se to his feet, took good aim at the animal,
and shot it dead.

The creature fell, flinging the girl headlong.

She struck solidly, and lay still, in a huddled mass upon the ground.

"Hurrah!" cried Frank, seeing the enemy was repulsed. "I fancy they have
had about enough of us."

He hastened to replenish the magazine of his rifle.

Bart's first thought, on seeing the fight was over, was of the girl they
had been defending. He turned and found her safe where she had been
placed behind the large bowlder, but she was still holding her hands
over her ears, and her face was very pale.

Frank sprang outside the rocks, caught up the other girl, and leaped
back quickly, placing her gently on the ground.

"I hope she is not harmed," he said, as he deftly removed the mask.

The moment the girl's face was exposed a shout of amazement broke from
the lips of both lads. They stared first at one girl and then at the
other, looking bewildered.

The girls were almost counterparts of each other!

"They are doubles!" exclaimed Frank. "Taken separately, it would be
impossible to tell one from the other."

Then he turned on the girl they had been defending, stared straight into
her face for a moment, and asked:

"What is your name?"

"Vida Melburn."

"It is not Isa Isban?"

"No, sir."

"Did I not change two fifty-dollar bills for you on the Pacific Express,
shortly after leaving Ogden?"

"I never saw you till this morning."

"That settles it!" cried Frank; "the other girl is Isa Isban, and she is
queen of the counterfeiters. She was the one for whom I changed the
money, and she completely fooled me by her innocent face and manner."

"And I mistook her for Miss Melburn," said Bart. "Such a thing seems
impossible, but it actually occurred."

"But how Miss Melburn came to be here is what I cannot understand,"
asserted Frank.

"I came up to Tahoe with my father, an uncle, and an aunt," said the
girl, who was recovering from her terror. "My uncle and aunt live in
Carson, and father and I were visiting them. We hired a sailboat of a
big hermit who lives somewhere on the shore of the lake, and sailed over
here, coming ashore to have a picnic dinner. The wind went down, and we
could not get back. That evening I took a little stroll from camp, and I
was suddenly seized from behind, nearly smothered in a blanket and
carried away. I was held a captive in a cabin, far up on a high cliff.
Back of the cabin was a cave through