The artist, Mr. Smit, notwithstanding the novelty of the subject and the difficulties of the task, has thrown himself heartily into the work of making the twenty-four restorations of extinct animals. To him, also, the author is greatly indebted, and considers himself fortunate in having secured the services of so excellent an artist. To the publishers his thanks are due for their liberality in the matter of illustrations, and the readiness with which they have responded to suggestions. With regard to minor illustrations the following acknowledgments are due:-- To the Palæontological Society of Great Britain for permission to reproduce three of the illustrations in Sir Richard Owen's great work, _British Fossil Reptiles_, published in their yearly volumes, viz. Figs. 3, 4, and 8. To Messrs. Bell and Co. for the following cuts from the late Dr. Gideon A. Mantell's works: viz. Figs. 12, 14, 20, 33, 37, 38. To Messrs. A. and C. Black for the following cuts from Owen's _Palæontology_: viz. Figs. 51, 54, 56, 57. * * * * * Appendix IV. contains a list of some of the works of which the writer has made use; but it would be impossible within reasonable limits to enumerate all the separate papers which have necessarily been consulted. The reader will find numerous references, such as "Case Y on Plan," in brackets; these refer to the plan given at the end of the excellent little _Guide to the Exhibition Galleries in the Department of Geology and Palæontology in the Natural History Museum_, Cromwell Road (price one shilling), which visitors to the Museum are advised to obtain. PREFACE TO SECOND EDITION. The appearance of a second edition affords the author a pleasant opportunity of thanking the reading public, and the Press, for the kind way in which his endeavour to popularise the results of modern Palæontology has been received. There seem to be fashions in all things--even in sciences; and perhaps the wonderful advances we have witnessed of late years in the physical sciences on the one hand, and in biological sciences on the other, may have tended to throw Palæontology somewhat into the shade. Let us hope that it will not remain there long. A large number of illustrations have been added for the present edition, besides additional matter here and there in the text. Three of the plates (viz. Plates II. X. XV.) have been redrawn. Plate II. shows the Ichthyosaurus as interpreted by the latest discovery from Würtemberg. Plate X. gives a somewhat different interpretation of the Stegosaurus, suggested by some remarks of Mr. Lydekker. A slight change will be noticed in Plate XV. (Brontops). Plate XVII. is a great improvement on the old drawing (Fig. 28, old edition) of the Megatherium skeleton. Plate XXIV., besides containing a valuable portrait of the late Sir Richard Owen, gives another drawing of the Dinornis skeleton. _April, 1893._ CONTENTS.