NORTHERN TWO-TOED SLOTH (COSTA RICA).
This is also known as Hoffmann's Sloth. The appellation "two-toed" refers to the fore limb only. The hind foot has three toes.
In the matter of personal appearance Nature has not been kind to the Sloth, though it is certainly true that there are many uglier animals—not including those, such as some of the Monkey Tribe and certain of the Swine, which are positively hideous. The mode of life of the sloth is certainly remarkable, for almost its whole existence is passed among the highest trees of the densest South American forests, and passed, too, in a perfectly topsy-turvy manner, inasmuch as it moves from bough to bough with its legs up in the air and its back towards the ground. It walks and sleeps suspended beneath the boughs instead of balanced above them, securely holding itself by means of powerful hooked claws on the fore and hind feet. This method of locomotion, so remarkable in a mammal, coupled with the deliberate fashion in which it moves, and the air of sadness expressed in its quaint physiognomy—large-eyed, snub-nosed, and earless—on which there seems to dwell an ever-present air of resignation, led the great Buffon to believe that the sloth was a creature afflicted of God for some hidden reason man could not fathom! His sympathy was as certainly wasted as his hasty conclusion was unjustified. There can be no doubt but that the life led by the sloth is at least as blissful as that of its more lively neighbours—the spider monkeys, for instance. Walking beneath the boughs comes as natural to the sloth as walking on the ceiling to the fly.
The sloth sleeps, as we have already remarked, suspended from a bough. During this time the feet are drawn close together, and the head raised up and placed between the fore legs, as in the cobego, which we depicted asleep on [page 170], as our readers will remember. In the sleeping position the sloth bears a striking resemblance to the stump of a lichen-covered bough, just as the cobego resembles a fruit. Thus is protection from enemies gained. The resemblance to lichen is further aided by the fact that the long, coarse hair with which the sloth is clothed becomes encrusted with a peculiar green alga—a lowly form of vegetable growth—which lodges in certain grooves or flutings peculiar to the hair of this animal. Such a method of protection is unique amongst the Mammalia. As the sloths sleep by day and feed by night, the usefulness of such a method of concealment is beyond question.
Photo by L. Medland, F.Z.S.] [North Finchley.
THREE-TOED SLOTH.
A remarkable peculiarity about the three-toed sloths is the fact that they have no less than nine vertebræ in the neck, instead of seven, as is usual among mammals.
The strange form of locomotion of the sloths renders separate fingers and toes unnecessary, and so the fingers and toes have come to be enclosed in a common fold of skin, extending down to the base of the claws.
The sloths stand out in strong contrast to the volatile spider monkeys, with whom they share the forest; these have added a fifth limb in the shape of a prehensile tail, by which they may suspend themselves at will. The sloths, on the contrary, have no tail; they move deliberately, and do not require it. The monkeys move by prodigious leaps, taken not seldom by gathering impetus by swinging on their tails.