22 ODOXTORNITHES. 



Transverse diameter of vertebra, across pre-zygapophyses, 23. O 17 



Transverse diameter of vertebra, across post-zygapophyses, _. 29.0 



Diameters of pre-zygapophyses, — '7. 0-1 1.0 



Diameters of post-zygapophyses, 8.0-1 0.0 



Length of floor of neural canal, 24.0 



Vertical diameter of lateral foramen, 4.0 



Length of pleurapophysis, 14.0 



Length of free portion of pleurapophysis, 10.0 



Extent of hypapophysis below vertebral articulation, 6.0 



Diameter of terminal tubercle of hypapophysis, 7.5 



Measurements. (No. 1207.) 



Length of centrum, 22. m 



Least transverse diameter of centrum, 1.5 



Transverse diameter of anterior articulation of centrum, 10.0 



Vertical diameter of anterior articulation of centrum, 5.2 



Transverse diameters of posterior articulation of centrum, 8.6- 9.5 



Vertical diameters of posterior articulation of centrum, 7.2- 9.0 



Transverse diameter of vertebra, across pre-zygapophyses, 1 S.O 



Transverse diameter of vertebra, across post-zygapophyses, 28.0 



Diameters of pre-zygapophyses, 8.0- 4.0 



Diameters of post-zygapophyses, 7.5- 8.6 



Length of floor of neural canal, 22.0 



Length of roof of neural canal, ... 22.0 



Transverse diameter of anterior opening of neural canal, 7.5 



Vertical diameter of anterior opening of neural canal, 6.0 



The Fourth Vertebra. (Plate III, figure 3.) 



The fourth, vertebra resembles the third, but is larger and longer. 

 The centrum is much excavated in the postero-lateral region, so as even 

 to become somewhat translucent over a small area, about seven millimeters 

 in advance of the posterior articulation. The latter is supported upon a 

 very abrupt expansion of the centrum. In Trout, the centrum thickens 

 quite evenly toward the anterior face. The under surface of the centrum 

 presents, immediately behind the anterior articulation, a rather deep 

 triangular fossa, the apex of the triangle pointing backward. Behind this 

 fossa, the lower surface is nearly fiat, with an acute median ridge, which 

 divides below the posterior articular face, and sends, downward and out- 

 ward, two somewhat triangular ear-like processes. The articular ends of 



