82 FOURTH GENERAL MEETING. 



convolutions of the brain must have developed considerably and 

 made strong impressions on the inner surface of the frontal bones. 

 ■Without doubt the frontal scaphocephaly was not peculiar to the 

 species, but only an individual variety, as otherwise the frontal 

 lobes would have had sufficient space for their development, and 

 •would not have made such strong impressions on the inner surface 

 of the bony wall containing them. 



Another important feature of the cerebrum to be remarked when 

 viewed from above, and which is certainly more than an individual 

 one and is independent of the described narrowing of the frontal 

 lobes, is given by the shape of the posterior part of the cerebrum. 

 The largest diameter is at the temporal lobes just before the fossa 

 petrosa. About three-fifths of the length falls before the largest 

 transverse diameter, two-fifths behind that line. In all the apes, 

 with the exception however of some small New-world genera 

 {Chrysothrix, Midas), the largest diameter at the temporo- occipital 

 lobes, observed in casts of the cranial cavity, is situated much more 

 behind, and the anterior part of the length is about double of the 

 posterior part, but in man the same proportion prevails as that 

 observed in Pithecantlwopus. In every case the greatest width of the 

 cranial cavity corresponds to the anterior part of the linea semicir- 

 cularis, and the processus mastoideus, and evidently thus depends 

 upon the point of the greatest muscle-traction by the sternocleido- 

 mastoideus muscles, for those muscles want the broadest place of 

 the calvaria for their insertions. These are situated in the apes, 

 except in Chrysothrix and Midas, behind those in man, by reason 

 of the occipital condyli being situated much more behind in apes 

 than in man. The agreement in this respect, of the brain of 

 Pithecanthroptcs with that of man, can in my opinion only be 

 accounted for by similar insertions of the named muscles and an 

 erect attitude. For in accordance with the other very human 

 features of the brain -case, it is highly improbable that we should 

 have to account for this feature in a way similar to that of account- 

 ing for the forward shifting of the occipital condyli in the small 

 New-world monkeys. 



In the frontal region of the hemispheres the convolutions are 

 most perfectly distinct. Those on the left side are a little different 

 from those on the right side ; the latter are, further, best preserved. 

 For first orientation the central and precentral fissures are easily 

 identified. The intraparietal sulcus is only very partially distinct, 

 but seeming to point to a relatively large occipital lobe, an apelike 

 condition, undoubtedly consequent on a relatively larger develop- 

 ment of the sensory centres of the cortex in contrast with smaller 

 areas of association. In the neighbourhood of the medial part of 

 this sulcus the brain is very flat. 



The most conspicuous feature is the second frontal fissure, as 

 clearly developed as in any human hemisphere, originating in the 

 common T-shaped form from a clearly distinct inferior precentral 



