SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK xi HEMICHORDATA CHAPTER I CHORDATA AND VERTEBRATA-HEMICHORDATA-ENTEROPNEUSTA-EXTERNAL CHARACTERS AND HABITS-STRUCTURE-GENERA-DEVELOPMENT-PTEROBRANCHIA- _CEPHALODISCUS_ AND _RHABDOPLEURA_-PHORONIDEA-_PHORONIS_ AND ACTINOTROCHA-AFFINITIES OF THE HEMICHORDATA 3 TUNICATA CHAPTER II INTRODUCTION-OUTLINE OF HISTORY-STRUCTURE OF A TYPICAL ASCIDIAN- EMBRYOLOGY AND LIFE-HISTORY 35 CHAPTER III CLASSIFICATION: LARVACEA-APPENDICULARIANS-STRUCTURE, ETC.-ASCIDIACEA- SIMPLE ASCIDIANS-SPECIFIC CHARACTERS-COMPOUND ASCIDIANS-GEMMATION- MEROSOMATA-HOLOSOMATA-PYROSOMATIDAE-THALIACEA-DOLIOLIDAE- SALPIDAE-GENERAL CONCLUSIONS-PHYLOGENY 63 CEPHALOCHORDATA CHAPTER IV INTRODUCTION-GENERAL CHARACTERS-ANATOMY OF AMPHIOXUS-EMBRYOLOGY AND LIFE-HISTORY-CLASSIFICATION OF CEPHALOCHORDATA-SPECIES AND DISTRIBUTION 112 CYCLOSTOMATA AND FISHES {viii} CHAPTER V THE SYSTEMATIC POSITION AND CLASSIFICATION OF FISHES 141 CHAPTER VI EXTERNAL CHARACTERS OF CYCLOSTOMATA AND OF FISHES: EXTERNAL CHARACTERS- COLORATION-POISON GLANDS AND POISON SPINES-PHOSPHORESCENT ORGANS 150 CHAPTER VII THE SKIN AND SCALES 182 CHAPTER VIII THE SKELETON 193 CHAPTER IX THE DENTITION, ALIMENTARY CANAL, AND DIGESTIVE GLANDS - 247 CHAPTER X THE RESPIRATORY ORGANS 277 CHAPTER XI THE AIR-BLADDER 297 CHAPTER XII THE VASCULAR SYSTEM, THE LYMPHATICS, AND THE BLOOD-GLANDS 313 CHAPTER XIII MUSCULAR SYSTEM-LOCOMOTION-SOUND-PRODUCING ORGANS-ELECTRIC ORGANS 349 CHAPTER XIV NERVOUS SYSTEM AND ORGANS OF SPECIAL SENSE 367 CHAPTER XV {ix} THE KIDNEYS AND THE REPRODUCTIVE ORGANS-BREEDING 397 CHAPTER XVI CYCLOSTOMATA (SYSTEMATIC) 421 CHAPTER XVII ELASMOBRANCHII: GENERAL CHARACTERS-PLEUROPTERYGII-ICHTHYOTOMI- ACANTHODEI-PLAGIOSTOMI-SELACHII-BATOIDEI-HOLOCEPHALI 431 CHAPTER XVIII TELEOSTOMI: GENERAL CHARACTERS-CROSSOPTERYGII-CHONDROSTEI-HOLOSTEI 475 CHAPTER XIX DIPNEUSTI 505 CHAPTER XX APPENDIX TO THE FISHES: PALAEOSPONDYLIDAE-OSTRACODERMI-HETEROSTRACI- OSTEOSTRACI-ANASPIDA-ANTIARCHI-ARTHRODIRA 521 CHAPTER XXI TELEOSTEI: GENERAL CHARACTERS-MALACOPTERYGII-OSTARIOPHYSI 541