638 



ANIMAL BIOLOGY 



Ophiuroidea, 204-206 



(See also Brittle stars) 

 Opossums, 431, 534, 537 

 Optic lobes, 334, 343, 346, 347, 367, 375, 376, 387, 



408, 427 

 Optic nerves, 227, 260, 261, 339 

 Optic tract, 408 

 Optimum, 141 

 Oral funnel, 316, 317 

 Oral groove, 69, 70 

 Oral hood, 320, 321 

 Oral papilla, 273 

 Oral ring, 320 

 Oral sucker, 168, 379 

 Oral tentacles, 209 

 Oral valves, 368, 359 

 Orang-utan, 449, 534 

 Order, 59 



Ordovician period, 539—543 

 Organ-pipe coral, 164 

 Organelles, 85, 463 

 Organic matter, 17 

 Organismal concept, 462 

 Organisms, 17 



animal, 457-462 



behavior, 497-504 



compared to engine, 481 



compared to fire, 480 



definition, 457 



development, 475-479 



energy changes, 480-485 



function, 486-496 



in health and disease, 515-520 



infective, 517 



inheritance, 555-569 



relations between, 521-526 

 Organization, 17, 21, 23, 24, 28, 166 

 Organogeny, 122, 478 

 Organs, 104-106, 122, 123, 160-163, 166, 463-464 



adrenal, 492 



of Corti, 337 



hydrostatic, 350 



and systems, 104—106, 464 

 Origin, muscle, 471 

 Origin, of life, 26 



birds and flight, 410 

 germ cells, 475 

 mammals, 429 

 Bex cells, 109-113 

 species, 545 

 Orioles, 419 

 Ornithology, 5 

 Ornithomimus, 411 

 Ornithorhynchus anatinus, 431 

 Orthogenesis, 551 

 Orthoptera, 288 

 Osborn, H. F., 27 

 Oscula, 130-132 

 Osmosis, 12, 13, 35 

 Osmotic pressure, 12 

 Osphradium, 217 

 Ossicles, 196, 207, 338 



(See also Ear) 

 Ostia, 130-132, 146, 147 

 Ostracoda, 267, 268 



Ostracoderms, 642 

 Ostriches, 409, 419, 420, 534 



egg, 418 



foot, 413 

 Otocyst, 318 

 Otter, 436 



Outer chamber, eye, 338 

 Outer ear, 336-338, 424 

 Ovary, 137, 142, 162, 163, 168-170, 176, 179, 240, 



303, 323, 331, 408, 460, 470, 493 

 Oviduct, 162, 163, 169, 240, 303, 323, 331 

 Oviparity, 108 

 Oviposition, 286 

 Ovipositor, 277, 292 

 Ovum, 31, 109 

 Owen, 582 

 Owls, 414, 415 



barn, 416 



burrowing, 537 

 Ox, musk, 439, 537 

 Oxidases, 480 

 Oxidation, 39 



Oxidations in body, 39, 480 

 Oxygen, 19, 458, 480, 484, 488, 491 

 Oxygen cycle, 488 

 Oxyhemoglobin, 236, 330, 491 

 Oyster drill, 229 

 Oysters, 202, 225, 230 



P generation, 669, 660, 663 



Paddle plates, 156, 574 

 Pain, 473, 501, 502 



receptors, 334 



spots, 473 

 Paired characters, 556 

 Paired units, 557 

 Palaeomastodon, 662 

 Palate, 336 



hard, 426 



soft, 328, 426 

 Palatine bone, 398 

 Palearctio region, 535 

 Paleontology, 538 

 Paleozoic era, 539, 541, 542 

 Paleozoology, 5, 538-543, 548 

 PalUal hne, 213, 214 

 Pallium, 214 

 Palolo, worm, 253, 264 

 Palpi, insects, 248, 277, 278 

 Palps, 214, 216, 248 

 Pancreas, 99, 323, 329, 346, 459, 492 

 Paper nautilus, 228 

 Paralysis, 565 

 Paramecium, 69-77, 82 

 Paramecium aurelia, 77 

 Param.ecium, caudatum, 69, 70, 76, 77 

 Parapodia, 248, 575 

 Parasites, 29, 172, 174, 506, 524 



(Sec also Human parasites, and individual 

 types) 

 Parasitism, 168, 169, 172-177, 363, 524-526 

 Parasitology, 5 

 Parathyroids, 492, 493 



