He heard a thumping, and looked up to see a second helicopter circling the bay, its dark shadow sliding across the sand. This helicopter was ambulance-white, with red lettering on the side. In the glare of the setting sun, he couldn't read it.

He turned back to the carcass, noticing now that the hind leg of the animal was powerfully muscled, very different from the foreleg. It suggested that this creature walked upright, balanced on strong hind legs. Many lizards were known to stand upright, of course, but none so large as this. In point of fact, as Levine looked at the general shape of the carcass, he felt increasingly certain that this was not a lizard.

He worked quickly now, for the light was fading and he had much to do. With every specimen, there were always two major questions to answer, both equally important. First, what was the animal? Second, why had it died?

Standing by the thigh, he saw the epidermis was split open, no doubt from the gaseous subcutaneous buildup. But as Levine looked more closely, he saw that the split was in fact a sharp gash, and that it ran deep through the femorotibialis, exposing red muscle and pale bone beneath. He ignored the stench, and the white maggots that wriggled across the open tissues of the gash, because he realized that -

"Sorry about all this," Guitierrez said, coming over. "But the pilot just refuses."

The pilot was nervously following Guitierrez, standing beside him, watching carefully.

"Marty," Levine said. "I really need to take pictures here."

"I'm afraid you can't," Guitierrez said, with a shrtig.

"It's important, Marty."

"Sorry. I tried my best."

Farther down the beach, the white helicopter landed, its whine diminishing. Men in uniforms began getting out.

"Marty. What do you think this animal is?"

"Well, I can only guess," Guitierrez said. "From the general dimensions I'd call it a previously unidentified iguana. It's extremely large, of course, and obviously not native to Costa Rica. My guess is this animal came from the Galdpagos, or one of the - "