Molar Teeth of the Marmot--The Striped Spermophile, or Gopher 92 Burrows of the Prairie Dog 93 The Alpine Marmot 95 The Fulgent Anomalure--Molar Teeth of the Anomalure 96 Molar Teeth of the Beaver 97 The Beaver 98 Molar Teeth of the Dormouse--The Dormouse 102 The Garden Dormouse 103 Skull of Lophiomys--The Lophiomys 104 Molar Teeth of the Black Rat 105 The Brown Rat 106 The Black Rat 107 Harvest Mice 109 Molar Teeth of the Hapalote 111 Head of the Rabbit-like Reithrodon 112 Hamster _To face page_ 113 Molar Teeth of the Hamster 113 Molar Teeth of the Gerbille--Skull of the Water Mouse--Teeth of Sminthus 114 Molar Teeth of the Water Rat 115 The Southern Field Vole 116 The Musquash 118 The Lemming 119 Skull of Mole-Rat--The Mole-Rat 121 Molar Teeth of the Mexican Pouched Rat--Under Surface of the Head of Heteromys 122 Skull of the Mexican Pouched Rat 123 Skull of the Cape Jumping Hare 124 The American Jumping Mouse--Molar Teeth of the Jerboa 125 The Jerboa 126 The Alactaga--Molar Teeth of the Jumping Hare 127 The Cape Jumping Hare 128 The Degu 129 Dentition of the Rock Rat--Teeth of the Spiny Rat 130 The Coypu 131 The Hutia Conga--Teeth of Plagiodon--Molar Teeth of Loncheres 132 Skull of Loncheres 133 Skull of the Porcupine--The Common Porcupine 134 The Tree Porcupine 136 Mexican Tree Porcupines 137 Viscachas _To face page_ 139