MAR 



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MAE 



Lomouroux, that it is divisible 

 into different systems, apparently 

 as distinct as those on the land, 

 notwithstanding that the unifor- 

 mity of temperature is so much 

 greater in the ocean. The number 

 of hydrophytes, or plants growing 

 in water, is very considerable, and 

 their stations are found to be in- 

 finitely more varied than could 

 have been anticipated ; for while 

 some plants are covered and uncov- 

 ered daily by the tide, others live 

 in abysses of the ocean, at the ex- 

 traordinary depth of one thousand 

 feet ; and although in such situa- 

 tions there must reign darkness 

 more profound than night, at least 

 to our organs, many of these vege- 

 tables are highly coloured. 



MARL, (mergel, mar gel, Germ.) A 

 combination of common clay and 

 calcareous earth ; a mixture of clay 

 and lime. 



MARL SLATE. A brown indurated 

 fossil shale, with occasional beds of 

 thin compact limestone : a rock of 

 the Permian period. 



MARLSTONE. The name given to a 

 member of the lias which (the lias) 

 Sir E. Murchison states to be capa- 

 ble of a four-fold division. This 

 member of the lias, he says, is well 

 exposed in the hill on which the 

 church of Prees is built, both in 

 quarries and by the sides of the 

 rocks, dipping to the NYN.E. at low 

 angles. The upper beds are com- 

 posed of yellowish and greenish 

 thin-bedded sandstone, slightly mi- 

 caceous, and in parts calcareous; 

 the middle, of other yellowish 

 sandstones, some of which are more 

 calcareous ; and the lowest beds, of 

 sandy, dark-coloured slaty marl, 

 and shale with flattened spheroids 

 of impure lias limestone, which are 

 undistinguishable from the cement- 

 stone of the Yorkshire coast. The 

 marlstone is a well marked division 

 of the lias, being more arenaceous, 

 though still fine-grained, and often 



bound by calcareous or ferruginous 

 cement into a hard stone. In 

 Gloucestershire it is divisible into 

 the "hard rock bed" above, and 

 the sands below. Jukes. 



MA'RLY. Composed of marl; con- 

 taining marl ; resembling marl. 



MA'RTSTES IRISEES. The French geolo- 

 gists designate by this term the 

 upper party-coloured marls or clays 

 of the new red formation. They 

 are the same as the keuper-marls of 

 the Germans, and the gypseous and 

 saliferous marls of Cheshire, "Wor- 

 cestershire, &c., of England. 



MA'RSIPOBRANCHII. The fifth order 

 of fishes, comprising the lampreys, 

 &c. 



MARSTJ'PIAL. (from marsupium, a 

 pouch, Lat.) Having a pouch; 

 belonging to the order Marsupialia. 

 New Holland is known to contain a 

 most singular assemblage of mam- 

 miferous animals, consisting of more 

 than forty species of the marsupial 

 family. 



MARSITPIA'LIA. (The term Marsupialia 

 is derived from the presence of a 

 large marsupium, or pouch, fixed on 

 the abdomen, in which the faatus 

 is placed after a very short period 

 of uterine gestation. Foetus ad 

 uterum maternum haud intermedio 

 placenta vera3 annexus.) Animals 

 possessing abdominal pouches. The 

 marsupialia form the fourth order 

 of Mammalia, in Cuvier's arrange- 

 ment. The economy of marsupialia 

 is in many respects most singular. 

 One most striking peculiarity is the 

 premature production of the foetus, 

 whose state of development at birth 

 is extremely small. Immediately 

 on their birth they pass into a sort 

 of second matrix. Incapable of 

 motion, and scarcely displaying 

 any germs of limbs or external 

 organs, these diminutive beings 

 attach themselves to the mamma? 

 of the mother, where they remain 

 fixed by the mouth, until they have 

 acquired a growth and development, 



