Mastodonioid and Megatherioid Animals. 563 
lightened munificence of the College of Surgeons, all the necessary 
illustrations have appeared, I pass to the generalizations, and learn 
that the Mylodon, in common with the Megatherium and Megalo- 
nyx, are genera of the family of Gravigrada, as distinguished from 
the Tardigrada in the order Bruta. 
Professor Owen then proceeds to a comparison of the anatomy of 
the Mylodon with that of all analogous creatures, and after an able 
analysis, he satisfies himself, and also, I am persuaded, every one 
who has followed his close reasoning, that he has at length ascer- 
tained the true habits and food of this family of mammifers. From 
their dentition, it is inferred that the Megatherium and Mylodon must 
have been phyllophagous, or leaf-eating animals; whilst, from 
their short necks, the very opposite extreme to the camelopard, 
they never could have reached the tops of even the lowest trees. 
Cuvier, on the contrary, suggested that they were fossorial, or dig- 
ging animals; and we all recollect the animated manner in which 
Dr. Buckland attracted us, whilst he described the Megatherium as 
a huge beast, which, resting upon three legs, employed one of its 
long fore-hands in grubbing up whole fields of esculent roots ; 
a habit which procured for it the significant popular name of “ Old 
Scratch.” 
Dr. Lund, a Danish naturalist, had considered the Megatherium 
to be a scansorial or climbing animal; in short, a gigantic Sloth. 
After a multitude of comparisons, Professor Owen rejects the 
explanatiun of all his predecessors. He shows that the mon- 
strous dimensions of the pelvis and sacrum, and the colossal 
and heavy hinder legs, could never have been designed, either 
to support an animal which simply scratched the earth for food, 
or one which fed by climbing into lofty trees, like the diminutive 
Sloth ; and he further cites the structure of every analogous creature, 
either of burrowing or climbing habits, to prove, that in all such the 
hinder legs are comparatively light. What then was the method by 
which these extraordinary monsters obtained their great supplies of 
food? The osteology of the fore-arm has, it appears, afforded 
answers which are valuable, chiefly for their negation of erroneous 
conjectures, such as that the animal was an ant-eater, rather than for 
the habits which it directly elicits. It is, therefore, to the organi- 
zation of the hinder limbs that Professor Owen mainly appeals to 
ascertain the functions of the forefeet and the general habits of the 
Mylodon. 
Arguing that the enormous pelvis must have been the centre 
whence muscular masses of unwonted force diverged to act 
upon the trunk, tail and hind-legs, the latter, it is supposed, formed 
with the tail a tripod on which the animal sat. Professor Owen 
supposes that the animal first cleared away the earth from the roots 
with its digging instruments, and that then seated on its hinder 
extremities, which with the tail are conjectured to have formed a 
tripod, and aided by the extraordinary long heel as with a lever, it 
grasped the trunk of the tree with its forelegs. Heaving to and 
fro the stateliest trees of primeval forests, and wrenching them 
