times a foot and a half in length. These 
horny substances are said to be loose when 
the animal reposes, or is calm, hut to be 
erected irremoveably when he is highly 
agitated ; a circumstance asserted by Dr. 
Sparman, though ridiculed by Mr. Bruce. 
It is, however, observed by Dr. Shaw, that, 
on inspection of the horns and the skin on 
which they are seated, they do not appear 
firmly attached to the bone of the cranium. 
This animal, after having devoured the foli- 
age of trees, rips up their trunks, and 
dividing them with his horns i»to a sort of 
laths, fills his immense jaws with these fruits 
of his labour, and masticates them with as 
much facility as an ox does grass. Its 
swiftness is great considering its bulk, but 
its security arises not so much from speed 
as from its directing its course to thickets 
and woods, where sapless trees are broken 
by its violence, and green ones after yielding 
to it, recoil upon the pursuers, and strike 
them from their horns sometimes with fatal 
consequences. In an open plain the horse 
speedily overtakes him, on which he makes 
a thrust with his horn at the horse, which 
the latter easily evades by its agility. A 
man at this moment drops from behind the 
chief horseman, with a spear, and, as the 
rhinoceros sees' only immediately before 
him, wounds him in the tendons of his heels, 
and tlius totally disables him from further 
motion. He is also occasionally taken by 
night while rolling himself in mire, in which 
he appears to experience a rapture which 
deprives him of all suspicion and vigilance ; 
while thus abandoning himself to transport, 
tlie hunters approach and fix a mortal 
wound, by their spears or muskets, in his 
belly. See Mammalia, Plate XVIII. fig. 5. 
RHINOMACER, in natural history, a 
genus of insects of the order Coleoptera. 
Antennae setaceous, seated on the snout ; 
four feelers, growing thicker towards the 
end, the last joint truncate. There are 
three species, found in Italy and Sweden. 
RHIZOBOLUS, in botany, a genus of 
the Polyandria Tetragynia class and order. 
Essential character: calyx, half five-cleft ; 
petals five; germ four-lobed, superior; 
nuts four, one-celled, one-seeded. There 
are two species, viz. R. butyrosiis, and R. 
tuberculosus, both natives of Guiana. 
RHIZOPHORA, in botany, a genus of 
the Dodecandria Monogynia class and or- 
der. Natural order of Holorace®. Capri- 
folia, Jussieu. Essential character : calyx 
four-parted ; corolla four-parted ; seed one, 
very long, fleshy at the base. There are 
six species, of which R. mangle, or man- 
grove tree, commonly attains the height of 
fifty feet ; it is generally found on the bor- 
ders of the sea, in whose waters alone it 
seems to thrive, and there only in such 
places as have a soft and yielding bottom ; 
its larger branches frequently emit soft afid 
weakly appendicles, having the appearance 
of' so many slender, leafless branches, al- 
ways bending downwards; but as these 
are softer, and furnished each with a large 
column of a lax, spongy pith in the centre ; 
they grow more luxuriantly than the other 
parts of the tree, and reach the mud in a 
short time, where they throw out a num- 
berless series of slender fibres, which in 
time become roots, to supply the stem 
more copiously with nourishment, whilst 
they become so many props or limbs to the 
parent tree ; the trunk seldom grows to 
any considerable thickness ; the bark is ex- 
cellent for tanning leather ; it performs this 
operation more perfectly in six weeks, than 
oak bark will do in ten. The mangrove is 
a native both of the East and West Indies, 
of the Society and Friendly islands, the 
New Hebrides, and New Caledonia, in the 
South Seas. 
RHODIOLA, in botany, a genus of the 
Dioecia Octandria class and order. Natu- 
ral order of Succulentae. Sempervivae, Jus- 
sieu. Essential character : male, calyx 
four-parted ; corolla four-petalled ; nectary 
four : female, calyx four-parted ; corolla 
four-petalled ; nectary four ; pistils four ; 
capsules four, many-seeded. There are 
two species, viz. R. rosea, common, or yel- 
low rose-wort, and R. bitternata. 
RHODODENDRUM, in botany, a ge- 
nus of the Dodecandria Monogynia class 
and order. Natural order of Bicornes. 
Rhododendra, Jussieu. Essential charac- 
ter : calyx five-parted ; corolla funnel-form ; 
stamina declined ; capsule five-celled . 
There are nine species. 
. RHODORA, in botany, a genus of the 
Decandria Monogynia class and order. Na- 
tural order of Bicornes. Rhododendra, 
Jussieu, Essential character; calyx five- 
toothed ; petals three, unequal ; stamina 
declined ; capsule five-celled. There is 
only one species, viz. R. canadensis, a na- 
tive of Newfoundland, fiom which place it 
was introduced by Sir Joseph Banks. 
RHOEADEjE, in botany, the name of 
the twenty-seventh order in Linnaeus’ Frag- 
ments of a Natural Method, consisting of 
the poppy, and a few genera which resem- 
ble it in habit and structure. The plants, 
