528 S. W. WILLIS TON 



Openings. — The external nares are large and ovate, looking' 

 outward and upward and forward. They are bounded above by 

 the premaxillary anteriorly, the nasal posteriorly, below by the 

 maxilla (and premaxillary anteriorly?), behind by the nasal 

 above and the maxilla below. 



The orbits are longer than wide, looking outward and but 

 slightly upward and forward. The superior emargination above 

 (doubtless roofed over in life by the integument) if not taken 

 into account would leave the orbit oval in shape, with the ante- 

 rior end rather broader than the posterior. It was bounded 

 above by the frontal, prefrontal, and lachrymal, by the lachrymal 

 and malar in front, the malar below and behind, and the post- 

 frontal in part behind. It had a ring of thin, large sclerotic 

 plates, which were preserved in displaced positions. The sep- 

 arate plates were not united by imbrication, as in the mosasaurs. 



The supratemporal vacuity is broadly oval in shape, deep 

 anteriorly and shallow posteriorly, bounded on the inner side by 

 the parietal, on the outer side by the postfrontal and squamosal, 

 and behind by the margin of the squamosal and parietal process. 

 It opens anteriorly into the spheno-quadrate vacuity, and has 

 a narrow slit between the squamosal and opisthotic. The infra- 

 temporal vacuity is long and narrow, broader posteriorly. It 

 is bounded on the inner side and behind by the quadrate, exter- 

 nally and above by the jugal and the quadrato-jugal. The large 

 oval vacuity between the quadrate and the basi-sphenoid is 

 broadest at the middle, bounded in front by the quadrate process 

 of the pterygoid, behind by the paroccepital process. The pter- 

 ygo-jugal vacuity is irregular and elongated, bounded behind by 

 the articular end of the quadrate, on the outer side by the jugal 

 and maxilla, on the inner side by the pterygoid posteriorly and 

 the ectopterygoid anteriorly. The posterior palatine vacuity is 

 a small oval vacuity placed obliquely between the ectopterygoid 

 behind, and the palatine in front, barely touching, if at all, at 

 the extremities the pterygoid and the maxilla. The interpter- 

 ygoid vacuity is arrow-shaped, placed between the basi-sphenoid 

 posteriorly and the pterygoids on the sides. The narial vacuity 



