M O U 



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M U S 



Wales, both from its "extent, the thickness 

 and number of its beds, the quantity and 

 variety of its organic remains, and its 

 richness in metallic ores, particularly of 

 lead. In Derbyshire, where the different 

 beds of limestone have been pierced 

 through by the miners, the average thick- 

 ness of the three uppermost is about 160 

 yards ; the beds are separated by beds of 

 trap or basalt, resembling ancient lavas. 

 The limestone is generally sufficiently 

 hard to bear a polish, and forms what 

 is denominated marble, of considerable 

 beauty. The mountain limestone forma- 

 tion occupies an immense tract in North- 

 umberland, Durham, and Yorkshire, from 

 which country it runs out in a curve to 

 encircle on the north, and partially on 

 the south, the group of Cumbrian slate 

 mountains. It also appears in great force 

 in Derbyshire, ranges through Flint and 

 Denbigh, to St. Orme's head and Angle- 

 sea ; shows slightly round the Glee hills 

 in Shropshire ; and presents picturesque 

 cliffs on the Wye, near Monmouth. The 

 prevailing characteristic organic fossils 

 are madrepores and encrinites ; of the 

 latter some of the upper beds appear to 

 be almost entirely composed. Mountain 

 limestone is generally almost a pure car- 

 bonate of lime, but sometimes it contains 

 a considerable proportion of magnesia. 



MOU'NTAIN SOAP. A mineral, a variety of 

 green earth, of a brown or blackish-brown 

 colour. It is massive, dull, smooth and 

 soapy to the touch, and adheres strongly 

 to the tongue. It writes on paper. Its 

 constituents are silex 44-0, alumine 26% 

 oxide of iron 8'0, lime 0-5, water 2(HO. 

 It occurs in secondary rocks of the trap 

 formation, in the Isle of Skye and in 

 Poland. 



MU'CRONATE. (mucronatus, Lat. pointed.) 



1. In entomology, when from an obtuse 

 end a fine point suddenly proceeds. 



2. In botany, when a small point termi- 

 nates an entire leaf, as in the vetch, 

 house-leek, &c. 



3. In conchology, when a shell terminates 

 in a sharp rigid point. 



MO'YA. The name given by the natives of 

 South America to the mud and slime 

 ejected from volcanos during the erup- 

 tions. 



MULTISPI'RAL. (from multus, many, and 

 spira, a spire, Lat.) In conchology, a 

 term for a shell whose spire consists of 

 many whorls ; also to an operculuin of 

 many volutions. 



MULTILO'CULAR. (from multus, many, 

 and loculus, a chamber or shell, Lat.) A 

 term applied to shells containing parti- 

 tions, which divide them into several 

 chambers. Orthoceratites, baculites, ha- 

 mites, scaphites, belemnites, &c., are all 



multilocular shells ; the argonaut, or 

 paper nautilus, is a unilocular shell. 



MU'LTI VALVE, (from multus, many, and 

 valves, valves, Lat.) Some of the mol- 

 lusca have, in addition to the two princi- 

 pal valves, small supplementary pieces of 

 shell ; these have been comprised in the 

 order of multivalves. 



MU'RCHISONITE. A new mineral, thus 

 named in honour of Mr. Murchison. Its 

 constituents are silica 68*10, alumina 16'6, 

 potash 14'8. It occurs near Dawlish. 



MU'REX. (murex, Lat. murex, Fr.) A 

 genus of shells. Animal a Umax : shell 

 univalve, spiral, rough, with membraneous 

 sutures ; aperture oval, ending in an en- 



tire straight, or slightly ascending canal. 

 The murex is an inhabitant of the ocean, 

 found at depths varying from five to 

 twenty-five fathoms, on different bottoms. 

 These shells, besides their long channelled 

 beaks, are remarkable for the beauty and 

 variety of their spines. Murices, or rock- 

 shells, were in high esteem from the ear- 

 liest ages, on account of the dye that 

 some of them yielded ; cloths died with it 

 bearing a higher price than others. More 

 than one species yielded a dye ; one, ac- 

 cording to Bochart, a glaucous or azure 

 colour ; the other, a purple. Different 

 species of fossil murex are found in the 

 London clay and in Bognor sandstone, 

 and Lamarck describes upwards of seven- 

 teen species found in the neighbourhood 

 of Paris. 



MU'RICATED. (muricatus, Lat. full of 

 sharp points and prickles.) Clothed with 

 sharp rigid points ; beset with short erect 

 spines. 



MU'RICITE. The fossil murex. 



MUSA'CEA. A family of tropical monoco- 

 tyledonous plants, including the banana 

 and plaintains. Lyell, Principles of 

 Geology. 



MU'SCHEL KALK. (from muschel, shell, 

 and kalk, lime or chalk, Germ.) A 

 compact hard limestone, of a greyish co- 

 lour, found in Germany. It belongs to 

 the red sandstone group. The muschel 

 kalk has not yet been discovered in Eng- 

 land, but the upper part of the mountain 

 limestone of the north of England is in 

 some respects similar in mineral proper- 

 ties. In Bavaria and Wurtemburg the 

 muschel kalk is interposed between the 

 red sandstone, on which it rests, and the 

 variegated marls which lie over it, and 

 with which, at the junction, it alternates. 

 The muschel kalk abounds in organic 

 remains ; its chief fossils are the lily 

 encrinite, ammonite, and terebratula. Re- 

 mains of ichthyosauri, plesiosauri, cro- 

 codiles, and turtles, are also found in it. 

 The salt mines of Wurtemburg are also 

 in this formation. 



