The greatest inconvenience the hunters caused me was the delay, for they have a nasty habit of keeping one treed for an hour or more if balked in their designs; but at last we came in sight of a line of cliffs running east and west across our path as far as the eye could see in either direction, and I knew that we reached the natural boundary which marks the line between the Kro-lu and Galu countries. The southern face of these cliffs loomed high and forbidding, rising to an altitude of some two hundred feet, sheer and precipitous, without a break that the eye could perceive. How I was to find a crossing I could not guess. Whether to search to the east toward the still loftier barrier-cliffs fronting upon the ocean, or westward in the direction of the inland sea was a question which baffled me. Were there many passes or only one? I had no way of knowing. I could but trust to chance. It never occurred to me that Nobs had made the crossing at least once, possibly a greater number of times, and that he might lead me to the pass; and so it was with no idea of assistance that I appealed to him as a man alone with a dumb brute so often does. "Nobs," I said, "how the devil are we going to cross those cliffs?" I do not say that he understood me, even though I realize that an Airedale is a mighty intelligent dog; but I do swear that he seemed to understand me, for he wheeled about, barking joyously and trotted off toward the west; and when I didn't follow him, he ran back to me barking furiously, and at last taking hold of the calf of my leg in an effort to pull me along in the direction he wished me to go. Now, as my legs were naked and Nobs' jaws are much more powerful than he realizes, I gave in and followed him, for I knew that I might as well go west as east, as far as any knowledge I had of the correct direction went. We followed the base of the cliffs for a considerable distance. The ground was rolling and tree-dotted and covered with grazing animals, alone, in pairs and in herds--a motley aggregation of the modern and extinct herbivora of the world. A huge woolly mastodon stood swaying to and fro in the shade of a giant fern--a mighty bull with enormous upcurving tusks. Near him grazed an aurochs bull with a cow and a calf, close beside a lone rhinoceros asleep in a dust-hole. Deer, antelope, bison, horses, sheep, and goats were all in sight at the same time, and at a little distance a great megatherium reared up on its huge tail and massive hind feet to tear the leaves from a tall tree. The forgotten past rubbed flanks with the present--while Tom Billings, modern of the moderns, passed in the garb of pre-Glacial man, and before him trotted a creature of a breed scarce sixty years old. Nobs was a parvenu; but it failed to worry him.