ON the bank not far away were at least fifteen large alligators, their hideous jaws partly open as they basked in the hot sun. Frequently one would plunge into the water to cool itself, and then there would be a terrific splashing about.

As soon as possible, the Indians stopped the boats, and the explorers viewed the creatures with a terrible awe. Here was their first encounter with the wild life of Brazil. Here, not far away, were some of the most terrible reptiles of South America.

For some time the alligators did not seem to notice the human invaders. Then they one by one crawled off the bank and sank a few inches beneath the water.

“Evidently don’t care for our company,” said Joe in a low tone. He had brought the movie camera to his shoulder and was taking in the unusual sight.

It was thought best not shoot any of the reptiles for fear of causing an undue commotion. Then, too, it would prove difficult to get the victims in the boat with so many others around.

In a short time no traces of the creatures were left, and the Indians again turned to the paddles.

“Is it safe to go on?” asked Joe.

“Yes,” the professor replied. “They probably won’t attack the boats. And if they should they could do little or no damage to the stout hulls.”

For a few seconds he conversed with the Indians. Then the party resumed the journey, keeping a close watch about.

No more was seen of the alligators, and the explorers again were quiet. But now they were more anxious than ever before, for the past experience had stirred their sporting blood and made them long for a jaunt in the forest. Even Professor Bigelow was affected, and he sat fingering his rifle as if awaiting another such incident.

“Alligators and crocodiles are very much alike,” said Mr. Lewis, wishing to break the silence. “The only difference is in the canine teeth. In the alligator they fit into pits in the upper jaw; in the crocodile they fit into notches. Otherwise they look alike.”

“Which is the most ferocious?” inquired Joe, thoroughly interested.

“Scarcely any difference,” his father returned. “Both are bad enough when they’re after you.”

For a time the adventurers paddled near the center of the river, in order to avoid heavy piles of brush that lay near the shore’s edge. They did not feel like talking. The mid-afternoon sun beat down upon them until they were dripping with perspiration. Why, even summer Florida weather was nothing to this!

The water glistened like silver. It was almost impossible even to cast eyes upon it, for the reflection of the sun was extremely blinding.

For entertainment and amusement the boys’ fathers and Professor Bigelow related some of their experiences, which Bob and Joe never grew tired of hearing. The naturalists told of encounters with wild animals; the professor, of savage people. Bob and Joe sat in silence, marveling that before long they could tell of happenings probably as much or more breath-taking.

Suddenly, as they neared a patch of bright red bushes, Mr. Holton called to the Indians to stop the boat.

“What is it?” asked Bob, and then his gaze followed that of his father.

Not far away on a low branch was a large oriole, almost the size of a crow, with a red and white bill, and yellow, green, and brown plumage. It uttered not a word, although no one doubted that it could.

“We must have that bird,” whispered Mr. Holton. “It is rather rare, and few of them are in museums. Keep quiet now, while I get a small gun.”

The others obeyed. The naturalist found a suitable shotgun. He raised it to his shoulder, took careful aim, and pulled the trigger.

The next moment there was a terrible screeching and wailing. The bird fluttered about for a brief second, then fell into the water.

“You got him,” said Bob joyously. “You——Well, of all things!”

The reason for his exclamation was not far to seek. No sooner had the bird struck the water than a rather small fish darted to the surface, caught the bird by the breast, and bit it in two. It evidently did not like the taste, however, for the remains of the bird’s body were left to float on the water.

“Stung!” exclaimed Mr. Holton, regaining his breath. “The piranhas spoiled the chance of getting that specimen.”

“So that fish was a piranha?” asked Joe, looking to see if he could locate it in the dark water.

“Yes,” Mr. Lewis returned. “They’re mean creatures, all right. Got a temper like a bull. They’ll attack anything from jaguars to people, and they usually do the job right. I once heard of a man devoured by them in a very short time.”

“It wasn’t very large,” said Bob. “Looked about like a pickerel to me.”

“It isn’t their size,” his father returned. “It’s their ferocity—and strong, sharp teeth.”

“Let’s don’t worry about the bird,” consoled the professor. “We’ll probably see more of them later on.”

The naturalists resolved to follow the professor’s advice and regard the matter as one of the many discouragements that could be expected at almost any time.

“After all, we didn’t lose much,” said Mr. Lewis. “But then—but then——”

As they paddled on, signs of life became more frequent. Once there was a small flock of bright red birds, and the naturalists had more luck in bringing them in as specimens. None was shot near the river; only those on shore were aimed at. A little later they saw the first monkeys since they had turned down this river. They had often heard the little creatures in the depths of the jungle, but had never been successful in getting a glimpse of them.

Along toward evening Mr. Lewis suggested that they go ashore and pitch camp for the night. His friends agreed, and after making sure that the Indians were willing, he gave the word and the boats were turned into a little cove, where they were tied to a stout tree.

“Plenty of room around here,” observed Bob, as he got out and stretched his legs. “No trees within a radius of several score feet. Ought to be fairly good protection against night marauders.”

The tents and poles were untied, and after locating a suitable site the stakes were driven to the ground, the poles hoisted, and the hammocks hung.

Then a bountiful supper was prepared, and the party ate hungrily. Bob and Joe especially partook of large quantities, for their appetites were those of youth.

After the meal the explorers sat in a group, chatting merrily. Even the Indians took part in the conversation, answering many of the whites’ questions about the jungles they were passing through. Bob and Joe had trouble in understanding them, but their fathers translated whenever there was any difficulty.

A little later, darkness fell suddenly, and with it came the chill of night.

“Seems strange that the nights should be so cool when the days are so hot,” remarked Bob, going into the tent for a coat.

“Does at that,” said Mr. Lewis. “But it’s true of all tropical places.”

Soon the sky became dotted with countless numbers of twinkling stars. Soon afterwards the moon came out in full splendor, flooding the boundless expanse with enchanting light, and casting a reflection on the water beautiful beyond description.

The explorers were filled with awe as they sat staring into the vast jungle, thrilled that they were the only inhabitants on this wild shore.

For some time no one spoke. Then Mr. Holton rose and looked at his watch.

“Getting late,” he said, walking over to a box of supplies.

“Yes,” agreed Professor Bigelow. “I suggest that we turn in.”

The others agreed, and they attended to last-minute tasks.

“Ordinarily it is the Indians’ duty to stand guard,” said Mr. Lewis, glancing at the brawny crew, several of whom had fallen asleep. “But since they’ve worked hard and unflinchingly, and are nearly worn out, I suggest that we whites take turn about on this first night. We’ve had it comparatively easy all day. Then, too, it will increase their respect and liking for us. What do you think?”

“I’m all for it,” declared Professor Bigelow. “Now who is to have the first watch?”

It was decided to draw straws, the person getting the shortest to be the first guard.

By chance the short piece fell to Bob, and he took his place just outside the tents, sitting on one of the boxes, a rifle in ready grasp. The others retired to their hammocks.

For over a half-hour Bob stared quietly into space, glancing occasionally at the sparkling river. Then he decided to change his position.

But at that moment there came a crashing sound on the far side of a group of palm trees.

The youth was on his feet at the instant, wondering what the noise meant. Then he decided to find out.

“It’s only a short distance from camp,” he thought. “There’s no harm in going over there.”

Grasping his rifle, he stole quietly in the direction of the strange commotion.

It did not take him long to reach the patch of trees. Then he wormed his way through the tall grass for a distance of perhaps twenty feet.

The next instant he shrank back, for the sight that met his eyes was fearful and repulsive.