The day following our discovery of the trail, I accordingly invited him to accompany me, and we set out early, each armed with a revolver and a rifle. I advised West, who automatically took command of the ship during my absence, that we might be gone considerably longer than usual and that he was to feel no apprehension and send out no relief party unless we should be gone a full twenty-four hours, as I wished to follow up the spoor we had discovered, learn where the trail led and have a look at the animal that had made it. I led the way directly to the spot at which we had found the trail, about four miles down river from the ship and apparently in the heart of dense forest. The flying-toads darted from tree to tree about us, uttering their weird and plaintive cries, while upon several occasions, as in the past, we saw four-legged snakes such as we had seen upon the day of our landing. Neither the toads nor the snakes bothered us, seeming only to wish to avoid us. Just before we came upon the trail, both Orthis and I thought we heard the sound of footsteps ahead of us—something similar to that made by a galloping animal—and when we came upon the trail a moment later it was apparent to both of us that dust was hanging in the air and slowly settling on the vegetation nearby. Something, therefore, had passed over the trail but a minute or two before we arrived. A brief examination of the spoor revealed the fact that it had been made by a three-toed animal whose direction of travel was to our right and toward the river, at this point some half mile from us. I could not help but feel considerable inward excitement, and I was sorry that one of the others had not been with me, for I never felt perfectly at ease with Orthis. I had done considerable hunting in various parts of the world where wild game still exists but I had never experienced such a thrill as I did at the moment that I undertook to stalk this unknown beast upon an unknown trail in an unknown world. Where the trail would lead me, what I should find upon it, I never knew from one step to another, and the lure of it because of that was tremendous. The fact that there were almost nine million square miles of this world for me to explore, and that no Earth Man had ever before set foot upon an inch of it, helped a great deal to compensate for the fact that I knew I could never return to my own Earth again. The trail led to the edge of the river which at this point was very wide and shallow. Upon the opposite shore, I could see the trail again directly opposite and I knew therefore that this was a ford. Without hesitating, I stepped into the river, and as I did so I glanced to my left to see stretching before me as far as my eye could reach a vast expanse of water. Here then I had stumbled upon the mouth of the river and, beyond, a lunar sea.