224 THE CRANIA OF THE SIMIIDAE (PRIMATES) [SECT. A 



From external features we pass to those revealed when the 

 skull is sectionized in the median sagittal plane, and the exami- 

 nation of such sections is to be particularly recommended as 

 leading to important conclusions on the essential differences 

 between the skulls of Simiidae and Hominidae. The conditions 

 presented by skulls of adult specimens will be considered first. 



Fig. 149. Skull of an adult male Orang-utan (*- nat. size). (From a specimen 

 in the Cambridge Anatomical Museum.) The interior of the skull and other points 

 in the median plane are shewn in projection by interrupted lines. The references 

 to numbers are as follows : — ■ 



1. Sella turcica. 



2. Tympanic bone. 



3. Level of hard palate. 



4. Deep surface of mandible. 



If we examine the skull of an adult male Gorilla thus prepared 

 (Fig. 148) the relative development of the facial components is as 

 distinct as when the exterior of the skull is observed. The skull 

 of an Orang-utan presents analogous features, as may be seen in 

 Fig. 149. Comparisons with the human skull may be instituted 

 conveniently by reference to the next illustration (Fig. 150). Here 

 the specimens are arranged from right to left in a sequence which 

 may be termed an "ascending" one. Continuing the inspection 

 of the facial portion of the skull, attention is directed to the points 



