1869.] 



HTJXLET HTPERODAPEDON. 



145 



is, it measures 1*5 in. in length ; and the palatine surface has a width 

 of 0-25 in. in front and 0-55 in. behind. The section of the bone is 

 trihedral, the outer face of the trihedron being somewhat concave, 

 the inner convex from above downwards ; the anterior half of the 

 upper edge is thin and broken ; the posterior half is a comparatively 

 broad, longitudinally grooved, narrow surface. Along the bottom of 

 the groove lie three apertures, which are probably vascular foramina ; 

 and other such foramina lie on the inside and on the outside of the 

 ridge into which the anterior half rises. One of the foramina on 

 the inside is the commencement of a canal which traverses the base 

 of the ridge longitudinally. 



Pig. 1. — Left palato-maxillary o/ Hyperodapedon. 



B 



E 



wv 



C 



A. From the inside. 



D. From below. 



D 



B. From the outside. C. From above. 



E. From behind. 



The posterior half of the oral surface of the bone presents two faces, 

 which are inclined towards one another at an obtuse angle ; the wide 

 valley which they include ends abruptly in a sharply cut narrow 

 groove. On the outside of this groove lies a single row of fifteen 

 teeth, anchylosed with the edge of the outer wall of the valley. The 

 anterior eleven of these are worn down to a level with the bony 

 substance of the jaw ; the twelfth and thirteenth have their points 

 ground away, while the fourteenth and fifteenth are entire and 

 sharply pointed. 



The inner wall of the valley presents two parallel series of teeth 

 — one on the middle, and one on the extreme inner edge. Traces of 

 fourteen or fifteen teeth can be discovered in each series. Those of 

 the middle series are, all but the very hindmost, worn down to the 



