1869.] 



of the Cerebral Hemispheres, 



53 



beneath the outer to the grey matter of the hippocampus and to the 

 splenium C. callosi, the outer fibres crossing over and reaching the upper 

 wall of the calcarine fissure, in which they pass to the posteroparietal 

 lobule and to the callosal gyrus. 



The anterior enlarged extremity of the uncinate gyrus, sometimes called 

 the uncinate lobule, is connected by bands of fibres with various parts ; it 

 is very firmly adherent to the subjacent structures, and when torn away 

 leaves a patch of exposed grey matter, which has been named the internal 

 grey nucleus. This is about in the same transverse line with the C. 

 albicans, a little to the outer side of the optic tract. 



By the removal of the uncinate lobule and gyrus fibres can be seen to 

 pass from the apex of the lobe forwards in the fasciculus uncinatus, back- 

 wards and inwards along the roof of the cornu to the thalamus, and inwards 

 to the grey nucleus. 



On further dissection, which will consist in tracing the fibres from the 

 apex backwards to various parts, and in removing little by little more of the 

 convolutions along the outer edge of the lobe, and in a careful investigation 

 of the parts about the calcarine fissure, the following appearances will be 

 presented. 



Along the axis of the lobe a longitudinal ridge with a slight convexity 

 outwards, prominent posteriorly, subsiding anteriorly. On its inner side, 

 from behind forwards, first the posterior cornu : next the outer wall of the 

 ventricle, where the cornua enter it ; this is formed by fibres curving 

 directly backwards into the ridge from the thalamus (also from crus and 

 corpus striatum, but more deeply), they are crossed transversely, however, 

 by a thin lamina of fibres from the under surface of the splenium, which 

 bend down from the roof of the ventricle and then curve forwards in the 

 ridge : next the posterior end of the thalamus, which bends forwards round 

 the crus, and gives oft forwards from a pointed extremity the optic tract 

 and laminae of fibres on the outer side of this, which run above the roof of 

 he cornu to the apex. Anteriorly this longitudinal ridge is continuous 

 with the fasciculus uncinatus, and on its inner side are the internal grey 

 nucleus, and more anteriorly the anterior perforated space between which 

 the anterior commissure dips forwards and inwards in its canal. 



On the outer side of the ridge fibres may be seen to start at the edge of 

 the lobe, run inwards to the ridge, and curve forwards in it, to leave it 

 again on its outer or inner side, or to pass with it to the fasciculus un- 

 cinatus. 



A bundle of fibres taken up from the posterior part of the ridge would 

 pass mainly to the thalamus ; but some would proceed forwards in the 

 ridge, and either turn outwards to some part of the inframarginal gyrus 

 or apex, or inwards to the internal grey nucleus, or behind it. Others 

 again go on in the F. uncinatus. 



Fibres taken from the middle part of the ridge, and traced backwards, 

 would mostly curve outwards to some part of the outer edge of the lobe, 



