An hour’s travel the next day brought them to what was undoubtedly “the worst of it.” The entrance to the valley was blocked with high, sharp-ridged dunes, of a loose shifting sand. Even the camels with their soft cushiony feet had much ado to keep from sinking deeply into it, and as there was no possibility of getting them over with the riders remaining in the saddle, Perry had to get off and lead his beast over the ridges. Into the blistering sand he sank, even more deeply than the camel. There was a light but hot wind blowing, and as this breeze topped the crest, it blew what might almost be called a thin spindrift of sun-heated sand into the faces of the travelers. The effect was like that of putting one’s face on a heated emery wheel. The camels didn’t like it, either, and said so, their harsh bubbling roar being most rasping to the temper. “Keeping up all right, lad?” his uncle asked him once, after they had crossed a particularly vicious bit. “Oh, sure, I’m all right,” Perry answered cheerily. “But I think they hit it off when they named this place.” At a few moments after eleven o’clock, the party topped the last of the ridges and looked down into Zeuglodon Valley below. Bones, bones everywhere. Skull, ribs, and the backbones of the Zeuglodons or primitive whales lay scattered on every side. Clear to the horizon, the gleam of white here and there amid the sun-burned rocks and patches of sand, told of the world’s greatest burying place of fossil whales. Ten thousand monsters lay around them. A day’s search would have produced enough skeletons to supply all the museums of all the countries in the world. “The sea must have swarmed with Zeuglodons, Uncle George,” said Perry, breaking silence when at last the sand-dunes were crossed and they were in the famous valley itself. “Apparently it did,” was the reply, “for Zeuglodons had a wide distribution. Thousands of specimens have been found in our Southern States, showing that, in those times, the Gulf of Mexico was a great deal larger than it is to-day. So thickly scattered were these bones on southern farms that foundations—for example like those of corn cribs—have been made of the vertebræ of Zeuglodons.” “They must have been whacking big,” said Perry, looking at the section of a backbone that protruded above the ground. “Bigger than anything we’ve got to-day.” “No, not as big as whales,” the scientist corrected him. “Few Zeuglodons were more than fifty feet long.” “Still, fifty feet isn’t bad.” “Fifty feet is a good length,” the professor agreed. “And Zeuglodon was a queer-looking beast. It’s hard to realize that he could have had so large a proportion of tail to so small a body and head. The Zeuglodon’s head was only about four feet long, the body wasn’t over ten, and it lugged forty feet of tail behind.” “Regular sea-serpent,” commented the boy. “I don’t suppose the tail was very big through?” [Illustration: _Courtesy of American Museum of Natural History._