For three long hours in the very midmost heat of the day, in that broiling valley, the scientist and his young follower worked hard examining the thousands of skeletons that littered the expanse, and then Dr. Hunt gave the word to return. Perry was tired, the heat had made him dizzy, and his back felt as if he had a sore on each and every vertebra, but his pockets were full of Zeuglodon teeth, and he gloated over the fact that he had been one of the very few people in the world to visit the great Zeuglodon Valley where the bones of ancestral whales lie buried, and he was well content. Exactly three hours after the halt, the party started home for the camp. Back they went over those sand dunes, with the camels slipping and sprawling in every direction, back against the hot flying sand; back with the perspiration oozing at every pore and the tongue so parched that it licked up greedily such sweat as ran into the corners of the mouth; back with the lungs aching and the breath coming in quick, short gasps; back through the hot afternoon and until the great globe of fire dipped below the horizon, and darkness and coolness had come. On, then, still over the rough and stony approach to the Gar el Gehannem, or Hell Butte, using a slightly different route, until at last came camp, near the village of Qasr Qurun, where water, indifferent but possible to drink, was to be had. A score of village dogs barked as though each had a score of throats, yowled in loud welcome, and bayed the whole night through. It mattered little to Perry. He was tired to exhaustion, and lay asleep completely happy, while in the pockets of the coat that lay beside him in the tent, were a couple of dozen Zeuglodon teeth, that he had brought from Zeuglodon Valley with his own hands. The next day saw the party climbing homewards, up again to the raised beaches far above the ancient lake, up past the level where the Eosiren was found, up past the level of the ancient temple, up the great cliffs which marked the ages during which the sea had rolled over them, up to the levels of the ancient river deposits and then over the long miles to where the peaked outline of the distant tents held out the promise of a welcome. Yet it was the evening of the third day before they reached it, fifty-eight hours since they had left the camp, of which thirty hours had actually been spent on camel-back. “You’re a seasoned traveler now, Perry,” his uncle said, as the camel sank to its knees and the boy clambered painfully out of the saddle, “seventy-five miles in fifty-eight hours is quite a feat.” “It was great,” said Perry, “and I wouldn’t have missed it for the world. What’s a little ache in one’s bones compared to doing a stunt like that!” “After the work comes the fun,” put in Antoine. Then, turning to the leader of the expedition, he continued: