The next twenty-four hours constituted a regular field-day for the Professor, being distinguished by an event which, from a scientific stand-point, was among the most important of our entire expedition. This was the discovery of a large fossil saurian, which we came upon while exploring quite in sight of Sheridan, and not more than half a mile from its eastern outskirts. Descending the side of a deep, desolate rift in the earth, we found ourselves among unmistakable traces of violent volcanic action. The ground was strewn with black sand, and with yellow pebble-like masses, apparently impure sulphur. There were numerous round cones also, looking like diminutive craters, with edges and surface composed of bubble-like lava, the material having evidently hardened while still distended by the struggling gases. The appearance, to use a homely comparison, was somewhat that of several low pots, over the edges of which boiling molasses had poured, and then burned by the heat of the fire. Some scattered objects, which at first we took for stumps of huge trees, upon examination we found to be pillars of mud and rock, upheavals, apparently, from volcanic action, and not the work of the floods, which, in those primeval times, we knew, must have poured down the valley. They would have answered, without much difficulty, for druidical altars, had we only been in the land once inhabited by those long-bearded, blood-thirsty priests of old. Two or three poisoned cayotes and a dead raven were lying near some bleached buffalo skulls, on which, as we presently discovered, daubs of lard mixed with strychnine had been placed, and licked off by the victims; and straightway, as genius of the scene, an unshaven, woolen-shirted little man appeared in view, busily engaged in skinning a wolf. We saluted him, and the response in French-English told us his nationality at once. We found his name to be Louis, and his proper occupation that of watchmaker. But as the pinchbeck time-pieces of the frontier did not furnish enough repairing to take up his entire time, he had many spare hours, and these he devoted to securing pelts. As buffalo were not now in the vicinity, he larded their bones, with the success of which we were eye-witnesses. Louis was a wiry little Gaul, very positive in his ideas about every thing. An animated conversation sprang up at once between him and the Professor, and it soon became amusingly evident that his geological ideas did not entirely accord with those of the Philosopher. A sudden turn in the colloquy developed a fact of keen interest to even the most unscientific member of our party.