352 



B. S. Lull — Pleistocene Ground Sloth, 



canals are much smaller than in the dorsal last described, 

 though bearing about the same ratio to each other. The 

 zygapophyses are well- developed, the anterior ones being large 

 and bounded externally by prominent wing-like projections 

 which rise nearly to the height of the spinous process. The 

 postzygapophyses, while strong and well-buttressed, are propor- 

 tionately small, as they are entirely enclosed below and later- 

 ally by the prezygapophyses of the following vertebra. The 

 transverse processes unfortunately are not preserved, but must 

 have been of considerable lateral expanse, to judge by those of 

 the succeeding bones. 



Dimensions. 



Centrum, length 51 mm 



depth. 60-5 



width of articular face 67 



Neural canal, height 25 



width 38 



Neural arch, ant.-post. diameter ever zygapophyses 80 



width over prezygapophyses 87 



Total height of vertebra . _ _1 132 



Third caudal. — This bone may belong to another animal, 

 but its general proportions are what one would be led to 



Fig. 7. 



Fig. 7. Third caudal vertebra of Mylodon harlani. One-fourth nat. size. 

 fac, chevron facet ; other lettering as in fig. 4. 



expect were there a single intervening bone between it and the 

 one just described. It may possibly, however, represent the 

 second caudal of a somewhat larger animal. 



In contrast to the first caudal, the median ridge of the neural 

 aspect of the centrum is very slight, though flanked by the 

 usual nutritive foramina which, however, become confluent 



