OF CREATION. 



363 



I shall not dwell long on the description of the ver- 

 tebral column and the ribs of the Megatherium. The 

 neck is strong, but not remarkably so. It is of mo- 

 derate length, and differs from that of the three-toed 

 sloth in a point in which this latter quadruped dif- 

 fers from all others, namely, the possession of an addi- 

 tional vertebra of the neck. In this respect, indeed, 

 the two-toed sloth, or unau, (another existing species,) 

 approaches the megatheroid type, but is itself ano- 

 malous, exhibiting an increased number of dorsal ver- 

 tebrae, so that the extinct genus did not agree in this 

 respect with either of the existing sloths inhabiting 

 trees. In the tail, also, the difference is marked not 

 less strongly, for the sloth is unprovided with any 

 such appendage, while it formed a prominent and 

 important organ of support in the Megatherium and 

 other extinct species. 



The ribs, both of the Megatherium and the sloth, 

 are broad, and offer a firm support to the body of the 

 animal. Those which are interlocked among each other 

 to form the breast-bone offer an example of a very 

 singular structure, found not in the sloth but in the 

 ant-eaters, and apparently intended to assist these 

 animals when burrowing through the earth. The 

 resisting power and the strength thus afforded to the 

 fore extremities was exceedingly great. 



But by far the most remarkable part of the mega- 

 there is seen in the posterior portion of the skeleton, 

 commencing with the lumbar vertebree, and including 

 the bones of the pelvis, the tail, and the hinder 

 extremities. 



In all these there may be traced a succession of 

 contrivances strikingly indicative of enormous, un- 



R 2 



