"When I first got to the Silurian Period, I met a couple of scientists named Doctor Russell and Doctor Vrastil, who were planning a little weekend boating expedition along the coast. Doctor Russell studied fish, and Doctor Vrastil studied plants. They asked me if I'd care to go along for the ride and a change of scenery, which is a laugh, since every place in the Silurian Period looks pretty much like every other place. But I said yes, because right then we were in a place called Stinktown. It's called that because when the tide goes out, all this slimy mud and seaweed lies around in the hot sun and starts stinking to high heaven. I had a few days to kill before I could catch a ride to my weather station, but I thought the smell was likely to kill me if I stayed in Stinktown.

"So, early one morning, the three of us took a boat and headed out along the coast, which was all cut up into inlets. Some had never been explored. Around midday, we put into one that Russell and Vrastil found particularly interesting for some reason. I thought it was creepy, even for the Silurian Period, but I didn't want to say anything. It wasn't my party. We went in past thick floating mats of seaweed and then turned off the motor and drifted for a while. It was so quiet all you could hear was the water slapping against the hull of the boat. High rocky cliffs rose on both sides of us, and nothing grew on the shore except moss. There was a glass observation pane in the bottom of the boat, so Russell could point out all the trilobites and funny-looking fish and things, but as we went in further, the water got murky from a muddy little river that emptied into the inlet.

"After we'd set up camp, they went their separate ways to look at fish or moss. I decided to climb the cliffs enclosing the inlet and see what I could see from the top, only to find that they were too steep to climb. The only way out of the inlet was the way we'd come in.

"At sundown, we met back at camp. We were hungry and very tired, and as soon as we'd eaten supper we turned in for the night. But something awakened me after a while, a strange sound, perhaps, or something else I'd sensed in my sleep. I lay there for a minute or two, trying to figure it out, then sat up and looked around. There was enough moonlight for me to see that the others were sound asleep—and that our boat was missing!

"I gave a yell to wake them up, and we all scrambled down in a panic to the water. There we realized that our boat wasn't actually missing, it just wasn't where we'd left it, tied up to a metal stake driven into the ground. We could just barely see the boat about a hundred feet out and figured it must've pulled loose when the tide went out. Doctor Russell said, I tied the line, I'll go get the boat, and walked right into the water. Doctor Vrastil and I could see the silvery splashes he made as he waded out and started swimming. Then, suddenly, there was a big noisy splash and a sound like he was trying to shout with his mouth full of water.

"We called out, but he didn't answer. I started to run into the water, but Doctor Vrastil stopped me. Let me go, I said, something's happened to Russell! But he said, Wait, there's a flashlight in my pack, and ran to get it.

"I didn't wait but plunged in. I'd waded out up to my knees when the beam from the flashlight stabbed through the darkness and played over the water. What I saw before me froze my blood—a moving mass of sea scorpions, all writhing bodies and snapping pincers. The creatures fed at night, and poor Doctor Russell had blundered right into their feeding ground. Now they were coming after me!

"I backed onto the shore, fast, and thought that would be enough. Doctor Vrastil kept the light on the creatures as they advanced to the water's edge. They hesitated there. And then, to my horror, they began to crawl ashore, alternating dragging and pushing themselves forward. They were gill-breathers, of course, but they could trap water in their gills.

"I dashed back to where Vrastil crouched with the flashlight. Everywhere he trained the beam, we saw dozens of the hideous monsters, converging on us. The only sounds were the clicking of their terrible claws and the scrape and crunch they made as they dragged their bellies over the ground. We could've outrun them easily if there'd been any place to run to, but the cliffs trapped us, and we had no weapons. I don't mind telling you I was scared, and Vrastil was making little whimpering cries.

"But millions of years of evolution have given us brains, and at last I used mine. I had an inspired thought and suddenly dashed the flashlight from Vrastil's hand. It struck the ground I heard glass break, and the light went out. Vrastil screamed and clutched at me in terror. It was all I could do to make him be quiet and listen to me. The light, I told him, it's the light! The light attracts them! Sure enough, the monsters began to mill around uncertainly in the moonlight.

"But if they no longer had the beam of light to guide them to us, they still had the idea of prey fixed in their primitive little minds, and with so many of the creatures blindly groping about, the chance still existed that they'd overrun us. It seemed like hours before their gills began to dry out and, one or two at a time, they slipped back into the water. Even then, I didn't dare relax my vigilance, knowing that they could come ashore at will. Nights are short in the Silurian Period, because the Earth rotates faster, but that night was the longest of my life."