MAS 



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M E A 



of birds. The use of the marsupium 

 is not ascertained, but it is present 

 in almost every bird having ex- 

 tensive powers of vision. 



MA'SCAGNINE. A native sulphate of 

 ammonia, found, by M. Mascagni, 

 near the warm spring of Sasso, in 

 Tuscany, and named after its dis- 

 coverer. It has also been called 

 Sassolin, from the place near which 

 it was found. 



MA'SSETER. (from fjiaaaao^ai, Gr. to 

 chew.) A muscle connected with 

 the under jaw of insects, and which 

 assists in masticating. 



MA'SSIVE. A term used in mineral- 

 ogy to describe a substance of no 

 determinate form, whatever its 

 internal structure may be : it is, 

 however, generally applied to 

 minerals possessing regular internal 

 structure, but having no character- 

 istic external form. 



MA'STODON. (from ^CUTTO?, a breast or 

 udder, and oSovs, a tooth, Gr.) A 

 name given by Cuvier to a genus 

 of fossil mammalia. The remains 

 of the mastodon were first dis- 

 covered at Albany, near Hudson 

 river, about the year 1711. The 

 first specimens brought to Europe 

 were obtained from the neighbour- 

 hood of the Ohio, from which 

 circumstance the French called the 

 mastodon the animal of the Ohio. 

 Several species have been dis- 

 tinguished. "The Great Masto- 

 don," says Griffith, "is one of the 

 most remarkable and apparently 

 the most enormous of all the fossil 

 species. Bones of this species are 

 found in abundance over all North 

 America, from the 43rd degree of 

 north latitude, as far south as 

 Charlestown, in Carolina, in thirty- 

 three degrees, and, as far as we 

 at present know, do not exist in 

 any other country of the globe. 

 They are found at moderate depths, 

 exhibiting few marks of decompo- 

 sition, and none of detrition." 

 The great mastodon was very 



similar to the elephant in the tusks 

 and entire osteology, the cheek- 

 teeth excepted. It is supposed 

 to have possessed a trunk ; its 

 height, about which very false and 

 exaggerated notions once prevailed, 

 does not appear to have exceeded 

 ten or twelve feet, but its body 

 was longer than that of the recent 

 elephant, its limbs were thicker, 

 and its belly less bulky. The 

 structure of its molars, is sufficient 

 to constitute it a different genus. 

 " Two dental characters exist 

 which distinguish, in a well-marked 

 and unequivocal manner, the genus 

 Mastodon from the genus Elephas. 

 The first is the presence of two 

 tusks in the lower jaw of both 

 sexes of the mastodon, one or both 

 of which are retained in the male, 

 while both are early shed in the 

 female. The second character is 

 equally decisive ; it is the displace- 

 ment of the first and second molars, 

 in the vertical direction, by a tooth 

 of simpler form than the second, a 

 true dent de r emplacement, developed 

 above the deciduous teeth in the 

 upper, and below them in the 

 lower jaw." Prof Owen. 



MA'STOID. (from /uurros, the breast, 

 and ef<5o9, likeness, Gr.) Shaped 

 like the breast, or like a nipple. 

 Applied to some prominences of 

 bones ; to a foramen ; to a muscle ; 

 and to cells in the ear. 



MA'TRIX. (matrix, Lat. matrices, pi.) 

 In mineralogy, the earthy or stony 

 matter in which a fossil is im- 

 bedded. Called also gangue. 



MAXI'LLA. (maxilla, Lat.) The jaw. 

 The lower jaws of insects are cal- 

 led maxillae ; they are placed be- 

 hind the mandibles, and between is 

 situated the labium, or lower lip. 

 The maxillaa are employed princi- 

 pally for holding the substances on 

 which the grinding apparatus of 

 the mandible is exerted. 



MEAN QUANTITIES. Such as are inter- 

 mediate between others that ar 



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