existed," Naida said presently, voice hushed, "but no one except the holy men of our race has ever beheld it."
"But, what is it?" Kirby asked. "Whence came it?"
However, when Naida would have answered, he interrupted.
"But wait! Tell me as we go. We could stay here for the rest of our lives without much trouble, but we've got to cover the rest of the tower and get back to the others."
IT was after they had closed the door to the treasure room that Naida told him the story.
"There is not so much to tell," she began. "The diamond itself is so gorgeous that it is hard to talk about. But here is the story. A great many ages ago one of the Ducas of our race found the diamond, decided to carve it into a perfect likeness of the head of the Serpent God. All of the craftsmen of the race helped him and when they were done, they took their image to Quetzalcoatl himself, and showed him what they had done.
"Quetzalcoatl was pleased. So pleased, that he promised all of the wise men that he would cease to prey upon them as he had in the past, and henceforward would take his toll of sacrifice from the ape-men alone. Them he hated and would continue to hate because they worshipped not him but Xlotli.
"And so it came about," Naida went on slowly, looking up at Kirby as they still mounted wide steps to the upper reaches of the tower, "that our people gained immunity from a God which had always before harmed and destroyed them. Our race presently began to build this castle here on the high plateau, and Quetzalcoatl kept his compact with them. He still comes out of his chasm at intervals and preys upon the ape-men, but no one of our race has seen him for thousands of years, and he has always let us alone. And there is the whole myth and explanation of why the great diamond is revered among us as a holy of holies."
THEY had mounted to a new door which Kirby guessed might give entrance to the Duca's living quarters. But he was in no mood to open it at once.
"Wait a minute," he said as they all paused. "You say that, although none of your race has seen Quetzalcoatl since the diamond head was carved, he still comes out of his chasm and makes trouble for the ape-men. Just what does that mean?"
"Why—" Naida looked at him wonderingly. "I mean what I have said. The Serpent comes out of his chasm and—"
"What chasm?" Kirby asked sharply.
"Why, the one we crossed this morning. It extends to the far reaches of our country, beyond the Rorroh forest, where the ape-men dwell but which our people never visit. It is in that distant part of the chasm that the Serpent dwells."
"But—but—Oh, good Lord!" Kirby whistled softly. "Naida, do you mean to tell me that Quetzalcoatl was not simply a mythical monster, but an actual, living serpent which is alive now?"
Naida and the others shrugged.
"Why not?" she answered. "Sometimes we have captured a few ape-men, and they tell us stories of how Quetzalcoatl kills them. They say he is very much alive."
"But," Kirby mumbled in increasing wonder, "is this living creature the same which your ancestors worshipped first as long ago, perhaps, as a million years?"
"That," Naida answered unhesitatingly, "I'm not sure of. Our caciques believe that the Serpent, although it lives longer than any other sentient thing, finally dies and is succeeded by a new Serpent which is reproduced by itself, within its own body."
So overwhelming did Kirby find this unexpected sequel to their discovery of the great diamond head, so stag-
