L Y C 



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MAC 



leaves of existing lycopodiacese are simple, 

 and arranged in spiral lines around the 

 stem, and impress on its surface scars of 

 rhomboidal, or lanceolate form, marked 

 with prints of the insertions of vessels. 

 Buckland. Lindley. Lyell. 



LYCOPODI'TES. Fossil plants of the genus 

 Lycopodium. 



LYCOPO'DIUM. A genus of plants of the 

 club-moss tribe. 



LY'DIAN STONE. The Lydischer stein of 

 Werner ; La pierre de Lydie of Brochant ; 

 Basanite of Kirwan ; Lydian stone of 

 Jameson. A variety of siliceous slate ; a 

 black siliceous flint-slate, called by some 

 black jasper. It differs but little from 

 the common variety of siliceous slate. 

 Colour grayish or bluish-black, some- 

 times quite black. 



LYMN^E'A. See Limneea. 



LYMPH. (lympha, Lat. water.) A co- 

 lourless liquid, found in the lymphatics. 



LYMPH OF PLANTS. During the vegeta- 

 tion of plants, there is a juice continually 

 ascending from their roots. This is 

 called the sap, or lymph of plants. From 

 experiments made by Vauquelin, it was 

 ascertained that the lymph of the com- 

 mon elm consisted as follows : Of 1039 

 parts, 1027-904 water and volatile matter, 

 9-240 acetite of potash, 1-060 vegetable 

 matter, 0-796 carbonate of lime. 



LYMPHA'TICS. Minute vessels pervading 

 every part of the body, absorbing and 

 conveying the absorbed matter into the 

 thoracic duct, to be afterwards conveyed 

 into the blood. The lymphatics are sup- 

 plied within with valves, and without with 

 glands. 



LY'RATE. (from lyra, a harp, Lat.) Lyre- 

 shaped ; a term applied to leaves divided 

 transversely into several segments, the 

 segments gradually increasing in size as 

 they approach the extremity of the leaf. 



M 



MACHAI'RODUS. An extinct animal of the 

 order Mammalia, referrible to the Mio- 

 cene period, and allied to the bear. 



MACI'GNO. The Italian word for a kind of 

 stone, a siliceous sandstone sometimes 

 containing calcareous grains, &c. Macigna 

 pietra, a very hard stone. 



MA'CLE. The Hohl spath of Werner; 

 Hollow spar of Jameson. Made occurs 

 only in crystals, the form of which is a 

 four-sided prism. But each crystal, when 

 viewed at its extremities, or on a trans- 

 verse section, is obviously composed of 

 two very different substances ; and its 

 general appearance is that of a black 

 prism, passing longitudinally through the 

 axis of another prism, which is whitish. 

 These crystals, often long, are sometimes 

 very minute ; in some instances their 

 edges are rounded. The crystals of 

 Macle present a considerable number of 

 natural joints, which lead to an octohe- 

 dron for their primitive form. Macle 

 scratches glass ; its powder is soft and 

 unctuous. It is opaque, or sometimes 

 translucent. Colour white or gray, often 

 shaded with yellow, green, or red. Spe- 

 cific gravity 2'94. It is found, generally, 

 imbedded in black argillaceous slate. 

 Cleaveland. 



MACLU'REITE. Called also Brucite and 

 Chondrodite. A mineral occurring in 

 imbedded grains in small massive pieces, 

 and in longish granular concretions. Co- 

 lours yellow, straw-colour, orange, red, 

 and brown ; translucent ; scratches glass ; 

 fracture imperfectly conchoidal. Specific 



gravity 3'15 to 3'50. It consists of mag- 

 nesia 54-0, silica 36-60, fluoric acid 4'0, 

 oxide of iron 2-30, potash 2'0, manganese 

 a trace. 



MACROPO'MA. The name given by M. 

 Agassiz to a genus of sauroid fishes, the 

 fossil remains of which have been disco- 

 vered in the chalk formation. The scales 

 of the Macropoma are studded with hol- 

 low tubes, through which, it is stated, 

 there flowed a fluid which served to lubri- 

 cate the surface of the body. 



MACROPO'MA MANTELLI. A species of 

 fossil fishes belonging to the genus Ma- 

 cropoma, found in the chalk near Lewes, 

 and named after Dr. Mantell. The 

 length of a specimen figured in Dr. Man- 

 tell' s Wonders of Geology is twenty-four 

 inches. 



MACRODA'CTYLI. (from /waicpoc, long, and 

 SctKTvXoG, finger, Gr.) The name given 

 to a family of birds in Cuvier's arrange- 

 ment, having very long toes. The coot, 

 rail, &c. are examples. 



MACROSPO'NDYLUS. A fossil saurian found 

 in the oolite and lias formations. 



MACROSTO'MATA. (from juaiepof, long, 

 and (rro/ia, mouth, Gr.) A family of 

 univalves, belonging to the order Tra- 

 chellipoda, comprising the genera Sto- 

 mata, Stomatella, and Haliotis. 



MACROU'RA. (from paKpoQ, long, and 

 ovpa, a tail.) A family of crustaceans, 

 including the lobster, prawn, shrimp, &c. 

 They are so named from their having 

 a long tail, which is, at least, as long as 

 the body, and provided at its termination 



