PLIOSAUKUS. i 



teeth, the last at the tenth and eleventh. As already mentioned, the palatine plate of 

 the maxilla overlaps the vomer to a considerable degree in front. Opposite the 

 internal nares it is raised into a high cristiform ridge which is perforated by a foramen 

 and forms the outer wall of the narial opening. Behind this the maxilla unites with the 

 palatine for some distance, but is then separated from it by the narrow suborbital 

 vacuity (s.orb.) as above described ; the transpalatine (t.p.) joins the maxilla to the 

 pterygoid and closes this vacuity posteriorly. At its hinder extremity the maxilla 

 sends a long process beneath the jugal, nearly as far as the anterior end of the 

 zygomatic process of the squamosal. Within the alveolar margin as far back as the 

 anterior end of the suborbital vacuity there is a deep groove, with a series of 

 pits in which the tips of the crowns of the replacing teeth are seen. The facial 

 surface of the maxilla is gently convex from above downwards. The maxillo-pre- 

 maxillary suture has already been referred to ; it seems to terminate opposite the middle 

 point of the external narial aperture (iictr.), where the process of the maxilla which forms 

 the hinder part of its inuer margin joins a corresponding process of the bone which 

 may be the nasal (In.). The maxilla also forms the outer border of the nares, from the 

 posterior angle of which a suture runs back towards the orbit, separating the maxilla 

 from the (I) nasal. Posteriorly it seems to be excluded from the orbit by an element 

 which may be the lachrymal (I.). 



The jugal (j.) is a small bone which at its hinder end joins the zygomatic process of 

 the squamosal by a vertical suture. On the ventral border for the greater part of its 

 length it joins the backward prolongation of the maxilla. Above, it unites posteriorly 

 with the ventral end of the postorbital, and anteriorly it seems to have formed the 

 postero-inferior part of the border and floor of the orbit. It probably also has a short 

 contact with the transpalatine. 



The postorbital (p.orb.) is a roughly triangular bone, the lower edge of which unites 

 with the jugal, the anterior edge forms the lower part of the hinder border of the orbit, 

 while the posterior border forms part of the edge of the temporal fossa. On its inner 

 surface this bone bears a greatly thickened ridge which seems to separate the orbital 

 region from that belonging to the temporal fossa : the relations of its upper end to the 

 neighbouring bones are not known. 



The squamosal (sq.) consists of a comparatively slender zygomatic bar, a stout dorsal 

 branch, and a broad short ventral portion closely adherent to the quadrate. The dorsal 

 ramus probably met its fellow on the middle line, the two forming the upper border of 

 the occipital region of the skull to the exclusion of the parietals which they overlie. 

 The quadrate portion is apparently fused with the quadrate; its ventral border is 

 convex and forms a prominent rounded ridge a little distance above the articular 

 surface of the quadrate: this ridge is most prominent on the inner side, where, between 

 it and the quadrate condyle, there is a deep groove. The comparatively slender 

 zygomatic process unites anteriorly with the jugal in a vertical suture. 



