Hypostome, 23. Ichneumon fly, 89. Imago, 81. Infusoria, 16. Inorganic, 1. Insecticides, 95. Insects, 73, 75; biting, 82; classified, 82; sucking, 82. Instinct, 80, 121. Jacana, Mexican, 178. Jay, blue, 181. Jelly fish, 29, 30. Kangaroo, 198. Kidneys, of fish, 117; of insects, 76; of mussel, 102; of worm, 45. Labial palpi, 68, 74, 101. Labium, 68, 74. Labrum, 68, 74. Lady bug, 91. Lamellibranch, 107. Lark, meadow, 182; sky, 179. Larva, 81. Lasso cell, 34. Leg, of bird, 152; of horse, 210; of insect, 74. Lemur, 220. Lepidoptera, 82, 87. Louse, 92, 93. Lungs, of bird, 165. Madreporite, 35. Mammal, 184; classified, 193; defined, 189. Manatee, 209. Mandibles, 68, 74. Mantis, praying, 3. Mantle, 99. Maxillæ, 68, 74. Maxillary palpi, 68, 74. May beetle, 90, 91. May fly, 83. Measuring worm, 81, 84. Medusa, 31. Mesoglea, 26. Metamorphosis of insect, 80, 81, 82. Metazoan, 1. Migration of birds, 171, 173. Mimicry, 146. Moccasin, 145. Mole, 201. Mollusc, 9, 97, 125. Moulting, 69, 174. Monkey, 220. Morula, 7. Mosquito, 92, 93, 96. Moth, 83. Mother-of-pearl, 99. Mussel, 96, 103. Nautilus, chambered, 107. Nectar, 8. Nephridium, 45. Nervous system, of bee, 78; of mussel, 102. Nest building, 166, 182. Neuroptera, 82. Nostril, of bird, 151; of fish, 112. Nucleolus, 6. Nucleus, 6, 11, 14. Octopus, 106. Okapi, 214. Omnivorous, 47. One-celled animals, 7. Opossum, 197. Oral surface, 35. Orang, 227. Order, 9. Organ, 1. Organism, 1. Orthoptera, 82. Osculum, 18. Ovary, 25, 37, 117. Oviduct, 46. Oxidation, 3, 4, 5. Oxygen, 4, 5. Oyster, 104. Paramecium, 13. Parasites, 49, 93. Partridge, 178. Pearls, 105. Peccary, 217. Perch, 109, 110, 123. Pests, insect, 93. Pheasant, 174. Plastron, 141. Pollen, 85. Pollen basket, 88. Polyp, 9, 22, 125. Portuguese man-o’-war, 28. Potato bug, 90. Primates, 220. Proboscis, of butterfly, 83, 87; elephant, 207. Prolegs, 84, 87. Protection of birds, 171. Protective resemblance, 34, 146. Protoplasm, 6, 11. Protozoa, 7, 9, 11, 125. Pseudoneuroptera, 82. Pseudopod, 11. Quill, 156. Rabbit, 205, 223. Radial symmetry, 34, 125. Rattlesnake, 145. Rectum, 134. Regeneration of lost parts, 37. Reproduction, 12, 15, 20, 25, 37, 46, 120. Reptiles, 139. Rhizopoda, 16. Road runner, 169. Robin, 183. Rotifer, 49. Round worm, 49. Ruminant, 213. Salamander, 134, 138, 139. Sandworm, 49. San José scale, 95. Scab in sheep, 95. Scales, of bird, 161; fish, 110; moth, 89. Scallops, 104. Scarab, 90, 91. Sea anemone, 33. Sea fan, 32. Sea horse, 124. Sea urchin, 38. Senses of insects, 76. Setæ, 43, 48. Sexual selection, 174. Shark, 121. Silkworm, 84, 86, 95. Silver scale, 83. Siphon, 101. Siphonoptera, 82.