherson
bestriding his pony, a dread apparition, big, rigid, grim, just breaking
through the timber edge, not more than two or three hundred feet distant.
Masten had hoped he had distanced his pursuer, for he had ridden at least
five miles at a pace that he had never before attempted. There had been
no way for him to judge the pony's speed, of course, but when he had
halted momentarily he had noted that the animal was quivering all over,
that it caught its breath shrilly in the brief interval of rest, and now
as he rode, bending far over its mane, he saw that the billowing foam on
its muzzle was flecked with blood. The animal was not equal to the
demands he had made upon it.

But he forced it on, with spur and voice and hand, muttering, pleading
with it incoherently, his own breath coughing in his throat, the muscles
of his back cringing and rippling in momentary expectation of a flying
missile that would burn and tear its way through them. But no bullet
came. There was no sound behind him except, occasionally, the ring of
hoofs. At other times silence engulfed him. For in the deep sand of the
level the laboring ponies of pursued and pursuer made no noise. Masten
could hear a sodden squish at times, as his own animal whipped its hoofs
out of a miniature sand hill.

[Illustration: The grim, relentless figure behind him grew
grotesque and gigantic in his thoughts]

He did not look around again for a long time. Long ago had he lost all
sense of direction, for twilight had come and gone, and blank darkness,
except for the stars, stretched on all sides. He had never seen this sand
level; he knew it must be far off the Lazette trail. And he knew, too,
before he had ridden far into it, that it was a desert. For as twilight
had come on he had scrutinized it hopefully in search of timber, bushes,
a gorge, a gully--anything that might afford him an opportunity for
concealment, for escape from the big, grim pursuer. He had seen nothing
of that character. Barren, level, vast, this waste of world stretched
before him, with no verdure save the repulsive cactus, the scraggy yucca,
the grease-wood, and occasional splotches of mesquite.

They raced on, the distance between them lessening gradually. Masten
could feel his pony failing. It tried bravely,