MTJE^NOSAUETJS. 89 



between the premaxillfe, and a mucli broader posterior portion, the small internal 

 nares being situated in the angle caused by the sudden widening. The outer and 

 anterior border of the nares is formed by the maxillae, which behind them unite with the 

 vomers. Posteriorly the broad vomerine plates join the palatines and, towards the 

 middle line, the pterygoids, the slender anterior ends of these bones being thrust 

 between them for a short distance. 



The palatines {pal., text-fig. 47) are thin, roughly oblong bones ; posteriorly they 

 unite with the anterior edge of the lateral wing of the pterygoids (see below) and 

 with the transpalatine, internally with the outer edge of the anterior limb of the 

 pterygoids, while externally they join the maxillae in an overlapping suture. 



The pterygoids (pt., text-fig. 47) are triradiate bones, of which the anterior and 

 posterior rami are very long, the median one much shorter. The posterior ramus is 

 stout and somewhat compressed laterally ; towards its posterior end it becomes thicker, 

 and on its inner face bears a large facet for union with the ventro-latei'al process 

 of the basioccipital described above. Behind this it curves outwards, and its hinder 

 end unites with the inner edge of the quadrate, but no specimen showing the exact 

 form of this part of the bone has been found. A little in front of the basioccipital 

 facet there is another projection which seems to have effected a junction with the 

 basisphenoid. The anterior (palatal) branch of the pterygoid is flattened and 

 expanded. It is widest just in front of the point of union with the lateral ramus, and 

 thence narrows gradually forwards terminating in a pointed process which unites with 

 its fellow of the opposite side, the two running forwards between the hinder ends of 

 the vomers. Behind this anterior union of the pterygoids there is in this genus a 

 long median slit-like palatine vacuity extending back to the anterior end of the para- 

 sphenoid (2>as.), which, judging from a well-preserved example in a closely allied genus, 

 was short and abruptly truncated in front ; the pterygoids seem to have overlapped 

 the edge of the parasphenoid for a short distance. The outer edge of the anterior 

 process of the pterygoid unites closely with the palatine. The lateral ramus is short ; 

 its posterior border is concave, passing by a gentle curve into the outer border of the 

 posterior ramus. Towards its outer end it is much thickened to form a downwardly 

 projecting knob, which unites with a corresponding process on the transverse bone. 

 Anteriorly this ramus unites with the palatine. No good specimen of the transverse 

 bone is preserved. 



The structure of the mandible (PL III. figs. 3, 3 a ; PI. VI. fig. 2 ; text-figs. 46 & 48) 

 is somewhat diflScult to make out with certainty. This arises from the fact that some 

 of the bones of the ordinary reptilian mandible are either wanting or, at least in all 

 the specimens seen, fused with other elements. The largest bones of the mandible are, 

 as usual, the dentaries {dent.) ; these form the whole, or nearly the whole, of the 

 symphysis and the greater part of the rami to a little beyond the alveolar region. They 

 are widest at the symphysis, where they form a slight expansion, bearing large teeth 



