676 GLOSSARY. 



Metagenesis. (Gr. meto, indicating change; gignomai,! jivodnce.) The changes 

 of form which the representative of a species of animal or phint undergoes in 

 passing by a series of successively generated individuals from the egg to the 

 mature or imago state. It is distinguished from " metamorphosis," in which 

 those changes are undergone in the same individual. 



Metamorphosis. (Gr. tyieta, signifying change; and morphe, form.) The change 

 of form which the individual of certain species undergoes in passing from one 

 stage of existence to another. 



Metatitorax (Gr. 7neta, after; thorax.) The hindmost of the three segments 

 which compose the thorax of an insect. 



Miocene. (Gr. meiou, less; kainos, recent.) The tertiary epoch in which a 

 minority of fossil shells are of the recent species. 



Molecules. (Dim. of moles, a mass.) Microscopic particles. 



MoLLCscA. (Lat. mollis^ soft.) The primary division of the Animal Kingdom, 

 characterised at page 13. 



Monad. (Gr. moiias, unity.) The genus of the most minute and simple micro- 

 scopic animalcules, shaped like spherical cells. Monadiform, like a monad. 



Monadiary. The common envelope of many organically associated monads. 



MoNiLiFORM. (Lat. monile, a necklace.) A structure like a necklace or string of 

 beads. 



MoNocARPOus. (Gr. monos, single; carpos, fruit.) An animal or plant which 

 perishes when they have once borne fruit. 



MoNOCULUS. (Gr. monos, single ; Lat. oculus, an eye.) The animals which have 

 but one eye. 



Moncecious. (Gr. monos, single ; and oikos, house.) Organisms whose structure 

 is both male and female. 



MoNOMYARY. (Gr. vionos, single; muon, a muscle.) A bivalve whose shell is 

 closed by one adductor muscle. 



MoNOTHALAMOus. (Gr. monos ; thalamos, a chamber.) A shell forming a single 

 chamber, like that of the whelk. 



Morphology. (Gr. mor^Ae, form; Zo^o5, discourse.) The history of the modifica- 

 tions of fonn which the same organ undergoes in the same or in different 

 organisms. 



Motor Y. The nerves which excite and control motion. 



MuLTivALVE. (Lat. multus, many; valvcE, folding-doors.) Shells composed of 

 many pieces or valves. 



Myelencephala. (Gr. muelos, marrow; egkephalon, brain.) The primary divi- 

 sion of animals chai*acterised by a brain and spinal marrow. 



Myriapoda. (Gr. mwios, ten thousand ; pons, foot.) The order of insects cha- 

 racterised by their numerous feet. 



Nacreous. Pearly, like mother-of-pearl. 



Natatory. An animal or part formed for swimming. 



Nematoidea. (Gr. nema, a thread; eidos, like.) The intestinal worms, which 



are long, slender, and cylindrical like threads. 

 Nematoneura. (Gr. nema, a thread; neuron, a nerve.) The animals in which 



the nervous system is filamentary, as in the star-fish. 

 Nervures. (Lat. nervus, a sinew.) The delicate frame-work of the membranous 



wings of insects. 

 Neurilemma. (Gr. neuron, a nerve ; lemma, a covering.) The membrane which 



surrounds the nervous fibre. 

 Neurology. {Gv. 7ieuron, a nerye; Zo^os, a discourse. ) The science of the nervous 



system. 

 Neuroptera. (Gr. neuron, a nerve ; pteron, a wing.) The order of insects with 



four wings, characterised by their numerous nervures, like those of the dragon- 



fly. 



Nidamental. (Lat. nidus, a nest.) Relating to the protection of the egg and 

 young, especially applied to the organs that secrete the material of which many 

 animals construct their nests. 



Nodule. (Dim. of jiodus, a knot.) A little knot-like eminence. 



Normal. (Lat. norma, rule.) According to rule, ordinary or natural. 



