44 



(6) The infundibulum, the downward continuation of the third 



ventricle. 



(7) The corpus albicans, posterior to the infundibulum. 



(d) The corpora quadrigemina, now fully exposed. 



(e) The pons Varolii. 



(/) The fourth ventricle, its posterior triangular portion or calamus 

 scriptorius, and the aqueduct of Sylvius (or iter) underneath 

 the corpora quadrigemina, connecting its anterior extremity with 

 the third ventricle. 



(g) The roof of the fourth ventricle, and the cerebellum. Make a 

 longitudinal section of the cerebellum, and observe its arborescent 

 structure. 



