12 



E. C. CASE 



arch is co-ossified with the centrum and in the dorsals it is free. 

 The ribs of the cervicals and anterior dorsals are united by the 

 tuberculum to the transverse process and by the capitulum to a 

 process of the preceding intercentrum, but in the lumbars, 

 caudals, and posterior dorsals there is no process on the inter- 

 centrum for the capitulum of the rib which is attached to edge 

 of the centrum. The intercentra change remarkably through 

 the series ; in the anterior portion of the column they have 



natural size. 



considerable vertical height and prominent lateral processes for 

 the capitula of the ribs ; in the posterior part of the series they 

 become shallower and wider in an antero-posterior direction and 

 lose all trace of the process for the ribs in the lumbars and even 

 in the posterior dorsals (?) . In the cervicals, the dorsals, and 

 the anterior caudals there is a prominent facet on the lower por- 

 tion of the anterior face of the centrum for attachment of the 

 intercentrum. This is absent on the lumbars and sacrals. The 

 anterior and posterior zygapophyses change from broad in 

 the cervicals to narrow in the dorsals, and broad in the lum- 

 bars and caudals again ; in the same order the articular faces 

 of the zygapophyses change from horizontal to oblique and 

 back to horizontal, so that the faces of the post-zygapophyses 

 of the dorsals look out as well as downward, and of the pre- 



