126 FOSSIL MAMMALIA. 



twenty-eight inches. This enormous bone, pressing on the- 

 ground, gives a firm bearing and solid support to the continu- 

 ous accumulation of weight, which we have been tracing 

 down from the pelvis through the thigh and leg : in fact the 

 heel-bone occupies nearly one-half of the entire length of the 

 hind-foot ; the bones of the toes are all short, excepting the 

 extreme joint, which forms an enormous claw-bone ; larger 

 than the largest of those in the fore-foot^ measurmg thirteen 

 inches in circumference, and having wnthin its sheath a 

 core, ten inches long, for the support of the horny claw 

 with which it was invested. The chief use of this large 

 claw was probably to keep the hind-foot fixed steadily upon 

 the ground.* 



Feet and legs thus heavily constructed, must have been 

 very inefficient organs of rapid locomotion, and may conse- 

 quently seem imperfect, if considered in relation to the or- 

 dinary functions of other quadrupeds ; but, viewed as in- 

 struments adapted for supporting an almost stationary crea- 

 ture, of unusual weight, they claim our admiration equally 

 with every other piece of animal mechanism, when its end 

 and uses are understood. The perfection of any instrument 

 can only be appreciated by looking to the work it is intend- 

 ed to perform. The hammer and anvil of an anchorsmith, 

 though massive, are neither clumsy nor imperfect ; but bear 

 the same proportionate relation to the work in which they 

 are employed, as the light and fine tools of the watchmaker 

 bear to the more delicate wheels of his chronometer. 



Bony Armour. 



Another remarkable character of the Megatherium, in 

 which it approaches most nearly to the Armadillo, and 



* It is probable that the large thick claw, PI. 5 5', was placed on tha 

 second toe of the hind-foot. Its size approaches nearly to that of the first 

 toe of this foot, and both of tliese differ materially in form and propoc 



