722 S. W. WILLISTON 



On the underside of the atlantal intercentrum, beyond the middle 

 antero-posteriorly, there is an obtuse hypopophysis with the sides 

 concave. The axial intercentrum has an obtuse keel, thicker pos- 

 teriorly; this bone, also, is proportionally a little longer than in 

 T. osborni. Ten or twelve other cervical vertebrae are preserved, but 

 are, for the most part, without processes. They all have a conspicu- 

 ously large vascular foramen on each side of a prominent ridge. A 

 pair of smaller foramina for the centrum veins is seen in the floor of the 

 neural canal. The ribs are single-headed, their sutures well indicated, 



Fig. 7. — T. hentoniamim. Sacrum, from above, one-fourth natural size. 



though they, as also the neural arches, are firmly attached to the 

 centrum. 



Length of atlanto-axis 80 mm 



Diameter of axis posteriody 54 



Lengths of vertebrae, as preserved. . . .37, 37, 48, 50, 50, 50, 50 

 Transverse diameters of same 53, 75, 75, 75, 83, 86 



There are fifteen dorsal vertebrae preserved in the type specimen, 

 none of which is complete, though the preserved parts indicate well 

 their structure. Two united anterior thoracic vertebrae have each a 

 length of 63°^'^ and a width of 85™"^. The transverse processes, 

 arising low down, are stout, and the zygapophyses are large and stout. 

 The underside of the centrum is gently concave, and has the usual 



