IKDEX. 



435 



genus of the most minute and ] Nerves, pairs of, their several offices, 



simple microscopic animalcules, 



shaped like spherical cells. 

 Monocotyledons, plants with a single 



seed lobe, 7_. 

 Monoc'ulus (Gr. IJLOVOQ, single ; Lat. 



oculus, an eye), the animals which 



have but one eye. 

 Monomy'ary (Gr. /xovoc., 



single ; 



97114. 

 Ner'vous system of man, 84 95 ; of 



other classes of animated beings, 



92119; special senses,120 184. 

 Nervous system, the, and general 



sensation, 76 79. 

 Ner'vous tissue, 45, 55 ; its structure, 



80, 81 ; termination, 82. 



fj,vov, a muscle), a bivalve whose Ner'vures (Lat. nervus, a sinew), 



the delicate frame of the mem- 

 branous wings of insects. 



Neurapoph'yses (Gr. vtvpov, nerve ; 

 a7ro</>y<nf, a process of bone), 

 those vertebral elements which 

 enclose and protect the spinal cord 

 and brain. 



Neu'ral- spine, the spinous processes 

 of the vertebra. 



Neuri'lemma (Gr. vtvpov, a nerve ; 

 X/jjWfta, a covering), the mem- 

 brane which surrounds the ner- 

 vous fibre. 



Neurop'tera (Gr. veiipov, a nerve ; 

 iTTtpov, a wing), the order of in- 

 sects with four wings, character- 

 ized by their numerous nervures, 

 like those of the dragon-fly. 



Nodu v le (dim. of nodus, a knot), a 

 little knot-like eminence. 



Nor'mal (Lat. norma, rule), accord- 

 ing to rule, ordinary or natural. 



Notosau'rus, an extinct saurian, 672. 



Nucleated, having a nucleus or cen- 

 tral particle ; applied to the ele- 

 mentary cells of animal tissues, 

 the most important properties of 

 which reside in the nucleus, 38,56. 



Nucleus and mYcleolus, 56 



Nu'dibrachiate (Lat. nudus, naked; 

 Gr. fipayxta, arms), the polyps, 

 whose arms are not clothed with 

 vibratile cilia. 



Nudibranchiata v (Lat. nudus, naked ; 

 Gr. fipavxia, gills), an order of 

 gasteropods, in which the gills 

 are exposed. 



Nutrition, 308349; digestion, 312 

 349. 



shell is closed by one adductor 



muscle. 

 Monothal'amous (Gr. fiovog, single ; 



OaXapoQ, a chamber), a shell 



forming a single chamber, like 



that of the whelk. 

 Motion, 205 307 ; apparatus of, 



205 227; locomotion, 228 288; 



standing, andmodes of progression, 



289307. 

 Mo'tory, the nerves which control 



motion. 

 Moult'ing, the shedding of feathers, 



hair, &c., 412. 

 Mul'tivalve (Lat. multus, many; 



valvce, folding doors). 

 Mus'cular tissue, one of the primary 



forms of animal tissues having 



the power of contraction, 44, 54. 

 Myri'apods (Gr. pvptoQ, ten thou- 



sand ; Trove, foot), the order of 

 insects characterized by their nu- 

 merous feet. 



NA'CREOUS (Fr. nacre), pearly, like 



mother-of-pearl. 

 Natato'res (Lat. nato, I swim), birds 



with webbed feet for swimming,xxi. 

 Na'tatory, an animal or part formed 



for swimming. 

 Natural history, extent of the study 



of, 30. 



Nature, ages of, 656690. 

 Nautilus, cephalopoda with cham- 



bered shells, xxii. 



Nep'tunic, or water-formed rocks,646. 

 Nerves, structureof the primary fibres 



of, 80, 81; their termination, 82 



119. 



