80 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 19, 



is convex forwards, and from above downwards. It consists of an 

 outer and an inner lamella, which pass into one another along the 

 ridge-like anterior convexity of the bone, and enclose a deep cavity 

 posteriorly. The distal end of the bone was provided with a trans- 

 versely elongated convex condyle. The angle of the ramus of the 

 mandible, which is 1*35 in. long, projects not more than 0'15 in. 

 behind its articular surface (fig. A). 



At the articular surface, the jaw is not more than 1-5 in. thick; 

 but in front of this point it rapidly rises, and, at 0*65 in. from the 

 posterior extremity, forms a coronoid process, the summit of which 

 is 0-4 in. distant from the lower edge of the ramus. It then de- 

 clines in height, and, at 0*75 in. from the angular end, begins to 

 bear teeth. Of these teeth the three posterior occupy a space of 

 0*25 in., and each has a conical crown 0-1 in. high. Three teeth 

 in the upper jaw, of similar size and form, interlock with them, the 

 hindermost maxillary tooth being posterior to the hindermost man- 

 dibular tooth. The next two teeth, forwards, in the ramus of the 

 mandible are somewhat smaller than those just mentioned ; but the 

 most anterior tooth of all is a curved tusk, twice as long as any of the 

 others, and having its concave side outwards, its convex side in- 

 wards and towards its fellow. These teeth bite behind the two long 

 teeth lodged in the prsemaxillse (fig. B). 



Three teeth in the upper jaw answer to the foregoing; and the 

 anterior of these passes externally to the mandibular tusk when the 

 mouth is closed. Thus there appear to be six teeth below, and 

 seven teeth above, on each side of the upper and lower jaws ; but it 

 is possible that additional posterior teeth may not be visible. 



I have carefully examined into the mode of implantation of those 

 teeth, and I have been unable to satisfy myself that they are lodged 

 in true alveoli. They appear to be anchylosed to the edges of the 

 jaw-bones, as in many modern Lizards with a so-called " acrodont" 

 dentition. 



Each tooth contains a proportionally large pulp-cavity. 



The vertebral column is broken in the middle of the dorsal 

 region, and it is not practicable to ascertain the number of vertebrae 

 with precision ; but it may be safely assumed that the cervicodorsal 

 series contains not fewer than twenty, and not more than twenty-two 

 vertebra?. There are certainly not more than two sacral vertebrae. 

 Eleven caudal vertebrae, belonging to the proximal half of the tail. 

 He in undisturbed relation to one another. There were probably 

 as many more in the broken-up part of the tail. 



The casts of these vertebrae show that they had completely ossified 

 centra, very slightly concave at each end; large neural canals, and 

 stout neural arches, running out into broad oblique processes or 

 zygapophyses. The spines were very low narrow crests. The trans- 

 verse processes must have been represented by mere tubercles. 



Eive long and slender vertebral ribs are visible on the right side 

 of the anterior dorsal region, in connexion with a similar number of 

 anterior dorsal vertebrae. The largest of these, though its distal end 

 is not entire, measures 1-15 in. in length, but is nowhere more than 



