At this point Dr. Gainman, the head of the camp they were visiting and with which Antoine was working, joined the party and the conversation passed into a scientific discussion concerning the effect of geographic isolation on the development of birds, and, long before the subject had been settled, Perry had made his way to his own tent and was fast asleep. Next morning, while Dr. Hunt and Dr. Gainman rode over to No Wood Draw, with Antoine as guide, to view the skeleton of the Hyrachyus and discuss the best means of removing it and shipping the block to New York, Perry started out alone for Haystack Butte. His ride with Round-up Dick and Antoine had given him a good idea of the country, and, on the way from the station to Blue Goose Gully, Antoine had pointed out to him its geology. Still he was surprised, when, less than an hour after leaving camp, he found himself on a well-beaten trail. Half feeling that the trail might lead in his direction, since it passed close to Haystack Butte, he followed it for a little distance. The skeleton of a horse, half buried in the soil, and, a quarter of a mile further on, the skull of an ox, made him wonder. Then, suddenly, the lad remembered a diagram in one of his old scientific books at home, showing a section of Haystack Mountain and the surrounding country, and on the diagram a winding road with the old thrilling name: “The Overland Trail!” Unconsciously, Perry checked his pony and looked to the westward. “The Overland Trail!” Over that trail how many emigrant trains had passed! On the long prairie stretches how many bands of hostile Indians had been fought; over the Bad Lands in which he was riding, how many emigrants had died, the men gaunt and footsore, the women weak and starved. “The Overland Trail!” No three words in all the language tell a grimmer story of American History, no three words hold more gallantry or more adventure. It was with a jerk that Perry pulled himself back to reality again and turned to the left from the old trail, towards the low slopes of that butte which is dignified by the name of Haystack Mountain. It took a sharp eye to distinguish between the two levels of rock, of which the distinguishing characters had been explained to Perry by Antoine, but the boy read his way correctly. Rounding one of the small erosion buttes he reached the point where one of the parties from the camp was engaged in uncovering an Eobasileus or Loxolophodon skeleton that had been discovered a week or two before. Perry called to remembrance the rhyme his uncle had told him quoting the scornful remarks of the Loxolophodon to the aspiring Eohippus, and he smiled. He tethered his pony, and boy-like, clambered to the very top of Haystack Butte, beneath the cap of which the Eobasileus skeleton had been found. He spent the day happily roaming around the country, learning the lie of the rocks from the clues that had been given him by Antoine.