

722 



INDEX 



Okapi, 671. 



Olfactory, capsule, 416, 418; chamber, 

 482, 483; lobes, 501, 502; pits, 131, 

 397, 399J sac, 440 (see nervous sys- 

 tem and sense organs). 



Oligocene, 686, 697. 



Oligoc/nela, 236. 



Ommastrephes, 268. 



Ommatidium, 285, 286. 



Ommosternum, 495, 496. 



Omnivorous, 21. 



Oncorhynchus, 461. 



Oniscus, 296, 297, 301. 



Onit/ioc/iiton, 252. 



Ontogenesis, 302. 



Onychophora, 275, 305-308. 



Oocytes, 82, 83, 84. 



Ooecium, 184. 



Oogenesis, 82, 83, 84. 



Oogonia, 82, 83. 



O patina, 63. 



Operculum, 433, 439. 



Ophibolus, 562. 



Ophidia, 538. 



Ophioglypha, 200, 201. 



Ophiopluteus, 210, 211. 



Ophisaurus, 556. 



Ophiura, 189. 



Ophiuroidea, 189, 199-201. 



Opislhobranchia, 258. 



OpislhocomidcE, 590. 



Opisthoglypha, 539, 563. 



Opossum, 642, 647, 648. 



Optic, chiasma, 501, 502 ; lobes, 501, 502 

 (see nervous system). 



Optinum, in behavior, 44, 57. 



Oral, groove, 53; hood, 396, 397; lobe, 

 123, 130; papillae, 306. 



Orang-utan, 644, 665. 



Ore a, 675. 



Order, 22. 



Oreamnos, 670. 



Organization, 9-10. 



Organs, 76 ; analogous, 76 ; homologous, 

 76; systems of, 76-79. 



Origin of muscles, 497. 



Oriole, 593. 



Ornithorhynchus, 642, 646. 



Orohippus, 700. 



Orthonectidce, 176, 177. 



Orthoptera, 337, 343, 344, 345. 



Orycteropus, 644. 



O seines, 616. 

 Osculum, 93. 

 Osmosis, 220. 

 Osphradium, 249. 

 Osprey, 605. 



Ossicle, ambulacra!, 191, 192. 

 Ostariophysi, 443. 

 Osteolcemus, 548. 

 Ostia, 94, 135. 



Ostracoda, 293, 294, 299, 300. 

 Ostrea, 262, 263. 

 Ostrich, 589, 595, 596. 

 Otariidce, 657. 

 Otoes, 657. 

 Otter, 655. 



Ovary, 490,491 (see reproductive system) . 

 Ovibos, 670, 671. 



Oviduct, 490, 492 (see reproductive sys- 

 tem). 



Oviparous, 80, 413. 

 Ovipositor, 330. 

 Oiris, 670, 685. 

 Ovum, 75. 

 Ovotestis, 254, 257. 

 Owl, 591, 611, 612. 

 Ox, 684. 

 Oxyglossus, 512. 

 Oxyrhopus, 539. 

 Oxytricha, 65. 

 Oyster, 263, 271; drill, 260. 



Pachyderms, 672. 



Pasdogenesis, 80. 



Palcemon, 289, 290. 



Palamonetes, 297, 299, 301. 



Palceospondylus, 421. 



Palamedeida, 590, 603. 



Palapteryx, 597. 



Palate, 637. 



Palatine, 493, 494. 



Paleontology, 26. 



Paleozoic, 697. 



Palinurus, 297. 



Pallium, 246. 



Palp, 313- 



Palpigradi, 382. 



Paludicola, 512. 



Paludina, 271, 272. 



Pan, 665, 666. 



Pancreas, 401, 402, 406, 481, 638. 



Pandion, 605. 



Pangolin, 643, 66 1, 662. 







