248 



THE ANATOMY OF THE HORSE. 



tions of the postero-siiperior and postero-inferior lobes, it is directed forwards at the base 

 of the brain (Plate 33, Hipp, con.), between the cms cerebri and the outer olfactory 

 tract. Finally, it terminates in the nipple-like eminence already noticed (Unc. con.). 



The whole of tliis great convolution corresponds very closely to the gyrus fornicatus of 

 human anatomy. Tlius, the part which turns round the genu and rests on the upper 

 surface of the corpus collosum is tlie caUosal convolution ; the part from the splenium 

 to the side of the cerebral crus is the hippocampal convolution; and the nipple-like 

 eminence is the uncinate convolution. 



The hippocami)al part of the gyrus fornicatus lias a small process which projects 

 forwards under the splenium ; and as the convolution curves forwards to emerge at the 

 side of tlie crus, it rests on the optic thalamus. By carefully raising the convolution from 

 the thalamus, there will be brouglit into view a fissure on the under asi)ect of the former. 

 This is the hippocampal Jigs are, and it projects tlie convolution into the lateral ventricle 

 as the hippocampus. Beyond this fissure tlie edge of the liippocamjius is seen, margined 

 by a thin-edged white band — tlie taenia hippocampi. The hippocampus and its taenia 

 here form the upper boundary of the r/rcat transverse fissure of the brain, by wliich the 

 pia mater of the hemisphere projects towards the interior of the cerebrum as the velum 

 intcrpositum. 



Fig. 31. 

 Corpus Callosum and Inner Face of the Cerebral Hemisphere. 



1, 2. Right and left cerebral hemispheres ; 3. Cerebellum ; C. Corpus callosum ; G. F. Gyrus 

 fornicatus (its callosal portion) ; C. M. Calloso-marginai fissure ; A. M. Antero-marginal convolu- 

 tion ; P. M. Posteromarginal convolution. 



Directions. — With a large, thin-bladed, sharp knife a horizontal slice 

 shonld be removed from the top of one or both cerebral hemispheres, 

 down to the level of the corpus callosiim. 



The hemisphere will now be seen to contain both grey and white 

 matter. In the centre of the hemisphere the white matter forms a large 

 mass connected with that of the opposite side by the corpus callosum. 

 At the surface the mass sends a white core into each convolution. The 



