120 AMERICAN PERMIAN VERTEBRATES 



spines of one or two of the vertebrae could not be recovered entire, 

 nor could the smaller bones of the atlas be worked out. The 

 spines of these vertebrae are a little less dilated. 



As far forward as the sixth or seventh vertebra back of the 

 skull the transverse processes are much alike, standing out hori- 

 zontally from the sides of and a little below the anterior zygapo- 

 physes, a little thickened at the extremity. Their length increases 

 gradually and slightly to the eleventh or twelfth presacral and 

 are thence nearly uniform to the fifth, where they become less 

 stout, a little shorter, and are directed more downward. This 

 slight distinction may be sufficient to distinguish these five verte- 

 brae as cervical; there are, of course, no other characters. Back 

 of the fifth postcranial the centra are about the same length below 

 as above; the third and fourth have the lower border distinctly 

 shorter than the length at the upper part of the centra. This 

 diminished shortness seems to be entirely normal in the single 

 series. In none of the presacral vertebrae of the three series have 

 any intercentra been found, nor is there much space for them in 

 the intervals between the centra. The presence of intercentra 

 at the base of the tail and between the sacral vertebrae is, however, 

 sufficient evidence of their existence in life throughout the series; 

 but they were probably quite small in the presacral series and may 

 not have been well ossified throughout. 



Axis. The axis has a remarkably stout spine, as shown in 

 Plate XIV, Figs, i, ib. Small zygapophysial articulations were 

 probably present on the sides in front, but the border of the speci- 

 men was slightly injured here in preparation. The spine is nearly 

 as long antero-posteriorly as the centrum, in the shape of an obtuse 

 wedge, the end rounded, its front border a little thinner than the 

 hind one. The transverse processes are apparently complete. 

 They are short, and are situated lower down than in the following 

 vertebrae; the rib, which was not preserved with the specimen, 

 was doubtless small and short. All parts of the atlas were pre- 

 served in the specimen, but because of their small size only the 

 odontoid could be extricated from the matrix, as shown in the 

 figure. It differs very materially from the odontoid of the Clepsy- 

 dropidae or Poliosauridae. It is relatively large, thinned below, 



