THE ANIMAL WORLD OF BRAZIL 



which would be a protection against birds of prey. At other times 

 I would see it clambering down like a gymnast equipped with hooks 

 instead of fingers. The head turns cautiously, seeking for the best 

 purchase ; it can be turned until it looks directly backwards, for the 

 neck is very mobile in the Three-toed Sloth, since it possesses nine 

 cervical vertebrae, whereas other mammals, including the giraffe, 

 have only seven. I have seen the Sloth hook its way down perpen- 

 dicular lianas, so firmly do its claws hold ; even when the animal is 

 dead they do not relax, so that a Sloth which has been shot often 

 remains hanging. From time to time the Sloth slings itself along a 

 bough and eats the leaves, for whose digestion it has a stomach 

 divided into several compartments, in each of which the food is 

 exploited in a different manner. 



The Sloth is a fascinating creature, and although its movements 

 are slow, they are extraordinarily certain. I once saw a Sloth which 

 wanted to climb from a palm into another tree, but when it slung 

 itself forward along a palm-leaf the leaf was so far pulled down by 

 its weight that it could no longer reach the tree. Quietly it went 

 back and embraced two palm-leaves, but as these were not rigid 

 enough it made another attempt with three leaves, which did support 

 its weight, and having reached the end of the three leaves, it was 

 able to reach and grasp the nearest bough of the adjacent tree. In 

 Santos, however, I once saw a Sloth in the grass, looking about it 

 with its owlish face, and pushing itself along from one tree to another. 

 Fortunately there were no dogs about. 



The next group of animals which came to South America was 

 that of the Rodents, in which the canine teeth are lacking, while 

 the incisors, two in the upper and two in the lower jaw, have 

 developed into sharp cutting-chisels, which grow continually, and 

 must be worn down by constant gnawing, since they have no roots 

 which would otherwise limit their growth. It is these large incisors 

 which give the animal the truncated profile by which the rodent 

 may always be recognized. The Rodents are a very ancient order, 

 which seems to have arisen at the very base of the mammalian 

 family tree, for they still display many characteristics which are 

 reminiscent of the reptiles. For example, like the lizards, they often 

 have scales on their frequently hairless tails. The Rodents have 

 undergone a tremendous expansion; the number of their species 

 represents more than a third of the whole mammalian world, and 



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