LOP 



LUN 



of glass, which, being impervious to the 

 light, reflect the images of things placed 

 before them. 



LOTHIODON {\6(poi, a crest, hdovi, 

 a tooth). A genus of extinct pachyderms, 

 allied to the tapir, and named from emi- 

 nences of the teeth. They are known 

 only by imperfect fragments. 



LOPHOBRA'NCHII {\6(pos, a crest or 

 tuft, /Spdyx^a, gills). An order of Fishes, 

 in which the gills, instead of hanging in 

 regular fringes, like the teeth of a comb, 

 from the branchial arches, are disposed 

 in tufts, as in the pipe-fish, &c. 



LORFCA. Literally, a coat of mail. 

 A kind of lute, with which vessels are 

 coated before they are exposed to the 

 fire. Hence the term lorication in che- 

 mistry, for coating. See Lute. 



LORICA'TA {lorica, a coat of mail). 

 1. An order of Reptiles, including the 

 crocodiles, alligators, and gavials, inter- 

 mediate between the fresh-water tortoises, 

 and the true lizards, and characterized 

 by the plate-armour with which their 

 body is protected. 2. Also, a group of 

 polygastric animalcules, enclosed in a 

 shell, and thus distinguished from the 

 group termed nuda, in which the body is 

 entirely soft. 



LOWER GREENSAND. The geo- 

 logical designation of the early deposits 

 of the Cretaceous Period, consisting, in 

 England, principally of sand, varied oc- 

 casionally by calcareous and muddy 

 bands ; but on the Continent including 

 many beds of limestone. See Neoco- 

 mian. 



LO'XIAD^. The Cross-bill tribe; a 

 family of the Insessores, or Perching birds, 

 named from the genus loxia, and charac- 

 terized by the strong curvature of the 

 mandibles, which is carried to such an 

 extent that the extremities pass over 

 each other. See Conirostres. 



LOXODRO'MIC CURVE (\0f69, ob- 

 lique, dpojixor, a course). A term applied 

 to a curve of a very peculiar nature, 

 commonly called, in Navigation, the 

 oblique rhumb line. It is a spiral, and 

 has the remarkable property of winding 

 round and round the pole of the earth, 

 constantly approaching, yet never reach- 

 ing it ; so that, if a ship could sAil on the 

 same oblique course for ever, she would 

 approach infinitely near either to the 

 north or the south pole, but could never 

 actually reach them. See Rhumb Line. 



LUCERNl'NiE. Land Volutes, or 

 Lamp snails ; a sub-family of the Heli- 

 cidce, named from the genus lucerna, and 

 203 



having an orbicular, depressed, or flat- 

 tened shell, with the aperture furnished 

 with distinct teeth. 



LUCU'LLITE. A sub-species of lime- 

 stone, of which there are three kinds, 

 the compact, the prismatic, and the fo- 

 liated. The name was derived from the 

 consul Lucullus. It is the Nero antico 

 of the Italians. 



LUDLOW ROCKS. A portion of the 

 Upper Silurian rocks, 2000 feet in thick- 

 ness, composed of three groups : — 1. The 

 Lower Ludlow Rock, or Mudstone, con- 

 sisting of sandy, dark-coloured shales 

 and flags, with concretions of earthy 

 limestone, and containing marine mol- 

 lusca, corals, and fishes; 2. The Ayme- 

 stry Limestone, grey or bluish argillaceous 

 limestone, full of remains of shells and 

 corals; and, 3. The Upper Ludlow Rock, 

 thin, grey, slightly micaceous sandstones 

 and shales, containing shells and trilo- 

 bites. 



LUMACHE'LLA, CARINTHIAN. 

 Fire marble; a variety of shell lime- 

 stone, much esteemed for ornamental 

 purposes. 



LUMIE^RE CENDRE'E. The ashy 

 light; a term applied by the French to 

 the feeble lustre observable on the un- 

 illuminated portion of the moon, arising 

 from the light reflected upon her from 

 the earth. It is popularly called, in this 

 country, the old moon in the new moon's 

 arms. 



LUNA. The Moon; the satellite of 

 the Earth, being the fiftieth part of the 

 bulk of this planet, and 230,000 miles 

 distant from it. She revolves round the 

 earth in 29 days, 12 hours, 44 minutes, 

 2 seconds, turning upon her own axis 

 precisely in the same time as she takes 

 to revolve round the earth. 



LUNA CORNEA. Horn silver; the 

 chloride of silver, so named from its 

 horn-like appearance and consistence. 

 Luna was the alchemical name for 

 silver. 



LUNAR DISTANCE. In nautical 

 astronomy, the distance of the moon from 

 the sun, a fixed star, or a planet ; by de- 

 termining this, the longitude of the ship 

 is found. 



LUNATE {luna, the moon). Present- 

 ing the form of a crescent or half-moon, 

 as the muscular impressions of most 

 bivalves. 



LUNA'TION {luna, the moon). The 



interval from one new moon to another. 



This is the original month, but, to avoid 



confusing it with the arbitrary months 



K6 



