which the perfume musk is obtained.

MOUNTAIN LIMESTONE, OR CARBONIFEROUS LIMESTONE. A series of
limestone strata of marine origin, usually forming the lowest member
of the Coal Measures.

MOYA. A term applied in South America to mud poured out from
volcanoes during eruptions.

MULTILOCULAR. Many-chambered; a term applied to those shells which,
like the nautilus, ammonite, and others, are divided into many
compartments. _Etym._, _multus_, many, and _loculus_, a partition.

MURIATE OF SODA. The scientific name for common culinary salt,
because it is composed of muriatic acid and the alkali soda.

MUSACEAE. A family of tropical monocotyledonous plants, including the
banana and plantains.

MUSCHELKALK. A limestone, belonging to the Upper New Red Sandstone
group. Its position is between the Magnesian Limestone and the Lias.
This formation has not yet been found in England, and the German
name is adopted by English geologists. The word means shell
limestone. _Etym._, _muschel_, shell, and _kalkstein_, limestone.

NAPHTHA. A very thin, volatile, inflammable, and fluid mineral
substance, of which there are springs in many countries,
particularly in volcanic districts.

NENUPHAR. A yellow water-lily. P. 618.

NEW RED SANDSTONE. A formation so named, because it consists chiefly
of sandy and argillaceous strata, the predominant color of which is
brick-red, but containing portions which are of a greenish-gray.
These occur often in spots and stripes, so that the series has
sometimes been called the variegated sandstone. This formation is
divided into the Upper New Red in which the Muschelkalk is included,
and the Lower New Red, of which the Magnesian Limestone is a member.

NODULE. A rounded irregular-shaped lump or mass. _Etym._, diminutive
of _nodus_, knot.

NORMAL GROUPS. Groups of certain rocks taken as a rule or standard.
_Etym._, _norma_, rule or pattern.

NUCLEUS. A solid central piece, around which other matter is
collected. The word is Latin for kernel.

NUMMULITES. An extinct genus of the order of molluscous animals,
called Cephalopoda, of a thin lenticular shape, internally divided
into small chambers. _Etym._, _nummus_, Latin for money, and [Greek:
lithos], _lithos_, stone, from its resemblance to a coin.

OBSIDIAN. A volcanic product, or species of lava, very like common