MYCETES SENICULUS 



207 



occipital lobe of the hemisphere itself. This concavity is deepest in the midline 

 where it appears as the postsplenial fossa for the accommodation of the 

 protuberant superior vermis of the cerebellum. 



FIG. 114. RIGHT LATERAL SURFACE OF BRAIN, MVCETES SENICULUS. 



[Actual Length, 52 mm.] 



Key to Diagram, ram. post., Ramus Posterior of .Superior Temporal Sulcus; SULC. occip. lat., Sulcus 



Occipitalis Lateralis; SULC. precnt. inf.. Sulcus Precentralis Inferior; sulc. retrc. inf.. Sulcus Retro- 



centralis Inferior. 



THE CEREBELLUM 



In the cerebellum, certain advances are prominent, consequent primarily 

 upon the pronounced expansion of the lateral lobes. The tentorial surface is 

 entirely overhung by the occipital lobes. It is gabled from its lateral extrem- 

 ity toward the median ridge-pole formed by the vermis cerebelh. The inter- 

 foHal sulci pass without interruption from the vermis to the lateral lobes. 

 On the occipital surface the expansion of the hemispheres of the cerebelhim 

 is an even more conspicuous feature. The inferior vermis still occupies a 

 prominent position on this surface but its proportions are reduced to about 

 a sixth of the entire expanse of this region. In the lower forms the vermis 

 constitutes a third of this area. Two deep paramedian sulci interrupt the 

 passage of the interfolial fissures from the vermis to the lateral lobes. A 

 feature of much importance in connection with the petroso-ventricular sur- 

 face of the cerebellum in mycetes is the extreme development of the flocculus. 



