OF THE GYRUS MARGINALTS AND GYRUS FORNICATUS IN MONKEYS. 343 
tract on the right side, similar in shape and position to that seen after lesions of the 
motor areas, being triangular in shape, with a broad base towards the posterior cornu, 
but becoming narrower as it extends forwards and outwards till it reaches the circum¬ 
ference, about the middle of the lateral surface. Here it spreads out a little, 
joining a tract of degeneration which passes forwards in the direct cerebellar tract; 
close to the circumference, from near the posterior root. There is a band of healthy 
fibres belonging to the cerebellar tract, between the degeneration at the surface of tlie 
direct cerebellar tract and that in the main part of the crossed pyramidal tract. 
Dorsal Region (fig. 36).—The degeneration comes nearer to the circumference, 
leaving a narrower hand of healthy fibres in the position of the direct cerebellar tract. 
It extends over the whole area of the pyramidal tract. 
Lumhar Enlargement. —The degeneration is considerably less on the right side, arid 
on the left there is none to be seen. It extends fi’om near the posterior root exit a 
short distance forwards close to the circumference, and lies chiefly in the angle formed 
by the posterior cornu and the circumference, although it does not come quite close 
to the posterior cornu. 
Fourth Lumhar Nerve. —A small amount of degeneration can still be seen on the 
right side, in a similar position to that noted above, but not quite so near the root 
exit. 
Case 9,— No. 39 q/ First Series. 
Lesion 1.—Incomplete removal of the gyrus fornicatus and considerable injury to 
the middle of the marginal convolution (see ‘Phil. Trans.,’ B, 1888, Plate 7, fig. 39). 
Lesion 2,—Removal of that jDart of the limbic lobe which bends round the splenium 
of the corpus callosum. 
Lesion 3.—A fortnight later the posterior part of the hippocampal convolution was 
scooped away. 
Result. —Ansesthesia, and distinct muscular paresis of both right limbs. 
Tliis animal was killed about five months after the first operation. 
Degenerations Observed. 
Degeneration could be seen with the naked eye in the pyramidal bundles in the 
midbiain, pons, and medulla. After hardening, these parts look paler and smaller 
than those of the opposite side. 
In the spinal cord a patch of degeneration is to be seen occupying the crossed 
pyramidal tract as far down as the third lumbar nerve. 
Microscopically, degeneration can be seen, scattered in the pyramidal bundles of the 
midhrain and' pons of the left side. 
The medulla oblongata shows considerable degeneration and sclerosis (apparently 
more than in the jaons) in the left pyramid. 
Spinal Cord. Cervical Region. —There is a patch of degeneration in the crossed 
