replied.

"So! That is good. But now listen: my name is Zoro and I am Chief of the Heads of Apex. Ages ago we Heads lived on a continent of your Earth now known to scholars as Atlantis. When Atlantis sank below the waves—in your sacred book that tragedy is known as the Flood—all but a scattered few of its people perished. I and my companions were among the survivors."

The Americans stared at him unbelievingly. "But that was a hundred thousand years ago!" exclaimed Ward.

"Three hundred thousand," corrected Zoro.

They stared at him dumbly.

"Yes," said Zoro; "it sounds incredible to your ears, but it is true. Mighty as is the industrial civilization of your day, that of Atlantis was mightier. Of course, the country wasn't then called Atlantis; its real name was A-zooma. A-zooma ruled the world. Its ships with sails of copper and engines of brass covered the many seas which now are lands. Its airships clove the air with a safety and speed your own have still to attain. The wealth of the world poured into A-zooma, and its rulers waxed vain-glorious and proud. Time after time the enslaved masses of A-zooma and of conquered countries rose in great rebellions. Then against them marched the "iron baylas" breathing death and destruction, and from the air mighty ships poured down the yellow fog...."

Zoro paused, but presently went on: "So we ruled—for ten thousand years; until the scientists who begot those engines of destruction became afraid, because the serfs themselves began to build secret laboratories. We of the priesthood of science saw the inevitable disaster. Long ago we had put off our bodies—"

Zoro smiled at the Americans' amazement. "No," he said, "I am not a cripple in a wheelchair. This tubular container holds no fleshly body. Inside of it is a mechanical heart which pumps artificial blood—blood purified by a process I will not describe—through my head. It also contains certain inner devices under my mental control, devices that take the place of human hands and feet. Only by accident or through lack of certain essentials can I die."

His listeners stared at him in awe. "You mean," faltered Miles, "that save for your head you are all—machine?"

"Practically, yes. We priest-scientists of the Inner Mystery prolonged life in such fashion. I was three thousand years old when—But enough! I will not weary you with a recital of how the slaves burrowed the bowels of A-zooma and of how the masters loosed against them the forces of the atom. Suffice it to say that on an island we built our vast system of buildings—or tunnel as you choose to call it—and sealed them away from the outside world, entrance being made by submarines through automatically controlled locks.

"At about this time our experiments opened up another realm of existence, manifesting at a vibratory rate above that of earth. To this new realm we brought workers who built the City of Apex and the palace you are in. But, unfortunately, we brought with us no weapons of offense, and in the new world we had neither the material nor the delicate mechanisms and factories to reproduce them. However, for countless ages there was no rebellion on the part of the workers who, even in A-zooma, had worshipped us as gods. They were born, grew old and died, but we abode forever. Besides, in the City of Apex they were freer than they had ever been before, merely having to furnish our laboratories with certain raw materials and the wherewithal to sustain the blood supply on which our lives depend. But, of late, they have made common cause with the original inhabitants of this plane, the green men—"

The green men! As if the words were a signal, a dreadful thing happened. Out of a far shadow leaped a lean and hideous monster. To Miles' startled eyes it seemed to grow as it leaped. Thin, unbelievably thin it was, yet swelling at the head. From between two goggle-eyes writhed a rope-like trunk. Twelve feet in the air its head towered over Zoro. "Look out!" screamed the American.

Zoro's chair seemed to jump. Too late! Around the tubular container wrapped the snake-like trunk, plucking the wheelchair and its occupant from the floor and dangling them high in air. "Shoot!" cried Zoro.

Miles shot. His bullet ploughed through the unbelievably thin body and ricochetted from a pillar beyond. Ward fired with better effect. One of the goggle eyes spattered like glass. Under a fusillade of bullets the monster wilted, giving expression to a weird, shrill cry. Zoro dangled head downwards. To drop from such a height on his skull would probably be fatal.

But the monster did not drop him. Instead, in its death agony, its grip tightened, and the Americans witnessed an incredible sight. Before their very eyes the monster began rapidly to shrink. Its tenuous body telescoped together, becoming thinner and thinner in the process, until on the floor there lay the lifeless body of a snake-like creature not more than six inches in length!

"Good Lord!" breathed Miles.

Zoro who had escaped unscathed from his perilous plight, regarded it with his peculiarly colored eyes.

"It is a tah-a-la," he said, "and must have entered the room at the same time you did. The green men often capture and train them for hunting. When about to seize their prey their bodies have the power of enormously stretching." Outwardly he seemed unaffected by the danger safely passed and waved away several of his fellows who had wheeled to the spot attracted by the noise of the pistols. The Americans were more shaken. "Perhaps," said Ward, "there is danger of—"

"None," replied Zoro. "I know there are no other tah-a-las inside these rooms, since it is the nature of these beasts to rush to each other's aid when they scream. And as for outside attacks, the laboratories are insulated against any the insurgent workers can make. Their weapons are poor—the green men use but clubs. No, it is not their attacks we fear but their refusal to furnish us with supplies. They worshipped us as gods, and the giving of supplies was long a religious rite. But now they doubt our divinity, and, since they no longer listen to or obey our decrees, we have no means of punishing them. Spiro is responsible for this."

"Spiro?" questioned the two men.

"He whom we raised to the dignity of godhead on the accidental death of Bah-koo, causing a deep sleep to fall upon him in the temple and grafting his head upon the mechanical body left by the latter. Twice before we had done this with citizens of Apex, and how were we to know that Spiro would resent it? True, he was in love with Ah-eeda, but the physical passions of men die with the organisms that give them birth. For three years he dwelt with us in the laboratories, learning the wisdom of the Heads, and then,"—Zoro's face became forbidding—"he denounced us to the people. Though there was more or less discontent, they would never have dared defy us save for him. He told them that our curses could do no harm, that we were merely the heads of men like himself and would die if they refused to give us the wherewithal to renew blood.

"But this refusal of theirs is an evil thing," he cried, looking at the Americans with his strangely colored eyes. "It violates the custom of ages, and strikes at the very roots of our existence. So we held council and sent two of our number to Earth after men and weapons to enforce our demands. For years we had watched Earth, seen its myriad civilizations rise and fall, studied the coming of America to power and importance. So it was to America that Solino went, by way of the tunnel that still exists under the Atlantic—"

"And hired us," interrupted Ward, "and brought us to the tunnel in the submarine-car where we—"

"Stepped into the crystal chamber," finished Zoro. "That chamber is a re-vibrating device of certain rays and chemicals. The shutting of the door