O. Object of book, 5. Objections from astronomy, 136. Octopods, 77. Offensive remarks of Prof. Vogt, 13. Old, care of the, 192. Old Fuegian women, 192. Omygena exigua, 115. Ophiocephalus, 146. Optic lobes of pterodactyls, 71. Orchids, 92. Orchids, Bee, &c., 55. Organ of hearing, 74. Organ of sight, 76. Organic polarities, 185. Origin of man, 277. Orioles, 90. Ornithoptera, 84. Ornithorhynchus, 175. Orthoceratidae, 170. Orycteropus, 174. Ostracods, 79. Ostrich, 70. Otoliths, 74. Outlines of butterflies' wings, 86. Owen, Professor, 74, 102, 123, 217, 238, 274. Oyster of Mediterranean, 88, 98. Oysters, 79. P. Paget, Mr. J., 182. Palaeotherium, 109. Pallas, 125. Pangenesis, 19, 208. Pangolin, 175. Papilio Hospiton, 85. Papilio Machaon, 85. Papilio Ulysses, 84. Papilionidae, 83. Papuan morals, 197, 198. Parthenogenesis, 217. Passiflora gracilis, 107. Pastrana, Julia, 174. Pathological polarities, 184. Pavo nigripennis, 100. Peacock, black shouldered, 100. Peacock, inflexibility of, 119. Pedicellariae, 44. Pelvis, diseased, 182. Pendulous appendages of turkey, 100. Perameles, 68. Periophthalmus, 146. Perissodactyle ungulates, 109. Permian, jugular fish, 141. Perodicticus, 105, 179. Phalangers, 67. Phasmidae, 89. Phyllopods, 79. Physical actions, 253. "Physiological units," 168, 218. Pigeons' "boots," 181. Placental mammals, 67. Placental reproduction, 81. Plants, tendrils of, 107. Plates of baleen, 40. Platypus, 175. Pleiades, 193. Plesiosaurus, 106, 133, 178. Pleurodont dentition, 148. Pleuronectidae, 37, 166. Plotosus, 147. Poisoning apparatus, 66. Poisonous serpents, 50. Polarities, organic, 184, 185. Political economy, Fuegian, 192. Polyzoa, 80, 81. Pompadour, Madame de, 206. Poppy, variety of, 101. Porcupine, 175. Porto Santo rabbit, 100, 122. Potto, 105, 179. Pouched beasts, 67. Powell, the Rev. Baden, 259, 261, 285. Premolars, 111. Prepotency, 124. Primary intuitions, 251. Primitive man, 204. Problem of origin of kinds, 1. Proboscis monkey, 139. Proboscis of ungulates, 123. Processes, bird's-head, 80. Psettus, 146. Psoriasis, 183. Pterodactyles, compared with birds, 70. Pterodactyles, wing of, 64. Puccinia, 115. Purpose, 259. [Page 295] Q. Quasi-vertebral theory of skull, 172. R. Rabbit of Porto Santo, 100, 122. Radial ossicle, 176. Rarefied air, effect on dogs, 99. Rattlesnake, 49, 50. Red bird of Paradise, 92. Relations, analogical, 157. Relations, homological, 156. Reptiles compared with birds, 70. Retina, 76. Retrieving, virtue a kind of, 189, 205. Reversion, cases of, 122. Rhea, 70. Ribs of Cetacea and Sirenia, 41. Ribs of flying-dragon, 64, 158. Richardson's figures of pigs, 99. Roger Bacon, 266. Rudimentary structures, 7, 102.