Another early ploughman was a bird, the Moa. The Moa had no wings, but his muscular legs were simply enormous, and so were his feet. New Zealand seems to have been the headquarters of the Moas. There used to be loads of them as shown by the huge deposits of their bones. They are supposed to have been killed in countless numbers during the Ice Ages in the Southern Hemisphere; for there were Ice Ages in the Southern as well as the Northern Hemisphere. In one great morass in New Zealand abounding in warm springs, bones of the Moas were found in such countless numbers, layer upon layer, that it is thought the big birds gathered at these springs to keep warm during those great freezes. THE MILLSTONES OF THE MOAS Besides the work they did with feet and bills you may imagine how much nice fresh stone the Moas must have ground up in their crops during the millions of years they existed. It was a regular mill--the gizzard of a Moa--full of pebbles as big as hickory nuts. Scattered about the springs where their bones are found are little heaps of these pebbles, each the contents of a gizzard. Like miniature tumuli, they mark the spots where the bodies of the Moas returned to dust. Perhaps some of those flesh-eating Dinosaurs did a little ploughing once in a while, too; for one theory is that those ridiculous little arms were used for scratching out a nest for the eggs, just as the crocodiles and the alligators and the turtles dig nests for their eggs to-day. For all these animals, as did the Dinosaurs, belong to the reptile family, and show the family trait of digging out nests for their eggs. [Illustration: A PUZZLE PAGE FROM THE GREAT STONE BOOK Talk about your cut-out puzzles! Here is a specimen of the kind of puzzle Nature and the course of things in the darkest ages of world history have cut out for the paleontologists. It is a find of ancient bones in the asphalt deposits near Los Angeles.] Although the Dinosaurs roamed the swamps and lowlands of all the ancient world, their favorite resort was the territory now occupied by our Western States--judging from the quantities of bones they left--while that old Mediterranean Sea of ours was full of their kin, the sea-lizards. Professor Marsh, of Yale, who was among the first explorers of the graves of these monarchs of the past, says that one day, while riding through a valley in the Rocky Mountains, he saw the bones of no less than seven sea-lizards staring at him from the cliffs. Yet, only here and there by the wearing through of the rocks by flowing streams has nature opened up these vast mausoleums, the mountains and the cliffs. What enormous quantities of bones, then, must still be buried there, what tons and tons must have given their lime and phosphate to the soil. So you see this story of old bones, even from a farming standpoint, is no light matter. [Illustration: HOW THE WISE MEN ANSWER THE PUZZLES