X:XXX.J THE BRAIN'. 309 



b. The cerebellum covers the dorsal part of the 

 medulla oblongata. 



3. Tearing away as much of the pia mater as may- 

 be necessary, turn forward the cerebellum; the 

 posterior dorsal surface of the medulla oblongata 

 will be seen. Note 



a. The choroid plexuses of the fourth ventricle, 

 appearing on either side as a very vascular 

 projection of the pia mater; they lie immedi- 

 ately above the thin epithelial roof of the 

 ventricle; tear them away to expose the pos- 

 terior half of the fourth ventricle. 



b. The diverging posterior columns of the spinal 

 cord ; the fasciculus of GoU (cp. Lesson xxix. 

 § 4, d.) is continued on as the fasciculus 

 gracilis which forms the lateral wall of the 

 posterior part of the fourth ventricle ; late- 

 rally of this is seen the fasciculus cuneatus 

 continuous with the fasciculus cuneatus of 

 the cord (cp. Lesson xxix. § 4, d.). 



c. The oblique fibres running from the lateral 

 and anterior columns over the fasciculus 

 cuneatus and apparently blending with it; 

 the depression between the fasciculus gracilis 

 and the fasciculus cuneatus at the same time 

 disappearing, so that soon after the posterior 

 columns have diverged, a single rounded 

 eminence, the restiform body, is seen. 



d. Anteriorly the restiform bodies run into the 



