of the Order Edentata. 355 



bivora, they likewise were, of all the quadrupeds provided with 

 formidable claws, the most strictly vegetable feeders. 



And, if we have reason to view the structural differences or 

 superadditions which the Megatherioids present, compared 

 with the Sloths, as being the necessary consequences of an 

 identity of diet in quadrupeds too bulky to climb, and there- 

 fore requiring new powers for the attainment of the foliage, 

 such an interpretation of the peculiarities of their organiza- 

 tion, whilst it confirms the close mutual affinities between the 

 great extinct and small existing phyllophagous Unguiculata, at 

 the same time indicates unerringly the true natural affinities 

 of the whole of this great tribe to the other groups of Mam- 

 malia. 



It would border upon the ridiculous to advocate the claims 

 of the Mylodon to the Quadrumanous order, because its thorax 

 was wide rather than deep, its muzzle broad and truncated, its 

 pelvis expanded, the head of the radius round and apt for ro^ 

 tation, the inflection of the carpus and tarsus free, the long 

 claws prehensile, and the diet exclusively vegetable. Yet the 

 <5laims of the Megatherians to be associated with the Apes and 

 Lemurs, are, on these grounds, equal with those of the Sloths. 



The only modifications in the small tardigrades which might 

 mislead a naturalist into exaggerating the importance of the 

 characters just cited, are due, in fact, to the absence of the 

 characters of the phyllophagous Edentata, by which the Sloths 

 are made inferior to the Megatherioids, without being thereby 

 especially approximated towards the Quadrumana : such, for 

 example, as the removal of the ungulate digits, the loss of the 

 mobility of certain joints in the hands and feet, the diminution 

 of the bulk of ^the body, and the incomplete clavicles in one of 

 the species. 



It is most probable that the Megatherioids, like the Sloths, 

 give birth to a single and unusually large foetus ; but in that 

 case, they would coincide in their uniparous generation with 

 the Elephant and Whale, as much as with the Ape. If their 

 uterus was undivided, as in the Sloths, they would agree with 

 the Armadillos, as well as with the Quadrumanes. The pecto- 

 ral mammae of the Dugong and Elephant shew the insufficiency 

 of this character in determining the natural affinities of a 



