."]

"But, Captain," answered Vigilant, "we have searched for the guard, and
can't find him. No one has seen him off his rounds. Indeed, he was seen
at his post by the nearest sentinel but a few moments before the relief
came up. Here is his spear, which was picked up on the ground.
Otherwise there is not a trace of him anywhere."

"Remarkable indeed! Who was the sentinel?"

"Private Standwhile."

"Ah, a good man and true! I know him well. Lead the way to his picket
post."

The two were soon upon the ground. The spot where the missing soldier's
lance was found was carefully examined, but there was no trace of
conflict or other unusual occurrence. The approaches to the picket line
from the enemy's direction were closely scanned. Nothing suspicious was
seen. The ground for some distance between the Pixie and Brownie camps
was at this point flat and smooth. Unable to solve the mystery, the
Captain ordered another sentinel to be placed.

"See that he is a good man, one of the brightest and most careful in the
ranks," said Bruce. Accordingly Sergeant Vigilant assigned Private
Sharpsight to the vacant post.

"And, be sure, Sergeant," said the Captain, as he turned away, "that you
keep a bright lookout upon your sentinels during the watch, especially
on this one."

Scarcely an hour had passed ere Captain Bruce heard the sharp challenge
of the sentinel before his tent door: "Who goes there?"

"Sergeant Vigilant of the picket guard."

Bruce rose from his couch without waiting to be called, and left the
tent. "Well, what is it? Speak!"

"The second sentinel is gone!"

"Sharpsight gone?"

"Aye; not a sign or sound of him anywhere. I visited the picket once
within an hour after he was stationed. All was then well. But I felt
restless and nervous about the disappearance of Standwhile, and a few
moments ago returned. Sharpsight had vanished as mysteriously as the
other!"

"Call out the guard!" cried Bruce, snatching his broadsword and striding
off toward the picket line. "Keep this matter as quiet as possible. It
won't do to alarm the camp."

[Illustration: FIG. 111.--"The Horizontal Snare of a Young Uloborus
Among the Laurels."]

Every bush, and clump of grass, weed, stone, stock, or other place that
could possibly give shelter to friend or foe, Brownie or Pixie, within a
wide circuit of the fatal picket post, was thoroughly explored. Nothing
more dangerous was found than the horizontal snare of a young Uloboru