Cope.l 554 LJan . is, 



cess is directly below its anterior border. Thus the tympanic bone is 

 directed obliquely downwards and forwards. Posteriorly it is separated 

 by a groove from the mastoid process. Anteriorly it is separated by a fossa 

 from an osseous mass which occupies the space between it and the post- 

 glenoid process. Before the skull was reconstructed from its fragments, this 

 mass was observed to be entirely distinct from the postglenoid process, 

 which it equals in height. Continuous with it, there descends another 

 osseous body to near the line of the extremity of the mastoid process, with 

 a truncate inferior edge, which is separated from the otic bulla by an open 

 groove. The stylohyal ligament is probably inserted into a fossa at the 

 anterior extremity of this groove. The postglenoid process is low and 

 more extended transversely. The anteroposterior diameter is small. The 

 glenoid surface is much extended transversely and terminates externally in 

 a slight thickening. The zygomatic process of the squamosal bone is at 

 first expanded horizontally and has a low convexity of the thin superior 

 edge. Its- vertically compressed portion is entirely supported by the ma- 

 lar, and does not extend so far forwards as the anterior edge of the 

 zygomatic foramen . The malar bone is remarkable for the depth of its 

 suborbital portion, which fully equals the diameter of the orbit. Its infe- 

 rior edge presents a thickened angle downwards below the anterior part of 

 the last superior molar. Its superoanterior angle terminates in a promi- 

 nent rib of the side of the face, which extends along the inferior edge of 

 the facial vacuity. Beneath the anterior part of the latter the face is con- 

 cave. Above this concavity the ascending plate of the maxillary is con- 

 vex in the vertical section, turning inwards at the apex to unite with 

 the lateral part of the extremity of the nasal bone. The preorbital fossa 

 is small and looks forwards and upwards. 



The otic bulla? are larger than in any other Oreodontid. They are of a 

 short oval form, somewhat truncate anteriorly and posteriorly. Thus they 

 differ from those of G. simus, where they are elongate -oval. They only 

 reach as far anteriorly as the middle of the internal extremity of the 

 glenoid surface ; while in G. simus they reach the line of the posterior 

 outline of the zygomatic foramen. The}' terminate near the inferior inter- 

 nal point, in a liUle acute osseous apex, which is smaller than in G. simus. 

 The bulloe approach so closely together that the bassioccipital is much nar- 

 rowed, and the sides of its inferior surface are excavated so as to reduce 

 the middle line to a narrow acute keel. The lateral excavations follow the 

 posterior internal base of the bullae, leaving a median table, which is itself 

 excavated by a shallow fossa, which extends from the median keel to the 

 foramen magnum. The median keel disappears anteriorly. The sphenoid 

 is protuberant downwards as a narrow convex rib, which rises and disap- 

 pears in the presphenoid. The descending sphenoid ala forms the posterior 

 boundary of the posterior nareal trough, and makes a strong angle with 

 the pyramidal process of the palatine, which is turned outwards. The 

 pterygoid squama lerminates in an apex which points downwards and 

 posteriorly towards the apex of the otic bulla. The palatonareal border is 



