NOT ten feet away, at the point where the trail branched, was a huge mound of earth that must have been at least thirty feet high. It was conical in shape, gradually tapering up to a sharp point.

“What do you call that?” asked Joe, staring in amazement at the formation.

“If I’m not mistaken, it’s an ant hill,” Bob answered, moving closer to the mound of earth. Often Bob had heard of this phenomenon, but until now had not seen it.

“A what? Ant hill? You don’t mean to say that ants built that, do you?”

“I guess they did,” returned Bob. “Dad says ants have been known to heap up the earth to a height of forty feet or more.”

“Of all things!” Joe could hardly believe what his chum said. “How do they do it, anyway?”

“More than I know. They’re busy little creatures, though.”

The boys examined the ant hill with a great deal of curiosity. It seemed almost incredible that ants could construct such a huge piece of architecture. Why, it must have required the efforts of tens of thousands of the little creatures!

But although greatly interested, Bob and Joe did not spend too much time here, for they desired to explore a bit longer before returning to the safari.

Everywhere they went they saw brilliantly colored birds, which often fluttered so near that the youths could almost touch them. Luxuriant flowers were also in abundance.

The chums trekked on for a distance of perhaps a half mile, then turned back toward the expedition. When they reached the clearing, they found Mr. Lewis and Mr. Holton ready to continue the journey.

“See anything of interest, boys?” inquired the latter, signaling to Noko to lead the way.

“Plenty,” returned Joe. “An ant hill, for one thing. And was it a whopper! Must have been thirty feet if an inch.”

“That was only a taste,” grinned Mr. Lewis, with a wink at Bob’s father. “Howard and I have often seen them forty feet or more.”

As they penetrated deeper into the jungle, the vegetation became denser and consequently more difficult to pass through. Often the sun was entirely hidden from view by the thick canopy of foliage above, and the explorers found themselves in a sort of twilight. At other times they would emerge from the leafy depths and make their way over wide plains under the fierce tropical sun.

But despite many difficulties of the trail, the expedition made good time and by night had covered a good many miles. They camped beside a narrow, winding stream, which looked as if it were several yards deep.

“Bet there’s fish in there,” remarked Joe, peering into the dark water of the stream.

Noko overheard the remark and understood.

“Um big fish dare,” the native said, his eyes following those of Joe. “Dey good eat.”

“That’s an idea,” mused Bob. “Why not try our luck at fishing?”

“Sure.” Joe was more than willing.

The youths got out their tackle and fashioned crude poles out of tree branches. Then, sitting a short distance apart on the bank, they waited silently, while the naturalists looked on with interest.

Suddenly, when it had been in the water but a few minutes, Joe’s float was drawn completely under the water with such force that the pole was almost snatched out of the youth’s hands.

“Pull!” exclaimed Bob in a loud whisper.

Joe obeyed, but found that to do this was harder than he had anticipated. But with the aid of his chum the catch was drawn out easily.

All uttered startled exclamations at sight of it.

“A tiger fish,” pronounced Mr. Lewis. “Only a small one, though.”

“Small one?” cried Joe, wheeling about. “What are you talking about, Dad? Bet that fish weighs ten pounds!”

“Maybe so,” Mr. Lewis returned. “But it isn’t uncommon to catch tiger fish that weigh as much as twenty pounds. In fact, Howard hooked one in the Zambezi River that tipped the scales at forty-two.”

“No!” Bob and Joe both looked up in amazement.

“That’s right,” vouched Mr. Holton. “It was the biggest I’ve ever caught.”

During the next fifteen minutes Joe caught four more of the big fish, none, however, being as large as the first one. Then, using the knowledge gained on other exploration ventures, he dressed them and placed them over the fire.

“Doggone the luck!” growled Bob. “I didn’t get a single bite. This big bum here walks off with a whole river full.”

“Cheer up,” consoled Mr. Holton. “You can at least share the eating of them.”

“Yeah,” put in Joe. “You can take a whiff at them.”

The tiger fish proved good eating and were a welcome addition to the usual menu.

“And now,” began Mr. Lewis, stretching out to retire after two hours of chatting, “we’d better get to sleep. Noko says we’ll run into a native village tomorrow. That may delay us for a while.”

Shortly before noon of the next day the explorers heard a chorus of shouts and yells, which came from around a bend, and they soon found themselves facing a large group of natives.

Noko at once fell into conversation with the chief, with whom he was well acquainted. They talked for several minutes, and in the end the chief motioned for the safari to follow him into the village.

That village the two youths found very interesting. It was made up of several rows of thatched huts, about which sat natives dozing or conversing. Apparently there was no work being done, the natives probably resting to escape the terrible heat of the sun.

The chief escorted the safari to his own huge hut, where he asked that they remain for a while. The bearers were glad to do as requested, so as to get out of the fierce heat. And as Mr. Holton and Mr. Lewis were also reluctant to continue the journey at this time of day, they also consented.

Both the naturalists had picked up a good knowledge of the native language on their frequent trips to Africa and so had no difficulty in taking part in the conversation. They translated occasionally to Bob and Joe.

During the course of the talk the chief mentioned something that was of great interest to Mr. Lewis and Mr. Holton, and also to the chums. The section around the village was being made unsafe for hunting by a huge, bad-tempered buffalo which would charge any of the natives on sight. One man had been killed and two others severely wounded by the beast, and although numerous parties had set out to kill it, they had so far been unsuccessful in doing so. For some reason the animal never would wander far from a certain spot near a stream. So dangerous was the buffalo that the villagers were afraid to go to the stream to get water and had to follow a roundabout trail.

When the chief had finished, Mr. Lewis spoke up at once.

“We”—indicating Mr. Holton, the youths, and himself—“will make a special effort to kill that buffalo,” he told the chief in the native tongue. “We would like to kill the animal and take it back to our own country to show the people. Will you help us?”

The head native was delighted. Certainly he would help. If the bad animal could be killed, he would be very grateful to the whites, and would present them with several wild animal skins.

“It is agreed, then,” Mr. Holton said to the chief. “We will set out this afternoon.”

“This is going to be good,” mused Bob, giving his chum a nudge in the ribs.