GLOSSARY. 385 



Mes-o-stee'nuj! (Gr. mesos, intermediiite ; sternnii, the breast-cione). The 

 middle portion of tiie sternum, intervening between the attachment of the 

 second pair of ribs and the xiphoid cartilage (xipliisierimm ). 

 Mes-o-tho'rax (Gr. mesos ; and thurax, the chest). The middle ring of the 



thorax in Insects. 

 Mes-o-zo'ic (Gr. mesos ; zo\ life). The Secondary period in Geology. 

 MEr-A-CAE'p[is (Gr. mcto, after; harpos, the wrist). The bones winch form 



the ^'root of the hand," and intervene between the wrist and the lingers. 

 M et-a-mok'pho-sis (Gr. meta, implying change ; morplie, shape). The changes 

 of form which certain animals undergo in passing from their younger to 

 their fully-grown condition. 

 Met-a-po'di-um (Gr. meta, after; pous, the foot). The posterior lobe of the 

 foot in Mollusca ; often called the " operculigerous lobe," because it de- 

 velops the operculum when this structure is present. 

 Me-tas'to ma (Gr. meta, after; stoma, mouth). The plate which closes the 



mouth postexiorly in the Crustacea. 

 Met-a-tae'sus (Gr. mda, after; tarsos, the in.itep). The bones which inter- 

 vene between the bones of the ankle (tarsus) and the digits in the hind-foot 

 of the higher Vertebrates. 

 Met-a-tso'eas. (Gr. jneia, after ; thorax, the chest). The posterior ring of 



the thorax in Insects, 

 IWi-met'ic (Gr. mimeti&os, imitative). Applied to organs or animals which 



resemble each other in external appearance, but not in essential structure. 

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



dont Mammals which are not preceded by milk-teeth. 

 MoL-LDs'cA (Lat. mollis, soft). The sub-kingdom which includes the Shell- 

 fish proper, the Pohjzoa, the Tuiiicata, and the Lamp-shells ; so called from 

 the generally soft nature of their bodies. 

 IIol-lus-ooi'da (^Mollu&:a ; Gr. eldos, form). The lower division of the Mol- 



lusGi, comprising the Polyzoa, Tuibicata, and Brachiopoda. 

 Mon'ads (Gr. motias, uiiity ). Microscopical organisms of an extremely simple 



character, developed in organic infusions. 

 Mo-Noc'u-x-0[js (Gr. mo/ios, smgle ; Lat. oculas, eye). Possessed of only one 



eye. 

 Mo.^-o-delph'i-a (Gr. monos, single ; delp7ius, womb). The division of Mam- 

 malia in which the uterus is single. 

 Mo-nce'ci-ous (Gr. inon-os, single ; oihos, house). Applied to individuals in 



which the sexes are united. 

 Mox-o-jty'a-rt (Gr. monos, single ; m.us, muscle). Applied to those bivalves 



(Lamellibrancniata) in which the shell is closed by a single adductor muscle. 

 Moy-o-PHY'o-DONT (Gr. monos ; phuo, I generate ; odous, tooth). Applied to 



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

 Mox-o-thal'a-mous ("Gr. monos ; and thalamos, chamber). Possessing only a 



single cliamber. Applied to the shells oi Foraminifera and Mollusca. 

 Mon-o-teem'.v-ta {Gr. monos / frem.a, aperture). The order of Mammals com- 

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

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

 MoL-Ti-LOo'u-LAE (Lat. mitltl, many; loculus, a little purse). Divided into 



many chambers. 

 Mol'ti-valve. Applied to shells which are composed of many pieces. 

 Mul-tun'gu-la (Lat. m-ulti, many ; nngala, hoof). The division of Perisso- 



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

 ^^^'E-L0N (Gr. muelos, marrow). The spinal cord of Vertebrates. 

 MrR-i-Ap'o-DA (Gr. TniiHol, ten thousand ; podes, feet). A class of Artliropoda 

 comprismg the Centipedes and their allies, characterized by their numerous 

 feet. 



Na'cre-ous (Fr. nacre, mother-of-pearl, origuially Oriental). Pearly ; of the 



texture of mother-of-pearl. 

 Nat-a-to'ees (LaX. jiare, to swim). The order of the Swimming Birds. 

 Na'ta-to-ev (Lat. nare, to swim;. Formed for swimming. 



