79 



use of such a proboscis in obtaining nutritious roots, on the Cuvierian hypothesis 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 buried parts of 

 vegetables ; but no trace of the prenasal bone exists in the skull of the Megatherium. 

 A short proboscis might be useful in rending off the branches of a tree when prostrated 

 and within reach of the low and broad-bodied Megatherium, but this office has been 

 provided for by the organization of the tongue, of which, both the hyoid skeleton by its 

 strength and articulation, and the foramina for the muscular nerves by 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 on 

 the humerus, and in the possession of complete clavicles. These bones are requisite 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 merely 

 rudiments 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 clue 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 Megatherium the depth of the claw-phalanx exceeds its breadth, especially in the 

 large one of the middle finger ; and not any of the claws can be extended into a line 

 with the metacarpus, but they are all more or less bent inward and downward. Thus, 

 although they might be used for occasional acts of scratching up the soil, they are 

 better adapted for grasping ; and the whole structure 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. LuNDf supposes, a scansorial 

 quadruped ; for, in the degree in which the fore 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 length, and from 

 the increased strength and the inequality of the claws, especially the disproportionately 

 large size of that weapon of the middle digit, that the fore foot of the Megatherium was 

 occasionally applied by the short and strong fore limb in the act of digging : but its 

 analogy to that of the Anteaters teaches that the fossorial actions were limited to the 

 removal of the surface-soil, in order to expose something there concealed, and not for 

 the purpose of burrowing. Such an instrument would be equally effective in the dis- 

 turbance of roots and of ants ; it is, however, still better adapted for grasping than for 



• Das Riesen-l'aulthier, Ac. fol. 1821, p. 16. 



t Blik paa Brasiliena Dyreverden for sidste Jordomva-ltning, at' Dr. Lund, 4to. Kjobenbavn, 1838, p. 21. 



M 



