III R 
it is able to swim with great rapidity, its 
progress in the water is at the bottom by 
walking. If wounded in the Water, it some- 
times is highly infuriated, and has been 
known to attack the boats or canoes, which 
it supposed to contain its enemy, and over- 
turn them by its vast strength, or sink them 
by making a large hole in them with its 
teeth. It produces but one at a birth, ge- 
nerally in the little rushy isles of the rivers 
which it frequents, and ip these islets it ge- 
nerally sleeps. When taken young, it is ca- 
pable of being tamed. These animals are 
sometimes seen in considerable numbers, 
ranging for several miles beyond the banks 
of their rivers. They are often shot by the 
Africans, and frequently taken by the har- 
poon; pitfalls also are sometimes dug for 
them. They are valued by the natives of 
Africa for food, and the fat which it supplies 
is supposed to be equal to that of the hog. 
The feet are highly gelatinous, and regard- 
ed as a particular delicacy. With their 
Skins the warriors of Africa are furnished 
With shields and bucklers. The grand mo- 
tive to destroy these animals, however, is 
the value of their tusks, whicii are whiter 
than those of the elephant, and retain their 
original clearness and beauty. They are 
likewise of a harder consistence, and are, 
on both these accounts, preferred by den- 
tists, for artificial teeth, to every other sub- 
stance. 
In the iEdileship of Scaurus a temporary 
lake was formed, into which he introduced 
four crocodiles and a hippopotamus, for the 
entertainment of the Roman people; and 
Augustus, in his triumph over Cleopatra, 
amidst many other objects characteristic of 
Egypt, exhibited a hippopotamus. In Upper 
Egypt, and in the fens of Ethiopia, tra- 
versed and inundated by the Nile, these 
animals are more particularly abundant. 
For the hippopotamus, see Mammalia, Plate 
X. tig. 2. 
HIPPURIS, in botany, mare's-tail, a ge- 
nus of the Monandria Monogynia class and 
order. Natural order of Inundatae. Naia- 
des, Jussieu. Essential character : calyx a 
two-lobed rim to the germ ; corolla none ; 
stigma simple ; seed one. There are three 
species. 
HIRjEA, in botany, so named from Ni- 
col de la Hire, a genus of the Decandria 
Trigynia class and order. Natural order 
of Trihilatae. Malpighi®, Jussieu. Essen- 
tial character : calyx five-leaved ; petals 
roundish, on claws; capsule three-celled, 
with three wings ; seeds two. There is 
VOL. III. 
MIR 
only one species, viz. H. reclinafa, a native 
of Carthagqna in New Spain. 
HIRCUS, in anatomy, a part of the auri- 
cle or outer ear, being that eminence next 
the temple. See Ear. 
Hircus, a goat, in astronomy, a star of 
the first magnitude, the same with Capella. 
See Capella. 
Hircus is also a name used by some 
writers for a comet, encompassed, as it 
were, with a mane, seemingly rough and 
hairy. 
HIRTELLA, in botany, a genus of the 
Pentandria Monogynia class and order. 
Natural order of Rosace®, Jussieu. Es- 
sential character : petals five ; filaments 
very long, permanent, spiral ; style lateral ; 
berry one-seeded. There are three spe- 
cies. 
HtRUDO, the leech, in natural his- 
tory, a genus of the Vermes Intestina class 
and order. The body moves either for- 
ward or backward. There are Seventeen 
species, principally distinguished by their 
colour. The most remarkable are the fol- 
lowing : 
H. medicinalis, or medicinal leech, the 
form of which is well known, grows to 
the length of two or three inches. The 
body is of a blackish-brown colour, marked 
on the back with six yellow spots, and 
edged with a yellow line on each side ; but 
both the spots and the lines grow faint, and 
almost disappear at some seasons. The head 
is smaller than the tail, which fixes itself 
very firmly to any thing the creature pleases. 
It is viviparous, and produces but one young 
at a time, which is in the month of July. 
It is an inhabitant of clear running waters, 
and is well known for its use in bleeding. 
H. muricata, or muricated leech, has a 
taper body, rounded at the greater extre- 
mity, and furnished with two small tenta- 
cula, or horns, strongly annulated and rug- 
ged upon the rings, the tail dilated. It in- 
habits the Atlantic ocean, and is by the 
fishermen called the sea-leech. It adheres 
to fish, and generally leaves a black mark 
on the spot. 
The mouth of the leech is armed with a 
sharp instrument, that makes three wounds 
at once, and may be compared to the body 
of the pump, and the tongue or fleshy nip- 
ple to the sucker : by the working of this 
piece of mechanism the blood is made to 
rise up to the conduit which conveys it to 
the animal’s stomach, which is a membrana- 
ceous skin, divided into twenty-four cells. 
The blood which is sucked out is there 
H h 
