290 



FROM FISH TO PHILOSOPHER 



Onychopus gigas, 93 



Opossum, 133 



Opsanus, see Toadfish 



Ordovician, 57 



Oreopithecus, 182-83 



Origin of Species, 11, 222 



Orogeny, 6 



Osmotic balance, see Water 

 balance 



Osmotic pressure, 29 



Osteoblasts, 54 



Osteolepis, Figure 7 



Osteostraci, 27 



Ostracodenn armor, defen- 

 sive role, 35, 237 



Ostracoderms, 53-55. see 

 ALSO Figure 4 



Ouachita disturbance, 86 



Ovoviviparous fishes, 250 

 reptiles, 128 

 sea-snakes, 172 



Ovoviviparity, 66 



Paddlefish (Polyodon), 112 



Paedogenesis, 183 



Paget, Sir James, 205, 208 



PAH, see p-Aminohippuric 

 acid 



Paleozoic, 8, 21 f. 



Pampiniform plexus, 43 



Pantotheria, 133 



Pelican (Pelecanus)y 169 



Pelycosauria, 132 



Penguin, Humboldt (Sphen- 

 iscus), 169 



Pennsylvanian, 85 f . 



Perak River, 68 f . 



Periophthalmus, see Mud- 

 skipper 



Permian, ii8f. 



and Amniotes, 121-22 



climate, 135 



Perognathus, 156 



Personality, 225 



Petrel (Oceanodroma), 169 



Petromyzon, see Lamprey 



Piano playing, speed of, 205- 

 11 



Pineal eye, 54, 9^7, ^57 

 gland, in Cartesian philos- 

 ophy, 198 



Pipefish, 106, 113 



Pithecanthropus, 181-82 



Pituitary, 257 f. 

 Amphibia, 97 

 ostracoderms, 54 



Placodermi, 55 



Plasma, blood, 1 



Platypus, see Duckbill 



Plesianthropus, 182 



Plesiosaurs, 126-27 

 marine, 173 



Pleurancanthodii, 67 



Poikilothermia, 134 



Polyodon, see Paddlefish 



Polypterus, see Bichir, Nile 



Pongidae, 179 



Prairie dog, 156 



Preadaptation, 18 f. 



Predatory habitus and con- 

 sciousness, 213 f. 



Pressures in the earth, 4 



Pristis Microdon, 68, 254 



Progress in evolution, 17 f. 



Pronephros, 38 



Protista, 22 



Protopterus, 72, 252-53 

 estivating, Figure 7 



Proto vertebrate, 21, 25, 33 

 bibliography, 230 

 hypothetical, Figure 4 

 nervous system, 188 



