INDEX 



553 



Muscular tissue, 59-61 

 Mussel, 253, 255, 240, 258 

 Mutahilia, 384 

 Mutation, 104, 108, 489 

 Mya, 240, 2S7 

 Myctodera, 384 

 Myotome, 314, 346 

 Myriapoda, 297 

 Mytilus, 259 



Nats, 239 



Natural history, 520 



Natural selection, 105 



Nauplius, 294 



Nautilus — pearly, 262; paper, 264 



Necator, 201 



Necturus, 381, 384 



Nemathelminthes, 200 



Nemertinea, 204 



Neornithes, 411 



Nephridia, 72, 73, 232, 345 



Nereis, 22,6, 237 



Nervous system, 77-84 (see sense or- 

 gans); coelenterata, 183; echinoderms, 

 218; annulata, 232; mollusks, 252; 

 arthropods, 284; vertebrates, 348; 

 reptiles, 389; birds, 406; mammals. 



447 



Nervous tissue, 61, 62 



Nettling cells, 182 



Neuron, 62 



Neuroptera, 299 



Newts, 384 



Nictitating membrane, 356; in birds. 

 406 



Notochord, 312, 329 



Nucleoplasm, 27 



Nucleolus, 21 



Nucleus, 21; functions of, 26 



Nutrition, 67; protozoa, 155; see di- 

 gestion, metabolism, etc. 



Nutritive pole, 37 



Obelia, 186 

 Ocelli, 286 

 Occulina, 177 

 Octopoda, 260 

 Octopus, 263, 264 

 Odonata, 299 

 Odontophore, 245, 249 



CEsophagus, 335 



Oil glands, 327 



Olfactory nerves, 353 



Oligochaeta, 238 



Ommatidium, 286 



Oniscus, 270 



Onychophora, 297 



Oocytes, 32, 33, 34 



Oogonia, 32, 33, 34 



Ophidia, 394 



Ophiuroidea, 221 



Optic nerve, 353, 356 



Orb-weavers, 308 



Organization, 19, 48, 66; of protozoa, 154 



Organs, 67 



Origin of tissues, 48 



Original home of animals, 137 



Orioles, 421 



Ornithodelphia, 450 



Ornitkorhynchus, 450 



Orthoceratites, 263 ^ 



Orthoptera, 298 



Oscines, 430 



Osculum, 166 



Osmerus, 371 



Osseous tissue (bone), 57 



Ostrea, 260 



Ostrich, 412 



Otocyst, 82 (see also auditory organs). 



Otolith, 82 



Otter, 455 



Ovary, 75, 287, 345 



Oviduct, 253, 287, 345, 407 



Ovipositor, 273 



Oviparous, 346 



Ovum, 30 



Owls, 420, 421, 422 



Ox, 454 



Oxidation, 17, 69 



Oysters, 243, 257, 260 



Palcemonetes, 296 

 Palaeontology, 480 

 Palaeozoology, defined, 5 

 Paludicolae, 418 

 Papilio, 306 

 Paramecium, 150, 154 

 Parapodia, 237 



Parasitic worms, — cycle of, 207 

 Parasitism, 130, 196, 204, 206 



