180 EXTINCT MONSTERS. 
powerful claws, such as might be used for scratching up the 
ground near the roots of a tree, and it was at one time thought 
that this was the way in which the creature obtained its leafy food, 
namely, by digging up trees by the roots and then devouring the 
leaves. But Professor Owen had another explanation. 
As in the living sloths and armadillos (edentata 1), there: arem0 
teeth in the fore part of the jaw. The molar teeth, of which there 
are five on each side of the upper jaw, and four in the lower, are 
hollow prismatic cylinders, straight, seven to nine inches long, 
and implanted in deep sockets. There are no other teeth, but 
these are composed of different substances, and so arranged that, 
as the tooth wears, the surface always presents a pair of trans- 
verse ridges, thus producing a dental apparatus well suited for 
grinding up vegetable food. In the elephants, which live on 
similar food, the grinding is effected by great molar teeth, which 
are replaced by new ones as the old ones are worn away. In the 
Megatherium, however, only ove set of teeth was provided; but 
these, by constant upward growth, and continual addition of new 
matter beneath, lasted as long as the animal lived, and never 
needed to be renewed. 
On looking at the model so skilfully set up at South Kensington, 
and especially at the front part of the skull, it will be seen that 
the snout and lips must have been somewhat elongated, possibly 
into a slight proboscis like that of the tapir. The specimens of 
the lower jaw in the wall-case close by show that it was much 
prolonged and grooved. ‘This fact must be interpreted to mean 
that the creature possessed a long and powerful tongue, aided by 
which it could, like the giraffe, strip off the small branches of the 
trees which it had broken or bent down within its reach. 
A bony shield (or carapace) of a great armadillo was found 
with one of the specimens described by Mr. Clift, and Buckland 
and others thought it belonged to the Megatherium ; but Owen 
1 This word, which means éoo¢h/ess, is misleading. All the edentata, how- 
ever, agree in having no front, or incisor, teeth. 
