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1906-7.] Functions of the Rolandic Cortex in Monkeys. 
The excitable areas and their boundaries, as determined by ' us, are 
briefly as follows : — 
On the convexity of the hemisphere close to the margin of the 
longitudinal fissure lies a small area superior to sulcus X, and separated 
from it by part of the leg area, from which movements of the tail and 
perineum are obtained, and in association with these, movements of the 
muscles of the trunk. 
The area for the leg is situated partly on the mesial aspect and partly 
on the convexity of the hemisphere. On the mesial aspect it occupies part 
of the marginal convolution, extending posteriorly from a continuation 
over the margin of the Rolandic fissure to a point in front corresponding to 
the anterior extremity of sulcus X. Below, it extends almost to the 
calloso-marginal fissure. From this part of the marginal gyrus movements 
of the lower extremity are obtained, chiefly of the foot and digits. On the 
convex surface the centre for the leg covers an area extending from the 
margin to a line drawn antero-posteriorly from the posterior extremity of 
sulcus X to the upper border of the superior genu of the Rolandic fissure. 
This area, which is wider above than below, extends in front to the 
anterior extremity of sulcus X. 
Below the leg centre, and interposed between it and the arm centre, is a 
small area lying at the level of the superior genu of the Rolandic fissure 
and extending forwards almost to the posterior extremity of sulcus X, from 
which can be elicited movements of the body muscles. 
Movements of the arm are obtained by stimulating over an area stretch- 
ing from the lower boundary of the body centre to the level of an oblique 
line drawn from a little below the sagittal part of the precentral fissure to 
the Rolandic fissure at the level of the inferior genu. 
The face centre extends from this line downwards almost to the 
Sylvian fissure. The posterior boundary of the face area is in its upper part 
the fissure of Rolando. In its lower part the excitable area does not quite 
reach this fissure posteriorly, but leaves it as the latter inclines backwards, 
and finds its limit behind in a line drawn directly downwards. 
From the upper portion of the face area a small part can be cut off 
stretching from its upper boundary downwards for a distance of about 
1 mm. in the average brain. Movements of the neck result from stimula- 
tion of this part of the cortex in its anterior half and movements of the 
eyelids in its posterior half. In the remaining part of the face area from 
above downwards we obtain movements of the upper lip, larynx, opening 
of mouth, closure of mouth, tongue movements, and those of mastication. 
The anterior boundary of the excitable area is that which we found 
