New
plants and shrubbery of various kinds were constantly sought for and
examined--they fished and hunted; and on the morning of the third day it
was decided to move on.

"We have not yet sighted any original inhabitants, and have found no
signs of people living here; nevertheless, we had traces of a fire
thirty or forty miles east of here. That is what puzzles me."

"I am in favor of following this stream to the north," was Harry's
conclusion, "unless we make a raft and cross the river."

Harry's view finally prevailed, and at noon of that day they camped at
the mouth of a little stream which flowed into the West River. Beyond
was a forest, and on the opposite side of the West River the wood had
all along been dense. At that point the trees did not come down to the
stream, and there was considerable lowland between the river and the
forest.

The Professor and George wandered up the banks of the little stream on a
prospecting tour, as had been their constant practice. When they
returned Harry knew something unusual had occurred from the excited
appearance of George.

"What is it? Any animals?"

"No; only this." And George held up an arrow made of flint. The wooden
portion of the arrow was really of good workmanship, and of hard, stiff
wood.

"Where did you find this?"

"Not more than five hundred feet from here."

Harry looked at the Professor for an explanation, but he was silent. By
common consent they now agreed upon making a more extended investigation
of the vicinity for other traces, if possible. Within an hour Harry
stumbled across the skull of an animal. This was not an unusual sight,
as bones had been found at various places in their travels, but here was
a specimen, lying on a rocky slope, with but little vegetation about it.

[Illustration: _Fig. 2 Types of Arrow-Heads._]

"I should like to know what animal this belonged to?"

The Professor examined the bones critically, without venturing an
opinion. "What is this?" were his first words. Directly behind the ear
cavity was a split or broken cleavage in which they found a round piece
of dark wood.

"Get the bolo, George; we may find something interesting here." With a
few strokes the skull was opened, and embedded within the brain
receptacle was an arrow.

"This animal was, as you see, killed by the inhabitants of the island. I
infer that there are several tribes living here."

The boys looked at each other in astonishment.

"Why do you t