When the three had filled their bellies, they arose to continue their search for Jana and Jason, only to discover that the torrential rain had effectually erased every vestige of the spoor that they had been following.
"We cannot pick up their trail again," said Thoar, "until we reach the point where they continued on again after the waters ceased to fall. To the left is a deep canyon, whose walls are difficult to scale. In front of us is a fissure, which extends along the base of the mountains for a considerable distance in both directions. But if we go to the right we shall find a place where we can descend into it and cross it. This is the way that they should have gone. Perhaps there we shall pick up their trail again." But though they continued on and crossed the fissure and clambered upward toward the higher peaks, they found no sign that Jana or Jason had come this way.
"Perhaps they reached your country by another route," suggested Tarzan.
"Perhaps," said Thoar. "Let us continue on to Zoram. There is nothing else that we can do. There we can gather the men of my tribe and search the mountains for them."
In the ascent toward the summit Thoar sometimes followed trails that for countless ages the rough pads of the carnivores had followed, or again he led them over trackless wastes of granite, taking such perilous chances along dizzy heights that Tarzan was astonished that any of them came through alive.
Upon a bleak summit they had robbed a thipdar's nest of its eggs and the three were eating when Thoar became suddenly alert and listening. To the ears of the ape-man came faintly a sound that resembled the dismal flapping of distant wings.
"A thipdar," said Thoar, "and there is no shelter for us."
"There are three of us," said Tarzan. "What have we to fear?"
"You do not know them," said Thoar. "They are hard to kill and they are never defeated until they are killed. Their brains are very small. Sometimes when we have cut them open it has been difficult to find the brain at all, and having no brain they have no fear of anything, not even death, for they cannot know what death is; nor do they seem to be affected much by pain, it merely angers them, making them more terrible. Perhaps we can kill it, but I wish that there were a tree."
"How do you know that it will attack us?" asked Tarzan.