"_They are after us!_" gasped one of the girls in terror. "Quick, Naida!

Quick! Quick!"

Whatever it was that threatened, Naida did not need to be told that the need for action was pressing. She shouted at her companions some order which Kirby did not understand. From a pouch at her side, she s.n.a.t.c.hed out a greyish, spherical vegetable substance which looked almost like a tennis ball. Then she braced herself as if to withstand an a.s.sault.

"Stand back!" she cried to Kirby.

He had long ago ceased to wonder at anything that might happen here.

Disappointed that Naida's story had been interrupted, wondering what was wrong, he obeyed Naida's order to keep clear.

As he fell back and stood motionless, there came from behind a dense screen of shrubs which would have resembled aloe and p.r.i.c.kly pear bushes, save that they were as big as oak trees, a ghastly howling. The next second, hopped and hurtled across the beach toward the girls, a group of hair-covered, s.h.a.ggy creatures which were neither apes nor men.

The faces, contorted with l.u.s.t, were hideously leathery and brown, the foreheads small and beetling, and the mouths enormous, with immense yellow teeth.

Helpless, Kirby realized that Naida and all the others had clapped over their faces curious masks which seemed to be made of some crystalline substance, and that now others had armed themselves with the tennis b.a.l.l.s. And that was the last observation he made before the battle opened furiously.

With a cry m.u.f.fled behind her mask, Naida leaped out in front of her squadron and cut loose her queer vegetable ball with whizzing aim and force.

Full into the snarling face of one of the ape-men the thing smashed, filling the air all about the creature with a yellow, mistlike powder.

Kirby was half deafened by the yells of rage and terror which went up from the entire attacking band. The creature who had been hit fell to his knees the while he made agonized tearing movements at his face and uttered shrill, jabbering yelps.

Other b.a.l.l.s flashed instantly from Naida's ranks, and each brought about the same ghastly result as the first. But then Kirby saw that the whole jungle seethed with the hairy, awful men.

"Keep back!" Naida shrieked at him through her mask. "We have no mask for you. If the powder from our fungi touches you, it will be the end!"

With gaps in the advancing line filled as soon as each screeching ape went down, the attackers leaped on until Kirby knew they would be upon the girls in a matter of seconds. A sweat broke out on his neck.

But then an idea gripped him, and suddenly, without even a last glance at Naida, he leaped away even as she had commanded.

A great boulder lay on the sh.o.r.e fifty yards away. Toward it Kirby streaked as though he had become coward. But he had not turned coward.

By the time he reached the shelter which would protect him from the fungus mist, a turning point had come in the battle. The ape-men had closed in on the girls, were swarming about them, and the mist b.a.l.l.s had almost ceased to fly. But the thing which gave Kirby hope was that the apes were not attempting to harm the girls. They seemed victors, but they were not committing atrocities.

It was the sharp intuition that something like this might happen which had sent Kirby fleeing from the fight. He believed he might yet prove useful.

The thickest group of attackers were jostling about Naida. As the screams and sobs of the girls quivered out, mingled with the guttural roaring of the men, Naida was shut off by a solid wall of aggressors.

Then Kirby saw her again. But now two of the most powerful of the ape-men had caught her up and was carrying her. Her kicking and writhing and biting accomplished nothing. The apes were headed directly back to the jungle.

Now, however, most of the yellow mist had disappeared, and that was all Kirby had been waiting for. With a growling shout, he tore out from behind his boulder, his Luger ready. Naida's captors were in full retreat, and other pairs of men were s.n.a.t.c.hing up other girls and hopping after them. Toward Naida Kirby ran madly but not blindly.

"Naida! Naida!" he bellowed.

He got in two strides for every one the apes made.

"Naida!" he shouted, and at last saw her look at him.

Her face was pallid with loathing and terror. As her glimmering dark eyes met his, they flashed a plea which made his heart thrash against his lungs.

With a final roar of encouragement Kirby closed in on the hair-covered men, and fired instantly a shot which caught one full in the heart. The creature wavered on its legs, looked at the unexpected enemy with dismayed, swinish little red eyes, and relaxing his hold upon Naida, dropped without making a sound.

After that--

But suddenly Kirby found himself unable to comprehend fully the other terrific results of his intervention. Before the echoes of his shot died, there came to him the rumble of what seemed to be tons of falling rock. In the bright air a slight mist was precipitated. To all of which was added the effect upon the ape-men of fear of a weapon and a type of fighter utterly new to them.

Kirby had fired believing that he would have to fight other ape-men when the first fell. But not so. Instead of that--

He blinked rapidly as he took in the scene.

Naida had been released. Lying on the sand beside the dead ape-man, she was looking up at him in stupefied wonder. And her other captor, instead of remaining to fight, had clapped s.h.a.ggy hands over his ears, and was leaping headlong for the protection of the jungle!

Moreover, the soprano cries of the girls and the deep howls of the men were rising everywhere, and everywhere the ape-men were dropping their captives and plunging away after their leader.

"Huh," Kirby muttered aloud, and wondered what the citizens of Kansas would have to say about _this_.

Naida looked at the dead and bleeding ape-man and shuddered, and then at the score or so of others brought down by the puff b.a.l.l.s. Then she looked up at Kirby, raised her arms for his support, and smiled up into his brown face.

Kirby forgot Kansas, lifted her, warm and alive, radiantly beautiful, in his arms.

"Our friends the enemies," she whispered as she remained for a second in his embrace and then drew away, "will attack no more this day--thanks to you."

There was no possible need for another shot, Kirby saw. In terrified silence, the first of the apes had already floundered behind the p.r.i.c.kly pear and aloe bushes, and the last stragglers were using all the power in their legs to catch up. On the beach, Naida's followers were picking themselves up, and already a few of them had burst into ringing laughter.

"Come on, all of you," Naida said to them, and, including Kirby in her glance, added, "We may as well go to the caciques now, and have it over with."

CHAPTER IV

It was with Naida at his side and the other girls grouped about them, that they started their journey to the "caciques," whoever they might be, "to have it over with," whatever that might mean. As they strode along in silence, Kirby did what he could to straighten out in his mind the many curious things which had happened since he sat testing his rope in the upper world this morning.

In final a.n.a.lysis, it seemed to him that, extraordinary as his experience had been, there was nothing so much out of the way about it, after all. The only unusual thing was the existence of this inhabited pocket in the earth. For the rest, the strange colors to which he could not put a name, were simply some manifestation of infra-reds and ultra-violets. And then the startling effect of his single shot at the ape-men--that was simply the old story of savage creatures running from a new weapon and a new enemy; naturally the shot had sounded loud in this enclosed cavern. Lastly, the pull of gravity down here seemed upset somehow. But why should it not seem so, at this distance within the earth? The American was no scientist; the conclusions he reached seemed very reasonable to him.

All told, the last thing Kirby found he needed to do was pinch himself to see if he was awake.

A place of indefinite extent, the cavern seemed to be exactly what he had already judged it--a giant pocket within the earth. The ceiling, or the sky, was of some kind of natural gla.s.s--no doubt the same kind which was crackling on his clothes now--and from it emanated the brilliant, many colored glow which lighted the cavern. Radium? Perhaps it was that.

Perhaps the rays were cast off from some other element even less understood than mysterious radium. As for the plant and animal life with which the cavern teemed, it was amazing.

But Kirby did not give himself up to silent observation any longer.

"Will you finish telling me," he asked of Naida, "about the task I am to perform for you here?"