36 ODOXTORXITHES. 



The dimensions of the thirteenth cervical vertebra in one series of 

 Hesperornis regalis are given below : 



Measurements of Thirteenth Vertebra. (No. 1207.) 



Length of centrum, -- - - 25.0 mm 



Least diameter of centrum, at base, 6,0 



Transverse diameters of anterior articulation of centrum, — . .. .'- 14.0-15.5 



Vertical diameters of anterior articulation of centrum, 7.0-1 1.0 



Transverse diameters of posterior articulation of centrum, 10.0-14.0 



Vertical diameters of posterior articulation of centrum, 9.0-13.0 



Transverse diameter of vertebra, across pre-zygapophyses, 49.0 



Transverse diameter of vertebra, across post-zygapophyses, - 31.5 



Greatest diameter of pre-zygapophyses, 14.0 



Least diameter of pre-zygapophyses, 9.0 



Greatest diameter of post-zygapophyses, 12.0 



Least diameter of post-zygapophyses, 10.0 



Length of floor of neural canal, - 25.0 



Length of roof of neural canal, 17.0 



Transverse diameter of neural canal, at anterior opening, 8.8 



Vertical diameter of neural canal, at anterior opening, 7.0 



Transverse diameter of neural canal, at posterior opening, 8.5 



Vertical diameter of neural canal, at posterior opening, _ •_ 9.0 



Length of hypapophysis below centrum, 9.0 



The Fourteenth Veetebea. (Plate IV, figure 5.) 



The fourteenth vertebra measures a little less than the thirteenth along 

 the centrum. The zygapophyses are approximated, and the neural spine 

 is rudimentary, as in that vertebra. The lateral foramen appears to have 

 been large, and enclosed by bone, which is in part broken away in the 

 specimen represented in Plate IV. The most conspicuous feature of this 

 vertebra is the great development of the inferior descending processes, or 

 " catapophyses," as they are sometimes called. These are much flattened, 

 with nearly parallel sides, and rounded ends. They arise near together on 

 the antero-lateral lower part of the centrum, and descend obliquely for- 

 ward, and a little outward. They are somewhat strengthened along their 

 inner faces at the base by a low, broad, rounded ridge, which at its base 

 forms, with its fellow of the opposite side, a pulley-shaped surface. They 

 do not appear to have been cpiite symmetrical in their distal portions on 

 the opposite sides. 



