62 



concludes that the Megatherium must have subsisted, like the 

 Sloths, on the foliage of trees; but that the greater size and strength 

 of the jaws and teeth, and the double-ridged grinding surface of the 

 molars in the Megatherium, adapted it to bruise the smaller branches 

 as well as the leaves, and thus to approximate its food to that of the 

 Elephants and Mastodons. The existing Elephants and the Giraffe 

 are specially modified to obtain their leafy food ; the one being 

 provided with a proboscis, and the entire frame of the lofty Giraffe 

 adapting it to browse on branches above the reach of its largest 

 ruminant congeners. If the Megatherium possessed, as Cuvier 

 conjectured, a proboscis, it cannot, judging from the suborbital 

 foramina, have exceeded in size that of the Tapir, and could only 

 have operated upon branches brought near its mouth. Of the use of 

 such a proboscis in obtaining nutritious roots, on the prevalent hypo- 

 thesis that such formed the sustenance of the ^Megatherium, it is 

 not easy to speculate : the hog's snout might be supposed to be more 

 serviceable in obtaining those parts of vegetables ; but no trace of 

 the prsenasal bone exists in the skull. A short proboscis would be very 

 useful in rending off the branches of a tree prostrated and within 

 reach of the low and broad-bodied Megatherium, and it would be 

 aided in this act by the tongue, of which, both the hyoid skeleton, by 

 its strength and articulation, and the foramina for the muscular 

 nerves b}" their unusual area, attest the great size and power. 



As regards the limbs, the Megatherium differs from the Giraffe and 

 Elephant in the unguiculate character of certain of its toes, in the 

 power of rotating the bones of the fore-arm, in the corresponding 

 development of supinator and entocondyloid ridges in the humerus, 

 and in the possession of complete clavicles. These bones are requi- 

 site to give due strength and stability to the shoulder-joint for varied 

 actions of the fore-arm, as in grasping, climbing and burrowing : 

 but they are not essential to scansorial or fossorial quadrupeds ; the 

 Bear and the Badger have not a trace of clavicles, and the mere rudi- 

 ments of these bones exist in the Rabbit and the Fox. We must seek, 

 therefore, in the other parts of the organization of the Megatherium, 

 for a clew to the nature of the actions by which it obtained its food. 

 In habitual burrowers the claws can be extended in the same plane as 

 the palm, and they are broader than they are deep. In the Mega- 

 therium the depth of the claw-phalanx exceeds its breadth, especially 

 in the large one of the middle finger ; and they cannot be extended 

 into a line with the metacarpus, but are more or less bent. Thus, 

 although they might be used for occasional acts of scratching up 

 the soil, they are better adapted for grasping ; and the whole struc- 

 ture of the fore-foot militates against the hypothesis of Pander and 

 D'Alton, that the ^Megatherium was a burrowing animal. The 

 same structure equally shows that it was not, as Dr. Lund supposes, 

 a scansorial C|uadruped ; for, in the degree in which the foot departs 

 from the structure of that of the existing Sloths, it is unfitted for 

 climbing; and the outer digit is modified, after the ungulate type, 

 for the exclusive office of supporting the body in ordinary terrestrial 

 progression. It may be inferred from the diminished curvature and 



