of Edinburgh, Session 1873-74. 245 
the relations he believed to exist between these lobes and the 
vault of the skull, e.g. frontal, parietal, occipital, and temporo- 
sphenoidal lobes. In an essay published in 1861,* M. Broca pointed 
out that the frontal bone was not equal in extent to the frontal lobe, 
but that the fissure of Bolando was invariably some distance behind 
the coronal suture. In eleven males examined the minimum dis- 
tance of the upper end of this fissure was 40 mm., the maximum 
63 mm. from the suture. He further stated that a constant rela- 
tion existed between the lambdoidal suture and the fissure which 
separates the parietal from the occipital lobe. He never found the 
suture more than 15 mm. from the fissure, rarely more than 5 mm. 
M. Broca’s method of determining these relations was by drilling 
holes in the skull, inserting wooden pegs into the brain, and then, 
after removing the skull cap, ascertaining the part of the surface 
of the hemisphere into which the pegs had penetrated. Almost 
similar results were obtained by Professor Bischoff by pursuing the 
same mode of examination, f 
This plan of drilling holes through the skull, and inserting pegs 
through them into the brain, is one which may be conveniently 
employed when the object is merely to obtain an idea of the extent 
of the lobes of the cerebrum in relation to the surface of the head, 
as only a few holes require to be bored to effect this object. But 
as the operation of drilling a number of holes through the cranial 
bones demands the expenditure of much time and labour, it is not 
very convenient if it is desired to fix the position of the individual 
convolutions. It occurred to me, therefore, that some other method 
might be resorted to to effect this object. 
As a preliminary measure, I sub-divided the surface of the skull 
into regions : a prae-coronal or frontal, the region of the frontal 
bone; a parietal, sub-divided into antero- and postero-parietal by a 
vertical line drawn upwards from the squamous suture through the 
parietal eminence to the sagittal suture; a post-lambdoidal or 
occipital, between the lambdoidal suture and the superior curved 
line of the occiput ; a squamosal and a sphenoid, corresponding to 
the squamous temporal and to the great wing of the sphenoid. 
The line of the temporal ridge sub-divides the antero- and postero- 
* Sur le Siege de la Faculty du Langage articule. Paris, 1861. 
t Die Grosshirnwindungen des Menschen. Munich, 1868. 
