INDEX. 



681 



Olyntlius. 222 



Omasum, 642 



Omentum, 546 



Ommastrephes, 3S8, 395 



Ommatidium, 405 



Oncosphaera, 283 



Oniscidie, 442 



Oniscus, 442 



Ontogeny, 3, 160 



Oospore, 185 



Ootype, 272 



Opalina, 209 



Opercular ttones, 562, 566 



Opercularella, 242 



Operculum, 210, 323, 371, 440, 566 



Ophidia, 600 



Opliidiaster, 334 



Ophiocoma, 338 



Opliiocnida, 338 



Ophioglypha, 338 



Ophiopliolis, 338 



Ophiothelia, 338 



Ophisaurus, 599 



Ophistliotic bone. 522 



Ophiuroidea, 337 



Opisthobranchia, 381 



Opisthocoelous, 519 



Opisthopatus, 458 



Opossums, 633 



Opossum shrimp, 42S 



Opoterodonta, 601 



Optic ganglion, 129 



Optic lobes, 534 



Optic nerve, 536 



Optic stalk, 541 



Optic thalami, 534 



Optic vesicle, 541 



Oralia, 330, 340 



Orang-utan, 651 



Orange scale insect, 490 



Orbitelarife, 453 



Obit(jsphenoid bone, 522 



Orchestia, 438, 439 



Order, lo 



Organic bodies, 133 



Organisms, f)rigin of, 139 



Organ-pipe coral, 259 



Organs, 99 



Organs, animal, loi, 121 



Organs, of assimilation, 102 



Organs, auditory, 127 



Organs, of Bojanus, 363 



Organs, circulatory, 109 



Organs, of Corti, 543 



Organs, digestive, 103 



Organ, dorsal, 341 



Organs, electric, 563 



Organ? of equilibrium, 128 



Organs, excretory, 115 



Organs, excretory, of vertebrates, 550 



Organ of Jacobson, 539 



Organs of hearing, 127 



Organs, lateral line, 537 



Organs, olfactory, 126 



Organs, pearl, 558 



Organs, respiratory, 107 



Organs, sensory, 125 



Organs, sexual, 117 



Organs, sexual, of vertebrates, 550 



Organs of smell, 126 



Organs, systems of, 100 



Organs, tactile, 125 



Organs, of taste, 126 



Organs, of touch, 537 



Organs, vegetative. lOI, 102 



Oriental region, 176, 178 



Orioles, 616 



Ornithodelphia, 631 



Ornithorhynchidce, 632 



Ornithorhynchus, 631, 632 



Orohippus, 643 



Oronasal groove, 53S 



Orthis, 328 



Orthoceras, 394 



Orthonectida, 220 



Orthoneurous, 374 



rjrthopoda, 597 



Orthoptera, 480 



Orycteropus, 636 



Oscarella, 227 



Oscines, 616 



Osculum, 222, 225 



Os en ceinture, 581 



Ossein, 86 



Os transversum, 590 



Os turbinale, C20 



