x CONTENTS 



CHAPTER PAGE 



C. Flat Worms 78 



D. Round Worms 79 



E. Segmented Worms 81 



F. Rotifers, Bryozoans, and Brachiopods .... 82 



G. Echinoderms 83 



H. Molluscs 86 



I. Arthropods 90 



VIII. THE INVERTEBRATE BODY 98 



A. Hydra 98 



B. Earthworm .... 100 



1. Body Plan 101 



2. Tissues and Organs 104 



C. Crayfish 104 



IX. SURVEY OF VERTEBRATES Ill 



A. Fishes 112 



1. Sharks and Rays 113 



2. Bony Fishes 115 



3. Lung Fishes 116 



B. Amphibians 117 



1. Salamanders and Newts 117 



2. Toads and Frogs 118 



C. Reptiles 120 



1. Turtles and Tortoises 120 



2. Crocodiles and Alligators 121 



3. Lizards and Snakes 121 



D. Birds 123 



E. Mammals .126 



1. Monotremes 127 



2. Marsupials 127 



3. Placentals 128 



X. THE VERTEBRATE BODY 132 



A. Body Plan 132 



B. Skin 134 



C. Muscles 135 



D. Skeleton 138 



E. The Human Body 143 



F. Distinctive Vertebrate Characters 145 



XI. NUTRITION 150 



A. Buccal Cavity, Pharynx, and Esophagus . . . 151 



B. Stomach 153 



C. Small Intestine 153 



1. Liver and Pancreas 154 



2. Absorption 157 



3. Distribution 157 



D. Large Intestine 158 



E. Food Use 159 



F. Ductless Glands 160 



