MEGATHERIUM. 151 
the horizontal distance between the extremities 
of the two transverse processes, being twenty 
inches. If to this we add the thickness of the 
muscles and tendons, and of the shelly integu- 
ment, the diameter of the tail, at its largest end, 
must have been at least two feet ; and its cir- 
cumference, supposing it to be nearly circular 
like the tail of the Armadillo, about six feet. 
These vast dimensions are not larger in propor- 
tion to the adjacent parts of the body, than 
those of the tail of the Armadillo, and as this 
animal applies its tail, to aid in supporting the 
weight of its body and armour, it is probable 
that the Megatherium made a similar use of 
the same organ.* To the caudal vertebrae were 
attached also large inferior spines, or additional 
Chevron bones, which must have added to the 
strength of the tail, in assisting to support the 
body. The tail also probably served for a 
formidable instrument of defence, as in the 
Pangolins and Crocodiles. In 1822, Sellow saw 
portions of armour that had covered a tail, found 
near Monte Video. 
The ribs are more substantial, and much 
thicker, and shorter, than those of the Elephant 
* The tail of the Elephant is remarkably light and slender, 
with a tuft of coarse hair at its extremity, to brush off flies ; that 
of the Hippopotamus is a few inches only in length, and flattened 
vertically, to act as a small rudder in swimming. 
