CONTENTS. 



Preface i 



Contents 3 



Maps Illustrating the Distribution of Species and Sub- 

 species Belonging to t'he Genera Represented within 

 our Limits in the Eastern United States and Southern 



Canada 7 



Introduction 9 



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 19 



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 or 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 



