LOW 



L Y C 



of some of the members is concerned, de- 

 pending on local appearances. Generally 

 speaking, the lower chalk may be distin- 

 guished from the upper by the absence of 

 flints, and by the superior hardness of the 

 chalk, which is sometimes used for build- 

 ing-stone. The lower is regularly strati- 

 fied. In the north of England, Professor 

 Phillips states, " The lower chalk is of a 

 red colour, and flints are found in it. The 

 only mineral found in the lower chalk is 

 sulphuret of iron. The fossil remains 

 are very numerous and all of them ma- 

 rine." 



LOWER GREEN-SAND. The lowest member 

 of the chalk series ; called also Shanklin 

 sand, from Shanklin, in the Isle of Wight, 

 and iron-sand. A considerable mass of 

 green, or ferruginous sands, with layers 

 of chert, local beds of gault, rocks of 

 cherty or chalky limestone, and deposits 

 of ochre and fuller's-earth. In York- 

 shire, this member of the series is wholly 

 wanting, but in Lincolnshire it is fully 

 developed. The lower green- sand is a 

 marine deposit. In some situations, the 

 beds of Shanklin, or lower green-sand 

 admit of a triple division ; the first, or 

 uppermost, consists of sand, with irregu- 

 lar concretions of limestone and chert, 

 sometimes disposed in courses oblique to 

 the general direction of the strata. The 

 second consists chiefly of sand, but in 

 some places is so mixed with clay, or with 

 oxide of iron, as to retain water ; it is 

 remarkable for its great variation in its 

 colour and consistency. The third, and 

 lowest division abounds much more in 

 stone ; the concretional beds being closer 

 together and more continuous. The fos- 

 sils of the lower green- sand are not so 

 numerous as those of the lower chalk. It 

 contains upwards of thirty genera belong- 

 ing to different classes ; among these may 

 be enumerated ammonites, nautilus, pa- 

 tella, turbo, natica auricula, rostellaria, 

 pileopsis, &c., of the class Mollusca; 

 corbula, cucullea, gervillia, inoceramus, 

 lenia, modiola, mytilus, mya, nucula, or- 

 bicula, pecten, pholadomya, pinna, tellina 

 thetis, terebratula, trigonia, venus, &c. 

 of the class Conchifera; dentalium and 

 vermicularia of Anuelides ; spatangus, of 

 the class Radiaria, &c., &c. 



LO'ZENGED. In entomology, of a quadran- 

 gular shape, with two opposite angles 

 acute, and two obtuse. 



LUBRI'CITY. (lubricite, Fr.) Smoothness 

 of surface ; slipperiness. More particu- 

 larly applied to shells. 



LUCU'LLITE. (from Lucius Lucullus, a 

 celebrated Roman, who is said greatly to 

 have admired it.) A black variety of 

 transition limestone, a black marble. 



LU'CID. (from lucidus, Lat. lucide, Fr. 



lucido, It.) Bright; shining; clear; 

 pellucid ; transparent. 



LUCI'DITY. (lucidite, Fr.) Splendour; 

 brightness ; transparency. 



LU'MBAR. (from lumbus, Lat.) Pertain- 

 ing to the loins, as the lumbar region, 

 the lumbar muscles, &c. 



LUMINI'FEROUS. (from lumen, light, and 

 fero, to produce, Lat.) Producing light ; 

 yielding light. 



LU'MINOUS. (luminosus, Lat. lummeux^. 

 luminoso, It.) Shining; bright; emit- 

 ting light. 



LU'MINOUSNESS. Brightness ; the quality 

 of shining so as to emit light, or to ap- 

 pear to do so, as the luminousness of the 

 sea ; the luminousness of phosphoric bo- 

 dies. 



LU'NATED. (lunatus, Lat.) Crescent- 

 shaped ; formed like a half-moon. 



LU'NULATED. Crescent-shaped ; shaped 

 like a half-moon ; semilunar. 



LU'NULE. In conchology, a crescent-like 

 mark or spot, situated near the anterior 

 and posterior slopes in bivalve shells. In 

 different species of Venus they are pro- 

 minent ; they are frequently very useful 

 in assisting to ascertain the species. 



LU'NULET. In entomology, a half-moon 

 shaped spot in insects, of a different 

 colour from the rest of the body. 



LU'TEOUS. (luteus, Lat.) A brownish 

 yellow, something of a clay colour. 



LTJ'TOSE. (lutosus, Lat.) Miry ; covered 

 with clay. 



LUTRA'RIA. A genus of bivalves, placed 

 by Lamarck in the family Mactracea. A 

 thin, transverse, inequilateral shell, gap- 

 ing at the extremities ; two oblique and 

 diverging hinge-teeth accompanying a 

 large pit for the cartilage. No lateral 

 teeth, in which feature it differs from 

 Mactra. One species, Lutraria com- 

 pressa, has been found fossil in alluvial 

 deposits, and another, Lutraria oblata, in 

 the sandstone of Bognor. 



LYCOPODIA'CEA. The club-mosses ; or 

 club-moss tribe. Plants of an inferior 

 degree of organization to coniferse, 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 at- 

 tained to the size of forest trees. Their 

 mode of reproduction is similar to that of 

 ferns. The affinities of existing lycopo- 

 diacecs are intermediate between ferns 

 and coniferse 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 annu- 

 lar ducts contained in their axis ; to coni- 

 ferae in the aspect of their stems ; and to 

 mosses in their general appearance. The 



