PURBECK FORMATION. 37 



being subcompressed and slightly recurved, as well as sharp-pointed. It would 

 serve well to pierce and retain a living prey. 



The tooth succeeding the laniariform one presents the typical characters ; 

 beyond it the jaw-bone has been broken away in splitting the matrix, and the 

 detached part adheres to the opposite layer (fig. 2). In fig. 1 are shown the 

 impressions of four of the teeth preserved in the slab (fig. 2). Above the first 

 impression (o, fig. 1) is the crown of a successional tooth, about to displace the 

 tooth (o, in fig 2). The outer side of a type upper maxillary tooth is shown, mag- 

 nified at fig. 1, h. 



The remainder of the upper maxillary, with part of the palatine and pterygoid 

 bones of the left side, are represented adhering to the other half of the split slab 

 in fig. 2, and of the natural size, in outline, at a. The extent of the inner alveolar 

 wall, effecting, with the cross partitions, the lodgement of the teeth in sockets, 

 is here demonstrated. The expanded crowns of the teeth come into contact. 

 The inner surface of the crown is shown at h, in which the middle longitudinal 

 rising is rather less prominent than on the opposite surface. The fore part of the 

 crown is represented at c, showing the angle at which the obtuse basal borders of 

 the enamelled crown meet there ; the cement covering the fang is continued upon 

 the crown within that angle. 



The outer side of a portion of the right superior maxillary bone, with eight 

 contiguous molars, is represented in fig. 3, and of the natural size, in outline, 

 at a. There is a linear row of small foramina above the alveolar border. The 

 median longitudinal rising of the crown of the teeth is more strongly marked on 

 this, the outer, surface, as shown in the tooth magnified at h, fig. 3. 



In fig. 4 is represented the inner surface of the posterior part of a right, 

 superior maxillary bone, containing six contiguous teeth, with a less prominent 

 or less defined median rising of the teeth in this fragment ; the last three teeth 

 gradually decrease in size. There is no discernible trace of the socket of another 

 tooth beyond the sixth {x). A portion of the bony palate remains, which gives 

 evidence of a large palatal vacuity, probably internal nostril, at m, and of a pos- 

 terior palatal vacuity at v, probably corresponding with those in the Iguana. 



The inner surface of a portion of a ramus of the mandible, with eight con- 

 tiguous teeth, is represented at fig. 5, and in outline, of the natural size, at a. 



The fore part of a right ramus, consisting chiefly of the dentary element, is 

 represented in figs. 6 — 8, and of the natural size, in outline, at «. Fig. 6 gives the 

 outer side, but the whole vertical extent of the bone is only preserved at the 

 symphysial end. The apex of a young tooth projects from the fifth of the 

 sockets here preserved ; it is represented magnified at a and h. 



There is a linear series of small, nervo-vascular foramina a little below the 

 alveolar border. The crowns of the developed teeth have been broken away; 



