Evening approached again with what seemed like unreasonable rapidity. The previous days had been so busy and so strenuous that Matthew had hardly noticed the fact that Tyre’s day was 11 percent shorter than the Earthly day that had been carefully conserved aboard Hope. Now that Voconiahad take over the burden of progress, while Matthew was not merely a passenger but an invalid, the time-scale difference seemed to leap out at him as if from ambush, further increasing his sense of dislocation and surreality.

Ike finally condescended to step back from the wallscreen and lay the keyboard aside, saying: “I can’t take any more.”

“We’re not going to turn anything up this way, Ike,” Matthew said, somberly. “We’re just looking at the rest-states of the cells. We need to keep tabs on them while they’re active. Lityansky’s watched the cut-and-paste processes that produce the local equivalents of sexual exchange, but we need to fill in the yawning gap that still separates us from an understanding of their reproductive mechanisms. It’s not here. It’s just not here. The specimens are all too small, too simple. This stuff isn’t ever going to show us what all that juicy over-the-top complexity is for.”

“It might,” Ike demurred, “if we could only figure out how to extrapolate the data properly. Even in the simple world of the DNA monopoly it’s extraordinarily difficult to catch the more elusive genes at it. The guys who navigated their way through the hinterlands of the original genome maps back in the twentieth century had to creep up on all the rarely activated axons. It took them all century and a lot of inspired guesswork to nail down the reallyshy ones. It might take us as long. We have better equipment, but we’re on the outside looking in. But you’re right about one thing: we need some good key specimens—and these don’t qualify. Unfortunately, we couldn’t know that they didn’t until we’d looked.”

Matthew nodded agreement. Earth’s ecosphere had thrown up useful specimen species at every stage of genetic research, but nobody would have been able to identify them as significant keys just by looking at them. Drosophila, Rhabditis, and the puffer fish had not come bearing labels proclaiming their unique value as foundation stones of genetic analysis.

“Even if we found a humanoid,” Ike continued, pensively, “there’d be no guarantee that analyzing his—or more likely its—genes would illuminate the fundamental issues. On the other hand, there might be some unobtrusive little creature minding its own business in the shadows, whose cells are working overtime in a special way that would do exactly that. So we have to keep looking. Do you want to call it a day and watch the sunset?”

“Sure,” Matthew said. “And tonight, I want a reallygood night’s sleep, to get me ready for the cliff-descent. If my arm will let me sleep, that is.”

“Your IT will see to it,” Ike assured him, as they made their way out on to the deck. Lynn and Dulcie were already there, having abandoned their own labors a little earlier.

As on the previous evening, the character of the river fauna changed quite markedly as the light faded through dark blue to dark gray, but the most noticeable aspect of the change this time was auditory. The noises emanating from the forest increased in volume and complexity, although the crescendo was relatively brief.

“Is it just me,” Dulcie Gherardesca asked, “or is the chorus progressing from quaintly plaintive to almost harrowing?”

“It’s just the numbers,” Ike told her. “There must be thousands. No birds, though. Squirrels and monkeys and whistling lizards. Great lungs, though. Can we assume that they’re marking territories and summoning mates, do you think, or should we be bending our minds to wonder what otherfunctions that kind of caterwauling might serve?”

Nobody bothered to answer that, or to remind the speaker that what he really meant was squirrel- and monkey- analogues.

“The biodiversity might be limited by comparison with home,” Lynn observed, “but there are plenty of critters out there. Maybe we ought to moor for a spell and take a look. The forest’s quite different hereabouts, nothing like the hills around the ruins.”

“Better to do it on the way back,” Ike said. “We came to take a look at the vitreous grasslands. They’re the great unknown, the ultimate Tyrian wilderness.”

The urgent phase of the chorus faded soon enough, although it never dissolved into silence. Almost as soon as the stars came out in force the boat bumped something, and then bumped it again. The impacts were slight but distinctly tangible. Matthew’s first thought was that they were nudging dangerous underwater rocks, but it only required a glance to inform him that the river was easily wide enough to allow the AI to steer a course through any such hazard. Whatever was bumping Voconiawas moving under its own power to create the collisions, and it had to be at least as big as a human, if not bigger.

“We need a picture,” Ike was quick to say. “I’ll feed the AI’s visuals through to the big screen.”

Matthew and the two women returned immediately to the cabin, but the results were disappointing. There were no more bumps, and the recorded images were worthless. The AI had the means to compensate for near-darkness, but not for the turbidity of the water. They could see that somethinghad thumped the boat repeatedly, but whether it was merely a big eel-analogue or something less familiar remained frustratingly unclear.

“Here be mermaids,” Matthew murmured.

“Or maybe manatees,” Dulcie said, drily. “ Genuineexotics.”

Matthew knew what she meant. Manatees had been extinct before he was born, along with Steller’s sea cow and the dugong, and their DNA was unbanked. Humans would never see their like again—but mermaids, being safely imaginary, would always be present in the chimerical imagination. On the other hand, this was Tyre, where chimerization was built into the picture at the most fundamental level, even though the vast majority of individuals didn’t seem to be exhibiting it at the moment of their observation. If there were mermaids anywhere, this was the kind of place in which one might expect to find them.

“It was big,” Ike reported. “The AI estimates not much less than half a ton. That’s reallybig. There’s nothing like that around the base. I bet there’ll be even bigger ones further downstream, and more of them. We’ll catch up with them tomorrow. It’s only a matter of time.”

“It’s about time we found some sizable grazers,” Matthew opined. “Dense forests always favor pygmies, but rivers and their floodplains usually have far more elbowroom. There used to be hippos in Earthly rivers and elephants on plains, until people crowded them out. Even if there are humanoids lurking in the long grass of the glass savannah, they surely can’t be so numerous that they’ve driven the big herbivores to extinction. If they were that effective, we’d have found proof of their existence easily enough.”

“They couldn’t have driven the big herbivores to extinction recently,” Dulcie put in, by way of correction. “This is an oldworld. What would the biodiversity of Earth have been like a billion years hence, if humans had never invented genetic engineering?”

“It isn’t coming back,” Lynn observed. “We must have passed through its stamping ground. But there’ll be others.”

“They can’t do us any damage,” Ike said. “They won’t even wake us up, unless they can stay close enough to start chewing up the biomotor outlets.”

“Is that possible?” Matthew asked, suddenly realizing that there might be a downside to Voconia’s employment of organic structural materials and an artificial metabolism that used lightly converted local produce as fuel.

“No, it’s not,” Lynn assured him. “The AI defenses can take care of anything that conspicuous. There’s no need for anyone to sit in the stern with Rand’s gun.”