Mylodon Jutrlani, from Rock Creek, Texas. 353 



below the surface. Another smaller foramen lies anterior to 

 the pair but only on the right-hand side. Ventrally the bone 

 is deeply excavated and exhibits numerous symmetrically 

 placed foramina. The articular faces are nearly flat, with 

 rounded margins and a very slight central depression. The 

 curves of each face are comparable to those of the anterior 

 caudal, but much less pronounced. As already stated, the 

 chevron facets arise on separate pedicels, those of the anterior 

 face being the more prominent. There is a tendency toward 

 the bridging over of the lateral grooves to form canals as in the 

 previous bone, and where this tendency is most pronounced 

 there is a small foramen leading into the centrum on either 

 side. 



The transverse processes are complete, arising from the upper 

 half of the centrum in contrast to those of the first caudal, 

 wherein they spring from the mid-height. In the vertebra under 

 consideration, these processes are deflected slightly downward 

 and backward, and taper somewhat, to dilate again into a rugose 

 end. The origin of the neural arch covers nearly the entire 

 length of the centrum on either side, indicating a slightly 

 developed intervertebral foramen, the formation of which is 

 shared by the two adjacent vertebrae in the proportion of about 

 two to one, whereas in the first caudal it lies entirely within 

 the limits of the posterior portion of the one vertebra. The 

 neural canal is elliptical behind, but has its roof drawn upward 

 between the postzygapophyses in such a manner as to be 

 almost triangular when viewed from the front. The ill-pre- 

 served spinous process was evidently low, while the lateral 

 limiting w r alls of the prezygapophyses arise to approximately 

 the same level. The zygapophyses are nearly horizontal when 

 viewed from the side, though facing upward and inward and 

 downward and outward, respectively, the chord of their arcs 

 being about 45° from the perpendicular. 



Dimensions. 



Centrum, length 59 mm 



breadth, articular face '72*5 



depth 63 



Neural canal, ant. end, height 38 



breadth 39 



post, end, height _ _ 23 



breadth ._. 38 



Neural arch, length over zygapophyses 86 



width over prezygapophyses 94 



Breadth of transverse processes 230 



Total height of vertebra (estimated) _ _ 140 



