THE joy of Bob and Joe at seeing the naturalists was certainly great. After those strenuous weeks in the mountains, the youths had been growing anxious to be with their fathers and Mr. Wallace again. Now, as they viewed the men waving at them from below they were overly anxious to land.

There was a wide open place directly under them, and to this Karl sent the monoplane. When finally it came to a stop, Bob and Joe dashed out and ran to meet their fathers and the scientist from Chicago.

“Boys!” cried Mr. Holton, too joyful for words.

He and Joe’s father and Mr. Wallace fairly ate the youths up in their happiness at seeing them alive and well.

“You came through all right, I see,” laughed Mr. Lewis, after the first few remarks were over. “What kind of a time did you have? And the treasure—did you find any?”

“Look,” returned Joe and showed them the box of gold beads.

The men cried out in astonishment. Unlike Karl Sutman, they had expected the youths to return without having found anything of value.

“You were successful, all right,” observed Mr. Holton. “Tell us about your adventures.”

While the men listened intently, the boys related their experiences from the time they had left Cuzco with Dr. Rander.

When at last they were finished, the naturalists shook their heads gravely.

“It was all very interesting, but at the same time it was dangerous,” said Bob’s father solemnly. “Afterward we wished you fellows hadn’t gone.”

“But they came through all right—and brought us a white condor at that,” beamed Mr. Lewis. “No doubt this is the only condor real we’ll see. We did shoot two of the more common kind, though.”

“Did you get many specimens?” inquired Bob.

“Come and see for yourselves,” smiled his father and led the way to the naturalists’ camp.

“Great Scott!” cried Joe, surprised at seeing such a vast number of wild animals and birds. “This region must teem with all sorts of animal life.”

“It does,” returned Mr. Wallace. “And that reminds me. We were going out in search of a black ‘spectacled’ bear this afternoon. We’d like to have you go with us, if you will.”

“Will we?” cried Joe. “Does a cat miaow?”

The naturalists had everything in readiness for the bear hunt. They had but to eat a lunch and then they would be ready to start the hunt.

Mr. Lewis had heard reports from natives that one of the huge animals had been seen in a dense woodland beside the river. To this spot the party went, rifles in readiness.

When they entered the jungle they were met with total surprise. Beside an opening in the hillside was the bear, crouching low for a charge!

There was only a moment to act.

“Shoot!” cried Joe fearfully. His rifle had been dashed from his grasp by a protruding tree bough.

Bob had taken a position a number of yards from the others. He had intended to search another part of the jungle. The youth was holding his gun in readiness now, looking for a chance to take aim.

Then he thought the time had come to fire, and pulled the trigger.

Bang! The rifle spoke, but the bear had suddenly turned, and the bullet missed.

With a snort of rage the huge beast turned on Bob, showing its terrible teeth savagely.

Bob saw the danger and was hurriedly trying to work the bolt on his rifle. But unfortunately the mechanism had jammed.

Helpless, the youth would be at the mercy of those terrible teeth and claws! Already he could imagine the horror of what would follow.

Bang! Bang! Two rifles barked, and each bullet found its mark. Another shot and the huge bear fell dead, almost at Bob’s feet.

“Whew!” gasped Karl Sutman, holding his smoking rifle. “Another narrow escape to add to you fellows’ already long list.”

“We’re piling ’em up thick and fast,” said Bob. He could laugh, now that the danger was over.

They made their way back to camp, after having cut off the great skin. It was at once placed in preservative.

“One more prize specimen to add to our collection,” said Mr. Wallace. “I’m betting that Bob and Joe will prove a valuable asset to the expedition during the next few weeks. They’re both good shots, and they have plenty of courage.”

Indeed the youths tried to justify themselves of this tribute, and were successful in doing so. During the eventful days that followed they collected many specimens for the scientists, including about every form of life they could see in this wild region. Often they made long excursions into the adjoining mountains in search of new wild creatures, and usually found them. Taking moving pictures also occupied their time.

But although the naturalist party was meeting with success in its search for fauna, the men did not wish to remain here too long, for other duties at home prevented it. Especially was Mr. Wallace anxious to get back to Chicago.

It was arranged one day that he and Bob and Joe go with Karl Sutman in the monoplane back to the United States, preceding Mr. Holton and Mr. Lewis, who would arrive later by steamship. The youths’ fathers took it on themselves to attend to getting the specimens on muleback to the coast, where they would be loaded on the vessel.

The four leavetakers were given an affectionate farewell by Mr. Holton and Mr. Lewis, who expressed hope that their sons and friends would arrive in the United States without mishap.

On the way to the coast the air travelers stopped to see Dr. Rust and others of the archÆologist party. Bob informed them of the Inca secrets he and his friend had found, and gave them the map he had made of the region. The scientists’ delight far exceeded the boys’ expectations. They literally mauled the youths in their intense enthusiasm.

When the chums, Mr. Wallace, and Karl climbed into the cabin, the scientists gave them a royal send-off, wishing them a safe journey.

And safe it proved to be. Karl’s ability as a pilot was greatly appreciated as they flew toward the United States, which they reached without incident.

“Now to get home,” said Bob, as he and Joe and Mr. Wallace hailed a taxi. The naturalist intended to spend another day or so with the boys before boarding a train to Chicago. Karl Sutman left them at the airport, promising to get in touch with them within the next few days.

At their homes Bob and Joe and their friend were given a profound welcome by Mrs. Holton and Mrs. Lewis, who were desirous of knowing about their experience.

“We had a wonderful time,” said Joe, as they all sat in the Lewis living room. “And we met with adventures aplenty. There’s nothing quite like exploration, especially when you’re looking for ancient secrets.”