600 E. B. BRANSON 



or articulate with the exoccipitals in Broili's specimens. It has a 

 broader median expansion than in this form, is narrower behind, and 

 contracts more abruptly in front of this expansion, and has a much 

 longer, slenderer cultriform process. 



The prevomers are broad and thin. They articulate anteriorly 

 with the premaxillae in a straight line that runs at right angles to 

 the main axis of the skull. On the outside they articulate with the 

 pterygoids and palatines. They articulate with each other in the 

 median line of the skull for the anterior half of their length, then 

 pass backward on either side of the parasphenoid, and end just in 

 front of the median expansion of that bone. They form the anterior 

 inner boundary of the palatine foramina. 



The palatines are long and slender, and extend from the middle 

 of the outer margin of the skull to the anterior end of the internal 

 nares. They are broadest immediately behind the nares, narrowest 

 just inside their posterior end, and they form their entire inner and 

 posterior borders. They bear three large teeth, one at the back end, 

 one just behind the nares, and one immediately inside the anterior 

 end of the nares. 



The pterygoids have very long anterior and posterior wings, 

 and a short, thick inner wing. The anterior wing is broad at the 

 outer end between the maxillary and the palatine foramen, but 

 becomes narrower anteriorly between this foramen and the palatine 

 bones. It is narrower between the infratemporal and palatine 

 foramina, and the part that forms the inner boundary of the former 

 is turned upward at right angles to the main part of the bone. Just 

 inside this upturned portion there is a deep depression that extends 

 forward, becoming broader and shallower, until it finally disappears. 

 The posterior wing is twisted on the main part of the bone until 

 only the edge is seen from below. It articulates with the quadrate 

 at the outer end and above, and projects outward nearly to the cotylus. 

 The inner wings are present in six specimens preserved in Walker 

 Museum, and in every specimen they are broadly separated by the 

 parasphenoid, instead of meeting in the median line as in Broili's 

 specimens. 



The premaxillaries are greatly expanded, forming the anterior 

 fifth of the floor of the skull. 



