We had barely entered the great plain when we discovered two enormous animals approaching us from a great distance.  So far were they that we could not distinguish what manner of beasts they might be, but as they came closer, I saw that they were enormous quadrupeds, eighty or a hundred feet long, with tiny heads perched at the top of very long necks.  Their heads must have been quite forty feet from the ground.  The beasts moved very slowly—­that is their action was slow—­but their strides covered such a great distance that in reality they traveled considerably faster than a man walks.

As they drew still nearer we discovered that upon the back of each sat a human being.  Then Dian knew what they were, though she never before had seen one.

“They are lidis from the land of the Thorians,” she cried.  “Thoria lies at the outer verge of the Land of Awful Shadow.  The Thorians alone of all the races of Pellucidar ride the lidi, for nowhere else than beside the dark country are they found.”

“What is the Land of Awful Shadow?” I asked.

“It is the land which lies beneath the Dead World,” replied Dian; “the Dead World which hangs forever between the sun and Pellucidar above the Land of Awful Shadow.  It is the Dead World which makes the great shadow upon this portion of Pellucidar.”

I did not fully understand what she meant, nor am I sure that I do yet, for I have never been to that part of Pellucidar from which the Dead World is visible; but Perry says that it is the moon of Pellucidar—­a tiny planet within a planet—­and that it revolves around the earth’s axis coincidently with the earth, and thus is always above the same spot within Pellucidar.

I remember that Perry was very much excited when I told him about this Dead World, for he seemed to think that it explained the hitherto inexplicable phenomena of nutation and the precession of the equinoxes.

When the two upon the lidis had come quite close to us we saw that one was a man and the other a woman.  The former had held up his two hands, palms toward us, in sign of peace, and I had answered him in kind, when he suddenly gave a cry of astonishment and pleasure, and slipping from his enormous mount ran forward toward Dian, throwing his arms about her.

In an instant I was white with jealousy, but only for an instant; since Dian quickly drew the man toward me, telling him that I was David, her mate.

“And this is my brother, Dacor the Strong One, David,” she said to me.

It appeared that the woman was Dacor’s mate.  He had found none to his liking among the Sari, nor farther on until he had come to the land of the Thoria, and there he had found and fought for this very lovely Thorian maiden whom he was bringing back to his own people.

When they had heard our story and our plans they decided to accompany us to Sari, that Dacor and Ghak might come to an agreement relative to an alliance, as Dacor was quite as enthusiastic about the proposed annihilation of the Mahars and Sagoths as either Dian or I.