The drawings on wood were, with few exceptions, made by Miss M. E. Durham, mostly from living specimens–a procedure which has to a great extent determined the selection of the illustrations. Since both the metric and the English systems of measurements have been employed, it may be well to state for the convenience of the reader that the length of a line of the text is four inches or approximately ten centimeters. I have frequently and freely quoted accounts of previous authors instead of paraphrasing them. Especial thanks are due to Messrs. Longmans, Green, and Co., and to Messrs. Murray, {viii}for their courteous permission to make several long quotations from Sir J. E. Tennent's _Ceylon_, and from H. W. Bates' _Naturalist on the River Amazons_. Lastly, a remark about my Editors. Instead of being a source of annoyance they have rendered me the greatest help. H. GADOW. CAMBRIDGE, _December 19, 1900_. {ix}CONTENTS PAGE PREFACE v SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK xi PART I. AMPHIBIA CHAPTER I CHARACTERS AND DEFINITION—POSITION OF THE CLASS AMPHIBIA IN THE PHYLUM VERTEBRATA—HISTORICAL ACCOUNT OF THE CLASSIFICATION OF AMPHIBIA 3 CHAPTER II SKELETON OF URODELA AND ANURA—SKIN—COLOUR-CHANGING MECHANISM— POISON-GLANDS—SPINAL NERVES—RESPIRATORY ORGANS—SUPPRESSION OF LUNGS—URINO-GENITAL ORGANS—FECUNDATION—NURSING HABITS— DEVELOPMENT AND METAMORPHOSIS 11 CHAPTER III NEOTENY—REGENERATION—TEMPERATURE—GEOGRAPHICAL DISTRIBUTION 63 CHAPTER IV STEGOCEPHALI OR LABYRINTHODONTS—LISSAMPHIBIA—APODA 78 CHAPTER V LISSAMPHIBIA (_CONTINUED_)—URODELA 94 CHAPTER VI LISSAMPHIBIA (_CONTINUED_)—ANURA 138 PART II. REPTILIA {x} CHAPTER VII PAGE DEFINITION AND CHARACTERS—POSITION OF THE CLASS REPTILIA IN THE PHYLUM VERTEBRATA—CLASSIFICATION—SKULL AND VERTEBRAE 277 CHAPTER VIII PROREPTILIA—PROSAURIA—THEROMORPHA 285 CHAPTER IX CHELONIA—ATHECAE—THECOPHORA 312 CHAPTER X DINOSAURIA—CROCODILIA 412 CHAPTER XI PLESIOSAURIA—ICHTHYOSAURIA—PTEROSAURIA—PYTHONOMORPHA 473 CHAPTER XII SAURIA—AUTOSAURI OR LACERTILIA—LIZARDS 491 CHAPTER XIII SAURIA (_CONTINUED_)—OPHIDIA—SNAKES 581 INDEX 651