494 GLOSSARY. 



Metathorax (Gr. meta, after ; thorax, the chest). The posterior ring of the 



thorax in Insects. 

 MiCEOLESTES (Gr. mihros, little ; lestes, thief). An extinct genus of Triassic 



Mammals. 

 MlLLEFORA (Lat. mille, one thousand ; porus, a pore). A genus of " Hydro- 

 corallines." 

 Miocene (Gr. meion, less ; Tcainos, new). The Middle Tertiary period. 

 Molars (Lat. mola, a mill). The "grinders" in man, or the teeth in diphyo- 



dont Mammals which are not preceded by milk-teeth. 

 Mollusca (Lat. mollis, soft). The sirb-kiugdom which includes the Shell-fish 



proper, the Polyzoa, the TunicMa, and the Lamp-shells ; so called from the 



generalljf soft nature of their bodies. 

 Molluscoida {Mollusca; Gr. eidos, form). The lower division of the Mollusca, 



comprising the Polyzoa, Tunicata, and Brachiopoda. 

 Mokodelphia (Gr. monos, single ; delphus, womb). The division of Mammalia 



in which the uterus is single. 

 MoNOMYARY (Gr. monos, single ; muon, muscle). Aytidied to those Bivalves 



{LamellibrancMata) in which the shell is closed by a single adductor muscle. 

 MoNOPHYODONT (Gr. mo'iios ; phuo, I generate; odous, tooth). Applied to 



those Mammals in which only a single set of teeth is ever developed. 

 MoNOTHALAMOUS (Gr. monos ; and thalamos, chamber). Possessing only a 



single chamber. Applied to the shells of Foraminifera and Mollusca. 

 Monotremata (Gr. monus; trema, aperture). The order of Mammals com- 

 prising the Duck-mole and Echidna, in which the intestinal canal opens 



into a " cloaca" common to the ducts of the urinary and generative organs. 

 MULTILOCULAR (Lat. multus, many ; loculus, a little purse). Divided into 



many chambers. 

 Multivalve. Applied to shells which are composed of many pieces. 

 MuLTUNGULA (Lat. multiis, many ; ungula, hoof). The division of Perisso- 



dactyle Ungulates, in which each foot has more than a single hoof. 

 Myriapoda or Myriopoda (Gr. murios, ten thousand ; podes, feet). A class 



of Arthropoda comprising the Centipedes and their allies, characterised by 



their numerous feet. 



Nacreous (Fr. nacre, mother-of-pearl, originally oriental). Pearly ; of the 

 texture of mother-of-pearl. 



Natatores (Lat. nare, to swim). The order of the Swimming Birds. 



Natatory (Lat. nare, to swim). Formed for swimming. 



Naxjtiloid. Resembling the shell of the Nautilus in shape, 



Nervures (Lat. nervus, a sinew). The ribs which support the membranous 

 wings of in.sects. 



Neural (Gr. neuron, a nerve). Connected with the nervous system. 



Neurapophvsis (Gr. netiron, a nerve ; apophusis, a projecting part). The 

 "spinous process" of a vertebra, or the process formed at the point of 

 junction of the neural arches. 



Neuroptera (Gr. neuron; si,\\i\. ptcron, a wing). An order of insects charac- 

 terised by four membranous wings with numerous reticulated nervures (e.g., 

 Dragon -flies). 



Nocturnal (Lat. nox, night). Applied to animals which are active by night. 



Normal (Lat. norma, a rule). Conforming to the ordinary standard. 



