LAC 



[245] 



LAG 



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



LACI'NIATED. j Fr.) Ragged at the 

 edges; jagged. In botany, applied 

 to leaves cut into numerous irre- 

 gular portions. 



LA'CBYHAL. (from lachryma, vel la- 

 cryma, Lat. lacrymale, Fr.) Certain 

 parts about the eye, connected with 

 the secretion and passage of the 

 tears, as the lacrymal glands, the 

 lacrymal ducts, &c. This word is 

 also written lachrymal. 



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

 teals are numerous minute tubes 

 commencing, by open and very 

 minute orifices, from the inner 

 surface of the intestines, and uni- 

 ting successively into larger vessels, 

 till they form trunks of consider- 

 able magnitude. The office of the 

 lacteals is to take up the chyle and 

 transmit it to the heart. It is 

 only among the vertebrata that 

 lacteals are met with; in inverte- 

 brated animals, the absorption of 

 the chyle is performed by veins 

 instead of lacteal vessels. The 

 chyle of the higher orders of ani- 

 mals often contains a multitude of 

 globules, which give to it a milky 

 appearance, from which circum- 

 stance the vessels containing it have 

 obtained their name. 



LACU'STEINE DEPOSITS. Purely lacus- 

 trine deposits are almost unknown 

 among any of the stratified rocks 

 of a date earlier than the tertiary 

 period, and it was not until the 

 publications 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 the land. 

 "If we drain a lake," says Sir C. 

 Lyell, " we frequently find at the 

 bottom a series of deposits, disposed 

 with great regularity one above 

 the other; the uppermost, perhaps, 

 may be a stratum of peat, next 

 below a more compact variety of 



the same, still lower a bed of lami- 

 nated marl, alternating with peat, 

 and then other beds of marl, alter- 

 nating with clay. Now if we 

 sink a second pit through the same 

 continuous lacustrine deposit, at some 

 distance from the first, we commonly 

 meet with nearly the same serie*s 

 of beds, yet with slight variations ; 

 some, for example, of the layers of 

 sand, clay, or marl may be wanting, 

 one or more of them having thinned 

 out, and given place to others, or 

 sometimes one of the masses, first 

 examined, is observed to increase 

 in thickness to the exclusion of 

 other beds. At length we arrive 

 at a point where the whole assem- 

 blage of lacustrine strata terminate, 

 as, for example, when we arrive at 

 the borders of the original lake- 

 basin." 



LAGA'NUM. A fossil echinite thus 

 named by Klein, called also pan- 

 cake. 



LAG'OMYS. (from \a<yo<?, a hare, and 

 /><?, a rat, Gr.) A rat hare. A 

 genus of animals forming a link 

 between the hare and the rat. The 

 lagomys is placed by Cuvier in the 

 order rodentia. They have been 

 found in Siberia, and are described 

 by Pallas. There are several species. 

 The lagomys has ears of a moderate 

 size; legs nearly alike; clavicles 

 almost perfect ; and no tail. The 

 Rev. W. Kirby observes of the 

 lagomys, "it ought rather to have 

 been called the hay-maker, since 

 man may, or might, have learned 

 that part of the business of the 

 agriculturist, which consists in 

 providing a store of winter pro- 

 vender for his cattle, from this 

 industrious animal. The Tungu- 

 sians, who inhabit the country 

 beyond the lake of Baikal, call it 

 PiJca, which has been adopted as its 

 trivial name. These animals make 

 their abode between the rocks, and 

 during the summer employ them- 

 selves in making hay for a 



