INDEX. 



477 



Metamorphosis worms, 189, 190 

 echinoderms, 212; arthropods, 284 

 amphibia, 376, 377 



Metaphase, 23 



Metapleure, 310 



Metathorax, 269 



Metazoa, 140 



Metridium, 167 



Mice, 444 



Micromeres, 227, 249 



Micropyle, 30 



Microstomum, 188 



Migration, 98, 128 ; of birds, 425 



Millipedes, 293 



Mimicry, 122, 386 



Mitmis, 423 



Mink, 443 



Mites, 306 



Mitotic cell-division, 23 



Mocking bird, 423 



Modern birds, 407 



Modiola, 254 



Molar teeth, 432 



Moles, 446 



Mollusca, 138 



Molluscoidea, 195 



Mongrels, 102 



Monkeys, 447 



Monodelphia, 440 



Monomya, 254 



Monotremata, 429, 439 



Morphology defined, 3 



Morula, 34 . 



Mosquitoes, 296, 298 



Moths, 300 



Motion, 69 (see locomotion) ; proto 

 plasmic, 14 



Moulting, 276, 399 



Mouth-parts (arthropods), 263, 269 



Mucous epithelium, 42 



Muscular system coelenterates, 1 74 

 echinoderms, 209 ; annulates, 222 

 mollusks, 243 ; arthropods, 277 

 vertebrates, 342 



Muscular tissue, 52-55 



Mussel, 234, 252, 254 



Mya, 234, 252 



Myctodera, 379 



Myotome, 310, 313, 344 



Myriapoda, 293 



Mytilus, 254 



Nais, 232 



Natatores, 411 



Natural selection, 97 



Nauplius, 289 



Nautilus pearly, 257 ; paper, 258 



Nccturus, 377, 379 



Nemathelminthes, 193 



Neornithes, 407 



Nephridia, 66, 225, 341 



Nereis, 219, 230 



Nervous system, 71-78 (see sense or- 

 gans) ; coelenterata, 175; echino- 

 derms, 21 o ; annulata, 226 ; mollusks, 

 247 ; arthropods, 280 ; vertebrates, 

 344 ; reptiles, 385 ; birds, 401 ; mam- 

 mals, 436 



Nervous tissue, 50, 55 



Nettling cells, 173 



Neurone, 56 



Neuroptera, 296 



Newts, 379 



Nictitating membrane, 352; in birds, 

 401 



Nucleoplasm, 26 



Nucleolus, 20 



Nucleus, 20 ; functions of, 25 



Nutrition, 60 ; protozoa, 147 ; see 

 digestion, metabolism, etc. 



Nutritive pole, 32 



Obelia, 177 



Ocelli, 281 



Occulina 168 



Octopoda, 259 



Octopus, 257 



Odontophore, 244 



CEsophagus, 332 



Oil glands, 323 



Olfactory nerves, 349 



Oligochaeta, 231 



Ommatidium, 282 



Oniscus, 265 



Onychophora, 292 



Ophidia, 389 



Ophiuroidea, 214 



Optic nerve, 349 



Orb-weavers, 304 



Organization, 18, 44, 60; of protozoa, 



147 



Organs, 60 

 Origin of tissues, 56 

 Original home of animals, 129 

 Ornithodelphia, 439 

 Ornithorhynchus, 439 

 Orthoceratites, 259 

 Orthoptera, 294 

 Oscines, 422 

 Osculum, 159 

 Osmerus, 366 

 Osseous tissue (bone), 49 

 Ostrea, 254 

 Ostrich, 408 



Otocyst, 75 (see also auditory organs) 

 Otolith, 75 



