DE. H. F. STANDING- ON SUBFOSSIL 



margin of tlie orbital rim to the lower end of the suture of the malar with the maxilla 

 exceeds the diameter of the orbit itself (text-fig. 10). No extant Lemur exhibits this 

 peculiarity, which is only paralleled by some of the Old World Apes (e. g. Papio). In 

 the case of Pcdmoprointhecus a broad plate of bone frequently stretches across between 



Text-fi^. 10. 



Front view of skull and mandible of Pcdceopropkhecus inaxhnus. 



the lower posterior margin of the orbit to join the zygomatic arch, thus walling in part 

 of the temporal fossa. The plane of the orbital rim is more upwardly and forwardly 

 directed than in Indris or Prointhecus. The angle made by this plane with a plane 

 passing through the lower margins of the orbits and the upper margins of the external 

 auditory meatus (the horizontal plane of the Frankfort Convention) may be compared 

 with that occurring in the three extant genera thus : — 



Palaopropithecus 52° 



Indris 73° 



Propithecus ■. . . 77° 



Avahis 47° 



The intersection of the plane of the orbital rim with the median sagittal plane gives 

 an angle which is a measure of the extent to which the orbits are directed forwards. 

 For the same series of skulls these angles are approximately as follows : — 



Palcsopropithecus 55° 



Indris 50° 



Propithecus 53° 



Avahis 50° 



In form and arrangement the various elements constituting the inner wall of the 



