168 ODONTORNITHES. 



the entire absence of transverse processes. The anterior articular face is 

 nearly circular, but flattened in outline above, and is concave. Behind the 

 articular face, the centrum, tapers rapidly ; and its entire upper surface is 

 occupied by the neural canal. The walls of the canal rise from each side 

 of the centrum, enclose a triangular neural canal, and are surmounted 

 with a very short or rudimentary neural spine. Only a small part of the 

 centrum of the second vertebra of the pygostyle is preserved. This is 

 closely united with the first centrum, without trace of suture, as are also 

 the neural arch and spine to the corresponding parts of the first vertebra. 



The following measurements g'ive the dimensions of the consecutive 

 caudal vertebrae above described : 



Measurements of Anterior Median Caudal. (Ichthyornis victor, No. 1732.) 



Length of centrum, 3. l mm 



Transverse diameter of anterior articulation, 3. 



Vertical diameter of anterior articulation, 2.2 



Transverse diameter of posterior articulation, 3. 



Vertical diameter of posterior articulation, 2.5 



Diameter of vertebra, across transverse processes, 8. 



Diameter of vertebra, across pre-zygapophyses, 3.6 



Diameter of vertebra, across post-zygapopbyses, 2.8 



Vertical diameter of neural canal, 2. 



Measurements of Median Caudal. {Ichthyornis victor, No. 1732.) 



Lengtb of centrum, 3.2 mm 



Transverse diameter of anterior articulation, 3. 



Vertical diameter of anterior articulation, 2.4 



Transverse diameter of posterior articulation, 3.2 



Vertical diameter of posterior articulation, 2.5 



Diameter of vertebra, across transverse processes, 9.5 



Diameter of vertebra, across pre-zygapophyses, 3. 



Vertical diameter of neural canal, 1.6 



Measurements of Median Caudal. {Ichthyornis victor, "So. 1732.) 



Lengtb of centrum, 3.6 mm 



Transverse diameter of anterior articulation, 3. 



Transverse diameter of posterior articulation, 3. 



Diameter of vertebra, across transverse processes, 11.5 



