SKELETON OF THE SLOTH. 189 



fiecl in their huge predecessors to tread the ground, are 

 reduced to rudiments, or are undeveloped; and those only 

 are retained which support the claws, now rendered by their 

 length and curvature admirable instruments for clinging 

 to the branches. The whole structure of the hind and 

 fore limbs is modified to give full effect to these instru- 

 ments as movers and suspenders of the body in the bosky 

 retreats for which the sloths are destined; and, in the 

 same degree, the powder of the limbs to support and carry 

 the animal along the bare ground is abrogated. Accord- 

 ingly, when a sloth is placed on level ground, it presents 

 the aspect of the most helpless and crippled of creatures. 

 It is less able to raise its trunk above its limbs than the \ 

 seal, and can only progress by availing itself of some in- 

 equality in the soil offering a holdfast to its claws, and! 

 enabling it to drag itself along. But to judge of the 

 creative dispensations towards such an animal by ob- 

 servation of it, or reports of its procedure, under these 

 unnatural circumstances, would be as reasonable as a spe- 

 culation on the natural powers of a tailor suddenly trans- 

 ferred from his shopboard to the rigging of a ship under 

 way, or of a thorough-bred seaman mounted for the first 

 time on a full-blood horse at Ascot. Eouse the prostrate 

 sloth, and let it hook on to the lower bougli of a tree, and 

 the comparative agility with which it mounts to the top- 

 most branches will surprise the spectator. In its native 

 South American woods its agility is still more remarkable, 

 when the trees are agitated by a storm. At that time, the 

 instinct of the sloth teaches it that the migration from tree 

 to tree wdll be most facilitated. Swino-ino- to and fro, 

 back downwards, as is its habitual position, at the end of 

 a branch just strong enough to support the animal, it 

 takes advantage of the first branch of the adjoining tree 



