"Or at least leaving it alone," Veg said. "It's a decent bird..."

"We appear," Cal remarked, "to have a multiple difference of opinion. Veg feels that we should leave his Orn-bird alone; 'Quilon feels we should help it; I feel the needs of our own species must take precedence. We must have room to expand."

"Lebensraum," Aquilon whispered tersely.

The word shook him. How bitterly she had drawn the parallel: Adolph Hitler's pretext for conquest. The Third Reich had to have room to live -- at the expense of its neighbors. Their living needs were not considered.

"What do birds eat?" Veg asked.

Cal felt Aquilon shudder. She was a practicing vegetarian at the moment, eschewing the omnivorous way of life. If her comment about Lebensraum had shaken Cal, Veg's question had shaken her. For they all knew what birds ate, especially big birds. They were carnivorous or omnivorous.

They hashed it through, but their positions were set by those two words: Lebensraum and Omnivore. Cal was on one side, accepting both concepts and their applicability to the present situation of Earth; Veg was on the other, accepting neither. Aquilon, torn between the two, finally had to go with Cal: when one omnivore contested with another for territory, might was right.

It was a subtle, seemingly minor distinction, but it touched on deep currents. They had all waged an interplanetary struggle against the omnivore -- yet they themselves were aspects of the omnivore. The words they said now were hardly more than chips floating on the sea, hinting at the implacable surges beneath. In the end Veg got up and left the raft.

Cal felt a pain as though his heart were physically breaking; he knew the rift was fundamental. Perhaps Veg would return -- but once Cal made his report to Earth, which would set in motion Earth's exploitation of Paleo and the probable extinction of dinosaurs and Orn-birds alike, their friendship would never be the same.

Beside him, Aquilon was sobbing. Cal knew that some streak of perversity in him had made him argue the omnivore's case; he had no more sympathy with the appet.i.tes of the omnivore than Veg did. Let Paleo remain unspoiled!

No, the issue had to be brought out, examined, even though it hurt.

They slept side by side. Cal did not touch her, though he longed for her with a loin-consuming pa.s.sion. She was not a proper subject for l.u.s.t, she was Aquilon, fair and perfect...

In the morning they checked for Veg but could not find him. "I think he's all right," Aquilon said. "He's with the birds. We should leave him alone and go to make the report. He'll never go with us."

That d.a.m.ned report! "I hate this schism," Cal said.

"So do I. But how can we bridge it? We talked it all out."

They had talked nothing out! But words today were as pointless as the words of yesterday.

They set sail on the Nacre, dispatching the mantas to locate Veg and return with news of him. While they were at sea, there was a dancing of the waves, indicating a small tremor or earthquake. "I hope that's the extent of it!" Cal said.

They beached the raft with some difficulty, then set out on foot.

And in the afternoon the tyrannosaurus picked up their trail.

The mantas were ready to help, but Cal warned them off. "If we think our kind is superior, we should be ready to prove it," he said.

"Against a carnosaur?" she demanded incredulously. "Ten tons of appet.i.te? The ultimate predator?"

"The ultimate reptilian predator, perhaps," he said. "Though I suspect the earlier allosaurus might have been more efficient. The mantas would be the ultimate fungoid predators. And man stakes his claim to being the ultimate mammalian predator. So it is proper that the champions meet in single combat."

Suddenly she saw it. "The mammals and the reptiles, meeting on the field of honor. The decisive combat. The carnosaur has size and power; the man has brain. It is a fair compromise, in its fashion. It relieves the conscience of difficult moral decisions."

"Precisely," Cal said, smiling grimly. "I knew you'd understand. And so will Veg. You had better hide in a tree. I must do this alone."

She scrambled away as the ground shuddered, and not from any geologic tremor. Tyrannosaurus rex, king of predators, was closing in for the kill! The tyrant lizard's tread rocked the land, and the crashing of saplings became loud.

He glanced at Aquilon to make sure she was safe, knowing that she would be terribly afraid for him, and with reason. Intellectually, she comprehended his decision, but emotionally it was intolerable. She thought he would be killed. "Cal -- no!"

Too late. The slender fern trees swayed aside. A bird flew up from a nearby ginkgo tree. Through the palm fronds poked a gaping set of jaws -- fifteen feet above the ground. There was a roar. Tyrann had arrived.

The dinosaur charged upon Cal, dwarfing the man. Aquilon stared from her perch, unable to turn her head away, horrified.

When Tyrann was no more than its own length -- fifty feet -- distant, Cal dodged to the side. He surprised himself by the alacrity with which he moved, picturing what Aquilon was seeing. She still tended to think of him as the wasted, physically weak sufferer she had known on Nacre. But he had recovered greatly and now approached normal vitality. His love for her, he knew, was partly responsible.

Tyrann was unable to compensate in time and drove his nose into the dirt where Cal stood. He lifted his mottled head, small eyes peering about while leaves and twigs tumbled wetly from his jaws.

Now the real chase began. Cal had no chance to watch out for Aquilon, but he knew she was following with the mantas, observing. If Tyrann should spot her, the mantas would help her escape. They could hardly stop Tyrann's charge, but their cutting tails could strike out the monster's eyes and nose, depriving him of his princ.i.p.al senses.

Cal played a desperate game of peekaboo around a large palm tree with the carnosaur. Then he fled through a small forest of firs, Tyrann pursued indefatigably, relentlessly. Cal found a herd of triceratops, grazing dinosaurs with huge bony plates on their heads and a deadly trio of horns. One of the bulls came out to challenge Tyrann and so provided Cal with some breathing s.p.a.ce.

He ran up the side of the mountain toward the snow-line. Then the earth rocked violently: another quake. He was thrown to the ground almost under Tyrann's nose.

But the quake also upended the dinosaur, who went rolling down the slope. Relieved, Cal got up -- and was struck by a stone rolling down the mountain. A freak of luck -- but fatal.

He was only unconscious a few seconds, he thought -- but as he struggled to his feet, Tyrann was upon him. The gaping mouth with its six-inch teeth closed on his legs.

There was an instant of unbearable pain. Then his system, recognizing that, cut off the pain. Cal knew he had lost. One leg had been sheared off. There would be no report from this world. The dinosaur had proved superior.

Perhaps that was best.

Aquilon, thrown off her feet by the quake, waited for the upheavals to stop. Then she ran up the slope after the dinosaur, flanked by four mantas. What she saw was sheer nightmare.

... rag-doll form flung high into the air... jaws closed, ripping off an arm... head lolled back from broken neck... dead eyes staring...

Aquilon screamed.

Tyrann gulped down the remnants of his meal, then cast about, orienting on the scream. He saw Aquilon.

Had it really been a nightmare, a bad dream, she would have awakened then. But it was real, and the carnosaur was still hungry.

The four mantas settled about her, facing Tyrann, In a moment they would attack. "No!" Aquilon cried. "I will finish the fight he started -- or die with him!" For now, too late, she realized how completely she loved Cal. Why had she never taken the initiative? Only in this way -- by sharing his challenge -- could she exonerate her missed opportunity.

"Hex and Circe -- go find Veg, take care of him. Diam and Star, go guard the Orn-birds and their nest. Don't come back to me until I have settled with Tyrann -- one way or the other."

They moved out, sailing down the mountain like the manta rays for which they had been named. She was on her own.

She fled up the mountain, knowing that Cal must have had good reason to go that way. The cold -- maybe the snow of the heights would stop the creature!

Tyrann followed -- but not with the alacrity he had pursued Cal. Was it because he had suffered internal injuries when he tumbled during the earthquake -- or was he simply less hungry now?

Dusk was coming. That and the increasing elevation chilled the air rapidly. Soon it was near freezing, and she knew the snows were not far beyond. She was not cold, for her continued exertion generated warmth -- but the moment she stopped, she would be in danger.

Her foot caught in something, and she fell, splashing. It was a small stream. Now she was soaked -- and that would only accelerate her exposure. But she could not stop, for Tyrann was not far behind.