CONTENTS. 



PREFACE J 



CONTENTS - 3 



MAPS ILLUSTRATING THE DISTRIBUTION OF SPECIES AND SUB- 

 SPECIES BELONGING TO THE GENERA REPRESENTED WITHIN 

 OUR LIMITS IN THE EASTERN UNITED STATES AND SOUTHERN 



CANADA 7 



INTRODUCTION . g 



THE OSSEUS SYSTEM . 10 



Skull, 13; Teeth, 13; Vertebral Column, 15; Pelvis, 15; Ribs, 



15; Sternum, 15; Scapula, 16; Clavicle, 16; Limbs and Feet, 16. 



ANATOMICAL AND PHYSIOLOGICAL CHARACTERS IN GENERAL . 17 



Tegumentary Structures 18 



Hoofs, Claws and Nails, 18; Hair, 18; Odor-secreting Glands, 

 19. 



Circulatory and Digestive Systems IQ 



Heart, 20; Lungs, 21; Blood, 21; Stomach and Intestinal 

 Canal, 22; Liver, 23. 



Urinary Organs ; 23 



Reproductive Organs 23 



Mammary Glands . 24 



Nervous System and Organs of Sense . 24 



Brain, 24; Spinal Chord, 24; Sense of Touch, 24; Sight, 25; 

 Smell, 26; Hearing, 26; Taste, 26. 



TAXONOMY AND CLASSIFICATION 27 



SUBCLASSES, ORDERS AND SUBORDERS OF LIVING MAMMALS . . 28 

 CLASSIFIED LIST OF MAMMALS OF ILLINOIS AND WISCONSIN . 30 



How TO ESTIMATE THE AGE OF A MAMMAL 37 



How TO MEASURE A MAMMAL 37 



LIFE ZONES 38 



KEY TO THE ORDERS AND FAMILIES REPRESENTED WITHIN OUR 



LIMITS 41 



Key to the Orders . . . . . . . ... . .41 



Key to the Families 41 



ORDER MARSUPIALIA. MARSUPIALS 49 



Family Didelphiidae. Opossums -. . . . 51 



3 



