DISSOROPHUS COPE 527 



angular. Behind, these swelhngs are partly separated by an angular 

 emargination of the hind border. The epiotic region on each side is 

 produced backward considerably beyond the transverse line of the 

 rounded swellings. The broad surface between the orbits is shallowly 

 concave transversely. The thickened upper margin of the orbits is- 

 nearly horizontal to the middle of the orbit in front, where there is a 

 rugosity, the outer border of which is nearly vertical. The face in 

 front of the orbits is convex, with a depression on each side in front 

 of the orbital rugosity. The nares are large, oval in outline, and are 

 directed upward and outward and forward. Below and a little 

 behind the orbits there is a distinct elevation or rugosity. The pos- 

 terior lateral or temporal region is unfortunately wanting on each side, 

 or rather the parts were so mutilated that they could not be joined. 

 The structure here is quite surely as in Cacops, the epiotic prolonga- 

 tion with its attached quadrate inclosing the ear opening at the bottom 

 of a cavity. The upper margin of this opening is preserved in part 

 on the left side, as is also most of the smooth bone forming the 

 anterior part of the auditory cavity, the ridge limiting this surface 

 from the roughened exterior of the side of the skull in front of it 

 running downward and backward from a point about ten millimeters 

 back of the orbital margin, to the jugal border. 



On the palatal side of the skull the basioccipital, basisphenoid, 

 and parasphenoid could not be recovered, nor the vomerine portion 

 in front. On the left side the pterygoid and palatine regions are 

 nearly perfect and undistorted, save for the interior border of the 

 nares. The nareal opening is long and narrow, the anterior margin 

 a little in advance of the posterior border of the external opening. 

 In front the external border is very close to the dental margin; behind, 

 it is removed a few millimeters. Near the posterior margin of the 

 opening there is a single large tooth, as in Cacops, and doubtless 

 there was another on the vomers at the anterior inner border; no 

 other palatine or pterygoid teeth are visible. The infratemporal 

 opening between the pterygoid and jugal margin is shorter and 

 narrower than in Cacops, and the lateral process, doubtless correspond- 

 ing to the transpalatine, is smaller. The basisphenoid process of the 

 pterygoid is stout, transverse, and nearly horizontal. Evidently the 

 structure throughout of the palatal surface was quite alike in the 



