PREVIOUS TO THE LAST GEOLOGICAL REVOLUTION. 209 



that this peculiar conformation in the existing creation is 

 found in the sloth, and I have pointed out the effect produced 

 on that animaFs habits, by this organization. An approxi- 

 mation to this conformation is also observed in apes, which, 

 when they walk, place the foot somewhat obliquely on the 

 outer edge, and it is well known that this peculiarity incom- 

 modes them in terrestrial progression, as much as it fits them 

 for climbing. But what in the apes is only, as it were, par- 

 tially indicated, is fully developed in the sloth ; which ani- 

 mal, in consequence of this organization, has been shown to 

 be confined throughout its existence to an arboreal life. 

 Thus in every one of the points of comparison we have in- 

 stituted between burrowers and climbers, we have seen that 

 Megalonyx constantly differs from the former, and resembles 

 the latter : but the point to which I last alluded, I consider 

 to be quite decisive. There is one other character in its or- 

 ganization, which is not quite without weight in reference to 

 our present enquiry, I mean its unusually powerful tail. Now, 

 it is certainly true, that many animals which are not climbers 

 have a powerful tail, as for instance, armadilloes, &c., while 

 others that climb well have none, as sloths, and some apes ; 

 but when we find a remarkably powerful tail attached to an 

 animal, that, according to all probability, was a climber, we 

 are led to infer that this organ must have served for that pur- 

 pose, in other words, that Megalonyx was furnished with a 

 prehensile tail. 



How far the Megatherium is to be considered in the same 

 light as Megalonyx, cannot be decided without an accurate 

 and scientific examination of the skeleton at Madrid. Pan- 

 der and Dal ton do not mention any distortion of the hind 

 foot, neither does their figure exhibit any. It is, nevertheless, 

 quite possible that such may exist, but that it is disguised 

 by the faulty manner in which the skeleton is put up. It 

 strikes me as very unlikely, that two animals which agree 

 so closely in all other striking particulars of their organiza- 

 tion, should differ so much in one of the most important. 

 The Megatherium has been proved by later discoveries to 

 possess the same powerful tail as the Megalonyx ; and as it 

 besides corresponds with the latter entirely in the conforma- 

 tion of its extremities, the same difficulties present them- 

 selves against the supposition of its having been a burrower. 

 But if the Megatherium was really a climber, it must have 

 had still more occasion (on account of its greater size), for 

 that peculiar arrangement of the hind feet, which we have 

 described in the Megalonyx. I am aware that most people, 

 from the immense bulk and clumsy make of these animals, 



