"It isn't finished," Lex said.

"I think it's meant to be open like that," Grant said.

"Then all the birds can fly out."

"Not if they're big birds," Grant said.

The river carried them beneath the edge of the dome. They stared upward. Now they were inside the dome, still drifting down the river. But 'thin minutes the dome was so high above them that it was hardly visible in the mist. Grant said, "I seem to remember there's a second lodge here." Moments later, he saw the roof of a building over the tops of the trees to the north.

"You want to stop?" Tim said.

"Maybe there's a phone. Or motion sensors." Grant steered toward the shore. "We need to try to contact the control room. It's getting late."

They clambered out, slipping on the muddy bank, and Grant hauled the raft out of the water. Then he tied the rope to a tree and they set off, through a dense forest of palm trees.

"I just don't understand," John Arnold said, speaking into the phone. "I don't see the rex, and I don't see Grant and the kids anywhere, either."

He sat in front of the consoles and gulped another cup of coffee. All around him, the control room was strewn with paper plates and half-eaten sandwiches. Arnold was exhausted. It was 8:00 a.m. on Saturday. In the fourteen hours since Nedry destroyed the computer that ran Jurassic Park, Arnold had patiently pulled systems back on line, one after another. "All the park systems are back, and functioning correctly. The phones are working. I've called for a doctor for you."

On the other end of the line, Malcolm coughed. Arnold was talking to him in his room at the lodge. "But you're having trouble with the motion sensors?"

"Well, I'm not finding what I am looking for."

"Like the rex?"

"He's not reading at all now. He started north about twenty minutes ago, following along the edge of the lagoon, and then I lost him. I don't know why, unless he's gone to sleep again."

"And you can't find Grant and the kids?"

"No."

"I think it's quite simple," Malcolm said. "The motion sensors cover an inadequate area."

"Inadequate?" Arnold bristled. "They cover ninety-two-"

"Ninety-two percent of the land area, I remember," Malcolm said. "But if you put the remaining areas up on the board, I think you'll find that the eight percent is topologically unified, meaning that those areas are contiguous. In essence, an animal can move freely anywhere in the park and escape detection, by following a maintenance road or the jungle river or the beaches or whatever."

"Even if that were so," Arnold said, "the animals are too stupid to know that."

"It's not clear how stupid the animals are," Malcolm said.

"You think that's what Grant and the kids are doing?" Arnold said.

"Definitely not," Malcolm said, coughing again. "Grant's no fool. He clearly wants to be detected by you. He and the kids are probably waving at every motion sensor in sight. But maybe they have other problems we don't know about. Or maybe they're on the river."

"I can't imagine they'd be on the river. The banks are very narrow. It's impossible to walk along there."

"Would the river bring them all the way back here?"

"Yes, but it's not the safest way to go, because it passes through the aviary…"

"Why wasn't the aviary on the tour?" Malcolm said.

"We've had problems setting it up. Originally the park was intended to have a treetop lodge built high above the ground, where visitors could observe the pterodactyls at flight level. We've got four dactyls in the aviary now-actually, they're cearadactyls, which are big fish-eating dactyls."

"What about them?"

"Well, while we finished the lodge, we put the dactyls in the aviary to acclimate them. But that was a big mistake. It turns out our fish-hunters are territorial."

"Territorial?"

"Fiercely territorial," Arnold said. "They fight among themselves for territory-and they'll attack any other animal that comes into the area they've marked out."

"Attack?"

"It's impressive," Arnold said. "The dactyls glide to the top of the aviary, fold up their wings, and dive. A thirty-pound animal will strike a man on the ground like a ton of bricks. They were knocking the workmen unconscious, cutting them up pretty badly."

"That doesn't injure the dactyls?"

"Not so far."

"So, if those kids are in the aviary…"

"They're not," Arnold said. "At least, I hope they're not."

"Is that the lodge?" Lex said. "What a dump."

Beneath the aviary dome, Pteratops Lodge was built high above the ground, on big wooden pylons, in the middle of a stand of fir trees. But the building was unfinished and unpainted; the windows were boarded up. The trees and the lodge were splattered with broad white streaks.

"I guess they didn't finish it, for some reason," Grant said, hiding his disappointment. He glanced at his watch. "Come on, let's go back to the boat."

The sun came out as they walked along, making the morning more cheerful. Grant looked at the latticework shadows on the ground from the dome above, He noticed that the ground and the foliage were spattered with broad streaks of the same white chalky substance that had been on the building. And there was a distinctive, sour odor in the morning air.

"Stinks here," Lex said. "What's all the white stuff?"

"Looks like reptile droppings. Probably from the birds."

"How come they didn't finish the lodge?"

"I don't know."

They entered a clearing of low grass, dotted with wild flowers. They heard a long, low whistle. Then an answering whistle, from across the forest.

"What's that?"

"I don't know."

Then Grant saw the dark shadow of a cloud on the grassy field ahead. The shadow was moving fast. In moments, it had swept over them. He looked up and saw an enormous dark shape gliding above them, blotting out the sun.

"Yew!" Lex said. "Is it a pterodactyl?"

"Yes," Tim said.

Grant didn't answer. He was entranced by the sight of the huge flying creature. In the sky above, the pterodactyl gave a low whistle and wheeled gracefully, turning back toward them.

"How come they're not on the tour?" Tim said.

Grant was wondering the same thing. The flying dinosaurs were so beautiful, so graceful as they moved through the air. As Grant watched, he saw a second pterodactyl appear in the sky, and a third, and a fourth.

"Maybe because they didn't finish the lodge," Lex said.

Grant was thinking these weren't ordinary pterodactyls. They were too large. They must cearadactyls, big flying reptiles from the early Cretaceous. When they were high, these looked like small airplanes. When they came lower, he could see the animals had fifteen-foot wingspans, furry bodies, and heads like crocodiles. They ate fish, he remembered. South America and Mexico.

Lex shaded her eyes and looked up at the sky. "Can they hurt us?"

"I don't think so. They eat fish."

One of the dactyls spiraled down, a flashing dark shadow that whooshed past them with a rush of warm air and a lingering sour odor.

"Wow!" Lex said. "They're really big." And then she said, "Are you sure they can't hurt us?"

"Pretty sure."

A second dactyl swooped down, moving faster than the first. It came from behind, streaked over their heads. Grant had a glimpse of its toothy beak and the furry body. It looked like a huge bat, he thought. But Grant was impressed with the frail appearance of the animals. Their huge wingspans-the delicate pink membranes stretched across them-so thin they were translucent-everything reinforced the delicacy of the dactyls.

"Ow!" Lex shouted, grabbing her hair. "He bit me!"

"He what?" Grant said.

"He bit me! He bit me!" When she took her band away, he saw blood on her fingers.

Up in the sky, two more dactyls folded their wings, collapsing into small dark shapes that plummeted toward the ground. They made a kind of scream as they hurtled downward.

"Come on!" Grant said, grabbing their hands. They ran across the meadow, bearing the approaching scream, and he flung himself on the ground at the last moment, pulling the kids down with him, as the two dactyls whistled and squeaked past them, flapping their wings. Grant felt claws tear the shirt along his back.

Then he was up, pulling Lex back onto her feet, and running with Tim a few feet forward while overhead two more birds wheeled and dove toward them, screaming. At the last moment, he pushed the kids to the ground, and the big shadows flapped past.

"Uck," Lex said, disgusted. He saw that she was streaked with white droppings from the birds.

Grant scrambled to his feet. "Come on!"

He was about to run when Lex shrieked in terror. He turned back and saw that one of the dactyls had grabbed her by the shoulders with its hind claws. The animal's huge leathery wings, translucent in the sunlight, flapped broadly on both sides of her. The dactyl was trying to take off, but Lex was too heavy, and while it struggled it repeatedly jabbed at her head with its long pointed jaw.

Lex was screaming, waving her arms wildly. Grant did the only thing he could think to do. He ran forward and jumped up, throwing himself against the body of the dactyl. He knocked it onto its back on the ground, and fell on top of the furry body. The animal screamed and snapped; Grant ducked his head away from the jaws and pushed back, as the giant wings beat around his body. It was like being in a tent In a windstorm. He couldn't see; he couldn't hear; there was nothing but the flapping and shrieking and the leathery membranes. The clawed legs scratched frantically at his chest. Lex was screaming. Grant pushed away from the dactyl and it squeaked and gibbered as it flapped its wings and struggled to turn over, to right itself. Finally it pulled in its wings like a bat and rolled over, lifted itself up on its little wing claws, and began to walk that way. He paused, astonished.

It could walk on its wings! Lederer's speculation was right! But then the other dactyls were diving down at them and Grant was dizzy, off balance, and in horror he saw Lex run away, her arms over her head… Tim shouting at the top of his lungs…