ON THE BRAINS OF TWO IDIOTS OF EUROPEAN DESCENT. 
537 
lution (a), the bent convolution (e), and the second connecting convolution (/ 3 ). This 
better definition of the lobule of the left side, it is worthy of remark, is not uncommon 
in perfect European brains. In the Bushwoman’s brain, too (Plate XVII. fig. 1), 
described in the first part of this paper, the lobule in question is better defined on the 
left than on the right hemisphere. In the brains of the higher Apes (Plate XXIII. 
fig. 20) the parts are more nearly symmetrical ; so that in this region again the idiots’ 
brains manifest the human want of symmetry. 
In both the idiots’ brains the Sylvian fissure is so short that the supramarginal convo- 
lution (ni-mi), its so-called lobule (a), and the bent convolution (e) are all three necessarily 
very small, and, indeed, are represented only by a simple convolutional band, turning 
round the front and upper end of the nearly vertical or slightly oblique Sylvian fissure. 
Nothing can show more clearly the fundamental unity of these parts, especially of the 
supramarginal convolution and its so-called lobule ; whilst the bent convolution is a 
sort of connecting convolution between the supramarginal and one of the temporal con- 
volutions. Thus understood, the very short supramarginal convolution ultimately joins, 
in both idiots, the lower frontal row anteriorly. In the idiot woman it sends downwards 
and inwards a short process to the transverse smooth eminence, lying partly exposed at 
the entrance of the Sylvian fissure, which expands into the rudimentary central lobe , or 
island of Beil (C). In the idiot boy this process is a mere ridge, and the eminence 
itself is not distinctly recognizable. The so-called convolutions of the island of Reil, or 
central lobe, are absent, even in the idiot woman, whilst in the idiot boy a plain indi- 
stinctly elevated surface occupies its usual situation. 
The supramarginal lobule (a), if defined to be a largely developed part of the convo- 
lution so named, overhanging the Sylvian fissure and helping to depress its hinder end, is 
certainly absent in both the idiots’ brains ; but it is doubtless really represented by the 
part of the supramarginal convolution just in front of the hindmost bifurcation of the 
upper end of the Sylvian fissure. The structure of this part of the idiots’ brains is exceed- 
ingly simple, as simple indeed as in the Cercopithecus, far simpler than in the higher 
Apes (Plate XXIII. fig. 20). It is smaller and more simple in the idiot woman than in the 
idiot hoy, is larger in both on the right than on the left side, and is largest on the right 
side in the idiot boy. In the idiot woman the supramarginal lobule is connected, on the 
right side, with the lobule of the posterior ascending parietal convolution, and also with 
the second external connecting convolution ; on the left side only with the latter. In 
the idiot boy it is, on both sides, connected only with the latter, but by a larger and 
more tortuous band. 
The bent convolution (Plates XXI. & XXII. figs. 10, 12, 14 & 16, 6), turning, as usual, 
behind the summit of the Sylvian fissure, is connected posteriorly, in both the idiots’ brains, 
with the second connecting convolution, and joins below the upper external temporal or 
inframarginal convolution (Plates XXI. & XXII. figs. 12 & 14, 7), instead of being sepa- 
rated from that by a secondary sulcus and running between it and the middle external 
temporal ( « ) ; this peculiarity is found only in the simplest quadrumanous brains, and 
