198 C. W. M. POYNTER AND J. J. KEEGAN 
there is any profit in analyzing the connections formed by these 
sulci. Table 1 presents the easiest way of comparing the con- 
ditions found in this series with the results of other observations. 
TABLE 1 
Type l Type II Type III Type lV Type V Type V1 
| 
a a2 ae | 
| 
Type per cents . 
ObsenveniiOneer rcs eres «cis ocvsns Screen I Ih uu IV Vv VI 
Cummins er ave. cous scent nee 69 19 11 3 6.3 
Cunningham: (Negro):............... PEM ee 37 25 25 12 
DireckworthwecNustraliam)) o.. sc. 4 fee eee 30 50 
Wuckworth. (embryo)... sc. +2 oe eee D0) Words alo 510 one 
TRGB 5 6 Li Sa nN PO REREPRIE Send 6 55 itt l¢/ 4 9 4 
SLSTEIOWON AT 5 Heb dicen eek Ree ene NE RE a on 44 31 
BIBINSURENNCS tees... on sod sisaeeea s aoe Oe 66.6 21 25 4.2 
Complete union of all three elements without bridging gyri at any point in 
the complex was present in this series in only 8.5 per cent. 
The inferences, if any, to be drawn from table 1 are in the 
main, opposed to the conclusions of Cunningham in regard to the 
Negro brain, but in any case the difference between the Negro 
and the Caucasian is not enough to establish race characters. 
The communication between the sulcus retrocentralis inferior 
and the fissura Sylvii is present in 21 per cent of hemispheres, it 
is generally effected through the sulcus subcentralis posterior. 
The sulcus interparietalis is frequently deeper than the sulcus 
centralis, the average depth of the former is 21 mm. and of the 
latter is 20 mm. The bridging of the interparietal sulcus by a 
superficial gyrus occurs in 87.6 per cent, the condition amounts 
to an actual separation into two elements in 16.6 per cent. The 
ramus parietalis is quite variable in form but presents almost 
constantly a descending branch which incises the lobulus parie- 
talis inferior and forms a boundary of the gyrus angularis and 
also frequently indicates its independence from the so called_ 
gyrus post-Sylvius. There is frequently a communication 
