ADAPTATION FOR PROTECTION FROM ENEMIES 83 _Mollusca_: Clam, 83; Snail, 87; Squid, 89; Comparative Study, 91; Review and Library Exercise, 92. Comparative Study of Exoskeletons, 93; Protective Coloration, 94; Animal Associations, 96; Protective Habits and Powers, 98; Defensive Structures, 99; Thesis: "Adaptation for Protection," 99. CHAPTER VI VERTEBRATES 101 _Fishes_: Living Fish, 101; External Structure, 103; Mouth and Gills, 105; Alimentary Canal and Circulatory System, 107; Review and Library Exercise, 110. Primitive Chordates, 112. _Amphibia_: Living Frog or Toad, 114; Mouth, 116; Organs of Digestion, Absorption, and Excretion, 117; Organs of Circulation and Respiration, 120; Nervous System, 123; Endoskeleton, 125; Comparative Study, 129; General Review and Library Exercise, 129. _Reptiles_: Living Snake, Lizard, and Turtle, 130; Review and Library Exercise, 132. _Birds_: Living Pigeon, 133; Plumage, 136; Birds and Migration, 139; Laboratory Exercise, 139; Field Work, 141; Review and Library Exercise, 142; Migration in General, 145. _Mammals_: Rodents: Domestic Rabbit, 146; Wild Rabbit, 148; Guinea Pig or White Rat, 149; Squirrel, 150; Library Exercise, 152. _Carnivora_: Laboratory Exercise, 153; Library Exercise, 155. _Ungulates_: Laboratory Exercise, 157; Library Exercise, 160. The Horse, 162. Homology of the Vertebrate Skeleton, 168. CHAPTER VII ADAPTATIONS FOR THE PRESERVATION OF THE SPECIES 170 Methods of Reproduction: Simple or Asexual Method, 170; Complex or Sexual Method, 171. Development: Structure of an Egg, 172; Development of an Egg, 173; Metamorphosis of a Mosquito, 174; Metamorphosis of a Butterfly, 176; Development of the Chick, 177. Protection and Care of Young: Library Exercise, 179. Adaptation for the Preservation of the Species: Review and Library Exercise, 180. CHAPTER VIII POULTRY 182 * * * * * GLOSSARY 189 A GUIDE FOR THE STUDY OF ANIMALS CHAPTER I INTRODUCTORY STUDIES OF LIVING ANIMALS In the following brief exercises the primary purpose is to arouse an active, attentive interest on the part of the pupil in various forms of animal life which may be at hand, reminding him of what and how various creatures eat, how they breathe, how they get ideas of the world, how they get about, and perhaps how they succeed where others fail. Of secondary importance is the introduction of laboratory methods by easy stages. The pupil should feel that his natural curiosity is only being directed to definite ends and that he is free to investigate in his own way.