Radnal smiled at the physician’s phrasing. “That was a fat sand rat. It’s a member of the gerbil family, one specially adapted to feed off succulent plants that concentrate salt in their foliage. Fat sand rats are common throughout the Bottomlands. They’re pests in areas where there’s enough water for irrigated agriculture.”

Moblay said, “You sound like you know a lot about them, Radnal.”

“Not as much as I’d like to, freeman vez Sopsirk,” Radnal answered, still trying to persuade the Lissonese to stop being so uncouthly familiar. “I study them when I’m not being a tour guide.”

“I hate all kinds of rats,” Nocso zev Martois said flatly.

“Oh, I don’t know,” Eltsac said. “Some rats are kind of cute.” The two Martoisi began to argue. Everyone else ignored them.

Moblay said, “Hmp. Fancy spending all your time studying rats.”

“And how do you make your livelihood, freeman?” Radnal snapped.

“Me?” Flat-nosed, dark, and smooth, Moblay’s face was different from Radnal’s in every way. But the tour guide recognized the blank mask that appeared on it for a heartbeat: the expression of a man with something to hide. Moblay said, “As I told you, I am aide to my prince, may his years be many.” He had said that, Radnal remembered. It might even be true, but he was suddenly convinced it wasn’t the whole truth.

Benter vez Maprab couldn’t have cared less about the fat sand rat. The spiny spurge under which it hid, however, interested him. He said, “Freeman vez Krobir, perhaps you will explain the relationship between the plants here and the cactuses in the deserts of the Double Continent.”

“There is no relationship to speak of.” Radnal gave the old Strongbrow an unfriendly look. Try to make me look bad in front of everyone, will you? he thought. He went on, “The resemblances come from adapting to similar environments. That’s called convergent evolution. As soon as you cut them open, you’ll see they’re unrelated: spurges have a thick white milky sap, while that of cactuses is clear and watery. Whales and fish look very much alike, too, but that’s because they both live in the sea, not because they’re kin.”