UPON THE SERIES OF PREHISTORIC CRANIA. 269 



i and j ' in the Oxford University Museum), the skull belonging to 

 which has not been accessible to me, but which may be supposed 

 to have been brachy cephalic, and from the measurements here 

 given to have been sinistrally flattened (see p. 177 supra) in the 

 parieto-occipital region, I find the width of this zone to be 095" on 

 the left and 1.7" on the right side. In Negroes, who are usually 

 spoken of as being ' occipitally dolichocephalic,' but in whom the 

 position of the parietal tubera is more variable than in any other 

 race of men with which I am acquainted, I have found the width of 

 this zone to vary correspondingly. In one Negro brain I found it to 

 be 1" on both sides ; in the cast of another, presented by E. Garner, 

 Esq., F.L.S., to the University Museum, I find the width to be 2-3" 

 on the right side and 1-9" on the left; in another, in which the 

 posterior cerebral arteries on both sides were very largely contri- 

 buted to by the carotids and the convolutions generally broad and 

 coarse, I found the width of this belt of brain to be 0-4" on the 

 right and i-i" on the left side. It is rarer to find great differences 

 in the width of this zone in dolichocephalic than in brachycephalic 

 brains, which indeed the most superficial examination of the skulls 

 would lead us to expect would be the case. 



When, however, we have gained the knowledge that particular 

 sets of convolutions in the brain underlie particular areas of the 

 surface of the skull, and correspond generally in extent and limits 

 with them, we have gained after all but little unless we can go 

 further and show that particular functions, or at least that a greater 

 power for activity in functions generally, can be assigned to the 

 portions of brain thus localised. To attain either of these ends we 

 must enter upon the following lines of enquiry. We must ask, 

 firstly, whether any portions of the brain-surface have such a dif- 

 ferentially advantageous blood-supply as to render it but reasonable 

 to suppose that they have either differentially important functions, 

 or a differentially greater amount of functions generally, to under- 

 take. Secondly, we must discover whether the microscopical 

 structure and connections of the several convolutions can be shown 

 to differ in such a way and to such an extent as to justify us in 

 conjecturing that important differences of function, either quali- 

 tative or quantitative, must be correlated with such differences of 

 structure. Thirdly, we may learn much from observations as to the 

 sequence of certain mental upon certain cerebral changes produced 



