138 MAURICE G. MEHL 



The palate is somewhat crushed and distorted and most of the 

 sutures are indistinguishable. Still a fairly good idea of its con- 

 figuration and the general relations of the bones can be gained. 

 It is quite highly arched along the median line and especially so 

 in the region of the nares. The low, rounded arch along the median 

 line of the premaxilla and maxilla, formed by the ridges parallel to 

 the alveoli, increases gradually in height and width posteriorly, the 

 increase being more rapid as the nares are approached, till at the 

 posterior margin of the nares the arch is about 82 mm. wide at the 

 general level of the palate surface and rises to a height of about 

 42 mm. from that plane. Behind this point the arch attains a still 



P'iG. 6. — Mystriosiichus planirostris, posterior view of skull, two-sevenths natural 

 size. Outlines and sutures after J. H. McGregor. 



greater width before it again rounds in posteriorly. The internal 

 nares are a little back of the external nares, 10 mm. perhaps. The 

 forward ends of these openings are still covered by the matrix. 

 Their exact extent in that direction cannot be told, but they are 

 probably about 48 mm. long. The width between their lateral 

 borders is 34 mm. The median partition is slightly wider on the 

 palate surface than it is between the external nares. A line con- 

 necting the anterior borders of the post-palatine foramina crosses the 

 internal nares a little in front of the posterior border. From this 

 line the foramina extend back and inward a distance of 60 mm. 

 They are about 8 mm. wide, are slightly curved, concave inward, 

 and have rounded anterior and posterior borders. Their anterior 

 extremities are 190 mm. apart and their posterior ends some 

 120 mm. In size they are similar to those of Mesorhinus fraasi 



