632 THE EOCENE FAUNA. 



ledges of the true molars are rudimental. The heel of the last true molar 

 is large and wide ; a median posterior tubercle represents it on the penulti- 

 mate molar. The posterior part of the last molar rises with the base of the 

 coronoid process. Enamel wrinkled. 



Measurements. 



M. 



Length of inferior molar series 05<; 



Length of true molars 03C 



Length of last molar 014 



Length of Mrst true molar 009 



Depth of ramus at last true molar 023 



Length of diastema behind first premolar 003&- 



The superior surface of the skull of the second individual shows a 

 low sagittal crest, formed by the convergence of two gradually approach- 

 ing temporal ridges, which are continuous with the posterior border of the 

 postorbital processes. The latter are rather long, and have a broadly rounded 

 extremit}^, which is quite different from the acuminate form of those of the 

 H. venticolum. A slight superior angle of the malar bone marks the poste- 

 rior border of the orbit below. The lateral occipital and squamosal crests- 

 are prominent, and send a branch downwards, forming the prominent edge 

 of the posttympanic process, which is thus well distinguished from the 

 surface of the paroccipital. The latter is the longer of the two, and is 

 directed backwards, while the posttympanic points downwards and is sep- 

 arated from the paroccipital to the base. There is no osseous floor to thfr 

 neatus auditorius. The 05 petrosum is flat, and of a suboval outline. The 

 postglenoid process is obtuse, and has a subtriangular section. The basi- 

 occipital is posteriorly flat on each side, with a strong median keel ; ante- 

 riorly the keel disappears, and the borders become more prominent. A 

 short distance within the postglenoid process, the surface is roughened. 



Tlie infraorbital foramen opens above the anterior 2)art of the fourth 

 premolar. A strong ridge from the pterygoid process passes upwards and 

 backwards over the ahsphenoid canal. The foramina lacera anterius and 

 posterius are rather large and are connected. The f. 1. posteriiis is con- 

 tracted and terminates anterior to the / comhjloideum. The postglenoid 

 foramen is large, and there is no supraglenoid. 



The diastema posterior to the first premolar is only as long as the dia- 



