DESCRIPTION OF SLOTHS. 153 



that it supported itself on the sides of its great hind claws. Naturally, the animal took its time 

 in moving, and as it was never seen to be lively, it received the name of Sloth. Interesting 

 from being so different in its habits from other arboreal animals, it became much more so, to 

 naturalists, when, its remarkable construction was ascertained ; but still the hairy creature with a 

 short face, small head, long neck, hardly any tail, and very long front limbs, retained its popular 

 name. 



A very slight examination of one of the Sloths showed that it had no front teeth, that is to say, 

 neither incisors nor true canine teeth, and that the hinder teeth the false and true molars were not 

 like those of any other mammal. The back teeth, few in number, have since been ascertained to be 

 exceptionally simple in their structure, and evidently the masticating process is very simple. 

 But when it was noticed that the Sloth fed upon leaves and young twigs, the absence of the 

 necessity for more elaborate teeth was acknowledged. Then it was observed that they had very 

 long arms, or rather fore limbs, for the fore-arm bones and the humerus are all unusually long, and 

 also that they had great power of movement. Moreover, it was seen that the fingers were reduced 

 to three in number in some kinds, and to two in others, and that they were furnished with long 

 and strong claws, which did not interfere with a great amount of mobility in the wrist. The 

 length of limb, the mobility of the wrist, and the great claws, enable the Sloth to bring the 

 leaves to its mouth, to hang on, and to walk, as it were, beneath the branches. An examination of 

 the hind limbs showed that they were shorter than the others, and always furnished, in all kinds of 

 Sloths, with three great claws. But the ankle seemed to be turned in, as if there was a state of 

 " club-foot." This condition would enable the toes to clasp a bough without effort, but it would 

 prevent the sole from being placed flat on the ground. As the knowledge of the anatomy of these- 

 constant tree-livers progressed, other modifications of structure, equally important in relation to the 

 peculiar arboreal life and food, were gradually discovered. For instance, a remarkable flexibility of 

 the neck, produced by the peculiar arrangement of the vertebrae ; a rete mirabile, to a certain extent, 

 in the' limbs, resembling somewhat that in the Lemurs (Vol. I., pages 213, 245), and a complicated 

 stomach suited for the digestion of leaves, and foreshadowing that of the Ruminants. 



Two different kinds of Sloths were described in the first instance, and subsequently, several 

 others. The first kinds known were the Ai, a Sloth with three claws on the fore limb, and the Two-toed 

 Sloth, with two claws on the fore limb. The Ai was called Brady pus tridactylus, and the other the 

 Unau, or BradypiM didactylus, names which have been changed somewhat, as will be seen further on. 



Sloths are caught without much difficulty, and their habits, in captivity, have been observed 

 in South America, and also after their removal to Europe. Waterton writes ' f on the subject : 



" Some years ago I kept a Sloth for several months. I often took him out of the house and placed 

 him on the ground, in order to have an opportunity of observing his motions. If the ground were rough 

 he would pull himself forward by means of his fore-legs, at a pretty good pace, and he invariably 

 shaped his course towards the nearest tree : but if I put him upon a smooth and well-trodden part of the 

 road, he appeared to be in trouble and distress. His favourite abode was the back of a chair, and often 

 getting all his legs in a line upon the topmost part of it, he would hang there for hours together. The 

 Sloth, in its wild state, spends its whole life upon trees, not upon the branches, but under them; he 

 moves suspended from the branch, he rests suspended from it, and he sleeps suspended from it ; hence 

 his seemingly bungled conformation is at once accounted for. One day, crossing the Essequibo, 

 I saw a large Two-toed Sloth on the ground upon the bank, and although the trees were not twenty 

 yards from him, he could not make his way through the sand in time enough to make his escape 

 before we landed. He threw himself on his back and defended himself with his fore-legs. I took 

 a long stick and held it for him to hook on, and then conveyed him to a high and stately Mora. 

 He ascended with wonderful rapidity, and in about a minute he was almost at the top of the tree. He 

 now went off in a side direction, and caught hold of the branch of a neighbouring tree, and then proceeded 

 towards the heart of the forest." 



At Santos, in Brazil, in 1826, Mr. Burchell kept a tame Sloth, a Bradijpus tridactylus, which at the 

 end of two months pined and died. It fed exclusively on the buds and leaves of a species of Cecropia, 

 a tree having a slender stem of thirty or forty feet long, with horizontal branches, hollow internally- 



* AVaterton's "Wanderinjcs," PP. 161, 284. 



