LAB 



137 ] 



LAC 



divisions of their corollas resembling the 

 form of lips. 



LABIA'T^E. There is a large class of plants 

 called labiates, which have irregular mo- 

 nopetalous corollas, and these, generally, 

 bilabiate and ringent; the mint, nettle, 

 &c. are examples. 



LA'BIUM. (labium, Lat.) 



1. In entomology, the lower lip of insects 

 is called the labium; the upper, the la- 

 drum. The lower pair of jaws are behind 

 the mandibles, and between them is situ- 

 ated the labium, or lower lip, which closes 

 the mouth below, as the labrum does 

 above. The labium of insects consists of 

 two chief parts, each of which may be 

 considered as a separate organ ; namely, 

 the chin and the tongue. 



2. In conchology, the inner lip of the 

 shell. 



LA'BRUM. {labrum, Lat.) 



1. In entomology, the upper lip of insects. 

 The labrum is situated above, or rather 

 in front of, the mandibles, it is generally 

 of the form of the segment of a circle, or 

 a triangular, or quadrangular, somewhat 

 convex, corneous plate, which is united 

 posteriorly by a membranous hinge with 

 the clypeus. 



2. In conchology, the outer lip ; that 

 edge of the aperture which is placed at 

 the greatest distance from the axis of the 

 shell. 



LA'BRADOR FELSPAR. } So named from 



LA'BRADOR STONE. $ having been 

 found on the coast of Labrador, more 

 particularly on the Island of St. Paul. 



This mineral was at one time 

 called Labrador Hornblende, but its 

 present name has very properly been 

 substituted for what was incorrect. 

 Labrador felspar has been found 

 massive and disseminated only. Its 

 laminae are slightly curved ; lustre 

 nearly metallic, and pearly on the per- 

 fect cleavage faces. It is distinguished 

 by its splendent changeability of colour, 

 reflecting very beautiful colours when the 

 light falls upon it in certain directions. 

 Although principally occurring on the 

 coast of Labrador, yet this mineral has 

 been found in different parts of Europe. 



LA'BRADORITE. A name for Labrador fel- 

 spar. 



LABYRINTH. (labyrinthus, Lat. Xa/3v- 

 pivOog, Gr. labyrinthe, Fr. laberinto, It.) 

 The name given to several cavities of the 

 ear, from their flexuous position. The 

 internal parts of the ear compose what is 

 designated, from the intricacy of its 

 winding passages, the labyrinth. It con- 

 sists of a middle portion, termed the ves- 

 tibule, from which, on its upper and 

 posterior side, proceed three tubes, called 

 from their shape, semicircular canals ; to 



the lower anterior side of the vestibule 

 there is attached a spiral canal, resem- 

 bling the shell of snail, and termed the 

 cochlea. 



LACE'RTA. (lacerta, Lat.) A lizard. In 

 Cuvier's arrangement, lacerta constitutes 

 the second genus of Lacertiuida, or lacer- 

 tians. 



LACE'RTIAN. Belonging to the family La- 

 certinida ; order Sauria. 



LACE'RTINE. Resembling a lizard. 



LACI'NIATE. i (laciniatus , Lat. lacinie, 



LACI'NIATED. $ Fr.) Ragged at the 

 edges ; jagged. In botany, applied to 

 leaves cut into numerous irregular por- 

 tions. 



LA'CRYMAL. (from lachryma, vel lacryma, 

 Lat. lacrymale. Fr.) Certain parts 

 about the eye, connected with the secre- 

 tion and passage of the tears, as the 

 lacrymal glands, the lacrymal ducts, &c. 

 This word is also written lachrymal. 



LACTA'TION. (from lac, milk, Lat.) The 

 act of suckling ; the period of suck- 

 ling. 



LA'CTEAL. (from lac, Lat.) The lacteals 

 are numerous minute tubes commencing, 

 by open and very minute orifices, from 

 the inner surface of the intestines, and 

 uniting successively into larger vessels, 

 till they form trunks of considerable 

 magnitude. The office of the lacteals is, 

 to take up the chyle and transmit it to 

 the heart. It is only among the verte- 

 brata that lacteals are met with ; in in- 

 vertebrated animals, the absorption of 

 the chyle is performed by veins instead 

 of lacteal vessels. The chyle of the 

 higher orders of animals often contains a 

 multitude of globules, which give to it 

 a milky appearance, from which circum- 

 stance the vessels containing it have ob- 

 tained their name. 



LA'CTEOUS. (lacteus, Lat.) Milky; of a 

 white colour, resembling milk. 



LACTI'FEROUS. (from lac, milk, and/ero, 

 to bear, Lat.) Conveying milk ; yielding 

 a white juice, or milky liquor. 



LACU'NJE. (lacuna, Lat.) PI. Small ex- 

 cretory ducts. 



LACU'NOSE. ) (from lacunosus, Lat.) Hav- 



LACU'NOUS. $ ing the surface -covered 

 with small furrows, pits, or depressions. 



LACU'STRAL. } (from lacm, Lat.) Per- 



LACU'STRINE. $ taining to a lake. 



LACU'STRINE DEPOSITS. Purely lacustrine 

 deposits are almost unknown among any 

 of the stratified rocks of a date earlier 

 than the tertiary period, and it was not 

 until the publication of Cuvier and Brong- 

 niart, on the environs of Paris, that the 

 attention of geologists was much directed 

 to the study of those numerous fresh* 

 water deposits from which we may obtain 

 a knowledge of the ancient condition of 



