THE OSTEOLOGY OF THE DIADECTIDAE 



147 



This vertebra is undistorted, so that the following measure- 

 ments are characteristic: 



Total height from the lower edge of the anterior face to the apex of the spine 0.143™ 

 Width across the anterior zygapophyses - - - - 0.111 



Width across the transverse processes ._._.. 0.122 



Antero-posterior diameter across the zygapophyses 0.066 



Antero-posterior diameter of the centrum, approximate - - - 0.036 



The six presacral vertebras following the one described above do 

 not differ from it in many particulars. The centra become slightly 



Fig. 

 in Fig. 12 



— Outline of vertebrae shown 

 One-half natural size. 



Fig. 14. — Lateral 

 view of vertebra shown 

 in Figs. 12 and 13. 

 One-half natural size. 



shorter in the posterior ones, the first presacral is the shortest, 

 and the dorsal spines become irregularly larger and heavier. The 

 main difference is in the size and position of the transverse pro- 

 cesses. These become progressively shorter, and with less well- 

 defined articular faces for the ribs, as they approach the sacrum. 

 The shortening is accomplished at the upper end only. The lower 

 edge of the process, except in the last two, remains opposite the upper 

 fourth of the centrum, but the upper end gradually drops from a 



