150 



M A M M A L I A. 



one branch to another, they are efficient for hardly 

 any purpose, save this very peculiar motion ; and thus 

 they are perhaps more exclusively climbing instru- 

 ments than the fore feet of any other tree animal. 

 The hind legs have the same twisting articulation as 

 those of the tree apes, so that when they are on the 

 ground the outer edges of the feet are points of such 

 rest as the animal possesses there. They are neces- 

 sarily very unstable points of rest ; and as the ani- 

 mals have besides great difficulty in stretching their 

 legs, and cannot possibly stretch them all at the same 

 time, their progress on the ground is exceedingly 

 slow, and performed with great apparent labour and 

 pain. The labour and pain are, however, only appa- 

 rent, not real ; but the animals are gentle and timid 

 in their dispositions ; and as they have not the power 

 of escaping from enemies, they are much alarmed, 

 and, like all animals when alarmed, they utter plain- 

 tive cries. They have been pitied and described as 

 helpless, and even imperfectly formed, in consequence 

 of this want of adaptation for walking, which is vul- 

 garly regarded as the characteristic of the mammalia. 

 To understand their organisation aright, we must, 

 however, look at them in their proper place ; for a 

 sloth upon the ground is just as much out of its ele- 

 ment as a race-horse in a deep quagmire, or a hawk 

 in the sea. 



Under the article Ai there will be found some 

 details of the history of the three-toed sloth ; and we 

 here introduce a figure of the two-toed one, for the 



Kurpose of illustrating the mode in which these singu- 

 ir creatures make their way, which is always when 

 the forests are agitated by strong winds. That the 

 sloths do not tumble even upon such occasions, unless 

 where the trees are actually broken by the wind, 

 shows how well they are fitted for their place in nature. 



There is reason to believe that sloths are tar more 

 numerous than is generally supposed. They inhabit 

 the deepest forests that are known in any part of the 

 globe, ranging from Guyana to the dry country 

 southward of Upper Peru, and enjoy a depth both of 

 solitude and of shade, to which there is nothing equal 

 in any other part of the world. It is for the very 

 fastnesses of those forests that they are adapted. The 

 difficulty they have in descending and ascending 

 again, necessarily stops them wherever there is an 

 opening in the forest ; while the agility of their neigh- 

 bours the monkeys, adapts them better for the margins 



of those openings than for the thickest parts of the 

 forests. Those forests are in many places so exceed- 

 ingly close and dark, and so frequently flooded or 

 covered with stagnant water among the roots of the 

 trees, that there are perhaps hardly any mammalia in 

 them except sloths, except it be the manate in the 

 waters. Thus we see that their curious structure, and 

 equally curious mode of life, are given them for the 

 wisest purposes, and that mammalia differently con- 

 structed, could not subsist in those localities which 

 they inhabit. There is no food for any herbivorous 

 animal of this class lower down than the dwelling of 

 the sloths ; and unless in places where there are 

 herbivorous ones to supply food for them, there can 

 of course be no carnivorous ones. The peccaries and 

 other herbivorous mammalia of South America are 

 found in the openings, and not the depths of the vast 

 woods of that country, and therefore the jaguars and 

 other predatory animals are found in the same. Thus, 

 in the depths of the forests the sloths dwell in peace 

 and safety, perhaps more so than any known race of 

 animals. Nor must we suppose that the part which 

 they act in nature is an unimportant one. Those lux- 

 uriant forests are places of great productiveness and 

 plenty ; and it is a law traceable through the whole 

 of nature, that wherever productiveness is in excess, 

 there is always provided a sufficient number of con- 

 sumers for keeping it within those bounds which 

 appear to be essential to the health and preservation 

 of the whole. The reason of this is equally obvious 

 and traceable through the whole of nature. Every 

 production of nature must exercise its productive 

 powers within certain limits, otherwise it exercises 

 them to its own destruction. We observe in a neg- 

 lected garden or field, that natural weeds first put 

 down the cultivated plants, and then one weed puts 

 down another, until some one gets the mastery, ex- 

 terminates all the rest, and quickly follows them to 

 oblivion. That the powers of vegetation are very 

 great in those American forests must be admitted, 

 but still if they were left to be overwhelmed in the 

 ruins of their own leaves, they would perish in time ; 

 and to prevent this appears to be the principal service 

 rendered by the sloth. 



The sloths may be considered as the most lofty- 

 inhabiting of all the tree animals, and indeed of all 

 climbing mammalia, that is to say, if we estimate 

 their abode from the ground immediately under them. 

 They also approach in some of their characters the 

 grazing ruminantia, much as they differ from these 

 in other characters. Their feet are simply organs of 

 locomotion, not applied, and from their structure not 

 very applicable, to any other purpose. With them 

 therefore we shall close our brief survey of the climb- 

 ing organs of animals. There are a few other animals 

 which can climb, as, for instance, the goats and ante- 

 lopes which inhabit high and rocky mountains. These 

 however, climb by bounding, in which the elasticity 

 of the body comes into play, and not by grasping in 

 any manner with the feet, which are not fitted for 

 any such purpose ; and though the animals are, in 

 some of the species exceedingly expert in gaining 

 heights, yet they belong to the walking animals rather 

 than to the climbers. The few remarks which we have 

 to offer concerning them, can therefore be introduced 

 with more propriety and effect in our notice of these. 



Organs of Walking. All these may be considered 

 as belonging to one general class, though there 

 are great diversities in their forms, in the modes 

 of using them, and also in the other purposes which 



