142 FOSSIL MAMMALIA. 
malous conditions are so far from being defects, 
or sources of inconvenience in the Sloth, that 
they afford striking illustrations of the varied 
contrivances, whereby the structure of every 
creature is harmoniously adapted to the state in 
which it was destined to live. The peculiarities 
of the Sloth, that render its movements so awk- 
ward on the earth, are fitted with much advan- 
tage to its destined office of living entirely upon 
trees, and feeding upon their leaves : so also, if 
we consider the Megatherium with a view to its 
province of digging and feeding upon roots, we 
shall, in this habit, discover the explanation of 
its unusual structure, and apparently incongruous 
proportions ; and find, in every organ, a relation 
of obvious convenience, and of adaptation to the 
office it had to discharge.* 
It will be my present object to enter into such 
a minute investigation of some of the more re- 
markable parts of this animal, viewing them with 
a constant reference to a peculiar mode of life, as 
may lead to the recognition of a system of well 
* The remains of the Megatherium have been found chiefly in 
the southern regions of America, and most abundantly in Para- 
guay ; it appears also to have extended on the north of the 
equator as far as the United States. We have, for some time, 
possessed detailed descriptions of this animal by Cuvier, Oss. 
Foss. vol. 5. and a series of large engravings, by Pander and 
D'Alton, taken from a nearly perfect skeleton, sent in 1789 from 
Buenos Ayres to Madrid. Dr. Mitchell and Mr. Cooper have 
described, in the Annals of the Lyceum of Nat. Hist, of New 
York, May, 1824, some teeth and bones found in the marshes of 
