NATURAL HISTORY OF THE PRIMEVAL WORLD. 



45 



food, like the Megatherium, by digging in sandy and 

 sun-scorched plains. 



We close our description of the Megatherium in the 

 words of the eminent geologist already quoted : 



" The size of this extraordinary animal exceeds that 

 of the existing Edentata, to which it is most nearly 

 allied, in a greater degree than any other fossil animal 

 exceeds its nearest living congeners. With the head 

 and shoulders of a sloth, it combined in its legs and 

 feet an admixture of the characters of the Ant-eater, 

 the Armadillo, and the Chlamyphorus ; it probably also 

 still further resembled the Armadillo and Chlamyphorus 

 in being cased with a bony coat of armour. 



' ' Its haunches were more than five feet wide, and its 

 body twelve feet long and eight feet high ; its feet were 

 a yard in length, and terminated by most gigantic claws: 

 its tail was probably clad in armour, and much larger 

 than the tail of any other beast among extinct or living 

 terrestrial mammalia. Thus heavily constructed and 

 ponderously accoutred, it could neither run, nor leap, 

 nor climb, nor burrow under the ground, and in all its 

 movements must have been necessarily slow ; but what 

 need of rapid locomotion to an animal whose occupation 

 of digging roots for food was almost stationary? and 

 what need of speed for flight from foes to a creature 

 whose giant carcass was encased in an impenetrable 

 cuirass, and who by a single pat of his paw, or lash of 

 his tail, could in an instant have demolished the couguar 

 or the crocodile ? Secure within the panoply of his 

 bony armour, where was the enemy that would dare 

 encounter this leviathan of the Pampas ? Or in what 

 more powerful creature can we find the cause that has 

 effected the extirpation of his race? 



" His entire frame was an apparatus of colossal 

 mechanism adapted exactly to the work it had to do ; 

 strong and ponderous in proportion as this work was 

 heavy, and calculated to be the vehicle of life and 

 enjoyment to a gigantic race of quadrupeds, which, 

 though they have ceased to be counted among the living 

 inhabitants of our planet, have, in their fossil bones, 

 left behind them imperishable monuments of the con- 

 summate skill with which they were constructed ; each 

 limb, and fragment of a limb, forming co-ordinate parts 

 of a well-adjusted and perfect whole ; and through all 

 their deviations from the form and proportion of the 

 limbs of other quadrupeds, affording fresh proofs of 

 the infinitely varied and inexhaustible contrivances of 

 creative wisdom." 



These are considerations which should never be for- 

 gotten by the student of natural history. 



The family Megaiheriidce of Professor Owen includes 

 several allied genera of huge Edentata, as the Megalonyx, 

 the Mylodon, and the Scelidotherium, which are chiefly 

 distinguished from the Megatherium by dental peculi- 

 arities. Their fossil remains have all been discovered 

 in the superficial stratum of the Pampas of South 

 America. 



The Mylodon (i.e., Grinder-teeth) was an animal 

 of gigantic sizo, with a short massive neck and a bulky 

 body, like that of the rhinoceros, but in habit and gen- 

 eral structure resembling the Megatherium. It had 

 eighteen teeth five on each side in the upper, and four 

 in the lower jaw ; they were long, simple, fangles?, 



uniform in substance, and nearly straight, with the 

 exception of the first tooth in the upper jaw, which 

 was slightly curved. From the conformation of its 

 jaws, and its dental characteristics, this animal is sup- 

 posed to have fed, like the elephant or the sloth, on 

 the leaves or slender terminal twigs of trees, which its 

 immense strength and the arrangement of its lower 

 limbs enabled it to uproot and level to the ground. 



"They may be supposed, says Professor Owen, "to 

 have commenced the process of prostrating any parti- 



Mylodon robustus. 



cular tree by scratching away the soil from the roots, 

 for which office we find in the Mylodon the modern 

 scansorial fore-feet of the sloth, modified after the type 

 of that of the partially fossorial ant-eater. The com- 

 pressed or subcompressed form of the claws which 

 detracts from their power as burrowing instruments, 

 adds to their fitness for penetrating the interspaces of 

 roots, and for exposing and liberating them from the 

 attached soil. This operation having been duly effected 

 by the alternate action of the fore-foot, aided probably 

 by the unguiculate digits of the hind feet, the long and 

 curved fore-claws, which are habitually flexed and 

 fettered in the movements of extension, would next 

 be applied to the opposite sides of the loosened trunk 

 of the tree, and now the Mylodon would derive the 

 full advantage of these modifications of its fore-feet by 

 which it resembles the Bradypus ; the correspondence 

 in the structure of the prehensile instruments of the 

 existing and extinct sloth, extending as far as was 

 compatible with the different degrees of resistance to 

 be overcome." 



In the small climbing sloth the claws are long and 

 slender, for they have only to sustain the weight of its 

 little body, which is approximated by the action of the 

 muscles towards the grasped branch, as to a fixed point. 

 The stouter proportions of the prehensile hooks of the 

 Mylodon accord with the harder task of overcomi 



the 



