Originally published in 1901. PREFACE: I WAS a student of law at a time when Sir -- Richard Owen was lecturing on Extinct Fossil Reptiles. The skill of the great master, who built bones together as a child builds with a box of bricks, taught me that the laws which determine the forms of animals were less understood at that time than the laws which govern the relations of men in their country. The laws of Nature promised a better return of new knowledge for reasonable study. A lecture on Flying Reptiles determined me to attempt to fathom the mysteries which gave new types of life to the Earth and afterwards took them away. Thus I became the very humble servant of the Dragons of the Air. Knowing but little about them I went to Cambridge, and for ten years worked with the Professor of Geology, the late Rev. Adam Sedg- wick, LL.D., F.R.S., in gathering their bones from the so-called Cambridge Coprolite bed, the Cambridge Greensand. The bones came in thousands, battered and broken, but instructive as better materials might not have been. My rooms became filled with remains of existing birds, lizards, and mammals, which threw light on the astonishing collection of old bones which I assisted in bringing together for the University. In time I had something to say about Flying Animals which was new. The story was told in the theatre of the Royal Institution, in a series of lectures. Some of them were repeated in several English towns. There was still much to learn of foreign forms of flying animals but at last, with the aid of the Government grant administered by the Royal Society, and the chiefs of the great Continental museums, I saw all the specimens in Europe. So I have again written out my lectures, with the aid of the latest discoveries, and the story of animal structure has lost nothing in interest as a twice-told tale. It still presents in epitome the story of life on the Earth. He who understands whence the Flying Reptiles came, how they endured, and disappeared from the Earth, has solved some of the greatest mysteries of life. I have only contributed something towards solving the problems. In telling my story, chiefly of facts in Nature, an attempt is made to show how a naturalist does his work, in the hope that perhaps a few readers will find happiness in following the workings of the laws of life. Such an illumination has proved to many worth seeking, a solid return for labour, which is not to be marketed on the Exchange, but may be taken freely without exhausting the treasury of Natures truths. Such outlines of knowledge as here are offered to a larger public, may also, I believe, be acceptable to students of science and scientific men. The drawings given in illustration of the text have been made for me by Miss E. B. Seeley. KENSINGTON, May, 1901 H. G. S. Contents include: CHAPTER I. PACK FLYING REPTILES . I CHAPTER II. HOW A REPTILE IS KNOWN . ... CHAPTER III. 4 A REPTILE IS KNOWN BY ITS BONES . II CHAPTER IV. ANIMALS WHICH FLY . . . . . 15 CHAPTER V. DISCOVERY OF THE PTERODACTYLS . CHAPTER VI. HOW ANIMALS ARE INTERPRETED BY THEIR BONES . CHAPTER VII. INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS . . . ... CHAPTER VIII. . . 27 37 45 THE PLAN OF THE SKELETON .. . 58 CHAPTER IX. THE BACKBONE, OR VERTEBRAL COLUMN . 78