138 ODONTORXITIIES. 



3feasure>nents of the Seventeenth "Vertebra. (Xo. 1733.) 



Length of centrum, C. 1 ?" 1 " 1 



Least transverse diameter of centrum, 1.8 



Transverse diameter of anterior articulation of centrum, 2.5 



Vertical diameter of anterior articulation of centrum, 3.0 



Transverse diameter of posterior articulation of centrum, 2.5 



Vertical diameter of posterior articulation, 3.2 



Transverse diameter of vertebra, across pre-zygapophyses, 4.0 



Transverse diameter of vertebra, across post-zygapophyses, 3.2 



The Eighteenth Vertebra. 

 Another vertebra (number 1733) not figured, evidently posterior to 

 the one above described, has the under surface of the centrum somewhat 

 hour-glass shaped, and nearly alike at each end, being destitute of tubercles 

 or hypapophysis, and very evenly rounded throughout below. The artic- 

 ular faces are sub-circular, and about equally concave. Laterally, this 

 centrum, like the one before it, is deeply excavated nearly to the middle 

 on each side, leaving a thin wall of bone along the median line to support 

 the floor of the neural canal. The articular face for the head of the rib 

 is above the anterior part of this excavation, and is obliquely oval. The 

 diapophyses, zygapophyses, and most of the neural spine, are broken 

 away in this specimen. 



In one of the best preserved skeletons of IcMJiyomis victor (number 

 1732), several vertebrse, apparently consecutive, lie near together in front 

 of the sacrum. The first of these, or the eighteenth vertebra, has been 

 thrown somewhat out of the line of the next two, and possibly may not 

 have been consecutive with them. The centrum is badly crushed, but was 

 evidently excavated at the sides above, as in the Tern, and had concave 

 articular faces. The neural spine was about two-thirds as long antero- 

 posteriorly as the centrum, and was proportionally higher than in the 

 Tern. It does not appear to have been united to the adjoining spines by 

 ossified tendons, as in that bird. The posterior zygapophyses are approxi- 

 mate laterally, as in the succeeding vertebrse, and look outward as well 

 as downward. The diapophyses were broad, and directed somewhat 

 backward. 



