"You have much to learn, thern," replied Xodar, with an ugly smile, "nor do I envy you the manner in which you will learn it."

As we came on deck I saw to my surprise that the vessel was passing over a great field of snow and ice. As far as the eye could reach in any direction naught else was visible.

There could be but one solution to the mystery. We were above the south polar ice cap. Only at the poles of Mars is there ice or snow upon the planet. No sign of life appeared below us. Evidently we were too far south even for the great fur-bearing animals which the Martians so delight in hunting.

Xodar was at my side as I stood looking out over the ship's rail.

"What course?" I asked him.

"A little west of south," he replied. "You will see the Otz Valley directly. We shall skirt it for a few hundred miles."

"The Otz Valley!" I exclaimed; "but, man, is not there where lie the domains of the therns from which I but just escaped?"