The Indians seemed glad to leave the “place of the bats,” as they called the camp site.  Jacinto explained that the Indians believed a vampire could kill them while they slept, and they were very much afraid of the blood-sucking bats.  There were many other species in the tropics, Professor Bumper explained, most of which lived on fruit or on insects they caught.  The blood-sucking bats were comparatively few, and the migratory sort fewer still.

“Well, we’re on our way once more,” remarked Tom as again they were in the canoes being paddled up the river.  “How much longer does your water trip take, Professor?”

“I hardly know,” and Professor Bumper looked to Jacinto to answer.

“We go two more days in the canoes,” the guide answered, “and then we shall find the mules waiting for us at a place called Hidjio.  From then on we travel by land until—­well until you get to the place where you are going.

“I suppose you know where it is?” he added, nodding toward the professor.  “I am leaving that part to you.”

“Oh, I have a map, showing where I want to begin some excavations,” was the answer.  “We must first go to Copan and see what arrangements we can make for laborers.  After that—­well, we shall trust to luck for what we shall find.”

“There are said to be many curious things,” went on Jacinto, speaking as though he had no interest.  “You have mentioned buried cities.  Have you thought what may be in them—­great heathen temples, idols, perhaps?”

For a moment none of the professor’s companions spoke.  It was as though Jacinto had tried to get some information.  Finally the scientist said: 

“Oh, yes, we may find an idol.  I understand the ancient people, who were here long before the Spaniards came, worshiped idols.  But we shall take whatever antiquities we find.”

“Huh!” grunted Jacinto, and then he called to the paddlers to increase their strokes.

The journey up the river was not very eventful.  Many alligators were seen, and Tom and Ned shot several with the electric rifle.  Toward the close of the third day’s travel there was a cry from one of the rear boats, and an alarm of a man having fallen overboard was given.

Tom turned in time to see the poor fellow’s struggles, and at the same time there was a swirl in the water and a black object shot forward.

“An alligator is after him!” yelled Ned.

“I see,” observed Tom calmly.  “Hand me the rifle, Ned.”

Tom took quick aim and pulled the trigger.  The explosive electric bullet went true to its mark, and the great animal turned over in a death struggle.  But the river was filled with them, and no sooner had the one nearest the unfortunate Indian been disposed of than another made a dash for the man.

There was a wild scream of agony and then a dark arm shot up above the red foam.  The waters seethed and bubbled as the alligators fought under it for possession of the paddler.  Tom fired bullet after bullet from his wonderful rifle into the spot, but though he killed some of the alligators this did not save the man’s life.  His body was not seen again, though search was made for it.