366 



PICTURESQUE SKETCHES 



thirteen inches in circumference at the root; and in 

 this respect, therefore, the analogy with the sloth is 

 still preserved. 



The tail of the Megatherium is a part in which the 

 extinct genus differed essentially from the sloth. Its 

 length was very considerable, certainly not less than 

 five feet. The vertebrae of which it is composed are 

 so large, that the circumference of this organ near 

 the root must have been between five and six feet. 

 Large processes are attached to the caudal verte- 

 brae, which would strengthen it greatly; and there 

 are indications on the back of extremely powerful 

 muscles to work it. It assisted, no doubt, in occa- 

 sionally supporting part of the weight of the body. 



Having thus considered the remarkable structure 

 of the hinder extremities and their vast strength, let 

 us turn next to the fore-legs, and learn the relation 

 exhibited by them to the rest of the body. 



The fore extremity of the Megatherium consists 

 of a scapula or blade-bone, a humerus or shoulder- 

 bone, two bones of the fore-arm, wrist-bones, bones 

 of the palm of the hand and finger-bones ; including 

 therefore every perfection of structure manifested in 

 the mammalian type except an opposing thumb. 

 Some of the fingers are, however, imperfectly deve- 

 loped, and were chiefly useful in locomotion. The 

 length of this extremity does not differ greatly from 

 that of the hind leg. 



The shoulder-blade exhibits the general propor- 

 tions and some of the peculiarities of structure be- 

 longing to the class Edentata, and more especially 

 possessed by those requiring to make great and pow- 

 erful use of the fore extremity; and the effect of the 



