844 PROFESSOR DAVID HEPBURN ON 
IV. Tae Hinp Brain. 
(a) Lhe Cerebellum.—As is usual among carnivores, the cerebellum possessed a 
relatively large vermis in proportion to the size of the hemispheres. When examined 
in longitudinal section (fig. 2), the relation of the vermis to the 4th ventricle and the 
other constituents of the hind brain presented a great similarity to the corresponding 
appearances seen in the human brain.* 
The central lobe rested upon the superior medullary velum and possessed a lingula. 
The culmen and declive were similarly recognisable, as were also the nodule and the 
tonsil upon the inferior or ventricular aspect of the vermis.. The pyramid, the tuber 
valvule, and the foliwm cacuminis were not so easily determined in the brain of the seal 
as they are in the brain of man, because, whereas in the latter these structures are turned 
towards the floor of the skull, in the former they were turned more towards the hinder 
end of the vermis. 
The hemispheres were small and practically impossible of the detailed subdivision 
which is customary in the descriptions of the human cerebellum, and any attempt to do 
so would introduce unnecessary risks of error. In a measure, the points of entrance of 
the middle cerebellar peduncles from the pons Varolii provided a guide to what might 
be regarded as the dorsal and ventral portions of the cerebellum. On this assumption, 
the biventral lobe and the tonsil projected laterally some distance beyond any other part 
of the hemisphere, while the flocculus formed a mass of considerable size which over- 
lapped the middle peduncle from behind. If we accept the position of the middle 
cerebellar peduncle as a sufficiently reliable guide from which to continue the great 
horizontal fissure by means of which the upper and lower aspects of the human 
hemisphere are located, then in the brain of this seal all that remained of each hemi- 
sphere, in addition to the objects already mentioned, occupied the same aspect and was 
directed towards the tantorium. Nevertheless, it was divided into two clearly defined 
areas by a fissure which commenced at the point where the middle peduncle entered 
from the pons Varoli. If, now, we name these lobes respectively superior-anterior and 
superior-posterior, then all the parts of the cerebellum of the seal have been accounted 
for. It may be noted that the part which I have just named the superior-anterior lobe 
is reduced to a single folium in relation to the vermis, and it is this folium which is 
named the folium cacuminis (fig. 2). 
Compared with the human cerebellum, it would appear that whereas in the seal the 
vermis and its subordinate parts are well developed, and the flocculus, biventral lobe, 
and tonsil are produced on a large scale, the remainder of the hemisphere is much 
reduced in proportion. On the other hand, in man the hemisphere proper has become 
much expanded and thickened, with corresponding reduction in the size of the flocculus, 
the biventral lobe, and the tonsil. In fact, a theoretical enlargement of the superior- 
anterior and superior-posterior lobes of the hemisphere of the seal, accompanied by their 
* Teat-Book of Anatomy, edited by CUNNINGHAM, 8rd ed., p. 512. 
