t'»t> \i:\\ REPTILES A\l) STEGOCBPHALIANS PROM 



specimen this plate lies directly in contact with the parasphenoid process and rises 

 considerably above it, but not so high as figured by v. Huene. 1 



The upper edge of the pterygoid rises slowly, forward, from the median portion 

 and panes above the upper edge of the parasphenoid process at about its middle point. 

 The anterior portions of the pterygoids are joined at their lower edges, forming a V, which 

 lies between the anterior portions of the palatines. 



The ( pipU rygoid.- There is no evidence of an epipterygoid, either of a separate bone 

 or of an articular space upon the pterygoid. If such a bone were present, as figured by 

 Huene.- it is remarkable that no evidence remains in a specimen otherwise so complete. 



The transverse. — This bone is radically different, both in position and form, from 

 the conception which has been derived from the study of crushed specimens. It 

 stands nearly vertical in the skull, slanting slightly backward as it descends. The upper 

 end is attached to the maxillary and the jugal. The upper portion of the shaft is a 

 rather thin oval in section. Below, the bone becomes broader and thicker, with a 

 prominent, heavy Mipporting ridge on the lower surface. The upper surface of the 

 distal end is smooth and flat, meeting a similar face on the pterygoid. The anterior 

 outer edge of the smooth face of the transverse is terminated by an elevated shoulder 

 which limited the direction of motion between the bones. The palatine was attached 

 to the posterior end of the inner side of the transverse by a close suture, forming a rigid 

 joint: this fixed the transverse in its position and allowed motion in the pterygoid only. 

 1 he transverse forms the greater portion of the descending process of the palatine 

 legion: the pterygoid is visible from the side only as the thin edge of the distal portion 

 of the descending process. 



On the inner side of the jugal, or the jugal and the postorbital, there is a thin, 

 prominent extension of the bone which forms the anterior border of the lateral temporal 

 opening: this gives the bone an L-shaped section and contributes largely to its strength. 

 The lower portion of this extension becomes quite heavy just posterior to the last of the 

 maxillary teeth and is penetrated by a large foramen running antero-posteriorly for a 

 short distance. The transverse is attached just below this heavy extension. Just 

 anterior to its attachment to the distal end of the palatine the transverse is free for a 

 short distance, but the bones are united again, leaving a small palatine fenestra opposite 

 the middle of the shaft of the transverse. 



The palatines are rather heavy posteriorly, where they unite with the transverse, 

 but soon become more thin and plate-like. The median portion of the palatine is thicker, 

 and this portion forms the characteristic ridge on the lower surface of the palate and the 

 outer edges of the choanae. On the inner side of the heavier portion is the shoulder 

 described and figured by v. Huene as supporting the lower edge of the pterygoid. The 

 palatine sends out two very thin extensions: an upper, which overlies the pterygoids 

 for a short distance, not nearly so much as is indicated by v. Huene, and an outer, which 

 unites with the palatine plate of the maxillary. The upper plate forms the posterior 

 and outer borders of the choanae. Near the middle of the plate there is a strong vertical 

 ridge which ends upon a prominence upon the upper edge. Just anterior to this ridge 

 the palatine divides into two vertical plates. The upper edge of the inner plate descends 

 rapidly and soon joins its fellow of the opposite side, leaving a shallow V-shaped channel 

 on the upper surface; the two together form the septum which divides the choanal. 

 '1 he outer plate runs forward and joins the premaxillaries. The lower, or horizontal, 

 plate of the palatine is deeply concave just below the heavier median portion, forming a 

 channel which runs as far forward as the anterior end of the choanae. This channel 



1 lliniK-. I', v . Beitrftge zur Kenntau und BeurtheiluiiK der PuMuchiet, Geol. u. Paleont. Abhandiungen, 



N. !•'. B«L x, fit' I I'll I. 

 • lliicni', !■'. v., lor cii.. Bfh 5 and 6. 



