GLOSSARY. 167 



^ Marsupialia (Lat. marsiipium, a pouch) An order of Mammalia 

 in which the immature young are protected in a pouch, 

 placed beneath the abdomen of the female. 

 1-- Masticatory (Lat. mastico, I chew) A term applied to organs 



used in chewing food. 



> Maxilla (Lat. jaws) The lower pair, or pairs, of jaws in the 

 Artliropoda. 



Maxillipedes (Lat. tnaxillce, jaws; j)es, a foot) Or "foot jaws," 

 the modified limbs of the Crustacea, which are used as 

 masticatory organs* 



Medusae The sea-nettles or jelly-fishes, so called because their 

 tentacles resemble the hair of the Medusa, or chief of the 

 gorgons, which was said to consist of snakes. 



Mesenteries (Gr. mesos, the middle; enter on, an intestine) The 

 vertical partitions which divide into chambers the interven- 

 ing space between the alimentary tube and the body wall of 

 a sea-anemone. 



'., Metacirpus (Gr. meta, after; carpus, the wrist) The bones which 

 intervene between the wrist and the fingers in the higher 

 vertebrates. 



MetaUrsus (Gr. meta; tarsos, the hollow part of the foot) The 

 tones which intervene between the tarsus or ankle bones 

 and the phalanges of the toes. 



I Molars (Lat. mola, a mill) The teeth which are not preceded by 

 a milk set the " grinders." 



Mollusca (Lat. mollis, soft) One of the sub-kingdoms, so 

 called from the soft nature of their bodies. It includes 

 the classes Cephalopoda, Gasteropoda, Pteropoda, and 

 Lamellibranchiata. 



Molluscoida (Lat. mollis, soft; Gr. eldos, form) A sub-kingdom, 

 including the Brachiopoda, Asddioida, and Polyzoa. 



Monad (Gr. monas, a unit) An exceedingly minute infusorian. 



Monodelphia (Gr. monos, single; delphus, womb) A division of 



Mammalia, including all the higher members of the group. 

 fc> Monotremata (Gr. monos, single; trema, an opening) An order of 

 Mammalia, in which the intestine and the ducts of the uri- 

 nary and genital organs open into a common cloaca. It 

 includes the duck mole and the porcupine ant-eater. 



Multivalve (Lat. multus, many ; valvce, folding doors) A term 

 applied to certain gasteropod shells which are composed of 

 several pieces. 



Myriapoda (Gr. murios, ten thousand ; pous, a foot) A class of 

 Artliropoda, distinguished by having numerous feet. It in- 

 cludes the centipedes and millipedes. 



Nectocalyx (Gr. necho, I swim; fcahix, a cup) The swimming bell 

 of a jelly-fish. 



