552 PROFESSOR MARSHALL ON THE BRAIN OR A BTTSHWOMAN ; AND 
In both cerebra the fissures and convolutions are readily comparable with those of 
the idiots’ brains of which an account is given in this paper, and so resemble them as 
to suggest a similarity in their mode of evolution. Like them, too, they present indi- 
vidual peculiarities, and a disproportional development of their component parts. In 
a few points they are more advanced than even the idiot woman’s brain described above. 
An examination of them serves to confirm in every particular the explanations ventured 
upon in the preceding pages. The fissures present nothing remarkable ; but the convo- 
lutions require some notice. 
In the smaller or male brain (A. 123) the orbital convolutions are extremely simple, 
the triradiate sulcus being only a linear mark ; the frontal are very simple also ; both 
ascending parietals are preesnt on the right side, whilst on the left only the posterior 
one exists, but the intrusive convolution is seen largely developed, forming nearly a 
complete anterior ascending convolution ; the parietal lobules are plain, short, and wide ; 
the supramarginal and bent convolutions are simple, and there is no developed supra- 
marginal lobule ; the temporal are short and thick ; the occipital are simple ; the external 
connecting are very short. 
In the larger or female brain (A. 121) the orbital convolutions are not quite so rudi- 
mentary ; the frontal are large and few ; the two ascending parietals are present on both 
sides, but are plain narrow bands ; the parietal lobules are large, the left one being more 
defined than the right ; the supramarginal and bent convolutions are large, and so well 
formed as to remind one of the condition of the parts seen in the Orang’s brain, but 
there is no overhanging supramarginal lobule ; the temporal are very large, and espe- 
cially long; the occipital are broad, shallow, and coalesced; the external connecting 
are short and simple. 
The ridge leading to the island of Reil is prominent and exposed in the female brain, 
but not so much so in the other. Both brains exhibit in special details a decided want 
of symmetry. 
It is interesting to find that the variable conditions of the anterior ascending parietal 
convolution establish the correctness of the explanation given above of the ultimate 
conversion of the intrusive convolution into that gyrus. It must not escape notice that, 
in the smaller or male brain, this intrusive convolution is again present on the left side, 
as in our idiot woman and idiot boy. The two brains, moreover, differ, not only in 
the parietal convolutions, but also in the orbital region, in the shape of the temporal 
lobes, and in other respects to be presently mentioned. There is evidence of a defective 
and therefore disproportional size of the frontal lobe in both brains, in the fact that, 
taking the total length of the cerebrum as 100, the part in front of the fissures of 
Rolando, the part between them and the perpendicular fissures, and the part behind 
the latter, as seen from above, measure in the smaller or male brain 29, 42, and 29, 
and in the larger or female brain 40, 35, and 25. The frontal region, in front of the 
fissure of Rolando, as compared with the parts lying behind that fissure, is therefore in 
the former as 29 to 71, and in the latter as 40 to 60. In both idiots the frontal region 
