716 



Index 



Oogonium, 275 



Ookinete, 365 



Ootid, 275 



Ootype, 413, 417 



Operculum, 385, 583 



Opheodrys, 609 



Ophisaurus, 607 



Ophiura, 544, 553 



Ophiuroidea, 544, 549 



Opiliones, 514, 515 



Opisthorchis, 411-414 



Opossum, 292, 628, 629, 632, 633 



Optic chiasma, 69, 199 



lobes, 69, 197 



nerves, 69, 200, 205, 218 

 Oral end, of ctenophore, 399 

 of echinoderms, 542, 545 

 of hydra, 386 

 Oral groove, 369 



hood, 564 

 Orbit of eye, 55, 56, 57, 102 

 Order, 44 



Ordovician period, 343, 567 

 Oreaster, 553 

 Organ, 40 



grade of organization, 344 



of Corti, 222, 223 

 Organelle, 349, 350 

 Organic chemistry, 30-32 

 Organization, 24 

 Organizer, 294, 295 

 Organogeny, 287-289 

 Origin, of muscles, 117 



of species, 320, 322, 323, 327 

 Oriole, 621 



Ornithischia, 604, 613 

 Ornithology, 21 



Ornithorhynchus, 627, 629, 631, 632 

 Orthogenesis, 330-331 

 Orthoptera, 44, 521, 538 

 Orycteropus, 630, 632, 638-639 

 Osculum, 377, 379 

 Osmosis, 34-35, 36, 269 

 Osmotic equilibrium, 235 



pressure, 160, 186 

 Ossicle, 545j 549 

 Ostariophysi, 590 

 Osteichthyes, 46, 567. 568, 575, 581-591 



characteristics, 582 



classification, 582-583 



orders, 588-591 

 Osteoblast, 96, 97, 232 

 Osteostraci, 570 

 Ostium of insect heart, 525 



of Metridium, 396 



of sponge, 377, 378 



tubae, 73 

 Ostracion, 589, 590 

 Ostracoda, 506, 508 

 Ostracoderm, 567, 568, 570, 574 



Ostrich, 619, 620, 623, 624 

 Otolith, 223, 224 

 Otter, 256 



Outbreeding, 316, 317 

 Ovarian cycle, 263 

 Ovariole, 526, 527 

 Ovary, 61, 72, 241-243 



cortex, 242 



medulla, 242 

 Oviduct, 61, 73, 242, 260 

 Oviparous, 254, 602 

 Ovipositor, 523, 527 

 Ovoviviparous, 254, 602 

 Ovulation, 242, 250, 262 

 Ovum (sec Egg) 

 Owl, 623, 624, 625 

 Oxidation, 147, 228 

 Oxygen, 26, 29, 147, 177 



debt, 121 

 Oxyhemoglobin, 154, 177 

 Oyster, 468, 471, 476, 477, 548, 549 



drill, 471 



Paddlefish, 569, 582, 589, 590 



Paedogenesis, 254, 520 



Pagurus, 507 



Pain, 213 



Painted turtle, 605, 606 



Palaeognathae, 623, 625 



Palaeoniscid, 569 



Palate, hard, 103, 130, 131, 149 



soft, 131 

 Palatines, 57, 103 

 Paleontology, 325 



Paleozoic era, 343, 509, 511, 568, 569 

 Pallial line, 472 

 Palolo worm {sec Eunice), 449, 



453-454 

 Palps, 450, 521, 522 

 Palpus, 512, 513 



Pancreas, 60, 72, 137, 142, 237-240 

 Pancreatic juice, 137, 138, 139, 140, 



141, 237 

 Pancreozymin, 140, 141, 142, 248 

 Pandorina, 356, 644 

 Pangene, 327 



Pangolin, 85, 630, 632, 635 

 Panulirus, 507 

 Papilla, of kidney. 187, 188 



of tapeworm, 418 

 Papillae, 80 

 Papillary layer, 80, 82 



muscles, 63, 163 

 Paragonimus, 414 

 Paragordius, 442 

 Parakeet 624 

 Paralichthys, 588, 589, 590 

 Parallel evolution, 336 



i 



