INDEX 



939 



Oestrin. 676 



Oligochaeta, 194, 196. 199 

 Omasum, 633 

 Ommatidia. 277, 302 

 Ommatidium. 276 

 Omosternum, 521 

 Onchocerca volvulus. 745. 746 

 Oniscus. 282 

 Ontogeny. 113. 285 



recapitulates phylogeny. 870 

 Onychophora, class, 265. 287 

 Oocyst, 74 



Oocyte, secondary, 115 

 Ooecium, 185, 187 

 Oogenesis, 113. 114 

 Oogonia, 114, 799 

 Ookinete, 74 

 Opalina, 70, 745 

 Operculum, 537 

 Opliichthyidae, family, 449 

 Ophidia, suborder, 548, 556 

 Ophioderma, 219 

 Ophiothrix, 219 

 Ophisaurus, 552 

 Ophiura, 219 

 Opliiuroidea, class, 219 

 Opisthobranchiata, 258 

 Opisthoglypha, 556 

 Opisthotic bone, 494 

 Opossum. 619 

 Optic chiasma. 526 



ganglion. 262 



lobes. 469 

 Oral groove. 93 



hood, 370 



lobes, 138 



ossicles, 229 

 Orangutan. 636. 637 

 Orcinus orca, killer whale. 634 

 Oreamnos montanus. 631 

 Oreaster, 218 

 Organ. 108 



of corti. 403, 650 

 Organ pipe coral, 143 

 Organic catalysts, 57 

 Organizers. 694 

 Organogenesis. 801 

 Organs and system. 817 

 OrioTital region. 712 

 Origin of species, 43, 863 

 Ornithorhynchus anatinus. 617 

 Orohippus. 874 

 Orthoceracone, 259 

 Orthoptera, order, 265. 313 

 Orytricha. 71 

 Osculum. 122 

 Osmeridae. family, 448 

 Osphradium, 253 

 Ospreys, 589 

 Ossicles. 227. 228 

 Osteoblasts. 691 

 Ostia, 122. 124. 273 

 Ostium. 531, 573. 652 

 Ostracoda. order, 204, 284 

 Ostraea virginica, oyster. 771 

 Ostrich. African. 584. 585 

 Otocyst. 237, 367 

 Otter. 638 

 Otus asio. 593 

 Ova, 104 



Ovarian follicle. 812, 813 

 Ovaries of cat, 6i>2 

 Ovary of hen, 614 

 Ovibas mo.schatus. musk ox. 631 

 Oviducts. 407 



of frog. 531 

 Oviparous. 407 

 Ovipositor. 348 



Ovis canadensis, mountain sheep, 630 



Ovotestis, 243 



Ovoviviparous condition, 248. 487 



Ovum. 652 



Owls, 593 



barred or hoot, 593 



great horned, 593 



prairie dog. 592 



screech. 593 

 Oxyechus vociferus. 590 

 Oyster drill. 241 



extinct. 854 



shell, 771 

 Oysters, 255 ' 



Pacific shore animals, 774 

 Paddlefishes, 446 

 Pagurus, 282 



hermit crab. 772 

 Palaearctic region. 712 

 Palatine bones. 517 

 Paleontology, 854 

 Paleozoology, 24 

 Pallial line, 249, 250 

 Palpigradi, order, 266 

 Palps, 197 



labial, 250 

 Palpus, 305 

 Pancreas, 490, 677 

 Panaorma. To 

 Panther. 629 

 Pantothenic acid, 390 

 Papillae, filiform, 603 



fungiform, 650 



vallate, 650 

 Papula, 226 



Parabacillus coloradus, 318 

 Paragastric canals. 158 

 Paragonimus, 161, 760 

 Paragordius, 178 

 Parakeets, 591 

 Paramecium, 70,93, 100 



locomotion. 102 



metabolism. 95 



reaction to temperature. 100 



reproduction, 96. 98 



structure. 93 

 Paramylum. 83 

 Paramj-xine. 412 

 Parapodia. 196 

 Parapophyses. 465 

 Parapsida, subclass. .547 

 Parascalops breweri, hairy-tailed mole, 



619 

 Parasite, accidental, 736 



occasional, 736 

 Parasites, facultative, 737 



their transmission, 740 

 Parasitism, 735 



Parasphenoid bone, 465, 495, 518 

 Parathormone, 670 

 Parathyrin. 670 

 Parathyroid glands, 670 

 Parenchyma, 105 

 Parietal bone, 465, 494 

 Parotoid gland, toad, 540 

 Parrots, 591 



Parthenogenesis, 112, 191. 410 

 Parthenogonidium. 76 

 Passalidae. family. 335 

 Passalus cornutus. 335 

 Passenger pigeon, 591. 786 

 Passeriformes. order, 595 

 Pasteur, 47 

 Patella, 240. 293. 644 



larva. 237 



