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M U 



distance from the front of the gla- 

 cier, it is considered that the glacier 

 has retreated to the amount of that 

 distance ; but if there be no other 

 than that which the glacier imme- 

 diately drives before it, it is con- 

 sidered to be on the increase. 

 HORO'XITE. A sub-species of apatite, 

 occurring in crystals, of a brownish 

 or greenish-blue colour : found in 

 Norway, in primary rocks. 



\ "The Mososaurus," 

 > says Buckland, "has 

 ) 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 skilful naturalists; 

 some considered it to be that of a 

 whale, others of a crocodile; but 

 its true place in the animal king- 

 dom 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 disco- 

 vered in the upper chalk near 

 Lewes, in Sussex ; these have the 

 body convex posteriorly, and con- 

 cave anteriorly, and were one hun- 

 dred and thirty-three in number. 

 It had four paddles instead of legs. 

 Teeth of the mososaurus have been 

 discovered in the green-sand of 

 Virginia. Portions of jaws, with 

 teeth of the mososaurus, may be 

 seen in the British Museum. 

 The mososaurus was a reptile, 

 holding an intermediate place 

 between the monitor and iguana, 

 about twenty- five feet long, and 

 furnished with a tail of such con- 

 struction 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, to the 

 commencement of the chalk forma- 

 tion, the ichthyosauri and plesiosauri 

 were the tyrants of the ocean ; and 

 just at the point of time when their 

 existence terminated, during the 

 deposition of the chalk, the new 

 genus mososaurus appears to have 

 been introduced, to supply for a 

 while their place and offices, being 

 itself destined, in its turn, to give 

 place to the cetacea of the tertiary 

 periods." 



Moss A' GATE. A kind of agate which 

 on being cut and polished, presents 

 delicate vegetable ramifications of 

 different shades, resembling small 

 filaments of moss, or fibres of roots, 

 irregularly interwoven. It has 

 been suggested by some authors 

 that these filaments may be really 

 mosses enveloped in the agate. 



Moss FIR. The name given to a 

 certain kind of wood frequently 

 found in peat mosses or bogs. It 

 much resembles in its colour and 

 general external appearance, ordi- 

 nary decayed fire- wood; but on 

 examination it appears that the 

 fibre of the wood is strongly im- 

 bued with resin, and that all its 

 interstices are filled with resinous 

 matter. It is so highly inflam- 

 mable as to be employed not only 

 as fuel but as torches. 



MOTHER OF COAL. In many coals 

 little flakes of mineral charcoal 

 occur, retaining that part of the 

 vegetable structure called the vas- 

 cular tissue. They are called by 

 the colliers " mother of coal." 



MOULD. (muld, Goth, mold, Seel. 

 mold, Sax. mul, Dan. mull, Germ. 

 Dr. "Webster says the orthography 

 of this word is incorrect, and that 

 it should be written mold : so far 

 as the etymology of the word is 

 concerned, perhaps Webster is cor- 

 rect, but, assuredly, custom war- 



