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Show 70 MR. E. E. BEDDARD ON THE [Feb. 7, lateral parieto-occipital comes into viewT lying between the two forks of the Y. In the third brain, as will be seen from the drawings exhibited, the arrangement is practically the same; and one side of the brain belonging to the College of Surgeons (fig. 4) offered no differences. The other side of that brain is not so easy of explanation. It seems, however, to be, like the simplest case, complicated by an additional branch running towards the calcarine. Fig. 4. Brain of Gorilla belonging to Royal College of Surgeons. Vertical section. Ca. Calcarine fissure. M.p.o. Mesial parieto-occipital. CM. Calloso-marginal. The Simian fissure.-The Simian fissure, or " Affenspalte " as it is so constantly termed even by English writers, is only hidden by an operculum in one of the five brains at my disposal-that belonging to the Oxford University Museum. In the other brains it is traceable throughout its whole course upon the surface of the brain. This course is roughly obliquely transverse, the fissure bending backwards towards the middle line. It is joined by the intra-parietal fissure at about the middle of its extent. An exceptional state of affairs is seen in the brain represented in fig. 5. Here the fissure on both sides takes a bend forward and reaches the mesial surface, becoming continuous with a portion of the parieto-occipital. Fissure of Rolando.-Some stress has been laid upon the position of this fissure as marking the posterior boundary of the frontal lobes and as thus determining their relative size. Cunningham |
