LAB 



[244] 



LAC 



LABE'LLUM. (labellum, Lat. a little 

 lip.) A term applied, in botany, 

 to one of the three pieces forming 

 the corolla in orchideous plants. 

 The calyx and corolla consist of 

 three pieces each, and ODC of those 

 forming the latter, differs very 

 much in size and form from the 

 other two; it is called the labellum, 

 and is often spurred. 



LABIATE. | In botany, plants are so 



LA'BIATED. j called which have the 

 segments or divisions of their co- 

 rollas resembling the form of lips. 



LABIATE. There is a large class of 

 plants called labiates, which have 

 irregular monopetalous corollas, 

 and these, generally, bibaliate and 

 ringent ; the mint, nettle, &c. are 

 examples. 



LA'BIUH:. (labium, Lat.) 



1 . In entomology, the lower lip of 

 insects is called the labium ; the 

 upper, the labrum. The lower 

 pair of jaws are behind the mandi- 

 bles, and between them is situated 

 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 cly- 

 peus. 



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, j having been 

 found on the coast of Labrador, 



This mineral was at one time 

 called Labrador Hornblende, but 

 its present name has been substi- 

 tuted for what was incorrect. 

 Labrador felspar has been found 

 massive and disseminated only. Its 

 laminaa are slightly curved ; lustre 

 nearly metallic, and pearly on the 

 perfect cleavage faces. It is dis- 

 tinguished by its splendid change- 

 ability of colour, reflecting very 

 beautiful colours when the light 

 falls upon it in certain directions. 

 This mineral has been also found in 

 different parts of Europe. 



LA'BYRINTH. (labyrinthus, Lat. \afiv- 

 plvOo-s, Gr. labyrinths, Fr. laberinto, 

 It.) The name given to several 

 cavities of the ear, from their flex- 

 uous position. The internal parts 

 of the ear compose what is desig- 

 nated, from the intricacy of its 

 winding passages, the labyrinth. 



LABRYRI'NTHODON. Called also Mas- 

 todonsaurus. A name proposed to 

 be given by Prof. Owen to a genus 

 of reptiles, the remains of which 

 have been discovered in the War- 

 wick sandstone. The Labryrin- 

 thodon belongs to the extinct order 

 Labyrinthodonta. 



LABYRI'NTHODONTA. An extinct order 

 of the class Amphibia, comprising 

 Labryrinthodon; Capitosaurus; Me- 

 topias; Trematosaurus; Zygosau- 

 rus; Odontosaurus; Archegosaums; 

 Rhinosaurus ; and Telerpeton. 



LACERT'ILIA. The third order of the 

 class Eeptilia. 



LAC'ERTA. (The lizard.) A genus of 

 reptiles of the order Lacertilia. 



