L U 



[268] 



L Y M 



Caermarthenshire, in Wales. Or- 

 ganic remains are found in all 

 three sub-divisions. The Ludlow 

 formation, says Sir E. Murchison, is 

 the key which accurately reveals 

 to us the relations of the inferior 

 masses to the overlying strata. 



LUXATED. j (lunatus, Lat.) Cres- 



LI/NULATED. ) cent-shaped ; formed 

 like a half-moon. 



LTJ'NTJLE. In conchology, a crescent- 

 like mark or spot, situated near 

 the anterior and posterior slopes in 

 bivalve shells. 



LU'NULET. In entomology, a half- 

 moon shaped spot in insects, of a 

 different colour from the rest of the 

 body. 



LUNTTLI'TES. A genus of foraminated 

 polypifers. A free, stony, circular 

 polypifer, with one side convex, 

 the other concave. The convex 

 side striated in rays, with intersti- 

 cial pores; the concave side radiated 

 with diverging rugae and grooves. 



LU'STBE. In mineralogy, one of the 

 physical characters by which mi- 

 nerals may be recognized. It is 

 of several kinds, as metallic and 

 pseudo-metallic,adamantine,pearly, 

 silky, resinons, vitreous, waxy, &c. 

 In the absence of lustre, a mineral 

 is said to be dull. 



LTTTRA'EIA. A genus of bivalves, 

 placed by Lamarck in the family 

 Mactracea. A thin, transverse, 

 inequilateral shell, gaping at the 

 extremities; two oblique and di- 

 verging hinge-teeth accompanying 

 a large pit for the cartilage. No 

 lateral teeth, in which feature it 

 differs from Mactra. 

 LYCOPODIA'CEJG. The first order of the 

 class Anogens. The club-mosses; 

 or club-moss tribe. Plants of an 

 inferior degree of organization to 

 conifera3, some of which they greatly 

 resemble in their foliage. This tribe, 

 at the present day, contains no 

 species more than three feet high, 

 while many of the fossil species are 

 as large as recent coniferse, having 



attained to the size of forest trees. 

 The affinities of existing lycopodiacea 

 are intermediate between ferns and 

 conifera3 on the one hand, and ferns 

 and mosses on the other. They are 

 related to ferns in the want of sexual 

 apparatus, and in the abundance of 

 annular ducts contained in their 

 axis ; to conifers in the aspect of 

 their stems ; and to mosses in their 

 general appearance. The leaves of 

 existing lycopodiacea are simple, 

 and arranged in spiral lines around 

 the stem, and impress on the surface 

 scars of rhomboidal, or lanceolate 

 form, marked with prints of the 

 insertion of vessels. 

 LYCOPODI'TES. 1. Fossil plants of the 

 genus Lycopodium. 

 2. 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, sometimes quite black. Prof. 

 Jameson constitutes Lydian stone a 

 sub-species of flinty- slate. Specific 

 gravity from 2 -5 8 to 2 -62. It is 

 employed as a test or touchstone to 

 determine the purity of gold and 

 silver, whence its name Basanite, 

 given to it by Kirwan, from fidaa- 

 i/o?, Gr. the trier. It obtained its 

 present name from having been first 

 noticed in Lydia. It is described 

 by Pliny and Theophrastes. 

 LYMPH, (lympha, Lat. water.) A 

 colourless liquid, found in the lym- 

 phatics. 



LYMPH OF PLANTS. During the vege- 

 tation of plants, there is a juice 

 continually ascending from their 

 roots. This is called the sap, or 

 lym/ph of plants. From experiments 

 made by Yauquelin, it was ascer- 

 tained that the lymph of the com- 



