12 
NOTICE OF THE MEGATHERIUM. 
§ 3. PHYSIOLOGICAL FEATURES. 
Let, us now imagine the bony frame-work of this gigantic animal clothed with flesh and 
instinct with life. There towers up before us a huge, ungainly beast, eighteen feet in length 
and eight feet high, having a Tapir like head, an elephantine body, and hind feet and tail 
which find no match in geologic or historic time. Such mammoth haunches, nearly 6 feet 
across ; such singular extremities ; so slow in his movements ; and so stupid in look,— we 
wonder at the strange part he must have played in the economy of the ancient world. We 
see him the lord of the Pampas, — swaying a wider realm than the Incas of Peru ; for his size 
and strength most certainly placed him at the head of the Animal Kingdom. The brain of the 
Megatherium must have been less by nearly one half than that of the Elephant ; for the vertical 
diameter of the cranial cavity is only 4f inches, and the transverse diameter but six. We 
infer from this, as well as from other features, that it was a creature of fewer instincts than the 
present monarch of terrestrial mammals. The general proportions of the former resembled, 
with some variations, those of the latter. Its body was relatively as large ; its head much 
smaller ; its legs shorter and thicker ; and its neck a very little longer. It probably exceeded 
more than a hundred-fold the bulk of any living Edentate. Its thick and callous hide was 
very probably scantily clothed with coarse, stiff' hair, Ike the Elephant’s* Its prehensile organs 
were w 7 ell supplied. To the tongue of a Giraffe and the proboscis of a Tapir there was added 
a perfectly developed clavicle, and the power of rotating the bones of the fore-arm. The 
vertebrae of the neck show, moreover, by their articular surfaces, the freedom with which the 
animal’s head was carried in all directions in front of the body. As we have before observed, 
the monster walked, like the Ant-eater, on the outside edge of its fore-feet, on a marginal, hoof- 
like callosity, resting mainly on the fifth finger and the joint of the fourth, with the superior^ 
claw-bearing toes bent inwards. The feet presented a combination, hitherto unknown, of 
ungulate and unguiculate characters. At the same time, the very arrangement of the bones, 
which permits the co-existence of hoofs and claws in the same foot, in a great measure 
provides also for the efficiency of the unguiculate digits in their application to the violent 
exertions which were habitual to the living animal. While in the Cat tribe the claws are 
kept sharp and serviceable by the mechanism for their retraction, in the Megatherium the 
same effect was gained, and they were prevented from impeding the march of the animal, by 
their oblique introflection, and by the concentration of the superincumbent weight on the 
outer toes. The extreme length of the fore-foot from the top of the wrist to the tip of the 
claw was 28 inches. The sole of the hind-foot was also turned inwards, ; and its rough surface 
bespeaks the thick and callous integument with which it was shod. The long heel afforded a 
firm posterior fulcrum ; while the powerful claw of the middle toe kept the foot fixed upon the 
* We are led to make this conjecture as to the probable outer covering of the Megatherium, from the 
character, in this respect, of the Elephant, Rhinoceros, Tapir, and other huge Herbivora of the present period. 
But it is still well to bear in mind that it is in the Edentates among Mammals that we find the most extreme, 
— as the fullest — developments of the tegumentary system. The Megatherium may, perchance, have had as 
abundant and as peculiar a covering as has the shaggy, coarse-haired Sloth ; the Phatagin with its acute, imbri- 
cated scales ) or the Armadillo with its stiff coat of mail. 
