CEREBELLUM. 405 



and most prominent in front, is a ridge or process, called 

 the superior vermiform process, or middle superior lobe, 

 which is related with the valve of Yieussens covers the 

 tubercula quadrigemina, and connects the lateral lobes. 

 One deep sulcus divides the superior surface of each hemi- 

 sphere into an anterior and posterior lobe. The anterior 

 stretches as far forward as the anterior notch, and is con- 

 nected to its fellow by the transverse fibres of the superior 

 vermiform process. The posterior extends to the convex 

 border behind, and is also connected by transverse fibres. 

 Both of these lobes are again divisible into smaller parts 

 consisting of lobules, and laminae, or leaflets. 



The inferior surface, like the superior, is also marked by 

 concentric lines, furrows, or sulci. It is divided from the 

 superior by a horizontal fissure, which is deep and extends 

 round the circumference of both hemispheres, as far for- 

 ward as the pons. This fissure is lined by pia mater, and 

 has its floor covered with medullary matter, which can be 

 traced into the crura cerebelli. 



When the membranes are removed, the furrows of both 

 surfaces are found to differ from those of the cerebrum, in 

 having their bases closed with the white neurine, instead 

 of the gray. 



The lower surface which is very convex, has been divided 

 by anatomists into as many as five lobes, distinguished as 

 follows : The anterior and internal, called also the amyg- 

 daloid, or tonsillitic; the anterior external, or the digastric; 

 the posterior, or semilunar; the pneumogastric lobe, or floc- 

 culus ; the anterior inferior, and the middle lobe, or gracilis. 

 The names of these several lobes define pretty well their 

 location. The tonsil, or anterior internal lobe, is covered 

 by the medulla oblongata, and projects into the fourth ven- 

 tricle, at its sides and posterior part. 



The pneumogastric lobe is near the origin of the eighth 

 pair of nerves hence its name. 



In the median fissure, on the inferior surface, is seen a 

 pyramidal projection, divided into rings transversely, and 

 called the inferior vermiform process, which unites the 



