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CAPT. D. M. S. WATSON ON SEYMOURIA, 



The odontoid is a single bone. Its upper surface is slightly 

 rounded but presents no trace of any articulation. The posterior 

 surface is not exposed. The anterior surface is slightly convex, 

 rising to a small point. This surface is in general triangular 

 with the noint at the mid-ventral surface. The lateral edges are 

 slightly emarginate at about the middle of their height so as to 

 divide the whole area into three ; of these, the lowest articulates 

 vvitli the anterior intercentrum, and the two dorsal with the 

 neural arches. The lateral surface is nearly flat, but rises some- 

 what towards the ends ; it is triangular, so that there must be a 

 gap for a triangular intercentrum between the odontoid and the 

 axial centrum. 



Text-figure 8. 



Seijmouria hayloriensis Broili. X 2. 



A. Odontoid from in front. 



B. Atlantal intercentrum from in front. 



C. Atlantal intercentrum from below, anterior end upward. 

 J). Third intercentrum and centrum from below. 



E. Fourth centrum and fifth intercentrum. 



Axis. — The second vertebra preserved differs in no important 

 respect from the third and fourth. It has large well-formed and 

 somewhat swollen zygapophyses, which are not very much pro- 

 duced laterally, the lateral part of the neural arch immediately 

 below the articular surface being extended outward into a short 



