“WHAT is it?” cried Joe, as he noticed the look of anxiety on his chum’s face.

For answer, Bob pointed to the wild boar, and as Joe glanced around he shrank back in consternation.

“Quick!” he cried. “It’s going to charge!”

There was no time to lose. The animal, angered because cornered, was getting ready to stand its ground savagely. And the boys had heard of the wild boar’s terrible ferocity.

Almost in unison the youths raised their rifles and took careful aim. The guns were of only twenty-two caliber, not any too powerful for the occasion, but the chance had to be taken.

“Now,” murmured Bob, holding his rifle in a steady position.

Bang! Bang! Two shots rang out, and each found the mark.

But the small bullets did not stop the beast’s charge, and it came on with horrible atrocity.

“Run!” cried Bob, his nerve completely gone. “Let’s go up a tree!”

As the youths darted to one side, a shot rang out; another; and still another. A moment later the wild boar sank to the ground in a crumpled mass, gave a convulsive twitch, and then lay still.

Mr. Lewis and Mr. Holton came running up, on their faces a look of apprehension.

“A narrow escape!” said Joe grimly. “It’s a good thing you came across with those high-speed bullets. They sure did the job, all right.”

“We just happened to glance around in time,” explained his father. “We didn’t know you boys were so far behind. Why didn’t you bring larger rifles?”

“Weren’t expecting to meet such a creature as this,” replied Bob. “I had an idea that this was a tame country, but I see I’m wrong,” with a glance at the wild boar.

“You certainly are,” smiled Mr. Holton, shaking his head. “And this incident may be the beginning of a series of adventures with wild animals. Where there’s one of a thing there’s likely to be another. So stick close, boys. I’d hate to have to rely on those twenty-twos again.”

The wild boar was shattered by the bullets and was no good as a specimen. The naturalists especially wanted one of these terrible beasts and were put out to think that this one had been made worthless by the rifles, but they were thankful that they had been able to come to the rescue of their sons.

With one last look at the creature they resumed the hike, this time keeping a closer lookout for any other formidable beast.

As they penetrated deeper into the forest, signs of life began to increase in numbers. Small rodents darted out, only to be brought down by the guns of the naturalists; lizards of grotesque and ugly shapes were all about; birds of many colors flew overhead, their plumage showing brightly in the sunlight. It was a sight that the youths never grew tired of.

Suddenly a jackal ran out, and Mr. Holton lost no time in firing at it. It was carefully but quickly skinned and placed in the burlap bag for the specimens.

“This forest certainly is untrodden,” observed Mr. Lewis, unable to discern the faintest traces of human tracks. “It has probably been a long time since anyone broke into its fastness.”

“Which is all the better for us,” said Joe. “Animals here probably have never heard the sound of a gun before.”

Along toward noon they picked out a small grassy area and got out the kit of lunch. The sandwiches were spread on a paper, and thermos bottles of cold lemonade were opened. To the tired adventurers it promised to be a feast fit for a king.

“No meal in the most luxurious cafÉ tastes better than a bountiful lunch in the heart of a forest,” said Mr. Lewis.

Bob’s father nodded.

“It has been said that no one but an explorer really knows what an appetite is,” he remarked. “And in times when I’m working in the museum at home and not doing any strenuous work I can fully realize the truth of it.”

They ate the lunch in quiet contentment, taking it easy on the soft grass. It seemed good to be out on the trail again, feasting on the wonders of nature. Bob and Joe were impressed by the stillness of the great forest.

“This is about the only kind of a woods you can get through,” remarked Bob, his eyes on the numerous cork-oak trees. “A tropical jungle has so much undergrowth and vines that it keeps you busy cutting them away with a machete.”

An hour or two after the repast was spent in resting their tired limbs and chatting merrily. Then Mr. Lewis suggested that they continue the hunt.

“We won’t have so very much time left,” he said. “And we’d like to get several more specimens.”

A little later they came to a narrow valley between two high mountains. A tiny spring trickled from beside a large rock, and they welcomed the taste of the refreshing liquid. It was quite cold, showing that it probably came from an underground stream.

“Drink all you want,” said Mr. Lewis. “It’s likely the last water we’ll see till we get back to Arba.”

All the remainder of that afternoon the explorers trudged on, bringing down several small animals and birds. None of them happened to be dangerous, however.

The hunters had described a wide circle that took them by sundown within a mile or two from Arba, and the accuracy of the naturalists’ calculations was greatly appreciated, for they were very tired and did not feel that they would care to have to hike a great distance to get to the automobile.

“Wonder if the old car’s still there,” mused Bob, as they came to the limits of Arba.

“Don’t know why it shouldn’t be,” returned his chum. “Nobody’d want it for anything.”

It required but a short time to reach the main part of the town. Then they turned off on the street where the car was parked.

“It’s there!” cried Joe, making out its ancient shape in the distance.

The others shared in his enthusiasm. They had had an uneasy feeling about its safety all day, despite the fact that the ignition had been locked.

In a short time the explorers were in the seats, and Joe, who had asked to drive, began the task of starting the engine. It finally responded to the sluggish self-starter.

“Now let’s hurry and get back to Algiers,” urged Mr. Holton. “We don’t want to be out after dark, for there’s no telling how good these lights are.”

During the next half-hour Joe pulled the throttle as far down as possible, and then complained because he could only do forty-five. However, it was not long before they saw the lights of Algiers in the distance.

“Now to get something to eat,” said Mr. Holton, sitting up in the seat in anticipation. “It will be good to see the old hotel again, won’t it?”

“Sure will,” replied Bob. “I’ll bet Dr. Kirshner expected us long before this.”

“He’s probably conversing with Fekmah,” was the opinion expressed by Mr. Lewis. “You know,” he went on, “that Arab is a strange contrast to these worthless fellows around here. It all goes to show what anyone can do if he wants to.”

“He’s educated, too, isn’t he?” inquired Joe.

“Yes, highly,” the naturalist replied. “Was graduated from the University of Algiers and received a degree. What he doesn’t know isn’t worth knowing.”

“Where is his home?” asked Bob. “He doesn’t live in Algiers, does he?”

“No. He lives in Oran; that’s about a hundred and twenty-five miles or so west of here. Quite a prosperous city, I guess.”

“But,” questioned Bob, thoroughly puzzled, “what is he doing here in Algiers?”

“It all goes back to Dr. Kirshner’s conversation with him on the ship,” Mr. Holton explained. “You see, Tom”—referring to the archÆologist—“met him on the last day of the voyage and recognized him to be a very intellectual man. As soon as Fekmah found that he could trust Kirshner, he confided this secret about the hidden riches. Well, then, when he found that we would accept his proposition and make it one of the objects of the expedition to search for this treasure, Fekmah put up at a hotel in Algiers in order to accompany us into the Sahara. See?”

“Sure. I don’t know now why I didn’t before.”

They were now among the lights of Algiers, and Joe headed straight for the business section, where the car was to be returned to the garage.

They reached the place in a short time and left the automobile. Then they hurried around to their hotel.

When they came to their room, they found Dr. Kirshner and Fekmah in earnest conversation. When the two heard their friends in the hall, they arose, wreathed in smiles.

“We have good news for you,” announced Dr. Kirshner joyously. “The train is leaving for Wargla in the morning.”