CONTENTS. xiii 



PAGE 



G. ORGANS OF RESPIRATION 245 



I. GILLS .... 245 



of Amphioxus ... 246 



of Cyclostomi .... 246 



of Fishes 248 



of Dipnoi 250 



of Amphibia 250 



II. AIR-BLADDER AND LUNGS . . 251 



1. THE AIR-BLADDER ... 251 



2. THE LUNGS 252 



A iv- Passages 253 



of Amphibians 253 



of Reptiles .... 254 



of Birds 255 



of Mammals " 255 



The Lungs in a more Restricted Sense ... 257 



The Lungs of Dipnoi 237 



of Amphibia 257 



of Reptiles 258 



The Lungs and Air-Sacs of Birds 259 



The Lungs of Mammals 263 



ABDOMINAL PORES 265 



Bibliography ... 267 



H. ORGANS OF CIRCULATION 268 



(VASCULAR SYSTEM) 268 



Development of the Heart and Blood- Vessels 268 



The Foetal Circulation v 270 



The Heart and its Vessels 277 



of Fishes . . 277 



of Dipnoi 280 



of Amphibia 281 



of Reptiles 284 



of Birds and Mammals 286 



Arterial System 



Venous System 



Retia Mirabilia . . 292 



Lymphatic System 



Bibliography 294 



I. URINOGENITAL ORGANS 296 



Development 



URINARY ORGANS .302 



of Fishes and Dipuoans 



of Amphibians 



of Reptiles and Birds 307 



of Mammals . 308 



