LEM 
long ones. Tlieir manners are very dif- 
ferent from thosB of monkeys, and display 
nothing of the- active mischief and intrusive 
impertinence of that animal. There are 
tliirteen species, of which we shall notice 
the following: 
L. tardigradus, or the Idris. This is of a 
light brown colour, and of the usual size of 
a cat. It walks and climbs with great slow- 
ness, and is supposed incapable of leaping. 
Its manners are gentle and interesting, it is 
extremely susceptible of cold, and when 
exposed to a strong degree of it is agitated 
■with extreme uneasiness, and with consi- 
derable exasperation. It sleeps fi om sun- 
rise to sun-set without intermission, rolled 
up in the manner of the hedge hog ; it is 
extremely attentive to cleanliness, licking 
its full and rich fur with the same assiduity 
as a cat. Its food consists of plantains, 
mangoes, and other fiuits, and it is scarcely 
capable of satisfying itself with grasshop- 
pers when it has access to them. Many 
species of insects, indeed, form a repast 
particidarly gratifying to it, and the sight of 
them excites in its look the most glowing 
animation, and summons to exertion all the 
energies of its frame. Several of the above 
particulars are taken from an account given 
of one kept in a state of confinement by the 
late. Sir William Jones. It is a native of 
various parts of India. 
L, indri, is a native of Madagascar, is 
the largest of the genus, has a face of a dog- 
like form, and a fur thick and soft. It has 
no appearance of a tail; it is very docile, 
and sometimes trained by the natives to 
hunt various animals. It is three feet and 
a half in height. 
L. macauco, or the ruffed macauco, is 
found in some of the Indian islands, and is 
particularly numerous at Madagascar. It is 
full of energy and fierceness, and its voice 
is so strong as to fill the woods with its 
cries. It will endure captivity, notwith- 
standing the violent passions it exhibits in a 
natural state, without discontent or depres- 
sion, and is stated to be extremely inoffen- 
sive, and even sociable in it, with those by 
whom it is surrounded. It possesses neither 
craft nor malice in it. 
L. catta, or the ring-tailed macauco. In 
their state of nature these animals are seen 
in companies of twenty or thirty. They 
feed on almost every species of fruits, and, 
in a state of confinement, like several 
others of this genus, will take animal food 
without any hesitation. They are the most 
elegant and beautiful species of the wliole 
LEO 
genus, are livel}^ and gentle, and so agile 
and elegant in their movements, as to be 
highly interesting. They delight much in 
sunshine, and will sit before a fire, like the 
squirrel, extending towai’ds it their out- 
spread Iiands. It inhabits Madagascar, is 
of the size of a small cat, and resembles 
that animal in purring. See Mammalia, 
Plate XV. fig. 1 and 2. 
LENS, in dioptrics, properly signifies a 
small roundish glass, of the figure of a len- 
til; but is extended to any optic glass, not 
very thick, which either collects the rays of 
light into a point, in their passage through 
it, or disperses them further apart, accord- 
ing to the laws of refraction. 
Lenses have various figures, that is, are 
terminated by various surfaces, from which 
they acquire various names. Some are 
plane on one side, and convex on tlie otlier ; 
others convex on both sides, both which are 
ordinarily called convex lenses ; though 
where we speak accurately, the former is 
called plano-convex. Again, some are plane 
on one side, and concave on the other ; and 
others are copcave on both sides ; which 
are both ustiaily ranked among the concave 
lenses ; though, when distinguished, the for- 
mer is called a plano-concave. Others, again, 
are concave on one side, and convex on the 
other, which are called convexo-concave, or 
concavo-convex lenses, according as the one 
or the other surface is more concave, or a 
portion of a less sphere. It is here to be 
observed, that in every lens terminated in 
any of the forementioned manners, a right 
line, perpendicular to the two surfaces, is 
called the axis of the lens ; which axis, when 
both surfaces are spherical, passes through 
both their centres ; but if one of them be 
plane, it falls perpendicularly upon that, and 
goes through the centre of the other. See 
Optics. 
LEO, in astronomy, one of the twelve 
signs of the zodiac, the fifth in order. See 
Astronomy. 
LEONTICE, in botany, a genus of the 
Hexandria Monogynia class and' order. Na- 
tural order of Corydales. Berberides, Jus- 
sieu. Essential character : 'calyx six-leav- 
ed, deciduous; corolla six-petalled ; nectary 
six-leaved, placed on the claws of the 
corolla, spreading. There are three spe- 
cies. 
LEONTODON, in botany, dandelion, a 
genus of the Syngenesia Polygainia .Slipiali* 
class and order. Natural order of Compo- 
sita- Semiflosculosi. Cichorace®, Jussieu. 
Essential character ; calyx imbricate, with 
