An hour later, the drums were still throbbing when Joe Nara pointed above the jungle to a huge, flat-topped mountain that towered like a mighty mesa above the wavy green.

“Cerro Duida,” called Nara, from his boat. “One of the biggest mountains in the Parima chain, about a mile and a half high. It was a long time before anybody climbed it, because Indians are afraid to go with them, on account of the spirits they think live on top. It’s kind of tied in with the El Dorado story. Anyway, Cerro Duida is close to the Orinoco River—”

Nara broke off as some canoes came scooting from the canal banks, filled with armed natives. Motors were opened to the full, and the flotilla again outdistanced the native dugouts. But Biff, at the bow of his father’s monteria, saw new problems ahead.

“We’ve missed the main channel, Dad,” Biff called to the stem. “It’s shallow ahead, with a lot of sandbars.”

Mr. Brewster cut off his motor and signaled for the other boats to do the same.

“We’d better pole our way through,” he decided. “We still have time before those natives catch up with us, and we can’t risk getting stranded on a sandbar.”

“Watch where you push pole,” Kamuka advised Biff. “Big sucuria may wrap around it.”

As Kamuka pointed, Biff saw a huge anaconda lazily sunning itself on a sandbar near the canal bank. Beyond that were others; in fact, the area was alive with the giant snakes, though none appeared to be active.

Carefully, the boats were poled through the channels without disturbing the basking boas. Biff looked back and counted a dozen of them, still in repose. Snakes as well as shallows had been avoided, when Nara’s boat ran on a hidden sandbar that the others had crossed. With its heavy cargo of ore, Nara’s monteria refused to budge.

Mr. Brewster attached lines to Nara’s boat, so that the others could haul it free. He told everybody to pole at once, and his plan seemed certain of success, when Nara shrilled: