836 PROFESSOR DAVID HEPBURN ON 
sulcus. The general arrangement of their surface suggested the possibility of the 
rhinal fissure being the foundation for the more elaborate fissures which characterise 
the orbital surface of the higher brains. 
The olfactory tract presented two distinct roots, separated from each other by a 
large area of the locus perforatus anticus. Of these, the mesial root came into view 
from the mesial surface in relation to the anterior end of the callosal gyrus of the 
limbic lobe. The lateral root emerged from under cover of the expanded end of 
the hippocampal gyrus. Closely adhering to the locus perforatus anticus, these 
roots converged and fused to form the olfactory tract, which occupied and moulded 
itself to the olfactory sulcus. 
In all my adult specimens the olfactory bulb had been broken off, so that I am 
not able to state its size, frontal relations, etc. ; but it was present in the young specimen 
as an ovoid enlargement 17 mm. in length and 6 mm. in breadth. It turned upwards 
upon the frontal surface of the hemisphere, to which it was closely applied. 
Behind the fissure of Sylvius, the basal surfaces of the occipito-temporal lobes were 
much more expanded in the lateral direction than is the case in the primate brain ; 
and, as a consequence, convolutions and sulci which are not found on this aspect in 
the human brain were visible in the brain under consideration. At the same time, 
it presented sulci which do not occur in a human brain, and therefore it is not easy 
to suggest a nomenclature for some of these sulci, nor to be quite certain that they 
should be accepted as providing boundaries between the occipital and temporal sections 
of the surface. . 
The dentate and collateral sulci, situated respectively on the mesial and lateral 
aspects of the hippocampal gyrus, were distinctly indicated. Towards the hinder end. 
the collateral sulcus was interrupted by a bridging gyrus, behind which the suleus 
corresponded to the general position of the emnentia collateralis in the lateral 
ventricle, as was afterwards revealed by dissection. Further, with the same part of 
the sulcus, 7.e. posterior to the annectant gyrus, just mentioned, other two well-marked 
sulci communicated. Of these, one was directed backwards towards the occipital end 
of the hemisphere, and the other diverged backwards and outwards towards the 
infero-lateral margin of the hemisphere in its occipital area. Thus a large segment 
of the oecipito-temporal surface, situated between the collateral sulcus and the infero- 
lateral margin of the hemisphere, was divided into three wedge-shaped gyri whose 
bases were directed towards the infero-lateral margin and whose apices converged 
towards the annectant gyrus above referred to. Indeed, this annectant gyrus connected 
the anterior and the middle of the three wedge-shaped gyri with the middle portion 
of the hippocampal gyrus. The posterior one of these three wedges presented a free 
apex, but the surfaces of each of the three showed indications of further subdivision 
by additional sulci. 
The callosal and hippocampal gyri were united to each other by a narrow gyrus 
which curved round behind the splenium of the corpus callosum and the crura cerebri. 
