“You haven’t learned the first thing about fossil-collecting yet,” the other replied. “In the first place, before a bone is moved, it must be studied just in the position in which it lies. Quite often the position of the bones may be of tremendous help in restoration. For example, Perry, the legs of the great fossil swimming bird Hesperornis were supposed for years to be attached to the skeleton in a way that we now know to have been entirely different. And, for another thing, you can’t tell just how fragile fossilized bones may be. You might smash them all to pieces, just by picking them up the way you started to do.”

“That’s why you collared me,” exclaimed Perry, “I was wondering.”

“Of course. Now hurry, Perry, and gather a lot of stones. We’ve got to make a heap so that we can easily find the place again, and get Dr. Hunt to come down to-morrow. I’ll take the bearings.”

Pulling from his pocket a note-book and pencil, Antoine noted with extreme care the exact bearing of as many different points as he could. Meantime Perry, first alone, and afterwards with Antoine’s aid, built up a small heap of pebbles, on the top of which they spread a white handkerchief, weighting this down by a stone at each corner. It was nearly dark when they were finished, and Perry clambered back into his camel-saddle eagerly.

Along the ledge they traveled, not knowing just where the rest of the caravan might be, and, as time went on, Antoine began to look a little troubled.

“How do you hurry up a camel?” Perry shouted to his companion.

“You don’t,” was the reply. “A camel can’t be taught to hurry. He’ll walk and carry a load. That’s about all.”

Perry clucked to his beast, reached over and slapped it on the hump, and did everything he could to suggest speed. He might as well have tried to influence the desert sand, the camel went walking steadily along, not changing its double-jointed walk by a hair’s-breadth.

Just as the sun was disappearing on the edge of the horizon, one of its last rays caught and illumined a spot of color on the ledge just a little above them.

“No chance of getting lost now,” called Perry, cheerily, “there’s the Stars and Stripes.”