Mark's in
the canoe for the mail, allowed to take their guns and fishing-tackle
with them, and given permission to stay out as long as they chose,
provided they came home before dark. Sometimes Ruth was allowed to go
with them, greatly to her delight, for she was very fond of fishing,
and always succeeded in catching her full share. While the boys were
thus absent, Mr. Elmer took charge of whatever work Mark might have
been doing, and Jan always managed to be within sound of the ferry-horn.

On one of their first trips down the river Mark had called Frank's
attention to the head of a small animal that was rapidly swimming in
the water close under an overhanging bank, and asked him what it was.

For answer Frank said, "Sh!" carefully laid down his paddle, and taking
up the rifle, fired a hasty and unsuccessful shot at the creature,
which dived at the flash, and was seen no more.

"What was it?" asked Mark.

"An otter," answered Frank, "and his skin would be worth five dollars
in Tallahassee."

"My!" exclaimed Mark, "is that so? Why can't we catch some, and sell
the skins?"

"We could if we only had some traps."

"What kind of traps?"

"Double-spring steel are the best."

"I'm going to buy some, first chance I get," said Mark; "and if you'll
show me how to set 'em, and how to skin the otters and dress the skins,
and help do the work, we'll go halves on all we make."

Frank had agreed to this; and when Mark went to Tallahassee he bought
six of the best steel traps he could find. These had been carefully set
in likely places along the river, baited with fresh fish, and visited
regularly by one or the other of the boys twice a day. At first they
had been very successful, as was shown by the ten fine otter-skins
carefully stretched over small boards cut for the purpose, and drying
in the workshop; but then, their good fortune seemed to desert them.

As the season advanced, and the weather grew warmer, they began
frequently to find their traps sprung, but empty, or containing only
the foot of an otter. At first they thought the captives had gnawed off
their own feet in order to escape; but when, only the day before the
one with which this chapter opens, they had found in one of the traps
the head of an otter minus its body, this theory had to be abandoned.

"I never heard of an otter's gnawing off his own head," said Frank, as
he examined the grinning trophy he had just taken from the trap, "and I
don't believe