964 MAMMALIA—SLOTH. 
and on each side of its head, under the ears. Its legs are short, with four 
toes on the fore, and three on the hind foot ; and it has no tail, 
These animals inhabit the banks of rivers, and are found in damp and hot 
places of South America; the flesh is very good to eat, and excessively fat; 
their skin, also, is eaten as that of a pig. The natives of Brazil consider 
the flesh to be a great delicacy ; a perpetual war is therefore carried on 
against these animals. Hunters find it very difficult to take them alive; 
and when they are surprised in their burrows, which have two openings, 
they defend themselves, and bite with great rage and inveteracy. When 
pursued, they take to the water, and escape by diving. If attacked by dogs, 
it defends itself vigorously. Their skin, though covered with short and 
rough hair, is valuable, because it is spotted on the sides. These animals 
bring forth young in abundance: men, and animals of prey, destroy a great 
quantity of them, and yet the species is still numerous. They are peculiar 
to South America, and are found no where in the Old Continent. 
ORDER, SEVEN DT ER-EDENT AMA... 
Animats of this order have no incisors in either jaw ; sometimes canines 
and molars, or molars only ; often no teeth at all; extremities terminated 
with toes, in number variable, armed with strong nails; orbital and tem- 
poral fossz united. se 
THE UNAU- AND THE: Al? ORCS 0 TH. 
THESE two animals have the epithet of sloth given to them both, by most 
authors, on account of their slowness, and the difficulty with which they 
walk. The unau, or two-toed sloth, has no tail, and only two nails on the 
fore feet. The ai, or three-toed sloth, has a short tail, and three nails on 
every foot. The nose of the unau, is likewise much longer, the forehead 
higher, and the ears longer than those of the ai. It differs also in the hair. 
As for its interior, its viscera are both formed and‘situated differently ; but 
the most distinctive, and, at the same time, the most singular character, is, 
that the unau has forty-six ribs, while the ai has but twenty-eight. This 
alone supposes two species, quite distinct one from the other; and these 
forty-six ribs, in an animal whose body is so short, is a kind of excess or 
1 Bradypus didactylus, Lr. 
2 Bradypus tridactylus, Lis. The genus Bradypus has two upper and two lower 
canines ; four Bune and six lower molars. Canines higher than the molars, pyramidal 
and pointed; molars cylindrical; head small, rounded; muzzle truncated ; neck short, 
nostrils at the extremity of the muzzle; anterior extremities longer than the postericr 
with two or three united toes, terminated by very long, robust nails; fur thick and harsh, 
with the hair of the fore arms directed upwards; stomach membranous, divided inte 
lnany sacs; intestines short; no cecum. 
