_Metriorhynchus_, _39_, 278 Microchiroptera, _49_; general characters, 371 _Microgale_, _49_; caudal vertebrae, 454 Mid-digital quill, duck, 303 Milk-teeth, 344; dog, 377; horse, 430 Moa, _40_, _299_; aftershaft, 328; pectoral girdle, 336; wing, 338 Molar teeth, 344; dog, 376 f. Mole, _49_, _370_; auditory ossicles, 488; cervical vertebrae, 446; humerus, 503; manus, 512; presternum, 490; shoulder girdle, 499; skull, 481; teeth, 440; Golden --, _49_; see _Chrysochloris_; Marsupial --, _43_; see _Notoryctes_ _Molge_, _35_, _135_; see Newt Monitor, _38_; see _Varanus_ Monkey, _49_, _373_; see under Primates Monodelphia, _43_; characters of, 351 _Monodon_, _45_, _357_; see Narwhal Monophyodont, defined, 7, 344 Monopneumona, _34_ Monotremata, _42_; arm bones, 499; auditory ossicles, 486; caudal vertebrae, 453; cervical vertebrae, 443; general characters, 346; manus, 504; pectoral girdle, 493; pelvis, 513; pes, 521; ribs, 490; sacral vertebrae, 451; skull, 455; sternum, 489; teeth, 422; thigh and shin, 517; thoraco-lumbar vertebrae, 447 _Morosaurus_, _38_, _207_; pes, 294 _Mosasaurus_, _38_, _204_ _Moschus_, _46_; canines, 429 Mouse, _47_; teeth, 437; see _Mus_ Mud-fish, _34_ Multituberculata, _43_, _348_ Muntjac, _46_; see _Cervulus_ Muraenidae, _33_ Muridae _47_ _Mus_, _47_; _M. musculus_, teeth, 437; _M. sylvaticus_, sternum and shoulder girdle, 498 Musk deer, _46_; canines, 429 Mustelidae, _48_; teeth 439 _Mycetes_, 49; hyoid, 485; mandible, 484; skull, 482 Myliobatidae, _32_; teeth, 109 Myomorpha, _47_ _Myrmecobius_, teeth, 423 _Myrmecophaga_, _44_; manus 505; pectoral girdle, 495; skull, 458 Myrmecophagidae, _44_, 424; see Anteaters Mystacoceti, _44_; general characters, 356; hind limb, 518; manus, 505; pectoral girdle, 495; skull, 461; teeth, 426 _Myxine_, _31_, 55; fins, 115; notochordal sheath, 9 Myxinoidei, _31_, 55 Nails, 3; Amphibia, 168; mammals, 417 Nares: anterior --, crocodile, 252, 257; dog, 401; duck, 317; newt, 143; turtle, 225, 229; posterior --, crocodile, 257; dog, 402; duck, 318; frog, 158; newt, 143; turtle, 230 Narial cavity, salmon, 89; -- passage, crocodile, 254; dog, 395; -- septum, dog, 401 Narwhal, _45_, _357_; teeth, 427