HYKACOTHERIUM. 639 



posterior articular face. The latter is subcordate, and as wide as deep. The 

 centrum of the second or third cervical is deeply excavated below the trans- 

 verse processes, leaving the middle line a prominent keel. This is not pro- 

 duced into a hypapophysis of any prominence posteriorly. The transverse 

 process is extended anteriorly to beyond the line of tlie articular surface. 

 It has no transverse laminar expansion. The anterior face is very oblique, 

 is moderately convex, and is deeper than wide. The neural canal is deeper 

 than wide. " The neurapophy ses are concave on account of the prominence 

 of an obtuse ridge which connects the zygapophyses. The neural spine is 

 a keel. 



The articular faces of the first dorsal vertebra are not oblique, and are 

 moderately opisthocoelous. The centrum has a median inferior angular 

 line, on each side of which the surface is a little concave. The prezyga- 

 pophyses are inclined at 45°, and the poslzygapophyses are horizontal. 

 The tubercular facet is horizontal and projects about as far as the prezyga- 

 pophysis which is directly above it. The capitular facets are large. The 

 sides of the centra of the dorsal vertebrae which follow, are concave, and 

 the middle line below is narrowed so as to be a ridge. The ridge becomes 

 successively more obtuse posteriorly, becoming on the posterior dorsals an 

 angle, which becomes quite obtuse on the lumbars. The neural canal grows 

 smaller towards the posterior part of the column, its section being sub- 

 round. On the posterior dorsals, the tubercular rib facet is near the ante- 

 rior margin of the middle of the neural arch. A ridge passes from it to the 

 posterior capitular facet. Behind the point of its disappearance this ridge 

 continues to connect the two capitular facets. The neural spines of the 

 dorsals are compressed, and present a simple edge posteriorly as well as 

 anteriorl^^ On the posterior lumbars, the sides of the centrum below the 

 base of the very wide diapophysis, become again concave. The articular 

 faces of the lumbars are plane, and wider than deep. 



Measurements of vertebrw. 



■' M. 



Leiieth of centmm of axis on inferior middle line \ 



I without odontoid 0-2o 



Length of base of nenral spine of axis 0'24 



Elevation of neural spine posteriorly 016 



Width of axis at atlantal facets 0200 



