THE BRAIN OF PREHISTORIC MAN 913 



present it seems desirable lo regard this specimen as representiii<i a distinet 

 raee whose adinities and aiitic|uit\ iiia\- be estimated in the most general 



terms only. 



The Sylvian fissure may be loeated without dIfTieuIt\- b\ the deep groove 

 starting at tlu- temporo-lrontal noteh and extendmij; backward beneath the 

 parietal eminence. Tlu' lissurc of Rolando has been introduced in the cast 

 by utilizing the usual formula for this sulcus. The groove of the transverse 

 sinus is well defined as are also the ridges marking the distribution of the 

 middle meningeal arteries of the right and left hemispheres. With the recog- 

 nition of such landmarks it is |)ossible to identify the boundaries of the 

 major lol)i's u|)on the convexit\- of the hemisphere although no actual limits 

 ma\ be dcrmcd between tlu' occipital and jxirietal areas (Figs. 401 to 

 406). 



The Frontal Lobe. The frontal lobe shows a notable absence of 

 con\<)lutional impressions. This is particularlj- true of the prefrontal area 

 where the polar extremities of the middle and superior Irontal convolutions 

 are usually well marked. A pronounced ridge indicates the position of the 

 coronal suture in the immediate \icmity ol which are two i)romincnt Pae- 

 ehionian elevations, one on either side of the sagittal line. The Irontal are 

 is higher than in Neanderthal man and suggests a more modern t \ pi' of 

 fori'head. It does not ]jresent any tendency toward conca\it\ in its entire 

 extent. The frontal and intermediate prcccntral areas, on the other hand, 

 show a distinct llalness indicati\e ol a relatnely incomplete de\elopment 

 in these two regions. Two distinct areas ol compression appear on I'ltherside 

 of \hv coronal ridge. These are the llatteiied regions rek'rred to as indicating 

 a lack of fullness in the frctntal contour. They are symnu-trical in the two 

 hemispheres and for this reason less likely to be in the nature ot arteiacts. 

 The more anterior of these two depressions is included in a wcll-delined 

 e(jronal constriction. There is no surface leature to denote any jjarticular 



