46 THE HISTORY OF THE PELYCOSAURIA, WITH 



slender and conical, slightly recurved. The succeeding two are nearly as large as the 

 canine above ; the remaining teeth are all small and recurved. The lower edge of the 

 dentary is thin and marked internally with strong suture lines. The symphysis is short. 



The Vertebral Column. 



The vertebral column is represented by cervicals, dorsals and caudals. 



The cervical vertebral. The following cervicals are preserved : The atlas, with the 

 exception of the neural arches, the axis, the third, the sixth, the seventh and the eighth. 

 Two vertebrae, the fourth and fifth, are missing. 



The atlas (PL II, Fig. 20). The centrum is broad above, antero-posteriorly, 

 but below it is much contracted between the first and second intercentra. The anterior 

 face is divided into an upper and lower part by a compression of the sides opposite the 

 opening of the chordal canal. The lower part is saddle-shaped, and the upper somewhat 

 convex. There are no traces of transverse processes. The posterior face is hidden by 

 the second intercentrum and the axis, but another specimen shows a large opening of the 

 chordal canal, in contrast to a very small one on the anterior face. 



The^rs^ intercentrum, forming the lower piece of the atlas ring, is crescent shaped, 

 with a broad lower rugose surface and a transverse concave keel above. The anterior 

 face of the intercentrum is the largest, concave vertically and transversely, and lodges the 

 lower part of the occipital condyle. The posterior face is convex from above downwards 

 and occupies the saddle-shaped lower half of the anterior face of the atlas. The first 

 intercentrum shows at the distal end below a facet on each side for the articulation of the 

 single-headed atlas ribs. 



The second intercentrum is similar to the first ; the anterior and posterior faces are 

 more equal. It is wedged in between the centra of the atlas and axis, and has the facets 

 for the capitula of the axis ribs placed more to the middle of the posterior edge. 



In the axis the centrum is well developed ; on the ventral side a keel begins to 

 appear. The posterior face of the neural spine is greatly expanded vertically at the base 

 and greatly elevated. The posterior edge of the spine is thickened and divided by a 

 groove which forms a deep cavity between the well-developed zygapophyses below. The 

 apex is marked by a shallow triangular depression. The prae zygapophyses are very 

 small, with the articular faces directed downwards. The postzygapophyses are strong 

 and elevated above the centrum. The articular faces look outwards and downwards and 

 meet on the summit of a short keel below. The transverse processes project laterally and 

 ventrally from the anterior part of base of the neural arch. The distal end does not 

 become separated from the body of the neural arch, and is above the neuro-central suture. 



The third cervical is badly injured by decay, but many points can be made out. The 



