THE CEREBELLUM; 355 



Us medullary matter, six or seven principal fissures will be 

 seen, which, by penetrating to a considerable depth, divide the 

 cineritious portion into as many converging parts. In the in- 

 terior of these fissures there are much smaller ones, which pass 

 at right angles to them. On the surface or periphery of- the 

 cerebellum, in the intervals of the larger fissures, there are 

 many small ones, which, .though nearly horizontal, terminate 

 in each other by acute angles. 



The superior middle ridge of the cerebellum, from its shape 

 and position, is called, by Vicq. D'Azyr, Vermis Superior; the 

 anterior extremity of which, from its elevation, is the Monti- 

 culus Cerebelli. 



The middle inferior part of the cerebellum, which presents 

 the deep sulcus running longitudinally and forming the division 

 into hemispheres, has a long ridge occupying the sulcus. This 

 ridge is the Vermis Inferior of Vicq. D'Azyr, and is so con- 

 cealed by the adjacent portions of the hemispheres, that a 

 good view of it can be got only by removing the arachnoidea,. 

 pia mater and pushing the hemispheres aside. The transverse 

 fissures which penetrate it, and its general irregularity of sur- 

 face, will then be sufficiently distinct. The pia mater and 

 arachnoidea pass from the fore part of this body to the medulla 

 oblongata, and thus assist in forming the floor of the fourth 

 ventricle; which, without this reflection,, would be exposed. 

 The central part of the cerebellum as formed by the vermis 

 superior and by the vermis inferior, is the Fundamental For-, 

 tion of Gall and Spurzheim. 



At the root of the crus cerebelli are two small protuberances; 

 the one below it, in the erect position, is the Lobulus Amygda- 

 loides, and the other the Lobulus Nervi Pneumogastrici. 



The substance of the cerebellum is formed of cineritious- mat- 

 ter externally, and of medullary matter internally. When a 

 vertical section of it is made through the middle of one of its 

 hemispheres, the medullary neurine or matter puts. on the ap- 

 pearance of the thuya or arbor vitae, the roots and ramifications 

 of whose limbs,, even to their smallest extremities, are sur- 

 rounded by cineritious neurine or matter. In this view, there 

 appears to be more cineritious than white matter; but when a 

 horizontal cut is made from the periphery to the centre, paral-. 

 teLwith one of. the, deep concentric fissures,, the proportion , of; 



