, being quick to
learn, he hoped to graduate from that class after a while. Having always
been fond of outdoor sports in his Kentucky home, he was, at least, no
greenhorn. When he came to the new country where his father was
interested with Frank's in mining ventures, Bob had brought his favorite
Kentucky horse, a coal-black stallion known as "Domino," and which vied
with Frank's native "Buckskin" in good qualities.

These two lads were so much abroad on horseback that they had become
known as the "Saddle Boys." They loved nothing better than to ride the
plains, mounted on their pet steeds, and go almost everywhere the
passing whim tempted them.

Of course, in that wonderland there was always a chance for adventure
when one did much wandering; and that Frank and Bob saw their share of
excitement can be readily understood. Some of the strange things that
happened to them have already been narrated in the first volume of this
series, "The Saddle Boys of the Rockies, Or, Lost on Thunder Mountain,"
and which, in a way, is an introduction to the present story. In the
first book the boys cleared up a wonderful mystery concerning a great
cavern.

For several minutes Bob was busily engaged with the saddle girth that
had been giving him considerable trouble on this gallop.

"There," he remarked, finally, throwing down the flap as though
satisfied with his work. "I reckon I've got it fixed now so that it will
hold through the day; but I need a new girth, and when we pull up again
at Circle Ranch I'll see about getting it. Oh! did you make out anything
with the glasses, Frank?"

He sprang into the saddle like one who had spent much of his time on
horseback. Domino curvetted and pranced a little, being still full of
mettle and spirits; but a very firm hand held him in.

"Take the glass, and see if you can make out what it is," Frank
remarked, as if he hardly knew himself, or felt like trusting his eyes.

A minute later Bob lowered the glasses.

"There's something on the ground, and I can catch a glimpse of what
looks like a dun-colored hide through the tufts of buffalo grass. The
yearling was red, you said, Frank? All right. Then I reckon we'll find
her there; but not on her feet."

"Come on!"

As he said these curt words Frank let Buckskin have his head; and,
accompanied by his chum, started at a full gallop over the level, in the
direction of the spot where the dun-colored object had been sighted.

Shortly afterward