BrADYI’ID-E.' 
JIAMMALIA. Bradypid.®. 1 53 
very nearly twice as long as the hinder extremities, 
and in this feature we arc inevitably reminded of a 
similar arrangement in the limbs of certain qnadru- 
mana whose habits are in some respects analogous to 
those of the family under consideration. On closer 
inspection of the hands, it will be noticed that the 
bones of the carpus and metacarpus are short and 
ankylosed together, whilst the terminal digits are 
long, and furnished with immense hooked claws. 
These prehensile taloirs are closely curved towards the 
palm while not in use, or in a state of rest ; but when 
the animal requires to grasp a fresh branch, they are 
forcibly extended by muscular contraction, assuming 
a position like that given in the raised arm of the 
accompanying representation, above referred to. The 
hind feet are similarly constructed, and a glance at 
their position, with the soles directed obliquely inwards, 
is sufficient to show how unnatural it is to represent a 
Sloth walking all-fours on a plain level surface. In the 
older natural history collections of the United Kingdom, 
nothing is more common than to observe the errors 
into which taxidermists have fallen in mounting and 
displaying the stuffed skins of Sloths; and we could 
still point to fine collections where the tardigrade 
edentates may be seen sprawling on the floor in the 
most approved style, with their backs toward the sky ! 
Ha^'ing personally inspected, with care, the principal 
museums of natural history in London, Edinburgh, 
Glasgow, and Dublin, we have no hesitation in saying 
that, if any one vdshed to see the way in which Sloths 
ought to be stuffed, they would do ■well to take a 
glance at the specimens preserved in the museum of 
Trinity College, Dublin — and they are not the only 
evidences of taxidermal skill to be seen in the Irish 
capital. But, to return to our skeleton, and the 
figure reduced from that given in Cuvier’s celebrated 
“Ossemens Fossiles” — let us next examine the head 
(fig. 52). Here we have a striking contrast Avhen 
compared with the attenuated crania of the ant-eaters. 
Fig. 52. 
Skull of the Sloth. 
Tlie Sloth’s head is short, rounded, flat, and truncated 
at the muzzle ; the jaws are generally furnished with 
eighteen molar teeth — the anterior pair, above and 
below, having been regarded by Cuvier as incisors ; 
the young individual carries twenty molars. In the 
construction of the bones of the trunk, and especially of 
the pelvis, we notice other interesting adaptations to the 
peculiar habits of these creatures ; but among these we 
have only space to mention tlie remarkalfle elongation 
VoL. I. 20 
of the neck. This cervical extension was at one time 
supposed to be due to the presence of nine true neck- 
vertebrse ; but some years since. Professor Bell satis- 
factorily demonstrated, from prepared skeletons in his 
own collection, that the so-called eighth and ninth 
cervical veretebrm were, in reality, true dorsal segments, 
seeing that he had discovered a pair of little rudi- 
mentary ribs attached to each of the osseous elements 
in question. “The object,” says Mr. Bell, “of the 
increased number of vertebrae in the neck, is evidently 
to allow of a more extensive rotation of the head ; for, 
as each of the bones turns to a small extent upon the 
succeeding one, it is clear that the degree of rotation of 
the extreme point will be in proportion to the number 
of movable pieces in the whole series. When the 
habits of this extraordinary animal are considered, 
hanging as it does from the surface of boughs with the 
back downwards, it is obvious that the only means by 
which it could look towards the ground must be b}" 
rotation of the neck ; and as it was necessary, in order 
to effect this without diminishing the firmness of the 
cervical portion of the vertebral column, to add certain 
movable points to the number possessed by. the rest of 
the class, the additional motion was acquired by modi- 
fying the two superior dorsal vertebra, and giving 
them the office of cervdeal, rather than infringing on a 
rule which is thus preserved entire without a single 
known exception.” As we shall immediately have 
occasion to return to the consideration of the habits of 
these animals, we ha\'e here only further to observe 
that the Sloths are all natives of the forests of South 
America, where they feed upon vegetable matters, 
chiefly leaves. The extinct genera, Megatherium, 
Megalonyx, Scelidotherium, Erinathopsis, and Erep- 
todon, are also referable to this family, forming the 
subdivision of gravigrade edentates. 
THE AI {Bradypus tridactylus) or Three-Toed 
Sloth — Plate 17, fig. 55 — is the best known of all the 
species. The specific term applied to it rests upon the 
arbitrarily assumed grounds that it is the only species 
which is furnished with the three toes ; but there is 
every reason to believe that at least two other Sloths — 
the B. gularis of Piiippell, B. torquaius of Illiger, and 
B. infuscatus of Wagler being regarded as so many 
distinct species — have tridactylous feet. Be this as it 
may, the generality of naturalists appear content to retain 
the old Linnsean appellation, and we shall not deviate 
in the present instance from their combined authority. 
The Ai inhabits the most secret recesses of the South 
xVmerican forests. The body is enveloped by a coarse 
shaggy fur, and so disposed about the short round 
head, as to impart to the physiognomy a human look. 
The fur has a greyish colour generally, young indi- 
■viduals being frequently spotted with browir and white ; 
the under parts have usually a light fulvous tint. 
When describing the skeleton, we took occasion to 
remark somewhat on the habits of this animal, and 
especially referred to its awkward behaviour when placed 
on a level surface. One of the most singular errors 
into which the great French anatomist fell, was that 
of ascribing to the Ais deficiencies and imperfections 
of organization, as if they were not well adapted to the 
mode of existence which the Creator had been pleased 
