Pigeons, pouter, 120. Pigeons, tumbler, 120. Pigeons, white-headed fruit, 131. Pines, 100, 102, 245. Pisces, 234, 236. Plagiostomi, 236. Plants, land, 96, 97, 99, 100. Plants, flowering, 100, 110, 244. Plants, flowerless, 100, 244. Plants, generalized, 102. Plants, unicellular, 4. Plants, multicellular, 4. Plastids, 5. Platyhelminthes, 232. Platyrrhinæ, 241. Pleuracanthus, 103. Pliohippus, 113. Plovers, 131. Polar bodies, 29. Polyodon, 237. Polyps, 32, 231. Polypterus, 236. Polytheism, 210. Poplars, 245. Porifera, 25, 230. Pouter, 120. Preferential mating, 157, 159, 169. Primates, 239. Primitive man, 187. Primrose, 163. Proboscidea, 239. Pronucleus, female, 29, 31. Pronucleus, male, 29, 31. Prosencephalon, 199. Protective Imitation of Particular Objects, 138. Protective Resemblance, 128. Proteus, 237. Protohippus, 113. Protophyta, 244. Protoplasm, 4, 5, 33, 44. Protopterus, 237. Protozoa, 229, 230. Protozoa, flagellate, 24, 25. Protozoa, colonial, 22, 25. Pseudo-heredity, 53. Pseudopodia, 12. Psychic phenomena, 207. Ptarmigan, 131. Pteridophyta, 244. Pterosauria, 107, 109, 238. Ptilopus cinctus, 131. Quadrula, 17, 230. Recognition Marks, 150. Reducing process, 46. Redwood, 111. Regeneration of lost parts, 50. Reptiles, 96, 104, 106, 107, 109, 110, 152, 157, 235, 238. Reptiles, Age of, 110. Reptiles, generalized, 104, 107. Reptiles, land, 107. Reptiles, sea, 107. Reptiles, extinction of, 125. Reptiles, of bat-like form, 107. Reptiles, of lizard-like form, 104. Rabbit, 151. Radiolaria, 97. Ratitæ, 238. Raven, 132. Rays, 106, 236. Recognition Marks, 128, 150, 169. Religion, 221, 222. Rhinencephalon, 199. Rhinoceros, 112. Rhizopoda, 230. Ribs, 194. Rocks, table of stratified, 95. Rodentia, 239. Rotalia, 13, 23. Rotatoria, 232. Rotifer, 232. Ruminants, 111, 137. Rupture, 190. Saitis pulex, 156. Salamanders, 103, 147. Salamandra, 237. Salmons, 157, 158, 237. Saururæ, 238. Scaphopoda, 234. Scorpions, 99, 233. Sea, Cretaceous, 68. Sea, Palæozoic, 86. Sea-anemones, 231. Sea-cucumbers, 232. Seals, 160. Seaweeds, 96, 97, 244. Sea-urchins, 97, 99, 232. Selfishness, 216. Selection, artificial, 120, 121. Selection, insect, 160, 164. Selection, natural, 119, 120, 122, 124, 131, 132, 134, 137, 138, 141, 143, 147, 149, 152, 153, 158, 160, 162, 165, 225. Selection, physiological, 169. Selection, rational, 214. Selection, sexual, 152, 153, 154, 157, 158, 164. Sharks, 106, 107, 109, 235. Sharks, primitive, 100. Sheep, 121. Sheep, heath, 169. Sheep, merino, 169. Shrimps, 103, 233. Simia, 243, 244. Simiidæ, 242, 243, 244. Simiinæ, 244. Sinus venosus, 236. Siredon, 62, 63. Siren, 237. Sirenia, 239.