CONDYLAETHEA. 499 



cated by postorbital angles only; there are no zygomatic angles bounding 

 them below. The former rise into strong temporal ridges, which rapidly con- 

 verge and unite to form a low, straight, and narrow sagittal crest. The pari- 

 etal bones over the hemispheres are convex in all directions, and posterior 

 to them are a little concave, where the surface rises posteriorly into the supra- 

 occipital crest. This projects upwards, and, being concave in the middle, 

 has a bilobed outline, though not so strongly as the Periptychus rhabdodon. 

 The occiput is concave on eacli side above the position of the condyles. 

 The lateral crest continues into the posttympanico-paroccipital crest, which is 

 incurved on the inferior base of the skull as far as the occipital condyle. 

 The basioccipital has a faint median keel. Thebasisphenoid is flat. Between 

 the postglenoid and the foramen ovale there is a small concave face, which 

 extends from the anterior base of the zygoma to the external meatua on the 

 inferior surface. On its interior edge is the base of the styloid process. In 

 front of the latter its border is cut by the large foramen ovale, which is not 

 cut off from the foramen lacerum. The palate is doubly excavated posteriorly 

 to opposite the middle of the anterior external lobe of the third superior 

 molar. 



The infraorbital foramen is large, and issues above the middle of the 

 fourth superior premolar. There are three postparietal foramina, serially 

 arranged, the anterior on the squamosal suture. There are three supra- 

 sqamosals, also lineai-ly placed, the last near the parietal suture. Thex-e are 

 two inferior squamosals near the base of the zygomatic process, one above 

 the other. The nasal bones widen posteriorly, but not so much as in the 

 species of Phenacodus. Their posterior outlines are acuminate. The malar 

 bone extends to the lachrymal. The lachrymal foramen is not external to 

 the orbit. Palate rather concave. Frontal region slightly concave in 

 transverse section. 



The mandible is contracted forwards. The symphysis is narrowed, 

 flat, and at the incisor teeth nearly horizontal. The rami are compressed 

 and rather robust. The coronoid processes are elevated, and have nearly 

 vertical anterior edges. The angles are produced posterior to the line of 

 the condyles and are broadly rounded. The basal part is compressed and 

 thin, but the posterior edge is thickened and projects inwards opposite the 

 line of the molars. The condyles are close to the posterior base of the cor- 



