They, too, were blank.
Sidney jumped up. "I don't care!" he exclaimed. "He told me and I've got it here!" He pointed to his head. "I can remember it, anyway."
"Can you?" asked George.
"Why, certainly I can," Sidney asserted confidently. "The reason the cliff dwellers left, George, was that they ..." Sidney stopped.
"What's the matter, Sid?"
"Well, I—it—I guess it just slipped my mind for a second." His brow puckered. He looked acutely upset and mystified. "Huk told me," he faltered. "Just a minute ago I was thinking of it when I started to tell you. Now ... I can't remember."
"That's gone, too."
"I'll get it!" Sidney declared. "I've just forgotten it for a minute. I'll remember!"
"No," said George, "you won't."
Sidney looked around. "There must be something left." He thought. "The atlatl lances they shot at us!" He looked at the U-Haul-It. The lances no longer stuck in its side. Nor were those that had fallen to the ground to be seen.