208 Cc. W. M. POYNTER AND J. J. KEEGAN 
frontalis superior, the sulcus frontalis mesialis is represented by 
a large number of elements and the sulcus frontalis medius is 
represented by a few shallow fissures. 
The above condition is sufficiently striking to call for the 
attempted explanation of the causative factors, which have 
preceded the statement of these characteristics. If the expla- 
nation is correct, the findings would seem to substantiate the 
claims of a poorly developed frontal lobe or association area 
in the Negro brain, and would clear up a few confusing points 
in regard to the interpretation of the sulci in the frontal region. 
If the sulcus frontalis superior is situated relatively or actually 
further from the mesial border in the Negro brain than in the 
Caucasian and this is associated with a flattened anterior associ- 
ation center, this area must necessarily be smaller and not spread 
over a greater area in compensation forthe flattening which 
might be due to the racial characters of the cranium. 
Because the sulcus frontalis mesialis is absent in apes and 
present in man it was concluded by Cunningham (’92) and 
--others that its simplicity indicated inferiority. In all probability 
it merely represents a human accessory sulcus whose complexity 
depends on the width of the gyrus frontalis superior. Since 
the width of this gyrus seems to vary inversely with the de- 
velopment of the anterior association center, the prominence 
of the sulcus frontalis mesialis would seem rather to be indicative 
of a poorly developed brain. In this series it is however too 
irregular to merit such distinction. 
A general characteristic of the Negro brain which has been 
remarked by a number of observers, is the prominent parietal 
lobe in contrast to the ‘ill filled’ frontal region. In this series 
of brains it has been noted that the lobulus parietalis inferior 
presents a mushroom-like growth overlapping by operculi the 
surrounding cortex, especially in the region of the gyrus arcuatus 
posterior and gyrus arcuatus medius of the lobulus parietalis 
superior. 
In the inferior parietal region there appears to be a variation 
from the generally accepted type of fissuration. A prominent 
accessory sulcus is found in the post-Sylvian region which in 
