CONTENTS xix 



Page 



CHAPTER LVI 



Reptiles and Birds 382 



Structural characteristics — Embryonic modifications — Egg — Amnion — 

 Allantois — Body coverings. 



CHAPTER LVII 



Class Reptilia 386 



Classification — Internal structure — Squamata — Chameleons — Lizards — 

 Snakes — Venomous snakes — Rhynchocephalia — Crocodilia — Testudinata — 

 Economic importance. 



CHAPTER LVIII 



Class Aves 403 



External characteristics — Feathers — Internal structure — Classification — 

 Origin of birds and of flight — Flight — The bird as a flying animal— Modifica- 

 tions of birds — Plumage — Songs — Migration of birds — Reproduction — 

 Economic importance. . 



CHAPTER LIX 

 Class Mammalia 424 



External characteristics — Hair — Internal structure — Classification — Ori- 

 gin of mammals — Monotremes — Marsupials — Unguiculata — Primates — 

 Ungulata — Cetacea — Hibernation — Reproduction — Economic importance . 



CHAPTER LX 

 Anthropoid Apes and Man 449 



Manlike apes — Erect position — Evidences in man of former arboreal life — 

 Intermediate forms — Fossil men — Present-day man. 



PART V 

 General Considerations 



CHAPTER LXI 

 Animal Organisms 457 



The organism — Definition — Income and outgo — Differentiation — Integra- 

 tion — Centralization — Chemical control — Individuality — Life cycle in birds 

 and mammals — Other life cycles — Practical considerations — Organismal 

 concept. 



CHAPTER LXII 

 Structure of Organism 463 



Grades of organization — Germ layers and tissues — Relationship of cells in 

 metazoans — Organs and systems — Tegumentary system — Skeletal system — 

 Digestive system — Glands — Respiratory system — Circulatory system — 

 Excretory system — Reproductive system — Muscular system — Nervous sys- 

 tem — Convergence and divergence. 



CHAPTER LXm 



Development of the Organism 475 



Germ cells — Origin of germ cells — Maturation of the germ cells — Egg — 

 Fertilization — Cleavage — ^Blastula — Gastrulation — Mesoderm formation — - 



