M O N 



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M O U 



MONOTHA'LAMOUS. (from ^dvoc, single, 

 and OdXctfiog, a chamber, Gr.) Shells 

 whose chamber is undivided by partitions ; 

 these are termed unilocular, or mono- 

 thalamous : the argonaut is an example. 



MO'NOTREME. The Monotremes form Cu- 

 vier's third tribe of Edentata, comprising 

 two genera, namely, Echidna and Orni- 

 thorhynchus. They are found only in 

 New Holland. The Monotremes seem 

 connected with the birds ; one genus, the 

 ornithorhyiichus, having a mouth resem- 

 bling the bill of a duck, and being almost 

 web-footed ; it has also been stated to be 

 oviparous. The Monotremes have no 

 marsupial pouch. They suckle their 

 young from a mammary orifice. 



MONOTRE'MATOUS. Belonging to the tribe 

 Monotremata. 



MOO'NSTONE. A variety of felspar, called 

 also adularia, possessing a silvery or 

 pearly opalescence. Moonstone is trans- 

 parent and translucent. Its colour is 

 white, with sometimes a tinge of yellow, 

 green, or red. When held in certain po- 

 sitions, its surface is iridescent. It occurs 

 massive, and in crystals. It is found in 

 the fissures and cavities of granite, gneiss, 

 &c. 



MORA'INE. An accumulation of sand, 

 stones, or debris, found upon icebergs, 

 glaciers, &c. 



MO'RDANT. (from mordeo, to bite, Lat. 

 mordant, Fr.) A substance, employed in 

 the process of dying, which has an affinity 

 both for the colouring matter and the 

 material to be dyed. It is also termed a 

 basis. Sulphate of iron and acetate of 

 alumina are commonly employed as mor- 

 dants. 



MORO'XITE. A sub-species of apatite, oc- 

 curring in crystals, of a brownish or 

 greenish-blue colour. It is found in 

 Norway, in primary rocks. 



MOSASAU'RUS. "| " The Mosasaurus," says 



MOSASAU'RUS. > Prof. Buckland, " has 



MOSOSAU'RUS. J been long known by the 

 name of the Great Animal of Maestricht, 

 occurring near that city, in the calcareous 

 freestone, which forms the most recent 

 deposit of the cretaceous formation. A 

 nearly perfect head of this animal was 

 discovered in 1780, and is now in the 

 museum at Paris. This celebrated head, 

 during many years, puzzled the most skil- 

 ful naturalists ; some considered it to be 

 that of a whale, others of a crocodile ; 

 ,but its true place, in the animal kingdom, 

 was first suggested by Adrian Camper, 

 and, at length, confirmed by Cuvier. By 

 their investigations, it is proved to have 

 been a gigantic marine reptile, most nearly 

 allied to the monitor. Some vertebrae of 

 the mososaurus have been discovered in 

 the upper chalk near Lewes, in Sussex : 



these have the body convex posteriorly, 

 and concave anteriorly. Teeth of the 

 mososaurus have been discovered, by Dr. 

 Morton, in the green- sand of Virginia. 

 Portions of jaws, with teeth of the mosse- 

 saurus, may be seen in the British Mu- 

 seum. Dr. Man tell observes, " The mo- 

 sosaurus was a reptile, holding an inter- 

 mediate place between the monitor and 

 iguana, about twenty-five feet long, and 

 furnished with a tail of such construction 

 as must have rendered it a powerful oar, 

 enabling the animal to stem the waves of 

 the ocean, of which Cuvier supposes it to 

 have been an inhabitant." 



" From the lias upwards," says Dr. 

 Buckland, " to the commencement of the 

 chalk formation, the ichthyosauri and 

 plesiosaui'i were the tyrants of the ocean ; 

 and just at the point of time when their 

 existence terminated, during the deposi- 

 tion of the chalk, the new genus mosa- 

 saurus appears to have been introduced, 

 to supply for a while their place and of- 

 fice, being itself destined, in its turn, to 

 give place to the cetacea of the tertiary 

 periods." 



MOU'NTAIN CORK. The Berg kork of 

 Werner ; Suber montanum of Kirwan ; 

 Asbeste suberiforme of Brongniart. A 

 white or grey variety of asbestos, to which 

 the name of mountain cork has been 

 given from its extreme lightness, its 

 specific gravity being from 0'68 to 0'99, 

 consequently so light as to swim in water. 

 Its structure is fibrous ; the fibres pro- 

 miscuous and interwoven. Its consti- 

 tuents are silex 56'2, magnesia 26*1, lime 

 12'7, iron 3'0, alumine 2'0. It occurs in 

 France and Saxony. 



MOU'NTAIN BLUE. A species of blue ma- 

 lachite or blue copper. The Cuivre car- 

 bonate bleu of Haiiy ; Kupfer lazur of 

 Werner. Carbonate of copper. The 

 characteristic colour of mountain blue is 

 azure-blue, often exceedingly beautiful 

 and splendent. Occurs regularly crystal- 

 lized in scopiform and stellular concre- 

 tions, radiated, and also curved lamellar. 

 When rubbed on paper it leaves a light 

 blue streak. Specific gravity from 3'20 

 to 3 '60. It dissolves with effervescence 

 in nitric acid. It is scarcely fusible alone, 

 but with borax, to which it communicates 

 a fine green, it yields a globule of copper. 

 Its constituents are copper 66'0, carbonic 

 acid 18-0, oxygen 8'0, water 2-0. 



MOU'NTAIN LI'MESTONE. A series of ma- 

 rine limestone strata, whose geological 

 position is immediately below the coal 

 measures and above the old red-sandstone. 

 To this formation the French have given 

 the name of Calcaire de transition. Moun- 

 tain limestone is one of the most impor- 

 tant calcareous rocks in England and 



