46 



presented as distinct in the figures of the Madrid Megatherium, are here 

 broken off; the spine of the fifth sacral vertebra is distinct from its origin. 

 The pelvis, which Cuvier was led to suspect, from the defective condition 

 of that part of the Madrid skeleton, to be naturally open anteriorly as in 

 the small Ant-eater, is here shown to be inclosed by a narrow symphysis 

 pubis. The acetabula are large, excavated by an oblong depression for 

 the synovial adipose tissue, and looking downwards and a little outwards. 

 The size and strength of the ordinary processes of the pelvis, the great 

 breadth of the rough labrum of the iliac bones, and the numerous and 

 well-defined inter-muscular crests indicate the unusual size and vigour 

 of the muscular masses which proceeded from the pelvis in different 

 directions to act upon the trunk and anterior extremities, and upon the 

 hind limbs and tail. They lead to the conviction that the resistance which 

 demanded such forces for its overcoming must have been of a very dif- 

 ferent nature and degree to any that now opposes itself to the labours of 

 the existing vegetable feeders in supplying their daily wants ; whence it 

 may be inferred that the exertion of such forces was associated with 

 equally peculiar habits in the Megatherioid animals*. 



258. The body and left transverse process of the first caudal vertebra. 



259. The neural arch and spine of the same vertebra. 



260. The haemapophyses of the same vertebra. Their proximal extremities 



are expanded, and each supports two oval and nearly flat articular surfaces, 

 separated by a rough tract, an inch and a half in diameter ; they gradually- 

 taper towards their inferior extremities, which terminate obtusely and are 

 not united together, as in the succeeding caudal vertebrae, where they con- 

 stitute by that union, the haemal arch or chevron-bone. 



261. A scorched and mutilated body of the second caudal vertebra. 



262. The neural arch, wanting the spine, of probably the same caudal vertebra. 



* This argument is pursued to its legitimate consequences in the Memoir on the Mylodon, 4to, 

 1842, pp. 138-162. 



