321 
1888 .] Dr A. Bruce on Absence of Corpus Callosum. 
the psalterium of the fornix. Covering the third ventricle and the 
sides of the optic thalami was a thin membrane (evidently the velum 
interpositum), extending from the lamina terminalis in front back- 
wards over the thalami, and having in the middle line two long 
antero-posterior veins. This structure had extended into the lateral 
ventricles, and was fringed by the choroid plexus in the usual way. 
It was loosely connected with the falx, but the adhesions were torn 
in removing the latter. The two hemispheres were separated by a 
mesial incision and placed in Muller’s fluid ; the left reserved for 
transverse vertical, the right for transverse longitudinal sections. 
Nothing abnormal was noted about the size or conformation of the 
cranium, but unfortunately no careful examination of this was made. 
The brain was not weighed, but its size seemed fairly normal. It 
was richly convoluted, but there was a remarkable anomaly in the 
formation of the various lobes (see figs. 1 and 2. Drawings natural 
size of inner and outer surface right hemisphere). 
The outer surface of the cerebrum presented the following abnor- 
malities : — (a) The frontal lobe is reduced in size, while the occipital 
and, to a less degree, the temporal are increased. The length of the 
convex margin of the great longitudinal fissure between the extreme 
point of the occipital and frontal lobes is 1 1 1 inches ; the distance 
between the tip of the frontal lobe and the superior extremity of the 
fissure of Eolando (/.r.) is 3f inches ; that between the fissure of 
Rolando and the parieto-occipital {p.o) fissure is 4 inches j and that 
between the parieto-occipital fissure and the tip of the occipital lobe 
is inches. (6) Both limbs of the fissure of Sylvius {f.s.) are 
normal; but the fissure of Rolando (fr.), instead of having the 
normal direction downwards and forwards, passes downwards and 
slightly backwards. It also reaches the median surface of the hemi- 
sphere, where it extends as a deep fissure as far as the free margin 
of the grey matter of the gyrus fornicatus. 
In the frontal lobe the sulci are all present, but the convolutions, 
especially the lower, are abnormally small. The prsecentral sulcus 
(pr.c) and ascending frontal convolution (a.f.) are normal. 
The postcentral sulcus (po.c) extends from inch above the hori- 
zontal limb of the fissure of Sylvius to within 1 inch of the middle 
line. It is not directly continuous with the intra-parietal sulcus 
(i.p.), which is unusually deep, and extends backwards to within 
