PAPIO CVNOCEPHALUS 295 



Occipito-nasal length of the skiill 173 mm. 



Interparietal width 62 mm. 



Width of the brain case 87 . 3 mm. 



The dimensions of the brain including the cerebellum and brain stem are: 



Longitudinal go mm. 



Transverse (tcmporo-parietal or intertemporal). . . 70 mm. 



Total weight of the brain i ^7 • 7 gni- 



Total water displacement 125 .0 c.c. 



Weight of the forebrain (including end-brain 109.0 gm. 



and interbrain) 



Weight of the midbrain 2.2 gm. 



Weight of the hindbrain 16.5 gm. 



Upon the basis of these ligures, the following encephalic indices have 

 been computed for the several divisions of the animal's brain : 



Forebrain index 83 . o 



Midbrain index 3.0 



Hindbrain index 14.0 



The forebrain index of 83 assigns the baboon to that class of animals 

 possessed of a brain which indicates a fairly well-advanced manual 

 development. 



Surface Appearance of the Brain in Papio Cynocephalus 



LOBES and fissures 



The brain is definitely gyrencephalic in type. The lobation is distinct, 

 the demarcation between the frontal and parietal lobes being clearly drawn 

 by a prominent fissure of Rolando (Fig. 138). This fissure leaves the supe- 

 rior longitudinal fissure almost at right angles, much in the manner of the 



