654 Jourjial of Comparative Neurology and Psychology. 



of the lenticular nucleus to the end of the posterior horn of the 

 lateral ventricle. About the anterior third of the posterior horn, and 

 still further back, there is a great intercrossing with the fibers of the 

 optic radiation, tapetum, and others. Indeed, throughout the whole 

 posterior end there is, to some extent, intercrossing of fibers. 



It is desirable to keep in mind that the structures constituting the 

 bed enter into the formation of the roof of the posterior and descend- 

 ing horns of the lateral ventricle with which they are thus in close 

 relation. The hippocampus major, being in floor of the descending 

 horn, has a close relation to the bed. The cut edge of the hippo- 

 campus major is shown in Fig. 3. Winding round and embrac- 

 ing the whole of the posterior part of these structures are many 

 fibers of the fasciculus oocipito-frontalis inferior, which are shown 

 so well in Figs. 3 and 4 (F. 0. f. i.^). The choroid plexus, not 

 shown in Fig. 3 owing to the view-point from which it was taken, 

 but present in the dissection from which the photograph was taken, 

 lies above the hippocampus major (Fig. 3) in close relation with the 

 fibers as they begin to wind under the lateral ventricle from the ex- 

 ternal aspect. 



Having described the bed on which the fasciculus occipito-frontalis 

 inferior lies, it now remains for me to point out the internal, external, 

 and superior relations abo\it the island of Reil, and the external 

 relations throughout the remainder of its course. It has been men- 

 tioned that the lower fibers of the fasciculus were partly hidden by 

 the uncinate fasciculus (see Fig. 2). The gray matter of the 

 cortex of the island of Eeil, and the extreme capsule lie on the 

 external side of it. The base of the claustrum rested, as it were, on 

 this part of the fasciculus occipito-frontalis inferior, in the shadow 

 (Fig. 2) immediately above the bundle. Most of the fibers of the 

 external capsule begin about this place, arising as they do from the 

 claustrum and basal grey. The deepest layer of the external capsule 

 is very thin in this place and begins lower down under the fasciculus, 

 separating it from the lenticular nucleus throughout the region of 

 the island of Eeil. This layer and the rest of the external capsule 

 has. been removed in Fig. 3, to show the close relationship of the 

 fasciculus to the lenticular nucleus. As regards its relations with 



