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guised on the surface. Nevertheless the pyramid can be shown to be 

 continuous (in most mammals) with the parapyramidal area, including 

 not only its pars dorsalis (biventralis), as is taught in Human Anatomy, 

 but also its pars ventralis (tonsillaris), which, for reasons indicated 

 above, is usually regarded as an appendage, not of the pyramid, but 

 of the uvula. 



The postlunar fissure often (but by no means always) becomes 

 confluent with the corresponding fissure of the other side on the vermis. 

 The two postpteroid fissures become joined together in some cases, 

 but not nearly so often as the confluence of the postlunar fissures. 

 When both pairs of fissures cross the mesial plane they separate off 

 between them a strip called the folium cacuminis (Figs. 20 and 21). 

 In most mammals such a folium is of rare occurrence and it is not 

 present in the human brain nearly so often as is usually supposed. 

 The division of the suprapyramidal part of the vermis into three parts 

 (clivus, folium cacuminis and tuber valvulae) by the merely fortuitous 

 mesial extensions of the postlunate and postpteroid fissures is an in- 

 constant phenomenon so utterly devoid of any importance that it 

 might well be ignored in a scheme exemplifying the natural subdivi- 

 sion of the cerebellum (Fig. 1). 



I have already referred to the fortuitous confluence of the supra- 

 pyramidal and parafloccular fissures resulting in the formation of a 

 peculiar band, which I have called the copula pyramidis. In my ear- 

 lier memoirs on this subject (4, 6, 7 and 8) I have perhaps attached 

 undue importance to this really insignificant phenomenon, common 

 though it be in the Mammalia (Fig. 23). 



In the larger mammals the parafloccular fissure cuts into the alar 

 part of the middle lobe without becoming confluent with any impor- 

 tant fissure and the processes of secondary subdivision of the dorsal 

 limb of the paraflocculus and of the paravermis mutually influence one 

 another so that the two parts appear to consist of a long, worm-like 

 series of folia (Fig. 24), those of the paravermis forming a vertical 

 series of short horizontal folds, while the paraflocculus dorsalis con- 

 sists of a horizontal band of short vertical folia, which are brought 

 into serial arrangement with those of the paravermis by the oblique 

 position of the lowermost folia of the latter (Fig. 24). 



In the Apes the folia of the paravermis become progressively 

 longer from below upward (Fig. 25) and the rounded lowermost ex- 

 tremity of the resultant wedge-shaped mass is pushed downward be- 

 tween the uvula on the inner side and the paraflocculus on the outer 

 side. The most mesial folia of the latter become compressed and the 



