Robert Bennett Bean 375 
may be determined by examining Charts III and IV, constructed from 
the numbers in Table III, and also from the position of the fissure of 
Rolando, to be discussed further on, and the areas of the brain outlines 
anterior to this fissure. The numbers in Table III are obtained by meas- 
uring the radii at 60° and 120° of the three outlines of the horizontal, 
vertical and 45° planes intersecting the brain axis, the numbers repre- 
senting the average length of these three radii in each instance. Charts 
III and IV are constructed in a manner similar to that described for 
Charts I and II, and they are treated throughout in the same way. The 
arbitrary line is found to separate the races similarly, but it passes 
through the 64.5 mm. ordinate instead of through the 68 mm., which 
means that the average length of the 45° radii to the frontal lobes for the 
three planes is less than the average length of the radii to the anterior 
association center. The arbitrary line is an approximate compound ordi- 
nate mean in this table as well as in Table IIT», representing the ordinate 
mean for all brains on Charts I and IT, and III and IV respectively. 
A table showing the comparison of the frontal lobes in the two races 
is as follows: 
TABLE IITa. 
EXTREMES OF THE FRONTAL LOBES. 
Left Side. Right Side. 
= (zy —= oe ya ae} * Saas) 
Symbols. Above the Below the “Above the Below the 
arbitrary line. arbitrary line. arbitrary line. arbitrary line. 
WauGaSiam Ss ecisiec, stasiehee a 34 10 32 12 
INGEST ON Sete csla onc attactoe eet 30 52 29 54 
This presents the fact that there is a greater number of large frontal 
lobes among the Caucasian brains (66 large, 22 small), and a greater 
number of small frontal lobes among the Negro brains (106 small, 59 
large) the relations being nearly proportional, and practically the same on 
the two sides of the brain in each race. The difference between the two 
sides found in Tables [1 and II” evidently lies about a point on the 45° 
plane where the 60° radius intersects the outline of this plane. This 
point lies over the anterior association center on the right side, and over 
the gyrus frontalis inferior on the left side. From Table II? it is deter- 
mined that the average for this side is relatively greater on the left side 
in each race. From Table II¢ it is determined that the mean for this 
point is relatively greater on the left side in each race. From Table [I> 
it is determined that the extreme for this point is greater in the Negro 
brain and less in the Caucasian. We may conclude that in general the 
gyrus frontalis inferior is well developed in the two races, causing the 
