“Look out!” yelled Ned.  “If it’s a vampire it’ll——­”

“It won’t do anything to me!” shouted Tom, as he struck the creature, knocking it into the corner of the tent with a thud that told it must be completely stunned, if not killed.  “But what’s it all about, anyhow?” Tom asked.  “What’s the row?”

From without the tent came the Indian cries of: 

“Oshtoo!  Oshtoo!”

Mingled with them were calls of Jacinto, partly in Spanish, partly in the Indian tongue and partly in English.

“It is a raid by vampire bats!” was all Tom and Ned could distinguish.  “We shall have to light fires to keep them away, if we can suc-ceed.  Every one grab up a club and strike hard!”

“Come on!” cried Tom, getting on some clothes by the light of his gleaming electric light which he had set on his cot.

“You’re not going out there, are you?” asked Ned.

“I certainly am!  If there’s a fight I want to be in it, bats or anything else.  Here, you have a light like mine.  Flash it on, and hang it somewhere on yourself.  Then get a club and come on.  The lights will blind the bats, and we can see to hit ’em!”

Tom’s plan seemed to be a good one.  His lamp and Ned’s had small hooks on them, so they could be carried in the upper coat pocket, showing a gleam of light and leaving the hands free for use.

Out of the tents rushed the young men to find Professor Bumper and Mr. Damon before them.  The two men had clubs and were striking about in the half darkness, for now the Indians had set several fires aglow.  And in the gleams, constantly growing brighter as more fuel was piled on, the young inventor and his chum saw a weird sight.

Circling and wheeling about in the camp clearing were many of the black shadowy forms that had caused Ned such alarm.  Great bats they were, and a dangerous species, if Jacinto was to be believed.

The uncanny creatures flew in and out among the trees and tents, now swooping low near the Indians or the travelers.  At such times clubs would be used, often with the effect of killing or stunning the flying pests.  For a time it seemed as if the bats would fairly overwhelm the camp, so many of them were there.  But the increasing lights, and the attacks made by the Indians and the white travelers turned the tide of battle, and, with silent flappings of their soft, velvety wings, the bats flew back to the jungle whence they had emerged.

“We are safe—­for the present!” exclaimed Jacinto with a sigh of relief.

“Do you think they will come back?” asked Tom.

“They may—­there is no telling.”

“Bless my speedometer!” cried Mr. Damon, “If those beasts or birds—­whatever they are—­ come back I’ll go and hide in the river and take my chances with the alligators!”

“The alligators aren’t much worse,” asserted Jacinto with a visible shiver.  “These vampire bats sometimes depopulate a whole village.”