PROZEUGLODON. 
253 
^rcatly eloiig-ated from above downwards, their u])per ends rnnning ont on projecting 
])lates of bone, the snmmits of which arc nearly on a level with the upper border of the 
iienral arch, with the anterior edge of which they are united hy narrow bars of bone, 
Text-fig. 8;}. 
Anterior cervical vertebroe of Froze agio don atrox: A, atlas from front ; B, axis from front ; 
C, third cervical from front ; D, the three anterior cervicals articulated with one another, from left side. 
at., lateral surface for atlas ; a.z., anterior zygapophvses ; cond., condylar cups of atlas ; ef., epiphysis of 
centrum; %P., liypapophysis ; n.sp., neiu’al spine ; od., odontoid process ; posterior zygapophyses ; 
sjnn., passage for first spinal nerve ; t.p., ti-ansverse process ; v.c., vertehrarterial canal. | na,t. size. 
enclosing a pair of large foramina for the first spinal nerve {sp.n.). The articular surfaces 
are strongly concave from above downwards and slightly so from side to side. They 
